Regulator R4/R39 Hydraulic Analysis and Upgrades


The City of Everett is working towards compliance of its combined sewer outfalls to meet Department of Ecology requirements of no more than one overflow per year on average over a 20-year period. This project aimed to modify two existing regulator weirs to divert more flow through their Summit Interceptor and less flow towards the outfalls. The initial phase included modeling of several alternatives to optimize weir heights and configurations, and included replacement of one regulator and modifications of another. The new regulator was designed to allow for stormwater separation in the upstream basin in the future and improved maintenance access. The completed project has reduced overflows and the outfalls are now at or near compliance.


  • InfoSWMM model of a combined sewer
  • Modeling used to optimize existing infrastructure and minimize capital costs
  • Improved access and maintenance