SECTION FIVE
Performance Standards and Construction Quality Control
after which they were opened. It was determined that the passive injection wells should remain
open unless a detrimental effect could be demonstrated.
The concentration of TCE in the soil gas extracted by the SVE system generally decreased from
210 parts per billion by volume (ppbv) to 140 ppbv during the period of April 1, 1995 through
July 27, 1995. The extracted soil gas concentration then increased to a maximum of 640 ppbv
during the period of August 1, 1995 through December 27, 1999. This increase generally
corresponds to the opening of the passive injection wells after July 29, 1995, suggesting that the
use of the passive injection wells enhanced the system's performance.
Groundwater Sampling
Twenty-two rounds of groundwater sampling have been conducted (two before the remediation
system was installed and four times per year for five years after the system's installation). The
first round of sampling was performed during March 1994 and the last round for which data was
available was performed in December 1999.
TCE was the only contaminant in groundwater consistently identified above the cleanup levels
established for the site. In addition, monitoring for Mn was required.
The average TCE concentration in the contaminant reduction monitoring wells has decreased
from 79 to 6.4 mg/L from March 1994 to December 1999, while the average TCE concentration
in the migration monitoring wells has showed no consistent trend (average concentrations have
ranged from 3.78 to 12.03 mg/L). TCE concentrations in both areas were still above the site
cleanup level of 5 mg/L in December 1999.
The average total Mn concentration in the contaminant reduction monitoring wells has decreased
from 11,000 mg/L in March 1994 to 8.0 mg/L in December 1999, while the average Mn
concentration in the migration monitoring wells has generally decreased from 488.0 to
40.0 mg/L) during the same time period.
Vinyl chloride, the other contaminant with a cleanup level for the site, was only detected above
method detection limits on one occasion (March 1997)and was never detected above site cleanup
levels.
Air Emissions Sampling
Based upon the system performance testing of the AS/SVE system, the air effluent from the
system was determined to be several magnitudes below the RAPCA emission action levels.
Therefore, because the RAPCA emission action levels would not be exceeded during the SVE
system's operation, additional air sampling was not required.
PERFORMANCE DATA QUALITY
According to the technical memorandum on the results of the pilot study, the required QA/QC
samples were collected. Field duplicates, field blanks, rinsate blanks, and travel blanks were
5-2
Ft. Griffey Landfill 5 OU Interim RA Report
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