Toronto and Region Conservation Authority LID Design and Sustainability

1. Toronto and Region Conservation Authority LID Design and Sustainability 2017 Annual Municipal Engineers Association Workshop November 22, 2017

2. Presentation Overview • Introduction • Why LIDs • LID Design Options • At-Source • End-of-Pipe • What to Do With This Information? • Key Takeaways

3. Why LIDs? • Primary reason for LIDs are to provide quality treatment and reduce the volume of runoff through infiltration, evapotranspiration, or re-use; • Current practice of storm sewers, oil/grit separators and SWM ponds only provide conveyance, quality and quantity control, but do not reduce runoff volumes; • Result can prolong erosive discharge to watercourses

4. Why LIDs? (continued) • SWM ponds provide quality and quantity treatment, but do not reduce runoff volume generated through development. • Result can prolong erosive discharge to watercourses

5. Why LIDs? (continued) • SWM ponds do not provide water balance function and only retain excess volumes. • Result can prolong erosive discharge to watercourses Development with SWM pond controlling to existing conditions peak flows.

6. Why LIDs? (continued) • SWM ponds do not provide water balance function and only retain excess volumes. • Result can prolong erosive discharge to watercourses

7. Why LIDs? (continued) • SWM ponds do not provide water balance function and only retain excess volumes. • Result can prolong erosive discharge to watercourses

9. Why, But With A Twist • For municipalities, this is why you need to be concerned: • July 8th, 2013. Between 50-100mm of rain fell on Brampton, Mississauga, Vaughan, and Toronto (amongst others); • Resulted in well over $100 Million in erosion damages, primarily to the downstream receiver systems; • Lawsuits against municipalities are arising from flooding and erosion damages; • Further, costs for channel restorations resulting from erosive damages can run $2,500 - $10,000 per linear metre.

10. Why, But With A Twist Reducing erosive volumes to downstream receiving systems using Low Impact Designs can help reduce impacts. LIDs need to be considered as a SWM facility, requiring design input during early planning and development stages to provide adequate SWM services. • But to a municipality that sits upstream of others, this is why you need to be concerned: • July 8th, 2013. Between 50-100mm of rain fell on Brampton, Mississauga, Vaughan, and Toronto (amongst others); • Resulted in well over $100 Million in erosion damages, primarily to the downstream receiver systems; • Lawsuits against municipalities are arising from flooding and erosion damages; • Further, costs for channel restorations run $5,000 - $10,000 per linear metre.

11. LID Design Options Low Impact Development (LID) is a set of design strategies that can reduce stormwater runoff and the cost of managing it. The idea is to minimize impervious surfaces and treat runoff with decentralizedstormwater management techniques

12. LID Design Options • Rainwater Harvesting • Green Roof • Downspout Disconnection • Soakaway (Infiltration Trench/Chamber, Dry Well) • Bioretention • Soil Amendment • Vegetated Filter Strip • Permeable Pavement • Grass Channel • Dry Swale • Perforated Pipe/Catchbasin Source: Cultec

13. Source Controls Conveyance Controls End-of-Pipe Controls Wet Pond CWC / Infiltration Systems Porous Pavers Stormwater Management Practices • Impacts are mitigated through the implementation of Stormwater Management Practices consisting of:

14. LID Design Options – At-Source • Focus on incorporating LID into limited ROW space; • Can include end-of-pipe or at-source options; • Easiest option with respect to road infrastructure SWM is to use ditching; • Ditching, both v-ditching and the preferred flat-bottom ditching, offer quality treatment through filtration, quantity storage component, and opportunities for infiltration and evapotranspiration; • Maintenance is straight-forward and municipalities and Regions currently own appropriate equipment;

15. LID Design Options – At-Source • Other at-source options can include ROW treatments such as a curb cut leading to a filtration strip with a catchbasin located at the lowest point; • Quality treatment, runoff reduction through infiltration and evapotranspiration. • Pros: • Provides for most SWM targets, and can be integrated into most any quantity control practice; • Helps alleviate effects of climate change. • Cons: • Requires adjustments to ROW and alternative maintenance;

