North Shore Wastewater Treatment Plant Conveyance

Phase 1

Henry Foundation Drilling Inc. was hired to complete a design build contract for the new North Shore pump station positioned under the Lions Gate Bridge.  The design consisted of a circular secant pile compression ring adjoining an internally braced secant pile shaft. HFDI worked hand in hand with the client on a cost-effective design for the pump station.  Positioned less than 100m from the ocean and in very difficult sand, gravel and boulder soil conditions, the shoring for this structure was difficult.  Ground water was less than 3m from working elevation, so a robust shoring structure was required.  HFDI designed a temporary secant pile wall in the shape of a keyhole.  The secant piles had to be carried well below the 12m deep floor elevation to allow for a thick tremie slab to be installed.  HFDI used a Liebherr HS895 duty cycle crane to excavate the structure under water, and a 1600m3 underwater tremie slab was installed in only 8 hours using 3 cranes holding tremie pipes and 3 pump trucks.  All reinforced steel and struts were completed by HFDI and a multi step build out sequence organized with the client.

Phase 2

Shafts 2, 6, 8 and 9

Henry Foundation Drilling Inc. designed and constructed temporary shoring for a new pump station and 8 – access shafts to facilitate construction of related pipes to convey wastewater from the existing Lions Gate Wastewater Treatment Plant to the new North Shore Wastewater Treatment Plant. Many excavations were within feet of the existing active 2.1m pipeline, beside railway tracks and/or positioned between other services.