OUR ENGINEERS PREPARE STORMWATER MANAGEMENT REPORTS

Concept Site Plan for a Pre-Consultation Meeting.

OUR ENGINEERS PREPARE STORMWATER MANAGEMENT REPORTS FOR SITE PLAN APPROVALS & SUBDIVISIONS

A Stormwater Management (SWM) Report should be prepared by a qualified civil/water resources engineering consultant. The Stormwater Management (SWM) Report must be stamped, dated, and signed by a Professional Engineer (P.Eng.) licensed in Ontario.

Our well-experienced, qualified professional engineers licensed in the Province of Ontario, specializing in Storm Drainage and Stormwater Management, prepare Stormwater Management Reports to support Zoning By-law Amendments, Plans of Subdivision and Condominium, Consent to Sever and Site Plan Control Applications, and to obtain building permits in Ontario, including

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 MUNICIPALITIES

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 Newbury

Huron

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 Sauble Beach, Town of South Bruce Peninsula, Township of Huron-Kinloss

County of 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

County of 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

The objective of a Stormwater Management (SWM) Report is to evaluate the effects of a proposed development on the stormwater and drainage system, and to recommend how to manage the rainwater/snowmelt for the proposed development, consistent with the municipal requirements for storm drainage, and also meet conservation authority and provincial regulations for stormwater management.

A Stormwater Management (SWM) Report may be required in support of the following development application types:

Official Plan Amendment
Zoning By-law Amendment
Draft Plan of Subdivision / Condominium
Site Plan Control
Consent to Sever
Minor Variance

The Stormwater Management (SWM) Report must provide sufficient engineering information to allow for the necessary review and acceptance of the proposed stormwater management schemes in principle and should address, but not be limited to, the following:

Identify and describe the site location, area, pre-development and post-development conditions for storm drainage, etc.;
Identify the inlets from upstream and outlets to downstream for the minor and major systems, including overland stormwater flow routes;
Identify all internal and external stormwater drainage areas under existing and future development conditions for minor and major stormwater flows;
Identify constraints and potential opportunities – quantitative, qualitative, erosion sensitivity, and environmental concerns related to stormwater for both interim and ultimate development conditions;
Identify existing stormwater management requirements and/or criteria that apply specifically to the site (applicable watershed);
Indicate the design assumptions and conceptual engineering schemes to manage both the quantity and quality of stormwater run-off;
Identify how the water balance requirement is to be achieved through the use of green infrastructure and/or
Low Impact Development (LID) techniques;
Assess mitigation measures to minimize any negative impacts on the stormwater drainage system by applying appropriate on-site controls.
Demonstrate that the stormwater management proposal has maximized source control measures to reduce stormwater runoff from the site and maximized conveyance control measures to infiltrate and/or treat stormwater runoff as appropriate and consistent with water quantity and quality objectives;
Indicate if off-site land or works are required to implement the stormwater management proposal and comment on the extent to which (e.g. easements, dedication, land acquisition, etc.);
Indicate the interim measures required for erosion, pond siltation and sedimentation, downstream works, and riparian flow considerations during the construction phase;
Indicate if other agencies have jurisdiction and if their approvals or permits are required (e.g., MTO, MECP, Conservation Authority, Niagara Escarpment Commission, etc.) and provide a record of approvals;
Submit all stormwater management plans, modeling results, and calculations to support the stormwater management proposals.
If a Drainage Proposal is requested, the outlet(s) are to be identified and storm sewer capacity verified.

The owner of the site is encouraged to discuss the need, scope, and proposed stormwater management concepts and design assumptions with municipal staff prior to preparing the stormwater management report.

