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Draft Final Site-Wide ROD - 2 - • 17 June 2008 1 Lawrence Livermore Natio Laboratory Site 300 U.S. Department of Energy San Joaquin County 3. Page 2-38, Section 2.9.2. Remedial Alternatives for Building 834 (OU-2). DOE states that it will continue evaluating innovative technologies to improve remediation of VOCs in low-permeability sediments to expedite cleanup. DOE has been conducting a bioremediation pilot study which should be mentioned in the Final SWROD. DOE needs to commit to a schedule for completing the bioremediation study and presenting the results to the regulatory agencies. 4. Page 2-83, Pit 7 Complex (OU 5). In this section, DOE states "There is minimal short- term exposure risk to workers that can be controlled." This statement is with reference to the drainage diversion system that has been completed. Please explain what the minimal risk to workers is and how it will be controlled or remove the sentence. 5. Page 3-8, Section 3.2.3.1. Hydraulic Control of the Tritium Plumes. DOE states that the Qal/WBR HSU is not saturated for significant periods during the year; therefore, significant downgradient plume migration does not occur. The Building 850 plume in the Qal/WBR HSU has migrated down Doall Ravine, a distance of more than 3,000 feet. DOE needs to state the distance the plume has migrated and explain why the distance of at least 3,000 feet does not represent significant migration. 6. Pages 2-46 and 2-47, Remedial Alternatives for Building 832 Canyon. DOE proposes monitored natural attenuation (MNA) for nitrate in the Building 832 Canyon OU; therefore the heading for section 2.9.8.2 should include MNA. On page 2-47, DOE states that nitrate-bearing treated effluent is either discharged via misting towers or is injected into Tnbs2 to undergo natural denitrification. The three groundwater treatment systems all discharge treated nitrate-bearing effluent via misting towers. DOE needs to show the locations of the misting towers on the appropriate figures and add a sentence in the text stating that, although MNA for nitrate was selected for nitrate remediation, no injection of treated effluent is occurring at present. DOE should explain why the effluent is not being re-injected into the Tnbs2 HSU and if DOE plans to do so in the future. 7. Figures 2.4-2 and 2.5-7. Figure 2.5-7, Building 850 Firing Table (OU 5) contaminants in ground water above cleanup standards, shows a separate perchlorate plume above the MCL which is detected by monitoring well NC2-18 and is not shown on Figure 2.4-2 (Map of Site 300 showing operable units with ground water plume outlines and water-supply Pp Y wells). Figure 2.5-7 does not show perchlorate in groundwater detected in monitoring wells NC7-29 and W-Pit7-2141 south and north of the Building 850 plume, as is shown on Figure g 2.5-11 of the 2007 Annual Compliance Monitoring Report. On Figure 2.5-7, DOE needs to show the extent of perchlorate above cleanup standards in groundwater in the Building 850 area. In DOE's response to my draft SWROD comment number 6, DOE states that Figure 2.4-2 shows COCs above background; therefore, on Figure 2.4-2, please show the contours for all detectable perchlorate in groundwater in the Pit 7 Complex/Building 850 OU and in the text identify the source(s) of the occurrences of perchlorate that are disconnected from the sources at the Pit 7 Complex and Building 850.