Kent hires consultant to design Mill Creek sediment pond culvert replacement

Kent City Council authorized the mayor on June 30 to sign a consultant services agreement with Somas Inc. to produce a preliminary design and alternatives analysis for replacement of two culverts that carry Mill Creek under a park trail at the Earthworks sediment pond.

Why it matters: the culverts provide critical access to the park, the water main up the canyon and the sediment pond that requires annual maintenance to remove accumulated material. The existing corrugated metal pipes are degraded and replacement is needed to protect access and improve habitat and flood reduction.

Melissa Dahl, an engineer in Public Works, described the site and the role of the sediment pond in removing hillside sediment before flow continues downstream. She said the two existing corrugated metal culverts are "a little squashed, a little bit eaten down" and the consultant will evaluate alternatives, likely either another culvert or a bridge. Dahl said the city received about $330,000 from the King County Flood Control District Sub‑Regional Opportunity Fund to cover the preliminary design and alternatives analysis.

Dahl said annual maintenance removes "tons of material" from the pond to keep sediment from flowing into lower streets. She said the target for construction is 2027 and the current contract will cover preliminary design and alternatives analysis.

Council member Fincher moved to authorize the mayor to sign the consultant services agreement with Somas Inc., subject to final terms acceptable to the public works director and city attorney. The motion was seconded and carried on a voice vote.

Next steps: Public Works will complete the alternatives analysis and preliminary design under the consultant agreement and return with design and funding recommendations ahead of a 2027 construction schedule.