ARCHIVED REPORTS_XR0012364 - Laserfiche WebLink

Home Browse Search

l ENV IRONMEN1 AL HEALTH D E■ ARTNtIENT SAN JOAQUIN COUNTY !v,j• >h 1?onnu K Horan,R E H S Lail Supervisors --"' 304 East Weber Avenue,Third Floor Carl Borginan,R h H s ! Arector Mike Iiugginc R E H SR D I s W ` J Al Olsen,R E H 5 Stockton, California 95202-2708 DouglaWilson,R E 1-19 ^�r .ON t'rograri hfunagcr Telephone (209)468-3420 Ivl-trgaret Lagono,R E H S Laurie A Catulla,R E H S Pro r am Manu er Fax (209) 464-0138 Robert McClcilen,R E H S $ M irk 3lreellos,R F H 5 JOHN FRARY APR 2 9 2005 UNION OIL, CC14PANY 276 TANK FARM ROAD P O BOX 1069 SAN LUIS OBISPO CA 93406 RE Former Unocal#2859 and Former Unocal#0187 f 1665 Pacific Avenue 437 E Miner Street f Stockton, CA Stockton, CA San Joaquin County Environmental Health Department (EHD) has reviewed the"Response to Agency Request for Additional Subsurface Data" (Response) dated August 30, 2004, prepared by ENSR International (ENSR)for the 1665 Pacific Avenue site In addition, Nuel Henderson and myself from EHD and James Barton from the Central Valley Regional Water Quality Control Board met with Ryan Harding from ENSR. on April 5, 2005, to discuss the above referenced sites The August 30, 2004, Response did not provide any information about the source of the 1,2- DCA found in the groundwater samples collected from monitoring wells on site and off site in fact, the response focused on lead sampling of the soil instead of 1,2-DCA Since the April 5, 2005, meeting I have reviewed mformation m EHD flies on other sites in this area to determine if there is information indicating another possible source of origination of the 1,2-DCA and have not identified any, so I would conclude that the 1665 Pacific Avenue site is the source of the 1,2- DCA contamination At the April 5, 2005, meeting, Ryan Harding explained that the above referenced sites were on ! the Union Oil Company (UOC)"Portfolio of Reduction Sites" Apparently these are sites that UOC wants to aggressively remediate and get closed as soon as possible It was also explained that since there have been problems with operation of the ozone remedial systems at the sites (i a tubing conveying the ozone to the wells breaks down and some ozone injection wells being screened at too great of a depth for the compressor to force the ozone injection), use of the ozone rerredial systems are being re-evaluated ENSR on behalf of UOC may propose air sparging as a remedial alternative It was discussed that vapor extraction should be performed in conjunction with air sparging and that feasibility tests should be conducted after installation of some initial air sparge and vapor extraction wells it was also discussed that both sites have existing vapor extraction wells but that they may not be in the right location or screened in appropriate intervals It was also discussed that vapor extraction and air sparge welts should be constructed in separate borings It was discussed that a work pian for any proposed site work must be submitted to EHD for evaluation and cornmentlapproval Remediation of the 1,2-DCA contaminant plume at 1665 Pacific Avenue must be includi,d in as v.ell as evaluated in choosing the remedial action to be performed at the site