7904_RockinghamCountyMSWLF_SoilAssmtRptResp_DIN28623_20171108

November 8, 2017

Sent Via Email – [e-mail]

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

Re: Soil and Sediment Basin Assessment Report Addendum
Rockingham County Landfill
Solid Waste Permit Number 7904-MSWLF-1995
DIN 28623

Dear Ms. Jolly:

The Solid Waste Section (Section) has completed a review of the Soil and Sediment Basin Assessment
Report Addendum (DIN 28622) submitted on behalf of Rockingham County by Joyce Engineering (Joyce)
for the Rockingham County Landfill, Solid Waste Permit Number 7904. The report was submitted to
provide additional information related to leachate seeps observed during an April 27, 2017 facility audit
that resulted in a notice of violation.

Joyce conducted an initial investigation to determine the potential impact of the leachate seeps on May
17, 2017. The initial investigation consisted of collecting six soil samples from areas in the stormwater
ditch below each leachate seep location. The soil contaminant concentrations did not exceed the
Residential or Protection of Groundwater Preliminary Soil Remediation Goals (PSRGs) for volatile organic
compounds. Arsenic, phosphorus, and vanadium were reported at concentrations exceeding the PSRGs,
but those concentrations were within the same order of magnitude as the background sample, so their
presence was determined to be naturally occurring. Since cobalt was the only constituent reported at
concentrations above the PSRGs in all the soil samples except the background sample, further evaluation
was necessary.

Joyce returned to the site on September 13, 2017 to collect soil samples near the original sampling
locations within the stormwater ditch. The ditch was re-graded before the second sampling event and
the samples were collected from sediment that accumulated on top of rip rap placed along the
stormwater ditch. A new background sample was also collected at a deeper interval than the previous
background sample since the previous background sample was believed to be comprised of stockpiled fill
material instead of existing in place soil. Cobalt concentrations for the six new soil samples were similar
to the previous soil samples, but the cobalt concentration reported in the new background sample was
within the same order of magnitude as both sets of samples. Joyce concluded that leachate did not have
a definitive impact on soil since cobalt concentrations reported from the May and September 2017

sampling events are similar to the concentrations detected in the new background sample. Based on the
results of the soil assessment addendum, the Section agrees with Joyce’s conclusion and Rockingham
County is not required to conduct additional assessment activities related to the April 2017 leachate seeps
at this time.

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