All stormwater management designs must meet the criteria set out by the Municipality, the MECP, and the Conservation Authority. Stormwater quantity control is typically implemented to minimize the potential for downstream flooding, stream bank erosion, and infrastructure overflows. The objective of the water balance is to capture and manage annual rainfall on-site to preserve the pre-development hydrology. The water balance consists of runoff, infiltration, and evapotranspiration.
Detailed calculations and the design of the stormwater management facilities and drainage systems based on the accepted principles in the draft report or Drainage Proposal must be accepted before, or in conjunction with, the final acceptance of the engineering drawings.

For Additional Information, don't hesitate to get in touch with the following Key Players of Our Visionary, Dynamic, and Dedicated Design Team:

Miaoyi Xue, P.Eng,
Joo Min Park, MEng, P.Eng.
Rui Cong Xia, P.Eng
Mahboubeh Ghasemizaniani, PhD
Saloni Khoja, B.Arch.
Liu Sun, B.Des (Arch)
Pamela M Jerezano, B.Arch

LAND DEVELOPMENT EXPERTS

Landline: 905 940 9937

Text Messages: 647 877 8262

Emergency: 416 727 8336

Email: landbuildex@gmail.com

We have qualified, licensed professional engineers specialized in storm drainage and stormwater management, and can rush your project through when you need us.

Our qualified, licensed professional engineers have deep experience working with municipalities, which enables a faster response to address their concerns.

Our qualified, licensed professional engineers collaborate with architects, arborists, and surveyors to respond to changes quickly whenever required.

A Site Plan Application for a proposed Land Development near a regulated floodplain, a wetland, or a river valley may require additional assessments and studies, including the following:

Stormwater Management Plan and/or Natural Hazards Assessment to prove to the conservation authority that the proposed land development will not increase flood risks.
Hydrologic and Hydraulic (H&H) assessment to prove the development will not create or worsen flood risks. HEC-RAS Hydraulic model to prove to the conservation authority that the proposed land development will not negatively impact flood levels, storage, or safe access.
Flood Report/Floodplain Analysis/Flood Hazard Assessment/Flood-Risk-Management Report

A “Floodplain” is an area of land that is flooded by nearby water bodies, including creeks, rivers, and lakes, during large storm events. When the storm event passes, the floodwaters generally recede from the floodplain and return to the watercourse. Examples of floodplains include low-lying lands that flood or become inundated when a river spills over its banks or when lake levels rise due to storm surge or heavy precipitation. Floodplains are natural features that allow flow to spread across the landscape.

A “Spill” occurs when floodwaters leave the watercourse, its valley, and the floodplain and spill overland, typically in multiple directions by complex pathways, before rejoining the same watercourse at a distance downstream, flowing into an adjacent watershed or remaining within the spill area if there is no outlet. Spills often mix with urban flooding on roadways and other urban surfaces. A spill can occur due to individual or a combination of factors, including ground elevations that slope away from a watercourse and its floodplain or because of barriers to the passage of flood flows such as undersized bridges or culverts.

HEC-RAS - Hydrologic Engineering Center’s River Analysis System (HEC-RAS) is standard software made by the U.S. Army Corps of Engineers. It simulates water flow and calculates water surface elevations in rivers, streams, and floodplains, and estimates how much stormwater runoff a watershed generates from a specific storm event. Conservation authorities use it to verify building safety and set regulatory flood lines.

Hydrologic Engineering Center’s River Analysis System (HEC-RAS) is widely accepted and frequently required by Conservation Authorities such as Nottawasaga Valley Conservation Authority(NVCA), and Grand River Conservation Authority (GRCA) to perform 1D and 2D hydraulic modeling for floodplain mapping, flood risk assessments, and development reviews.

Key Requirements for Conservation Authority such as Nottawasaga Valley Conservation Authority(NVCA), and Grand River Conservation Authority (GRCA) Submissions

• Regulatory Flood Standards: Models must evaluate the Regional Storm (typically the Hurricane Hazel or Timmins storm event) or the 100-year (1% annual chance) flood, whichever is greater.

