Tuesday, September 10, 2024
3:15 PM - 3:45 PM
Tackling Inflow and Infiltration; When the Public Doesn’t Approve
Rehabilitation - CW

The Problem on Signal Mountain The Hamilton County Water and Wastewater Treatment Authority (HCWWTA) faces increasing population and regulatory requirements on Signal Mountain, where they own a 42-mile sewer collection system in difficult terrain and shallow bedrock. Ten percent of this aging system sits along, or even in, creeks, making it prone to inflow and infiltration (I/I). As a result, the system experiences sanitary sewer overflows (SSOs) that contaminate creeks and popular swimming holes, and visibly disrupt the beauty of iconic hiking trails. During wet weather, the wastewater treatment plant also receives peak flows up to ten times the dry weather flow. Jacobs identified solutions for I/I removal including installing low pressure sewer systems throughout areas that contributed to the high I/I and installing two pump stations within a park to abandon the problematic sewers in the creek. To increase public buy-in during 2023, the Jacobs/HCWWTA team addressed the impact to the community during surveying and geotechnical services, prioritized buy-in from key stakeholders and planned for public meetings and doorknocking education events. Public meetings were met with high scrutiny and pushback from the larger community for the proposed solutions. Additionally, doorknocking efforts for low pressure conversions began in Fall of 2023 with a great amount of push back from the homeowners. This began causing issues with the overall project schedule and budget. To remove I/I and solve the issues at the wastewater treatment plant, the solutions had to change. The Challenges: Public Communication and TDEC Permitting The HCWWTA implemented a two-part communication plan to educate the community on the benefits of removing I/I from the system with the proposed solutions. If the proposed solutions could not be implemented, then the alternatives would be highly disruptive to the community and to the creeks. The major message was that the HCWWTA wanted to avoid doing work in the creeks as to not disturb the natural beauty of Signal Mountain. The construction of new pump stations would result in low disruption to the community as they are on the edges of the park. While the 300 homes receiving low pressure grinder pumps would be slightly more disruptive – at least we wouldn’t be in their backyards and in the creeks, right? Unfortunately, the other solution for removing I/I is performing trenchless rehabilitation techniques such as using cured-in-place pipe and point repairs which could involve a heavy amount of tree clearing, creek disruption, and issues with access. The majority of the backyards on Signal Mountain have creeks where the sewer pipes sit and this alternative is going to create a massive amount of disruption. HCWWTA and Jacobs are currently collecting data for habitat assessments and coordinating with TDEC to ensure that the proper permitting is executed for these solutions such as Aquatic Resource Alteration Permits (ARAP).