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By Terry D. Bennett, PLS, LLS, LPF, LEED AP
Part 2: BIM and Sustainable Approaches
In the first article in this series, I discussed what sustainability is, why it’s important to civil engineers, and how a design process known as building information modeling (BIM) has enabled engineers to practice sustainable design much more effectively in their design efforts. In this installment, I’ll go into specific detail about how adoption of BIM enables sustainable outcomes in several key aspects of civil engineering design, including water, wind power, sewer, energy and materials, and waste.
The New Technologies and Resource Context
Everything in the built environment—roads, buildings, bridges, and neighborhoods—requires some combination of energy, water, and materials for its design, construction, and long-term operation. By making smarter choices about these factors early in the design-build process, you can greatly increase the odds for a sustainable outcome. The first step is understanding which factors you can control, such as material choices, water usage, or energy consumption. The next step is having access to advanced design and analysis tools that enable you to measure, analyze, and optimize these factors in a timely fashion.
 Figure 1: A rain garden in action near Iowa's Great Lakes. Image courtesy of Natural Resources Conservation Service (USDA).
As mentioned in the previous article, BIM is a process that delivers these results. It enables civil engineers and designers to understand the environmental impact of every design element early in the design process—long before they make critical design decisions about site location, storm water management, or material movement. A model-based process also makes it easier to accurately represent nontraditional elements of design, such as rain gardens [see Figure 1], engineered wetlands, wind farms, and eco-community development or transportation corridors that minimize environmental impact. As a result, civil engineers can now view an entire project and its surroundings as a single integrated digital system—from initial concept development through construction—and not as individual, unrelated designs.
More than just a new approach to design, BIM also gives you the flexibility and power to design and redesign until you get it just right. With the BIM process, everything you need for sustainable design, analysis, simulation, code compliance, and certification becomes routinely available as a by-product of the standard model-based design process. As a result, you can analyze data on the fly, obtain almost immediate results, revise, and then compare accurate, quantifiable results. This iterative process greatly increases your ability to reduce energy use, water consumption, carbon emissions, and waste in your designs.
Let’s look at how you can apply this methodology to achieve more sustainable outcomes in the following areas:
Water
Water is an increasingly scarce and precious resource. Around the globe, water tables are falling—the victims of excessive pumping—even as demand continues to double every 21 years. Because more than 70 percent of all water use is for irrigation of vegetation, landscaping, and crops, attempts to limit water consumption can lead to limits on food production, particularly in countries with high poverty levels. In those cases, such limits can result in higher food prices, an increase in imports, and even political instability. As mentioned previously the U.N. Intergovernmental Panel on Climate Change found that as many as 2 billion people won't have sufficient access to clean water by 2050. That figure is expected to rise to 3.2 billion by 2080. At the beginning of this decade, the World Health Organization estimated that 1.1 billion people did not have sufficient access to clean water.
Because civil engineers design much of the infrastructure that stores and conveys water, they have an opportunity to mitigate some of these problems. By using coordinated, consistent BIM data to design systems that minimize the overall use of water in construction processes, protect existing wetlands from construction, and focus on net-zero water usage and removal from a site, civil engineers can greatly reduce the costs and risks associated with water and wastewater. In their new, more sustainable designs, they’ll encourage using recycled water for irrigation, minimizing contaminants in wastewater, and investigating the feasibility of capturing, recycling, and reusing water onsite.
 Figure 2: Wind Farm in upstate NY. Image courtesy of Author.
Wind
According to a recent report by the U.S. Department of Energy, wind turbines could provide 20 percent of the country's power by 2030—compared with about 1 percent that they provide now. Proponents believe that for an investment of $6/person per year, increased adoption of wind power could save 4 trillion gallons of water and reduce carbon dioxide emissions from electric plants by 25 percent. Others believe that the inconsistent nature of wind limits its usefulness for mass deployment across the grid, but still makes it worth considering as part of an overall renewable energy strategy, especially if the price of fossil fuels continues to rise.
Although civil engineers do not design wind turbines, they do have an opportunity to participate [Figure 2] in creating the necessary infrastructure, without which the turbines themselves will be useless. Design opportunities for civil engineers include:
• Wind studies (including topography, grades, weather patterns, soils, etc...)
• Temporary met towers
• Construction trailers and lay-down areas
• Concrete batch plant
• Construction spoil disposal sites
• Construction work areas around turbine foundations
• Access roads
• Public road improvements
• Electrical collection lines, & transmission lines as well as switchyards, substations, point-of-interconnection stations
• Permanent met towers
• Restoration and mitigation projects
• Operations and maintenance buildings
Sewers
America’s aging sewer system is another source of tremendous opportunity for civil engineers. Despite years of fines and penalties, public agencies across the country continue to dump human waste into rivers and streams. According to analysis by the Environmental Protection Agency (EPA), since 2003 hundreds of municipal sewer authorities have been fined for violations, including spills that make people sick, threaten local drinking water, and kill aquatic animals and plants. To improve this situation, local governments across the USA plan to spend billions modernizing failing wastewater systems—some of which are more than 100 years old—over the next 10 to 20 years.
