ARCHIVED REPORTS_CLEANUP PLAN - Laserfiche WebLink

Home Browse Search

S E C 0 R ' • CleanupPlan October 27, 2003 ' Page 7 1. Pre- and post-removal soil characterization within the footprint of the ethanol transfer ' facility excavation. 2. The destruction & proper abandonment of MW-14A and TW-3 by Watermark Drilling of Woodland, California. 3. The collection of post-remedial soil data in the former DE area and post-demolition ' soil data in the card-lock area. 4. The segregation, profiling, transportation and disposal of effected soil within the transfer facility excavation. A total of 397 tons of soil was removed from the ' excavated area and transported by Integrated Wastestream Management Inc. (IWM) to Forward Landfill located in Manteca, California. ' On January 21 through 29, 2003, under the supervision of SECOR, Cascade Drilling Incorporated (Cascade) completed site assessment activities performed to delineate the vertical and lateral extent of pollutants at the site. The site assessment included 15 soil ' borings (NSB-0 through NSB-4, NSB-6 through NSB-15) and 5 monitoring wells (MW-61 UA, MW-62UA, MW-63A, MW-6413, and MW-65A) (SECOR, 2003b). ■ During May of 2003, a step-drawdown test and a constant-rate aquifer pumping test were ' performed to estimate hydraulic characteristics for the Upper A-zone and the A-zone aquifers beneath the site. Results of the step-drawdown test performed in the Upper A-zone indicate the maximum sustainable extraction rate for the wells screened in this zone should lie not exceed 0.9 gpm. In addition, for effective dewatering, the spacing of wells that will be used in dewatering the Upper A-zone should also not exceed 25 feet from center to center. Results also indicate that extraction from the Upper A-zone influenced monitoring well MW- 24A, which is screened in the A-zone. This may indicate that hydraulic communication exists between the Upper A-zone and the A-zone aquifers beneath the site. Results of the constant rate aquifer pumping test performed in the A-zone determined this aquifer could sustain a pumping rate of 9.25 gpm. Also, drawdown was observed in monitoring wells located 60 feet away from the pumping well at a pumping rate of 9.25 gpm. An average value of approximately 294 ftZ/day and 0.41 was estimated for T and SY, respectively. Based ' on the A-zone saturated thickness of 20 feet, the average K estimated was 15 ft/day (0.0052 cm/sec). In addition, the zone of influence of the pumping well was calculated to be 264 feet. This was confirmed by the drawdown data observed in monitoring wells during the pumping test (SECOR, 2003c). ' During March of 2003, a 1,000-gallon transmix (tank ID 1842-6) UST was removed and selected soil samples were collected from the tank pit area. Results of soil sampling ' indicated moderate levels of petroleum hydrocarbons along the sidewalls of the tank pit. SECOR is currently working on conducting assessment activities to delineate the lateral and vertical extent of hydrocarbons associated with the UST. On September 3`d, 2003, Cascade ' installed MW-67UA to a total depth of 15 feet bgs with a screening interval of 5 to 15 feet bgs. The results and discussion of these activities will be reported in the 2003 Additional On-Site Assessment Report. ' In July of 2003, SECOR submitted a Feasibility Study Report and Site Assessment Work Plan, which presented a discussion of the objectives of the feasibility study, site background, ' description and evaluation of each remedial action alternative, potential impacts of each ' I:\Chevron\1001621\REPORTS\2003\2003-Cleanup Plan\Cleanup Plan.doc