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Golder Associates NC, Inc.
5B Oak Branch Drive
Greensboro, NC. 27407 USA
Tel: (336) 852-4903 Fax: (336) 852-4904 www.golder.com
Golder Associates: Operations in Africa, Asia, Australasia, Europe, North America and South America
September 23, 2016 Project No. 0636572016
Ms. Jaclynne Drummond
Compliance Hydrogeologist
Solid Waste Section, Division of Waste Management
North Carolina Department of Environmental Quality
Asheville Regional Office
2090 US Highway 70
Swannanoa, North Carolina 28778
(828) 296-4500
RE: RESPONSE TO COMMENTS
ALTERNATE SOURCE DEMONSTRATION TO ADDRESS ANAMOLOUS VOCS AT MW-28
NCDEQ RESPONSE DATED JUNE 30, 2016
Dear Jackie:
Golder Associates NC, Inc. (Golder) has prepared this report on behalf of Rowan County, North Carolina
(the County) in response to the June 30, 2016, comment letter received from the North Carolina Department
of Environmental Quality (NCDEQ) regarding the County’s recently submitted Alternate Source
Demonstration to Address Anomalous VOCs at MW-28. In the letter, NCDEQ requested that Rowan
County provide additional information with regard to the following potential sources of volatile organic
constituents (VOCs) detected at monitoring well MW-28: landfill gas, 2007 leachate release (compliance
order dated June 11, 2007), and the location of leachate collection system components.
1.0 LANDFILL GAS SOURCE EVAULATION
As documented in the facility’s Landfill Gas Remediation Plan submitted by HDR in July 2013, methane
monitoring well MMW-8, which is located on the same side of the landfill as and approximately 650 feet
upgradient of MW-28, has been impacted from methane released from the landfill and continues to show
methane at concentrations ranging from 4 to 18 percent by volume methane. To address landfill gas as a
potential source of groundwater contamination in MW-28 Golder collected two summa canister samples
from the headspace of MMW-8 and MW-28 on August 15, 2016. At the time of sampling, methane gas
was detected in MMW-8 at a concentration of 6.4 percent by volume using a GEM 2000 methane monitoring
device. Methane was not detected in MW-28 during the August 2016 sampling event with the field meter.
The summa canister samples were collected from MMW-8 and MW-28 over a 30 minute period via the use
of a regulator. The summa canisters were then packaged and returned to ENCO laboratories where they
were analyzed for TO-15 VOCs. The analytical results from the August 15, 2016, summa canister samples
are included in this report as Appendix A.
The results of the summa canister gas sampling were then analyzed using Henry’s Law calculations to
predict groundwater concentrations of VOCs detected in the summa canister samples (included as Table
1). Conversely Henry’s Law was used predict headspace gas concentrations of the VOCs detected in
groundwater during the January 2016 groundwater monitoring event [i.e., tetrachloroethene (PCE) and
trichlorofluoromethane (TCFM)], which are included as Table 2.
During the August 15, 2016, sampling event, only one constituent (i.e., acetone which is a common
laboratory contaminant) was detected in both summa canister headspace gas samples. The Henry’s Law
calculations included on Table 1 predict that potential groundwater impacts from landfill gas as detected in
the gas sample from MMW-8 would not produce the current detections of VOCs found in MW-28. It should
also be noted that PCE and TCFM were not detected in the summa canister sample collected from MMW-8,
Jaclynne Drummond, Compliance Hydrogeologist September 23, 2016
Solid Waste Section, DWM, NCDEQ 2 Project No. 0636572016
g:\projects\rowan\0636572016\250 final reports\202 final 2016 response to comments (asd)\80-03_20160923.docx
further suggesting that landfill gas is the source of VOCs detected at MW-28. Based on the analysis of
results from summa canister samples collected from MMW-8 and MW-28, landfill gas does not appear to
be responsible for the detections of VOCs in MW-28, which supports conclusions in the June 10, 2016
Alternate Source Demonstration to Address Anomalous VOCs at MW-28 that the source of VOCs in
groundwater at MW-28 is not related to the landfill or landfill activities.
