Over $400,000 to rebuild primary clarifier
Miriam Ostermann
Times Associate Editor
The Strathmore Town Council is shelling out nearly half a million dollars to fast-track a rebuild on the primary clarifier at the wastewater treatment plant, after a former decision to cover the concrete tank hastened corrosion and prevented routine maintenance to the mechanism.
The primary clarifier, a settling tank built with mechanical means for continuous removal of solids and floating materials, had originally been scheduled for a full refurbishment in 2017, but was rendered inoperable in November of 2015.
As a result of severe corrosion and lack of regular maintenance, the engineering department deemed to have been caused by the mechanism enclosure in a cover, the clarifier mechanism failed.
“[Epcor] is recommending that it gets fixed right away,” said Bryce Mackan, acting director of engineering for the Town of Strathmore.
“We’ve gone through the books and the process and it seems that the original plan design may not have had the covers as part of the original design. It might have been brought up during the design phase or early construction phase that it might be needed.”
According to Mackan, full details regarding the installation of the cover have so far been unavailable and efforts to gain such information from the original staff at the time have gone unanswered. Following Councillor Pat Fule’s question on why the cover was installed in the first place, Mackan informed council that the cover was installed to prevent odours from wafting out of the tank – a problem he said hasn’t become an issue within other communities.
Since the mechanism failed in November of last year, Epcor proceeded to remove some of the cover, drain the tank, and inspect the unit. Epcor concluded the scope would entail the removal of the cover, as a covered clarifier usually contains an exhaust system to withdraw the air to a gas scrubber system so the corrosive and odorous gases can be treated. Rebuild the corroded mechanism, build a new walkway for access to the mechanism for routine inspection and maintenance, and lastly re-surface the corroded mechanism to prevent further corrosion and damage to the mechanism.
According to the town’s engineering department, Epcor has by-passed the process unit – a critical unit as the large concrete tank continuously removes materials from the waste water – with no adverse effects on the effluent quality standards, owing to the treatment plant’s additional designed capacity. However, operational efficiency for Epcor was affected and additional chemical costs incurred to mitigate the lack of primary treatment. Epcor therefore assured the town that shutting down the clarifier would have negative effects, including sludge settlement in downstream process units which require additional maintenance and increased chemical consumption to compensate for the volatile fatty acids (VFA) production.
Councillor Bob Sobol also questioned the action of replacing the unit rather than rebuilding the unit.
“We did ask Epcor about replacing the unit with a brand new drive mechanism, and with rough estimates they have one planned in 2020 just for the mechanism itself and they’re budgeting approximately $560,000 for that project,” Mackan said. “If you look back at the actual list, the actual rebuilding of the clarifier drive mechanism, will actually work out between $120,000 to $150,000. So it’s quite a substantial difference.”
The estimated cost approval involves a completed primary inspection conducted in November 2015 for $50,000, the removal of the roof at over $65,000, construction of a walkway at more than $87,000, rebuild drive/mechanism at $65,500, and resurfacing mechanism at over $65,500. The estimate also included a 10 per cent Epcor management fee and a 20 per cent contingency.
Strathmore town council voted in favour of allocating up to $430,000 from MSI funding for the rebuild of the primary clarifier equipment. Councillor Brad Walls and Councillor Steve Grajczyk were absent during the Jan. 13 regular council meeting.