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Clayton <br /> E�URtI\tiIEN=+l <br /> C07\iLEI+VTS <br /> 4.4 EXCAVATION AND AERATION CONCLUSIONS <br /> In a letter to Interland Corporation, dated November 1, 1990, the SJC/EHD stated <br /> that, based on Clayton's findings, no further soil remediation was required for the <br /> .. former underground storage tanks at the site However, they requested additional <br /> groundwater monitoring and proper abandonment of monitoring well MW-3 and the <br /> Y" domestic water well. This letter is presented in Appendix B. <br /> a 5.0 ADDITIONAL INVESTIGA'T'ION <br /> Following the soil remediation, Clayton was retained by OSH to complete the <br /> „-, following tasks at the site in January 1991: <br /> (1) Install groundwater monitoring well MW-3B downgradient of the soil excavation <br /> s pit Sample and analyze soil and groundwater. <br /> s (2) Properly abandon monitoring well MW-3 <br /> (3) Properly abandon the domestic water well <br /> (4) Conduct a quarterly sampling of all morutonng wells onsite <br /> IJ <br /> Work for this phase of the investigation was documented in our report, Soil and <br />,t Groundwater Investigation for Orchard Supply Hardware, dated February 11, 1991 <br /> (Clayton Project No. 32649.00) and is summarized below. <br /> 5.1 ADDITIONAL INVESTIGATION <br /> MW-3B was installed at the southwest corner of the property, downgradient of the <br /> former excavation pit (Figure 2) on January 8, 1991. The borehole was drilled to a <br /> depth of 20 feet bgs using a 10-1/2 inch hollow stem auger from a mobile truck- <br /> mounted drr'lhng ng. The borehole was converted into a monitoring well. <br /> The installation of monitoring well MW-3B and abandonment of monitoring well MW- <br /> 3 and the domestic water well were observed by Ms. Eleanor Ratliff, SJC/EHD <br /> r 1 x W environmental health inspector. <br /> Soil samples were collected from 4 feet and 9 feet below grade. These samples were <br /> analyzed by the following methods: <br /> • EPA Method 5030/8015-8020, for gasoline and BTEX <br /> i <br /> e EPA Method 418.1 TRPH <br />,x E Analysis detected a TRPH concentration of 770 ppm at 4 feet bgs and 20 ppm at 9 <br /> feet bgs. Gasoline was not detected in the soil samples. Clayton surmised that the <br /> a i hydrocarl:ons detected were probably oil and grease. <br /> These analytical results were discussed with Ms. HLnson on the telephone on March <br /> 28, 1991. The conversation was confirmed in a letter from the SJC/EHD, dated April <br /> 3, 1991. This letter is presented in Appendix B At Ms. Hms..n's request,we <br /> 8 <br /> } a:wao1� <br />