HomeMy WebLinkAbout3301_EdgecombeMSWLF_20160220_GWMReport_DIN27215
January 2016 Environmental
Compliance Monitoring Report
Edgecombe County Landfill (Permit No. 33-01)
Tarboro, North Carolina
S&ME Project No. 4305-15-172
Prepared for:
Edgecombe County Solid Waste Department
P.O. Box 10
Tarboro, North Carolina 27886
Prepared by:
S&ME, Inc.
3201 Spring Forest Road
Raleigh, NC 27616
February 20, 2016
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Table of Contents
1.0 Project Information and Status ........................................................................... 1
1.1 Introduction ....................................................................................................................... 1
1.2 Background ....................................................................................................................... 1
2.0 January 2016 Sampling Event.............................................................................. 2
3.0 Site Hydrogeology ................................................................................................. 3
3.1 Groundwater Elevations and Flow Direction ............................................................... 3
3.2 Groundwater Flow Velocity ............................................................................................ 4
4.0 Water Quality ......................................................................................................... 5
4.1 Groundwater Analytical Data ........................................................................................ 5
4.1.1 Compare Background and Compliance Detections to the SWSL ........................................ 5
4.1.2 Compare Background and Compliance Detections to Standards ........................................ 7
4.1.3 Compare Background and Compliance Detections to MDL ............................................... 8
4.1.4 Quality Control ................................................................................................................... 8
4.2 Surface Water Analytical Data ........................................................................................ 9
5.0 Discussion of Groundwater Detections ............................................................ 9
5.1 Appendix I Inorganics ..................................................................................................... 9
5.2 Appendix I VOCs ............................................................................................................. 9
5.3 Previous Investigations Selected Corrective Measures Remedy ............................. 10
6.0 Conclusions and Recommendations ............................................................... 10
6.1 Summary of January 2016 Sampling Event ................................................................ 10
6.2 Recommendations .......................................................................................................... 11
7.0 References ............................................................................................................. 12
List of Figures
Figure 1 Vicinity Map
Figure 2 Groundwater Potentiometric Map
List of Tables
Table 1 Groundwater Elevation Data
Table 2 Summary of Field Parameters
Table 3 Groundwater Quality Summary
Table 4 Existing Well/Piezometer Construction Details
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Appendices
Appendix I – Field Notes
Appendix II – Report of Laboratory Analyses
Appendix III – Compact Disk with Electronic Copy of Historical Analytical Results (.xls) and
Electronic Copy of this Report
Appendix IV – Groundwater Velocity Calculations
Appendix V – Time Series Graphs for Monitor Wells
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1.0 Project Information and Status
1.1 Introduction
Edgecombe County currently operates a solid waste facility on a tract of land located off of Colonial Road
(S.R. 1601) in Edgecombe County, south of Tarboro, North Carolina (Figure 1). The solid waste facility
includes a municipal solid waste (MSW) transfer facility, a construction & demolition (C&D) debris landfill
unit, white goods and wooden pallet storage area, soil borrow pits, a landfill gas to energy system, and
various operational buildings. The C&D landfill unit is operated over a closed MSW landfill, and is
regulated in general accordance with North Carolina Department of Environment and Natural Resources
Division of Waste Management (NCDENR-DWM) Permit No. 33-01. Edgecombe County continues to
perform groundwater and surface water monitoring on a semiannual basis to comply with the
requirements of North Carolina Solid Waste Management Rules (Solid Waste Rules), 15A NCAC 13B.
S&ME has prepared this report on behalf of Edgecombe County to present the results of the January 2016
monitoring event as required by § .0600 and .1632 of the Solid Waste Rules.
The January 2016 monitoring event included sampling for groundwater quality from the following wells,
which comprise the groundwater monitoring network:
Water Quality Monitoring Network Groundwater Sampling Locations
Background
Monitor Wells
Compliance
Monitor Wells
MW-3B MW-5 MW-13
MW-4 MW-6 MW-14
MW-9
MW-7A MW-15
MW-12 MW-16
Jerry’s Creek is the surface water feature located on the northern boundary of the landfill where two
surface water samples (upstream and downstream) are typically collected to review surface water quality
(Figure 2).
1.2 Background
Groundwater has been monitored at the landfill facility since 1994 in accordance with § .1632 of the Solid
Waste Rules under the landfill’s Water Quality Monitoring Plan (WQMP). The WQMP was originally
written in September 1994, revised in June 2008 and again in January 2010. Current groundwater
monitoring at the landfill is conducted in general conformance with the January 2010 WQMP.
Volatile organic compounds (VOCs) and inorganic constituents (metals) have been detected above North
Carolina groundwater protection standards in groundwater samples collected from groundwater
compliance monitoring points at Edgecombe County Landfill. Previous statistical evaluation of the
groundwater monitoring data indicated that a release of VOCs and metals had occurred. In accordance
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with NCDENR North Carolina Solid Waste Rules defined under 15A NCAC 13B, S&ME has completed the
following activities on behalf of Edgecombe County in response to the detections of the VOC and metals
in groundwater:
– Statistical analyses (January 2007) of semiannual water quality results of compliance well
monitoring system in accordance with the facility’s Water Quality Monitoring Plan (WQMP);
– Alternate Source Demonstration (ASD) study in accordance with Solid Waste Rules defined
under 15A NCAC 13B.1633(c)(3) and .1634(g)(2);
– Nature and Extent Study (NES) prepared in accordance with Solid Waste Rules defined under
15A NCAC 13B.1634(g)(1);
– Assessment of Corrective Measures (ACM) in accordance with Solid Waste Rules defined
under 15A NCAC 13B.1635; and,
– Corrective Action Plan (CAP) in accordance with Solid Waste Rules defined under 15A NCAC
13B.1636.
– Baseline Groundwater Sampling and Monitored Natural Attenuation Report (July 2012).
The January 2016 semi-annual groundwater sampling services were completed in general accordance with
the requirements of the Solid Waste Rules defined under 15A NCAC 13B .1632 (Groundwater Sampling
and Analysis Requirements), .1634 (Assessment Monitoring Program), and .1637 (Implementation of the
Corrective Action Program).
2.0 January 2016 Sampling Event
On January 18 and 19, 2016, S&ME personnel collected groundwater samples from 11 monitor wells
(MW-3B, MW-4, MW-5, MW-6, MW-7A, MW-9, MW-12, MW-13, MW-14, MW-15, and MW-16) and
surface water samples at two locations (upstream/SW-1 and downstream/SW-2) at the Edgecombe
County Landfill (Figure 2). S&ME personnel performed sampling in general accordance with the Solid
Waste Rules and the facility’s WQMP, dated June 2008, revised January 2010. In addition to collecting
samples from the 11 compliance monitor wells, groundwater levels were measured in 25 other monitor
wells and piezometers listed in the WQMP network of monitoring points.
Prior to collecting groundwater samples, the monitor wells and piezometers were opened and allowed to
equilibrate with atmospheric conditions before gauging the liquid level. Groundwater depths were
measured to an accuracy of ±0.01 feet using an electronic water level indicator, which was
decontaminated before its initial use and between measurements. The measurements were collected to
calculate relative groundwater elevations, to develop a groundwater potentiometric map, and to estimate
the hydraulic gradient and groundwater flow direction at the time of the sampling event. Water level
measurements are presented in Table 1 and Figure 2.