2.0 LEACHATE COMPLIANCE ORDER (JUNE 11, 2007)
On September 28, 2007, S&ME submitted an Acetone Assessment Report on behalf Rowan County in
response to an acetone detection that was confirmed in surface water monitoring point SW-3. This report
stated that the confirmed detection of acetone could have been from a possible leachate release caused
by an overflow from the leachate collection system, in which the leachate could have comingled with
stormwater and subsequently been released via the facility’s stormwater conveyance features.
In response, S&ME was contracted by the County to evaluate the area of the potential release. During this
investigation, S&ME collected several soil samples for laboratory analysis of NC Appendix I metals and
VOCs, installed two piezometers which were used to obtain groundwater samples for laboratory analysis
of NC Appendix I metals and VOCs, and continued to monitor the surface water at the facility. The
conclusion of this report was that “the results of the soil and groundwater sampling do not appear to indicate
that a leachate release has impacted soil and groundwater at the sampling locations.”
In response to comments issued by NCDEQ in October 2007, S&ME prepared a response on behalf of the
County which was subsequently submitted under the title Acetone Assessment Report Addendum in
January 2008. NCDEQ’s comments included the request for additional soil sampling along with additional
information related to field instrumentation, laboratory methods, and reporting limits, variability of metals in
soils and an evaluation of a possible source of low levels of gasoline constituents detected in soil and
groundwater samples. The conclusions of this report were that “soil and groundwater sampling results
performed to date to not indicate a release of leachate in the area investigated and that no further
assessment is warranted.”
VOC impacts to soil or groundwater discovered during the 2007 investigation were minimal and none could
be linked directly to a leachate release, therefore, this does not appear to be a likely source of VOCs at
MW-28. This is further substantiated by the data presented in Alternate Source Demonstration to Address
Anomalous VOCs at MW-28, which indicate that landfill leachate is not the source of VOCs at MW-28.
3.0 LOCATION OF LEACHATE SYSTEM COMPONENTS
The leachate collection system force main locations are shown on the attached Drawing 1. These are the
closest points of the leachate collection system relative to monitoring well MW-28. According to the
available engineering documentation and information provided by HDR, the leachate collection system
force mains from Phases 1, 2, 3, and 4 were designed and constructed with double containment. Therefore,
it is not likely that this system is actively leaking. Also, based on the location of MW-28 with respect to the
leachate collection system force mains, in the unlikely event of a release, the direction of groundwater flow
is sidegradient between the potential release area and MW-28. Therefore, because the leachate system
components have dual containment and are generally sidegradient with respect to MW-28, leachate from
the containment system is not a likely source of VOCs at MW-28. This is further substantiated by the data
presented in Alternate Source Demonstration to Address Anomalous VOCs at MW-28, which indicate that
landfill leachate is not the source of VOCs at MW-28.
