RWQCB renews FPUD's treatment plant permit

The San Diego Regional Water Quality Control Board (RWQCB) renewed the Fallbrook Public Utility District’s waste discharge permit for FPUD’s wastewater treatment plant.

The RWQCB’s Aug. 8 actions also approved a tentative order establishing a time schedule for FPUD to comply with the total residual chlorine effluent limitations included in the waste discharge permit order.

The permit was extended to Sept. 27, 2017. The permit renewal was approved on a 4-2 vote with board members George Loveland and Grant Destache expressing displeasure with recycled water only being used once. Loveland also indicated that a higher chlorine discharge limit for wet-weather periods should have been part of the permit. The timetable was approved on a 6-0 vote.

“It was a pretty thorough discussion on both sides,” said FPUD general manager Brian Brady. “There was a lot of technical information exchanged. Fallbrook still believes some of the requirements are unnecessary in terms of testing. However, we’re fully committed to the new permit.”

The most significant changes from the previous permit issued in 2006 are updates in the monitoring and reporting program, quality-based effluent limitations for total residual chlorine and for tetrachlorodibenzo-p-dioxin, the change in chronic toxicity effluent limitation to a performance goal, and an update in compliance determination language.

FPUD’s Wastewater Treatment Plant Number 1 is located in the 1400 block of Alturas Road. The treatment processes include preliminary treatment by mechanical bar screening, aerated grit removal, primary sedimentation, aeration and secondary clarification (an activated sludge treatment process), and chlorination. Sludge from the secondary treatment facilities is thickened, aerobically digested, and dewatered through a centrifuge process. The dewatered sludge is hauled by a contractor to a land application site in Yuma while grit and screenings from the preliminary treatment processes are collected and subsequently deposited in a San Diego County landfill.

Treated water which is not distributed as recycled water is discharged to FPUD’s land outfall pipeline which conveys effluent to the Oceanside ocean outfall at the City of Oceanside’s La Salina Wastewater Treatment Plant. The discharge permit allows a flow rate of 2.7 million gallons per day (mgd), although FPUD’s contractual agreement with the City of Oceanside calls for a discharge of 2.4 mgd on an annual average.

FPUD’s previous permit was adopted on April 12, 2006, and had an expiration date of June 1, 2011. FPUD applied for a permit renewal on Sept. 30, 2010, and the RWQCB deemed the application to be complete on Oct. 30, 2010 (in the absence of objections, the application is automatically deemed complete 30 days after submittal; while the application was officially deemed complete on a Saturday, FPUD was notified the following Monday). The permit was extended administratively until the RWQCB made a decision on its renewal.

The RWQCB had proposed a modification of the permit in 2011, and FPUD addressed seven topics of concern about the new provisions.

“We tried to find a compromise,” said RWQCB water resource control engineer Ben Neill. “We made some of the changes that their lawyer asked.”

The new permit’s average monthly effluent limitations include 25 milligrams per liter (mg/l) and 560 pounds per day of carbonaceous biochemical oxygen demand, 30 mg/l and 680 pounds per day of total suspended solids, 25 mg/l and 560 pounds per day of oil and grease, 1.0 milliliters per liter (ml/l) of settleable solids, and a turbidity of 75 nephelometric turbidity units (NTU).

The average weekly limits are 40 mg/l and 900 pounds per day of carbonaceous biochemical oxygen demand, 45 mg/l and 1,000 pounds per day of total suspended solids, 40 mg/l and 900 pounds per day of oil and grease, 1.5 ml/l of settleable solids, and 100 NTU of turbidity. The permit also includes instantaneous maximums of 75 mg/l and 1,700 pounds per day of oil and grease, 3.0 ml/l of settleable solids, and 225 NTU of turbidity. The conditions also include that the pH level must be between 6.0 and 9.0 at all times. The tetrachlorodibenzo-p-dioxin limits are 0.000000034 milligrams per liter and 0.0000000077 pounds per day.

The total residual chlorine limitations include a six-month median of 180 micrograms per liter and 4.0 pounds per day, a daily maximum of 700 micrograms per liter and 16 pounds per day, and an instantaneous maximum of 5,300 micrograms per liter and 120 pounds per day, although FPUD has been given until March 31, 2016, to achieve full compliance. FPUD was given interim limitations including a six-month median of 5.4 milligrams per liter (or 5,400 micrograms per liter) and 122 pounds per day, a maximum daily of 11.12 mg/l and 252 pounds per day, and an instantaneous maximum of 11.12 mg/l or 252 pounds per day.

FPUD must submit a report identifying new or modified facilities and control measures to achieve compliance by Sept. 30, 2012. Final design of any required facilities and control measures must be completed by Jan. 11, 2013, and the construction contract must be awarded by April 13, 2013. Construction of the required facilities and control measures must be completed by Dec. 31, 2015. FPUD will also be required to submit semi-annual progress reports.

“The time schedule will give them interim limits,” Neill said. “It gives Fallbrook time to upgrade their facilities.”

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