COMPLIANCE INFO_FILE 7 - Laserfiche WebLink

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Supplemental Information The subject tank system was registered with the State Water Resources Control Board in June, 1984 as underground storage tank (UST) 879-11G, and has subsequently been renamed UST 879-G1U1. Figure 1 (Appendix B) shows the location of UST 879-G1U1 at Lawrence Livermore National Laboratory (LLNL) Site 300. Figure 2 (Appendix B) shows the underground utilities and UST piping. Figure 3 (Appendix B) shows a plan view of UST 879-G1U1. UST 879-GlU1 was installed in 1968. It stores unleaded gasoline for the Motor Pool,see Figure 3 (Appendix B). However,in the past, it has contained leaded gasoline. The tank system consists of a single-walled 10,000-gallon carbon-steel tank, a fill pipe,vent pipe, and product piping. The 879-GlU1 tank system is being closed because it lacks secondary containment. UST 879-G1U1 and UST 879-G2U1 shall be replaced with a new double-walled 15,000-gallon UST identified as UST 879-G3U1. The area to be excavated is paved with asphalt, with a concrete slab near the fuel pump island. It is not known whether a concrete anchor pad is present beneath UST 879-G1U1. If a concrete anchor pad is present, it shall be removed as part of this closure plan. If minor soil contamination is found when the tank is removed, LLNL will remove up to 50 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 minor, 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. UST 879-GlU1 has not leaked according to previous tank testing reports. LLNL had contracted witl the Gary Peters Enterprises to perform precision tank tests using the Tank Audit LEAK COMPUTER on this underground storage tank system for the past 4 years. The most recent test results, from Clayton Environmental Consultants using the Horner EZY-CHEK method, are included as Appendix C, and show the tank and piping to be product tight. Water from the groundwater monitoring well locations shown on Figure 4 (Appendix B) are not currently analyzed for gasoline. No aromatic hydrocarbons were found in the initial water samples from groundwater monitoring wells W- 879-01 and W-889-01. No petroleum hydrocarbons have been found in water samples from W-879-01. Concentrations of aromatic hydrocarbons below 0.005 parts per million were found in soil samples from the installation of groundwater monitoring wells W-876-01 and W-889-01. Concentrations of chlorinated hydrocarbons (below 100 parts per billion) have been found in soil and groundwater near these groundwater monitoring wells. The source of this contamination may have been from steam cleaning operations near the northeast A-1