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WASTE DISCHARGE REQUIRED—ATS ORDER NO.R5-2003-0178 -5- MORADA PRODUCE COMPANY LINDEN PACKING SHED SAN JOAQUIN COUNTY 28. Although not fully characterized yet, it is presumed that the wastewater in the pond will contain chloroform at concentrations exceeding groundwater water quality objectives. The Toxicity objective in the Basin Plan applies to all groundwaters, which states, in part, "[g]round waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human,plant, animal or aquatic life associated with designated beneficial use(s)." Chapter IV of the Basin Plan contains the Policy for Application of Water Quality Objectives, which provides that "[w]here compliance with narrative objectives is required (i.e., where the objectives are applicable to protect specified beneficial uses), the Regional Water Board will, on a case-by-case basis, adopt numerical limitations in orders which will implement the narrative objectives." The policy further provides that to evaluate compliance with narrative water quality objectives the Regional Board considers, among other things, "relevant numerical. ._ criteria and guidelines developed and/or published by other agencies and organizations (e.g., ... California Office of Environmental Health Hazard Assessment, ...)." The Office of Environmental Health Hazard Assessment (OEHHA)has published and maintains the Toxicity Criteria Database, which contains cancer potency factors for chemicals, including chloroform, that have been used as a basis for regulatory actions by the boards, departments and offices within the California Environmental Protection Agency(Cal/EPA). The cancer potency factor for oral exposure to chloroform in this database is 0.031 milligrams per kilogram body weight per day (mg/kg-day). By applying standard toxicologic assumptions used by OEHHA, USEPA and other environmental agencies in evaluating health risks via drinking water exposure (i.e., 70 kg body weight and 2 liters per day water consumption), this cancer potency factor is equivalent to a concentration in drinking water of 1.1 ug/L(ppb) at the 1-in-a-million cancer risk level. The 1-in- a-million risk level is consistent with that used by the Department of Health Services (DHS)to set de minimis risks from involuntary exposure to carcinogens in drinking water in the development of drinking water MCLS and Action Levels and by OEHHA to set negligible cancer risks in the development of Public Health Goals for drinking water. The one-in-a-million cancer risk level is also mandated by USEPA in applying human health protective criteria contained in the National Toxics Rule and the California Toxics Rule for priority toxic pollutants in California surface waters. Chloroform is projected to be present in the pond wastewater at concentrations ranging 16 µg/L to 25 µg/L, well in excess of the 1.1 ug/L human toxicity value. 29. Because the facility is not yet in operation, wastewater has not been fully characterized and chloroform could be present in the storage pond at concentrations that could degrade the underlying groundwater. However, chloroform could also volatilize from the wastewater stored in the pond. Due to the unknown potential for chloroform impacts, it is appropriate to require the Discharger to reevaluate the discharge after a year of monitoring. If chloroform, or other constituents, are present at concentrations that could degrade the underlying groundwater, then the Discharger will be required to take steps to prevent degradation. These steps could include treating the waste,using different chemicals, or lining the pond. The Discharger may also be required to install lysimeters or groundwater monitoring wells. SITE SPECIFIC CONDITIONS 30. The area surrounding the facility contains agricultural, industrial, residential, and educational land uses. The topography of the surrounding area is level.