Project Profile

The Village of Pemberton’s sanitary sewer catchment encompasses an area of 89 hectares comprised largely of residential land use. When it became clear that major portions of the existing sanitary sewer collection system were not only inadequate to accommodate existing peak flows but that there was also excessive sagging of the existing gravity main, the Village began to explore its options. To avoid costly sewer upgrades to the existing system, the Village decided to install a pump station upstream of the sewer reaches to divert flows through a new forcemain to Pump Station 1 on Highway 99.

ISL  provided preliminary and detailed designs and construction services for a sanitary lift station and approximately 900 m of 300 mm diameter forcemain. The project scope included approximately 100 m of directional drilled HDPE under existing bridge structures and crossing of the Arn Canal. The pump station freed up capacity in the downstream collection system to accommodate future development plans.

Challenges

• Significant barriers to open trench construction.
• Redundancy to pump station during power outages.
• Faced challenging dewatering conditions in the direct vicinity of environmentally sensitive drainage channels.

Solutions

• Used a combination of open trench construction where possible and directional drilling at creek crossings and significant existing structures.
• Provided generator backup power and an innovative overflow diversion manhole, operated hydraulically.
• Incorporated a more robust pipe design with full restraint which allowed for reuse of native material as backfill thereby reducing export/import operations and overall cost.
• Closely inspected construction activities.