After collecting the static groundwater levels, stagnant water from wells that were scheduled for sampling
were purged using a peristaltic pump. Low-flow sampling methods were followed to purge and sample
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groundwater from the monitor wells. As purging proceeded, an YSI® multi-meter with a flow-through
cell was used to measure field parameters that included pH, temperature, specific conductance, oxidation-
reduction potential, and turbidity. Field parameters were measured and recorded at regular intervals
before sampling. A copy of the field notes are included in Appendix I.
A groundwater sample was collected after field parameters (pH, temperature, and conductivity) stabilized
and the turbidity measurement was approximately 10 Nephelometric Turbidity Units (NTUs) or less. In
accordance with the WQMP, field parameters were considered stable when they were changing less than
10 percent over three consecutive measurements. The field parameter measurements are presented in
Table 2. One duplicate groundwater sample was collected from MW-5 for the purpose of Quality Control
(QC). In addition, one trip blank and one equipment blank sample were also collected for QC. These
results are included in Table 3.
Groundwater samples were collected through the silicon tubing and pumped directly into clean
containers provided by the laboratory. Once filled, the sample containers were sealed, labeled, and
placed into an insulated container with ice. The samples were managed under chain-of-custody protocols
and shipped to Environmental Conservation Laboratories, Inc. (ENCO), a North Carolina-certified
laboratory. ENCO analyzed the samples for constituents listed in 40 CFR 258 Appendix I.
The results of analytical testing are discussed in Section 4, and a summary of detected constituent
concentrations are presented in Table 3. Copies of the laboratory reports are provided in Appendix II. A
compact disk (CD) with an electronic copy of tabulated historical analytical results in Excel spreadsheet
format (.xls) and an electronic copy of this report in portable document format (.pdf) are included in
Appendix III. Well construction details for the monitor wells are shown in Table 4.
3.0 Site Hydrogeology
3.1 Groundwater Elevations and Flow Direction
Based on the Soil Conservation Service, Soil Survey of Edgecombe County, the uppermost aquifer at the
site is unconfined and is found in the silty sands of the Sunderland Formation. This aquifer is recharged
by inflow from up-gradient areas and by precipitation infiltration. The uppermost aquifer underlying the
landfill is expected to discharge to the local surface water features including Jerry’s Creek and the
drainage features in the active landfill area. During flood conditions, the southwest perimeter trench and
the farm pond located in the southeast corner of the site may recharge the aquifer. The marine clay layer
(Yorktown Formation) encountered at depths from approximately eight to 24 feet below the original
ground surface acts as an aquitard and semi-confining layer below the landfill.
Shallow monitoring wells and piezometers are installed in the surficial aquifer with the bottoms of the
wells resting above, on, or penetrating the top of the Yorktown Formation. As previously discussed, static
water levels in the 11 compliance wells, 15 other monitor wells and 10 piezometers of the site monitoring
network were measured prior to sampling.
Static water level measurements collected during the January 2016 sampling event (Table 1) were used to
calculate the corresponding groundwater elevations based on surveyed top of casing (TOC) elevations. A
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groundwater potentiometric map was developed using the groundwater elevations (Figure 2). Based
upon the groundwater potentiometric surface elevations, the groundwater flow direction was estimated
to be to the north-northeast. The average horizontal hydraulic gradient was calculated from three point
calculation solutions using two sets (three wells per set) of groundwater elevation data measured on
January 18, 2016 and by 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 two-well 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-3B, MW-7A, and MW-5, and P-1, MW-7A and MW-5 is estimated to be
0.0212 ft/ft. The hydraulic gradient calculations are included in Appendix IV.
3.2 Groundwater Flow Velocity
An approximate average linear groundwater flow velocity (V) was calculated using the following equation
(Freeze and Cherry, 1979):
V = Ki
n
where: V = Average linear groundwater flow velocity [feet per year (ft/yr)]
K = Hydraulic conductivity (ft/yr)
i = Flow gradient as a ratio (ft/ft)
n = Effective soil porosity (percent)
Aquifer rising and falling head tests were previously performed at the site by Law Engineering Company
(Law) and by S&ME. The aquifer 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 (provided in previous reports) were analyzed by the Bouwer and Rice Method.
The hydraulic conductivity, K, values previously measured at the site ranged from 1.29x10-5 centimeters
per second (cm/sec) to 3.65x10-4 cm/sec. An average hydraulic conductivity value of 5.95x10-5 cm/sec was
used for calculating the site-wide flow velocity. The average hydraulic gradient of 0.0212 ft/ft, calculated
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from the three point solution described above was used as the site-wide average gradient. An effective
soil porosity, n, of 15% was used as the site-wide average.
The average groundwater flow velocity, V, for the site, using the equation and input values above, was
estimated at 8.7007 ft/yr. Groundwater flow velocity calculations are included in Appendix IV. The
average groundwater flow velocity information is presented on Figure 2.
4.0 Water Quality
In general accordance with the assessment monitoring requirements described in § .1634 of the Solid
Waste Rules, S&ME sampled three background and eight compliance groundwater monitor wells during
the January 2016 sampling event. The samples were analyzed by ENCO for constituents listed in the 40
CFR 258, Appendix I analyte list using the analytical methods that included EPA Method 6010/6020
(metals) and Method 8260B (VOCs). The field measurements are summarized on Table 2. The
groundwater summary of compound detections is presented in Table 3. The chain-of-custody form and
the laboratory reports from ENCO are provided in Appendix II.
Effective December 1, 2006, NCDENR-DWM, changed the standard limits for comparing constituent
detections in laboratory analysis from the Practical Quantitation Limits (PQLs) established in 1994 to the
Solid Waste Reporting Limits (SWRLs). On February 23, 2007, the Section further revised the reporting
limits from the SWRL to the Solid Waste Section Limit (SWSL). The SWSL was defined as the lowest
amount of analyte in a sample that can be quantitatively determined with suitable precision and accuracy.
The new SWSL limits are lower than the previous PQL limits. Concentrations reported by the laboratory
that are above the Method Detection Limit (MDL) but below the SWSL must be qualified as estimated
values designated by the letter “J”. According to the laboratory quality control performed by ENCO,
detections above the MDL but below the method reporting limit (MRL) are considered estimated values,
designated by the letter “J”.
4.1 Groundwater Analytical Data
Constituent concentrations detected above the laboratory MDLs are summarized on Table 3. For
comparison purposes, these results are shown with their respective SWSL and the 15A North Carolina
Administrative Code (NCAC) Subchapter 2L .0200 Groundwater Quality Standards (2L Standard), which
were recently revised and became effective April 1, 2013. Where target groundwater constituents have no
established 2L Standard, the MDL is the default 2L Standard. However, since the DWM has listed
constituent concentrations protective of groundwater, the NCDENR-DWM Section Ground Water
Protection Standard (GWPST) established in accordance with the Solid Waste Management Rules, Section
.1634(h) is used as the action level for detections where no 2L Standard is established.
