A one-of-a-kind water feature is a collaborative success

by jason_cramp | March 3, 2016 9:30 am

By David Bergstrome

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Acapulco Pools, a commercial pool builder and service provider based in Kitchener, Ont., has worked with Dan Euser Waterarchitecture (DEW) several times over the years and have come to know his water feature designs, which are typically well-suited to the location, reflect functional expectations, and by no means ‘run of the mill.’ In addition to the hauntingly dramatic National September 11 Memorial water features in Manhattan, N.Y., Euser has produced dozens of unique water effect designs all over the world. Despite knowing this, Acapulco Pools did not expect him to say he was designing a “one-off” project called the ‘Weather Catcher’ to be built in Ft. McMurray, Alta., at the Jubilee Centre of the Regional Municipality of Wood Buffalo. The water feature was part of a larger reurbanization project that included new municipal-use spaces, a café, and an open-air plaza designed with a large moving sculptural stage that would also act as a gathering place for residents in the city.

The Weather Catcher is a unique above-grade stainless steel structure/water feature that was conceived by Marc Ryan and Adam Nicklin, principles of Public Work, a Toronto-based urban design and landscape architecture studio. DEW, as a sub-consultant, was responsible for the development of feasible and effective water feature effects that would complement the overall project design. In turn, Euser recommended Acapulco Pools as the provider of the mechanical and electrical systems for the project.capulco Pools, a commercial pool builder and service provider based in Kitchener, Ont., has worked with Dan Euser Waterarchitecture (DEW) several times over the years and have come to know his water feature designs, which are typically well-suited to the location, reflect functional expectations, and by no means ‘run of the mill.’ In addition to the hauntingly dramatic National September 11 Memorial water features in Manhattan, N.Y., Euser has produced dozens of unique water effect designs all over the world. Despite knowing this, Acapulco Pools did not expect him to say he was designing a “one-off” project called the ‘Weather Catcher’ to be built in Ft. McMurray, Alta., at the Jubilee Centre of the Regional Municipality of Wood Buffalo. The water feature was part of a larger reurbanization project that included new municipal-use spaces, a café, and an open-air plaza designed with a large moving sculptural stage that would also act as a gathering place for residents in the city.

Due diligence

Prior to its installation, Acapulco Pools met with DEW at their workshop and design offices in Toronto to discuss and learn more about the project, as well as to see where they could help.

Similar to his other projects, Euser built a mock-up of the water feature behind his workshop to test the various effects he was looking for, and to present them to the landscape architect and the City of Ft. McMurray. During this meeting, Acapulco Pools reviewed the photographs of the mock-up and talked about the water feature’s different effects and other important considerations.

By the time Acapulco was approached about the project, the rest of the team’s consultants had already been established, with Paul Hobern of PCL Construction Management Inc., acting as the construction manager. The structural engineering for the project was provided by Mott MacDonald Engineering, which was a critical aspect to the project’s success, as it was important to maintain the architectural vision of the water feature, while ensuring its structural integrity in its ability to handle loads imposed by wind, as well as the weight of the accumulated ice, which would be created by the water feature over the course of the winter.

To complicate this, the structure would need many openings to house the various water feature components as well as to allow the plumbing and electrical to be routed within the interior of the structure in the most discrete way possible.

The stainless steel structure was fabricated by Mariani Metal, which has produced various metal works of art, structures, and monuments all over the world. In addition to handling the mechanical and electrical systems for the structure, Acapulco Pools worked closely with the other consultants on the team, including sub-consultants Culligan Water and Atomizing Systems Inc.

Water feature elements

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The essence of the water feature, which is 7.5 m (24.6 ft) long, 1.5 m (4.9 ft) wide, and 18.75 m (61.5 ft) tall, is its 316 stainless structural steel (HSS) construction. After it was fabricated, the entire structure was bead blasted to provide a matte finish.

