3D modeling slashes the costs of long-term maintenance, project design, and construction

The Tracy Wastewater Treatment Plant (WWTP) Phase 1B expansion project required a complex engineering design to upgrade and expand existing facilities constructed in the 1950s. The primary project goal is to meet stringent environmental regulatory conditions imposed by the U.S. Environmental Protection Agency.

Tracy WWTP is located some 75 miles southeast of San Francisco and serves a population of about 75,000. Because the effluent discharge is near the Sacramento River’s Delta region (which provides drinking water for about two-thirds of California’s population), the plant needs to provide a high level of treatment on a consistent basis. This requires complex, advanced treatment, such as oxic and anoxic basins. Accommodating these processes required designing large, complex equipment and piping systems.

Because of a limited site area, several existing facilities were reused and old drawings were converted to 3D models so both the old and new facilities could be represented in one model.

Upon project completion, Tracy WWTP will be able to produce high-quality recycled water for landscape irrigation, cooling and other environmentally beneficial applications.

Total estimated program cost is $145 million and Phase 1B is expected to cost roughly $80 million. Pre-design was completed in 2003 and the final design was completed in 2004. The project is currently under construction and expected to be completed by the end of 2006.

Working across the miles
To facilitate efficient operations and maintenance, piping ranging in size from 2 in. to 48 in. is routed in galleries. Additional equipment included numerous control valves and actuators, pipe crossings, two large blowers (600 hp) in the blower building and 12 pumps in the galleries. 3D modeling proved to be beneficial in designing and illustrating the project. All told, there are 564 drawings and 4,500 pages of specifications in the contract document.

Making matters more complex, completion of the final design was a collaborative effort involving the technical staff from six offices in four states. A collaborative project Web site facilitated the sharing of data, drawings and 3D models among the various offices. Based on the number of pipes, valves, pumps and control systems in the piping galleries, it would have been almost impossible to avoid conflicts without using 3D modeling. Similar efficiency was achieved in concrete slab thickness and headroom clearance space for equipment and monorails.

“3D modeling used by the CH2M HILL design team was terrific,” said Dr. Nicholas A. Pinhey, public works director, City of Tracy, California. “This feature enabled operations staff to see future facilities in a virtual reality mode and helped them to provide quality feedback to the design team.”

The project design rarely included 2D drawings because 3D visualization provides a much better environment for project review. 3D models used during city council meetings received enthusiastic reviews and facilitated quick and efficient project implementation. These models also were shown to potential contractors during the project’s pre-bid meeting, helping them visualize the work without going through the more than 500 drawings.

Using 3D modeling also was responsible for saving 10% to 15% of the design hours. This increased efficiency allowed the entire design to be completed in nine months, rather than the 12 months to 15 months that would normally be needed for a project of this scope. This resulted in savings of $5 million to $10 million in steel and cement costs alone, which recently have been rising rapidly.

After startup
Eventually, the 3D visualization will be transformed into an operations and maintenance manual that should increase operations and maintenance efficiency by an order of magnitude during the facility’s entire life cycle. The plant will also use the manual as a tool to help train new operators on each facility, and to show them the location of pipes and equipment not visible from the ground.

The Tracy WWTP has been described as an operator’s dream facility. The 3D design software will enhance the owner’s visualization of the project as it progresses, as well as making design and construction more efficient.

Rob Brawn is director of automation technology at CH2M Hill, Englewood, Co. Contact him at (303) 771-0900.