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(:Vl� kTc Nwo� <br /> A S S 0 C I A T E S I N C . <br /> Groundwater Monitoring Wells Construction Details <br /> Up to three of the soil borings may be completed as groundwater monitoring wells. The <br /> monitoring wells will be constructed of 2-inch inside diameter schedule 40 PVC well screen and <br /> casing. A 0.020-inch well screen slot and #2/12 mesh sand pack will be used. Neat cement will <br /> be used to seal the wells in accordance with California Well Standards (December 1981). To <br /> protect the integrity of the wells, locking, water-tight well plugs will be installed on each well and <br /> a water-tight wellhead labeled "monitoring well" will be concreted over each well. Proposed well <br /> construction details are shown on Figure 3. If all three borings are completed as wells, then the <br /> top of casing of the new wellheads will be surveyed to assess groundwater gradient and flow <br /> direction. All drill cuttings will be stored on site in 55-gallon drums pending laboratory results. <br /> Sample Analysis <br /> Selected soil samples will be immediately placed on ice and delivered under chain-of-custody <br /> documentation to a State-certified laboratory for analysis. Samples will be analyzed for total <br /> petroleum hydrocarbons as diesel (TPHd, EPA Method 8015), and benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX, EPA Method 8020). <br /> Well Development and Groundwater Sampling <br /> If groundwater monitoring wells are installed at the site, measurement of depth to water in all <br /> wells will be completed to evaluate the direction and magnitude of the groundwater gradient <br /> beneath the site. The new wells will be developed using surge and bail techniques until the <br /> produced water is relatively sediment free. Prior to the collection of groundwater samples, a <br /> minimum of three well volumes (casing and sand pack) will be purged. Temperature, pH, and <br /> electric conductivity will be measured and allowed to stabilize. Water samples will be collected <br /> using disposable bailers, one dedicated to each well. <br /> Groundwater samples collected from all monitoring wells will be submitted using chain-of- <br /> custody record to a State-certified laboratory. Groundwater samples, three total, will be analyzed <br /> for TPHd and BTEX. Purge water will be stored in 55-gallon drums approved for hazardous <br /> liquid storage pending laboratory results. <br /> Report Preparation <br /> Upon completion of the boring/well installation and development activities, a summary report will <br /> be prepared for submittal to PHS/EHD. The report will include a description of all field activities, <br /> laboratory analytical results, and well/boring logs. <br /> All work described in this workplan will be performed under the direction of a California <br /> Registered Professional Engineer. All work will be performed in accordance with ATC's Site <br /> wA62574.06wcportslwkpwe1.doc 3 <br />