Upgrades to the water and sewer systems in Drayton will be needed to ensure both systems meet present and projected future needs, according to engineering reports from R. J. Burnside and Associates.
A report on extraneous flows into the sewage system was commissioned by Mapleton council as part of a response to an order from the Ministry of Environment, following an emergency discharge of the system in 2011.
At that time the municipality was in the process of completing two new lagoon cells as a result of a contingency plan resulting from an emergency discharge in the spring of 2008.
Public works director Larry Lynch explained the 2011 discharge occurred partially because of excess effluent in the lagoon and also because of a need to empty most of the largest cell in order to complete the hook up from an expansion project last fall. The “totally unprecedented” amount of rain last year also contributed to a significant rise in the volume of water in all the lagoon cells, but the MOE also required a report that identified any inflow and infiltration that may have contributed.
David Paetz of R. J. Burnside told council at its Sept. 11 meeting that testing during two recent rainfall events revealed inflow from extraneous sources into all parts of the system, with the heaviest inflows occurring in the downtown core area. Paetz suggested the municipality focus on that area for further study and remedial action.
“Every system is going to have some leakage, so we just want to focus on an area where were going to get the most payoff,” he explained.
The flow-monitoring program involved installing flow monitors at four strategic locations to monitor flows for the period from April to August.
“To some extent, all areas show an increase in flow almost immediately during a significant rainfall event, as well as approximately one to two days after a significant rainfall event,” states an interim report from the engineering firm. The report recommends continuing with the flow-monitoring program, “as there have not been enough significant rainfall events recorded to accurately determine the origin of extraneous flows.”
As a further measure, the engineers proposed to visually inspect the condition of all manholes. During the next few weeks, the visual inspections will be carried out during late night hours at selected manholes throughout the collection system.
“This will identify those catchment areas with high extraneous flows as the base flows at these times would normally be low,” the report states.
“We need a bigger sample to find out how significant the issue is,” said Paetz.
Once the report is complete the engineers will provide council with recommendations for reducing the inflow problems. Potential solutions may include further inspection for illegal sanitary sewer connections; inspection of specific sections of the main sewers and specific laterals and repair to manholes and manhole cover seals where warranted. Detailed smoke testing investigations may be needed on problem areas to determine further trouble spots, the report notes.
Paetz pointed out that illegal connections from residential sump pumps in the village could be a part of the problem.
“There are a lot of homeowners who know it goes into a pipe and the pipe goes into the ground, but they don’t really know where it goes after that,” he said.
Water system
The township also asked Burnside to review the Drayton water supply system to evaluate the system’s adequacy for present and future needs.
Paetz reported the existing wells have adequate capacity for existing and projected future needs and that the distribution system meets pressure and flow requirements for existing demands.
“That’s a very good thing, there’s a lot of places that aren’t able to meet that,” he commented.
However, Paetz said the study indicated there is not enough storage capacity at the water treatment plant to meet existing or future needs. The report indicates projected daytime maximum demands on the system are expected to double by 2031. That means the future expanded distribution network won’t be able to meet future fire flow requirements without upgrades to some of the watermain sizing and looping, upgrades to the existing highlift pumping station or the addition of a booster pumping station.
The addition of an elevated storage system, such as a standpipe or water tower, would be one solution to meeting future pressure and flow requirements, the report states.
Councillor Jim Curry asked if the municipality would need to look at commissioning a currently unused well in the village as part of the solution. However, Paetz pointed out that the two wells currently in use have enough capacity for present and anticipated needs and an additional well wouldn’t address the distribution system issues.
Mayor Bruce Whale said the township needs to be prepared for future expansion in Drayton.
“There is potential for future growth and that’s what we have to start thinking about. It seems like we have a few decisions to make in this area,” Whale said.
