HomeMy WebLinkAbout7401_PittCountyMSWLF_Assessment_DIN27528_20170316Groundwater Management Associates, Inc.
4300 Sapphire Court, Suite 100
Greenville, North Carolina 27834
Telephone: (252) 758-3310
Facsimile: (252) 758-8835
www.gma-nc.com
March 15, 2017
Ms. Jaclynne Drummond
Compliance Hydrogeologist
NCDEQ Solid Waste Section
2090 US Highway 70
Swannanoa, North Carolina 28778
Re: Proposal for Assessment of Benzene Contamination Migration
Pitt County Solid Waste Municipal Landfill
Dear Ms. Drummond,
During the January 2017 groundwater monitoring event conducted by Groundwater
Management Associates, Inc. (GMA) at the inactive Pitt County Solid Waste Municipal Landfill,
benzene was detected at concentrations slightly exceeding the 1.0 µg/L 15A NCAC 2L standard
in two groundwater monitoring wells. Specifically, the samples from well P16R and well P20R
contained 2.4 and 1.7 µg/L of benzene, respectively. The source of benzene in wells P16R and
P20R is unknown. Because benzene has been detected previously in wells P16R and P20R at
concentrations above the 15A NCAC 2L standard, GMA submitted a 14-Day Notice documenting
the exceedances to the North Carolina Solid Waste Section (SWS) on behalf of Pitt County on
March 3, 2017 as required by rule 15A NCAC 13B.1633(c)(1).
Well P16R is located hydraulically upgradient of well P20R and is used as an upgradient
monitoring location for the Southern Pitt County Landfill Unit. Well P20R is located
approximately 90 feet north of the Pitt County Landfill property boundary and in close proximity
to the ditch along the property boundary. During our March 2, 2017 phone conversation
regarding the benzene detections at this site, you indicated that Pitt County needs to assess
whether benzene contamination has migrated off the property, and you suggested sampling the
pore water beneath the ditch along the southern property boundary to establish this.
Based on our conversation, GMA proposes to collect two pore water samples from the beneath
the southern boundary ditch using a PushPointTM sampler and syringe. The proposed sampling
locations are down gradient of well P20R, as shown in Figure 1. Sampling procedures will
follow the Environmental Protection Agency, Science and Ecosystem Support Division’s (SESD)
2013 Pore Water Sampling Operating Procedure (SESDPROC-513-R2) guidelines to ensure
sample integrity and avoid surface water intrusion. Pore water samples will be transferred to
ENCO Laboratory in an ice-filled cooler under chain-of-custody protocol and analyzed for
Appendix I parameters. Pore water samples will not be filtered in the field such that all metals
are analyzed as total metals.
Ms. Jaclynne Drummond
NC Solid Waste Section
March 15, 2017
Page 2 of 2
GMA proposes to conduct this pore water sampling during the next semi-annual monitoring
event for the Southern portion of the Pitt County Landfill scheduled for July 2017. Analytical
results will be reported as part of the corresponding Semi-Annual Monitoring Report.
If you have any questions or comments regarding the proposed assessment work, please
contact me at 758-3310 or emma@gma-nc.com.
Sincerely,
Groundwater Management Associates, Inc.
Emma H. Shipley, P.G.
Project Hydrogeologist
Cc: Mr. John Demary, Pitt County Director of Solid Waste & Recycling
Mr. Tim Corley, Pitt County Engineer
Mr. Steve Campbell, GMA
Enclosures: Figure 1
Z:\GMA\251XX- Pitt County\25101 - Landfill\2017 January\Mini-assessment Proposal Letter to NCSWS 20170314.docx
P5
P4P6
MW1
P11R
P1276.58
P16R
P20R
P19
P28
P17 MW6R
P23
P21 P9
P13DP13
MW4
P7
P2
MW3
P26
P25
MW7
MW2MW8
MW8D
P14
74.67 75.01
74.35
75.20
75.86 77.32
77.08
77.35
(75.12)77.71
77.7
P24 P10
P8
MW5
P3
78.58
78.01
77.31
78.56
80.2781.03
81.33
78
77
78
80 P15
140
120
100 80
100
MW7D
76.61
77
77
80
79
76
78
MW1R(78.06)
76
81
81
79
75
75
(75.14)
75 75
100
100
120
80
80
80
80
80
80
80
80
80
80
80
80
80 8
0
80
80
80
80
80
80
0 300 600'
PROPOSED PORE WATERSAMPLING LOCATIONS
- LEGEND -
PROJECT: 25101
FIGURE 1
DATE 3/15/2017
SCALE IN FEET
GENERAL NOTES:1. TOPOGRAPHIC CONTOUR INTERVAL = 2.0 FEET2. GROUNDWATER CONTOUR INTERVAL = 1.0 FOOT3. ARROW INDICATES DIRECTION OF GROUNDWATER FLOW4. WATER LEVEL ELEVATIONS ARE POSTED BY EACH WELL5. ( ) INDICATES DATA NOT USED
1" = 600'
POND
PROPERTY LINE
TOPOGRAPHIC CONTOUR
NORFOLK SOUTHERN RAILROAD (100'
R
/
W
)
RAILROAD TRACKS
WATER LEVEL(FEET ABOVE SEA LEVEL)77.31
DRW BY: EHS
MONITORING WELL
ABANDONED MONITORING WELL
UNMEASURED MONITORING WELL
INDICATES DIRECTION OFGROUNDWATER FLOW
JANUARY 2017 GROUNDWATERELEVATION CONTOUR
PROPOSED PORE WATERSAMPLING LOCATION