For more than a decade, all of the eco-friendly stormwater projects that Seattle touched turned to green. The city rebuilt block after neighborhood block to incorporate rain gardens and other natural strategies that can clean up and reduce polluted runoff. The projects worked great: they showcased native plants and sucked up the extra rainwater like green urban sponges. Seattle Public Utilities won awards for its work and was viewed a national leader in innovative stormwater solutions.
Then came Ballard.
This past fall and winter, Seattle Public Utilities launched a program to install more than 90 roadside rain gardens throughout the Ballard neighborhood (also see the story that I wrote for Investigate West, a journalism nonprofit, that ran on Seattlepi.com and Crosscut, and I was interviewed on KUOW’s The Conversation). The gardens were built to help divert up to 50,000 gallons of stormwater runoff that otherwise can overwhelm the city’s sewer system and send raw sewage into the Ship Canal.
Seattle Public Utilities was eager to install the pilot project in Ballard in the hope that it could be replicated in other neighborhoods to help reduce sewage overflows in an environmentally sound and less expensive way than simply rebuilding storm sewer pipes and big storage tanks. And if the project worked out, other cities also struggling with costly sewerage repairs could follow suit.
So when the federal government dangled recovery dollars back in 2009, the project got fast tracked. City officials admit they didn’t take the time they normally would have preparing for the project. They did tests and monitoring to prepare for the project, but had to skip winter monitoring when the ground is wettest. They didn’t do as much public outreach to make sure neighbors were in full support. And the fast track ran Seattle right off a sodden cliff.
The rain gardens — basically sloped ditches that are planted with grasses and small shrubs — have turned into muddy messes. Many of them fill with water and don’t drain, or drain so slowly that they have pooled water for three days or more.
Many of the neighbors are not pleased. They worry that a child could drown in the water, which stands a foot deep in places. They’re afraid they’ll lower property values and become breeding grounds for mosquitoes. Residents even started a blog called The Ballard Raingardengue, a play on the mosquito-borne disease Dengue fever.
What are the bigger picture implications of this mess? Let’s take a look at the policy and science questions raises by this muddy misstep.
1. Do rain gardens work?
This question is a big deal. Cities including Seattle, Portland, Spokane, Vancouver, BC, and elsewhere are trying to figure out greener, cheaper, more effective ways to reduce and clean their polluted runoff. Rain gardens are seen as a key tool for getting this done, along with strategies such as green roofs, rain barrels, porous pavement, and tree and land conservation. If the Ballard bomb meant rain gardens were a failed technology, that would be a serious problem.
Happily, that’s not the case. Seattle Public Utilities got unlucky in Ballard. Some of the rain gardens tapped into natural springs and pockets of ground water that flowed into the gardens along with the rain. The soil had finer particles than expected, and they’re slow to drain. With more upfront research, those problems should have been detected and some of the site would have been deemed unsuitable for rain gardens.
As Curtis Hinman, a rain garden expert at Washington State University (see this story about his research center in Puyallup), says, you have to modify your plans when these tough situations arise.
“You either don’t build rain gardens or you put in under drains,” Hinman said. “You really don’t have a choice.”
(An under drain functions sort of like a half-open drain at the bottom of a bathtub, allowing as much water as possible to soak into the rain garden, and letting the excess flow into the conventional stormwater system.)
2. Will communities support stormwater retrofits?
Successful stormwater projects in Seattle’s past have been of two varieties: building green streets in neighborhoods that previously lacked sidewalks, or building green streets in entirely rebuilt neighborhoods.
Residents in areas lacking sidewalks seem to welcome the construction of rain gardens and sidewalks — they’re getting obvious amenities along with their green stormwater infrastructure. In the rebuilt neighborhoods situation — namely the High Point low-income development in West Seattle — the rain gardens were well integrated into the project and were just accepted as part of the package.
In Ballard, the streets where the rain gardens were built already had sidewalks and grassy strips along the roadways that many residents simply viewed as an extension of their yards. Then the city went in, tore up the grass, in some cases eliminated street parking, and then installed rain gardens that didn’t always work as expected. That set up a lose-lose-lose scenario: a big change to the landscape, the perception of lost amenities, and rain gardens that didn’t work as planned.
“This is unlike another utility infrastructure project,” said John Spencer, a stormwater consultant with Seattle Public Utilities. “It’s in your front yard.”
So are retrofits a non-starter for residents when there’s no benefit such as sidewalks to balance the change in landscape?
No. That’s because the city made some key errors in Ballard. There wasn’t enough outreach to get neighbors on board ahead of time. They were shown photos of mature rain gardens where the plants were lush and grown in. Instead they got shallow ditches with a few clumps of grass. Their expectations weren’t well managed. And the rain gardens they got were too focused on performance — diverting as much water as possible — and not enough on aesthetics.
If they had been done right, with community buy in and more attractive plans, rain garden retrofits can still work in Seattle and around the Northwest.
To Seattle Public Utility’s credit, officials there have responded to the residents’ concerns. The department formed a task force with 13 Ballard residents to come up with solutions to the gardens. They’ve filled in a couple of the most problematic sites and are coming up with ways to rehab others.
3. Can rain gardens treat enough stormwater to make a cost-effective dent in sewage overflows?
Cities all around North America — Victoria and Vancouver, BC, Port Angeles, Portland, and others — are trying to stop overflows of raw sewage that are triggered by rain storms. The projects cost tens of millions to more than a billion dollars.
The problem is caused when rainwater gets into the sewer system, which flows to treatment plants. Much of the time this isn’t a big problem. The runoff and sewage get treated together and released into Puget Sound or the Columbia River or wherever.
