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Ms. Bazeley <br /> June 5, 1996 <br /> Page 3 <br /> assessment . If rebound is not observed for three consecutive <br /> assessment events, monitoring will be conducted. Vapor <br /> monitoring wells will be monitored monthly. <br /> DTSC Comment: Monitoring events should include the <br /> collection of soil gas samples from both extraction wells and <br /> monitoring wells . <br /> 6 . Page 9 . Section 5 . "SVE SYSTEM OPERATIONS TERMINATION" . <br /> The first paragraph "Closure with residual VOCs in soil may <br /> entail a risk assessment to determine whether groundwater quality <br /> could be affected by the remaining VOCs . " <br /> DTSC Comment: This paragraph needs to be clarified to <br /> include the following information: <br /> Closure with residual VOCs in soil should entail the <br /> following three requirements : <br /> (1) Assessment of the impact on groundwater quality from the <br /> remaining soil contamination based on the active soil gas <br /> confirmation sampling results; and <br /> (2) Risk assessment of the impact on public health and safety <br /> may be required based on the active soil gas sampling <br /> results; and <br /> (3) Deed restriction may apply if it is deemed necessary by the <br /> risk assessment . <br /> 7 . Page 9 . The first paragraph. The last sentence "Clean <br /> closure requires completion of a closure report . . . " <br /> DTSC Comment : Soil gas confirmation sampling will be <br /> required in addition to a closure report as specified in the <br /> DTSC' s April letter. <br /> 8 . Page 11 . Terminology. <br /> (1) Clean closure : Clean closure requires no further action <br /> other than a closure report . <br /> DTSC Comment: As stated in DTSC comment #9, soil gas <br /> confirmation sampling is required in addition to a closure <br /> report . <br /> Additionally, the definition for closure requirement with <br /> residual VOCs in soils needs to be amended to reflect DTSC' s <br /> comment #7 . <br />