HomeMy WebLinkAbout9204_Sorrell_WQMonitoring_DIN25887_20160404NOVEMBER 2015
SEMI-ANNUAL MONITORING OF
GROUNDWATER AND SURFACE WATER
SORRELL LANDFILL
APEX, WAKE COUNTY, NORTH CAROLINA
(DWM Permit No. 92-04)
S&ME Project No. 1054-07-251
Prepared for:
Sorrell Grading Company
P.O. Box 100
Apex, North Carolina 27502
Prepared by:
3201 Spring Forest Road
Raleigh, North Carolina 27616
___________________________________________________________
Alexander R Culpepper, P.G.Samuel P. Watts, P.G.
Project Geologist Senior Project Manager
January 5, 2015
November 2015 Semi-Annual Monitoring S&ME Project No. 1054-07-251
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Table of Contents
Section Page
EXECUTIVE SUMMARY............................................................................................1
1.1 BACKGROUND ...................................................................................................................4
2.0 GENERAL PHYSIOGRAPHY ...........................................................................6
2.1 SITE TOPOGRAPHY...........................................................................................................6
2.2 REGIONAL GEOLOGY........................................................................................................6
2.3 SITE GEOLOGY AND HYDROGEOLOGY............................................................................7
2.4 GROUNDWATER TABLE ....................................................................................................7
2.5 HYDRAULIC GRADIENT AND GROUNDWATER FLOW VELOCITY CALCULATIONS...........8
2.6 SURFACE WATER ...........................................................................................................10
3.0 SAMPLING PROGRAM ....................................................................................11
4.0 FIELD PARAMETERS .......................................................................................12
4.1 SPECIFIC CONDUCTIVITY................................................................................................12
4.2 PH....................................................................................................................................12
4.3 TEMPERATURE................................................................................................................13
4.4 TURBIDITY .......................................................................................................................13
5.0 ANALYTICAL RESULTS .................................................................................14
5.1 GROUNDWATER..............................................................................................................14
5.2 SURFACE WATER ...........................................................................................................15
6.0 QUALITY CONTROL SAMPLES...................................................................16
7.0 STATISTICAL ANALYSIS ..............................................................................17
8.0 SUMMARY ............................................................................................................18
8.1 GROUNDWATER RESULTS..............................................................................................18
8.2 SURFACE WATER SAMPLES...........................................................................................19
9.0 RECOMMENDATIONS .....................................................................................20
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Table of Contents (Cont’d)
TABLES
TABLE 1:STATIC GROUNDWATER ELEVATIONS
TABLE 2:SUMMARY OF HYDRAULIC CONDUCTIVITY VALUES
TABLE 3:GROUNDWATER VELOCITY CALCULATIONS
TABLE 4:SUMMARY OF FIELD PARAMETERS
TABLE 5:DETECTED ANALYTES –APRIL 2015 SAMPLING EVENT
FIGURES
FIGURE 1:VICINITY MAP
FIGURE 2:GROUNDWATER POTENTIOMETRIC MAP
APPENDICES
APPENDIX I:LABORATORY REPORTS
APPENDIX II:HYDRAULIC GRADIENT /GROUNDWATER FLOW VELOCITY CALCULATIONS
APPENDIX III:SUMMARY TABLE OF ELECTRONIC DATA DELIVERABLE (EDD)
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EXECUTIVE SUMMARY
S&ME, Inc. (S&ME) was contracted by the Sorrell Grading Company and The Estate of
Mr. Clyde E. Sorrell, Senior, (Sorrell) to provide semi-annual groundwater and surface
water monitoring services at Sorrell Landfill located off of Smith Road (S.R 1303) near
Apex, North Carolina. This monitoring event was performed on April 30, 2015. These
services were performed in general accordance with the Water Quality Monitoring Plan
(WQMP) prepared in June 1996 by Trigon Engineering Consultants, Inc. as modified by
the request for additional sampling locations made by representatives of NCDENR-
DWM, and NCDENR’s Water Quality Monitoring Requirements Letter, dated April 29,
2003. The landfill is currently in an assessment monitoring program because of the
detection of contaminants in monitor well samples in excess of North Carolina
Groundwater Protection Standards. Services conducted by S&ME for the April 2015
sampling event were performed in general accordance with proposal no. P4258-07V,
dated April 25, 2007 and the S&ME’s memorandum Cost Estimate for 2015 Semi-Annual
Groundwater and Surface Water Sampling Events,dated February 16, 2015.
During the November 2015 monitoring event, one background well (MW-1R), one deep
and four shallow compliance wells (DW-1, MW-5, MW-6, MW-8 and MW-9), one off-
site assessment well (GP-9) and two surface water sampling locations (SW-1 and SW-2)
were sampled. Based on groundwater elevations measured during the November 2015
sampling event, the overall groundwater flow at the landfill is to the east-northeast at an
average velocity of 32.80 ft/yr. Deep well DW-1 was installed within the bedrock
aquifer, near MW-8 along the facility’s southern boundary, to delineate the vertical extent
of landfill contaminants that may be migrating from the landfill cell. However, a
comparison of groundwater elevations in DW-1 and MW-8 indicates that an upward
gradient continues to exist between the two water-bearing zones in the vicinity of these
wells. Due to the upward gradient in the vicinity of DW-1, contaminants are unlikely to
migrate downward. Current analytical data of groundwater quality at DW-1 supports this
assumption.
Groundwater and surface water samples were analyzed for constituents listed in 40 CFR
258, Appendix I Constituents for Detection Monitoring (Appendix I). In addition, the
ground water samples from monitor wells MW-8 and GP-9 were also analyzed for the
Appendix II List of Hazardous Inorganic and Organic Constituents (Appendix II) for
assessment monitoring. The laboratory analytical results for the groundwater samples
were compared to the maximum allowable concentrations promulgated in the State of
North Carolina groundwater standards as presented in 15A North Carolina
Administrative Code, Subchapter 2L (15A NCAC 2L), hereafter referred to as the 2L
Standards, NCDENR Solid Waste Section Limits (SWSLs) or the Solid Waste
Groundwater Protection Standards (GWP ST) established in accordance with the Solid
Waste Rules Section .1634(h). The surface water sample analytical results were
compared to the maximum allowable concentrations promulgated in the North Carolina
Surface Water Class C standards found in 15A NCAC 2B (2B Standards).
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From groundwater samples collected during the November 2015 sampling event, seven
constituents were detected at concentrations greater than their respective 2L Standards:
benzene (4.5 µg/L at MW-8), tetrachloroethene (42 µg/L at MW-8) trichloroethene (12
µg/L at MW-8), vinyl chloride (6.1 µg/L in MW-8), barium (105 µg/L in MW-8),
vanadium (6.64 µg/L in MW-6), and zinc (11.2 µg/L in MW-8).
During the November 2015 monitoring event only one Appendix II constituents
(dichlorodifluoromethane) was detected above the laboratory method detection limits
(MDLs) in the sample collected from MW-8. The detection was well below the NCAC
2L Standard of 1,000 µg/L and 40 µg/L, respectively. During the November 2015
monitoring event no additional semi volatile organic compounds (SVOCs) were detected
above the laboratory method detection limits (MDLs). The inorganic constituents,
barium, vanadium and zinc were detected above their MDLs in the sample from the
upstream (SW-1) surface water monitoring location. Barium, cobalt, and vanadium were
detected in the downstream (SW-2) surface water sample. All organic constituents were
detected at concentrations below their respective surface water quality standards (2B
Standards).
