Page 8 - May-June2018

CHATTANOOGA By Gabrielle Sobel
Progress on Sewer Improvements

Chattanooga Consent Decree treatment plant, wet-weather volume- within the city, including 80 permitted
Background reduction projects, additional reliability industries. It also provides treatment
projects and, lastly, additional focused for eight regional or satellite users
On April 24, 2013, the City of sanitary sewer evaluation surveys and comprised of approximately 25,000
Chattanooga entered into a consent rehabilitation in the remaining priority customers. The Wastewater Collection
decree with the U.S. government and basins. and Transmission System is composed
the State of Tennessee. This negotiation of 1,263 miles of gravity sewers
was reached with Tennessee Clean Wastewater Collection and (approximate), including 70 miles of
Water Network, the U.S. Environmental Transmission System Overview combined sewers; 30,000 manholes
Protection Agency and the Tennessee (approximate); 70 pump stations; 53
Department of Environment and As a regional wastewater utility, the miles of force main; eight CSOTFs;
Conservation in response to excessive city, a municipal corporation, owns, one Combined Sewer Storage Facility;
sanitary sewer overflows in the city’s operates, maintains and manages a 171 (approximate) residential/grinder
regional sewer system in violation network of pipes, manholes, pump stations; and one major regional
of the National Pollutant Discharge stations, force mains, combined sewer wastewater treatment plant (Moccasin
Elimination System permit. Phase I is overflow treatment facilities, and Bend).
performance-based lasting five years. associated appurtenances that transport
Phase II will last 11 years. Phase 1 is wastewater from homes, businesses The WCTS is divided into 12 major
estimated to cost over $300 million. and industries to the Moccasin Bend sewer basins, which are further divided
plant. All of this infrastructure is part into 105 individual sewer sub-basins for
The main goals of the consent of the Wastewater Collection and SSES analysis as shown below.
decree are to reduce wet-weather Transmission System and managed by
flows to Moccasin Bend Wastewater the Waste Resources Division. Property Rainfall and Flow Monitoring Program
Treatment Plant, improve reliability owners own the private service laterals
at the treatment plant and pump from the served residential, commercial The Phase I flow-monitoring program
stations, maximize the use of existing and industrial structures to the public had an initial flow-monitoring period to
Moccasin Bend facilities, and minimize main line in the street or right-of-way, support the development of a hydraulic
sanitary sewer overflows. Phase I including the connection. model and project prioritization. The
includes upward of 100 projects city hired ADS Environmental Services
and/or tasks such as updating the The city’s wastewater system currently to install, monitor and maintain 104
Capacity, Management, Operations serves approximately 170,000 people ADS Triton+ flow monitors, 12 ADS
and Maintenance program, land with approximately 61,000 customers RainAlert III rain gauges and 12 billing
survey and GIS development
of the city’s sewer system, a
comprehensive hydraulic sewer
model used for master planning
and other wet-weather solutions,
pump-station reliability and
upgrade projects, a green
infrastructure master plan,
long-term control plan updates,
a Moccasin Bend process control
plan, and, lastly, focused sanitary
sewer evaluation surveys and
rehabilitation in the top five worst
sewer basins.

Phase II depends heavily on
the results of Phase I but will
include an overflow solution
to Moccasin Bend’s two non-
permitted relief sites, potential
new storage facilities, combined
sewer overflow long-term control
plan solutions, a potential new

8 TPW May/June 2018