The projected flow rate for a future Erin wastewater treatment plant is sufficient, Ainley Group president Joe Mullan told council at a special meeting on Jan. 26.
Mullan presented a four-page report, answering council questions relating to the per capita wastewater flow used in the report.
The current flow rate used for calculations in the ongoing wastewater environmental assessment (EA) is 380 litres per person per day (L/p/d), which includes a 90 L inflow and infiltration buffer.
Changing the flow rate now could have an impact on the total cost of the wastewater system. Mullan estimated changing the flow rate from 380 to 315 L/p/d would reflect a total of $8.8 million in savings to the preliminary capital cost (to service a full build out of) $118 million.
However, he recommended not changing the flow rate for several reasons.
Mullan said the current average water consumption in Erin is low, but it could change in the future as septic restrictions are lifted, the community grows and sees different demographics move in, and the push for development of secondary suites increases.
He added the ministry guideline of a 90 L/p/d inflow and infiltration buffer is low in comparison to other municipalities that have aged systems, but is in place for future deterioration possibilities.
“We feel that the number that we presented … is a conservative number, it’s a reasonable number to use moving forward,” he said.
In his report, Mullan said the change to the flow rate would save the town about $8.8 million. It would reduce the preliminary capital cost estimate by $6.8 million and it could save about $2 million in the trunk sewer system.
“I truly recognize the challenges you have financially … however, we are still of the opinion … (and) recommending to you that you stick to the 380 (L/p/d),” he said.
The current costs are estimated at $118 million to $128 million ($50 million to $60 million for the existing community and $58 million to $68 million for future development).
His report also noted it would cost the town approximately $40,000 in engineering fees to revise, review and finalize the reports if council decided to change the flow rate.
Councillor Jeff Duncan said the 90 L/p/d buffer seemed high for the new system.
“It is a high number and there are some sort of explanations for it,” said Mullan.
He explained the number accounts not just for leakage, but also for illegal sump pump and storm drain hook ups as well as deterioration.
“We feel it is prudent to allow for (90 L/p/d),” he said.
Councillor Matt Sammut questioned the community’s current water usage of 195 L/p/d, pointing out the average in Canada is 329 L/p/d.
“That’s a massive difference,” he said.
“It’s because water is so expensive,” councillor John Brennan joked.
Mullin said, “We believe your numbers … we know that water conservation over the last three to five to seven years has been bringing the number significantly down.”
Sammut asked what the risks were to reduce the flow rate.
“Obviously the lower you come with that buffer … in our opinion, increases the risks that we haven’t got it right in the future,” said Mullan.
“You obviously don’t want to be in a situation … whereby your flows are greater than what your capacity is.”
Brennan said it would be less expensive to leave the number the way it is.
“It seems to me that it’s a lot less expensive to come down in the future than it is to go up because now you have to go in and add stuff to the existing infrastructure to meet your targets and that’s got to be a lot more expensive,” he said.
Council passed a resolution stating it does not authorize updates to the technical reports to reduce the flow rate. A public meeting on the town’s wastewater is set for Feb. 2 at 7pm at Centre 2000 in Erin.
