Duke University is home to two, 1920s-era steam plants that have been central to the growth of the university, which is renowned for its academic and medical excellence. Comprised of 220 academic, research, and medical buildings split between Central, East, and West Campuses, Duke has more than 14,000 undergraduate and graduate students and employs more than 33,000 people campus-wide, including the Health System. The prestigious Duke University Medical Center, located on West Campus, is consistently among both the top medical schools and medical centers in the United States, serving more than 40,000 inpatients and 1.1 million outpatients annually.
Campus growth has far outpaced the estimates of early campus planners and, subsequently, outpaced the capacity of the two existing coal burning steam plants and their associated infrastructure. The East Campus Steam Plant (ECSP) originally was completed in 1926 and later decommissioned in 1978. Its sister plant, the West Campus Steam Plant (WCSP), was completed in 1929. However, since its original construction, the WCSP has undergone several significant renovations. Upgrades included boiler additions in 1966, 1977, 1988, and 1994 designed to meet growing campus demands.
Since the 1920s, Duke's main source of energy has been coal. In 2007, the university's president and the Campus Sustainability Committee adopted a Climate Action Plan (CAP), pledging to make the university carbon neutral by 2024. Within that plan, a recommendation was made to eliminate coal use completely on all of its campuses by converting both the ECSP and the WCSP to natural gas.
In 2007, RMF Engineering was tasked with replacing the old decommissioned coal-fed boilers in the ECSP with 15 new natural gas boilers and upgrading the badly aged infrastructure that once served the plant. The project presented unique challenges that often surface when designing new infrastructure for older and high-density college and university campuses. For instance, most of the existing utilities serving the ECSP were completed in the 1920s and little was known about their size, location, or condition.
RMF adopted AutoCAD Civil 3D as early as 2006. At that time, a custom template was created containing pipes and structures that differed from the "out of the box" solution provided by Autodesk. Unique AutoCAD Civil 3D parts were created to match industry standards for sizes and materials. The parts were compiled to create a custom set of pipe networks tailored to infrastructure design including thermal distribution, gravity systems, and duct banks.
Template styles were created to match company drafting standards, allowing for an easy transition from the 2D drafting environment to 3D modeling. The early effort and experience proved to be vital in 2007 when the ECSP project was awarded to RMF Engineering. The challenging site, the constantly evolving design, and later the efficiency with which the ECSP was constructed would demonstrate the value and capability of Civil 3D as a design tool.
An accurate 3D model was created of the existing ECSP site and subsurface conditions based on a current traditional survey and subsurface investigation of the project limits. Original site plans from the 1920s were incorporated into the model, as were the university's archived site plans from more recent projects near the ECSP.
Accuracy of the model was essential when progressing through the design stages. The final design would only be relevant if the existing conditions were correctly identified. After completing a preliminary layout, test holes at all proposed utility crossings were completed in an effort to verify the size, depth, and location of each existing utility in the newly created 3D model. By creating and maintaining a highly accurate 3D model of the existing site, the design team was able to better handle design challenges as the project progressed.
The model was used throughout the entire design process to make intelligent decisions regarding the preliminary layout of all the new utilities needed on site. Since this was a steam plant project, there was an extensive amount of new utilities in the surrounding area. Pipe networks were built for all of the infrastructure systems surrounding the plant, including new steam and condensate piping, electrical and telecommunications duct bank, domestic water, propane and natural gas piping, storm sewer, and sanitary sewer piping.
All utility crossings were analyzed to ensure that proper cover and clearances were provided for the new infrastructure system. During the design process, the design team could tell at a glance if a utility was designed without proper cover or if there was a conflict with another utility by viewing the 3D model within the software.
There wasn't a pipe network included in the standard Civil 3D template that could accurately model the realistic behavior of the duct bank system's design. RMF Engineering manipulated tools from the Civil 3D program in an unconventional way to allow for the electrical and telecommunication duct bank systems to be designed in 3D. The program's corridor modeling capabilities were used to create a custom layout that met the design criteria. The coordinated utility systems created a cohesive and complex underground jungle of new and existing infrastructure.
Beyond utilities, the site required significant grading and surface improvements, including retaining walls, stairs, parking lots, and sidewalks. One of the unique site improvements was the restoration of the abandoned railroad trestle bridge that was once used to deliver coal to a hopper at the roof of the plant.
The revised site and grading design was incorporated into the 3D model using Civil 3D's grading and surface creation tools, which allowed for the new utility profiles to be designed accurately based on the proposed grade. To assist the team's ability to visualize the system, RMF created a video fly-through of the site after the model was completed. The video showed the plant, infrastructure, and site improvements. It allowed the final design to be reviewed by team members that did not have access to Civil 3D.
Construction for the $26 million ECSP renovation project began in 2008 and was completed in 2010 with minimal design conflicts. The success of the project factored into awarding RMF Engineering the WCSP renovation project in 2011.
The WCSP is similar in size and complexity to the ECSP. However, the staging and site limitations were significantly more difficult. The Duke University Medical Center is located on the West Campus immediately adjacent to the WCSP. Like all buildings on West Campus, the Medical Center is supplied with steam solely from the WCSP. As opposed to the ECSP, the WCSP needed to remain operational throughout construction.
A 3D model was developed using the same methodology as the ECSP project, with the added pressure that a mistake in the design could potentially lead to a utility outage affecting half the campus – including the Medical Center.
"During the early design stages of the WCSP project, it was critical to be able to use the object viewer tool when expressing design strategies within the project team," explained Matt Boatwright, a designer at RMF Engineering. "Images from the object viewer were constantly being circulated among the owner, design team and contractor. We continue to see the benefit during construction as we coordinate the project's complex phasing and installation with the contractor."
The project also has benefited from RMF's investment in robust computer hardware and software.
The project also has benefited from RMF's investment in robust computer hardware and software, including Autodesk's visualization software Navisworks. Navisworks allows designers to show the client changes in the design file immediately. For Duke, this feature gave the university the ability to see video renderings throughout the stages of design, as opposed to when the design was complete.
"Navisworks allows us to easily combine several different file types between disciplines to produce a brilliant 3D representation in real-time during the design process," said Mike McClenathan, designer at RMF Engineering. "The animation and rendering features are effortless and the process is greatly improved compared to past visualization software."
Intelligent 3D modeling and visualization software has significantly advanced engineers' design capabilities. These programs have allowed for more accurate and detailed designs, minimizing conflicts during construction. These improvements are proven by the past success of the East Plant and more recently the West Plant, which is currently midway through the construction schedule.
The use of 3D software ultimately has led to a pair of designs that incorporate new infrastructure seamlessly on the historic project sites. The result: fewer underground conflicts, greater project management efficiency, and higher cost-savings.
View a fly-through of the Duke University project at http://youtu.be/D7A5OIn7FrY
Kyle Bowker, EI, is a project designer at RMF Engineering's North Carolina office (www.rmf.com). Vance Nall, P.E., is a project manager at RMF Engineering's Georgia office.