The frequency and number of metals detected at the site have declined since low-flow
sampling procedures were implemented in 1999. It is recommended that the use of low
flow sampling methods be continued and that monitoring for inorganics be limited to
Appendix I inorganic constituents (no cyanide or sulfide) at the facility’s monitor wells
and surface water monitoring points.
VOCs have been detected in samples collected from well MW-8 since the well was
installed in 2001. The consistent detection of VOCs at MW-8 indicates that a source or
sources of VOCs may be present at or near this well. Additional assessment of
surrounding properties was conducted in October 2008 to further evaluate the extent of
the groundwater plume in the area of MW-8. VOCs were detected above the 2L
Standards in the off-site groundwater assessment monitor wells in October 2008 and
subsequent monitoring events. An assessment of corrective measures and corrective
action should be performed to address the groundwater contamination in the area of MW-
8. In the meantime, it is recommended that groundwater monitoring at MW-8 continue to
monitor for Appendix II VOCs. Sampling of the off-site assessment wells in the vicinity
of MW-8 (GP-9 and /or GP-10) should continue to be included as part of the regular
compliance monitoring to monitor the extent, movement and concentration of off-site
groundwater contamination.
S&ME recommends that semi-annual assessment monitoring of groundwater and surface
water be continued at the Sorrell Landfill. Currently, six monitor wells and two surface
water locations are sampled at Sorrell Landfill to fulfill the monitoring requirements as
required by North Carolina Solid Waste Management Rule .1634.
It is our understanding that the Wake County Department of Environmental Services,
Water Quality Division regularly samples the potable wells on the adjacent properties to
the south of the landfill (Dye and Herndon properties) as a precautionary measure to
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protect the users of these potable wells. S&ME recommends the results of this sampling
event be provided to Wake County for consideration in deciding protective measures for
the potable wells and their users.
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1.0 INTRODUCTION
1.1 Background
S&ME, Inc. (S&ME) was contracted by the Sorrell Grading Company and The Estate of
Mr. Clyde E. Sorrell, Senior, (Sorrell) to provide groundwater and surface water
monitoring services at Sorrell Landfill located off of Smith Road (S.R 1303) near Apex,
North Carolina (Figure 1). The sampling for this monitoring event was completed on
November 30, 2015. The services were performed in accordance with the facility’s
revised Water Quality Monitoring Plan (WQMP) prepared in February 1996 by Trigon
Engineering Consultants, Inc. Section 4.0 of the WQMP outlined the sampling and
analysis plan (SAP) to be used to monitor groundwater and surface water in the vicinity
of the landfill. The landfill is currently in an assessment monitoring program because of
the detection of contaminants in monitor well samples at concentrations exceeding
groundwater standards.
In accordance with the approved WQMP, four baseline sampling events were performed
in May, June, July, and August 1999. During each of those sampling events,
groundwater samples were collected from two upgradient (background) wells (MW-1R
and MW-4), and three downgradient (compliance) wells (MW-5, MW-6, and MW-7). A
surface water sample was collected at one down-gradient surface water monitoring point
(SW-2). Groundwater and surface water samples collected during the four 1999
sampling events were analyzed for constituents listed in 40 CFR 258,Appendix I
Constituents for Detection Monitoring (Appendix I). The sample results and subsequent
statistical analyses performed for the 1999 sampling rounds constitute the baseline for the
semi-annual sampling events being conducted during the post-closure period. The
baseline sample results submitted to the North Carolina Department of Environment and
Natural Resources, Division of Waste Management (NCDENR-DWM) on April 9, 2001,
indicated that one or more constituents listed in Appendix I were detected at statistically
significant levels.
Based on the results of the baseline sampling events, assessment monitoring was
conducted at Sorrell Landfill during four subsequent sampling events (April 2001,
December 2001, April/May 2002, November 2002) for the constituents listed in 40 CFR
258,Appendix II List of Hazardous Inorganic and Organic Constituents (Appendix II) as
promulgated in Section .1634.
At the request of the DWM, beginning with the December 2001 sampling event and
continuing with the April/May 2002 and November 2002 events, S&ME also collected
groundwater samples from two new monitor wells and a leachate sampling point. The
two new monitor wells included one shallow well (MW-8) and one deep well (DW-1)
installed along the facility’s southern property boundary. Both wells are located
approximately between the southern edge of the landfill cell and the closest residential
well. Based on measured monitor well water elevations obtained during performance of
the 2001 and 2002 sampling events, and potentiometric mapping of the shallow aquifer, it
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appears that monitor wells DW-1 and MW-8 may be hydraulically upgradient of the
landfill. However, for the purposes of this report, wells MW-8 and DW-1 are reported as
compliance wells.
Following the November 2002 sampling event, S&ME recommended revising the
number of sampling locations, the sampling frequency, and the laboratory analysis
performed at each sampling location. In a letter dated April 23, 2003, the Section
approved these revisions. Based on the revised monitoring plan, one background well
(MW-1R), five compliance wells (DW-1, MW-5, MW-6, MW-7, and MW-8), and two
surface water locations (SW-1 and SW-2) were to be monitored. Subsequently, S&ME
determined that monitor well MW-7 was located either in or immediately adjacent to the
landfill wastes. Therefore, S&ME requested, on behalf of the owners, that the sampling
of MW-7 be suspended and that a new compliance well be installed in that area. In a
letter dated May 10, 2004, the Section concurred with that opinion. Monitor well MW-9
was installed on September 18, 2007 and has replaced MW-7 as the compliance well
along the northern portion of the landfill. Well MW-7 remains in place for measuring
water levels.
This report presents the methods used and the results of the sampling event conducted by
S&ME during the November 2015 sampling event at the facility which included the
sampling of one background well (MW-1R), one deep and four shallow compliance wells
(DW-1, MW-5, MW-6, MW-8 and MW-9), one off-site assessment well (GP-9) and two
surface water sampling locations (SW-1 and SW-2).
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2.0 GENERAL PHYSIOGRAPHY
Some of the general background information presented in this section has been compiled
from the Water Quality Monitoring Plan prepared in June 1996 by Trigon Engineering
Consultants, Inc.; from the Preliminary Explanatory Text for the 1985 Geologic Map of
North Carolina (1988) prepared by The North Carolina Geological Survey; and from
Geology of the Carolinas (1991) by Horton and Zullo. The information presented herein
has been modified for brevity and is intended to provide general background information,
particularly in regards to regional topography, geology, and hydrogeology.
2.1 Site Topography
The landfill site is located southeast of Apex, North Carolina in southwestern Wake
County (Figure 1). At its highest point, the landfill extends approximately 30 to 45 feet
in elevation above the surrounding natural ground surface. The natural ground surface
elevations at the site prior to construction of the landfill ranged from 400 to 460 feet
above Mean Sea Level (MSL). The current landfill cap surface slopes gently downward
to the southwest to an approximate elevation of 490 feet above MSL (Figure 2).
2.2 Regional Geology
The site is located in the eastern portion of the Piedmont physiographic province. In
Wake County, the land surface is evenly divided between flat to gently rolling inter-
stream areas and valleys. Soils and weathered rock typically extend downward to depths
up to 60 feet below ground surface (bgs). Outcrops of hard bedrock are rare and most are
confined to streambeds and excavations.
Bedrock at the site area has been characterized as part of the Carolina Slate Belt. The
Carolina Slate Belt in this portion of the county consists primarily of predominately low-
grade felsic metavolcanic and meta-epiclastic rocks, presumed to have originated from a
sub-aqueous, volcanic arc environment. Primary rock types include metamorphosed
argillites, mudstone, volcanic sandstone, and conglomerate. Approximately one-half
mile to the west, an unconformity identified as the Jonesboro Fault separates the Carolina
Slate Belt from Triassic claystone and siltstone sediments.
