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Calgary Zoo 2013

Project profile of an IDSO Consulting Services managed drying plan and drying documentation.

Called a “500 Year Flood”, the city of Calgary, Alberta Canada and outlying areas suffered from catastrophic flooding that carried silt and drainage contaminants into the built environment. An obviously cherished city landmark is the Calgary Zoo with its dozens of beautifully designed buildings and acres of sculptured landscape.

Ranked among North America’s top ten zoos and boasting 1,000 animals from about 275 species, the buildings on the property were severely damaged by the flooding. The life and health of all who would occupy the more than three dozen buildings ranging in size from 400 to more than 20,000 square feet with some ceiling heights in excess of 80 feet were potentially endangered. Once this risk was acknowledged by all involved, the restoration protocol became apparent: access and remove all absorbent materials and expose the breached structural cavities followed by a thorough washing and decontamination protocol prior to drying efforts. The very definition of “mitigation” is to manage risk. 

Hundreds of temporary help workers were utilized to remove the absorbent materials and shovel the debris out of the buildings. Safety protocols were defined and strictly enforced upon all who worked on the property by qualified, third party health and safety officers; an earmark of a competently managed project.

It was quickly realized that the structures would not have any electrical power for many weeks and were therefore incapable of self-sustaining responsible atmospheric conditions. Sufficient temporary power was brought in necessary for each building to power responsible temporary atmospheric control devices.

Objectives

The humidity control and restoration strategy was segregated into three phases:

1. Pre-Restorative Drying Stabilization Phase
2. Restorative Drying Phase
3. Post Restorative Drying Stabilization Phase

   

It was important to acknowledge the difference in the objective of each phase. For this project, the first and third phase had the distinct objective of maintaining an atmospheric condition of less than 50% relative humidity so as to diminish the possibility of secondary damages that would inflate the monetary cost of the loss. Following the emergency controlled deconstruction and initial sanitizing of the structure, the second phase had the distinct objective of producing an adequate and responsible delta vapor pressure necessary to responsibly dry the remaining materials. This delta vapor pressure was predetermined prior to the execution of Phase Two, and became the drying plan against which the drying strategy was measured. By segregating these phases, the paying parties and third party auditors would understand that the equipment use was not strictly a “drying effort”. Their usage was dictated by an adherence to a predetermined plan. Equipment type and quantity was modified as each phase was executed.

While carpeted areas were quickly scheduled for carpet removal, the hardwood, VC tile, slate and ceramic tile required a careful consideration for salvage potential. It was determined early in the process that the contamination had become trapped below these flooring surfaces and therefore, they too were scheduled for removal. Powerful flooring removal devices were brought in to not only remove the mortar beds into which the tiles were set, but also the adhesives used in the carpet installation process. If the concrete slabs were not exposed, the drying efforts would have been severely impeded thus delaying the ability to replace the flooring materials. This process took the better part of about 10 to 14 days… and a lot of sweat from some very dedicated, hard workers.

Federally regulated materials like asbestos and lead were found in several buildings. This complication required qualified individuals to be brought in to assist in the process.

Unique Challenges

Many of the buildings presented unique challenges for the restorative drying expert. Interior gardens of rare plants, structural embellishments of rare woods, classrooms with real animal biology training devices, heavens… even live, exotic animals were potentially exposed to the drying chambers!  Drying experts regularly work with these nuances on a case by case basis and relish the challenge.

One such case was a favorite exhibit of many who visit the Calgary Zoo:

The Butterfly Room

A lush garden and center pond comes to life with dozens of rare, intensely colorful and flamboyant butterflies that inspire visitors with a sense of awe and serenity. The slate tile floor was removed and the concrete slab required drying prior to tile replacement. However, the room possessed a normal relative humidity of between 60% and 80%. The butterflies and the plants could not be relocated, so the concrete slab needed to be isolated from the ambient conditions with a tenting process.

While it is easy enough to inflate a tent in the room, it was necessary to evacuate the air from under the tent so that it wouldn’t seep into the butterfly’s atmosphere. This was accomplished by extending the tent to an open window on the opposite end through which the air could ventilate.

As it turned out, the butterflies only have a lifespan of a few weeks and perished naturally. However the efforts taken by the technicians to preserve the zoo’s living assets were vocally praised and appreciated.

Safari Building

Another structure included the use of timber imported from Africa. While this wood was not found in large quantities within the building, its function and beauty was an important element of the building’s superstructure.

Exposed roof trusses were made of large African wood beams assembled with strong gussets plates. The rich tone of the wood is effectively reminds the visitor of the African safari. These beams were embellished with a Plexiglas type mirror that reflected and emphasized their presence. Phase Two (drying phase) is the intentionally engineered creation of a low atmospheric vapor pressure in conjunction with the wet materials being responsibly warmed.

An obvious focus was placed upon the efforts to dry the concrete slab upon which the building was erected and wood / tile flooring materials were placed. The African trusses would surely be affected by the dry atmospheric conditions – but that didn’t seem to be too much of a concern. After all, they’re from Africa – and it is pretty dry there!

On the seventh day of Phase Two (the drying phase), it was reported that “the mirrors were falling from the roof trusses”. Yikes!

The area was quarantined until the cause could be determined. Speculations surrounding the temperatures in the building causing a failure in the mirror adhesives or even melting the Plexiglas type mirrors were alleged. However, the thermal conditions in the building never rose to temperatures that could support such assertions. At no time did the temperatures exceed 91°F with the desiccant dehumidifiers being used. But the environmental conditions indeed possessed and incredibly low vapor pressure and thus a very low relative humidity.

The cause of the mirror breakage became apparent when we referenced the US Department of Forestry’s wood equilibrium moisture content table. The anticipated “normal wood EMC” in the building was approximately 7% to 8%. The drying strategy we employed produced an atmospheric condition that would produce a wood moisture content of 2% or 3%.

We all know that timber will change dimensionally (shrink) when its moisture content diminishes below approximately 30% MC. Indeed, we were shrinking the wood trusses causing the mirrors to no longer “fit” into the truss framework. Snap!

The Plexiglas product was not a high ticket item and they were verified to be adequately fastened to the trusses. The risk was documented and abated and the last few days of drying were completed. However, we were firmly nudged with the reminder that our drying strategies can produce surprising consequences for which we shall be held accountable. We tend to “look down” when evaluating our drying processes, and every once in a while, we might get a surprising reminder that we are modifying all materials within the drying chamber.

Lesson learned!

Drying Documentation

This was the kind of job that most restorative drying professionals relish. The unique challenges at the Calgary Zoo made every day both engaging and rewarding.