Expansion to the Annacis Waste Water Treatment Facility

History

Metro Vancouver is serviced by five wastewater treatment plants. The Annacis Island wastewater treatment plant is among the largest, treating about 175 billion liters of wastewater each year. The plant is designed both as a primary and secondary treatment plant. The primary treatment utilizes mechanical processes to remove surface and settled solids, or about half of the solids in the wastewater. The remaining solids and dissolved pollutants are removed during secondary treatment, which uses aerobic bacteria to remove dissolved organic matter. Annacis Island treats wastewater for over 1 million residents across 21 municipalities, one Electoral Area, and one Treaty First Nation.

Problem

Vancouver is expected to grow to a total population of 3.4 million by 2041—a growth of about 1 million residents. The increased population will weigh heavily on the city’s existing infrastructure, requiring upgrades or new developments to fill the gap. A key initiative to help meet the region’s wastewater treatment needs is the expansion of the Annacis Island wastewater treatment facility.

Solution

The expansion to the Annacis wastewater treatment facility will take place over several years and comprises over 20 projects that will ultimately improve the facility’s capacity. These currently planned expansion projects are being conducted in phases and include new trickling filters, secondary clarifiers, and a co-generation facility that will improve the energy generation from the recycled energy captured on site. The expansion will also feature a new outfall pipe. Overall, all the expansion project together will increase the volume of treated wastewater, improve the generation of on-site green energy, and manage odor. Eventually, the facility will also be able to quickly recover and resume operating even shortly after a major earthquake.

Concrete protection is an essential element in extending the lifespan of many critical concrete structures that make up wastewater treatment facilities. Concrete protection liners (CPL) help prevent corrosive compounds and gases from damaging the structures. Since the early 1990s, Metro Vancouver has utilized AGRU’s Sure-Grip®, a high-density polyethylene (HDPE) CPL, on at-risk concrete structures exposed to and in contact with wastewater. As part of the expansion effort at Annacis, the primary influent channel, pre-aeration tanks, and primary effluent channels are being expanded. These new constructions will use AGRU-Ultra Grip® to line the walls and ceilings. Ultra Grip is a new version of Sure-Grip which utilizes an enhanced anchoring system design.

In this one of the many ongoing projects, Metro Vancouver worked with project design consultant Brown and Caldwell to develop the plans for the new grit removal facilities. AGRU’s customer and fabricator, PREDL Systems North America, Inc., then coordinated with the designers and engineers to provide support for the structures to be lined with Ultra Grip, fabricating the Ultra Grip into panels sized to match the exact dimensions of each concrete pouring sequence.

Outcome

The first phase of expansion is estimated to be completed by August 2021 and the final phase of current planned expansion is December 2026. Upon completion, the plant will have an average dry weather flow of roughly 650 ML/d in capacity and will be capable of reaching a peak total installed capacity of roughly 1,632 ML/d.

For new structures, the design service life of the buildings, concrete basins, roofing, and coatings systems are 50 years, 50 years, 20 years, and 10 years, respectively. The tanks, channels, and other structures designed to ACI 350 with additional rebar cover and more robust concrete mix designs have a service life of 75 years.

AGRU Sure-Grip and Ultra Grip have been in active use throughout Metro Vancouver’s wastewater treatment and collection system since the 1990s, lining the digesters, pipes, and more. The new process concrete basins currently under construction by the Graham/AECON Joint Venture at Annacis are being lined with Ultra Grip.