The Golden Ears Forcemain and River Crossing Project involves the installation of two sewer force mains beneath the Fraser River running parallel to the adjacent Golden Ears Bridge. These 914-millimeter-diameter (36 in.) pipes will transport wastewater from Maple Ridge and Pitt Meadows to the future Northwest Langley Wastewater Treatment Plant. By augmenting the capacity of the existing system, these new pipes will contribute to the reliable and safe management of liquid waste in a rapidly developing region, while also enhancing seismic resilience.
The project includes a 2,134-millimeter-diameter (84 in.) trenchless crossing spanning 160 meters (525 ft) beneath the Golden Ears Bridge on- and off-ramps, approximately 600 meters (1,968 ft) of open-cut force main, and two horizontal directional drilling (HDD) installations measuring 1,600 meters (5,249 ft) each, under the Fraser River.
Delve Underground is providing preliminary design, geotechnical analysis, civil design, HDD design, seismic analysis, detailed design, permitting, tender support, and construction management.
The ground conditions consist of varying types of soil, including soft to stiff clayey silts and silty clays, which extend to depths exceeding 120 meters (394 ft). These soils are overlain by potentially liquefiable sands along the riverbanks, as well as gravel and cobble zones on the north side of the river. To protect the force mains from these challenging ground conditions, surface casings were employed, extending up to 90 meters (295 ft) in length.
The laydown area for the 1.6-kilometer-long (1 mi) pipeline presented additional complexities. It traversed through wetlands intersected by numerous sloughs, was situated between two archaeological piles, and extended beneath the on- and off-ramps of the Golden Ears Bridge. Keeping the ramps accessible required the installation of a 2,134-millimeter-diameter (84 in.) steel casing pipe rammed underneath the ramps. The casing served as the conduit for the HDD pipe strings that passed under the ramps and houses the permanent force mains under the ramps.