NCD980840409_19910705_Charles Macon Lagoon & Drum_FRBCERCLA FS_Revised Feasibility Study and Risk Assessment-OCR

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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION IV
345 COURTLAND STREET. N.E .
. ATLANTA, GEORGIA 30365
Ms. Charlotte V. Jesneck
North Carolina Department of Environmental,
Health and Natural Resources
401 Oberlin Road
Raleigh, North Carolina 27605
RE: Macon-Dockery CERCLA Site Revised Feasibility Study (FS) and Risk
Assessment {RA)
Dear Ms. Jesneck:
Enclosed is a copy of the Revised FS Report and Revised RA for the
above referenced site. These reports were submitted by the
Responsible Parties contractor, Sirrine Environmental Consultants.
Please review these document. All review comments should be
submitted to me no later than July 19, 1991.
If you have any questions please call Curt Fehn at 404/347-7791.
Thank you for your prompt attention to this matter.
11-iJ n . Nohrstedt r 1Remedial Project Manager
Enclosures
cc: Ms. Lee Crosby, NCDEHNR
Mr. William L. Meyer, NCDEHNR
Printed on Recycled Paper
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RESPONSE TO EPA REGION IV AND STATE OF NORTH CAROLINA
COMMENTS ON THE DRAFT FEASIBILITY STUDY
RESPONSES TO FS COMMENTS
As requested in the EPA letter of June 5, 1991, the following describes how each EPA
comment (June 5 and June 10, 1991) was addressed in the July 5, 1991 Feasibility Study
for the Macon/Dockery Site.
Responses to June 5. 1991 EPA Comments About the FS
COMMENT 1
The text has been changed as requested to more accurately reflect the Site
hydrogeology (pages 2-4 through 2-7). The saprolite, transition zone, and bedrock
are described as lithographic units and not as distinct aquifers.
COMMENT 2·
lnorganics data from other locations were used for comparative reasons. Data from
the Savannah River Site were used because extensive, peer-reviewed research has
been conducted on similar soils as those found at the Macon/Dockery Site (e.g.,
Orangeburg series). The clarification was made on page 2-11.
COMMENT 3
There is a high confidence level that the TCL constituents found in the surface soil
samples at the Dockery Site are laboratory contaminants, as described on
pages 2-11 and 2-12.
Responses to FS Comments 1 July 5, 1991
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COMMENT 4
The comment concerning TAL constituents has been clarified. This comment referred.
to vadose zone {e.g., boring SB12-01-1) samples which are addressed in Section
2.2.2 Vadose Zone Soils {page 2-12).
COMMENT 5
Surface water and sediment sample locations (page 2-17) are clearly shown in the
Remedial Investigation (RI) report Figure 3-8. Control samples are now designated
on pages 2-14 through 2-17 as requested.
COMMENT 6
Section 2.2.3.3 has been modified to include the statement "Contaminant transport
modeling indicates that there may be a ground water plume extending downgradient
from the vicinity of MW-15 for several hundred feet."
COMMENT 7
Impact of the Site on Solomon's Creek is minimal, as stated on page 2-17.
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COMMENT 8
Future residential use of the Site was considered in the Risk Assessment. Vadose
zone remediation levels consider the results of the Risk Assessment and of potential
impact on the Site ground water, as discussed in Section 3.2.3.3, and in Tables 3.4
through 3.8. Ground-water remediation levels (Table 3.3) were used for comparing
the potential impact of the vadose zone on the ground water.
Responses to FS Comments 2 July 5, 1991
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COMMENT 9
Wetlands have been included in the text as a potential location-specific ARAR {page
:µ).
COMMENT 10
MCLs are an ARAR (page 3-5).
COMMENT 11
The text has been clarified on page 3-5 concerning MCLs as an ARAR. MCLs are
an appropriate and relevant remediation standard for the ground water at the
Macon/Dockery Site (40 CFR 300.121(d)(2)(A)).
COMMENT 12
Please refer to the response to Comment 57.
COMMENT 13
The discussion about the practical limitations of achieving MCLs has been edited and
reduced in length. The revised text is in Section 4.
COMMENT 14
MCLs at Potential Points of Exposure, found in Section 3.2.3.1 has been deleted.
References to ACLs have been eliminated with the exception of the following passage
on pages 3-5 and 3-6: 'Site data are not sufficient at this time to establish the
Responses to FS Comments 3 July 5, 1991
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appropriateness of Alternate Concentration Limits (ACLs; 40 CFR Part 300) for ground-
water remediation levels. Establishment of ACLs for Site ground water may be
appropriate after additional ground-water monitoring. ACLs will not be considered
in this FS."
COMMENT 15
Comments about ground-water are addressed in Appendix C (not in Appendix E as
the comment states).
COMMENT 16
The text has been changed to include North Carolina Groundwater Standards as an
ARAR. This replaces the text in the April 22, 1991 version of the FS. The revised
discussion is on page 3-5 and in Tables 3.2 and 3.3 .
COMMENT 17
Alternate Concentration Limits (ACLsl. found in Section 3.2.3.1 has been deleted.
Therefore, no discussion is needed on the relative impact of the chemical constituents
on the ground water prior to reaching Solomons Creek.
COMMENT 18
Please refer to the response to Comment 59 for a discussion of dilution calculations.
Calculations of Mure contaminant concentrations in Solomons Creek are retained in
Appendix C for use in discussion of the No-Action remediation alternative. Alternate
Concentration Limits (ACLs), formerly found in Section 3.2.3.1 has been deleted.
Responses to FS Comments 4 July 5, 1991
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COMMENT 19
This comment refers to the vadose zone modeling (Appendix E) and is addressed In
Appendix E.
COMMENT 20
As requested, Lagoon 1 o and Lagoon 11 were modeled separately using the VIP
model. Results are provided in Table 3.5 (Lagoon 10) and Table 3.6 (Lagoon 11 ).
The EPA comment concerning the effect of lower concentrations of a chemical nearer
to the ground water surface (e.g., 10 feet) was addressed by modeling
benzo(a)pyrene and phenanthrene (Table 3.6) since these compounds had relatively
high concentrations nearer the ground water surface .
COMMENT 21
The text has been changed in Section 3.2.3.3 to clarify the potential effect of vadose
metals on the ground water at the Site. Comparisons to the March 1991 ground-
water data have not been made.
COMMENT 22
Additional VIP modeling was conducted as requested in various comments. This
modeling has shown that only Lagoon 7 at the Upper Macon Site has the potential
to impact Site ground water (Table 3.4).
Responses to FS Comments 5 July 5, 1991
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COMMENT 23
Refer to the response to Comment 57.
COMMENT 24
The Wetland ARAR will be retained (page 3-4 and Table 3.1).
COMMENT 25
ACLs are not considered ARARs for this FS. Consequently, this comment has been
addressed by removing text that states that ACLs are ARARs.
COMMENT 26
Table 3.0 is a greatly summarized version of the Risk Assessment. Since the Risk
Assessment is a companion document to the FS, it should be consulted for detailed
information, rather than duplication of efforts in the. FS.
COMMENT 27
Potential remediation levels include MCLs and North Carolina Groundwater Standards
(Table 3.3). All references to URTH levels and ACLs as potential remediation levels
have been removed.
COMMENT 28
Tables 3.6 and 3.8 have been deleted.
Responses to FS Comments 6 July 5, 1991
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COMMENT 29
Clarification has been provided concerning the immobility of metals. Maximum vadose
zone metal concentrations were modeled to predict the maximum migration and the
maximum concentration found in the pore water at that migration depth. As seen In
Tables 3.4 through 3.8, metals are estimated to migrate from 3 to 10 feet In 50 years.
However, there is no· estimated adverse impact to ground water, including nickel.
Selenium, a non-metal, is estimated to migrate about 14 feet but not adversely impact
ground water.
COMMENT 30
The lists of technologies presented in Tables 4.1 and 4.2 provide the basis for the
development of remedial alternatives. Since it is required by the NCP, no action has
been included for both source and ground water control for completeness. In
accordance with Response 31, ACLs have deleted as part of no action for ground
water recovery.
COMMENT 31
The No Action -Alternate Concentration Limits alternative has been deleted from
Section 4.3.1.
COMMENT 32
The reference has been added to the text.
Responses to FS Comments 7 July 5, 1991
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COMMENT 33
Precipitation is primarily effective for dissolved metals. From the sampling results
presented in Appendix B, metals in site ground water are related to particulate matter
not dissolved species. Filtration is a demonstrated, readily maintained technology for
the removal of particulate matter. As discussed in Section 6.2.2 of the draft FS,
filtration alone should be adequate to achieve anticipated surface water discharge
levels. Coagulation (or co-precipitation) is another technology for the removal of
particulate metals. Coagulation will be added to the retained list of technologies to
offer more comprehensive control of metals in ground water, if necessary.
COMMENT 34
The comment is noted. Actual design and placement of the ground water extraction
and infiltration gallery systems would be conducted during Remedial Design.
Responses to FS Comments 8 July 5, 1991
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COMMENT 35
LDRs are a potential action-specific ARAR and their evaluation is presented in the
detailed analysis of alternatives. Please see Section 6.3.4 for the evaluation of LDRs
with respect to bioremediation of materials in Lagoon 10 (Alternative SC-4).
COMMENT 36
While it would involve significantly greater costs than equally effective in situ options,
the excavation and direct treatment of Lagoon 7 materials will be evaluated. Based
on an area of 50 feet by 25 feet and a depth of 27 feet, the volume of materials in
Lagoon 7 is approximately 1300 cubic yards.
COMMENTS 37
Soil washing has been most effective (although not entirely effective) for sandy soils
containing fairly soluble contaminants (e.g. BTEX compounds). Site soils have an
appreciable silt and clay content (greater than 50 percent) and site contaminants have
moderate to low solubilities (e.g., PCE, PNAs). Either of those factors would limit the
effectiveness of soil washing and the combination makes the implementation of soil
washing impracticable for the site. In addition, soil washing was determined to be
ineffective at a Superfund site in Michigan for compounds with similar or greater
solubilities than at the Macon-Dockery site (EPA, 1990). Based on site-specific factors
and relevant experience at similar sites, the preponderance of technical evidence
indicates that soil washing would not be effective at the site. Please see revised text.
Responses to FS Comments 9 July 5, 1991
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COMMENT 38
Per Comment 36, the materials in Lagoon 7 have been considered for potential
excavation. The combined volume of materials in Lagoons 7 and 1 O is approximately
2,300 cubic yards. This volume is insufficient to warrant mobilization of a
transportable incinerator, as clarified in the revised text. This volume could potentially
be handled at an off-site permitted incinerator. The cost for off-site incineration of
Lagoon 7 materials has been included in the screening of potential alternatives. (Table
5.2}.
COMMENT 39
Proposed sites for L TIS in Region JV include the Aberdeen Pesticide Dumps Site
(100,000+ cubic yards) and the Sangano Weston PCB Sites (50,000+ cubic yards).
Conversations with potential vendors confirmed that the limited volume of site
materials (2300 CY} is insufficient for mobilization of an L TIS system. Please see
revised text. More significantly, the boiling points of site PNAs exceed the operating
temperature of an L TIS system and the process would not be technically effective (as
discussed in the text}.
COMMENT 40
SVE would be applied only at Lagoon 7. Based on the VIP modeling, the only
compound in Lagoon 7 with the potential to exceed groundwater ARARs is PCE.
While other compounds may be removed through SVE, their removal is not required
to satisfy the site remedial action objectives (Section 3.2.3.3).
Responses to FS Comments 10 July 5, 1991
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COMMENT 41
The evaluation of no action and capping with respect to the criteria of reduction of
toxicity, mobility and volume and long-term effectiveness is presented in Section 6,
Detailed Analysis of Alternatives.
COMMENTS 42
The text has been revised to state that: "On-site landfilling would offer comparable
effectiveness to capping with respect to denial of infiltration and potential human
exposure but at a significantly higher cost."
COMMENT 43
The table has been revised to be consistent with the text .
COMMENT 44
As stated in response to comments 20 and 22, additional VIP modeling has shown
that only Lagoon 7 at the Upper Macon Site has the potential to adversely impact Site
ground water. This takes into account less contaminated soil that is closer to the
ground-water table.
COMMENT 45
The document Guidance for Conducting Remedial Investigations and Feasibility
Studies Under CERCLA (EPA, 1988) describes a true no action alternative (GWC-1A)
and a limited action alternative involving ground water monitoring (GWC-1B).
Differences between these two distinct alternatives are further clarified in Response
50 .
Responses to FS Comments 11 July 5, 1991
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COMMENTS 46
Site ground water data is not sufficient at this time to support the application of ACLs.
Alternative GWC-2 will therefore be deleted from the FS document.
COMMENTS 47
Treated ground water would meet the required limits for discharge to a surface water
or an infiltration gallery, through filtration and/or coagulation if necessary. The
evaluation of ground water remediation in the FS was based on discharge to
Solomons Creek. The actual point of discharge would be determined during Remedial
Design, should ground water remediation be selected for the site. Please see revised
text.
Construction costs for an infiltration gallery that could accept 40 gpm at a
conservative application rate of 0.5 gpd/fl2 would be approximately $ 93,000. This cost
has been provided in the FS document as a reference for comparison with surface
water discharge (Section 6).
COMMENT 48
To be conservative, the present worth costs for ground water remediation include
coagulation and filtration for metals removal. Actual treatment requirements would be
determined during Remedial Design. Please see Responses 33 and 47.
COMMENT 49
Soil vapor extraction alone can achieve the remedial action objectives for Lagoon 7.
Please see Response 40. The title will be revised to more completely describe the
alternative.
Responses to FS Comments 12 July 5, 1991
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COMMENT 50
References to deed restrictions will be removed from Alternative GWC-1A.
COMMENT 51
The discussion of ACLs in the final FS document will be limited to their evaluation in
Section 3.2.3.1.
COMMENT 52
The paragraph will be deleted from the final FS document.
COMMENT 53
References to Alternative GWC-2 (MCLs at the Property Line) will be removed from
Sections 5 and 6 of the final FS document.
COMMENT 54
Please see response to Comment 53.
COMMENT 55
The Remedial Investigation (RI) report is also a companion document to the FS (e.g.,
RI/FS). To avoid unnecessary duplication of efforts, data from the RI are summarized
in Appendix A. More detailed information than provided in Appendix A (e.g., sample
locations and depths) can be easily found in the RI report.
Responses to FS Comments 13 July 5, 1991
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COMMENT 56
The FS has been revised throughout to state that remediation of Site ground water
will be at the source and not at the property boundary (i.e., no ACL.s). Remediation
levels are provided in Table 3.3. References to ACL.s as remediation levels have been
deleted.
COMMENT 57
Values of Kd available in the literature have a broad range (as much as five orders
of magnitude) due to variations in soil type. Values of Kd measured in soil similar to
that found at the Macon/Dockery Site were necessary to accurately estimate
contaminant movement. Because of the similarity between the Macon/Dockery Site
soil series and Savannah River Site soil series (e.g. Orangeburg series), Kd values
measured for the soil series at the Savannah River Site were considered the best
available data and were used in contaminant-transport modeling in both the saturated
and unsaturated zones.
Simplifying assumptions inherent in analytical modeling using CONMIG are as follows:
, the model assumes ground-water flow can be described as steady state;
, the model does not take into account specific hydraulic boundary
conditions;
, the model assumes the aquifer is homogeneous with respect to hydraulic
parameters;
, the model assumes that residual chemicals completely mix over the entire
thickness of the aquifer;
Responses to FS Comments 14 July 5, 1991
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• the model does not simulate density differences between residual
chemicals and ground water, chemical speciation or biodegradation.
The degree of characterization of an aquifer determines the type of model used
to simulate the aquifer. Given the existing ground water analytical data base for
the Macon/Dockery site, an analytical model was considered adequate for
representing the aquifer and estimating contaminant flow at the site.
The analytical model was calibrated to the extent possible based on contaminant
concentrations observed in the RI. To determine source concentrations,
simulated concentration distributions were calibrated against concentrations
measured in monitoring wells. Verification of this model was not possible given
the existing data base. During Remedial Design, a more-refined model would
be used, and data available at that time will allow for more intensive calibration
and verification.
COMMENT 58
The approach used in the RI/FS was presented in a work plan (Project Operations
Plan Macon/Dockery Site Rl/FS, Sirrine, June 1989) which was negotiated with and
approved by EPA. Additional monitoring would be conducted during Remedial Design
to confirm the actual extent of contamination and refine the placement of extraction
wells.
Responses to FS Comments 15 July 5, 1991
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COMMENT 59
Phase II Modeling was used to determine maximum concentrations of contaminant
discharging into Solomons Creek after migration to this point of discharge. These
concentrations were reduced mathematically to determine the diluted concentration
of contaminants after mixing.
Surface water in Solomon's Creek prior to mixing is assumed to be pristine for
modeling purposes. Surface-water samples collected and analyzed during the
Remedial Investigation indicate that surface water flowing to the Macon/Dockery Site
is below detection limits in concentrations of tetrachloroethene, 1, 1, 1,-trichloroethane,
trichloroethane, vinyl chloride, chromium, cadmium and nickel and, therefore, can be
considered pristine with respect to those contaminants.
We see no reason to assume detectable concentrations of these constituents will be
present in the surface water in the future under ambient conditions .
An aerial photograph taken January 18, 1990 was used to delineate an area of
standing water in Solomon's Creek. A water depth of 3.5 feet was assumed to
calculate a volume of water present (approximately 25 million gallons). Assuming one-
tenth of this standing water in Solomon's Creek is available for mixing, and using a
calculated specific discharge of ground water to the creek, a dilution factor of 9.6 x
10-2 was calculated for ground water mixing with surface water. Calculated Mure
contaminant concentrations in Solomon's Creek are discussed in the No-Action
remediation alternative. All references to ACLs have been removed from Appendix
C.
Responses to FS Comments 16 July 5, 1991
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COMMENT 60
As ACL.s have been removed from consideration at the Macon/Dockery Site, Phase
Ill Modeling: Concentrations at Downgradient Boundaries formerly in Appendix C has
been deleted.
COMMENT 61
Evaluation of potential extraction systems using an analytical model is appropriate to
allow comparative evaluation of alternatives during the FS. A more intensive modeling
approach would be used during subsequent design efforts.
COMMENT 62
Sampling distances for soil borings were from 15-17 and 25-27 feet below ground
surface, for a sampling distance of two feet. This distance was doubled (i.e., four
feet) for use in the VIP modeling. Assuming a maximum contaminated thickness of
4 feet overestimates the impact of vadose zone contaminants on the ground water
since this decreases the estimated distance to ground water by one foot. For
example, if the maximum contamination were found at the 25-27 foot depth, then the
center of that zone is at 26 feet. The maximum assumed contamination zone (four
feet) would also be centered at 26 feet and extend downward to 28 feet. Twenty
eight feet is actually one foot closer to the ground water table and hence is a more
conservative assumption.
COMMENT 63
The references in Table E.2 have been corrected and added to the master reference
list for the FS at the end on Section 7. The text in Appendix E has been edited to
make the correct references to tables.
Responses to FS Comments 17 July 5, 1991
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COMMENT 64
Distances to ground water are provided in Tables 3.4 through 3.8. Table E.2 provides
Koc, Kd, and half-life information.
COMMENT 65
As stated, Kd values from similar soils found at the Savannah River Site (SAS) In
Aiken, South Carolina were used instead of generic text book values. The average
values reported by Dragun (1988) are generally higher than the SAS values used for
VIP modeling. As such, the SRS values are more conservative (i.e., lower Kd value).
COMMENT 66
Justification is provided in Appendix E as to why constant soil parameter values were
assumed for the Site.
COMMENT 67
More information is provided in Appendix E concerning the derivation of Q(I) and
Q(gw). The mixing depth is calculated based on the VHS Model (50 Federal Register
229: 48896, November 27, 1985). The model recommends a vertical dispersivity of
0.2 meters (0.656 feet) to simulate a reasonable worst-case scenario. A dispersivity
of 0.656 feet is typical for a silty loam. The predominantly silt/sandy aquifer found at
the Macon/Dockery Site would have a slightly higher dispersivity than a silty loam soil.
Consequently, a vertical dispersivity of 0. 7 feet (az; Table E.3) was used for calculating
the mixing zone.
Responses to FS Comments 18 July 5, 1991
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Responses to June 10. 1991 EPA Comments About the FS
COMMENT 1
Remediation goals have been clarified in Section 3. They consider both health-based
criteria and ARARs.
COMMENT 2
As the EPA comment states, comparison of Site soil arsenic levels to background
levels does justify not remediating the soil arsenic. This is further discussed and
clarified in Section 3.
COMMENT 3
The target risk for isophorone has been changed to 10E-5. The resulting PPLV Is
70 ug/1 (Appendix D and Tables 3.2 and 3.3).
COMMENT 4
The remediation level for lead has been changed to 15 ug/I, the Superfund action
level (Table 3.3).
Responses to FS Comments 19 July 5, 1991
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I~11 SIRRINE Ill! ENVIRONMENTAL > Ill! CON SU LT ANTS
Post Office Box 24000
Greenville, South Carolina 29616
[phone]
July 3, 1991
Mr. John S. Nahrstedt
Remedial Project Manager
NSMS/SFB/WMD
U. S. Environmental Protection Agency
345 Courtland Avenue, NE
Atlanta, Georgia 30365
Re: Macon/Dockery Site RI/FS
Risk Assessment and Feasibility Study Reports
Richmond County, North Carolina
Dear Steve:
VIA FEDERAL EXPRESS
Please find enclosed five copies of the Risk Assessment and Feasibility Study Reports for the
Macon/Dockery stte. As we stated wtth the Draft RA and FS reports transmittal, we are only
providing replacements to the reports where changes were required. Detailed instructions are
provided for making replacements and additions to each of the reports.
We have also enclosed responses to the Agency comments on the draft reports. Changes made
specifically to address agency review comments were identified in the response to comments for
the respective report. However, for the Risk Assessment, numerous changes to the text and
tables were generated as a result of modifications to chemical specific permeability constants,
application of additional toxicity factors, and changes in exposure frequencies and durations. It was
not feasible to identify where all of these changes were made in the Response to Comments.
If you have any questions or need additional information please feel free to contact me at (803)
234-3068, Mr. David L. Jones at [phone], or Mr. Christopher A. Keele at [phone].
Sincerely,
~c.sf2!)~
Patrick A. Shirte~-~
Project Manager
Enclosures
c: Mr. Christopher A. Keele, Morrison & Foerster
Mr. Tom Daggett, WHA&D
Mr. Thomas N. Barefoot, SABDM&J
Mr. David L. Jones, Clarll Equipment
Mr. William T. Gallagher, Crown Corl\ & Seal
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Following are instructions for updating the April 22, 1991 version
of the Macon/Dockery Feasibility Study (FS) to the July 5, 1991
version. Keep means no change for the noted item. Remove means to
take out the noted item with no replacement. Replace means take
out the noted item and replace it with the updated (July 5, 1991)
version.
Item
Notebook, Cover, and Binder
Section and Appendix Dividers
Flysheet
Table of Contents
List of Acronyms and
Abbreviations
Section 1 text
Figure 1.1
Section 2 text
Figures 2.1 and 2.2
Tables 2.1 through 2.3
Section 3 text
Table 3.0
Table 3.1
Tables 3.2 through 3.12
Section 4 text
Tables 4.1 -4.4
Section 5 text
Figures 5.1 and 5.2
Tables 5.1 through 5.3
Section 6 text
Figure 6.1
Table 6.1
Section 7 text
Table 7.1
References
Appendix A
Appendix B
Appendix C text and figures
Appendix C Tables C.1 & C.2
Appendix C Table C.3
Appendix C Tables C.4 -C.6
Appendix C references
Appendix D -all
Appendix E text and tables
Appendix E Figure E.l
Appendix F.1
Appendix F.2
Appendix G
Action to Update the FS
Keep
Keep
Replace
Replace
Keep
Replace
Keep
Replace
Keep
Keep
Replace
Replace
Keep
Remove Tables 3. 2 - 3 .12 and replace
with Tables 3.2 -3.8
Replace
Replace with Tables 4.1 -4.4
Replace
Keep
Replace with Tables 5.1 -5.3
Replace
Replace
Keep
Replace
Replace
Replace
Keep
Keep
Replace text and Figures C.1 & C.2
Replace Tables C.1 and C.2
Keep
Remove Tables C.4 -C.6 and
replace with Table C.4
Remove -all references are now at
the end of the FS text (Section 7)
Replace
Replace text & Tables E.1 -E.3
Keep
Insert numerically by module number
Replace
Keep
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Following are Instructions for updating the April 22, 1991 version of the Macon/Dockery Risk
Assessment (RA) to the July 5, 1991 version. Keep means that no change occurred for this
Item. Replace means remove the noted item and replace it with the updated (July 5, 1991)
,1erslon.
Notebook, Cover and Binder
Section and Appendix Dividers
Flysheet
Table of Contents
List of Figures
Section 1.0 Text
Section 2.0 Text
Tables 2.1 through 2.12
Section 3.0 Text
Tables 3.1 through 3.120
Section 4.0 Text
Tables 4.1 through 4.14
Section 5.0
Table 5.1 Text
Section 6.0 Text
Section 7.0 Text
References
Appendix A
Appendix B
Appendix C
Appendix C References
Action to Update the RA
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FINAL
FEASIBILITY STUDY
MACON/DOCKERY SITE
RICHMOND COUNTY, NORTH CAROLINA
JULY 1991
SIRRINE PROJECT NUMBER G-9168.76
SIRRINE ENVIRONMENTAL CONSULTANTS
GREENVILLE, SOUTH CAROLINA
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TABLE OF CONTENTS
1.0 INTRODUCTION
1.1 Objectives
1.2 Report Format
2.0 SUMMARY OF REMEDIAL INVESTIGATION
2.1 Site Characterization
2.1.1 Location
2.1.2 Physiography
2.1.3 Utilities
2.1.4 Geology
2.1.5 Hydrogeology
2.1.5.1 Perched Water Table
2.1.5.2 Shallow Saprolite Unit
2.1.5.3 Transition Zone
2.1.5.4 Ground-Water Velocity
2.1.5.5 Bedrock Unit
2.1.5.6 Vertical Flow Patterns
2.1.6 Meteorology
2.1.7 History
2.1.8 Demography and Land Use
2.2 Identified Chemicals
2.2.1 Surface Soils
2.2.2 Vadose Zone Soils
2.2.3 Ground Water
2.2.3.1 Upper Macon Site
2.2.3.2 Lower Macon Site
2.2.3.3 Upper Dockery Site
2.2.3.4 Lower Dockery Site
2.2.3.5 Private Wells
2.2.4 Surface Water
2.2.5 Sediment
2.2.6 Vessels
2.2.7 Additional Ground-Water Data
2.2.8 Summary of Site Contamination
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TABLE OF CONTENTS
Page
3.0 REMEDIAL RESPONSE OBJECTIVES 3-1
3.1 Risk Assessment Summary 3-1
3.2 Applicable or Relevant 3-1 and Appropriate Requirements (ARARs)
3.2.1 Action-Specific ARARs 3-3 3.2.2 Location-Specific ARARs 3-3 3.2.3 Chemical-Specific ARARs 3-4
3.2.3.1 Ground Water 3-5 Maximum Contaminant Levels (MCLs) 3-5 North Carolina Ground-Water Standards 3-5 Alternate Concentration Limits (ACLs) 3-6 Preliminary Pollutant Limit Values (PPLVs) 3-6 Ground-Water Remediation Levels 3-7 3.2.3.2 Surficial Soils 3-7 3.2.3.3 Subsurface Soils 3-8 3.2.3.4 Surface Waters 3-13 3.2.3.5 Sediments 3-13 3.2.3.6 Vessels 3-13
3.3 Areas of Potential Remediation 3-14
3.3.1 Ground Water 3-14 3.3.2 Surficial Soils 3-15 3.3.3 Subsurface Soils 3-15 3.3.4 Surface Waters 3-16 3.3.5 Sediments 3-16 3.3.6 Vessels 3-16
3.4 Remedial Design Basis 3-17
3.4.1 Ground Water 3-17 3.4.2 Vadose Zone 3-18
3.5 Summary of Remedial Response Objectives 3-18
Macon/Dockery FS ii July 5, 1991
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TABLE OF CONTENTS
4.0 IDENTIFICATION OF POTENTIAL TECHNOLOGIES
4.1 Screening Criteria
4.1.1 Effectiveness
4.1.2 Implementability
4.1.3 Cost
4.2 Listing of Potential Technologies
4.3 Ground Water Control Screening
4.3.1 Ground-water Recovery
4.3.2 Ground-water Treatment
4.3.2.1 . Volatile Organics
4.3.2.2 Metals
4.3.3 Ground-water Discharge
4.4 Source Control Screening
4.4.1 Direct Treatment
4.4.2 In Situ Treatment
4.4.3 Off-Site Treatment or Disposal
4.4.4 Containment
4.4.5 No Action
4.5 Technology Screening Summary
4.5.1 Ground Water Control
4.5.1.1 Ground-water Recovery
4.5.1.2 Ground-water Treatment
4.5.1.3 Ground-water Discharge
4.5.2 Source Control
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TABLE OF CONTENTS
5.0 DEVELOPMENT OF ALTERNATIVES
5.1 Areas of Potential Remediation
5.1.1 Ground-Water Control
5.1.2 Source Control
5.1.3 Vessels
5.2 General Screening Criteria
5.2.1 Effectiveness
5.2.2 Implementability
5.2.3 Cost
5.3 Formulation of Potential Alternatives
5.3.1 Ground-Water Control
5.3.1.1 Ground-Water Recovery
5.3.1.2 Ground-Water Treatment
5.3.1.3 Ground-Water Discharge
5.3.1.4 Concerted Ground Water Alternatives
5.3.2 Source Control
5.3.3 Vessels
5.3.4 Preliminary Costs for Alternatives
5.4 Screening Evaluation
5.4.1 Ground-Water Control
5.4.2 Source Control
5.4.3 Vessels
5.5 Summary of Retained Alternatives
Macon/Dockery FS iv
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TABLE OF CONTENTS
6.0 DETAILED ANALYSIS OF ALTERNATIVES
6.1 Evaluation Criteria
6.2 Ground-Water Control
6.2.1 Alternative GWC-1 : No Action
6.2.1.1 Alternative GWC-1A: No Further Activities
6.2.1.2 Alternative GWC-1 B: Long-term Monitoring of Site
Ground Water
6.2.2 Alternative GWC-2A: MCLs at the Site
6.3 Source Control
6.3.1 Alternative SC-1 : No Action
6.3.2 Alternative SC-2: Capping
6.3.3 Alternative SC-3: Capping and Soil Vapor Extraction
6.3.4 Alternative SC-4: Soil Vapor Extraction and
Biological Treatment
6.3.5 Alternative SC-5: Soil Vapor Extraction and
Off-Site Disposal
6.4 Vessels
6.4.1 Alternative V-1 : No Action
6.4.2 Alternative V-2: Off-Site Disposal
7.0 SUMMARY OF ALTERNATIVES
7.1 Ground Water Control
7.2 Source Control
7.3 Vessels
REFERENCES
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LIST OF APPENDICES
A -Summary of Constituent Detections for the Macon/Dockery Site
B -Additional Site Ground-Water Data of March 1991
C -Ground-Water Modeling
D -Protective Levels for Site Chemicals (PPLVs)
E -Development of Potential Soil Remediation Levels for the Vadose Zone
F -Cost Estimates
G -Air Quality Impact Analysis
Macon/Dockery FS vi July 5, 1991
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LIST OF FIGURES
1.1 Location Map tor the Macon/Dockery Site
2.1 Macon Site Plan
2.2 Dockery Site Plan
5.1 Proposed Cap at Former Lagoon 7
5.2 Proposed Cap at Lagoon 1 O
6.1 Ground-Water Treatment Flow Diagram
C.1 Macon Site Proposed Extraction Well Locations
C.2 Dockery Site Proposed Extraction Well Locations
E.1 Example Graphical Output from the VIP Model
Macon/Dockery FS vii July 5, 1991
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LIST OF TABLES
2.1 Summary of Site and Typical lnorganics Data for Surface Soils
2.2 Comparison of Vadose Zone lnorganics With Control Data
2.3 Summary of Macon/Dockery Site Contaminants by Matrix
3.0 Summary of Risk Assessment
3.1 Location-Specific ARARs
3.2 Comparison of Drinking Water, Ground Water, and Contract-Required
· Detection/Quantitation Limits for Chemicals Detected in the
Macon/Dockery Ground Water
3.3 Ground-Water Remediation Levels for the Macon/Dockery Site
3.4 Potential Soil Remediation Levels: Upper Macon Site
3.5 Potential Soil Remediation Levels: Lower Macon Site -Lagoon 10
3.6 Potential Soil Remediation Levels: Lower Macon Site -Lagoon 11
3.7 Potential Soil Remediation Levels: Upper Dockery Site
3.8 Potential Soil Remediation Levels: Lower Dockery Site
4.1 Potential Ground-Water Remediation Technologies
4.2 Potential Soil Remediation Technologies
4.3 Ground-Water Control Technology Summary
4.4 Source Control Technology Summary
5.1 Potential Remedial Alternatives
5.2 Preliminary Costs for Alternatives
5.3 Retained Alternatives for Detailed Analysis
6.1 Summary of Vessel Contents
7.1 Total Present Worth Costs for Retained Alternatives
Macon/Dockery FS viii July 5, 1991
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1.0 INTRODUCTION
Following is a Feasibility Study (FS) for the Charles Macon Lagoon and Drum Storage Site
and the Dockery Site (hereafter referred to as the Macon/Dockery Site or Site). The Site
is located in a rural section of Richmond County, North Carolina, approximately 6 miles
southwest of Rockingham, North Carolina near the South Carolina State line (Figure 1.1).
The Site is currently ranked 260 out of 1071 sites on the National Priority List (55 Federal
Register 35502, August 30, 1990). A more detailed discussion of the Site is presented in
Section 2 of this FS.
1.1 OBJECTIVES
The overall objectives of the Remedial Investigation/Feasibility Study (RI/FS) process
established by the EPA under the Superfund program are to:
(1) characterize the nature and extent of risks to human health and the environment, and
(2) evaluate potential remedial alternatives.
The RI/FS approach • ... should be viewed as a dynamic, flexible process that can and
should be tailored to specific circumstances of individual sites; it is not a rigid step-by-step
approach that must be conducted identically at every site" (EPA, 1988a). The
Macon/Dockery FS follows this United States Environmental Protection Agency (EPA)
rationale and these objectives for the performance of an RI/FS.
Data collected and interpreted as part of the RI are used to conduct a (1) Baseline Risk
Assessment (a separate document; Sirrine, 1991b) and (2) FS. The FS evaluates the
feasibility of potential remedial alternatives that will essentially eliminate or minimize the
uncontrolled release of any hazardous substances from the Site. This FS also addresses
any areas of potential off-site chemical migration.
Macon/Dockery FS 1-1 July 5, 1991
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The goal of the FS is to develop alternatives for review by the EPA and the State of North
Carolina to aid In selecting appropriate remedial alternatives for the Site. This FS is in
accordance with the Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA or Superfund) as promulgated under the National Oil and Hazardous
Substances Contingency Plan (NCP) of November 20, 1985 (50 Federal Register 47973),
the Superfund Amendments and Reauthorization Act (SARA) of October 17, 1986, and the
amended NCP of March 8, 1990 (55 Federal Register 8666). The general framework of this
document is based on the interim final EPA document Guidance for Conducting Remedial
Investigations and Feasibility Studies Under CERCLA (EPA, 1988a).
The primary objectives of the FS are to:
• develop appropriate remedial action levels based on (1)(a) Federal and State
chemical-and location-specific Applicable or Relevant and Appropriate Requirements
(ARARs) and (b) non-promulgated advisories or guidance issued by Federal or State
government, where available, and (2) through a health-based risk assessment where
uniformly applied and relevant standards are not available
• identify remedial alternatives and technologies available to reduce the risk to public
health or the environment based on known Site characteristics and levels of chemical
residuals
• perform screening of the identified remedial alternatives and technologies and conduct
a detailed evaluation of the retained alternatives
• identify action-specific ARARs for the implementation of the retained alternatives
• identify technologically feasible remedial alternatives that attain institutional and
regulatory requirements and are cost-effective.
Macon/Dockery FS 1-2 July 5, 1991
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This FS report gives a conceptual review of alternatives but is not intended to present
design level . detail. The objective is to develop a representative framework for evaluating
the potential remedial alternatives applicable to conditions at the Site. Upon selection of
a Site remediation program, any detailed design will be conducted in the Remedial Design
phase.
1.2 REPORT FORMAT
The remainder of this report is organized into the following sections:
2.0 SUMMARY OF REMEDIAL INVESTIGATION
3.0 REMEDIAL RESPONSE OBJECTIVES
4.0 IDENTIFICATION OF POTENTIAL TECHNOLOGIES
5.0 DEVELOPMENT OF ALTERNATIVES
6.0 DETAILED ANALYSIS OF ALTERNATIVES
7.0 SUMMARY OF ALTERNATIVES
APPENDICES
Brief descriptions of the remaining sections are provided on the following pages.
Section 2 (Summary of Remedial Investigation) summarizes the findings of the Site RI
(Sirrine, 1991a) relevant to the evaluation of remedial alternatives.
Section 3 (Remedial Response Objectives) presents the potential applicable or relevant and
appropriate requirements (ARARs) for the Site and identifies potential areas/media of
remediation. Site-specific and chemical-specific parameters relevant to conceptual design
are also specified.
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In addition to Section 3, a Baseline Risk Assessment was prepared as a separate document
(Sirrine, 1991b). The Risk AssJssment presents the baseline Public Health and I Environmental Risk Assessments. 0ata collected and interpreted in the RI were used to I perform the Risk Assessment. This evaluation serves as the basis for assessing the
potential human health and environ~entai impacts from the Site under current conditions. I The baseline risk assessment includes an analysis of potential pathways of exposure and
potential impacts to receptors (if !ny) of a no-action remedial alternative. Exposure
pathways identified in the baseline ~isk assessment that exceed acceptable risks will be
I further evaluated as part of the FS process. This further evaluation identifies remedial
alternatives that will reduce identifie I risks to acceptable levels.
Section 4 (Identification of Potential echnologies) identifies and screens potential treatment
and disposal technologies on the basis of Site conditions, waste characteristics, and
technical requirements. The screeni g process results in the elimination or modification of
those technologies that are not aJplicable, feasible, effective, sufficiently developed, or
otherwise not appropriate to be c6mbined into remedial alternatives for the Site. The
development of preliminary cost information allows the elimination of more costly
technologies which do not provide additional remedial effectiveness over remedies of
equivalent effectiveness.
Section 5 (Development of Alternatives) assembles a series of remedial alternatives for each
I different media identified in Section 3. Alternatives thus identified are compared with respect
I to short-and-long term aspects of technical effectiveness, implementability, and present
worth costs. The result is a reduJd list of alternatives for detailed analysis (Section 6).
Only the most promising alternativesl based on these evaluation factors are retained for final
screening. The action-specific ARARs are finalized in this section according to the refined
. potential remedial alternatives.
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Section 6 (Detailed Analysis of Alternatives) presents a detailed analysis of the retained
remedial alternatives based on the following NCP criteria: :(1) overall protection of human
health and the environment, (2) compliance with ARARs, (3) longcterm effectiveness and
I permanence, (4) reduction of toxicity, mobility, or volume, (5) short-term effectiveness, (6)
implementability, (7) cost, (8) state acceptance, and (9) co1mmunity acceptance.
A summary of remedial alternatives is presented in Section 7.
References for the FS are provided at the end of Section il.
Figures and Tables are provided within their referenced section or appendix.
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2.0 SUMMARY OF REMEDIAL INVESTIGATION
The purpose of the RI was to describe the (1) natur1 and extent of contamination identified I at the Macon/Dockery Site and (2) methods used to collect and evaluate data. That
information is used as the data base to evaluate\ risks associated with the Site (Risk
Assessment) and to conduct this FS to evaluate o~ions for Site remediation, if required.
A summary of the RI report (Sirrine, 1991 a) is prese1ed here to support the selection and
evaluation of remedial alternatives. More detailed infbrmation is contained in the RI report.
2.1 SITE CHARACTERIZATION
Descriptions of the Site's location, physiography, u1ilities, geology, hydrogeology,
meteorology, history, demography, and land use are ~resented in the following sections.
2.1.1 Location
The Macon/Dockery Site is located approximately 1 mile east of the Pee Dee River and 1.6
miles sou1hwest of Cordova, North Carolina on State \Road (SR) 1103. As indicated on
Figure 1.1, the Site comprises two non-contiguous prbperties. The Dockery property is
located approximately 2,600 feet north of the Macon prJperty on the west side of SR 1103. . I
The Macon Site is located at 34• 53' 30" north latitude, 79• 50' 18" west longitude, and the I
Dockery Site is located at 34 • 53' 52'' north latitude, 79150' 18" west longitude.
For reference purposes, the Macon and Dockery Sites have been divided into the upper
and lower Macon Sites and the upper and lower Dobkery Sites (Figures 2.1 and 2.2,
respectively). The upper Site in each case is located abjacent to SR 1103 which follows
a topographic ridge east of the Sites. The lower\ Site in each case is located
topographically downgradient and west of the upper Site.
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2.1.2 Physiography
The area where the Macon and Doc ery Sites are located lies on the western margin of the
Sandhills Region of the Inner CoastJ1 Plain Physiographic Province. The topography in this
area is generally smooth with exte~sive gently rolling interstream areas. The Site slopes
toward the Pee Dee River from an abproximate elevation of 275 feet above mean sea level
(MSL) to approximately 160 feet abhve MSL at the western boundary of the Sites. Along
the Pee Dee River, the topography becomes more rugged with deeply dissected stream
valleys where tributaries flow into the river. A broad, flat alluvial plain approximately 2,000
-wide • looated "'°"' 1,000 f•t wost of the Sito odjacorn to tho Poo o., ""''
Surface water and storm runoff on the Macon Site primarily drains to the west in the
direction of Solomon's Creek (Figu~e 1.1). Water which exits the northern portion of the
Macon Site enters either a small pdnd located in the western portion of the lower Macon
Site or an unnamed first order triJutary to Solomon's Creek. Water flowing from the
southern portion of the Macon Site ahd the small pond enters Solomon's Creek. Solomon's
Creek enters the Pee Dee River appjoximately two miles downstream from where Site runoff
enters Solomon's Creek.
Surface water runoff from the Doc ery Site flows via numerous gullies and intermittent
streams. Water leaving the norther~ portion of the Dockery Site enters a westward-flowing I tributary to the Pee Dee River. That tributary enters the Pee Dee River approximately one
mile west of the Dockery Site. wlter leaving the southern portion of the Dockery Site
enters the same unnamed tributa~ to Solomon's Creek as water leaving the northern
portion of the Macon Site. Water fr6m the Dockery Site enters the tributary approximately
one-half mile upstream of the Macoh Site.
The Macon property is approximately 60 percent wooded. Several cleared areas are
present at the Macon Site where dru1 storage areas, three unused surface impoundments,
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and 11 oil/water waste storage lagoons were located. As indicated on Figure 2.1, most of
the waste lagoons (Lagoons 1 thrbugh 9) were located in cleared areas on the upper
I Macon Site. Two waste storage lagoons (Lagoons 1 O and 11) were located on the
southwest portion of the lower Macon Site. Three empty and unused surface
impoundments, which were not investigated during this study, were located in the northern
portion of the lower Macon Site (Fidure 2.1). In addition to the above, various abandoned
buildings and above ground storag I vessels (i.e., tanks, vats, and tankers) remain on the
upper Macon Site.
The Dockery property is wooded ith few cleared areas (Figure 2.2). A single unpaved
road provides access to the Site frbm SR 1103. One waste lagoon (lagoon 12 at lower
I Dockery), as well as several drum storage areas were located in clearings on the Dockery
Site. Drum storage primarily occur ed at the cleared area that forms the upper Dockery
Site.
2.1.3 Utilities
Electricity, city water, and telephone connections are present along S.R. 1103. Municipal
sewer and natural gas services are not available.
2.1.4 Geology
The Sites are located in the Pee Dee River Basin near the Coastal Plain/Piedmont
physiographic boundary. Based Ion borehole logs and the observation of bedrock
outcroppings, the layer of residual boil and saprolite on competent bedrock at the Site is
estimated at 30 to 95 feet thick. Relidual soils are thickest in the area of the upper Macon
and Dockery Sites and thin westwa~d with increasing proximity to the Pee Dee river. The
I unsaturated zone of soil (also called the vadose zone) ranges from 25 to 35 feet thick. The
bedrock is granite and gneiss.
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2.1.5 Hydrogeology
Four distinct hydrogeologic units were encountered at the Macon/Dockery Site during the
RI. These units are distinguish~d primarily be differences in lithology and also by
differences in relative permeabilitieJ. In order of descending depth, these units include (1)
a perched water table, (2) a shillow saprolite unit, (3) a transition zone of partially
I weathered rock, and (4) a bedrock unit. Based on data obtained from both the Macon I and Dockery Sites and in view of t eir close proximity, the hydrogeology of the two Sites
appears to be similar.
Monitoring well locations are shown on Figures 2.1 and 2.2. A well construction data I
summary is provided in Table 3-6 of the RI Report. All monitoring wells are screened in the
saprolite or in the transition zone. For clarity, Site hydrogeologic units are discussed
separately in the following sections.
2.1.5.1 Perched Water Table
Evidence of a perched water tablel was observed during drilling and test pit excavation
activities at the upper and lower Macon Site and during drilling activities at the upper I Dockery Site. When encountered, the perched water table was present as a thin, laterally
discontinuous horizon of saturated boils. Perched water contained in this unit is believed
to recharge the underlying shallow 1saprolite aquifer. .
