7904_RockinghamCountyMSWLF_SoilAssmtRpt_DIN28622_20171013

2211 West Meadowview Rd. Boone Building, Suite 101 Greensboro, NC 27407 tel: [phone] fax: [phone] www.JoyceEngineering.com

October 13, 2017

Mr. Ervin Lane
Compliance Hydrogeologist
NCDEQ/Solid Waste Section
1646 Mail Service Center
Raleigh, NC 27699-1646

Re: Soil and Sediment Basin Assessment Report Addendum
Solid Waste Permit No. 7904-MSWLF-1995
Rockingham County, North Carolina
JOYCE Project No. 00401.1801.12, Task No. 07

Dear Mr. Lane:

Joyce Engineering (JOYCE) presents this report on the results of the additional soil
sampling conducted at the Rockingham MSW landfill, Permit # 7904-MSWLF-1995 that was
requested in your letter dated July 7, 2017. The original sediment basin and soil sampling,
conducted in May 2017, were in response to a Notice of Violation (NOV) issued by the North
Carolina Department of Environmental Quality (NCDEQ) on May 2, 2017. A North Carolina
Environmental Monitoring Reporting Form (EMRF) is attached.

BACKGROUND

On April 27, 2017, NCDEQ conducted an inspection of the above-mentioned landfill and
observed leachate releases (seeps). During the inspection of these seeps, NCDEQ observed two
streams of leachate leaving the lined area and entering the drainage ditch below it. On May 17,
2017, JOYCE collected soil and sediment basin samples to evaluate the extent of any potential
environmental impact resulting from the leachate releases. The soil samples were collected from
six locations (SS-1, SS-2, SS-3, SS-4, SS-5, and SS-6) from areas in the stormwater ditch below
observed seeps as well as along the stormwater ditch at approximately 400-foot intervals between
SS-1 and Sediment Basin No. 1. JOYCE also collected a background soil sample and a water
sample from Sediment Basin No. 1 (see Drawing 1). The samples were analyzed for the NC
Appendix I list of total metals by EPA Method 6010 and volatile organic compounds (VOCs) by
EPA Method 8260, as well as for phosphorous and sulfate.

There were no VOC exceedances of Industrial Preliminary Soil Remediation Goals (PSRGs)
or Protection-of-Groundwater PSRGs in the soil samples. In addition, the concentrations of
detected metals in background and stormwater ditch samples were similar except for cobalt. As
part of a response action to NOVs dated December 22, 2016, and May 2, 2017, the County removed
accumulated sediment from the stormwater ditches between June and September 2017. In addition,
as part of maintenance activities, the County is currently removing accumulated sediment from
Sediment Basin No. 1. The removed soil has been placed back on the landfill for use as daily cover.
Mr. Ervin Lane
October 13, 2017
Page 2 of 3

In a letter dated July 7, 2017, NCDEQ requested further evaluation of cobalt after the soil had been
removed from the stormwater ditches.

ADDITIONAL SOIL SAMPLING

On September 13, 2017, JOYCE collected soil samples from approximately the same
locations as SS-1, SS-2, SS-3, SS-4, SS-5, and SS-6 in May. For locations SS-1, SS-2, SS-3, and
SS-4, JOYCE collected samples of sediment near the original sampling locations within the
regraded stormwater ditch. JOYCE collected samples SS-1 and SS-2 from the soil in the center of
the stormwater ditch. JOYCE collected samples SS-2 and SS-4 from sediment accumulated on the
riprap recently placed in the stormwater ditch in these locations near the original locations from
May. JOYCE also collected samples SS-5 and SS-6 from sediment accumulated on the riprap
recently placed in the stormwater ditch for these locations. However; since there was not a
sufficient amount of sediment accumulated on the riprap at the May 2017 locations the SS-5 and
SS-6 samples were collected in closer proximity to the drop inlets, as discussed with you in e-mail
correspondence following the July 7, 2017, letter requesting the additional samples. In addition,
JOYCE collected one composite soil sample from an upgradient location (SS-BG) in the borrow
area to represent background soil conditions. It is noted that the borrow area excavation was deeper
into existing soil and saprolite in September than it had been in May 2017.

