|Contracted To / Performed By
||NAC Constructors Ltd
The Wastewater Treatment Project includes the Arbutus Attenuation Tank, a 5,000m3 underground concrete tank that will temporarily store wastewater flows during high volume storm events to reduce the number of sewer overflows. High volume storm events usually occur in the winter and during these events excess wet weather flows will be diverted into the Arbutus Attenuation Tank. Once the high storm flow has passed, the tank will empty back into the existing sewer system, through the East Coast Interceptor (ECI) trunk sewer system, which directs wastewater to the Clover Point Pump Station and then to the McLoughlin Point Wastewater Treatment Plant for tertiary treatment.
Once the tank is emptied, an automatic cleaning system will be activated to clean the floors, walls and columns of the tank. CRD staff will inspect the tank after each use to ensure it is cleaned and that all wastewater has drained back into the sewer system. The temporary storage of wastewater will reduce the number of overflows and impacts along the coastline. The tank will be kept under negative air pressure to draw air within the tank directly into an activated carbon absorber system that will contain and suppress potential odours. The CRD has successfully implemented this system at the Marigold Attenuation Tank.
The Arbutus Attenuation Tank will be located on CRD-owned land in Haro Woods that is already partially cleared and has been previously disturbed during the construction of existing sewers. Once construction is complete the site will be planted with vegetation appropriate for the local woodland setting.
NAC Constructors Ltd. has been selected by the CRD through a competitive selection process to construct the Arbutus Attenuation Tank. Site clearing took place in March 2019. Construction of the tank began in summer 2019 and is expected to take approximately 16 months to complete. Construction activities include site preparation, excavation, concrete works for the underground tank and connection to the existing conveyance system.