McMahon & Mann prepared design plans for a 600-foot-long sheet pile wall constructed at Niagara Mohawk’s headquarters in Syracuse, New York. Niagara Mohawk’s parking lot was impacted by polyaromatic hydrocarbons resulting from former coal gasification at this site. In addition to the need to prevent contamination from seeping into Onondaga Creek, the existing wall was failing and could not adequately support the parking lot.

We worked closely with Niagara Mohawk to design the wall. The wall is 15 to 18 feet high and includes an anchored sheet pile wall at the ends and a cantilevered wall along most of the length.

The cantilever design was necessary to avoid excavation into the potentially contaminated soils behind the wall, which would occur during anchor construction. Flowable fill, a mixture of cement, fly ash and water was used to backfill the space between the crumbling stone wall and the new sheet pile wall.

Herbert F. Darling, Inc. constructed the wall in 1996 and a photo of the completed wall is shown above.