SITE INFORMATION AND CORRESPONDENCE_FILE 2

Home Browse Search

Mr.Russell Chapin 1766 W.Monte Diablo Avenue Page 2 of 5 Attorney's Office was disbanded, and the EHD was notified that their office would no longer be able to handle requests for legal action made by the EHD. In February 1993, after review of the EHD files, the SWRCB Cleanup Fund informed Chapin Brothers, Inc., that they were not eligible for reimbursement of corrective action costs because they were out of compliance with permit requirements. Chapin Brothers, Inc., appealed this decision, and the SWRCB Cleanup Fund reinstated the site as eligible for reimbursement of corrective action costs in March 1993. The UST's at the site were finally removed on August 4, 1993. The only documented soil excavated from the site was the soil removed as part of the UST removal process. This soil was taken to the Mr. Chapin's private property for aeration and disposal. On August 6, 1993, approximately three feet of free product was observed in monitoring well MW1; the free product was removed on August 16, 1993. On August 19, 1993, and September 2, 1993, there was about one inch of free product in MW1, which was removed. In the July 1994 quarterly report, it was stated that free product was observed in MW-1, but the report did not state the thickness or indicate that it was removed. In January and May of 1995, minimal free product was observed in MW1 and MW4, which was removed. In March 1996, free product was no longer observed in the monitoring wells. In December 1993, additional monitoring wells and a vapor extraction well were installed. Soil contamination on site was encountered from depths of 10 to 35 feet below surface grade (bsg). Soil contamination, off site to the west, was encountered from 15 to 25 feet below grade. Groundwater contamination was confirmed on-site and off-site to the west. The depth to groundwater was about 21 feet bsg at that time. Soil vapor extraction (SVE) tests were conducted in June 1994 and January 1995. An air- sparge test was conducted in January 1995, and the consultant recommended vapor extraction with air sparging as a viable remedial alternative and proposed a system design. In letters dated August 18, 1995, and December 5, 1995, the EHD approved the vapor extraction with air- sparging remedial action. Operation of the vapor extraction system began in April 1997. By this time, groundwater at the site had risen to 15 feet below grade, limiting the effectiveness of the SVE system. Vapor extraction proved over time to not be as effective as originally projected, due to problems with the equipment and continued rising of the groundwater (10 feet bsg). An in situ air-sparge (IAS) system was initiated in March 1997, and was operated in conjunction with the SVE system until June 1999, but the anticipated reduction of groundwater contaminant concentrations did not occur. On April 5, 2000, a meeting was held with the EHD, the Central Valley Regional Water Quality Control Board (CVRWQCB), Mr. Chapin, and a representative from his consultant, Advanced GeoEnvironmental (AGE). It was decided that the site required further investigation, that the contaminant mass under the building needed to be assessed, and that the cleanup goals had not been met. It was felt that groundwater extraction should be reevaluated as a potential remedial option. A pumping test was performed in March 2001, which indicated that groundwater extraction was a feasible remedial alternative. The groundwater extraction system was installed in December