Depth to the perched water table is estimated to range from 14 to 20 feet. The saturated
thickness of the perched water tablel is estimated to be approximately 1 to 2 feet. Although
hydraulic conductivity (k) was not measured, attempts to produce water from this interval
while drilling the borehole for Mw-110 indicate that the yield of the perched water table is
extremely low.
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21.5.2 Shallow Saprolite Unit
Results of RI Site characterization activities indicate that an unconfined, shallow saprolite
unit is present throughout most of the Macon/Dockery Site, except where partially
weathered rock or bedrock is exposed at land surface. This unit comprises the water table
aquifer throughout most of the SitJ and is generally encountered between 20 to 35 feet
below land surface. Depth to the w1ter table generally decreases with increasing proximity I to the Pee Dee River. The saturate thickness of the shallow saprolite unit is approximately
20 to 30 feet.
The lateral component of ground-water flow for the shallow saprolite unit at the Site is, in
general, to the west-northwest with kn approximate hydraulic gradient of 0.07. Water table
configuration approximately parallell Site topography. Thus, the topographic ridge which I parallels SR 1103 is believed to act as a hydraulic divide for local ground-water flow.
Hydraulic conductivities obtained from slug tests conducted in 12 wells in the shallow
I saprolite unit ranged from 0.07 ft/day to 16. 71 ft/day with an arithmetic average of
approximately 2.4 ft/day. Hydraulic bonductivities in MW-05 (6.71 ft/day) and MW-07 (16.71
I ft/day) were much greater than the 10 other shallow wells tested ( <3.0 ft/day) and therefore,
the arithmetic average of 2.4 ft/day i! considered high. Consequently, the more appropriate
geometric average for these 12 iells is 0.55 ft/day. These differences in hydraulic
conductivity reflect the anisotropic bnd heterogenous character of the unit.
2.1.5.3 Transition Zone
A transition zone of partially weathered rock separates the saprolite and bedrock units.
Geologic logs indicate that this zo~e has an approximate thickness of 5 to 20 feet. The
ground-water flow direction in the trlnsition zone appears to be in a westerly/northwesterly
direction towards the Pee Dee Rive1r.
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Hydraulic conductivities calculated from slug tests performed in the 4 wells screening this
I unit range from 0.34 fVday (MW-08A) to 22.19 fVday (MW-02A), with an average value of
7.64 fVday. These variances are delieved to indicate that the hydraulic characteristics of
this unit are heterogenous and ahisotropic. Considering the fine-grained size of the
materials composing the unit, the :observed maximum value for hydraulic conductivity of
22.19 fVday exists in localized areas of limited extent.
2.1.5.4 Ground-Water Velocity
Horizontal ground-water flow velocities for both the Macon and Dockery Sites were
estimated using the geometric mea~ of hydraulic conductivities and the average (arithmetic)
hydraulic gradient across each SitJ. The geometric mean for hydraulic conductivity was
considered to be the most repreJentative for the entire flow regime due to apparent
-09'"'°"' and aa;sotropic "'t"""' ;°"""'"' by the sl,g tesl '"""'·
Ground-water velocity estimates were calculated with the following equation derived from
Darcy's Law:
V = ~ dh
n di
where: V = groun -water velocity
k = hydrau ic conductivity
n = effective porosity (assumed value = 0.20)
dh = hydraJlic gradient.
di
The geometric mean calculated fro slug test data on 16 wells is 0.82 fVday. Using an
I arithmetic average hydraulic gradient for the Macon Site of 0.05 fVft, the estimated ground-
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water velocity for the Macon Site is 0.21 ft/day. For the Dockery Site, the estimated
ground-water velocity is 0.16 ft/da~ (arithmetic average hydraulic gradient of 0.04 ft/ft).
2.1.5.5 Bedrock Unit
Bedrock or regional extent underlies the perched water table, saprolite unit, and transition
zone. This aquifer is predomlnantlylcomposed of granite, although it may grade into gneiss
at certain localities. No Site-spec~c Information is available concerning to the frequency
I and extent of any fractures within t is unit. There are no bedrock wells at the Site.
2.1.5.6 Vertical Flow Patterns
Macon Site
Ground water elevations collected at well pairs on the upper Macon Site Indicate that
recharge from the saprolite unit to t e transition zone is occurring. Approximate downward I vertical gradients were from 0.006 to 0.14 ft/ft. Vertical hydraulic conductivities obtained I from Shelby tube samples ranged from 0.00853 to 0.262 ft/day, with a geometric average I of 0.04 ft/day. Using this average value, vertical ground-water flow velocities were estimated
to be from 0.001 to 0.028 ft/day.
Dockery Site
Only one well pair is located at the Upper Dockery Site. A vertical upward hydraulic
gradient of 0.05 ft/ft was measured at this well pair. Using the average vertical hydraulic
conductivity of 0.04 ft/day at the Macon Site, the vertical ground water velocity for the
I Upper Dockery Site is 0.01 ft/day. This upward hydraulic gradient suggests that discharge
to the shallow unit is occurring at t~e Upper Dockery Site. Seasonal variations in ground
water elevations may influence the 61rection of the vertical ground-water flow.
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2.1.6 Meteorology
Climate in the study Site area is moderate, characterized by cool winters and hot summers.
Average minimum temperatures arl ju~t below freezing during the winter months with an
average high temperature of 54 t6 57•F. High temperatures for the summer months
average near 90•F with average I inimum temperatures around 66•F. Annual average
precipitation is 48 inches.
The prevailing wind directions for the area are south or southwest for most of the year. For
three months out of the year the pr I vailing direction is northeast. Destructive winds do not
occur frequently, but may occur in the form of tornadoes or hurricanes which strike the
coast.
2.1.7 History
From 1979 to 1982, Mr. Charles Macon operated a waste oil reclamation and antifreeze
manufacturing facility at the Maco~ property. Drums containing waste paints, solvents,
acids, and bases were also receivJd and stored on the Macon and Dockery properties.
I Operations at the Site were terminated in 1982.
In November 1982, clean-up of the Site by the United States Environmental Protection
Agency (U.S. EPA) was initiated. T~is clean-up involved the removal of approximately 300
55-gallon drums, installation and Jampling of two ground-water monitoring wells, and I collection and analysis of soil samp es.
In November 1983, the U.S. EPA resumed clean-up operations. Drums containing paint
wastes, organic solvents, ba~es, dus and assorted chemical wastes were solidified in
Lagoons 1 and 2 prior to off-site di~posal by the U.S. EPA.
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Lagoons on the Macon and Dock ry properties were excavated and back filled with soil I except for Lagoon 10 (Figure 2.1) which is reported by the U.S. EPA to contain an
estimated 940 tons of creosote-typ I waste. The U.S. EPA closed the wastes in Lagoon 10
in place by backfilling the unit and capping it with a synthetic liner and a three-foot-thick
clay cover. Prior to closure, the U S. EPA also disposed of approximately five truckloads
of solidified sludge from Lagoon , two truckloads of boiler fly ash, 43 crushed, empty
drums, and an unknown quantity of contaminated soil from the drum staging areas in
Lagoon 10.
A total of 2,142 tons of solidified wa te and 111,000 gallons of waste oil were removed from
the Macon/Dockery Site and dispoied of by the U.S. EPA. In addition, 26,000 gallons of
oil was recycled and 467,000 gallo~s of lagoon water was land farmed by the U.S. EPA in
an orchard located on the lower Mkcon Site. As part of the removal action, Acme Name
I Plating, Inc., Crown Cork and Seal Company, Inc., and General Tire Company, removed 508
drums of waste from the Site .
In February 1985, a geological an sampling investigation of the Site was begun by the
NUS Corporation. The data obtainJd during this investigation were used to determine Site
conditions following the initial clea~-up and to provide data needed to apply the Hazard
Ranking System (HRS) to the Site.
An Administrative Consent Order between the EPA and the participating Potentially
Responsible Parties (Clark Equipment Company and Crown Cork and Seal Company) was
I signed in April 1988. The Consent Order required that an RI/FS be conducted. Sirrine
Environmental Consultants (Sirrine) las contracted by the PRPs to prepare a RI/FS Project I
Operations Plan and conduct the RI/FS.
The RI was conducted in two phases: Phase I field activities were conducted from
September 1989 to January 1990, lnd Phase II field activities were conducted from July
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1990 to October 1990 .. A draft RI Report was prepared in December 1990 and submitted
to the U.S. EPA. U.S. EPA comments and additional concerns were addressed in a final
RI Report in March 1991 (Sirrine,j~991a). This final RI was submitted to the U.S. EPA.
2.1.8 Demography and Lan Use
Current land use within a one mj radius of the Sites is primarily agricultural with limited I residential use along Old Cheraw ~cad (SR 1103). Much of the land surrounding the Site
is uninhabited and undeveloped. Hunting is the primary human activity at the Site.
2.2 IDENTIFIED CHEMICALS
This section presents a general overview of the contaminants identified at the Site. The
objective of this section is to desc~ibe the contaminants that are in potential source areas
(surface soils, test pits, and soil b~rings) followed by potentially impacted areas (ground
water, surface water, and sediment). The referenced data summary tables are in Appendix
I A. This section and the tables in fppendix A are not intended to replace the voluminous
RI Report (Sirrine, 1991 a); please refer to it for more detailed information.
2.2.1 Surface Soils
Macon Site
Analytical data for surface soils collected from the Macon Site indicate that residual
chemicals correlate well with eithlr (a) isolated occurrences of disposed material and
chemicals or (b) waste materials associated with known disposal areas (lagoons) as
opposed to widespread areas of surface and shallow subsurface disposal. Chemical
analyses of 30 surface soil samples detected the presence of 35 Target Compound List
(TCL; organics) compounds at th I Upper and Lower Macon Site (Tables A-1 and A-2).
These constituents included 3 acid extractable compounds (semivolatiles), 22 base/neutral
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extractable compounds (also semivolatiles), one pesticide, and 9 volatile organic
compounds (volatiles). The mJjority of compounds detected in surface soils were
I polyaromatic hydrocarbons (PAHs), a subset of the base/neutral extractable compounds.
One pesticide was detected one t me. Dieldrin (a pesticide) was reported at 22 ug/kg in
only one sample. This sample Jas collected immediately after the field sampling team
noted the presence of a strong p~sticide-like odor arising from a garden adjacent to the
Site. The sample location and 11 w concentration of dieldrin reported for this sample,
therefore, is believed to represent contamination transport of dieldrin from the adjacent
residence (about 400 feet upwind) and not from the Site.
The detected Target Analyte List (TAL; inorganics) constituents at the Macon Site generally
occur in concentrations less than t~ose reported for typical background inorganics data for I surface soils typical of the area. The results are also similar to related soils found at the
Savannah River Site in Aiken, So~h Carolina where extensive soils research has been
conducted on soil series similar to t~ese found at the Site (Westinghouse, 1990), other soils
(Lindsay, 1979), and data from the USGS (Shacklette and Boerngen, 1984; Table 2.1).
Dockery Site
Detected TCL constituents among the Dockery Site surface soil samples included di-n-butyl
phthalate, acetone, and methylene hhloride. Di-n-butyl phthalate was detected in sample
at a concentration of 77 ug/kg and ias reported in the associated method blank. Method
or reagent blanks provide a measJre of contamination that has been introduced into a
sample set in the laboratory durin~ sample preparation and analysis. To prevent the
I inclusion of non-site-related contaminants in the Site assessment, the concentrations of
chemicals detected in blanks must b~ compared with concentrations of the same chemicals
detected in the Site samples.
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Blank sample data should be compared with results from samples with which the blanks
are associated (i.e., sample batch). However, comparisons of blank data with results from
the entire sample data set are recommended in EPA (1989a) as an alternative.
As discussed in the CLP SOW for Organics (EPA, 1988e) and the Functional Guidelines for
Organics (EPA, 1988f), acetone, 2-butanone (or methyl ethyl ketone), methylene chloride,
toluene, and phthalate esters are considered by EPA to be common laboratory
contaminants. In accordance with the Functional Guidelines for Organics (EPA, 1988f), if
the blank contains detectable levels of common laboratory contaminants, then the sample
results should be considered as positive only if the concentrations in the sample exceed
ten times the maximum amount detected in any blank.
0 Laboratory contamination is commonly found in the vicinity of 25 ppb. Using the ten times
rule discussed above, organics recognized by EPA as laboratory contaminants could be as
high as 250 ppb before being considered site contamination.
Acetone and methylene chloride concentrations reported for the Dockery Site surface soil
samples are indicative of laboratory contamination. Consequently, analytical data for
surface soils collected from the Dockery Site do not indicate the presence of TCL
chemicals.
The detected TAL constituents at the Dockery Site surface soil (Tables A-5 and A-6)
generally occur at background concentrations (Table 2.1). No TAL constituents were
detected at significant concentrations in the Dockery Site surface soil samples.
2.2.2 Vadose Zone Soils
A discussion of impacts to vadose zone (unsaturated) soils at the Macon/Dockery Site is
primarily a discussion of the history and nature of waste disposal at the Site (e.g., lagoons).
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Test pits and soil borings (including borings advanced for monitoring well installation) were
employed to directly observe and sample waste materials and impacted vadose zone soils
in suspect areas.
Test pits were excavated at former lagoons at the Site and were generally excavated to a
depth of 10 to 13 feet below the ground surface. This was also below the depth of visually
determined changes in soil strata caused by previous Site activities. Organic analytical data
for the Macon Site test pit samples (Tables A-7 and A-8) indicate that volatiles are the
predominant TCL constituents in vadose soils underlying the former waste lagoons.
Organics data (Table A-10) for the Lower Dockery Site test pit (no test pit at the Upper
Dockery Site) indicate low levels of primarily volatile organic compounds.
Inorganic data (TAL parameters) for the test pits are provided in Tables A-9 through A-11.
Soil borings were also drilled at the Site. Soil samples were collected from borings
generally at 15-17 feet and 25-27 feet below the land surface. Consequently, samples from
soil borings advanced through former lagoons were collected beneath the bottom of the
former lagoons. Soil borings samples were also collected as part of the monitoring well
installations.
Analytical data from soil boring vadose zone samples (Tables A-12 through A-19)
substantiate conclusions developed upon review of test pit samples. Elevated
concentrations of TCL constituents in vadose zone soils are associated with former waste
storage lagoon areas. Detected TCL constituents generally correspond to the types of
materials reportedly removed by the U.S. EPA clean-up in the former lagoon storage areas.
Detected TAL constituents in soil boring samples correspond to those reported for the test
pit soils. Table 2.2 compares maximum vadose zone inorganic concentrations with Site
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control data. For ease of comparison, vadose soils have been grouped into 6 areas based
on the close proximity of certain former lagoons.
2.2.3 Ground Water
Following Is a discussion of the constituents detected in the ground water at Upper and
Lower Macon and at Upper and Lower Dockery.
2.2.3.1 Upper Macon Site
Analytical data (Tables A-20 and A-21) indicate that the ground-water in the vicinity of
monitoring wells MW-03 and MW-11 (Figure 2.1) has not been impacted by former waste
handling activities at the upper Macon Site. TCL constituents were undetected in these well
samples, and detected TAL constituents are consistent with those reported for the control
sample (MW-01). Monitoring well MW-01 contains trace concentrations of TCL constituents .
The presence of these trace compounds is likely related to transport of residual chemicals
in ground water towards MW-01 during seasonal changes in ground-water flow.
Ground-water samples collected from monitoring wells MW-2, MW-2A, MW-5, MW-6, MW-
8, MW-8A, MW-9, MW-10, and MW-19 exhibit varying concentrations of TCL constituents.
Only ground-water samples collected from wells MW-9 and MW-19 contained
base/neutral/acid extractable compounds as well as volatile organic compounds. The
remaining samples contained only volatile organic compounds. Each of the wells listed
above are located directly down-gradient from areas of past waste storage, primarily
lagoons. The presence of residual chemicals in these wells is likely due to the close
proximity of storage lagoon areas and appropriate placement of the wells for intercepting
residual chemicals in ground water moving away from the source areas.
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In general, ground-water samples which contained TAL metals at concentrations above
those reported for the control sample (MW-01) were collected from monitoring wells MW-
5, MW-6, MW-7, MW-8, MW-SA, MW-9, MW-10, and MW-19. However, most ground-water
samples were highly turbid despite proper monitoring well installation, monitoring well
development, and sample collection. The particulate matter that contributed to the turbidity
contained naturally-occurring metals on and within soil particles. Consequently, as turbid
ground-water samples are preserved to a pH of 2 (or less; as required by U.S. EPA
protocol), these naturally-occurring metals desorb and dissolve, thus contributing to the
metals composition of a ground-water sample. This positive bias must be considered when
interpreting the inorganics data for ground-water samples. This situation, and results of
selected monitoring well re-samples, are discussed further in Appendix B.
2.2.3.2 Lower Macon Site
Analytical data for lower Macon Site monitoring wells (Table A-22) indicate the presence of
residual TCL constituents. As with the majority of upper Macon Site wells, the presence of
residual chemicals in wells MW-4, MW-12, MW-13, and MW-14R (Figure 2.2) appear to be
related to the presence and close proximity of former waste storage areas, primarily
lagoons. These wells are located directly down-gradient of lagoon areas and serve as
direct monitoring positions for residual chemicals migrating to the northwest in ground
water.
2.2.3.3 Upper Dockery Site
Concentrations of TCL constituents at the upper Dockery Site (Table A-23) were detected
in an area where drums had been stored. Ground-water samples collected from monitoring
well MW-15 (Figure 2.2) indicated residual chemicals, especially 1,1,1-trichloroethane, 1,1-
dichloroethane, and 1, 1-dichloroethene. Review of aerial photographs of the Site and visual
observations during RI field activities indicate that the vicinity of MW-15 was used for drum
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storage. Contaminant transport modeling indicates that the ground-water contaminant
plume may extend several hundred feet downgradient from the vicinity of MW-15.
2.2.3.4 Lower Dockery Site
The presence of residual chemicals (TCL and TAL constituents; Table A-25) in MW-16
(Lower Dockery site) appears to be related to the close proximity of the well to Lagoon 12.
MW-16 Is located Immediately down-gradient of Lagoon 12 and serves as a direct
monitoring position for ground water migrating away from MW-16 (Figure 2.2). Widespread
contamination of the lower Dockery Site is not likely based on the limited disposal area and
reported disposal activities.
2.2.3.5 Private Wells
No TCL compounds were found in samples collected from privately-owned wells near the
Site (Table A-26). · Detected TAL constituents for wells PW-02 and PW-03 were within
Maximum Contaminant Levels (MCLs) and ranges determined from the control sample. In
well PW-o4, iron exceeded the secondary MCL (483 ug/I versus an MCL of 300 ug/L} but
was less than the concentration detected in the control sample. Well PW-05 exceeded
MCLs for iron and manganese. However, these constituents were detected in
concentrations less than the control sample.
Vanadium and zinc were detected in concentrations slightly exceeding the control sample
(MW-01}. Consequently, elevated concentrations these two metals are most likely
attributable to natural background levels.
Cobalt, copper, magnesium, vanadium, and zinc concentrations in PW-05 exceeded the
control sample (MW-01) concentration. PW-05 is located at a slaughterhouse facility that
is hydraulically upgradient from the Site. Observed Site conditions at the slaughterhouse
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indicate that impact to the soil and ground-water media are possible due to the slaughtering
operations, cleaning practices, and disposal procedures. In summary, the Site does not
adversely impact private wells.
2.2.4 Surface Water
No residual TCL constituents were detected in surface water samples collected down-
gradient from either the Macon Site or the Dockery Site (Table A-27). TAL constituents
(Table A-27) detected in the Macon Site surface water control sample (SW/SED-03; Figure
3-8 of RI) were within normal ranges for natural waters.
The surface water sample collected from the lower Macon Site pond contained elevated
concentrations of barium, calcium, magnesium, and manganese. The surface water results
of samples collected down-gradient of the Dockery Site are essentially the same as the
results from the control sample (SW/SED-07; Figure 3-8 of RI) for TAL constituents (Table
A-28). The impact or residual chemicals from the Site to Solomon's Creek is minimal (see
the Risk Assessment, Sirrine, 1991b).
2.2.5 Sediment
TCL constituents detected in Macon Site sediment samples (Table A-29) correspond with
tar or asphalt-coated wood fragments from the bridge materials (not related to the Site) that
were found in the sediment sample. TCL constituents were not detected in other
downstream sediment samples. Sediment samples from the Dockery Site (Table A-30)
indicate the presence of benzoic acid and benzo(a)pyrene. However, the remote nature of
the sampling location indicates that these compounds are not from the Site.
Pond sediment samples (Lower Macon Site) and surface water samples contained
inorganics at or near background concentrations. Variations in metals concentrations
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detected in sediment samples are viewed as a function of sediment grain size, mineralogy,
and depositional environment. Analytical and physical data indicate that stream sediment
transport is not acting as a mechanism for the off-site transport of TAL constituents.
2.2.6 Vessels
Site vessels (above ground tanks, tankers, and vats) that contained mixtures of water, oil,
tar, and solids were sampled. Samples were submitted for Toxicity Characteristics Leaching
Procedure (TCLP) volatiles, semivolatiles, and inorganics analyses (55 CFR 26986, June 29,
1990). In addition, ignitability and corrosivity tests were conducted on samples to determine
if they met the characteristic of a hazardous waste according to RCRA.
Vessel analytical data are summarized in Table A-31. All samples analyzed were determined
to be non-hazardous (RCRA) except for lead (Pb) in tank Samples 3 and 4 (both oils) and
Vat 4 (solids). Tank 3 exceeded the regulatory TCLP level for lead by a factor of 3 (15
mg/L). Tank 3 and Vat 4 levels were less. Estimated volumes of water, oil, tar, and solids
are provided in Table A-32.
2.2.7 Additional Ground-Water Data
Additional ground-water samples were collected by Sirrine in March, 1991 and analyzed for
selected inorganic constituents. These samples and data were collected to better
understand potential effects of the Site, if any, on ground water. Details are discussed in
Appendix B.
2.2.8 Summary of Site Contamination
No uniform vertical or horizontal distribution of the residual chemicals is apparent at the
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Site. Instead, chemical residuals in soil and ground water appear to be concentrated in
localized areas related to former storage activities (lagoon waste and drum storage).
PCBs are not chemicals of concern at the Site. One pesticide was detected at one
sampling location; however, its presence was attributed to pesticide application by an
adjacent land owner near the sampling location. Potential chemicals of interest include
selected volatile and semivolatile organic compounds and inorganic compounds. A
summary of matrices and contaminants for the Macon/Dockery Site is presented in Table
2.3.
Previous removal actions by the U.S. EPA have significantly reduced or eliminated the
concentrations of contaminants in potential source areas (soils) and therefore have reduced
any impact to receptor areas (e.g., surface water, sediment, ground water).
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3.0 REMEDIAL RESPONSE OBJECTIVES
Site-specific remedial response objectives are based on the baseline risk assessments
(Sirrine, 1991b) and on the evaluation of applicable or relevant and appropriate
requirements (ARARs). Results of the risk assessments and the evaluations of ARARs will
be used to define potential areas of remediation at the Macon/Dockery Site.
3.1 RISK ASSESSMENT SUMMARY
Details of the risk assessment are presented in a separate document (Sirrine, 1991b). A
summary of the current and predicted Mure risks is provided in Table 3.0. For
carcinogens, an acceptable risk is 10E-4 to 10E-6 (or below) lifetime excess cancer risk
(LECR) as reflected in EPA remediation goals and for non-carcinogens, a Hazard Index (HI)
less than unity (i.e., 1). Examination of Table 3.0 reveals that the Site currently does not
pose any significant risks (current-use risk assessment). Predicted Mure use of Site
ground water indicates unacceptable risks for both non-carcinogens and carcinogens (Table \
3.0). The predicted future LECRs for the Upper and Lower Macon Site surface soil are
estimated to be 4.56E-4 and 3.58E-4 (respectively), primarily due to arsenic at the Upper
Macon Site and PAHs at the Lower Macon Site. This will be further discussed in Section
3.2.3.2. Other predicted future risks are estimated to be acceptable.
An ecological endangerment assessment was also conducted for the Site (Sirrine, 1991 b).
Although areas of possible concern were identified, these appear to be localized and overall
effects are expected to be minimal. Further characterization of these areas of possible
concern will be conducted during Remedial Design.
Macon/Dockery FS 3-1 July 5, 1991
I Table3.0
Summary of Risks .. Macon/Dockery Site
Site/ Surface Ground Surface
I Type of Risk Soil Water Water Sediment Total
I Current Use
Upper Dockery
I Carcinogenic
Noncarcinogenic 4.0SE-12 4.0SE-12
Lower Dockery
I Carcinogenic 2.88E-07 2.75E-10 2.63E-13 2.88E-07
Noncarcinogenic 2.79E-02 8.41E-05 3.02E-08 2.B0E-02
I Upper Macon
Carcinogenic 6.21E-05 3.33E-10 6.21 E-05
Noncarcinogenic 2.11 E-01 6.71E-04 2.0SE-03 2.14E-01
I Lower Macon
Carcinogenic 4.20E-05 7.67E-10 3.33E-10 4.20E-05
Noncarcinogenic 1.27E-02 1.03E-03 2.14E-03 1.59E-02
I Pee Dee River at
Solomon's Creek .. Carcinogenic 1.28E-11 1.28E-11
Noncarcinogenic 3.09E-06 3.09E-06
I Pee Dee River at
Cheraw
Carcinogenic 3.73E-07 3.73E-07
Noncarcinogenic 7.89E-04 7.89E-04
I future Residential Use
I Upper Dockery
Carcinogenic 1.40E-03 1.40E-03
Noncarcinogenic 4.0SE-12 1.00E+01 1.10E+01
I Lower Dockery
Carcinogenic 2.88E-07 5.12E-04 4.74E-10 5.26E-13 5.12E-04
Noncarcinogenic 2.18E-01 9.70E+00 1.72E-03 6.04E-08 9.92E+00
I Upper Macon
Carcinogenic 4.56E-04 6.SSE-03 6.66E-10 7.00E-03
I Noncarcinogenic 7.83E-01 1.27E+01 1.33E-03 3.45E-03 1.35E-01
Lower Macon
I Carcinogenic 3.SBE-04 1.29E-03 8.91E-10 6.66E-10 1.64E-03
Noncarcinogenic 1.27E-01 4.20E+02 1.97E-03 3.70E-03 4.29E+00
•• Macon/Dockery July 5, 1991
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3.2 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARs)
Section 121 (d) of the Comprehensive Environmental Response, Compensation and Liability
Act (CERCLA) of 1980, as amended by the Superfund Amendments and Reauthorization
Act of 1986 (SARA), requires that remedial actions comply with requirements or standards
set forth under Federal and State environmental laws. The requirements that must be
complied with are those that are applicable or relevant and appropriate (ARAR) to the (1)
potential remedial actions, (2) location, and (3) media-specific chemicals at the Site.
As mandated by CERCLA 121(d)(2)(A), remedies must consider "any promulgated standard,
requirements, criteria, or limitation under a State environmental or facility siting law that is
more stringent than any Federal standard, requirement, criteria, or limitation" if the former
is applicable or relevant and appropriate to the site and associated remedial activities.
SARA requires that the remedial action for a site meet all ARARs unless one of the following
conditions is satisfied:
the remedial action is an interim measure where the final remedy will attain the
ARAR upon completion;
compliance will result in greater risk to human health and the environment .than
other options;
compliance is technically impracticable;
an alternative remedial action will attain the equivalent of the ARAR;
for State requirements, the State has not consistently applied the requirement
in similar circumstances.
In addition to ARARs (i.e., legally binding laws and regulations), many Federal and State
environmental and public health programs also develop criteria, guidance, and proposed
standards that are not legally binding, but that may provide useful information or
recommended procedures (EPA, 1988c). These '1o-be-considered" (TBCs) are not potential
ARARs but are evaluated along with ARARs to set remediation objectives (e.g., cleanup
goals) .
Macon/Dockery FS 3-2 July 5, 1991
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ARARs may be classified as either action-specific, location-specific or chemical-specific.
Review of ARARs and TBCs with respect to the Macon/Dockery Site is given In the
following subsections.
3.2.1 Action-specific ARARs
Action-specific requirements set controls or restrictions on the design, performance and
other aspects of implementation of specific remedial activities. Examples Include RCRA
regulations tor off-site disposal of hazardous residuals, Clean Water Act standards tor
discharge of treated ground water, and North Carolina sediment and erosion control
standards (North Carolina Division of Land Resources) for excavation of soils. Because
action-specific ARARs apply to discrete remedial activities, their evaluation is presented in
Section 6, Detailed Analysis of Alternatives, for each retained alternative. A retained
alternative must conform to all ARARs unless one of the five statutory waivers stated above
is involved.
CERCLA Section 121(e) exempts any on-site response action from having to obtain a
Federal, State and/or local permit. The on-site actions must, however, still comply with the
substantive aspects of these requirements.
3.2.2 Location-specific ARARs
Location-specific ARARs must consider Federal, State, and local requirements that reflect
the physiographical and environmental characteristics of the site or the immediate area.
Remedial actions may be restricted or precluded depending on the location or
characteristics of the site and the resulting requirements. A listing of potential location-
specific ARARs and their consideration in this FS is given in Table 3.1.
Macon/Dockery FS 3-3 July 5, 1991
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One potential location-specific ARAR that will be considered is Federal and State aquifer
classifications. The classification and potential uses of an aquifer are important elements
In determining appropriate remediation levels. Under EPA's ground water classification
system, the ground water beneath the Site is considered Class IIA (current source of
drinking water) even though there are no downgradient receptors In the Immediate area or
current users of the Site ground water (Table 3.1 ).
The State of North Carolina has three classifications for ground water: GA, GSA, and GC.
Class GA ground waters are current or potential sources of drinking water, GSA Is for
potable mineral water, and GC is for waters other than drinking water. Although ground
water beneath the. Site is not used for drinking water nor is it expected to, it is a potential
source of drinking water and is classified GA according to North Carolina. This ground
water classification is a potential ARAR and will be considered further during the
development of remedial alternatives.
Both Solomon's Creek and the pond at the Lower Macon Site may potentially be classified
as wetlands. Consequently, another potential location-specific ARAR relates to wetlands
(Table 3.1).
3.2.3 Chemical-specific ARARs
Chemical-specific ARARs are concentration limits in the environment promulgated by
government agencies. Health-based site-specific levels must be developed for chemicals
or media where such limits do not exist and there is a concern with their potential health
or environmental impacts. Potential chemical-specific ARARs are discussed by media
below.
Macon/Dockery FS 3-4 July 5, 1991
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3.2.3.1 Ground Water
Potential ARARs for ground water include Maximum Contaminant Levels (MCLs), North
Carolina Drinking Water Standards, and North Carolina Ground-Water Standards. Some
chemicals at the Site lacked established ground-water quality criteria for consideration In
developing remedial alternatives. Consequently, remediation levels were calculated for these
chemicals using the preliminary pollutant limit value (PPLV) approach.
Maximum Contaminant Levels (MCLs)
Site ground water is considered a potential source of drinking water under Federal
guidelines (Class IIA) and as Class GA under North Carolina state guidelines. Currently,
the Site ground water is not being used as a source of drinking water.
The NCP states that Maximum Contaminant Levels (MCLs), established under the Safe
Drinking Water Act (SDWA), are potentially relevant and appropriate ground-water standards
for the remediation of current or potential sources of drinking water (300.430(e)(2)(i)(A)) .
MCLs and proposed MCLs for Macon/Dockery Site ground water chemicals are provided
in Table 3.2. In addition, the table presents the maximum ground-water concentration for
a particular chemical and its associated sampling location as determined by the RI.
North caronna Ground-Water Standards
North Carolina drinking water standards (1 O NCAC 1 OD) are essentially identical to the
SDWA MCLs established by the EPA (Table 3.2). North Carolina Ground-Water Standards
(North Carolina Administrative Code (NCAC) Title 15A, Chapter 2, Subchapter 2L) for Class
GA ground water are generally more stringent than MCLs and are potentially applicable.
Drinking water standards (applicable to millions of people i,:, North Carolina) are equal or
less stringent than the North Carolina Ground-Water Standards.
Macon/Dockery FS 3-5 July 5, 1991
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As seen in Table 3.2, some of the North Carolina Ground-Water Standards are below the
CERCLA contract required quantitation limits (i.e., benzene, chloroform, tetrachloroethene,
trichloroethene, vinyl chloride). In these cases, the North Carolina Ground-Water Standard
defers to the quantitation limit as the maximum allowable concentration {15 NCAC 2L
Section .0202{b)).
Alternate Concentration Limits (ACLs)
Site data are not sufficient at this time to establish the appropriateness of Alternate
Concentration Limits (ACLs; 40 CFR Part 300) for ground-water remediation levels.
Establishment of ACLs for Site ground water may be appropriate after additional ground-
water monitoring. ACLs will not be considered in this FS.
Preliminary Pollutant Limit Values
As seen on Table 3.2, three chemicals in the ground water lack established water quality
criteria for consideration in developing remedial alternatives. These are acetone, 1, 1-
dichloroethane, and isophorone .
Ground water quality levels for these remaining compounds must be based on health-
based risk levels, where available. Oral reference doses (RFD) are used for non-
carcinogens while oral cancer potency factors are used for carcinogens. Calculation of
ground water quality levels is based on the following EPA factors:
70 kg body weight
2 liters per day ingestion
10-5 risk level (carcinogens).
PPLVs were calculated for 3 of the 4 chemicals. Derivation of PPLVs are presented In
Appendix D. The resulting PPLVs are listed in Table 3.2.
Macon/Dockery FS 3-6 July 5, 1991
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It was not possible to calculate a PPLV or find any quantitative risk information about
chloroethane. Based on the information found and on the localized, low concentrations of
chloroethane at the Upper Macon Site, It was determined that chloroethane Is not a
chemical of significant concern at the Site (see Appendix D).
Ground-Water Remediation Levels
Ground-water remediation levels for the Macon/Dockery Site will be the most stringent
standard listed in Table 3.2 or the quantitation limit. Table 3.3 presents the ground-water
chemicals of concern and their associated remediation level. For purposes of clarity In this
FS, remedial alternatives will discuss achieving MCLs as specified by the NCP.
3.2.3.2 Surficial Soils
The current-use risk assessment (Sirrine, 1991b) determined risk levels for surficial soils.
For carcinogens, an acceptable risk is 10F4 to 10E-6 (or below) and for non-carcinogens,
a HI less than 1. Carcinogenic risks for Site surface soil were slightly exceeded at the
Upper and Lower Macon Site (Table 3.0), primarily as a result of arsenic. No surficial soil
had a HI greater than one. Arsenic was detected at the Upper Macon Site from 1.9 to 5.8
ppm and at the Lower Macon Site from 0.88 to 3.9 ppm while average background
concentration for arsenic was 3 ppm at the Site. There are no promulgated Federal or
State standards applicable for contaminants detected in surface soil at the Site. However,
a relevant and appropriate ARAR for surface soils is RCRA soil action levels (40 CFR Part
264.521 (a)(2)(i-iv). The RCRA soil action level for arsenic (non-carcinogenic, systemic risks)
is 80 mg/kg while the maximum arsenic concentration for surface soils at the Upper Macon
Site was 5.8 N mg/kg (N indicates that the spiked sample recovery was outside of control
limits) and 3.9 mg/kg at the Lower Macon Site. In addition, there is a degree of uncertainty
associated with the potential risks posed by exposure to trace levels of arsenic in the Site
surface soil, as discussed in the Risk Assessment (Sirrine, 1991b). For these reasons, the
surficial soils at the Macon Site do not require remediation. Consequently, remediation of
surficial soils at the Site will not be further considered in this FS.
Macon/Dockery FS 3-7 July 5, 1991
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3.2.3.3 Subsurface Soils
As discussed in Section 2.1.7, the interim remedial action by the EPA in 1982-1983 removed
most of the chemical sources at the Site (e.g., lagoon and drummed materials). One of the
greatest effects of this removal action was to significantly reduce the concentration of
chemicals In source areas, including the vadose zone. Although not quantifiable, the effect
on human health and the environment (i.e., ground water) was greatly reduced.
Examination of the RI data demonstrates that in spite of the early remedial actions, some
chemicals migrated through the vadose zone and into the ground water by natural flushing.
This migration was driven by at least two transport forces: bulk flow of chemicals and the
infiltration of precipitation into the vadose zone. This migration is likened to a slug of
contamination moving down through the vadose zone from a concentrated source area
such as a lagoon. However, modeling (discussed below) indicates that the most significant
portion of these slugs of mobile chemicals have already migrated through the vadose zone.
As a result, the vadose zone is generally contains only residual chemicals that are relatively
Immobile or will not adversely impact the ground water.
Remediation levels for subsurface soils that are above the ground water are based on a
compound's potential to impact ground water. Concentrations of chemicals In subsurface
soil that are protective of ground water were developed using the Vadose Zone Interactive
Processes (VIP) model (Stevens et al., 1991 ).
This model was developed by EPA's Kerr Environmental Laboratory (Ada, Oklahoma) and
the Civil and Environmental Engineering Department of Utah State University (Logan, Utah).
The VIP model was developed to accurately predict the fate and transport of compounds
In the vadose zone of soil. Input parameters, such as those associated with a specific soil
type and recharge rate (e.g., precipitation), allow the model to be tailored to a specific
situation. The model therefore calculates Site-specific remediation levels.
Macon/Dockery FS 3-8 July 5, 1991
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In order to conduct a model run, Site-specific and chemical-specific parameters (Tables E.1
and E.2 in Appendix E) are input. The thickness of the initial contaminated zone was
assumed to be 4 feet, based on RI data (Sirrine, 1991a). The model was run for a time
specified by the modeler. The model runs were continued until the maximum concentration
of vadose zone leachate reached the ground water. The concentration in this maximum
slug of contamination (if any) was diluted (attenuated) by the ground water beneath the
modeled vadose zone. Details about the modeling, including input parameters, are
provided in Appendix E.
Potential remediation levels for vadose zone soils are provided in Tables 3.4 through 3.8
for the Site. These tables present the maximum vadose concentration for a chemical and
its estimated concentration in, and time of travel to the water table. For compounds that
are estimated to migrate to the ground water, the estimated concentration and its regulatory
limit (if any) are presented for comparison. For three compounds found in the ground
water (acetone, isophorone, and 1,1-dichloroethane), PPLVs were used for comparison
since no MCL values were available. The derivation of PPLVs for these compounds is
provided in Appendix D.
Upper Macon Site
Potential subsurface soil remediation levels for the Upper Macon Site are provided in Table
3.4. The VIP model estimated that five organic compounds would reach the ground water
from the vadose zone above detection limits: acenaphthene, isophorone, acetone,
ethylbenzene, and tetrachloroethene (PCE). Only three of the compounds were found in
the ground water: isophorone at 2 ug/L (VIP predicted 4 ug/L), acetone at 42 ug/L (VIP
predicted 33 ug/L), and tetrachloroethene at 44 ug/L (VIP predicted from 2 to 80 ug/L).
The other compounds were not detected in ground water.
Macon/Dockery FS 3-9 July 5, 1991
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Comparison of Table A-20 (ground water, Upper Macon) with Table 3.4 (vadose zone,
Upper Macon) shows that some compounds were detected in the ground water but not in
the vadose zone. For example, vinyl chloride (a degradation product of chlorinated aliphatic
compounds such as PCE) was found in the ground water at the Upper Macon Site at a
maximum concentration of 510 ug/L but not in the vadose zone. Other examples Include
chloroethane (possibly a degradation product of trichloroethane) and 1,1-dichloroethene.
Consequently, it appears as though volatile organic compounds in the Upper Macon vadose
zone may continue to impact the ground water. Specifically, PCE and vinyl chloride are the
compounds of concern. PCE may Impact the ground water directly (as PCE) or Indirectly,
by serving as the parent compound for the formation of vinyl chloride.
Metals in the vadose zone of the Upper Macon Site appear to be slightly above background
levels (Table 2.2). However, they have apparently been immobilized by the considerable
cation exchange capacity of the vadose zone (Table 3.4) .
Lower Macon Site
Because of the differences in waste materials between Lagoon 1 o and Lagoon 11 they
were modeled separately using the VIP model. Potential remediation levels for the Lower
Macon Site Lagoon 10 are provided in Table 3.5. The VIP model estimated that seven
organic compounds would impact the ground water: benzoic acid, acenaphthene, di-n-
butyl phthalate, acetone, ethylbenzene, styrene, and toluene. However, only acetone and
benzoic acid were detected in the ground water at the Lower Macon Site (Table 3.5). As
with the Upper Macon Site, chemicals found in the ground water are most likely the result
of a slug of contamination entering the ground water prior to the interim remedial action.
VIP Modeling for Lagoon 11 predicted that acenaphthene would impact the ground water
at the Lower Macon Site. However, acenaphthene was not detected in the Lower Macon
Site ground water.
Macon/Dockery FS 3-10 July 5, 1991
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In addition, benzo(a)pyrene and phenanthrene were modeled at three concentrations and
three depths to determine the effect on ground water, if any, of lower concentrations nearer
the ground-water surface (compared with higher concentrations further above the ground
water). Again, these compounds were predicted to be immobile and not adversely impact
the ground water even when a lower concentration was modeled closer to the ground
water.
Material from Lagoon 1 O at the Lower Macon Site contains some of the highest chemical
concentrations on Site. Most of these compounds are polycyclic aromatic hydrocarbons
(PAHs) that have a tendency to sorb to the soil in the vadose zone (high Koc values). In
addition, a temporary soil/polyethylene cap was placed on Lagoon 1 O during the interim
remediation.
' Cadmium appears to be the only metal that is slightly elevated in the Lower Macon vadose
zone (see Table 2.2). However, neither cadmium or any other soil metals in the Lower
Macon Site will adversely impact the ground water since the metals have been immobilized
by the vadose zone soils. Immobilization occurs due to the (1) high values of the vadose
zone soil cation exchange capacities (CEC) and (2) relatively high equilibrium adsorption
coefficients (Kd; see Appendix E).
Upper Dockery Site
The Upper Dockery Site does not contain any former lagoons. However, it reportedly
served as a drum storage area. Vadose zone contamination at the Upper Dockery Site Is
most likely related to reported drum storage.
Potential remediation levels for the Upper Dockery Site are provided in Table 3.8. The VIP
model estimated that five organic compounds could impact the ground water: diethyl
phthalate, dimethyl phthalate, acetone, methylene chloride, and 4-methyl-2-pentanone. Of
these five, acetone was the only organic compound detected in ground water at the Upper
Macon/Dockery FS 3-11 July 5, 1991
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Dockery Site and its presence may be related to laboratory sample contamination (Table
A-23; maximum acetone concentration of 59 ug/L versus 32 ug/L as estimated by the VIP
model).
As with the other areas of the Site, ground water contamination appears to be related to
a slug of contamination when the source area was much more concentrated. For example,
the highest concentration of any organic compound found in the Upper Dockery Site
ground water was 1,1-dichloroethene at 640 ug/L. However, this compound was not
detected in the vadose zone, indicating that it is either a degradation product or that the
source for it no longer exists.
Metals, although slightly elevated (see Table 2.2), will not adversely impact the ground water
since the metals have been immobilized by the vadose zone soils.
Lower Dockery Site
Potential remediation levels for the Lower Dockery Site are provided in Table 3.7. The VIP
model estimated that acetone would be found in the ground water at 4 ug/L, well below its
PPLV of 3500 ug/L. However, acetone was not detected in the Lower Dockery Site ground
water (Table 3.5). Six organic compounds were detected in the Lower Dockery Site
ground water: bis(2-ethylhexyl)phthalate, chloroform, 1, 1-dichloroethane, 1, 1-dichloroethene,
and trichloroethene, and 1,1,1-trichloroethane (Table A-25).
Additional evidence that the ground water was impacted by a former contaminant slug Is
Indicated by the fact that two chemicals found in the ground water (1, 1-dichloroethene and
chloroform) were not found in the vadose zone. 1,1,1-Trichloroethane (1,1,1-TCA) was
found both in the vadose zone (32 ug/kg) and the ground water (51 ug/L) as well as 1,1-
dichloroethane (1,1-DCA; 43 ug/L in ground water versus <1 predicted by the VIP model).
Further impacts on the ground water from 1,1,1-TCA or 1,1-DCA in the vadose zone are
Macon/Dockery FS 3-12 July 5, 1991
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expected to be insignificant, based on the lack of a concentrated source area and the
estimated fate of the trace amounts of 1, 1, 1-TCA and 1, 1-DCA remaining In the vadose
zone.
3.2.3.4 Surface Waters
Surface water from the Site drains into Solomons Creek and finally into the Pee Dee River
(Sectlon 2.1.2). Potential ARARs for surface water include Federal Ambient Water Quality
Criteria (AWQC, 1986). As seen in Table 3.0, the current use and predicted Mure
carcinogenic and non-carcinogenic risks associated with Site surface waters were all within
acceptable risks (Sirrine, 1991b). Therefore, remediation of surface water at the Site is not
necessary and will not be further considered in this FS.
3.2.3.5 Sediments
There are no promulgated Federal or State quality standards for sediments. However, as
seen in Table 3.0, the current use and predicted future carcinogenic and non-carcinogenic
risks associated with Site sediments were all within acceptable risks (Sirrine, 1991 b).
Therefore, remediation of sediment at the Site is not necessary and will not be further
considered in this FS.
3.2.3.6 Vessels
As discussed in Section 2, there are several vessels on the Macon Site (tanks, tankers, and
vats) that contain waste materials (Section 2), A relevant and appropriate requirement for
off-site disposal of vessel contents is RCRA (Resource Conservation and Recovery Act)
guidance. As a preliminary step for identifying off-site disposal alternatives, RCRA guidance
was used to determine if the vessel contents were hazardous according to the Toxicity
Macon/Dockery FS 3-13 July 5, 1991
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Characteristics Leaching Procedure (TCLP) and selected hazard characteristics (i.e.,
lgnitability and corrosivity). Consequently, vessel contents were sampled and analyzed for
these parameters.
