Seattle Emerges as Leader in Resilient Storm and Wastewater Infrastructure

In the aftermath of the 7.2 Seattle Fault earthquake, there were concerns over the possibility of broken storm-water and wastewater pipes under the streets of Seattle, Washington. After dealing with flooded streets and unusable plumbing, Seattle Public Utilities made the difficult decision to change water and wastewater management techniques, including what’s called low impact development, and help provide the cost of a completely new system in the affected areas to have a more resilient system for the future. This is one reason why Seattle is a successful example of forward thinking and disaster recovery gone right.

This story is a work of fiction, including all names and quotes, written by WWU DRR students for public education purposes. Site design by Dr. Scott Miles.

Because of extensive liquefaction, many concrete pipes settled and broke due to lack of support. After the earthquake, toilets in businesses and homes became unusable, causing many homes to be unoccupiable. Residents’ indoor plumbing systems did not work after the event because gravity-based systems were disrupted from the liquefaction damage. Sewage was not able to flow through the system as designed.

The earthquake happened in the midst of the rainy season, leaving parts of Seattle susceptible to flooding on the streets because of non-functioning storm-water systems. Such urban flooding is caused by the lack of bare earth or permeable pavement within cities. Water is prevented from soaking into the ground. The pooling of rainwater further exacerbated other post-earthquake issues. Roads closed on flooded streets causing further transportation issues and blocked access to businesses and homes.

Cars driving through flooded streets in Madison Valley, WA

Cars driving through flooded streets in Madison Valley, WA

Madison Valley, a neighborhood within Seattle, was among the hardest hit within King County, due to its low-lying, bowl shaped topography.

Sally Rickard both lives in the area as well as owns the most popular café in the neighborhood.

“We were the place everyone came to share information and meet up with friends on weekend mornings,” she said.

Rickard went on to describe the challenges she faced during the first rainfall after the earthquake.

“Water took up the whole intersection. It started seeping under the front door. There was so much of it, and no one could help with the flooding because they were dealing with their own damages and just couldn’t.”

Like the Madison Valley Neighborhood, the topography of the land in New Orleans during Hurricane Katrina also contributed to flooding, but on a much larger scale. The storm surges broke six levees causing around 80% of the city to be submerged. The wastewater system significantly damaged. Nearly all the sewer lift stations were out of commission and over 80,000 water mains experienced leaks. The first priority after the storm was repairing the levees and drainage pumps relieve the city of its flooding. Only after that was complete could repairs to the sewage system begin. Because the two utilities are separated in New Orleans, the two systems had to be dealt with at different times.

Within Seattle, the storm and wastewater systems are made up of one of two different configurations: one where storm and wastewater are separated and one where the two are combined. With combined sewer-wastewater systems, the ability to prevent sewage spills can be difficult to predict because of Washington’s rainfall patterns. The combined system can accommodate potential storm water overflows by having pipe capacities based on historical rainfall of the past 20-50 years. Any rain event exceeding that intensity results in overflow, which includes sewage, being discharged straight into the Puget Sound.

Billy Fowery, wastewater supervisor, explained how climate change has the potential to make combined systems more risky because it “may change timing and intensity of precipitation. This would make the existing pipe diameters based on historical records less accommodating.”

After the earthquake, SPU did not have enough replacement pipes and parts on hand, causing several delays in reconstruction their system. Unexpectedly this had a positive unintended consequence: the delay provided SPU officials the time to facilitate discussions about alternative methods for replacing or rebuilding damaged components of the system.

In consultation with the public and other stakeholders, SPU eventually decided to implement a new vacuum sewage system in many areas that needed replacement. This new system was chosen to reduce the number of sewage overflows due to rain, and because of its increased robustness in the face of future earthquakes. If damaged, repairs will be less labor intensive because pipes are buried much shallower than the former gravity sewage system. In areas where the new vacuum system was placed, new infrastructure for managing storm water was then needed—the combined systems could no longer be used.

Changes to SPU’s system were partially funded by disaster recovery funds from FEMA and other related grants. However, SPU had to bridge the gap between funding and cost. Unlike like police and fire departments, which are funded by property taxes and other general fund sources, public utilities are enterprise funded based on rates charged to the customer.

Utility rates had to be raised because of the high cost of repairs and use of new more expensive technology. After SPU proposed the change, it took a month for city council to convene public hearings and eventually approve a higher rate. During this time federal disaster recovery funds were used on simpler repairs.

Two and a half years after the earthquake, all vacuum system projects were complete, which far exceed pre-earthquake estimates by local engineers and scientists. This rapid reconstruction freed up enterprise funds to explore sustainable methods for now dealing with the city’s storm-water management needs.

Seattle Public Utilities teamed up with Washington State Department of Ecology to conceive and implement the Let Water Flow! Program. This city program encouraged low impact development (or LID) practices during the rebuilding process. Utilizing the Puget Sound Partnership’s LID toolkit, a funding matching grant program was set in place to offset some of resident’s and developers’ rebuilding costs. Within the document were various LID techniques that are effective for the area, as well as best practices for their construction.

LID is a design and construction approach that aims to improve the health of water bodies by replicating or replacing the functioning of natural water systems that have been covered with concrete and roofs. Rain gardens, rain catching barrels, and permeable pavement are all LID techniques that let rainwater soak into the ground and be filtered naturally by soil. LID techniques reduce the strain on storm-water systems, filtering out harmful substances, and improve community livability by increasing green space.

Seattle wasn’t the first city to implement LID techniques to their plan for storm-water treatment. Auburn, AL has implemented land use regulations into their city code that help incorporate different land use techniques. The majority of their design standards focus on working with the natural features of an area rather than against it—an important recommendation in LID. The Conservation Subdivision Ordinance has helped the city to better manage the area’s storm-water by treating it as a resource rather than a waste product. Seattle’s program is unique in the way that funding is provided to encourage the implementation of LID.

The Let Water Flow! Program granted homeowners and business’ up to $2000 to offset the cost of implementing LID on their property. Although it sounds expensive, in most cases LID costs less than the original design would have cost, allowing recovering residents’ budgets to stretch even further.

Hannah Jones and her husband have lived in the city for 30 years and applied to the grant program to install rain barrels around their home.

“It was so easy,” she explained, “I just applied and within a few months I was watering my garden with what I got from the barrels instead of the hose.

The LID grant program allowed city residents to positively impact their surroundings through less water pollution, increased green space, and increased city funds from reducing the wear and tear on the storm-water system.

Using Seattle’s City Hall green roof implemented in 2003 as an example, over 80% of the repaired or rebuilt government buildings within the city have added LID elements to their buildings since in the 10 years since the earthquake. These LID features range from simple rain barrels to capture water for landscaping purposes, to constructing rain gardens along sidewalks to catch street runoff.

The Rooftop Garden above the Seattle Department of Licensing Building

The Rooftop Garden above the Seattle Department of Licensing Building

Looking forward, City of Seattle is looking into to treating and reusing the storm-water on government property for non-potable uses such as landscaping. This would conserve drinking water and reduce the amount of pollutants released into Puget Sound.

The city of Seattle has come a long way since the earthquake 10 years ago. By incentivizing Low Impact Development, Seattle has increased the beauty of the city and reduced its risk of future flooding. The transition to more robust vacuum system has made the city an example to others for building back better.