By Tracy Record
West Seattle Blog editor
That big tank on SW Barton, about halfway between Westwood Village and the Fauntleroy Ferry Dock – officially known as the Barton Standpipe – is empty and decommissioned.
We didn’t know that until our recent visit to Seattle Public Utilities‘ Operations Control Center in SODO:
At the heart of that visit was a preview of the big flushing operation that SPU is about to start in West Seattle in hopes of lessening the recurring brown-water problems we’ve been covering since last fall. (Even today, we’ve received scattered reports of discoloration – no word on the cause this time.) We published our first flush preview on March 31st, and then followed up on April 8th with the first look at what was being mailed out to local homes.
Now, months of targeted flushing is about to begin in the area shown on this map:
SPU was planning to start with test flushes late tonight at California/Spokane and 49th/Spokane (11:34 pm update: they’re under way, as shown in our quick added video clip).
They’ll be working out the process for a night or two. So we’re taking the opportunity to report the rest of the story behind how SPU gets water to you.
The briefing started with numbers – Seattle Public Utilities provides water to 1.3 million people. 600,000 of them are their customers, with 184,000 service connections; 700,000 of them are wholesale customers with 124,000 connections. The water comes from four “raw-water reservoirs,” two treatment plants, 30 portable storage facilities, 29 pump stations, 27 major pressure zones, and 1,800 miles of pipeline. More than two-thirds of the supply comes from the Cedar River Watershed, most of the rest from the Tolt – both managed by SPU “from snowflake to tap,” the utility says – and then there’s the “well field” south of Seattle that is “really just supplemental,” it’s explained.
Managing the Cedar River is complicated, to say the least, and probably could be an entirely separate story. Let’s just say it has a lot of stakeholders – including salmon. But they don’t go through the 8-foot pipe that diverts Cedar water to Lake Youngs for the drinking-water supply. It’s a human-made lake, created after a pipeline washout more than a century ago left Seattle without water for two weeks.
While the aforementioned wells are not often summoned into use, they were drawn on for four months last year because of the then-drought, and adding them into the system played a role in the West Seattle brown-water problems, SPU told us back then.
When they’re in use, the aquifer water is treated on site – two wells in Riverton with 7,000,000 gallons a day capacity, one in Boulevard Park with 3,000,000 gallons a day – and pumped into the “West Seattle Pipeline,” which in turn feeds up to the West Seattle Reservoir next to Westcrest Park in Highland Park.
Once the water gets here, it’s on to the distribution system. As mentioned above – the Barton Standpipe has been decommissioned. But the Charlestown Standpipe contains water. Storage around the area helps “equalize supply and demand,” also helps with settlement of “suspended particles,” and in some storage facilities there’s “booster chlorination” if needed. Eighty percent of the system is delivered without pumping, but in some areas it’s necessary, and that’s why those 29 pump stations are in operation (different from the sewer-system pump stations you tend to hear a lot about) – most are used to fill storage facilities.
Distribution includes delivery, and that’s where the water mains come in. They’re among the oldest assets in the system, and collectively, the most valuable. Some are made of cast-iron, which is the source of the rust that constitutes much of the discoloration with which we’ve had problems.
Some are steel, some concrete, some from plastics. Some have coatings/linings but most of the system is unlined pipe – and when it’s unlined cast iron, that’s where the rust buildup is. Internal corrosion affects carrying capacity, efficiency, and water quality.
An unexpected fact emerges here: Water conservation has really taken hold. Though our area’s population has grown, the amount of water sold by SPU has shrunk – the summer peak is now about 220 million gallons a day; not that long ago, it was 350 million gallons a day.
Now to the pressure zones, which play into the flushing that will be done. Here’s the West Seattle map:
The zones relate to topography, which SPU managers explained presents challenges for keeping the water flowing and keeping rust/sediment from building up; some parts of our area are supplied by gravity, some by pumping. On the map below, the green zone (270) is served via gravity; buff (498), pink (550), purple (585) are the zones that need pumping.
Most of West Seattle is in 498, so, SPU managers told us, “if we clean that up [via flushing], we can move into 550.”
After that lesson, we moved into the control room for the system:
That’s operations manager David Muto in the photo above. He explained that the room is staffed 24/7, as a “complex network of pipes, storage, pump stations, valves” and more is monitored continuously. This is a big change, however, from the days when the system was dotted by “little pump stations staffed 24 hours a day, all out in the field,” and there was no way to get an overview of how the system was doing.
From the center, the processes that are monitored include even river-flow gauges and dam-failure-warning systems for way out at the edge of what brings in your water. An acronym appears here – SCADA, Supervisory Control And Data Acquisition. The original version was launched in 1958; then, when the control center was built in 1972, its second generation was launched, and that lasted until 2006. Now, they’re using Windows-based workstations, with redundant LINUX servers, a dedicated communications network, and more. Taking a quick look at the West Seattle section of the system, we see it broken down to facilities such as the north tank at Myrtle Reservoir and the south tank in Myrtle Reservoir.
We ask Muto about failsafes. “Everything can be done manually in the field,” he explains.
And that’s where some things – like the flushing operation that’s about to begin – have to be done. If you haven’t yet read the information sent out by SPU, here are two pages of questions and answers. They are trying to ensure the flushing has a minimal effect, but it could lead to the problem it’s meant to lessen, and the Q&A document reminds you that brown water which doesn’t go away quickly should be reported to 206-386-1800. We’ll continue to follow what SPU does, and what the results are, in the days, weeks, months ahead.