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Mr. Harlan Knoll, R.E.ti.S. <br />November 29, 2005 <br />Page 3 <br />direction, thereby prolonging soil source contribution to the groundwater contamination. MW -3 <br />is also at the center of the groundwater mound that has been persistent over the last several years <br />and may be in hydraulic connection with the former excavation backfill. <br />Further evaluation for performing groundwater extraction from monitoring wells MW -3 and <br />MW -4 will be investigated by conducting and assessing a well performance test (aka, step <br />drawdown test) in each of these two inch monitoring wells. Should a longer test be determined to <br />be feasible, a constant rate test will be designed and performed in either or both of these wells. <br />4.0 Disposal Options for Extracted Groundwater <br />There are four potential possibilities for the disposal of extracted groundwater: <br />1. Discharge to POTW via Sanitary sewer connection. <br />2. Off-site transportation for treatment/disposal. <br />3. Discharge via NPDES Permit. <br />4. Land surface discharge <br />Option 1, discharging untreated groundwater to the Local POTW, would not be available <br />because, according to the San Joaquin County Public Works Department, the only sanitary sewer <br />connection in the local area is for the exclusive use of the local housing authority. <br />Option 2 seems to be the most practical and cost effective. Extracted groundwater would be <br />collected in one or more above ground tanks. A local transporter would be contracted to transport <br />the groundwater to In-Strat Environmental, in Rio Vista, California for disposal by deep well <br />injection. <br />Disposal Options 3 requires the purchase of treatment equipment and requires costly and lengthy <br />permitting processes that are impractical for the relatively small quantities of extracted <br />groundwater expected from this investigation. Further evaluation of Option 3 will be assessed <br />following completion of the evaluation of performing groundwater extraction from monitoring <br />wells MW -3 and MW -4 <br />Disposal Option 4 also requires the purchase of treatment equipment and the costly and lengthy <br />permitting processes impractical for the relatively small quantities of extracted groundwater <br />expected from this investigation. Furthermore, there is insufficient useable land area on the <br />property for disposal option 4. <br />1 20GEOL A GROUNDWATER CONSULTANCY <br />