4.1.1 Compare Background and Compliance Detections to the SWSL
The following table summarizes the monitor well locations where Appendix I constituents were detected
at levels that are equal to or exceed the SWSL concentration in one or more samples in the January 2016
monitoring event:
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January 2016 Groundwater Sampling Event
Appendix I Constituent Concentration Detected Equal to or Greater than SWSL
Background
Monitor Wells
Appendix I Detected Constituents
Equal to or Greater Than Their SWSL
MW-3B ---
MW-4 zinc
MW-9 barium
Compliance
Monitor Wells
Appendix I Detected Constituents
Equal to or Greater Than Their SWSL
MW-5 Benzene, chlorobenzene, 1-4-dichlorobenzene, cis-1,2-
dichloroethene, vinyl chloride, arsenic, barium, cobalt, nickel, zinc
MW-6 barium, cobalt, zinc
MW-7A benzene, 1, 4-dichlorobenzene, arsenic, barium
MW-12 benzene, chlorobenzene, 1,4-dichlorobenzene, barium, cobalt,
zinc
MW-13 chlorobenzene, 1,4-dichlorobenzene, cis-1,2-dichloroethene, vinyl
chloride, arsenic, barium, cobalt, nickel, zinc
MW-14 barium
MW-15 cis-1,2-dichloroethene, vinyl chloride, arsenic, barium, cobalt
MW-16 barium
--- = No Appendix I constituent concentrations were detected above SWSL.
Volatile Organic Compounds
No Appendix I VOC concentrations were reported at concentrations above the analytical method’s
detection limit in the groundwater samples collected from the background monitor wells MW-3B, MW-4,
and MW-9, nor were they detected above the analytical method’s detection limit in the groundwater
samples collected from the compliance monitor wells MW-6, MW-14 and MW-16.
The table above lists the VOCs detected in groundwater sampled from monitor wells MW-5, MW-7A,
MW-12, MW-13, and MW-15 that were detected above their respective SWSLs.
Inorganic Compounds
The table above lists the inorganic compounds detected in groundwater sampled from the upgradient
background monitor wells MW-4 and MW-9 and down-gradient compliance monitor wells MW-5, MW-6,
MW-7A, MW-12, MW-13, MW-14, MW-15, and MW-16 that were detected above their respective SWSLs.
Five inorganic compounds were detected in the groundwater sample collected from background monitor
well MW-4 and eight inorganic compounds were detected in the groundwater sample collected from
background monitoring well MW-3B.
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4.1.2 Compare Background and Compliance Detections to Standards
The following table summarizes the monitor well locations where Appendix I constituents were detected
above the 2L Standard or GWPST (presented in Table 3). The following targeted chemicals were detected
above the 2L Standard in one or more groundwater samples analyzed for the January 2016 monitoring
event:
January 2016 Groundwater Sampling Event
Appendix I Constituent Concentration Detected Above 2L Standard or GWPST
Background
Monitor Wells
Appendix I Detected Constituents
Above 2L Standard or GWPST
MW-3B cobalt, vanadium
MW-4 vanadium
MW-9 --
Compliance
Monitor Wells
Appendix I Detected Constituents
Above 2L Standard or GWPST
MW-5 benzene, 1,4-dichlorobenzene, cis-1,2-dichloroethene, vinyl chloride,
arsenic, cobalt
MW-6 cobalt, vanadium
MW-7A benzene, arsenic
MW-12 benzene, 1,4-dichlorobenzene, cobalt
MW-13 vinyl chloride, arsenic, cobalt, nickel, thallium
MW-14 ---
MW-15 1,2-dichloropropane, vinyl chloride, arsenic, cobalt
MW-16 cobalt
--- = No Appendix I constituent concentrations were detected above 2L Standard or GWPST.
Volatile Organic Compounds
No Appendix I VOC were detected above their respective 2L Standards or GWPSTs in the groundwater
samples collected from the upgradient background monitor wells MW-3B, MW-4, and MW-9, nor were
they detected in the groundwater samples collected from the downgradient compliance monitor wells
MW-6, MW-14, and MW-16.
The table above lists the VOCs detected in groundwater sampled from monitor wells MW-5, MW-7A,
MW-12, MW-13 and MW-15 that were detected above their respective 2L Standards or GWPSTs.
Inorganic Compounds
The table above lists the inorganic compounds detected in groundwater sampled from the upgradient
background monitor wells MW-3B and MW-4 and downgradient compliance monitor wells MW-5, MW-6,
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MW-7A, MW-12, MW-13, MW-15, and MW-16 that were detected above their respective 2L Standards or
GWPSTs. One inorganic compound, barium, was detected in the groundwater sample collected from
background monitor well MW-9 and from compliance monitoring well MW-14, but below its respective 2L
Standard or GWPST.
4.1.3 Compare Background and Compliance Detections to MDL
The analytical data was reviewed by comparing constituent detections in the background and compliance
monitor wells to the laboratory’s Method Detection Limit (MDL). Twenty Appendix I constituents
(summarized in Table 3) were detected above the MDL in one or more groundwater samples collected
during the January 2016 monitoring event.
4.1.4 Quality Control
Quality assurance and quality control of field sampling methods and analytical test methods were
assessed by collecting and analyzing one duplicate sample, one equipment blank sample, and one trip
blank sample. The duplicate and equipment blank samples were analyzed for Appendix I constituents by
the same methods and for the same target constituents as the record samples, with the exception of
dissolved metals. Duplicate sample analysis documents the consistency of field sampling methods and
the consistency of laboratory testing between samples. Equipment blank sample analysis documents the
quality of sampling equipment and decontamination procedures used to reduce the potential of cross-
contamination or carry-over effects from sampling equipment used on-site. The trip blank is analyzed for
VOCs to document the effect of external conditions on samples/sample containers during lab pack
preparation and transportation to and from the site.
The concentrations of Appendix I VOCs and inorganic compounds detected in the record and in the
duplicate samples collected from monitor well MW-5 were within an acceptable tolerance level and
indicate a suitable replication of results from the test procedures. Given that the record sample and the
duplicate sample for MW-5 were analyzed at a one to five dilution factor for the VOC analysis, these
results fall within an acceptable tolerance level and indicate suitable replications of results from the test
procedures. This results are presented in Table 3.
In the equipment blank sample, acetone was the only constituent detected at concentrations that
exceeded their respective MDLs with a “J” qualified result, but were approximately twenty-five orders of
magnitude below the respective SWSL. This result is presented in Table 3.
Some technical limitations exist in the laboratory’s reporting of MDLs. MDLs for some VOCs and some
inorganic constituents are above the applicable standards. The MDL for vinyl chloride (0.32 µg/L), cobalt
(1.1 µg/L), and vanadium (1.4 µg/L) in groundwater are greater than the 2L Standard of 0.03 µg/L for vinyl
chloride and the GWPSTs of 1.0 µg/L for cobalt and 0.3 µg/L for vanadium. Therefore, vinyl chloride,
cobalt, and vanadium may have been present at concentrations above their respective 2L
Standard/GWPST, but were reported as being below their respective MDLs.
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4.2 Surface Water Analytical Data
Surface water samples were collected from two surface water stations (upstream/SW-1 and
downstream/SW-2) in Jerry’s Creek as part of the January 2016 monitoring event. Surface water sample
stations are illustrated on Figure 2.
Laboratory analytical results indicated that no Appendix I VOCs was reported above the laboratory
method detection limits in the upstream/SW-1 or the downstream/SW-2 surface water samples.
Laboratory analysis indicated that barium, cobalt, and zinc were detected above the laboratory MDL in the
surface water samples collected from the upstream/SW-1 and downstream/SW-2 locations. The values
for barium, cobalt, and zinc were flagged by the laboratory as estimated values. Cobalt was detected
above its 2L standard for the upstream/SW-1 and downstream/SW-2 locations.
