7904_RockinghamCountyMSWLF_SoilAssmtRptResp_DIN28122_20170707

July 7, 2017

Sent Via Email – [e-mail]

Kathryn Jolly
Environmental Compliance Solid Waste Program Manager
P.O. Box 132
Wentworth, NC 27375

Re: Soil and Sediment Basin Assessment Report
Rockingham County Landfill
Solid Waste Permit Number 7904-MSWLF-1995
DIN 28122

Dear Ms. Jolly:

The Solid Waste Section (Section) has completed a review of the Soil and Sediment Basin Assessment
Report (DIN 28035) submitted on behalf of Rockingham County by Joyce Engineering (Joyce) for the
Rockingham County Landfill, Solid Waste Permit Number 7904. The report was submitted in response to
leachate seeps observed during an April 27, 2017 facility audit that resulted in a notice of violation. Joyce
subsequently submitted an assessment plan to address possible contamination which was approved by
the Section on May 5, 2017.

Joyce collected six soil samples, SS-1 through SS-6, at 400 foot intervals along the storm water ditch. A
composite background soil sample(SSBG) in addition to a surface water sample (SB-1) from Sediment
Basin No. 1 were also collected. The samples were analyzed for Appendix I metals via EPA Method 6010
and volatile organic compounds (VOCs) via EPA Method 8260 in addition to phosphorous and sulfate. The
Section compared laboratory analytical results to the Preliminary Residential Health Based Soil
Remediation Goals (PSRG) and Protection of Groundwater PSRGs. There were no VOCs reported at
concentrations exceeding the PSRGs in the soil samples. Arsenic, phosphorus, and vanadium were
reported at concentrations exceeding the PSRGs in soil samples SS-1 through SS-6 in addition to the
background soil sample. Cobalt was the only inorganic constituent reported at a concentration exceeding
the PSRGs in samples SS-1 through SS-6 but below the PSRG in SSBG. Sulfate, 2-Butanone, and acetone
were reported at quantified concentrations above laboratory reporting limits, but below the surface water
standards established in 15A NCAC 02B (2B Standard) in SB-1. Cobalt was also reported at a quantified
concentration in the surface water sample, but there is no 2B Standard for Cobalt.

Based on the lack of VOC exceedances in the soil samples and the similarity of metals concentrations
between the background and drainage ditch samples, leachate does not appear to have a definitive
impact on the soil. Since cobalt was the only inorganic constituent reported at concentrations above the
PSGRs in all soil samples except the background sample, further evaluation is necessary. Additional soil

samples should be collected and analyzed for cobalt after the stormwater ditch cleanout is complete. The
samples should be collected in approximately the same locations as samples SS-1 through SS-6.

If you have any questions or concerns regarding this letter, please feel free to contact me by email at
[e-mail] or by phone at 919.707.8288. Thank you for your continued cooperation with this
matter.

Sincerely,

Ervin Lane
Compliance Hydrogeologist
Solid Waste Section, Division of Waste Management
NCDEQ

cc sent via email: Jason Watkins, Field Operations Branch Head
Deb Aja, Western District Supervisor
Susan Heim, Environmental Senior Specialist
Ed Mussler, P.E., Permitting Branch Head
Larry Frost, Permitting Engineer
Jennifer Johnson, Joyce Engineering