Cretaceous-age Coastal Plain sediments immediately overlie the basement rocks in the
southern and eastern portion of the site. Middendorf units include deposits of sand,
sandstone, and mudstone. Beds are laterally discontinuous with inter-fingering cross-
bedding common in the upper units.
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2.3 Site Geology and Hydrogeology
The site lies on the western edge of the Neuse River basin. Surface water run-off from
the site flows to the west into Middle Creek. Surface water then flows to the south and
east toward the confluence of Middle Creek and the Neuse River near Smithfield, NC.
The unconfined aquifer in western Wake County is typically present in the
unconsolidated subsurface residual soils to an approximate depth of 30 feet bgs,
depending on the topography. Shallow groundwater flow patterns in the vicinity of the
landfill have been evaluated through a series of shallow downgradient monitor wells
finished at depths ranging between approximately 14 to 27 feet bgs and approximately 45
feet bgs in an upgradient well (MW-1R). The depth to groundwater varies from just
below the ground surface in the downgradient wells located on the western side of the
landfill to approximately 34 feet bgs on the eastern (upgradient) side of the landfill at
MW-1R.
A nested well pair, one shallow well (MW-8) and one deep well (DW-1) is
approximately located between the edge of the landfill cell and the closest residential
wells installed along the facility’s southern property boundary line (Figure 2). The
shallow monitor well (MW-8) was installed into the overlying sandy silt and is believed
to monitor the same shallow unconfined aquifer monitored by the other wells previously
installed at the site. Monitor well DW-1 is the only well installed into the bedrock
aquifer at the site.
At the location of DW-1, the soil immediately beneath the ground surface was classified
as sandy silt and silt to a depth of approximately 54 feet bgs. Underlying the sandy silt
and silt is partially weathered metavolcanic and metasedimentary rock of various degrees
of weathering, extending to approximately 66 feet bgs, where more competent bedrock
was encountered. The underlying competent rock is bluish schist with quartz, muscovite,
biotite, and hornblende minerals, and was observed to a depth of 101 feet bgs, where the
deep boring was terminated.
During drilling activities, water-bearing fractures were observed in the bedrock at 78 feet
bgs and 99 feet bgs. Based on field estimates by S&ME, the water-bearing zone at 78
feet bgs produced approximately one gallon per minute (gpm) and the water-bearing zone
at 99 feet produced approximately six gpm.
2.4 Groundwater Table
Prior to sampling for this monitoring event, each well was examined for its general
integrity, including protection from surface water inflow, well identification tag, vented
cap, lock, and general well security. Each well was opened and the depth to the water in
the well was measured from a referenced mark on the top of the PVC well casing using
an electronic water level indicator. The water elevation at each well was calculated by
subtracting the depth measurement from the elevation of the referenced top of casing.
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Table 1 shows the depth to groundwater measurements and groundwater elevation
calculations for each of the monitor wells sampled during the November 2015 sampling
event and the groundwater elevation calculations at each of the methane monitor wells.
The shallow groundwater is defined in this report as the water-bearing zone located in the
soil regime beneath and in the vicinity of the landfill. The depth to the shallow
groundwater was measured in the background wells (MW-1R, MW-4) and in the
compliance wells (MW-5, MW-6, MW-7, MW-8 and MW-9) during the sampling event.
Depth to groundwater was also measured in the deep well DW-1. However, this well is
believed to monitor a separate water-bearing zone within the bedrock aquifer and is not
representative of the shallow groundwater. In addition to the depth-to-water
measurements taken at these groundwater monitor wells, depth-to-water measurements
were also taken at thirteen groundwater monitor wells (GP-7, GP-7D,GP-8, GP-9, GP-10,
GP-10D, GP-11, GP-12, GP-12D, GP-13, GP-14, GP-15 and GP-16) installed along the
southern boundary of the landfill that were used to assess groundwater contamination in
the vicinity of MW-8 and methane gas monitor wells to supplement the water elevation
data. A complete list of monitor wells and methane gas monitor wells with the associated
groundwater elevation calculation is presented on Table 1.
2.5 Hydraulic Gradient and Groundwater Flow Velocity Calculations
The well water elevations and our interpretation of the water table surface expressed as a
potentiometric map along with groundwater flow direction are shown on Figure 2.
Based upon the groundwater elevations in the vicinity of the landfill cell, groundwater in
this area is projected to flow north-northwest toward an unnamed tributary of Middle
Creek, which is consistent with previous groundwater data.
Hydraulic Gradient
The average horizontal hydraulic gradient was calculated from three point calculation
solutions using two well sets of groundwater elevation data measured during the
November 30, 2015 sampling event and by and applying the following equation
(Driscoll, 1986):
i = h1 - h2
L
Where:
i = Hydraulic gradient
h1 - h2 = Difference in hydraulic head (feet)
L = Distance along flow path (feet)
The three point calculation is used to estimate the hydraulic gradient perpendicular to a
groundwater potentiometric contour of equal elevation determined from high,
intermediate and low groundwater elevations at three monitor wells. The gradient
calculated perpendicular to the equal elevation contour plotted from the well set is
representative of a true gradient rather than the apparent gradient that is estimated from a
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two point gradient calculation. Based on the Driscoll gradient equation and using a third
groundwater elevation to plot the equal elevation contour, the distance L can be measured
between h1 and h2 perpendicular to the equal elevation contour to estimate the true
hydraulic gradient for the three groundwater elevation data points. The average
horizontal hydraulic gradient from two three point solutions using well sets MW-1R,
MW-9, and MW-4, and MW-8, MW-5 and MW-6 is estimated to be 0.026 ft/ft. The
hydraulic gradient calculations are included in Appendix II.
Groundwater Flow Velocity
An approximate average linear groundwater flow velocity (v) may be calculated by the
equation (Freeze and Cherry, 1979):
v = Ki
n
Where:
v = Average linear groundwater flow velocity [feet per day (ft/day)]
K = Hydraulic conductivity (ft/day)
i = Flow gradient as a ratio (ft/ft),
n = Effective soil porosity (percent)
Aquifer slug tests were previously performed in monitor wells MW-6, MW-7, MW-8,
MW-9 and DW-1 at the site by S&ME using rising and falling head test techniques. The
slug test data were used to estimate the hydraulic conductivity of the sediments in the
surficial aquifer intersected by the screened intervals of the monitor wells tested. The
aquifer test data were analyzed by the Bouwer and Rice Method. As summarized on
Table 2, the average hydraulic conductivity values previously measured at the site ranged
from 4.00x10
-4 centimeters per second (cm/sec) to 1.86x10
-4 cm/sec.
The groundwater flow velocity was calculated for the site using the average hydraulic
conductivity values measured at the site; the average hydraulic gradient of 0.026 ft/ft,
calculated from the three point calculation described above; and an effective porosity of
20%. Groundwater flow velocities calculated during the November 2015 sampling event
ranged from 26.90 feet per year (ft/yr) between monitor wells MW-8 and MW-5 to 39.98
ft/yr between monitor wells MW-1R and MW-9. Calculations performed using the
equation and input values above estimate the average groundwater flow velocity for the
site was approximately 32.80 ft/yr. The calculated hydraulic gradients and groundwater
flow velocities are presented in Table 3.