• Model Acceptability: HEC-RAS (1D steady/unsteady or 2D models via RAS Mapper) is standard

• Hydrologic Inputs: HEC-RAS is often paired with an upstream hydrologic model built in HEC-HMS to generate peak flows and hydrographs for various return periods.

"Hydrologic Modelling" analyzes rainfall, runoff volumes, and watershed characteristics like soil and slope to calculate peak flow rates.

"Hydraulic Modelling" uses software such as HEC-RAS to simulate water behavior, velocity, and precise flood-line elevations across the site.

Floodplain mapping is used to identify areas that may be susceptible to flooding during large storm events. Floodplain mapping relies on field surveys, engineering analysis, and Hydrologic and Hydraulic modelling. Hydrologic modelling predicts how much stormwater will run off the land during a rainfall event. Flood Flows generated by the Hydrologic model are then input into the Hydraulic model, which routes these flood flows to predict the peak flood depth.

Unrestricted land development within a floodplain increases the risk of loss of life, personal injury, and property damage. Any site alterations for a proposed land development on or near a valley or bluff slope can aggravate existing erosion problems or create new erosion problems, and can also affect neighbouring properties by changing the physical characteristics of the valley or floodplain, or drainage to these properties.

Conservation authorities such as Nottawasaga Valley Conservation Authority(NVCA), and Grand River Conservation Authority (GRCA) require site-specific Hydraulic and Hydrologic modeling during the site plan approval process for land developments to ensure proposed land developments do not adversely affect flood flows, storage, or risk-to-life. A standard submission to the Conservation Authority often includes a topographic survey by an Ontario Land Surveyor (OLS), a Grading and Drainage Plan incorporating an Erosion/Sediment Control Plan, A Stormwater Management Design, Plan and Report, a Functional Servicing Report, and a Hydraulic/Hydrologic analysis.

Role of Flood Modelling in Site Plan Application
Our Licensed Professional Water Resources Engineers use Hydraulic and Hydrologic modelling to show that peak flows, water levels, and storage volumes will not negatively impact the property or surrounding areas. Conservation Authority and/or the municipality review the Hydraulic and Hydrologic modelling against provincial standards to regulate floodplain land use and ensure the proposed Land Development complies with the provincial natural hazard standards. Hydraulic and Hydrologic Modelling helps size infrastructure like swales, ponds, and oversized pipes to manage excess stormwater runoff safely.

Conservation Authority's one-dimensional and two-dimensional HEC-RAS models for the watersheds would not meet the requirements of the province for providing a site-specific floodplain limit and, as such, all inputs, such as flow rates, Manning’s “n” values, and overbank locations, into the models would be adjusted by our Licensed Professional Water Resources Engineers to meet the provincial requirements. As the accuracy of the topographic data for the Conservation Authority's hydraulic models is +/- 1 m, all cross-sections within a given development site must be based on a site-specific geodetic topographic survey completed by an Ontario Land Surveyor. Based on this geodetic topographic survey completed by an Ontario Land Surveyor, a correction factor for the datum related to the Conservation Authority's hydraulic model can be determined by our Licensed Professional Water Resources Engineers by comparing points on the survey with the appropriate Triangular Irregular Network (TIN) and determining the average error for a site.

The Conservation Authority reviews Site Plan Applications as per the Conservation Authority's delegated responsibility from the Province to represent provincial interests regarding natural hazards identified in Section 3.1 of the Provincial Planning Statement (PPS, 2024), as a regulatory authority under Ontario Regulation 41/24 and through the Conservation Authority's role as a public body under the Planning Act.

The Conservation Authority provides comments as per its Partnership and Service Agreement with the municipality and/or the Niagara Escarpment Commission.

Ontario Regulation 41/24
Any development within the regulated area due to the slope & meander erosion hazard, flood hazard, unevaluated and Provincially Evaluated wetlands will require a permit from the Conservation Authority under the Conservation Authorities Act.

