Seattle plans $600m project to stop wastewater overflows

US city Seattle has announced a $600m plan which is aimed at preventing untreated wastewater discharges and polluted runoffs into the regional creeks, lakes, the Duwamish river and the Puget Sound.

Under the proposed 15 year plan, a Seattle utility will construct a 2.7-mile combined sewer overflow storage system in the north side of the Lake Washington Ship Canal.

Planned to be built few miles from the planned $3.1bn Seattle roadway, the construction is expected to cost around $374m, reports Reuters.

Seattle Public Utilities spokesman Andy Ryan was quoted by the news agency as saying: "The plan would also keep millions of gallons of storm runoff out of public waterways, reducing threats to human and aquatic health and the region’s quality of life."

The initiative intends to fulfil the promises made by Seattle in 2013 through a consent decree with the US Environmental Protection Agency and Washington’s Department of Ecology to lessen the sewer overflows in compliance with the state and federal laws.

The proposal will be discussed by the Seattle City Council next week.

Construction works for the planned canal is likely to start in 2018.

Nearly one third of the city’s rainwater passes via the storm sewer pipes discharging around 13 billion gallons of runoff into creeks, lakes, and the Puget Sound.

A combined sewer system is utilised by the remaining portion of the city which carries the drainage runoffs and sewage to the regional wastewater treatment plants operated by King County.

Heavy rainfall affect the sewer system in the city, forcing it to discharge untreated wastewater along with sewage and stormwater into the regional waterways, in order to avoid it flowing into streets, homes and businesses.