Results of the sampling and analysis were presented in Section 2 (Table A-31). As seen
in Table A-31, only 3 vessels contained waste that could be considered hazardous for off-
site disposal under RCRA guidance: solids in Vat 4 (TCLP lead at 7 mg/L), oil In Tank 3
(TCLP lead at 15 mg/L), and oil in Tank 4 (TCLP lead at 10 mg/L). The oil in Tanks 3 and
4 Is most likely used engine oil that was contaminated with tetraethyl lead (former antiknock
agent in gasoline). Used oil is currently not considered a hazardous waste. Contents of
the remaining vessels are not considered hazardous wastes. Off-site remedial alternatives
for the vessels will consider these data and RCRA guidance. Additional characterization
may be necessary depending on the waste disposal method that is selected.
3.3 AREAS OF POTENTIAL REMEDIATION
Site media that pose significant risks to human health and the environment and/or exceed
ARARs represent areas of potential remediation. Potential human health and environmental
risks were evaluated in the Risk Assessment (Sirrine, 1991b). Potential ARARs and site-
specific remediation levels were evaluated in the preceding section (Section 3.2). The
following sections discuss the specific areas of potential remediation.
3.3.1 Ground Water
The results of the RI and the predicted future residential use scenario (Table 3.0) indicate
that ground water exceeds risk levels at the Site. While the existing public water supply
makes construction of a supply well in this area unlikely, ground water remediation
alternatives will be developed on a risk basis as a protective measure.
Macon/Dockery FS 3-14 July 5, 1991
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Ground-water extraction modeling was performed considering that extraction and treatment
(as necessary) of all ground water from the Site with concentrations of voes exceeding
MCLs. The results of the modeling of these extraction options are presented In Section
3.4.1 and Appendix C.
3.3.2 Surficial Soils
As discussed in Section 3.2.3.2, surficial soils at the Site do not require remediation.
3.3.3 Subsurface Soils
The potential need for remediation of subsurface soils is based on the ability of a chemical
to migrate (through leaching) and thereby impact ground water at concentrations exceeding
ground-water ARARs. As discussed in Section 3.2.3.3, it appears as though a slug of
contaminant has migrated from the source area, through the vadose zone, and into the
ground water. Interim remediation by the EPA in 1982-1983 removed significant portions
of the source areas.
Only the vadose zone at the Upper Macon Site (i.e., Lagoon 7) may require remediation
to mitigate the potential effects on ground water of volatile organic compounds.
Remediation of other vadose zone soils is not required, for the following reasons:
-contaminant slugs have already passed through the vadose zone
-further slugs of contamination have been eliminated by the removal of the
concentrated source areas during the interim remediation conducted by the EPA
-inorganic chemicals remaining in the vadose zone, although above background
levels, are not expected to impact the ground water
-organic chemicals remaining in the vadose zone are not expected to adversely
impact the ground water
Macon/Dockery FS 3-15 July 5, 1991
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-there is no direct exposure route from vadose zone chemicals to humans or the
environment
-In the unlikely event that contaminants migrate from the vadose zone to ground
water above MCLs, they could be captured and removed from the ground water
by ground water extraction.
From a human health point of view, there is not a direct exposure route with chemicals In
the vadose zone. Consequently, chemicals In the vadose zone do not pose any direct
threat to human health or the environment. However, there are relatively concentrated
levels of PAHs in the waste in Lagoon 10 at the Lower Macon Site. These wastes currently
do not pose a risks nor are expected to impact the ground water. Lagoon 10 is covered
by a temporary cap that was built during the initial Site remediation in 1982-1983. Since
this cap is temporary, there is the possibility that the cap could fail, thus potentially exposing
humans and the environment to impact from these wastes. Consequently, remedial
technologies will be examined (Section 4) and potential remedial alternatives developed
(Sections 5 and 6) for Lagoon 10 .
3.3.4 Surface Waters
As discussed in Section 3.2.3.4, surface water at the Site does not require remediation.
3.3.5 Sediments
As discussed in Section 3.2.3.5, sediment at the Site does not require remediation.
3.3.6 Vessels
A relevant and appropriate requirement for off-site disposal of vessel contents is RCRA
guidance. Additional characterization may be necessary depending on the disposal
alternatives that are considered .
Macon/Dockery FS 3-16 July 5, 1991
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3.4 REMEDIAL DESIGN BASIS
Identification of the media at the Site potentially requiring remediation and the
physicaVchemical properties of contaminants related to former disposal operations at the
Site is necessary for the evaluation of potential remedial alternatives. Areas of potential
remediation were presented in the previous section (Section 3.3).
3.4.1 Ground Water
The assessment of potential ground-water recovery technologies at the Site Is based on RI
data (Sirrine, 1991a). Analytical modeling of ground-water flow and chemical transport at
the Site, based on RI data, was used to estimate the distribution and concentrations of
contaminants present at the Site (Appendix C). Next, analytical models describing ground-
water flow and hydraulics were used to develop a conceptual design for the location of
extraction wells for potential ground-water remediation scenarios. Descriptions of the
models, input parameters and site-specific assumptions are presented in Appendix C.
Aquifer characteristics were used to complete this remedial design analysis. Based on
these characteristics, ground-water extraction could require extraction wells operating at
pumping rates ranging from 2 to 4 gallons per minute (gpm) per well, depending on
anticipated variations in aquifer conditions (saturated thickness, transmissivity, and
storativity) at each well location.
Because of the extremely low yield of the aquifer, ground-water extraction wells would be
screened through the saprolite and into the relatively competent bedrock ('1ransition zone").
This zone generally consists of extremely fractured bedrock with zones of saprolite.
Capture effectiveness would be confirmed through aquifer response measurements
conducted in select wells during construction of the overall extraction system.
Macon/Dockery FS 3-17 July 5, 1991
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Assuming withdrawal of all ground water containing Site-related chemicals above MCLs, the
reasonable maximum extraction flow rate would be on the order of 41 gallons per minute
for the entire Site (5 wells each pumping at 4 gpm at Upper Macon, 3 wells each pumping
at 3 gpm at Lower Macon, 2 wells each pumping at 4 gpm at Upper Dockery, and 2 wells
each pumping at 2 gpm at Lower Dockery).
The evaluation of potential ground water treatment technologies must be based on
anticipated extraction rates and influent concentrations. The most conservative estimate of
influent conditions would be the combination of the maximum flow rate (41 gpm) at the
highest individual chemical concentrations detected in ground water at the Site.
Chemicals present at concentrations exceeding potential ground-water remediation levels
are limited to volatile organic compounds (VOCs), chromium, and nickel, as determined in
Sections 2 and 3.2.3.1. However, chromium is most likely an artifact from ground water
sampling procedure. while nickel is a secondary (aesthetic) MCL (see Appendix B).
3.4.2 Vadose Zone
As discussed, the vadose zone at the Upper Macon Site may adversely impact the ground
water (PCE at former Lagoon 7) while the vadose zone at the Lower Macon Site (i.e.,
Lagoon 10) may result in future exposure to the buried PAH compounds. The estimated
volume at Lagoon 7 that would require remediation is 1300 cubic yards. The estimated
volume of remediation at Lagoon 10 is 1000 cubic yards. Waste at Lagoon 10 Is estimated
to be from 2 to 10 feet below the land surface.
3.5 SUMMARY OF REMEDIAL RESPONSE OBJECTIVES
Three types of ARARs were examined: action-specific, location-specific, and chemical-
specific. Detailed evaluation of action-specific ARARs is dependent on the specific remedial
Macon/Dockery FS 3-18 July 5, 1991
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response alternatives that will be considered. These will be evaluated in Section 6, Detailed
Analysis of Alternatives. Two location-specific ARARs (actually, "To Be Considered") were
retained: the Federal and State ground-water classification for the aquifer at the Site and
wetlands (Table 3.1).
Chemical-specific ARARs were examined for ground water. Retained as chemical-specific
ARARs for Site ground water are presented In Table 3.3. Twelve extraction wells with a
combined flow of 41 gpm is estimated to be necessary to extract contaminated ground
water to MCLs across the Site. Because they were not detected or are not significant,
semivolatile organic compounds, pesticides, and PCBs will not be remediated In ground
water.
Remediation levels for surficial soils were based on the Risk Assessment (Sirrine, 1991b)
and on RCRA action levels. Although the Macon Site had a carcinogenic risk slightly above
10-4, primarily due to arsenic, it has concluded that surface soils do not require remediation
since arsenic is only slightly above background levels, there is a high degree of uncertainty
associated with the arsenic risk factor, and the maximum arsenic concentration (5.8 mg/kg)
Is well below the RCRA soil action level for surface soils of 80 mg/kg.
Remediation levels for the vadose zone were based on RI data and on VIP modeling
results. The Upper Macon Site vadose zone is the only area that could potentially
adversely impact Site ground water. The area of concern is centered around former
Lagoon 7 which accounts for a volume of approximately 1300 cubic yards. The primary
chemical of concern in the Upper Macon Site vadose zone is tetrachloroethene (PCE).
The PAHs in Lagoon 10, although not expected to adversely impact the ground water, may
have the potential to pose a risk in the future from direct contact. The potential remediation
volume for Lagoon 10 is estimated to be 1000 cubic yards.
Macon/Dockery FS 3-19 July 5, 1991
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Site surface water and sediment do not pose significant risk and thus do not require
remediation. A relevant and appropriate ARAR for off-site disposal of vessel contents Is
RCRA guidance and regulations.
Macon/Dockery FS 3-20 July 5, 1991
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Table 3.2 Comparison of Drinking Water, Ground Water, and
Contract Required Detection/Quantitation Limits for Chemicals Detected
in Macon/Dockery Ground Water
Maximum
Chemical Cone. Well
Class Chemical (ua/L) Number
Antimony 29 16
Barium 5710 9
Bervllium 22 6
Cadmium 6 16
Chromium 1400 5
Lead (CERCLA level is 15 ua/I) 76 6
Manqanese 6130 5
Mercurv 0.3 15
Nickel 2120 9
Vanadium 627 5
Zinc 730 6
Cyanide 10.4 10
B lsophorone (PPLV = 70 ua/L)(5) 2 9, 19
V Acetone (PPLV = 3500 ua/L)(5) 59 20
V Benzene 6 19
V Chloroform 17 1
V 1 , 1 Dichloroethane (PPLV 3500)(5) 190 9,19
V 1, 1-Dichloroethene 640 15
V 1,2-Dichloroethene (total) 150 5
V Methvlene Chloride 2 2A
V Tetrachloroethene 44 5
V Toluene 7 9
V 1, 1, 1 -Trichloroethane 500 15
V Trichloroethene 290 2
V Vinyl Chloride 510 9
V Xvlenes (Total) 9 19
SOWA
MCL
(ua/L)
NA
1000 (2)
1 /3)
10
100
50
50 (4)
2
100 (3)
NA
5000 (4)
200
NA
NA
5
NA
NA
7
cis-70:trans-100
5 (3)
5
1000
200
5
2
.•• :::010:000
SOWA MCL = Safe Drinking Water Act Maximum Contaminant Level (40 CFR Part 141.61)
North Carolina Drinking Water Standards from NCAC Title 10, Ch.10, Subsection 10D
North
Carolina
Drinking
Water
Standard
(ug/L)
NA
1000 (2)
1 /3) · .
10
50
50
50 (4)
2
100 (3)
NA
5000 (4)
200
NA
NA
5
NA
NA
7
cis-?O;trans-100
5 (3)
5
1000
200
5
2
. 10;000 : .. : .:
North Carolina Ground-Water Standards for ground water class GA from NCAC Title 15A, Ch.2, Oct. 1990
NA = Not Available
(1) = CERCLA detection limits (inorganics) and quantitation limtts (organics)
(2) = Proposed revised MCL for barium is 2000 ug/L
(3) = Proposed MCL (pMCL)
(4) = Secondary (aesthetic) standard
(5) = Preliminary Pollutant Limit Value (PPLV) derived in Appendix D of the FS
I = Inorganic; B = E!ase Extractable Organi_c Compound; V = Volatile Organic Compound
· ····=,=c•::=::,=,:=:,:··,==:-:-:?': = Standard is less than detection or quantitation limlt
North
Carolina Contract
Ground Required
Wat.er Detection or
Quality Quantitation
Standard Limits (1)
(ua/L) (ua/L)
NA 60
1000 200
NA 5
5 5
50 10
50 3
50 15
1 .1 0.2
150 40
NA 50
5000 20
154 10
NA 10
NA 10
....•. :·::·.-1•.):•·••··· 5
0.19 5
.. ···•· ·•• < 5
7 5
cis-70;trans-70 5
5 5
0.7 5
........ • 1000),:::•:••· 5
200 5
2.6 5
· ·: 0:0.15? ·• · 10
._.:-::,:·:: ,-·--·:·, :·. 5
7/3/91, NC-ARAR.MD
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Table 3.3 Ground-Water Remediation Levels For the Macon/Dockery Site
Chemical
Antimony
Barium
Beryllium
Cadmium
Chromium
Lead
Manganese
Mercury
Nickel
Vanadium
Zinc
Cyanide
B lsophorone
V Acetone
V Benzene
V Chloroform
V 1, 1 -Dichloroethane
V 1, 1 -Dichloroethene
V 1,2-Dichloroethene (total)
V Methylene Chloride
V Tetrachloroethene
V Toluene
V 1, 1, 1 -Trichloroethane
V Trichloroethene
V Vinyl Chloride
V Xylenes (Total)
Maximum
Cone. Well
(ug/L) Number
29 16
5710 9
22 6
6 16
1400 5
78 6
6130 5
0.3 15
2120 9
627 5
730 6
10.4 10
2 9, 19
59 20
6 19
17 1
190 9,19
640 15
150 5
2 2A
44 5
7 9
500 15
290 2
510 9
9 19
Remediation
Level
(ug/L)
60
100011)
5
5
50
15
50 (3)
1.1
100 (2)
50
5000 (3)
154
70
3500
5
5
3500
7
cis-70;trans-70
5 12)
5
1000
200
5
10
400
CERCLA Detection Limit = Contract Required Detection Limit (inorganics)
CERCLA Quantitation Limit = Contract Required Quantitation Limit (organics)
SOWA MCL = Safe Drinking Water Act Maximum Contaminant Level (40 CFR Part 141.61)
-------
Source
CERCLA Detection Limit
SOWA MCL/NC Ground Water Standard
CE RCLA Detection Limit
NC Ground Water Standard
NC Ground Water Standard
CERCLA Level
SOWA MCL/NC Ground Water Standard
NC Ground Water Standard
SOWA MCL
CERCLA Detection Limit
SOWA MCL/NC Ground Water Standard
NC Ground Water Standard
Preliminarv Pollutant Limit Value IPPLVl
Preliminarv Pollutant Limit Value (PPLVl
CERCLA Quantitation Limit
CERCLA Quantitation Limit
Preliminary Pollutant Limit Value (PPLV)
SOWA MCL/NC Ground Water Standard
NC Ground Water Standard
SOWA MCL/NC Ground Water Standard
CERCLA Quantitation Limit
SOWA MCL/NC Ground Water Standard
SOWA MCL/NC Ground Water Standard
CERCLA Quantitation Limit
CERCLA Quantitation Limit
NC Ground Water Standard
North Carolina Ground Water Standards for ground water class GA from NCAC Title 15A, Ch.2, Oct. 1990
Preliminary Pollutant Limit Value (PPLV) derived in Appendix D of the FS
(1) = Proposed revised MCL for barium is 2000 ug/L
(2) = Proposed MCL (pMCL)
(3) = Secondary (aesthetic) standard
I= Inorganic; B = Base Extractable Organic Compound; V = Volatile Organic Compound 7/2/91, GW-REM.MD
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Table 3.4 (cont'd)
Potential Soil Remediation Levels Estimated
Upper Macon Site Estimated Leachate Maximum
Depth Time Cone. Estimated
to To Reach From Ground
Max. Ground Ground Vadose Water
Vadose Water Water Zone (VIP) Cone.
Chemical Cone. (Feet) (Days) (ug/L) (ug/L)
I Inorganics (mg/kg for the vadose zone)
Antimony 7.4 27 5 feet/50 yrs. NA NA
Arsenic 4.5 27 <7 feet/50 yrs. NA NA
Barium 337 10 ND
Beryllium 4.1 10 ND
Cadmium 30 27 1 0 feet/50 yrs. NA NA
Chromium 462 10 <6 feet/50 yrs. NA NA
Cobalt 119 10 < 8 feet/50 yrs. NA NA
Copper 176 10 < 6 feet/50 yrs. NA NA
Lead 62 20 5 feet/50 yrs. NA NA
Manganese 1810 10 <5 feet/50 yrs. NA NA
Mercury 0.16 20 5 feet/50 yrs. NA NA
Nickel 263 10 5 feet/50 yrs. NA NA
Selenium 0.45 27 15 feet/50 yrs. NA NA
Thallium 0.58 27 ND
Vanadium 258 10 ND
Zinc 137 27 7 feet/50 yrs. NA NA
NA = Not Applicable ND = Not Determined (no Kd value found)
(1) Ground-waterremediation level provided only for chemicals predicted to
impact the ground water
(2) Not detected in the Upper Macon Site ground water
(3) Maximum isophorone concentration was 2 ug/L in the ground water at the Upper Macon Site'
(4) PPLV; see Appendix D
(5) Maximum acetone concentration was 42 ug/L in the ground water at the Upper Macon Site
(6) Maximum tetrachloroethene (PCE) concentration was 44 ug/L in the ground water
at the Upper Macon Site; estimated PCE concentration was 2 ug/L with a half-life
of 300 days and 80 ug/L with no half-life (i.e., no degradation).
7/2/91, VAD-UM.MD
Ground
Water
Remediation
Level (1)
(ug/L)
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Potential Soil Remediation Levels Estimated
Upper Macon S~e Estimated Leachate Maximum I Depth Time Cone. Estimated Ground
to To Reach From Ground Water
Max. Ground Ground Vadose Water Remediation
I Vadose Water Water Zone (VIP) Cone. Level (1)
Chemical Cone. (Feet) (Days) (ug/L) (ug/L) (ug/L) I Semivolatiles (ug/kg for the vadose zone)
I Benzoic Acid 98 27 2800 1 <1
Phenol 3000 20 Degrades NA NA
Acenaphthene 180 27 1200 2 1 (2)
I Acenaphthylene 120 27 Degrades NA NA
Anthracene 100 27 Immobile NA NA
Benzo(a)anthracene 350 27 Immobile NA NA
I Benzo(a)pyrene 260 27 Immobile NA NA
Benzo(b)fluoranthene 470 27 Immobile NA NA
Benzo(g,h,Q perylene 110 27 Immobile NA NA
I Benzo(k)fluoranthene 470 27 Immobile NA NA
bis(2-Ethylhexyl) phthalate 2900 27 Immobile NA NA
Chrysene 600 27 Immobile NA NA
Dibenzo(a,h)anthracene 63 27 Immobile NA NA
I Dibenzofuran 1500 10 Immobile NA NA
Di-n-butyl phthalate 180 20 10000 <1 <1
Fluoranthene 1300 10 Immobile NA NA -Fluorene 1400 10 Degrades NA NA
lndeno(1,2,3-cd)pyrene 120 27 Immobile NA NA
lsophorone 810 27 1300 7 4(3) 700(4)
I 2-Methylnaphthalene 43000 10 Immobile NA NA
Naphthalene 22000 10 Degrades NA NA
Phenanthrene 4700 10 Degrades NA NA
I Pyrene 1400 10 Degrades NA NA I Volatiles (ug/kg for the vadose zone)
Acetone 6100 10 400 63 33(5) 3500(4)
I Benzene 2 10 Degrades NA NA
2-Butanone 16000 10 Degrades NA NA
Chloroform 2 10 470 <1 <1
1, 1-Dichloroethane 4 10 Degrades NA NA I 1,2-Dichloroethene (totaQ 51 10 Degrades NA NA
Ethyl benzene 240 27 2000 2 1 (2)
2-Hexanone 5 10 700 <1 <1 I Methylene Chloride 480 27 1500 <1
4-Methyl-2-Pentanone 4900 10 1100 1 <1
Tetrachloroethene 31000 10 1500 3 2-80(6) 5
I Toluene 46000 27 Degrades NA NA
Trichloroethene 49 10 650 <1 <1
Xylenes (TotaQ 15000 10 Degrades NA NA
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I Table 3.5
Potential Soil Remediation Levels Estimated
Lower Maco~ Site-Lagoon #1 O Estimated Leachate Maximum •• Depth Time Cone. Estimated Ground
to To Reach From Ground Water
Mex. Ground Ground Vadose Water Remediation
Vadose Water Water Zone (VIP) Level (t) I Chemical Cone. Feet Das u L u /L
Semivolatiles u for the vadose zone
Benzoic Acid 5300 28 2900 26 13(2)
I Acenaphthene 31000 28 1300 310 152(3)
Acenapthylene 310000 28 Degrades NA NA
Anthracene 160000 28 Degrades NA NA
Benzo(a)anthracene 150000 28 Immobile NA NA
I Benzo(a)pyrene 140000 28 Immobile NA NA
Benzo(b)fluoranthene 120000 28 Immobile NA NA
Benzo(g, h,i} pery lene 60000 28 Immobile NA NA
Benzo(k)fluoranthene 120000 28 Immobile NA NA
I bis(2-E1hylhexy~phthalate 1 t000 21 Immobile NA NA
Chrysene 140000 28 Immobile NA NA
Oibenzofuran 18000 28 Immobile NA NA
Dibenzo(a,h)anthracene 30000 28 Immobile NA NA
I Di-n-bu1yl phthalate 3200 21 10000 4 2(3)
Fluoranthene 200000 28 Degrades NA NA
Fluorene 250000 28 Degrades NA NA
lndeno(1,2,3-cd)pyrene 47000 28 Immobile NA NA
I 2-Methylnaphtha lene 14000 28 Immobile NA NA
Naphthalene 3100000 28 Degrades NA NA
Pherianthrene 1300000 28 Degrades NA NA
P rene 410000 28 De rades NA NA
I Volatiles u /k for the vadose zone
Acetone 3500 21 1000 36 t8(4) 3500
Benzene 25000 28 Degrades NA NA
2-Butanone 8 28 Degrades NA NA
18 Ethyl benzene 8600 28 1900 56 28(3)
Methylene Chloride 240 11 570 <1
Styrene 12000 28 7000 21 10(3)
Tetrachloroethene 48 28 Degrades NA NA
I Toluene 110000 28 2100 770 380 (3)
5 28 3000 <1 <1
23000 28 De rades NA NA
for the vadose zone
I Arsenic 2.3 21 < 7 feet/50 yrs. NA NA
Barium 24 11 ND
Beryllium 0.26 11 ND
Chromium 39 21 < 6 feet/50 yrs. NA NA
I Cobalt 10 11 <8 feet/50 yrs. NA NA
Copper 18 2t <6 feet/50 yrs. NA NA
Lead 33 11 < 5 feet/50 yrs. NA NA
Manganese 132 11 < 5 feet/50 yrs. NA NA
I Vanadium 42 21 ND
Zinc 27 27 < 7 feet/50 yrs. NA NA
I NA ~ Not Applicable ND = Not Determined (no Kd value found)
(1) Ground-water remediation level provided only for chemicals predicted to
impact the ground water
{2) Benzoic acid concentration in the Lower Macon Site ground water was 3 ug/1
I (3) Not detected in the ground water at the Lower Macon Site
(4) Acetone concentration in the Lower Macon Site ground water was 7 ug/I
~-7/2/9t, VAD-L 10.MD
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Potential Soil Remediation Levets Estimated
Lower Macon Site-lagoon #11 Estimated Leachate Maximum •• Depth Time Cone. Estimated Ground
to To Reach From Ground Water
M8X. Ground Ground Vadose Water Remediation
Ve.dose Water Water Zone (VIP) Level (1) I Chemical Cone. Feet u /L u /L
Semivolatiles u /k for the vadose zone
Acenaphthene 330 28 1300 3 2(2)
Acenapthylene 5200 28 Degrades NA NA I Anthracene 2300 28 Degrades NA NA
Benzo(a)anthracene 3000 28 Immobile NA NA
Benzo(a)pyrene 4100 28 Immobile NA NA
I Benzo(a)pyrene 2100 21 Immobile NA NA
Benzo(a)pyrene 530 11 Immobile NA NA
Benzo(b)fluoranthene 3500 28 Immobile NA NA
Benzo(g,h,i)perylene 1300 28 Immobile NA NA
I Benzo (k)fluoro.nthene 3500 28 Immobile NA NA
bis(2-Ethylhexyl)phthalate 66 2t Immobile NA NA
Chrysene 3700 28 Immobile NA NA
Oibenzofuran 320 28 Immobile NA NA
I Dibenzo(a.h)anthracene 640 28 Immobile NA NA
Oi-n-butyl phthalate 43 21 10000 <1 NA
Oi-n-octyl phthalate 190 21 Immobile NA NA
Fluoranthene 4700 28 Degrades NA NA
I Fluorene 3300 28 Degrades NA NA
lndeno(1,2,3-cd)pyrene 930 28 Immobile NA NA
2-Methylnaphthalene 10000 28 Immobile NA NA
Naphthalene 18000 28 Degrades NA NA
I Phenanthrene 11000 28 Immobile NA NA
Phenanthrene t400 21 Immobile NA NA
Phenanthrene 630 11 Immobile NA NA
P rene 7300 28 De rades NA NA • Volatiles u /k for the vadose zone
27 21 Degrades NA NA
1 21 1900 <1 NA
3 21 De rades NA NA
I /k for the vadose zone
Arsenic 1.6 21 < 7 feet/50 yrs. NA NA
Barium 45 11 ND
Beryllium 0.48 11 ND
I Cadmium 3.9 28 < 1 O feet/50 yrs. NA NA
Chromium 30 21 < 6 feet/50 yrs. NA NA
Cobalt 2.1 11 < 8 feet/SO yrs. NA NA
Copper 4.9 21 < 6 feet/SO yrs. NA NA
I Lead 12.4 11 < S feet/50 yrs. NA NA
Manganese 68 11 < S feet/50 yrs. NA NA
Vanadium 39 28 ND
Zinc 54 28 < 7 feet/SO yrs. NA NA
I NA -Not Applicable ND = Not Determined (no Kd value found)
I
(1) Ground-water remediation level provided only for chemicals predicted to
impact the ground water
(2) Not detected in the ground water at the Lower Macon Site
I 7/2/91, VAD-L11.MD
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I Table 3.7 .-Potential Vadose Zone Remediation Levels Estimated
Upper Dockery Site Estimated Leachate Maximum
Depth Time Cone. Estimated Ground
to To Reach From Ground Water
I Max. Ground Ground Vadose Water Remediation
Vadose Water Water Zone (VIP) Cone. Level (1)
Chemical Cone. (Feet) (Days) (ug/L) (ug/L) (ug/L)
I I Semivolatiles (ug/kg for vadose zone)
bis(2-Ethylhexyl)phthalate 620 17 Immobile NA NA
Di-n-buty1 phthalate 42 13 5000 <1 <1
Diethyl phthalate 9500 17 1000 .10 30(2)
I Dimethyl phthalate 1600 13 700 14 6(2)
lsophorone 76 17 850 <1 <1
2-Methllehenol 97 17 600 1 <1
I I Volatiles (u9/k9 for vadose zone)
Acetone 9200 13 420 75 32(3) 3500(4)
2-Butanone 16000 17 Degrades NA NA
I Methylene Chloride 500 17 800 2 1 (2) 5
4-Methyl-2-Pentanone 5000 17 700 5 2(2)
Toluene 460 17 Degrades NA NA
I Tetrachloroethene 540 17 2500 <1
1, 1, 1 -Trichloroethane 630 17 1600 <1 <1
Trichloroethene 530 17 1200 <1 <1 -Xllenes (TotaQ 390 17 Degrades NA NA
J 1norganics (mg/kg for vadose zone)
Arsenic 5.9 17 <7 feet/SO yrs. NA NA
Barium 2990 17 ND I Beryllium 6.5 17 ND
Chromium 1970 17 6 feet/50 yrs. NA NA
Cobalt 326 17 8 feet/50 yrs. NA NA
I Copper 193 17 6 feet/SO yrs. NA NA
Lead 58.1 17 <5 feet/50 yrs. NA NA
Manganese 19000 17 5 feet/50 yrs. NA NA
I Nickel 252 17 <5 feet/50 yrs. NA NA
Vanadium 672 17 ND
Zinc 106 17 < 7 feet/SO yrs. NA NA
I NA = Not Applicable ND = Not Determined (no Kd value found)
(1) Ground-water remeciation level provided only for chemicals predictec to
I impact the ground water
(2) Not detectec in the Upper Dockery Site ground water
(3) Maximum acetone concentration was 59 ug/L in the Upper Dockery Site ground water
I (4) PPLV; see Appendix D
I 7/2/91, VAD-UD.MD
119
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·-Table 3.8
Potential Vadose Zone Remediation Levels Estimated I Lower Dockery Stte Estimated Leachate Maximum
Depth Time Cone. Estimated Ground Max. to To Reach From Ground Water I Vadose Ground Ground Vadose Water Remediation
Cone. Water Water Zone (VIP) Cone. Level (1) Chemical (ug/k ) (Feet) (Days) (ug/L) (ug/L) (ug/L)
I Semivolatiles (ug/kg for the vadose zone)
Pentachlorophenol 300 14 4300 <1 <1 2,4,5-Trichlorophenol 170 14 10000 <1 <1 bis (2-Ethylhexyl) phthalate 1400 21 Immobile NA NA I Phenanthrene 470 21 Immobile NA NA I Volatiles (u9/kg for the vadose zone)
Acetone 720 21 1000 7 4(2) 3500(3) I Benzene 8 21 Degrades NA NA 2-Butanone 54 21 Degrades NA NA 1, 1-Dichloroethane 26 21 920 <1 <1 I Ethylbenzene 10 21 1500 <1 <1 2-Hexanone 3 14 950 <1 <1 Methylene Chloride 28 14 600 <1 <1 I 4-Methyl-2-Pentanone 52 14 600 1 <1 Toluene 87 21 Degrades NA NA 1, 1, 1-Trichloroethane 32 21 Degrades NA NA -Xylenes (TotaQ 53 21 Degrades NA NA [ 1norganics (mg/k9 for the vadose zone)
Arsenic 1.7 21 <7 feet/50 yrs. NA NA Barium 228 14 ND I Beryllium 0.7 14 ND Chromium 252 14 < 6 feet/50 yrs. NA NA Cobalt 99 14 <8 feet/50 yrs. NA NA I Copper 167 14 <6 feet/50 yrs. NA NA Lead 6.1 14 <5 feet/50 yrs. NA NA Manganese 1480 14 <5 feet/yrs. NA NA I Nickel 251 14 <5 feet/50 yrs. NA NA Vanadium 232 14 ND
Zinc 52 14 < 7 feet/50 yrs. NA NA
NA = Not Available ND = Not Determined (no Kd value found) (1) Ground-water remediation level provided only f_or chemicals estimated to impact the ground water
(2) Acetone was not detected in the ground water at the Lower Dockery Site (3) PPLV; see Appendix D
7/2/91, VAD-LD.MD
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4.0 IDENTIFICATION OF POTENTIAL TECHNOLOGIES
The purpose of this initial screening effort is to identify a list of generally applicable
remediation technologies that can be grouped into remedial alternatives for the Site.
Remedial action technologies evaluated include treatment alternatives, physical controls, and
institutional measures that can be used individually or in combination with other
technologies to eliminate or control threats to public health or environmental concerns
associated with the Site. The potential remedial measures must be technically feasible
considering the Site conditions and the identified chemicals. The specific technologies have
been individually screened on the basis of the Site conditions, waste characteristics, and
technical requirements. Preliminary cost information has been used to screen out the more
costly technologies which do not provide additional remedial effectiveness over those
retained. A series of general remedial alternatives has been developed for Site media using
retained technologies.
Certain technologies have been retained that may only apply to a discrete portion of a
medium but may be useful in forming an overall alternative or disposing of a minor amount
of material. Specific technical and institutional requirements regarding implementation of
technologies are described more completely in the "Detailed Analysis of Alternatives"
(Section 6).
4.1 SCREENING CRITERIA
The National Contingency Plan (NCP) and Superfund Amendments and Reauthorization Act
(SARA) provide basic criteria for screening of technologies. The criteria are:
•
•
•
Macon/Dockery FS
Effectiveness
Implementability
Cost
4-1 July 5, 1991
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4.1.1 Effectiveness
Technologies must be compatible with the waste and Site conditions and must protect
public health and the environment. To accomplish this they must be effective in reducing
or eliminating any short-term and long-term risk to human health or environment directly
associated with the Site to appropriate levels. The technology Itself must not have adverse
impacts on the environment, public health, or public welfare. Technologies for which Site
waste characteristics or Site conditions clearly limit their effectiveness or which do not
provide adequate protection of the environment, public health, and public welfare have been
eliminated. Technologies which have not demonstrated effectiveness at similar sites have
also been eliminated from further consideration.
4.1.2 Implementability
implementability addresses both the technical and institutional feasibility of applying a
technology. Technologies have been evaluated based on the technical feasibility and
availability of resources and equipment, and the administrative feasibility of implementing
them. The nature of the technology should be such that, in the physical setting associated
with the Site, it can be implemented in a cost effective and timely manner. In addition, the
implementation of the technology should not elicit substantial public concerns in the
community. Site accessibility, available area, and potential future use of the property may
also affect the implementation of certain technologies. Technologies that are unworkable
based on site conditions have been eliminated. Mobilization and permitting requirements,
where applicable, must be workable and previously demonstrated at equivalent projects.
Preliminary consideration has also been given to regulatory constraints such as handling,
disposal, and treatment requirements that will effect the implementation of certain remedial
technologies. These considerations will be evaluated further for the retained technologies
when action-specific ARARs are developed. Technologies that are not technically or
administratively feasible have been removed from further consideration.
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4.1.3 Cost
Any technology which delivers similar levels of applicability, effectiveness and
implementability as other technologies but has a significantly greater cost has been
eliminated. Technologies that are equivalent in cost but are clearly less effective than other
retained technologies also are rejected. Otherwise, cost is not used as a criterion to screen
technologies at this point in the process.
4.2 LISTING OF POTENTIAL TECHNOLOGIES
The purpose of this section is to establish a preliminary list of treatment technologies that
are potentially applicable based on the considerations outlined in Section 4.1. As directed
by the NCP, appropriate technologies for the range of general response actions have been
considered. The initial list of technologies is based on past experience at other sites,
demonstrated technologies at similar hazardous waste sites, a literature review of technical
publications, EPA guidance publications, a literature search of the EPA Alternative Treatment
Technology Information Center database (ATTIC; EPA, 1991b), and Appendix D of the NCP.
Based on the areas of potential remediation identified in Section 3.2 and on the remedial
design basis presented in Section 3.3, potentially applicable technologies were identified for
the following areas of application:
•
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ground water recovery
ground water treatment
ground water disposal
soil remediation .
Technologies are divided between ground water and source control (soils). Chemicals in
ground water exceeding ARARs are volatile organics and metals. Potential treatment
technologies for metals in ground water will also be considered (Appendix B). Ground
water recovery, treatment, and discharge technologies are presented in Table 4.1.
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Potential risks to human health under baseline conditions posed by site surficial soils are
within the acceptable exposure levels defined by the NCP. The only compound in
subsurface soils that could exceed ground water ARARs through leaching is
tetrachloroethene (PCE). Soil treatment technologies are presented in Table 4.2 according
to their method of application (e.g., containment, in situ, etc.).
Site ground water exceeds some ARARs but presents no risks to human health under
current conditions. Remediation of Site surface soils, surface waters and sediments Is not
required based on protection of human health and the environment or for compliance with
applicable ARARs. The absence of significant risks posed by the Site indicates that extreme
remedial efforts are not warranted and that the evaluation of remedial technologies can be
limited to those that have demonstrated capabilities and are commercially available.
4.3 GROUND WATER CONTROL SCREENING
Ground water control refers to all elements of potential ground water remediation, including
recovery, treatment and discharge. Comprehensive ground water control alternatives will
include retained technologies for each element.
MCLs are a relevant and appropriate remediation standard for the ground water at the
Macon/Dockery Site (40 CFR 300.121 (d) (2) (A)). Current research, including full-scale
ground-water remeqiation projects, has shown that there are practical limitations in
remediating the ground-water concentrations of selected compounds to MCLs (Travis and
Doty, 1990; EPA, 1989b; EPA, 1989c; EPA, 1989d; EPA, 1990a; EPA, 1990b; Hall, 1991;
Haley et al., 1990). Limitations include sorption of contaminants to soils, specific aquifer
properties such as subsurface heterogeneity and fractures, low remediation levels (e.g.,
MCLs), and the presence of stagnation zones within the extraction system. For example,
the hydraulic conductivity for the shallow saprolite unit at the Site is 1.94E-6 cm/sec,
indicative of low permeability saturated zone. Based on the limited success at other
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remediation projects, it appears that MCLs may not be met in the ground water at the entire
Macon/Dockery Site in predictable or reasonable time frames. Ground-water recovery and
treatment, however, would contain and reduce contaminant levels.
4.3.1 Ground Water Recovery
The following technologies have been evaluated as a means of recovering contaminated
ground water for the purpose of treatment. These technologies will be coupled with the
treatment technologies in Section 4.3.2 and discharge technologies in Section 4.3.3 In
developing overall remedial alternatives.
1) Extraction Wells
Extraction wells (or recovery wells) withdraw ground water from distinct points. Multiple .
extraction wells are placed such that the zone of influence from each individual well
overlaps that from adjacent wells, thereby providing a concerted withdrawal of ground water
containing site-related chemicals.
Aquifer conditions at the Macon/Dockery Site make the use of extraction wells feasible. It
is anticipated that due to the water table conditions and heterogeneous hydraulic
characteristics of the bedrock/saprolite system at the Site, the well yields and zones of
influence will vary between individual installations across the Site. Optimization of well
locations and pumping rates will be essential in order to create the desired capture zone.
This technology is retained for further consideration.
2) Interceptor Trenches and Subsurface Drains
Trenches and drains can be used to collect ground water containing site-related chemicals
along a line located hydraulically downgradient from the source. In terms of hydraulics,
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trenches and drains behave similarly to a series of extraction wells installed along a straight
line, but extend over a more continuous zone than extraction wells. Drains are generally
passive systems, designed to allow ground water to flow into a drain under the natural
hydraulic gradient. Interceptor trenches, on the other hand, can be actively pumped to
Induce flow into the trench. Subsurface drains and interceptor trenches are more cost-
effective than extraction wells at shallow depths. However, at depths greater than about
40 feet, increasing excavation and construction costs reduce their cost-effectiveness
(EPNS00/2-87/001, 1987).
Saturated thickness of the aquifer and depth to bedrock for the portion of the Site to be
remediated is variable. Minimum depth to the top of bedrock is 50 feet. Excavation to such
a depth would be difficult. Moreover, placement of impermeable liner, geotextile, filter fabric,
collection pipes, and pumps would present further complications. Efficient collection of Site
ground water across the distributed trench line would be questionable. Therefore,
interceptor trenches or subsurface drains are not retained for further evaluation.
3) No Action
The NCP requires that the no action alternative be retained throughout the Feasibility Study
as a basis of comparison during the detailed analysis of alternatives. The no action
alternative would leave chemical residuals in ground water and rely on natural attenuation
mechanisms to bring concentrations within remediation levels.
4.3.2 Ground-Water Treatment
Compounds exceeding potential ground water remediation levels at the Site are limited to
voes and metals, and the assessment of treatment technologies can be limited accordingly.
The required level of treatment of extracted ground water will be a function of the selected
discharge option.
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4.3.2.1 Volatile Organics
1) Air Stripping
Air stripping is a mass transfer process in which volatile compounds in ground water are
transferred to an air stream, typically within a packed tower. In general, compounds with
dimensionless Henry's Law Constants (He) greater than 0.01 are readily stripped. All the
volatile organic chemicals except acetone detected at the site have He greater than 0.01.
Ground water contaminants should, therefore, be easily removed using air stripping. EPA
considers air stripping to be the best demonstrated available technology for the removal of
voes from ground water (40 CFR 142.62). A comparison of modeled maximum voe
emission rates with North Carolina allowable air standards indicates that emissions control
would not be required at the Site (Appendix G). Air stripping is a proven technology that
is effective for Site voes and will be retained for further evaluation.
2) Activated Carbon Adsorption
Activated carbon adsorption is a demonstrated technology for the removal of a large variety
of organic compounds from ground water. The VOCs present in the ground water have
organic carbon partitioning coefficients that indicate they will be effectively removed by
granular activated carbon adsorption. Carbon adsorption is a proven technology for ground
water remediation and will be retained for further evaluation.
3) Sorptive Resins
Resin adsorption is a process which may be used to extract and, if desired, recover organic
solutes from aqueous wastes. The nature of the resin adsorption process is similar to that
of carbon adsorption and the two processes may be competitive in several applications.
The most significant difference between carbon and resin adsorption is that resins are
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chemically regenerated with caustic or organic solvents while carbon is thermally
regenerated. Resins generally have less adsorptive capacity than carbon and are more
expensive. Also, relatively little information is available on the few systems that are currently
in operation leaving uncertainties regarding process effectiveness and reliability. This
technology Is not retained for further consideration.
4) Chemical Oxidation (UV-Ozone)
In chemical oxidation, the oxidation state of the treated compound is raised through addition
of chemicals. Organic compounds can ultimately be oxidized to carbon dioxide and water,
although such extensive treatment is generally not necessary. The most powerful form of
oxidation and the method of choice for ground water treatment is ultra-violet (UV) catalyzed
ozonation. Ozonation has been applied successfully for the treatment of VOCs at a number
of ground water remediation sites. Chemical oxidation will be retained for further evaluation.
5) Biological Treatment
The majority of VOCs detected in site ground water are chlorinated and not amenable to
aerobic biodegradation. They are potentially amenable to anaerobic biodegradation but
there is the possibility of forming partially degraded end products such as vinyl chloride
which would require further treatment. Anaerobic reactors are also more difficult to control
than aerobic systems. Biological treatment will not be retained for further evaluation.
6) Land Treatment
Land treatment involves applying ground water to the soil and enhancing degradation
through the addition of nutrients and oxygen. Removal of VOCs occurs through
biodegradation and volatilization. As discussed under Biological Treatment, VOCs at the
Site are not amenable to aerobic biodegradation. Also, prevailing climatic conditions at the
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site may not be conducive to year round volatilization of VOCs through land application.
For effectiveness reasons, land treatment is not feasible and will not be retained.
4.3.2.2 Metals
1) Precipitation
Precipitation is a physicochemical process in which some or all of the substances in
solution are converted into the solid phase by shifting chemical equilibrium with the addition
of coagulants. The process involves mixing, flocculation and sedimentation which may be
followed by filtration. Once coagulants have been added and mixed, the contaminated
water flows to a flocculation chamber where gentle mixing enhances interparticle contact
to form larger easily settleable particles. From the flocculation chamber, the water is
directed to a sedimentation tank for the removal of the flocculated solids. Significant
amount of sludge is produced in this process. The sludge would require further treatment
before disposal. Precipitation is an effective technology for metals that are in solution.
Based on the supplemental site sampling presented in Appendix B, site metals in ground
water are related to particulate matter. Standard precipitation would have limited
effectiveness towards particulate matter and will not be retained for further evaluation.
Filtration and coagulation are potentially more effective technologies for site metals in
ground water.
2) Filtration
Filtration is a physical process in which suspended solids are removed from solutions by
forcing the fluid through a porous media. The suspended solids are trapped or enmeshed
in the media. Typically, the media consists of either sand or sand plus anthracite coal.
As more suspended solids are trapped in the filter media, the filter becomes clogged, and
the flow through it is reduced. When this occurs, the filter media must be cleaned. The
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media is cleaned by reversing the flow through the filter and fluidizing the filter bed. The
solids are then washed from the media. The backwash water contains a high concentration
of solids which require further treatment.
Filtration can be used as a pretreatment step prior to carbon adsorption In order to remove
suspended solids which may cause plugging of the unit operation. It is also used following
precipitation/flocculation processes when a high degree of metals removal is required or to
remove flocculent material which is difficult to settle. Filtration has been identified to be a
successful treatment technology for the removal of metals.
Filtration has potential application at the Site to remove metals. Based on its easy
implementability and reliable operation, filtration is retained for further evaluation.
3) Reverse Osmosis
Osmosis is the movement of a solvent from a dilute solution through a semi-permeable
membrane to a more concentrated solution. Reverse osmosis (RO) is the application of
sufficient pressure to the concentrated solution to overcome the osmotic movement and
force the solvent to the more dilute side. This allows for a build-up of a concentrated
solution on one side while relatively pure water is transported through the membrane.
Reverse osmosis has been used to reduce the concentration of both organic and inorganic
dissolved solids, as well as low molecular weight organics such as alcohols, ketones,
aldehydes, and amines. However, RO units are subject to chemical fouling and plugging.
Also, the contaminated water may require pretreatment to remove any oxidizing materials,
and particulates. Therefore, reverse osmosis is not retained for further consideration.
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4) Coagulation
Coagulation is a physicochemical process used to agglomerate colloidal suspensions and
other small particulate matter that cannot be removed through standard filtration. Colloids
are finely divided suspended solids that maintain a net negative electrical charge on their
surfaces causing neighboring colloids to repel. These repulsive forces prevent colloids from
colliding to form larger, more settle able masses or floes.
Coagulation is the destabilization of colloids by neutralizing the forces that keep them apart.
