SITE INFORMATION AND CORRESPONDENCE

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Health Risks Continued from page and FHCs. Preliminary risk estimates for volatilization of The health risks from potential exposures to the VOCs are contaminants from the surface soils were also extremely presented in Table 2. A detailed risk assessment was not low,and were therefore not considered in the detailed risk done for FHCs because their potential to migrate offsite in assessment. The results of a screening-level risk analysis concentrations above drinking water standards is very that LLNL prepared for tritium is on page 3. low. Similarly,risk assessments were not done for chromi- No One Currently Using Contaminated Water um and lead because they occur in relatively small areas along with VOCs and FHCs,respectively. These metals No one is currently using water that has been affected will be removed and treated if necessary with the VOCs by the Livermore site contaminants: ■ All affected private and agricultural wells have been Scenario Arrival Time of Additional sealed off. Maximum VOC Cancer Risk - Concentrations 3 ■ LLNL employees use water from the Hetch-Hetchy Best Estimate f 270 years 7 in 10,000,000 4 Reservoir and sometimes from the Zone 7 Water District. Health Conservative f 110 years 1 in],1100 Health Conservative r 1 years 2 in 1,000 ■ No LLNL contaminants have reached the Livermore municipal water supply wells,or are likely to for over I Based on VOCs reaching municipal wells in downtown Livermore. 1 OOears. 2 Based on VOCs reaching a hypothetical monitor well drilled immediately 100y ears. of LLNL. It is unlikely that the contaminated ground water 3 This is the estimated length of time it will take for the highest concentration of chemicals to reach the specified well. The best estimate assumes a migration west of LLNL will need to be used as a drinking water rate based on curent data,and some degradation and retardation(slowing) source in the future. This is because City water is avail- of the chemical. The health conservative estimate assumes that the ground water will move twice as fast as in the best estimate,and that the chemicals able at a relatively low price and the ground water is will not degrade or be retarded in their migration. naturally quite"hard" (contains cpineral salts). There is 4This means that each individual that consumes 2liters of this water each day for 70 year would increase his or her risk of developing cancer by 7 in also little residential demand for the shallow ground 10 million. This risk is in excess of the normal 1 in 4 cancer risk faced by all water near LLNL,nor should there be any in the future Americans. because of readily available City water. v Table 2. Summary of the maximum potential cancer risks for exposure to VOCs in well water if no cleanup occurs. Evaluation of Cleanup Alternatives The Feasibility Study(FS)evaluat- The last three technologies The FS and PRAP evaluated the ed many alternative cleanup strate- were dropped from detailed eval- most promising remedial technolo- gies for the Livermore site. These uation because: bioremediation is gies and alternatives according to alternatives are divided into two naturally occurring at the FHC's nine EPA evaluation criteria used general groups,according to release area,but bioremediation for all Superfund sites(see page 9). whether the chemical contaminants of VOCs is still too experimental Figure 6 on page 8 is a chart that are in ground water or in unsaturat- for the specific conditions at evaluates these alternatives against ed soils. The alternatives would use LLNL;chemical precipitation the nine EPA criteria. The alterna- different treatment technologies, requires further treatment prior to lives are summarized below. some of which are described on disposal;and ultrafiltration is rel- Ground Water Remedial Alternatives pages 6-7 of this fact sheet. atively inefficient and is prone to clogging. The PRAP evaluates three reme- The ground water remedial dial alternatives for ground water. alternatives all use a "pump and For unsaturated soil,the four Two of the three alternatives treat" strategy. Seven treatment primary remediation approaches involve immediately pumping the technologies were initially consid- evaluated were: excavation and water out of the ground and treat- ered in the FS for the contaminants disposal or onsite treatment;cap- ing it in above-ground treatment of concern. They are: ping;vacuum-induced venting; facilities located onsite. The third 1. granular activated carbon(GAC) and allowing the contaminants to alternative would treat contaminat- 2. air stripping(with GAC filter- naturally migrate,with treatment_ ed ground water from a municipal ing of the air discharge) only if concentrations above supply well in use by the City of drinking water standards result. Livermore,onlyif contaminants 3. ultraviolet light/hydrogen per- Vacuum-induced ventingrequires oxidation(with air stripping) q from LLNL ever reach it. 4. ion exchange treatment of the extracted vapors. g Three treatment technologies eval- Because the contaminants in the 6. chemical precipitation. bioremediation uated were: thermal oxidation, ground water vary in type,loca- tion,depth,and concentration,the 7. ultrafiltration catalytic oxidation,and GAC. P continued on page 5