Mud Mountain Dam

Buckley, Washington

This project replaced an existing fish trap and haul facility downstream of the Mud Mountain Dam to protect homes and businesses in the lower White River and Puyallup Valleys from flooding, and provide fish passage to current standards while mitigating complex habitat and infrastructure needs. Osborn Consulting (Osborn) was responsible for the Care and Diversion Work Plan and the Temporary Environmental Controls, and the temporary diversion of the river flow and fish passage during construction. The Care and Diversion Plan for the river documents each phase of construction, hydraulic modeling for both scour design and fish passage requirements, environmental compliance, and a fish monitoring plan.

Owner

USACE Seattle District & Cascade Water Alliance

AERIAL PHOTOS COMBINED 20180719_Page_1_Image_0001

The Care and Diversion Plan was a critical path item that required approval from regulatory agencies prior to starting in-water work construction. We developed an efficient method and phasing plan to isolate the work area and complete the project while still meeting all project specifications. Our plan included using 170 feet of the existing fish barrier while constructing two of the three bays of the permanent barrier, rather than relocating the river in a bypass channel. Utilizing the permanent gates/barrier for the remainder of the construction resulted in a stable and safe working environment. This alternative approach maximized the use of existing structures and the natural river channel to convey flow and still maintain operation of the fish barrier, fish trap and haul facility, and CWA diversion.

osborn’s plan shaves 20+ months off construction

The plan Osborn developed to efficiently phase and isolate the work area shaved 20+ months off the construction schedule and enabled USACE to use the new facility for the 2021 Pink Salmon run, which is a bi-annual fish run that historically overwhelmed the old facility.

osborn’s access road design helps avoid delays

Osborn developed the design for the access road leading to the trap and haul facility. Originally planned as a two-lane road that transitioned to a one-lane road due to the surrounding topography, a Value Engineering Change Proposal (VECP) was submitted to consider widening the road to include two lanes for the entire extent. The new design avoids delays in the movement of fish hauling trucks or emergency vehicles and removes the need for signal lights on the access road. Instead of the costly fabricated elevated walkway that was initially proposed, the new design was able to accommodate a simple paved pedestrian path along the whole length of the access road.