Traditional wastewater disposal systems convey sewage from urban areas to nearby natural wetlands. Today, however, civil engineers are helping to develop systems that do much more than just dump waste in a stream and hope for the best. By using analysis made possible through the BIM process, civil engineers are developing ever more efficient and higher-capacity constructed wetland systems that leverage the natural tendency of ecosystems to purify water and recycle nutrients. Their exact design depends on location, climate, and population, but all involve passing wastewater through a managed or constructed environment where a diversity of plant and animal organisms transforms the waste in pure water.
Energy and Materials
Virtually all design and construction processes rely on energy—whether it’s electricity to power your desktop computer or fuel to run heavy equipment. Regardless of the type and source, one trend has been consistent—energy prices have risen steadily over the last 35 years. Unless your firm has invested time, money, and effort in learning how to design and build more efficient infrastructure, energy costs now represent a much larger share of your operating expenses than ever before—with no end in sight. In addition, in many parts of the world, the electrical grid is aging, inadequate, and vulnerable to outages, which could further drive prices up as utility companies struggle to upgrade.
 Figure 3: GPS-guided grader. Image courtesy of Trimble Navigation LTD.
One recent development, GPS Machine Control, [Figure 3] provides civil engineers with a valuable opportunity to improve productivity, while minimizing unnecessary resource use, costly change orders, and fuel costs. After engineers finish creating the initial3D model, contractors can upload a variant of that model onto GPS-controlled construction equipment, enabling machine operators to see the model on their equipment, grade more accurately, ensure positional accuracy of all elements, and minimize field surveying.
When everyone on the extended design team is connected through the integrated building information modeling process, planning for both design and construction can proceed almost simultaneously, with everyone on the extended design team able to provide input early and often. The BIM process also enables design teams to conduct ongoing constructability reviews as the project progresses from planning to design. For example, if designers carefully consider the sequence of grading a site pad or road as a part of the overall construction design and transfer that information to GPS-controlled equipment, the construction team can virtually eliminate the design misinterpretations that result from human error that occur when transferring that information on paper.
Such levels of precision also help:
• Increase productivity by up to 50 percent
• Reduce guesswork and costly rework by moving dirt right the first time
• Reduce survey costs up to 90 percent
• Increase material utilization
• Reduce operating costs by eliminating unnecessary equipment movement
• Extend the work day when required to shorten the project time
Waste
Another environmental issue growing ever more acute is the worldwide problem of waste disposal. Landfills are at capacity and difficult to site. Decomposing trash emits greenhouse gases more potent than carbon dioxide. Escaping chemicals can contaminate the soil and water supply. Incinerators are under pressure to close because they emit benzene and chlorine, carcinogens that endanger human health and the environment. There is simply no longer any place on earth to throw things “away.” That’s why more than 50 government entities worldwide have adopted a goal of zero waste—a policy often backed up by steep waste disposal fees, especially common anywhere waste disposal options are scarce.
Waste is a symptom of a non-optimized and non-collaborative approach to the design, construction, and operations/management process. Any unwanted byproduct increases expenses—and the cost of goods—but does nothing to increase the project’s overall value, whether it’s a building, a road, or infrastructure. Civil engineers can participate in the zero-waste movement by carefully considering how much waste, both direct and indirect, their designs create. The best possible practice—and the most cost-effective—is to eliminate waste altogether by improving process efficiency and sustainability. However, when unable to eliminate waste, you may also recycle it by transferring it to another party who can repurpose it.
Some ways BIM helps civil engineers optimize design process and reduce generated waste include:
• Providing better and more accurate takeoff estimates of material quantities and required components.
• Finding a productive (and ideally profitable) use for industrial outputs and leftover material.
• Enabling new project delivery methods, such as Integrated Project Delivery (IPD) where engineers, architects, contractors, and owners share project risks and rewards and exchange dynamic, real time project information from project outset.
Conclusion
If you take away one concept from this article, let it be this: advances in model-based technology that leverage consistent, coordinated information have made sustainable design practices both practical and economically feasible—for civil engineers, their clients, and all members of the extended design team.
As a result, more and more public/private partnerships are forming throughout the country and around the world to develop or renew a more sustainable infrastructure. Developers are participating with owner clients, taking advantage of sustainable practices to offset rising fuel costs and better communicate design intent when seeking support for large-scale projects. They also reap the benefits of lower long-term infrastructure costs. Local, state, and federal agencies see potential benefit as well. Not only will sustainably designed infrastructure and communities attract new commercial businesses, but they will also have undeniable health benefits for their constituents. Finally, many private individuals will be attracted to efficient buildings, low impact developments, and neighborhoods for philosophical and personal reasons.
In the final installment of this series, I will look at how to leverage sustainable design as a business opportunity and focus on the triple bottom line—one that puts the Earth and green back into the civil engineering business balance sheet.
Want to learn more? Visit http://usa.autodesk.com/company/sustainable-design for more information.
About the Author
Terry D. Bennett, PLS, LLS, LPF, LEED AP, is the senior industry manager for civil engineering and construction at Autodesk, responsible worldwide for the company’s industry strategy and relations in the areas of land/environmental planning, land surveying, civil engineering and construction. He holds multistate registration in both land surveying and natural resource forest management, and is a LEED-accredited professional. Bennett has also been a practicing professional consultant for the last 26 years.
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