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Clayton ENVIRONMENTAL CONSULTANTS The monitoring wells will be drilled to an approximate depth of 25 feet below ground surface (bgs). Clayton will collect soil samples at 5 foot intervals from the monitoring wells. We anticipate that the groundwater table will be encountered approximately 15 feet bgs. If groundwater is encountered at depths less than 15 feet bgs, then Clayton will obtain three evenly spaced soil samples from ground surface to the groundwater table. No soil sample, below the saturated zone, will be collected for laboratory analysis. To aid in locating any contamination, Clayton will screen the soil cuttings during drilling using a photoionization detector (PID), and visual senses to detect petroleum compounds. If contamination is identified using the PID at depths other than at the specified sampling depth, Clayton will collect additional samples until groundwater is encountered. The soil samples will be collected in precleaned brass tubes. The brass tubes selected for analysis will be sealed with aluminum foil, plastic end caps, and immediately placed in an iced cooler for shipment to Clayton's state-certified laboratory in Pleasanton, California, for analysis. Standard chain-of-custody procedures will be followed for handling of soil samples. The monitoring wells will be extended at least 10 feet into the first encountered groundwater and constructed of 2 inch polyvinyl chloride (PVC) casing. Screened casing will be used extending one to three feet above the water table. Solid casing will then be installed to the surface. The sand pack will extend 2 feet above the screen. A 1-foot bentonite seal will be placed on top of the sand pack and the well will be sealed to the surface using cement grout. A locking cap will secure the well in a Christie box raised above the surface grade by approximately 1 inch to prevent surface run-off from entering the well head. The monitoring wells will be surveyed by a City of Stockton land surveyor using a surveyed benchmark. The surveyed elevations and locations of the wells will be used to calculate the local groundwater flow direction and gradient. 2.3 MONITORING WELL DEVELOPMENT AND SAMPLING Following completion of the wells the seal in the newly installed wells will be allowed to set for 72 hours prior to well development. The new wells then will be developed to increase their yield and to prevent sanding. Well development is accomplished by removing finer materials from the natural formations surrounding the perforated sections of the wells. Development of the well can volatilize present contaminants; therefore, the wells will be allowed to settle for another 72 hours between development and the first purging/sampling event. Water samples from the wells will be collected using clean disposable bailers. Water will be collected in clean laboratory supplied containers and placed immediately into an iced cooler for transport to Clayton's laboratory for analysis. One trip blank will be furnished in accordance with Clayton's quality assurance/quality control (QA/QC) program. The water generated from well development and sampling will be placed into DOT- approved 55-gallon drums until laboratory results from groundwater samples can be evaluated to determine the proper disposal method. The drums will be closed, labeled, and left at the site until the proper method of disposal can be determined based on laboratory analysis. 2 ACTT V E\577R9-00.W PN