Dams — Walden Pond Spillway Channel Reconstruction

SAUGUS, MA — T Ford Co. Inc. constructed a new emergency spillway discharge channel for Walden Pond Dam. The dam is 2000 ft long and has a hydraulic height of 25 ft. The spillway was severely damaged during the Mothers Day storm in May 2006 and resulted in erosion near the toe of the earth embankment. The reservoir created by the dam impounds acre ft. of water for the City of Lynn water supply.

The new spillway channel consists of a combination of grouted riprap and a cast in place reinforced concrete training wall. Construction of the training wall at the toe of the dam required a temporary earth support system. T Ford Co. Inc. designed and installed a soldier beam and lagging system for temporary earth support. Steel pipe piles were drilled and grouted into the underlying rock to provide cantilever soldier piles. Steel road plates were used to span between the pipe piles. The system was successful in providing temporary support for excavation for the new training wall.

Access to the spillway channel was provided by a temporary earth ramp from the end of the dam crest. All materials had to be staged in small quantities on the crest and loaded onto a track mounted dump truck for hauling to the work area as needed. The new channel included an under drain system and work progressed from the bottom up the channel, completing the full cross section as it went since it was not feasible to travel over completed work. The project was completed on schedule.