Any proposed structures within the floodplain will need to be structurally designed to withstand hydrostatic pressures associated with flood depths and flood velocity and need to be flood-proofed with all minimum opening elevations elevated 0.3m above the Regulatory flooding hazard and all mechanical and electrical servicing 0.3m above the Estimated Regulatory flood elevation. Any works proposed within the 30m wetland interference buffer shall be completed in accordance with the Environmental Impact Assessment.

The Conservation Authority Approval Process
Existing Baseline 1D or 2D HEC-RAS Models for Watersheds:
Conservation Authorities often have baseline 1D or 2D HEC-RAS models for their watersheds. Through a data sharing agreement, our Licensed Professional Water Resources Engineers obtain elevation mass points as well as a portion of the Generic Regulations HEC-RAS hydraulic model and relevant engineered modelling (if available) associated with the property from the Conservation Authorities.
Site-Specific Updates and Modelling:
Our Licensed Professional Water Resources Engineers gather site topography using LiDAR or field surveys, infrastructure data culverts and bridges, soil types, and regional rainfall records, update the geometry of the Conservation Authority's baseline 1D or 2D HEC-RAS model for the watershed with precise site survey data and the proposed site alterations, and run the flood simulation.
Key Modelling Requirements
Topography:
High-accuracy LiDAR and on-the-ground cross-section surveys of channels and structures (bridges/culverts) are required.
Flow Inputs:
Peak flows are derived from regional storms like Hurricane Hazel or 100-year flood events.
1D vs. 2D Flow:
Simple channels use 1D models, while complex floodplains with wide spills require 2D or coupled 1D/2D HEC-RAS setups.
Regulatory Standard:
In Ontario, flooding models are typically tested against the Regulatory Flood Event—often based on the 100-year flood or historical worst-case storms like Hurricane Hazel (1954).

Flood Hazard Assessment:
Our Licensed Professional Water Resources Engineers need to demonstrate that the proposed land development will cause zero net increase in water surface elevation, no increase in upstream or downstream water levels, no loss of floodplain storage, no loss of critical flood storage volume on adjacent properties, and safe vehicular/pedestrian access. The completion of a flood hazard assessment does not guarantee approval of the proposed development.

Floodplain Analysis, Flood Assessment Brief, and Flood Hazard Study in Ontario identify and manage flood risks using engineering models, local watershed data, and provincial safety standards.
How Floodplain Analysis, Flood Assessment Brief, and Flood Hazard Study Work:
Data Collection: Qualified engineers gather weather records, streamflow measurements, land use details, and ground elevation surveys.
Hydrologic Modeling: Software calculates how much water runs off the land during major storms, such as a 100-year flood or historical events like Hurricane Hazel.
Hydraulic Modeling: Runoff estimates are routed through rivers and lakes to map peak water depths and high-risk boundaries.

CULVERT DESIGN
Based on the existing terrain derived from LiDAR data and the slope of the upstream catchment area, our Licensed Professional Water Resources Engineers identify critical intersections where culverts are required. These are further supported by roadside runoff collection ditches to manage surface water effectively. These culverts are specifically designed to handle the 100-year flood event, ensuring sufficient capacity to manage the flow effectively.

Preliminary Fluvial Geomorphology Assessment
Preliminary fluvial geomorphology assessment includes the following tasks:
• compilation and review of relevant background information including previously completed fluvial geomorphological reports
• desktop assessment of historical imagery and meander belt width analysis
• field visit (rapid assessments)
• identification of constraints and opportunities from a fluvial geomorphic perspective to inform the flood mitigation assessment
• recommendations for further analysis to be completed in subsequent project stages

