SWM Pond FAQ

Some municipalities adopt a standard policy. My opinion is it’s a judgment call per site and that if you see you have permanent pool, you see steep embankments for whatever reason, there you can make the call that there’s a potential heightened risk here. Why not fence off that area where the steep embankment is and avoid the risk if it’s a large pond. Signage goes a long way and just reminding people this is infrastructure, this is not recreational facility for swimming, but things happen out there as I’m sure you all know. So, I do strongly think it’s a bit of a judgment call. I think it’s overkill if you have them at every wet SWM pond.

I would go more to the latter and again, depending on the site, if there is a lot of public traffic, find that right location. The location where people might be stopping at a bench or open area by the pond. There’s a great example of exactly what you’re talking about, in Aurora, where we held the training last year for the field session in the Lake Simcoe watershed with a really well thought out sign on what the pond is. It looks like a lake and it’s near an arboretum but it explains what it’s doing. And again, just reminding people, it’s hands off. You shouldn’t be fishing in it, you shouldn’t be swimming in it, your dog shouldn’t be swimming in it. You know, there’s a lot of stormwater runoff from the roads in those ponds, and not the potentially best water. It’s for the aesthetic, but it’s also key piece of infrastructure for water quality. I think a storyboard is probably what you’re talking about. And I agree 100% on something like that, showing sort of a cross section of the pond and what it actually does and how it operates.

I’m not 100% sure which bylaws would trigger enforcement, but I would imagine so. It’s essentially your “no dumping” regulations within your municipality. I think we’ve seen our fair share of shopping carts in streams and a lot of litter, a lot of garbage, especially when the maintenance is not happening and there isn’t that public ownership. But then we’ve seen some really nice well-kept ponds too. I would think it could be part of your whole enforcement portfolio just to remind people out there to be looking for that. I do think it’s best to circle back with your enforcement officers internally and that’s all part of our ongoing message with stormwater management. Not just with design but with planning there’s a lot of integration that’s required within it. So, there’s that enforcement piece you don’t want to forget about with your inspection maintenance programs. What are your teams seeing out there? Are you seeing this as a common concern and maybe it’s time to ramp up? Resource that a little bit better or at least get more eyes on it and see what you can do to mitigate the issue.

From our perspective, we worked with Credit Valley Conservation to determine some of those sensitive areas that we didn’t want people getting into. Particularly in development, and as it turns out, a lot of these areas are stormwater ponds, and of course environmentally sensitive areas. So, what we had done in conjunction with Credit Valley is put in a robust fence, like a commercial chain link, on municipal property and we place a clause, site plan, or subdivision agreement depending on how the lands were developed, including or prohibiting residents or contractors and builders from cutting the fence, particularly gates, into what is known as a municipal fence. So, can someone cut a gate into their fence? The answer is probably not, they would have to go to the municipality to seek approval to do it, and then we will have to break the bad news to them indicating unfortunately they cannot. Where it becomes a bit of an issue is if they back onto a trail way and want access to that trail way. Do they have to go around the block, maybe 3 miles to get those trails? We would look at it on a case by case basis, but the initial reaction that our municipality has, is let’s keep them out of there unless we see a reason to allow them to go in where there’s a trail that gets built later on down the line, then we can certainly provide access.

I think the research we have done and compiling this with input from a lot of departments, TRCA, etc. is the more preventative you are, the better. From my experience with the Algae buildup it’s always connected with some significant sedimentation buildup in the pond. So, we’re seeing it at a number of sites that really require the maintenance and the removal of sediment, because the nutrients are bound to the sediment. That just exasperates any sort of growth of Algae and can take over the pond.

I can’t speak to all of the criteria, but some of the work we’ve done, because we have a bit of an interest in winter salt and chloride, we’ve done some work with some of the pond sediment, and it’s really hard to get pond sediment that is in the sodium absorption ratio, the SAR criteria. It’s hard to get it low enough that it would meet the criteria, I think it’s as low as 1 that meets agricultural land use. So that would probably be one of the most challenging parameters to meet.

We have been successful in doing a sediment reuse. We used the sediment from the pond and reused it with household compost and were able to put it on GRCA lands for tree growth but there are a lot of steps that you need to do. We worked with Francine Kelly-Hooper on that project. She was our consultant and we saw a significant cost savings. We were able to divert almost 3000 cubic meters from the pond at a savings of roughly about $250,000. So, we saw immediate results from that pilot study.

