Black Diamond culvert replacement project receives $2 million

A small stretch of 224th Avenue Southeast will soon become a bridge.

By Ray Miller-Still • March 3, 2021 9:30 am
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These culverts run water fromLake Sawyer underneath 224th Avenue Southeast to Covington Creek. But soon, this stretch of road will be a bridge instead. Photo by Ray Miller-Still
These culverts run water fromLake Sawyer underneath 224th Avenue Southeast to Covington Creek. But soon, this stretch of road will be a bridge instead. Photo by Ray Miller-Still

More than $2 million is expected to head Black Diamond’s way to help the city replace some failing culverts underneath a well-traveled road.

According to city documents, the Covington Creek culverts — located underneath 224th Avenue Southeast — have been on Black Diamond’s capital improvement plan as a top priority for nearly a decade. The culverts, which feed water from Lake Sawyer into Covington Creek, are nearing the end of their usefulness; this causes flooding on the road and makes it difficult for salmon to migrate.

The project started small. Before 2020, the city’s plan was to put up guardrails to prevent erosion into the culverts, and then replace the culverts themselves — a project that was expected to cost less than $1 million.

However, while completing the 2019-2024 Capital Improvement Plan, the city decided to instead replace a section of the road with a bridge, which would remove the culverts and any impediment to water flow. This caused the cost of the project to spike to more than $2 million.

To find funding for the project, the city appealed to the King County Flood Control District. The district’s executive committee, vice-chaired by King County Councilmember Reagan Dunn, approved an interlocal agreement with Black Diamond for roughly $2.3 million on Feb. 17.

The Black Diamond City Council approved of the agreement during its regularly-scheduled Feb. 18 meeting, but the agreement must first be approved by the whole of the Flood Control District Board of Supervisors before it becomes active. This is expected to happen March 9.

“We appreciate the opportunity to partner with the Flood Control District to replace the three culverts on Covington Creek with a bridge, which has been a project on our Capital Improvement Plan for many years,” Black Diamond Mayor Carol Benson said in a press release.

Construction is not expected to start soon. According to the agenda bill for approving the interlocal agreement, permitting and design work will be completed this year, with heavier construction beginning in 2022. It’s unclear how construction will affect commuters at this moment.

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