"High" Tech Treatment of Storm Drain Wastes

For a look at the “State of the Art” in storm water waste treatment, see this article in Sunday’s Los Angeles Times:


I’m reminded of an expression used by a friend of my father, who was a journeyman plumber. He often proclaimed that “There are only two things a plumber knows for sure: Friday’s payday, and [stuff] don’t run uphill.” I often remind people taking my classes that “water flows downhill,” just like my Dad’s friend informed me while I watched him ply his trade decades ago. And the “stuff” — my Dad’s friend used a more colorful term, not suited for a family blog — in the water flows downhill along with the water.

In the stormwater business, we know that you can’t get more “downhill” than sea level. So all the stuff that finds its way into the storm drains eventually makes it to the ocean. It “don’t run uphill.” And for decades, this has constituted the state of the art and the best available technology for dealing with non-sanitary sewer urban wastes: just let it go to the ocean!

(Incidentally, don’t you find it odd that the most “stuff”-filled flow streams in the city are called “sanitary sewers.” Now, that’s an oxymoron for you!)

The project touted by the Times article is spending $10 million in federal stimulus funds for a pilot project to eradicate storm water wastes in southeast LA County. And as the fellow in today’s photos (from the same Times article) can attest, this is certainly a “shovel-ready” project!

Well ain’t technology amazing? This project involves the installation of screens — some costing $12,000 per installation — to catch the “stuff” as it enters the storm drain system. The Times article acknowledges that this project is a “simple, even low-tech concept.” In addition to being disturbed that our technological society can’t come up with a better idea than this, I have a few other concerns about this project.

First, screens that pose a barrier to debris also restrict the flow of water. Any obstruction of the path of the water in the storm drain necessarily reduces the capacity of that drain to convey storm water safely away. With these screens, our storm drains just got smaller. And since we have all witnessed flooded storm drains already, I can’t wait to see how much additional flooding occurs due to these screens. And I’m sure the attorneys are circling in the swirling storm waters, waiting to sue the government agencies responsible for flooding out their clients’ homes and businesses.

The design intent of these screens is that they will collapse to minimize flooding risk. Two problems here: a collapsed screen captures nothing, and releases everything it had already captured; and I suspect a less than 100% success rate, especially in debris-clogged catch basins.

Next, if something is removed by the screens, how do we clean the screens and where does the debris go? Most municipalities already have preventive maintenance of storm drains as a standard operation, but this will obviously require far more labor and machinery to clear these basins on an even-more-frequent basis. I foresee a lot of “great” new jobs coming — see today’s photo again. The $10 million will wind up being “chump change” when compared to the on-going maintenance costs. And I hope these folks can find a landfill in LA County that will take their debris. Otherwise, the cost of burying this trash will be enormous.

Trash in the storm drains, and “downhill” in the oceans, really is a serious problem, and I don’t mean to minimize this issue in any way. I’m just not sure that this is a serious solution.

I hope I’m wrong.

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