Trimble - Transforming the way the world works.

The $50 million 10-acre Asian Tropics conservation center exhibit at the Denver Zoo in Denver, CO, will be one of the most advanced, sustainable zoo habitats in the world, featuring the magnificent Asian elephant.

The exhibit will include multiple ponds, an extensive life-support network, a water treatment plant, and nine different habitats and facilities. That is, assuming approximately 11,000 feet of complex animal life-support plumbing, piping and mechanical systems can be located, fabricated and installed below ground. Enter BIM.

Pioneers of progress

Heating and Plumbing Engineers (HPE) was contracted to model, coordinate, fabricate and install the plumbing, piping and HVAC systems. The owner also tasked the firm with coordinating a building information model of the entire exhibit concept that would guide design and construction for the entire project team.  

HPE began using 3D modeling techniques more than a decade ago. Today, BIM tools, techniques and processes are embedded into its day-to-day business operations. The firm's expertise is a key part of why they were selected for the Asian Tropics Exhibit project.  

Sean Lauck, CAD department manager for HPE, says, "The pipe networks below ground look like a bowl of spaghetti. This project would be virtually impossible without BIM to accurately link all facets of the project to what actually occurs in the field."

The Asian Tropics exhibit's critical life-support system cleans and treats the pool water in the animal exhibits. The water is piped from a filtration building to each pool and dispersed through a network of eyeball fittings located in the sides and bottom of the pools. The challenge is to coordinate each system through a myriad of new and existing site utilities and structures, such as rock wall foundations, signage, fencing, buildings, lighting and shelters as well as all the different ponds that supply and drain water to the water treatment plant on one side of the facility.  

The life-support pipe systems range from 4-inch to 12-inch schedule 80 PVC (a majority is 10-inch to12-inch range) with non-standard connections for changes in direction (not typical 45 degree or 90 degree, etc.). Each pipe is run at a different elevation from 5-ft to 25-ft below ground.

Using the QuickPen PipeDesigner 3D solution, HPE developed an intelligent 3D model of the exhibit concept from 2D contract drawings.  

Lauck adds, "The design team had coordinated key site utilities and life-support system positions, including each change in direction of the underground piping and utilities. We were able to import those coordinates to our 3D solution to build our routing model as well as to our survey equipment to coordinate field activities."  

Model basics

The Asian Tropics exhibit model includes an outline of the ten primary structures, caging, foundations, animal drinkers, and other critical structural systems such as the crane system that zoo officials used to move the larger animals. HPE modeled the entire pipe network above and below ground, in the walls of the various habitats, and critical connections along with an outline of the proposed structures and existing site conditions.  All major pipe components within the model are color-coded based on service provided. For instance, all life-support pipes are coded green while the storm water pipe is purple. All other members of the project team were required to submit designs in 3D, as well.

The general contractor modeled site utilities and site structures, such as lightpost footings and rock walls, while the mechanical and electrical subcontractors modeled their systems.

Once complete, every project team members uploaded their individual models to the project website. HPE coordinated all the data using Autodesk's Navisworks 3D coordination software, allowing the project team work out clashes.
In addition, HPE analyzed 12 different disciplines of the site such as storm versus sanitary, storm versus life support, sanitary versus life support, and so on. They also performed clash detections for six disciplines inside the buildings.

"Our goal was to run clash detection scenarios for each trade against each other and against the structural objects to ensure there were no conflicts," explains Lauck. "We also looked at unique things such as gating/caging, garage door opening paths, animal reaches, depths of pipe under exhibit area, equipment and building accesses, and even made sure the sustainable daylight lighting solutions did not block or cast shadows."

Once the model was created, it was time to bring in the zookeepers.

Clever creature challenges

Large creatures, such as elephants and rhinoceros, are probably best known for size and strength. Few realize that many of these animals are also curious, persistent and creative zoo inhabitants.  

Rhinoceros, for instance, have a 10-ft vertical reach that they will use to take apart pipes, wires, lights and any other items within their sphere. Elephants have a terrific sense of hearing. In fact, water pipes have to be buried at least 5-ft below ground because these mammals can hear water running in a pipe buried that deep and they will dig it up.  Tamper resistant nuts and bolts must be used because elephants will use their trunks to twist off a nut.

Therefore, zookeeper feedback during the design phase is invaluable. The project team met with the zoo staff weekly, using the 3D model to fly-through the various facilities and exhibits, helping the project team resolve some critical issues that might have been missed if 3D modeling had not been used.

In one case, the zookeepers noticed that the storm drain and water pipes located in the elephant transfer area were in easy reach of elephants. All pipes were protected with sheet metal covering. As a rule of thumb, the covers must maintain a 30-degree angle or less at corners to prevent the elephants from pulling cover off and yanking pipes down with their trunks.

A second issue was the ventilation and lighting openings at the top of the parlor.

Lauck recalls, "We discovered from the model that it would be possible for an elephant to reach through these openings and grab components like the pipes, lights and fire sprinklers. During our meetings, we came up with a mesh panel to cover some of the openings and in other cases re-routed pipes."

As design requirements changed, each member of the project team would revise and upload digital models to the project team website. HPE would import the models into Navisworks and go through the review process again.

Once approved, HPE fabricated all PVC piping and duct in its shop directly from the 3D model.

From model to field

With conceptual agreement of the design, the role of the 3D model shifted from design to construction and construction management. The general contractor used it to sequence all the piping installation.  

Lauck says, "All piping lines were numbered and labeled in the model to make sure pipes, connections and other underground utilities were installed from deepest to shallow and from one side of the site to the other. We couldn't have open trenches blocking access, because some of the deepest pipe was in the middle of the site."

Once installation was ready to begin, HPE downloaded the data from QuickPen PipeDesigner 3D to a GPS receiver to make sure that the pipes and connections were placed exactly as modeled.

 In fact, every component from site utilities to pipes and ducts are being located using GPS and total station technology, such as Trimble's MEP Layout Solution.

"I don't know how we could have done this project without BIM in the office, the shop and the field. It's simply the best way to provide the most quality, efficiency and accuracy, concludes Lauck.

To-date, 100% of the life-support pipe network has been installed on the project site, with no conflicts with other systems below ground. The Asian Tropics exhibit is on schedule for completion in December 2011.