August 28, 2008

WILLIAM CONWAY/PROGRESS PHOTOGRAPHY

Work on the Galt Wastewater Treatment Plant, led by Detra Builders Inc., is nearly completed. Above, the 80 tonne primary digester lid is lifted into place by a 650 tonne crane supplied by Mammoet.

Increased Capacity

Treatment plant in Cambridge, Ontario gets $23 million upgrade

Sludge dewatering key element of project

DAN PELTON

correspondent

CAMBRIDGE, ON

The growing southwestern Ontario city of Cambridge will have more faith in its water quality and management, thanks to a $23-million upgrade to its Galt Wastewater Treatment Plant that is expected to be completed next month.

The project is being carried out by Detra Builders Inc., a St. Clements, Ontario-based specialist in industrial, commercial and institutional projects with over 200 successful projects to its credit.

As for the new facility in Galt, the aim is to construct a plant that has the capability to “dewater” the sludge held in its digesters.

Dewatering is done by adding a polymer solution that enables the solid material to bind together, leaving the water (centrate) to be purified and discharged back to the Grand River. Prior to construction of the new facility, digested material was hauled off site for processing at other facilities or applied to farmers’ fields.

The final product, commonly referred to as “cake” in the industry, is achieved by running digested material through a centrifuge located in the new facility, which is basically a dryer that rotates at approximately 3500 rpm. From there it is conveyed to four hoppers, where it is stored and ready to be picked up and hauled off site from a fully-automated unloading system.

Detra broke ground at the Galt plant in August, 2006.

“One of the biggest obstacles we had to overcome was handling the material that is pumped to the facility on a daily basis during the shut down of the primary and secondary digesters,” says project superintendent Jason Gagnon.

“The digesters were taken down for new pipe installation, cleaning and fabrication/installation of a new diameter primary digester lid. We tackled the material dewatering by mobilizing a temporary belt press on site with the capacity to squeeze the water from 400m3/day of raw sludge, running five to six days a week.”

On average, the new facility will receive an intake of 320m3/day for processing. The material can be easily processed through one of the two centrifuges.

In addition, the new facility can process digested sludge from surrounding wastewater treatment plants if required.

Prior to Galt, the company had undertaken several water treatment facility projects, including an upgrade and expansion of the water treatment plant in Chatham, Ont.

It included construction of a new pre-treatment and residue-management facility, finished water reservoir, high lift pumps, low lift pumps, backwash pump and replacement of filter media in the existing filter building.

In Galt, residue management includes sludge thickening, clarification, plate settling and dewatering.

The new facility is complemented with new electrical, including high-voltage switch gear, transformers, motor control centre, diesel generator, PLC equipment and all related cabling.

Detra is currently working at the Cornwall, Ont. water pollution control plant; a job requiring that the incoming water main be taken out of service and the new inlet piping and bypass line be installed.

Fabrication of the new backwash pump piping system has been completed. It was installed in parallel with the old piping system to make use of both the new and existing pumps.

Municipal infrastructure projects, such as the one in Cambridge, are likely to become more common in Ontario after federal and provincial politicians agreed on a joint $6.2-billion infrastructure program in July.

A McGill University study, commissioned by the Federation of Canadian Municipalities, estimated last fall that cities and communities across Canada would need $123 billion to fix and upgrade core areas of infrastructure, such as water treatment systems, roads and public transit.

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