4.0 CLOSING
After further evaluation, as requested by NCDEQ in the June 30, 2016, comment letter, it does not appear
that the source of groundwater contamination in MW-28 is related to a release from the Rowan County
Table 1
September 2016 1 of 1 Project No. 0636572016
MW-28 MMW-8 MW-28 MMW-8 MW-28 Influenced by
MMW-8 MW-28
1,2-Dichloroethane 0.93 ND 98.95 25 101.325 4.04E-03 0.004 --4.01E-02 0.09 --ND 0.4 1
2,2,4-Trimethylpentane ND 300 114.23 25 101.325 4.67E-03 --1.401 7.33E-03 --191 ND ----
2-Butanone 22 ND 72.11 25 101.325 2.95E-03 0.065 --1.94E-03 33.5 --ND 4000 100
2-Propanol 11 ND 60.10 25 101.325 2.46E-03 0.027 --2.18E+01 0.00 --ND ----
Acetone 62 430 58.08 25 101.325 2.37E-03 0.147 1.021 1.59E-03 92.6 642 ND 6000 100
Carbon Disulfide 1.8 ND 76.14 25 101.325 3.11E-03 0.006 --1.24E+00 0.005 --ND 700 100
Cyclohexane ND 360 84.16 25 101.325 3.44E-03 --1.238 1.54E-01 --8.04 ND ----
Dichlorodifluoromethane ND 110 120.91 25 101.325 4.94E-03 --0.544 8.55E-03 --64 ND 1000 5
Ethyl Acetate 7.8 ND 88.11 25 101.325 3.60E-03 0.028 --1.59E+02 0.000177 --ND ----
Freon 114 ND 24 170.92 25 101.325 6.99E-03 --0.168 2.03E-02 --8.27 ND ----
Heptane ND 160 100.20 25 101.325 4.10E-03 --0.655 2.93E-02 --22 ND ----
n-Hexane ND 240 86.18 25 101.325 3.52E-03 --0.845 2.44E-02 --35 ND ----
Tetrachloroethane 31 ND 165.82 25 101.325 6.78E-03 0.210 --7.54E-01 0.28 --2.8 0.7 1
Toluene 28 ND 92.14 25 101.325 3.77E-03 0.105 --2.72E-01 0.39 --ND 600 1
Vinyl Chloride ND 30 62.50 25 101.325 2.55E-03 --0.077 1.11E+00 --0.07 ND 0.03 1
Notes:
1) ug/L = micrograms per liter
2) Calculated groundwater concentrations based on headspace gas sample analyses from the October 2014 sampling event.
4) Henry's Law Constant = dimensionless value
5) ppbv = parts per billion by volume
6) -- = not calculated
7) Bold = calculated concentrations greater than 2L Groundwater Standard
8) ND = not detected
9) Shaded cells = identified as constituents of concern for the facility as discussed in text
10) ppb (v/v) = parts per billion on a volume by volume basis
11) NC 2L Standard = the North Carolina groundwater standards
12) SWSL = Solid Waste Section Limit
= Henry's Law constants coverted to dimensionless speciation from listed values obtained from "Compilation of Henry's Law Constants for Inorganic and Organic Species of Potential Importance in Environmental Chemistry" by Rolf Sander Version 3 (April 8, 1999).
TABLE 1
Calculated Groundwater Concentrations
Based on Analytical Results of Headspace Samples
Rowan County Landfill, Permit No. 80-03
Woodleaf, Rowan County, North Carolina
NC 2L Standard
(ug/L)SWSL (ug/L)
3) Values obtained from Table 2 - Summary of Non-Methane organic Compounds in Various Landfills in "A Review of the Literature Regarding Non-Methane and Volatile Organic Compounds In Municipal Solid Waste Landfill Gas" by Hamideh Soltani-Ahmadi and from the 1996, EPA, Soil
Screening User Guidance, EPA/540/r-96/018.
Observed Headspace Samples
(ppbv)Molecular
Weight
(g/mol)
Temperature
(°C)PARAMETER
Gas
Concentrations
(ug/L-gas)Henry's Law Constant
(Dimensionless)
Pressure
(1 atm = 101.325
kPA)
Gas
Concentrations
(ug/L-gas)
Calculated Water Concentrations
(ug/L)
Actual Water
Concentrations
(ug/L)ppbv to ug/L
conversion
G:\Projects\Rowan\0636572016\200 DRAFT Reports\202 DRAFT 2016 Response to Comments (ASD)\B_Tables\Henry Law Calculations.xlsx
Table 2
September 2016 1 of 1 Project No. 0636572016
MW-28 MW-28 MW-28 MW-28
Tetrachloroethene 2.8 165.83 25 101.325 1.48E+02 413.081 4.01E-02 16.56 31
Trichlorofluoromethane 0.66 137.37 25 101.325 1.78E+02 117.546 7.33E-03 0.86 ND
Notes:
1) ug/L = micrograms per liter
2) Calculated groundwater concentrations based on headspace gas sample analyses from the October 2014 sampling event.