As previously discussed, monitor wells MW-8 and DW-1 were installed in December
2001 along the facility’s southern boundary based on hydrologic data available at the
time and the relative position of the landfill and the nearby potable wells. Monitor well
MW-8 was intended to serve as a point of compliance between the landfill and residential
wells installed adjacent to the site’s southern property boundary. However, as shown on
Figure 2, static water levels measured during the April 2015 sampling event indicate that
MW-8 may be located hydraulically upgradient of the landfill cell.
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DW-1 is the only well installed on site within a separate water-bearing zone contained
within the bedrock aquifer, and was installed to delineate the vertical extent of landfill
contaminants that may be migrating from the landfill cell. As shown on Table 1, the
groundwater elevation in DW-1 was observed to be 3.81 feet higher than the groundwater
elevation in MW-8 during the November 2015 sampling event. This difference in
groundwater elevations, representing hydraulic head, indicates that an upward gradient
exists between the two water-bearing zones in the vicinity of these two wells. This
upward flow component has been observed at these two wells since they were installed in
December 2001.
2.6 Surface Water
The site is located just south of an unnamed tributary that flows southwest into Middle
Creek. Middle Creek flows to the southeast, eventually emptying into the Neuse River
near Smithfield, North Carolina. The unnamed tributary is the only surface body to
receive surface water runoff from the landfill. S&ME selected two surface water
collection points along the unnamed tributary. One sample collection point (SW-1) is
located hydraulically upgradient from the landfill. The other sample collection point
(SW-2) is located hydraulically downgradient from the landfill. During the November
2015 sampling event surface water samples were collected from both sample locations.
Surface water sample collection points SW-1 and SW-2 are shown on Figure 2.
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3.0 SAMPLING PROGRAM
In accordance with 15A NCAC 13 B, § .1632, and the approved groundwater and surface
water SAP for the facility, the following sections describe the procedures used for the
collection of groundwater and surface water samples during the sampling event.
S&ME sampled surface water from the up-gradient and down-gradient collection points
along an unnamed tributary of Middle Creek (SW-1 and SW-2), one background well
(MW-1R), four shallow and one deep compliance wells (MW-5, MW-6, MW-8, MW-9
and DW-1) on November 30, 2015. One shallow off-site groundwater assessment well
(GP-9) was also sampled during the November 2015 sampling event. The monitor wells
at the landfill were sampled using a low-flow peristaltic pump equipped with
polyethylene tubing. Prior to sampling each of the wells, the groundwater was purged at
a rate of approximately 150 milliliters per minute until the turbidity was reduced to less
than 10 Nephelometric Turbidity Units (NTUs) where it was achievable. Stabilization of
the selected field parameters was defined as a variance of less than 10 percent in three
successive readings recorded two minutes apart. Monitor well MW-1R was sampled
with a polyethylene bailer due to an increased depth-to-water.
The surface water samples from the creek were collected using laboratory-supplied 1-liter
bottles dipped directly into the stream as collection devices. The water was then poured
into laboratory-prepared vials and bottles.
At the completion of sampling, S&ME delivered the samples to Environmental
Conservation (ENCO) Laboratories in Cary, North Carolina for analysis according to the
following:
•MW-1R, MW-5, MW-6, MW-8, MW-9, DW-1, SW-1, and SW-2 were analyzed
for constituents listed in Appendix I (40 CFR 258); and
•MW-8 and GP-9 were analyzed for constituents listed in Appendix II (40 CFR
258).
Laboratory analytical methods for Appendix I constituents included EPA Method
6010C/6020A (metals) and Method 8260B volatile organic compounds (VOCs).
Laboratory analytical methods for Appendix II constituents included the Appendix I
constituent list, plus Method 8270D (SVOCs), Method 7470A (mercury), Method 9014
(cyanide) and SM18 4500-S D (sulfide). The analytical results reported from this
sampling event are discussed in subsequent sections of this report.
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4.0 FIELD PARAMETERS
Specific conductivity, pH, temperature, dissolved oxygen, oxygen reduction potential and
turbidity were measured in the field during well purging prior to sample collection. The
normal sampling protocol includes purging the shallow monitor wells with a peristaltic
pump at a rate of approximately 150 milliliters per minute until the turbidity is reduced to
less than 10 NTUs and the selected field parameters stabilize. Field parameters recorded
just prior to collecting the groundwater samples are summarized in Table 4 and discussed
below.
4.1 Specific Conductivity
Specific conductivity (conductance) is a measurement of the ability of a solution to pass
an electrical current. Dissolved inorganic anions and cations such as chloride, nitrate,
sulfate, phosphate, sodium, calcium, aluminum, and iron increase the ability of water to
carry a current. Conductivity is therefore related to the amount of total dissolved solids
in the water. Waters percolating through a landfill cell typically become enriched with
dissolved solids, which are reflected by increased conductivity values. Typically,
specific conductivity measures the presence of common ions such as chloride and sulfate
that are not necessarily indicative of hazardous constituents.
During the November 2015 sampling event, the specific conductance measured in the
background well (MW-1R) was 0.025 milliSiemens per centimeter (mS/cm).
Measurements in the four shallow compliance wells (MW-5, MW-6, MW-8, and MW-9)
ranged from 0.031 mS/cm (MW-9) to 0.093 mS/cm (MW-5). The specific conductance
measured in the off-site monitoring well (GP-9) was recorded as 0.028 mS/cm. The
specific conductance measured in the deep compliance well (DW-1) was recorded as
0.064 mS/cm. The highest groundwater conductivity value (0.093 mS/cm) was measured
in well MW-5. In general, conductivity readings are within the typical range of values
that would be expected to occur in shallow groundwater flow under natural conditions in
the Eastern Piedmont region.
4.2 pH
The pH is a measurement of the hydrogen ion concentration. Values lower than pH=7
indicate increasingly acidic conditions and values higher than pH=7 indicate increasingly
alkaline conditions. The pH may strongly influence the activity of certain chemical
reactions and the solubility and mobility of metals.
The pH of the groundwater in the landfill wells was measured just prior to sample
collection. The pH reading in the background well (MW-1R) was measured as 4.21. The
pH measured in the four shallow compliance wells ranged from 3.98 (MW-8) to 5.11
(MW-5). The pH values are within the range that would be expected for shallow
groundwater conditions in the Eastern Piedmont region. The pH measured in the off-site
November 2015 Semi-Annual Monitoring S&ME Project No. 1054-07-251
Sorrell Landfill, Apex, North Carolina January 5, 2015
13
monitoring well (GP-9) was recorded as 4.09. The pH measured in the deep compliance
well (DW-1) was recorded as 5.42.
4.3 Temperature
Groundwater temperature collected from the background well was 14.82ºC (MW-1R).
Groundwater temperatures recorded from samples collected from four shallow
compliance wells ranged from 15.18ºC (MW-6) to 15.52 ºC (MW-5). Temperature
measured from the deep compliance well (DW-1) was 15.89 ºC. Temperature measured
from the off-site assessment well (GP-9) was 15.15 ºC. Where the aquifer is in close
proximity to the ground surface, groundwater temperatures may be closely related to
seasonal temperature variations and the presence or absence of vegetative ground cover.
Groundwater temperature directly affects the solubility of oxygen and other geochemical
constituents. The solubility of dissolved oxygen is temperature-dependent, with oxygen
being more soluble in cold water than in warm water.
Groundwater temperature also affects the metabolic rate of bacteria. Rates of
biodegradation almost double for every 10 ºC increase in temperature between 5 ºC and
25 ºC. Elevated temperatures may also be an indication of significant microbiological
activity.
4.4 Turbidity
Nephelometric turbidity was added to the list of field parameters for selected wells after
the May 1999 sampling event detected higher than expected concentrations of metals.
Because the samples collected from monitor wells MW-1R and MW-6 during the initial
baseline sampling event were turbid, it was suggested that suspended soil particles
present in the groundwater could have contributed to elevated concentrations of metals
reported by the laboratory. Therefore a turbidity value of 10 NTUs was established as a
goal to achieve while purging and prior to collection of samples. During the November
2015 sampling event, the target value of 10 NTUs was not achieved in monitor wells
MW-1R, MW-6, and MW-8. Groundwater turbidity recorded just prior to sample
collection in the four shallow compliance wells ranged from 4.0 NTUs (MW-9) to 12.2
NTUs (MW-6). The turbidity level measured in the deep compliance well (DW-1) was
recorded as 7.0 NTUs. The turbidity level measured in the off-site assessment well (GP-
9) was recorded as 10.7 NTUs.
November 2015 Semi-Annual Monitoring S&ME Project No. 1054-07-251
Sorrell Landfill, Apex, North Carolina January 5, 2015
14
5.0 ANALYTICAL RESULTS
S&ME sampled one upgradient (background) well; four shallow and one deep
downgradient (compliance) wells; two surface water samples; and one off-site
groundwater assessment well on November 30, 2015. The samples were analyzed by
ENCO Laboratories for constituents listed in Appendix I of 40 CFR 258. The
groundwater sample from compliance well MW-8 and the off-site assessment well GP-9
were additionally analyzed for Appendix II SVOCs, mercury, cyanide and sulfide.
Laboratory analytical methods included EPA Method 6010C/6020A (metals), Method
8260B (VOCs), Method 8270D (SVOCs), Method 7074A (mercury), Method 9014
(cyanide), and SM18 4500-S D (sulfide). The analytical results for the groundwater and
surface water samples collected and analyzed in November 2015 are detailed below. A
copy of the analytical laboratory report is provided in Appendix I.
5.1 Groundwater
Groundwater sample analytical results were compared to North Carolina groundwater
standards as presented in 15A North Carolina Administrative Code, Subchapter 2L (15A
NCAC 2L), hereafter referred to as the 2L Standards and the Solid Waste Groundwater
Protection Standards (GWPST) established in accordance with the Solid Waste Rules
Section .1634(h). The analytical results for the November 2015 sampling event are
summarized on Table 5.Appendix III includes a summary table of the electronic data
deliverable (EDD) of the analytical and field data for the November 2015 sampling event.
From groundwater samples collected during the November 2015 sampling event, seven
constituents were detected at or above the reporting limits established by the Solid Waste
Section (SWSLs). The SWSL has little regulatory significance, except that it is a
minimum reporting limit. For several constituents, the SWSL is greater than the
corresponding North Carolina Groundwater Protection Standard.
For the November 2015 sampling event, seven constituents were detected at
concentrations greater than their respective 2L Standards: benzene (4.5 µg/L at MW-8),
tetrachloroethene (42 µg/L at MW-8) trichloroethene (12 µg/L at MW-8), vinyl chloride
(6.1 µg/L in MW-8), barium (105 µg/L in MW-8), vanadium (6.64 µg/L in MW-6), and
zinc (11.2 µg/L in MW-8). It is important to note that the laboratory method detection
limit (MDL) for vinyl chloride is 0.32 µg/L which is greater than the 2L Standard of 0.03
µg/L. Therefore, vinyl chloride may have been present at concentrations above the 2L
Standard but reported below the MDL.
One constituent, cobalt (5.18 µg/L at MW-8, 8.87 µg/L at MW-9) was reported at a
concentration above the respective GWPST. The laboratory analytical results indicated
that the concentrations of cobalt reported in the groundwater samples collected from
monitor wells MW-1R, MW-6, MW-8, and MW-9 were below the laboratory reporting
November 2015 Semi-Annual Monitoring S&ME Project No. 1054-07-251
Sorrell Landfill, Apex, North Carolina January 5, 2015
15
limit. Constituents reported at concentrations below the reporting limit are flagged with a
“J” and are considered to be an estimate.
Appendix III includes a summary table of the electronic data deliverable (EDD) of the
analytical and field data for the November 2015 sampling event.
5.2 Surface Water
The surface water sample was compared to the North Carolina Class C surface water
standards as promulgated in 15A NCAC 2B (2B Standards). The surface water sample
results for the November 2015 sampling event are summarized in Table 5.
All organic constituents were detected at concentrations less than their respective surface
water quality standards (2B Standards).
The inorganic constituents, barium, vanadium and zinc, were detected above their MDLs
in the sample from the upstream (SW-1) surface water monitoring location during the
November 2015 monitoring event. Barium, cobalt, and vanadium were detected in the
downstream (SW-2) surface water sample location in November 2015. All inorganic
constituents detected in samples from SW-1 and SW-2 were reported with a “J”
laboratory qualifier indicating that the values are estimated concentrations below the
lowest calibration point. All organic constituents in surface water samples collected
during the November 2015 sampling event were detected at concentrations below their
respective 2B Standards.
November 2015 Semi-Annual Monitoring S&ME Project No. 1054-07-251
Sorrell Landfill, Apex, North Carolina January 5, 2015
16
6.0 QUALITY CONTROL SAMPLES
Quality control samples are required by the WQMP to demonstrate consistency of the
laboratory analytical processes and field sampling methods.
During the November 2015 sampling event, in addition to the groundwater sample
collected from monitor well MW-8 and identified as MW-8 on the chain-of-custody
(record sample), a blind duplicate sample was also collected from monitor well MW-8
(duplicate sample). As shown on Table 5, similar analytes were detected in the record
sample and the duplicate sample.
Additionally, to assess the efficacy of the field equipment decontamination procedures,
an equipment rinse sample was taken by dipping the probe of the decontaminated water
level meter into a laboratory supplied bottle of deionized water. The equipment blank
sample was analyzed for the full Appendix I analyte list. Copper (1.86 µg/L) was
detected above the laboratory method detection limit in the equipment blank sample.
Copper was reported with a “J” laboratory qualifier indicating that the values are
estimated concentrations below the lowest calibration point. The results of the quality
control sampling are presented with the analytical results in Appendix I of this report.
November 2015 Semi-Annual Monitoring S&ME Project No. 1054-07-251
Sorrell Landfill, Apex, North Carolina January 5, 2015
17
7.0 STATISTICAL ANALYSIS
Previous monitoring reports submitted to the Section for this facility have included a
statistical evaluation of groundwater monitoring data. Statistical analysis was performed
to determine whether or not a statistically significant increase (SSI) above statistically
computed Upper Limits calculated from the upgradient background data set had occurred.
For this sampling event, no statistical analysis was performed on the data.
November 2015 Semi-Annual Monitoring S&ME Project No. 1054-07-251
Sorrell Landfill, Apex, North Carolina January 5, 2015
18
8.0 SUMMARY
S&ME was contracted by Sorrell to provide groundwater and surface water monitoring
services at Sorrell Landfill located just off Smith Road (S.R. 1303) near Apex, North
Carolina. Groundwater samples were collected from one upgradient (background) well
(MW-1R), four shallow and one deep downgradient (compliance) wells (MW-5, MW-6,
MW-8, MW-9 and DW-1), and one off-site assessment well (GP-9). Surface water
samples were collected from the up-gradient and down-gradient surface water monitoring
points (SW-1 and SW-2).
