By Tracy Record
West Seattle Blog editor
West Seattle Blog has learned that Seattle Public Utilities has ordered waterproofing work dug up and redone at two newly covered city reservoirs — Myrtle Reservoir here in West Seattle (photo) and Beacon Hill Reservoir — because of hundreds of leaks discovered in the “membranes” applied to both projects.
To get to the membranes, the grass, dirt and “drain rock” over the reservoirs must all be removed, which is happening right now. SPU says it has not finished calculating the costs of the additional work but will front the money to the contractor until it is decided – potentially in court – who is to blame for the leaks, which SPU emphasizes do not pose any health risk.
In the case of Myrtle Reservoir, the transfer of part of the site to the Seattle Parks Department, for construction of a park on the newly created open space has been delayed a year already — we reported delays here and here — in June of last year, in fact, the site was seeded, the same month we were told “final acceptance testing” was planned.
Now, though, SPU says that because the waterproofing is being redone, the transfer to Parks may not happen before the end of November.
The waterproofing problems recently came to our attention because of questions from neighbors who live near Myrtle Reservoir. Several e-mailed WSB in the past week to ask why the Myrtle site was being “dug up again.” Today, SPU spokesperson Andy Ryan confirmed the problem to WSB and provided more information on what happened, how it was discovered, what’s being done and what happens next. (We also have spoken with another SPU manager and with the state Health Department.)
First, some background: The reservoir-covering program has been under way citywide, mostly (as explained in that link) for safety reasons that came to light after 9/11. These are reservoirs that previously were open-air.
Elsewhere in West Seattle, the covering work is also happening right now at the West Seattle Reservoir in Highland Park’s Westcrest Park area, but SPU says Myrtle and Beacon are the only two reservoirs where these waterproofing leaks have been found. All three projects – Westcrest, Myrtle and Beacon – have the same contractor, Mid-Mountain, but Westcrest hasn’t gotten to the waterproofing stage, since the lid (cover) is still being built, as we were shown during a site tour two months ago:
Beacon was shown off to the media in June of last year, in a tour (WSB coverage here) during which we shot video of the fully covered area before water was brought in:
Beacon is a 50-million-gallon reservoir, 10 times the 5-million-gallon size of Myrtle (the one at Westcrest is inbetween them, at 30 million gallons). Ryan says the extent of the leaks in the waterproofing membranes at both reservoirs was verified by electronic testing, after crews inspecting the reservoirs’ interiors noticed what he described as “drips.” He says the discovery happened several months ago and added, “Before we sign off on the completion of any project, Seattle Public Utilities always performs quality control inspection. Like any construction job—whether it’s a major public project or a home remodel — you have to look closely at the contractor’s work. It’s not unusual to find things that need to be fixed or improved.”
The membrane is made with a product called Procor, manufactured by Grace Construction (whose waterproofing products are detailed here). According to Ryan, Procor was chosen by a “design consultant” who is working on the reservoir projects, which he identified as MWH: “The designer specified what material we would use.” (A 2008 MWH presentation about efficiency aspects of the projects is online here, but doesn’t mention the waterproofing.)
In addition to Myrtle and Beacon, according to Ryan, Procor was also used to waterproof the Lincoln Reservoir on Capitol Hill, but he says testing indicates NO problems there.
SPU senior water planner Bill Wells explains that once the “drips” were detected, the electronic testing involved uncovering several concrete panels “down to the waterproofing” and trying to “pass an electric current through the reservoir concrete and up through the membrane.” When this was done on six 20 x 20 concrete panels at Beacon, they found “almost 100 breaches,” according to Wells; when it was done on “several” panels at Myrtle, what they found was “even more extensive” – more than 400 breaches.
“Most were small pinpoint holes,” Wells added, generally not visible – none bigger than 1/8 of an inch.
Ryan says the utility wants to reassure residents that there are no safety concerns resulting from those “pinpoint” leaks that have been discovered. Myrtle, for example, was put into service as a covered reservoir last year, and he says the water is “absolutely” safe. Ryan adds that “these projects are protecting water quality, replacing decades-old open reservoirs with state-of-the-art covered structures. This current issue is about construction quality — not water quality. We know the water from the reservoirs is safer because SPU has a comprehensive water quality monitoring program and regularly collects samples throughout the distribution system and from all its reservoirs. We test these samples for a range of microbiological and chemical constituents. Our testing methods are approved through a State laboratory accreditation process. We are regulated by the State Department of Health’s Office of Drinking Water, which, with SPU, ensures the water quality within our distribution system and from reservoirs (including the Beacon and Myrtle reservoirs) meets or exceeds federal standards.”
We checked late today with Bob James from the state Health Department, and he confirmed that there had been no problems reported with the water from these reservoirs because of the waterproofing problems. He said, “There may be a little bit of leakage, but there’s very little public-health significance attached to it. Clearly there was a lot more (safety/surveillance/testing) work to do when these reservoirs were open to the atmosphere.” He echoed what Ryan had told us earlier – saying it’s vital to “stop and do it right” now, because these facilities are expected to be in service for a least a century.
So what happens next?
First – finding out how much extra SPU will have to front in the short run to get this work redone, and who pays for it in the long run. Ryan says a “change order” is being finalized right now and that by next week, that should yield specific cost numbers.
Next – who ultimately pays? Ryan says they are “working with the construction company and design consultant to determine responsibility” — the exact cause of the leaks — and have not “signed off on this project. … But the bottom line is, we believe the problems will be corrected without additional costs to our ratepayers.” He says there are at least three possible causes of the leaks – they could include the way the waterproofing material was applied, the way the concrete surface of the reservoirs was prepped before the material was applied, or whether the material itself was adequate for the waterproofing work in these projects.
Then – According to SPU, there is no question that the “redoing” could not wait until those questions were answered, so that’s why the work is under way now. Ryan says that at both Myrtle and Beacon Hill, and likely also at West Seattle (Westcrest), crews will use a rubberized “hot asphalt” process, said to be more expensive than the product which had been used for the application which is now being removed. Bill Wells, the senior water planner, explained that the “hot asphalt” comes in bricks which are heated before the material is applied the same way hot tar is put on roofs.
We will continue to pursue followups on this story, including the cost information promised next week, and comments we are pursuing from the waterproofing project manufacturers and the contractor, and of course we will continue to track the progress of the work. Once the city has finally accepted the Myrtle Reservoir project and turned it over to the Parks Department late this year (Ryan says the timeline will be similar for Beacon), it’ll take a few months to build the park, for which this was the final “schematic design”:
Side note: Going back through WSB archives, we also found we had reported a glitch in the Parks/SPU coordination last year — Parks had done some designing based on what turned out to be an “imprecise grading survey” they said had been provided by SPU. (Here’s our story from June 2008.)