The water feature produces rain, fog, and icicles—big icicles. A self-contained system, provided by Atomizing Systems, controls the three water elements: fog, which operates year-round; ice system, which only runs in the winter; and rain system, which only operates in the summer.

In a fog

The fog system comprises 24 manifolds each with 10 fog nozzles. DEW, together with Public Work, strategically placed the manifolds throughout various levels of the structure for maximum effect.

Right as rain

The rain system has six manifolds grouped in three sets of two. The two centre manifolds were placed at a higher level (approximately 10.5 m [34.4 ft]), while the mid-level manifold is offset from centre, and the lower manifold is offset further to produce a tri-level rainfall across the entire length of the water feature. The rain system only operates during warmer temperatures and produces a unique visual effect along with tranquil sounds.

As cold as ice

The ice system also radiates from the centre of the water feature to form five rows of icicles. Each row has several stainless steel cables that act as a substrate upon which the icicles ‘grow.’ There are a total of 89 icicles that vary in length and diameter depending on weather conditions. Some icicles can grow up to 305 mm (12 in.) in diameter near the top and reach an approximate length of 9.1 m (30 ft).

At strategic points adjacent to the fog manifolds, stainless steel grids made of small dimension square stock, were installed to collect the ice crystals that are produced by the system in the winter.

Rise to the challenge

There were certain challenges associated with the project that were obvious, such as operating the water feature during the winter in Ft. McMurray, while others, such as not knowing what would happen if the power went out in the middle of February, not so much. The following challenges were more subtle; however, and as such they were not immediately apparent.

Finishing first

The winter operating systems (fog and ice) needed to be heat traced and insulated with ethylene propylene diene monomer (EPDM) insulation and the installation of the mechanical and electrical systems within the structure needed to be completed before it left Ontario, but only after the structure received its bead-blasted finish.

To make this happen, each system needed to be dry-fitted before the bead blasting was performed; there could be no changes to the structure in the form of access holes or supports after the fact. If the systems could not be installed properly after the bead blasting, it would be a major problem.

Inaccessible access holes

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Some of the connections were relatively straightforward. For instance, each of the ice system manifolds were served by a single-braided hose with no branch connections, as the feedlines ascended up and through the structure. On the other hand, the fog and rain systems were a different story, as each has several branches from the feedline to the individual manifold branches. To put this into perspective, the high pressure fog system has 24 branches.

As the feedlines branch away from the vertical columns, the plumbing was fed through small access holes, which were limited in size due to structural requirements. If they were made too big, the structure would not be able to withstand the lateral forces of the wind, not to mention other loads. The location of the access holes were also critical, as each one had to be positioned well back from the structural steel’s vertical-to-horizontal connections to ensure the integrity of the structure was not compromised.

This made Acapulco Pools’ job of connecting the horizontal plumbing branches to the vertical feedlines quite difficult, as it was impossible to reach the connection point by hand. Therefore, to manage this, Atomizing Systems developed special, quick-release tools designed specifically for use on the structure. However, before these tools could be developed, Acapulco Pools shipped a mock-up of the structural interface to Atomizing Systems’ offices in New Jersey with the proposed access holes in place to assist in manufacturing the tools.

Once they were developed, Acapulco Pools’ technicians were able to make the final branch connections to the main feedlines. If a leak were to occur after the structure was erected, it would be disastrous. Finding the problematic fitting among dozens of other connections that are all wrapped with heat tracing and encased in insulation would be impossible. As a result, the entire feedline would need to be removed to repair a leak.

Therefore, to reduce the likelihood of a leak after installation, the entire feedline for each system—and all of its branches—were pre-assembled and pressure tested at 6895 kPa (1000 psi) at Acapulco Pools’ project support centre before the Weather Catcher was installed.

It was also important the preassembly accounted for the physical orientation of each and every fitting. The lengths of heat tracing required for each horizontal branch also had to be predetermined and installed as part of the preassembly to avoid an excessive number of electrical splices in the heat trace. Every splice is a potential electrical failure and an opportunity for water to enter the watertight splice connection.

