4112_CityofGreensboroWhiteStreetPhaseIII_ASD_DIN27388_20161028

Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
Prepared for:
City of Greensboro
401 Patton Street
Greensboro, North Carolina 27406
Prepared by:
S&ME, Inc.
8646 W Market Street, Suite 105
Greensboro, NC 27409
October 28, 2016
S&ME, Inc. | 8646 W Market St, Ste 105 | Greensboro, NC 27409 | p 336.288.7180 | f 336.288.8980 | www.smeinc.com
October 28, 2016
City of Greensboro
401 Patton Street
Greensboro, North Carolina 27406
Attention:Mr. Richard Lovett
Reference:Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
Dear Mr. Lovett:
S&ME, Inc. (S&ME) has prepared this Alternate Source Demonstration for White Street Landfill, Phase 3, in
accordance with Task Order #3 dated August 25, 2016. This assessment was conducted in response to the
August 8, 2016, letter from the North Carolina Department of Environmental Quality, Division of Waste
Management, Solid Waste Section (NCDEQ-SWS) to the City of Greensboro requiring that facility owner
or operator perform one of two actions in response to reported 15A NCAC 2L Standard Exceedances for
Appendix I inorganics. The City of Greensboro elected to pursue the option to “demonstrate that a source
other than the MSWLF unit caused the exceedance, or the exceedance resulted from an error in sampling,
analysis, statistical evaluation, or natural variation in groundwater quality.” This report documents the
findings for our assessment of the natural occurrence of certain metals at Phase 3 of the Facility. A copy
of this report should be provided to the NCDEQ-SWS and one placed in the operating record.
Sincerely,
S&ME, Inc.
Lyndal Butler Edmund Q.B. Henriques
Environmental Scientist Project Manager / Senior Geologist
NC Geologist License No. 1216
Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
October 28, 2016 ii
Table of Contents
1.0 Introduction............................................................................................................1
2.0 Geology & Hydrogeology....................................................................................2
2.1 Site Geology.......................................................................................................................2
2.2 Soil Description.................................................................................................................2
2.3 Groundwater Hydrogeology..........................................................................................3
3.0 Data Collection ......................................................................................................4
3.1 Soil Sampling.....................................................................................................................5
3.2 Groundwater Sampling...................................................................................................5
4.0 Results......................................................................................................................5
4.1 Soil Sample Analytical Results .......................................................................................5
4.2 Probable Natural Groundwater Concentration Computations.................................6
4.3 Groundwater Analytical Results....................................................................................6
4.4 Time vs Concentration Graphs.......................................................................................7
5.0 Conclusions ............................................................................................................8
6.0 Limitations..............................................................................................................8
7.0 References...............................................................................................................9
List of Figures
Figure 1 – Site Plan
Figure 2 – ASD Sample Location Plan
List of Tables
Table 1 – 3-Year Summary of Groundwater Analyses Results
Table 2 – Summary of Soil Sample Analyses Results
Table 3 – Summary of Groundwater Analyses Results
Appendices
Appendix I – Analytical Reports
Appendix II – Time vs Concentration Graphs
Appendix III – USGS NURE Diagram
Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
October 28, 2016 1
1.0 Introduction
The White Street Landfill is located at the eastern end of White Street in Greensboro, North Carolina. The
Facility includes three landfill Phases (Phase 1, Phase 2, and Phase 3) depicted on Figure 1. The City of
Greensboro (CITY) operates the lined Subtitle D landfill, referred to as Phase 3, under Solid Waste Permit
#41-12. Twelve wells (MW-15, MW-16, MW-17, MW-18, MW-19, MW-20, MW-21, MW-22, MW-23, MW-
24, MW-25, and MW-25D) comprise the groundwater monitoring system for Phase 3 of the landfill.
Monitoring wells MW-15 and MW-16 serve as background wells for Phase 3. For detection monitoring,
groundwater samples are collected from each monitoring well on a semi-annual basis and submitted for
laboratory analysis using the Appendix I list of volatile organic and inorganic constituents.
The letter from the North Carolina Department of Environmental Quality, Division of Waste Management,
Solid Waste Section (NCDEQ-SWS) to the CITY dated August 18, 2016, required that the CITY as owner
and operator of White Street Landfill perform one of two actions in response to reported 15A NCAC 2L
groundwater standard exceedances (2L Standards) for certain Appendix I inorganics at Phase 3
compliance monitoring wells. The CITY elected to pursue the option to “demonstrate that a source other
than the MSWLF unit caused the exceedance, or the exceedance resulted from an error in sampling,
analysis, statistical evaluation, or natural variation in groundwater quality.”
