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P 7 1 PEX44�-Mldison Avenue,Suite 106 • Fair Oaks,{A 95628 E N V I R 0 T E C H , I N C . 1.800.242.5249 • Ph.916.535.0200 • Fax 916.535.0207 April 3, 1996 Ms. M. Lagorio San Joaquin County Environmental Health Division Post Office Box 2009 Stockton, California 95201 Subject: Soil Boring Verification Workplan Addendum Moore Petroleum, Inc. 1399 East Yosemite Ave., Manteca, California Apex Project No. ERA02.006 Dear Ms. Lagorio: Apex Envirotech, Inc. (Apex), has been authorized by Moore Petroleum, Inc. (Moore Petroleum), to submit this Workplan Addendum at the subject site (Figure 1). VERIFICATION SOII, BORINGS Apex proposes to drill two angle soil borings(VSB-1 and VSB-2)for the purpose of verifying the absence of petroleum impacted soil beneath the former tank basin. All field work and sampling will be in accordance to Apex's Standard Operating Procedures(SOP)located in Attachment 1. Figure 2 shows the locations of the two proposed angle soil borings. The two proposed verification soil borings will be drilled at an angle of 30 degrees measured from vertical. The approximate depth of the former tank basin is 15 feet below grade. To insure that we do not drill through any backfill material, which is pea gravel, the two soil borings must be at least 26 feet away from the former tank basin based on a 30 degree angle boring. The purpose of not drilling through any pea gravel is to eliminate any possibility of under mining the site. The two borings will be drilled with the use of a hollow stem auger drill rig and with the use of 8-inch diameter augers. Soil sampling will begin at 10 feet of drilled depth, which is 8 feet below grade. Soil samples will be collected at drilled depth of 10,15, 20, 25 and 30 feet. This corresponds to 8, 12, 16, 20, and 23 feet below grade. Three soil samples from each boring will be selected in the field based on PID field screening and observations by Apex Field Geologist and a representative of San Joaquin County Environmental Health. The six soil samples, three from each boring, will be analyzed for TPH, as gasoline, and BTEX.