Water quality

The quality of the water used by the Weather Catcher was also critical. That said, water with low-mineral content (total dissolved solids [TDS]) is required so there is no build-up in the small, non-wearing ruby-orifice fog nozzles. Given the sensitivity of the nozzles, it was important to maintain nearly hospital-clean conditions during the assembly to prevent any contamination from entering the plumbing. Further, any minerals in the water would also need to be removed to prevent the formation of unsightly scale or rust on the structure. To manage this, DEW specified a water treatment system that included a commercial quality water-softening system, reverse osmosis (RO) filter, ultraviolet light (UV) sanitizer, along with a holding/buffer tank system. A booster pump was also included as part of the water treatment system to provide the appropriate water volume and pressure to serve all three systems.

When the feature is not operating, or when only a portion of the available treated water is required, a pressure relief valve returns the excess water to the holding tank where it is continuously recirculated, treated, and ready for use by the next feature cycle.

Weather permitting

It was clear there would be certain weather conditions when it would be inappropriate to operate the Weather Catcher’s systems. For instance, if wind speeds are quite high, or when it is extremely cold, it may not be appropriate to run any of the systems that day. However, when wind speeds are more moderate, it might be good to run lower levels of rain, and exclude the high levels. Similarly, when the temperature drops toward zero, the rain feature must not be operated, but the ice system should run.

The Weather Catcher is able to automate the operation of the three features thanks to a weather station installed discretely at the top of the structure. It collects and sends current weather information to an automation system, programmed by Atomizing Systems, to interpret and control the three systems according to fixed and adjustable parameters that were designed into the automation software.

Operators are also able to turn the Weather Catcher’s systems on/off at certain times of day, depending on variables such as wind speeds and directions, etc. Some parameters, however, are fixed to protect the system. For instance, if it is -40 C, an operator cannot override the system to turn it on. The programming parameters, set points, and current status of the system are all accessed through a touch screen human-machine interface (HMI) installed in an ergonomically sound way in the equipment room. The automation system also generates alarms if something is wrong (e.g. low water pressure from the water treatment system).

Under pressure

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To produce the desired effect, the fog system operates at approximately 6895 kPa (1000 psi); therefore, the plumbing had to withstand this type of pressure. In this regard, only stainless steel braided hose rated for 17,236 kPa (2500 psi) and compression fittings with a pressure rating of 41,368 kPa (6000 psi) were used.

During the winter, when the ice system is operable, a significant amount of ice forms on the drip cables, which eventually comes crashing down to the base of the structure where all of the plumbing and lights are located. In fact, this happens every time a natural thaw event occurs. Therefore, to manage the falling ice, a grid was provided by the steel fabricator to break it up into smaller, less damaging pieces, while a special stainless steel-covered trough was constructed to protect the plumbing in the base of the water feature.

All of the braided hose used to plumb the water feature had to be ordered to exact lengths with adjustable ridged portions so it could be routed in an organized fashion to fit the troughs. They also had to be protected from chaffing within the structure, so Mariani Metal put a small radius on every opening the hoses pass through. Further, every valve and fitting had to be stainless steel to resist the aggressive nature of the reverse osmosis treated water.

Power down

Another major concern was figuring out how to protect the plumbing from freezing in the event of a power failure, as no backup generator was in the plan and draining the plumbing was complicated for a number of reasons. First, the elevation of the pit where the plumbing enters the Weather Catcher is lower than the equipment room. Therefore, it was not possible to simply let the water drain to the heated equipment area, as it would get trapped in the low spot at the base of the feature. Second, the individual nozzles for the fog and ice systems acted like check valves that could prevent the water from draining out of the plumbing system in a timely manner.

Therefore, three things were done to manage these challenges. First, a compressed air purge system, which can be controlled by the automation system, was incorporated into the design to evacuate the plumbing whenever a system shutdown occurred. For example, if the temperature were to drop toward 0 C (32 F), the rain system is stopped and high-pressure air, delivered through a solenoid valve, forces water out of the system. Instead of relying entirely on the purge system, a redundant system was also installed to ensure all of the water is removed.