The depth to the groundwater was measured in each monitor well and landfill methane
well located at the site. As shown on the potentiometric map (Figure 2), groundwater in
the vicinity of the landfill is projected to flow north-northwest toward an unnamed
tributary of Middle Creek. It should be noted that static water levels measured during the
November 2015 sampling event indicate that MW-8 may be located hydraulically
upgradient of the landfill cell. In addition, the groundwater elevation in DW-1 was
observed to be higher than the groundwater elevation in MW-8 during the November
2015 sampling event. This difference in groundwater elevations indicates that an upward
gradient exists between the two water-bearing zones in the vicinity of these two wells.
These findings are consistent with historical data.
Groundwater and surface water samples were analyzed by ENCO Laboratories for
constituents listed in Appendix I. The sample from monitor well MW-6 and off-site
assessment monitor well GP-9 were also analyzed for constituents listed in Appendix II.
Laboratory analytical methods included EPA Method 6010C/6020A (metals), Method
8260B (VOCs), Method 8270D (SVOCs), Method 7470A (Mercury), and Method 9014
(cyanide).
8.1 Groundwater Results
From groundwater samples collected during the November 2015 sampling event, seven
constituents were detected at concentrations greater than their respective 2L Standards:
benzene (4.5 µg/L at MW-8), tetrachloroethene (42 µg/L at MW-8) trichloroethene (12
µg/L at MW-8), vinyl chloride (6.1 µg/L in MW-8), barium (105 µg/L in MW-8),
vanadium (6.64 µg/L in MW-6), and zinc (11.2 µg/L in MW-8).
The detected analytes from the November 2015 sampling event are summarized on Table
5.
It is important to note that the laboratory method detection limit (MDL) for vinyl chloride
is 0.32 µg/L which is greater than the 2L Standard of 0.03 µg/L. Therefore, vinyl
chloride may have been present at concentrations above the 2L Standard but reported
below the MDL.
November 2015 Semi-Annual Monitoring S&ME Project No. 1054-07-251
Sorrell Landfill, Apex, North Carolina January 5, 2015
19
8.2 Surface Water Samples
The inorganic constituents, barium, vanadium and zinc, were detected above their MDLs
in the sample from the upstream (SW-1) surface water monitoring location during the
November 2015 monitoring event. Barium, cobalt, and vanadium were detected in the
downstream (SW-2) surface water sample location in November 2015. All inorganic
constituents detected in samples from SW-1 and SW-2 were reported with a “J”
laboratory qualifier indicating that the values are estimated concentrations below the
lowest calibration point. All organic constituents in surface water samples collected
during the November 2015 sampling event were detected at concentrations below their
respective 2B Standards.
November 2015 Semi-Annual Monitoring S&ME Project No. 1054-07-251
Sorrell Landfill, Apex, North Carolina January 5, 2015
20
9.0 RECOMMENDATIONS
As required by North Carolina Solid Waste Management Rule .1634, these results should
be forwarded to the owner/operator of Sorrell Landfill for inclusion in the operating
record and to the NCDENR Division of Waste Management for their review. In addition
to the conclusions presented in previous chapters of this report, S&ME provides the
following recommendations:
•Analytical data since 1999 have demonstrated that the use of low-flow sampling
techniques has successfully reduced reported inorganics in the samples to more
accurate results. Accordingly, it is recommended that monitoring for inorganics
continue to be limited to Appendix I inorganic compounds at the facility’s
monitor wells (no cyanide or sulfide).
•VOCs have been detected in samples collected from well MW-8 since the well
was installed in 2001. The consistent detection of VOCs at MW-8 indicates that a
source or sources of VOCs may be present at or near this well. Additional
assessment of surrounding properties was conducted in October 2008 to further
evaluate the extent of the groundwater plume in the area of MW-8. VOCs were
detected above the 2L Standards in the off-site groundwater assessment monitor
wells in October 2008 and subsequent monitoring events. To monitor the off-site
groundwater contamination, off-site assessment monitor well GP-9 was sampled
during the April 2015 sampling event. None of the VOCs detected in nearby
compliance well MW-8 were detected in off-site assessment monitor well GP-9
during the April 2015 sampling event. An assessment of corrective measures and
corrective action should be performed to address the groundwater contamination
in the area of MW-8. In the meantime, it is recommended that groundwater
monitoring at MW-8 continue to be analyzed for Appendix II VOCs and sampling
of the off-site assessment wells in the vicinity of MW-8 (GP-8, GP-9 and /or GP-
10) continue to be included as part of the regular compliance monitoring, to
monitor the extent, movement and concentration of off-site groundwater
contamination.
•Surface water quality is monitored upstream and downstream in the vicinity of the
landfill at sampling locations SW-1 and SW-2, respectively. Samples from
surface water sampling locations SW-1 and SW-2 should continue to be
monitored for the Appendix I organic and inorganic compounds required for
detection monitoring.
•It is our understanding that the Wake County Department of Environmental
Services, Water Quality Division regularly samples the potable wells on the
adjacent properties to the south of the landfill (Dye and Herndon properties) as a
precautionary measure to protect the users of these potable wells. S&ME
recommends the results of this sampling event be provided to Wake County for
consideration in deciding protective measures for the potable wells and their
users.
TABLES
TOC Elevation
(Feet MSL)
Screened Interval
(feet below TOC)
Depth to Groundwater
(Feet below TOC)
Groundwater Elevation
(Feet MSL)
MW-1R 482.92 25-45 29.64 453.28
MW-4 445.30 12-22 3.61 441.69
MW-5 393.63 7-17 3.43 390.20
MW-6 407.15 7-17 2.20 404.95
MW-7 423.42 13-28 13.25 410.17
MW-8 463.33 21.9-31.9 24.58 438.75
MW-9 425.82 14-34 16.03 409.79
DW-1 463.18 96-101 20.77 442.41
GP-7 471.32 25-35 22.48 448.84
GP-7D 471.33 55-65 22.78 448.55
GP-8 460.39 23-33 22.14 438.25
GP-9 462.19 20.1-30.1 21.90 440.29
GP-10 456.15 15-25 16.35 439.80
GP-10D 456.20 78-88 18.05 438.15
GP-11 461.77 23-33 19.65 442.12
GP-12 466.71 23-33 23.86 442.85
GP-12D 466.72 58-68 23.87 442.85
GP-13 453.70 20-30 14.93 438.77
GP-13D 453.56 59-69 13.95 439.61
GP-14 463.45 25-35 24.32 439.13
GP-15 454.32 18-28 14.53 439.79
GP-16 449.99 18-28 7.87 442.12
MMW-2 471.71 5-20 Dry Dry
MMW-3 452.50 3-18 14.02 438.48
MMW-4 445.60 3-13 8.41 437.19
MMW-5 437.81 3.5-13.5 Dry Dry
MMW-6 419.04 5-15 16.38 402.66
Notes:
1. TOC = Top of Casing
2. MSL = Mean Sea Level
NM = Not Measured
TOC Elevations measured by Bateman Civil Survey, June, 2007.
GP-7 - GP-16 installed by S&ME between September 5 & 11, 2008, casing elevations by Bateman Civil Survey, September 11, 2008.
Monitoring wells MW-4, MW-5, andMW-6 installed by Law Engineering in October 1991. All other wells were installed by S&ME.
MW-9 installed by S&ME on September 18, 2007, casing elevation by Bateman Civil Survey, October 5, 2007.
