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cvvi 0 A S S O C I A T E S I N C Placement of Borings and Wells To evaluate the vertical extent of impacted soil and groundwater, the 45 -foot soil boring will be located near soil borings SB6 and SB8 To evaluate the lateral extent of impacted soil and groundwater, one boring will be located southwest of soil boring SB 10, and one boring will be located north of soil boring SB2 The estimated groundwater flow direction is to the northeast Proposed boring locations are shown on Figure 2 Groundwater Monitoring Wells Construction Details The 45 -foot soil boring will be filled with a concrete/bentonite slurry from 45 feet below ground surface (bgs) to 35 feet bgs All borings will then be completed as groundwater monitoring wells The monitoring wells will be constructed of 2 -inch inside diameter schedule 40 PVC well screen and casing A 0 020 -inch well screen slot and #2/12 mesh sand pack will be used Neat cement will be used to seal the wells in accordance with California Well Standards (December 198 1) To protect the integrity of the wells, locking, water -tight well plugs will be installed on each well and a water -tight wellhead labeled "monitoring well" will be concreted over each well Proposed well construction details are shown on Figure 3 The top of casing of the new wellheads will be surveyed to assess groundwater gradient and flow direction All drill cuttings will be stored on site in 55 -gallon drums pending laboratory results Sample Analysis Selected soil samples, at least two from each boring, will be immediately placed on ice and delivered under chain -of -custody documentation to a State -certified laboratory for analysis Samples will be analyzed for total petroleum hydrocarbons as gasoline (TPHg, EPA Method 8015), total petroleum hydrocarbons as diesel (TPHd, EPA Method 8015), benzene, toluene, ethylbenzene, and xylenes (BTEX, EPA Method 8020), and oxygenate fuel additives (EPA Method 8260) Well Development and Groundwater Sampling Measurement of depth to water in all wells will be completed to evaluate the direction and magnitude of the groundwater gradient beneath the site The new wells will be developed using surge and bail techniques until the produced water is relatively sediment free Prior to the collection of groundwater samples, a minimum of three well volumes (casing and sand pack) will be purged Temperature, pH, water elevation, and electric conductivity will be measured and allowed to stabilize Water samples will be collected using disposable bailers, one dedicated to each well Groundwater samples collected from all momtonng wells will be submitted using chain -of - custody record to a State -certified laboratory Groundwater samples, three total, will be analyzed w k14981\reports\wkpwet doc 3