SR 167, SR 161 to SR 410 - Rebuild Interchange Project
Puyallup, Washington
PEC Water provided specialized hydraulic, stormwater, and pipeline engineering as a subconsultant on this WSDOT design-build project, which is rebuilding the SR 167/North Meridian interchange into a modern Diverging Diamond configuration while extending the SR 167 expressway through Puyallup. Working in coordination with Jacobs and the design-build team, PEC Water developed TESC plans, Temporary Drainage designs, and a pipeline replacement analysis for multiple construction phases — protecting the adjacent Puyallup River and wetlands, managing runoff across large active grading zones, and keeping traffic moving safely through a live interchange throughout construction.
Client
Prime
and
Subconsultant
Wapato Diversion Pipeline Replacement
Crossing the new SR 167 alignment is the Wapato Creek Diversion — an 84-inch corrugated metal pipeline that carries fish-bearing flows from Wapato Creek through the WSDOT right-of-way. CCTV inspections from 2009 and 2022 identified structural issues including joint offset at the upstream riser and sediment buildup, and the Stage 2A embankment fill — adding up to 22 feet of surcharge above the existing 12-foot cover — made full replacement within WSDOT ROW necessary.
PEC Water led the hydraulic engineering for the Wapato pipeline replacement, beginning with a condition assessment of the CCTV inspection data and a hydraulic capacity evaluation to confirm the replacement pipe could convey design flows under the increased fill loading. Because the pipeline carries fish-bearing flows, the replacement design had to comply with the project's Fish Exclusion Plan, WSDOT Fish Exclusion Protocol and Standards (FEPS), and applicable Hydraulic Project Approval permits — adding a layer of environmental coordination to what was already a technically complex pipeline project. We produced the replacement plan and profile and a Preliminary Technical Memorandum documenting our analysis for WSDOT review.
Erosion and Sediment Control
The scale of grading on Stage 2A required comprehensive TESC planning across two large geographic zones. PEC Water developed separate TESC plan sets and narratives for West of Meridian and East of Meridian — each covering distinct soil types, drainage patterns, and sequences of land clearing, embankment construction, and surface stabilization.
West of Meridian, the work involves clearing vegetation, removing existing structures, grading for the new alignment and embankments, and restoring roadsides across two full construction seasons. East of Meridian, the work focuses on the interchange reconstruction zone where grading, new drainage infrastructure, and stormwater water quality facilities are being installed in close proximity to wetlands and the Puyallup River. Our TESC designs for both zones addressed all thirteen WSDOT TESC elements — from clearing limits and construction access through dewatering control, pollutant management, and LID facility protection — in compliance with WSDOT and Washington State Department of Ecology requirements.
Temporary drainage designed for a live interchange carrying full traffic while a new Diverging Diamond was built around it.
The Project
The SR 167 Stage 2A Design-Build project reconstructs the SR 167/SR 161/North Meridian interchange into a modern Diverging Diamond configuration, builds a new highway segment to SR 512, and widens SR 167 to SR 410. The full scope includes two new bridges, multiple retaining walls, new sidewalks, utility relocations, and the installation of stormwater systems and water quality facilities along the corridor. Running through the project site is the Tacoma to Puyallup (T2P) Regional Trail, which the project extends with a new shared-use path and buried segment connecting to the Riverwalk Trail — giving cyclists and pedestrians a continuous route through Puyallup for the first time.
For PEC Water, the site conditions added significant complexity to every scope item. The project area sits in the Puget Lowland within the Puyallup River floodplain, with ground elevations ranging from 40 to 70 feet and soils ranging from mixed fill to native floodplain deposits. Sensitive areas — wetlands, the Puyallup River, and fish-bearing streams — border the construction footprint on multiple sides. Every drainage decision had to account for those sensitivities while keeping construction moving on a fast-paced design-build schedule.
Wapato Diversion Pipeline excavation — 84-inch CMP exposed during site investigation
West Meridian TESC Construction
East Meridian TESC Construction
Temporary Drainage Design
Traffic kept moving through the SR 167/North Meridian interchange throughout construction — and keeping water off live lanes while grading, embankment, and interchange reconstruction progressed required a layered approach to temporary drainage. PEC Water designed temporary drainage systems for the Meridian Shoofly, MOT Stage 1, and MOT Stage 2, each representing a different traffic configuration and construction footprint at the interchange.
The Meridian Shoofly presented a particularly intricate challenge: a new temporary roadway alignment had to carry all traffic through the interchange while the permanent DDI was constructed around it. PEC Water sized scuppers, inlets, and conveyance systems for the shoofly lanes per WSDOT Hydraulics Manual standards, ensuring runoff was captured and conveyed without exceeding allowable spread limits on a roadway carrying the full interchange traffic load. For MOT Stages 1 and 2, we developed drainage designs that adapted as construction zones shifted — updating inlet locations, barrier drainage configurations, and outlet arrangements with each staging transition. Every submittal included full hydrologic calculations and technical memoranda for WSDOT review.
Stormwater Treatment Design
The Stage 2A project introduces significant new impervious surface along the SR 167 corridor, triggering stormwater treatment requirements under Washington State Department of Ecology standards. PEC Water prepared the project's Drainage Technical Information Report (TIR), documenting the stormwater management approach for the permanent drainage systems being installed along Meridian Avenue.
Our work included evaluating proprietary stormwater treatment facilities for integration into the corridor's permanent drainage infrastructure, sizing treatment systems for the design storm flows, and documenting compliance with WSDOT and Ecology requirements. The TIR established the framework for how new runoff from SR 167 widening and interchange improvements would be managed — protecting the adjacent Puyallup River and wetlands from untreated highway runoff while meeting the project's long-term water quality commitments.
What we Delivered
PEC Water’s temporary drainage and TESC designs kept construction moving without compromising the environment the project was built to protect. Our hydroplaning analyses resolved drainage challenges that standard inlet spacing could not solve, providing a technically defensible path forward that WSDOT accepted. By designing drainage conveyance and stormwater treatment as a single integrated system — rather than separate submittals that happened to coexist — we reduced the risk of permit violations at sensitive creek crossings throughout every phase of construction.
Over the course of the project, we produced eight submittal packages covering three highway construction stages and four creek locations, responding to dozens of multi-discipline review comments while maintaining schedule on one of Washington State’s most complex active fish passage restoration efforts. The result is a corridor where salmon and steelhead can once again move freely beneath I-90 — and where the construction that made it possible was managed with the same care as the habitat it restored.