Hydraulic Analysis Methodologies for Urban Development Areas

Washington Suburban Sanitary Commission (WSSC) is among the largest water and wastewater utilities in the United States, serving approximately 1.9 million residents in Montgomery and Prince George’s County, Maryland. WSSC’s Development Services Division (DSD) has used different methodologies for the last 40 years to analyze the capacity of the water system for new developments. DSD uses Hydraulic Benchmarks, skeletonized models, and a modified all pipes water model developed by WSSC’s Planning Division to do these hydraulic analyses. The Planning all-pipes model has been used primarily for Master Planning and provide support to different stakeholders in WSSC, such as Water Condition Assessment, Operations, and Asset Management. WSSC has decided to compare the different methodologies and a start to build a new all-pipes model that better reflects the changes in demand allocation, pipe roughness, and capacity. This paper will discuss the different methodologies and what are the next steps to update the all-pipes water model and calibrate it.