Final assessment on earthen dike in Hadley nearly done

  • In this 2014 file photo, Mitch Hartley, left, and Randy Dettmers, who work for the U.S. Fish and Wildlife Service, walk the Connecticut River dike in Hadley in search of the rusty blackbird. A final phase of an assessment into the 2-mile-long earthen dike that protects portions of Hadley from possible Connecticut River flooding is nearing completion. GAZETTE FILE PHOTO

Staff Writer
Thursday, October 19, 2017

HADLEY — A final phase of an assessment into the 2-mile long earthen dike that protects portions of Hadley, including town center and a section of Route 9, from possible Connecticut River flooding, is nearing completion.

AMEC Massachusetts, Inc., based in Chelmsford, has had crews doing 34 borings and taking core samples as part of a subsurface survey in the levee and flood protection system for the past several days. This geotechnical assessment will conclude with a report analyzing the stability, seepage and settlement of the dike.

Town Administrator David Nixon said on Oct. 11 that this work will show what materials both the levee and the abandoned railroad embankment, now used for the Norwottuck Rail Trail, are made from and what their underground structures are like, and set the stage for ensuring they remain viable.

The work, at a cost of $121,000, supplements two earlier phases.

“This will help us with the fourth and final phase of the investigation, developing a maintenance and improvement schedule,” Nixon said.

The levee starts from near the intersection of Rocky Hill Road and River Drive and runs toward the Calvin Coolidge Bridge. Because the Norwottuck Rail Trail passes over a portion of it, the town has notified the Department of Conservation and Recreation about the ongoing survey.

During the previous studies, the evaluation was focused more on the dike’s surface composition and the amount of area protected by it and where flood waters might rise over it.

One of the concerns identified is the height of the levee as compared to a projected 500-year flood. AMEC identified two places where flood waters could cause problems, one on the West Street Common, the other where the rail trail passes by, Nixon said.

Nixon said the town is spending the money as part of capital plan and critical infrastructure, and is not a federal mandate, but rather a prudent, proactive effort by the town.

The dike was damaged and extensively repaired following the Great Flood of 1936 and the Hurricane of 1938. In addition, in 2009 a crack was found in a section of the dike. During repairs a section collapsed and was rebuilt.

That incident prompted a thorough analysis of the condition of the dike system including subsurface testing and recertification of the system through the Federal Emergency Management Agency.

In an earlier interview, Nixon said ensuring the town’s flood management system meets the certification requirements of FEMA would be beneficial to the town and homeowners to assess flood insurance costs and get possible federal assistance when flooding occurs.

Scott Merzbach can be reached at smerzbach@gazettenet.com.