J.L. Richards & Associates Ravensview Wastewater Treatment Plant

The existing Ravensview Wastewater Treatment Plant located along the St. Lawrence River in Kingston, Ontario underwent a $115-million upgrade and expansion.

J.L. Richards & Associates were the prime consultants on the project, which increased the plant’s capacity by 30% and also added a secondary treatment to make it one of the most environmentally progressive wastewater treatment plants in North America. As a result of the upgrades, the plant’s effluent quality is greatly improved and exceeds expectations and all regulatory requirements.

Biological Aerated Filters

The existing chemically-assisted primary treatment process consisted of screening, grit removal and primary clarification through seven rectangular clarifiers.

The upgrade added Biological Aerated Filters, a high-rate secondary treatment process that has a very compact footprint. It requires only 20% of the land area of a conventional activated secondary treatment process, which meant that nearby waterfront properties did not need to be expropriated and an adjacent mature woodlot was preserved.

This secondary process includes a leading edge aeration technology — high-speed blowers using air bearings. Manufactured in South Korea and new to North America, the blowers operate at a speed of 30,000 rpm, similar to jet engines.

The technology is much quieter than standard North American aeration technologies and is more efficient. (Standard technologies operate at around 3,000 rpm, and produce so much noise and vibration that they require more significant structural and acoustic mitigation measures.)

Implementing these high speed blowers reduced the plant’s electrical load for the aeration system from 675 kW to 450 kW — a 33% reduction. Despite the capital premium of $300,000, the payback is estimated at less than five years.

Sludge Treatment Innovations

To improve the quality of the biosolids produced from the upgraded plant, the project team added temperature-phased anaerobic sludge digestion. The common practice is to operate these systems at 37 C in a single stage digestion process. The Ravensview plant has a dual stage process operating at 55 C followed by a second stage at 37 C. The dual process kills more pathogens and stabilizes the sludge more effectively, thereby helping to continue the success of Kingston’s biosolids land application program.

Another benefit of stabilizing the sludge at a higher temperature is the increased production of methane bio gas as a by-product. This “free” source of energy is used in a dual-fuel 375 kW cogeneration system to produce electricity and heat year-round.

The high-speed turbo blowers and cogeneration/biogas system as well as other energy-efficiency measures have reduced the plant’s electrical load by 0.6 MW and reduced its greenhouse gas emissions.

Thinking Like Contractors

A fully enclosed biosolids storage facility was added. It operates under negative air pressure and the exhaust air is discharged through activated carbon filters. This approach helps to address the odour problems from the plant, which have historically caused a nuisance to nearby residents.

The existing plant was renovated over a three year period while the plant continued to operate. The upgrades included replacing all the electrical, instrumentation and control systems.

The J.L. Richards’ team, who provided all structural, civil, mechanical and electrical engineering, as well as the planning, architecture, and project management, “thought like contractors” in reviewing how to construct the works. The specifications not only provided a detailed outline and sequence to assist the contractor in the construction, but also now guide the plant’s operators in maintaining the plant.

The buildings’ architecture has a more refined look than typical industrial buildings and they were all designed according to LEED environmental principles.

The upgraded plant has a capacity of 95,000 m3/day and is one of the largest of its kind in Canada. The $115-million project was completed in late 2009 approximately 10% under budget and six months ahead of schedule, in time to ensure a combined contribution of $50 million from the Canadian and Ontario governments.

The plant now serves as a benchmark and training centre for the public, other municipalities, and Kingston-based education centres.

Project name: Ravensview Wastewater Treatment Plant Upgrades, Kingston, Ont.

Award-winning firm: (prime consultant, project management, structural, civil, mechanical, electrical, architecture, planning) J.L. Richards & Associates, Kingston & Ottawa (Dan Lalande, P. Eng., Dale Craig, P. Eng., Brian Davies, P. Eng., Mike Duivenvoorden, P. Eng., Louis Fournier, P. Eng., Brent Whaley, P. Eng., Jim Steele, P. Eng., Randy Romanin, Ted Portmann, P. Eng., James O’Connor, P. Eng.)

Owner/client: Utilities Kingston

Other key players: XCG (process); Dakins (system integration); C & R (health, safety); Inspec-Sol (geotechnical, materials); Enermodal (LEED); RWDI (noise, air); Williamson (public consultations)

Supplier: Eaton (coordination study)