RWQCB amends discharge permit for Camp Pendleton

The San Diego Regional Water Quality Control Board (RWQCB) amended Camp Pendleton’s discharge permit to allow for brine discharge from the advanced water treatment plant at Haybarn Canyon to the Oceanside Ocean Outfall.

The RWQCB’s 6-0 vote June 13 also adds technology-based effluent limitations and monitoring requirements while maintaining the base’s discharge limit of 3.6 million gallons per day (mgd). The permit amendment also acknowledges the current expansion of the Southern Region Tertiary Treatment Plant which will increase the average daily design capacity from 5 mgd to 7.5 mgd with daily peaks at 10 mgd as well as the new advanced water treatment plant which will supplement the existing iron and manganese Plant 24 facility which treats groundwater extracted from potable water wells within the Ysidora hydrologic area. The permit amendments also add two new monitoring locations to recognize the new facilities.

The Haybarn Canyon advanced water treatment plant processes will include carbon adsorption, cartridge filters, reverse osmosis, neutralization, and disinfection. The plant will treat up to 8.64 mgd of groundwater which will result in 1.73 mgd of waste brine. The brine will temporarily be discharged, along with the effluent from the Southern Region Tertiary Treatment Plant, into the Pacific Ocean through the Oceanside Outfall until a permanent subsurface brine disposal diffuser outfall at the beach northwest of Del Mar Harbor is constructed. (The brine would still be discharged though the Oceanside Outfall on an as-needed basis once the new outfall is constructed and the discharge from the diffuser will be regulated with individual waste discharge requirements.)

The effluent limitations for the Southern Region Tertiary Treatment Plant already had average monthly and weekly limits for biochemical oxygen demand, total suspended solids, and oil and grease in milligrams per liter (m/l); limits in pounds per day were also added for those (oil and grease also has an instantaneous maximum, and pounds per day were added to the m/l limits). The advanced water treatment plant was given a total suspended solids average monthly limit of 60 mg/l or 866 pounds per day with no average weekly or instantaneous maximum standards for total suspended solids.

Oil and grease at the treatment plant will be limited to a monthly average of 25 mg/l and 361 lb/day, a weekly average of 40 mg/l and 557 lb/day, and an instantaneous maximum of 75 mg/l and 1,082 lb/day. Settle-able solids at the plant have an average monthly limit of 1.0 milliliters per liter (ml/l), an average weekly maximum of 1.5 ml/l, and an instantaneous maximum of 3.0 ml/l. Turbidity at the new treatment plant has an average monthly maximum of 75 nephelometric turbidity units (NTU), an average weekly limit of 100 NTU, and an instantaneous maximum of 225 NTU. The pH level at the treatment plant must be between 6.0 and 9.0 at all times.

The permit also added effluent limitations at the discharge point for endrin, hexachlorocyclohexane, aldrin, beryllium, dieldrin, heptachlor, heptachlor epoxide, hexachlorobenzene, polychlorinated biphenyls, tetrachlorodibenzodioxin, and toxophene.

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