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GEOMATRIX <br /> Ms. Wendy L. Cohen <br /> RWQCB - Central Valley Region <br /> 28 February 1996 <br /> Page 2 <br /> 2. Site maps, to scale, of area impacted . . ., etc. <br /> 3. High and low groundwater levels, etc. <br /> 4. Tabulated results of all sampling and analyses. <br /> Items 2 through 4 were provided within the most recent quarterly groundwater monitoring report <br /> ("Quarterly Monitoring Report and Annual Progress Summary," dated 26 October 1995). <br /> 5. Vertical and lateral concentrations contours, etc. <br /> The distribution of soil analytical data and groundwater analytical data were included in the 26 <br /> October 1995 report. These data are not contoured because only two wells had detectable <br /> analytes. <br /> 6. Mass balance calculations of treated vs. remaining, etc. <br /> 7. Technology used to clean the site, etc. <br /> 8. Zone of influence, etc. <br /> 9. Reasons why "background" is unattainable, etc. <br /> Items 6 through 9 are not applicable because active remediation has not been implemented at the <br /> site. <br /> 10. Rationale why conditions remaining a the site will not adversely impact water quality, health <br /> or other beneficial uses. <br /> Our rationale for requesting site closure was described in the 26 October 1995 report. In <br /> summary, we conclude that the lateral and vertical distribution of petroleum (degraded crude oil) <br /> is defined; that detectable analytes in groundwater are limited to two wells and analytes detected <br /> do not exceed MCLS; that the petroleum is not providing a significant source of dissolved <br /> constituents to groundwater and, therefore, is not a "source"; that intrinsic bioremediation of the <br /> petroleum at the site is occurring; site groundwater occurs at a depth of 7 feet; that no drinking <br /> water wells are screened in the shallow groundwater zone within 250 feet of the site; and that the <br /> petroleum at the site poses no adverse risk to human health under residential exposure scenario <br /> (this conclusion has been approved by the DTSC in a letter dated 3 November 1995 from DTSC <br /> to CPL). <br /> In accordance with these conclusions, we propose that the site fits the definition of "low-risk soil <br /> case," as defined in the 8 December 1995 guidance letter from Walt Pettit of the SWRCB, and <br /> should be closed. <br /> i <br /> I <br />