New Install Honorable Mention: WWTP Outfall Extension

Mears Group Inc. took on a short but complicated HDD project in Gig Harbor, Wash., installing 711 ft of 24-in. HDPE in a water-to water crossing under a historical lighthouse sitting on a sandspit and near a community park. Due to 15-ft tides and potential storm surges, Advanced American Construction built stationary platforms for the HDD rigs at both the entry and exit sites 45 to 50 ft above the sea bed. The commensurate hydrostatic head associated with this elevation created an additional 30 psi of required lift to get the anticipated heavy returning drilling fluids (with entrained cuttings) back up to the top of the platform to the recycling plant.

Pressure calculations suggested that this additional 30 psi would likely create a ‘frac out’ condition near the lighthouse, something Mears Group was required to avoid. By using a patent-pending mud recovery system, the additional 30 psi could be eliminated by capturing the fluids at or below the sea bed level and then pumping them up to the platform. This system guaranteed no ‘frac outs’ would occur. The project was completed on-schedule with no delays due to tide or weather conditions.

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Owner: City of Gig Harbor
Engineer: Cosmopolitan Engineering Group
Contractor: Advanced American Construction
Subcontractor: Mears Group Inc.