Background: The Hamilton County WWTA conducted permanent flow monitoring studies and sanitary sewer evaluation surveys (SSES; including smoke testing, manhole inspections, closed-circuit television inspections, etc.) within the WWTA East Ridge service area as a part of the process of identifying priority projects and areas for infiltration and inflow (I/I) reduction to address Sanitary Sewer Overflows (SSOs).  Upon completion and analysis of the investigations, the WWTA identified East Ridge Basins 01B, 03A, 03C, 04B, 05, and 10 as priority areas. The WWTA also discovered that multiple pipelines crossing and located near the I-75, Exit #1 Interchange in East Ridge were undersized and severely deteriorated. Repairing the assets within the identified areas could result in a substantial reduction in the amount of excess flow entering the system and resulting Sanitary Sewer Overflows (SSO’s) in both WWTA’s and the City of Chattanooga’s collection system. A brief scope of work for each project designed to rehabilitate the priority areas have been provided below.

Recent Improvements (Completed Projects):

WWTA Project No. 16-317: East Ridge Basin 10 Sanitary Sewer Rehabilitation:  The East Ridge Basin 10 Sanitary Sewer Rehabilitation project was a project designed to repair assets within East Ridge Basin 10 identified by flow monitoring and sanitary sewer evaluation surveys (SSES) to reduce the amount of inflow and infiltration during heavy rain events to increase capacity and minimize Sanitary Sewer Overflows (SSOs). The project consisted  of the rehabilitation of approximately 20,190 linear feet of gravity sewer pipe ranging from 6-inch to 18-inch, 16 electrofuse coupling laterals, 66 open cut lateral replacement repairs, 181 cured-in-place pipe top hat lateral repairs, and 222 cured-in-place pipe full wrap t-lateral repairs. The project also consists of 16 mainline sewer point repairs ranging from 6-inchto 18-inch gravity sewer pipe, 5 mainline cured-in-place pipe sectional liner of 8-inch gravity sewer pipe. Manhole work consists of 3 vertical feet of 24-inch diameter manhole lining, 12 vertical feet of 36-inchdiameter manhole lining, 1,473 vertical feet of 48-inch diameter manhole lining, 7 vertical feet of 66-inch diameter manhole lining, 4 bench and invert repairs, 112 pipe connection grout repairs, 1 plugging of abandoned lines, 15 inflow dishes, 4 raise to grade repairs, 9 replace frame and cover repairs, 9 boltdown covers, 21 watertight frame and covers, 3 realign and seal frame repairs and 5 chimney seals. The project was completed in November of 2020 and had a total project cost of approximately $7,248,536.16.

Current Improvements (In Construction):

WWTA Project No. 18-320: East Ridge I-75 Collector Sewer Project: Upon completion and analysis of flow monitoring and sanitary sewer evaluation surveys, the WWTA determined that a new collector sewer would be required to replace the existing collector sewer serving East Ridge Basin 10 that was installed in the 1950’s. The East Ridge I-75 Sewer project was designed to replace the aged infrastructure while concurrently reducing the amount of inflow and infiltration during heavy rain events to increase capacity and minimize Sanitary Sewer Overflows (SSOs). The project consists of constructing approximately 2,600 linear feet of open cut 16-inch ductile iron gravity sewer, 650 linear feet of 16-inch ductile iron gravity sewer associated with jack and bore installation with 600-linear feet of 30-inch steel casing pipe, 1,800 linear feet of open cut 12-inch ductile iron and PVC gravity sewer, 200 linear feet of open cut 8-inch PVC gravity sewer, and the installation of associated precast sewer manholes with watertight frame and covers. The project is currently in construction with an anticipated completion date of Spring 2022 and has a total estimated project cost of approximately $3,307,322.23.

WWTA Project No. 18-323, Phase I: East Ridge Basins 3C & 4B Sanitary Sewer Rehabilitation: The East Ridge Basins 3C & 4B Sanitary Sewer Rehabilitation is a project designed to repair assets within East Ridge Basins 3C & 4B identified by flow monitoring and sanitary sewer evaluation surveys (SSES) to reduce the amount of inflow and infiltration during heavy rain events to increase capacity and minimize Sanitary Sewer Overflows (SSOs). The project consists of the installation of approximately: 35,165 linear feet (LF) of Cured-In-Place Pipe (CIPP); 755 LF of open-cut 8-inch gravity sewer replacement;  1,465 LF of 6-inch to 8-inch gravity sewer pipe bursting; 465 LF of slipliner removal; 50 LF of sectional open-cut replacement of 6-inch gravity sewer; 30 mainline sewer point repairs in 6-inch, 8-inch, and 10-inch gravity sewer pipe, and 20 mainline sewer point repairs at lateral connections; 450 service lateral reinstatements with CIPP liners; 65 open cut service lateral replacements; and 5 electrofused lateral reinstatements. Manhole work consists of: Six (6) 48-inch diameter manhole replacements; 140 replacements of frames and covers on existing manholes; 1,540 VF of 48-inch diameter manhole lining; 10 pipe connection grout repairs; 10 bench and invert repairs; and 40 prep and re-lining of manhole connections. The project is currently in construction with an anticipated completion date of Summer 2022 and has a total estimated project cost of approximately $6,976,980.00.

Planned Improvements:

WWTA Project No. 18-323, Phase II: East Ridge Basins 1A, 1B, 3A, 5, and 8A Sanitary Sewer Rehabilitation: Phase II of WWTA Project No. 18-323 is a selective sanitary sewer rehabilitation project designed to utilize the remaining State Revolving Fund loan budget to complete cost-effective repairs to defects identified by flow monitoring and sanitary sewer evaluation surveys (SSES) within East Ridge Basins 1A, 1B, 3A, 5, and 8A. This project will consist of approximately: 1,664 linear feet (LF) of Cured-In-Place Pipe (CIPP), 212 linear feet (LF) of mainline open cut repairs, 156 service lateral repairs, 45 surface manhole repairs, 3 point repairs, and 429 vertical feet (VF) of subsurface manhole repairs. Construction is anticipated to begin in Fall of 2022 with an estimated completion date of Summer 2023. The total design and construction cost for Phase II of WWTA Project No. 18-323 is projected to be approximately $3,529,352.00.