The soil samples were collected using the disposable terra-core sampler included with each
sample container kit, and placed directly into the containers. The samples were placed in
laboratory-prepared containers and put immediately into a cooler with ice for transport to the
laboratory. The samples were transported under chain-of-custody control to ENCO in Cary, North
Carolina for analysis of cobalt by EPA Method 6010.

LABORATORY RESULTS

The laboratory analytical report was received on September 25, 2017, and is included in
Attachment A. Table 1 summarizes the cobalt analytical results for the May and September 2017
soil samples and includes the PSRGs from the NCDEQ Inactive Hazardous Sites Branch. The soil
analytical results were compared to both the Industrial Health-based PSRGs and the Protection-of-
Groundwater PSRGs.

When compared to the cobalt concentrations detected in May 2017, the September 2017
results for the soil samples collected from the stormwater ditch are not significantly different. The
May 2017 cobalt concentrations ranged from 7.84 milligrams per kilogram (mg/kg) to 25.0 mg/kg,
while the September 2017 cobalt concentrations ranged from 5.54 mg/kg to 17.0 mg/kg. However,
the background concentration detected in September 2017 was 12.3 mg/kg, while it was 0.768
mg/kg in the May 2017 background sample. Although cobalt was detected at quantified
concentrations above the lowest PSRG in all of the soil samples collected from the stormwater ditch
(May and September 2017), the concentrations of cobalt detected in all of the soil samples (May
and September 2017) are within the same order of magnitude as that detected in the September
2017 background sample (12.3 mg/kg). During the September 2017 sampling, the borrow material
Mr. Ervin Lane
October 13, 2017
Page 3 of 3

was observed to be existing, in-place soil and saprolite with residual structure; whereas the May
2017 background sample did not appear to be saprolite, and may have contained more stockpiled
fill material. In addition, the range of cobalt concentrations is within the order of magnitude of the
range of concentrations that occur naturally in the mineralogy of the North Carolina Piedmont soils
(2.5-10 mg/kg; Reid, 1993).

CONCLUSIONS

The results of this additional investigation indicate that the concentrations of cobalt detected
in the May and September 2017 soil samples are similar to the concentration detected in the
background sample collected from the borrow area in September 2017. Hence, leachate does not
appear to have had a definitive impact on the soil in the stormwater ditches.

Please contact me at [phone] if you have any questions or comments.

Respectfully,
JOYCE ENGINEERING
Jennifer Johnson
Senior Technical Consultant

Attachment A Laboratory Report

Cc: Ronnie Tate, Engineering & Public Utilities Director – Rockingham County
Kathryn Jolly, Solid Waste Program Manager – Rockingham County
Martie Neugent, Landfill Supervisor – Rockingham County
Deborah Aja, Western District Supervisor, Solid Waste Section, NCDEQ
Susan Heim, Environmental Senior Specialist, Solid Waste Section
Larry Frost, P.E., Engineering Project Manager, NCDEQ/Solid Waste Section

Reference: Reid, Jeffery C. A Geochemical Atlas of North Carolina. North Carolina
Geological Survey, Bulletin 93. Raleigh, NC. 1993.

