Somerton Wastewater Master Plan

Somerton, AZ


PACE prepared an updated Water and Wastewater Master Plan for the City of Somerton. The Wastewater Master Plan assessed the City’s existing and projected wastewater generation against the existing sewer infrastructure, such as the collection systems, sewer lift stations, and wastewater treatment systems, to determine whether the existing capacity and treatment processes will meet the City’s current and future wastewater treatment needs. PACE developed a wastewater model to identify flow capacity within the existing collection system using a Geographic Information System (GIS). Field verification and calibration identified and verified the existing pipe dimensions and material, existing locations of equipment, pipelines, valves, meters, etc., flow and pressure within force mains, and quantity and capacity of equipment. PACE developed a GIS database from existing GIS data, existing CAD drawing files, and field survey of the City facilities. The GIS included flow connectivity, similar to third-party modeling software such as SewerGems, but without the high sticker price. Python scripts and geoprocessing tools were used to place all pipelines in the appropriate flow direction based on upstream and downstream connection points.  PACE worked closely with the City to verify indeterminate directions and pipeline locations.


PACE was able to determine flow capacity based on the pipe size, roughness coefficient, and slope, all attributes within the GIS. For comparison, PACE connected all sewer mains with laterals using unique IDs, then connected the laterals to the associated customer’s parcels. A cumulative flow was generated using the parcel to lateral to connect over 3,896 existing and future development parcels within the GIS to determine actual flow. With the actual flow and capacity both quantified within the GIS, PACE was able to demonstrate where capacity issues existed within the system. Additionally, the database allowed input of future wastewater generation based on population projections, zoning, and general plan estimates. Multiple build-out scenarios helped determine where the City needed to focus on making improvements to the system.


Key Features:

  • GIS database schema development: data conversion
  • Geometric network development
  • Based inventory of customer sewer generation
  • GIS capacity analysis tool and dynamic display

City of Somerton

GIS Data Management, GIS Water Resource Applications, Hydraulics Automation and Analysis, Hydrology, Wastewater Infrastructure