But when there’s a downpour, all of the rainwater runoff added to the sewage overwhelms the treatment plant and that combo gets dumped into waterways without treatment. The runoff gets into the sewer system either in outdated, combined systems where rain and sewer water are intentionally sharing pipes, or when rain water seeps into aged sewer pipes.
Seattle and Portland have been leaders in experimenting with green strategies in partnership with traditional solutions to reduce the amount of stormwater runoff that gets into the sewer system and causes the overflows.
But will it work? Leaders in both cities think so. The idea is to either keep the water out of the stormwater and sewer systems entirely, or to slow how fast it gets into the sewer pipes. Even if it’s slowed down, that can help. It gives the system more time to treat the extra water that comes with a rainstorm.
The challenge is to balance performance — getting enough water out of the drains and into the rain gardens and green roofs — to make a difference. And that’s going to require a little more tolerance for mud and puddles from the public.
If people won’t tolerate any ponding ever in the rain gardens, it won’t work, said Tracy Tackett, program manager for Seattle Public Utility’s Green Stormwater Infrastructure.
“We’re bringing our utilities above ground in some ways,” said Nancy Ahern, deputy director for utility-systems management for Seattle Public Utilities.
“It’s a change from the status quo,” she said. “There are going to be growing pains.”
4. What’s the take home?
The bottom line is that rain gardens work, and they can reduce stormwater volumes and ease pressure on sewage treatment systems. But they’re not going to work everywhere and they take careful planning.
City workers like Tackett will keep pushing the government to install these less conventional solutions because traditional approaches cost too much and aren’t doing enough to protect the environment and human health.
And scientists like WSU’s Hinman will keep doing research on how to make green stormwater technologies perform better. Hinman, who does a lot of training for engineers and others building and approving natural drainages, says the Ballard snafu has prompted him to urge people working with rain gardens to do really rigorous testing upfront.
“If you don’t do these things you are going to potentially run into problems and be liable,” he warns.
The Rain gardens are a good solution all around and need to be engneeered to meet the soil conditions of the area there installed. One of a great many new ways to allow old ways to happen and make our city work less. Bravo to the rain garden work and better planing, then rushing to spend where ever the money comes from. Tom Crawford
But hold on…urban public space has to serve multiple purposes. Urban public space is not an unlimited resource. What are the opportunity costs and real gains from this strategy, and when and where is it really useful or important? Is any service to stormwater management enough to result in making parts of the urban public realm less useful for gathering, meeting, moving, and making? Is it really true that any diminution of impermeable surface is worth it? Seeing rain gardens and bioswales sprouting like mushrooms in service to a narrow set of objectives makes me wonder how we’re better serving the overall ecology of cities, and what we’re accomplishing when we call any alternative stormwater management green.
Thanks for the feedback, Tom and Ethan. Clearly, careful planning and consideration of the options are necessary to do this right. In the Seattle area at least, I don’t think folks would argue that these green stormwater solutions are “sprouting like mushrooms” though that might be so in Portland. From the examples I’ve seen, little if anything is sacrificed in terms of land use when they’re installed—replacing an impervious patch of grass with native plants and a gentle ditch that temporarily holds water seems like an OK trade. I’m sure there are cases where something more desirable is lost, but I don’t think it’s often.
Jim M. PE
I’ve been thinking of adding these to some suburban county road projects, but I have one concern: we have some areas where the adjacent residents have wet basements. Is that a counter-indication for infiltration methods?
Nice article, Lisa. But can you explain the line “the soil had finer particles than expected.” What exactly were the city workers divining or expecting? And how come they didn’t realize they were planting in clayey soil in the first place. All you have to do to analyze soil texture is rub the muck between your fingers. Perhaps there were hardpans or hidden layers of compaction in the subsoil? But even still, it doesn’t take a whole lot of “careful planning” to discover these issues.
It’s unfortunate that to be able to take advantage of federal grant/stimulus money the city had to cut out some of the engineering prep work to make the project “shovel ready” sooner. I hope this doesn’t sour residents on future low-impact development projects; clearly they work well when the project engineers are allowed to do all their testing. The city had to make a tough choice and luck wasn’t on their side this time.
Niall, as even geotechnical engineering students can tell you, there’s a little more to soil analysis than to “rub the muck between your fingers” especially if you’re going to be putting tax dollars into that soil. The soil under the rain garden needs to drain and that’s at least a foot deep under the surface. The article says there were about 90 gardens and I’m simply assuming that it is not feasible to test all 90 locations, even though soil conditions can vary even over a small area. As stated above, they also had to skip winter monitoring which would have shown exactly how well or poorly the test sites drained during the wettest natural conditions. Anything else was just modeling and predictive calculations; useful, but not a 1:1 substitute.
Anca, as any experienced gardener can tell you, you don’t need no fancy engineering degree to figure out a good baseline for drainage in a specific site. My comment about muck-rubbing was – and it seems like you were too busy being condescending to notice – somewhat facetious, which is why I qualified it with an inquiry about subsoil conditions. I’m just having a hard time buying the excuses that were given here – the soil texture was heavier than expected? What exactly were these folks expecting? Though, as you say, soils can vary widely over short distances, as a general rule, urban soils are terrible – laced with compaction, construction debris, and all sorts of rubbish – and the default assumption should be that they won’t drain the way you’d expect an “average/good” soil to drain. Anyway, how hard is it to dig a 1-foot hole to examine what’s down below? (I can dig a one-foot hole in about 5 minutes. Let’s see, that’s 5 mins X 90 gardens – not a whole lotta time really, and that’s just one hole per site.) Even a simple soil percolation test requires digging a foot-deep hole. And I’d be interested to know why the Utilities folks “HAD TO skip the winter monitoring.” Because of the fast-track, because they were short-staffed, because they were lazy and incompetent, because it’s winter all year long in this godforsaken hole of a city and monitoring would be redundant, because…why?