Drawing

740630640650 640 620600590590610630640630620610600590600590 59058071070069067065063067068069070071062063064065060061063065067063
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680690700650660670680690700640650660670EXISTING PERIMETER ACCESS ROADEXISTING PERIMETER ACCESS ROADEXISTINGSED BASINNO.2EXISTING MAIN ACCESS ROADEXISTINGLEACHATECOLLECTIONLAGOONEXISTINGSED BASINNO.17207107006906807307407507607707807908008108208307
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0 15' BENCH15' BENCH3:1 SLOPEEXISTINGLANDFILLOFFICEPERMITTEDWASTE LIMITPERMITTEDACCESS ROADDROPINLET 2CULVERT 2CULVERT 1CULVERT 3OUTLET PROTECTION (TYP)SLOPE DRAIN (TYP)DITCH CHANNEL (TYP)BEGIN SCC-4DROPINLET 1DROPINLET 2DA - 11.77 ACRESDA - 22.09 ACRESDA - 32.23 ACRESDA - 42.38 ACRESDA - 51.50 ACRESDA - 61.68 ACRESDA - 72.26 ACRESDA - 82.51 ACRESDA - 91.77 ACRESDA - 100.83 ACRESDA - 114.41 ACRESDA - 125.37 ACRESDA - 133.68 ACRESDA - 142.61 ACRESDA - 152.62 ACRESDA - 161.46 ACRESDA - 1711.48 ACRESDA - 182.53 ACRESBORROWAREA (4 ACRES)SB-1SS-1SS-2SS-6SS-4APPROXIMATE SOIL SAMPLE LOCATIONAPPROXIMATE SURFACE WATERSAMPLE LOCATIONDIRECTION OF STORMWATER FLOWSS-1SB-1APPROXIMATELOCATION OF SEEPAPPROXIMATELOCATION OF SEEPSS-3SS-5SS-BGLOCATIONSAPPROXIMATELOCATION OF SEEPPROJECT NO.APPROVED
CHECKED
DRAWN
DESIGNED
DATE
DATE REVISIONS AND RECORD OF ISSUE BYNO APPCKSCALE All rights reserved.
Ó Joyce Engineering, Inc.DRAWING NO.L:\Rockingham\dwg\2017-RESPONSE TO NOV-SAMPLING PLAN\SAMPLING PLAN.dwg Layout=e&s plan0(FEET)GRAPHIC SCALE20010050401.1701.12.07ROCKINGHAM COUNTY LANDFILL PERMIT 79-04
MADISON, NORTH CAROLINA
201701AS NOTEDSAMPLING PLAN
JPJ
RWH
JPJ
JPJ
05/04/17
NC CORP LIC: C-0782
9731-F SOUTHERN PINE BLVD
CHARLOTTE, NC 28273
PHONE: [phone]

Table

Sample ID Sample Date Parameter PSRG-IH PSRG-GW Result Q Method Units
7904-SSBG 5/17/2017 Cobalt 70.0 0.09 0.768 EPA 6010D mg/kg
SS-BG 9/13/2017 Cobalt 70.0 0.09 12.3 EPA 6010D mg/kg
7904-SS1 5/17/2017 Cobalt 70.0 0.09 16.4 EPA 6010D mg/kg
SS-1 9/13/2017 Cobalt 70.0 0.09 9.07 EPA 6010D mg/kg
7904-SS2 5/17/2017 Cobalt 70.0 0.09 8.45 EPA 6010D mg/kg
SS-2 9/13/2017 Cobalt 70.0 0.09 17.0 EPA 6010D mg/kg
7904-SS3 5/17/2017 Cobalt 70.0 0.09 13.0 EPA 6010D mg/kg
SS-3 9/13/2017 Cobalt 70.0 0.09 5.54 EPA 6010D mg/kg
7904-SS4 5/17/2017 Cobalt 70.0 0.09 7.8 EPA 6010D mg/kg
SS-4 9/13/2017 Cobalt 70.0 0.09 15.6 EPA 6010D mg/kg
7904-SS5 5/17/2017 Cobalt 70.0 0.09 10.1 EPA 6010D mg/kg
SS-5 9/13/2017 Cobalt 70.0 0.09 15.6 EPA 6010D mg/kg
7904-SS6 5/17/2017 Cobalt 70.0 0.09 25.0 EPA 6010D mg/kg
SS-6 9/13/2017 Cobalt 70.0 0.09 14.5 EPA 6010D mg/kg
NOTES:mg/kg = milligrams per kilogram = parts per million.
µg/kg = micrograms per kilogram = parts per billion.
J = Estimated concentration below the quantitation limit.
PSRG = Preliminary Soil Remediation Goals (NC-DEQ Inactive Hazardous Sites Branch)
PSRG-IH = Industrial Health-based PSRG.
PSRG-GW = Protection-of-Groundwater PSRG.
NS = No standard established.
Bold results exceed the lowest PSRG.
Table 1: Cobalt Sediment Results
Rockingham County Landfill
Permit No. 7904 Page 1 Joyce Engineering

Attachment A

Laboratory Report