"At roughly 35 acres, this wetland is by far the biggest in the Turnpike’s inventory," said Turnpike Environmental Scientist Bill Packer. "Even more importantly, it is the largest manmade wetland in the Commonwealth of Pennsylvania."

Located south of the Turnpike at milepost 110, motorists can spy the ample wetland just east of Somerset Interchange #10. This wetland is unique not only because of its size, but also because of its function.

Typically, the Turnpike and other transportation agencies replace wetlands after an impact is made during construction or expansion projects. 

If one acre of wetland is disturbed as a result of a project, then one acre must be constructed elsewhere in the project area to compensate for the disturbed acreage. But the Somerset project is an Advanced Wetlands Compensation Area — also called a wetlands "bank" — created to mitigate for a project that is still in the design phase.

The total reconstruction of the Turnpike from the Somerset Interchange to the Allegheny Tunnel involves digging up the original, 60-year-old roadway and replacing it with an all-new road, sub-base and drainage system. Although the Turnpike has been patched and re-paved in the area numerous times, never before has such a complete, from-the-dirt-up replacement been undertaken. As a part of this total reconstruction, the median will be widened from 10 feet to more than 25 feet, and the on/off circular ramp at the Somerset Interchange will be relocated and widened as well. Consequently, wetlands in the vicinity will be unavoidably impacted.

"Whenever wetlands impacts are made for this total reconstruction project, which won’t happen for at least another 2-3 years, we’ll already have accounted for the mitigation," Packer pointed out. Although the total reconstruction project will by no means impact 35 acres of wetlands currently available in the bank, PENNDOT — a partner in the construction of the wetland — will use some of that acreage to mitigate its local projects.

The key benefits of building the wetlands prior to making an impact are cost and availability of property. Traditional, smaller wetlands can cost from $50,000 to $100,000 per acre to construct. But the per-acre cost for the Somerset project — due largely to its vastness — is only $2,100 per acre, resulting in significant cost savings. Also, availability of a suitable site is historically a big hurdle in constructing wetlands, but this concern is addressed because an appropriate location was discovered and acquired before the project began.

The site upon which the wetland was constructed was farmland that the Turnpike acquired from the property owner. Prior to serving as a farm, however, the property had been a natural wetland — a huge advantage because scientists knew that the soil and geology of the site could already support a wetland.

"First, we eliminated the manmade drainage system that had been installed some 30 or 40 years ago to draw off the surface water and allow for crop production at the site," Packer said of the construction of the wetland that began in June 2000 and was completed in September. "Then, we constructed low, earthen embankments — totaling about 1 mile in length — to retain rainwater and runoff."

PENNDOT equipment operators, under Packer’s direction, created islands, fingers and moguls from existing topsoil to increase habitat diversity. Shrubs and trees were transplanted from the surrounding woodlands, and snags (dead trees), boulders and nesting boxes were added to provide immediate wildlife shelter.

After that, Packer said Mother Nature finished the job. The rains filled in nicely, and natural wetland foliage — the seeds of which had laid dormant beneath the soil for many years — emerged shortly thereafter.

In the ensuing months, various conservation and wildlife clubs and agencies from in and around Somerset have visited the site to make improvements such as adding more nesting boxes, planting additional wetlands grasses and setting up decoys to attract wetlands and migratory bird species.

"The Somerset project has really evolved, in a very short time, to a top-notch example of what a wetlands should be," Packer concluded. "You could safely say that it’s the best manmade wetlands ever created in Pennsylvania."