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AUG 17 '99 15: 10 FR LFR ROSEVILLE 916 78G 0366 TO 9-12094693433 P.04/08 <br /> LFR Levine•Fricke DRAFT <br /> 5.2.2 Pressure Data <br /> Extraction well VEW-1 operated at a vacuum of approximately 0.8 to 2.1 inches of <br /> mercury at a flow rate of approximately 62 to 85 cubic feet per minute. A pressure <br /> response was observed in each of the SVE vapor piezometers during the test. As <br /> expected, the observed pressure response decreased with distance from the SVE <br /> extraction well. For example, a vacuum pressure of 3.32, 0.94, and 0.17 inches of <br /> water was measured in piezometers PZ-4, PZ-5, and PZ-6 located approximately 10, <br /> 20, and 35 feet, respectively from VEW-1. A vacuum pressure of 0.010 inches of water <br /> was also measured in well N-6, located approximately 50 feet away from VEW-1. <br /> These data indicate that the effective radius of influence of an SVE well at the site is <br /> greater than 30 feet. <br /> 6.0 RECOMMENDATIONS FOR FURTHER WORK <br /> Results of this and previous investigations indicate that petroleum hydrocarbons released <br /> in 1986 have impacted both shallow soil and groundwater on the north and south sides <br /> of Cook Road. The results of this investigation characterized the lateral extent of <br /> petroleum hydrocarbon-affected soil and groundwater south of Cook Road and suggest <br /> that SVE would be an appropriate remedial measure for mass/source removal in this <br /> portion of the site. The results of this investigation also revealed that petroleum-affected <br /> groundwater may extend to depths of at least 40 feet bgs and that further assessment of <br /> the vertical extent of petroleum-affected groundwater is necessary. <br /> Based on these data and the presence of free product at the site, LFR recommends: <br /> • Further groundwater investigation to assess the vertical extent of petroleum <br /> hydrocarbons in groundwater beneath the site; <br /> • Installation of a shallow groundwater monitoring well in the southeastern portion of <br /> the site (as requested by the RWQCB); and <br /> • Installation of a SVE system to address petroleum-affected soil and groundwater <br /> (source removal) south of Cook Road in conjunction with the existing GWET <br /> system. <br /> The following sections describe the proposed scope of work to implement these <br /> recommendations. <br /> 7.0 SCOPE OF WORK <br /> The proposed Scope of Work to address the above recommendations consists of the <br /> following tasks <br /> • Task 1: Lithologic and Deeper Groundwater Investigation <br /> Page 10 no�c.ra.wp:EBF <br />