It is well-known that many inorganics occur naturally in groundwater. Consequently, the 2L Standards
contain a provision to exempt naturally occurring inorganic concentrations. Therefore, a direct
comparison of detected concentrations to the 2L Standards is not conclusive evidence of an exceedance.
Since naturally occurring inorganic constituents in soils at the Facility can influence inorganic constituent
concentrations detected in groundwater samples, this assessment was developed to examine the naturally
occurring concentrations of certain Appendix I metals in soils within and surrounding Phase 3. The
collected data would then be examine to assess if metals detected groundwater at the facility were
indicative of naturally occurring conditions, rather than a result of a release from the Facility. Considering
that the method used to develop an Alternate Source Demonstration (ASD) for certain metals occurring in
Phase 2 of the Facility was previously successful, a similar approach was used for Phase 3.
Prior to conducting this ASD, Phase 3 groundwater analytical results for the last three years were reviewed
for constituents and concentrations which exceed the 2L Standards or the NCDEQ Interim Maximum
Allowable Concentrations (IMACs) if no 2L Standards currently exists for these constituents. This review
revealed that one or more monitoring wells reported concentrations of antimony, cobalt, and vanadium
which exceeded the corresponding IMACs. No other Appendix I inorganics were reported with
concentrations greater than their respective 2L Standards or IMACs, during this time frame. Accordingly,
antimony, cobalt, and vanadium were recognized as Constituents Of Potential Concern (COPC) for this
ASD. No other Appendix I inorganics were evaluated as part of this ASD.Table 1 summarizes the Phase
3 groundwater analytical results for antimony, cobalt, and vanadium over the past three years.
This ASD assessment focused on two primary objectives:
Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
October 28, 2016 2
1.Assess naturally occurring concentrations of the COPCs in the residual soils within and up-
gradient of the Phase 3 landfill unit. Utilize the observed natural soil concentrations to predict
plausible naturally occurring groundwater concentrations.
2.Assess dissolved metals vs total metals in current groundwater samples obtained from the Phase
3 groundwater monitoring well network. Utilize this data to determine if suspended or colloidal
solids in groundwater samples might influence the reported total metals concentrations, which
are used to judge compliance with applicable groundwater standards.
The following section provide a summary of local soils, geology, and hydrogeology information. Relevant
background information is followed by a discussion of the ASD assessment methods employed, analytical
results, findings, and conclusions.
2.0 Geology & Hydrogeology
2.1 Site Geology
The Greensboro area of North Carolina lies in the center of the Piedmont Physiographic province of the
Appalachian Highlands. The Piedmont is comprised of five northeast southwest trending rock belts of
various metamorphic grades. Greensboro lies within the Carolina Slate Belt, a group of low rank meta
sedimentary rocks which were originally deposited in an off-shore island arc system. Various volcanic
rocks including tuffs, basalts, argillites, and others were deposited in a shallow marine environment. The
age of these rocks are believed to be PreCambrian to Paleozoic.
Numerous tectonic events have greatly deformed these rocks and a metamorphic imprint has taken place.
Additionally, several intrusive events have occurred which have resulted in the emplacement of granitic
plutons of Paleozoic age throughout the belt.
Locally, the landfill area is underlain by an assemblage of metamorphosed felsic intrusive rocks. The
depth of these rocks varies with topography, but is generally less than 30 feet. When partially weathered,
these subsurface materials are generally referred to as saprolite. Saprolite is a residual soil which retains
some of the original structural features of the parent rock. The demarcation between the soil and rock
materials is transitional, as the difference is one of consistency and degree of weathering between very
stiff soil and relatively soft rock.
2.2 Soil Description
According to the Soil Survey of Guilford County, the soil in the landfill area has been classified as Pits (Pt).
Pits are miscellaneous land types made up of areas where the original soil has been removed or altered
beyond recognition. In landfill areas the original soil has been removed and solid waste material has been
placed in alternating layers with original soils and other materials.
The soil survey indicates that the soils around the landfill include Wehadkee silt loams (Wh), Chewacla
sandy loams (Ch), Wilkes sandy loams (Wke), Madison sandy loams (MaE and MaD), Enon fine sandy
loams (EnC and EnB), Mecklenburg sandy clay loam (McC2), Mecklenburg-Urban land complex (MuB), and
Cecil-Urban land complex (CfB).
Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
October 28, 2016 3
2.3 Groundwater Hydrogeology
In the Piedmont region, groundwater occurs in two hydraulically interconnected zones. The upper zone,
or regolith, consists of an unconsolidated or semi-consolidated mixture of clay fragmental material
ranging in size from silt to sand boulders. The porosity of the regolith is generally on the order of 20 to
30 percent (Heath, 1984). Because of its high porosity, the regolith functions as a reservoir which slowly
feeds water downward into the bedrock. Water is introduced to the regolith by precipitation and stream
flow. Once in the regolith, groundwater moves between intergranular pore spaces.
