Concrete Cloth Stormwater Infrastructure

Washington, DC
GeoSpray® Geopolymer Mortar: 72" Brick Sewer Rehabilitation

Project Overview
DC Water’s engineering group implemented a pipe entry inspection after receiving an alert from the District Department of Transportation (DDOT) to verify the integrity of a 72” diameter brick sewer.  This was located at the F Street NW block between 12th and 11th streets. DDOT had done a bore-hole inspection at a street depression, which revealed a 20-inch deep void under the pavement.  

Prior to entering the sewer, DC Water evaluated its records and noted the Metro subway tunnel runs below the length of 12th Street and the 72” brick sewer runs above the tunnel. In addition, in the 1970s, a 188-foot section of the 72” brick sewer was offset and replaced with 205 feet of 72” reinforced concrete pipe (RCP). The entry inspection showed the replaced 72” RCP was in great shape, but the original brick sewer was not. Starting at the interface with the RCP, the brick crown was cracked and propagating east toward 11th Street and west toward 13th Street. It was considered that the cracking likely developed after the construction of the Metro Subway system.

The most severe damage was located between 12th and 11th Streets where the crown was cracked and missing bricks. Fortunately, there was no significant oval deformation, and there were not many open mortar joints, which would be typical of an impending pre-sink-hole collapse scenario.

Read the full case study here.

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