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Black Diamond sewer upgrade
The Black Diamond Sewer Upgrade Project will increase capacity for 6 miles of regional sewer pipe in Black Diamond. The project will help us treat more wastewater to meet the needs of the growing Black Diamond community.
Project description
Upgrading the sewer pipe to meet Black Diamond's growth
Black Diamond is one of the fastest-growing communities in the Puget Sound region. In 1992, King County built a regional sewer line to serve the area’s much smaller population at the time. Today, we need to upgrade the existing sewer line because it’s reaching capacity. Upgrading the sewer line may include a combination of repairing the existing pipe and installing new pipes
The project will look at options to upgrade 6 miles of sewer pipe in Black Diamond. The option we select will:
- Serve the community’s wastewater capacity needs through 2070
- Ensure reliable wastewater service to Black Diamond's homes and businesses
- Foster a healthy and resilient community with reliable wastewater infrastructure
Project update
February 2025
Crews plan to collect groundwater samples along the existing sewer pipeline on February 19
King County Wastewater Treatment Division (WTD) is in the early stages of the design phase for the Black Diamond Sewer Upgrade Project. Starting as early as February 19, field crews will collect groundwater samples from survey wells installed last year. These samples will help inform design.
To collect samples, crews will access groundwater from the previously surveyed locations and use equipment to download data onto a computer. Crews can complete this work in as little as one day and will spend approximately 30 minutes at each site. The work may take longer depending on site conditions. This work may reoccur quarterly.
For more information, view the February 14 bulletin.
Previous project updates
Project location
Understanding site conditions and community needs
Our team is in the early stages of design for the project. During the design phase, the project team will:
- Survey the project area to understand existing conditions in Black Diamond
- Conduct geotechnical surveys to understand underground conditions
- Inform community members about the project and upcoming survey work
- Analyze design alternatives and identify a preferred option to upgrade the sewer
- Complete 30% design for the project
Working with the community
We’ll share details about specific engagement opportunities as the project progresses
We’re committed to engaging with the community during each stage of the project, and we want to make sure everyone has access to information. We welcome you to take part in the project in the following ways:
- Contact us to have a one-on-one conversation by phone, video chat, email, or in person.
- Invite us to a meeting hosted by your group or organization.
- Join our team remotely or in person at future meetings at project milestones. We will post these meetings on our website and email list once they are scheduled.
Interpretation and translation services are available to you at no cost. If you need them, please contact Annie Plumley, aplumley@kingcounty.gov, 206-263-3203
Los servicios de interpretación y traducción están disponibles para usted sin costo alguno. Si los necesita, comuníquese con Annie Plumley, aplumley@kingcounty.gov, 206-263-3203