Marlay Avenue Storm Drain

Ninyo & Moore was retained to provide third-party geotechnical review services for the Marlay Avenue Storm Drain project. The project consisted of construction of a new reinforced concrete pipe that varied in diameter from 54 inches to 78 inches along the approximately 3,600-foot long, east-west alignment. The pipe invert varied along the alignment and reached depths on the order of 16 feet below the street surface. The storm drain was constructed in 1997 in the existing Marlay Avenue utilizing conventional cut-and-cover construction methods. In 1998, settlement of the asphalt concrete pavement was observed above the pipe along the west end of the alignment. This area was subsequently repaired. In 1999, additional settlement of the roadway pavement was observed in the roadway along the central portions of the storm drain alignment. Settlements and depressions in the pavement, some more than 18 inches in depth, were also observed along the alignment. Ninyo & Moore performed a subsurface evaluation along the pipe alignment, which included excavation of the trench backfill, installation of temporary shoring, and performance of in-place density tests of the trench backfill materials utilizing both nuclear gauge and sand cone test methods. Samples of the trench backfill materials were tested in our laboratory to evaluate the materials gradation, sand equivalent, and maximum density and optimum moisture content characteristics. Repair of the roadway included excavation of the trench backfill materials to the bottom of the storm drain pipe, placement and compaction of bedding sand along the sides of and above the pipe, and replacement and compaction of the trench backfill materials. Slurry was also used to backfill portions of the trench. During repair operations Ninyo & Moore provided Quality Assurance observation and testing, which included observation of the repair operations, performance of in-place density tests of the trench backfill compaction, and laboratory maximum density testing and sand equivalent testing on the trench backfill materials to evaluate the contractor's Quality Control testing program. Upon completion of the roadway repairs, Ninyo & Moore issued a written report summarizing our observations and the results of our field and laboratory testing during the repair operations.