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10/11/2002 13:06 707-585-2900 VERTEX ENG PAGE 07/13 4.1, GROUNDWATER SAMPLE LOCATIONS Four locations will be selected in order to sample groundwater along the western property boundary. Prior to on-site drilling, the proposed soil boring/groundwater monitoring well locations will be marked with white paint. Underground Service Alert (USA) will, be notified at least 48 hours prior to drilling to identify adjacent public utilities. Also prior to drilling, a geophysical utility survey will be conducted in the area of investigation to identify the alignment of underground utilities in the vicinity of proposed boring locations. The survey methods consist of the use of electromagnetic line locating (BMLL) equipment. The location of potential underground obstructions will be marked with paint on the ground surface. The ,results of the utility survey will be used to place final locations for drilling activities. 4.2 GROUNDWATER SAMPLING AND ANALYSIS The driller will use Direct Push Technology(DPT) to collect isolatedab gr groundwater samples. Isolated grab sampling is a common practice when the aquifer offers sufficient recharging to provide the desired volumes in a short amount of time, and when soil sampling above the groundwater is not required. The driller will utilize a screen Point 15 Sampler to collect groundwater samples at each location. The Screen Point 15 Sampler is a common tool for groundwater grab samples. The sampler is comprised of a hollow cylindrical sheath of hardened steel that measures four feet in length with. an outside diameter (OD) of 1.5 inches. An expendable drive point and a drive head are placed on either end of the sampler, which is then driven,to the desired depth, The Screen.Point 15 uses either a stainless steel screen or a Schedule 80 PVC screen that is sealed inside the sheath with Neoprene 0-rings to prevent infiltration of formation fluids until the desired depth is attained. The DPT drilling method dramatically reduces soil cuttings from traditional drilling applications. As with most direct push applications, it provides time and. cost efficiencies over traditional drilling as well. Investigation derived waste (EDW) consisting of soil cuttings and/or water will be containerized in an approved and labeled 55-gallon drum and stored in an appropriate Iocation at the site until analytical results are received and reviewed. Then the containerized EDW will be removed from the site in an appropriate mariner. Temporary DPT monitoring wells will be sampled, using a peristaltic pump, Teflon tubing or clean bailer/new disposable bailer. A peristaltic pump, Teflon tubing or bailer will be used f0 purging and sampling. The procedure for groundwater sampling is listed below: • Groundwater will be sampled as soon as possible after purging is completed. If the monitoring well becomes dry (i.e., all. groundwater is removed) it will be sampled as soon as sufficient volume has recharged; • The sampling container, preservation, and holding time requirements will meet the method specifications; 3