Off-site Groundwater
Monitoring Wells
Well Number
Background Wells
Compliance Wells
Methane Monitoring
Wells
Permanent Methane Monitoring Wells
Permanent Groundwater Monitoring Wells
Temporary Groundwater Monitoring Piezometers
Table 1
Static Groundwater Elevations
Semi-Annual Assessment Monitoring - November 30, 2015
Sorrell Landfill, Apex, North Carolina
S&ME Project No. 1054-07-251
cm/sec ft/sec ft/day ft/year
MW-1R 25 - 45'--------
MW-4 12 - 22'--------
MW-5 7.0 - 17'--------
MW-6 7.0 - 17'1.86E-04 6.07E-06 0.525 191.47
MW-7 13 - 28'3.25E-04 1.06E-05 0.917 334.59
MW-8 22 - 32'4.00E-04 1.31E-05 1.130 412.49
MW-9 14 - 34'3.86E-04 1.26E-05 1.090 397.85
DW-1 96 - 101'3.28E-04 1.07E-05 0.924 337.44
Notes:
1. ft-bgs = feet below ground surface
3. ft/sec = feet per second
4. ft/yr = feet per year
5. -- = no site specific hydraulic conductivity values available
6. Hydraulic conductivity for MW-6 and MW-7 obtained from slug tests by S&ME, April 1999.
7. Hydraulic conductivity for MW-8, MW-9 and DW-1 obtained from slug tests by S&ME, January/March 2008.
Screened Interval
(ft-bgs)
8. Hydraulic conductivity for DW-1 was calculated from transmissivity value using the Cooper-Bredehoeft-Papadopulos solution where K=T/b.
Well Number
Background
Wells
Compliance
Wells
Hydraulic Conductivity (K)
Table 2
Summary of Hydraulic Conductivity Values
Semi-Annual Assessment Monitoring - November 30, 2015
Sorrell Landfill, Apex, North Carolina
S&ME Project No. 1054-07-251
Gradient Calculation
Segment
Monitoring
Wells
Flow
Direction
Gradient Segment
Length (feet)
Gradient
Segment
Elevations
(feet)
Horizontal
Gradient
(i, feet)
Effective
Porosity
(ne)
Hydraulic
Conductivity
(K, cm/sec)
MW-1R to 453.28
MW-9 409.79
Intermediate
Well MW-4
441.69
MW-8 to 438.75
MW-5 390.20
Intermediate
Well MW-6
404.95
0.027 Avg. Velocity =34.22 feet/year
Notes:
Horizontal velocities based on the modified Darcy equation Vgw = Ki/ne.
1. Porosity (ne) estimated for residual soils in Carolina Slate Belt
2. Average K value used for background wells and compliance wells
3. Hydraulic Gradient (i) calculated by measuring linear feet between selected contour intervals
4. Ave. Linear Velocity (v) = (1.035E06)K*i/n for units shown
5. To convert cm/sec to ft/yr, multiply n by 1.035E06
Average Hydraulic Gradient=
1.86E-04
Table 3
Groundwater Velocity Calculations
Semi-Annual Assessment Monitoring - November 30, 2015
Sorrell Landfill, Apex, NC
0.2
i 1
i 2
0.2
S&ME project Number 1054-07-251
3.25E-04
WNW 0.0282
0.02591690
1695
NNW 43.31
27.04
Velocity
(Vgw, feet/year)
pH1 Conductivity (mS/cm)
2 Temperature (
oC)3 Turbidity (NTUs)
6
B a c k g r o u n d
W e l l s
MW-1R 4.21 0.025 14.82 94.3
MW-5 5.11 0.093 15.52 6.2
MW-6 5.03 0.064 15.18 12.2
MW-8 3.98 0.062 15.39 6.9
MW-9 4.11 0.031 15.28 4.0
DW-1 5.42 0.064 15.89 7.0
O f f -S i t e
A s s e s s m e n t
W e l l s
GP-9 4.09 0.028 15.15 10.7
SW-1 4.63 0.041 12.47 17.6
SW-2 4.63 0.041 12.47 17.6
Notes:
1. pH reported in standard units
2. mS/cm = miliSiemens per centimeter
3. °C = degrees Celsius
4. mg/L = milligrams per liter
5. mV = millivolts
6. NTUs = nephelometric turbidity units
S u r f a c e
W a t e r
C o m p l i a n c e
W e l l s
Table 4
Semi-Annual Assessment Monitoring - November 30, 2015
Sorrell Landfill, Apex, North Carolina
S&ME Project No. 1054-07-251
Summary of Field Parameters
Field Parameter
Well Number
MW-1R MW-5 MW-6 MW-8 MW-9 DW-1 GP-9 Equip. Blank Duplicate SW-1 SW-2
11/30/2015 11/30/2015 11/30/2015 11/30/2015 11/30/2015 11/30/2015 11/30/2015 4/30/2015 4/30/2015 11/30/2015 4/30/2015
1,1-dichloroethane 5 6 <0.13 <0.13 <0.13 1.4J <0.13 <0.13 <0.13 <0.13 1.3J 6,700 <0.13 <0.13
1,1-dichloroethane 0.52J 0.47J
1,2-dichloropropane 1 0.6 <0.10 <0.10 <0.10 0.54J <0.10 <0.10 <0.10 <0.10 0.67J 0.5 <0.10 <0.10
1,4-dichlorobenzene 1 6 <0.19 <0.19 <0.19 0.56J <0.19 <0.19 <0.19 <0.19 0.61J 63 <0.19 <0.19
Acetone 100 6000 <1.2 <1.2 <1.2 <1.2 <1.2 <1.2 <1.2 <1.2 240 2,000 <1.2 <1.2
Arsenic 10 10 <5.40 <5.40 <5.40 <5.4 <5.40 <5.40 <5.40 <5.40 5.46J 10 <5.40 <5.40
Benzene 1 1.0 <0.15 <0.15 <0.15 4.5 <0.15 <0.15 <0.15 <0.15 4.0 1.19 <0.15 <0.15
Chloroform 5 70.0 <0.18 <0.18 <0.18 <0.18 <0.18 <0.18 <0.18 <0.18 <0.18 5.6 <0.18 <0.18
Cis-1,2-dichloroethene 5 70.0 <0.15 <0.15 <0.15 14 <0.15 <0.15 <0.15 <0.15 11 330 <0.15 <0.15
Trans-1,2-dichloroethene 5 100 <0.21 <0.21 <0.21 0.53J <0.21 <0.21 <0.21 <0.21 0.41J 140 <0.21 <0.21
Carbon disulfide 100 700 <1.5 <1.5 <1.5 <1.5 <1.5 <1.5 <1.5 <1.5 <1.5 NE <1.5 <1.5
Tetrachloroethene 1 0.7 <0.17 <0.17 <0.17 42 <0.17 <0.17 <0.17 <0.17 44 0.7 <0.17 <0.17
Trichloroethene 1 3 <0.15 <0.15 <0.15 12 <0.15 <0.15 <0.15 <0.15 12.0 2.5 <0.15 <0.15
Trichlorofluoromethane 1 2000 <0.24 <0.24 <0.24 <0.24 <0.24 <0.24 <0.24 <0.24 <0.24 9,100 <0.24 <0.24
Vinyl chloride 1 0.03 <0.32 <0.32 <0.32 6.1 <0.32 <0.32 <0.32 <0.32 5.2 0.025 <0.32 <0.32
Xylenes (total)5 500 <0.45 <0.45 <0.45 2.9J <0.45 <0.45 <0.45 <0.45 2.9J 670 <0.45 <0.45
Methylene chloride 1 5 <0.23 <0.23 <0.23 4.2 <0.23 <0.23 <0.23 <0.23 3.8 4.6 <0.23 <0.23
MW-1R MW-5 MW-6 MW-8 MW-9 DW-1 GP-9 Equip. Blank Duplicate SW-1 SW-2
11/30/2015 11/30/2015 11/30/2015 11/30/2015 11/30/2015 11/30/2015 11/30/2015 4/30/2015 4/30/2015 11/30/2015 4/30/2015