4) Henry's Law Constant = dimensionless value
5) ppbv = parts per billion by volume
6) -- = not calculated
7) Bold = calculated concentrations greater than 2L Groundwater Standard
8) ND = not detected
9) Shaded cells = identified as constituents of concern for the facility as discussed in text
10) ppb (v/v) = parts per billion on a volume by volume basis
11) NC 2L Standard = the North Carolina groundwater standards
12) SWSL = Solid Waste Section Limit
= Henry's Law constants coverted to dimensionless speciation from listed values obtained from "Compilation of Henry's Law Constants for Inorganic and Organic Species of Potential Importance in Environmental Chemistry" by Rolf Sander Version 3 (April 8, 1999).
TABLE 2
Calculated Headspace Concentrations
Based on Analytical Results of Headspace Samples
Rowan County Landfill, Permit No. 80-03
Woodleaf, Rowan County, North Carolina
3) Values obtained from Table 2 - Summary of Non-Methane organic Compounds in Various Landfills in "A Review of the Literature Regarding Non-Methane and Volatile Organic Compounds In Municipal Solid Waste Landfill Gas" by Hamideh Soltani-Ahmadi and from the 1996, EPA, Soil Screening User
Guidance, EPA/540/r-96/018.
ug/L to ppbv conversion
Gas Concentrations
(ug/L-gas)Henry's Law Constant
(Dimensionless)
Calculated Soil Gas
Concentrations
(ppbv)
Actual Soil Gas
Concentrations (ppbv)PARAMETER
Groundwater Sample
Concentrations (ug/L)Molecular Weight
(g/mol)Temperature (°C)Pressure (1 atm
= 101.325 kPA)
G:\Projects\Rowan\0636572016\200 DRAFT Reports\202 DRAFT 2016 Response to Comments (ASD)\B_Tables\Henry Law Calculations.xlsx
Drawing 1
i2
i3
i1
660
650
670
680
690
700
700
690
680
670
660
650
640
640
OLD
LANDFILL
ENTRANCE
SCALE
HOUSE
PROPERTY
LINE
100-YEAR
FLOODPLAIN
EXISTING
SEDIMENT
BASIN
EXISTING
SEDIMENT
BASIN
EXISTING
SEDIMENT
BASIN
FUTURE
MSW LANDFILL
(PHASES IV &V)
FRENCH DRAIN
SAMPLE POINT
TO SW-1
(SEE NOTE 6)
MMW-6A
MMW-6
MMW-2A
MMW-1MMW-3MMW-4
MMW-CD
MMW-5A
710
710
706.46MW-9
704.62MW-16
681.45
MW-13
679.18
MW-12
SW-4
664.46MW-23A
683.50
MW-20
699.83MW-1
680.69MW-24R
663.86MW-6
SW-3
648.58MW-7
644.35MW-18R
644.71MW-19
706.20MW-17
SW-5
SW-2
MW-25
MW-26
MW-27A
MW-28
655.82
656.00
659.07
661.64
674.53MW-11
MW-27
671.10
EXISTING
SEDIMENT
BASIN
EXISTING
SEDIMENT
BASIN
MMW-5
MMW-2
MMW-8MMW-7
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
664.46MW-23
LEACHATE POND
CONSULTANT
DESIGN
PREPARED
REVIEW
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PHASE
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2016-02-02
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ROWAN COUNTY ACTIVE LANDFILLS
PERMIT NO.80-03
ROWAN COUNTY, NORTH CAROLINA
ROWAN COUNTY
GROUNDWATER CONTOUR MAP (JANUARY 12-14, 2016)
WITH LEACHATE COLLECTION FORCE MAIN LOCATIONS
0
FEET
250 500
SCALE
EXISTING TOPOGRAPHIC CONTOUR
FACILITY BOUNDARY
APPROXIMATE LIMITS OF WASTE
GROUNDWATER SURFACE CONTOURS
APPROXIMATE GROUNDWATER FLOW SEGMENT USED TO CALCULATE GRADIENT
LEACHATE COLLECTION SYSTEM FORCE MAINS
EXISTING GROUNDWATER MONITORING WELL WITH GROUNDWATER ELEVATION
PROPOSED GROUNDWATER MONITORING WELL
SURFACE WATER MONITORING POINT
COMPLIANCE METHANE MONITORING POINT
ASSESSMENT METHANE MONITORING POINT
NOT AVAILABLE
FRENCH DRAIN MONITORING POINT
LEGEND
NOTES
REFERENCES
i1i1
1.TOPOGRAPHIC CONTOUR INTERVAL = 2 FEET.
