Friday, February 2, 2001
ConsCom explores affordable options for Greenough dam repair
Following receipt of five engineering service proposals from firms interested in designing and overseeing repair of the 300-foot Greenough Dam, the Carlisle Conservation Commission (ConsCom) decided to broaden negotiations with Stevens Associates Consulting Engineers (SACE). The need to renovate the 70-year-old man-made earthen structure or to contemplate the loss of the 21-acre pond behind it became obvious last fall following an inspection by the state Department of Environmental Management (DEM). Their report found the dam to be "in fair to poor condition" and recommended that the cited deficiencies be attended to "at your earliest opportunity."
Commissioner Eric Jensen who, along with commissioner Christine Gaulden and administrator Sylvia Willard, has accompanied engineers from Stevens and the other firms, listed four options as available to the town at the January 25 ConsCom meeting: 1) build a virtually new dam, 2) make serious repairs to minimize recurring problems, 3) handle emergency problems only as they arise and 4) let the dam go and lose the pond. Jensen found option one fiscally impossible and option four counter to public sentiments. His strong recommendation was that the commission push for the second alternative as the best long-range approach. Greenough Land abutter Harvey Nosowitz seconded that solution "not only for environmental reasons but also because I fear an unpredictable impact on people living near Pages Brook if the dam goes out."
The initial step in the project as outlined in the DEM report called for retention of "a professional civil engineer experienced in the construction and repair of dams," now SACE, to determine the actual repair requirements. Those were presumed to include the clearing of trees and brush from the dam and its downstream outflow area. Also anticipated were a study of the hydrology and hydraulics in relation to the spillways, and construction specifications for the town's use in soliciting contractor bids. After the necessary repairs are carried out, the state advised that the town engineering firm develop an operation and maintenance plan and handbook for continued preservation of the dam.
The cost of fulfilling its prescribed role has been estimated by SACE at approximately $13,000. However, the commission urged the subcommittee to continue discussions with the engineers to identify possible cuts or staged implementation of the overall project.
One important question pursued by Willard is the extent to which the department of public works (DPW) might be able to carry out a major portion of the repair work under direct engineer supervision. According to Willard, DPW head Gary Davis has indicated willingness to consider that approach. The present tenant in the Greenough farmhouse has volunteered to help cut down the 50 or so trees with six-inch or larger trunks now growing on the dam itself. This would leave the DPW with the task of removing the stumps and roots with existing equipment and filling in the holes that would result. Either leaving them in to rot or just pulling them out would leave the dam "no better than a strainer" to quote one ConsCom member. The commission and the town are clearly facing a complicated problem with a formidable price tag.
© 2001 The Carlisle Mosquito