Regional District of Nanaimo will spend close to $200,000 on engineering plans as it prepares to fix damaged sewer pipe and upgrade a pump station in south Nanaimo.
Force main pipe stemming from the Chase River pump station and installed in 1980 was estimated to last between 60 to 80 years, according to an RDN staff report, but major leaks were discovered in the Haliburton Street area in March 2017 and emergency repairs were performed. The pump station also needs upgrades and the RDN board awarded a $199,682 contract to CH2M Hill Canada Limited to prepare a detailed design for the project.
The pipes are made of ductile iron and severe corrosion was found at the lower part, which staff said was likely caused by “gravel and grit.” According to Sean De Pol, RDN director of water and wastewater services, grit gets into wastewater systems through various sources and the pump station also accepts septic tank sewage, another source of grit. Although it is separated at the pump station, some gets through.
“The force mains they’re epoxy coated … and over time with stones sort of bouncing along the pipe, it can be quite abrasive and it removes that epoxy coating on the outside and then can ultimately be an area of corrosion and an area that will start to deteriorate,” said De Pol.
In addition to pipe replacement, plans will include enhanced rock and gravel removal at the pump station, expansion of the force main valve chamber, septic reception upgrades and replacement of motor control.
“The motor control is the electrical component,” said De Pol. “We run our pumps at varying speeds and rotating reuse of each pump depending upon the flows, so we run a lead pump and then we put that off service and we run another one, so there is an electronic motor control system that is aging and needs to be upgraded and components replaced. It’s what allows us to run that pump station in an optimal way.”
Design work is expected to be completed in 2018 with tendering and construction anticipated for 2019.
There is currently $1.7 million in the RDN’s current budget for construction and should the cost exceed that, De Pol said staff will seek further direction from the board.
“We do our budgets typically September/October for 2019, when construction will be underway … and we will be examining what the budget is,” said De Pol. “We’ll either change it as part of that budget process, which I don’t think will happen just purely on the timing, so then the other way we get picked up is we’d carry the $1.7 million and then we would tender the project and at time of award, we would note the new budget amount that would either be less or more.
“If it’s more we would make a recommendation accordingly, either to award or for us to go back to the drawing board and see if we can make the project smaller or less.”