Introduction

The Port Dalhousie Wastewater Treatment Plant (WWTP) services the western part of both the City of St. Catharines and the City of Thorold, with a service population of approximately 71,500 people.  The WWTP is a conventional activated sludge facility and has a rated capacity of 61.4MLD. 

The Waste Gas Burner (WGB) system was installed prior to 1972 and is beyond its service life, causing significant operational issues at the plant.  Biogas produced as a by-product of the anaerobic digestion is captured and stored either for reuse as an alternative fuel source for the plant boilers or burned (flared) prior to release to the atmosphere.

Port Dalhousie WWTP receives the majority of hauled winery wastewater within the Niagara Region.  This high strength wastewater is directed to the digester to avoid upsetting the normal aerobic plant processes.  Due to limitations of the WGB system, it is unable to effectively flare off the excess methane gas, this results in an excessive amount of gas building up within the digesters that must be released by bypassing the WGB.  As this is outside the normal operation of the digester, the gas release must be reported to the Ministry of the Environment as a “spill”.  The Ministry of Environment, Conservation and Parks (MECP) is aware of the issues with the WGB. 

Repairing or replacing parts on the WGB system is complicated because of the age of the existing components and the scarcity of replacement parts for this vintage of equipment.  The current WGB is “grandfathered” but would not meet current TSSA guidelines.  Once modified, recertification of the equipment with the TSSA is necessary.  In addition, some of the specifications of WGB are described in the Certificate of Approval from the MECP.  Any modifications to the current system will trigger a new approval application for an amendment.  The WGB system no longer conforms to the guidelines set by the MECP so a full replacement of the system is required to meet regulatory standards.

The Region requires a proactive action plan for the elimination of the methane releases to the environment and, to comply with air pollution parameters, with the replacement of the WGB system we should be able to effectively eliminate these issues. 

1. Review and determine the capacity of the new waste gas burner system based on standards, codes, and past performance data of the Port Dalhousie WWTP
2. Administer and include all applicable permits, Ministry approvals and regulatory approvals and standards
3. Review options and determine location for new waste gas burner system
4. Design a new waste gas burner system, including; supporting infrastructure, all process piping, equipment, and valves, any existing infrastructure or piping that will need to be relocated to accommodate new burner system
5. Design demolition of existing waste gas burner system

Port Dalhousie WWTP is undergoing a large upgrade that is phased into two construction contracts, phase 1 is scheduled to start early 2021 and phase 2 will be tendered in 2023.  Phase 2 includes the replacement of the associated MCC and SCADA panel for the WGB system.  The Port Dalhousie WWTP WGB system will be designed separately, and in an accelerated manner, in order to be ready for construction in 2022.