Final Remedial Action Completion Report for the ... - Rvaap.org

Remedial Action Completion Report
June 2008
Remediation of Soils and Dry Sediments at RVAAP 08-11 (LLs 1-4)
Page 3-17
capable of analyzing specifically for hexavalent chromium, total chromium was used as the
screening contaminant for this COC.
As a proactive measure, the Shaw field crews continued excavation for all inorganic COCs,
including those not previously identified, that were found to exceed cleanup goals at each of the
discrete excavations. Excavation of soils continued until the XRF field screen results identified
all inorganic COCs to be below the applicable cleanup goal levels. The locations where
previously unidentified COCs were detected and removed are presented in the data summary
tables (Table B-3) in Appendix B.
3.6 CONFIRMATORY SAMPLING
Confirmatory samples were collected from each of the excavation areas using multi-increment
sampling in accordance with the Guidance for Multi-Increment Sampling procedures included in
Appendix A of the Shaw FSP (Shaw 2006b).
3.6.1 Sample Collection
As indicated in Section 3.4.2, excavation began in the area of the highest COC concentration(s)
previously detected and moved outward from the assumed source location. Once field screen
test results identified an excavation area to be below the applicable cleanup goals for the COC(s),
multi-increment samples were collected from a pre-determined number of stratified random
sample locations from the excavation area using disposable sample trowels. The random
samples were placed into a clean plastic lined bucket and combined to make a single sample.
The sample was homogenized by manual mixing and a maximum of 1 kilogram (kg) of the
sample was removed from the plastic bag and placed into a labeled pre-cleaned container. Each
multi-increment sample consisted of random samples combined from the floor and sidewalls of
the excavation areas. In general, 20 random samples were collected from excavation areas less
than 100 square feet (ft 2 ) and 30 random samples were collected from excavation areas greater
than 100 ft 2 . For the most part, excavations were greater than 100 ft 2 and 30 random samples
were collected from the majority of the excavations. The excavation dimensions and locations at
which the random samples were collected for the multi-increment sample were noted by the
Shaw field sample technicians and documented in the field log sheets presented in Appendix E
in the electronic attachment to this RACR. It should be noted that the reduction of the sample
volume to 1 kg prior to shipment deviated from the methodology outlined in the RAWP but was
approved by USACE and the Ohio EPA prior to implementation in the field.
The sample containers were secured, packaged, and shipped to the designated off-site laboratory
for drying, processing, and analysis, along with the appropriate chain-of-custody documentation
as outlined in the FSP (Shaw 2006b). The off-site laboratories used by Shaw as part of the
remediation of soils at LLs 1-4 were approved by USACE and the Ohio EPA prior to shipment
of the samples.
3.6.2 Sample Processing and Analysis
In all, a total of 125 multi-increment samples, including duplicate and MS/MSD duplicate
samples, were submitted for analysis at either of the two off-site laboratories contracted by
Shaw: Test America in North Canton, Ohio and Kemron in Marietta, Ohio. Shaw contracted
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