This “water table” zone is controlled by climactic factors. Groundwater levels vary seasonally, declining
during the summer when atmospheric conditions favor evaporation and plants transpire large amounts of
water, and rising during the winter when plants are dormant.
Groundwater also occurs below the regolith, in the bedrock zone where it moves through sheet-like
openings formed along fractures. Fractures in bedrock are of two types: joints, which are fractures along
which there has been no differential movement, and faults, which are fractures along which the adjacent
rocks have undergone measurable differential movement. Groundwater in the bedrock zone is generally
more stable and less readily influenced by climactic conditions. The regolith and bedrock zones are
connected hydraulically.
Precipitation generally occurs in the form of rainfall, which is variable throughout the year. Depending on
factors such as ground saturation, ground cover, and slope, a portion of the precipitation forms runoff.
This natural runoff flows to areas of lower elevation where some of the runoff water infiltrates in the
unconsolidated material (i.e. soil) and some flows into local surface waters. The precipitation that does
not form runoff infiltrates through the unsaturated zone where it can merge with underlying aquifers,
providing aquifer recharge.
Most aquifer recharge in the study area takes place in inter-stream areas. In the case of Phase 3, the lined
landfill footprint area limits local aquifer recharge. In general, recharge from precipitation enters the
surficial aquifer through the porous regolith. It is believed that much of the recharge water moves
laterally through the regolith aquifer and discharges to nearby streams. Near surface groundwater flow
generally mimics surface topography, with groundwater moving from topographic highs to topographic
lows, with flow lines perpendicular to lines of equal elevation. North Buffalo Creek is the expected
dominant discharge area at this Facility.
The saprolite regolith and bedrock underlain the Facility could contain antimony, cobalt, and vanadium as
natural trace minerals. Dissolution of minerals in the bedrock and residual soils releases naturally
occurring constituents to the underlying groundwater. Dissolved concentrations of trace constituents can
vary widely based on their occurrence and distribution in the regolith and bedrock. In addition, many site
specific factors including but not limited to exact bedrock minerology, the solubility of constituents, and a
range of site specific geochemical conditions impact mobility and transport of metals. This preliminary
assessment did not attempt to define the vast array of complex site specific variables which could control
the natural occurrence of COPC in site groundwater.
Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
October 28, 2016 4
3.0 Data Collection
The US Environmental Protection Agency (EPA’s) developed guidance for predicting what soil
concentrations will not cause contamination to groundwater at levels that exceed applicable groundwater
cleanup levels. According to the EPA’s Soil Screening Guidance
1 “As contaminants in soil leach and move
through soil and groundwater, they are subjected to physical, chemical, and biological processes that tend
to reduce the eventual contaminant concentration at the receptor point” (i.e., groundwater monitoring
well). This reduction or attenuation in the concentration of parameters as they percolate through the soils
to a ground water aquifer is governed by a variety of processes, the sum of which, are referred to as a
Dilution/Attenuation Factor. The Dilution/Attenuation Factor (DAF) is defined as “the ratio of contaminant
concentration in soil leachate to the concentration in ground water at the receptor point. EPA chose a
default DAF of 20 to account for contaminant (parameter) dilution and attenuation during transport
through the saturated zone to a compliance point (i.e., a receptor well).
15A NCAC 02L .0411 “Establishing Maximum Soil Contaminant Concentrations” relied substantially upon
the EPA’s Soil Screening Guidance for the development of the published equation used to establish the
NCDEQ’s “Soil to Groundwater, Maximum Soil Contaminant Concentrations” (Soil-to Groundwater MSCCs)
for organic and inorganic constituents. This equation is used by the NCDEQ to predict a maximum
concentration of a given constituent in the soil that would not yield a resultant groundwater
concentration equal to or greater than the associated 15A NCAC 02L groundwater quality standard. As a
predictive tool, this equation was generally intended to be conservative (overly protective) of the
protection of groundwater quality.
