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FIRST SEMIANNUAL REPORT OF 2018
TOWN OF SOUTHOLD LANDFILL
POST CLOSURE GROUNDWATER MONITORING PROGRAM
Prepared for:
TOWN OF SOUTHOLD
SOLID WASTE MANAGEMENT DISTRICT
CUTCHOGUE, SUFFOLK COUNTY, NEW YORK
Prepared by:
D&B ENGINEERS AND ARCHITECTS, P.C
WOODBURY, NEW YORK
AUGUST 2018
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FIRST SEMIANNUAL REPORT OF 2018
TOWN OF SOUTHOLD LANDFILL
POST CLOSURE GROUNDWATER MONITORING PROGRAM
TABLE OF CONTENTS
Section Title Page
1.0 INTRODUCTION....................................................................................................... 1-1
2.0 SAMPLING PROCEDURES AND ANALYSES .................................................... 2-1
2.1 Groundwater Level Measurement Procedures .................................................. 2-1
2.2 Groundwater Sampling Procedures .................................................................. 2-1
2.3 Sample Analyses ............................................................................................... 2-3
3.0 GROUNDWATER LEVEL MEASUREMENTS .................................................... 3-1
4.0 DISCUSSION OF RESULTS .................................................................................... 4-1
4.1 Data Validation ................................................................................................. 4-1
4.2 Groundwater Results ......................................................................................... 4-2
4.2.1 Field Parameters ................................................................................... 4-2
4.2.2 Volatile Organic Compounds ............................................................... 4-3
4.2.3 Inorganic Parameters (Metals) .............................................................. 4-4
4.2.4 Leachate Indicators ............................................................................... 4-5
5.0 CONCLUSIONS AND RECOMMENDATIONS ................................................... 5-1
List of Appendices
Groundwater Analytical Results ...................................................................................A
Groundwater Sampling Logs ........................................................................................B
Chain of Custody Forms ...............................................................................................C
Data Validation Check List ..........................................................................................D
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TABLE OF CONTENTS (continued)
List of Figures
1-1 Site Location Map .............................................................................................1-2
2-1 Groundwater Monitoring Well Location Map ..................................................2-2
List of Tables
3-1 Groundwater Level Data June 26, 2018 .......................................................3-2
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1.0 INTRODUCTION
The Town of Southold has retained D&B Engineers and Architects, P.C. (D&B) to
perform post-closure groundwater monitoring and reporting for the closed and capped municipal
solid waste (MSW) landfill in Cutchogue, New York (i.e. the Site). The location of the Site is
shown in Figure 1-1. This report is for the First Semiannual 2018 groundwater monitoring event,
conducted on June 26, 2018 and describes the work performed and the results obtained. The
groundwater monitoring wells were sampled in strict conformance with the Quality
Assurance/Quality Control (QA/QC) Plan, which is part of the Post Closure Monitoring and
Maintenance Manual, dated August 2003.
In the past, groundwater sampling was performed quarterly, with three rounds analyzed
for New York Codes, Rules and Regulations (NYCRR) Part 360 Routine Parameters and one
round analyzed for 6NYCRR Part 360 Baseline Parameters on a rotating basis. In the Spring of
2015, on behalf of the Town of Southold, D&B proposed modifications to the New York State
Department of Environmental Conservation (NYSDEC) pertaining to the sampling frequency
and analyses for the Post-Closure Groundwater Monitoring Program for the Site. The request for
these modifications was approved by the NYSDEC on July 2, 2015.
Commencing with the Second Semiannual 2015 groundwater monitoring event,
modifications to the Post-Closure Groundwater Monitoring Program included:
A reduction in sampling frequency from quarterly to semiannually for all well
clusters (MW-1, MW-3, MW-4, MW-5, MW-6 and MW-8); and
Groundwater analysis for 6NYCRR Part 360 Baseline Parameters for both
semiannual sampling events.
This report is organized into the following sections: Section 2.0 (Sampling Procedures
and Analyses) describes the water level measurements and groundwater sampling procedures, as
well as the groundwater analyses; Section 3.0 (Groundwater Level Measurements) summarizes
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1-1
Long Island
NN
Sound
Southold
48
25
Great Peconic
Bay
SOUTHOLD LANDFILL
CUTCHOGUE, NEW YORK
SITE LOCATION MAP
Figure 1-1
3753 -Site Location Map.indd (04/29/16 - 2:54 PM)
the groundwater level measurements and groundwater elevations; Section 4.0 (Discussion of
Results) summarizes the key findings from this groundwater monitoring event, including
comparison of the laboratory results to NYSDEC Class GA Groundwater Standards and
Guidance Values; and Section 5.0 (Conclusions and Recommendations) provides conclusions
and recommendations based on the first semiannual 2018 results.