This is accomplished by adding coagulants, which neutralize the colloidal surface charge
allowing collisions between colloids, and applying mixing energy, which increases collision
frequency between neutralized colloids and promotes colloidal agglomeration. Coagulation
is typically followed by flocculation to chemically bridge agglomerated colloidal particles to
form large settleable floes. Subsequent processes generally include sedimentation followed
by filtration. Coagulation can generate significant volumes of sludge that would require
subsequent treatment and/or disposal.
Commonly used coagulants used for metals removal include lime, ferric sulfate, ferric
chloride and alum. Coagulation is an effective technology for the removal of particulate
metals. Coagulation will therefore be retained for further evaluation.
4.3.3 Ground Water Discharge
Ground water must be discharged after recovery and treatment. The level of ground water
treatment required is a function of the selected discharge option. Potential methods for the
discharge of treated ground water are listed below.
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1) Surface Water Discharge
Surface water discharge may include the discharge of treated ground water into a stream,
river, or storm sewer. Site ground water would be discharged to Solomons Creek because
of Its proximity to the Site. Surface water discharge would require a National Pollutant
Discharge Elimination System (NPDES) permit. Surface water discharge is technically
feasible and will be retained for further evaluation.
2) Horizontal Infiltration Gallery
With horizontal infiltration, the treated ground water is pumped into trenches lined with
gravel and allowed to percolate into the soil. A positive hydraulic head is the driving force
behind the system, as opposed to an active pumping system injecting the water into the
subsurface. The success of this method is dependent on vadose zone acceptance of the
treated water. An approved method of percolation testing would be required to determine
permissible application rates of treated water. The infiltration gallery must be located so that
recharge to the aquifer does not interfere with the performance of the extraction system.
The feasibility of this technology is dependent on the extraction rate and the allowable
application rate for Site soils and suitable application areas. Any infiltration galleries would
have to be located downgradient of the extraction system to avoid interfering with the
ground water capture zones. A significant portion of any such water would eventually
discharge into Solomons Creek. Infiltration galleries will be retained provisionally pending
a final determination of the allowable application rates.
3) Injection Wells
Treated ground water could be discharged to the subsurface environment by injection
wells. Although underground injection is a proven technology for treated ground water
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discharge, the State of North Carolina prohibits its use (G.S. 143-214.2{b)}.
technology will not be retained for further evaluation.
This
4) Publicly Owned Treatment Works (POTW)
The shortest distance to the municipal sewer from the Site is approximately 1 mile. There
are no plans to expand sewer service towards the Site in near future. Construction of a
force main and lift stations would create utility. traffic and aesthetic concerns along the
service length during construction. This option would require considerably more time to
implement and would be considerably more costly than the other discharge options.
Moreover, the treatment plant is already operating at its design capacity. It will not be able
to accommodate additional flow of contaminated water from the Site. Discharge to a POTW
is therefore not feasible based on implementability, cost considerations, and design capacity
of the treatment plant. This technology will not be retained for further consideration.
4.4 SOURCE CONTROL SCREENING
Source control measure address Site soils containing residual chemical concentrations that
are above calculated remediation levels, pose potentially unacceptable risks to human
health or could pose unacceptable risk to human health and the environment. These soils
were identified in Section 3 and are summarized below:
• Upper Macon -Former Lagoon 7; aerial extent -1250 tt2 (approx.);
tetrachloroethene exceeds calculated remediation level of.3000
µg/kg at a depth of 25 to 27 feet
• Lower Macon -Lagoon 1 O; contains approximately 940 tons of creosote wastes
Macon/Dockery FS
and solidified sludge from former Lagoon 7; temporary cover
consisting of a synthetic liner and 3-feet of backfilled clay;
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Lagoon 1 0 wastes could pose risks to human health and
environment if cover fails.
Technologies retained after this screening will be used to develop remedial action
alternatives.
4.4.1 Direct Treatment
Direct treatment refers to excavating contaminated soils and performing any necessary
pretreatment steps, such as sizing and/or slurrying the wastes, followed by on-site
treatment. Excavation will be required prior to application of all direct treatment
technologies. Control of dust and vapors during excavation would be necessary to
adequately protect human health and the environment. Excavated soils would be staged
in a secure holding area prior to on-site treatment. The costs associated with direct
treatment technologies increase as soil excavation proceeds beyond the limits of
conventional excavation equipment. Excavation beyond this limit would necessitate heavy
equipment access inside the pit, resulting in additional sloping and/or shoring requirements.
All soils excavated as a result of these requirements would be handled as potentially
contaminated and could require testing and/or treatment prior to disposal. The dimensions
of former Lagoon 7 (50 feet x 25 feet) and the depth at which PCE concentrations exceed
the calculated remediation level (27 feet) would complicate . excavation. The limited
cohesiveness of site soils would require significant benching of the excavation (2:1 side
slope), creating a hole up to 125 feet by 150 feet by 27 feet deep. While these excavation
requirements would favor the implementation of in situ technologies, the excavation of
Lagoon 7 along with that of Lagoon 1 0 will be considered for the evaluation of direct
treatment technologies. The volume of materials in Lagoon 7 is approximately 1300 cubic
yards while that in Lagoon 1 0 is approximately 1000 cubic yards.
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1) Biological Treatment
Biological treatment uses indigenous or introduced aerobic or anaerobic bacteria to
biodegrade organic compounds in soils or ground water. Biodegradation has been used
for only limited full-scale applications to date. It has been used to successfully degrade
gasoline, non-halogenated aliphatics, certain chlorinated compounds, and aromatics. There
are three different methods of utilizing biodegradation to reduce chemical concentrations
to acceptable levels: in-situ (discussed in Section 4.4.2), use of a bioreactor, and land
treatment.
Land Treatment
Land treatment involves excavation and placement of contaminated soils into a lined waste
pile where the soils are irrigated and nutrients are applied. Contaminants can potentially
be biodegraded by indigenous and introduced bacteria. Key parameters for this type of
treatment include adequate aeration, optimum temperature, pH, moisture and nutrient
contents, and the presence of the appropriate microbial population. Contaminated leachate
may require treatment and therefore must be collected when utilizing this treatment method.
An evaluation of off-gas generation would be required to determine whether treatment of
off-gasses is warranted.
Land treatment would require regular maintenance for tilling, moisture control, fertilization,
etc. Optimum temperatures for land treatment are in the range of 15'-45"C (EPNG00/9-
89/073; august 1989). Climatic conditions in this region of North Carolina are conducive
to land treatment year round except for brief periods of unseasonably cold weather during
the winter months. An enclosure can be used to maintain sufficient biodegradation
temperatures.
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Land treatment has been successfully implemented to remediate soils of creosote wastes
in a variety of soils and environments. It has been documented that land treatment can
reduce creosote waste concentrations by 80% to 90% in less than 100 days (Mahaffey, et
al.; 1990). Land treatment has been selected for the remediation of PNAs and creosote-
type materials at the following NPL sites in Region IV:
• Brown Wood Preserving (Live Oaks, FL)
• American Creosote Works Units 1 and 2 (Jackson, TN)
Clean up levels at these sites were set at 100 ppm for PNA indicator compounds. Land
treatment has also been selected for use at sites in Regions 11, Ill, V, VI, VII, and VIII. Land
treatment will be retained for further consideration for the soils containing PNAs in Lagoon
10.
Bioreactor
Biodegradation can be performed on excavated soils and sediments in the form of a slurry
fed to a bioreactor. Microbes in the reactor are supplied with required growth factors, such
as oxygen (in aerobic systems) and nutrients. Bioreactor capacity is typically less than
30,000 gallons. A typical soil slurry is approximately 20% to 30% suspended solids by
weight. Bioreactor residence time varies depending on the physical/chemical nature of the
contaminant. The residence times for treating soils contaminated with creosote wastes is
typically 10 to 14 days (ECOVA Corp., 1991). A by-product of the slurry-phase treatment
process is residual water from the slurry dewatering process, which may required treatment
prior to disposal (EPN540/2-88/004, Sept. 1988). An evaluation of off-gas generation would
be required to determine whether treatment of off-gasses is required. Sizing requirements
may affect the implementability of this technology when applied for Lagoon 1 O wastes.
Monitoring and maintenance requirements are far greater for bioreactor technologies than
for land treatment of wastes, adding significantly to the cost of operation. Bioreactor
technologies will be removed from further consideration based on effectiveness and costs.
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2) Chemical Extraction
Chemical extraction processes are used to separate contaminated sludges and soils into
the following phase fractions: organics, water, and ps1rticulate solids. Two types of
chemical extraction are liquid carbon dioxide (CO~ extraction and the BEST process.
These technologies will be considered for remediation of Lagoon 1 O wastes.
Supercritical CO2 Extraction
Certain gases may become solvents for removing organic compounds from solids and
aqueous solutions when they are kept at supercritical conditions. Liquid CO2 is the most
commonly used solvent. The extracted organics are separated with the carbon dioxide and
recovered when the CO2 is volatilized. The CO2 can then be recycled following
recompression. In order to use this technology for soils or soils treatment, the material
must be slurried so it can be pumped into the unit. Prnparation of fill materials into a
suitable slurry is a potential problem associated with this process .
An EPA study found supercritical carbon dioxide extraction to give poor recoveries of
adsorbed organics from activated carbon and synthetic resins (B.W. Wright, et al., 1986),
which may reflect the efficacy of the process on other solid residuals. Another EPA study
found this process to have removal levels greater than 40 percent for only 4 of 23 organic
compounds tested (Ehntholt, D.J., 1985). The authors theorized that low removal
efficiencies may have been due in part to an ineffective trap system (volatiles) and
adsorption on the extraction system (hydrophobic solutes). Although pilot tests have been
conducted with this type of technology, no full-scale operations have been applied.
Therefore, supercritical CO2 extraction is not considered further.
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BEST Process
Another extraction technique which has been developed is called the "BEST' (Basic
Extraction Sludge Technology) Process. It uses aliphatic amines to break down
suspensions and emulsions in sludges and contaminated soils. The BEST process consists
of two stages, a cold stage followed by a hot stage. In t~1e cold stage, sludges and soils
are mixed with the refrigerated extractant to form a mixture at about 40.F. After an
appropriate residence time is completed, the solids in the mixture are separated from the
liquid. Precipitated metal oxides formed due to the alkaline nature of the extractant are
removed with the solids. The liquid is then heated in the hot stage causing the liquid to
separate into two phases: solvenVwater and solvenVoil/organic. These two phases are
then decanted and each sent to a stripping column to remove the solvent. The solvent can
then be recycled back into the treatment process (EPN540/2-88/004, September 1988, p
63). The phases produced would require further treatment prior to disposal.
The BEST process is not as cost effective as other treatment alternatives when used to
treat limited volumes of soils or sludges such as the volumes estimated for Lagoon 10
(Resource Conservation Company, 1991). The BEST process will, therefore, not be retained
for further consideration.
3) Chemical Oxidation/Reduction
Chemical oxidation or reduction (Redox) destroys hazardous components or converts them
to less hazardous forms. The process is based on chemical reactions between the waste
and the added reactant in which the oxidation state of one of the reactants is raised and
the other is lowered. The process consists of an initial pH adjustment, addition of the redox
agent, mixing, and treatment to remove or precipitate the reduced or oxidized products.
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Oxidation
The most common oxidation process for solid residuals involves using ultraviolet (UV) light
and hydrogen peroxide or ozone to degrade petroleum hydrocarbons, halogenated
hydrocarbons, aromatic hydrocarbons, halogenated aromatics, and pesticides. The UV light
reacts with the hydrogen peroxide or ozone to produce a highly reactive radical that readily
oxidizes organic compounds.
Some of the major disadvantages of oxidation include the potential for the formation of
more toxic or more mobile compounds if the oxidation is not complete; the excess oxidation
agent required due to the interference of non-targeted compounds; and the difficulty
associated with on-site production of ozone gas (if used). Chemical oxidation of organic
compounds is more suited for waters than soils. The solids in a soil slurry would interfere
with the UV/hydrogen peroxide or ozone reaction, thereby rendering this technology
ineffective. Chemical oxidation is therefore removed from further consideration.
Reduction
Reduction is used primarily for the treatment of heavy metals, such as mercury. Chemical
reduction is therefore considered for remediation of Site surface soils. Full-scale application
of this process to contaminated soils has been limited and pilot-scale data would be
required to design a system to treat wastes such as those present at the Site. An excess
of reducing solution would be required because of competing reactions with non-targeted
compounds. Ensuring adequate contact of solutions with c:ontaminants imbedded in clay
and silt materials would be difficult.
Because of the limited number of site contaminants addressed by the process and the lack
of full-scale application, this process is not considered feasible for application at the Site.
Chemical reduction is not retained for further investigation.
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4) Supercritical Water Oxidation
Supercritical water oxidation processes operate above the supercritical temperature of water
(374"C, 220 atm) to achieve high destruction efficienciei; for organic compounds. The
process is being developed by MODAR, Irie. of Natick, Massachusetts. Application of the
MODAR process has been limited to pilot level testing (500 gpd) on aqueous wastes and
sludges. A full-scale MODAR system has not yet been built and the current design is being
revised. The effectiveness of supercritical oxidation processes toward soils is not sufficiently
demonstrated for application at the Site. This technology is rejected from further
consideration.
5) Soil Washing
Soil washing is a method of extracting contaminants from excavated sludge or soil using
a liquid such as water as the washing solution. Soil washing is similar to the in-situ process
of soil flushing, which is essentially the same process except soil washing is performed on
excavated soils which are fed into a processing unit.
Washing liquids can be water, organic solvents, water/heating agents, water/surfactants,
acids, or bases. The washing solution is then treated to remove contaminants via a
subsequent wastewater treatment system, although the presence of the extraction solution
may complicate treatment of the contaminants. Some soils may require multiple washing
cycles for effective contaminant removal.
Selection of the washing solution is based on characteristics of the contaminants and of the
soil. The limited solubility of most semivolatile organic contaminants indicates that
surfactants would have to be added to enhance contaminant desorption. The chemical
disparity of compounds within site soils suggests that th1~re may not be one extraction
solution that is effective for all contaminants. Bench-scale testing would be necessary to
select the appropriate surfactants and dosages for specific: applications.
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Review of the literature indicates that the majority of full-scale research on soil washing is
being performed in Europe (The Hazardous Waste Consultant, May/June 1989) and the
availability of U.S. vendors is severely limited. To date, research on soil washing has been
conducted on soils that could be screened to discrete particle distributions. Soils treated
in the European studies have been used in asphalt mi:<tures or sent to landfills. Fine
grained sediments smaller than 63 microns are difficult to treat because of strong
contaminant adsorption. Consequently, this fraction is screened for separate treatment.
Waste materials containing over 20 percent fines are considered economically unsuitable
for soil washing. From Appendix D of the RI, the fraction of site soils smaller than 63
microns is approximately 50 percent. The percentage of fines (silts and clays) is greater
than 50 percent.
Soil washing was determined to be ineffective at a Superfund site in Michigan for
compounds with similar or greater solubilities than at the Macon-Dockery site (EPA, 1990).
Site soils have an appreciable silt and clay content (approximately 50 percent), which would
greatly hinder the contaminant contact and mass transfer properties of surfactant solutions.
The limited amount of full-scale applications for this technology and uncertain treatment
effectiveness indicate that soil washing is not feasible for the site at this time. Soil washing
is not considered further.
6) Stabilization/Solidification
Stabilization and solidification are treatment processes that are designed to improve the
handling and physical characteristics of the waste, decrease the surface area of the waste
material across which transfer or loss of contaminants can occur, and/or limit the solubility
of any hazardous constituents of the waste. Stabilization deals with the addition of materials
which limit the solubility or mobility of waste constituents with or without change or
improvement in the physical characteristics of the waste.
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Solidification deals with processes where a solid block of waste material with high structural
integrity mechanically locks contaminants within the solidified matrix. Since soil is a solid
residual, the remainder of this discussion will be concerned solely with stabilization.
Stabilization is applicable for solid, liquid, and sludge wastes. These processes can be
performed in-situ or on excavated materials depending on Site conditions. There are
various types of stabilization agents which can be used based on the contaminants of
concern. Stabilization technologies have been most effective when treating inorganic
wastes.
It is unlikely that stabilization could achieve a concentration-based treatment standard.
However, stabilization may be able to achieve a leachate-based performance standard, such
as the Toxicity Characteristic Leachate Procedure (TCLP).
Cement-Based Stabilization
This method involves mixing the wastes directly with Portland cement, typically Type I. The
end product may be a monolithic solid or it may have a soil-like consistency, depending on
the amount of cement added. Portland cement alone is not effective in immobilizing
organics and the end product will not be acceptable for disposal without secondary
containment. The end product typically increases the weight and volume of the original
material, increasing space requirements for waste disposal. Consequently, this technology
is best suited for applications where waste concentrations are high and waste volumes are
low. For these reasons, cement-based stabilization is rejected from further consideration
as a treatment technology.
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Silicate-Based Stabilization
Silicate-based stabilization processes use a siliceous material such as fly-ash, blast furnace
slag, or other pozzolanic materials together with lime, cement, gypsum, or other setting
agents. The basic reaction Is between the silicate material and polyvalent metal ions. The
polyvalent metal ions act as initiators of silicate precipitation and/or gelation and come from
the waste solution, an added setting agent, or both. The solid formed varies from a moist,
clay-like material to a hard, dry solid similar in appearance to concrete. As with cement-
based stabilization, an increase in the bulk and mass of tile treated waste can be expected
with silicate-based treatments. There is considerable research data to suggest that silicates
used with setting agents can also stabilize a wide range of materials including waste oil,
solvents, and other organics. Silicate-based stabilization may therefore be a suitable
remedial technology at locations where contaminant concentrations are known to be high.
These compounds can, however, physically interfere with bonding by coating waste
particles. Also, if strongly alkaline, the cementing system can react with certain waste to
release undesired materials such as gas or leachate (EPA, June 1986). For these reasons,
silicate-based stabilization will not be retained for further Gonsideration.
Modified Clay -Based Stabilization
Stabilization of organic wastes using conventional stabilization materials (cement or
pozzolans) is difficult to achieve because the organic constituents tend to retard the settling
of the binding agents and are often relatively easy to leach from the resulting mass.
However, modified clays may be mixed with the conventional stabilization materials to
adsorb the organic materials, thereby preventing them from interfering with the curing
process while making it more difficult to leach from the solidified mass.
Montmorillonite and attapulgite clays are modified by a process called pillaring. The
surfaces of both clays are predominantly negatively charged. This negative charge is
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partially balanced by inorganic cations such as sodium, calcium, and magnesium. Modified
clays are produced when these inorganic cations are replaced with organic cationic
surfactants having an affinity for other organic molecules. The surfactant molecules are
larger than the inorganic cations and force the clay matrix apart (pillaring) creating additional
porosity within the clay structure. This pillaring effect increases the capacity of the clay to
adsorb organics. Organically modified clays can be engineered to provide optimum
adsorption characteristics for specific types of organic contaminants (G.R. Alther, et al.,
1988).
Although organically modified clays have been successfully used to adsorb organic
compounds in the laboratory, this method of waste stabilization is not a proven or
demonstrated technology for full scale application. Soil stabilization using modified clay is
not considered for application at this site.
Thermoplastic Microencapsulation
This technology involves drying and then dispersing homogeneous solid wastes through
a heated, plastic matrix. After cooling, the mixture forms a rigid but deformable solid.
Encapsulating materials include asphalt (most common). polybutadiene, and polyethylene.
Specialized equipment is required to insure proper mixing of the materials. Screw extruders
similar to those used in the plastics industry are usod to mix the waste and the
encapsulating material at temperatures of 130" to 230"C. This temperature can cause
volatilization of contaminants, so worker protection and off-gas control must be addressed.
High equipment and energy costs are the main disadvantages of this technology. Another
problem is that the plastics formed are not rigid. Containers are generally required for
transportation and disposal, if required, which greatly increases the cost associated with this
treatment.
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Microencapsulation was developed for and has been widely used in the disposal of nuclear
waste, although it has also been used for wastes consisting of concentrated heavy metal
sludges. The plastics act as neutron absorbers for radioactive waste, and metals can be
stabilized by preconditioning with lime or by the addition .of fixing agents. Organics,
however, are merely encapsulated and not immobilized. Volatile organics can diffuse
through asphalt, making its use impractical at this Site if tile volatiles are not stripped during
encapsulation. Research on encapsulation of organics ~1as been limited and there appear
to have been no field applications with contaminated soils.
microencapsulation is not considered further.
7) Transportable Incineration
Thermoplastic
Incineration is a demonstrated treatment technology for the removal of organic compounds
from soils. Quantitative reduction of organic chemicals in soils has been consistently
achieved by incineration. Heavy metals are not destroyed during incineration and are
portioned either to the ash or to the stack. The assessment of appropriate and available
technologies among the many kinds of incinerators must be made. Transportable
incineration technologies used for remedial application include rotary kiln incineration,
infrared thermal treatment, pyrolitic incineration, fluidized bed incineration, multiple hearth
incineration, high temperature wall incineration and plasma arc incineration. The
assessment of each technology must be based upon individual considerations as they
pertain to specific applications.
A primary consideration common to all transportable technologies is the trial burn
demonstration requirements. Elements of the trial burn process include (EPA, 1987):
• Prepare trial burn plan and submit to Federal and State agencies (required 6
months after notification).
• Prepare responses to any questions or deficiencies in the trial burn plan (1
month).
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• Make any additions or modifications to the incinerator that may be necessary
(1 to 3 months).
• Prepare for trial burn.
Prepare for all sampling and analysis (S&A) (2 to 3 months).
Select date for trial burn, in concert with S&A staff or contractor
(completed 1 month prior to test).
Notify all appropriate regulatory agencies (1 month).
Obtain required quantities of waste having specified characteristics (est.
2 months).
Calibrate all critical incinerator instrumentation (2 weeks).
• Conduct trial burn sampling (1 week).
• Conduct sample analysis (1 to 1-1/2 months).
• Calculate trial burn results (1/2 month).
• Prepare results for submittal to EPA (1/2 to 1 month). Include requested permit
operating conditions.
• Obtain permit to accept candidate waste (3 months).
The total process requires approximately 20-24 months.
Transportable incinerators are currently in use and planned for use at a number of CERCLA
sites. The mobilization, trial burn and demobilization requirements are such that a significant
portion of the time and costs associated with on-site incineration are outside of actual
treatment. The demand for incineration and logistics regarding on-site applications have
combined to create a severe shortage of incineration capacity. The demand is further
exacerbated because there are but a handful of firms with incineration experience at
CERCLA sites. Land disposal restrictions based on incineration have been given a two year
extension because of this capacity shortage.
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Lagoon 10 materials comprise only approximately 1,000 cubic yards (or 1300 tons), while
Lagoon 7 materials are on the order of 1300 cubic yards (1700 tons). Thus, total treatment
volumes of Lagoon 7 and Lagoon 1 0 would be approximately 2300 cubic yards (3000 tons).
Transportable incinerators typically have a nominal throughput of 5-1 O tons/hour. The 3000 I tons of soils at the site would therefore be processed in only two to four weeks. This short
period is out of proportion to the time required for a trial burn and represents a utilization I rate of only four percent. Major incineration vendors will not obligate their equipment for
such a short period of actual remediation. The economics are also unfavorable, since the
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mobilization, start up and trial burn costs must be spread over such a limited volume of
materials. The next result is that it is not technically or economically feasible to mobilize an
on-site incinerator to a site unless there are at least ·10,000 cubic yards of material
(Chemical Waste Management; July, 1991). This technology is therefore rejected from
further consideration on the basis of implementation.
8) Low Temperature Thermal Separation
Low Temperature Thermal Separation (L TTS) removes organic compounds from soils by
mixing the soils in the presence of a stream of heated air or indirectly contacted with a
heated air or indirectly contacted with a heated fluid to volatize and remove organic
contaminants from the soils. Three proprietary thermal technologies include Low
Temperature Thermal Aeration (LTTA) by Canonie Environmental, the x*TRAX system by
Chemical Waste Management, Incorporated and Low Temperature Thermal Treatment (LT3)
by Weston Services, Incorporated.
Soils suitable for L TTS must be appropriately sized and preferably of low moisture content.
Soil sizing requirements range from 1-inch to 3-inches in diameter for the x*TRAX and LTTA
* technologies, respectively. X TRAX uses grinders to reduce the size of soil particles to
meet sizing requirements. Soils with relatively high moisture content require longer
residence times to drive off water that inhibits the desorption and volatization of organic
compounds from soils.
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Lagoon 7 soils are expected to meet sizing requirements while Lagoon 1 O soils are
expected to meet sizing requirements after the removal of large debris. Soil moisture
content, however, may dictate longer residence times for Lagoon 10 soils.
Mobilization, demobilization and permitting requirements for L TIS technologies must be
considered when evaluating this technology as they are extensive, requiring a significant
portion of time outside of actual treatment time. The estimated time for permitting (or permit
equivalency), mobilization, soil treatment (based on a nominal throughput of 5 tons/hours)
and demobilization are presented below:
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Permitting
Mobilization and setup
Soil processing
Demobilization
5 to 8 months
2 to 7 weeks
2 to 3 weeks
3 to 7 weeks .
L TIS technologies, like transportable incinerators, are currently in use and planned for use
at a number of CERCLA sites. The demand for L TIS technologies and logistics regarding
on-site applications have combined to create a severe shortage of L TIS capacity. It is
therefore not technically or economically feasible to mobilize an L TIS unit to a site unless
there is at least 10,000 cubic yards of material (Chemical Waste Management, June 1991).
Lagoon 7 and Lagoon 10 materials comprise only approximately 2300 cubic yards and
implementation of L TIS technology at the Site is impractical.
L TIS technology are only effective for the removal of organic compounds with boiling points
less than treatment operating temperatures. Operating temperatures of the L TIS
technologies vary, but range from 350°F (177°C) for LTrA, 450°F to 750°F (232°C to
399°C) for x*Trax and 650"F (343°C) for the LT3 technologies. Tetrachloroethene, the
primary contaminant of concern in Lagoon 7, has a boiling point of 121 • C. Consequently,
LTIS may be effective on Lagoon 7 material. However, Lagoon 10 contains polyaromatic
hydrocarbons (e.g. creosote wastes) that have higher boiling points. Some of the organic
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compounds detected in Lagoon 10 soils are listed below along with their respective
concentrations and boiling points.
• Anthracene 160,000 µg/kg 34o•c
• Benzo {a) anthracene 150,000 µg/kg 437°C
• Benzo (a) pyrene 140,000 µg/kg 49s•c
• Benzo {g,h,i) perylene 60,000 µg/kg ·>500°C
• Benzo (k) fluoranthene 120,000 µg/kg 480°C
• Chrysene 140,000 µg/kg 44s•c
• Fluoranthene 200,000 µg/kg 384°C
• Phenanthrene 1,300,000 µg/kg 34o•c
• Pyrene 410,000 µg/kg 404°C
Based on system operating temperatures and the boiling points of the residuals in Lagoon
10 soils, LTTS technologies would not be an effective alternative for the removal of a
number of the chemical residuals from Lagoon 1 0 soils. L TTS technologies are therefore
rejected from further consideration on the basis of implementation (Lagoon 7) and
implementation and effectiveness (Lagoon 10).
4.4.2 In Situ Treatment
In situ treatment for soil remediation is performed without excavation, using the soil matrix
as the treatment zone. The absence of excavation requirements for in situ treatment is an
important consideration for sites, such as former Lagoon 7, where the costs of remedial
alternatives requiring excavation are prohibitive. In-situ options will still be evaluated for
potential application at former Lagoon 7 and Lagoon 10. Potential options include soil
vapor extraction, air sparging, soil venting, enhanced biodegradation, soil flushing, and
vitrification .
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(1) Soil Vapor Extraction
Soil vapor extraction (SVE) involves the removal of volatile organics from the soil matrix by
mechanically drawing or venting air through the unsaturated soil layer. As air is pulled
through the soil, the equilibrium that exists between the organic compounds distributed on
soil particles, in soil moisture, and in soil gas is disturbed. Soil gas laden with volatized
organic compounds is replaced by fresh air, causing a redistribution of volatile organics
from soil particles and soil moisture into the soil gas. Air emissions may require further
treatment before they are vented to the atmosphere. Soil moisture will be entrained in the
extracted soil gas, initially in high volumes, until content in the affected soils is reduced by
the SVE process. The moisture would need to be collected for further treatment.
The process typically includes a series of slotted vertical extraction vents connected by a
common manifold to an extraction pump or blower. Simple SVE systems consist of
extraction wells and supporting equipment. In these systems, air is pulled from the ground
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surface, through the soil and into the vent. The radius of influence depends upon soil
density and soil porosity, but varies usually between 15 to 100 feet. Short circuiting occurs
when air is drawn along side the extraction well, thereby limiting the effective radius of
influence. Short circuiting usually occurs in soils that are very permeable or when the soil
vapor extraction wells are placed too shallow. An impermeable cap may be placed over
the area of impacted soils to limit the amount of air that is drawn through the soil from the
ground surface near the well, thereby inducing a more radial air flow pattern. For soils
requiring treatment to depths of 15 feet or less, it is often more practical to dig trenches
and install perforated pipes horizontally. A supplement to the simple SVE system is the
installation of passive air inlet wells. The passive air inlet wells are sited to enhance and
direct the air flow into and through the contaminated soil.
Soil parameters of interest include the permeability, porosity, moisture, and soil "horizons".
The presence of soil horizons can lead to short circuiting and isolation of areas of
contamination from stripping. Chemical parameters of interest include vapor pressure,
octanol-water partitioning coefficient, and solubility .
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Site conditions are appropriate for the application of SVE. Soil permeability is approximately
2.5 x 10.s cm/s based on hydraulic conductivity testing in saprolite wells. A SITE
demonstration showed that SVE systems are effective in soils with permeabilities of 1 o.a
cm/s when the porosity has been sufficient (Stinson, 1989). Calculated actual and effective
porosities at the Site are approximately 40 and 20 percent (conservative), respectively,
which would be sufficient for application of SVE. A permeability barrier would exist,
however, in the zone of perched water beneath the Upper Macon, Lower Macon and Upper
Dockery areas. The perched aquifer is 14 to 20 feet below ground surface and is estimated
to be 1 to 2 feet thick. A simple, or horizontal SVE design could be implemented for soils
lying above the perched water and SVE used in conjunction with passive air Inlet wells
could be used for soils below the perched aquifer.
SVE is effective for compounds with a Henry's Law constant, He (dimensionless), of at least
0.001. The Site compounds listed below have He values above this and can be effectively
removed through SVE. From Section 3.2.3.3, the only compound in subsurface soils
potentially requiring remediation is tetrachloroethene in Lagoon 7.
Semivolatiles
Acenaphthene
Acenaphthylene
Anthracene
Benzo (k) fluoranthene
Di-n-butyl phthalate
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Volatiles
Acetone
Benzene
2-Butanone
Chloroform
1, 1-Dichloroethane
1,2-Dichloroethene
Ethylbenzene
2-Hexanone
Methylene Chloride
Tetrachloroethene
Toluene
Trichloroethane
Xylenes
A secondary effect of SVE is to stimulate biodegradation through the passage of air and
concomitant increase in oxygen levels.
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North Carolina regulations for the exemption of air emission from an SVE system are the
same as for an air stripper (Section 4.3.2). The actual need for off-gas control would be
dependent on achieving ambient air standards at property boundaries. Emissions
concentrations are a function of the soil chemical concentrations, the SVE air flow rate, and
the soil desorption kinetics, which are difficult to estimate. Empirical relationships developed
by vendors from field experience are generally the best predictors of volatile organic
emissions. The need for off-gas control would be determined during Remedial Design,
should this technology be selected for implementation. Control of voe emissions can be
achieved using an activated carbon or catalytic oxidation unit.
An SVE system can also be used for localized ground water recovery through the use of
dual vapor/water extraction wells. The applied vacuum enhances ground water recovery
In soils with limited production. After reaching equilibrium, the dual extraction system can
lower the effective water table through continuous extraction of vapor and ground water.
This increases the effectiveness of VOC removal by increasing the volume of unsaturated
soils available for vapor extraction. voes in unsaturated soils are more quickly removed
through SVE than they are in the saturated zone through long-term ground water pumping.
If saturated soils can be adequately dewatered, treatment by SVE can significantly shorten
the time required for remediation.
SVE has been successfully used for the removal of volatile and semi-volatile organics. The
process has also been used successfully for full-scale remediation projects in the Piedmont
region (Vicellon facility, Fountain Inn, SC). Because of the review of case studies at sites
with similar geology and compounds, SVE appears feasible for application at the Site and
is retained for further evaluation.
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2) Enhanced Biodegradation
In-situ biodegradation involves enhancing the naturally occurring microbial activities found
in subsurface soils. Breakdown and removal of contaminants can be accelerated by the
addition of oxygen, inorganic nutrients, and prepared microbial populations. This
technology has been developing rapidly and is one of the most promising in-situ treatment
techniques. General limitations of in-situ biodegradation include transport of nutrients to the
distant points of contamination, the sorption and solubility of the contaminants, toxic
inhibition, and extended treatment times. In order to be effective, the proper mixture of
nutrients and chemical reactants must be distributed over the entire area to be
bioreclamated. Nutrient addition can increase the mobility of contaminants. Ground water
conditions could deteriorate if remedial measures do not completely recover these
contaminants. Compounds with high octanol-water partitioning coefficients are typically non-
polar and have low aqueous solubilities. Such properties make these compounds tend to
sorb onto the soils and remain unavailable for biodegradation. Highly chlorinated
compounds are generally resistant to biodegradation. Some chlorinated compounds that
are susceptible biodegradation are degraded to intermediate compounds that are more toxic
than the parent compound. For example, biodegradation intermediates of PCE, 1, 1-
dichloroethane, 1,2-dichloroethene, and trichloroethane includes vinyl chloride, which is
more mobile and more toxic than its parent compounds. Consequently, the potential of
producing vinyl chloride from PCE precludes the use of enhanced biodegradation at former
Lagoon 7. Similarly, land treatment, discussed in Section 4.4.1, can effectively treat Lagoon
10 wastes and maintain positive containment of relatively mobile intermediates. Enhanced
bioremediation is therefore removed from further consideration.
3) Soil Flushing
Soil flushing is a method of extracting contaminants from unexcavated soils using an
injection/recirculation system. Potential washing fluids include water, acids, bases,
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water/chelating agents, water/surfactants, and organic solvents. Selection of the optimal
washing fluid is based on characteristics of the contaminants and of the soil. If surfactants
or chelating agents that pose environmental risks are added, they also must be removed
for complete remediation.
General difficulties facing effective implementation of surfactant-assisted soil flushing include
the need for intensive soil contact followed by thorough collection of leachate. For effective
soil flushing, soils should be consistent, permeable, and contain only a few specific
contaminants. Site soil permeabilities are generally low and somewhat variable making
removal of contaminants to an acceptable level difficult. The greatest concern regarding
soil flushing is that mobilized contaminants would not be completely recovered by the
extraction system and therefore degrade ground water conditions. Furthermore, many of
the compounds present at the Site have high octanol-water coefficients, making them
difficult to remove from soils. For these reasons, soil flushing is removed from further
consideration .
4) Vitrification
In-situ vitrification is a process of melting wastes and soils or sludges in place to bind the
waste in a glassy, solid matrix resistent to leaching and more durable than graphite or
marble. It was originally developed for treatment of radioactive wastes, although it has
potential for use with soils contaminated with heavy metals, inorganics, and organic wastes.
The process consists of placing electrodes in the soil and constructing trenches filled with
a flaked graphite and glass fruit mixture to connect the electrodes in an "X" pattern. Voltage
is then applied to the electrodes and the graphite/glass fruit mixture is quickly heated to
3600°F, which is well above the melting point of soil (2000 to 2500°F). A molten zone
expands horizontally and vertically to encompass the volume between the electrodes. As
the soil melts, organic wastes are pyrolized and combust when they come in contact with
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air. The high temperatures at the surface cause virtually complete combustion of the
organics in the gases. Hazardous compounds that do not volatilize remain in the molten
soil and become part of the glass and crystalline product after cooling. Non-combusted
volatiles are collected in an off-gas hood for treatment. When the desired vitrification depth
Is reached, the electrodes are turned off and the soils are allowed to cool.
In-situ vitrification tests have been completed on an engineering scale (0.05 -1.0 tons of
soil), a pilot-scale (1 o tons of soil) and a large-scale (400 to BOO tons of soil). Test results
have shown that 99.99% of volatile heavy metals are trapped In the vitrified mass or
removed by the off-gas system. Bench-scale results for PCB-contaminated soils showed
overall destruction and removal efficiencies (DRE's) of >99.99% and tests on soils
contaminated with 2, 3, 7, 8 -TCDD give similar results.
Vitrification is most suitable for use with dry soils, or soils with hydraulic conductivities of
less than 1 x 1 o-5 cm/sec. The presence of water in the soil increases the cost of
operation, as the water must be evaporated before the soil will begin to melt. Site soils are
generally composed of a clay-silt-sand mixture. Since clays are very porous and
aggressively retain water, soil moisture conditions at the Site are a concern. Soil moisture
content is also a concern in soils overlying the shallow perched water table at the Upper
Dockery, Upper Macon and Lower Macon sites. The moisture contained in the perched
water table would inhibit soil vitrification at lower depths. Because soil moisture content
would limit the effectiveness of soil vitrification, in-situ soil vitrification is removed from further
consideration.
4.4.3 Off-Site Treatment or Disposal
Remediation of contaminated soils and residual materials can potentially be handled off-
site. In accordance with Section 300.70(c) of the National Contingency Plan (NCP), source
control alternatives involving off-site treatment, destruction, or disposal must satisfy the
following criteria:
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1. be more cost effective than other remedial actions,
2. create new waste management capacity, or be necessary to protect public health and
welfare or the environment; and
3. satisfy best demonstrated available technologies (BDA T) requirements.
Additionally, the current NCP requires that off-site treatment and disposal methods be
considered as potential remedial alternatives.
The removal and transportation of contaminated materials involves the potential of increased
risk to workers and the surrounding population as compared to equally effective on-site
remediation efforts. Consequently, transportation of waste materials off-site requires
precautionary measures to protect public health and the environment.
There are various commercial treatment and disposal facilities available, but capacity and
acceptance of Site residuals are potential limitations associated with off-site options. On-
site pretreatment options, such as phase separation, segregation for chemical
incompatibility, neutralization, solidification, and bulking, may still be required prior to off-
site transportation. Off-site disposal may require additional efforts to comply with RCRA
regulations.
Another consideration for selection of off-site treatment or disposal alternatives is the
accessibility of the Site. The capacity and long-term condition of the roadways providing
access to the Site must be considered in light of the extensive traffic required for potential
removals.
1) Commercial Landfilling
Increasing regulatory control of landfilling of hazardous substances makes this alternative
steadily more expensive and difficult to implement. Landfilling waste does not reduce the
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volume or toxicity of the wastes, but merely relocates the problem, thereby deferring the
Impact of these wastes on the environment. Sending hazardous residuals off-site can be
limited by available capacity or RCRA compliance requirements for existing facilities. Waste
materials cannot be accepted for disposal at AGRA-permitted landfills without prior treatment
(40 CFR 268.31) unless the waste or treatment residual can pass the TCLP. Commercial
landfilling is retained for further consideration.
2) Commercial Incineration
Commercial off-site incinerators capable of accepting soils are generally of the rotary kiln
type. The rotary kiln is a cylindrical refractory-lined shell that is mounted on a slight incline.
Rotation promotes movement of waste through the kiln as well as enhancement of waste
mixing. Rotary kilns can incinerate solids, semi-solids, and liquids independently or in
combination. Pretreatment requirements are generally less than those for other types of
hazardous waste incinerators. Incineration efficiencies are very high when the kilns are
coupled with a secondary combustion chamber, with combustion temperatures ranging from
1500 to 3000°F and residence times from a few minutes to hours. For these reasons,
rotary kilns are the preferred method for treating mixed hazardous solid residues.
Off-site incineration is cost-effective when applied to high concentration materials in relatively
low volumes. Site soils most suited for off-site incineration are those at the Lower Macon
Site at lagoon 10 since they contain the highest concentration of chemicals at the Site. The
estimated volume of waste at Lagoon 10 is 1,000 cubic yards. Soils from Lagoon 7 at the
Upper Macon Site contain low concentrations of volatile organic compounds, primarily PCE.
Estimated volume of Lagoon 7 soil is 1300 cubic yards.
Current constraints regarding the application of off-site rotary kilns include available capacity
and the type of wastes that are acceptable. Soils are generally disfavored because of their
high ash content and low BTU value. Off-site commercial incineration of soils will be
retained for further consideration.
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4.4.4 Containment
Containment alternatives minimize leaching of chemicals from the soil by providing low
permeability barriers to infiltration, thereby preventing chemical transport to the ground
water. Containment can be used to isolate and reduce mobility of large waste disposal
areas where other technologies would be technically or economically infeasible.
Containment strategies have been applied successfully at numerous.hazardous waste sites.
1) Capping
Capping is a process used to cover buried waste materials to prevent their contact with the
land surface and ground water. A cover is often employed as a remedial measure at a site
in conjunction with other remedial technologies such as drainage and revegetation. Should
a standard RCRA cap or an alternative cap meeting the intent of the RCRA regulations be
required, this would be achievable at the Site .
Capping offers proven protection against vertical leaching of chemicals by precipitation to
the ground water. Operational considerations include the need for long-term maintenance
and uncertain design life. Present worth maintenance costs are typically less than
excavation and treatment, however, and experience over the last few years at hazardous
waste sites has allowed better estimation of cover longevity. Synthetic liners supported by
a low permeability base may last over 100 years.
Capping is most effective when the chemicals present are not highly mobile. The octanol-
water coefficient for most of the compounds present are high, thereby limiting the mobility
of these compounds and making the Site potentially appropriate for capping. Further
leachability of these compounds is expected to be minor and can be further reduced by
placement of the cap and additional surface controls. Capping will also reduce any
potential for uncontrolled exposure to the waste material remaining at the Site. Capping
is therefore retained for further evaluation.
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2) Subsurface Barriers
Subsurface barriers are used to minimize leaching of contaminants from the soil by installing
low-permeability cut-off walls or diversions below ground to contain, capture, or redirect
ground water flow in the vicinity of the Site. These methods can be used to Isolate areas
of waste disposal and greatly restrict the mobility of contaminants.
Slurry Walls
Slurry walls are the most common subsurface barriers at hazardous waste sites because
they can vastly reduce ground water flow in unconsolidated earth and are readily
constructed. In addition, they provide a means of establishing an inward hydraulic gradient
when combined with ground water extraction systems, further reducing contaminant mobility.
Slurry walls are almost always used in conjunction with other means of containment or
treatment. Generally, they are constructed in vertical trenches that are excavated under a
slurry. For a typical soil-bentonite installation, the slurry hydraulically shores the trench walls
to prevent collapse while forming a filter cake on the trench walls to minimize fluid losses
into the surrounding soils. An appropriate backfill is added to complete the installation.
Alternate installation methods are also available that will be considered with this technology.
Design parameters for slurry walls include vertical depth and horizontal placement. Walls
that extend into a low permeability zone are called keyed and those that extend partially into
the water table are called hanging. Hanging walls are used to control contaminants which
float on top of the ground water. Since the contaminants at this Site are dispersed
throughout the water table, keyed slurry walls are the only type requiring further
consideration.
Slurry walls can be isolated upgradient or downgradient of the waste area or can
completely surround the waste area. Upgradient walls are used with drains to divert
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uncontaminated ground water away from the waste area and down to a receiving body.
Ground water gradients must be properly managed to prevent ground water. from flowing
over or behind the wall. Downgradient walls are used as a barrier of flow of contaminated
ground water, allowing recovery or treatment via extraction wells. Circumferential walls are
used to Isolate an area of contamination, usually with an impermeable surface barrier. A
leachate collection system can be used to selectively direct ground water flow. This
extraction of ground water may create differential hydraulic pressure across the wall, which
must be allowed for in design.
Considerations for the various slurry wall configurations are generally site specific.
Downgradient walls would not be effective without dewatering. Upgradient walls require
suitable site topography. Circumferential walls are the most expensive but offer the most
extensive control of contaminant migration and would probably be the preferred type for
effective control at this Site; however, Site-specific limitations of using circumferential wails
are discussed below.
Slurry walls can be constructed of soil-bentonite (SB), cement bentonite (CB), or reinforced
concrete sections (diaphragms). In general, SB walls have the lowest permeability and the
widest range of waste compatibilities. SB admixtures may include proprietary formulations
to enhance chemical compatibility. Preliminary testing of the backfill material with actual Site
ground water should be performed to determine suitability for use. CB walls can be built
on more severe terrain but are more permeable and more costly. CB walls are not
applicable for the specific wastes identified at this Site and therefore would not be suitable
for use at this Site. Diaphragm walls are also more permeable than SB walls and
significantly more expensive and are therefore also rejected from consideration. SB walls
are the only type which will be considered further.
Depth to a bedrock across the Site is approximately 60 to 80 feet. Excavation to these
depths is not practical with standard excavation equipment. Although the use of slurry walls
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is a conventional, well-demonstrated technology which has been applied successfully at
other hazardous waste sites they would be very difficult to implement at this site. Therefore,
soil-bentonite slurry walls are not retained for further consideration.
Grouting
Grouting Involves the injection of fluids into rock or a soil mass. The fluid sets and forms
a barrier to reduce water flow. Grouted barriers are more costly and have higher
permeabilities than slurry walls. As discussed in the slurry walls section above, the depth
to bedrock at this Site is approximately 60 to 80 feet, making this technology very difficult
to implement. Grouting, therefore, is not retained for further consideration.