For this ASD the equation was reworked to calculate predicted groundwater concentrations relying upon
site specific measured soil concentrations. The reworked equation is as follows:
GWC (mg/L) = soil concentration (mg/kg) ÷ [(20 x Kd) + 41 + (1.733 x 41 x HLC)}
Where:
GWC = predicted natural concentration of inorganic constituent in groundwater
Soil Concentration = to be measured with site-specific soil sample analytical data
Kd = soil/water partitioning coefficient for the inorganic constituent
HCL = Henry’s Law Constant for the inorganic constituent
Relying on this equation as a conservative tool for predicting plausible naturally occurring concentrations
of the COPC, this ASD included the collection of in-situ soils within the immediate vicinity of the affected
down-gradient compliance monitoring wells, as well as soil samples collected in the up-gradient and
presumed undisturbed portion around Phase 3. The collected soil samples were analyzed for the full
Appendix I metals list. The above equation was then used to calculate predicted natural concentrations of
the COPC at the landfill.
1 EPA’s Soil Screening Guidance: Technical Background Document, Second Edition, United States
Environmental Protection Agency, EPA/540/R95/128, May 1996
Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
October 28, 2016 5
To examine potential influences of suspended solids or colloids in groundwater samples, this ASD
included the collection of split groundwater samples from monitoring well locations. For each sample
pair, one sample was laboratory filtered and the other unfiltered prior to the analysis for Appendix I
metals. Analytical results for each sample pair were evaluated for probable inorganic constituent
contributions due to suspended solids in the groundwater sample (e.g. total constituent concentrations)
verse true dissolved concentrations for the monitored shallow groundwater.
3.1 Soil Sampling
Soil samples were collected at the Facility between September 26 - 28, 2016. Fifteen individual grab
samples were obtained. At each of the selected eleven Phase 3 groundwater monitoring wells, one
sample was collected within no more than fifty feet of the well. Four additional soil sample were collected
at random locations in the up-gradient region of Phase 3, judged to be relatively undisturbed. Historic
aerial photographs and other field observations were used to make these judgement calls. These grab
soil samples were collected using a properly decontaminated hand-auger, from depths generally ranging
from approximately 1-2 feet below the land surface. These sample depths were selected to reduce the
chance of obtaining soil samples which could have been influenced by anthropogenic activities. Each soil
sample was transferred by hand using disposable nitrile gloves from the hand auger bucket to laboratory-
provided containers. Following collection, the soil sample containers were placed in an ice-filled cooler,
stored, and transported by courier to ENCO Laboratories under proper chain-of-custody procedures. The
collected samples were analyzed for Appendix I metals.
Figure 2 depicts Phase 3 of the White Street Landfill and the soil sample locations. These fifteen soil
sample locations provide reasonable spatial coverage for this landfill unit, sufficient to quantify some of
the expected natural variations in constituents and concentrations present in the native soils.
3.2 Groundwater Sampling
During the routine semi-annual detection monitoring event completed in September 2016, the Phase 3
monitoring wells were sampled using the Facility’s low-flow sampling protocol. Split groundwater samples
were collected at monitoring wells: MW-16, MW-17, MW-18, MW-19, MW-20, MW-23, MW-24, and MW-25b
(see Figure 2). Each groundwater sample was transferred from the dedicated well pump tubing directly
into laboratory-provided containers. Following collection, the sample containers were placed in an ice-
filled cooler, stored, and the shipped by courier to ENCO Laboratories under proper chain-of-custody
procedures. The collected samples were analyzed for Appendix I metals. For each sampled location, one
split sample was filtered in the laboratory with a 45 micron filter prior to laboratory analysis, to represent total
“dissolved” metals in the sample. The other split sample was analyzed for total metals without field or
laboratory filtering, representing total metals present in the groundwater sample obtained (dissolved plus
suspended solids or colloidal solids).
4.0 Results
4.1 Soil Sample Analytical Results
Table 2 summarizes the analytical results for the soil samples collected. Each of the COPC were detected
in each soil sample.Table 2 also includes some basic statistics for each COPC such as maximum detected
Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
October 28, 2016 6
concentration, minimum detected concentration, mean concentration, and standard deviation. The
standard deviation statistic was particularly valuable since it illustrates the magnitudes of reported
concentrations of the COPC; which were expected to vary based on anticipated spatial variations in the
underlying parent bedrock mineralogy.
The complete Laboratory Analytical Report of the soil sampling results in included in Attachment 1. The
soil sample results were used in the computation discussed in section 4.2.
4.2 Probable Natural Groundwater Concentration Computations
Table 2 includes predicted groundwater concentrations for each COPC using the site-specific soil sample
concentrations. The ASD predicted natural groundwater concentrations were calculated using the
minimum, maximum, and mean soil concentration for each COPC.Table 2 includes the corresponding
IMAC concentrations for each COPC. The predicted natural groundwater concentrations calculated
utilizing the mean soil concentration for each COPC were greater than corresponding IMAC
concentrations. This finding suggests that the COPCs could naturally occur at concentrations greater than
the corresponding published IMACs. Furthermore, groundwater concentrations observed for the COPC
over the last three years (see Table 1) were within the range of natural groundwater concentrations
predicted utilizing this equation.
