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UI-U414 IZAM rKUM PT k�[s lj I 1U MU946401H P004/U07 <br /> Mr. Derrick Adac • <br /> December 17 , 1493 <br /> Page 4 <br /> Recommandation! <br /> Additional soil sampling and analysis is required to support <br /> an attenuation hypothesis for chlorinated hydrocarbon <br /> contamination north of the tank area. GSU recommends ground <br /> water sampling to confirm the absence of solvents in that media <br /> (see Comment 1) . <br /> General Comment 4: WZI Recommendations <br /> WZI recommends that a Proposed Remedial Action Plan be <br /> prepared which addresses removing soil material around the tank, <br /> cleaning and abandoning the tank, and capping the tank area. <br /> The concrete tank may qualify as a leaking underground fuel <br /> tank, and as such require evaluation by the RWQCB. Remediation <br /> for underground tanks could require complete removal of the tank <br /> and ground water monitoring. <br /> Recommendation: <br /> GSU recommends contacting the RWQCB to determine if the tank <br /> remediation is under their jurisdiction and for the appropriate <br /> procedures to follow. <br /> specific remedial design discussions related to the RAP will <br /> be addressed in the following section. <br /> B. REAEDIAL ACTION PLAN <br /> summary statement <br /> As stated in the RAP, "The proposed Remedial Action Plan for <br /> the LCN site includes: cleaning and rinsing all liquid from the <br /> concrete tank, disconnection of all piping related to the tank <br /> and removal or filling with inert material, excavation of <br /> hydrocarbon impacted soil immediately adjacent to the tank to a <br /> depth of approximately 20 feet and backfilling with clean sand <br /> or fill gravel, filling the tank with clean sand, and placing <br /> and impermeable cap over the entire site." Additionally, the RAP <br /> states, 'The potential impact to local ground water due to <br /> chlorinated hydrocarbons is not part of this proposed action <br /> plan. It will be addressed separately." <br /> General Comment 1: Soil Excavation <br /> Removal of contaminated sail adjacent to the tank as <br /> described in the RAP and associated figures indicates that <br /> approximately 38 percent of the potential contaminated soil <br /> volume would be removed if it is assumed that similar <br /> contamination exists beneath the tank and to the south. The <br /> extent and distribution of hydrocarbons directly beneath the <br />