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1-3
2.0 SAMPLING PROCEDURES AND ANALYSES
monitoring wells (MW-1S, MW-1D, MW-3S, MW-3D, MW-4S, MW-4D, MW-5S, MW-5D,
MW-6S, MW-6D, MW-8S and MW-8D) on June 26, 2018 as part of the First Semiannual 2018
groundwater monitoring event. A site plan showing the locations of the monitoring wells is
provided in Figure 2-1. The following sections provide a brief discussion of the procedures used
during groundwater level measurements, groundwater sampling and sample analysis.
2.1 Groundwater Level Measurement Procedures
Prior to sampling, water level measurements were obtained from the 12 monitoring wells
to determine the volume of standing water in the well for purposes of purging, as well as for
determination of groundwater elevations and flow direction. Groundwater level measurements
were obtained from a surveyed measuring point on each well utilizing a decontaminated
electronic water level indicator to an accuracy of 0.01 foot. A discussion regarding groundwater
level measurements and groundwater flow direction is provided in Section 3.0.
2.2 Groundwater Sampling Procedures
Sampling procedures for the collection of the groundwater samples were implemented in
accordance with the protocol described in the Quality Assurance/Quality Control (QA/QC) Plan,
which is part of the Post Closure Monitoring and Maintenance Manual, dated August 2003.
Field decontamination was performed between sampling locations for non-disposable equipment.
Prior to collecting groundwater samples, the 12 monitoring wells were purged to remove
the standing water in each well. Well purging was accomplished by first measuring the static
water level in the well and then calculating the volume of standing water. A decontaminated
submersible pump was used to purge the water from the well. Decontamination of the
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2-1
submersible pump used for well purging was performed in accordance with the procedure
described in the QA/QC Plan.
During the purging process, groundwater was monitored and recorded for the following
field parameters: pH, temperature, specific conductance, oxidation reduction potential (ORP),
dissolved oxygen and turbidity. When the values of the field parameters stabilized to within 10%
based on the last two readings, the turbidity of the groundwater was less than 50 Nephelometric
Turbidity Units (NTUs) and at least three well volumes had been removed, well purging was
considered complete.
In accordance with the QA/QC Plan, groundwater samples were collected using new,
dedicated, disposable polyethylene bailers and polypropylene rope. Samples for VOC analysis
were collected first, followed by inorganic parameters and leachate indicators. Each sample was
labeled with the well number, time and date, and stored in an ice-filled cooler with the chain of
custody forms and shipped to the laboratory (ALS Environmental).
Appropriate quality assurance/quality control (QA/QC) samples, which included matrix
spike and matrix spike duplicate (MS/MSD) sets and a trip blank were collected in accordance
with the QA/QC Plan.
Tables summarizing the analytical results are provided in Appendix A and are discussed
in Section 4.0. Groundwater sampling logs for the First Semiannual 2018 groundwater
monitoring event are provided in Appendix B, and the chain of custody forms are provided in
Appendix C.
2.3 Sample Analyses
Groundwater samples collected during the First Semiannual 2018 groundwater
monitoring event from the 12 monitoring wells were analyzed for 6NYCRR Part 360 Baseline
Parameters. Laboratory analyses were performed by ALS Environmental, located in Rochester,
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New York. This laboratory is approved under the New York State Department of Health
Environmental Laboratory Approval Program (ELAP) for the analyses performed.
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3.0 GROUNDWATER LEVEL MEASUREMENTS
Groundwater level measurements were collected by D&B on June 26, 2018 from the 12
groundwater monitoring wells as part of the First Semiannual 2018 groundwater monitoring
event. The groundwater level measurements from the monitoring wells are summarized in
Table 3-1.
