City approves funds for project to address localized flooding
Improvements to the stormwater system in the vicinity of the art gallery and public library in Swift Current will help to address a problem with localized flooding after high rainfall events.
Funding for the Herbert Street stormwater system realignment project was approved during a regular City council meeting, April 18.
An intense downpour of rain will result in flooding around the Herbert Street and 4th Avenue NE intersection. City General Manager of Infrastructure and Operations Mitch Minken said the Herbert Street stormwater system has to cope with a large catchment area.
“As a result, the storm main runs at full capacity during heavy rainfall and excess surface water is not able to enter the underground system,” he mentioned. There are two stormwater mains in the area to drain water to the nearby Swift Current Creek. There is a 1,200-millimeter corrugated steel pipe in Herbert Street and a 900-millimeter wood stave pipe that runs through the library parking lot.
However, the City discovered that the 900-millimeter pipe was blocked and disconnected from the system sometime in the past. Minken is not sure why this occurred, but it probably happened as a result of the large variety of underground infrastructure in that part of Herbert Street between 4th and 6th Avenue NE. There is a SaskEnergy substation at the 6th Avenue NE corner with gas line infrastructure and also a water booster station on the same corner.
“So there's numerous water lines in there and of course all the sewer and storm infrastructure,” he explained. “At some point another water line was added in that location and it was decided by the folks at the time that in order to accommodate the additional water line that they would disconnect that storm system in there. So now with the modern construction techniques, we can directionally drill deeper and go underneath that and that gives us the opportunity to put that back in.”
The reconnection of the 900-millimeter pipe will be part of various upgrades of the stormwater system during the project.
The existing stormwater system in the library parking lot will be connected to a new manhole. A 1,050-millimeter diameter stormwater main will be installed over a distance of 14 metres between this new manhole and an existing manhole at 5th Avenue NE.
A new 400-millimetre diameter water line will be installed over a distance of 45 metres through the use of the directional drilling method. This pipe will have a new alignment to ensure proper separation from other underground utility infrastructure.
The City will be able to avoid any further costly work if this project proves to be a success. Minken felt the upgrades and stormwater realignment will help to address the issue of localized flooding in this area.
“As with any storm system, it's all about probabilities and intensity,” he said. “So this solution will definitely help in a number of cases. Large rains like the largest one that we had recently, which was over three inches in less than an hour, no system is going to be able to take care of that. So what we're striving for in this case is to lessen the overground flooding and shorten the duration that water would be in the intersection. So we're hoping that this will help in the majority of storms, knowing that a high intensity event we're still going to see some of the overground flooding, hopefully for not as long.”
The approval of the project by City council means the work can start as soon as conditions allow for it. The main issue at the moment is the frost in the soil.
“We're still hearing reports of four to five feet of frost in the ground yet,” he said. “So until that frost is gone we won't be able to start, but I would venture to say we will probably be in there by about the end of May.”
The City received one tender submission for this project from Knudsen Excavating Ltd. of Swift Current. The original bid was over budget, but the City and the company was able to negotiate pricing and find efficiencies to reduce the cost.
The total cost of the contract awarded to Knudsen Excavating Ltd. is $223,438.04 (including 10 per cent contingency and PST, excluding GST). This is still higher than the original budgeted amount of $200,000 and the surface work will cost an additional $30,000.
The total project cost will therefore be $253,438.04. Council approved the cost increase of $53,500. The additional funds for the project will be made available through the re-allocation of $30,000 from the 2022 paved street rehabilitation capital budget and the re-allocation of $23,500 from the 2022 storm sewer main rehabilitation capital budget.