5.0 Discussion of Groundwater Detections
Statistical analyses have been performed in previous reports to evaluate the significance of the analytical
results. These analyses include a more comprehensive discussion of the groundwater quality and trends
than are within the scope of this report. Modifications to the sampling and reporting schedule were made
in the Baseline Groundwater Sampling and Monitored Natural Attenuation Report (S&ME, 2012), which
established that monitored natural attenuation parameters sampling and statistical analysis will be
performed on an 18-month basis. Time series graphs for individual constituents were plotted for wells
with detections of the corresponding constituents over the regulatory limits. The constituent charts are
provided in Appendix V.
5.1 Appendix I Inorganics
For the combined data set of both groundwater and surface water sample results, of the 20 Appendix I
constituents that were reported above the MDL from the January 2016 monitoring event, 12 are inorganic
compounds. In June 2008, S&ME performed an Alternate Source Demonstration (ASD) study that
concluded that several inorganic compounds detected in groundwater were the result of the natural
occurrence of these constituents in the native, residual soil. The detections of the 12 inorganic
compounds, with the exception of antimony, were compared to the expected groundwater concentration
calculated from the soil-to-groundwater Dilution/Attenuation Factor (DAF) computations included in the
ASD (reference Table 3). During the January 2016 sampling event, five Appendix I inorganics were
detected, in groundwater samples collected from compliance wells, at concentrations above their
respective 2L Standards/GWPST or the expected groundwater concentration from the ASD: arsenic, cobalt,
nickel, thallium and vanadium.
5.2 Appendix I VOCs
Appendix I VOCs were reported above the laboratory MDLs in groundwater samples collected from
compliance monitor wells MW-5, MW-7A, MW-12, MW-13, and MW-15. Of the detected constituents,
the following were reported at concentrations in excess of the respective 2L Standard/GWPST: benzene,
1,4-dichlorobenzene, cis-1,2-dischloroethene, 1,2-dichloropropane, and vinyl chloride.
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With some exceptions, concentrations of VOCs have been shown to increase during the July sampling
events and decrease during the January sampling events. Lower January concentrations are likely a
function of the higher water table resulting from increased rainfall in the winter months. The goals of the
corrective measures include minimizing the infiltration of rainwater through the waste and increasing the
residence time of constituents so that constituents are completely attenuated prior to migration off site.
5.3 Previous Investigations Selected Corrective Measures Remedy
On June 30, 2008, S&ME prepared a Corrective Action Plan in which the following corrective measures
were recommended:
• Installation of an up-gradient groundwater hydraulic barrier;
• Maintaining a consistent contour with pre-1998 waste area;
• Increasing slope of the closed MSW area;
• Stormwater improvements on the western half of the landfill; and,
• Implementation of a monitored natural attenuation (MNA) program to address impacted
groundwater.
S&ME prepared a Baseline Groundwater Sampling and Monitored Natural Attenuation Report (July 19,
2012), which established baseline water quality standards to gauge MNA and establish the key parameters
for sampling. Corrective measures currently being implemented at the site include the increase in slope
of the closed MSW area, stormwater improvements, and the implementation of the MNA program. Semi-
annual monitoring will continue to assess the effectiveness of the corrective measures.
6.0 Conclusions and Recommendations
S&ME performed semiannual sampling at the Edgecombe County Landfill in Tarboro, North Carolina.
During the January 2016 sampling event, groundwater elevations were calculated from water levels
measured in the 11 compliance monitor wells and 25 other monitor wells and piezometers listed in the
WQMP network of monitoring points. Groundwater samples were collected from three background (up-
gradient) monitor wells and eight compliance (down-gradient) monitor wells. Surface water samples were
collected from two stream sample locations (upstream and downstream).
6.1 Summary of January 2016 Sampling Event
Based on the water table elevations and calculated potentiometric surface, the groundwater flow
direction within the surficial aquifer was estimated to be toward the north-northeast with an average
hydraulic gradient of 0.0212 ft/ft. The average groundwater flow velocity for the site is approximately
8.7007 ft/yr.
Constituent concentrations of 20 Appendix I analytes were detected in one or more samples collected
during the January 2016 monitoring event. Ten of the 20 Appendix I analytes were detected in one or
more samples at concentrations equal to or exceeding their respective SWSLs.
Ten Appendix I analytes were detected at concentrations in excess of the 2L Standards/GWPSTs in
groundwater samples collected at the site including benzene, 1,4-dichlorobenzene, cis-1,2-
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dichloroethene, 1,2-dichloropropane, vinyl chloride, arsenic, cobalt, nickel, thallium and vanadium.
Wells in which there were one or more constituents above the standards include MW-3B, MW-5, MW-
6, MW-7A, MW-12, MW-13, and MW-15.
Three Appendix I inorganics (metals) were detected above the laboratory MDLs in the surface water
samples collected from Jerry’s Creek. The concentrations of barium, cobalt, and zinc were above the
laboratory MDL, but below the SWRLs and the concentrations were flagged as an estimated value (J)
for both the upstream and downstream samples. Concentrations of cobalt were above the 2L
standard levels for both the upstream and downstream samples. Concentrations of inorganic
constituents were generally similar in the upgradient and downgradient samples for barium, cobalt
and zinc, indicating the detected metals are naturally occurring.
No VOCs were detected in the surface water samples, indicating impacted groundwater at the facility
is not adversely affecting surface water.
Constituent detections above the 2L Standard or GWPST trigger implementing the assessment monitoring
program. This monitoring event was performed in general accordance with § .1634 (d)(2)of the Solid
Waste Rules since the Assessment Monitoring Program was already implemented. An Alternate Source
Demonstration (ASD) study was performed, the Nature and Extent Study (NES) was prepared, the
Assessment of Corrective Measures (ACM) was performed, and the Corrective Action Plan (CAP) was
prepared and approved by the NCDENR. Corrective measures have been initiated with grading
improvements on the landfill cap and breaching the dam of the pond located at the southeast corner of
the landfill (part of the construction of a hydraulic barrier). Therefore, monitoring for this event is also for
compliance with § .1637 (a)(1) under Implementation of the Corrective Action Program.
6.2 Recommendations
The results of the January 2016 sampling event show that groundwater near the Edgecombe County
Landfill has been impacted by a release of constituents from the facility. Impacted groundwater at the
facility does not appear to be adversely affecting surface water at the site. The additional assessment
performed at the site as part of the NES and ACM refined the source characterization, determination of
constituents-of-concern, and evaluation of corrective actions. Based on the additional findings presented
in the NES and ACM, Edgecombe County selected a remedy for corrective measures and submitted a CAP.
According to the Corrective Action Plan Review letter, dated January 16, 2009, the Solid Waste Section
recommends that semiannual sampling be continued at the site for analytes on the Appendix I
constituent list. S&ME completed four baseline data sets of MNA parameters and submitted the Baseline
Water Quality and Monitored Natural Attenuation Report, dated July 19, 2012.
On January 18, 2013, S&ME personnel met with the Section to discuss changes to the SAP. During the
meeting, the Section approved modifications to the Sampling and Analysis Plan (SAP), in which MNA and
Geochemical parameters are to be temporarily discontinued until the corrective measures, detailed in the
Corrective Action Plan (CAP), prepared by S&ME and dated November 17, 2009, are implemented. Once
the corrective measures are in place, the revised SAP for MNA and geochemical parameters will be
implemented.
Environmental Compliance Monitoring Report
January 2016
Edgecombe County Landfill
S&ME Project No. 4305-15-172
February 20, 2016 12
As required by North Carolina Solid Waste Management Rule .1634, these results should be forwarded to
the owner/operator of the Edgecombe County Landfill for inclusion in the operating record and to the
North Carolina Division of Solid Waste for their review.
