By Kim J. Gifford

The terms “conservation” and “construction” may seem contradictory at first. After all, conservation seeks to maintain an environment and construction strives to transform the environment to meet the requirements of a specific project.

“The environmental impact of the construction process is something very few people really think about,” says Fred Ploeger, purchasing agent for Trumbull-Nelson. “Construction, being the intrusive activity it is, sometimes assumes that anything that’s damaged will eventually get fixed.”

Unfortunately, when it comes to the environment some damage is irreparable. Construction may displace wildlife, remove trees and leave the landscape vulnerable to erosion. Recognizing the importance of preserving the natural balance in light of expansion and growth, federal, state and local governments have enacted laws and regulations to protect wetlands and certain wildlife habitats. Some businesses are even going beyond what is required, taking proactive measures to minimize the damage from construction at the very start of a project. Such efforts are going a long way toward ensuring that conservation and construction do not remain mutually exclusive terms.

…contractors currently rely on silt fences, vegetation swales and temporary stabilization structures made of timber, straw or hay bales to detain sediment and manage runoff and storm water.

“Given the rapidly expanding population, it is obvious that growth — and construction —is going to occur,” says Peter Spear, owner of Natural Resource Consulting Services in Concord, N.H. Spear’s company secures building permits for businesses and implements environmental mitigation methods and plans specified in these permits. “It is our job to mold that growth so it does the least amount of damage to ecological systems.”

Ploeger agrees. “Construction companies, such as Trumbull-Nelson, can reduce the ecological impact on their job sites by minimizing the use of heavy equipment, controlling storm water drainage, reducing construction waste, and protecting local flora and fauna through proactive site management.”

Soil Erosion and Water Management

One of the primary environmental concerns involving construction is soil erosion. Construction disturbs the ground, uproots vegetation and exposes soil to elements that cause erosion such as wind and water. Subsequently, surface runoff and silt particles can form gullies and sediment deposits or wash away into wetlands or streams where they can block culverts, flood channels and destroy wildlife.

“Development plans are always beautiful,” says Vicki Smith of New Hampshire’s Town of Hanover Planning Board. “It’s what happens from the time they take down the first tree and start the first bulldozer that’s so important.”

Homeowners and contractors, she feels, are finally becoming aware of the effects of water and sediment caused by construction. “They visit a brook to go fishing and find no trout,” she says. “We hear a lot of ‘I’m sorrys,’ but for all the creatures who live in the brook, ‘I’m sorry’ doesn’t matter. It’s finally starting to click.”
Spear recommends scheduling construction during “low flow periods” to avoid high runoffs and considering trout spawning cycles when working adjacent to a trout stream or tributary. Trout spawn in the fall, but their eggs remain in the stream and do not hatch until spring, so it’s best to avoid construction in or near the water during these times.

Construction projects typically require an erosion control plan, and contractors currently rely on silt fences, vegetation swales and temporary stabilization structures made of timber, straw or hay bales to detain sediment and manage runoff and storm water. “It takes more than a plan to meet the challenge. It takes a daily effort to minimize runoff,” says Rick Nothnagel, facilities planner at Dartmouth-Hitchcock Medical Center (DHMC) in Lebanon, N.H.

Companies such as Spear’s are also using biotech stream bank enhancement as a means of reducing erosion on the sides of a stream. “The standard method is to use big rocks that don’t erode,” says Spear. Instead, he puts the natural environment to work for him, using logs or existing eroded trees in combination with the rocks. “We leave trees intact and fill in gently around them with rocks, allowing some openings for the silt to fill in and the area to green up again.”

One of the considerations of any construction project is the bottom line. Even eco-friendly developers must bear in mind financial concerns when undertaking a project. Some solutions, however, can have huge environmental benefits with minimal additional costs. For example, many projects require the construction of a detention basin to hold and parcel out excess water. These basins are usually rock-lined, man-made structures, yet without much additional money, they can be redesigned to resemble ponds that continuously hold some water and landscaped to enhance the environment. “You get to fulfill regulations and build a wetland at the same time,” says Spear.

Wetlands and Wildlife

Wetlands not only help regulate water levels in watersheds and reduce storm damage, but also function as fish and wildlife habitat. Regulations exist to minimize the effect of construction on wetlands, but some organizations such as DHMC are going beyond the regulations, seeking creative solutions to maximize the benefits to the environment and preserve as much of the wetlands during construction as possible.

DHMC recently designed a 1,000-space parking lot around a wetland, and worked with Spear, Pathways Engineering, and landscape architect Towers|Golde to come up with ideas to make the project environmentally friendly. They added twin, concrete box culverts — one for water and one for a terrestrial crossing for small mammals, amphibians and reptiles. Many of these creatures, says Spear, are at particular risk in high traffic areas “because they are slow or not so bright when it comes to automobiles.”

Similar wildlife crossings are becoming quite common in high traffic areas. In Florida, for example, the Department of Transportation has established crossings under Interstate roadways to allow safe passage for the Florida panther. Road construction not only puts wildlife at risk from high speed vehicles, but also causes them to modify their behavior and movement patterns. Construction can also destroy vegetation and much needed tree cover for species such as deer.

Although DHMC was careful in its design to provide an appropriate wildlife crossing, the project still displaced a portion of wetland. As a result, the medical center chose to create a subsequent wetland area complete with a slightly raised pedestrian boardwalk intended to accommodate the passing of water and small animals underneath it. “The flooring is spaced G" to H" wide so light can penetrate it, allowing ferns and moss to grow,” says Spear. It’s a good example of how construction can complement conservation efforts.

Invasive Species

Invasive species — such as purple loosestrife, garlic mustard, glossy buckthorn and shrub honeysuckle — are taking over the areas in which they grow. Some of these plants cause erosion, others alter soil chemistry and many overtake wildlife habitats. Insects and birds often inadvertently spread invasive plants, while many landscapers intentionally planted them before their ill effects were known. In fact, the Audubon Society introduced much of the glossy buckthorn that has invaded large portions of the Upper Valley region of New Hampshire and Vermont.

Invasive species — such as purple loosestrife, garlic mustard, glossy buckthorn and shrub honeysuckle — cause erosion, others alter soil chemistry and many overtake wildlife habitats.

DHMC took advantage of its parking lot project to remove large amounts of glossy buckthorn and to introduce a variety of vegetation to the wetland it subsequently created. A recent bank restoration project in Charlestown, N.H., resulted in the uprooting of 100 large honeysuckle bushes by a Jeep and logging chain. A few years ago, a construction project at the Montshire Museum in Norwich, Vt., transformed a thicket of glossy buckthorn and honeysuckle into “a lovely walkway through a meadow of beautiful and interesting grasses,” says Barbara McIlroy, cofounder of the Upper Valley Purple Loosestrife Coalition. She cautions that it is not enough to simply dig up these plants — they must also be disposed of properly so the seeds do not spread.

“Invasive species just take over,” she says. “They won’t allow for any of the things you’d expect to find in the woods or wetlands. There is none of the expected diversity. As the ground is being disturbed anyway, construction provides an excellent opportunity to survey an area and rid it of
invasive species. It allows for a fresh start.”