Table 2 presents the HLC and Kd values used in the performance of the underlying calculations. It is
important to note that generic Kd values for inorganic constituents can vary. Therefore, when available
mean values for Kd were utilized in the computations. Furthermore, this equation is sensitive to variations
in Kd values; therefore, the resultant predicted natural groundwater COPC concentrations should be
consider as plausible values rather than as absolute or ceiling values. Other lines of evidence were
considered to assess if these predicted concentrations were realistic.
4.3 Groundwater Analytical Results
The analytical results for the filtered vs unfiltered groundwater sample pairs obtained were compared to
aid in assessing the potential for suspended solids or colloids in the groundwater samples, introducing
bias to the conclusions reached regarding groundwater quality. Particularly if the IMAC exceedance might
be due to suspended solids or colloids in groundwater samples, and not representative of dissolved
metals in groundwater quality.Table 3 provides a summary of the groundwater analytical results for total
metals (unfiltered) and dissolved metals (filtered). The table also provides the field measured turbidity
values for comparison. As indicated in Table 3:
♦Antimony was not detected in the groundwater samples collected the monitoring wells.
♦Cobalt was detected in only one of nine monitoring wells sampled. The dissolved cobalt and total
cobalt concentrations reported were estimated values, which were relatively similar.
♦Vanadium was detected in four of nine monitoring wells sampled. Although the percent change
values associated with these paired results exhibit substantial percent change values, it is our
opinion that differences between these very low concentrations were not significant for this
assessment.
♦Field turbidity values measured for the samples collected were relatively low, which suggests that
the low-flow sampling procedures utilized when sampling these wells yielded samples that exhibit
Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
October 28, 2016 7
relatively low turbidity. Groundwater samples with low turbidity typically yield samples with fewer
suspended or colloidal solids.
Based a comparison of the laboratory analyses for the total metals verses dissolved metals for the sample
pairs collected, and giving consideration to measured field turbidity values, the data collected indicates
that samples obtained from the monitoring wells did not contain suspended or colloidal solids at levels
sufficient to significantly influence the reported total metal concentrations. From this finding we can
conclude that suspended or colloidal solids were not the likely cause for the prior reported exceedances
of the 2L Standards for antimony, cobalt, and vanadium in Phase 3, assuming that the prior samples
exhibited similar turbidity values. Thus the current and the prior groundwater samples collected using
low-flow sampling methods should be considered representative of the monitored units.
4.4 Time vs Concentration Graphs
Time vs concentration graphs for historic concentrations of antimony, cobalt, and vanadium in
groundwater were reviewed for indications of the natural occurrence of metals in groundwater vs
indications of a release from the monitored unit. These graphs are contained in Appendix II.
The historic groundwater monitoring data set for Phase 3 predates the unit’s receiving of waste, therefore,
the data set could provide evidence of the natural background concentrations. Unfortunately, historic
analytical method reporting limits were higher than they are today, which hindered an evaluation of pre-
waste disposal naturally occurring metals concentrations, particularly so for constituents present at
relatively low concentrations. The graphs depict both detected concentrations and the changes in the
method reporting limits over time. These time vs concentration graphs do not provide evidence of
increasing concentrations of antimony, cobalt, or vanadium over time at the Phase 3 monitoring wells.
Despite some of the limitations associated with the data set, the absence of trends of rising
concentrations over time provides an additional line of evidence for the natural occurrence of antimony,
cobalt, and vanadium in groundwater associated with Phase 3.
It is noteworthy that:
♦Antimony has been detected in groundwater at background monitoring well MW-15. The
concentrations detected at monitoring well MW-15 were generally similar to those detected at
other Phase 3 compliance monitoring wells.
♦According to the United State Geologic Survey (USGS) National Uranium Resource Evaluation
(NURE) program database, Guilford County, North Carolina was found to have elevated vanadium
concentrations in wells sampled 1976-1979. Based on USGS NURE database North Carolina
diagram, contained in Appendix III, many of the Guilford County wells sampled were reported to
contain vanadium concentrations greater than 1 part per billion (or 1 µg/L), with some wells
reported to contain greater than 10 parts per billion vanadium. These assumed natural
concentrations are generally consistent with the vanadium groundwater concentrations observed
in Phase 3.
Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
October 28, 2016 8
5.0 Conclusions
For this ASD, natural groundwater concentrations for each COPC were predicted using the site-specific
soil concentrations. The NCDEQ utilizes an equation to predict a maximum concentration of a given
constituent in the soil that would not yield a resultant groundwater concentration equal to or greater than
the associated 2L Standard. This equation was modified for this ASD to calculate predicted site-specific
groundwater concentrations relying upon site-specific measured soil concentrations. The predicted
natural groundwater concentrations for Phase 3 calculated utilizing the mean soil concentration for each
COPC were greater than corresponding IMAC concentrations. This finding suggests that the COPCs could
naturally occur at concentrations greater than the corresponding published IMACs. Furthermore,
groundwater concentrations observed for the COPC over the last three years were within the range of
natural groundwater concentrations predicted utilizing this equation. Based on this finding, the prior
detections of antimony, cobalt, and vanadium at concentrations greater than their corresponding IMACs
were not due to a release by landfill Phase 3, but instead can be reasonably attributed to the natural
occurrence of these metals in the native, residual soil.
As additional lines of evidence to support this finding:
♦A review of time vs concentration graphs for each COPC provide no evidence of increasing
groundwater concentrations over time at the Phase 3 monitoring wells. This finding was
consistent with natural concentrations predicted using a modified version of an NCDEQ equation.
♦Antimony has been detected in groundwater at background monitoring well MW-15 at
concentrations generally similar to those detected at other Phase 3 compliance monitoring wells.
♦The USGS NURE database indicated that many Guilford County, North Carolina wells contained
vanadium concentrations greater than 1 part per billion, with some wells reported to contain
greater than 10 parts per billion. These assumed natural groundwater concentrations were
generally consistent with the vanadium concentrations observed in Phase 3 monitoring wells.
A comparison of the laboratory analyses for the total metals verses dissolved metals for the sample pairs
collected indicated that the groundwater samples did not contain suspended or colloidal solids at levels
sufficient to significantly influence the reported total metal concentrations. Therefore, suspended or
colloidal solids were not the likely cause for the prior apparent exceedances of the 2L Standards.
6.0 Limitations
This ASD was conduct to initiate an assessment of the potential natural occurrence of antimony, cobalt,
and vanadium in shallow groundwater at Phase 3. For a larger scale site like Phase 3, underlain by a
complex metamorphic bedrock unit, the distribution of metals in residual soil can vary spatial due to their
natural heterogeneous distributions. This condition can make the use a single background monitoring
well, impractical as a definitive tool to define naturally occurring metals concentrations in groundwater.
Similarly, a heterogeneous distribution of metals in residual soils and bedrock make it impractical to
establish absolute background concentrations of certain metals, present or likely present. Therefore, this
assessment has established probable natural concentrations for certain metals in groundwater. Review of
this ASD by the NCDEQ-SWS is required to confirm if the regulatory requirements for this matter have
been met.
Alternate Source Demonstration
White Street Landfill - Phase 3
Greensboro, North Carolina
S&ME Project No. 1584-98-081C
October 28, 2016 9
7.0 References
Soil Screening Guidance: Technical Background Document, Second Edition, May 1996, United States
Environmental Protection Agency (EPA), EPA/540/R95/128, OSWER-9355.4-17A.
Geologic Map of North Carolina, 1985. North Carolina Geologic Survey, North Carolina Department of
Natural Resources and Community Development
USGS National Uranium Resource Evaluation Program Database, http://mrdata.usgs.gov/nure/water/.
Accessed April 15, 2015.
