McAleer Creek is a six mile long salmon-bearing stream in the Lake Forest Park area. When it became necessary to connect a water main across its path, we needed a method that would ensure it remained undisturbed.
The story began back in 1972, when a water main servicing the Sheridan Beach neighborhood of Lake Forest Park broken under McAleer creek. In order to restore service quickly, our crews isolated the broken section by capping off the water main on either side of the creek.
Fast forward to 2018, while in the middle of conducting tests to assess the accuracy of our computer hydraulic model (as part of our Water System Plan update), we noticed the hydraulic modeling numbers for water flow and pressures in that area didn’t match our field readings.
Further investigation identified the culprit: the water main that had been capped off on either side of McAleer Creek. In order to provide consistent water pressure and flow to this neighborhood, we needed to connect those two mains.
A “closed loop” system not only supports better water pressure and flow, it creates resilience that helps our water system adapt to unforeseen situations, such as natural disasters or underground soil movement.
Engineers from Psomas were hired to help us identify the best approach. After considering several options and working with the City of Lake Forest Park, we agreed to use a “boring” machine capable of horizontal directional drilling (HDD) for the portion of water main under the bridge and creek, as shown in the following illustration:
Upon completion of multiple State Environmental Policy Act (SEPA) tasks and a Critical Areas report, the District hired Ryatt Construction to install approximately 600 feet of water main under the street, with an additional 540 feet of High-Density Polyethylene (HDPE) pipe installed by subcontractor LineScape under McAleer Creek using horizontal directional drilling (also known as “boring”). The project scope also included new services, a new fire hydrant, and storm drain and street improvements.
Day one of the project involved stretching out multiple sections of the new HDPE water main along Beach Drive, fusing the sections together, and positioning them on rollers in preparation for pulling the pipe through on the following day, “very similar to a needle pulling thread into the bore hole,” says Michelle Macauley in this video:
They also excavated two pits, roughly 275 feet away from either side of the creek, through which the boring would take place.
On September 16, the boring effort began with a “pilot bore” from one side of the creek to the other; followed by several “ring passes” through the pilot hole to enlarge it to roughly one and a half times the size of the water main, as explained in this video:
On September 17, once the pilot hole was drilled and enlarged, LineScape crews attached the new water main and began pulling it through, as seen in this video:
Once the pipe reached the second bore hole on September 18, the connection was cleaned, the pulling equipment was disassembled from the pipe, and the pipe was connected to the existing water main on the other side of the creek. Later this month, Ryatt Construction will finish installing ADA accessible ramps, curbs, and paving overlays.
North City Water District wishes to thank the surrounding neighbors for their patience during this project, LineScape for their excellent drilling services, and Ryatt Construction for their coordination and communication to neighbors and District staff throughout another successful water main project!