Emergency Retaining Wall Repair Post-Hurricane Ida

Hurricane Ida was a Category 4 hurricane that hit the Atlantic coastal region in the fall of 2021. The subsequent rainfall created flooding conditions that inundated streams and rivers throughout the state of NJ. The hurricane also tested the capacity of embankments and retaining walls and their associated factor of safety against failure, throughout the state. Specifically, the flood event from the hurricane impacted a section of gravity block retaining wall about 100 ft along Vosseller Avenue in the township of Bridgewater, NJ. Vosseller Avenue, which sits atop this retaining wall, is a vital access corridor that was closed due to the failure of the retaining wall. The main cause of failure experienced at the retaining wall was due to the sudden rise in water level causing scouring and an overflow condition that undermined and washed out the material backfill behind the wall. This sudden reduction of factor of safety due to material washout caused a base sliding failure between the wall and the rock surface it sits on. American Pile and Foundation was contacted to investigate the field condition and provide an emergency design/repair of the damaged wall section. The solution provided was a permanent cantilever wall system socketed into rock using drilled soldier pile micropiles and permanent reinforced shotcrete facing. The geology encountered at the site location was very hard igneous rock intrusion of basalt and would prove difficult to drill. Site constraints also include an adjacent gravity sewer line underneath the road that could not be disturbed. American Pile was able to expedite the design of the permanent wall system and began construction within a week of notice. The construction process encountered some difficulties with the hard rock geology and difficult access. However, APF was able to adjust the drilling method to the difficult geology and employed the overburden system with a down the hole hammer with success. The micropile soldier piles were successfully installed and socketed into the bedrock. Temporary lagging was installed to allow backfill to be placed to the existing road grade and facilitate reinforcement and placement of the permanent wall shotcrete facing. Utilizing these techniques, the wall was finished in three weeks, and the road reopened just a month after the hurricane damage.