7.0 References
Department of Environment and Natural Resources, Division of Water Quality, 15A NC Administrative
Code Subchapter 2B .0200 Classifications and Water Quality Standards Applicable to Surface Waters and
Wetlands of NC, May 2007.
Department of Environment and Natural Resources, Division of Water Quality, 15A NC Administrative
Code Subchapter 2L .0200 Groundwater Quality Standards, April 2013.
Department of Environment and Natural Resources, Division of Waste Management, 15A NC
Administrative Code Subchapter 13B .1634(h) Solid Waste Groundwater Protection Standard, Solid Waste
Management Rules, November 2004.
Law Engineering Company, Initial baseline Sampling of Groundwater, Edgecombe County Landfill, October
1994.
Cherry, John A. and Freeze, R. Allen, Groundwater, Prentice Hall, Inc., 1979.
Driscoll, F., Groundwater and Wells, Second Edition, Johnson Division, USA, 1986.
S&ME, Inc., Alternate Source Demonstration Report, Edgecombe County Landfill, June 10, 2008.
S&ME, Inc., Assessment of Corrective Measures Report, Edgecombe County Landfill, June 26, 2008.
S&ME, Inc., Baseline Groundwater Sampling and Monitored Natural Attenuation Report, July 2012.
S&ME, Inc., Corrective Action Plan, Edgecombe County Landfill, June 30, 2008.
S&ME, Inc., Nature and Extent Study, Edgecombe County Landfill, June 25, 2008.
S&ME, Inc., Water Quality Monitoring Plan, Edgecombe County Landfill, Tarboro, North Carolina, May 10,
1994.
S&ME, Inc., Water Quality Monitoring Plan, Edgecombe County Landfill, Tarboro, North Carolina, June 30,
2008, Revised January 2010.
US Department of Agriculture, Soil Conservation Service, Soil Survey of Edgecombe County, NC, November
1979.
FIGURES
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EDGECOMBE COUNTY LANDFILL
ENVIRONMENTAL COMPLIANCE MONITORING
TARBORO, NORTH CAROLINA
GROUNDWATER POTENTIOMETRIC MAP
JANUARY 18 & 19, 2016
Q:\PROJECTS\2015\4305-15-172\CAD\D1432.dwg, FIG2, 5/4/2016 4:27:18 PM, 1:1
TABLES
PIEZOMETER
OR STATIC BOTTOM TOP OF STATIC
WELL NUMBER WATER LEVEL OF WELL CASING WATER LEVEL
P-1 5.61 21.96 74.48 68.87
P-2A 12.43 27.17 83.61 71.18
P-3A 12.15 27.17 79.77 67.62
P-12 8.24 13.92 54.15 45.91
P-15 4.70 10.30 45.16 40.46
P-17 3.38 10.15 42.45 39.07
P-18 12.20 18.44 54.44 42.24
P-19 9.47 17.67 58.88 49.41
P-25 NM ------
P-29 NM ------
P-34 2.92 13.04 44.34 41.42
P-35 3.36 13.10 44.50 41.14
MW-3B 6.42 22.67 81.18 74.76
MW-4 7.65 20.18 68.95 61.30
MW-5 10.40 23.86 53.75 43.35
MW-5D 9.54 41.63 52.08 42.54
MW-5S 7.99 13.50 50.54 42.55
MW-6 3.15 19.75 46.29 43.14
MW-7A 13.33 26.94 68.43 55.10
MW-8A 9.40 22.38 82.34 72.94
MW-9 3.60 16.85 72.41 68.81
MW-10 3.20 13.57 75.78 72.58
MW-12 7.13 12.68 51.24 44.11
MW-13 5.25 23.00 54.99 49.74
MW-14 3.60 14.64 43.88 40.28
MW-15 4.98 14.27 44.87 39.89
MW-16 8.25 19.85 46.58 38.33
GW-1R 5.90 9.83 81.08 75.18
GW-2R 6.34 9.88 75.72 69.38
GW-3 DRY 5.22 69.00 DRY
GW-4 9.33 12.05 69.93 60.60
GW-5 10.22 12.07 65.23 55.01
GW-6 5.67 9.64 79.02 73.35
GW-7 1.69 9.61 75.02 73.33
GW-8 2.70 9.84 79.92 77.22
GW-9 4.98 9.19 72.69 67.71
GW-10 2.15 10.01 69.17 67.02
GW-11 2.75 9.68 64.19 61.44
Upstream (SW-1)NM --49.22 NM
Downstream (SW-2)NM --44.58 NM
NOTES:
TOC = TOP OF CASING - ELEVATIONS FROM SITE SURVEY
AMSL = ABOVE MEAN SEA LEVEL
NM = NOT MEASURED
(A OR B) = REPLACEMENT WELL
D OR S = DEEP OR SHALLOW
Table 1
ELEVATIONS (FEET AMSL)
Groundwater Elevation Data
Edgecombe County Landfill
January 18 and 19, 2016
S&ME Project No. 4305-15-172
DEPTH FROM TOC (FEET)
Edgecombe County Landfill
Tarboro, NC
S:\ENVIRON...\January 2016 Sample Tables
MW-3B MW-4 MW-9 MW-5 MW-6 MW-7A MW-12 MW-13 MW-14 MW-15 MW-16 SW-1
(Upstream)
SW-2
(Downstream)
Field Parameters Units
Conductivity mS/cm 0.258 0.248 0.233 1.121 0.686 0.741 0.867 0.945 0.380 0.828 0.616 0.090 0.104
Oxidation-Reduction Potential (ORP)mV 295.3 138.7 20.8 -112.9 156.3 -34.4 214.7 16.2 13.0 -75.5 -56.3 0.6 -74.1
Dissolved Oxygen mg/L NM NM NM NM NM NM NM NM NM NM NM NM NM
pH SU3 4.15 5.74 6.77 6.34 5.27 5.98 4.78 6.09 6.98 6.40 6.18 7.02 7.35
Temperature °C 14.90 23.93 27.11 24.83 24.52 26.80 25.03 24.86 24.35 24.44 25.05 20.81 20.48
Turbidity NTU 4.7 6.9 5.9 0.0 8.2 25.6 5.9 7.3 0.0 11.3 7.4 1.9 3.7
Well ID
BACKGROUND MONITOR WELLS COMPLIANCE MONITOR WELLS SURFACE WATER
Table 2
Summary of Field Parameters
Edgecombe County Landfill
January 18 and 19, 2016 Sampling Event
S&ME Project No. 4305-15-172
MW-3B MW-4 MW-9 MW-5 MW-6 MW-7A MW-12 MW-13 MW-14 MW-15 MW-16 DUPLICATE
(MW-5)
EQUIPMENT
BLANK TRIP BLANK UPSTREAM
(SW-1)
DOWNSTREAM
(SW-2)
Acetone µg/l 100 6,000 <1.2 <1.2 <1.2 <6.0 <1.2 <1.2 <1.2 <1.2 <1.2 <1.2 <1.2 <6.0 D 4 J <1.2 <1.2 <1.2
Benzene µg/l 1 1 <0.15 <0.15 <0.15 4.0 D <0.15 1.8 3 0.5 J <0.15 0.58 J <0.15 3.8 JD <0.15 <0.15 <0.15 <0.15
Chlorobenzene µg/l 3 50 <0.17 <0.17 <0.17 20 D <0.17 2.6 J 4.5 12 <0.17 2.1 J <0.17 22 D <0.17 <0.17 <0.17 <0.17
