SITE INFORMATION AND CORRESPONDENCE_1998-2000

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ENVIRONMENTAL AUDIT, INC. e 20'h ANNIVERSARY 1000-A Ortega Way r, j'Lji 2t4 p;1 1: 04 Placentia,CA 92870-7162 714/632-8521 714/632-6754=FAX E-mail: bstolin i:environmentalauditinc. om WD )MEMORANDUM DATE: January 20 2000 Project No. 1232 TO: MichaelInfuma San Joaquin County Publis Health Services Environmental Health Division cc: Ed Koberstein, Montgomery Ward Mark Gilmartin,Esq. FROM: Boris Stolin RE; MODIFICATION OF WELLS VEW-211, VEW-3 AND VEW-4 Montgomery Ward, Stockton Environmental Audit, Inc. (EAI) is requesting approval to modify existing wells VEW-2 , VEW-3, and VEW-4 to increase the efficiency of on-going soil and ground water remediation efforts at the above referenced site. These wells were installed in November 1996 and had been converted to in-well sparging wells by inserting a one-inch diameter sparging tube and connecting to the air sparging compressor and the vacuum blower of the oxidizer. However, due to extensive carry-over of ground water into the soil vapor collection header, air sparging air was cut-off and the wells have been used for vapor extraction only. The results of the latest ground water monitoring performed in December 1999 showed a high concentration of dissolved hydrocarbons in monitoring well MW-2, which is located next to well VEW-2B. On January 13, 2000,EAI obtained two ground water grab samples fro wells VEW-3 and VEW-9. The analytical data of grab samples show TPH concentrations of 14.3 mg/L in well VEW-3 and 1.7 mg/L in well VEW-9. The analytical results indicate that a more aggressive remediation approach should be ap lied to reduce the concentration of dissolved hydrocarbon in the vicinity of wells VEW-213, 3, and VEW-4. Instead of installing new sparging wells, EAI proposes to modify the e isting wells which have two screens: one in the unsaturated zone and one in the saturated zone The proposed modification will consist of: