Friday, November 15, 2002
ConsCom OKs Maple Street repair plan
Replacement of the collapsed culvert that has blocked Maple Street to through traffic since May moved closer to a predicted end-of-the-month completion date at the conservation commission's November 7 meeting. In the second of two public hearing segments, the board gave final approval to engineering specifications prepared for the Carlisle Department of Public Works (DPW) by Landtech Consultants, Inc. The commission's okay was particularly important to this project because of its location in the riverfront area of Pages Brook, and because the work must proceed within the wetland itself.
Engineer Mark Sleger indicated that the failed eight-and-a-half-foot corrugated culvert will be replaced by a 16-foot, pre-cast concrete structure with new headwalls. Footings can be installed with the present culvert in place until the last minute.
DPW superintendent Gary Davis was happy to report that the beaver dam on the upstream side could also remain in place. "It will make an excellent cofferdam and will really help us out," he said. He noted further that nature's furry engineers had not been busy in that area recently and appeared to have moved construction downstream. So far the DPW has eliminated only asphalt from the site to keep it out of the wetland. Davis seemed confident that the structural work could be completed in about a week once all the materials are on site. If the weather cooperates, the road can then be paved, although that is not critical.
Speaking as an inveterate birdwatcher, commissioner Tom Brownrigg sought and received assurance that there will be sufficient space on the roadway atop the culvert for pedestrians to watch for bird and animal life in the wetlands on either side. For his part, commissioner Peter Burn was concerned that canoes should still be able to pass under the structure. Sleger promised him plenty of headspace.
Returning to engineering con-siderations, conservation administrator Sylvia Willard asked whether a private dam upstream of the culvert had been taken into account, particularly in the event of an unusually heavy storm that might wash it out. Sleger answered in the negative, noting however that, "We're talking about a sizeable watershed that should be able to handle almost any foreseeable volume." Still a bit uneasy, chair Chris Kavalauskas wondered what the effect of a breach upstream might have on the Greenough dam. Sleger replied that the large flood plains on either side of the road were about equal and, in his opinion, there should be no problem. Apparently reassured, Kavalauskas closed off further conjecture with the observation that, "If there's a 100-year flood, the water is going to go over the road anyway."
The commission closed the public hearing and issued a standard order of conditions, adding only that all accumulated silt and sand should be removed, heavy siltation barriers installed and provision made for easy future monitoring of sediment accumulation.
© 2002 The Carlisle Mosquito