Meander Belt Width
A meander belt width is delineated to characterize planform geometry and lateral extent of the channel; the meander belt is defined by tangential lines that are drawn along the outside bends of the laterally extreme meanders within the reach, following the meander axis. The Toronto and Region Conservation Authority (TRCA) delineation procedures (PARISH 2004) outline that when a watercourse has been previously altered from its natural planform and when the hydrologic regime of the watercourse has not been altered, the meander belt width should be based on the original unaltered configuration. Most of the time, as a result of both channel alterations and changes to the hydrologic regime, the meander belt width of the original channel planform would not be representative of current conditions.
A standalone Meander Belt Width Assessment generally ranges from $2,985⁺ʰˢᵗ to $6,985⁺ʰˢᵗ, whereas a broader fluvial geomorphological assessment can range from $4,975⁺ʰˢᵗ to over $14,950⁺ʰˢᵗ depending on site complexity. Meander Belt Width Assessments are typically conducted to satisfy municipal zoning or Conservation Authority requirements regarding the erosion hazards.

Fluvial Geomorphology Assessment and Erosion Hazard Delineation
The geomorphological and erosion hazard delineation assessment will, in part, inform the limits of development. The following activities were completed as part of the geomorphological and erosion hazard assessment:
• Review available background reports and mapping (e.g., watershed/subwatershed reporting, geology, and topography) related to channel form and function and controlling factors related to fluvial geomorphology
• Review recent and historical aerial photographs of the site to understand historical changes in channel form and function
• Delineate watercourse reaches based on a desktop assessment and field confirmation
• Conduct field reconnaissance using standard, industry-accepted tools such as the rapid geomorphic assessment (RGA) (MOE, 2003) and rapid stream assessment technique (RSAT) (Galli, 1996) to evaluate existing instream and riparian conditions (i.e., evidence of ongoing channel processes, active erosion/deposition, or potential channel instability)
• Delineate limits of the meander belt width/erosion hazard on a reach basis using the results of the desktop and field assessments

Most watercourses in southern Ontario have a natural tendency to develop and maintain a meandering planform, provided there are no spatial constraints. A meander belt width or erosion hazard assessment estimates the lateral extent that a meandering channel has historically occupied and will likely occupy in the future. This assessment is therefore useful for determining the potential hazard to proposed activities in the vicinity of a watercourse.

When defining the erosion hazard for a watercourse, Ministry of Natural Resources (MNR, 2002) guidelines treat unconfined and confined systems differently. Confined systems are those where the watercourse is contained within a defined valley, where valley wall contact is possible. In contrast, unconfined systems are those with poorly defined valleys or slopes well outside where the channel could realistically migrate. Unconfined systems are generally found within glaciated plains with flat or gently rolling topography. Partially confined systems are those where meander bends, or the channel, are adjacent to only one valley wall and the watercourse is therefore restricted in migration and floodplain occupation on one side of the valley system.

In unconfined systems, a meander belt width can be applied, at minimum, based on 20 times the bankfull channel width. Alternatively, the meander belt width can be determined through a detailed geomorphological study that examines the largest channel meanders observed through historical and recent aerial photograph interpretation. The meander belt width can then be graphically defined using orthorectified aerial imagery by determining the channel centerline and the channel’s central tendency (i.e., meander belt axis). In cases where the channel is not discernible in aerial photographs or the channel has been substantially modified, empirical models can be used to estimate the meander belt width.

The Ontario Ministry of Natural Resources (MNR) outlines an approach for establishing the erosion hazard where watercourses are confined by valley walls. This approach defines an appropriate erosion setback or toe erosion allowance from a channel bank where the creek is within 15 m of the toe of the valley slope. A toe erosion allowance can be determined in several ways: use of an average annual recession rate; application of a 15 m toe erosion allowance in areas where the channel is within 15 m of the toe of the slope; or use of soil information and field observations of geomorphic processes (MNR, 2002). In partially confined systems, a hybrid approach can be used to delineate the erosion hazard whereby an appropriate meander belt width is applied to unconfined portions of a given reach and where the channel is within 15 m of the valley toe, a toe erosion allowance and stable slope allowance are applied.