Sheet Piling
Sheet pilings are preformed steel barriers that are driven into the ground and connected
by interlocking joints. The joints are initially quite permeable until fine soil particles fill the
void and form a seal. Grouting can be used to seal the joint but the procedure· is of
questionable effectiveness. In order to be effective, the sheet piles should extend into
impermeable material at the Site. However, fifteen feet is the maximum depth to which
sheet piles can be driven without damaging the piles. Since the depth to bedrock at the
site is approximately 60 to 80 feet, it would be impossible to properly implement this
technology at the site. Consequently, sheet piling is not considered further for application
at this Site.
3) Container Piles
Container piles are long hollow steel tubes which are driven into contaminated soils, thereby
filling the container piles with contaminated soil at the in-situ soil density. This method
prevents the usual 1.2 to 1.4 times expansion of volume associated with other excavation
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techniques. Once the container pile is driven into the ground, the bottom is sealed using
mechanical means and/or injection grouting and a cover is welded on top. Container piles
can then be removed, cleaned, handled, transported, and stored until final treatment of the
waste. Container piles can be used to excavate the entire site or just isolated "hot spots".
Use of container piles is only an intermediate storage step, as subsequent treatment is still
required.
As an excavation technique, container piles would be considerably less efficient and more
costly than standard excavation techniques. The open excavations would still be sources
of fugitive emissions. The use of container piles to excavate contaminated soils is an
innovative technology based on state-of-the-art civil engineering and off-shore technology.
This extreme measure is only warranted when there exists an immediate danger to human
health and the environment, which is not true of current Site conditions. Container piles
have not been used on a full-scale level and their effectiveness is questionable. Since this
is an untested technology not warranted by Site conditions, the use of container piles is not
considered further .
4) On-Site Landfill
Remediation alternatives that involve off-site processing must satisfy certain criteria under
the NCP, as outlined in Section 4.4.3. Equivalent on-site alternatives should be evaluated
when off-site alternatives are considered. An on-site landfill is considered here as the
counterpart of commercial landfilling.
Creation of an on-site landfill would involve the excavation of a landfill cell and the
installation of an appropriate liner system. The excavation and staging of contaminated
soils would be required if the landfill cell is sited at a location where soils are presently
impacted. Contaminated soils would then be placed into the lined excavation and covered
with an impermeable liner. Construction would most likely occur as a single landfill cell.
To construct a landfill in strict accordance with RCRA standards requires the following:
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• a double liner system
• two leachate detection systems
• ground water monitoring, and
• any applicable siting criteria.
RCRA requirements are given in 40 CFR 264 Subpart N. These regulations specify that
new landfills should contain "two or more liners and a leachate collection system above and
between the liners.• An alternative design can be implemented if it is demonstrated that the
alternative would be as effective as the RCRA design for the prevention of contaminant
migration. Evaluation of the Site's geological and hydrological conditions Is also critical to
developing a well designed hazardous waste landfill. Factors to be considered include
seismic activity, settlement or subsidence, high ground water table, storm water run-on, and
flood plains.
On-site landfilling would, however, yield no net reduction of residual chemicals on-site and
would result in increased monitoring requirements. On-site landfilling would offer
comparable effectiveness to capping with respect to denial of infiltration and potential
human exposure but at a significantly higher cost. On-site landfilling of Lagoon 10 wastes
will not be retained for further evaluation.
4.4.5 No Action
The National Oil and Hazardous Substances Contingency Plan (NCP) directs that the no
action alternative be retained during the Feasibility Study. The no action alternative
references the Site risk assessments and presents a baseline of performance with which
to evaluate other alternatives. Site soils would be left in place under this alternative. While
this alternative involves no active remediation, limited site control may be exercised to deter
unauthorized access. Typical options include maintenance of the perimeter security fence
and regular surveillance.
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4.5 TECHNOLOGY SCREENING SUMMARY
Potential technologies were screened according to the technical criteria in Section 4.1.
Summaries of the evaluations for migration and source control are presented below.
4.5.1 Ground Water Control
The screening of ground water control technologies is presented separately below for
ground water recovery, treatment and discharge. A summary of the technical evaluations
is presented in Table 4.3.
4.5.1.1 Ground-water Recovery
Two technologies and a control strategy were evaluated for the extraction of Site ground
water. Extraction wells were retained because of their proven effectiveness while an
interception trench was rejected because of implementation difficulties and limited
effectiveness. The no action alternative was retained as required by the NCP.
4.5.1.2 Ground-water Treatment
The compounds in ground water exceeding ARARs are VOCs and metals, and the
evaluation of potential treatment technologies was limited accordingly. A total of ten
technologies were evaluated and five were retained. Air stripping, carbon adsorption, and
a UV-catalyzed ozonation were retained because of their demonstrated effectiveness
towards VOCs. Filtration and coagulation were retained for their effectiveness in removing
particulate metals.
Biological treatment and land treatment were rejected because chlorinated VOCs are
resistant to biodegradation. Sorptive resins was rejected because of the uncertainties
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regarding its effectiveness and reliability. Precipitation was rejected because of limited
effectiveness toward removal of particulate metals. Reverse osmosis was rejected because
of its susceptibility to chemical fouling and plugging.
4.5.1.3 Ground-water Discharge
Four options were evaluated for the discharge of treated ground water. Discharge to a
surface water (Solomons Creek) was retained as being technically effective and allowed
under State law. Horizontal infiltration galleries were provisionally retained pending
determination of allowable application rates. The injection well option was rejected because
under State law it is not permittable (GS 143-214.2(b)). Discharge to the POTW was rejected
because it will not be able to accommodate any increase in hydraulic loading and will not
be cost effective.
4.5.2 Source Control
Fourteen direct treatment technologies were evaluated for possible implementation at the
Site. Land treatment was retained because of its proven effectiveness toward Site
contaminants. Cement-based stabilization and silicate-based stabilization were rejected
based on effectiveness concerns. Supercritical CO2 extraction, supercritical water oxidation,
and stabilization using modified clays, were rejected because they are developing
technologies that are not yet demonstrated for Site conditions. The BEST process was
rejected on the basis of costs. Contaminant reduction (redox) technology and soil washing
technology were rejected because they were technologies with limited development.
Oxidation and thermoplastic microencapsulation of contaminants were rejected because of
their limited application toward soils. Transportable incineration technologies were rejected
from further consideration on the basis of implementation. Low temperature thermal
separation was rejected on the basis of implementation and effectiveness.
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Four in-situ technologies were evaluated. Soil vapor extraction was retained because of its
demonstrated effectiveness towards voes and its applicability to Site conditions. Enhanced
biodegradation was rejected because of the availability of a more effective bioremediation
alternative. Soil flushing was rejected because of poor pilot-testing performance and the
limited permeability of the unsaturated zone. Vitrification is not sufficiently demonstrated for
use at Site depths.
Two off-site treatment technologies, commercial landfilling and commercial incineration were
considered and retained for further consideration.
Capping was the only retained containment technology. Subsurface containment methods,
such as slurry walls, grouting, and sheet piling would be ineffective because the depth to
ground water makes implementation of these technologies very difficult. Container piles
were rejected because of limited full-scale application and on-site landfilling was rejected
on the basis of cost.
The no action alternative was retained as a source control alternative as required by the
NCP.
A summary of the source control technology screening is presented in Table 4.4.
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TABLE 4.1
POTENTIAL GROUND WATER REMEDIATION TECHNOLOGIES
RECOVERY
Extraction Wells
Interception Trenches and Subsurface Drains
No Action
TREATMENT
Volatile Organics
Air Stripping
Granular Activated Carbon
Sorptive Resins
Chemical Oxidation (UV-Ozone)
Biological Treatment
Land Treatment
Metals
Precipitation
Filtration
Reverse Osmosis
Coagulation
DISCHARGE
Surface Water Discharge
Horizontal Infiltration Gallery
Injection Wells
Publicly Owned Treatment Works (POTW)
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TABLE 4.2
POTENTIAL SOIL REMEDIATION TECHNOLOGIES
Direct Treatment
Biological Treatment
Land Treatment
Bioreactor
Chemical Extraction
Supercritical CO2 Extraction
BEST Process
Chemical Oxidation/Reduction
Oxidation
Reduction
Supercritical Water Oxidation
Soil Washing
Stabilization/Solidification
Cement-Based Stabilization
Silicate-Based Stabilization
Modified Clay-Based Stabilization
Thermoplastic Microencapsulation
Transportable Incineration
Low Temperature Thermal Separation
In-Situ Treatment
Soil Vapor Extraction
Enhanced Biodegradation
Soil Flushing
Vitrification
Off-Site Treatment or Disposal
Commercial Landfilling
Commercial Incineration
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TABLE 4.2 (Continued)
POTENTIAL SOIL REMEDIATION TECHNOLOGIES
Containment
Capping
Subsurface Barriers
Slurry Walls
Grouting
Sheet Piling
Container Piles
On-Site Landfill
No Action
Macon/Dockery FS July 5, 1991
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TECHNOLOGY
GROUND WATER RECOVERY
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EXTRACTION WELL
INTERCEPTION TRENCHES AND
SUBSURFACE DRAINS
NO ACTION
GROUND WATER TREATMENT
AIR STRIPPING
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ACTIVATED CARBON ADSORPTION
SORPTIVE RESINS
CHEMICAL OXIDATION (UV-OZONE)
BIOLOGICAL TREATMENT
LAND TREATMENT
PRECIPITATION
FILTRATION
REVERSE OSMOSIS
COAGULATION
GROUND WATER DISCHARGE
SURFACE WATER
HORIZONTAL INFILTRATION GALLERY
INJECTION WELLS
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TABLE 4_3
GROUND WATER CONTROL
TECHNOLOGY SUMMARY
STATUS
RETAINED
REJECTED
RETAINED
RETAINED
RETAINED
REJECTED
RETAINED
REJECTED
REJECTED
REJECTED
RETAINED
REJECTED
RETAINED
REASON
CANNOT BE INSTALLED AT DEPTH IN BEDROCK
EFFECTIVENESS AND RELIABILITY
CHLORINATEDVOCS RESISTANTTO BIODEGRADATION
RESISTANT COMPOUNDS, SEASONAL USE
LIMITED EFFECTIVENESS
SUSCEPTIBLE TO CHEMICAL FOULING AND PLUGGING
PROVISIONALLY DEPENDING ON APPLICATION RATES
NOT PERMITTABLE
PUBLICLY OWNED TREATMENT WORKS (POTW)
RETAINED
RETAINED
REJECTED
REJECTED IMPLEMENTABILITY
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DIRECT TREATMENT
IN-SITU TREATMENT
OFF-SITE TREATMENT
CONTAINMENT
NO-ACTION
Macon/Dockery FS
TABLE 4.4
SOURCE CONTROL TECHNOLOGY SUMMARY
MACON-DOCKERY
TECHNOLOGY STATUS
LAND TREATMENT RETAINED
BIOREACTOR REJECTED
SUPERCRmCAL CO2 EXTRACTION REJECTED
BEST PROCESS REJECTED
OXIDATION REJECTED
REDUCTION REJECTED
SUPERCRmCAL WATER OXIDATION REJECTED
SOIL WASHING REJECTED
CEMENT-BASED STABILIZATION REJECTED
SILICATE-BASED STABILIZATION REJECTED
MODIFIED CLAY-BASED STABILIZATION REJECTED
THERMOPLASTIC MICROENCAPSULA TION REJECTED
TRANSPORTABLE INCINERATION REJECTED
LOW TEMPERATURE THERMAL SEPARATION REJECTED
SOIL VAPOR EXTRACTION RETAINED
ENHANCED BIODEGRADATION REJECTED
SOIL FLUSHING REJECTED
VITRIFICATION REJECTED
COMMERCIAL LANDFILLING RETAINED
COMMERCIAL INCINERATION RETAINED
CAPPING RETAINED
SLURRY WALL REJECTED
GROUTING REJECTED
SHEET PILING REJECTED
CONTAINER PILES REJECTED
ON-SITE LANDFILL REJECTED
RETAINED
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REASON
EFFECTIVENESS AND COSTS
NOT A DEMONSTRATED TECHNOLOGY
COSTS
LIMITED APPLICATION
NOT FULLY DEVELOPED
NOT DEMONSTRATED TECHNOLOGY
LIMITED FULL-SCALE APPLICATION
EFFECTIVENESS
EFFECTIVENESS
NOT DEMONSTRATED TECHNOLOGY
NO FIELD APPLICATION FOR SOILS
IMPLEMENTATION
IMPLEMENTATION AND EFFECTIVENESS
MORE EFFECTIVE TECHNOLOGY AVAILABLE
LIMITED EFFECTIVENESS
EFFECTIVENESS
IMPLEMENTATION
IMPLEMENTATION
IMPLEMENTATION
LIMITED FULL-SCALE APPLICATION
MORE EFFECTIVE TECHNOLOGY AVAILABLE
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5.0 DEVELOPMENT OF ALTERNATIVES
Remedial action alternatives represent a directed application of feasible technologies
towards areas of potential risk or site restoration. The technology screening in Section 4
evaluated options on an individual basis without reference to their part in a comprehensive
remedial action. The purpose of this section is to assemble the retained technologies into
functional alternatives considering site-specific factors and then to evaluate the alternatives
collectively. This initial screening of alternatives has been conducted to select the best
remedial schemes based on the overall nature of the Site. The alternatives retained from
this evaluation are subjected to a detailed analysis in Section 6.
Potential alternatives have been developed for ground-water control and source control.
The NCP requires that a range of alternatives including treatment be evaluated to reduce
toxicity, mobility, or volume of contaminants be developed. The range includes alternatives
which remove or destroy the residual chemicals, and to the maximu_m extent feasible
eliminate or minimize the need for long-term management. Alternatives have also been
developed which involve little or no treatment but which provide protection to human health
and the environment by preventing or controlling exposure to the contaminants through
engineering or institutional controls. The no action alternative for each media has also been
retained to provide a baseline for comparison, as required by the NCP.
5.1 AREAS OF POTENTIAL REMEDIATION
Determination of areas potentially meriting remediation was performed through the baseline
risk assessments (Sirrine, 1991b), through the assessment of chemical-specific ARARs,
and the development of site-specific remedial levels (Section 3). Existing significant risks
and the capability to generate future impacts on other media are both criteria for targeting
areas for potential remediation. The Site poses no existing significant risks, but does
present the possibility of generating future impacts. Areas of potential remediation that
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would eliminate or reduce future impacts are described below. The given volumes and
areas of media of potential remediation are summarized from Section 3.3.
5.1.1 Ground-Water Control
Ground water currently poses no risks to human health and the environment. The risk
assessment, however, considered future risks if Site ground water were used as a potable
water supply. Potential future risks from this scenario were found to be significant (Risk
Assessment, Sirrine, 1991b). Consequently, remedial alternatives were considered that
would potentially reduce future risks associated with ground water to acceptable risk levels.
Ground water at portions of the site exceeds ARARs. Ground water control alternatives
were considered that achieve ARARs at the Site and at the property line, a potential point
of exposure in the Mure.
5.1.2 Source Control
Potential remediation is indicated for subsurface soils underlying former Lagoon 7 (Upper
Macon) as tetrachloroethene (PCE) concentrations in these soils have the potential to cause
underlying ground water to exceed MCLs. Subsurface soils exceeding calculated
remediation levels are limited to the soils underlying former Lagoon 7.
Presently, Lagoon 10 wastes are effectively contained and will not adversely impact the
underlying ground water or pose unacceptable risks to human health. The cap on Lagoon
10, however, is temporary in nature and is not engineered for long term containment of the
wastes. Long term containment or remediation of Lagoon 1 0 may be necessary to control
any potential Mure risks posed by these wastes.
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Remedial alternatives will be developed that specifically address these areas. Residual
chemical concentrations at other locations at the Site are below calculated levels that could
result in human health risks or exceeding ground water standards.
5.1.3 Vessels
Potential risks associated with the Site vessels would be of an accidental nature, rather than
exposure related, therefore, they were not addressed in the Risk Assessment (Sirrine,
1991b). One potential risk associated with the vessels could be an injury related to
climbing on the tanks, tankers, and vats by trespassing children. A long-term concern is
that the contents of the vessels may spill if the vessels corrode or are otherwise damaged
(e.g., vandalism).
The risks related to the fertilizer in the box truck trailer (Figure 2.2) are considered
insignificant and similar to risks associated with agricultural and residential use of powdered
fertilizer. The risks associated with the industrial boiler in Building 2 (Figure 2.2) are also
expected to be minimal. However, remediation of the fertilizer and the boiler will be
considered to allow a more complete restoration of the Site, if necessary.
As discussed in Section 2.2.6, three vessels contain solids or oils that exceed TCLP lead
(Pb) levels (Tables A-31 and A-32). Otherwise, these data indicate that the wastes are non-
hazardous according to RCRA hazardous waste characterization. The fertilizer is assumed
to be non-hazardous according to RCRA definitions. Although there is no evidence that the
industrial boiler contains asbestos, for cost estimating, it is assumed to contain asbestos.
5.2 GENERAL SCREENING CRITERIA
The purpose of this section is to screen defined alternatives through a comparative
evaluation and generate a refined list for detailed analysis. Screening is conducted under
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the broad criteria of effectiveness, implementability and cost. Descriptions of these criteria
are presented below. Within these criteria, consideration is given to construction and
Implementation activities (short-term effectiveness) and any residual risk remaining after the
completion of remedial activities (long-term effectiveness). While the screening at this stage
is general, pending the more thorough and extensive analysis in Section 6, the evaluation
is sufficiently developed to allow differentiation among .alternatives.
5.2.1 Effectiveness
The primary consideration for an alternative is its protectiveness of human health and the
environment. Associated considerations include the reduction in toxicity, mobility or volume
of Site residuals that will be achieved. Short-term factors include protection of the
community and on-site workers during construction and implementation. Long-term factors
include potential risks from remaining residuals and the potential need to replace the
remedy in the future.
5.2.2. Implementability
The implementability criterion evaluates the technical and administrative feasibility of
constructing, operating, and maintaining an alternative. Technical feasibility refers to the
ability to construct, reliably operate, and satisfy action-specific regulations. Administrative
considerations include the ability to obtain regulatory approvals (where necessary), public
acceptance, available treatmenVdisposal capacity, and the availability of necessary
equipment and personnel.
5.2.3 Cost
Cost is a secondary criteria used to evaluate equivalent alternatives. Those alternatives that
are equivalent in cost but clearly would not achieve as effective a remediation as other
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alternatives are rejected from further consideration. Alternatives that achieve the same level
of treatment but at considerably higher cost also are rejected. Otherwise, cost is not used
as an elimination criteria at this juncture.
General capital, mobilization, start-up, and operational costs are considered during the
evaluation of technologies. Because of the limited detailed technical information available
and the accuracy required for this phase of the evaluation, only a preliminary cost analysis
is necessary. Present worth costs are used to allow common comparison of alternatives.
5.3 FORMULATION OF POTENTIAL ALTERNATIVES
Potential remedial alternatives are presented below for the following areas of application:
•
•
•
5.3.1
ground-water control
source control
vessels .
Ground-Water Control
Ground-water control alternatives involving direct remediation would include elements of
ground water recovery, treatment and discharge. These elements would be required for
all the extraction options described in Section 5.1.1 and are evaluated individually below.
The no action alternative is also developed under the ground water recovery alternatives.
5.3.1.1 Ground-Water Recovery
The only retained technology for ground-water recovery is extraction wells. All ground
water remediation alternatives will be based on the use of extraction wells. Ground water
recovery options would achieve MCLs at the property lines or across the Site. The no
action alternative will also be developed for ground water control, as required by the NCP.
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5.3.1.2 Ground-Water Treatment
Ground-water treatment is directed at the removal of volatile organics and potentially metals,
as required for discharge. Retained technologies are air stripping, carbon adsorption,
chemical oxidation (UV-ozone), filtration and coagulation. All of these technologies can be
designed to handle the anticipated flow rates and mass loadings. The required level of
treatment is dependent on the selected discharge option, although all of the retained
options can meet the range of anticipated effluent concentrations.
5.3.1.3 Ground-Water Discharge
Discharge options for treated ground water are to a surface water (Solomons Creek) or
provisionally to an infiltration gallery. Discharge to the infiltration gallery was provisionally
retained because its feasibility cannot be determined until field testing is conducted to
establish that the required flow rates can be discharged at the Site. Infiltration would be
conducted downgradient of the extraction system and a significant portion of water would
eventually discharge to Solomons Creek, limiting any advantages of this system over direct
discharge. Infiltration would be considerably more costly and more difficult to operate and
maintain than direct discharge to Solomons Creek (although accurate costs cannot be
estimated prior to field testing). For purposes of the FS, ground water discharge would be
to Solomons Creek. The actual discharge point would be determined during Remedial
Design.
5.3.1.4 Concerted Ground-Water Alternatives
Potential technologies for each element of ground-water remediation have been combined
in a logical, technically sound fashion to create overall alternatives for ground water control.
Each of the comprehensive alternatives for ground water control are described below and
summarized in Table 5.1.
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ALTERNATIVE GWC-1: No Action
Alternative GWC-1A: No further activities
Alternative GWC-1B: Long-term monitoring of Site ground water
This alternative is required under the NCP. There would be no ground water extraction
under this alternative and hence no treatment or discharge. Mitigation of chemical migration
would be through natural attenuation processes such as adsorption and dispersion.
Alternative GWC-1A would be a true no action alternative and involve no further activities
to assess ground water migration potential. Alternative GWC-1 B would include long-term
monitoring of Site ground water for VOCs and deed restrictions.
ALTERNATIVE GWC-2
Alternative GWC-2A:
Alternative GWC-2B:
Alternative GWC-2C:
Recovery and treatment of all Site ground water exceeding
MCLs
Air stripping, coagulation/filtration
Carbon adsorption, coagulation/filtration
Chemical oxidation, coagulation/filtration
All Site ground water currently exceeding MCLs would be recovered using extraction wells,
treated and discharged on site. The maximum anticipated ground water extraction rate is
approximately 40 gpm. The proposed extraction system layout is presented in Figures
C.1 and C.2. Treatment options for VOCs include air stripping, carbon adsorption and
chemical oxidation. Options for metals treatment, if necessary, include coagulation and/or
filtration. Tq be conservative, costs for metals removal are based on coagulation.
Discharge options include a surface water (Solomons Creek) and an infiltration gallery.
5.3.2 Source Control
Source control addresses residual chemicals remaining in Site soils. As described in
Section 5.1, soils exceeding the calculated levels protective of ground water (former Lagoon
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7) or having the potential for significant risks to human health and the environment will be
considered for potential remediation. While not posing a significant risk to human health
or having the potential to impact ground water, soils at Lagoon 10 will be evaluated for
remediation to allow for the evaluation of a more comprehensive restoration of the Site.
The no action alternative would be developed as a baseline of comparison for remedial
alternatives. Source control alternatives are described below and summarized in Table 5.1.
ALTERNATIVE SC-1: No Action
Site soils would be left in place and no remedial efforts would be conducted under this
alternative. Site soils present no significant risks to human health and there are no ARARs
governing allowable chemical levels. Institutional controls (e.g. fencing or deed restrictions}
are therefore not required. Subsurface soils underlying former Lagoon 7 would continue
to act as a source of chemicals to ground water under this alternative. The temporary
cover over Lagoon 10 would remain in place and unimproved. This alternative is required
under the NCP .
ALTERNATIVE SC-2: Capping
Former Lagoon 7 and Lagoon 10 would be covered with a low permeability caps under this
alternative. Capping would greatly restrict infiltration to soils and thereby remove the driving
force for chemical migration to the ground water at former Lagoon 7. The existing cap at
Lagoon 10 would be replaced with a low permeability cap engineered for long-term
containment of wastes and more effective maintenance. Capping would isolate Lagoon .1 o
wastes from any potential human and environmental exposure in the future.
The areal extent of the former Lagoon 7 and Lagoon 1 0 caps are presented in Figures 5.1
and 5.2, respectively. The extent of coverage exceeds that of the lagoon boundaries as
presented in the figures. Site coverage was increased to improve constructability and
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reduce the maintenance requirements of the cap. The capped area for former Lagoon 7
and Lagoon 10 is approximately 7,500 square feet and 13,000 square feet, respectively.
ALTERNATNE SC-3: Soil Vapor Extraction and Capping
Source areas with chemical levels exceeding calculated levels that are protective of ground
water (Tables 3.4 -3.8) would be remediated through soil vapor extraction (SVE). The
only compound exceeding subsurface soil remediation levels Is PCE In former Lagoon 7
(Figure 5.1 ). SVE is a demonstrated technology for Site chemicals and geology that will
permanently reduce the volume of chemical residuals. The existing cap at Lagoon 1 O
would be replaced with a permanent engineered design.
ALTERNATNE SC-4: Bioremedialion and Soil Vapor Extraction
Lagoon 10 materials would be excavated and bioremediated in a waste treatment cell. The
volume of excavated wastes is estimated to be approximately 1,000 cubic yards. Organic
compounds contained in the excavated soils would be permanently destroyed, effecting a
permanent reduction in the volume of Site contaminants. Excavation of the waste could
potentially increase direct exposure of the waste to site workers. Remediated soils would
be returned to Lagoon 10. Soil vapor extraction would be applied to Lagoon 7 under this
alternative.
ALTERNATNE SC-5: Off-Site Landfilling and Soil Vapor Extraction
Lagoon 10 materials would be excavated to a depth of approximately 10 feet (to native
soils) and disposed off-site In a secure landfill under this alternative. The volume of
excavated materials is estimated to be approximately 1,000 cubic yards. The volume of
materials at the Site would be permanently reduced under this alternative, although the
absolute volume would not be reduced. Off-site landfilling was used for the disposal of
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soils from the other Site lagoons during the immediate removal action. Excavation and
disposal of Lagoon 10 wastes could potentially increase direct exposure to workers
handling the soil and the public in route to the secure landfill. Soil vapor extraction would
be applied at Lagoon 7 under this alternative.
ALTERNATIVE SC-6: Off-Site Incineration
Lagoon 10 materials would be excavated to a depth of approximately 10 feet (to native
soils) and sent to a RCRA-approved facility for bulk incineration under this alternative.
Lagoon 7 materials would be excavated to a depth of approximately 27 feet. The total
volume of excavated materials is estimated to be approximately 2,300 cubic yards.
Materials would be placed in lined and covered roll-off containers for transportation to the
off-site facility. Based on discussions with RCRA-approved facilities with bulk soil capacity,
the most cost-effective off-site incineration would be at the Rollins facility in Deer Park,
Texas. The volume of materials would be permanently reduced under this alternative,
although such a reduction is not directed by any risks to human health or the environment.
Excavation and transportation of Lagoon 7 and 1 O materials could potentially Increase direct
exposure to workers handling the soil and the public in route to the incinerator.
5.3.3 Vessels
Two potential remediation alternatives for Site vessels will be examined (Table 5.1):
• Alternative V-1: No action
• Alternative V-2: Off-site disposal.
The no action alternative (V-1) would leave the vessels in their current conditions. Off-site
disposal (V-2) would involve:
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(1) pumping (Tanks 3 and 4) or scraping (Vat 4 solids) vessel contents for off-site
disposal as a RCRA hazardous waste,
(2) pumping the RCRA non-hazardous wastes out of the remaining vessels for off-site
treatment or recycling as a non-hazardous waste,
(3) pressure washing the vessels (except Tankers 1 and 2) and collection of the rinsate
with its respective category (hazardous or non-hazardous),
(4) cutting the vessels up for disposal as scrap steel,
(5) on-Site or off-site burial of Tankers 1 and 2 (difficult to clean because of the tar and
solids in them, both non-hazardous),
(6) disposal or recycling the fertilizer as a non-hazardous waste, and
(7) on-Site or off-site burial of the industrial boiler.
5.3.4 Preliminary Costs for Alternatives
Preliminary costs for the potential source control and ground water control alternatives are
presented in Table 5.2. Alternatives. are referenced by the number in Table 5.1 .
Construction and operational costs for the ground water and source control alternatives
. were developed using the Cost of Remedial Action (CORA) model (EPA, 1990). The
approximate level of accuracy for these cost estimates is -50 to + 100 percent, as
suggested by the EPA document Guidance on Feasibility Studies Under CERCLA (April
1985). Costs were developed on a present worth basis using an interest rate of 5 percent.
Costs for ground water control alternatives are based on a 30 year lifetime, the longest
allowed under EPA guidance. Projected present worth costs for these alternatives should
therefore be conservative.
For the Site vessels, preliminary estimates are based on bids received from four qualified
subcontractors. Estimated cost for alternative V-2 is $300,000. Detailed costs estimates
will be prepared in Section 6.
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5.4 SCREENING EVALUATION
The assembled alternatives are screened below according to the criteria listed in Section
5.2. Alternatives remaining after this screening will be subjected to detailed analysis in
Section 6.
5.4.1 Ground-Water Control
ALTERNATIVE GWC-1: No Action·
The no action alternative will be retained as required by the NCP. Should the no action
alternative be selected, ground-water remediation would occur solely through natural
processes. Remediation of Site ground water under this alternative would not be necessary
because of environmental considerations since average concentrations at the nearest
potential point of exposure, Solomons Creek, are projected to be below AWQC. Based on
these limited potential risks, both no action alternatives will be retained. Alternative GWC-
1 A would involve no further remedial or assessment activities. Alternative GWC-1 B would
involve no remedial activities but would include long-term monitoring of Site ground water
and deed restrictions.
ALTERNATIVE GWC-2: Recovery and treatment of all Site ground water exceeding
MCLs
Alternative GWC-2 would attempt to recover Site ground water that exceeds MCLs. Within
Alternative GWC-2, options are differentiated by the process used to treat ground water;
air stripping, carbon adsorption, or chemical oxidation. Each of the processes is
demonstrated as effective for the removal of voes to non-detection limits and can be
readily implemented using standard construction techniques. The major difference among
the Alternative GWC-2 options is the present worth cost. From Table 5.2, the costs for
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carbon adsorption (GWC-28) and chemical oxidation (GWC-2C) are significantly higher than
for air stripping (GWC-2A). Since these alternatives are equal in effectiveness to air
stripping but are significantly more expensive, they are rejected under the cost criterion.
Alternative GWC-2A is the only option retained for detailed analysis.
5.4.2 Source Control
ALTERNATIVE SC-1: No action
The no action alternative will be retained as required by the NCP. If selected, volatile
organics within subsurface soils below former Lagoon 7 will continue to pose potential risks
to the underlying ground water below. The existing cap providing containment of Lagoon
10 wastes would remain in its current condition.
ALTERNATIVE SC-2: Capping
Capping is a proven and effective technology that can be readily implemented at the Site
using standard construction techniques. The proposed caps over former Lagoon 7 and
Lagoon 1 O are illustrated in Figures 5.1 and 5.2, respectively. Capping outside of Lagan
7 is not necessary for the protection of underlying ground water. The caps would
substantially reduce infiltration of precipitation through the vadose zone, thereby reducing
the potential risks to ground water posed by contaminants in the vadose zone. Capping
Lagoon 10 is not presently required to protect human health or ground water. However,
the proposed cap would provide long-term isolation of the underlying waste materials
beyond the anticipated lifetime of the existing cap. This remedial alternative would
effectively reduce the mobility of compounds that pose potential risks to the ground water.
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ALTERNATIVE SC-3: Soil Vapor Extraction and Capping
Soil vapor extraction (SVE) is a demonstrated technology that would permanently reduce
the level of volatile organics in subsurface soils below former Lagoon 7, SVE can be
Implemented using standard construction techniques. An engineered cap would be
constructed to replace the existing cap at Lagoon 10. Alternative SC-3 will be retained for
detailed analysis.
ALTERNATIVE SC-4: Bioremediation and Soil Vapor Extraction
Alternative SC-4 would permanently destroy a majority of the organic waste in Lagoon 10.
Bioremediation is a demonstrated process for remediating chemical residuals such as those
in Lagoon 10. Alternative SC-4 can be readily implemented and monitored bu1 would
require an upfront treatability study to establish design parameters. Bioremediation would
satisfy SARA's preference for alternatives involving treatment and is retained for detailed
analysis. SVE would be applied at Lagoon 7 under this alternative.
ALTERNATIVE SC-5: Off-Site Landfilling and Soil Vapor Extraction
Alternative SC-5 would involve the excavation and removal to a secure landfill of all waste
materials deposited in Lagoon 1 0 during the immediate removal action. This alternative
would be conducted in accordance with EPA's off-site policy and would be readily
implemented. Alternative SC-5 would be a permanent remedy for the Site and is retained
for detailed analysis. SVE would be applied at Lagoon 7 under this alternative.
ALTERNATIVE SC-6: Off-Site Incineration
This alternative would involve the transportation of Lagoon 7 and 1 O soils to a RCRA-
approved facility for incineration. From Table 5.2, the cost for this alternative is more than
600 percent higher than that of the other source control alternatives. This cost differential
is disproportionate considering the absence of risks to human health from Lagoon 7 and
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to human health or ground water from Lagoon 1 O and the availability of other effective
remedies involving treatment (soil vapor extraction, bioremediation) and total reduction in
Site volume (off-site landfilling). The considerable increase in costs would result in little or
no incremental protectiveness or environmental benefit and therefore would not be
consistent with CERCLA's requirement that remedies be cost effective. Alternative SC-6 is
therefore rejected from further analysis.
5.4.3 Vessels
Two potential remediation alternatives for Site vessels are examined (Table 5.1):
• Alternative V-1: No action
• Alternative V-2: Off-site Disposal.
The no-action scenario would involve leaving the Site vessels in their current condition.
This alternative is retained since the NCP requires that a no action alternative be retained
as a baseline for comparison .
Off-site disposal (Alternative V-2) would eliminate any potential for physical injury and
accidental release of the vessel contents. This alternative is implementable since similar
removal actions are frequently conducted throughout the United States for underground
storage tanks (USTs), retrofitting at chemical companies, and demolition work at industrial
sites. Alternative V-2 is retained for detailed analysis in Section 6.
5.5 SUMMARY OF RETAINED ALTERNATIVES
Alternatives retained after this screening are listed in Table 5.3. The source control
alternatives are presented as they would be implemented and prefaced with SC (source
control). These alternatives will be subjected to a more rigorous screening in the detailed
analysis (Section 6).
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Alternative
GWC-1
A
B
GWC-2
A
B
C
SC-1
SC-2
SC-3
SC-4
SC-5
SC-6
V-1
V-2
TABLE 5.1
POTENTIAL REMEDIAL ALTERNATIVES
MACON/DOCKERY SITE
Description
GROUND WATER CONTROL
No action
No additional activities
Institute long-term ground water monitoring
Recovery and treatment of all site ground water exceeding MCLs
Treatment using air stripping and coagulation/filtration
Treatment using carbon adsorption and coagulation/filtration
Treatment using chemical oxidation and coagulation/filtration
No action
Capping
SOURCE CONTROL
Soil vapor extraction and capping
Bioremediation and soil vapor extraction
Off-site landfilling and soil vapor extraction
Off-site incineration
No action
Off-site disposal
VESSELS
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TABLE 5.2
PRELIMINARY COSTS FOR ALTERNATIVES
MACON/DOCKERY SITE
Alternative Description Present Worth Costs
GWC-1A
GWC-18
GWC-2A
GWC-28
GWC-2C
SC-1
SC-2
SC-3
SC-4
SC-5
SC-6
V-1
V-2
No action for ground water
No action; long-term monitoring
MCLs at site; air stripping, coagulation/filtration
MCLs at site; activated carbon, coagulation/filtration
MCLs at site; chemical oxidation, coagulation/filtration
No action
Capping
Soil vapor extraction and capping
Bioremediation and soil vapor extraction
Off-site landfilling and soil vapor extraction
Off-site incineration
No action
Off-site disposal
Macon/Dockery FS 5-17
$100,000
$1,300,000
$4,300,000
$6,100,000
$5,900,000
$100,000
$770,000
$680,000
$890,000
$640,000
$6,700,000
$0
$300,000
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TABLE 5.3
RETAINED ALTERNATIVES FOR DETAILED ANALYSIS
MACON/DOCKERY SITE
GROUND WATER CONTROL
GWC-1A
GWC-1B
GWC-2A
SOURCE CONTROL
SC-1
SC-2
SC-3
SC-4
SC-5
VESSELS
V-1
V-2
Macon/Dockery FS 5-18
DESCRIPTION
No action
Long-term monitoring of ground
water
MCL.s at Site, air stripping,
coagulation/filtration
No action
Capping (Lagoons 7 and 1 O)
Soil vapor extraction (Lagoon 7) and
capping (Lagoon 10)
Soil vapor extraction (Lagoon 7) and
bioremediation {Lagoon 1 O)
Soil vapor extraction (Lagoon 7) and
off-site disposal (Lagoon 1 O)
No action
Off-site disposal
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6.0 DETAILED ANALYSIS OF ALTERNATIVES
Detailed analysis of alternatives is required by the NCP (40 CFR 300.430(e)(9)). Alternatives
retained from Section 5 (Table 5.3) will be examined in this section. Detailed analysis are
provided for ground water control (GWC), source control (SC; surface soils and vadose
zone), and Site vessel M alternatives. Following is a discussion of the evaluation criteria
used to perform the detailed analysis of alternatives.
The Macon/Dockery Site is comprised of the Upper Macon, Lower Macon, Upper Dockery,
and Lower Dockery sub-sites. Throughout the detailed analysis, the collective
Macon/Dockery site will be referred to as the "Site" (capitalized). The sub-sites will be
refereed to as "sites" (lower case).
6.1 EVALUATION CRITERIA
The NCP requirements are reflected in the interim final document Guidance for Conducting
Remedial Investigations and Feasibility Studies Under CERCLA (OSWER Dir. 9335.3-01,
October 1988). Nine evaluation criteria are presented that "have proven to be important for
selecting among remedial alternatives". These criteria provide the basis for evaluating
alternatives and subsequent selection of a remedy. The criteria are:
Overall protection of human health and the environment
Compliance with ARARs
Long-term effectiveness and permanence
Reduction of toxicity, mobility or volume of waste
Short-term effectiveness
Implementability
Present worth capital and operating costs
State acceptance
Community acceptance
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All potential remedial alternatives will be evaluated according to the above criteria, except
for State acceptance and community acceptance. State and community acceptance will be
determined based on comments received after their review of this FS. Short descriptions
of these criteria are given below.
1) Overall protection of human health and the environment: A remedial alternative must
eliminate, adequately reduce or control all current or potential risks through Identified
pathways. Short-term risks during Implementation of an alternative must be within
acceptable levels.
2) Compliance with ARARs: Considers action-specific, location-specific and chemical-
specific ARARs and to-be-considered factors. CERCLA § 121 (d)(4) provides five
waivers for ARARs for remedial actions not financed by the Fund. Potential location-
specific and chemical-specific ARARs for the Site are presented in Section 4.
3) Long-term effectiveness and permanence: Considers the residual risk following
implementation of the alternative, adequacy of process controls, need for replacement
of materials during design life.
4) Reduction of toxicity, mobility and volume: Considers type of process, volume of
waste involved, degree of reduction, degree of irreversibility, type/volume of residuals
remaining.
5) Short-term effectiveness: Considers factors relevant to implementation of the remedial
action, including protection of the community, protection of on-site workers, potential
environmental impacts (e.g., air emissions), and time required to achieve the remedy.
6) Implementability: Considers ability to construct, reliability of technology, ease of
installing additional remedial actions (if required), monitoring considerations, and any
regulatory requirements.
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7) Present worth costs (capital and operational): Capital cost includes the following:
• Mobilization
• Site development
• Equipment purchase and rental
• Engineering and construction management
• Material cost
• Excavation
• Health and safety
• Legal fees and insurance
• Contingency
Operational and maintenance cost reflect the following.
•
•
•
•
•
•
•
•
•
Equipment repair and replacement
Labor
Purchased service cost
Utilities
Cost of monitoring and analysis
Disposal cost
Administrative functions
Contingency
Review of remedy every 5 years, as required by SARA .
8) State acceptance: Assesses State concerns. As part of a cooperative agreement
with the USEPA, State acceptance will be incorporated into the FS as part of the
document review process.
9) Community acceptance: Assesses community concerns. Public comments will be
made on the Final Feasibility Study and incorporated Into the responsiveness
summary of the Record of Decision. Where appropriate, anticipated public concerns
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based on activities at similar remedial actions elsewhere are included in the Feasibility
Study.
Accuracy of the present worth costs Is +50/-30 percent, per EPA guidance. The feasibility
level cost estimates given with each alternative have been prepared from the Information
available at the time of the estimate. The final costs of the project will depend on actual
labor and material costs, actual site conditions, productivity, competitive market conditions,
final project scope, final project schedule, and other variable factors. As a result, the final
project costs may vary from the estimates presented herein.
In estimating the present worth cost a discount rate of 5 percent is used and inflation is
taken to be 0 percent. A sensitivity analysis will be used when sufficient uncertainty exists
regarding the design, implementation, operation or effective life of an alternative.
Present worth costs for long-term ground water monitoring and review of site remedy every
five years are given for each alternative where residuals would remain at the Site. Present
worth costs for these items are based on 30 years of operation, the maximum time allowed
by EPA guidance.
Schedule estimates are based on projected availability of materials and labor and may have
to be updated at the time of remediation. Construction schedules are based on good
weather, the ability to create and receive adequate and authorized access, and the
availability of required utilities. All cost and time estimates assume that the selected
Remedial Design, including construction drawings, have been approved and all negotiations
with contractors have been concluded.
Macon/Dockery FS 6-4 July 5, 1991
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6.2 GROUND-WATER CONTROL
Ground-water control refers to mitigating chemical migration in ground water at the Site.
Potential remedial requirements for ground water were described in Section 3.2.
6.2.1 AllERNATIVE GW-1: No Action
The no action alternative Includes no remedial action measures and assumes that Site
ground water would migrate as modeled in Section 3.4.1. The NCP requires that the no
action alternative be retained through detailed screening of alternatives as a baseline for
comparison.
For the Site, there are two options under the no action alternative. Alternative GWC-1A
would involve no further activities at the Site other than a review of remedy every five years.
Alternative GWC-1 B would add long-term monitoring of ground water and deed restrictions.
Detailed analysis of the alternatives is presented below .
6.2.1.1 AllERNATIVE GWC-1A: No Further Activities
No further activities would be conducted with Site ground water under this alternative.
Existing monitoring wells would be retained as is for potential use although no ground water
monitoring is included under this alternative. A review of remedy would be conducted every
five years.
Overall Protection of Human Health and the Environment
The no action alternative would be protective of human health and the environment under
current conditions. The baseline risk assessment determined that Site ground water
currently poses no risks to human health since there are no receptors. The risk
assessments (Sirrine, 1991b) determined that Site ground water posed a maximum
Macon/DOckery FS 6-5 July 5, 1991
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carcinogenic risk of 6.6 x 10-3 at the Upper Macon site under a future use (residential)
scenario. This risk level exceeds the acceptable range of 1 o-4 to 1 o-6 specified by the
NCP. Potentially significant risks to human health could occur in the future if the ground
water is used as a source of potable water. The existence of public water supply and lack
of development in the area make the potential for construction of a potable well unlikely.
The potential impact of Site ground water on environmental populations would be through
discharge to Solomons Creek In the future. Toxicity quotients indicate a possible concern
for acute/chronic effects on aquatic organisms in Solomon's Creek adjacent to the Lower
Dockery and Lower Macon Sites due to inorganics in surface water and sediments.
However, exposure point concentrations were similar to measured background levels in
most cases. Lead may be of concern in Solomon's Creek, but the source is uncertain due
to topography and drainage to the creek. Furthermore, projected ground water
concentrations at Solomons Creek are compared with Federal Ambient Water Quality
Criteria (AWQC; EPA, 1986) in Table C.3. Average concentrations at Solomons Creek are
significantly below AWOC except for chromium. The exceedance of chromium above the
AWOC is likely over estimated. Resampling of Site ground water after the RI (Section 2.2.7;
Appendix B) found that chromium was below detection limits in all wells sampled. The
assessment is conservative because all Site ground water does not discharge to Solomons
Creek. Actual chemical concentrations at Solomons Creek would be less than these shown
in Table 6.1.
Compliance with ARARs
Potential chemical-specific and location-specific ARARs are presented in Section 3.2.
Because no remedial actions are included in this alternative, there are no applicable action-
specific ARARs.
Ground water at the Site is considered a current source of drinking water (Class GA under
the State classification system and Class II A under EPA's Ground Water Classification
Macon/Dockery FS 6-6 July 5, 1991
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Guidelines). Standards that are potentially ARARs for Site ground water are Maximum
Contaminant Levels (MCLs) under the Safe Drinking Water Act (40 CFR 141.11).
EPA generally considers MCLs to be the most appropriate remediation level for Class II A
ground water. Site ground water exceeds MCLs. Based on this preliminary evaluation of
ARARs, Site ground water exceeds potential remediation levels and the no action alternative
would not satisfy chemical specific ARARs across the site without a waiver (CERCLA Part
121 (d)(4)).
No endangered species or areas of significant historical importance were identified at the
Site. The no action alternative therefore does not violate any location-specific ARARs.
Long-term Effectiveness and Permanence
The magnitude of residual risks at the Site would remain unchanged under the no action
alternative. Since waste residuals would remain at the Site, review of the effectiveness and
protectiveness of the no-action alternative every five years would be required by SARA.
Conditions at the Site are not anticipated to change significantly over a five year period.
Reduction of Toxicity. Mobility or Volume
This alternative would not significantly reduce the toxicity, mobility or volume of Site
residuals. Remediation of ground water could occur through natural processes such as
biodegradation, adsorption, and attenuation by upgradient flow. The low concentrations of
site-related chemicals that would remain in the ground water have the potential to discharge
into Solomons Creek under this alternative, although such discharge would present no
significant risks (Section 3).
Short-term Effectiveness
This alternative presents no risks to the community, on-site workers or the environment
for its implementation. The no action alternative can be implemented immediately. Since
no remedial actions are included, there is no schedule of completion .
Macon/Dockery FS 6-7 July 5, 1991
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Implementability
The no action alternative can be readily implemented and would not hinder the
implementation of any remedial actions in the future.
