HomeMy WebLinkAbout17047 REEP Email VI Sampling 201704051
Schmithorst, William L
From:Schmithorst, William L
Sent:Thursday, April 5, 2018 11:14 AM
To:Matt Bramblett
Cc:Hinnant, Lori P.; John Lopez; Michael Cain; Jason Oriol
Subject:RE: DRAFT REEP-LRC Additional Assessment Results Summary and Update
Matt,
Based on the proposed site use and preliminary data/analysis submitted, additional vapor intrusion sampling would not
be required. Please forward a final report for confirmation when ready.
Regards,
Bill Schmithorst, P.G.
Project Manager
Division of Waste Management – Brownfields
NC Department of Environmental Quality
(919) 707‐8159 ‐ Direct Line & Fax
william.schmithorst@ncdenr.gov
217 W. Jones Street
1646 Mail Service Center
Raleigh, NC 27699‐1646
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From: Matt Bramblett [mailto:MBramblett@harthickman.com]
Sent: Friday, March 30, 2018 3:23 PM
To: Schmithorst, William L <William.Schmithorst@ncdenr.gov>
Cc: Hinnant, Lori P. <Lori.Hinnant@klgates.com>; John Lopez <jlopez@harthickman.com>; Michael Cain
<Michael.Cain@foundrycommercial.com>; Jason Oriol <Jason.Oriol@foundrycommercial.com>
Subject: [External] DRAFT REEP‐LRC Additional Assessment Results Summary and Update
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Bill,
Per our previous correspondence, Hart & Hickman (H&H) has conducted additional assessment and waste disposal
activities at the REEP‐LRC Project‐1 Site (Brownfields Project ID 17047‐13‐60). The additional assessment and waste
disposal activities were conducted in accordance with the approved February 7, 2018 Work Plan for Additional Waste
Disposal Assessment and included the collection of soil samples, groundwater samples, and some excavation in the area
of a previously identified potential drum and GPR anomaly located in the former disposal area in the southern portion of
the site. We will provide a report detailing the additional assessment and waste disposal activities at a later
date. However, we wanted to provide you with this summary on the results of the soil and groundwater samples
collected to seek feedback as soon as possible based on the pending Site development. The summary is provided below.
Soil Sampling‐Asbestos Areas
H&H conducted the confirmation asbestos soil sampling in the central and northern portions of the site. The
analytical results of the confirmation samples collected from the northern portions of the site were non‐detect
for asbestos. As you are aware, during sampling in the central portion of the site, additional transite material
was observed below the leaf layer and in shallow soil. As such, a soil sample was not collected from the central
area along with the samples from the northern areas to allow for the additional transite to be removed. The
additional transite was removed last week and a confirmation soil sample was collected. The asbestos results of
the confirmation sample collected from the central portion of the site was just received and is also non‐detect.
Soil Sampling‐Waste Disposal Area
H&H collected three soil samples from the former waste disposal area. One soil sample was collected from
below the known potential drum (Base‐2), one soil sample was collected from below the GPR anomaly (Base‐3),
and one soil sample was collected from a ash‐like material (Ash‐1) uncovered during excavation in the GPR
anomaly area. No additional drums or free product were observed during the excavation activities. The
locations of the soil samples are shown on the attached Figure 1. The attached soil laboratory analytical results
indicate that concentrations of VOCs, SVOCs, and metals were not detected above Inactive Hazardous Sites
Branch (IHSB) Industrial Preliminary Soil Remedial Goals (PSRGs) and/or were within published background
ranges except for the concentration of arsenic (13 mg/kg) detected in Ash‐1 which was above the IHSB Industrial
PSRG of 3.0. Although this concentration of arsenic is within published background ranges, it appears to be
elevated as compared to other arsenic concentrations detected at the site. The location with the arsenic
detection is in a significant fill area. A summary of the soil laboratory analytical data is provided on the attached
Table 1.
Groundwater Sampling and VI Evaluation
H&H installed and sampled two additional temporary monitoring wells at the site. One temporary monitoring
well was installed downgradient of the waste disposal area (TMW‐3) and one temporary monitoring well (TMW‐
4) was installed in the vicinity of former soil gas sample VMP‐8. The locations of the temporary monitoring wells
are shown on the attached Figure 1. The laboratory analytical results of the groundwater samples indicated the
presence of low levels of tetrachloroethylene (PCE) and trichloroethylene (TCE) slightly above North Carolina
Administrative Code 15A 2L Groundwater Standards (2L Standards) and Division of Waste Management (DWM)
Non‐Residential Vapor Intrusion Groundwater Screening Levels (GWSLs). Other VOCs were detected above
laboratory reporting limits in the groundwater samples collected, but the concentrations detected were below
applicable 2L Standards and DWM Non‐Residential GWSLs. The laboratory analytical results for the groundwater
samples are included in the attached Table 2.
To evaluate potential vapor intrusion risks associated with the groundwater concentrations detected in TMW‐3
and TMW‐4, H&H utilized DEQ’s Vapor Intrusion Risk Calculator (February 2018). The result of the risk
calculation indicated that the Lifetime Incremental Cancer Risk (LICR) for each sample were below 1 x 10‐4 and
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the hazard quotient for each sample was below 1.0. Copies of the risk calculators are included as Attachment 1
for your review.
To further evaluate the potential vapor intrusion risk associated with the site, H&H also utilized the most recent
version DEQ Risk Calculator to reevaluate the soil gas concentrations detected in SGP‐7 and SGP‐8 (which were
previously reported to be below acceptable risk thresholds). The result of the risk calculation for VMP‐7
indicated a LICR of 9.1 x 10‐7 and HI of 0.25. The result of the risk calculation for VMP‐8 indicated a LICR of 2.0 x
10‐6 and HI of 0.58. As consistent with the previous VI evaluation, the vapor intrusion risk associated with SGP‐7
and SGP‐8 are below the acceptable risk thresholds. Copies of the risk calculators for VMP‐7 and VMP‐8 are also
included in Attachment 1.
Based on the results of the groundwater and soil gas sampling and proposed industrial use of the site, potential vapor
intrusion levels do not pose a vapor intrusion risk beyond acceptable levels as defined by DEQ. Therefore, additional
vapor intrusion sampling is not warranted. Please let us know your thoughts on these data at your earliest convenience.
Thanks!
Matt Bramblett, PE
Hart & Hickman, PC