Sustainability in project design

February 2011 » Columns » BEYOND WORDS
Eileen Straughan

Engineers must set the standard for sustainability in project design activities. Whether designing the infrastructure for a residential subdivision, commercial development, or designing utilities, highways, transit systems, airports, or other major public infrastructure facilities, design activities will be more sustainable when all projects start with an understanding of the resources — both human and natural — that could be impacted by the project, and are guided by a commitment to avoid and minimize impacts to these resources wherever possible. This commitment includes development and design of appropriate mitigation where impacts are unavoidable.

This thinking represents a fundamental shift from environmental compliance to sustainability. The compliance-based approach asks: What is needed for basic environmental compliance to get approvals from government regulators? The sustainable design approach asks different questions, such as: Where and in what condition are the resources; how will the project impact these resources; how can the design of the project minimize those impacts; and how can the project improve the condition of the resources? It is a fundamentally different design process because it sets protecting, enhancing, and restoring the environment equal to the overall project objective. This approach does not increase project costs if environmental considerations are integrated within the design process in the preliminary design stage, and continues throughout the design development.

The process of sustainable design begins with collection of the environmental aspects of the project area — everything from soil and air quality to parks/community facilities and cultural/historic resources. 

Engineering sustainability requires attention to the larger habitat context of engineering projects such as understanding water resources at the watershed scale as well as the local drainage-area scale; designing to mimic natural landforms to avoid mass grading that changes hydrology of the sub-drainage area to protect receiving stream stability; and emulating natural hydrologic flow paths and destinations in the way stormwater is managed. It also includes providing for green infrastructure, a way for natural habitat to exist within the context of the project, and providing for essential connection of adjacent natural habitat for safe passage and movement of wildlife. Plans should specify renewable forms of energy wherever possible and the highest level of efficiency in equipment. Water use and re-use also must be addressed by specifying water-efficient fixtures, reducing the demand for potable water by using rainwater harvesting, and specifying native landscape materials that require less irrigation. Whenever possible, engineers should specify materials that come from local sources to reduce transportation-related emissions and environmental impacts, and specify recycled, recyclable, and reuseable materials.

Finally, engineering sustainability during the construction phase requires attention to reduce construction-related environmental impacts by implementing comprehensive pollution prevention. Sustainability on construction sites includes changes in site management to reduce the amount of land exposed to erosion at any one time, implementation of redundant erosion and sediment control devices, and significant attention to erosion and sediment control device maintenance. It also includes improved energy efficiency and reduced emissions on construction equipment, and continuous efforts to manage construction-related solid waste to reduce disposal to municipal landfills. A sustainable environment also includes effective and efficient transportation systems, utilities, other infrastructure, and buildings that serve the needs of our growing human community.

Armed with a comprehensive understanding of all resources, it’s easier to quantify and understand impacts associated with different project alternatives, so selecting the best alternative in terms of satisfying the overall project objectives and protecting the natural and human environment to the maximum extent practical is an easier path to discern. Our challenge as engineers is to design these human-needed elements of the environment in a way that protects, enhances, and restores the natural environment on which we and future generations depend to sustain life.

Eileen Straughan is president and founder of Straughan Environmental. Tracy Seymour, P.E., is director of environmental design at Straughan Environmental


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