Click here to view this survey in Español: https://publicinput.com/bdtrunkspanish
Welcome
Welcome to the Black Diamond Sewer Upgrade Community Survey. Thank you for your interest and participation. The Black Diamond Sewer Upgrade Project will increase capacity for 6 miles of regional sewer pipe between the cities of Black Diamond and Covington. This pipe serves the City of Black Diamond. Upgrading the pipe will help King County treat more wastewater to meet the growing community’s needs.
We want to hear from you!
The purpose of this survey is to share project information and gather early input from you on potential construction impacts, community interests, and communication preferences.
How to participate
Online
Survey questions are included on each page of this site. Use the menu at the top of the page to click through the site to learn. Answer survey questions about the sewer route, community interests, and how to stay connected as you go along. Hit “submit” at the bottom of each page to ensure your responses are captured.
In person
Join us at one of the following community events:
- Covington Days Festival: July 19 and 20, 2025
- Maple Valley Farmers Market: August 23, 2025
- Black Diamond Labor Days Festival: August 31 and September 1, 2025
Contact us to have a one-on-one conversation by phone, video chat, email, or in person, or to invite us to a meeting hosted by your group or organization. Contact Annie Plumley at aplumley@kingcounty.gov or 206-263-3203.
Fill out a paper copy
Paper copies of the survey will be mailed to residents and businesses in the area. You can also request a paper copy. Contact Annie Plumley at aplumley@kingcounty.gov or 206-263-3203.
Who is the King County Wastewater Treatment Division?
Every day, each person uses about 80 to 100 gallons of water for cooking, washing clothes, flushing the toilet, and more. With nearly 2 million people across our service area, that’s a lot of dirty water! King County Wastewater Treatment Division (WTD) is your clean water services provider. Your local sewer utility manages the local network of sewer lines. WTD collects that water through a complex network of pipes and pumps, sending it to a King County wastewater treatment plant.
Your privacy is important to us
To respect and protect your privacy, we will not collect any personal information in this survey. All responses will be anonymous.
If you have specific questions that you would like to receive an answer to, you can contact the Community Services Lead, Annie Plumley, via email at aplumley@kingcounty.gov or by phone at 206-263-3203.
Map of King County Wastewater Service Area
Fast facts about WTD
Project overview
The Black Diamond Sewer Upgrade Project will increase capacity for 6 miles of regional sewer pipe
King County is upgrading 6 miles of regional sewer pipe to support Black Diamond’s growing community.
The City of Black Diamond is one of the fastest-growing cities in the region. In 1992, the City of Black Diamond built the Black Diamond Trunk sewer pipe with support from King County.
Now, the pipe is reaching capacity. King County plans to upgrade it to serve the growing population by repairing, expanding, or adding new pipes.
The Black Diamond Trunk Sewer carries wastewater from the City of Black Diamond. The existing pipe is located north of the City between Black Diamond and Covington.
Project goals and benefits
Once complete, the upgraded regional sewer pipe will:
- Serve the City of Black Diamond’s wastewater capacity needs through 2070
- Ensure reliable wastewater service to the City of Black Diamond
- Foster a healthy and resilient community with reliable regional wastewater infrastructure
Project location
The existing sewer line was built under roads between Black Diamond and Covington. The map below shows its location.
Map of the existing sewer pipeline
Project timeline
The project is in the early design stage. We expect to finish the design in 2027.
Once the design is complete, construction will begin based on the graphic above.
The schedule may change as we learn more about the project and improve the design. We will keep the community updated as the project progresses.
What's happening now
Community engagement is ongoing, and we are seeking input through this survey to:
- Identify and minimize construction impacts
- Address common questions in future project materials
- Understand community interests and priorities
- Effectively engage with you throughout the project
Fast facts about WTD
How does wastewater get collected?
Wastewater from homes and businesses is collected in one of two ways:
- Through local pipes: Homeowners own their side sewers, which connect to sewer pipes owned by local utilities. Those pipes connect to King County’s regional pipes.
- Through septic systems: Sewage/septic systems collect and treat wastewater when homes and buildings are not connected to local pipes.
King County will not be offering the opportunity for homes and businesses on septic to connect to our regional wastewater system as part of this project.
Your local sewer utility manages direct connections. If you are interested in getting connected to sewer, you will need to go through the Soos Creek Water District, the City of black Diamond, or King County Local Services (unincorporated King County).
