Saunders Lake Stormwater Impact Evaluation

Leduc County, AB

Altalink is interested in constructing a new substation in close proximity to Saunders Lake near the City of Leduc. Before proceeding with construction, they selected three possible sites and engaged ISL to complete a Phase 1 Stormwater Impact Evaluation to determine what stormwater impacts might result from each of the three sites.

Document Review

To produce the high level document needed to evaluate each site, ISL reviewed all the regional and local stormwater management guidelines and plans, including the delineation of catchment areas and the site grading standards. We also conducted a detailed assessment of pre- and post-development release rates, downstream impacts and surface flow data.


Using this information, our team created a detailed surface model, and each scenario for each site was evaluated using XP-SWMM (2D Add-on) software. Peak site discharge rates were applied downstream of each potential site for multiple flowpaths.

Regulatory Approvals

Many high-level conversations were conducted with Alberta Environment in order to be proactive in terms of the stormwater management process and the level of regulatory risk outside of local municipalities.

Final Report

A Stormwater Management Report was compiled for Altalink's use. The report offered an unbiased presentation of potential stormwater impacts for each site, as well as recommendations and suggestions for discussion when selecting the final construction site. The report will act as a baseline for mitigation recommendations once the site has been chosen.

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Okotoks Stormwater Master Plan

Okotoks, AB

The Town of Okotoks has been experiencing a high level of growth and expansion, as well as some recent flooding issues. ISL was commissioned to develop a comprehensive Stormwater Management Master Plan and Flood Mitigation Plan.

Project Goals

The project was undertaken to define the existing stormwater system capacity, to catalogue possible upgrades and to review the system's operational strategies. The study was also intended to define future drainage planning goals in the undeveloped areas of the Town and create a single point of reference for stormwater planning.

LID Integration

The Town of Okotoks wanted the Master Plan to include the integration of low impact development stormwater management features and other sustainable solutions. To meet this criteria, the Master Plan ensures that sustainable stormwater infrastructure will be integrated with natural ecosystems and resident-friendly park spaces to optimize water quality prior to discharge to Sheep River.


For each possible upgrading scenario, improved system performance needed to be demonstrable, so ISL used state-of-the-art hydrodynamic modelling software (XP-SWMM) to individually evaluate and model each upgrading scenario.

Study Results

ISL compiled and reviewed existing reports and drainage system information, then used this information to conduct an analysis of the capacity of the existing stormwater infrastructure to identify the flooding issues. We also completed an assessment of the required upgrades and prepared preliminary cost estimates.

Master Plan

In November 2014, the Town was given operational strategies to prevent property damage in the event of flooding and guiding policies for sustainable and low impact development measures for retrofit and future incorporation.

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North LRT Extension: Storm Drainage

Edmonton, AB

ISL partnered with AECOM and Stantec as part of the design team tasked with building a 3.1km northwest-bound Light Rail Transit (LRT) extension from Churchill Station in downtown Edmonton to new LRT stations at MacEwan University, the Royal Alexandra Hospital and NAIT.

Project Design

The first three phases of the project design included Concept Planning, Preliminary Engineering and Detailed Design. ISL was responsible for leading the roadways, storm drainage and landscape architecture components of this massive project.

Drainage Scope

In terms of drainage, ISL provided the design of minor drainage system improvements, major drainage system and stormwater management facilities built to accommodate a 1:100 year rainfall event, track drainage alternatives and a portal drainage capture-and-conveyance system at the opening of the LRT tunnel.

Double Barrel Conflict

One of the most complex challenges came when trying to resolve the conflict of an existing double-barrel sewer pipe with the proposed LRT tunnel turning northward of downtown. This large sewer pipe was a major component of the downtown sewer system that serviced both sanitary/combined and storm flows. This conflict was ultimately resolved prior to tunnel construction.

LRT Improvements

When opened, the new LRT extension will improve accessibility for thousands of citizens, students, professionals and visitors to key centres of commerce, education, public health and entertainment.

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Blatchford Area Redevelopment Master Plan

Edmonton, AB

The City of Edmonton is seeking to transform the former municipal airport lands north of downtown into a world-class sustainable, transit-oriented and mixed-use development for 30,000 residents. Perkins + Will led the initial planning work for the 217-hectare redevelopment and retained ISL for civil works and land use planning.

Area Redevelopment Master Plan

ISL prepared the Area Redevelopment Master Plan (ARMP) for sewer and drainage services, including a Hydraulic Network Analysis for potable water services. The ARMP responds to the City's goals for zero discharge (both sanitary and storm), groundwater recharge, stormwater reuse and stormwater Low Impact Development and Best Management Practices for water treatment.

Stormwater Wetland

This ambitious plan envisions a six hectare stormwater wetland system for treating water on site for reuse in irrigation. This proposed wetland would store and treat stormwater volumes during typical rainfall years, while a piped outfall would handle larger volumes of stormwater during wet years. This whole system would tie into infrastructure for stormwater reuse in landscape irrigation.

Wastewater Treatment

The Master Plan also introduced the possibility of an onsite wastewater treatment facility to treat a portion of the wastewater generated by the development. A separated pipe system would allow for wastewater reuse in toilet flushing, for example.

Award Winner

The project design submitted by Perkins + Will won a 2014 National Urban Design Award from the Royal Architectural Institute of Canada (RAIC) as well as a 2014 GLOBE Award for Environmental Excellence in Urban Sustainability.

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Stony Industrial West Integrated Stormwater Management and Wetland Preservation Concept

Edmonton, AB

ISL partnered with Fiera Biological Consulting to develop the stormwater management component of a Neighbourhood Design Report (NDR) for a proposed 112 ha industrial subdivision and natural wetland in the Stony Industrial area in west Edmonton.

Site Optimization Approach

The team designed a unique integrated flood management system that used the available storage capacity in the natural wetland to reduce the land required for the adjacent stormwater management facilities (SWMF), making more land available for development.

Real Time Control System

Since the development will discharge into the City’s Quesnell Storm Trunk System, which is at capacity during storms, a Real Time Control System is required. This ensures discharge is zero during large events, resulting in additional storage capacity for the proposed development.

Integrated Stormwater Management Design

An integrated stormwater management design provided separate stormwater management functions within the SWMF cells for small events but flooded out the SWMF cells and adjacent natural wetland for large, infrequent flood events (i.e. larger than a 1:2 year flood).

Understanding Wetland Water Fluctuation

To understand how the water levels in the natural wetland normally fluctuate, we used a computer simulation model calibration exercise to replicate water levels observed in historic air photos and concluded that high groundwater infiltration was occurring.

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