1,4-Dichlorobenzene µg/l 1 6 <0.19 <0.19 <0.19 12 D <0.19 1.2 9.8 2.2 <0.19 <0.19 <0.19 13 D <0.19 <0.19 <0.19 <0.19
1,1-Dichloroethane µg/l 5 6 <0.13 <0.13 <0.13 2.8 JD <0.13 <0.13 0.41 J 0.43 J <0.13 0.65 J <0.13 3.4 JD <0.13 <0.13 <0.13 <0.13
cis-1,2-Dichloroethene µg/l 5 70 <0.15 <0.15 <0.15 210 D <0.15 <0.15 <0.15 11 <0.15 5.2 <0.15 210 D <0.15 <0.15 <0.15 <0.15
trans-1,2-Dichloroethene µg/l 5 100 <0.21 <0.21 <0.21 2.2 JD <0.21 <0.21 <0.21 <0.21 <0.21 <0.21 <0.21 2.2 JD <0.21 <0.21 <0.21 <0.21
1,2-Dichloropropane µg/l 1 0.6 <0.1 <0.1 <0.1 <0.5 D <0.1 <0.1 <0.1 <0.1 <0.1 0.67 J <0.1 <0.5 D <0.1 <0.1 <0.1 <0.1
Vinyl chloride µg/l 1 0.03 <0.32 <0.32 <0.32 22 D <0.32 <0.32 <0.32 4 <0.32 2.6 <0.32 20 D <0.32 <0.32 <0.32 <0.32
APP. I INORGANIC
COMPOUNDS
EPA METHOD 6010B MW-3B MW-4 MW-9 MW-5 MW-6 MW-7A MW-12 MW-13 MW-14 MW-15 MW-16 DUPLICATE
(MW-5)
EQUIPMENT
BLANK TRIP BLANK UPSTREAM
(SW-1)
DOWNSTREAM
(SW-2)
Antimony (Total)µg/l NE 6 1*0.466 J 0.731 J <0.22 <0.22 <0.22 <0.22 <0.22 <0.22 <0.22 <0.22 <0.22 <0.22 <0.22 NS <0.22 <0.22
Arsenic (Total)µg/l 30 10 10 <6.8 <6.8 <6.8 70.8 <6.8 46.2 <6.8 10.4 <6.8 12.7 <6.8 73.6 <6.8 NS <6.8 <6.8
Barium (Total)µg/l 178 100 700 69.5 J 62.2 J 116 327 132 253 178 253 200 328 293 326 <1.NS 54.4 J 54.4 J
Beryllium (Total)µg/l 2.5 1 4*0.169 J <0.1 <0.1 <0.1 0.141 J <0.1 0.196 J <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 NS <0.1 <0.1
Chromium (Total)µg/l 95 10 10 <1.4 <1.4 <1.4 3.28 J <1.4 <1.4 <1.4 9.79 J <1.4 3.67 J <1.4 3.23 J <1.4 NS <1.4 <1.4
Cobalt (Total)µg/l 61 10 1*7.61 J <1.1 <1.1 174 25.7 <1.1 16.3 555 <1.1 23.6 1.46 J 174 <1.1 NS 1.54 J 1.50 J
Copper (Total)µg/l 31 10 1,000 <1.6 1.63 J <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 NS <1.6 <1.6
Lead (Total)µg/l 54 10 15 <3.1 <3.1 <3.1 <3.1 <3.1 <3.1 <3.1 3.15 J <3.1 <3.1 <3.1 <3.1 <3.1 NS <3.1 <3.1
Nickel (Total)µg/l 34 50 100 7.06 J <2.2 <2.2 75.4 10.2 J <2.2 14.4 J 137 <2.2 14.4 J 2.36 J 76.5 <2.2 NS <2.2 <2.2
Thallium (Total)µg/l 0.72 5.5 0.28*0.249 J <0.11 <0.11 0.201 J 0.114 J 0.116 J 0.196 J 0.928 J <0.11 <0.11 <0.11 0.147 J <0.11 NS <0.11 <0.11
Vanadium (Total)µg/l 100 25 0.3*2.44 J 2.73 J <1.4 <1.4 1.88 J <1.4 <1.4 <1.4 <1.4 <1.4 <1.4 <1.4 <1.4 NS <1.4 <1.4
Zinc (Total)µg/l 64 10 1,000 7.62 J 151 <4.4 112 38.8 <4.4 126 67.7 <4.4 <4.4 <4.4 116 <4.4 NS 7.47 J 7.73 J
NOTES:
Samples were collected on January 18 and 19, 2016 and analyzed by Environmental Conservation Laboratories, Inc. (ENCO). Detection limits are shown on laboratory reports.
Values which are BOLD indicate levels above laboratory detection limits.
Values which are BOLD and shaded indicate levels above their respective NCDENR 2L or GWPST.
DAF Computation = Dilution/Attenuation Factor Computation (ref. S&ME Alternate Source Demonstration, June 2008).
2L STANDARD = North Carolina groundwater standards as promulgated by 15A North Carolina Administrative Code, Subchapter 2L (April 1, 2013).
SWSL = Solid Waste Section Limit. (ref. NCDENR-DWM, Solid Waste Section February 23, 2007 memorandum)
* Indicates there is currently no 2L Standard. The target analyte was compared to the Solid Waste Groundwater Protection Standard (GWPST).
J = Analyte detected, but below the laboratory reporting limit therefore the result is an estimated concentration.
D = The sample was analyzed at dilution.
NS = Not Sampled for this parameter.
NE = Not Established
µg/L = Micrograms Per Liter
VOCs = Volatile Organic Compounds
Duplicate sample collected from monitor well MW-5.
Appendix I compounds not shown were not detected during this sampling event. See Appendix I of the report for laboratory reports.
SURFACE WATER
Table 3
Groundwater Quality Summary
Edgecombe County Landfill
January 18 asnd 19, 2016 Sampling Event
S&ME Project No. 4305-15-172
COMPLIANCE MONITOR WELLS SURFACE WATER2L
STANDARD or
GWPST
APPENDIX I VOCs EPA METHOD
8260B
2L STANDARD
OR GWPST
QUALITY CONTROL
UNITS
QUALITY CONTROL
UNITS
BACKGROUND MONITOR
WELLS
BACKGROUND MONITOR
WELLS COMPLIANCE MONITOR WELLS
SWSL
SWSL
Expected Metals
Concentration
in Groundwater
from DAF
Computation
Edgecombe County Landfill, Tarboro, NC
S:\ENVIRON...\January 2016 Sample Tables
Existing Well/Piezometer Construction Details
Edgecombe County Landfill
January 18 and 19, 2016 Sampling Event
S&ME Project No. 4305-15-172
Well ID Reason for Well Northing Easting
TOC
ELEV
(FT-MSL)
TOG
ELEV
(FT-MSL)
Protective
Casing
Diameter
Protective
Casing
Type
Protective
Casing
Interval
Riser/Screen
Diameter Riser Type Riser
Interval
Grout Type
(Portland)
Grout
Interval Seal Type Seal Interval Filter
Pack Type
Filter Pack
Interval
Screen
Interval
MW-3B Corrective Measures Analysis/Water Levels 757,035.00 2,424,650.53 81.18 79.01 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 5.5 ft.Type II Cement 0.0 - 3.5 ft.Hydrated Bentonite 3.5 - 4.5 ft.#2 Sand 4.5 - 21.5 ft.5.5 - 20.5 ft.
