In 2003, BG Consultants was retained to model Phase I of the Manhattan’s sanitary sewer collection system for the City’s master plan, including the largest sewer basin in the City of Manhattan sewer service area—the Wildcat Creek Basin. This entailed 12.5 miles of gravity sewers (greater than 8-inch diameter), 253 manholes, the Wildcat Creek Lift Station, and 611 feet of force mains.

In 2009, BG Consultants was commissioned to update the existing 2003 sanitary sewer model, incorporating the remainder of Manhattan’s sewer collection system - the North and South Airport Basin, the Central Basin, and the North Basin. The updated existing conditions collection system model includes an additional 30.1 miles of gravity sewers 10-inches or larger, 476 additional manholes, the Job Corp. lift station, and 2.4 additional miles of forcemains.

Data collection included a GPS survey of the additional manholes added to the model. Data from thirteen flow meters strategically placed around the City of Manhattan were used to calibrate existing sewer flows. Because growth and development in a community drive the need for utility service improvements, BG conducted an analysis of the collection system for existing and future (25 years) conditions.

BG’s team identified improvements for mitigating capacity deficiencies and for expanding services to new locations throughout Manhattan. This Master Plan update enabled the City’s Public Works Department Utilities Division to develop a comprehensive Capital Improvements Program (CIP) for the sanitary sewer improvements.