As shown in Table 3-1, water
ranged from 7.73 feet above mean sea level (MSL) in well MW-1S, located on the south end of
the Site, to 5.61 feet above MSL in well MW-8S, located on the west side of the Site. Well
MW-8S exhibits a lower water table elevation in comparison to the closest shallow wells
MW-4S and MW-6S. The lower water table elevation at well MW-8S may be due to reduced
groundwater recharge in close proximity to the capped landfill. Based upon the June 26, 2018
groundwater level measurements and calculated water table elevations, groundwater flow
direction was determined to be in a north-northwesterly direction. Therefore, well cluster MW-1
is located upgradient of the Site, and the other wells are located along the downgradient
boundary of the Site.
generally
consistent with the shallow well water table elevations, except for well MW-8D, and indicate
virtually no vertical hydraulic gradient throughout the landfill site. An upward vertical hydraulic
gradient is indicated at well cluster MW-8, due to the lower water table elevation.
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3-1
Table 3-1
SOUTHOLD LANDFILL
FIRST SEMIANNUAL 2018 GROUNDWATER MONITORING EVENT
MONITORING WELL GROUNDWATER ELEVATION MEASUREMENTS
JUNE 26, 2018
Measuring Point Depth to Water from
Elevation Measuring Point Groundwater Elevation
Well Designation (feet above msl) (feet) (feet above msl)
37.10 7.73
MW-1S 44.83
MW-1D 37.00 7.88
44.88
MW-3S 42.75 6.75
49.50
MW-3D 42.46 6.73
49.19
MW-4S 56.80 6.23
63.03
MW-4D 56.66 6.26
62.92
MW-5S 61.95 6.19
68.14
MW-5D 61.45 6.19
67.64
MW-6S 48.95 6.82
55.77
48.92 6.79
MW-6D 55.71
48.55 5.61
MW-8S 54.16
47.40 7.89
MW-8D 55.29
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3-2
4.0 DISCUSSION OF RESULTS
4.1 Data Validation
Twelve groundwater samples and one trip blank were collected on June 26, 2018 as part
of the First Semiannual 2018 groundwater monitoring event performed at the Town of Southold
Landfill. All samples were analyzed for the 6NYCRR Part 360 Baseline Parameters, including
volatile organic compounds (VOCs), inorganic parameters (metals) and leachate indicators.
Sample analysis was performed in accordance with SW-846 methods. The laboratory analyses
were performed by ALS Environmental, located in Rochester, New York and reported in data
package R1806003.
The data package submitted by the analytical laboratory was validated in accordance with
NYSDEC quality assurance/quality control (QA/QC) requirements, the contract requirements
and Part 360. All samples were analyzed within the method specified holding times except where
noted below. The following requirements were outside limits and required qualification of the data:
Acetone was detected in the trip blank and was qualified as non-detect (UB) in
groundwater samples MW-3D, MW-4D, MW-8S and MW-8D.
Hexavalent chromium in groundwater samples MW-3S, MW-3D, MW-4D, MW-6D,
MW-6S, MW-8D and MW-8S was analyzed outside its holding time of 24 hours after
collection. As a result, hexavalent chromium was qualified as estimated (UJ) in these
samples.
The percent recovery (%R) was below the QC limits for chloride, chemical oxygen
demand and hexavalent chromium in the matrix spike. As a result, these parameters
were qualified as estimated (J/UJ) in all samples.
No other issues were identified with the sample results and all results are deemed valid
and usable for environmental assessment purposes, as qualified above. Data validation checklists
completed for the First Semiannual 2018 groundwater monitoring event conducted on June 26,
2018 are provided in Appendix D.
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4.2 Groundwater Results
The laboratory results for the First Semiannual 2018 groundwater monitoring event are
summarized on Table A-1 through Table A-3 in Appendix A and compared to the New York
State Department of Environmental Conservation Ambient Water Quality Standards and
Guidance Values for Class GA groundwater (herein referred to as the Class GA groundwater
standards and guidance values). Table A-1 provides the VOC results, Table A-2 the inorganic
parameters (metals) results and Table A-3 the leachate indicator results. Field parameters
measured during the groundwater purging process are presented on the groundwater sampling
logs in Appendix B. A discussion of the field parameters and each analytical parameter group is
provided below.
4.2.1 Field Parameters
A review of the field parameters collected immediately prior to collection of the
groundwater samples, provided on the groundwater sampling logs in Appendix B, indicates the
following key findings:
Conductivity values were highest in deep wells located downgradient of the Site,
including wells MW-3D, MW-4D, MW-5D and MW-8D. The higher conductivity
values appear to be Site-related. There is no Class GA standard or guidance value for
conductivity.
Groundwater temperatures were approximately 1 to 2 degrees Celsius higher in the
majority of the downgradient wells, relative to the upgradient wells. The highest
temperatures were recorded in well clusters MW-3, MW-4 and MW-8. There is no
Class GA standard or guidance value for temperature.