MW-4 Background Analyses/Water Levels 757,264.82 2,425,621.06 68.95 66.77 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 3.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.0 ft.#2 Sand 2.0 - 18.0 ft.3.0 - 18.0 ft.
MW-5 Compliance Analyses/Water Levels 758,410.72 2,425,211.43 53.75 51.89 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 7.0 ft.Type II Cement 0.0 - 4.7 ft.Hydrated Bentonite 4.7 - 6.3 ft.#2 Sand 6.3 - 23.0 ft.7.0 - 22.0 ft.
MW-5D Water Levels 758,426.83 2,425,215.75 52.08 50.45 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 30.0 ft.Type II Cement 0.0 - 6.0 ft.Hydrated Bentonite 6.0 - 8.0 ft.#2 Sand 8.0 - 40.0 ft.30.0 - 40.0 ft.
MW-5S Water Levels 758,446.42 2,425,216.28 50.54 47.04 4.0 in.Stick-Up ~3.5 2.0 in.Sch 40 PVC 0.0 - 5.0 ft.Type II Cement 0.0 - 3.0 ft.Hydrated Bentonite 3.0 - 4.0 ft.#2 Sand 4.0 - 10.0 ft.5.0 - 10.0 ft.
MW-6 Compliance Analyses/Water Levels 758,561.81 2,424,535.52 46.29 44.04 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 2.5 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.0 ft.#2 Sand 2.0 - 18.0 ft.2.5 - 17.5 ft.
MW-7A Corrective Measures Analyses/Water Levels 758,507.52 2,423,684.90 68.43 66.49 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 15.0 ft.Type II Cement 0.0 - 11.0 ft.Hydrated Bentonite 11.0 - 13.0 ft.#2 Sand 13.0 - 25.0 ft.15.0 - 25.0 ft.
MW-8A Water Levels 757,284.68 2,423,303.30 82.34 79.96 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 10.0 ft.Type II Cement 0.0 - 6.0 ft.Hydrated Bentonite 6.0 - 8.0 ft.#2 Sand 8.0 - 20.0 ft.10.0 - 20.0 ft.
MW-9 Background Analyses/Water Levels 757,217.12 2,422,945.48 72.41 70.56 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 5.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 3.0 ft.#2 Sand 3.0 - 15.0 ft.5.0 - 15.0 ft.
MW-10 Water Levels 757,012.80 2,423,318.48 75.78 74.21 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 2.0 ft.Type II Cement 0.0 - 0.5 ft.Hydrated Bentonite 0.5 - 1.5 ft.#2 Sand 1.5 - 12.0 ft.2.0 - 12.0 ft.
MW-12 Compliance Analyses/Water Levels 758,719.269 2,424,158.858 51.24 48.56 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 5.0 ft.Type II Cement 0.0 - 0.5 ft.Hydrated Bentonite 0.5 - 3.0 ft.#2 Sand 3.0 - 10.5 ft.5.0 - 10.0 ft.
MW-13 Corrective Measures Analyses/Water Levels 758,368.437 2,424,838.011 54.99 51.99 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 10.0 ft.Type II Cement 0.0 - 6.0 ft.Hydrated Bentonite 6.0 - 7.7 ft.#2 Sand 7.7 - 20.0 ft.10.0 - 20.0 ft.
MW-14 Corrective Measures Analyses/Water Levels 758,580.141 2,425,115.431 43.88 41.25 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 7.0 ft.Type II Cement 0.0 - 3.7 ft.Hydrated Bentonite 3.7 - 5.0 ft.#2 Sand 5.0 - 12.5 ft.7.0 - 12.0 ft.
MW-15 Corrective Measures Analyses/Water Levels 758,398.745 2,425,329.020 44.87 42.20 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 6.6 ft.Type II Cement 0.0 - 3.5 ft.Hydrated Bentonite 3.5 - 5.0 ft.#2 Sand 5.0 - 12.0 ft.6.6 - 11.6 ft.
MW-16 Corrective Measures Analyses/Water Levels 758,421.541 2,425,905.658 46.58 43.73 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 7.0 ft.Type II Cement 0.0 - 5.0 ft.Hydrated Bentonite 5.0 - 6.0 ft.#2 Sand 6.0 - 17.3 ft.7.0 - 17.0 ft.
GW-1R Methane Gas Monitoring 757,029.14 2,424,642.63 81.08 79.25 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 3.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.0 ft.#2 Sand 2.0 - 8.0 ft.3.0 - 8.0 ft.
GW-2R Methane Gas Monitoring 757,037.57 2,425,099.41 75.72 73.84 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 3.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.0 ft.#2 Sand 2.0 - 8.0 ft.3.0 - 8.0 ft.
GW-3 Methane Gas Monitoring 757,263.55 2,425,617.95 69.00 66.78 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 2.0 ft.Type II Cement 0.0 - 0.5 ft.Hydrated Bentonite 0 #2 Sand 0.5 - 3.0 ft.2.0 - 3.0 ft.
GW-4 Methane Gas Monitoring 757,480.62 2,425,833.83 69.93 67.88 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 5.0 ft.Type II Cement 0.0 - 0.5 ft.Hydrated Bentonite 0 #2 Sand 0.5 - 10.0 ft.5.0 - 10.0 ft.
GW-5 Methane Gas Monitoring 757,932.48 2,425,852.83 65.23 63.16 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 5.0 ft.Type II Cement 0.0 - 0.5 ft.Hydrated Bentonite 0 #2 Sand 0.5 - 10.0 ft.5.0 - 10.0 ft.
GW-6 Methane Gas Monitoring 756,992.92 2,424,102.59 79.02 77.38 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 3.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.0 ft.#2 Sand 2.0 - 8.0 ft.3.0 - 8.0 ft.
GW-7 Methane Gas Monitoring 757,013.93 2,423,549.98 75.02 73.41 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 3.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.0 ft.#2 Sand 2.0 - 8.0 ft.3.0 - 8.0 ft.
GW-8 Methane Gas Monitoring 757,000.52 2,422,862.84 79.92 78.08 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 3.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.0 ft.#2 Sand 2.0 - 8.0 ft.3.0 - 8.0 ft.
GW-9 Methane Gas Monitoring 757,579.04 2,423,113.15 72.69 NS 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 3.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.0 ft.#2 Sand 2.0 - 8.0 ft.3.0 - 8.0 ft.
GW-10 Methane Gas Monitoring 758,018.15 2,423,322.02 69.17 67.16 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 3.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.0 ft.#2 Sand 2.0 - 8.0 ft.3.0 - 8.0 ft.
GW-11 Methane Gas Monitoring 758,455.00 2,423,536.98 64.19 62.51 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 3.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.0 ft.#2 Sand 2.0 - 8.0 ft.3.0 - 8.0 ft.
P-1 Water Levels 757,088.75 2,425,176.72 74.48 72.52 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 10.0 ft.Type II Cement 0-0.5 Hydrated Bentonite 0 #2 Sand 0.5 - 20.0 ft.10.0 - 20.0 ft.
P-2A Water Levels 757,183.97 2,424,154.11 83.61 81.44 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 15.0 ft.Type II Cement 0.0 - 11.0 ft.Hydrated Bentonite 11.0 - 13.0 ft.#2 Sand 13.0 - 30.0 ft.15.0 - 25.0 ft.
P-3A Water Levels 757,797.19 2,423,482.12 79.77 77.60 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 15.0 ft.Type II Cement 0.0 - 11.0 ft.Hydrated Bentonite 11.0 - 13.0 ft.#2 Sand 13.0 - 25.0 ft.15.0 - 25.0 ft.