A standalone Fluvial Geomorphology Assessment and Erosion Hazard Delineation typically costs from $2,950⁺ʰˢᵗ to >$9,950⁺ʰˢᵗ for a small-to-mid-sized single-property development.

A standalone Fluvial Geomorphology Assessment and Erosion Hazard Delineation typically for a Small / Single-Property Site (e.g., local permit or single lot near a regulated stream) costs from $2,975⁺ʰˢᵗ to >$5,950⁺ʰˢᵗ. This usually covers a basic review, a brief site reconnaissance/rapid geomorphological assessment (RGA), and basic meander belt delineation to satisfy local Conservation Authority requirements.

A standalone Fluvial Geomorphology Assessment and Erosion Hazard Delineation typically for a Medium Development / Subwatershed / Multi-Reach Site (e.g., subdivision or commercial site plan) costs from $6,950⁺ʰˢᵗ to >$14,950⁺ʰˢᵗ. This includes extensive historical analysis, detailed instream measurements (bankfull dimensions, pebble counts), cross-sectional surveying, and coordination with the Conservation Authority.

A standalone Fluvial Geomorphology Assessment and Erosion Hazard Delineation typically for a Large Infrastructure / Municipal Class EA (Environmental Assessment) involving multiple stream crossings, long continuous reaches, comprehensive hydraulic/scour analyses, and public/agency consultation reports costs from $19,950⁺ʰˢᵗ to >$49,960⁺ʰˢᵗ

We prepare the following to the satisfaction of the Conservation Authority and municipality to support the Approval of Site Plan Applications:

Detailed Stormwater Management Report, which includes the following

The quantity and erosion control storm sewer/super pipes and orifice controls will be located above the adjacent watercourse 100-year water level
All storm outfall headwalls will be located outside of the vegetation protection zone of all key natural heritage and hydrologic features, where possible.
Detailed erosion and sediment control plans
Detailed grading and drainage plans;
Detailed Low Impact Development (LID) Evaluation demonstrating the means to maximize the use of low impact development measures consistent with Policy 1.6.6.7 of the Provincial Policy Statement;
Detailed cut/fill analysis for any grading proposed within the Regional Floodplain
Detailed delineation of the existing and proposed 100-year and Regional Floodplain demonstrating the location of all proposed development outside of the flood-susceptible area;
Conveyance Analysis to demonstrate conveyance of proposed flows to an appropriate outlet.
Hydraulic model flood elevation comparison table of the Existing Conservation Authority model versus the Proposed Conditions model
Detailed report addressing any dewatering requirements
Detailed phosphorus budget
Detailed Restoration/Mitigation Plan
Detailed Natural Channel Design based on geomorphic principles
Subwatershed Conformity Report

Floodplain cut and fill balance requires that any new soil or material placed in a flood hazard area (fill) is completely offset by an equal or greater volume of excavated soil removed from the same elevation slice (cut) to maintain zero net loss of flood storage capacity.

Under the Conservation Authorities Act and Ontario Regulation 41/24, the Conservation Authority enforces strict grading and storage rules:
• Volume Equivalence: Excavation volume (cut) must equal or exceed added material (fill) across corresponding elevation increments.
• Hydraulic Connection: Cut areas must connect directly to the active floodplain via unobstructed overland flow.
• No Negative Impacts: Hydrologic and hydraulic modeling (typically via HEC-RAS) must prove zero negative impacts on upstream or downstream water levels, velocities, or conveyance during events up to the 100-year or regulatory flood.
• Engineering Certification: Designs, volume calculations, and topographic plans must be stamped and certified by a qualified Professional Engineer.

