Toronto Star: Teedon Pit report overflowing with omissions about silt pond use, consultant tells Tiny council

David Hopkins (bottom row, left), senior hydrologist at R.J. Burnside & Associates Limited, provided an in-depth look to Tiny council at the problems with a sewage water application within the controversial Teedon Pit operations.

By Derek Howard, Local Journalism Initiative Reporter – MidlandToday.ca
Wed., Sept. 8, 2021

A large number of omissions made for a cloudy wash water report, and Tiny council didn’t want to settle with that.

Omissions, undefined descriptions and discrepancies were littered throughout a peer-reviewed document of the wash water facility portion at Teedon Pit, as reported to council by consultants brought on to make sense of the application.

An Environmental Compliance Approval (ECA) application was submitted to the Ministry of Environment Conservation and Parks (MECP) in February by consultant group GHD on behalf of Dufferin Aggregates, for existing sewage works on the Teedon Pit property at 40 Darby Road.

The township of Tiny is currently in an appeal process with the MECP over a permit to take water (PTTW) at the facility, which was granted approval in January. When the GHD ECA application was submitted one month later, along with an engineering drawing and specifications and an impact assessment, Tiny retained engineering and environmental consulting company R.J. Burnside & Associates Limited to look over the proposal and provide comments.

David Hopkins, senior hydrogeologist at R.J. Burnside & Associates Limited, spoke to council at the committee of the whole meeting of their findings and recommendations.

According to Hopkins, the interesting definition of the sewage works component is in the terminology of wastewater on an industrial operation, in comparison to stormwater, which is why the treatment facility of a sump pond, wash plant and silt pond are regulated as sewage works under Section 53 of the Ontario Water Resource Act (OWRA).

“The key thing here is that this is considered to be process water that’s used by an industry,” said Hopkins. “It isn’t really something you’d think of as process water.

“In this case, it kind of is but not really; the only treatment here is settling out of the silt and clay particles.”

Teedon Pit is an aggregate washing facility owned by Dufferin Aggregates, a division of building material and construction company CRH Canada Group Inc. Currently, up to 6.8 million litres of water per day has been authorized, which can be taken from the groundwater system for washing gravel and other on-site uses.

According to the Environmental Registry of Ontario (ERO), the water used in the two ponds, where aggregate is collected while silt and sand settle, is then pumped directed back to the primary wash pond for reuse.

Hopkins systematically went through the problems found in the GHD report to council, dealing mostly with undefined descriptions and unassumed actions regarding the designs, drawing, maintenance of site and environmental confirmation.

According to the GHD report, no surface overflow discharge from the recirculation aggregate wash system is anticipated given the controls established within the sump pond… except possibly under extreme climatic circumstances.

“So that’s kind of an interesting statement,” said Hopkins, noting the ECA does not specify a rate of discharge. “It hasn’t really been defined as to what ‘extreme’ is.”

Surrounding berms to contain the two ponds are mentioned by GHD, but engineering Drawing D-1 doesn’t show the location of the berms.

“That implies to us that the design of the settling ponds has not been completely finalized. And maybe that note is just a misnomer, but it looks like based on that, it says it might have multiple cells; it doesn’t say it will or it won’t,” Hopkins explained.

“However, if you look at Drawing D-1, it also has a note that says ‘silt pond and or sump pond may be lined to prevent water loss’. This implies that maybe they’re not so confident that that silt and clay layer is totally impermeable, and we were suggesting that that needs to be clarified.”

Another issue brought up was that as silt and clay is transferred into the wash pond and settles onto the already existing layer of silt and clay, thickness built up would require a dredging process to remove the excess while not impacting the pond’s natural layer; without removal, any unexpected overflow could threaten other water sources in its vicinity.

The unclear parts of the GHD report involve no mention of whether the dredging would be undertaken through manual labour or machine; the amount taken; the resulting cloudiness that would affect the water in the wash pond; the turbidity or “soupy” quality of the wet material coming out; storage of the wet silt and clay material; how it dries; where on-site runoff would flow to during the drying process; and more.

“As that silt and clay settles out,” said Hopkins, “they say that every four-to-six weeks they’re going to have to go in to remove a bunch of that, and they’ll place that on site either to use in rehabilitation of the site or for sale; they don’t really talk about how they’re going to sell that.”

Mention was made to the vulnerable aquifers and groundwater recharge areas throughout Tiny, and the unclear GHD report addressing that valuable resource.

“On this site, there’s only a little piece of it that’s mapped as a highly valuable aquifer, but if you look at all the borehole logs, there’s obviously all sand and gravel at the surface,” said Hopkins. “And even though those may not be designated as vulnerable aquifers or significant recharge areas, that sand and gravel allows surface water to get to and recharge that aquifer.

“If you go around and start spreading that silt and clay from the bottom of that pond over those areas that are currently sand and gravel, you could affect how much water is going to be able to go down and recharge that aquifer,” Hopkins concluded.

Ultimately, Burnside found Drawing D-1 to be highly problematic in the GHD report, not for what it provided, but for what it didn’t.

“Drawing D-1 does not provide much detail. There’s no elevation for the pond bottom, there’s no berm elevations, there’s no inlet or outlet elevations, or maintenance locations,” Hopkins explained. “There’s a lot of information that isn’t in there that probably should be in there.”

At the end of the ten-minute verbal report, Hopkins provided a list of recommendations, which addressed the issues that the GHD report raised, and pointed to the silt pond design drawing as a key factor in the Burnside conclusion.

“Since the design of the silt ponds is what has the greatest control of the silt loading the sump pond, it’s our opinion that the application can’t be approved until the treatment method is finalized,” stated Hopkins.

Council had many questions.

Councillor Gibb Wishart asked where the maximum of nearly 7 million litres per day of water was pumped to. Hopkins replied that as a business, it would be unprofitable to pump to that maximum always, and related the scenario as similar to the irrigation of a golf course over the span of several days.

“It would be in their best interest to have that pond as water tight as possible because then they’re not losing water,” said Hopkins.

Councillor Tony Mintoff noticed in the Burnside report that a sentence regarding the loss of water through groundwater recharge, ranging from his own estimated average of 10% up to 45%, was the largest part of water leaving the ponds, and needed to be enhanced in the recommendations.

“I think the applicant has known this for some time,” said Mintoff. “They have yet to make an offer to line that pond, to remove it. So to your point, it does cost money to pump the water, but I’m guessing it costs a heck of a lot more to line those ponds to make them impermeable.”

Hopkins agreed with the pond lining suggestion.

“Obviously, if they wanted this issue to go away with the residents, the easiest thing to do — now, it would be expensive — would be to line that pond, then it’s done,” replied Hopkins. “That’s always been an option for them. I think they’re aware of that.”

As a whole, council passed a motion that no decision be made on the ECA application until the applicant satisfies all outstanding matters listed in Burnside’s report, and also included a statement in the comments requesting the MECP to require a liner in any operating water retention pond.

The report from R.J. Burnside & Associates Limited can be found within the agenda package on the Tiny township website.

Archives of council meetings are available to view on Tiny township’s YouTube channel.

Watch the meeting here.

See original article here