The Golden Ears Pump Station (GDEPS) and Sanitary Sewage Overflow (SSO) tank supports the Northwest Langley Wastewater Treatment Plant (NLWWTP) Expansion Program. The GDEPS will convey wastewater flows from Pitt Meadows and Maple Ridge to the expanded NLWWTP. The SSO tank will temporarily store wastewater during wet weather events, providing hydraulic relief of upstream sanitary sewers and reducing sanitary sewer overflows into the Fraser River. Technical challenges during design phase included a small site in a quadrant of the 113 B Avenue interchange, proximity to the existing Katzie pump station, difficult geotechnical conditions, and busy adjacent roadways which required meticulous construction and traffic management. Construction started at the beginning of the pandemic and was successfully managed through this period. To maintain wastewater service throughout the construction period, the connections to existing sewers, the Katzie pump station and force mains were carefully staged to eliminate impacts to the existing pump station operations. To contain deep excavations within the site a sheet pile excavation shoring system was utilized to support excavations and control groundwater. Staged placement of sheet piles was required to control vibrations and prevent settlement of existing sewers, the Katzie pump station, and adjacent major roadways for the interchange off ramp, Golden Ears Way, and the 113B Avenue overpass. This post-disaster facility is designed to prevent flotation and remain operational during a major flood or earthquake event. Located in the Fraser River floodplain, the entrance doors are designed to keep out waters during a 1:500 year flood event. Serving as a community amenity and a welcoming gateway to the local neighbourhood, the partially buried SSO tank is finished with architectural precast concrete panels to reduce the scale of the large tank, Interpretive artwork by Katzie First Nation Indigenous artist Rain Pierre, and a green roof.

As part of NLWWTP Expansion Program, Stantec completed the design of a $64M wastewater pumping station and SSO tank. The Stantec team was faced with the following design challenges: 1) developing a design to fit on a confined small site in the quadrant of the 113B Avenue interchange while avoiding impacts on adjacent traffic during construction and operation of the existing Katzie pump station; 2) preparing a plan to manage traffic to the site during construction without impacting traffic on major roadways surrounding the site. Significant construction traffic was generated from excavation material removal offsite and concrete trucks; 3) developing a foundation design and dewatering approach to minimize the chance of long-term settlement and settlement of adjacent structures and roadways during construction period; 4) designing a system to flush sediment and solids from the tank using the wastewater stored in the tank. To mitigate the challenges, we developed a SSO tank design with a trapezoidal shape, enabling it to fit on the site land parcel which had a similar shape. A site access road and a construction traffic queue lane were constructed from the interchange off ramp to minimize impacts from construction traffic. Raft foundations were designed to mitigate differential settlement. A unique vacuum flush system allows wastewater to be stored in flush chambers and released for flushing sediment the once the tank is drained to the pump station.

Design objectives were successfully achieved, while provincial & federal government building codes and municipal seismic design criteria were also satisfied. Team synergy and close collaboration between Stantec, Metro Vancouver, and community partners led to the development of the final design. The architectural elements not only provide a unifying expression but also serve as a visual amenity for commuters, while simultaneously representing the rich heritage of the local Indigenous community.