STORMWATER MANAGEMENT BRIEF

A Stormwater Management Brief demonstrating that post-development flows are controlled to the allowable release rate is required for any of the following cases:

• A well-defined swale of 0.15m in depth is not provided alng the side and rear lot lines outside of the 0,60m undisturbed strip discharging to an outlet acceptable to the municipality.
• Proposing subsurface stormwater infrastructure including infiltration galleries, trenches, and soakaway pits.
• If a condition of the consent and/or minor variance application(s) requires the submission of a stormwater management brief
• Accessory buildings (attached or detached from primary dwelling), including but not limited to garden suite, garden home, and garages.
• Increased impervious area

The purpose of a Stormwater Management Brief is to outline the detailed Stormwater Management Plan for the development. When preparing the Stormwater Management Brief, we use the Rational Method or Visual OTTHYMO software to simulate existing drainage conditions.     

Stormwater Management Brief may recommend an on-site stormwater quality control under post-development conditions for any portion of the site that exceeds the pre-development storm drainage. Stormwater Management Brief ensures that stormwater flows are controlled to pre-existing rates on site, up to the 100-year event.   Stormwater management brief may outline the design of the major system to accommodate runoff exceeding the capacity of the minor system for flows up to and including the 100-year storm or Regional storm event, whichever is larger.  

A stormwater management brief includes Pre and Post-drainage area plans showing proposed conditions and identifying the drainage pattern of the site.   Stormwater Management brief may outline the design of infiltration systems to retain stormwater and control the post-development peak flow rates up to the 100-year storm event to the pre-development peak flow rates. 

 Typical stormwater management criteria included in a Stormwater Management Brief for a proposed development are 

• Water Quality – Provide sufficient treatment measures to meet the Ministry of the Environment, Conservation and Parks, (MECP) Enhanced (80% TSS Removal) criteria and promote the at-source removal of potential contaminants. 

• Water Quantity – Provide sufficient water quantity control to maintain post-development peak flow rates up to the 100-year storm event to the existing flow rates or the target discharge rate allowed for the Site in the design of the downstream receiving systems. 

• Erosion and Sediment Control – Provide appropriate erosion and sediment control during construction/area grading to protect adjacent properties from potential siltation.  

 We prepare a Stormwater Management Brief to identify the stormwater management measures including stormwater quality and quantity controls for proposed development to support the site grading and drainage plans.     If additional hard area footprints are proposed, it will produce additional runoff and we need to direct the additional stormwater runoff to a suitable outlet and demonstrate that there will not be any negative impact on adjacent properties.   If the majority of the rear yard is proposed to be hardscaped, percolation will not be feasible and the stormwater flows will drain onto the adjacent properties.   If impervious coverage and an elevated water table depth are present, a Low Impact Development (LID solution is not applicable and we need to design an engineered solution for the stormwater.
Stormwater Management brief typically manages the Post-development storm drainage using a combination of minor (storm sewers) and major (overland) systems.    For Site Plan Applications (SPA) and building permits, municipalities may require a Stormwater Management brief to calculate the pre and post-development stormwater flow calculations and identify how on-site drainage will be managed.  

 For Additional Information please contact

• Miaoyi Xue, P.Eng,
• Joo Min Park, MEng, P.Eng.
• Wei Ming Lin, P.Eng
• Rui Cong Xia, P.Eng

LAND DEVELOPMENT EXPERTS

Land Line: 905 940 9937

After Hours / Text Messages: 647 877 8262

Email: landbuildex@gmail.com  

  Our Licensed Professional Civil Engineers specializing in Grading, Drainage, Erosion/Sediment Control and Stormwater Management have prepared Stormwater Management Briefs for development projects in the following municipalities:

County of Brant, City of Brantford, City of Chatham-Kent, Haldimand County, City of Hamilton, Norfolk County, City of Kawartha Lakes, City of Toronto

REGIONAL MUNICIPLITIES

Durham

    City of Oshawa, City of Pickering, Municipality of Clarington, Town of Ajax, Town of Whitby, Township of Brock, Township of Scugog, Township of Uxbridge

Halton

    City of Burlington, Town of Halton Hills, Town of Milton, Town of Oakville

Niagara

    City of Niagara Falls, City of Port Colborne, City of St. Catharines, City of Thorold, City of Welland, Town of Fort Erie, Town of Grimsby, Town of Lincoln, Town of Niagara-on-the-Lake, Town of Pelham, Township of Wainfleet, Township of West Lincoln

