2,000-Acre Watershed

New Rochelle, NY

The City of New Rochelle selected H2M to design improvements to existing drainage systems that serve a 2,000-acre watershed.

The existing drainage system encompassed more than 5,900 linear feet of storm drain pipe that ranged in size from 12 to 66 inches in diameter, including a 55” x 38” box culvert. Improvements were required to address significant flooding events within residential communities that occurred in 2007. A series of storms resulted in many homes and streets being flooded due to a drainage system that lacked the capacity to convey the intense rainfall. Portions of the existing drainage system were more than 100 years old and the system had been modified and extended numerous times since its original construction. As a result of this “piecemeal” construction, numerous types of unorthodox construction methodologies were utilized to connect the various sections of the drainage system.

Record plans were contradictory, so H2M staff conducted an accurate inventory and field survey of the existing drainage systems. This included a physical observation of each accessible catch basin, manhole and junction box in order to verify pipe sizes, pipe routing, and inverts. To supplement the visual observation, video observations and tracing dye were utilized to confirm pipe routing in areas where record information was unreliable or could not be field verified. Once an accurate plan was developed for the existing system, appropriate improvements were designed based on a recent drainage study conducted by the City. Design improvements included combining parallel drainage lines, increasing pipe capacities and improvements to various drainage structures to improve hydraulics of the piping system. H2M prepared plans and specifications, and provided construction administration and observation services for the project.

Awards
ACEC New York – Platinum Award