I’m off to AÃ±o Nuevo today, to tell people all about the elephant seals (and to hear about how the park will be affected by the state budget.) So today’s post is a newsy one.
The California Coastal Commission on Thursday voted to deny the city of San Diego’s request for a third waiver from the federal Clean Water Act for its Point Loma wastewater treatment plant. According to the Union Tribune, this came as a “shock” and “a dramatic and startling defeat.” Mayor Jerry Sanders says, “I think (it’s) a political conclusion, and I think it was wrong.â€
The Point Loma plant treats 170 million gallons per day (MGD) of wastewater and discharges it into the Pacific Ocean. Our own WPCP treats currently 110 MGD, of which 10 MGD is recycled and flows back into the purple pipe system. But when I say “treat,” I mean something very different for the two plants. Our WPCP goes to tertiary treatment for the discharged effluent, and then beyond for the recycled water. The Point Loma plant only employs primary treatment on these millions of gallons of sewage before discharging them, and is fighting tooth and nail not to have to go further.
What are these two methods? I found a cool graphic at Wikipedia that I am including rather gratuitously.
Pretreatment takes out the big stuff, stuff that can be filtered out with rather coarse screens. Then primary treatment consists of holding the sewage in large tanks, called “sedimentation tanks,” so that heavy particles can settle out, while lighter-than-water fats and grease float to the top and get skimmed off.
And that’s primary treatment. Secondary treatment goes on to use aerobic digestion to break down organic compounds, which form clumps which are then filtered from the water. And tertiary treatment provides a further filtration step. I’m sure that San Diego’s effluent is also disinfected chemically before being discharged, as is ours.
One of the conditions of the two previous waivers that the Point Loma plant received (in 1995 and 2002) was that it monitor the discharge for bacterial contamination levels, and this denial of a third waiver was not a result of any of those tests. San Diego’s effluent has not suddenly got much dirtier. But it is the only city in California which has not upgraded to at least secondary treatment for discharge into the ocean, and, evidently, the Coastal Commissioners decided that it was time that they comply with the law.
One of the oddest quotes in the Union Trib article was from Marco Gonzalez, an attorney for San Diego Coastkeeper and the Surfrider Foundation. He said, â€œIn 10 to 15 years, we will no longer have the luxury of treating wastewater .â€‰.â€‰. and discharging it into the ocean.” The reporter, Mike Lee, writes that environmentalists contend that, “spending as much as $1.5 billion for the Point Loma retrofit would undermine efforts to maximize water recycling.” Both of these statements seem bizarre to me. While I am a passionate advocate for wastewater recycling, I certainly don’t believe that we could get to 100% in 10 or 15 years. And secondary and tertiary treatment are necessary prerequisites for recycling, not expensive distractions from it.