Wastewater Engineering Requires Coordination between Old and New Plant

The City of York’s original wastewater treatment plant was constructed in 1935 with several additions and upgrades throughout the years. The developed area around the WWTP has resulted in odours that were a nuisance with nearby residences. The following elements directly addressed the public impact of the project throughout the life of the facility:

• Provide a water reclamation facility to meet the current treatment requirements as well as future nutrient removal from wastewater requirements.
• Provide odour control at the existing pumping station. 
• Move the facility away from the residential area.
• Negotiate fair easement agreements with property owners along the force main route. 
• Minimize impacts to the farm ground along the force main route.
• Install trenchless force main at road crossings to reduce traffic impacts along the force main route.

HDR completed the design for the new greenfield WWTP, including biological nutrient removal for nitrogen and phosphorus removal. A new conveyance pipeline was designed to deliver wastewater to the new plant and the existing pumping station was rehabilitated at the existing facility for pumping flows to the new site. 

One of the more complex challenges was the coordination of activities at the existing WWTP. The headworks renovation required significant changes to the electrical service to the existing WWTP to meet the needs of the new pumps. The wet well also required significant work to meet current design standards. The headworks renovations included major shutdowns to the headworks pumping station while maintaining treatment operations. Shutdowns were anticipated to range from 3 to 6 months to complete the work. Relying on bypass pumping for this duration presents significant risks to the contractor and the owner. The general contractor and subcontractors, with coordination with the design team, were able to plan the work in such a way to limit the headworks pumping station shutdown to 2 months. 

During construction operations, local news outlets were periodically on site to update the public on the status of the project. The City conducted an open house in May 2019 to allow the public to tour the new facility. Our staff along with the contractor provided support for the open house and assisted by guiding tours of the facility and answering questions about the construction procedures and treatment processes. WRF staff also periodically conduct tours of the facility for local students. 

Throughout the project, the City, contractor, and HDR maintained a cooperative team approach to meet the City’s expectations on quality, schedule and budget. The project reached completion over four months ahead of the contract date with contract change orders totalling less than 1% of the contract amount.