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Regional Infiltration and Inflow Control Program

 

Fixing infiltration and inflow (I/I)

Once an I/I problem has been identified, there are many methods and technologies available to reduce I/I. One primary method focuses on fixing the broken pipes, manholes, and joint connections. Another focuses on reducing the amount of I/I that enters the sewer system from storm events by disconnecting roof drain downspouts and other building or yard drains that may be directly connected to the sewer.

Trenchless Technologies

Pipe bursting of private side sewer line.
Pipe bursting of private side sewer line.

Trenchless technology pipe repair methods may include pipe bursting, or cured-in-place pipe (CIPP). Pipe bursting is a technique that pulls a hardened steel breaker head through the old pipe, breaking it up, and replacing it with a new pipe all in one process.

CIPP repair involves pulling a resin-saturated liner through a damaged pipe which is then cured with steam or hot water to form a tight-fitting, jointless replacement pipe. Trenchless repair methods require less digging than traditional “dig and replace” repair methods and minimize damage to yards and landscaping.

Stormwater Disconnections

Stormwater connections such as roof drain downspouts, yard drains, and sump pumps may be disconnected from the sewer system and redirected to a separate stormwater system.

Cutting downspout
 

Removing downspout Disconnecting a downspout consists of cutting the downspout, capping the drainage line and redirecting the flow.

capping the downspout
 
Redirecting the downspout

 

» Initial I/I Reduction Projects


For questions about the I/I Control Program Web site, please contact Maryann Petrocelli at 206-263-7321 or maryann.petrocelli@kingcounty.gov.


Department of Natural Resources and Parks
Wastewater Treatment Division

Updated: July 3, 2008

 

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