16. LID Design Options – At-Source • Further examples include infiltration options such as: • Permeable pavers and/or concrete; • Conveyance treatments including perforated storm sewer system; • Silva Cells in boulevards for infiltration and evapotranspiration. • Goals are to build a SWM system that is capable of providing multiple treatment options, including improvement to quality treatment while providing runoff volume reduction; • Benefits as this facilities can help alleviate the stresses of climate change on the overall system

17. LID Design Options – End-of-Pipe • If at-source or conveyance options are not feasible, there are several end-of-pipe options that can provide final treatment to runoff • 40m of flat bottom swale graded at a relatively flat slope (~1-2%) can provide filtration and runoff reduction benefits previously discussed. • A bio-retention cell can also provide filtration benefits, and focus on enhancing infiltration, if property available; • Very useful in areas where water balance and matching infiltration targets is crucial.

18. LID Design Options – End-of-Pipe • A ROW treatment train system consisting of quantity control through storm sewer storage, initial quality treatment through an oil/grit separator, and final treatment with an end-of-pipe LID covers TRCA SWM requirements; • Focus on preparing a true treatment train, where there are multiple opportunities for runoff to be treated, with each facility complementing the treatment provided by others; • Communication through design process with municipalities is necessary to ensure the design will fit within operation and maintenance capabilities.

19. LID Inspection and Maintenance

20. What To Do With This Information? • Be proactive about LIDs in your municipality: • Consider preparing your own design standards or updating design guidelines to include LIDs based on input from all municipal parties (Engineering, Ops & Maintenance, Planning, Parks, etc). • If you’re looking for a source of help, many Conservation Authorities and consultants can provide assistance; • Also consider looking into stormwater grant programs to help with funding preparation of LID standards to improve water quality and decrease the impacts of climate change; • Federal NDMP Intake 5 closes September 2018.

21. Prepared by The Municipal Infrastructure Group

22. Key Takeaways • SWM measures and LIDs are necessary to reduce the impacts of increased runoff volume. • The majority of LIDs can provide double duty: volume reduction to reduce erosion impacts; and quality treatment through filtration and infiltration, resulting in pond size reduction. • LIDs are SWM facilities that require adequate property space to function properly. Incorporating into site designs at early planning phases will maximize chances of LID designs to be successful and ease long term maintenance. • Developing municipality specific LID standards and ROW standards make the review, construction, and maintenance of LIDs more efficient.

23. Technical Links • TRCA SWM Criteria Document: • http://www.sustainabletechnologies.ca/wp/home/urban-runoff-green-infrastructure/toronto-and-region-conservation-stormwater-management-criteria/ • LID Design Guide • http://www.sustainabletechnologies.ca/wp/home/urban-runoff-green-infrastructure/low-impact-development/low-impact-development-stormwater-management-planning-and-design-guide/ • LID Inspection and Maintenance Guide (DRAFT) • http://www.sustainabletechnologies.ca/wp/home/urban-runoff-green-infrastructure/low-impact-development/low-impact-development-stormwater-practice-inspection-and-maintenance-guide/

24. Technical Links cont. • LID Life Cycle Costing Tool • http://www.sustainabletechnologies.ca/wp/home/urban-runoff-green-infrastructure/low-impact-development/low-impact-development-life-cycle-costs/ • ESC • http://www.sustainabletechnologies.ca/wp/publications/publications-erosion-and-sediment-control/ • LID General Publications • http://www.sustainabletechnologies.ca/wp/publications/publications-low-impact-development/

25. Questions? Dan Hipple, P.Eng. Phone: 416 661 6600 x 5336 Email: dhipple@trca.on.ca TRCA website: www.trca.on.ca STEP website: www.sustainabletechnologies.ca