By Tracy Record
West Seattle Blog editor

Three weeks down, “several more months” to go.

Most late nights and early morning, somewhere in West Seattle, Seattle Public Utilities workers are flushing another section of our area’s aged water mains, to tackle the “brown water” problems that have vexed customers around the area.

To get the root cause – rust and sediment – out of the system, however, stirs it up in some spots – so, as was the case for a reader who e-mailed us early today, it gets temporarily worse in order to get better.

Meantime, we’ve checked with SPU for an update on how the project – first previewed here March 31st – is going, including one change in the plan, plus we have a firsthand look at what happens at a flushing scene:

First, for a refresher course – this is the area where SPU is working first, through June:

When they’re on scene, there’s a lot more to it than just opening a hydrant and letting the water run to the nearest drain, we found out one recent night, when SPU’s drinking-water-quality director Wylie Harper joined us at a flushing site in south Admiral.

He was joined that night by SPU communicator Ingrid Goodwin, with whom we checked on Tuesday for an update on the project.

Goodwin tells us that in the fourth week of “unidirectional flushing,” it’s “proceeding well.” They’ve done 21 of the 100 flushes they need to do in the North Admiral area alone. “We’re taking our time, doing it right and making field adjustments as we observe how the system is responding.”

Here’s what you should know about one adjustment. Goodwin says, “One of the challenges of achieving a successful unidirectional flush is achieving sufficient velocity while maintaining adequate pressure within the system. We are learning that this may require temporarily shutting off the water for some customers in the middle of the night (from about 11 pm to 4 am). Impacted customers will receive a door hanger at least 48 hours in advance of the shutdown.”

But even if you don’t have to deal with a shutoff, as mentioned earlier, you might see brown water temporarily as a result of this longterm effort to reduce its cause. Goodwin notes, “We are receiving good feedback from customers about the effectiveness of the flushing. One customer came outside before the flushing began with a glass of water that was discolored. He later returned when the flushing was complete with a glass full of clear water.”

If you notice discolored water, SPU stresses, please don’t just assume it’s the flushing – call them at 206-386-1800: “Information from customers really help us determine where the problem spots are located and how widespread the issue may be.” And you probably won’t know at the time whether the pipe’s been, or being, flushed anywhere near you (last night, for example, crews were at 46th/Stevens, 48th/Stevens, Hanford/Garlough).

The specific hydrants/lines to be flushed are chosen in a way that clears an entire section of pipeline at a time. It can be noisy, crews noticed early on, and the night we joined them in the field, they showed us what they’re doing to try to keep it down and keep it off nearby properties. The night we were out with them near SW Spokane in South Admiral, the first hydrant was right next to a fenced yard:

We were shown the “sound barrier box” the crew – headed by Nick Grover – came up with to muffle things once the flushing began:

What’s in the box besides hoses? The Hose Monster (explained here):

Doing the work overnight had already required a variance from the city planning department.

The goal at each location is to flush water equal to three times the volume of the stretch of pipe they’re clearing. The night we observed, that meant almost a mile of pipe – since the length they were working with was 1,600 feet. As the water discharges, since it’s going into the storm-drain system, it’s treated with vitamin C tablets to neutralize what it had been treated with before going into the residential system – they’re in the orange material you see the water flowing over:

Once they verify they’re at the right volume of water, they flush the water until it’s clear, measuring turbidity – cloudiness – throughout the process, and testing for other water-quality standards.

Meeting that standard means the flush of this section of line might take more than the 17 minutes or so that it should have technically taken to get three pipe volumes out, at five feet per second – more than five times the rate at which it would normally move through pipes. What they try to avoid is running fast and suddenly stopping, to the point where what they stirred up – that rust and sediment – stays in the system, and turns up in a nearby tap.

Everyone on the crew, meantime, has a role, including the person who watches to be sure the flushed water is going into the right place at the bottom of the hill. Overall, “there’s a little bit of an art form to it – just as long as it’s not moving backward,” Grover says.

Once more – even if you think it’s flush-related, if your water turns up discolored, please report it to SPU: 206-386-1800.