Groundwater pH was lower than the minimum Class GA groundwater standard of 6.5
in upgradient well MW-1S and in 3 downgradient wells. The results are consistent
with the naturally low pH of Long Island groundwater. Groundwater pH was
typically higher in the deep well at each well cluster, including the upgradient deep
well.
A Dissolved Oxygen (DO) reading of 0 was obtained for all monitoring wells, except
for upgradient shallow well MW-1S (7.85 mg/l) and deep downgradient well MW-4D
(0.34 mg/l). There is no Class GA standard or guidance value for DO.
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The Oxidation-Reduction Potential (ORP) of groundwater was positive in all
monitoring wells, indicating generally oxidizing conditions. There is no Class GA
standard or guidance value for ORP. The lowest ORP values were observed in well
clusters MW-3 and MW-8.
The groundwater samples collected from the 12 Site monitoring wells were observed
to be clear, and did not have a noticeable odor.
Light non-aqueous phase liquid (LNAPL) or dense non-aqueous phase liquid
(DNAPL) was not noted in any of the groundwater samples collected from the 12 Site
monitoring wells.
Overall, the field parameter results obtained during the First Semiannual 2018
groundwater monitoring event are consistent with previous sampling events and are indicative of
limited leachate impacts, typical of a closed municipal solid waste (MSW) landfill. The leachate-
related impacts are relatively minor in magnitude and limited to higher conductivity and
temperature, and lower DO and ORP in certain downgradient wells.
4.2.2 Volatile Organic Compounds
Review of the VOC results provided on Table A-1 in Appendix A indicates the
following key findings:
VOCs were not detected in upgradient well cluster MW-1.
Five out of the ten downgradient monitoring wells (shallow wells MW-3S and MW-
8S, and deep wells MW-4D, MW-5D and MW-8D) exhibited a limited number of
VOCs at concentrations marginally above their respective Class GA groundwater
standards, including: 1,2,3-trichloropropane in MW-3S; 1,2-dichloroethane
(1,2-DCA) and 1,2-dichloropropane in MW-4D and MW-8D; 1,2-dichloropropane
and chlorobenzene in MW-5D; and chlorobenzene in MW-8S.
Of the VOCs detected in exceedance of the Class GA standards, the highest
concentration was chlorobenzene, detected in MW-8S at a concentration of 14 ug/l,
above its Class GA groundwater standard of 5 ug/l.
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4-3
In general, the VOC results for the First Semiannual 2018 groundwater monitoring event
are consistent with previous sampling events. Based on these results, the Site is not a significant
source of VOC contaminants in groundwater.
4.2.3 Inorganic Parameters (Metals)
Review of the inorganic parameter (metals) results provided on Table A-2 in Appendix
A indicates the following key findings:
Iron, magnesium, manganese and sodium were detected above their respective Class
GA groundwater standards/guidance values in one or more downgradient wells.
Inorganic parameters were not detected above Class GA groundwater
standards/guidance values in upgradient wells.
- Iron was detected above the Class GA groundwater standard of 300 ug/l in 5
downgradient wells (MW-3S, MW-3D, MW-4D, MW-8S and MW-8D). These
iron concentrations ranged from 324 ug/l in deep well MW-4D to a maximum of
114,000 ug/l in shallow well MW-3S.
- Magnesium was detected above the Class GA guidance value of 35,000 ug/l in
deep downgradient well MW-4D, at a concentration of 58,900 ug/l. At each well
cluster, higher magnesium concentrations were detected in the deep well, which
suggests that the detected magnesium concentrations may be partly associated
with naturally saline groundwater conditions at depth.
- Manganese was detected above the Class GA groundwater standard of 300 ug/l in
9 of the 10 downgradient wells, with the exception of shallow well MW-5S.
Manganese concentrations in these wells ranged from 966 ug/l in shallow well
MW-6S to a maximum of 9,950 ug/l in deep well MW-5D.
- Sodium was detected above the Class GA groundwater standard of 20,000 ug/l in
6 downgradient wells (MW-3S, MW-3D, MW-4D, MW-5D, MW-8S and MW-
8D). Sodium concentrations in these wells ranged from 22,600 ug/l in shallow
wells MW-3S and MW-8S to a maximum of 173,000 ug/l in deep well MW-4D.
At each well cluster, higher sodium concentrations were detected in the deep well,
which suggests that the detected sodium concentrations may be partly associated
with naturally saline groundwater conditions at depth.
