This project consists of a floating pump station houses (4) – 4,160 volt 250 horsepower electric pump motors. To get power to the barge located 2,200’ into the lake, required (2) – large generators with (2) 50’ semi-trailers with electrical switchgear located close to 1000’ from shore in the Watershed Forest. The installation was complicated due to the wilderness topography of the lake and surrounding areas. The cooperative partnership created a practical design solution and installation plan for the temporary project. The final design consisted of (2) – 2M watt 480 volt generators, paralleled and connected to a 5,000 amp 480 volt switchgear. From there, (3) – breakers fed (3) – 480:4,160 volt step-up transformers. From each transformer Valley Electric installed 5,000 volt MC cables to each of the 3 barges. On the barge with the 4,160 volt, new pump motors, terminated to a disconnecting switch, then spliced to each of the (4) soft starts. For the other two barges, Valley Electric set up a 4,160:480 volt step-down transformer since the pumps and motors on those barges were 480 volt. The plan was set. The most critical milestone to execute the work before the existing water supply ran out – the lead-time and delivery for the cable and soft starts. To meet the short construction window of time, Valley Electric collaborated with their suppliers to acquire 10,000’ of rated 5,000 volt cable, delivered to the site within 1 week. The soft starts were locked-in and slated for delivery in 4 weeks.
The next challenge activity; installing the cable 2,200’ out and into the bottom of the lake, followed by an additional 1,000’ through the watershed’s forest steep slopes to the generator site. Orion Marine Group (OMG) developed a creative solution for this task. OMG weighed down the barge with ecology blocks on the stern side, allowing the bow able to get into 1’ of water. With one of the 9’ tall 6’ wide 14,000 pound spools loaded, on axels and jacks on the barge, the team drove the barge (with the help of a tug boat and two small skiffs) to the shore. From there, a wire feeder pulled the MC Cable from the spool and off the barge into 300’ of cable tray with cable rollers inside. There was an 8,000 pound tugger tied to a tree in the woods, energized by a portable generator, pulled the whole operation. Once the cable was pulled up to the location in the woods, we used the tug boat and skiffs to move the 50’ x 100’ barge backwards. This process was slow, but critical. The wire feeder had to match the pace of the boats. Not only to make sure that the cable wasn’t drug on the bottom, but to ensure it wasn’t spooled too fast, so to fall on itself and kink. Once the team arrived at the location, the cable was secured to large buoys to keep the ends out of the water while the temporary barges were still under fabrication.
While the barges were being prepped, Valley Electric focused attention on the power plant in the forest. The generators needed to be connected parallel to a 5,000 amp custom-made switchboard. With containers filled with 9,000’ of locomotive cable, the team had their challenges to meet the schedule. End connectors and cam lock splices needed to be installed along with termination ends. Once the generator site was ready, the work transition smoothly to the barges as they became available to work on. The crew then installed the soft starts, concrete vault (for splicing) and step down transformer. The entire project was completed and commissioned on-time, ahead of schedule for SPU to pump water to the City of Seattle. Work on the new project began after the peak water demands in October of 2015.