EPA published a Report to Congress, in 2004, on the impacts and control of combined sewer overflows (CSOs) and sanitary sewer overflows (SSOs). This report was published to comply with a request from Congress. This report summarizes what is known about the characteristics of CSOs and SSOs, the human health and environmental impacts of CSOs and SSO, and the resources spent and technologies used by municipalities to reduce the impacts of CSOs and SSOs. This report makes clear that EPA views CSOs and SSOs as threats to human health and the environment. This Report provides interested parties with a wealth of information on the impacts of sewer overflows and establishes a baseline of data for regulatory agencies to use in policy making related to the management of sewer collection systems.
The report highlights several agencies and how they are managing CSO’s and SSO’s, including our founder, Darrell Gadberry’s, highly progressive program at Fort Worth.
Responsible Agency: City of Fort Worth
Population Served: 880,000
Service Area: 291 sq. mi.
Sewer System: 2,589 mi. of sewer
For the full doc, download here and “search” for Fort Worth inside the doc.
Sewer Maintenance & Service Program
The City of Fort Worth Water Department created a Preventative Maintenance Section and a Technical Service Section in 1998. The Preventive Maintenance Section was tasked with implementing a system-wide small diameter (less than 18 inches) sewer cleaning and inspection program. Larger pipes are cleaned and inspected by private contractors, due to technical logistics and the specialized equipment needed. The Sewer Maintenance Section handles all other sewer maintenance activities such as cleaning blockages, and pipe installation and repair. The sewer system is divided into nine major drainage basins containing 167 subbasins. Each subbasin, along with its SSO and maintenance histories, is tracked in a Geographic Information System (GIS) database. Spatial analysis based on information from the GIS database and baseline performance criteria is used to prioritize the cleaning and inspection of the subbasins. Once a subbasin is selected for cleaning, approximately two-thirds of the cleaned lines are evaluated by CCTV. This information is used as part of the decision making process for determining whether or not further maintenance is needed. During 2001-2002, 176 miles of pipe were televised. The cost for inspection of small diameter sewers by city employees was $0.48 per linear foot including labor and equipment.
Sewer Cleaning Efforts
The City of Fort Worth’s sewer system consists of approximately 2,589 miles of pipe. The pipes range in size from 6-96 inches in diameter. Ninety percent of the system is composed of pipes with diameters of18 inches or less. The city has established maintenance goals which include cleaning all sewers 18 inches or smaller once every eight years and all sewers larger than 18 inches once every 15 years. The cleaning and maintenance of the smaller diameter pipes is conducted by city employees, while the cleaning of larger diameter pipes is outsourced due to technical logistics and the specialized equipment needed. The sewer system is divided into nine major drainage basins containing 167 subbasins. Each subbasin, along with its SSO and maintenance histories, is contained in a Geographic Information System (GIS) database. Spatial analysis of the GIS database is compared to baseline performance indicators to prioritize the cleaning order of the subbasins. In 2001-2002, 1.15 million linear feet of pipe were cleaned by the city. The cost for city cleaning activities during this time, including labor and equipment, was $0.61 per linear foot (in 2002 dollars) and the cost for cleaning of larger pipes by private contractors was $1.02 per linear foot (in 2002 dollars).