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Reaching Zero: The Realities of Ecologically-Friendly Engineering on a Continental Scale

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Photo by Skip Sowards, LEO A DALY
Towers to link the nationwide NEON ecological monitoring network are rising with minimal fuss in 60 locations in the continental U.S, as well as Hawaii and Puerto Rico.
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We will soon add the nation’s ecology to the evolving and expanding “Internet of Things.”

Scientists have embarked upon a nationwide project to create a linked network of sensor-studded towers to study, for the next 30 years at least, the impacts of climate change, land use change and invasive species on the ecology at 60 sites across the U.S.A.  The first goal is to establish a baseline of data representing the state of the ecology at those 60 locations before external influences begin to cause change.

But before that network can take form there is a construction challenge to solve:  How do you build a network like that without disturbing the ecology?

It turns out that the answer is that although you can’t completely avoid impacts, if scientists and engineers work together to thoroughly study and document each site before starting work—even compromise with each other a little—and then design and build with excruciating care, we can hold the impacts on the natural surroundings to nearly zero. And not only that, from the process of working with ecologists to develop designs and techniques for building out the system with minimal impact on nature, we in the construction community should be able to learn how to go more lightly on the land.

The National Ecological Observatory Network (NEON), which is funded by the National Science Foundation, will gather and synthesize data collected from sites across the nation, including Alaska, Hawaii and Puerto Rico, using instrument measurements and field sampling. The sites have been selected to represent different regions of vegetation, landforms, climate, and ecosystem performance.

NEON will combine site-based data with remotely-sensed data and existing continental-scale data sets, such as satellite data, to provide a range of scaled products that can be used to describe changes in the nation’s ecosystem through space and time.

A cyberinfrastructure of instrumentation and sensors affixed to the towers in 20 ecoclimatic domains across the U.S. will collect the data into an information management system. Then NEON will make the data available via the internet to anyone wishing to use it. Metrics and measures of ecosystem change—approximately 600 billion raw measurements every year—will be routinely computed and later used for a new generation of ecological forecasting models.

The first prototype tower was constructed in 2010. Limited data collection began this summer.  And now, scientists, engineers and construction personnel, using what was learned in building the first site, are following strict sensitivity guidelines to build minimally invasive towers in all 20 domains.

Some sites are permanent, designed to collect data for 30-plus years. Some are re-locatable, designed to collect data at any one site for five to 10 years. The future integrity of scientific outcomes relies on the integrity of the towers and their collective ecological impact.

Typically, when a building or design project calls for zero- or low-impact engineering, the scope is for one structure, or one roadway, or one sewer system, in one particular environment. With NEON, civil engineers are required to inspect sites, coordinate topographic surveys and geotechnical drilling, and plan and design foundations for 60 different ecological environments—all with “zero” in mind.

With NEON, everything—from the width of the access path created to each site, to the tread on the boots worn by construction crews—is considered with a zero-impact frame of mind.

The NEON project is driven by two communities – scientists (Science) and engineers and construction workers (Construction). Science demands zero impact to all sites: Any disturbance is too much. Construction, naturally, is forced to negotiate.

“In the beginning, everything was a negotiation,” says Chris Thompson, NEON’s assistant director of facilities and civil construction. “Science would tell us what they expected and we would tell them what was doable from a construction standpoint…from the width of the access path to the size of the tower foundation. Everything was analyzed to determine the right balance of construction practicality and long-term, accurate scientific research.”

NEON’s unprecedented nature, however, made it challenging to predict the long-term impact of construction. So to be safe, both teams agreed to be conservative.

Science originally envisioned the sites as being built without the use of conventional construction equipment. To achieve zero-to-minimal impact, excavations would be completed with a shovel and pick by hand. The Science team also envisioned smaller towers built of lightweight scaffolding with which they were familiar. In practice, though, NEON sites feature much larger and heavier towers, due to the instrumentation they hold and the safety concerns for those working on the tower to collect and adjust and calibrate instruments on a regular basis.

So one of the more important compromises was reached; the largest piece of equipment to be used on each site would be a Bobcat-like compact tractor. All aspects of each site design (foundations more than anything) were based on this agreement, and requirements started developing such as:

  • Access paths shall not exceed 7 ft in width
  • Each tower foundation extends two ft beyond the edge of the tower
  • Each instrument hut foundation extends three ft beyond the edge of the hut
  • Tower foundations must be less than 8-ft by 8-ft wide, which is a challenge when some towers are more than 200 ft tall.

Every site goes from design drawings, created by LEO A DALY engineers, to post-construction checks. LEO A DALY is providing civil design and engineering as well as site analysis, survey, and design services.Each site offers unique challenges, but the process, in general, is the same:

  1. Site work is conducted with a careful layout of access routes. Every tree’s location is surveyed so that access paths and power runs can be designed around them.
  2. Construction documents are reviewed by NEON Science and the civil engineering and facilities teams at 30%, 60% and 90%-complete.
  3. Drawings go out to bid; contractors engage in Q&A with NEON.
  4. A contractor is selected, followed by a pre-construction meeting between NEON, Leo A Daly, and the contractor. The contractor must provide means and methods for meeting both Science and Construction requirements.
  5. A pre-vegetation survey is completed prior to the arrival of construction crews, providing an ecosystem baseline.
  6. Construction begins with stakeout and boundary delineation.  Once everything is marked, Science visits the site for review and approval before any construction activities begin. Changes are made, if necessary, and the construction limits are approved.

A NEON field supervisor is present during each day of construction. The supervisor ensures the work is performed in accordance with the drawings and the approved construction limits.

Many challenges impact the process, including the restriction on machinery, the remote conditions, a lack of electricity, below-grade obstacles, site accessibility, cost, and pure incredulity. Ironically, the latter two factors—cost and incredulity—have the greatest potential impact on the project.

Cost is a major factor. The restrictions on use of automation and machinery reduce construction productivity and drive up cost. But there is no point to beginning a large-scale experiment in a manner that may cause material impact to the outcomes.

But the biggest factor impacting the zero-impact approach is incredulity. A common reaction from contractors, once they review the construction requirements, is “You want us to do what?”

It’s hard to say, at this point, how much human factors impact a project like NEON. But one thing’s for sure: compromise has been critical to improving the likelihood for success. And to our delight, a majority of the contractors hired have become eager to meet NEON’s strict, ecologically-friendly construction challenges. In return, NEON scientists have learned to accept that breaking new research ground comes by way of a machine, and not a hand tool.

Human factors, such as cost and time, have impacts on both Science and Construction on the NEON project and affect both parties ability to achieve ecologically-friendly engineering at the “zero” level. And the reality is that human factors prevent a zero-impact ecological study. If you take any ecosystem and introduce humans, whether they’re carrying spades or driving compact tractors, there is an impact.

The story is really just getting started. We’ve learned already, though, that a contractor’s awareness of zero may be the greatest advocate for achieving next-to-zero. And for now, next-to-zero will have to suffice. To conclude otherwise is to dismiss progress altogether and then human-impact measurements would round out to somewhere around…zero.


Authors include LEO A DALY employees Elizabeth Hunter, PE, AICP, LEED AP BD+C, Civil Project Engineer; Basant Kumar Satpathy, PE, SE, Senior Structural Project Engineer; Frank Egelhoff, PE, Senior Electrical Project Engineer; and Aaron Filip, Marketing Coordinator - Journalist; together with NEON Inc.'s, Christian Thompson, PE, Assistant Director of Facilities and Civil Construction.


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