The Maine Department of Transportation is seeking a permit from the U.S. Army Corps of Engineers to excavate and place fill material below the high-tide line in Marsh River in Newcastle to stabilize and protect the support structure for the Route 1 bridge in Newcastle that spans what is now the Marsh River. The secondary intent of the project is to support the restoration of the upstream marsh by improving tidal flow and flushing into and out of what is now known as Sherman Marsh.
Sherman Marsh was until recently better known as Sherman Lake. The lake was created in the 1930s when the Marsh River was impounded when a causeway to carry Route 1 was built over the river. In the early 1960s a new, elevated Route 1 was constructed over that causeway dam. And so Sherman Lake remained a lake until October 2005, when a dramatic rain storm caused the dam to fail and reopened the marsh to the tides for the first time in over 70 years. Since the dam was breached in 2005, the tides and river have continued to erode the banks of what once was the dam, exposing the bridge supports, and so MaineDOT plans to enlarge the outlet channel and stabilize the bridge supports.
“By improving the hydraulic connectivity between the marsh and the downstream Marsh River, we can restore the marsh,” said Charlie Hebson, chief hydrologist for MaineDOT. “The potential is there to restore as much as 217 acres of marshland.”
The proposed work will include excavating two channels between bridge footings beneath the bridge and stabilizing the channels with stone riprap. Approximately 3,000 cubic yards of earthen fill and the debris of the former dam structure will be excavated and removed to an upland, non-wetland location. About 1,075 cubic yards of stone riprap will be placed below the high-tide line to stabilize the channels.
In order to access the construction site, MaineDOT is proposing a temporary access road extending across the stream from the east shore to the west consisting of two or three large-diameter steel pipes placed in the stream channel and covered with stone to provide a travel surface for construction equipment. As part of the final site stabilization, a hand-carry boat launch will be constructed on the upland, immediately adjacent to the eastern stream channel.
Excavation and filling will directly impact 12,000 square feet of Essential Fish Habitat for various species and life stages. This habitat consists of tidal stream bed composed of sand, gravel, and stone debris, primarily a result of the 2005 failure. The construction activity is expected to result in short-term turbidity with minimal impact to fish. In the long term, MaineDOT says it anticipates some improvement to fish passage and overall habitat and improvement in water quality. The Corps has made a preliminary determination that the site-specific adverse effect will not be substantial.
A permit for this project from the Corps of Engineers is required under the Clean Water Act, which regulates the discharge or fill of material in United States waters, including wetlands; and under the Rivers and Harbors Act, which provides for federal regulation of any work in, or affecting, navigable waters of the United States. Public comments (reference File #NAE-2008-01690) should be sent by no later than July 9 to U.S. Army Corps of Engineers, New England District, Maine Project Office (ATTN: Jay Clement), 675 Western Ave., #3, Manchester, ME 04351 — or via e-mail to jay.l.clement@usace.army.mil. More information is available from Permit Project Manager Jay Clement at 623-8367.
Wetland Mitigation Bank—
MaineDOT says it plans to conduct the restoration of Sherman Marsh as a “departmental mitigation banking initiative,” and that by establishing a “mitigation bank,” it hopes to use that restoration to help mitigate other MaineDOT projects in the midcoast area.
In order to etablish an “Umbrella Wetland Mitigation Bank, with the entire state of Maine as a service area,” MaineDOT applied in May to the Army Corps of Engineers for authorization. According to the Corps, “the purpose of the umbrella bank will be to provide a framework within which future restoration, creation, enhancement, and/or preservation projects will be made available as potential mitigation for transportation projects affecting waterways and wetlands.” According to MaineDOT’s Deane Van Dusen, the purpose of the bank is to conserve the values and functions of wetlands that may be diminished or eliminated in future DOT construction projects in the state. According to the EPA, a wetlands mitigation bank is a wetland area that has been restored, created, enhanced or preserved, providing compensation for unavoidable impacts to aquatic resources.
To read MaineDOT’s prospectus, go to the Army Corps of Engineers’ New England District public notices Web site, www.nae.usace.army.mil/reg/pubnot2.asp. Public comments on it should be submitted in writing by July 10 to Ruth Ladd, U.S. Army Corps of Engineers, 696 Virginia Rd., Concord, MA 01742-2751; or e-mail ruth.m.ladd@usace.army.mil. For more information, call Ladd at 978-318-8818 or 800-343-4789.