Cost
This alternative involves no capital costs. Operating costs are based on the review of Site
conditions every five years. There would be no maintenance costs.
The detailed cost estimate for Alternative GWC-1A is presented in Appendix F. A summary
of the estimated costs is given below:
Total Construction Costs -
Present Worth O&M Costs -
Total Present Worth Costs -
$ 0
$140.000
$140,000
6.2.1.2 ALTERNATIVE GWC-1B: Long-term monitoring of Site ground water
This alternative is an extension of Alternative GWC-1A in that long-term monitoring of Site
ground water and deed restrictions would be added. For purposes of the FS. a maximum
of ten additional monitoring wells would be constructed. Sampling here is assumed to be
a twice per year event with analyses for voes and metals. The adequacy of the existing
well portfolio and sampling frequency would be established during Remedial Design. Deed
restrictions would be used to limit potential uses of ground water on the Macon/Dockery
property as a conservative measure, although they would not be required based on current
human health considerations.
Evaluation of the no action portion of this alternative would be as described for Alternative
GWC-1A (Section 6.2.1.1). The evaluation here will focus on the additional requirements
and considerations associated with long-term monitoring and deed restrictions.
Macon/Dockery FS 6-8 July 5. 1991
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Overall Protection of Human Health and the Environment
Site ground water poses no risks to human health under baseline conditions but could
present significant risks under the hypothetical future risk scenario. Deed restrictions would
be used to reduce the minimal potential for creation of a potable well on the
Macon/Dockery property and thereby any Mure risks. The remainder of the evaluation
under this criterion would be the same as for Alternative GWC-1A (Section 6.2.1.1).
Compliance Wrth ARARs
Monitoring of Site ground water wells would allow assessing the appropriateness of ACLs
or the effectiveness of natural remediation mechanisms towards achieving MCLs. The
remainder of the evaluation under this criterion would be the same as for Alternative GWC-
1A.
Long-term Effectiveness and Permanence
The magnitude of risks at the Site would decrease slightly (e.g., degradation and attenuation
of Site chemicals) but essentially remain unchanged under this alternative. Periodic
monitoring of Site ground water would be conducted to evaluate the potential for risks in
the Mure. Institutional controls might be necessary to prevent any future use of ground
water Influenced by Site activities, although the availability of a municipal water supply
indicates that potential ground water uses are unlikely.
Since waste residuals would remain at the Site, review of the effectiveness and
protectiveness of the no action alternative every five years would be required by SARA.
Conditions at the Site are not anticipated to change significantly over a five year period.
Reduction of Toxicity. Mobility or Volume
Natural mechanisms could effect a gradual reduction In contaminant concentrations that
could be evaluated through the system of monitoring wells.
Macon/DOCkery FS 6-9 July 5, 1991
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Short-term Effectiveness
This alternative presents no risks to the community, on-site workers or the environment
through its implementation. This alternative can be implemented immediately following the
installation of additional monitoring wells. Installation of the additional ten monitoring wells
would take approximately two months.
Implementability
Numerous monitoring wells have been installed at the Site. Construction of additional wells,
if necessary, would pose no significant technical concerns. Ground water discharge is the
sole migration pathway and this can be readily monitored using the existing monitoring
wells. The no action alternative would not hinder the implementation of any remedial action
in the future.
The no action alternative would require Institutional controls to govern future use of the Site.
The adequacy of these controls to protect human health and the environment should be
evaluated periodically to maintain their effectiveness.
Cost
Capital costs include the construction of ten additional monitoring wells. Operating costs
include periodic sampling of selected monitoring wells, chemical analyses, reporting and
review of the Site conditions every five years. Maintenance costs would include inspection
of the monitoring wells.
The detailed cost estimate for this alternative is presented in Appendix F. A summary of
the estimated costs is given below:
Total Construction Costs -
Present Worth O&M Costs
Total Present Worth Costs -
Macon/Dockery FS 6-10
$ 140,000
$1,700,000
$1,800,000
July 5, 1991
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6.2.2 ALTERNATIVE GWC-2k. MCL.s at the Site
This alternative involves the recovery of ground water such that MCL.s would not be
exceeded at the Site. The remediation system would include well point extraction, treatment
of the extracted ground water, and subsequent discharge to Solomons Creek. The
proposed extraction system would Involve installation of 12 recovery wells at the Upper
Macon, Lower Macon, Upper Dockery, and Lower Dockery sites and is presented in Figures
C.1 and C.2. The total extracted flow rate is anticipated to be approximately 40 gpm.
Actual design of the extraction system would be established during Remedial Design.
Capture zone effectiveness would be evaluated through aquifer response measurements
conducted during construction of the overall extraction system.
Compounds potentially requiring treatment in ground water are voes and metals. voes
would be treated through air stripping. The need for control of air stripper emissions is
evaluated in Appendix G through a comparison of modeled airborne concentrations at the
property line with North Carolina acceptable ambient levels (15 NCAC 2D.1104). Maximum
site emissions would be significantly below allowable ambient levels and would not require
control.
Metals removal at the Site was evaluated by comparing the analyses of total (unfiltered)
ground water with ground water filtered through a 5 micron filter (Appendix B). A 5 micron
filter was selected because standard cartridge or bag filters can be equipped with this cut.
Monitoring wells were purged using a bladder pump for the evaluation to minimize any
turbidity that could contribute to metals concentrations in the sample and to mimic actual
extraction wells. Comparison of the filtered and unfiltered results indicates that metals levels
have decreased significantly in comparison with samples collected by bailer during the RI
and that the only metals passing through the 5 micron filter are barium, manganese, nickel
and zinc. Federal Ambient Water Quality Criteria (AWQC; EPA, 1986) would be used to
establish discharge concentrations. Chronic fresh water criteria are only available for nickel
MaconJ[)ockery FS 6-11 July 5, 1991
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(160 ug/1) and zinc (11 o ug/l). Ground water filtered through the 5 micron filter was within
these standards for all samples except one (nickel at 220 ug/l in MW-16). Since the
discharged ground water would be a blend from several extraction wells and since the
AWQC would be applied as a blended in-stream concentration, use of a cartridge filter
should be sufficient to meet discharge requirements. To be conservative, however, the
costs for this alternative are based on a coagulation system. Actual metals treatment
requirements would be established during Remedial Design.
Discharge of treated groundwater could be either to a surface water (Solomons Creek) or
to an infiltration gallery. To be conservative, construction costs are based on use of an
infiltration gallery for each treatment system at the nominal application rate of 0.5 gpd/tt2.
The actual method of discharge and operating parameters would be established during
Remedial Design.
For purposes of the FS, ground water treatment would involve the following elements:
• manifolding of the extraction well piping to treatment areas (one each at Macon
and Dockery)
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concentration equalization and sediment collection
air stripping column
cartridge filtration or coagulation (if necessary)
transfer pumps
• flow measurement and sampling
• discharge line to outfall on Solomons Creek or to an infiltration gallery.
Because of the distances involved, separate treatment facilities will be specified for the
Macon and Dockery sites in the FS. The conceptual flow diagram for ground water
treatment is presented in Figure 6.1. Actual treatment requirements would be established
during Remedial Design, should this alternative be selected.
Macon/Dockery FS 6-12 July 5, 1991
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Protection of Human Health and the Environment
The baseline risk assessments determined that there are currently no risks to human health
or the environment posed by Site ground water. Remediation of ground water to MCLs
would be protective of human health in the future should site ground water be used for
potable water. The existing municipal water supply and lack of projected development in
the area indicate that Mure uses of site ground water are unlikely. The presence of an
operating ground water remediation system would further deter any future uses.
Site ground water currently poses no risks to the environment. Treatment of Site ground
water to MCLs would ensure that in-stream concentrations in Solomons Creek would be
within AWQC. This alternative is therefore protective of the environment.
Compliance with ARARs
MCLs would be met at the Site under this alternative. Discharge of ground water to
Solomons Creek would satisfy AWQC. This alternative therefore complies with ARARs.
Treatment and discharge of ground water would be conducted entirely on-site and permits
would not be required. Discharge of treated ground water to a surface water would have
to comply with the substantive requirements of an NPDES permit, as administered by the
State of North Carolina. Discharge to an infiltration gallery would have to comply with the
substantive requirements of a Non-Discharge Permit (15A NCAC 2H.0200), as administered
by the State of North Carolina. Air stripper emissions would comply with North Carolina
allowable ambient levels. Substantive requirements would be established during Remedial
Design.
Long-term Effectiveness and Permanence
Extraction wells would achieve removal of ground water for subsequent treatment. Ground
water recovery via extraction wells and submersible pumps is a proven technology and has
a high degree of mechanical reliability. Maintenance consists of periodic inspection of the
wells, pumps and control units .
Macon/Doekery FS 6-13 July 5, 1991
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The long-term goal of this alternative would be to achieve MCLs at the site. From the
discussion in Section 3.2.3.1, aquifer desorption kinetics and limitations of ground water
recovery indicate that it is uncertain whether MCLs can be achieved at the point of
extraction. Periodic monitoring of ground water concentrations and water levels would be
conducted to establish the effectiveness of extraction operations. A five-year review of
remedy would be required until the remediation levels were achieved.
Air stripping is an effective and reliable process for achieving high removal levels of VOCs
from ground water. Filtration, if necessary, would significantly remove metals, as evidenced
by the filtered metals analyses (Section 2.2.7). Coagulation would provide a further level
of treatment if filtration alone could not achieve the required discharge levels for metals.
Ground water recovery through well point extraction and treatment by air stripping are
proven processes with a high degree of mechanical reliability. Operation would include
regular inspections and effluent monitoring. The required maintenance would present no
technical concerns .
Effluent from the ground water treatment system is expected to satisfy all discharge
requirements and would not adversely impact Solomons Creek (surface water) or Site
groundwater (infiltration gallery). Periodic discharge monitoring would be required.
Reduction of Toxicity. Mobility. or Volume
Ground water extraction would reduce the volume of chemicals at the Site while the
subsequent treatment would reduce the toxicity of ground water prior to discharge. The
mass of voes in ground water would be reduced by greater than 98 percent under this
alternative (based on the removal of TCE to MCLs at the Upper Macon site). Air stripping
and coagulation or filtration of ground water would comply with SARA's preference for
remedies involving treatment.
Macon/Doekery FS 6-14 July 5, 1991
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Short-term Effectiveness
Installation of extraction wells would pose no health risks to the community. On-site
workers can be protected from potential risks through adherence to the remedial health and
safety plan. Construction of the ground water treatment facility would pose no risks to the
community or workers.
Installation of the extraction wells and subgrade utilities would take approximately four
months. Installation of the ground water treatment system and construction of a discharge
line to Solomons Creek would require approximately four months and could occur
simultaneously with other remedial activities.
The time to achieve remediation levels cannot be accurately estimated due to adsorption
and hysteresis effects upon mass transfer chemistry between soils and ground water.
Using a batch flushing model (EPA, 1988), the estimated time for ground water extraction
such that MCL.s would not be exceeded at the property line would be a minimum of 17
years. Based on the presentation in Section 3.2.3.1, the actual time to achieve MCL.s would
potentially be considerably longer.
Implementability
Numerous monitoring wells have been constructed at the Site and no difficulties are
anticipated in construction of the extraction wells. Distribution lines to the ground water
treatment system would be below grade and heat traced to prevent potential freezing where
placed above the frost line.
Installation of an air stripper and coagulation unit or cartridge filter at the anticipated flow
rate would have no special installation requirements and the ground water treatment system
should be readily constructed. Design of the treatment system could not be completed until
the surface water or infiltration gallery discharge requirements were defined with State
personnel. Sufficient area exists at the Site for construction of infiltration galleries.
Application rates would have to be established during Remedial Design .
Macon/Dockery FS 6-15 July 5, 1991
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Cost
Construction costs associated with this alternative include mobilization; extraction wells and
the ground water distribution system; the ground water treatment system (air stripper,
coagulation unit); discharge to an infiltration gallery; upgrading the Site roads; and utility
connections. Operating costs Include power, water, and maintenance for the extraction
wells; labor, power and sampling for the treatment system; and ground water monitoring.
Sampling is assumed to be a quarterly event focused on Indicator parameters.
Maintenance costs include facility Inspections and equipment repair.
A sensitivity analysis can be applied to detailed cost estimates when there is sufficient
uncertainty associated with a key independent variable. For ground water control
alternatives, a primary factor affecting long-term operations and maintenance costs (O&M)
is the duration of remedial activities. Detailed cost estimates are typically based on 30
years of operation, the maximum costing period allowed under EPA guidance. The 30 year
period generates conservative estimates of present worth costs .
The determination of the actual period for ground water extraction is problematic because
subsurface desorption kinetics are difficult to quantity. Based on the batch flushing model,
the estimated time to achieve MCLs at the property line would be at least 17 years. Detailed
cost estimates based on operation for 30 years and 17 years are presented in Appendix
F and summarized below.
Total Construction Costs -
Present Work O&M Costs -
Total Present Worth Costs -
MaconJ[)ockery FS
DURATION
30 years
$ 1,700,000
$ 5,200,000
$ 6,900,000
6-16
17 years
$1,700,000
$3,800.000
$5,500,000
July 5, 1991
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6.3 SOURCE CONTROL
The purpose of source control Is to address chemical residuals in soils that could cause
potential risks to human health or adversely impact ground water. Source control
alternatives will be considered for soils at the Macon/Dockery Site that could pose potential
risks to human health or adversely impact ground water. While not posing a risk to human
health or the environment, materials within Lagoon 1 O will also be considered for
remediation to present a comprehensive range of alternatives. Retained alternatives were
presented in Table 5.3. The detailed analysis of these alternatives is presented below.
6.3.1 ALTERNATIVE SC-1: No Action
EPA conducted an Immediate removal action at the Site that commenced in November
1983. Remedial activities included:
• removal of 808 55-gallon drums of wastes
• disposed of 2,142 tons of solidified waste and 111,000 gallons of waste oil
• recycled 26,000 gallons of oil
• landfarmed 467,000 gallons of lagoon water
• excavation and backfilling of all lagoons except Lagoon 1 O
• disposed of solidified sludge from Lagoon 7, boiler flyash, 43 crushed drums,
and contaminated soil in Lagoon 1 o
• backfilled and capped Lagoon 1 O with a synthetic liner and a 3-foot thick clay
cover.
The RI found limited levels of chemical residuals remaining at the Site, Indicating that the
great majority of residuals formerly at the Site were removed under the immediate removal
action. Under the no action alternative, no further remedial activities would occur.
Macon/Dockery FS 6-17 July 5, 1991
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Overall Protection of Human Health and The Environment
Results of the baseline risk assessments are presented in Section 3.1 and summarized in
Table 3.0. The NCP specifies an acceptable exposure level range of 10-4 to 10-6 for
carcinogenic risks (40 CFR 300.430 (e)(i)(A)(2)). Risk levels less than 10-6 are not
considered significant. At the Site under current conditions all estimated risks associated
with exposure to surficial soils are within the NCP acceptable risk range. Surficial soils at
the Upper and Lower Macon Sites represent a carcinogenic risk of 6.2 x 1 o·5 and
4.2 x 10·5, respectively. These values are within the NCP range of acceptable exposure
levels and does not represent a significant risk to human health. Noncarcinogenic health
hazard is insignificant.
The baseline risk assessments also considered a future use scenario involving potential
residential use of the Site. The only potentially significant carcinogenic risks under the
residential scenario are associated with exposure to surficial soils at the Upper and Lower
Macon sites. Surficial soils here represent a potential future risk of 4.6x1 o·4 and
3.6 x 10-4, respectively. These risks were principally due to arsenic at Upper Macon and
PAHs at Lower Macon. Arsenic values, except in two instances, were similar to surface soil
background levels and are significantly less than the proposed RCRA corrective action level
of 80 mg/kg. PAHs are at or similar to control soil surface sample concentrations at 22 of
28 sample locations on the Macon Site. Elevated PAH concentrations at Upper Macon
appeared to represent hot spots associated with former lagoons and waste storage areas,
while those at Lower Macon were present in an area where waste water from the former
lagoons was sprayed onto the ground during initial cleanup operations. Significant
uncertainty was introduced by the use of surrogate toxicity factors for PAHs lacking slope
factors and reference doses. The respective risk estimates of 4.56 x 1 o-4 and
3.58 x 10-4 for Upper and Lower Macon are related to limited localized hot spots and
embody significant uncertainty. It is therefore uncertain whether these risks actually exceed
the NCP acceptable risk range.
Macon/DOCkery FS 6-18 July 5, 1991
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The NCP does not address non-carcinogenic risks. According to EPA guidance, hazard
quotients greater than unity represent a potential concern for non-carcinogenic effects (EPA,
1989). The level of concern increases as the hazard quotient exceeds unity. Health
hazards from exposure to surficial soils do not exceed a hazard quotient of one under
current conditions (Table 3.0).
In summary, current and potential future carcinogenic risks from Site soils are generally
within acceptable levels specified by the NCP. Non-carcinogenic risks posed by Site
surface soils have a hazard quotient of less than unity. Site soils therefore represent
minimal, if any, risks to human health. The no action alternative is therefore protective of
human health.
The no action alternative would include deed restrictions to limit any development of the
Macon or Dockery properties in the future. The effectiveness of deed restrictions would
have to evaluated periodically so that potential human exposures at the Site in the Mure
are controlled .
Modeling of residual compound transport in the vadose zone (VIP model) indicated that
tetrachloroethene (PCE) concentrations in subsurface soils beneath former Lagoon 7, could
potentially cause ground water to exceed MCLs. Under the no-action scenario, any
leaching of PCE from the vadose zone to the ground water would not be controlled. No
other sources of residual compounds on Site are estimated to have the potential to impact
Site ground water above MCLs. Ground water discharge of PCE to Solomons Creek would
satisfy AWQC and be protective of the environment.
The environmental endangerment assessment indicated a possible concern for effects on
aquatic organisms in Solomon's Creek adjacent to the site and for effects on wildlife on the
Macon site. Potential toxic effects would depend upon site specific variables. It is expected
that adverse effects would be localized. The need for any additional biological monitoring
would be determined in the RD/RA phase.
Macon/Dockery FS 6-19 July 5, 1991
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Compliance with ARARs
There are no Federal or State ARARs for site contaminants in soils. Potential location-
specific ARARs are presented in Section 3.2.2 and summarized in Table 3.1. No
endangered species or areas of significant historical importance were identified at the Site.
The no-action alternative, therefore, does not violate an location-specific ARARs. There are
no action-specific ARA Rs for this alternative.
Long-term Effectiveness and Permanence
The magnitude of remaining risks would be essentially unchanged under this alternative.
Natural degradation mechanisms such as volatilization and biodegradation might effect
some reduction in organic residuals. Metals levels would not be expected to change
significantly in the Mure.
Deed restrictions would discourage Mure uses of the Site and limit potential Mure risks.
The long-term effectiveness of deed restrictions is uncertain, although it is unlikely that the
Site would ever be used for residential purposes and even more unlikely that a financial
institution would lend funds for development at the Site.
Since waste residuals would be left at the Site, review of the effectiveness and
protectiveness of the no !3ction alternative every five years would be required by SARA.
Conditions at the Site are not anticipated to change significantly over a five year period.
Reduction of Toxicity, Mobility or Volume
This alternative would not significantly reduce the toxicity, mobility or volume of remaining
Site residuals. A slight level of remediation of organic residuals may occur through natural
processes such as biodegradation, adsorption and volatilization.
Short-term Effectiveness
This alternative can be implemented immediately without environmental impact or increased
community or worker exposure.
Macon/Dockery FS 6-20 July 5, 1991
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Implementability
The no action alternative could be readily implemented and would not hinder the
implementation of any remedial actions in the Mure. No Site maintenance would be
required.
The no action alternative would include institutional controls to govern Mure use of the Site.
The adequacy of these controls to protect human health and the environment could be
evaluated periodically to establish their effectiveness.
Cost
There are no construction costs. Operating costs would involve a review of remedy every
five years. The detailed cost estimate for this alternative is presented in Appendix F. A
summary of the estimated costs is given below:
6.3.2
Total Construction Costs -
Present Worth O&M Costs -
Total Present Worth Costs -
ALTERNATNE SC-2: Capping
$ 0
$190,000
$190,000
This alternative involves construction and operation of two low permeability caps over
Lagoon 7 and Lagoon 10, as shown in Figure 5.1. The cap over Lagoon 7 would address
the potential for residual soil concentrations of PCE to impact ground water above MCLs.
The existing cap over Lagoon 1 O would be replaced with a permanent design as a
preventive maintenance measure to allow better long-term control of waste residuals.
Neither cap is required for the protection of human health or the environment.
The caps would deny infiltration to the underlying soils. By limiting infiltration, the potential
for chemical transport to ground water is significantly reduced. This consideration is
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potentially significant only for the Lagoon 7 cap. The transport of PCE from subsurface
soils below former Lagoon 7 to the ground water would be effectively mitigated.
Consequently, the potential risks to ground water posed by PCE would be greatly reduced.
The areal extent of the Lagoon 7 cap would be approximately 7,500 square feet. •
Capping of Lagoon 10 is not necessary based on the potential to impact ground water
above MCLs. Construction of the Lagoon 10 cap would replace the existing cover, thereby
providing the added assurance that containment of residual chemicals within Lagoon 1 0
would be secured indefinitely. The areal extent of the replacement cap for Lagoon 10
would be approximately 13,000 square feet.
Construction of a cap involves the use of heavy earth moving and grading equipment.
Existing access may have to be improved for optimal use of this equipment. Clearing of
brush contiguous to the capping areas may be required. Vegetation and any stumps would
be grubbed below the surface to prevent regrowth and ground water observation wells not
needed for long-term monitoring would be abandoned. The cap would be constructed of
a single layer synthetic liner over the compacted sub-base.
A multi-layer cap including compacted clay, as specified under RCRA, is not felt to be
appropriate for the Site. EPA's Hydrological Evaluation of Landfill Performance (HELP)
model was applied using site-specific data to evaluate caps based on the following low
permeability barriers:
•
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40-mil high density polyethylene (HDPE) liner and one foot of compacted clay
60-mil HDPE liner.
The model determined that there was no significant differences in performance of the two
capping systems. Shipping the required quantities of clay to the Site would increase costs
without increasing the effectiveness of the remedy. The long-term reliability of synthetic
Macon/DOCkety FS 6-22 July 5, 1991
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liners is well established (Gundle, 1990) and a redundant barrier should not be necessary.
Single synthetic liners have been approved to cap areas at other CERCLA sites in Region
IV (Sirrine, 1990). A 60-mil HOPE liner would therefore be the most appropriate low
permeability barrier to achieve Site capping requirements. For purposes of the Feasibility
Study, the Site caps would consist of a compacted sub-base of common and select fill, 60-
mil HOPE liner, drainage net, filter fabric, soil cover and vegetation. Permeability of the cap
would be approximately 1 x 10-13 emfs (Gundle, 1990). Actual design and materials of
construction would be determined in the Remedial Design phase, should a capping
alternative be selected for implementation.
Lagoon 10 is currently covered with approximately three feet of compact clay. The existing
clay would be used as a sub-base for the replacement cap to the extent possible. On-site
borrow areas would be evaluated for use as common and select fill for construction of the
sub-base for Lagoon 7.
Drainage swales would be constructed along the cap perimeter to control surface run-on
and direct cap run-off. A security fence would be constructed along the perimeter of the
cap to deter unauthorized access.
Placement of the cap would be as presented in Figure 5.1. Materials beneath the cap
would consist of saprolite soils containing low levels of inorganic and organic chemical
residuals. These soils are well consolidated and substantial settling beneath a cap is not
anticipated. Markers would be placed on the cap to define any settlement. Appreciable
gas generation beneath the cap would be anticipated only for Lagoon 10. A gas venting
system would be considered for Lagoon 10 during Remedial Design.
Overall Protection of Human Health and the Environment
Site soils do not pose potentially significant risks to human health. Consequently, capping
is not required for the protection of human health, The Lagoon 7 cap would significantly
Macon/DOCkery FS 6-23 July 5, 1991
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reduce the leaching potential of PCE in subsurface soils. A reduced leaching potential
would translate into lower chemical loadings into ground water, hence lower risks to
potential downgradient receptors in the future. No soils outside of the cap have the
potential to Impact ground water above MCLs. The Lower Macon surface cap would
effectively upgrade the existing cap over Lagoon 10, thereby ensuring that any potential
risks to human health and ground water will be controlled indefinitely. Alternative SC-2
would be protective of human health and the environment.
Compliance with ARARs
RCRA treatment and disposal requirements are not ARAR for capping at the Site. However,
the single synthetic liner design would still meet an equivalent performance standard of
RCRA (40 CFR 264.310), as follows:
i) provide long-term minimization of migration of liquids
ii) function with minimum maintenance
iii) promote drainage and minimize erosion or abrasion of the cover
iv) accommodate settling and subsidence to maintain cover integrity
v) have a permeability less than that of natural subsoils.
Actual design requirements would be specified during Remedial Design.
All construction activities would take place above the 100-year flood plain. The Health and
Safety Plan governing all remedial activities would conform to 29 CFR 1910.120.
Fencing around the capped area would discourage future uses. Deed _restrictions could
be included in the implementation of this alterative as a secondary control measure to
prevent uses of the Site that could reduce the effectiveness of remedial measures.
Macon/Dockery FS 6-24 July 5, 1991
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Long-term Effectiveness and Permanence
Potential risks to human health due to Site soils would be an incremental future risk through
chemical transport to ground water. The potential for chemical leaching to ground water
from Lagoon 7 would be significantly less than under current conditions, as the effective
mobility of residual chemicals beneath the cap would be significantly reduced. Remaining
risks associated with chemical residuals outside of the cap would not be significant.
Leakage due to permeation of synthetic membrane liners is not significant in comparison
to flow through holes created during construction of installation (Bonaparte, 1989). Use of
a 60 mil liner would limit the potential for pin holes to be formed during manufacturing.
Vacuum testing of seams in the field would provide excellent quality assurance and control
the only other potentially significant avenue of cap leakage.
Long-term stability of the cap should be excellent with regular inspections and maintenance.
Underlying Site materials are primarily inert and minimal settling is anticipated. Synthetic
liners can accommodate slight settling due to their resiliency. Gas generation beneath the
caps would be potentially significant only for the cap overlying Lagoon 1 o. Gas venting
requirements and equipment would be addressed during Remedial Design. Gas venting
of the Lagoon 1 O cap will be included in this feasibility study for cost estimating purposes.
Periodic inspections would be required to check for erosion, settling and. conditions of the
drainage system. Deterioration of cap integrity must be identified and corrected quickly to
maintain effectiveness. The integrity of the fence must also be maintained to deter
unauthorized access. An established inspection and maintenance schedule would be
implemented following construction and continued for as long as chemical residuals
remained at the Site. Regular care of the cap system would preserve its effectiveness
indefinitely.
Macon/Doekery FS 6-25 July 5, 1991
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Caps have been constructed at numerous CERCLA sites with excellent results. Proper
construction and regular maintenance would allow a perpetual operating life. Future
replacement, if required, should be straightforward since the earthwork has already been
completed and residuals isolated during construction. Potential risks are considered
minimal should elements of the cap require repair or replacement.
Evaluating the effectiveness of this alternative could be performed through periodic ground
water monitoring. Test vents would be required to estimate gas generation potential within
Lagoon 10. Biodegradation of the materials in Lagoon 10 has the potential for appreciable
gas generation.
Since compound residuals would remain at the Site, review of the effectiveness and
protectiveness of this alterative every five years would be required by SARA. Inspection
and maintenance records for the cap as well as ground water monitoring results would be
reviewed at this time. Conditions at the Site are anticipated to improve with placement of
the cap .
Reduction of Toxicity, Mobility, or Volume
No treatment processes would be used under this alternative to destroy or reduce the
toxicity, mobility or volume of residual chemicals in Site soils. Capping would greatly
reduce the mobility and effective toxicity of residuals in Site soils. The mobility of chemicals
below the water table would be addressed through the selected ground water control
(GWC) alternative. The volume of residuals would remain unaltered after implementation
of this alternative.
Short-term Effectiveness
Implementation of this alternative would not endanger the public as the Site is in a sparsely
populated rural area and dust control would be conducted during construction.
Construction would not occur within 300 feet of State Route ·1103.
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Environmental impacts as a result of cap construction would be minimal. Erosion control
measures would be required during cap construction to prevent migration of chemical
residuals by way of surface runoff.
Grubbing and grading of the Site would be necessary for construction of the cap. An
appropriate level of personal protective equipment would be required for on-site workers
to prevent direct exposure to site surface soils. Dust control would be exercised to
minimize the potential release of air-borne particulates. Worker safety, can be controlled
through adherence to the remedial health and safety plan.
Construction of the caps could not begin until all materials are available and adequate
access had been developed. Implementation time would depend on the number of crews
involved but should be approximately three months. This schedule assumes standard
production rates and compliance with all inspections of performance requirements and
workmanship. Adverse climatic conditions could hinder construction performance and delay
the schedule. Construction should be scheduled to facilitate revegetation immediately after
final grading.
Implementability
Construction of a cap is a straightforward operation that has been accomplished at
numerous waste sites. Clearing of the Site and establishment of access for heavy
machinery should pose no difficulties. Caps have been successfully implemented at other
CERCLA sites.
The maximum slope that would have to be capped would be approximately 15 percent,
along the east side of the Lagoon 7 cap. This slope could require the use of a textured
liner, enhanced anchor support, and an erosion control mat for vegetation. These
requirements would involve additional engineering and construction measures but represent
no significant implementation difficulties.
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The availability of common and select fill material should be adequate but procurement and
transportation could control the construction schedule. The use of on-site borrow materials
should be evaluated during Remedial Design. A drainage system would have to be
constructed along the perimeter of the cap. The drainage system would collect only
rainwater, which would be redirected to the land surface. Cover design would have to
consider possible freezing In the drainage system during winter.
Liner installation would have to be scheduled for suitable climatic conditions. Seams may
be welded under freezing conditions but not during periods of precipitation. Final
construction should allow for vegetation during the growing season. Hauling the required
quantities of materials to the Site may impact traffic patterns and cause road wear. A
staging area would be required outside of the area to be capped.
Lead time for the HDPE liner and geotextile materials is approximately one month and
competitive sources should be available. Identification of the common and select fill
sources would be the single greatest lead item. Cap construction is a common remedial
measure and there should be a number of qualified bidders.
Cap maintenance can be readily implemented. Periodic cap maintenan_ce would primarily
involve grass cutting and clearing any accumulation in the drainage swales. Inspections
would be required to determine whether repairs to the cap, drainage system, or fence are
required. The gas vent system for Lagoon 10, if required, would be inspected and have
gas samples analyzed periodically.
The effectiveness of this alternative for Lagoon 7 would be measured by the changes in
local ground water quality over time. In coordination with the selected ground water
extraction scheme, an overall decrease in Site chemical concentrations would be expected
in area monitoring well samples.
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Cost
Construction costs associated with this alternative include mobilization, excavation, grubbing,
grading, earth work, materials, and labor. Operating costs include maintenance of the cap
and review of the Site remedy every five years. Sampling is assumed to be a biannual
event focused on indicator parameters. Maintenance costs include peric,dic inspections and
grounds keeping.
The detailed cost estimate for this alternative is presented in Appendix F. A summary of
the estimated costs is given below:
6.3.3
Total Construction Costs -
Present Worth O&M Costs -
Total Present Worth Costs -
ALTERNATIVE SC-3:
$430,000
$260,000
$690,000
Capping and Soil Vapor Extraction
This alternative involves the construction and operation of a replacement cap over Lagoon
10 and a soil vapor extraction (SVE) system at former Lagoon 7. A detailed analysis of the
effects of capping is presented under Alternative SC-2 (Section 6.3.2). The analysis here
will focus on additional considerations associated with application of SVE.
SVE would be applied to former Lagoon 7 for the removal of tetrachloroethene (PCE). PCE
is the only compound in Site soils with the potential to cause ground water to exceed
MCLs. Upon completion of this alternative, there would no longer be a _significant source
of chemicals at the Site to impact ground water.
Construction of an SVE system at the Site would involve the following activities:
-system design based on soil and chemical properties
-connection of subgrade utilities ( 440 volt, 3 phase service)
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-installation of 4-inch PVC slotted well screen down to the water table at
predetermined locations to form the extraction system
-manifolding of the individual screen headers to the vacuum system
-connection of the emissions control system (activated carbon filters), if necessary
-startup, followed by monitoring of the individual headers and combined system to
assess the effectiveness of voe removal and refine operation as necessary.
SVE extraction wells would be installed using standard drilling equipment (e.g., hollow-stem
augers). A filter pack would be placed around the screen and a grout seal would be
placed at the well surface.
The SVE vacuum system would be self-enclosed and designed to operate unattended. A
30-40 HP unit would likely be required for the Site. All wiring would be explosion proof.
Silencers would be placed on the vacuum blower intake and outlet to minimize noise. Any
entrained water would be collected in a knock out drum and either stored for off-site
disposal or sent to the ground water treatment system, if available .
The system would be manned during startup until proper operation of the equipment was
verified and the required subsurface air flow rates were established. voe emissions from
each header and for the total system would be measured to evaluate removal rates and
establish that air emissions were within protective levels. After achieving equilibrium, the
system would be checked monthly for equipment maintenance, air flow rates and voe
emissions. The system would contain an automatic interrupt and telephone dialer in the
event of equipment malfunction.
Based on the VIP modeling (Appendix E), target remediation levels for SVE at the Site
would be 3000 ug/kg PCE in the vadose zone beneath former Lagoon 7. The effectiveness
of SVE in the removal of PCE from Site soils would be evaluated through periodic sampling
of the air emissions. Soil borings might be required to confirm that the tetrachloroethene
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remediation levels had been achieved. To be conservative, confirmation soil borings have
been Included in the FS cost estimate.
. A potential benefit of SVE at the Site would be the removal of SVOCs. SVOC levels at the
Site do not pose a risk to human health or the environment and cannot impact ground
water above remediation levels. Accordingly, SVOCs are not targeted for removal through
SVE. SVE, however, could incidentally remove SVOCs as part of the primary objective of
VOC removal. Removal would be effected through either enhanced biodegradation due to
increased oxygen levels in the subsurface or through direct volatilization, as discussed In
Section 3.4.2. Biodegradable compounds such as phthalates could potentially be
biodegraded while moderately volatile compounds such as naphthalene could be volatilized.
Overall Protection of Human Health and the Environment
The only Site soils with the potential to cause ground water to exceed MCLs are those
containing PCE at Lagoon 7. Chemical transport to ground water represents a potential
incremental risk to human health based on hypothetical consumption of Site ground water
in the future. PCE levels in Site soils would be below calculated remediation levels at the
close of SVE activities and would no longer pose a risk to ground water. Operation of the
SVE system would satisfy North Carolina ambient air requirements. This alternative would
therefore be protective of human health and the environment.
Compliance with ARARs
This alternative, if implemented, would comply with all chemical-specific, action-specific, and
location-specific ARARs. ARARs specific to capping are presented in Alternative SC-2.
After successful implementation and operation of this alternative, all chemical residuals is
subsurface soils would be below calculated remediation levels.
Operation of the SVE system would conform to North Carolina air emission requirements
(15 NCAC 2D.1104). Estimation of potential voe emission rates is not as straightforward
Macon/Dockery FS 6-31 July 5, 1991
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as for an air stripper, since the desorption rates from Site soils are unknown. For purposes
of the FS, it is assumed that vapor phase carbon adsorption would be required to satisfy
air quality standards. Emissions testing would be conducted during startup to establish
actual requirements. The remedial health and safety plan would conform to 29 CFR
1910.120.
Long-term Effectiveness and Permanence
The SVE system would be operated until the remediation level for PCE Is achieved.
Confirmation sampling could be required to verify that the remediation levels had been
achieved before the SVE system was decommissioned. Former Lagoon 7 subsurface soils
would no longer pose potential risks to ground water following completion of this alternative.
No long-term management of subsurface soils would be required following implementation
of this alternative.
Residual chemicals would remain at the Site, even after successful implementation of the
SVE system at Lagoon 7. Residual VOCs that volatilize more readily than PCE, however,
would have substantially lower residual concentrations at the close of remediation since the
duration of SVE operation would be dictated by removal of PCE. Residual chemical levels
after the completion of SVE would not have the potential to impact ground water above
MCLs and no review of remedy would be required for Lagoon 7. A five year review of
remedy would be required for Lagoon 10 since chemical residuals would remain.
Conditions at the Site are anticipated to improve following implementation of this alternative.
Reduction of Toxicity. Mobility or Volume
This alternative would permanently reduce the volume and mobility of Site related chemicals
in Site soils. SVE would permanently reduce the volume of PCE in soils by more than 90
percent, based on a reduction of PCE from 31000 µg/kg to the target remediation level of
3000 µg/kg. This level of reduction would be sufficient to keep former Lagoon 7 subsurface
soils from impacting ground water above remediation levels. PCE is the only compound
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that can impact ground water above MCLs. This alternative would therefore address the
sole risk to ground water posed by Site soils.
Removal of the PCE through SVE would satisfy SARA's preference for remedial actions
lnvoMng treatment as a principal element. Extracted voe levels that would exceed State
ambient air requirements would be adsorbed onto activated carbon. The carbon would
then either be incinerated or regenerated, depending on the volume of carbon available for
reclamation.
Reductions in SVOCs cannot be accurately predicted at this time. Certain compounds are
expected to be removed directly (e.g., naphthalene) while others have the potential to be
removed through oxygen-stimulated biodegradation (e.g., phenols). Even if no reduction
is achieved, SVOCs do not have the potential to impact ground water above remediation
levels.
Capping would reduce the limited mobility and potential future toxicity of residual chemicals
in Lagoon 10 soils.
Short-term Effectiveness
Implementation of the SVE system presents no risks to the community or on-site workers.
Emissions during operation would be controlled to below allowable ambient levels. Because
of the sparsely populated rural setting and setback from the road, it is unlikely that the
community would notice operation of the SVE system.
Installation and start-up of the SVE system would be concurrent with Lagoon 1 o cap
construction. Total implementation time would be approximately four months. The SVE
system would be operated until the soil remediation levels were achieved, a period of
approximately 6 to 12 months based on experience at sites with similar geology and
contaminants.
Macon/Dockery FS 6-33 July 5, 1991
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Implementability
The target remediation level of 3000 µg/kg PCE can be achieved using standard SVE
design and construction practices. Numerous monitoring wells have been Installed at the
Site and installation of the SVE extraction wells should present no difficulties. The SVE
vacuum and control system is designed to run unattended. The only required utilities are
electrical and telecommunication service, both of which are present at the Site.
Control of air emissions would be coordinated with NCDHNER. Disposal of entrained water
to the ground water treatment system, if available, or at an off-site facility should present
no significant difficulties.
SVE is a demonstrated technology using standard process equipment 'that is offered by a
number of vendors. Acquiring responsive and responsible bids to perform this work should
not be difficult .
Implementability of the Lagoon 10 cap is discussed in detail under Alternative SC-2.
Cost
Construction costs for this alternative would include installation and materials for the SVE
extraction wells and manifold piping. Operating costs would include leasing of the SVE
equipment, disposal of spent carbon, and regular monitoring and maintenance. The
detailed cost estimate for this alternative is presented in Appendix F. A summary of the
estimated costs is given below:
Total Construction Costs -
Present Worth O&M Costs -
Total Present Worth Costs -
Macon/Doekery FS
$630,000
$370.000
$1,000.000
6-34 July 5, 1991
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6.3.4 ALTERNATIVE SC-4: Soil Vapor Extraction and Biological Treatment
This alternative involves the operation of a SVE system at former Lagoon 7 and biological
treatment of Lagoon 1 o wastes in a controlled cell. A detailed description of the SVE
system is presented In Section 6.3.3 (Alternative SC-3).
Biological treatment would be applied to Lagoon 10 (Figure 5.1). Lagoon 10 reportedly
contains various organic wastes, including 950 tons of creosote and solidified sludge
collected during EPA's immediate removal action (Sirrine, 1991a). Creosote is a complex
mixture of compounds, primarily polycyclic aromatic hydrocarbons (PAHs) and phenolic
substances. The major PAHs in creosote are 2-, 3-, 4-and 5-ring compounds, including
naphthalene, acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene and
benzo(a)pyrene, all of which were detected in samples collected form Lagoon 10. PAHs
typically exhibit low volatility, low aqueous solubility and adsorb onto soils. The risks to
ground water posed by these compounds is minimal since they are relatively immobile in
soils (VIP Model; Section 3.4.2) and are located at least 21 feet above the water table.
Biodegradation of these compounds has been demonstrated under a variety of
environmental conditions and soil types. Previous studies have reported 80 to 90% removal
of these compounds in less than four months of treatment (Section 4.4.1 ). This technology
is proposed in conjunction with SVE as an innovative alternative by which Lagoon 1 0
wastes may be permanently destroyed. Installation of the SVE system at Lagoon 7 may
proceed concurrently with biological treatment of the Lagoon 1 0 soils.
Implementation of the bioremediation phase of this alternative would be preceded by a
treatability study to determine if the indigenous microbial population is capable of degrading
the PAHs in Lagoon 10. Other objectives of the treatability study would include:
-determine the percentage of endogenous microorganisms capable of degrading
PAHs;
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-determine whether the addition of acclimated microorganisms would be necessary
(bioaugmentation);
-evaluate chemical/physical soil parameters (e.g., pH, moisture content, nutrient
content, dissolved oxygen content, etc.) and identify optimal conditions for
bloremediation; and
-determine biodegradation kinetics and project treatment cycles.
A treatability study work plan would be submitted to EPA for approval prior to
implementation.
Specific remedial objectives would be established with EPA after evaluation of the treatability
study. Treatment levels that could be achieved for the Lagoon 1 o chemical residuals would
be determined. As discussed, these residuals would not have the potential to impact
ground water. Any risks posed by the treatment residuals would be through incidental
human exposure. Risk assessment guidelines would be used to establish protective levels
of human health. Should the final treatment levels be within the risk-based levels, the
treated materials would be replaced directly in the lagoon. If the treatment levels exceed
the risk-based levels, a low permeability cap as described for Alternative SC-2 would be
placed over the treated materials to deny incidental human exposure. Land treatment of
PNAs at other sites in Region IV have established 100 ppm as a treatment level. This level
will serve as a preliminary target for purposes of th~ FS, with actual levels to be determined
during Remedial Design. Final disposal of treatment residuals would be coordinated with
EPA.
RCRA land disposal restrictions (LOR) are potential ARARs if the Lagoon 1 O materials are
determined to be a characteristic or listed hazardous waste. Compounds within Lagoon 10
are not among the characteristic waste compounds of the Toxipity Characteristic Leaching
Procedure (TCLP; 55 FR 11798) that establishes characteristic hazardous wastes. Lagoon
10 materials therefore cannot be a characteristic waste. To be classified as listed
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hazardous waste under RCRA, the following information must be ascertained: The exact
identification of the original waste stream, whether or not the material was off-specification
or past shelf life, and the material must contain a chemical listed in 40 CFR 261.33 as the
sole active ingredient. The information collected thusfar in the RI/FS is insufficient to make
these determinations, and therefore the material in Lagoon 1 O cannot be classified as listed
hazardous waste under RCRA. RCRA LDR are therefore not ARAR for the treatment or
disposal of Lagoon 1 O materials.
Lagoon 10 wastes would be excavated and transferred to a lined waste treatment cell where
bioremediation would be conducted and monitored. The treatment cell would be enclosed
within a greenhouse-type structure that would be serve to maintain optimum microbial
growth conditions and to control any air emissions. Vapor phase carbon adsorption would
be used, as necessary, to control emission concentrations from the greenhouse. For
purposes of the FS, a 100-foot by 100-foot waste treatment cell would be lined with a 60
mil-HOPE liner to provide containment of the wastes. A 6-inch layer of sand and/or gravel
would be placed within the cell to provide a drainage layer for excess moisture. The waste
treatment cell would be built on a slight incline so that excess moisture would gravity drain
to a sump at the low end of the cell. This water would be reapplied to .the wastes during
the next application of nutrients. Fertilizer in the box trailer at the Uppe( Macon site would
be evaluated as a potential source of nutrients. Excess water not recycled would be treated
in the ground water treatment system, if available, or disposed otherwise depending on any
treatment requirements. Applying a 6 to 8 inch layer of lagoon soils above the drainage
layer would accommodate approximately 200 cubic yards. Actual treatment design and
operation would be established during Remedial Design.
A significant reduction in PAH concentrations would be expected within 100 days after
treatment begins based on remediation at other sites. The wastes would be sample for
volatile and semi-volatile analysis just prior to treatment and 100 days into treatment to
determine whether target remediation levels have been achieved. Periodic maintenance
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requirements would include tilling, watering, and fertilization of the wastes. Details of
treatment cell construction and operation would be prepared during Remedial Design.
Treated wastes would be returned to Lagoon ~1 O upon reaching the targeted remediation
level or capped otherwise. For purposes of conservative costing in the FS, treatment
residuals would be covered with a low permeability cap. The existing clay at Lagoon 1 o
would be replaced and recompacted to form the cap. The treatment cells would be
dismanHed and disposed as non-hazardous waste. Actual closure requirements would be
established during Remedial Design.
Overall Protection of Human Health and the Environment
Remediation of Lagoon 10 soils is not necessary for the protection of human health and
the environment. This alternative would be no more protective than Alternative GWC-2
(Section 6.3.2), which controls all Site soils that pose potentially significant risks to human
health.
Compliance with ARARs
There are no ARARs governing subsurface soils at the Site. As discussed, RCRA LDR are
not ARAR for land treatment of Lagoon 1 O materials. Bioremediation operations would
conform to North Carolina air emission requirements, as necessary. Emissions testing
would be conducted during the treatability studies as well as during startup to establish
actual requirements. If required, emissions would be treated to levels acceptable to North
Carolina air quality standards using vapor phase carbon adsorption. The low volatility of
Lagoon 10 chemical residuals and moist conditions of bioremediation indicate that any air
emissions would likely not be significant.
