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r <br /> F <br /> � + 1 <br /> e <br /> t Mrs. Diane Hinson, RENS August 7, 1991 <br /> San Joaquin County Environmental Health <br /> PO Box 2009 <br /> Stockton, CA 95201 <br /> RE: Addendum to site investigation/remediation to inhance the <br /> ` -- - vapor recovery from contaminated soil near extraction - well P3, <br /> Regal Station 604, 1448 N. E1 Dorado Street, Stockton, California, <br /> Figures 1 and 2. <br /> Dear Mrs. Hinson: <br /> As to our phone conversation on August 6, 1991, this addendum work <br /> plan details the procedures to install a vapor recovery swarm well <br /> (P3 A,B,C,D) to inhance vapor recovery at product dispensing area <br /> well P3. Due to the low porosity nature of the native soil in <br /> s this area we are experiencing low flow rates from extraction well <br /> P3. The added well(s) should greatly enhance vapor recovery and <br /> shorten the remediation of the soil contamination for this site. <br /> WELL PLACEMENT <br /> 4 <br /> Swarm well P3 A,B,C,D will be placed 10 feet north, 10 feet south, <br /> 10 feet east and 10 feet west of the existing P3 well. The <br /> well(s) will be manifolded from P3 to the 2" PVC tubing for vapor <br /> extraction, see Figure 3. <br /> WELL BORING(S) <br /> Each individual well that forms the swarm will be drilled to the <br /> 35-40 foot depth using Hogate Drilling Mobil B40 frilling rig with <br /> 8" hollow stem augers. Bill Hogate (C57 #401530) the driller will <br /> act as safety officer and be re4ponsible for generating the boring <br /> and well construction logs. Bill will also install the wells and <br /> call for the grout inspection. , <br /> Each boring (P3A, P3B, P3C, and P3D) will be advanced to the 40 <br /> foot depth. A sample will be obtained for analysis in Western <br /> Geo-Engineers (WEGE) non-certified portable laboratory at either <br /> the 30 or 35 foot depth, dependent upon which interval field <br /> screens as the higher in contamination. WEGE will perform DHS <br /> headspace method analysis for Total Fuel Hydrocarbons with <br /> Benzene, Toluene, Ethlybenzene and Total Xylene isomeres (TFH- <br /> S BTEX) on the selected samples. <br /> Field screen of the samples will be performed with a hand held <br /> photoionizing detector (PTD) with a 10.2 ev bulb, wha.ch has been <br /> calibrated with a 100 ppm Isobutylene in air standard is <br /> E equivalent to 54 ppm benzene in air vapor. <br /> WELL CONSTRUCTION <br /> page 1 <br />