Getting the most out of your limited CIP dollars — Wet weather storage solution to reduce CIP spending while improving performance

Sewer Utilities faced with rapidly growing demands deal with high-cost capital infrastructure projects that are necessary to sustain healthy growth in the region. Additionally, communities impacted by sanitary sewer infiltration and inflow (I/I) problems are also challenged when planning for future sewer infrastructure. These impacts result in larger proposed system capacity solutions to allocate peak wet weather flows in the sewer system. Traditional master planning for wastewater infrastructure typically recommends up-sized linear assets and pump stations to accommodate projected future flows all the way to the treatment plant. One concept that helps to maximize the capacity of existing sewer assets is the use of wet weather storage tanks for sanitary sewers. They help control the excessive I/I and prevent from oversizing linear assets and in-line pump stations. This presentation will: 1) discuss the challenges sewer Utilities are facing due to growth and aging infrastructure; 2) present the criteria used to evaluate, size, and cost both conveyance infrastructure and storage; and 3) compare proposed capital investment of traditional conveyance with that of wet weather storage. Additionally, this presentation will demonstrate important elements used to select potential storage locations, size a storage tank to meet a selected level of service (LOS), and discuss the assumptions and tools needed to present the concept of storage to the sewer utility.