ARCHIVED REPORTS_XR0002180 - Laserfiche WebLink

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Page 2,2360 Grant Line Road Two remedial methods were tested for feasibility for interim remediation at(his site, oxygen injection and groundwater extraction One sparge point and one extraction well were installed to conduct these tests The oxygen injection test was conducted on June 21, 2004 SECOR injected 150 cubic feet of oxygen over a period of 30 minutes Dissolved oxygen cancentralions In observation wells located approximately 5 and 10 feet from the injection point were measured immediately before and after the injection Concentrations of dissolved oxygen increased an average of only 0 1 milligrams per liter in the measurement taken after the injection Based on this result, SECOR recommends that oxygen injection is not a feasible remedial alternative for this site However, in the"Work flan for Additional Site Assessment and Intenm Remediation, SECOR had proposed to inject 150-300 cubic feet of oxygen over a period of up to two hours, and to take dissolved oxygen measurement readings in the observation welts 24 hours after the injection Before SECOR dismisses oxygen injection as a remedial option at this site, SJCIEHD considers that the test should be conducted as proposed and approved,or a justification and vabdation for the test method employed should be presented to SJCIEHD for further evaluation Please demonstrate the test design as conducted provided adequate response time for dissolved oxygen to migrate through fine grained sod to the observation wells The groundwater extraction tests were conducted August 11-12, 2004 A step drawdown test was followed by a 24-hour constant rate pumping lest SECOR reported that during the constant rate lest, the maximum drawdown in the observation wells was 0 09 feet in well S-1 and 0 07 feet in well MW-5 SECOR stated that they considered this observed drawdown to be due to earth tides, and the values were therefore not used in the data analysis Please provide a demonstration to SJCIEHD that the observed drawdown was an effect of"earth tides" Maximum drawdown in the extraction well, EX-'I,was 6 17 feel This data was used in the analysis using the AQTESOLV and FLOWPATH modeling software From the models SECOR predicted a capture zone of°280 feet in the 'a'direction and 440 feet in the W direction" SECOR proposes to conduct an extended groundwater pump test"to confirm the ROI and drawdown calculations determined during the 48-hour pump test "Although a 24-hour pump lest has been performed at the site, and SECOR has not yet stated what the target ROI has been determined to be.SJCIEHD approves conducting an extended groundwater pumping test Please submit a work plan addendum by April 1,2005 describing the pumping test design SJCIEHD recommends designing the test so that earth tidal effects can be demonstrated and compensated for in the test evaluation If necessary, piezometers should be installed to obtain drawdown measurements closer to the pumping well to help compensate for pumping well inefficiency and its effect on the evaluated hydraulic conductivity In addition, please submit a work plan to continue the investigation of the vertical and lateral extent of the documented contamination by the same date If you have any questions please call Lori Duncan at(209)468-0337 Donna Heran,REHS,Director Environmental Health Department Lon Duncan, Senior REHS Nuel C Henderson,Jr , RG LOP/Site Mitigation Unit IV LOP/Site Mitigation Unit IV cc James Barton CVRWQCB JaFE Auchler[orne, SECOR I