I don’t disagree with keeping them separate. I think the rationale is obviously all your sediment will be compiled/composited into one load to wherever it goes. So arguably there is some advantage if there are hot spots that you could potentially smooth those out and get your concentrations down. But I don’t disagree that more information, more knowledge, is better preparation if the cost of submitting some of these separately isn’t a deal breaker. So, I would agree with you and if that’s what the new soil Reg is saying I think maybe we need to go back and revisit where that recommendation came from.

The inspection from where I’m sitting as a PEng, is part of that certification process. So when you’re passing hands, you’re looking to ensure the pond was built as per its design intent and will function as per its design intent (including meeting peak flow targets, providing the storage volumes that are included in the Environmental Compliance Agreement (ECA)). Through that, there’s different things that hopefully the contract administration along the way have caught, but then being vetted with the engineer is one example. But then there’s the other things that can happen such as sediment accumulation. Likely a lot of them do need that clean out before assumption just to make sure it has that storage capacity again. So that inspection is just part of that whole effort, but I would consider it’s not just an inspection, it’s a series of inspections that make up the assumption certification process.

The assumption process can be lengthy. Some of the things municipalities were finding as we were talking about maintenance infrastructure that needs to be inspected each time, was the fact that it can be so long between construction and assumption that for example, your drawdown valves can actually seize. That’s something that pre-assumption, inspecting that drawdown valve, turning it, make sure it works, making sure water comes out would be a critical piece. So I think that full inspection should be done ahead of its assumption.

If the inspections are being recorded before assumption, that may help benefit you getting a good feel and comfort level with assuming the pond. I would say that you’re probably assuming the pond without a perfect score though. So, because there’s issues downstream, there’s other issues that you’ve inherited. So, the challenge you’ll have, is that the developer and the consultant, they’ll have to be in the know early on. The expectation is that they’d be either translating for you or helping you put it in Citywide, or you have the resources to take their inspection reports and document it in Citywide as you go. Whatever you end up doing, I would recommend you make sure it’s consistent. You establish means and methods early for how it’s recorded. In relation to the consolidated linear infrastructure expectations and the guidance document that’s out there now for people to submit the application – there can be best efforts to document what the municipality is anticipating in assuming, but a lot of that is at different resolutions depending on the situation they’re dealing with and out of the municipality’s control until assumption. So, with that in mind, I think a really good inspection protocol and process in QAQC, along with that certification and the as built drawings, all of those things really packaged up nicely is in your best interest. Whether that is really engaging the Citywide database yet, I think that’s up to the municipality to decide based on the resources you have.

If I could also add to that yes, most likely at the time of assumption your score wouldn’t be perfect, but it helps understanding and communicating with the parties involved to make sure who is responsible for what. So basically, adjusting that expectation and the responsibilities, if there is any funding that is required for if a clean out is required. Having that communication and having that sorted out before assumption it also has a different value for doing inspection before assumption.

The developer, I think they typically will carry at least one clean out cost per pond. They know that that’s just something that needs to be budgeted whether they do it or not. That’s always why you really want to be astute with what information they’re presenting to you through certification and whether or not the due diligence is there. For instance, if they have performed a bathymetric survey before or what are their means for estimating sediment accumulation is and the list goes on. I’ve all different resolutions of how much detail goes into that certification from the developer and their proponent.

Yes, a similar prioritization method has been developed for LIDs. There are slight differences as the criteria and components of LIDs are different. We have adapted a letter grading score for the LIDs, and what’s interesting is what we found with some sites where the LIDs get more complex. So if you’re trying to translate many LIDs at a site to work orders, etc. within Citywide, we found the happy medium for that is to choose the themes. We have the maintenance manager module inspection form theme to inspect bioretention. The inspectors would know, based on the preparation that we’ve prescribed and recommended, where the bioretention features are and they’ll capture the essence in the highlights and what needs to be acted on. If you were going to create six work orders for six rain gardens, that becomes a little bit much, so that’s our take and our adaptation with using the prioritization. Once you have that, you go back and you look at the score for that LID, and it’s a letter grade, so if it scored an A, that would mean you would just continue with annual maintenance. B is just a slight concern with functionality, and once you get to C and D you’re starting to get into something more major going on. For example, the materials might need to be updated, there could be an issue with the outlet etc. You can imagine there’s a longer list depending on the LIDs. Those are things you want to start to see more action on and bring to the attention of your works department. We also added a category which is called T, for testing, so we recommend if something is off on site, whether it’s infiltration testing or synthetic runoff test, taking a sample back to the lab. It could be the biomedia that was supposed to be implemented as an example, if it is questionable, whether or not it’s there or still there, those are just some examples to consider.

