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Mr. Brian Miller • - 3 - • 2 June 2006
<br /> Western Farm Service plans to conduct hydraulic testing by performing slug tests in
<br /> each of the two new pilot study monitoring wells. The objective of the hydraulic testing
<br /> is to provide an estimate of the hydraulic conductivity and confirm that the distance
<br /> between the performance wells and the proposed injection grid is sufficient to observe
<br /> results of the injection within a one-year time period.
<br /> Contingency Plan
<br /> Zero valent iron and carbon amendments will create a localized reducing environment
<br /> due to the transfer of electrons from the iron and other electron donors onto oxidized
<br /> compounds. Western Farm Service proposes to evaluate and discuss the magnitude
<br /> and extent of any effects observed in the pilot test wells with Regional Water Board
<br /> staff, and, if warranted, Western Farm Service can reverse the reducing conditions by
<br /> introducing oxygen into the pilot test area.
<br /> Pilot Study Monitoring
<br /> Prior to injecting EHCT and at quarterly intervals during the pilot study, Western Farm
<br /> Service proposes to sample PM-1, PM-2, MW-8, and E-1, and analyze the groundwater
<br /> for 1,2,3-TCP, 1,2-DCP, EDB, DBCP, their degradation products, dissolved and total
<br /> iron, dissolved hydrocarbon gases, alkalinity, nitrate, nitrite, ammonium, chloride,
<br /> sulfate, pH, oxygen-reduction potential, and dissolved oxygen. Western Farm Service
<br /> should also add analyses for dissolved manganese and carbon dioxide to the quarterly
<br /> analytical program.
<br /> Since zero valent iron is expected to produce results quickly, Western Farm Service
<br /> should monitor the performance well closest to the injection grid (PM-1) monthly for the
<br /> first three months. During these first three monthly monitoring events, PM-1 should be
<br /> sampled and analyzed for 1,2,3-TCP, 1,2-DCP, EDB, DBCP, dissolved iron, alkalinity,
<br /> nitrate, and the field parameters of dissolved oxygen, oxygen-reduction potential, pH
<br /> and temperature.
<br /> In a year, the pilot study may provide sufficient information to develop a larger scale
<br /> remediation strategy for the site groundwater constituents. The zero valent iron could
<br /> continue to be reactive for ten years, although the reductive capability and hydraulic
<br /> conductivity are expected to diminish over time. Since the iron is expected to remain
<br /> reactive, at the conclusion of the pilot study Western Farm Service should propose
<br /> changes to the routine groundwater monitoring specified in Monitoring and Reporting
<br /> Program No. R5-2004-0804 (MRP) to incorporate longer-term monitoring of the pilot
<br /> study injection area.
<br /> Reporting
<br /> GeoSyntec plans to provide a Pilot Study Implementation Report within 90 days of
<br /> injecting the EHCTM. The Implementation Report will include pre-injection sampling
<br /> results, a description of the delivery method, amount of product introduced, any
<br /> deviations from the work plan, and any other details pertinent to the implementation
<br /> aspect. The first three monthly monitoring results may be submitted via email in a
<br /> tabular format within 45 days of the monitoring event, with a hard copy summary
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