Wastewater treatment in San Diego
Posted by George J Janczyn on October 15, 2009
I’ve been thinking about the waiver given to San Diego on Oct. 7 by the California Coastal Commission allowing the city to defer secondary treatment at its Point Loma Wastewater Treatment Plant.
One thing that puzzled me was Spouting Off Blog’s report that the Surfrider Foundation, Coastkeeper, and Sierra Club were all in support of the waiver because of an agreement for San Diego “to complete a comprehensive water recycling study with recommendations to be completed in the next two years.” I also thought about the blog’s assertion that San Diego “refuses to embrace water recycling as an integral solution to our growing water crisis.”
I couldn’t find language requiring that study in the commission’s report. I’m not saying the groups don’t have some side agreement, perhaps not involving the Coastal Commission, but I’d like to see some documentation. In any case the city’s 2005 Recycled Water Master Plan Update was probably headed for another update soon anyway.
In 2002 San Diego’s Long-Range Water Resources Plan called for development and use of recycled water to the tune of 15,000 acre-feet per year (AFY) by 2010 and 33,000 AFY by 2030, according to the 2005 Master Plan Update.
San Diego now has two large-scale water recycling facilities online, the North County Water Reclamation Plant (NCWRP) and the South Bay Water Reclamation Plant (SBWRP), with capacities of 30,000 AFY and 15,000 AFY, respectively, a total of 45,000 AFY. So far there is lots more capacity than they can find users for.
The Coastal Commission report states that the city
has implemented a water reclamation program that will result in a reduction in the quantity of suspended solids discharged into the marine environment during the period of the 301(h) modification. To ensure compliance with this requirement, EPA Region 9 is imposing permit conditions slightly different than those proposed by the applicant. In addition, the applicant has constructed a system capacity of 45 mgd of reclaimed water, thereby meeting this January 1, 2010 requirement.
EPA Region 9 concludes that the applicant’s proposed discharge will satisfy CWA sections 301(h) and (j)(5) and 40 CFR 125, Subpart G.
So, even though Point Loma isn’t doing secondary treatment, the actual discharge is meeting the requirements for the waiver.
Now, consider that the North City Water Reclamation Plant (NCWRP) provides secondary treatment for a large amount of wastewater that is then discharged via the Point Loma outfall. As of 2005, NCWRP treated 75% of its capacity this way, according to the Master Plan Update. In other words, a significant portion of wastewater coming out of Point Loma received secondary treatment.
A smaller amount of NCWRP wastewater is given tertiary treatment which then goes towards beneficial reuse by a number of customers.
Perhaps the question should be why NCWRP isn’t doing more tertiary treatment so that more water can be beneficially reused. The 2005 Master Plan said that tertiary water amounted to 6 million gallons per day (MGD) and that the goal was to reach 12 MGD by the end of 2010. So there’s lots of unused capacity there.
Part of the problem is finding new large users (and you need large users because it’s much more expensive to deliver to many small users). Another problem is that some known large users are not near existing distribution pipelines. Not connected to the distribution system for recycled water is the central San Diego area, including Mission Bay Park, Balboa Park, Mission Valley (including the Riverwalk Golf Course) and east to La Mesa, downtown and south to National City. Inexplicably, though, the master plan says “MWWD does not project a need for a wastewater treatment facility in the Mission Valley area until 2030.”
If there is another study or plan update, I think that issue should be revisited. What if the 18-acre parcel of land near Qualcomm Stadium the plan contemplated for a plant is not available in 2030? There might be a new larger stadium, or other development. Recently we read of SDSU’s desire to build facilities somewhere in that area. Even though the city owns that parcel, future development in the area could pose problems.
As it stands, the master plan talks about expanding the distribution system from NCWRP or SBWRP to provide service to the central area. If we’re looking at the long term, though, those facilities will eventually find enough users in their own areas. I think it would make more sense to build a third recycling facility in Mission Valley. Especially since Balboa Park and Mission Bay Park are such huge water users (1240 AFY and 860 AFY). Also with a treatment facility in Mission Valley, some water could be discharged into the adjacent San Diego River as part of a live stream discharge/wetlands creation project. Last, we should revisit the proposal to pipe highly treated water to San Vicente reservoir and either place it in the reservoir or percolate it to recharge groundwater aquifers. While I disagree with Spouting Off that San Diego refuses to embrace recycling, it’s true there has been a lot of unsavory and uninformed reaction by certain people to recycling. But I think we’re approaching the stage where those people will realize it’s time to grow up.