COMPLIANCE INFO_FILE 6 - Laserfiche WebLink

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a M M Supplemental Information The subject tank system was registered with the State Water Resources Control Board in May 1986 as 83641D and has subsequently been renamed Underground Storage Tank 836-D 1 U 1 (UST 836-D 1 U 1). Figure 1 (see Appendix B)shows the location of UST 836-D 1 U 1 tank system at Lawrence Livermore National Laboratory Site 300(LLNL). Figure 2(see Appendix B)shows the utilities and tank piping in the immediate vicinity of the tank which were located by an underground locator. Figure 3(see Appendix B)shows a plan view of UST 836-D 1 U 1 tank system. It is unknown when UST 836-DIU1 tank system was installed. However,a tank at this location is shown on a 1966 plot plan. The tank supplies diesel fuel to the Building 836 emergency generator which is northeast of the tank(see Appendix B,Figure 3). The tank system consists of a single-walled 280 gallon carbon-steel tank and associated till pipe,vent pipe,and supply and return piping. The area to be excavated is covered with asphalt. It is not known if a concrete anchor pad is present beneath the tank. If an anchor pad is present it will be removed as part of this tank closure. If minor soil contamination is found when the tank is removed.LLNL will remove up to 10 cubic yards of suspected contaminated soil. The underlying soil will then be sampled to determine if any contamination is remaining in the soil. If soil contamination appears to be more than miner.or if there is an indication of contaminated groundwater, LLNL will perform further investigation and cleanup activities in agreement with San Joaquin County, Public Health Services. Any contaminated soil removed from the excavation will be stored,sampled and disposed of properly. The emergency generator for Building 836 and UST 836-D 1 U 1 are currently in use. UST 836-D 1 U 1 will be replaced with a new 250 gallon above=round storage tank,which will be placed near the emergency generator. UST 836-D 1 U I has never been suspected of leaking. LLNL had contracted with the Gary Peters Enterprises to perform precision tank tests using the Tank Audit LEAK COMPUTER on this underground diesel fuel storage system for the past 4 years. The most recent test results (conducted by Clayton Environmental Consultants,Inc.)are included as Appendix C and show the tank and piping to be product tight. The groundwater monitoring well locations shown on Figure 4 of Appendix B are not currently analyzed for the diesel constituents. If soil contamination is found,and if there is reason to suspect that the contaminants have migrated from the area,groundwater samples from the monitoring wells could be analyzed for possible diesel fuel contamination. However, groundwater contamination is not expected due to the tank integrity and the depth to regional groundwater aquifer of approximately 280 feet(Monitor Well W-833-30). Perched around water has been intermittently identified between depths of 20 to 40 feet below ground surface in Gravel lenses near Building 833. However Boreholes D-836-01 and 833-39, located on Figure 4, did not encounter groundwater above total depths of 22.5 and 45.5 feet,respectively. A State Water Resources Control Board Underground Storage Tank Permit Application Form B will be completed and sent to San Joaquin County Department of Environmental Health once UST 836-D 1 U 1 has been removed. A-1