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RWQCB adopts waste discharge requirements for Orange Grove plant

The Regional Water Quality Control Board adopted waste discharge requirements for the proposed Orange Grove Energy power plant in Pala.

The 6-0 RWQCB board vote from December 16 covers requirements for the use of recycled water for the cooling tower, toilet flushing, landscaping irrigation and the discharge of domestic wastewater. The RWQCB order includes prohibitions, discharge specifications, facility design, operations specifications, recycled water use requirements, reporting and compliance provisions and notifications.

On April 8 the California Energy Commission approved an Application for Certification to construct a 96-megawatt power plant in Pala. Orange Grove Energy, LP, will operate a simple-cycle power plant on a 220-acre site located off Pala Del Norte Road. The property is owned by San Diego Gas & Electric, which has a substation on an adjacent parcel to the south. Under the agreement between Orange Grove Energy and SDG&E, Orange Grove will be responsible for constructing the plant and an underground transmission line to the substation boundary approximately 2/10 of a mile from the plant.

Orange Grove will operate the plant and will have a tolling agreement with SDG&E for generating electric power. The facility is intended for peak periods and was proposed as a response to an SDG&E request for new peak period resources.

The facility will include two 50-megawatt combustion turbine generators, a gas metering station, water and natural gas pipelines. It will be fueled by natural gas delivered to the site by a two-mile extension of an existing SDG&E gas line. Air emissions from the plant will be controlled through technology including a water injection system, a carbon monoxide catalyst and a selective catalytic reduction system.

The turbine cooling will utilize dry cooling technology, but General Electric’s power boost technology requires water for power augmentation of the generators. The annual water usage is estimated at 117 acre-feet. Orange Grove will purchase recycled water from the Fallbrook Public Utility District, and will transport the recycled water to the power plant site. The recycled water will be stored in a 414,000-gallon storage tank and will be pumped for landscape irrigation, toilet flushing and cooling tower supply water. Fresh water will also be trucked to the power plant for use in the fire suppression system and demineralizer system.

The only water discharged from the power plant on-site will be from the irrigation system and the conventional septic tank system. The other water will be re-used internally, injected into the combustion turbines or collected in oily drain tanks for off-site disposal.

All wastewater treatment, storage, disposal and purveyance facilities for the power plant are located outside the 100-year flood plain, and drainage and water management systems will be designed to control run-on and run-off from a 100-year storm event.

An irrigation management plan must be developed and submitted within 180 days of the RWQCB approval, and water discharged for landscape irrigation shall not contain pollutants exceeding an annual average of 900 milligrams per liter (mg/l) for total dissolved solids, 500 mg/l for sulfate, 300 mg/l for chloride, 1.0 mg/l for fluoride, 0.75 mg/l for boron, 0.3 mg/l for iron or 0.05 mg/l for manganese. Extracted minerals from the demineralizer system shall not be disposed of on-site.

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