COMPLIANCE INFO 2000-2009 - Laserfiche WebLink

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' 0 0 [1 11 1 I 1 1 September 11, 2000 50441 Mr. Vidal Pedraza San Joaquin County Public Health Service Environmental Health Division (PHS/EHD) Page 4 Harding Lawson Associates UST Description PHS/EHD Permit Number Oxygen Percentage within UST Atmosphere Lower Explosive Limit within UST Atmosphere Tank East 39-0515527 21% 0.0% Tank Middle 39-0515528 21% 0.0% Tank West (1/2 tank) 39-0515529 21% 0.0% FUST description refers to the position of USTs within the excavation, as shown in Plate 3 These readings were recorded by representatives of the PHS/EHD and SFPD and both agencies concurred with HLA's proposed approach. At that time, the UST removal and sampling date was scheduled for June 29, 2000. All three USTs including the %: tank on the west were severely rusted with numerous holes observed on the ends, sides, and tops of the USTs. HLA also collected a representative sample of the native soil in the backfill stockpile, and contracted with Siena Testing Laboratories, in Eldorado Hills, California. to perform a Modified Proctor compaction curve using method ASTM D1557. REMOVAL ACTIVITIES The three USTs were located across Church Street from the main Newark Siena plant as shown on Plates 2 and 3. In accordance with the approved work plan, the USTs were split open by RAH personnel with a pneumatically powered Saws -All (approved by the SFPD without a Hot permit) on June 27, 2000. During this process, the severely rusted USTs were split in half and also broke into a few additional pieces. The sand within the USTs was then removed and was stockpiled on, and covered with plastic sheeting. On June 29, 2000, representatives of PHS/EHD and the SFPD were present to observe removal and sampling operations. The USTs were approximately 3.5 -feet in diameter and 8 feet long and the UST tops were located approximately 3 feet below ground surface (bgs). One of the USTs (Tank West) had previously been cut in half perpendicular to the long dimension (Plate 3). Exposed soils within the excavation generally consisted of brown clayey silt, and locally beneath the USTs were medium gray in color with a slight petroleum hydrocarbon odor. The excavation was variable in shape, approximately 12- to 15 -feet wide and 22- to 25 -feet long with depths ranging from 5 to 9.5 feet bgs. UST inverts were approximately 6.5 bgs, and no groundwater was encountered in the excavation. As previously discussed, the UST were discovered to be filled with sand, no piping was present, and there was no product present in the USTs. The sand was removed from the USTs on June 27, 2000 and cleaning the USTs after sand removal was performed with shovels and brooms. Because the USTs had previously been split in half and had broken into pieces, triple rinsing of the USTs with a steam cleaner was not performed and therefore no rinseate was generated by the cleaning process. A backhoe was used to remove the USTs halves from the excavation immediately prior to sampling beneath the USTs. 0