Date NCAC 2L NCDEQ
Analyte Sample MW-15 MW-16 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-25b Standard IMAC
Collected (µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(ug/L)
13 Antimony 4/23/2014 0.942 J 1.63 J 0.428 J 0.346 J 0.489 J 0.220 J <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 ns 1
10/1/2014 0.565 J 1.25 J 0.278 J <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 dry well <0.220 ns 1
4/13/2015 <0.220 0.552 J <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 dry well <0.220 ns 1
10/6/2015 <0.220 2.25 J <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 ns 1
4/18/2016 0.307 J <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 dry well <0.220 ns 1
9/28/2016 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 dry well <0.220 ns 1
53 Cobalt 4/23/2014 <1.10 1.89 J <1.10 1.30 J <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 ns 1
10/1/2014 <1.10 1.26 J <1.10 4.15 J 1.58 J <1.10 <1.10 <1.10 <1.10 3.72 J dry well <1.10 ns 1
4/13/2015 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 5.20 J dry well <1.10 ns 1
10/6/2015 <1.10 <1.10 <1.10 1.13 J 1.32 J <1.10 <1.10 <1.10 <1.10 4.09 J <1.10 <1.10 ns 1
4/18/2016 <1.10 2.01 J <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 6.24 J dry well <1.10 ns 1
9/28/2016 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 <1.10 4.40 J dry well <1.10 ns 1
209 Vanadium 4/23/2014 <1.40 <1.40 1.82 J 4.06 J 4.43 J 5.36 J <1.40 <1.40 <1.40 1.50 J <1.40 2.56 J ns 0.3
10/1/2014 <1.40 2.06 J <1.40 2.06 J 4.99 J 3.92 J <1.40 <1.40 <1.40 <1.40 dry well 2.88 J ns 0.3
4/13/2015 <1.40 2.54 J <1.40 <1.40 2.90 J 4.34 J <1.40 <1.40 <1.40 <1.40 dry well 1.94 J ns 0.3
10/6/2015 <1.40 5.38 J 2.56 J 2.47 J 7.70 J 3.60 J <1.40 <1.40 <1.40 <1.40 <1.40 3.58 J ns 0.3
4/18/2016 <1.40 <1.40 2.06 J <1.40 4.00 J 5.18 J <1.40 <1.40 2.59 J <1.40 dry well 3.21 J ns 0.3
9/28/2016 <1.40 <1.40 1.76 J <1.40 4.71 J 5.51 J <1.40 <1.40 1.59 J <1.40 dry well 3.11 J ns 0.3
µg/L = Concentrations reported in micrograms per liter (µg/L)
< = Concentrations is less than the method detection limit shown
J = Reported concentration is considered estimated
NCAC 2L Standards = 15A North Carolina Administrative Code 2L .0200, GW Quality Standards for Class GA groundwater. Concentrations in BOLD exceed the corresponding 2L Standard
NCDEQ IMAC = NCDEQ Interim Maximum Allowed Concentration. Concentrations in bold print exceed the corresponding IMAC value.
ns = no standard
Solid
Waste
Section
ID #
Sample Locations
ALTERNATE SOURCE DEMONSTATION - CONSTITUENTS OF POTENTIAL CONCERN
TABLE 1
3 YEAR SUMMARY OF GROUNDWATER ANALYSES RESULTS
PHASE 3 - PERMIT # 41-12
WHITE STREET LANDFILL
GREENSBORO, NORTH CAROLINA
S&ME PROJECT NO. 1584-98-081C
TABLE 2
SUMMARY OF SOIL SAMPLE ANALYSES RESULTS
AND CALCULATION OF PREDICTED GROUNDWATER CONCENTRATIONS
PHASE 3 - PERMIT # 41-12
WHITE STREET LANDFILL
GREENSBORO, NORTH CAROLINA
S&ME PROJECT NO. 1584-98-081C
Soil Sample ID Antimony
Data
Qualifier Cobalt
Data
Qualifier Vanadium
Data
Qualifier
(mg/kg)(mg/kg)(mg/kg)
MW-15 2.48 4.96 100
MW-16 4.76 5.63 51.2
MW-17 0.974 J 78.1 59.2
MW-18 0.954 J 2.76 35.5
MW-19 6.11 10.2 51.8
MW-20 1.24 8.49 39.2
MW-21 0.906 J 3.22 24.1
MW-22 0.960 J 8.40 27.0
MW-23 2.66 7.79 46.2
MW-24 5.74 9.86 117
MW-25 0.511 J 1.37 12.0
BG-1 3.15 JD 3.75 D 125 D
BG-2 1.21 J 2.99 57.9
BG-3 1.50 17.8 54.5
BG-4 0.673 J 2.17 30.1
Maximum 6.11 78.1 125
Minimum 0.511 1.37 12
Mean 2.38 14.53 56.9
Std. Deviation 3.69 37.36 65.9
Alternate Source Demonstration (ASD) Calculations
Kd 45 45 1000
HLC 1 0 0
Predicted Natural Groundwater
Concentration in mg/L (based on
minimum soil concentration)0.0005 0.0015 0.0006
Predicted Natural Groundwater
Concentration in mg/L (based on
maximum soil concentration)0.0063 0.0864 0.0062
Predicted Natural Groundwater
Concentration in mg/L (based on
mean soil concentration)0.0024 0.0161 0.0028
2L Standard or IMAC in mg/L 0.0010 0.0010 0.0003
mg/L = Milligram per liter mg/kg = micrograms per kilogram
