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EPA COMMENTS <br /> ON THE <br /> SCOPE OF WORK (21 SEP 91) FOR THE <br /> BASELINE RISK ASSESSMENT <br /> COMPREHENSIVE REMEDIAL INVESTIGATION/FEASIBILITY STUDIES <br /> AT <br /> DEFENSE DISTRIBUTION REGION WEST(DDR1\') <br /> TRACY, CALIFORNIA <br /> GENERAL COMMENTS <br /> 1. James M. Montgomery (JMM), DDRW-Tracy's architectural engineer must keep up <br /> with applicable, relevant and appropriate requirements (ARARs) promulgated by <br /> both EPA and the State of California and guidance; ARARs and guidance are <br /> updated regularly. For EPA, proposed rules (usually promulgated later) are <br /> published in the Federal Register (FR). Pertinent examples include: <br /> • EPA health risk-based action levels (ALs) for soils, groundwater, and air were <br /> published in the FR of July 27, 1990. In the absence of promulgated <br /> standards, these ALs have the status of to-be-considereds (TBCs) under <br /> CERCLA, but will become ARARs when and if promulgated. <br /> • Some of the above-mentioned EPA ALs for groundwater have been, or are to <br /> be, publicized in Region 9 EPA Drinking Water Standards and Health Advisory <br /> Table (July 1992). Some of the maximum contaminant levels (MCLS) become <br /> the rule in January 1993 and others in January 1994. Also published with the <br /> MCLS in the same guidance document are preliminary remediation goals <br /> (PRGs) for an excess cancer risk of 10-6 for Class A and Class B carcinogens. <br /> • EPA Region 1X has tabulated PRGs for soils, groundwater, and air, and <br /> copies of that document have been furnished to DDRW-Tracy and to JMM. <br /> These PRGs should prove useful in this process. <br /> 2. JMM should refer to EPA's letter dated August 27, 1992 in which contract-required <br /> detection limits (CRDLs) are compared against current ARARs and against PRGs in <br /> groundwater. Some of the CRDLs for analytes in groundwater, such as dioxins, as <br /> listed in the current Comprehensive Remedial Investigation/ Feasibility Studies <br /> (RI/FS) Work Plan (for Phase I), are inadequate to meet MCLS or PRGs and should <br /> be modified. <br /> 3. EPA suggests that the preferred acronym for baseline risk assessment (BRA) be used <br /> throughout these documents, rather than "RA" that usually indicates removal action <br /> Or remedial action, in order to avoid possible confusion over terminology. <br /> 4. EPA suggests that JMM keep up with the most current RI/FS guidance documents <br /> available, especially those used in the BRA. The following list constitutes some <br /> I <br /> I <br />