Marina Upgrades
City of Des Moines
Des Moines, WA

Shore Power Distribution: Completed 2008.  Construction Cost: $1.7 Million

North Marina Upgrades: Completed 2011.

Wood Harbinger’s used an innovative design with off-the-shelf products to reduce initial project costs and simplify maintenance requirements.


Built in 1970, the City of Des Moines’ aging marina needed an upgrade to improve the facilities for boaters and serve as an attractive destination for visitors. The City contracted Wood Harbinger multiple times to upgrade the electrical systems and fire protection standpipe systems throughout the marina. Wood Harbinger provided mechanical and electrical engineering design, specifications, cost estimate and construction administration services.

Shore Power Distribution

In the preliminary phase of the first upgrade project, we conducted a study of the entire site’s electrical systems. Subsequent phases under this contract encompassed electrical and mechanical engineering design for the phased upgrade of the Marina’s medium-voltage upland distribution and low-voltage pier distribution systems.

The first phase encompassed upgrades for the upland distribution system for the office building, new guest moorage, new dry storage, and Docks A through O, as well as electrical system upgrades and a new fire protection standpipe system for Dock N.

Subsequent phases included upgrades for the cable carrier system and fire protection standpipe system at Dock M, and just the fire protection standpipe system at Dock J.

In order to accommodate the master plan, which included future facilities and buildings on site, we designed the upland distribution system similar to a campus design, with additional electrical power capacity that enables flexibility for future development, and including 15 kV feeders, switchgear, and unit substations with ductbanks and sectionalizer switches to allow the Owner to efficiently distribute the system and create some redundancies in the event of an underground fault.

We routed the distribution north-south, via underground ductbanks, along the far east side of the site to avoid any other underground utilities, such as sanitary sewer, water and underground low voltage. Unit substations were placed at strategic locations to drop the voltage to 480/277 volts and provide power to accommodate a group of docks or upland facilities.

After analyzing the complex tide and wave forces, Wood Harbinger developed an innovative shore-to-dock cable protection system that keeps the cables out of the water and stable while in motion at the gangplank. This kind of high-speed cable carrier system is typically used in automated plants, bridge cranes, and other industrial applications, and results in less required maintenance and easier serviceability. We used readily available off-the-shelf products in a new way, which kept initial design and construction costs below budget and simplified required maintenance.

We also provided a low-voltage and communications ductbank system running parallel to the seawall to provide new pathway and cutover from existing system, located on the exterior of the seawall. The ductbank can be extended to a potential new dock and seawall section.

We brought 480 volt power down onto the docks and strategically provided three transformers and associated branch circuit panelboards along the length of the dock to minimize cable sizes and minimize voltage drop. Each slip received a dedicated circuit with a capacity for 50 amps to give the Owner and boat tenant flexibility to accommodate their boat power requirements. This also minimized any shutdown time to other tenants while servicing power for a particular slip.

Coordination for the new service cutover required maintaining the existing 15 kV system while phasing in the new system.

North Marina Upgrades

Wood Harbinger’s next project at the Des Moines Marina encompassed modifications on the north end of the marina, which included the fishing pier, guest moorage docks, and the parking area. This project was once again phased to maintain marina operations during construction.

We conducted a preliminary study of these areas, as well as design to extend power to the guest moorage dock and miscellaneous north marina upland areas from an existing unit substation located adjacent to the Harbormasters Office. We also provided new lighting for the north parking lot in the upland area, and extended the Comcast and communications ductbank system, routed parallel to the seawall, for cable pathway and cutover from the existing system.

After analyzing the complex tide and wave forces present in this portion of the marina, Wood Harbinger reused its innovative shore-to-dock cable carrier system that keeps the cables out of the water and steady. At the north marina, the required utilities included potable water, fuel, power, and communication/data. The fuel piping had to be reconnected from the upland fuel tank to the floating fuel dock.

We also provided shore power boxes and power pedestals upland, for use during various events at the parking lot. The pedestals have interchangeable faceplates to easily provide different configuration of plug and circuit breakers on pre-fabricated faceplates without rewiring. They also include easily removable tops and blank covers for winter storage, and times when they are not needed.

The mechanical system upgrades at the north marina included design for a standpipe system that allowed users to easily attach it to the dock, and interconnection between the existing fuel dock and the fuel tank with new concrete dock.