P-12 Water Levels 758,715.746 2,425,310.624 54.15 49.40 4.0 in.Stick-Up ~2 to +2 BGS 1.0 in.Sch 40 PVC 0.0 - 4.17 ft Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 3.17 ft.#2 Sand 3.17 - 9.17 ft.4.17 - 9.17 ft.
P-15 Water Levels 758,689.738 2,425,858.299 45.16 41.80 4.0 in.Stick-Up ~2 to +2 BGS 1.0 in.Sch 40 PVC 0.0 - 2.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 1.0 ft.#2 Sand 1.0 - 7.0 ft.2.0 - 7.0 ft.
P-17 Water Levels 758,437.412 2,426,190.771 42.45 40.00 4.0 in.Stick-Up ~2 to +2 BGS 1.0 in.Sch 40 PVC 0.0 - 2.7 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 1.70 ft.#2 Sand 1.7 - 7.7 ft.2.7 - 7.7 ft.
P-18 Water Levels 758,158.567 2,426,102.144 54.44 51.00 4.0 in.Stick-Up ~2 to +2 BGS 1.0 in.Sch 40 PVC 0.0 - 10.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 9.0 ft.#2 Sand 9.0 - 15.0 ft.10.0 - 15.0 ft.
P-19 Water Levels 757,756.845 2,426,403.572 58.88 59.00 8.0 in Flush ~0 to .75 BGS 1.0 in.Sch 40 PVC 0.0 - 7.67 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 5.67 ft.#2 Sand 5.67 - 17.67 ft.7.67 - 17.67 ft.
P-25 Water Levels 757,206.647 2,423,633.029 80.57 77.60 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 5.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 3.0 ft.#2 Sand 3.0 - 10.0 ft.5.0 - 10.0 ft.
P-26 Water Levels 757,554.222 2,423,325.095 80.33 77.20 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 10.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 7.0 ft.#2 Sand 7.0 - 15.0 ft.10.0 - 15.0 ft.
P-29 Water Levels 757,952.042 2,424,421.307 65.29 62.10 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 5.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 2.5 ft.#2 Sand 2.5 - 10.0 ft.5.0 - 10.0 ft.
P-34 Corrective Measures Analyses/Water Levels 758,455.766 2,425,359.738 44.34 41.30 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 5.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 3.0 ft.#2 Sand 3.0 - 10.0 ft.5.0 - 10.0 ft.
P-35 Water Levels 758,605.177 2,425,152.817 44.50 41.40 4.0 in.Stick-Up ~2 to +2 BGS 2.0 in.Sch 40 PVC 0.0 - 5.0 ft.Type II Cement 0.0 - 1.0 ft.Hydrated Bentonite 1.0 - 3.0 ft.#2 Sand 3.0 - 10.0 ft.5.0 - 10.0 ft.
Notes:
TOC = Top of Casing
TOG = Top of Ground
FT-MSL = Feet Above Mean Sea Level
BGS = Below Ground Surface
N/A = Not Applicable
NS = Not Surveyed
Monitor wells MW-1A through MW-10 and Gas wells GW-1 through GW-11 surveyed by Spruill & Associates on May 26, 2002.
Spruill & Associates surveyed piezometers P-1 through P-3A on May 26, 2002, P-4 through P-20 in December 2004, and P-21 through P-38 in September 2007.
Well locations shown on Figure 2.
Table 4
Appendices
Appendix I – Field Notes
Appendix II – Report of Laboratory Analyses
Appendix III – Compact Disk with Electronic Copy of
Historical Analytical Results (.xls) and Electronic Copy of this
Report
Appendix IV – Groundwater Velocity Calculations
JOB NO.
SHEET NO.
DATE
JOB NAME
SUBJECT
PURPOSE:
To determine the average true hydraulic gradient.
GIVEN:Well GW Elev
MW-3B 74.76
MW-5 43.35
MW-7A 55.10
P-1 68.87
CALCULATION:
Calculate the average of three point solutions using wells MW-5, MW-7A, MW-3B or P-1.
GRADIENT:
Where:i =Hydraulic Gradient (ft/ft)
i = h1 – h2 h1 - h2 =Difference in Hydraulic Head (ft)
L L =Distance Along Flow Path (ft)
Where distance between h1 and h2 is parallel to flow, determined by projection from 3 point problem.
i1 = MW-3B – MW-5 74.76 -43.35 =0.02115 ft/ft
L1
Use Elevation of Groundwater at MW-7A to establish 55.10' elevation between MW-3B and MW-5.
74.76 -55.10 =929.48 ft
Draw line from MW-7A to point located 929.48 feet from MW-3B to MW-5.
Measure the distance from new 55.10' contour line to MW-5 (Line perpendicular from contour to MW-5)
i1 = MW-7A – MW-5 55.1 -43.35 =0.02098 ft/ft
New L1
=0.02098 ft/ft
i2 = P-1 – MW-5 68.87 -43.35 =0.01933 ft/ft
L2
Use Elevation of Groundwater at MW-7A to establish 55.10' elevation between P-1 and MW-5.
68.87 -55.1 =712.24 ft
Draw line from MW-7A to point located 712.24 feet from P-1 to MW-5.
Measure the distance from new 55.10' contour line to MW-5 (Line perpendicular from contour to MW-5)
i2 = MW-7A – MW-5 55.1 -43.35 =0.02136 ft/ft
New L2
=0.02136 ft/ft
AVERAGE TRUE HYDRAULIC GRADIENT, iAVG =0.0212 ft/ft
CONCLUSION:
The Average True Hydraulic gradient, iAVG equals 0.0212 ft/ft.
gradient (P-1 and MW-5)
True Hydraulic Gradient, i2
True Hydraulic Gradient, i1
=P-1 - MW-7A
=
=
=
550
560
1,320
gradient (MW-3B and MW-5)
MW-3B - MW-7A
Edgecombe County Landfill
Hydraulic Gradient
0.02115
=
=
0.019333
4305-15-172
2/10/2016
1 of 1
CHECKED BY SPW
COMPUTED BY CBI/JA
1,485
JOB NO.
SHEET NO.
DATE
JOB NAME
SUBJECT
PURPOSE:
To determine the average groundwater flow velocity.
CALCULATION:
V = Ki
n
Where:V =Average Linear Groundwater Flow Velocity (feet/year = ft/yr)
K =Hydraulic Conductivity (ft/yr)
i =Average True Hydraulic Gradient (ft/ft)
n =Effective Soil Porosity (percent)
5.95E-05 cm/sec
5.95E-05 *1.9685
=0.00011713 ft/min
Convert KA ZONE from ft/min to ft/yr =0.00011713 ft/min *1440 min/day
=0.16866108 ft/day *365 day/yr
=61.561 ft/year
Average True Gradient, iAVG (MW-3B to MW-5):0.0212 ft/ft
n:15%
V = KA ZONE i
n
V = 61.561 ft/yr * 0.0197 ft/ft = 8.7007 ft/yr
0.15
CONCLUSION:
The average groundwater flow velocity, V, equals 8.7007 ft/yr.
Edgecombe County Landfill
4305-15-172
1 of 1
2/10/2016
COMPUTED BY CBI/JA
Velocity Calculation
KA ZONE =
Convert KA ZONE from cm/sec to ft/min =
CHECKED BY SPW
Appendix V – Time Series Graphs for Monitor Wells