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A S S O C I A T E S I N C <br /> determine the vertical extent of soil and groundwater contamination, one soil boring will be <br /> advanced to approximately 70 feet bgs. This boring will be grouted to approximately 57 feet bgs <br /> and completed as a groundwater monitoring well. If soil contamination is observed in the soil <br /> samples collected from the bottom of the deep boring, a deep nested well will be completed to a <br /> depth of 70 feet bgs in the same borehole as & shallow well. A contingency cost for the <br /> installation, development, and sampling and analysis of the deep nested well is contained in <br /> Attachment 1. <br /> Groundwater Monitoring Wells Construction Details <br /> The soil borings will be completed as groundwater monitoring wells. The monitoring wells will <br /> be constructed of 2-inch inside diameter schedule 40 PVC well screen and casing. A 0.020-inch <br /> well screen slot and 42112 mesh sand pack will be used. Neat cement will be used to seal the <br /> wells in accordance with California Well Standards (December 1981). To protect the integrity of <br /> the wells, locking, water-tight well plugs will be installed on each well and a water-tight wellhead <br /> labeled "monitoring well" will be concreted over each well. The top of casing of the new <br /> wellheads will be surveyed to assess groundwater gradient and flow direction. <br /> Soil 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 TPHg, <br /> TPHd, total petroleum hydrocarbons as Stoddard Solvents (TPHss, EPA Method 8015), and <br /> BTEX). <br /> Task.4: Groundwater Monitoring Well Development <br /> Measurement of depth to water in all wells will be completed to evaluate the direction and <br /> magnitude of the groundwater gradient beneath the site. The new wells will be developed using <br /> surge and bail techniques until the produced water is relatively sediment free. Prior to the <br /> collection of groundwater samples, a minimum of three well volumes (casing and sand pack) will <br /> be purged. Temperature, pH, water elevation, and electric conductivity will be measured and <br /> allowed to stabilize. Water samples will be collected using disposable bailers, one dedicated to <br /> each well. <br /> Groundwater samples will be submitted using chain-of-custody record to a State-certified <br /> laboratory. Groundwater samples will be analyzed for TPHg, TPHd, TPHss, BTEX, and <br /> oxygenate fuel additives (EPA Method 8260). Purge water will be stored on site in 55-gallon <br /> drums approved for hazardous liquid storage pending laboratory analysis. <br /> w:lproposal1p910001p9101 Sb.doc 3 <br />