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TRC Environmental Corporation
<br /> 1201 North McDowell Boulevard
<br /> Petaluma, CA 94954
<br /> Environmental Solutions through Technology a (707) 769-5250 Fax (707) 762-3614
<br /> June 30, 1993
<br /> Barclays Business Credit IPSIVE1999 Harrison Street, Suite 1450 Ivl I
<br /> Oakland, California 94612-3508 J U L 16 1993
<br /> Attention: Mr. Greg Ennis, Assistant Vice-President
<br /> ENVIRONMENTAL HEALTH
<br /> PERMIT/SERVICES
<br /> Proposal to Install Groundwater Monitoring Wells
<br /> 11800 South Harlan Road
<br /> Lathrop, California
<br /> TRC Environmental Corporation (TRC) is pleased to present this proposal for the installation of groundwater
<br /> monitoring wells at 11800 South Harlan Road, Lathrop, California (site). TRC understands that the adjacent
<br /> property, Sharpe Army Depot, has a documented Trichloroethylene (TCE) groundwater contamination problem.
<br /> Based on review of information presented in TRCs Preliminary Site Assessment, 11800 Harlan Road, Lathrop,
<br /> California, dated June 9, 1993, contamination has been confirmed in the first 3 underlying water-bearing units
<br /> (designated as the A-, B-, and C-aquifers), at several locations at the Sharpe Army Depot. One of these locations
<br /> is within close proximity of the site, and may actually extend beneath the site. Monitoring well location 517 is
<br /> located just outside of the northeast corner of the site. During the quarterly monitoring program for the past year,
<br /> TCE has been detected sporadically in groundwater from the A-aquifer (2 out of 4 sampling events), once out
<br /> of 4 sampling events in the B-aquifer, and consistently (4 out of 4 sampling events) in the C-aquifer. To
<br /> investigate the possible presence of TCE in groundwater beneath the site, TRC proposes to drill and install
<br /> groundwater monitoring wells within the C-aquifer. TRC recommends drilling the fust well closest to the
<br /> property boundary near the northeast corner, probably on top of the berm surrounding the water retention pond.
<br /> If groundwater from this well contains detectable concentrations of TCE, an additional well will be installed at
<br /> a distance further away from the plume, to identify the limits of TCE contamination. This proposal presents cost
<br /> estimates for drilling each well separately.
<br /> SCOPE OF WORK
<br /> The C-aquifer is being monitored at a depth of 120 feet below ground surface at the 517 monitoring well location.
<br /> TRC proposes to drill a pilot hole to this approximate depth, by a licensed driller with a mud-rotary wash drilling
<br /> rig. Soil samples will be collected from the pilot boring for lithologic classification; and, the boring will be
<br /> geophysically logged with natural gamma and electrical logs, for aquifer thickness and aquitard verification.
<br /> Upon determining the zone of the C-aquifer, the boring will be reamed to just below the B-aquifer. A conductor
<br /> casing will be installed to block off the A- and B-aquifer zones from possible cross-contamination with the C-
<br /> Aquifer. The conductor casing will be grouted in place, and the C-aquifer zone drilled to accommodate a 4-inch,
<br /> PVC groundwater monitoring well. The monitoring well will be installed according to State and local
<br /> requirements, and will be installed above ground with a locking well cap. The casing elevation will be surveyed
<br /> for accurate water elevation measurements.
<br /> Soil cuttings will be contained in a roll-off bin, tested for landfill profiling, and disposed at BFI's Vasco Road
<br /> landfill in Livermore, California.
<br /> The monitoring well will be developed by surging and bailing. A groundwater sample will be collected for
<br /> analysis of volatile organic compounds by EPA Test Method 8240.
<br /> Offices in California,Colorado,Connecticut, Illinois, Louisiana,Massachusetts, New Jersey, New York, North Carolina, Pennsylvania,Texas,
<br /> Washington,Washington, D.C.,and Puerto Rico A TRC Company
<br /> Printed on Recyded Paper
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