Dichlorodifluoromethane 5 1000 NA NA NA 18 NA NA NA NA NA NE NA NA
3 & 4-Methylphenol 10 40 NA NA NA NA NA NA <0.16 NA NA NE NA NA
MW-1R MW-5 MW-6 MW-8 MW-9 DW-1 GP-9 Equip. Blank Duplicate SW-1 SW-2
11/30/2015 11/30/2015 11/30/2015 11/30/2015 11/30/2015 11/30/2015 11/30/2015 4/30/2015 4/30/2015 11/30/2015 4/30/2015
Arsenic 10 10 <5.40 <5.40 <5.40 <5.4 <5.40 <5.40 <5.40 <5.40 5.46J 10.0 <2.8 <2.8
Antimony 6 1*<0.220 <0.220 2.73J <0.220 <0.220 <0.220 <0.220 <0.220 <0.220 5.6 <0.220 <0.220
Barium 100 700 18.7JB 31.5JB 33.5JB 105 B 25.4JB 10.3J 10.9J <0.100 201 1,000 29.9J 71.9J
Beryllium 1 4*<0.100 <0.100 <0.100 0.174J <0.100 <0.100 <0.100 <0.100 0.209J 6.5 <0.100 <0.100
Chromium 10 10 1.43J <1.40 <1.40 <1.40 <1.40 <1.40 <1.40 <1.40 <1.40 50 <1.40 <1.40
Cobalt 10 1*<1.10 <1.10 <1.10 5.18J 8.77J <1.10 <1.10 1.86J 5.2J 3 <1.10 1.24J
Copper 10 1000 4.02J <1.60 <1.60 <1.60 <1.60 <1.60 <1.60 <1.60 <1.60 7 AL <1.60 <1.60
Lead 10 15 6.06J <2.10 <2.10 <2.10 <2.10 <2.10 <2.10 <2.10 <2.10 25 N <2.10 <2.10
Nickel 50 100 <1.80 <1.80 <1.80 <1.80 <1.80 <1.80 <1.80 <1.80 <1.80 25 <1.80 <1.80
Silver 10 20 <1.90 <1.90 <1.90 <1.90 <1.90 <1.90 <1.90 <1.90 <1.90 0.06 AL <1.90 <1.90
Sulfide 1000 NE <0.010 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010 NE <0.010 <0.010
Vanadium 25 3.5*13.2J 4.07J 6.64J <1.40 <1.40 <1.40 <1.40 <1.40 <1.40 24 3.39J 1.95J
Zinc 10 1000 6.18J <3.8 <3.8 11.2 7.60J <3.80 106 <3.80 11.7 50 AL 5.54J <3.80
Notes:
1. ug/L = micrograms per liter (parts per billion).
2. SWSL = North Carolina Department of Environment and Natural Resources Solid Waste Section Limit established in 2007.
3. 15A NCAC 2L = North Carolina Groundwater Quality Standards (Updated January 2010).9. Bold and shaded indicates above 15A NCAC 2L or GWP ST.
4. GWP ST = Solid Waste Groundwater Protection Standard.10. Duplicate = Duplicate sample taken at DW-1 for the May 2014 sampling event.
5. 15A NCAC 2B = North Carolina Surface Water Quality Standards.11. Target analytes not shown were not detected above the laboratory method detection limits.
6. NA = Not Analyzed.12. MW-9 replaced MW-7 as a shallow groundwater monitoring compliance well. MW-9 was installed by S&ME personnel on 9-18-2007.
7. J = Detected, but below the Reporting Limit, therefore, result is an estimated concentration.13. * Indicates there is currently no 2L Standard. The target analyte was compared to the Solid Waste Section Groundwater Protection Standard (GWPST).
8. B= The analyte was detected in the associated method blank.
Sorrell Landfill, Apex, North Carolina
Semi-Annual Assessment Monitoring - November 30, 2015
downstream
EPA Appendix I Inorganic
Compounds Method 6010B/6020
(µg/L)
NCDENR
SWSL
15A NCAC
2L
EPA Appendix II Volatile Organic
Compounds (µg/L)
NCDENR
SWSL
15A NCAC
2L
EPA Appendix I Volatile Organic
Compounds (µg/L)
Table 5
Detected Analytes
S&ME Project No. 1054-07-251
15 NCAC
2B
NCDENR
SWSL
15A NCAC
2L
Sampling Date
Sampling Location
Compliance Wells
Off-site
Assessment
Well
upstream
Surface Water SampleSample Type Quality Control Samples
Background
Well
T:\Projects\2007\ENV\07-251 Sorrell Landfill\Reports\2015 November GW Sampling\Deliverables\Sorrell Landfill November 2015 Tables.xlsx
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APPENDIX I
LABORATORY REPORTS
APPENDIX II
HYDRAULIC GRADIENT / GROUNDWATER
FLOW VELOCITY CALCULATIONS
JOB NAME Sorrell Landfill JOB NO.
SUBJECT Hydraulic Gradient SHEET NO.
DATE
PURPOSE:COMPUTED BY
To determine the average true hydraulic gradient
CALCULATION FOR HYDRAULIC GRADIENT [ i = (h1-h2)/L ]
Purpose: To determine the average true hydraulic gradient
Given:Well GW Elevation
kA ZONE
: hydraulic conductivity 0.25 to 1.13 FT/DAY MW-1R 453.28
Ŋ: porosity 0.2 dimensionless MW-9 409.79
iAVG.: AVERAGE HYDRAULIC GRADIENT 0.0270 FT/FT MW-4 441.69
MW-8 438.75
CALCULATED FROM THE AVERAGE OF THREE POINT SOLUTIONS MW-5 390.20
USING MONITOR WELLS MW-MW-1, MW-9, and MW-4 or MW-8, MW-5 and MW-6 MW-6 404.95
GRADIENT:
distance
DETERMINED FROM 3 POINT PROBLEM BY PROJECTION
i4 = MW-1R – MW-9 =453.28 -409.79 =0.0257
distance
Use Elevation of Groundwater at MW-4 to establish elevation between MW-1R and MW-9
MW-1R - MW-4 453.28 -441.69 =450.38
gradient (MW-1R and
MW-9)
Draw line from MW-4 to point located 385.10 feet from MW-1R to MW-9.
Measure new distance between MW-1R and MW-9 perpendicular to line plotted for the contour. Recalculate Gradient
i4 = MW-1R – MW-9 =453.28 -409.79 =0.0259
New Distance
True Hydraulic Gradient =0.02589
i4 = MW-8 – MW-5 =438.75 -390.2 =0.0280
distance
Use Elevation of Groundwater at MW-6 to establish elevation between MW-8 and MW-5
MW-8 - MW-6 438.75 -404.95 =1165.52
gradient (MW-8 and MW-5)
Draw line from MW-6 to point located 1244.83 feet from MW-8 to MW-5.
Measure new distance between MW-8 and MW-5 perpendicular to line plotted for the contour. Recalculate Gradient
i4 = MW-8 – MW-5 =438.75 -390.2 =0.028243
New Distance
True Hydraulic Gradient =0.028243
Average True Hydraulic Gradient =0.0271
0.0290
1719
1690
0.0257
1680
1734
1054-07-251
1 of 1
1/5/2016
ARC
APPENDIX III
SUMMARY TABLE of
ELECTRONIC DATA DELIVERABLE (EDD)