SEATTLE, Wash. -- Every year, Seattle’s iconic rain washes millions of gallons of untreated sewage and stormwater into the city’s waterways, threatening human and aquatic health and the region’s quality of life.
In 2010, 190 million gallons of combined raw sewage and stormwater spilled from city-owned pipes into Lake Washington, Lake Union, local creeks, the Duwamish River, and Elliott Bay, creating significant health and environmental risks. More than 8,200 tons of toxic metals and volatile chemicals are carried by stormwater alone into the city’s waterways, annually.
Now, the city of Seattle has negotiated a first-of-its-kind proposed agreement with federal and state regulators that will ensure the systematic control of Seattle’s chronic sewage overflows, while allowing the city to use cost-effective and environmentally beneficial projects to control and treat both stormwater and sewage.
The proposed agreement, which took four years to negotiate, goes before the Seattle City Council this week. It could save utility ratepayers as much as $375 million.
“After more than 50 years of projects to protect local waterways, we need to finish the job — and now we’ve got a plan that will allow us to do that most effectively,” said Seattle Mayor Mike McGinn. “We will finish the large projects underway now to control sewage overflows to Lake Washington and move forward with our plans of protecting our waters for future generations.
“This proposed agreement is a refreshing milestone on our way to meeting the goals of the federal Clean Water Act. This new integrated approach will give us better tools and allow smart investments to protect the environment,” McGinn said.
“Building on the great legacy of Jim Ellis and Forward Thrust, this agreement is an important step moving us closer to repairing the past harm caused our local waterways and preserving them for future generations,” said Councilmember Jean Godden, Chair of the Libraries, Utilities and Center Committee.
Under the proposed plan, Seattle agrees it will meet its commitment to clean up sewage overflows under a specific and regulated schedule, to an average of one overflow per outfall per year and meet requirements of the federal Clean Water Act.
Over the next 13 years, the city estimates it will spend about $500 million on capital construction projects, including retrofits, green infrastructure, and large underground storage tanks, to implement the proposed agreement. The city projects that incremental rate increases to fund the CSO/stormwater plan will increase the typical single family annual drainage and wastewater bill $58.76 by 2025.
The proposal is expected to save the city approximately $375 million in future operating and maintenance costs over the next 13 years, primarily because Seattle Public Utilities has been able to demonstrate it uses best practices for inspecting and managing its existing sewer pipes and systems. Using some of the most advanced technology and system analytics available, Seattle’s maintenance program has significantly reduced the risk of pipe breaks and sewage spills. Recognizing this, the proposed plan requires SPU to take a much less prescriptive approach for maintaining its system.
“Today’s proposed agreement signals a new era in managing Seattle's sewage overflows on a grand scale, said Dennis McLerran, EPA Regional Administrator in Seattle. “This proposed agreement will allow city engineers and planners an unprecedented opportunity to use the most flexible, cost-effective and environmentally beneficial stormwater and sewage controls available today.”
Seattle and other cities across the country have asked the EPA for greater flexibility to make smart investments, using a range of tools. This translates into using the right tool, at the right time, at the right place. The proposed agreement would allow SPU to integrate the full set of tools, rain gardens, street swales, low-impact development, larger diameter pipes, larger storage tanks, and treatment, with street sweeping and best operation and maintenance practices. Through an integrated approach, these tools can be applied with care and focus on how well they perform in specific circumstances.
When approved, Seattle’s proposed plan will be the first in the nation to offer a local jurisdiction the flexibility to prioritize both stormwater and sewage control measures in an “integrated plan.” Previous consent decrees with major U.S. cities have focused primarily on pipe systems that carry a mix of stormwater and sewage, not pipes carrying only stormwater to a lake, river, creek or bay.
SPU manages sewage and stormwater, all of which ultimately makes its way to Puget Sound, throughout Seattle.
For about half of the city, both sewage and stormwater are carried to King County’s treatment plant at West Point in a common pipe system with overflow outfalls to prevent sewage backup into homes, businesses and the streets when combined sewage overwhelms system capacity.
The other half of the city is served by a separate sewage-only conveyance system to the West Point treatment plan in parallel with a separate stormwater system conveying stormwater into the nearest waterway with minimal water quality treatment.
Both stormwater discharges and combined sewage overflows contain similar contaminants, but in different concentrations. Unlike stormwater only, combined sewage contains much higher levels of bacteria and other disease-causing pathogens. However, stormwater has a much greater flow volume on a regional scale, and treating it holds tremendous potential for improving water quality. Each can be harmful to humans and the environment.
The Clean Water Act requires that water quality be achieved sufficient to preserve critical beneficial uses, allowing people to swim, boat, fish and enjoy our waterways in countless other ways. The law’s requirements are intended to protect the environment, human health, and preserve our quality of life.
In the development of Seattle’s water quality investment program, SPU has engaged organizations, communities and individuals, seeking their views. These stakeholders have said that preserving water quality is of high importance to preserving the quality of life citizens enjoy in Seattle. They recognize the importance of controlling stormwater discharges and emphasize that sewage overflows are not acceptable.
SOURCE: City of Seattle