The retaining walls at Kappock Street were showing signs of structural instability and deterioration. For safety reasons, the New York City Department of Design and Construction (DDC) determined that the walls needed to be completely rebuilt. STV provided complete engineering design services and developed a construction staging scheme for the north and south retaining walls along Kappock Street between the Henry Hudson Parkway and Knolls Crest. The firm also conducted a subsurface exploration program, which examined the soil and design parameters for both replacement retaining walls. The new walls consist of a series of precast modular concrete units. Rough and smooth surfaces on alternate horizontal columns are placed in angled patterns to add visual depth and texture which create an open feel. Wide grooves eliminate a horizontal sight line that would appear too continuous to drivers.