2.GROUNDWATER SURFACE CONTOUR INTERVAL = 10 FEET.
3.GROUNDWATER ELEVATIONS MEASURED ON JANUARY 12-14, 2016.
4.GROUNDWATER CONTOURS ARE BASED ON LINEAR INTERPOLATION BETWEEN AND
EXTRAPOLATION FROM KNOWN DATA, TOPOGRAPHIC CONTOURS, AND KNOWN FIELD CONDITIONS.
THEREFORE, GROUNDWATER CONTOURS MAY NOT REFLECT ACTUAL GROUNDWATER
CONDITIONS.
5.GROUNDWATER CONTOUR LINES SHOW THE WATER TABLE SHAPE AND ELEVATION. THESE
CONTOURS ARE INFERRED LINES FOLLOWING THE GROUNDWATER SURFACE AT A CONSTANT
ELEVATION ABOVE SEA LEVEL. THE GROUNDWATER FLOW DIRECTION IS GENERALLY
PERPENDICULAR TO THE GROUNDWATER SURFACE CONTOURS, SIMILAR TO THE RELATIONSHIP
BETWEEN SURFACE WATER FLOW AND TOPOGRAPHIC CONTOURS.
6.SURFACE WATER MONITORING POINT SW-1 IS APPROXIMATELY 550 FEET OFF THE MAPPING LIMITS
SHOWN AND IS COLLECTED FROM SECOND CREEK.
7.MONITORING WELLS MW-6 AND MW-27A ARE UTILIZED FOR WATER LEVEL MONITORING ONLY.
8.THE LOCATION OF THE FRENCH DRAIN MONITORING POINT IS APPROXIMATE.
650
1. OVERALL SITE BASE TOPOGRAPHY PROVIDED BY S&ME ENGINEERING, INC.
MW-25
NA
SW-4
MW-7648.58
SITE LOCATION MAP
1" = 10,000'
SITE LOCATION
PE C-2862
PG C-399
GOLDER ASSOCIATES NC, INC.
L L
Appendix A
GOLDER ASSOCIATES INC.
QUALITY ASSURANCE & QUALITY CONTROL
LABORATORY DATA REVIEW
Page 1 of 3
Project Name: Rowan County ASD Samples
Project Reference Number: 0636572016.100
Sampling Event Date: 8/02/2016
Review Date: 8/23/2016 Initials: WB
Report #: BZ03266, CZ10886
Person(s) performing the review are to initial each item on this form as acknowledgement
of data acceptance, or as acknowledgement of a review issue. In the case of the latter, a
brief explanation should follow the applicable item.
Golder Associates Inc. has reviewed the laboratory certificates of analysis, chain-of-custody
form, and laboratory provided sample group quality assurance and quality control data for the
above referenced sample group to identify potential bias or inaccuracy, in general accordance
with the following United States Environmental Protection Agency documents:
Region III Modifications to Functional Guidelines for Organic Data Review Multi-Media,
Multi-Concentration, September 1994;
Region III Modifications to the Laboratory Data Validation Functional Guidelines for
Evaluating Inorganic Analyses, April 1993; and
Laboratory Data Validation Functional Guidelines for Evaluating Inorganic Analyses,
July 1998.
ANALYTE LIST(S)
NC Appendix I VOCs
1.0 CHAIN OF CUSTODY (COC) REVIEW
WB COC was properly signed by all parties.
WB Correct project name and number are on the form.
WB Sample receipt condition at laboratory was acceptable.
WB Each sample and blank submitted for analysis appears in the report.