That’s a good question, thank you for that. I I’m not an expert with that act, but I believe if there’s a passive kind of association with the pond itself. Normally they have to be offline, but if it’s online, there’s a whole different element that you may want to bring into Citywide. So again, the benefit of using the database is that it’s there for you to adopt or adapt. It’s still municipalities that can benefit from just looking at the methods we’ve incorporated but you might have your own database where you’re still committed to that. We’re still working with our Lake Simcoe watershed municipalities that have gone in a different direction with the database to say we’re always there to help provide resources and show you examples, and you can bring that back to whichever database you prefer. But again, back to your question, there’s room for you to get your head around what, based on the Lakes and Rivers Act, is important for this feature that you know needs to be maintained and assessed in more detail and you build it into your work order, so we have templates that are prepared for different types of SWM ponds. You can add attributes and categories both for the SWM pond relating to that sort of situation and the maintenance work order that’s important for that situation. So, I hope that is giving you a little bit of perspective with the malleability. I’m not a Lakes and Rivers Act expert, so I don’t really want to go into more speculative detail.

SWM Shields are large forebay concrete structures, with baffles and sections to it for settling. It goes back to the Land Rivers Act in adapting your maintenance manager and work order with SWM Shield. That’s just another type of work order you could design. And based on the manufacturer’s recommendations and some rules of thumb, and what the region is comfortable with, you tailor to what you want the inspector to do there. Translate that back and then score the maintenance prioritization. We’ve created categories for wet SWM ponds and dry ponds and there are guides to walk you through the scoring for different types of features there, and you can use that to adapt for different types of features as well. So, you could say we do like this greater resolution, we could just scale it down for some of the criterions, some of the categories are not relevant, it’s up to you but you see what we did with the LIDs. We decided the letter grades make more sense and we don’t need to get into so much detail and apply the golf scores to the LIDs. And perhaps that’s something to think about when you move forward, if you want to score, create a prioritization score, for things like SWM Shields.

Our annual evaluation report card is based both on performance and the inspection. Our report cards include the inspections of the ponds which is point based, so it can fail inspections. Obviously it would have to be a fairly extreme deficiency that you noted, so it’s more performance based, and also includes resident complaints. And then the cost for the manual gauges or real-time loggers is changing all the time. Currently, manual gauges are anywhere from $1000 to $1500, our real-time loggers now are about $2500-ish. They’re installed and maintained over the year, so you’re looking at about $1500 for all of the installation and maintenance. We also remove some of them May through October to reduce damage from freezing, and there’s the web hosting feature too, which is around $400 per year, per gauge.

Some municipalities do two full inspections per year but often, to save time and costs, there might not be a full second inspection, and there would instead be one or two inlet/outlet-specific inspections or a winter inspection around November/December. The full inspection would still identify which larger ponds have specific issues and those would get a second full inspection as needed.

We have operation and maintenance staff out across our municipality and they pass ponds all of the time, so it helps for them to get out and take a quick look, make sure there’s nothing major impacting it. I’m creating a map to say if you’re in this area and you’re driving by, please note this pond and please make sure it’s clear and functioning as it should. Maybe not a full inspection to what we’ve been discussing, but at least a quick look to make sure we’re not having any serious issues.

Our biggest one is they think it’s a natural pond. They don’t realize it’s an engineered facility and then obviously when you go in and dredge it, it looks quite drastic. So, a long time ago, especially when developers were cleaning them, they weren’t doing the Fish and Wildlife Rescues as we do now. So, the biggest thing was the concern for the fish and wildlife in the ponds, especially when they’re draining them down and you see a sea of goldfish flapping around, so visually it was quite shocking to residents. Now obviously when the city does all of the stormwater dredging or storm pond dredging, we hire biologists. We do the proper Fish and Wildlife Rescues. And obviously sediment and erosion control, but that was the biggest one was the fish and wildlife in thinking it’s a natural area.

I would echo that, most of the time residents believe it to be a natural area and are concerned with us impacting it, but to be honest I’m sure most municipalities have had some outlandish emails sent to them from residents. The most recent one I received was where we are retrofitting a dry pond to a constructed wetland. It happened to be that there is part of the slope was used as a tobogganing hill and the subject line was “the town is going to kill children”. So, you can get all sorts of concerns. But what we have done this year, the town is part of an education campaign that we need to do around stormwater management ponds. We’re creating work every time we have a pond for clean out, we’re creating a rendering and having nice signage outside the pond, weeks in advance of the work being done to explain the work. We’re doing a more inclusive and holistic communication plan prior, to hopefully stop some of the misinformation about the work that’s being done at those facilities.