260076 Stanwood_IS4_Ph2_Manual - SIGNED FULL (R).pdf

This is a signed construction manual for the IS4 Phase 2 project, a storm sewer lift station construction project in the City of Stanwood, Washington. The project involves construction of a concrete cast-in-place underground vault equipped with three 185 horsepower submersible Flygt pumps located at the northeast corner of 92nd Avenue and State Route 532. The system includes a 24-inch diameter restrained joint ductile iron force main that transitions to a fusion-welded 24-inch diameter high-density polyethylene pipe south of SR 532, connecting to the existing outfall. The force main will be sleeved through an existing 36-inch corrugated metal pipe drainage discharge pipe beneath SR 532 to avoid open-cut installation across the state highway. Storm conveyance piping into the pump vault will utilize large-diameter storm drain pipe with catch basins and a jellyfish filter treatment system featuring a flow splitter to bypass larger flows. A 72-inch corrugated metal storm pipe located 14 feet under the sidewalk along the east side of 92nd Avenue requires partial removal to accommodate vault construction. The project scope encompasses all electrical equipment, including VFD starter panels, supply panels, a portable generator disconnect, and power supply vaults. Coordination with SnoPUD is required for the relocation of several power poles.

The project site presents significant construction challenges, including a vault depth of approximately 24 feet with groundwater encountered at 5 feet, necessitating dewatering and shoring systems. Trench side layback is not feasible due to constrained site conditions. The manual serves as the comprehensive technical guide for construction execution and quality control requirements for this complex infrastructure project, providing specifications and procedures necessary for successful completion of the lift station installation and associated appurtenances.