Peel

    City of Brampton, City of Mississauga, Town of Caledon

Waterloo

    City of Cambridge, City of Kitchener, City of Waterloo, Township of North Dumfries, Township of Wellesley, Township of Wilmot, Township of Woolwich

York

    City of Vaughan, Town of Aurora, Town of East Gwillimbury, Town of Georgina, City of Markham, Town of Newmarket, City of Richmond Hill, Town of Whitchurch-Stouffville, Township of King

COUNTIES

Dufferin

    Town of Grand Valley, Town of Mono, Town of Orangeville, Town of Shelburne, Township of Amaranth, Township of East Garafraxa, Township of Melancthon, Township of Mulmur

Elgin

    City of St Thomas, Municipality of Bayham, Municipality of Central Elgin, Municipality of Dutton/Dunwich, Municipality of West Elgin, Town of Aylmer, Township of Malahide, Township of Southwold

Hastings

    City of Belleville, City of Quinte West, Municipality of Centre Hastings, Municipality of Hastings Highlands, Municipality of Marmora and Lake, Municipality of Tweed,  Town of Bancroft, Town of Deseronto, Township of Carlow/Mayo, Township of Faraday, Township of Limerick, Township of Madoc, Township of Stirling-Rawdon, Township of Tudor & Cashel, Township of Tyendinaga, Township of Wollaston

Northumberland

    Municipality of Brighton, Town of Cobourg, Municipality of Port Hope, Municipality of Trent Hills, Township of Alnwick/Haldimand, Township of Cramahe, Township of Hamilton

Oxford

    City of Woodstock,  Town of Ingersoll, Town of Tillsonburg, Township of Blandford Blenheim, Township of East Zorra-Tavistock, Township of Norwich, Township of South-West Oxford, Township of Zorra

Peterborough

    City of Peterborough, Township of Asphodel-Norwood, Township of Cavan Monaghan, Township of Douro-Dummer, Township of Havelock-Belmont-Methuen, Township of North Kawartha, Township of Otonabee-South Monaghan, Township of Selwyn, Municipality of Trent Lakes

Simcoe

    City of Barrie, City of Orillia, Town of Bradford West Gwillimbury,  Town of Collingwood,  Town of Innisfil, Town of Midland, Town of New Tecumseth, Town of Penetanguishene, Town of Wasaga Beach, Township of Adjala-Tosorontio, Township of Clearview, Township of Essa, Township of Oro-Medonte, Township of Ramara, Township of Severn, Township of Springwater, Township of Tay, Township of Tiny

Wellington

    City of Guelph, Town of Erin, Town of Minto, Township of Centre Wellington, Township of Guelph-Eramosa, Township of Mapleton, Township of Puslinch, Township of Wellington North.

Perth

City of Stratford, Municipality of North Perth, Town of St. Marys, Township of Perth East, Township of Perth South, Municipality of West Perth

Middlesex

City of London, Municipality of North Middlesex, Municipality of Southwest Middlesex, Municipality of Thames Centre, Township of Adelaide Metcalfe, Township of Lucan Biddulph, Township of Middlesex Centre, Township of Strathroy - Caradoc, Village of NewburyHuron

Municipality of Bluewater, Municipality of Central Huron, Municipality of Huron East, Municipality of Morris-Turnberry, Municipality of South Huron, Town of Goderich, Township of Ashfield-Colborne-Wawanosh, Township of Howick, Township of North Huron

Bruce

Municipality of Arran Elderslie, Municipality of Brockton, Municipality of Kincardine, Municipality of Northern Bruce Peninsula, Municipality of South Bruce, Town of Saugeen Shores, Town of South Bruce Peninsula, Township of Huron-Kinloss

Grey

City of Owen Sound, Town of The Blue Mountains, Town of Hanover, Municipality of Meaford, Township of Chatsworth, Township of Georgian Bluffs, Municipality of Grey Highlands, Township of Southgate, Municipality of West Grey

Haliburton

Township of Algonquin Highlands, Municipality of Dysart et al, Municipality of Highlands East, Township of Minden Hills

District of Muskoka

Town of Gravenhurst, Town of Bracebridge, Town of Huntsville, Township of Muskoka Lakes, Township of Lake of Bays, Township of Georgian Bay