Friday 15 December 2017

SUSTAINABLE INFRASTRUCTURE

Sustainability results from the integrated consideration of all elements of developing places for our society to live, work, and recreate, not just the vertical, habitable spaces within the buildings walls. To be sure, what goes on in the building has a significant impact on the infrastructure serving the building, but are we realizing the full benefits of the efficiencies achieved inside?

If buildings are where we live, then the infrastructure providing access to them, and the systems that deliver power, telecommunications, water, sanitary sewer, and provide drainage and flood control, is the fabric that connects those buildings to a community.
Civil engineers are responsible for designing the infrastructure surrounding and serving the building, and they are the natural candidate to be the next champions of sustainability.

What happens outside the walls? Is your site designed to reduce rainfall runoff, control storm water quality, or capture reusable resources on site? Is the hardscape around your building helping or harming the environment? Is that design decreasing the need for downstream or offsite infrastructure, or is it actually increasing it? Have the reductions in energy and water consumption you have strived so hard to achieve resulted in reduced infrastructure requirements outside the walls? Have the efficiencies you have built into your building been translated all the way to the water supply or wastewater treatment plant? Are the streets and parking lots that provide access to your building designed to reduce materials resource consumption? Are they designed to use readily renewable or locally available materials? Has the exterior building lighting and adjacent street lighting been designed to preserve the enjoyment of the night sky by reducing light overspill? Has open space been integrated into the site design so that it can serve multiple purposes? Do those open spaces accommodate alternative mode circulation and access, storm water quality, shading pavement, or air quality enhancement through vegetative uptake of pollutants? Are the streets and intersections leading to your site designed to provide the most efficient flow of vehicular traffic, as well as provide for alternative fuel vehicles or multi-modal access?

For every foot of annual rainfall, a 3,000-square-foot roof can produce 22,440 gallons of water, potentially available for irrigation of surrounding landscape, if facilities are installed to capture it. That could be 10 to 15 percent of the total potable water demands for a single-family residence. These types of savings translate into real savings in the capacities (size) of the service-providing infrastructure. However, most infrastructure systems continue to be designed for simple compliance to yesterday’s standards and codes, with little thought about the sustainability potential of more thoughtful design approaches.

Think of the hundreds of miles of roadways that are constructed every year. A majority of those roadways are local serving. Think of the substantial savings in materials resources and energy consumption if those roadways were just 1 foot narrower. A mile of local roadway, 1 foot narrower on each side, could save more than 200 tons of asphalt. Think of the reduced future maintenance and replacement costs that would result. Think of the reduced rainfall runoff that would occur (9,500 cubic feet per year per foot of rainfall). Think of the reduced heat island effect that could result from such a small change in attitude and design standards. Think of the positive benefits that could result from using recycled tire rubber as a major component of roadway pavements.

Think of a building site, subdivision, or community that is designed with low-impact development techniques, which increase infiltration and watershed response times, thus reducing storm water runoff peak flows and volumes to equal or below that of the existing undeveloped condition. You can well imagine the potential in savings that could result from reduced or even eliminated underground pipe systems, detention basins, major conveyance channels, roadway culverts, and bridges that could result.

Now think of a current set of municipal design standards that do not recognize these potential reductions, requiring instead the installation of an over-designed infrastructure system, and then mourn the wasted materials resources and energy still necessary simply because someone did not want to think about a revised design standard.

Major achievements in energy efficiency and environmentally sensitive design have been made inside the walls, through integrated systems design. Now it is absolutely necessary that we approach sustainable solutions to infrastructure design in the same manner. Only by understanding that everything is connected to everything else will we be able to deliver thoughtfully designed infrastructure that reduces materials resource and energy consumption, thus approaching sustainability and leaving something for the next generation. What more can we do? Make sure that when you say ‘sustainable design’, your civil engineer gets it.

From driving on two tar macadam strips for vehicle tires on major roads in Rhodesia to excessive bands of concrete and blacktop the roadbeds holding up a small percentage of heavy axle weights on majority of the roads the cul de sacs prescribed for a laddered fire engine turnaround are all excessive. Sustainability can be accomplished for infrastructure with a little more thought to reduce the 38 percent land use of footprint for us to get around. What about reducing the weight and size of vehicles that use only one seat but carry four to six chairs for 80 percent of travel use?

Graham Kaye-Eddie
M.U.D. 878 words 11/9/2011

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