Emergency Slope Repair using Reinforced Soil - Gill, Massachusetts-PPT Presentation

PPT Presentation

Pdf Summary

A severe rainstorm on July 21, 2023—2.76 inches in three hours—caused a roughly 75-foot-high slope failure beside Route 2 in Gill, Massachusetts, closing a major east–west transportation route.<br /><br />MassDOT, contractor Northern Construction Services, and engineer Geosciences Testing and Research responded with emergency roadway support and slope reconstruction. Drone LiDAR surveys documented the failure and helped establish repair limits. A temporary support system was designed to reduce further erosion and limit traffic and soil loads on the remaining slope, while allowing Route 2 to reopen with two-way traffic. Micropiles were drilled at least five feet into unexpectedly shallow bedrock; drilling observations also informed the geotechnical assessment.<br /><br />The final repair combined a boulder-fill base with a reinforced soil slope above it. The base used boulders weighing about 500 pounds to 8 tons, topped by a two-foot layer of crushed stone. The upper slope was built with MassDOT gravel borrow reinforced with geogrid and wrapped in modified rock fill, with drainage behind it. Environmental constraints set the bottom elevation of the repair. The project used approximately 3,000 cubic yards of excavation, 5,000 tons of boulders, 5,300 cubic yards of gravel borrow, 2,300 square yards of mechanically stabilized earth, and 1,200 tons of riprap.<br /><br />Emergency planning began immediately after the failure. Temporary support was installed between July 31 and August 20, enabling the roadway to reopen. Permanent slope repair took place from August 22 through October 26, 2023, with automated monitoring included in the project.

Keywords

Route 2

Gill Massachusetts

slope failure

rainstorm

MassDOT

emergency roadway support

micropiles

geogrid

drone LiDAR

mechanically stabilized earth