Laserfiche WebLink
March 10, 1999 <br /> described in written format. Please provide this office with a copy of the notification ASAP. <br /> PHS/EHD will post the site upon approval of the notice. <br /> 2. Shoring of the excavation area on one side and one length are proposed(connected at intersecting <br /> right angles), no shoring on the remaining sides. Sloping is proposed on the other sides. It is likely <br /> given the soil types (sands/silts)that a 1:1 slope may be required. In order to reach contaminants <br /> between 15 and 20' bgs at a distance 20' laterally from the former tank pit the sloping would need <br /> to begin approximately 40 feet from the former tank pit. Given this approach a site walk should <br /> occur to ensure that equipment can operate between the building and area of ponded water. <br /> Shoring the entire excavation may become a more viable approach. <br /> 3. Analyses of water stored on-site in temporary tanks must occur. The purpose of analyses includes <br /> determining the mass of contaminants removed, treatment and final disposition evaluation (GAC or <br /> Off haul). Please provide a detailed plan to characterize the accumulated de-watering effort ASAP. <br /> 4. Clean backfill shall be low permeability materials in the vadose zone to reduce the potential for a <br /> hydraulic head to develop over a high permeability sink which could push residual contamination to <br /> the aquifer and off-site. <br /> 5. During field activities including excavation, soil management and segregation a Flame Ionization <br /> Detector(FID)shall be utilized given the lack of sensitivity of the Photo Ionization Detector(PID)to <br /> diesel range components. <br /> 6. Stockpile sampling shall be modified to allow only 2 samples per 50 yards of soil not 4 per 50 yards. <br /> Samples must be composited at the laboratory not in the field. <br /> 7. The plan fails to address past-remediation monitoring. In accordance with corrective action <br /> regulation any remedial action plan must be followed with a method by which the effectiveness of <br /> the remediation effort may be evaluated (Verification Monitoring Phase). Examples include <br /> confirmation boreholes and sampling of soil, monitor well installation to assess plume contaminant <br /> concentrations, mass and migration potential. Please submit a detailed post-remediation <br /> monitoring plan. Protection of the nearby municipal well field and beneficial use waters of the state <br /> shall remain the focus of this agency. Submit a post-remediation monitoring plan ASAP. <br /> Should you have questions regarding this correspondence please contact me at (209) 468-0342. <br /> Thanks, Ron. <br /> ENVIRONMENTAL_HEALTH DIVISION <br /> 304 E. Weber Ave.Third Floor <br /> P O. Box 388, Stoc n CA 95201-0388 <br /> Approved <br /> Denied ❑ <br /> W �Conditions <br /> Dateby <br /> 9 Page 2 <br />