This secondary system comprises a ‘solenoid dump box,’ designed collaboratively with Atomizing Systems, which allows the plumbing lines in the water feature, as well as the lines between the equipment room and the low point, to drain completely.

The solenoids have 120V coils to avoid any low-voltage drop, and are normally open (energized to close) so if there is a power failure, the valves would fail to the open position, allowing the system to drain. The fog system was one exception to this in that a normally closed valve had to be used in the dump box because of the pressure involved. So in the event of a power failure, this valve would remain closed and could potentially trap water. As a failsafe, a normally open valve was installed in the air-feed line to the fog purge system. If the power is unexpectedly lost, this air valve fails open and delivers the entire contents of the compressed air system to the fog system to remove all water.

Resolving one problem leads to another

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Although the compressed air system resolved one problem, it created another. The ice drip manifolds comprise several low-volume nozzles that are extended to make contact with the stainless steel ‘substrate’ cables (as described earlier) using small 6.35-mm (0.25-in.) poly tubing. This system worked great until it went through a compressed air purge cycle, as surges—created by the intermittent flow of water and air—dislodged the tube extensions from touching the cables. In fact, this was quite disruptive to the system as a significant number of interfaces between the nozzle and cable were lost after each purge cycle.

As it turned out, the resolution to this dilemma was quite simple. To prevent the tube extensions from being dislodged, they were merely anchored using stainless steel aircraft safety wire by twisting it around the cable and inserting it into the poly tubing. When the surging air and water tries to move the tubing around, the wire insert anchors the tubing in place.

The heat is on

Heat tracing was required because the water velocity in the system is so low it could potentially freeze at low temperatures even though it is moving. The status of the heat tracing system also needed to be known for decision-making purposes. For instance, if the heat trace is not working, the water should not be turned on.

Current transformers were added to the design and installed on each heat trace branch to constantly measure the current flow to the heat tracing for each system. If the current drops below a baseline level, the system will not run and an alarm is sent to the HMI as well as operator tablets, which can be used to control and monitor the Weather Catcher remotely. If the heat trace fails during operation, the system automatically shuts down and generates a purge cycle of the affected system. After the purge cycle is complete, the ‘dump’ solenoids in the pit open, and remain open until the issue is corrected.

Delivering the goods

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The Weather Catcher was built in Ontario and installed in Alberta; however, the logistics of transporting the structure made the project much more challenging, as it was too large to ship as a single unit. Thus, Mariani Metal built it in two pieces. However, this meant the plumbing, heat trace, and insulation had to be designed and installed in such a way that the interconnections between the two halves were not only mechanically and electrically reliable, but also minimized the need for lifting devices and temporary platforms within the structure. Further, as Acapulco Pools’ work was being installed inside the finished product, its technicians had to wear latex gloves and boot protectors to prevent surface contamination of the special stainless finish.

When all was said and done, the Weather Catcher is unique to the City of Ft. McMurray, Alta. On hot summer days, the high-pressure fog drifts hauntingly toward the ground creating a cooling effect, while the rain is visually and audibly enchanting.

The Weather Catcher is a living sculpture in a state of constant change depending on the influences of wind speed, direction, temperature, relative humidity, and ambient light. Icicle and fog crystal formations that are observed on one day are seen that day only. The following day, and every day thereafter, visitors will see an entirely different array of ice, water, sound, and light.

[7]David Bergstrome, is a business development/special projects consultant with Acapulco Pools in Kitchener, Ont. In this position, he pursues business development opportunities as well as provides technical advisory and assistance on special projects. Bergstrome has 25 years’ experience in processes and project management/consultation, and 15 years’ experience in the aquatics industry. He can be reached via e-mail at dbergstrome@acapulcopools.com[8].

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