The U.S. Section of the International Boundary and Water Commission (USIBWC) has identified urgently needed repairs at its South Bay International Wastewater Treatment Plant (SBIWTP) and a plan on how and when these fixes will be made. In addition, the USIBWC continues to make progress on efforts to rehabilitate and expand the plant.
“Tropical Storm Hilary exacerbated the vulnerabilities of an already at-risk treatment plant, accelerating damage through excessive flows and incoming debris,” Dr. Maria-Elena Giner, USIBWC Commissioner, said. “We want everyone to know we are working hard and have a plan to bring the plant back up to normal operations. We are also making critically needed improvements to achieve water quality permit compliance.”
Commissioner Giner outlined the strategy during a presentation to the San Diego Regional Water Quality Control Board on Sept. 13, 2023.
The USIBWC has created a recovery plan that will cost approximately $8 million, which will require the agency to realign other priorities by paying for the work out of the agency’s salaries/expenses and construction budgets.
This amount is in addition to $10 million in previously-awarded contracts to address the impact from excess flows the plant has been receiving for more than a year. The money was to help the plant comply with water quality standards.
The goal is for the plant to recover the ability to fully treat 25 million gallons a day (MGD) of wastewater and meet discharge quality permit parameters. Although the timeline to achieve compliance is nine months to a year, incremental progress may be seen earlier as repairs are made. In parallel, some of the work to recover from Hilary may be completed within 30 to 90 days.
The Hollister Street Pump Station, responsible for pumping transboundary flows from Goat Canyon and Smuggler’s Gulch into the plant, recently shut down when all four pumps became inoperable. Efforts are underway to restore operations. Until that station is fixed, flows containing untreated sewage can pass through the canyons into the Tijuana River and Estuary.
The USIBWC is prioritizing replacement of the pumps at the Hollister station within the items included in the $8 million recovery program. USIBWC will provide updates via X (formerly Twitter) and email in response to residents’ concerns.
The storm caused excessive flows into the plant, exceeding its capacity by 100 percent for six hours (25 MGD vs 50+ MGD) and by 320 percent for another six hours (80 MGD) from Aug. 20 to Aug. 21.
Secondary treatment was bypassed for 10 hours on Aug. 20, and untreated sewage mixed with stormwater had to be discharged through the South Bay Ocean Outfall, 3.5 miles into the Pacific Ocean.
Plant Rehabilitation and Expansion
Commissioner Giner also informed the Regional Board of progress on the SBIWTP rehabilitation and expansion project to reduce transboundary flows by 90 percent. The effort includes rehabilitation of the essential processes and infrastructure at the SBIWTP as well as expansion of the plant treatment capacity from 25 MGD to 50 MGD, plus a peaking factor to temporarily treat even higher flows.
The USIBWC will solicit bids for the project in fall 2023. The current project exceeds the funding available by approximately $300 million, so the agency will construct the expansion in phases as funding becomes available.
She also provided an update on Minute 328, a US-Mexico agreement signed in summer 2022 that describes a package of sanitation projects in San Diego and Tijuana. On Aug. 7, high-level U.S. and Mexican government officials met in Mexico City to reiterate their commitment to implement the Minute. Mexican officials reported the new San Antonio de los Buenos Wastewater Treatment Plant will go out to bid in 2023, with various sewer line and pump station projects also in various stages of implementation.
Source: International Boundary and Water Commission