A 660 Acre development on the East side of Cougar Mountain in the City of Issaquah that deeded 440 acres to King County as dedicated open space and provided 1735 residential units, 50,000 square feet of retail and 800,000 square feet of office space. More than 100,000 feet of piping was installed between September 2000 and November 2002
Spotlight
Untraditional and complicated sequence of construction required to fulfill owners commitments.
Problem
To meet expectations of the master planned project, it was necessary to construct the job from the top down. The project had to be constructed without the benefit of existing adjoining infrastructure. Offsite work required to service the project would only be permitted and constructed in subsequent years.
A major portion of the backbone roads, utilities and ponds were constructed during the first season of construction. During the second year more backbone infrastructure, parcel development and reservoir work was initiated. Late in the second year offsite work was also started. Early in the third year construction began on the Booster pump station. Sales agreements required recording of parcels and ability to meet fire flow needs, to allow combustible construction prior to the offsite work being completed. Without the completion of the offsite work and booster pump station, water for fire flow and testing would not be available by conventional means.
Solution
The backbone infrastructure was in place and Neighborhood C, (one of the parcels) was built to a point that was in close proximity to a low-pressure offsite water system. It was conceivable that if the reservoir was completed, water could be drawn off of the low pressure system and pumped up hill through the new piping with a temporary high-lift diesel pump, to the reservoir, to provide water for fire flow on an interim basis. It was confirmed and agreed with the City of Issaquah that the necessary capacities could be met if the required components could be completed, tested and accepted in a sequence and time frame to meet committed parcel recording dates.
Results
A completion plan and schedule was developed based on the availability of plan approvals that would complete all outstanding work within six weeks. A tie-in to the low pressure system was made and a high-lift diesel pump was installed. The reservoir and remaining portions of waterline were completed, tested, flushed and purified. The reservoir was filled and accepted. All work was completed, tested and accepted by the City to allow recording as committed.
Acknowledgements
Owner: OLY – INTRACORP
Engineer: TRIAD Associates
Soils Consultant: Golder Associates, Inc.
Inspecting Authority: City of Issaquah
