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w <br /> Mr. Ron Valladao <br /> January 13, 2000 <br /> Page 2 <br /> encountered at a depth of 9 to 10 ft. Soil samples from the trenches were analyzed for total <br /> petroleum hydrocarbons as diesel (TPHd)total petroleum hydrocarbons as gasoline (TPHg) <br /> using EPA Method 8015 and for the volatile fuel constituents benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX) using EPA Method 8020 (602 for water). Analyses were <br /> performed by Excelchem Laboratories of Roseville, California. <br /> 1,190 to 2,140 ppm TPHd was found in the soil onsite, 508 ppm TPHd was found in <br /> the groundwater. Only low to non-detectable concentrations of BTEX compounds were <br /> reported. The extent of contamination appears to be limited to a zone approximately 140 ft <br /> in length(north to south) and approximately 60 ft to the east of the property line. We infer <br /> that similar contamination exists on the adjoining property to the west. <br /> If contamination is confined to a zone of approximately 3 ft in thickness over that <br /> area, approximately 935 cu yd of contaminated soil is present. If the average degree of <br /> contamination is 1,000 ppm, and a cu yd of soil weighs 3,000 pounds, approximately 2,800 <br /> pounds of diesel fuel is inferred to be present onsite, with a similar or greater volume on the <br /> property to the west. <br /> Remedial Options <br /> The source of contamination has been removed from the adjoining Site. While little <br /> or no risk to human health is apparent due to the lack of BTEX compounds in high <br /> concentrations, further work will be required to assess the full extent of the contamination, <br /> particularly on the adjoining property, and to assess the need for mitigation of contamination. <br /> This responsibility rests with the owner of the adjoining property,.which is out of compliance <br /> with County directives to proceed with the assessment investigation. <br /> Three potential options are viable for this site, They include no further action, <br /> excavation and disposal or onsite treatment of the contaminated soil, and in situ treatment of <br /> the contaminated zone. Selection of the appropriate remedial action is dependent on <br /> regulatory acceptance and requirements, and must involve coordination between the two <br /> property owners. <br /> No Further Action <br /> No further action may be an acceptable response if it can be clearly demonstrated that <br /> the site presents no significant risk to the health and safety of the site occupants or the public <br /> 9015-025 <br />