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During construction, workers may pump groundwater or stormwater away from the site. This process is called dewatering.

Typically, this water is treated and sent to a surface water body, either directly or through a storm drain. If the treated water does not meet water quality criteria; or if direct or indirect discharge is not available, it may be possible to send it to the sanitary sewer. You must get permission from King County and your local sewer agency to send this water to the sewer.

We know that the industrial waste authorization and application process is complex. Please contact us if you have questions and our staff will be happy to assist you. If you have difficulty viewing or downloading documents, please visit Software Help.

Who needs formal authorization from King County?

Authorization not required  Authorization required
(see process below)
  • Single family residential construction projects should check with the local city or sewer agency. KCIW does not require applications from these projects.
  • Projects discharging to separated storm sewers or surface water bodies do not need approval from wastewater utilities. Check with the appropriate entity:
Site characteristics Agency to contact
Contaminated site, any size Washington State Department of Ecology
Clean site, bigger than one acre Washington State Department of Ecology
Clean site, less than one acre Local jurisdiction's storm water utility
Most construction projects discharging to sanitary sewers in King County’s Wastewater Service area (including combined sewers that carry stormwater and sewage in the older parts of Seattle) need approval.

How to get formal authorization

  1. Contact the local sewer agency. Confirm they accept water from construction sites. Confirm the location and conditions for discharging to their system.
  2. Select your King County construction dewatering application (general or individual).
  3. Download, complete, print and sign your application. Scan your signed application and submit it to King County via email: info.KCIW@kingcounty.gov 
  4. Contact the local sewer agency for permission to connect to their system and any additional requirements.

Allow enough time! The General Authorization Process may be complete as quickly as 3-10 working days. The Individual Authorization Process takes about 1 to 3 months depending on the complexity of the project. The cost of General Authorization is a set fee. The cost of Individual Authorization or permit depends on project complexity. Click here for information about fees.

Select your King County application

KCIW offers two types of authorizations for discharging construction water to sanitary sewers:

General Authorization Application Individual Authorization Application

You may be able to use the General Authorization Application for Construction Dewatering if your project meets all of the following criteria:

  • Site is not contaminated.
  • Site is less than 1 acre.
  • Project will discharge less than 25,000 gallons per day (gpm) to the sanitary sewer.
  • Site has a sedimentation tank.

Applying for a General Authorization is easier and requires less documentation (no exhibits) than an Individual Authorization, and no reporting is necessary once the General Authorization is approved.

If your project does not meet all four criteria, you must use the Individual Authorization Application for Construction Dewatering .

Select your application decision chart

Reporting

Your permit or letter of authorization to discharge wastewater into the sewer system may require self-monitoring. View and download the self-reporting forms.

The General Construction Dewatering Authorization does not require reporting.

General Construction Dewatering Authorization Process

  • Takes less documentation and less time
  • Has no required exhibits
  • Has no reporting requirements

Regulations

Contact us

206-477-5300

206-263-3001