J = concentration is estimated JD = concentration is estimated and based on sample dilution
ASD Calculation Formula:
Predicted groundwater conc. (mg/L) = [soil concentration (mg/kg)]÷ [(20 x Kd) + 4 + (1.7333 x 41 x HLC (amt. m3/mole))]
Note: 1.733 = conversion factor from organic matter to organic carbon (fom = 1.733 foc)
Kd = Soil/water partitioning coefficient (from published literature)
HCL = Henry's Law Constant (from published literature)
T:\Projects\1998\ENV\081C White Street Landfill (2014)\Alternate Source Demonstration_Phase 3\ASD Tables.xlsx
MDL SWSL NCAC 2L NCDENR Federal
MW-16 MW-17 MW-18 MW-19 MW-20 MW-23 MW-24 MW-25b Standard IMAC MCLs
4112-MW16 4112-MW17 4112-MW18 4112-MW19 4112-MW20 4112-MW23 4112-MW24 4112-MW26
09/28/16 09/28/16 09/28/16 09/28/16 09/28/16 09/28/16 09/28/16 09/28/16
(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)(µg/L)
13 Antimony (total)<0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 0.220 6 ns 1 6
Antimony (dissolved)<0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 0.220
% change 0%0%0%0%0%0%0%0%
53 Cobalt (total)<1.10 <1.10 <1.10 <1.10 <1.10 <1.10 4.40 J <1.10 1.10 10 ns 1 ns
Cobalt (dissolved)<1.10 <1.10 <1.10 <1.10 <1.10 <1.10 4.54 J <1.10 1.10
% change 0%0%0%0%0%0%-3%0%
209 Vanadium (total)<1.40 1.76 J <1.40 4.71 J 5.51 J 1.59 J <1.40 2.89 J 1.40 25 ns 0.3 ns
Vanadium (dissolved)<1.40 1.70 J <1.40 3.47 J 4.68 J <1.40 <1.40 3.11 J 1.40
% change 0%3%0%26%15%12%0%-8%
5.23 1.35 1.91 3.51 1.26 1.35 2.00 0.49 NS NS NS NS
µg/L = Concentrations reported in micrograms per liter (µg/L)
< = Concentrations is less than the method detection limit (MDL) shown
Shaded cells indicate parameter detected above the MDL
SWSL = North Carolina Solid Waste Section Limit
J = Concentration reported greater than the MDL but less than the SWSL, thus it is considered estimated
NCAC 2L Standards = 15A North Carolina Administrative Code 2L .0200, GW Quality Standards for Class GA groundwater. Concentrations in BOLD exceed the corresponding 2L Standard
NCDEQ IMAC = Interim Maximum Allowed Concentration, NCDEQ
Federal MCL = Maximum Concentration Levels, USEPA
ns = No Federal MCL listed, USEPA and/or no NCAC 2L standard Listed
Analyte (total) = Analyte result for total metal concentration with no field or laboratory filtering of the groundwater sample
Analyte (dissolved) = Analyte results for groundwater samples 0.45 micron filtered by the laboratory prior to analysis for total metals
% change = Percent change between total concentration and dissolved concentrations reported for each sample pair
S&ME PROJECT NO. 1584-98-081C
TOTAL METALS VS DISSOLVED METALS
Field Turbidity (NTUs)
TABLE 3
SUMMARY OF GROUNDWATER ANALYSES RESULTS
PHASE 3 - PERMIT # 41-12
WHITE STREET LANDFILL
GREENSBORO, NORTH CAROLINA
Solid
Waste
Section
ID #
Monitoring Well Locations
Appendix I Metals (Methods 6010B & 6010D)
Well ID
Sample ID
Date Collected
Analytes
T:\Projects\1998\ENV\081C White Street Landfill (2014)\Alternate Source Demonstration_Phase 3\ASD Tables.xlsx
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JOB NO.
SCALE:
DATE:
DRAWN BY:CHECKED BY:
FIGURE NO.
8646 WEST MARKET STREET, SUITE 105
GREENSBORO, NC. 27409
PH. 336-288-7180
FAX. [phone]
DRAWING PATH:
SITE PLAN
WHITE STREET LANDFILL
GREENSBORO, NORTH CAROLINA
AS SHOWN RDM EQBH
1584-98-081C OCTOBER 2016 1
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DATE:
DRAWN BY:CHECKED BY:
FIGURE NO.
8646 WEST MARKET STREET, SUITE 105
GREENSBORO, NC. 27409
PH. 336-288-7180
FAX. [phone]
DRAWING PATH:
ASD SAMPLE LOCATION PLAN
WHITE STREET LANDFILL - PHASE III
GREENSBORO, NORTH CAROLINA
AS SHOWN RDM EQBH
1584-98-081C OCTOBER 2016 2
0
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LEGENDMONITORING WELL AND WELL IDENTIFICATIONASD SOIL SAMPLE LOCATION AND SAMPLE IDENTIFICATION
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Appendices
Appendix I – Analytical Reports
Appendix II – Time vs Concentration Graphs
Appendix III – USGS NURE Diagram
Page 1 of 1
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