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BIM for Water: Filtering out risk

BIM-enabled design and construction workflows on a water treatment plant project in Arizona have greatly reduced project costs, delays and on-site confusion.

With its sunny southwest climate and an abundance of golf courses, Scottsdale, Arizona, is one of the US’s fastest growing cities. In fact, the population has grown by more than 35% in the past 10 years.

This rapid growth, however, has put pressure on Scottsdale’s water supply, which is a precious resource in the arid region.

In response, the city called for a plan to ensure the long-term availability of safe and abundant drinking water. Part of that plan is to expand the Scottsdale Central Arizona Project (CAP) water treatment plant, which already supplies 48% of the city’s drinking water. By increasing capacity from 230Ml/day to 360Ml/day the plant will be able to process additional surface runoff, thus supplementing the drinking water supply when other sources are stressed.

Adding capacity at an existing, highly complex facility is always challenging. In this case, CAP consisted of 15 structures interconnected by a spaghetti-like mesh of poorly documented piping, utilities, and other underground structures. The schedule, phasing, and logistics of design and construction were also demanding.

The difficult task fell to engineering firm Walsh Group. From the beginning, BIM manager Dan Klancnik realised that implementing building information modelling (BIM) would be strategic to project success.

“With traditional 2D plans, coordination and planning without schedule-jeopardising errors would have been nearly impossible,” he says. “Our team set out to not just implement BIM as an addendum or afterthought to the project processes, but rather to incorporate it seamlessly into our workflow. Because of this, fostering a culture of BIM buy-in was paramount.”

The project team began by organising meetings with the Bentley BIM project coaching team and project stakeholders, including employees of contractor and Walsh Group sister company, Archer Western Contractors, as well as the client, designers, and key subcontractors. These were the planning and education sessions, which were an important early factor in establishing a BIM-oriented mindset.

Our team set out to not just implement BIM as an addendum or afterthought to the project processes, but rather to incorporate it seamlessly into our workflow.

Dan Klancnik, Walsh Group

Klancnik had ambitious goals for using BIM on the expansion project. The 3D model would be the central repository of information for the design team; facilitate communication among team members and stakeholders; provide visuals for communications with the city and community; generate work plans for field crews; produce materials lists and quantities; facilitate safety planning; enable interference management and design coordination; establish project phases and construction sequences; and facilitate site logistic planning.

“The universal language for effective communication among all parties throughout the design and construction phases was BIM,” Klancnik explains.

“The goal was to integrate BIM seamlessly into our processes at every level to reduce workflow redundancies and aid effective communication. After project completion, the BIM would be handed over to the client to aid in management of the new facility.”

With strategic use of existing plans and new as-built surveying, an accurate model of the existing facility was created and superimposed on proposed architectural and structural designs. From that point forward, BIM served as the project’s central database.

Substantial investment in new software, tools, and training was needed in order to use BIM as the organising principle for this major infrastructure project. Even so, the firm not only quickly recovered its investment but also achieved a substantial payback.

“Our best estimate is that the project team spent an additional $45,000 (£28,000) on model-based processes,” Klancnik calculates. “So far, the project has saved over £93,000 in potential conflicts and reduced the 28-month construction schedule by five weeks.”

The model also revealed new information to those who had been analysing technical drawings for years.

“In one instance with the composite model, we were able to identify a truss designed with a six-inch overlap into a steel beam,” Klancnik recalls. “If we had approved the incorrect design for fabrication, it would have cost £25,000 and a four-week delay.”

Similarly, a conflict between a carbon steel pipe and a support beam was detected in time to save the project nearly £30,000 and another four-week delay. In all, about 20 major conflicts and countless minor conflicts were revealed by model-based analysis, greatly reducing project costs, delays, and on-site confusion.



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