The Town of Westlock now has a new draft storm water master plan that lays out seven priorities where it can improve drainage to avoid future events like the August 2016 flood.
Council discussed the document at its Jan. 15 committee of the whole meeting and brought it forward to its regular council meeting Jan. 22, where it was approved unanimously.
“The master plan is a guiding document for future budgetary considerations on projects required to be done based on the information included in the master plan,” said interim CAO Simone Wiley, adding councillors will see projects added to the capital budget.
Although the need for upgrades is not directly tied to the 2016 flood, said Wiley, “I guess I would say that the 2016 event brought this a little more to the forefront.”
On Aug. 22, 2016, more than 100 millimetres of rain fell in the region resulting in overland flooding. The town received 77 applications from residents who experienced property damage which were included in the town’s disaster recovery application.
MPE Engineering drafted the master plan and identified the seven priorities using specialized software to model how the current drainage systems would handle one-in-five-year storms and a one-in-100-year storm. Both showed the current system “generally performs well,” but some upgrades are still required.
For example, the drainage ditch and culverts on 96 Ave. are undersized. The drainage channel along the north side of 113A St. is also too small. Making these drainage features able to function properly during a one-in-100-year storm event is Priority 1.
“A primary drainage feature in the town is the west ditch that runs north along 96 Ave. and west along the 113A road allowance and follows a northwest direction… out of town limits for 4.5 km to Wabash Creek,” the report states, adding the ditch has “accumulated silt, debris and vegetation growth over the years resulting in frequent standing water.”
MPE recommends widening and deepening the channel to accommodate a one-in-100-year storm and prevent overland spillage into nearby commercial properties and farmland. A new storm water pond will also be built to provide adequate storage and the estimated capital cost, according to MPE is $2.96 million.
Priority 2 is a 108 St. outlet replacement at a cost of up to $301,500. The current outlet is damaged resulting in sediment buildup that has nearly blocked the 108 St. crossing.
The report also takes into consideration future development in Westgate and Greenfield Estates. Priority 3 sees a new storage pond in Greenfield Estates for $460,905 and a ditch for Westgate, at of $484,435. The cost of the pond and the ditch will be split with developers. The estimated cost of installing larger pipes to accommodate the future development comes in at $757,770.
Priority 4 is preventative maintenance, which will cost between $25,000 and $100,000 yearly.
“As with any infrastructure, preventative maintenance is key to ensuring (the storm water system) is operating at peak performance and does not necessarily degrade prematurely, resulting in high replacement costs and even higher emergency repair costs,” states the report.
MPE also recommends the town develop a storm water system preventative maintenance plan that will see tasks like street sweeping, hydro-vaccing and adding manholes implemented.
A new run-off pond east of Highway 44 and south of Highway 18, at a cost of $1.33 million (a portion of which could be recovered through an off-site levy from future developers) is the fifth priority.
Commissioning a study, worth $18,500, to help alleviate overland drainage in Southview is No. 6.
The final priority identified in the MPE report is replacing pipes the models predicted would be over-capacity during a one-in-five-year storm event.
“While this doesn’t necessarily mean they are flooding, it is an indication they are at capacity, and any further development or inflow may result in flooding,” the report states, and goes on to say the town should approach these upgrades case-by-case.
“They are all very important and several of them have implications regarding public safety if they are ignored. A reasonable timeframe should be determined that allows for realistic budgets to be formed and upgrades to be completed over this period.”
