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d � • MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 361-5600 Sacramento, CA 95827-3098 ATSS Phone: 8-495-5600 TO: Wendy L. Cohen FROM: Michael Higgins Senior Engineer Project Engineer l f" t.Yil DATE: 21 September 1990 SIGNATURE: SUBJECT: DRY WELLS REMEDIAL INVESTIGATION, UNIVERSITY OF CALIFORNIA, LAWRENCE LIVERMORE NATIONAL LABORATORY SITE 300, SAN JOAQUIN COUNTY I have reviewed the November 1989 Remedial Investigation of Dry Wells (RI) and the 29 January 1990 Addendum to Initia 1 Remedia 1 Investigation of Site 300 Dry We11s (Addendum) . Lawrence Livermore National Laboratory (LLNL) has not adequately demonstrated that the abandoned dry wells pose no threat to the beneficial uses of the ground water. My comments follow: Environmental Fate Analyses Rather than directly assess the pollutants' potential to impair beneficial uses of the ground water beneath the dry wells, LLNL relied on the environmental fate analysis, in the form of the designated level methodology (DLM) , conducted for the inactive high explosives (HE) rinsewater lagoons closures. LLNL asserts the results of the HE lagoons analysis are also appropriate for all the dry wells. We cannot know the truth of this because LLNL conducted no pollutant fate analyses at the dry wells. However, the hydrogeology beneath the HE lagoons and their closure sufficiently differ from aspects of the locations of the dry wells to suggest separate environmental fate studies. These aspects include, at least, the following: 1. The pollutants and the depths to the nearest groundwater differ between the areas, and 2. The HE lagoons are covered with clay covers equipped with runoff diversion channels, while LLNL proposes no action at any of the dry wells. LLNL should conduct environmental fate studies which quantitatively consider the major factors which either retard or accelerate each pollutant' s migration from each dry we l l and the potential for these constituents to impair the ground water's beneficial uses. The analyses should quantitatively consider the resistance presented to the migration of the individual constituents by specific physical attenuation factors including, but not limit to the following: soil adsorption of the constituents, possible chemical reactions in the soil , and steric hindrance of large organic molecules. The analyses should evaluate how the attenuation factors reduce the constituent concentrations in any water that may percolate into the vadose zone and migrate to the shallow aquifer. The factors should be employed conservatively because of the wide variability in soil properties possible throughout the soil column. The staff report on the DLM prepared by Jon Marshack, in addition to other sources, lists more factors which can be considered in the analyses.