2601_CumberlandCoMSW_MetalsASDTempMonSched_DIN28578_20171023

SCS Engineers, P.C. Environmental Consultants 2520 Whitehall Park Drive 704 504-3107 and Contractors Suite 450 FAX [phone] Charlotte, NC 28273-3557 www.scsengineers.com

October 23, 2017
File No. 02217304.01

Mr. Ervin Lane, Compliance Hydrogeologist
North Carolina Department of Environmental Quality Division of Waste Management, Solid Waste Section
217 West Jones Street
Raleigh, North Carolina 27699-1646

Subject: Cumberland County Landfill Facility Permit Number 2601-MSWLF-1997 Alternative Source Demonstration
Temporary Monitoring Schedule and Well Redevelopment

Dear Mr. Lane:
On behalf of Cumberland County, SCS Engineers, PC is submitting this response to the
Department’s review of the Alternative Source Demonstration for Appendix I Inorganic
Constituent Exceedances at the Cumberland County Landfill, originally prepared by CDM Smith
and dated November 8, 2016. In a letter dated July 21, 2017, the Department requested that
Cumberland County calculate statistical background concentrations of constituents of concern arsenic, beryllium, chromium, cobalt, lead, thallium, and vanadium in accordance with 15A
NCAC 13B.1634(g)(5). The Department further stipulated that, as turbidity appeared to have
adversely impacted groundwater analytical results, statistical background concentrations should
not be calculated using previous monitoring data unless field notes/logs indicated that turbidity
values were below 10 Nephelometric Turbidity Units (NTUs).
SCS has reviewed the available semi-annual water quality monitoring reports and has determined
that an insufficient amount of data exists that meets the Departments requirements regarding
turbidity. As such, SCS proposes to sample the Subtitle D background well (MW-E-REP) on a
quarterly basis beginning in the fourth quarter of 2017. When the timing of such sampling
events coincides with the semi-annual water quality monitoring, monitoring data collected during the semi-annual water quality monitoring event will be used. All samples collected in support of
this temporary monitoring schedule will be analyzed for Appendix I Inorganic constituents.
During the August 2017 semi-annual water quality monitoring event, SCS redeveloped
monitoring wells MW-E-REP (the background well for the Subtitle D landfill) and MW-J (the
well with the highest turbidity measurements during the last several semi-annual water quality monitoring events). Redevelopment was performed using a submersible pump at a rate of
approximately 0.5 gallons per minute at MW-J and an initial rate of 0.5 gallons per minute,
lowered to 0.25 gallons per minute (to accommodate an apparent slower well recharge) at MW-
E-REP. Time, turbidity, and cumulative purge volume were recorded in 2.5 gallon intervals.
This data can be found in Table 1 – MW-E-REP Redevelopment Results and Table 2 – MW-J Redevelopment Results, both attached.

Mr. Ervin Lane, Hydrogeologist
October 23 , 2017
Page 2
Per the Department’s July 21st letter, SCS will submit turbidity values for MW-E-REP on a
quarterly basis, as they are collected, including values collected during the semi-annual water quality monitoring events.
If you have any questions or need additional information, please do not hesitate to contact Mike
Cobb at 704-504-3107 or via email at [e-mail].
Sincerely,

Donald Michael Cobb, P.G. Steven C. Lamb, P.E. Senior Project Geologist Vice President
SCS ENGINEERS, PC SCS ENGINEERS, PC

cc: Jerod Roberts – Cumberland County Landfill

Enclosures
M:\PROJECT FILES\02217304.01\Deliverables\ASD\ASD DEQ Response and Schedule.doc

Ann Street Landfill
Cumberland County
M:\PROJECT FILES\02217304.01\Deliverables\ASD\Tables Page 1
Time
Turbidity
(NTUs)
Cumulative
Volume Purged
(gallons)
0945 710.80 2.5
0941 434.30 5.0
0948 534.50 7.5
0955 174.50 10.0
1000 82.32 12.5
1005 40.09 15.0
1011 30.63 17.5
1016 25.50 20.0
1022 15.93 22.5
1029 8.62 25.0
1037 6.16 27.5
1042 5.05 30.0
1048 10.23 32.5
1052 6.96 35.0
1058 6.71 37.5
1104 4.40 40.0
1109 18.27 42.5
1113 12.10 45.0
1117 20.24 47.5
1122 14.27 50.0
1127 6.14 52.5
1134 3.13 55.0
1140 2.58 57.5
1145 1.79 60.0
1151 1.86 62.5
1156 0.66 65.0
1202 3.57 67.5
1207 1.73 70.0
1213 8.07 72.5
1219 6.04 75.0
1224 2.49 77.5
1229 1.35 80.0
Table 2 - MW-J Redevelopment Results
Data Collected August 22, 2017