SITE INFORMATION AND CORRESPONDENCE 1994-2010

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San Joaquin County DIRECTOR Donna Heran. REHS Environmental Health Department �, �_,��'•.G F' ASSISTANT DIRECTOR 600 East Main Street Laurie Cotulla, REHS N: { Stockton, California 95202-3029 PROGRAM COORDINATORS Mike Huggins, REHS, RDI c ' - � Website: www.s ov.or /ehd Margaret Lagorio, REHS 9�i Fi 60 jg g Robert McClellon, REHS Phone: (209) 468-3420 Jeff Carruesco,REHS, RDI Fax: (209) 464-0138 Kasey Foley, REHS December 23, 2008 Mr. Weldon Church 1958 Yosemite Road Berkeley, California 94707 Subject: Weldon Church Property 104 West Beverly Place Tracy, California 95376 The San Joaquin County Environmental Health Department (EHD) has reviewed Soil Vapor Survey Work Plan Addendum — October 2008, dated October 24, 2008, prepared and submitted by Advanced GeoEnvironmental, Inc. (AGE) on your behalf. (On December 5, 2008, AGE provided the EHD with a site map illustrating overhead electrical utility line locations that were not inclUded in the original addendum.) AGE proposes to relocate five soil vapor borings adjacent to the site residence using a hand auger to advance the borings to depths of three-and-a-half feet below surface grade (bsg) instead of the originally proposed depth of five feet bsg. Two soil vapor borings remain at the originally proposed location north and west of the former underground storage tank site. Once the borings have been advanced, AGE proposes to install dedicated temporary vapor points within each borehole. Although it is not stated in the addendum, AGE has informed the EHD that soil gas samples are proposed to be collected on the same day the vapor points are installed and soil vapor borings will be abandoned on that same day by removing the vapor points and backfilling the borehole with portland cement from total depth to surface grade. The EHD approves the work plan addendum with the following conditions. The target depth of each boring should be five feet, but should not penetrate into the capillary fringe zone as the soil will be at or near saturation with groundwater. If the capillary fringe zone is reached at depths less than three-and-a-half feet bsg, abandon the boring. Setting the borings at or near the maximum practical depth for the vapor probe will minimize the effects of changes in barometric pressure, temperature, or breakthrough of ambient air from the surface and ensure the integrity of soil vapor samples is not compromised. Install the soil vapor points to depths of approximately five feet, if possible. Purge volume test, leak test, and soil gas sampling should not be conducted for at least forty- eilht hours after the soil gas probe installation. Following sample collection, remove casings, soil vapor points, sand and bentonite, then hand auger the borings to total depth and backfill the borehole with portland cement from total depth to surface.