SITE INFORMATION AND CORRESPONDENCE

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i 41914 Power Inn Road, Sacramento, CA 95826 (916) 452-2901 14pjD%%e0� �seOSJ�StB/11S • Fremont • Costa Mesa • Sacramento September 1 , 1987 0901GREE AGS Job # 8696 - 3 Mr . Gary Reents California Regional Water Quality Control Board ® Central Valley Region ll 3443 Routier Road 4 9987 Sacramento , CA 95827 - 3098 StP AL Subject : Crystal Cream and Butter Company Warehouse , ENVIROT /SERV C SLTH 404 West Fremont Street , Stockton , California FERMIT/ Mr . Reents : In response to your concerns expressed regarding our revised work plan for contamination delineation and mitigation at the above - referenced site , Applied GeoSystems would like to present the following statements . We agree that ground water samples are required to delineate the horizontal and vertical extent of contamination at this site . We feel that some sampling will be possible using the soil vapor probe equipment . However , we acknowledge that additional monitoring wells may be required to adequately define the j boundaries of contamination , particularly given the concerns expressed by regulatory agencies regarding delineation , monitoring , and verification . We also acknowledge that a final extraction system will require adequate definition and monitoring of contaminant boundaries . The vapor probe system will be sketched and described as fully as possible in a repairt submitted to the San Jcao,li. . Local Health District and to the Regional Water Quality Control Board . Field testing has taken place using this system . Data from these studies is largely proprietary , and not easily prepared for submission to outside agencies . We have been quite happy with the results obtained to date . With reference to concerns regarding purging of the sample chamber , we have found that low to nondetectable readings have been obtained immediately after readings in excess of 10 , 000 parts per million . This has given us confidence that the methods used are effective . Since most sampling is done in the vadose zone , head pressures are generally not a factor . If sampling is expected to occur at significant depths below the ground water surface , then the volume and pressure of the purge fluid and gas will need adjustment .