EXISTING CONDITIONS PLAN REQUIREMENTS
Detailed plan view and cross-section contour/topographic drawing, at 0.5m increments, to scale showing existing conditions including floodplain location and ground elevations.
Property boundaries extending a minimum of 10m beyond the property.
Delineation of the top and bottom of any slopes, if applicable.
Existing ground features including tree lines, driveways and gravel pad limits.
Watercourses and waterbodies (where applicable) including centerline, top of bank, current water level, high water mark and flood elevation AND distance of feature to existing development.
Wetland limits (where applicable) AND distance of feature to existing development.
Footprint of all existing and proposed structures and septic systems, complete with finished floor elevations.
Ditches and drainage swales.
Culverts and drainage structures.
Other relevant features as they appear on the property.

PROPOSED PLAN REQUIREMENTS
1. Detailed plan view and cross-section drawings that clearly delineate all proposed cut and fill area(s).
Fill Plan Details
• Limits of all fill areas extending to the toe of slope.
• Delineation of top and bottom of any fill slopes including slope label (i.e. 3H:1V).
• Existing and proposed spot elevations and grades of the limits of fill (i.e. show matching at toe of slope).
• Minimum of one cross-section per fill area depicting original ground, proposed ground, regulatory flood elevation, and high-water level.
• Original and modified floodplain limits (to ensure hydraulic connectivity).
• A note on the type and source of all fill material.
• A note on how and when all new fill will be stabilized.
• Sediment control measures; and,
• Depending on the purpose of application, we may require:
i. Footprint and finished floor elevation of all proposed structures;
ii. Proposed spot elevations and grades around structure, limits of fill pads, and driveway surfaces;
iii. Delineation of septic systems including tanks, filter beds and mantles as well as associated grading details.

Cut Plan Details
• Limits of cut area extending from top of cut to tie in point with original ground (to ensure hydraulic connectivity)
• Delineation of top and bottom of cut slopes including slope label (i.e. 3H:1V)
• Existing and proposed spot elevations and grades over cut area
• Minimum of one cross section per cut depicting original ground, proposed ground, and flood elevation
• Original and modified floodplain limits
• A note or description of where cut material will be placed or disposed of
• Sediment control measures
• A note on how all exposed soils within the cut area will be stabilized

CUT AND FILL CALCULATIONS
Cut and fill calculations must include:
a. A detailed table of the volume of fill placed and cut below the floodplain elevation calculated in a maximum of 0.2 m intervals;
b. Cross-sections and contour maps;

Our typical fee for preparing the stamped engineering Existing Conditions Plan, Proposed Fill Plan, Proposed Cut Plan, and Cut and Fill Calculations is $2,985⁺ʰˢᵗ and, upon receipt of all the required information, may take 6 to 8 days to complete.

RETAINING WALL

Where slopes exceed 5%, our engineers utilize “terracing” for proper grading and drainage. Terracing includes 3 parts:

a) A grade of 2%-5% must be used around the building footprint for 5m horizontally (minimum)

b) Transition to 3H:1V for 5 m horizontally (maximum).

c) Alternate between parts a) and b) above until the existing elevation is reached.

The use of retaining walls shall be avoided, wherever possible. Retaining walls are generally required where a 3:1 slope cannot be achieved. Details of retaining walls over 0.90 m shall be submitted with the Grading Plans and stamped by a Professional Engineer for design and structural stability. A letter of Credit may be required for retaining walls over 0.9 m. Our engineers design retaining walls constructed from dry stone (interlocking, stacking type, no tiebacks) adjacent to public property. Construction materials of the retaining wall shall be acceptable to the Municipality. A 1.5 m high fence shall be required where a retaining wall height exceeds 0.9 m. In INFILL areas, retaining walls shall be constructed completely on the higher property, adjacent to the property line, and in such a manner as not to block the property line drainage. Retaining walls, in NEW Subdivision areas, shall be constructed completely on the lower property, adjacent to the property line. Drainage swale shall be constructed along the top and bottom of the retaining wall to divert flows to an acceptable outlet. Our fee for Structural Engineering Design of a Retaining Wall up to 2m high is $1,295⁺ʰˢᵗ.