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June 14, 1991 <br /> 2 0 5 4 8,0 01.0 3 Harding Lawson Associates <br /> Ms. Margaret Lagorio <br /> San Joaquin County <br /> Page 4 <br /> Task 2 - Utility Clearance <br /> We have contacted Underground Service Alert (USA) and instructed <br /> a private utility locator to evaluate the presence of <br /> underground utilities at the three proposed well locations. <br /> Such clearances are required under County and State law, and it <br /> is an important step to minimize the potential for encountering <br /> utilities during drilling or sampling. Locations of underground <br /> utilities, septic tanks and leach fields are presented on <br /> Plate 2. <br /> Task 3 - Drilling, Sampling, and Construction of Wells <br /> We propose to install three groundwater monitoring wells. The <br /> proposed locations of these wells are presented on Plate 3 . <br /> Procedures for drilling, sampling, and constructing wells is <br /> presented in the attached Appendix. HLA understands that the <br /> SJC/PHS/EHD must be notified for the grout inspection. <br /> Task 4 - Purging and Sampling of Wells <br /> We will purge the three groundwater monitoring wells and sample <br /> them in accordance with the procedures described in Appendix. <br /> The three monitoring wells will be sampled one to two days after <br /> their construction and again one month later. If gasoline <br /> constituents are detected in groundwater from the first sampling <br /> event, HLA will sample tap water from the on-site domestic well <br /> and three other private water wells in the vicinity of the site. <br /> Task 5 - Chemical Testing of Samples <br /> During drilling and sampling, we will screen each soil sample <br /> with a photoionization detector (PID) , as described in the <br /> Appendix. The two soils samples with the highest PID readings <br /> will be tested for concentrations of TPH as gasoline, in <br /> accordance with EPA Test Method 8015/5030; and for <br /> concentrations of benzene, toluene, ethylbenzene, and xylenes <br /> (BTEX) , in accordance with EPA Test Method 8020. Groundwater <br /> samples from each of the three wells will be tested for the same <br /> constituents. Additionally, as required by SJC/PHS/EHD, <br /> groundwater from MW-3 will be analyzed for fecal coliform <br /> because it is located approximately 40 feet from a septic tank <br /> and leach field. National Environmental Testing, Inc. (NET <br /> Pacific) , a state certified laboratory, located in Santa Rosa, <br /> California will analyze the soil and groundwater samples. <br />