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o." .ate aun ci:ua rnA cua a45 u621 KLEINFELDER INC PHS/EHD IA004 4 T:le results of the field and laboratory work were detailed in Kleinfelder's report titled "Report, P:e-Abandonment Underground Storage Tank Soil Assessment, (12,000 Gallon SC-250 and 1:,000 Gallon SS-1H USTs),Granite Construction Company, 10500 South Harlan Road, French Camp, California 95231" dated February 5, 1999. That report had the following conclusions w A recommendations: Unidentified extractable hydrocarbons (UEH) were detected in one soil sample and both water samples at concentrations only slightly above laboratory reporting levels. UEH was detected at 2.03 mg/kg in a soil sample collected in boring 134 at an approximate auger depth of 13% feet. The groundwater samples collected from borings B1 and B3 had reported UEH concentrations of 0.203 mg/L and 0.407 mg/L,respectively. All of the hydrocarbons detected were relatively dense (generally Cle to C34hydrocarbon range). The trace UEH concentrations found in the two "grab" groundwater samples likely resulted in cross contamination from the soils in the borehole above it. Also no analytes were detected in soil or groundwater from the custom fuel fingerprint analyses (SC-250 and SS-1H), which lends support to this conclusion. Based on the results of this assessment Kleinfelder has the following recommendations: 1) Kleinfelder does not recommend further soil/groundwater assessment or mitigation related to the two existing USTs. 2) Kleinfelder recommends UST abandonment in-place according to PHS/EHD guidelines. 3) Kleinfelder recommends the drilling-derived wastes be used as fill on site, following PHS/EHD approval to do so. 4) A copy of this report should be submitted to San Joaquin County Public Health Services Department,Environmental Health Division(PHS/EHD)and the State of California, Central Valley Regional Water Quality Control Board(CVRWQCB)for their review and comment. -ROPOSED ABANDONMENT METHODOLOGY T he SS-1H and SC-250 USTs would be abandoned in place using the following methodology: 11 A permit to abandon each of the USTs in place would be filed with PHS/EHD. Please note that a PHS/EHD inspector may want to be present during abandonment. 21 The vent pipe for the SC-250 UST would be disconnected near the surface. The SS-1H tank does not appear to be vented. 31 Each 12,000 gallon tank would be pumped with a 2-sack sand/cement slurry (a.k.a. 2-sack mortar mix)until the mortar fills the tank and begins to flow from the disconnected vent pipe (SC-250 tank only) or until full and flowing from the fill neck. Preliminary calculations yield that each tank would require approximately 591/2 cubic yards of grout. 41 All unnecessary piping for the USTs would be removed,as practical. 51 Each UST would then be topped off with mortar to the top of the fill neck. 2)-1108.42.EO1 1201191,853 Page 3 of 4 Copyright 1999,Kleinfelder,Inc. September 27,1999 KLEINI=ELDER 2825 East Myrtle Street,Stockton,CA 95205-4794 (209)948-1345 (209)948-0621 fax