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During March 2006, heavy rains flooded three Manoa houses, resulting in large quantities of sandy debris damages to the homes. Department of Land and Natural Resources (DLNR) analyses determined that a break in curbing, as well as two water drains on Round Top Drive discharged the runoff and directed it toward houses below.

Three repair phases were implemented to correct the problem and to protect residents from future flooding.

Phase One was construction of debris catchment fences built on state lands on Round Top Drive. These fences were designed to catch sandy debris while letting water pass through. This was completed in 2007.

Phase Two included improvements to drainage systems on the affected properties to divert water away from the properties and into the city drainage system. This was completed in 2008.

Phase Three, which began in May 2010, involves installation of two dispersion channel structures along the western slopes of Manoa Valley (below Round Top Drive). The dispersion channels will be connected to two existing inlets, and will discharge culverts located along and under Round Top Drive. When completed, the dispersion channels will divert water away from private residences, and onto the hillside.

One lane of Round Top Drive is closed to traffic during the day while work is done on the dispersion channels. DLNR contractors will also repair one of the curb fences along Round Top Drive identified as a public safety hazard. After the repair work is completed, the City and County of Honolulu will maintain the dispersion channels.