Findings from phase two of Erin’s wastewater environmental assessment, including how the town can service up to 14,559 people, were presented by Ainley Group at a public meeting on June 22.
The public meeting at Centre 2000 offered information from the second stage of a five-step process.
Joe Mullan of Ainley Group said the preferred alternative was still a single sewage treatment plant with discharge into the West Credit River between the 10th Line and Winston Churchill Boulevard in the southeast corner of Erin.
During phase two, Ainley updated the assimilative capacity study, surveyed existing septic systems, assessed the required capacity and identified alternative treatment sites.
During the presentation, Mullan discussed the updated population figures, septic system studies and treatment alternatives.
What’s wrong with the current septic system?
In his presentation, Mullan spoke of concerns about current septic systems within the urban areas of the town.
“In this part of this process, we know from the background, from the SSMP (Servicing and Settlement Master Plan) and from other reports that there’s a long history of concern over the number and the concentration of septic systems within both Erin village and Hillsburgh,” he said.
In a 1995 study by the public health unit, properties close to the river in Erin village were identified as increasing the potential for contamination. Mullan said many of the lots were too small to comply with standards once the septic systems need replacement.
In 2005, a Ministry of Environment and Climate Change septic investigation found that the community’s septic systems were contributing to nutrients in the West Credit River.
The SSMP in 2014 found many of the systems were over 30 years old and were in need of replacement.
What has changed from the SSMP?
The most noticeable change from the SSMP to the EA process is the potential population increase.
The 2014 SSMP identified only 6,000 people could be serviced, including the existing 4,600. This left only a small growth amount for the two urban areas. The EA has determined that it is possible to service a full build out of the official plan, which is a population of 14,559.
Mullan explained a number of factors contributed to the increase.
Using the best available technology, Mullan said the total phosphorous in the treated sewage would be 0.045mg/L compared to the 0.15mg/L levels in the SSMP. The total phosphorous in the river after mixing with treated effluent would be 0.024mg/L, as opposed to 0.03mg/L as identified in the SSMP.
This number, combined with a higher flow rate based on more current data and a “conservative” but lower per capita sewage rate, contributed to increased potential population.
Mullan stressed the numbers would have to be approved through the official plan.
“This is an engineering number only,” he said.
“We’re saying you could service this in your community; the wastewater treatment facility could be designed to accommodate that, but your actual growth will actually be determined not by our class EA process, it will be determined by your official plan process.”
Mullan added, “We know that this is a viable solution that we’re presenting to the town that will allow you to make some serious decisions about your growth moving forward. We don’t want this to be your driver for growth, we want this not to be a constraint.”
One member of the public asked how other unconventional toxins were studied.
Neil Hutchison of Ainley Group said the company did not study those types of contaminants and there are no ministry regulations governing safe levels in sewage plants.
“The good answer is that sewage treatment plants do take a lot of these things out; the better the treatment for conventional pollutants, which is what we’ve studied, the better removal of other things,” he said.
Who connects to system?
Mullan showed two maps of Erin village and Hillsburgh, each divided into smaller areas.
“We looked at areas, identified and viewed the size of lots, the age of the septic systems in essence,” he said.
Areas shaded in red were recommended not to hook up to the sewage system.
The areas not recommended to connect are:
- – south Erin, which includes a portion of Wellington Road 124, Delambro Drive, Patrick Drive, Killdare Road, Kerry Court, Erinwood Drive and a portion of 8th line;
- – northeast Erin, which includes Credit River Road, Pine Ridge Road and a portion of 10th line; and
- – Upper Canada Drive and Leader Court in Hillsburgh.
Why not two plants?
As identified in a report to council on June 6, Ainley has stated a two-plant solution with two discharge locations would not be viable due to insufficient water quality or flow data available.
Ainley concluded it would cost in excess of $500,000 and take up to 10 years to gather the necessary data – without any guarantee that it would be approved by the ministry.
Mullan repeated these findings to the audience at the public meeting.
Ainley stated a single treatment plant is 27 per cent less expensive than two treatment plants with two discharges for servicing the existing community.
A single treatment plant is 32% less expensive than two plants for servicing full build out.
“The lack of water quality data, the cost analysis, and the fact that we have a viable solution, we … (are) recommending that the single-plant alternative be carried forward into phase three and no further analysis be completed in relation to two discharge or two treatment plant facilities,” he said.
Why not go subsurface?
Large subsurface sewage disposal systems, similar to a septic system typically used for smaller developments, was considered as an alternative.
However, Mullan said that option is not viable.
Repeating the information already presented to council on May 16, Mullan said potential for subsurface disposal in Erin and Hillsburgh would be “highly constrained” by land availability and protection zones surrounding wellheads, water features and existing development.
“Therefore … the use of subsurface disposal systems for discharge for a multi-plant solution is non-viable for Erin due to existing constraints and non-competitive for Hillsburgh due to higher capital and operating costs,” said Mullan.
What’s next?
Mullan said completion of the EA is still expected to be in March 2018.
Ainley is receiving comments on the phase two portion until July 6 and will provide an update to council in July on comments received.
Once that is complete Mullan said Ainley will be working on phase three, which consists of looking at design alternatives for collection and treatment systems.
Phase three will also look into costs as well as potential sites for the sewage treatment plant.
Another public meeting will be held in November and a final report will be presented to council next February.
