SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

tion of pathogens in drinking water)with the health are applied to protect the beneficial uses of a water threat posed by the trihalomethane by-products of this resource. For example,it is common practice for the process. In the case of ground water protection, this Regional Water Quality Control Boards to require type of cost/benefit balancing (accepting some chloro- compliance with aquatic life criteria for heavy metal form and other THMs in order to eliminate pathogens) contaminants in surface waters that are often much is not germane,and so the TTHM MCL is not suffi- lower than MCLS for the same contaminants. ciently protective of the ambient quality of domestic water supply sources. The antidegradation policy requires water quality goals to be set below beneficial use protective levels when The published one-in-a-million incremental cancer risk feasible. Multiple waste dischargers in an area and the estimates(ranging from 0.19 to 6µg/I)are a more contribution to degradation of water quality imposed accurate measure of potential impairment by chloro- by each must be considered. If one discharger is form of the beneficial use of ground water for domestic permitted, through the disposal of his/her waste,to supply. Staff of U.S. EPA, Region 9 (San Francisco), degrade the water resource to just below the level has supported the application of a one-in-a-million where beneficial uses are impaired, then no additional cancer risk estimate,instead of the TTHM Primary capacity exists for further degradation by other dis- MCL,as a water quality goal for chloroform in ground charges of waste. In addition,the knowledge of the water as consistent with the federal Clean Water Act health and environmental effects of chemicals or and the Safe Drinking Water Act. The TTHM drinking combinations of chemicals is constantly evolving. water standard is not appropriate for protection of What is considered to be safe at 10 ag/l today may be ambient water quality. found to be harmful at 1 µg/I tomorrow. In fact,virtually all Primary MCLS are derived by balancing the technologic and economic concerns that WASTE CLASSIFICATTON are directly related to the use of water for domestic supply with the health effects information developed In California,the classification of wastes is performed under the MCL Goal process. Thus,Primary MCLS are by two separate Cal/EPA state agencies with separate not necessarily reliable indicators of protection of regulatory authority. The Department of Toxic Sub- beneficial uses of ambient waters and should not stances Control (DTSC;formerly the Toxic Substances necessarily be relied upon as appropriate water quality Control Division of the Department of Health Services) goals in these situations. There are additional instances classifies wastes as hazardous or non-hazardous based where water quality criteria more stringent than MCLS on their direct threat to public health. The State Water Resources Control Board,together with the nine WASTE AND UNIT CLASSIFICATIONS Regional Water Quality Control Boards,classify non- USED IN CALIFORNIA hazardous wastes as"designated", "nonhazardous WASTE solid" or"inert",based on the threat that each waste WASTE CLASSIFICATIONSWASTEpow to the beneficial uses of ground and surface DEPT of TOXICS WATER BOARDS UNITS waters,as required by the Porter-Cologne Water Quality Control Act and regulations,water quality FIAIARDOUS CLASS I a HAZARDOUS i I control plans and policies set forth by the Wats = GIVEN YAR Boards. DESIGNATED CLASS II x ; v < As shown in Figures 2 and 3,Water Board regulations z. d NON. NONHAZARDOUS . CUSS III < a SOLID i divide wastes into four categories which,in turn, HAZARDOUS determine the classes of waste management units to U INERT UNCLASSIFIED - I which their discharge is permitted for treatment, storage or disposal. Detailed criteria are contained in Figure 2 Title 22 of the California Code of Regulations,Division Page 8 California's Water Quality Standards