• Washington Suburban Sanitary Commission

    Development Hydraulic Plan Review and Analysis

    Laurel, Maryland, United States

Project Summary


The Washington Suburban Sanitary Commission (WSSC) is tasked with reviewing the hydraulic pipelines to be connected to the existing water and sewer networks in two Maryland counties. The review of the design elements is stringent and exceptionally lengthy because future growth relies on these systems. Size, system integrity, and adequate fire flow are all considered. Each year, WSSC reviews an estimated 160 large-scale development projects from planning to construction-ready status.


Replacing its small-scale, in-house software with WaterGEMS and SewerGEMS, WSSC reduced the time needed to analyze and model large networks, and identified and addressed critical issues earlier in the review process. Model scenarios were created for each development phase of a project, which allowed for easier and faster reviews of hydraulic integrity and adequacy. Any changes to original alignments were able to be rapidly reanalyzed.


With WaterGEMS and SewerGEMS, the review cycle was reduced from 73 to 27 days over eight years, despite a two-fold increase in volume of proposed pipeline extensions and connections. Workflow efficiency was improved, analysis was standardized, and quality assurance was enhanced. The improved workflow resulted in construction starting sooner, and revenue from permits and new accounts being collected earlier. Ultimately, customers connected to the system sooner and customer service improved.


WaterGEMS reduced the time needed to accurately size the pipes to meet WSSC’s system constraints and standards. The GIS tools and model builder allowed reviewers to incorporate proposed pipelines within existing developments, then run alternative scenarios to verify optimal solutions. The hydraulic models also enabled WSSC to run multiple scenarios under various system outage conditions, as well as perform fire flow analysis throughout a network to ensure adequate fire flow.

  • In addition to the annual average of 160 large-scale development projects, WSSC also reviews an estimated 172 small-site utility plans each year.
  • Implementation of WaterGEMS and SewerGEMS enabled WSSC to thoroughly review and analyze potential service outages, and better manage the associated risks.
  • The use of SewerGEMS decreased the number of sanitary sewer overflows in new development areas, while the fire flow capabilities in WaterGEMS provided fast and efficient fire flow analysis.