The “Green Solutions” Debate for West Seattle CSO

The “Green Solutions” Debate for West Seattle CSO

There has been and will continue to be a lot of discussion and thought given to so-called “green” solutions for the West Seattle area. The consensus so far on green solutions (capturing roof-top run off, using roadside cut-out capture areas, and decentralized flow) is that capturing roof-top run off has NO controversy attached to it. However, the other solutions are very arguably difficult, possibly un-green in the long term, and although useful, do not help when pumps go down (the actual pump, not just an electrical outage). Most likely sewage spills when “green” solutions have been put in place would be highly concentrated fecal matter (not your basic 10% fecal of a current CSO event).

In addition, as you may know, these types of pump stations are at low elevations, near shorelines and are vulnerable to tidal surges and sea level rise. In fact, King County’s own 2008 document about such vulnerabilities belies any further investments in either the current Barton or Murray pump stations based on their limited future (unless you elevate them or build dikes around them, and then, I am not sure). Barton pump station is the lowest in the King County system (allegedly 13 feet above sea level, but the measurement guidelines are questionable, so likely lower). It has already gone down due to pump flooding from tidal surge at least once. There is no back up for that, currently.

Green solutions? So far, the idea of capturing the toxins of pesticides, dog fecal matter, heavy metals, weed killers, oil, etc., from ground surfaces, in roadside carve outs makes questionable sense. As far as I can tell, the idea has not been thought out very well for areas like most of West Seattle. Here are what I would consider clear downsides to such “decentralized capture.”

First, it puts all that stuff right back into the ground. In a sense, it is like having thousands of small, leaking septic tanks. I am not sure that is what we want, when we know that the dog population has already exceeded the child population in Seattle and one of the major components of non-roof runoff is dog fecal matter.

Two, it puts all that stuff right back into the ground — given the stratification nature of most of our geology in Seattle, and certainly, West Seattle, such “captures” (“diversion” would be a better word, possibly), would then find a level at which they would not permeate well and would start moving downhill between layers right back to the Sound (I don’t know the technical term, but leaching and travel to Sound works for me — slow but sure travel into the Sound).

Three, inter-strata water and liquids loosen those strata from each other and produce ground ripe for landslides. This is particularly true of the West Seattle geology.

Four, a vast majority of non-roof run-off to Murray and Barton pump stations moves at a high rate of speed and the first road-side capture areas would be overwhelmed quickly in a downhill run, making them real pools at best, and at worst, just overflowing to surrounding landscape. Capturing much of the fast moving water would not occur because it is not necessarily by the gutters, but maybe flowing directly down the middle or other areas of the streets.

I am interested in hearing the arguments about such “green” solutions. I am not so sure I want to jump on the green bandwagon if it has not been proven to do what we want it to do — capture and *treat* street and yard run off. Capture it does. Treat? Highly arguable and questionable. Landslide risky? Likely.

Finally, it doesn’t matter in a sense, whether so-called green solutions are in place, systems will go down. The future of rising sea levels should be planned for. The Barton and Murray pump stations are time-limited at best and there should be a better holding facility completed with its own set of pumps so that it can take over in emergencies at Barton and Murray and fill in when those are unusable in the future.

I would much rather capture ground run-off and treat it, than run it back into the ground to have it leach out into the Sound anyway, or raise the potential for landslides. The technologies for treatment of all the toxins in such runoff is getting better everyday. “Green” solutions for most of the West Seattle area seem to be more about hiding run-off than treating it, and diverting run-off rather than capturing it and treating it.

Comments? Arguments?

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