Quarterly inspection shows crack in landfill berm

by Town Reminder

Design team says its not a concern

By Kristin Will
Staff Writer

SOUTH HADLEY – Differential settlement is the cause of a crack which formed in the landfill’s Cell 2D stage 2 Mechanically Stabilized Earthen [MSE] berm.
Discovered through a Massachusetts Department of Environmental Protection [DEP]-required quarterly inspection in December, the crack is located in the pavement of an access road on top of the Cell 2D vertical expansion which was constructed in the spring of 2011. The crack cannot be seen on the exterior facing of the MSE berm, as it lies underneath the access road.
ARM Group Inc., the design engineers of the project, said at an April 10 Selectboard meeting they anticipated some settlement to occur in the structure, especially because of the site location. The landfill sits on old, buried materials from the town’s former dump. “We knew this was going to settle,” said Brian Wheeler of ARM. “That’s why we selected a MSE berm – it’s a pliable structure. This is the type you would use at this site.”
The berm is rotating slightly inward, which Wheeler said is normal. “If we had seen the berm show any indications of moving outward, that would be something that would raise red flags.” The interior portion of the berm has settled more than its exterior, which Wheeler surmises contributed to the crack.
An extensive investigation was performed by ARM of control point and settlement data, said Wheeler. “We have a lot of monitoring points on these berms.”
In order to repair the crack, ARM engineers recommended it be filled with grout to prevent any water from seeping through. “You don’t want water to get down into your berm,” said Wheeler. The crack was grouted and sealed, and ARM has continued to monitor the problem site. A follow-up inspection of the site has not indicated any other cracking or anything else “that would warrant further concern,” said Wheeler.
Information about the crack and subsequent repair was submitted to the DEP in January. This same information was also disseminated to Department of Public Works officials as well as the town.
Although the DEP did not certify the work performed by ARM, it did look into the repair process and asked ARM to perform additional monitoring to collect data in the area of where the crack was located.
“We did not want to wait,” said Wheeler of their decision to move forward with the grouting process. “We took the appropriate action.”
DEP officials also asked for an independent engineer to review ARM’s recommendation and repair and provide an assessment. Wheeler said that third party review is in progress. The data collected from the additional weekly monitoring has been reviewed by the DEP.
As for the settlement of the berm, Wheeler said, “We don’t see any cause for concern” and reassured the Selectboard there was no additional problematic movement within the berm. “We really view this as a maintenance issue,” he said. Design officials will continue to monitor the area, as well as conduct the quarterly monitoring.
The town receives monthly reports of landfill operations.