Wastewater collection and conveyance
systems have long been a neglected component of many
municipal wastewater systems, due to a lack of funding
and management focus. Increased population growth has
resulted in increased wastewater flows. Aging systems
may not have hydraulic capacity to receive the increased
flows due to a large volume of Infiltration and Inflow (I/I)
and lack of periodic maintenance. This may result in a
Sanitary Sewer Overflow (SSO) to receiving waters.
With the implementation of the Total Maximum Daily
Load (TMDL) program and watershed protection
programs, SSO events have received increased attention
from regulatory agencies. Utilities are required to record
the events and estimate the volume of the spills as they
occur. The purpose of the evolving Capacity,
Management, Operations, and Maintenance (CMOM)
program is to minimize SSO events by requiring that each
wastewater utility develop a comprehensive program. A
response plan is still needed, however, a response plan to
address the negative impacts of SSO events to receiving
waters.
Fulton County, Georgia (the county in which the bulk of
the City of Atlanta is located), operates a 45-million
gallons per day (MGD) wastewater system consisting of
16 sewersheds, 5 treatment plants, 45 pump stations, over
300 miles of pipelines, and over 42,000 manholes. The
system primarily serves residents in the unincorporated
portions of the County in areas to the north and south,
effectively bisected by the city limits of Atlanta, which
operates a separate system. The County is currently
developing several action plans in response to CMOM
requirements. These include development of a
comprehensive sewer system collection system model and
master plan, implementation of a comprehensive
maintenance program, replacement or rehab of key
conduits, and upgrades at pump stations. It is the goal of
the County to become more proactive in terms of its
activities instead of reactive; however, again a response
plan was needed, and in fact required for SSOs.
MACTEC assisted Fulton County in developing a
procedure for responding to SSO events in isolated water
bodies such as lakes and wetlands. This methodology
uses a simple series of charts to simplify the calculation of
carbonaceous and nitrogenous Biochemical Oxygen
Demand (BOD). The process takes as an input the
volume of the water body and the volume of the spill, and
estimates the size and schedule of run times for aeration
equipment deployed in response to the SSO event.
Several iterations of this procedure were developed to
simplify the method in application in the field. MACTEC
developed and conducted a series of training classes with
Fulton County’s sewer collection system personnel.
Despite technological and learning differences, the sewer
collection system personnel provided valuable feedback
on the method and on the state of the system. As the
CMOM program evolves, it will be important to consider
some of the lessons learned from operational personnel to
ensure effective implementation.Sponsored by:
Georgia Environmental Protection Division
U.S. Geological Survey, Georgia Water Science Center
U.S. Department of Agriculture, Natural Resources Conservation Service
Georgia Institute of Technology, Georgia Water Resources Institute
The University of Georgia, Water Resources Facult
