Benefiting important habitat and local wildlife across Ontario

Assessing dam safety: overcoming challenges in remote and outdated Data environments

The objective was to classify the condition and potential hazards of the dams at each site, and then perform large-scale analysis through the coordination of multiple departments to conduct field and desktop investigations.

One of the biggest challenges was having outdated information. We had scans of the original plans made in the 1970s and 1980s, which made it difficult to coordinate geodetic elevation reviews due to the discrepancies with updated data. For some sites, the information available was extremely limited or not applicable to the sites.

Site accessibility was also a challenge, due to the remote locations of the wetlands, or if access roads and foot trails were damaged or overgrown with vegetation.

Getting to know wetlands better.

Egis undertook both field investigations and desktop studies for each of the 250 wetlands across Ontario. During the field investigation phase, our team gathered data for the wetland characteristics, including the type of outlet control, dimensions and condition of each outlet control structure, condition of the dam/dyke, and areas of erosion and/or rodent damage.

Egis reviewed the site access given the remote nature of a number of these sites, including the accessibility of each structure for maintenance, laydown areas, brushing, and additional temporary works including new access roads and culverts and was regularly in contact with the landowners, obtaining permission to enter at all 250 sites and in a number of cases, accompanying the landowners on the site visit for them to gain a better understanding of their infrastructure.

Managing the risk of dam bursts.

We conducted a high-level assessment to determine which wetlands have little to no impact on the downstream surroundings in the case of a dam breach and which required further investigation to confirm their Hazard Potential Classification (HPC).

Due to the project’s large scale, multiple team members participated in this stage to increase the efficiency and provide an additional level of internal review, quality control, and quality assurance. Four impact categories, including life safety, property losses, environmental losses, and cultural-built heritage losses could be classified as having either a low, moderate, high, or very high hazard potential.

Each dam was analyzed using engineering judgement to determine the overall impacts, level of destruction, and the potential costs of repairs warranted if each dam were to fail. Any wetlands with concerning impacts were flagged for further analysis.

Taking care of wetland habitats.

For each downstream feature where concerning impacts were identified, the peak flow rates of water leaving the wetlands were calculated under normal weather conditions (assumed dam breach in the summer months, not coinciding with a storm event) and flooding conditions (assumed that the dam breach coincided with a 100-year storm event).

We compared the results to the criteria set out for each category to determine the final HPC for these wetlands, which was provided to Ducks Unlimited.

The HPC confirmations, the condition assessments, and the cost estimates will enable Ducks Unlimited to efficiently allocate funds where they are needed most and allow their staff to spend more of their time doing what they do best – conserving, restoring, and managing wetland habitats across North America.

Benefiting important habitat and local wildlife across Ontario.

Client

Timeline

Environmental benefit

Awards

Community impact.

The challenge.

Assessing dam safety: overcoming challenges in remote and outdated Data environments

Imagine.

Getting to know wetlands better.

Create.

Managing the risk of dam bursts.

Achieve.

Taking care of wetland habitats.