Power: After the Floods

When people think of the Canadian Prairies, images of golden hued grasslands rolling endlessly into the horizon most likely come to mind. But on June 19, 2013, this peaceful vision changed forever when the prairie landscapes were over-swept with raging waters surging from every direction. This was the day that a significant portion of southern Alberta experienced one of the most disruptive storm events in Canadian history,

In the days leading up to the flooding, torrential rainfalls set in motion a catastrophe that resulted in lives lost, property and residences damaged, and billions of dollars of destruction. Dubbed “the costliest natural disaster in Canadian history,” the deluge forced hundreds of thousands of Albertans and businesses to flee their communities and seek refuge on higher, drier land. In a matter of days, over 350 millimetres of rain poured down, causing the city of Calgary, the towns of High River and Canmore, and nine other municipalities to declare a state of emergency.

The floods ravaged countless buildings, city blocks, and entire city subdivisions. As a result, many buildings were shut down or closed due to lack of access, and as safety precautions.

Electrical services were also interrupted to the majority of the larger buildings located within the flood affected areas. Either the equipment or hydro supply had been shut down by the flood waters, or it had been shut down manually as a precaution prior to flooding.

Effect on building power systems

Calgary’s downtown core was hit especially hard as many hydro service underground substation transformers were flooded, which affected multiple buildings. Also, most buildings have their main distribution equipment located at basement level, so the flooding affected their power and equipment.

As the high waters slowly subsided, buildings required assessment and planning for repairs. Damage was extensive, and consulting engineers were called in to help restore power and get the building systems back up and running. The components that required review included:

• Underground service conduits and ducts

• Power distribution equipment

• Emergency generators and equipment

• Receptacles and other power connections

• Mechanical equipment and connections

• Lighting on lower flooded levels and lighting

control equipment

• Life safety devices such as batteries,

remote heads, and exit signage

• Fire alarm systems and devices

• Communication services and equipment

• Security systems and equipment

• Audio visual equipment and devices.

One of the after-effects of the flood was damage to equipment from debris and contaminants in the flood water. As the waters crept higher, dirt and residue shifted and sewage began to back up in some areas, which introduced bacteria such as E. coli into the environment. Also, prolonged exposure to flood waters and humidity potentially affects the operation and lifespan of equipment due to corrosion and oxidation. Every one of these factors had to be taken into consideration during the building investigation process to ensure that all scenarios were reviewed, explored, and that any final decisions would assure safety for the building occupants.

Below are two projects where Williams Engineering Canada was involved in helping facilities to restore their power systems after the flooding.

The Calgary Zoo

The flood-ravaged Calgary Zoo relocated over 150 of its animals into temporary accommodations and several buildings were closed.

Consisting of two main sections, the zoo has a mainland northern zone and a southern island that is surrounded by river water. This island was flooded from all sides and the majority of it was covered with water, so the main power service to the island was shut down.

In order to expedite the repairs, public access was restricted, and it took nearly five months to fully reopen the park. Significant water damage had occurred to electrical, plumbing, and various support systems in the facilities.

Williams Engineering Canada was involved in the investigation of 11 buildings that required their equipment replaced, including the animal shelter, cafeterias and eateries, gathering places, information centres, interactive displays, offices and meeting rooms.

To accommodate the many buildings, phased repairs, and available staff, a systematic approach coordinated with the Calgary Zoo was applied to each area and facility. The work consisted of investigating every building to assess how the flood affected it overall, followed by a review of each system and its components to establish what required replacement.

High River Field House

The Field House in the town of High River is an addition to an existing recreation centre. The building was in the initial construction stages and minimal electrical work was completed prior to the flood.

Damage to the expansion was fairly minor, but it included flooding in empty underground conduits and a partially submerged main switchboard. The conduits could be drained and no major switchboard components were submerged, which ensured that they could be cleaned and reused.

Unfortunately, additional damage occurred to the portable storage bays that contained all the uninstalled components. Water filled the storage containers to a depth of approximately 150 millimetres, which resulted in humidity and condensation. Passive components and sealed devices could be cleaned and used, but submerged devices required replacement. In addition, a few site luminaires were carried away by the flood waters. The damages were minimal in cost, but the project schedule was affected.

Preventing flood damage in the future?

We cannot perfectly predict the impact or possibility of a natural disaster, but we can plan for and consider longterm solutions that may mitigate the risk of damage should a comparable flood inflict havoc on Canada’s prairie provinces ever again. A few options are being examined.

As an engineering firm, we can consider relocating major equipment, which is now typically located in building basement and arcade levels, to locations above ground. However, this option may not be desirable as it would mean occupying potential revenue-earning lease space.

We can also ensure adequate pumping equipment is installed to remove any excess water, which can eliminate or reduce localized flooding. This solution, however, can only provide limited support as water will typically be pumped back into the sewers, which may back up during larger flooding events and possibly cycle back into the building.

“Tanking” the rooms would require building a sealed room or enclosure that has access from the top of the room. Flood water would only fill this area once the level had reached the top access hatch. The downside is that this scenario would create difficulties when installing or replacing major equipment.

Redundant systems, which are split and located in different areas and pathways of the building, will secure the operation of at least part of the building during an emergency.

The above solutions are not ideal, as they introduce some combination of larger space requirements, higher costs, or scheduling issues. Still, they are options that should be considered to reduce a building’s exposure to flood water damage.

The Alberta flood of 2013 will continue to have long-term impacts for many residents, but communities are pulling together, and we are on the road to recovery. Nearly eight months after the waters receded, the rebuilding continues, and Williams Engineering Canada is proud to be providing engineering support to help bring life back to these communities.cce

Lana Winterfield is the communications advisor for Williams Engineering Canada, whose head office is in Edmonton, Alberta.

Editor’s note. Beside
s Williams Engineering Canada, many other consulting engineering firms have been involved in the clean-up efforts in southern Alberta, which involved a wide range of work including civil engineering assessments and remediation of bridges, water treatment plants, etc. The firms, including Williams Engineering, did some of this work pro bono.