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June 13, 1997 <br /> Page 4 V <br /> wells (VW-I through VW-3) screened in the 9- to 53-foot depth interval. The system <br /> was successful in removing remaining hydrocarbons in the vadose zone. Approximately <br /> Y <br /> F 2,745 pounds of total purgeable petroleum hydrocarbons (TPPH) and 12 <br /> pounds of <br /> benzene were removed. <br /> Current Site Status. SJCEHD has determined that the both soil and.groundwater <br /> assessment has been completed and the plume appears stable (Attachment B). All <br /> potentially hydrocarbon-impacted.soil has been either removed by excavation or reme- <br /> diated through SVE. No SPH has ever been detected in any monitoring wells. The <br /> remaining dissolved-phase plume is concentrated in the eastern portion of the site. Off- <br /> site <br /> ffsite migration is apparently limited to less than 100 feet (Figure C-5). <br /> In their letter dated January 9, 1997, SJCEHD requested additional information regard- <br /> ing the potential for natural attenuation of hydrocarbons. Specifically. <br /> • Data on the presence of hydrocarbon degrading bacteria, oxygen, or <br /> other available electron acceptors, nitrogen, phosphorous, potassium <br /> values, soil porosity, and organic carbon content. <br /> • A survey of wells within 2,000 feet of the site and nearby pathways <br /> such as basements and utility line trenches. <br /> • A feasibility study and corrective action plan. <br /> • Continued quarterly monitoring. <br /> In a letter dated February 7, 1997, Unocal responded that this site poses no threat to <br /> human health and safety or the environment and that further assessment and active <br /> corrective action was unwarranted (Attachment B). Unocal concluded that the site was <br /> suitable for closure as a low-risk groundwater case. In a letter dated March 3, 1997, <br /> SJCEHD denied Unocal's request for site closure (Attachment B). <br /> f EVALUATION OF SITE FOR CLOSURE (1.G.) <br /> PACIFIC requests that the Fund Manager consider the following current site conditions <br /> when evaluating the site's eligibility for closure. <br /> • Shallow impacted soil identified at the site has been remediated via <br /> excavation and soil vapor extraction. Thus, soil potentially saturated <br /> with petroleum in the immediate vicinity of the former source(s) has i <br /> apparently been removed or remediated. <br /> • The health risk due to ingestion or dermal contact with soil affected by <br /> the discharge is reasonably abated, since the shallow hydrocarbon- i <br /> impacted soil has been excavated. <br /> 3100405A\C 1.S RE.DOC <br /> L <br />