Notes:
2.0 SAMPLE HOLDING TIMES
WB Holding times for extraction and/or analysis were met for each analytical
Method (see lab manual for holding times).
GOLDER ASSOCIATES INC.
QUALITY ASSURANCE & QUALITY CONTROL
LABORATORY DATA REVIEW
Page 2 of 3
Notes:
3.0 LABORATORY QUALITY CONTROL REVIEW
WB Laboratory analyzed at least one internal blank for each method, where applicable.
WB Laboratory blank is interference-free.
WB Surrogate recoveries are provided for each analytical method, where applicable.
WB Surrogate recoveries for each method are within the acceptable limits (i.e., at least
50% of the surrogates were within range).
WB MS/MSD/LCS data results are provided for each analytical method.
WB MS/MSD/LCS recoveries for each method are within the acceptable limits (i.e., at least 1 of
the 3 were within range).
4.0 ANALYTE LISTS/METHODS
WB The proper number of constituents are present for each analyte list as identified above
(including detects where applicable).
WB Proper analytical methods were used for analysis.
Notes:
5.0 DATA REPORTING
WB All analytical reporting associated with the event was performed by the contracted lab.
WB Trip, field and/or equipment, and laboratory blank results have all been reported. All
detects for blanks are listed below by constituent. All laboratory method blanks, if any, have
been ‘flagged’ with a ‘B’ where detected in other samples as appropriate and a laboratory
narrative was provided. If the sample was flagged by the laboratory and is not within 5X of
the concentration in the blank (or 10X for commonly detected laboratory contaminants-
acetone, methylene chloride and phthalates), list below with explanation if flags should be
removed. If flags need to be added for samples, also list below.
WB It is clear from the laboratory report that samples have or have not been diluted during
analysis, and if the samples have been diluted, the result is reported as a multiple of the
dilution (e.g., a sample diluted 10x resulting in an analytical detection of 1.0 should be
GOLDER ASSOCIATES INC.
QUALITY ASSURANCE & QUALITY CONTROL
LABORATORY DATA REVIEW
Page 3 of 3
reported as 10). Those that have been diluted are listed below with the dilution factor.
For MW-8, method TO-15, DF = 58x
For MW-28 (HS), method TO-15, DF = 5.44x
WB The report provides the reporting limit for each constituent.
WB The results were reported at or below their proper reporting limits (e.g., MDLs, MRLs,
PQLs, etc.). Those that are not reported correctly are listed below (by constituent) with the
proper reporting limit listed beside them. State if the reporting limit error is due to dilutions.
WB No inorganic and organic constituents were reported above their respective NC 2L Drinking
Water Standards in wells, surface points, or field/equipment/trip blanks.
WB For sites with historical data, no inorganic and organic constituents were detected in a well
or surface water point at concentrations outside of their historical range (more than 5X
previous concentrations or first-time detections).
WB Other report issues/Communications with laboratory/etc.:
Notes:
Affected Samples: MMW-8
Sample was diluted due to the presence of high levels of non-target analytes
resulting in elevated reporting limits.
Analysis: TO-15
Affected Samples: MMW-8 (HS)
The continuing calibration verification standard exhibited high bias for 2,2,4-
Trimethylpentane; the associated sample results had positive results.
Analysis: TO-15
Affected Samples: MMW-8 (HS), MW-28 (HS)
The laboratory control standard for Trans-1-3-Dichloropropene was out of control
with high bias. Since the analyte in the associated samples were not detected, there
is no impact on data quality.
Analysis: TO-15
Affected Samples: MW-28
The continuing calibration verification standard exhibited high bias for 2,2,4-
Trimethylpentane, 1,4-Dioxane and Vinyl Acetate; the associated sample results are
ND (not detected) and there is no impact on data quality.
Analysis: TO-15
Affected Samples: MMW-8 (HS)
The continuing calibration verification standard exhibited high bias for 1,4-
Dioxane and Vinyl Acetate; the associated sample
results are ND (not detected) and there is no impact on data quality.