ARARs as they relate to capping and SVE are discussed in Sections 6.3.2 and 6.3.3,
respectively.
Macon/DOckery FS 6-38 July 5, 1991
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Long-Term Effectiveness and Permanence
Waste materials in Lagoon 1 o currently pose no risks to human health and the environment
and there would be no risks following implementation of this alternative. Biodegradation of
the compounds in Lagoon 10 soils has been confirmed at a number of sites and has been
selected for implementation for similar compounds at other sites in Region IV. Effectiveness
of bioremediation for the Lagoon 1 O soils would be established through testing during
Remedial Design. Any chemical residuals following bioremediation could be contained by
a cap and not require further management.
Biological treatment of Site contaminants has previously been conducted on-site by EPA.
Approximately 470,00 gallons of lagoon water was landfarmed at the orchard on the Lower
Macon site during the immediate removal action in 1983. Similar compounds would be
expected to have been present in the lagoon water as are in Lagoon 10. The biological
treatment of Site contaminants by landfarming indicates that successful bioremediation of
residuals in Lagoon 10 would also be anticipated. The specific reductions in chemical
concentrations and duration of treatment cycles would not be known until completion of the
treatability study, however. The need for review of remedy would be established at this
time.
The long-term effectiveness and permanence of this alternative through SVE at former
Lagoon 7 are discussed in Section 6.3.3.
Reduction of Toxicity, Mobility, or Volume
If implemented, this alternative would result in a significant but undetermined reduction in
the volume of Lagoon 10 wastes. Biodegradation of PAHs is a permanent and irreversible
treatment process. PAHs are enzymatically broken down to less complex chemical
intermediates by aerobic microorganisms and are ultimately degraded to CO2 and water.
Bioremediation is documented as being very effective in treating PAHs such as those
detected in Lagoon 10 wastes. PAH concentrations have reportedly been reduced by as
Macon/DOCkery FS 6-39 July 5, 1991
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much as 80% to 90% using microbial biodegradation (Section 4.4.1). Similar success is
anticipated for Lagoon 10 wastes if this alternative is implemented.
The reduction of toxicity, mobility or volume of residual compounds contributed by SVE is
presented in Section 6.3.3.
Short-term Effectiveness
Implementation of this alternative would require excavation and processing of the lagoon
soils, which could potentially pose increased risks to the workers during handling.
Protection of on-site workers would be addressed through adherence to the remedial health
and safety plan. The need for emission control during bioremediation activities would be
considered during Remedial Design and implemented as needed. The need for a cap
would be deferred until Lagoon 10 bioremediation treatability activities are evaluated. Site
access would be controlled during bioremediation activities and implementation would
present no risks to the public .
The time required to complete· bioremediation of Lagoon 1 0 wastes would depend upon
the number of treatment cells, the extent of treatability testing, and the final target
remediation levels. Treatability testing would require 6 to 12 months depending on the rate
of degradation, the level of pilot-scale testing, and the degree of optimization desired.
Implementation of remedial activities would take approximately 18 months based on the
estimated volume of Lagoon 10 waste (1000 cubic yards), the treatment capacity of a single
treatment cell (200 cubic yards), and approximately 100 days to achieve the remediation
target concentrations. Construction of a cap following bioremediation, if required, would
take approximately one month. Total time for implementation of this alternative would be
approximately 25 to 31 months.
Macon/DOCkery FS 6-40 July 5, 1991
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Implementability
Successful bioremedlation of creosote wastes is well documented (Section 4.4.1 ).
Consequently, a significant reduction of Lagoon 10 wastes is anticipated. Materials needed
for the construction of the treatment cells is readily available and easily assembled.
Acquiring responsive and responsible bids to perform this work should not be difficult.
Maintenance of bioremediation operations is relatively simple, consisting mainly of periodic
tilling, fertilizing and watering of the soils. The soils would require periodic sampling for
volatile and semi-volatile organics to determine whether remediation target levels have been
achieved. Adverse climatic conditions would not impact bioremediation efforts since
optimum temperature and moisture control will be maintained within the greenhouse
enclosure. A detailed work plan describing periodic maintenance, operating parameters,
sampling and target remediation levels would be prepared as part of Remedial Design
based on the treatability testing results.
Implementability of potential capping and SVE are discussed in detail under Sections 6.3.2
and 6.3.3, respectively.
Cost
Construction costs for this alternative would include installation of the materials for the
bioremediation treatment cell, SVE extraction wells, manifold piping, and potentially a clay
cap for Lagoon 10 treatment residuals. Operating costs would include leasing of
equipment, periodic tilling and fertilizing, and regular monitoring and maintenance. The
detailed cost estimate for this alternative is presented in Appendix F. A summary of the
estimated costs is given below:
Total Construction Costs -
Present Worth O&M Costs -
Total Present Worth Costs -
Macon/DOCkery FS 6-41
$1,300,000
$200,000
$1,500,000
July 5, 1991
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6.3.5 ALTERNATIVE SC-5: Soil Vapor Extraction and Off-Site Disposal
This alternative Involves the construction and operation of a soil vapor extraction system at
former Lagoon 7 and excavation of Lagoon 1 O wastes for disposal at .a hazardous waste
landfill. Detailed analysis of soil vapor extraction at Lagoon 7 is presented in Alternative SC-
3 (Section 6.3.3). Off-site disposal of Lagoon 10 wastes would significantly reduce the
volume of waste materials and provide a more comprehensive restoration of the Site.
Removal of Lagoon 10 materials is not required for the protection of human health or
ground water.
Toe materials in Lagoon 10 include the original wastes plus materials added during EPA's
immediate removal action in 1983. Additional materials placed in Lagoon 1 0 reportedly
include solidified sludge from Lagoon 7, boiler fly ash (a stabilizing agent), crushed (empty)
drums, and soils from Site drum staging areas. The primary compounds in Lagoon 10 are
polynuclear aromatics (PNAs) and non-chlorinated aromatics (Table 3.10). Lagoon 10 Is
currently covered by approximately three feet of compacted clay and a synthetic liner.
Landfilling of the Lagoon 1 o materials would have to conform to RCRA land disposal
restrictions (LOR; 40 CFR 268) if the materials were determined to be hazardous. Toe
materials in Lagoon 10 come from a number of unknown, disparate sources that cannot
be identified with any certainty. These materials would therefore be classified as soil and
debris potentially containing hazardous waste under the LOR. EPA's Office of Solid and
Hazardous Waste has postponed final standards for soils and debris until May of 1992.
Until then, landfilling of soils and debris would be based on whether the materials were
considered hazardous under TCLP analysis. Should the materials exceed TCLP regulatory
levels, they would be disposed in a hazardous cell at a RCRA-approved facility. Otherwise,
the Lagoon 10 soils could be placed in a non-hazardous cell at the facility.
Macon/DOCkery FS 6-42 July 5, 1991
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Removal of the waste materials would first involve removal of the synthetic liner and the
overlying clay cover. The waste materials would then be excavated to native soils, a depth
of approximately 10 feet. The volume of waste materials is estimated to be approximately
1,000 cubic yards. Excavated soils would be placed into lined roll-off boxes and then
covered with a tarp. Dust control and ambient air monitoring would be conducted to
minimize any air emission impacts. Following removal of all waste materials, the excavation
would be backfilled with native soils and covered with compacted clay remaining from the
cap.
If the Lagoon 1 0 materials are hazardous, they would be manifested per RCRA requirements
and hauled by a registered hazardous waste transporter. Trucks would be washed down
prior to leaving the Site.
For purposes of the FS, Lagoon 10 materials would be landfilled at the Laidlaw facility in
Pinewood, South Carolina. The Laidlaw facility is RC RA-approved and can receive materials
from CERCLA sites. The facility is located approximately 130 miles from ihe Macon/Dockery
Site and has capacity for the approximately 1,000 cubic yards of materials in Lagoon 10.
The actual disposal requirements and RCRA-approved facility would be determined during
Remedial Design.
Overall Protection of Human Health and the Environment
Lagoon 1 o wastes presently do not pose any potentially unacceptable risks to human health
' or the environment. However, the cover on Lagoon 10 is temporary and its design life is
uncertain. If implemented, this alternative would permanently remove the Lagoon 10 wastes
from the Site, hence eliminating any potential for direct human or environmental exposure
to the wastes in the Mure.
Macon/DOCkery FS 6-43 July 5, 1991
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Compliance with ARARs
Landfilling of Lagoon 10 materials would have to comply with EPA's revised off-site policy
(OSWER Dir. 9834.11 ). The Laidlaw facility is in compliance with the requirements of their
RCRA Part B permit. Lagoon 1 0 materials would be transported by a licensed waste hauler
and transportation would comply with State and Federal requirements (49 CFR Parts 171-
173). This alternative would therefore be in compliance with ARARs. Should landfilling not
occur by May of 1992, disposal of the Lagoon 10 materials would have to comply with the
final soil and debris LOR. There are no chemical-specific ARARs for subsurface soils and
no location ARARs for this alternative.
Long-term Effectiveness and Permanence
If implemented, this alternative would effectively and permanently remove all Lagoon 1 O
wastes from the Site. Confirmation sampling of the unearthed soils would be conducted
prior to concluding excavation and removal activities to verify that all waste had been
effectively removed. Potential risks posed by the waste at the Site would be eliminated.
Remaining risks associated with chemical residuals would not be significant. Clay would
be compacted over backfilled native soils in the excavation to reduce any leaching of the
remaining residuals.
Following completion of this alternative, soils at Lagoon 7 would no longer have the
potential to impact ground water above MC Ls and waste materials in lagoon 1 o would be
removed from the Site. There would no be potentially significant source residuals remaining
at the Site and a review of remedy would not be required.
Reduction of Toxicity, Mobility or Volume
The volume of waste at the Site would be greatly reduced under this alternative although
the absolute volume of Lagoon 10 materials would not be reduced. Risks due to remaining
residuals at Lagoon 10 would not be significant.
Macon/DOCkery FS 6-44 July 5, 1991
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Short-term Effectiveness
There would be potential risks of direct human exposure to on-site workers during
excavation activities. Worker safety can be controlled through adherence to the remedial
health and safety plan. Personal protective equipment would be worn by on-site workers
to prevent direct exposure to the waste by inhalation or dermal contact. Dust control and
air monitoring would be exercised to minimize the potential impact of airborne particulates
on the community. Since lagoon 10 is over 1200 feet from State Route 1103, the potential
for excavation to impact the community would be minimal.
Excavation and disposal activities would not begin until all materials and equipment are
available and adequate access had been developed. Implementation time would depend
on the number of crews involved but should be approximately one month. This schedule
assumes standard production rates and compliance with all inspections of performance and
workmanship. Adverse climatic conditions could hinder work efforts and delay the
schedule .
Implementability
Excavation, hauling and landfilling wastes is a straightforward operation that has been
accomplished at numerous waste sites. Clearing of the Site and establishment of access
for heavy equipment, if necessary, should pose no difficulties. Similar operations have been
implemented at other CERCLA sites.
The availability of on-site backfill soil should be adequate. Lead time for procurement of
equipment and transportation is approximately one month and competitive sources should
be available. Actual excavation and landfilling should require approximately one month.
The State of South Carolina has recently attempted to ban the shipment of wastes from
North Carolina to the Laidlaw facility because of North Carolina's inability to create capacity
for the handling of hazardous wastes. Federal court rulings have held that such a ban
MaconJDockery FS 6-45 July 5, 1991
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would violate interstate transport and would be illegal. Landfilling of Site materials at the
Laidlaw facility should therefore be implementable on an institutional basis.
Costs
Construction costs associated with this alternative includes mobilization, excavation, earth
work, materials and labor. Operating costs include reporting and review of the Site remedy
every five years. A sensitivity analysis was conducted based on whether the Lagoon 1 O
materials would be considered hazardous or non-hazardous.
The detailed cost estimate for this alternative is presented in Appendix F. A summary of
the estimated costs Is given below:
Total Construction Costs -
Present Worth O&M Costs -
Total Present Worth Costs -
6.4 VESSELS
Hazardous
$660,000
$110,000
$770,000
CLASSIFICATION
Non-hazardous
$410,000
$110,000
$520,000
There are 8 vats, 2 tankers, and 15 tanks at the Upper Macon site. Characterization of
these vessels was summarized in Section 2.2.6. As discussed in Section 5.4.3, Alternatives
V-1 (no action) and V-2 (off-site disposal) were retained for detailed analysis. Following is
a discussion of alternatives V-1 and V-2 with respect to the evaluation criteria discussed In
Section 6.1.
6.4.1 AllERNATIVE V-1: No action
Vessels would be left in place under this alternative. Periodic inspections would be
conducted to evaluate vessel integrity and surrounding conditions.
Macon/Dockery FS 6-46 July 5, 1991
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Overall Protection of Human Health and the Environment
Chemical residuals within Site vessels are contained and represent an accidental exposure
risk rather than an incidental exposure risk. Vessels were therefore not considered in the
baseline risk assessments. The vessels represent a potential safety hazard, however.
Alternative V-1 would not eliminate potential risks from accidental spills of the vessel
contents or from physical Injury from climbing on the vessels.
Compliance with ARARs
RCRA regulations were identified in Section 3 as potentially relevant and appropriate ARARs
for off-site disposal of vessel contents. This action-specific ARAR for off-site disposal,
however, is not an ARAR under the no action alternative. Consequently, this alternative
would not violate any identified ARARs.
Long-term Effectiveness and Permanence
Since the vessels and their contents would not be addressed under this alternative, any
potential risks would remain. Periodic inspections would be required to evaluate
containment of the vessel residuals. A five-year review of remedy would be required since
waste materials would remain at the Site.
Reduction of Toxicity. Mobility. and Volume
There would be no reduction in toxicity or mobility of the vessel conten~s. The volume of
wastes in the vessels may fluctuate some depending on rainwater influx and evaporation
of oil and water.
Short-term Effectiveness
No action would pose no additional risks to the community or the environment during
implementation. No action can be implemented immediately.
MaconJDockery FS 6-47 July 5, 1991
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Implementability
Consideration of implementability is not applicable since the vessels would not be
addressed.
Cost
There are no construction costs for this alternative. Operating costs would consist of an
annual inspection and review of remedy every five years. The detailed cost estimate for this
alternative is presented in Appendix F.
Total Construction Costs
Present Worth O&M Costs
Total Present Worth Costs
6.4.2 ALTERNATIVE V-2 Off-site disposal
$ 0
$90,000
$90,000
Alternative V-2 would involve transferring all vessel contents into secure transportation
vehicles and dismantling the vessels. Hazardous vessel contents would be taken to a
RCRA-approved facility for disposal. Non-hazardous vessel contents and the vessel pieces
would be recycled or sent to an industrial landfill tor disposal.
Contents of the Site vessels are characterized in Table A.32 and are summarized in Table
6.1. Hazardous solids would be drummed and taken to a RCRA-approved landfill for
disposal while the remaining solids (including tar) would be disposed as non-hazardous
waste. Water would be sent through the ground water treatment system. if available. or
taken to the local Publicly Owned Treatment Works for disposal, pending comparison with
pretreatment requirements. Oil would be pumped into 5,000 gallon tanker trucks for off-
site reclamation or incineration. Ultimate disposition of the oils would be based on the bulk
concentrations in the tanker that would be sent to the receiving facility.
MaconJ[)ockery FS 6-48 July 5, 1991
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Fertilizer in the box trailer and the boiler insulation would be disposed of as non-hazardous
waste or recycled. Boiler insulation has not been characterized but, bas,ed on the assumed
age of construction, may contain asbestos. Characterization of the insulation would be
required prior to dismantling the boiler. To be conservative, it is assu_med in the FS that
disposal of boiler insulation would have to comply with asbestos handling requirements.
Overall Protection of Human Health and the Environment
Potential risks from the vessels would be accidental and were not addressed in the baseline
risk assessments. Alternative V-2 would eliminate potential risks from accidental spills of
the vessel contents or from physical injury from climbing on the vessels.
Compliance with ARARs
RCRA regulations were identified in Section 3 as potentially relevant and appropriate ARARs
for vessel remediation. RCRA disposal guidance was identified as an action-specific ARAR
while RCRA hazard characteristics were identified as a chemical-specific ARAR (i.e., TCLP).
Alternative V-2 would follow appropriate RCRA requirements and would therefore comply
with these potential ARARs.
It is not known if the industrial boiler (Building 2, Figure 2.1) contains friable asbestos. If . '
this boiler does contain asbestos, two potential action-specific ARARs may apply for off-
site disposal: (1) 29 CFR parts 1910.1001 and 1926.58 (general asbestos regulations under
the Occupational Safety and Health Administration (OSHA) and construction/demolition
regulations, respectively) and (2) North Carolina Specifications for Asbestos Abatement
(Division of State Construction, Department of Administration, as amended in February
1988). Most of these regulations pertain to the packing and shipping of asbestos-containing
materials such that the amount of asbestos fibers entering the air and affecting potential
human exposure are minimized. Alternative V-2 would follow the OSHA and North Carolina
requirements and therefore would comply with these potential ARARs.
MaconJ[)ockery FS 6-49 July 5, 1991
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Long-term Effectiveness and Permanence
Since the vessels and their contents would be taken off-site and recycled or disposed {with
the possible exception of the tankers), there would be no residual risk following
implementation of Alternative V-2. Since the tankers contain solids or tar that are not
hazardous according to RCRA toxicity characteristics, and would be difficult to clean
because of the tar and solids residues, off-Site burial at an industrial landfill {non-hazardous)
would be feasible.
Reduction of Toxicity. Mobility, and Volume
The volume and toxicity of materials at the Site would be permanently reduced under this
alternative. Incineration {hazardous materials) or recycling (non-hazardous) would effect a
permanent reduction in the absolute volume of vessel contents.
Short-term Effectiveness
Vessel removal Is estimated to take 2 months. Short term risks involved in this alternative
would be from cutting to dismantle the vessels and in moving the Site vessels. Other risks
could result from the removal of the solids from Vat 4 because of the dust that could be
generated, and from removal of the boiler if it is found to contain friable asbestos.
However, the low amount of lead and the small volume of solids in Vat 4 would minimize
any effects from the dust. Dust control and ambient air monitoring would be conducted to
minimize potential risks to the community. Potential worker exposure would be reduced by
using the appropriate personal protective equipment, as directed by the remedial health and
safety plan.
Implementability
Cleaning and removal of waste storage tanks has been successfully accomplished at
numerous hazardous waste sites and there are no special requirements at this Site that
would lead to implementation concerns. There are a number of qualified companies that
specialize in this type of remedial work. Transferring the vessel contents and dismantling
the vessels would be readily implemented .
Macon/Dockery FS 6-50 July 5, 1991
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Land disposal of the hazardous solids in Vat 4 could be complicated since North Carolina
does not have a hazardous waste landfill and Alabama and South Carolina, who do, may
not continue to accept hazardous wastes from North Carolina. However, recent court
rulings have held that barring waste from North Carolina is an obstruction of interstate
commerce and therefore illegal.
ff found to contain asbestos, the boiler would most likely be disposed in an industrial waste
cell at a municipal landfill. Asbestos is not considered a hazardous waste.
Cost
Costs associated with Alternative V-2 would be direct and indirect construction costs. There
would be no operational costs. Cost assumptions and estimated costs are provided in
Appendix F.
Total Construction Costs -
Present Worth O&M Costs -
Total Present Worth Costs -
Macon/Dockery FS 6-51
$300,000
$ 0
$300,000
July 5, 1991
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PHASE
Solids
Water
Oil
Tar
Table 6.1
SUMMARY OF VESSEL CONTENTS
VOLUME (Gallons)
HAZARDOUS* NON-HAZARDOUS TOTAL
100
0
600
0
500
13,500
8,900
900
600
13,500
9,500
900
* Characterization as a hazardous waste is based on TCLP analysis. Lead was the only
constituent to exceed the TCLP regulatory level, in Vat 4, Tank 3 and Tank 4 (Table 3.10).
Macon/DOCkery FS 6-53 July 5, 1991
--.-
Extraction
Wells
...
-- -
.
Concentration
Equalization
---
.
Air
Stripper
I --- - - ----
ESTIMATED FLOW RA TES
Macon Site
Dockery Site
Monitoring
l],____.c = J
Coagulation/
Filtration
28 gpm
12 gpm
Discharge to
Solomons Creek
or Infiltration
Gallery
Note: For purposes of the Feasibility Study, separate treatment facilities would be constructed for the Macon and
Dockery sites. Actual treatment requirements would be determined during_Remedial Design. The actual
method of metals removed (if necessary) and discharge of treated groundwater would be determined
during Remedial Design.
Figure 6.1
Groundwater Treatment
Flow Diagram
Alternative GWC-2A
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7.0 SUMMARY
A feasibility study (FS) was conducted for the Macon/Dockery CERCLA Site in Richmond
County, North Carolina. This FS was prepared in accordance with CERCLA, as
promulgated by the NCP. The primary objective of the FS is to develop remedial
alternatives for the Site. Remedial alternatives were developed based on considerations of
the RI data (Sirrine, 1991a), the Risk Assessment (Sirrine, 1991b), and examination of
Applicable or Relevant and Appropriate Requirements (ARARs), review of potential
technologies, and NCP screening criteria.
The RI was conducted from 1989 to 1991 by Sirrine Environmental Con~ultants. Significant
findings of the RI include:
• Site waste management activities occurred from 1979 to 1982
• Initial Site clean-up activities included those of the EPA in 1983
• EPA clean-up activities resulted in the removal or remedia\ion of a significant
portion of the Site waste, thus greatly reducing any impact on human health or
the environment
• Ground water contaminants primarily consist of trace amounts of volatile organic
compounds in localized areas of the Site's uppermost aquifer
• Slightly elevated concentrations of inorganic constituents (e.g., metals) have
been found in Site ground water; these inorganic constituents are probably not
representative of the ground water but are most likely naturally-occurring artifacts
from suspended sediment in the samples
• Low concentrations of residual volatile organic compounds and inorganic
compounds remain in vadose zone soil; however, only the volatiles under
Lagoon 7 have the potential to impact ground water
• Polyaromatic hydrocarbons (PAHs in Lagoon 10, although not expected to
adversely impact Site ground water, and pose a future risk from direct exposure
to the PAH residuals
Macon/Dockery FS 7-1 July 5, 1991
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• Site surface soil, sediment, and surface water have not been adversely impacted
by previous Site activities
• There are several vessels on Site, including above-ground tanks, tankers, and
vats; about half of the vessels are empty while the remainder contain mixtures
of water, oil, tar, and solids
Remedial response objectives were developed based on results of the Risk Assessment and
an examination of potential ARARs. Action-, location-, and chemical-specific ARARs were
examined. Action-and location-specific ARARs were examined and listed; consideration for
use as an ARAR is dependent on the remedial alternatives that are screened and retained.
Chemical-specific ARARs for ground water include MCLs, and North Carolina Ground Water
Standards.
No chemical-specific ARARs were found for vadose zone soil. Vadose zone modeling (VIP
model) was done to determine impacts (if any) from chemical residuals in the vadose zone
on Site ground water. PCE under Lagoon 7 was estimated to adversely impact ground
water. In spite of the conservative assumptions used in VIP modeling, other residuals in
the vadose zone are not predicted to adversely impact Site ground water.
Areas of potential remediation include the Site ground water (volatiles and inorganics),
vadose zone soil at Lagoon 7 (volatiles) and Lagoon 10 (PAHs), and the contents of Site
vessels (water, oil, tar, and solids).
Ground water recovery, if required, would be best achieved through extraction wells.
Capture zone efficiency would be evaluated through aquifer response measurements
conducted during construction of the extraction system.
The volumes of materials removed during the immediate removal action and the generally
low levels of chemical residuals found during the RI indicate that the great majority of waste
Macon/Dockery FS 7-2 July 5, 1991
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materials disposed of at the Site have been removed. Unsaturated transport modeling
determined the voes in former Lagoon 7 are the only contaminants in Site soils with the
potential to impact ground water above remediation levels.
7.1 GROUND WATER CONTROL
Site ground water currently poses no risks to human health or the environment. Potential
risks to human health could occur in the Mure should a potable well be installed on the
Site. The limited projected growth in the area, especially downgradient of the Site, and the
extent of the existing municipal water supply indicate that construction of such a well is
unlikely. Ground water migration in the Mure, even without treatment, would not pose a
risk to the environment based on comparison with Federal Ambient Water Quality standards.
The following alternatives were subjected to detailed analysis for migration control:
• Alternative GWC-1A: No Action
• Alternative GWC-1 B:
• Alternative GWC-2A:
Long-term monitoring of ground water
MCL.s at Site, air stripping, coagulation/filtration
The projected locations for ground water extraction systems for the Macon and Dockery
sites are presented in Figures C.1 and C.2. A summary of the evaluation of these
alternatives under the detailed analysis criteria is presented below.
Overall Protection of Human Health and the Environment
The no action alternative would be protective of human health and the environment under
current conditions. In the Mure, ground water migration will not pose a risk to the
environment, but could pose a risk to human health if a potable well were to be installed
at the Site. Currently there are no ground water receptors at the Site or immediately
downgradient of the property, and Mure receptors are unlikely. Consequently, the risk
estimate for the Site is an estimate of potential future risk of human health. The risk
Macon/Dockery FS 7-3 July 5, 1991
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assessments determined that Site ground water posed a maximum carcinogenic risk of 6.55 x 10-3 at the Upper Macon site under a future use (residential) ~cenario. This level exceeds the acceptable range of 10-4 to 10-6 specified by the NCP.
Alternative GWC-2A would be protective of human health and the environment, now and in the Mure, since this treatment alternative would result in MCLs being achieved at all times at potential exposure points.
Compliance with ARARs
Concentrations of VOCs in ground water located beneath the Site exceed MCLs, consequently the no action alternatives (GWC-1A and GWC-18) would not satisfy ARARs across the Site without a waiver. Ground water extraction alternative GWC-2A would satisfy ground water ARARS. Construction of the ground water extraction, treatment, and discharge system for Alternative GWC-2A would satisfy action-specific ARARs.
Long-term Effectiveness and permanence
The magnitude of residual risks would remain unchanged under the no action alternatives (GWC-1A and GWC-18). Since contaminants would remain at the Site, a review of remedy would be required every five years.
Alternative GWC-2A would permanently reduce the magnitude of potential risks at the Site through Mure exposure to ground water. Well point extraction of ground water and air stripping are demonstrated technologies that can be readily inspected and repaired, if necessary. Air stripping can readily achieve the concentrations necessary for discharge to Solomons Creek. Periodic sampling of the treated effluent would be-required. Since ground water remaining at the Site after remediation would attain all protective standards, a review of remedy every five years would not be required at the completion of Alternative GWC-2A .
Macon/Dockery FS 7-4 July 5, 1991
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Reduction of Toxicity. Mobility or Volume
The no action alternative would not significantly reduce the toxicity, mobility or volume of
contaminants in ground water. Alternative GWC-2A would permanently reduce the mass
of voes in ground water by more than 98 percent.
Short-term Effectiveness
None of the alternatives would pose a risk to the community or remedial workers through
implementation. Construction schedules for the alternatives would be:
• Alternative GWC-1A: None
•
•
Alternative GWC-1 B:
Alternative GWC-2A:
1 month
4 months
Based on a batch-flushing model, implementation of Alternative GWC-2A would require
approximately 17 years.
Implementability
None of the alternatives would pose any significant difficulties regarding construction or
operation. Design of any treatment system could not be completed until discharge
requirements were defined.
Cost
Total present worth costs for the ground water control alternatives are presented in Table
7.1.
7.2 SOURCE CONTROL
Site soils pose no significant risks to human health or the environment under current or
Mure conditions. Potential risks are only associated with ground water that has been
impacted by the leaching of contaminants from certain areas of soils. Source control
Macon/Dockery FS 7-5 July 5, 1991
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alternatives address those soils that could contribute contaminant levels to ground water
above MCL.s. Soil remediation levels based on leaching potential were derived in Appendix
E. Site soils exceeding these levels are limited to former Lagoon 7. PCE is the only
compound found in soils that could cause ground water to exceed ARARs. Source control
alternatives were also developed for the waste residuals in Lagoon 10, although these
materials do not represent a risk to human health or ground water. The following
alternatives were developed for Site soils and were subjected to detailed analysis:
• Alternative SC-1: No action
• Alternative SC-2: Cap former Lagoon 7 and Lagoon 1 O
• Alternative SC-3:
• Alternative SC-4:
• Alternative SC-5:
Soil vapor extraction (SVE) for Lagoon 7, cap
Lagoon 10
SVE for Lagoon 7, bioremediation for Lagoon 10
SVE for Lagoon 7, off-site disposal for Lagoon 10
A summary of the evaluation of these alternatives under the detailed analysis criteria is
presented below .
Overall Protection of Human Health and the Environment
Each of the source control alternatives would be protective of human health and the
environment. Capping (Alternative SC-2) and SVE (Alternatives SC-3, 4, and 5) would
reduce chemical loadings to ground water from Lagoon 7 and thereby lessen any risks to
potential downgradient receptors in the future. Remediation of Lagoon 10 is not required
for protection of human health or the environment.
Compliance with ARARs
The only identified ARAR for Site surficial soils are the proposed RCRA corrective action
levels. The only surficial soil compound posing potential risks is arsenic, whose maximum
concentration was significantly less than the RCRA action level. Concentrations at the Site,
and therefore each of the source control alternatives, satisfy the RCRA action level.
Macon/Dockery FS 7-6 July 5, 1991
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Soils at Lagoon 7 have the potential to cause VOCs in ground water to exceed MCLs.
Capping and SVE would significantly reduce further leaching of contaminants to ground
water from Lagoon 7. The cap in Alternatives SC-2 and 3 would be designed to comply
with RCRA performance standards. The SVE system in Alternatives SC-3, 4, and 5 would
be operated in accordance with North Carolina air emission requirements. Off-site disposal
(e.g., landfilling) of soils would comply with EPA's off-site policy and land disposal
restrictions (Alternative SC-5).
Long-term Effectiveness and Permanence
PCE is the only compound found in Site soils with the potential to impact ground water
above MCLs. The migration of PCE to ground water from Lagoon 7 would be permanently
controlled by capping and SVE. A five year review of remedy would be required for
Alternatives SC-1 through SC-3 because chemical residuals would be left at the Site. The
net reduction is chemical residuals through bioremediation (Alternative SC-4) is uncertain
at this time and the need for review of remedy will not be known until results of the
treatability study are evaluated. No review would be required following completion of
Alternative SC-5 since there would be no significant concentrations of chemical residuals
remaining at the Site.
Reduction of Toxicity. Mobility or Volume
The no action alternative would not significantly reduce the toxicity, mobility or volume of
remaining Site residuals. Capping would significantly reduce the mobility of Site residuals.
SVE would significantly reduce the volume of Site residuals that could impact ground water
above MCLs (more than 90 percent based on PCE removal in former Lagoon 7).
Bioremediation would effect a permanent but undetermined reduction ;in the volume of
chemical residuals in Lagoon 10. The volume of chemical residuals at the Site would be
significantly reduced through off-site landfilling of Lagoon 1 O waste materials.
Macon/Dockery FS 7-7 July 5, 1991
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Short-term Effectiveness
None of the alternatives would pose a risk to the community or remedial workers through
implementation. Construction and operation schedules for the alternatives would be:
• Alternative SC-1: O months
• Alternative SC-2:
• Alternative SC-3:
• Alternative SC-4:
• Alternative SC-5:
Implementability
3 months
6-12 months
25-31 months
2 months
None of the alternative would pose any significant construction nor operational difficulties,
although periodic inspections and repair of the cap(s) would be required. Actual
implementation requirements for bioremediation would be established through treatability
testing .
Cost
Total present worth costs for the source control alternatives are presented in Table 7.1.
7.3 VESSELS
Two alternatives were considered for Site vessels:
• V-1: No action
• V-2: Off-site disposal
Site vessels pose no incidental risks to human health or the environment. Disposal of the
vessel contents would comply with RCRA requirements as appropriate and would be readily
implementable. Present worth costs for the alternatives are presented in Table 7.1.
Macon/Dockery FS 7-8 July 5, 1991
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Ground Water Control
GWC-1A
GWC-1B
GWC-2A
Source Control
SC-1
SC-2
SC-3
SC-4
SC-5
Vessels
V-1
V-2
Macon/Dockery FS
TABLE 7.1
TOTAL PRESENT WORTH COSTS FOR
RETAINED REMEDIAL ALTERNATIVES
MACON/DOCKERY SITE
Corrective Action
No action
Long-term monitoring
of ground water
Ground water extraction
for MCLs across Site, air
stripping, coagulation/
filtration
No action
Cap former Lagoon 7 and
Lagoon 10
Soil vapor extraction for
former Lagoon 7, cap
Lagoon 10
Soil vapor extraction for
former Lagoon 7, bioremediate
Lagoon 10
Soil vapor extraction for
former Lagoon 7, off-site
landfilling for Lagoon 1 O
No action
Off-site disposal
Total Present
Worth Costs
$140,000
$1,800,000
$6,900,000 (30 year duration)
$5,500,000 (17 year duration)
$190,000
$690,000
$1,100,000
$1,500,000
$770,000 (hazardous)
$520,000 (non-hazardous)
$90,000
$300,000
July 5, 1991
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REFERENCES
Alther, G.R., J.C. Evans, et al., 1988 'Organically Modified Clays for Stabilization of Organic
Wastes,• Superfund '88: Proceedings of the 9th National Conference, Toe Hazardous
Materials Control Research Institute, 9300 Columbia Blvd., Silver Spring, MD 20910.
AWOC, 1986. Quality Criteria for Water, EPA 44-/5-86-001, May 1986 (51 FR 43665).
Bergren, C.L., M.A. Flora, J.L Jackson, and _E.M. Hicks, 1991, Application of Inorganic -
Contaminated Ground Water to Surface Soils and Compliance with Toxicity
Characteristic ITCLP} Regulations, Westinghouse Savannah River Company, Aiken,
SC (in preparation).
Bioremediation of Contaminated Surface Soils, USEPA, EPN600/9-89/073 August 1989.
Chemical Waste Management, Personal Communication, 2 July, 1991 Mr. Rick Chap, Oak
Brook, IL
Chemical Waste Management, Personal Communication, 13 June, 1991 Mr Rick Chap, Oak
Brook, IL
Clapp and Hornberger, 1978. R.B. Clapp and G. Hornberger. Empirical equations for some
soil hydraulic properties. Water Resour. Res. 14:601-604.
Dragun; J., 1988. Toe Soil Chemistry of Hazardous Materials, Hazardous Materials Control
Research Institute, Silver Spring, Maryland, 458 p.
Ehntholt, D.J., "Isolation and Concentration of Organic Substances from Water -An
Evaluation of Supercritical Fluid Extraction," EPA Project Summary, EPA-600/51-84-
028, January 1985.
EPA, 1986a, Guidance for Air Quality Models, EPN450/2-78-027R, Washington, DC, July
1986. .
EPA, 1986b, Handbook for Stabilization/Solidification of Hazardous Waste, USEPA,
Hazardous Waste Engineering Research Laboratory, Cincinnati, OH 45268; EPN540/2-
86/001, June 1986.
EPA, 1986c, Wright, B.W. and R.D. Smith, "Supercritical Fluid Extraction o.f Particulate and
Adsorbent Materials," EPA Project Summary EPNG00/54-86/017, June 1986.
EPA. 1987, Data Requirements for Selecting Remedial Action Technologies, EPNG00/2-
87/001, Washington, DC, January 1987.
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EPA, 1988a, Guidance for Conducting Remedial Investigations and Feasibility Studies Under
CERCLA, EPN540/G-89/004, Washington, DC, October 1988.
EPA, 1988b, Guidance on Remedial Actions for Groundwater at Superfund Sites,
EPA/540/G-88/003, Washington, DC, December 1988.
EPA, 1988c, Technology Screening Guide for Treatment of CERCLA Soils and Sludges,
USEPA, EPN540/2-88/004, September 1988, p 63.
EPA, 1988d. CERCLA Compliance with other Laws Manual. OWSER Directive 9234.1-01,
August 8, 1988.
EPA, 1988e. Contract Laboratory Program Statement of Work for Organic Analysis: Multi-
media. Office of Emergency and Remedial Response. SOW No. 288.
EPA, 1988f. Laboratory Data Validation Functional Guidelines for Evaluating Organic
Analysis. Office of Emergency and Remedial Response.
EPA, 1989a. Risk Assessment Guidance for Superfund -Volume 1 -Human Health
Evaluation Manual (Part A), Interim Final, EPA/540/1-89/002, December 1989.
EPA, 1989b. U.S. EPA Evaluation of Groundwater Extraction Remedies. Office Solid Waste
and Emergency Response; EPN504/0289/054; Washington, DC, 1989 .
EPA, 1989c. 'Consideration in Ground Water Remediation at Superfund Sites.'
Memorandum for Jonathan Cannon to EPA Regional Offices, Directive No. 9355.4-
03, Office of Solid Waste and Emergency Response 1989a.
EPA, 1989d. Ground Water Issue. Performance Evaluations of Pump-and-Treat
Remediations. Office of Research and Development.
EPA, 1990, Cost of Remedial Action (CORA) Version 3.0, Washington, DC.
EPA, 1990a. Evaluation of Ground Water Extraction Remedies, v. 2, Case Studies,
EPN540/2-89/054.
EPA, 1990b. Evaluation of Ground Water Extraction Remedies, v. 3, General Data Survey
Reports, EPN540/2-89/054.
EPA, 1990c. U.S. Environmental Protection Agency. Exposure Factors Handbook. Office
of Health and Environmental Assessment, U.S. EPA, Washington D.C.
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EPA, 1990d. U.S. Environmental Protection Agency. Health Effects Assessment Summary
· Tables. Third Quarter FY-1990. Office of Health and Environmental Assessment.
Environmental Criteria and Assessment Office, U.S. EPA, Cincinnati, Ohio.
EPA, _1991a. U.S. Environmental Protection Agency. Integrated Risk Information System
{IRIS; Online Database). Office of Health and Environmental Assessment,
Environmental Criteria and Assessment Office, U.S. EPA, Cincinnati, Ohio.
EPA, 1991b. EPA Alternative Treatment Technology Information database. Washington,
D.C.
Freeze, KA., and Cherry, J.A., 1979. Groundwater. Prentice-Hall, Inc., Englewood Cliffs.
New Jersey, 604 p.
Haley, J.L, et al, 1991, Evaluating the Effectiveness of Ground Water Extraction Systems,
Ground Water Monitoring Review, Winter 1991, pp. 119-124.
Hall, 1991. Hall, C.W., "Limiting Factors in Ground Water Remediation•, 20th Annual
Conference on Environmental Law, March 1991, Keystone, Co. [NOTE: C.W. Hall is
Director of EPA's Robert S. Kerr Environmental Research Laboratory.]
Hawley, J.K 1985. "Assessment of Health Risk from Exposure to Contaminated Soil." Risk
Analysis 5 (4): 289-302 .
Hutchinson, T.C. and KM. Meema, 1987. Lead. Mercury. Cadmium and Arsenic in the
Environment, Scope 31, John Wiley & Sons, Inc. New York.
Lindsay, W.L 1979. Chemical Equilibria in Soils, John Wiley & Sons, Inc., New York.
Looney et al., 1987. B.B. Looney, M.W. Grant, and C.M. King. "Estimation of Geochemical
Parameters for Assessing Subsurface Transport at the Savannah River Site.•
Savannah River Laboratory, Aiken, SC, DPST-85-904, March 1987.
Merck, 1989, The Merck Index. Eleventh Edition, Merck & Co., Inc., Rahway, NJ.
Montgomery and Weikom, 1990. John H. Montgomery and Linda M. Welkom, Groundwater
Chemicals Desk Reference, Lewis Publishers, Chelsea, Michigan.
Pickett, J.B., 1985 Technical Data Summary. Extended Characterization of the M-Area
Settling Basin and Vicinity. DPSTD-85-121, (Rev. 10/85), E.I. du Pont de Nemours and
Company, Savannah River Laboratory, Aiken, SC.
Rosenblatt, et al., 1986. Rosenblatt, D.H., W.R. Hartley, and E.Y. Williams, Jr. "The
preliminary pollutant limit value concept." Military Medicine 151: 645-647.
Macon/Dockery FS REF-3 July 5, 1991
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SDWA, 1986, Safe Drinking Water Act, 42 USC § 300f, et seq., as amended In 1976, 1977,
1979, 1980, 1984, and 1986, U.S. Congress, Washington, DC.
Shacklette, H.T., and J.G. Boerngen, 1984. Element Concentrations In Solis and Other
Materials of the Conterminous United States, U.S. Geological Survey Professional
Paper 1270, United States Government Printing Office, Washington, DC.
Sirrine, 1991a, Sirrine Environmental Consultants, Remedial Investigation (RI) Report for the
Macon/Dockery Site In Richmond County. North Carolina, Greenville, SC, March 1991
(Final Report).
Sirrine. 1991 b, Sirrine Environmental Consultants, Risk Assessment for the Macon/Dockery
Site in Richmond County. North Carolina, Greenville, SC.
•soil Washing -The European Experience•, The Hazardous Waste Consultant, Vol. 7, Issue
3, May/June 1989.
"Soil Washing -The European Experience•, The Hazardous Waste Consultant, Vol. 9, Issue
2, March/ April 1991.
Stevens, D.K., W.J. Grennay, and A. Yan, 1991, Vadose Zone Interactive Model (VIP),
Version 3.0, Utah State University, Logan, Utah.
Travis, C.C. and C.B. Doty, 1990, Can Contaminated Aquifers at Superfund Sites Be
Remediated?, Environmental Science and Technology, Vol. 24, No. 10, 1990, pp.
1464-1466.
Travis, C.C., S.A Richter, E.A.C. Crouch, R. Wilson and E.D. Klema. 1987 August. "Risk
and regulation.' Chemtech: 478-483.
Veith, G.D., K.J. Macek, S.R. Petrocelli and J. Carroll." An Evaluation of using partition
coefficients of water solubility to estimate bioconcentration factors for organic
chemicals in Fish, J. Fish Res. Board Can. 1980. (prepublication copy)." As cited in:
Handbook of Chemical Property Estimation Methods: Environmental Behavior of
Organic Compounds, W.J. Lyman, W.F. Reehl, D.H. Rosenblatt, MacGraw-Hill, New
York, 1982.
Walton, W.C., 1989. Analytical Ground-Water Flow Modeling, Lewis Publishers, Chelsea,
Michigan, 173 p.
Wright, B.W. and R.D. Smith, "Supercritical Fluid Extraction of Particulate and Adsorbent
Materials,' EPA Project Summary EPN600/54-86/017, June 1986 ..
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I APPENDIX C .. GROUND-WATER MODELING
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INTRODUCTION TO GROUND-WATER MODELING
Ground-water flow modeling and chemical transport modeling were conducted during the
Feasibility Study for the Macon/Dockery Site. The modeling was conducted in three phases
to: (1) calculate the areal extent of residual chemical plumes for various chemicals at
various time intervals; (2) simulate migration of residual chemical plumes to surface-water
discharge areas and calculate the maximum concentrations of various chemicals at the
discharge areas; and (3) develop conceptual designs for extraction of contaminated ground
water. Two analytical models were used: CONMIG and WELFLO. CONMIG (Walton, 1989)
is an analytical contaminant transport model which was used to evaluat? residual chemical
migration at the Site. WELFLO (Walton, 1989) is an analytical ground-water flow model
which was used to develop the conceptual placement of potential extraction wells. Site-
specific physical and chemical data collected during the RI were used as input to both
models.
Modeling Methods and Results
A discussion of CONMIG, its assumptions, applications and limitations, can be found in
Section 6.3.2 of the RI (Sirrine, 1991a). CONMIG requires data pertaining to aquifer
characteristics, residual chemical properties and residual chemical source concentrations
as input. Table C.1 provides the values which were selected as appropriate· for the
Macon/Dockery Site. Discussion of the values may be found in Section 6.3.2 of the RI
(Sirrine, 1991a).
Values of Kd for inorganic constituents available in the literature have a broad range (as
much as five orders of magnitude) due to variations in soil type. Values of Kd measured
in soil similar to that found at the Macon/Dockery Site were necessary to accurately
estimate contaminant movement. Because of the similarity between the Macon/Dockery Site
soil series and the Savannah River Site soil series (e.g. Orangeburg series), Kd values
measured for soil series at the Savannah River Site (Westinghouse Savannah River
Company, 1990) were considered the best available data and were used in contaminant-
Macon/Dockery FS C-1 July 5, 1991
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transport modeling in both the saturated and unsaturated zones. These Kd values are
consistent with those used in vadose-zone modeling in Appendix E. Due to the limited
number of available Kd values for inorganic constituents, modeling was limited to those
inorganics with available Kd values. In addition to the parameters discussed on Table C.1,
CONMIG also requires input of the source-area concentrations of the residual chemicals
being modeled and the contaminant injection rate.
Contaminant injection rates presented in the RI (Sirrine, 1991a; 112 gpd/node at the Macon
Site and 80 gpd/node at the Dockery Site) were also used for the ground-water modeling
in the FS. Source-area concentrations were calculated during the first phase of FS
modeling. Residual chemical migration was simulated for the following organic chemicals,
which were found in concentrations exceeding Maximum Contaminant Levels (MCLs) in
certain ground-water samples: trichloroethane; 1,2-dichloroethene (total); 1, 1-
dichloroethene; 1, 1, 1-trichloroethane; tetrachloroethene; and vinyl chloride. Residual
chemical migration was simulated for the following inorganic chemicals which were
determined to potentially pose an unacceptable risk to potential future users of Site ground
water, and for which AWQC and Kd values are available: cadmium, chromium and nickel.
