Regional Infiltration and Inflow Control Program

Why is I/I a problem? > Impacts of Peak I/I

Impacts of Peak I/I on Wastewater Flows

While there are multiple reasons why portions of the conveyance system are at or near capacity, a major contributing factor is the capacity taken up by I/I flows in the system. Several capacity related capital improvements are needed in the regional system that are directly related to excessive I/I entering the system upstream of the needed improvements. The following figure demonstrates how peak I/I flows can far exceed base flows.

Impacts of Peak I/I on Wastewater Flows
(Click for larger view.)

I/I that enters the collection and treatment system also triggers higher operating costs for the region. Operating costs for conveyance facilities such as pump stations are proportional to flow volumes passing through the facilities. I/I also increases treatment costs because more chemicals and electricity are used during peak flows at the treatment plants.

»Back to Why is I/I a problem?

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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