- Although chromium was detected above the Class GA groundwater standard of
50 ug/l in 3 wells during the previous December 2017 sampling event, it was not
detected during the current June 2018 sampling event.
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4-4
In general, the inorganic parameter results for the First Semiannual 2018 groundwater
monitoring event are consistent with previous sampling events and are indicative of limited
leachate impacts, typical of a closed MSW landfill. Groundwater in the North Fork of Long
Island is also naturally saline at depth, which may contribute to the higher concentrations of
some inorganic parameters observed in the deep wells.
4.2.4 Leachate Indicators
Review of the leachate indicator results provided on Table A-3 in Appendix A indicates
the following key findings:
Ammonia, chloride, nitrate and phenols were detected above their respective Class
GA groundwater standards in one or more downgradient wells. Leachate indicators
were not detected above Class GA groundwater standards/guidance values in
upgradient wells.
- Ammonia was detected above the Class GA groundwater standard of 2 mg/l in 6
downgradient monitoring wells (MW-3S, MW-3D, MW-4D, MW-5D, MW-8S
and MW-8D). Ammonia concentrations in these wells ranged from 4.85 mg/l in
shallow well MW-3S to a maximum of 61.6 mg/l in deep well MW-5D.
- Chloride was detected above the Class GA groundwater standard of 250 mg/l in
deep well MW-4D at a concentration of 264 mg/l. At each well cluster, higher
chloride concentrations were detected in the deep well, which suggests that the
detected chloride concentrations may be partly associated with naturally saline
groundwater conditions at depth.
- Nitrate was detected above the Class GA groundwater standard of 10 mg/l in
shallow well MW-4S at a concentration of 37 mg/l.
- Phenols were detected above the Class GA groundwater standard of 0.001 mg/l in
deep well MW-5D at a concentration of 0.0055 mg/l.
In general, the leachate indicator results for the First Semiannual 2018 groundwater
monitoring event are consistent with previous sampling events and are indicative of limited
leachate impacts, typical of a closed MSW landfill. Groundwater in the North Fork of Long
Island is also naturally saline at depth, which may contribute to the higher concentrations of
some leachate indicators observed in the deep wells.
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5.0 CONCLUSIONS AND RECOMMENDATIONS
Based on the results of the First Semiannual 2018 groundwater monitoring event, D&B
concludes the following:
Water level elevations, horizontal and vertical hydraulic gradients, and groundwater
flow directions are consistent with previous results and local/regional hydrogeologic
conditions.
In general, groundwater quality is consistent with previous sample results and are
indicative of limited downgradient leachate impacts, typical of a closed MSW
landfill.
A portion of the elevated concentrations detected in downgradient deep wells may be
related, in part, to naturally saline groundwater conditions at depth.
The NYSDEC has previously approv
scope and frequency of post-closure monitoring to semiannually for Part 360 Baseline
Parameters. The First Semiannual 2018 results discussed in this report are generally consistent
with previous sampling events and do not indicate any significant changes or deterioration in
groundwater quality that would warrant a change in the scope of the monitoring program.
Therefore, the monitoring reduction approved by NYSDEC should be continued.
The next monitoring round (Second Semiannual 2018 groundwater monitoring event) is
scheduled to be conducted in the fourth quarter of 2018 for Part 360 Baseline Parameters.
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5-1
APPENDIX A
GROUNDWATER ANALYTICAL RESULTS
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APPENDIX B
GROUNDWATER SAMPLING LOGS
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APPENDIX C
CHAIN OF CUSTODY FORMS
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010,011,012,013,014,015,016,
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APPENDIX D
DATA VALIDATION CHECK LIST
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DATA VALIDATION AND
QUALIFICATION SUMMARY Laboratory Numbers: R1806003
Sample ID Anal e s Qualifier Reason s
VOCs
MW-31),MW-41),MW-8S and Acetone UB Detected in the Trip Blank
MW-8D.
Metals
No qualification of the data was
necessary.
General Chemistry
MW-3S, MW-31), MW-41)
MW-6D, MW-6S, MW-8D and Hexavalent chromium UJ Analyzed outside of holding
MW-8s
times
All samples Chloride, chemical The %Rs were below QC
oxygen demand and J/UJ limits in the matrix spike
hexavalent chromium
VALIDATION PERFORMED BY&DATE: Donna M.Brown 8/13/2018
VALIDATION PERFORMED BY
SIGNATURE:
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