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s <br /> page 2, 1305 Escalon Ave. <br /> The cross sections included in the report incorrectly identify MW-1, VEW-3 and VEW-4 <br /> as being located in the former tank pit area. Please inform GTI that the former tank pit at <br /> this site was located on the southern edge of the property, and provide them with a <br /> detailed, scaled site map if necessary. MW-1, VEW-3 and VEW-4 are located near the <br /> former location of the northern dispenser island, which is considered to be the <br /> contaminant source area. Complete, accurate and properly labeled cross sections must <br /> be provided to PHS/EHD prior to the initiation of any remedial work at this site. A <br /> standard explanation should be included with the cross section that defines all units, <br /> abbreviations, and symbols used, as well as the horizontal and vertical scales used to <br /> create the drawing. <br /> The report concludes that the four soil vapor extraction wells currently on site should <br /> adequately address the vadose zone of contamination, but the report never specifically <br /> states what the radius of influence of each well is expected to be nor does it provide a <br /> calculation of the target soil contaminant mass. <br /> Comments-Corrective Action Plan <br /> The "Corrective Action Plan" (CAP) discusses GTI's proposed methodology for <br /> mitigation of the documented petroleum hydrocarbon contamination at this site by soil <br /> vapor extraction. PHS/EHD refers GTI to the California Code of Regulations (CCR) Title <br /> 23, Division 3, Chapter 16, Article 11, section 2725(d) for a listing of the required <br /> elements of a CAP. The submitted CAP failed to include a feasibility study evaluating <br /> two different cleanup alternatives for their ability to mitigate the contamination and <br /> comparing their cost-effectiveness. <br /> The CAP states in Section 1.2, Site Hydrology, "As of yet, monitoring wells have not <br /> been installed at the site therefore site specific data is not available for groundwater <br /> gradient slope and direction". However, in Section 1.0 GTI describes the installation of <br /> monitoring wells and the analytical results from samples collected from those wells. <br /> Could GTI please explain this discrepancy to PHS/EHD? <br /> The CAP fails to state how many of the existing VEW's will be used in the remediation. <br /> Section 2.1 states that no additional VEW's are proposed and that the site is under the <br /> influence of the existing vapor extraction wells. Section 2.2 states that"unused vapor <br /> extraction"will be used as air re-charge wells. This statement is unclear. How many of <br /> the VEW's does GTI propose to use in the remediation? <br /> The CAP states in section 4.1 Effectiveness Testing, that"GTI shall confirm that vacuum <br /> pressure drawdown extends beyond targeted hydrocarbon-impacted zones and <br /> demonstrate that the extraction system will reach the goals of the remedial action". <br /> However, GTI never states or shows in the CAP what the targeted hydrocarbon zones <br /> are, nor do they state what the goals of the remedial action are. <br /> The CAP states in section 4.3.1 Soil Vapor, in a discussion of when to conduct a spike <br /> test for confirmation sampling that "The point at which this event may take place will be <br /> determined by the safe in-situ levels determined by the regulatory agencies". What does <br /> GTI mean by `safe in-situ levels' and what is their connection with confirmation sampling <br /> of the extracted soil vapors? <br /> The CAP states in section 4.3.2 Soil Samples, that"A confirmation soil boring will be <br /> drilled near each point of release to confirm that the remediation has been successful". <br /> What does GTI consider 'each point of release' at this site to be? <br />