Abandoned municipal water wells can be removed from the list of culprits contributing to Lacombe’s flooding problems last summer.
The city hired Stantec Consulting last fall to review whether overflowing underground aquifers were one of the sources of severe flooding that hit the community in July after heavy rainfalls.
Some residents and business owners questioned whether the city’s move to getting its water supply from a regional pipeline instead of municipal water wells had caused aquifers to overfill because they were not longer being drawn down.
Stantec analyzed historical data for 12 city-owned and four private wells to get to the bottom of the issue.
The consultants found the aquifers had been recharged, with water levels rising about 30 metres, but it was not the source of high water table problems.
Increasing rainfall over the last several years was identified as a more likely factor.
The highest precipitation levels in the community since 1998 occurred in 2008 and 2010, says a report to city council. Irrigating lawns on heavy, poorly drained clay and silty clay soils also contributed.
“It can therefore be conclusively drawn that the recharge of the aquifers that used to provide Lacombe’s drinking water has no correlation to the high ground water and associated flooding that many Lacombians unfortunately experienced this summer,” the report sums up.
Meanwhile, the city has also provided more detail on its plans to upgrade the city’s storm water management system to address flooding.
A $2.5-million project will see a 1.2-metre storm sewer trunk line installed next to a pipe half that size that runs down 45th Street.
The new line will run about 750 metres and will drain a catchment area of about 18 acres and eliminate a chokepoint in the drainage system that was causing water to back up in low-lying areas.
It is expected the new line will improve the ability to remove water fourfold.
Another project worth about $550,000 will boost the capacity of Bruns Storm Pond to 22,000 square metres from 13,000 square metres. The pond is used to hold water after rainfall until it can be released into Wolf Creek.
A third component will see a 35-cm sewage lined twinned to fix over-capacity problems that were causing sewer backups for residents.
The project is expected to cost about $600,000.
Construction is expected to begin this spring and be completed by the fall.
Initially, the city said it would not start until the fall in case there were heavy rains again in the spring at the same time as construction was underway.
Matthew Goudy, the city’s engineering services manager, said on Wednesday that a way has been found to install the new pipelines without taking existing services off line.
“While the work is going on, (the city) will have the same infrastructure they’ve had in the past,” he said
The only work that will be left for a fall start is the expansion of Bruns Storm Pond.
The province has announced disaster relief funding will be available to residents, small business, agriculture operators and municipalities in the Lacombe area affected by flooding July 26-27.
Up to $1.5 million in funding will be available for those faced with uninsurable flood damage. Alberta Municipal Affairs is working with the city and county of Lacombe to set up registration dates and locations.
pcowley@www.reddeeradvocate.com