Other inorganic chemicals found to potentially pose an unacceptable risk to potential future
users of Site ground water (barium and beryllium) could not be modeled because necessary
Kd values were not available. Following is a discussion of modeling procedures.
Phase I Modeling: Source Concentrations and Estimated Areal Extent of Contamination
The first phase of modeling determined concentrations of chemicals that were present at
the source areas (lagoons and drum storage areas) to produce the current distribution of
ground-water contaminants, and estimate the current extent of residual plumes for the
organic chemicals. Chemical transport calculations were made for two time periods, five
years and ten years, bracketing the approximate time elapsed since operation of residual
chemical source areas began and ended. Residual chemical migration through ground
water would not have begun at precisely the same time as operation of the source areas
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did in 1979; time would be required for residual chemicals to first be transported through
the vadose zone. Therefore, ten years is considered to be a reasonable maximum time
period during which residual chemical migration may have occurred. Five years is
considered to be a minimum time period during which residual chemical migration is
expected to have occurred. The concentration distributions calculated using the ten-year
time period were used in designing the conceptual extraction system (Phase Ill Modeling)
as a maximum conservative estimate.
Source-area concentrations were calculated by initially setting the source-area concentration
equal to maximum ground-water concentrations observed at the Site, and then varying the
input concentration until simulated contaminant concentrations matched measured
contaminant concentrations in down-gradient monitoring wells. Calculated source-area
concentrations were used to model the 5-year (minimum) and 10-year (maximum) extent of
constituent migration (Figures C.1 and C.2). Table C.2 presents the estimated maximum
areal extent of constituents exceeding MCLs.
Phase II Modeling: Migration of Ground-Water Contamination to Surface Water
To evaluate the No-Action remediation alternative, a second phase of modeling was
conducted to determine the maximum concentrations of contaminants which would be
found at surface-water discharge areas if the residual ch_emical plume were to migrate to
the point of discharge. Plume migration generally is in a westerly direction from the source
areas towards. Solomon's Creek and to the Pee Dee River (Section 6.1 of the RI; Sirrine,
1991a).
Source-area loading in this phase of modeling was simulated as a slug or non-continuous
point source injecting each contaminant for a period of ten years. Ten years is considered
to be the maximum reasonable period during which the majority of contaminant loading to
the aquifer occurred, as discussed previously. Source-area contaminant concentrations, as
calculated in Phase I Modeling, as well as the parameters listed in Table C.1, were used
as input
Macon/Dockery FS C-3 July 5, 1991
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Plume migration was simulated for each chemical to the point when the maximum
concentration of the contaminant slug reached Solomon's Creek. Calculated ground-water
chemical concentrations were reduced by mathematically mixing the ground-water and
surface-water volumes, assuming instantaneous mixing of ground water and surface water.
A dilution factor of 9.6 x 1 o-2 was calculated for mixing of the ground water with surface
water based on a calculated volume of water available for mixing in Solomon's Creek
(assuming that one-tenth of the standing water in the creek is available for mixing) and
specific discharge of the ground water into Solomon's Creek. Surface water in Solomon's
Creek prior to mixing is assumed to be pristine for modeling purposes. Surface water
samples collected in 1989 (Section 3.1.3 of the RI, Sirrine, 1991 a) indicate that surface water
flowing to the Macon/Dockery Site is below detection limits in concentrations of
tetrachloroethene, 1, 1, 1-trichlorethane, trichloroethene, vinyl chloride, cadmium, chromium
and nickel and, therefore, can be considered pristine with respect to these contaminants.
The resultant values (Table C.3) represent the diluted contaminant concentrations. Diluted
concentrations were calculated for those contaminants for which AWQC are available .
Phase Ill Modeling: Extraction System Design
A conceptual design for the extraction system at each Site was developed based on the
Phase I modeling described above. The analytical ground-water flow model, WELFLO
(Walton, 1989), was used to establish the arrangement of wells and the pumping rates
necessary to create the proper ground-water capture zone. WELFLO assumes that delayed
gravity yield is negligible, well discharge rates are constant and the aquifer is isotropic and
homogeneous. These assumptions may limit the use of WELFLO, but at this stage of
evaluation the model is applicable. To model the Macon/Dockery Site with fewer
assumptions, therefore making the model more specific, a numerical approach would be
necessary. Numerical ground-water flow models are very time-and work-intensive and
therefore are not justified at this early stage of evaluation.
Macon/Dockery FS C-4 July 5, 1991
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Data collected during the RI specific to the aquifer at the Macon/Dockery Site were used
as input to the model. Data used as input parameters include average horizontal and
vertical hydraulic conductivity and aquifer thickness (Table C.4). Hydraulic conductivities
were calculated using slug tests (Section 4.6.3 of the RI) and Shelby tube samples (Section
4.6.6 of the RI; Sirrine, 1991a), and aquifer thickness was derived from monitoring-well logs
(Appendix C of the RI; Sirrine, 1991a). Specific yield is also an input parameter. The value
of specific yield was estimated from values stated in hydrogeology literature (Freeze and
Cherry, 1979). Extraction wells were simulated as 6-inch diameter and fully-penetrating.
Model calculations were made to develop conceptual designs for two scenarios: removal
of all ground water above MCLs at the Upper and Lower Macon and the Upper and Lower
Dockery Sites. As a conservative estimate of contaminant areal extent, the concentration
distributions calculated using a ten-year period of chemical migration (Phase I Modeling)
were used to locate extraction wells and determine duration and rate of pumping. During
remedial design, this conceptual extraction system design may be modified based on a
more-accurate concentration distribution developed by installing additional monitoring points
at strategic locations. Locations of proposed extraction wells are shown on Figures C.1 and
C.2.
For extraction of ground water above MCLs, 12 wells pumping at a total rate of 41 gallons
per minute (gpm) will create the necessary capture zone. This includes: five wells, each
pumping at 4 gpm, at the Upper Macon Site; two wells, each pumping at 4 gpm, at the
Upper Dockery Site; three wells, each pumping at 3 gpm, at the Lower Macon Site; and
two wells, each pumping at 2 gpm, at the Lower Dockery Site.
To estimate the necessary period of pumping to remove ground water above MCLs, the
volume of contaminated aquifer was estimated using the maximum areal extent of
contamination at each Site, as calculated in Phase I Modeling, an effective porosity of 0.3,
and an aquifer thickness of 25 feet. This volume and the pumping rates for each Site were
used to calculate the period of time necessary to remove one aquifer· volume of ground
Macon/Dockery FS C-5 July 5, 1991
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water. A Batch Flushing Model (EPA, December, 1988b) was used to calculate the number
of aquifer volumes that must be removed to achieve remediation with respect to the
contaminant found at the highest concentration at each Site. This model simulates a series
of consecutive, discrete flushing periods during which clean water, introduced at a known
rate, fills the aquifer pore space. It is assumed that, between each flushing, the total mass
of contaminant is in chemical equilibrium between the solid phase (aquifer material) and the
liquid phase (ground water). Parameters used in modeling include aquifer bulk density
(Table C.1), effective porosity (0.3), distribution coefficients for chemical constituents (Table
C.1) and maximum contaminant concentrations (RI; Sirrine, 1991a)., The porosity was
changed to 0.3 from that used in ground water flow modeling (0.2) to calculate a
conservative estimate of the volume of contaminated ground water.
The Upper and Lower Macon Sites were modeled based on trichloroethene. The Upper
and Lower Dockery Sites were modeled based on 1, 1-dichloroethene. Results of this
modeling indicate that removal of all ground water above MCLs at each Site will require an
estimated maximum of 16 years .
Macon/Dockery FS C-6 July 5, 1991
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TABLEC.1
MODEL PARAMETER VALUES USED IN MODELING WITH CONMIG
Parameter Value Notes
Actual Porosity 0.4 calculated (Appendix K of RI)
Effective Porosity 0.2 estimated (Appendix K of RI)
Aquifer Thickness 25 ft average (RI)
Longitudinal Dispersivity 70 ft estimated (Section 6.3.2 of RI)
Transverse Dispersivity 7 ft estimated (Section 6.3.2 of RI)
Seepage Velocity calculated (Section 4.6.4 of RI)
Macon site 0.21 ft/d
Dockery site 0.16ft/d
Aquifer Bulk Density 1.5 g/cm3 estimated (Section 6.3.2 of RI)
Distribution Coefficient Kd* Koc
Organics calculated (Appendix K of RI)
trichloroethene 0.082 126
1,2-dichloroethene 0.039 59
1, 1-dichloroethene 0.042 65
1,1,1-trichloroethane 0.116 178
tetrachloroethene 0.237 363
vinyl chloride 0.037 57
In organics Log Kd measured (Table E.2 of Appendix E)
Cadmium 0.8
Chromium 1.6
Nickel 2.0
• Kd = (Koc)(foc) where foe = 0.000653 (appendix K of RI)
RI = Remedial Investigation (Sirrine, 1991a)
6/28/91; GWMOD-1.MD
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TABLE C.2
SOURCE-AREA LOADING AND RESULTANT EXTENT OF CONTAMINANT MIGRATION
5-year plume 10-year plume
Ground Waler Above MCLs Source-Area Loading Maximum Maximum Maximum Maximum
Number of Concentrations at Longitudinal Transverse Longitudinal Transverse
Site Chemical Injection Point Injection Points (ug/1) Extent (ft) Extent (ft) Extent (It) Extent (ft)
Upper Macon 1rlchloroe1hene 4 50,250,600, 2500 675 350 950 475
1,2-dlchloroethene 3 550,600,650 375 50 525 100
tetrachloroelhene 2 60,170 475 75 675 100
vinyl chloride 1 2750 625 300 925 400
chromium 500,2750,3000 300 100
nickel 500,2750,4500 150 100
Lower Macon trlchloroethene 2 100,100 275 50 475. 100
chromium 330,120 75 50
Upper Dockery 1, 1-dlchloroethene 1 12000 575 200 775 300
1, 1, 1-trlchloroethane 1 10000 325i 100 525 100
chromium 15000 150 100
Lower Dockery 1, 1-dlchloroethene 1 150 275 50 425 100
chromium 20 50 50
nickel 400 50 50
7/1/91; GWMOD-2.MD
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TABLE C.4
MODEL PARAMETER VALUES USED IN MODELING WITH WELFLO
Parameter Value Notes
Horizontal Hydraulic Conductivity 0.82 ft/d calculated (section 4.6.3 of RI)
Vertical Hydraulic Conductivity 0.04 ft/d calculated (section 4.6.6 of RI)
Specific Yield 0.15 estimated
Aquifer Thickness average (appendix C of RI)
Upper Macon site 35 ft -Lower Macon site 30 ft
Upper Dockery site 40 ft
Lower Dockery site 25 ft
7/1/91; GWMOD-6.MD
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APPENDIX D
PROTECTIVE LEVELS FOR SITE CHEMICALS (PPLVs)
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Four chemicals present In the ground water at the Macon/Dockery Site lack established
water quality criteria for consideration in development of remedial alt~rnatives: acetone,
chloroethane, 1, 1-dichloroethane, and lsophorone. Target concentrations are required for
application at the point of exposure identified In the baseline risk assessment, I.e., ground-
water ingestion. It therefore was necessary to attempt to develop health-based ground-
water levels for these chemicals. The preliminary pollutant limit value (PPLV) concept was
used to obtain risk-based levels protective of human health for 3 of the 4 chemicals. A
thorough literature search did not result· in any quantitative risk data for chloroethane.
Chloroethane, however, is further discussed below.
The preliminary pollutant limit value concept has been used extensively, primarily by the
U.S. Army to help establish cleanup levels for soil and water, and goals for preventing
undue exposure to toxic chemicals from uncontrolled hazardous waste sites. The methods
Involved are described in numerous agency reports and in at leasf one peer-reviewed
journal (Rosenblatt et at., 1986). The application of this concept to the Macon/Dockery Site
is presented below .
Development of Preliminary Pollutant Values
Preliminary pollutant limit values (PPLVs) were calculated using the following standard
parameter values for chronic human exposure via the ground-water ingestion pathway: 70
kg adult body weight and an adult drinking water consumption rate of 2 liters per day (EPA,
1990c}. Site-specific parameter values used here (exposure frequency, exposure duration,
and averaging time) are taken from the Risk Assessment for the :Site. Estimates of
acceptable daily Dose (Dt) were derived from the best available toxicological data, as
explained below for each chemical.
Macon/Dockery FS D-1 July 5, 1991
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The PPLV for ingestion of ground water is calculated by:
Ground Water PPLV = Dt x body weight x averaging time
daily water intake x exposure frequency x exposure duration
Acetone
The EPA Carcinogen Assessment Group has classified acetone as a group D substance,
i.e., not classifiable as to human carcinogenicity. The oral RfD of 0.1 mg/kg/day (EPA,
1991 a) is therefore used as the acceptable daily dose for acetone.
The health based ground-water level for acetone is calculated as follows:
Ground-Water PPLV = 0.1 mg/kg/day x 70 kg x 10950 days
2 liters x 365 days/year x 30 years
= 3.5 mg/L or 3500 ug/L
Chloroethane
After a thorough literature search, no information was found about the potential
carcinogenicity of chloroethane or about quantitative risks. Chloroethane was only found
in the ground water of two monitoring wells at the Upper Macon Site: 21 ug/L in MW-19
and 60 ug/L in MW-9 (Figure 2.1 ). Chloroethane is considered to less toxic than methyl
chloride and many other lower chlorinated aliphatic hydrocarbons and it does not constitute
a serious health hazard in the industries where it is produced and used (Encyclopedia of
Occupational Health and Safety, 1983). It is used as a topical anesthetic for humans and
animals, solvent, refrigerant, and alkylating agent (Merck, 1989). Human toxicity is
described as mildly irritating to mucous membranes and at high concentrations can cause
narcosis and unconsciousness (Merck, 1989).
Macon/Dockery FS D-2 July 5, 1991
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Based on its (1) localized, low concentration in the ground water, (2) lack of significant
concern about its toxicity by governmental agencies, in spite of its industrial uses, and (3)
low qualitative human toxicity, chloroethane does not appear to be of significance at the
Site.
1, 1-Dichloroethane
Although 1, 1-dichloroethane has been classified as a Group C (possible human carcinogen)
by the EPA Carcinogen Assessment Group, the slope factor has been withdrawn pending
review (EPA, 1991a). The oral reference dose for noncarcinogenic effects (RfD) of 0.1
mg/kg/day (EPA, 1990d) Is therefore used as the acceptable Dt for 1,1-dichloroethane.
The health based ground-water level for 1,1-dichloroethane is calculated as follows:
Ground-Water PPLV = 0.1 mg/kg/day x 70 kg x 10950 days
2 liters x 365 days/year x 30 years
= 3.5 mg/Lor 3500 ug/L
lsophorone
lsophorone is classified as Group C (possible carcinogen) by the EPA Carcinogen
Assessment Group (EPA, 1991 a) with a slope factor of 0.0041. To calculate a acceptable
daily dose (Dt), the inverse of the slope factor is multiplied by a de minimis upper bound
risk factor of 10E-4 (Travis, 1987). This results In a Dt of 0.02 mg/kg/day. However, the
EPA Office of Drinking Water uses 1 0E-5 as a target risk in setting standards/guidelines for
Class C carcinogens. Consequently, the Dt is 0.02 mg/kg/day.
The health based ground-water level for isophorone is calculated as follows:
Macon/Dockery FS 0-3 July 5, 1991
I ._ Ground-Water PPLV = 0.002 mg/kg[dal£ x 70 kg x 10950 dal£S
2 liters x 365 days/year x 30 years
I = 0.07 mg/L or 70 ug/L
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APPENDIX E
DEVELOPMENT OF POTENTIAL SOIL REMEDIATION LEVELS
FOR THE VADOSE ZONE
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Introduction
Remediation levels for subsurface soils located above the water table (the vadose zone or
the unsaturated zone) are based on the potential of a chemical to potentially impact ground
water. Concentrations of chemicals in subsurface soil that are protective of ground water
were developed using the Vadose Interactive Processes (VIP) model (Stevens, et al., 1991).
The purpose of this appendix is to provide an overview of the· VIP model and to provide
the assumptions and detailed information used to perform the VIP modeling. A discussion
of the results and conclusions is provided in Section 3.2.3.3.
The VIP model was developed by the Civil and Environmental Engineering Department of
Utah State University (Logan, Utah) and EPA's Kerr Environmental Laboratory in Ada,
Oklahoma. Chemical-specific fate and transport processes simulated by the VIP model
include volatilization, degradation, sorption/desorption, advection, and dispersion. In
addition, site-specific parameters such as soil type, organic carbon content, and ground
water recharge are variable to allow for more accurate modeling.
Overview of the Vadose Zone Modeling
Following is an overview of the VIP modeling process for the Macon/Dockery Site. As
discussed, the Site consists of 4 sub-sites: Upper Macon, Lower Macon, Upper Dockery,
and Lower Dockery. Probable source areas (e.g., Lagoons 1-9, 10, 11, and 12 and the
Upper Dockery Site) are shown on Figures 2.1 and 2.2. Consequently, VIP modeling was
done for each sub-site. In addition, Lagoon 1 O and Lagoon 11 at the Lower Macon Site
were modeled separately because of differences in the waste materials and concentrations.
The maximum vadose zone soil concentrations for chemicals detected at the Site are
presented in Tables 3.4 (Upper Macon), 3.5 (Lagoon 10, Lower Macon), 3.6 (Lagoon 11,
Macon/Dockery FS E-1 July 5, 1991
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Lower Macon), 3.7 (Upper Dockery), and 3.8 (Lower Dockery). Maximum concentrations
for semivolatiles generally were found in test pits (depth to 10 feet or less). Maximum
concentrations of volatiles and inorganics were more widespread with respect to depth.
Some maximum concentrations were In test pits ( < 1 0 feet) while some were as deep as
27 feet below the ground surface.
An Initial modeling run was conducted for each chemical of Interest. The maximum vadose
zone concentration for a chemical at each sub-Site (and Lagoons 10 and 11) was entered
and modeling results generated. The model predicted the maximum water-phase
concentration at the bottom of the vadose zone and the time at which this maximum
occurs. This concentration (ug/L) was then conceptually mixed (diluted) in the ground water
beneath the vadose zone of interest. The resulting predicted concentration for a particular
chemical was then compared to ground water data and if actually found In Site ground
water, then to its potential ground-water remediation level (Section 3.2.3.1; Table 3.3).
Generally, MCLs or PPLVs were used to compare the estimated maximum ground water
concentration resulting from the effect of a chemical in the vadose zone on the ground
water. Since some chemicals of interest are estimated to either degrade or are essentially
immobile, they do not leach out of the vadose zone at any significant concentration, and
hence are not compared to ground water standards.
Major Assumptions Used for the VIP Modeling
Following is a discussion of the significant assumptions used in the VIP modeling program.
Included in the VIP model is the Soil Transport and Fate (STF) data base with published
literature values for chemical-specific physical/chemical properties. Also included in the VIP
database are chemical-specific fate processes such as degradation and equilibrium
partitioning coefficients. These values and other peer-reviewed literature values were used
for the VIP modeling.
Macon/Dockery FS E-2 July 5, 1991
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Major assumptions used in the VIP modeling are summarized in Table E.1. As stated on
page 2-4 of the FS, the Macon and the Dockery Sites are rather homogeneous with respect
to lithology, Including vadose zone soil. Therefore, VIP model assumptions presented In
Table E.1 are valid for both the Macon and Dockery Sites.
A number of input parameters were not used in the VIP modeling. These parameters were
either deemed to be unimportant fate processes (e.g., volatilization), not relevant to the
chemicals of interest, or not relevant to the Site conditions. Significant assumptions and
Site-specific parameters are discussed below.
Distance Between Contamination in Vadose and Water Table For modeling purposes, the
maximum concentration of each chemical was assumed to be distributed over a zone four
feet thick. Sampling distances for soil borings were from 15-17 and 25-27 feet below
ground surface, for a sampling distance of two feet. This distance was doubled (i.e., four
feet) for use in the VIP modeling. The assumption that the maximum contaminated
thickness zone is 4 feet overestimates the impact of vadose zone contaminants on the
ground water since this decreases the estimated distance to ground water by one foot. For
example, if the maximum contamination were found at the 25-27 foot depth, then the center
(vertically) of that zone is at 26 feet. The maximum assumed contamination zone (four feet)
would also be centered at 26 feet and thus extend downward to 28 feet. Twenty eight feet
Is one foot closer to the ground water table and hence is a more conservative assumption
than the bottom of the boring which was at 27 feet below surface. Distances from the
maximum chemical concentration to the top of the water table are summarized In Tables
3.4 through 3.8.
Son Partitioning Coefficients (Kd) One of the most important parameters used in predicting
the fate of organic chemicals in the vadose zone is the affinity of a chemical to bind to
organic matter and soil particles. For a particular soil, a partitioning coefficient (Kd) can be
measured or calculated.
Macon/Dockery FS E-3 July 5, 1991
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Measurement of Kd values is tedious, time-consuming, and expensive. Consequently, many
researchers have observed that Kd values for organics may be predicted on the basis of
a non soil-specific parameter known as the organic matter partitioning :coefficient, Koc. Kd
values may be calculated from the following equation:
Kd = Koc x Foe
where Foe = fraction of organic carbon in the soil.
The median value for the fraction of organic matter in the vadose z,one at the Site was
determined to be 0.00065 (Sirrine, 1991a). Koc and Kd values for organic compounds are
reported in Table E.2.
For metals, the most significant fate (i.e., transport) process is sorption to clay particles.
Equilibrium sorption coefficients (Kd) for metals are primarily depend~nt on the metal, the
soil, and the soil pH. Specific Kd values for metals were obtained from either Savannah
River Site (SRS) published values (Looney et al., 1987) or from Dragun (1988). SRS data
were preferred since there are similar soil types between the SRs: and the Site (e.g.,
Orangeburg series). Some metals had published Kd values that spanned several orders
of magnitude. Use of extremely low Kd values would tend to overestimate the potential
transport of metals from the vadose zone while use of high Kd values would underestimate
transport. Consequently, best professional judgement and a consideration of Site-specific
factors were used to select an intermediate and reasonable Kd value for a metal. As
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mentioned, preference was given to the SRS data which in general had lower Kd values
than those reported by Dragun (1988). Kd values for metals are rep_orted in Table E.2.
Degradation Half-Lives Another fate process that is important for predicting the
concentration at which an organic chemical may reach the water table Is the chemical's half-
life In the soil. First order decay constants associated with biodegradation or hydrolysis
are the most common rate constants used in the VIP model. Half-lives used In the VIP
Macon/Dockery FS E-4 July 5, 1991
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modeling are listed in Table E.2. If published rate constants could not be found in the
literature, then no degradation was assumed (i.e., the compound was considered to be
conservative). Since metals do not degrade, no half-life values were used in the VIP model.
Water Bulk Flow Another important input for the model is the bulk flow of precipitation of
water through the vadose zone (vertical flux). The model assumes one dimensional
downward flow of water through the vadose zone.
Two parameters determine the bulk flow of water through the vadose zone: (1) an
empirical relationship between soil texture and soil water content as developed by Clapp
and Hornberger (1978), and (2) recharge rate. The most appropriate Clapp and
Hornberger empirical constant for Site soils was 7.1 (a silty loam). As determined in the
RI, a recharge rate of 12 inches per year was used. This resulted in a volumetric water
content for the Site soils of 13. 7%.
Volatmzation Since the chemicals of interest are several feet below the ground surface,
volatilization was not considered to be a significant removal process for organics.
Model Output
Model output provides a plot of contaminant concentration (in soil water) versus depth at
a certain time (Figure E.1 ). If the maximum concentration is not yet at the bottom of the
vadose zone (vadose/ground water interface), then the model is run with a longer simulated
time period. The simulated time is increased until the maximum contaminant concentration
is found at the vadose zone/ground water interface, or until 50 years. Modeling over 50
years is inaccurate and not possible with the VIP model. The resulting leachate
concentration (ug/L) is then conceptually mixed (diluted) with the ground water below the
vadose zone (next section).
Macon/Dockery FS E-5 July 5, 1991
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Mixing of Vadose Leachate With Ground Water
There were several Important factors considered when estimating the amount of mlxlng that
occurs between leachate (recharge) and water already in the aquifer. These factors
Included the flux of leachate water entering the aquifer, the chemical concentration In this
water when it reaches the water table, and the areal extent of this affected recharge at the
site. Important aquifer parameters considered were flux of ground water beneath the sub-
site and the depth to which the two waters will mix.
A mass balance approach was used to calculate the concentration of a chemical after it Is
mixed with ground water:
c(aw) = cm x am
Q(I) + Q(gw)
where:
C(gw) = final concentration in ground water after leachate from
the vadose zone is added
C(I) = concentration in leachate (predicted from VIP model)
Q(I) = volumetric flow rate of leachate; equals the flux
rate from the VIP model times the surface area (A) of
the unit being modeled
Q(gw) = volumetric flow rate of ground water entering the mixing
zone per unit time; calculated from the hydraulic
gradient, hydraulic conductivity, and mixing depth.
Leachate concentrations were diluted by a factor of approximately two 'after mixing with the
ground water in the mixing zone. Site-specific values used to calculate 0(1), Q(gw), and
A are presented In Table E.3. Final concentrations of chemicals calculated in the ground-
water were then compared to potential ground water remediation levels (Table 3.3).
The mlxlng depth Is calculated based on the VHS Model (50 Federal Register 229: 48896,
November 27, 1985). The model recommends a vertical dispersivity of 0.2 meters (0.656
Macon/Dockery FS E-6 July 5, 1991
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feet) to simulate a reasonable worst-case scenario. A dispersivity of 0.656 feet Is typical
for a silty loam. The predominantly silVsandy aquifer found at the Macon/Dockery Site
would have a slightly higher dispersivity than a silty loam soil. Consequently, a vertical
dlspersivity of 0.7 feet (az; Table E.3) was used for calculating the mixing zone.
Potentiometric ground-water maps were examined in determining the width of the source I areas in a direction parallel to ground-water flow. This width (W) was used In calculating
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the vertical mixing depth (z: Table E.3).
The mixing depth was calculated as follows:
z = (azW)0.5
where:
z = mixing depth (L)
az = vertical dispersivity (L)
W = Width of source area parallel to ground water flow (L).
Site-specific information and assumptions used for calculating the mixing depth are
presented in Table E.3.
Results and Discussion
A discussion of the results and conclusions from the modeling is provided in Section 3.2.3.3 I of the FS text.
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Macon/Dockery FS E-7 July 5, 1991
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Table E.1
Assumptions Used in the VIP Model for the Macon/Dockery Site
Richmond County, North Carolina
CONSTANT VALUES FOR THE SITE:
Clapp and Hornberger
Constant
Dry bulk density
Porosity
Fraction organic
constant
Recharge rate
Thickness of maximum chemical
concentration in vadose zone
= 7.1 (unitless) for a sandy clay loam
= 1.5 g/cm3
= 0.2 (unitless)
= 0.00065 (value from RI)
= 1 ft/year (value from RI)
= 4 feet
VALUES WHICH VARY WITH THE SUBSITE CONSIDERED:
Maximum concentration of
chemical in vadose zone:
Depth to ground water:
Tables 3.4 -3.8
Tables 3.4 -3.8
VALUES WHICH VARY WITH THE CHEMICAL OF CONCERN:
Partitioning coefficient (kd):
Degradation rate:
Macon/Dockery FS
Table E.2
Table E.2 (If no data were available, no
degradation was assumed; for metals,
degradation rate equals zero)
July 5, 1991
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Table E.2
Chemical-S,-clfic Parameters Used In the VIP Modeling
Macon/Dockery Sita, Richmond County, North Cmorna
Chemical
Log Koc
(cm"3/g)
Kd
(em"'3/g)
Half-life
(Days)
(sNnote 1} I Semivolatnes
Acenapthene
~naphthylen1
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluOfarthene
Benzo(g,h,ijpe,yterm
Benzo(k)fluoranthene
S.nzoieAcid
Bia(2-ethylhexyl)phthaiate
Chrysene
Oibenzo(a,h)anthracene
Dibenzofuran
Di-ethyl phthalate
Di-methyl phthalate
01-n-butyl phthalate
DI-n-octyl phthalate
AUOfanthene
Fluorene
lndeno(1,2,3-ed)pyrene
lsophorone
2-Methylphenol
2-Methylnaphthalene
Naphthalene
Pentachlo,ophenol
Phenanthrene
Phenol
Pyrene
2,4,5-Trichlorophenol I volatiles
Acetone
Benzene
2-Butanone
Chloroform
1, 1 -OicMoroethana
1,2-Dichlotoethe.-. (total)
Ethylbenzene
2-Hexanone
Methylene Chloride
4-Methyl-2-Pentanone
Styrene
Tetrachtoroethene
Toluene
1,1,1-Trichloroethane
Trichtoroethene
X lenes otal
lnor nics
Antimony
Arsenic
Barium
Berylliun
Cadmium
Chromh.m
Cobalt
Copper
Load
Manganese
Mercury
Nickel
Seleniun
Thallium
Vanadium z;.,.,
1.25
3.68
4.41
5.27
5.8
5.8
6.89
6.64
2.26
4.5
5.27
6.23
4
1.64
1.64
3.14
8.99
4.75
3.7
7.23
1.49
1.34
3.93
3.17
2.98
4.22
1.43
4.92
3.38
1.17
1.73
1.3
1.58
1.12
1,77
1.98
2.13
1.49
0.79
2.87
2.58
1.97
2.25
1.98
2.34
loKdml 5
3.6
1.2
0.8
1.6
1
1.4
2
5
1.7
2
0.4
1.2
1.16E-02
3.11E+OO
1.67E+01
1.21E+02
4.10E+02
4.10E+02
5.04E+03
2.84E+03
1.18E-01
2.06E+01
1.21E+02
1.10E+03
15.SOE+OO
4.SOE-02
2.84E-02
8.li'l7E-01
e.35E+05
3.66E+01
3.26E+OO
1.10E+04
2.01E-02
1.42E-02
5.53E+OO
9.61E-01
5.93E-01
1.08E+01
1.75E-02
5.41E+01
1.49E+OO
9.61E-03
3.49E-02
1.30E-02
2.47E-02
8.57E-03
3.82E-02
6.21E-02
8.nE-02
2.01e-02
4.01E-03
4.82E-01
2.36E-01
6.07E-02
1.16E-01
6.21E-02
1.42E-01
Kd mt/
3981
16
6
40
10
25
100
100000
50
100
3
16
Note 1: A blank space indicates that no half-Ile was found in the literature; consequenUy,
no degradation was assumed; hatf-lWes are assumed to be constant with depth
1 = Qoundwater Chemicals Desk Reference (Montgomery and Welkom, 1990)
2 = STF Database (Stevena et al., 1Q91)
3 = Kd values for Savannah Rive, Site, f!.iken, South Carolina (Looney et al., 1 li'l87)
(Thne values were selected baaed on the similarity of soil aeries (e.g., Orangeburg series)
bet-Neen the Savannah River Site, where extensive soils research has been conducted,
and the Macon/Dockery Site)
4 = Mean value (Dragun, 1988)
5 = No Kd values were found for barium, berylliun, thalliun, and vanadium
6/28/91, VIP-E2.MD
28
471
1677
2230
4800
231
1900
5761
1634
803
3130
198
2239
686
2.2
821
68
6.5
474.5
184
77
548
300
39
300
329
32
1
2
2
2
2
2
2
2
1
2
2
2
1
2
2
2
2
2
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
2
1
2
2
2
2
2
3
4
3
3
3
3
3
4
4
3
3
3
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Table E.3 Parameters Used to Calculate Volumetric Flow Rates
Macon/Dockery Site, Richmond County, North Carolina
Volumetric Flow Rate: Leachate /Q(I))
Q(I) = AxR
Where: A = area of source (sq ft)
A= LxW
R = annual recharge rate (ft/day; from the RI)
Where: L = length of source area (feet)
W = width of source area parallel to around-water flow lfeefl
Volumetric Flow Rate: Ground Water (Qtnw\\
Q(gw) = kx ix A
Where: k = hydraulic conductivity (feet/day)
i = ground-water gradient (unltless slope)
A = area perpendicular to ground-water flow (square feet)
= Lx z
Where: L = length of source area (feet)
z = mixina death /feetl
Site-specttic Values Used to Calculate Q(I) and Q(gw)
Lower Macon
Uooer Macon Laaoon 10 Laaoon 11 Un=r Dockerv Lower Dockery
am
L(fee~ 100 100 100 100
W(feet) 190 110 100 60
Rift/day) 0.00274 0.00274 0.00274 0.00274
Qlnw)
k(ft/day) 0.62 0.62 0.62 0.62
i 0.05 0.05 0.05 0.04
L (feeQ 100 100 100 100
z (feeQ 11.5 7.5 6.4 6.6
/see belowl
Mixina Death Calculations !from the VHS Medell
0.5
z = (azW)
Where: z = mixing depth (feet)
az = vertical dispersivlty (feet)
W = width of source area parallel to ground-water flow (feet)
Assume: az = 0.1 x transverse dispersivrty (7 ft.; from the RI)
az = 0.7 feet
7/2/91, VIP-E3.MD
100
100
0.00274
0.62
0.04
100
6.4
-_,,_ - - - - - -II -- - ----·--
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SITE NAME:
OPERABLE UNIT:
SCENARIO:
RUN BY:
***** VERSION 3.0 DRAFT***** DATE:
TIME:
CORA SOIL EXCAVATION COST MODULE (201)
MACON DOCKERY
ENTIRE SITE ESTIMATED START: EARLY FY 1992
MODULES COMMON TO ALL SCENARIOS
PHONE NUMBER:
INPUTS RESULTS
(lf,/27 /'31
14: 4'3: 43
-----------------------------------------------------------------------
LAGOON 7
Sc,il type
Parameter
Depth of excavation (ft)
1. Steel sheeting or
2. side slope?
Horizontal component
Length of excavation Cftl
Width of excavation (ft)
Depth of cover above
contaminated materials (ft)
Depth of contaminated excav.
w/o continuous sampling (ft)
Depth of contaminated excav.
w/continuous sampling (ftl
Thickness of lifts (inches)
Number c,f drums
'Pct. of contaminated zone
Base air monitoring required?
Pct. of backfill available
onsite
Value
4
25
2
2
75
50
3
0
22
24
0
(>
y
100
Compc,nent Total
BYPRODUCTS FOR TRANSPORT/DISPOSAL:
DRUMS
CONTAMINATED SOIL (CY)
(SWELL FACTOR=l.45)
0
15,503
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***** VERSION 3.0 DRAFT***** DATE: 06/27/91
TIME: 14:4'3:4'3
CORA SOIL EXCAVATION COST MODULE (201)
SITE NAME: MACON DOCKERY
OPERABLE UNIT:
SCENARIO:
ENTIRE SITE ESTIMATED START: EARLY FY 1992
MODULES COMMON TO ALL SCENARIOS
RUN BY: PHONE NUMBER:
INPUTS
Parameter
Protection level f~r:
Uncontaminated materials
Contaminated materials
Te~perature (degrees Fl
Confidence level
Value
D
C
60
L
RESULTS
Component
COST FOR ALL EXCAVATIONS
CAPITAL COST
0 ~, M COSTS
*** Excavation depth cannot exceed 25 feet. For excavations
deeper than 25 feet, complex site-specific sheeting, bracing,
dewatering, terracing and haul roads may be required.
Excavation for depths deeper than 25 feet should be scoped and
costed on a site-specific basis.
NOTES:
LAGOON 7
Tc,tal
750,000
0
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***** VERSION 3.0 DRAFT***** DATE: 06/27/91
TIME: 1'4:55: 10
CORA OFFSITE INCINERATION COST MODULE (302)
SITE NAME: MACON DOCKERY
OPERABLE UNIT:
SCENARIO:
ENTIRE SITE ESTIMATED START: EARLY FY 1':1'32
MODULES COMMON TO ALL SCENARIOS
RUN BY: PHONE NUMBER:
INPUTS
Parameter
WASTES WITH PCB:
Materials to be packaged:
Soils <CY)
PCB concentration (PPM)
Liquids <GAU
PCB concentration <PPM)
Water wastes (GAL)
Level of protection
Bulk liquids (LBS)
PCB Concentration (PPM)
Steel drums
Drums with soils
PCB concentration (PPM)
Drums with liquids
PCB concentration (PPM)
Drums with water wastes
Ta:,~ per ton
WASTES WITHOUT PCB:
Material to be packaged
Soils (CY)
Water wastes (GAL)
Sllldges & Tars (CY)
Lo\,,! chloride org. (GAL)
High chloride org. (GAL)
Level of protection
Drums with soils
Drums with water wastes
Drums with sludges & tars
Drums w/low chlor. org.
Drums w/high chlor. org.·
Steel d·,,.,ms
Pumpable sludges (LBS)
Water wastes (LBS)
High chloride ot·g. (LBS)
Low chloride org. (LBS)
Ta~,; pei~ ti:,r:
Value
0
0
0
0
0
C
0
0
0
0
0
0
(l
0
Unit
Cost
0.00
0.00
0.00
0.00
27.00
1300
(l
0
0
0
C
0 177.00
0 200.00
0 375 .. 00
0 170.00
0 325.00
(l
0 0.45
0 0.30
0 0.35
0 0. 10
27 .. 00
RESULTS
Component
OFFSITE INCINERATION
CAPITAL COST
0 t, M COSTS
TRANSPORTATION
CAPITAL COST
0 g, M COSTS
Total
2,100,000
0
400,000
0
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***** VERSION 3.0 DRAFT***** DATE: D6/27/91
TIME: 14: 55: 25
CORA OFFSITE INCINERATION COST MODULE (302)
SITE NAME: MACON DOCKERY
OPERABLE UNIT:
SCENARIO:
ENTIRE SITE ESTIMATED START: EARLY FY 1992
MODULES COMMON TO ALL SCENARIOS
RUN BY: PHONE NUMBER:
INPUTS
------------------------------------------
Unit
Parameter Value Cc,st
Miles to offsite facility 1200
Demurrage time/load (hrs) 2
Average temp (deg. F) 60
Capital or O&M incin. cost? C
Capital or O&M transport cost? C
Confidence level M
RESULTS
*** Material-handling equipment at commercial incinerators are
generally not amenable to handling bulk solids and sludges.
Costs for packaging these materials will be added to the
disposal costs. Additionally, the user may wish to place
liquid wastes in drums for reasons of small quantity or
compatibility concerns.
NOTES:
Incineration of Lagoon 7 Materials at Deerpark TX:
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SITE NAME:
OPERABLE UNIT:
SCENARIO:
RUN BY:
INPUTS
***** VERSION 3.0 DRAFT*****
CORA METALS PRECIPITATION COST MODULE
MACON DOC,::ERY
ENTIRE SITE ESTIMATED START: EARLY
MODULES COMMON TO ALL SCENARIOS
PHONE NUMBER:
DATE:
TIME:
(311)
FY 1 '3'32
RESULTS
Parameter Value Unit Component
Flow 29.00
Susp. Sol. 250.00
Acidity 250.00
Alkalinity 250. ()~)
pH 6.50
Cd o. 10 ' Zn 0.73
Ni 2. 12
Pb 0.50
Cu 1. 16
Hg 0.05
Cr(VI) (l. 70
GPM
MG/L
MG/L
MG/L
MG/L
MG/L
MG/L
MG/L
MG/L
MG/L
MG/L
CAPITAL COST
0 ~, M COSTS
LABOR
LIME
CAUSTIC SODA
SULFURIC ACID
POLYMER
SODIUM METABISULFITE
BASE O ~, M COST
TOTAL O & M COSTS
07 /02/'31
13:1'3:37
Total
1,000,000
270,000
6,500
0
1 '3, 000
150
84
73,000
368,734
Cr(III) 0.70 MG/L BYPRODUCTS FOR TRANSPORT/DISPOSAL:
Ba 5.00 MG/L SLUDGE (CY/YR) 894
Al 3'31. 00 MG/L
Ca 25. '30 MG/L
Fe 640.00 MG/L
Mg 55.50 MG/L
Mn 6. 13 MG/L
S04 250.00 MG/L
Ad.just pH •,,;/ 1 ime
or caustic soda? L
Temperature 60 Deg. F
Confidence level L
P-rotection level D
I NOTES:
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Metals Removal from Upper and Lower Macon Groundwater by Coagulation
(Cost Approximation using Precipitation Cost Module)
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SITE NAME:
OPERABLE UNIT:
SCENARIO:
RUN BY:
INPUTS
***** VERSION 3.0 DRAFT*****
CORA METALS PRECIPITATION COST MODULE
MACON DOCKERY
ENTIRE SITE ESTIMATED START: EARLY
MODULES COMMON TO ALL SCENARIOS
PHONE NUMBER:
DATE:
TIME:
C: 311)
FY 19'32
RESULTS,
Parameter Value Unit Component
Flc,w 20.00
Susp. Sol. 250.00
Acidity 250.00
Alkalinity 250.00
pH 6.50
Cd o. 10
Zn 0.53
Ni o. 17
Pb 0.50
Cu 0.50
Hg 0.01
Cr(VI) 0.50
GPM
MG/L
MG/L
MG/L
MG/L
MG/L
MG/L
MG/L
MG/L
MG/L
MG/L
CAPITAL COST
0 ~< M COSTS
LABOR
LIME
CAUSTIC SODA
SULFURIC ACID
POLYMER
SODIUM METABISULFITE
BASE D ~< M COST
TOTAL D & M COSTS
07 /02/'31
13:28:01
Tc,tal
1,600,000
180,000
4,300
0
13,000
100
41
42,000
23'3, 441
Cr(III) 0.50 MG/L BYPRODUCTS FOR TRANSPORT/DISPOSAL:
Ba 1. (H) MG/L SLUDGE (CY/YR) 24'3
Al 107.00 MG/L
Ca 30. 10 MG/L
Fe 199.00 MG/L
Mg 53. 10 MG/L
Mn 3.81 MG/L
S04 250.00 MG/L
Adjust pH w/lime
or caustic soda? L
Temperature 60 Deg. F
Confidence level L
Protection level D
NOTES:
Metals Removal from Upper and Lower Dockery Groundwater by Coagulation
(Cost Approximation using Precipitation Cost Module)
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***** VERSION 3.0 DRAFT***** DATE:
SITE NAME:
OPERABLE UNIT:
SCENARIO:
RUN BY:
TIME:
CORA PRESSURE FILTRATION COST MODULE (313)
MACON DOCKERY
ENTIRE SITE ESTIMATED START: EARLY FY 1992
MODULES COMMON TO ALL SCENARIOS
PHONE NUMBER:
INPUTS RESULTS
Parameter
Flc,w <GPMl
TSS (MG/U
Value
30
Component
---------. ---------
CAPITAL COST
0 & M COSTS
07 /02/'31
13:42:36
Total
670,000
37,000
Average temp (degrees Fl
Protection level
Confidence level
60
D
L
BYPRODUCTS FOR TRANSPORT/DISPOSAL:
WET SLUDGE (CY/YR) 8
NOTES:
Metals Removal from Upper and Lower Macon Groundwater by Filtration
(Cost Approximation using Pressure Filtration Cost module)
(
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***** VERSION 3.0 DRAFT***** DATE:
SITE NAME:
OPERABLE UNIT:
SCENARIO:
RUN BY:
TIME:
CORA PRESSURE FILTRATION COST MODULE (313)
MACON DOCKERY
ENTIRE SITE ESTIMATED START: EARLY FY 1992
MODULES COMMON TO ALL SCENARIOS
PHONE NUMBER:
INPUTS RESULTS
Parameter
Flow (GPMl
TSS (MG/U
Value
30
.-,c:-..:..J
Component
CAPITAL COST
0 ~< M COSTS
07 /02/':il
13:44:47
Total
670,000
37,000
Average temp (degrees Fl
Protection level
Confidence level
60
D
L
BYPRODUCTS FOR TRANSPORT/DISPOSAL:
WET SLUDGE (CY/YR) 8
NOTES:
Metals Removal from Upper and Lower Doc~tery Groundwater by Filtration
(Cost Approximation using Pressure Filtration Cost Module)
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***** VERSION 3.0 DRAFT***** DATE:
TIME:
CORA WATER INFILTRATION COST MODULE (408)
SITE NAME: MACON DOCKERY
OPERABLE UNIT:
SCENARIO:
ENTIRE SITE ESTIMATED START: EARLY FY 1992
MODULES COMMON TO ALL SCENARIOS
RUN BY: PHONE NUMBER:
INPUTS
Parameter
Flc,w rate (GPM)
Depth to water table (ft)
Soil permeability
Average temp (degrees Fl
Protection level
Confidence level
NOTES:
Value
100
10
3
60
D
L
RESULTS
Component
CAPITAL COST
0 8, M COSTS
07 /02/':H
12: 37: 13
Total
1"30, 000
0
Discharge of Treated Groundwater fyom Upper and Lower Macon Sites to
Infiltration Trenches
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***** VERSION 3.0 DRAFT***** DATE:
TIME:
CORA WATER INFILTRATION COST MODULE (408)
SITE NAME: MACON DOC~::ERY
OPERABLE UNIT:
SCENARIO:
ENTIRE SITE ESTIMATED START: EARLY FY 1992
MODULES COMMON TO ALL SCENARIOS
RUN BY: PHONE NUMBER:
INPUTS
Parameter
F 1 ,:,w rate ( GPM)
Depth to water table (ft)
Soil permeability
Average temp (degrees Fl
Protection level
Confidence level
NOTES:
Value
100
10
3
60
D
L
RESULTS
Component
CAPITAL COST
0 ~< M COSTS
07/02/'31
12: 3'3: 38
Total
1'30, 000
(l
Discharge of Treated Groundwater from Upper and Lower Dockery Sites to
Infiltration Trenches
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