Sewer separation is a traditional combined sewer overflow (CSO) mitigation technology and has been proven effective in numerous applications. However, it is also well known based on experience in the industry that it is not universally cost-effective, as the effectiveness of separation varies based on the relative relationship of numerous factors in any given sewershed.
SD1 is applying sewer separation strategically and opportunistically, and only in those areas where it is a cost-effective component of the overall CSO mitigation approach.
SD1 has identified seven such sewer separation projects in the combined sewer system as part of the improvements scheduled under the first milestone of the Amended Consent Decree - to be implemented by 2023.
The Jacob Price Phase 2, Church Street Phase 2, Water’s Edge, Aqua on the Levee (initial phase) and RiverCenter separation projects have already been completed, and separated approximately 65 acres of pervious and impervious area. These projects removed approximately 36 million gallons of runoff from the combined system in a typical year.
The SR9 and Washington Street/Saratoga (Aqua on the Levee Phase II) projects will be completed in 2020, and will separate approximately 38 acres of pervious and impervious area, removing approximately 19 million gallons of runoff from the combined system in the typical year. All seven separation projects are projected to reduce CSO volume by approximately 49 million gallons in the typical year.