Cleanwater History
In the 19th century, sanitary sewage was discharged directly into streams or onto open land, and the use of "outhouses" was wide spread. Eventually, people took note of the unsightliness and odors caused by discharges, and constructed combined sewers that conveyed both storm water and sanitary sewage for discharge into the Cumberland River or its tributary streams. Some of these sewers were constructed in the stream itself.
In the more rural areas of Davidson County, disposal of sanitary sewage developed from "outhouses" to septic tanks, although streams and fields were used for disposal as well. These practices continued well into the 20th century.
By 1950 the total population of Davidson County exceeded 320,000. At this time approximately 70,000 lbs/day of sanitary waste was being discharged into the environment. As a result, Nashville began construction of large interceptor sewers to transport combined sewage flows to the Central Wastewater Treatment Plant, which was completed in 1958. Other wastewater treatment plants were built in later years to serve the areas outside of central Nashville. The construction of this infrastructure was undertaken to reduce impacts from septic tanks and to remove as much pollution as possible caused by the discharge of sanitary wastes into the Cumberland River and its tributaries.
While dramatic improvement was made in the reduction of pollution impacts on the environment between the 1950's and early 1980's, Nashville experienced explosive growth. By 1985 the population served by the Metro Department of Water and Sewerage Services (MWS) grew to over 500,000. In 1985, the Commissioner of the Tennessee Department of Environment and Health (TDEH) issued an Order to the Metro Government requiring the development of a plan to eliminate pollution caused by Combined Sewer System Overflows (CSOs). MWS worked with a consultant to perform a study and develop a plan. Meetings between MWS and the TDEH were held to develop compliance milestone dates based on the results of the 1988 study; and negotiated milestones were finalized in 1989. This plan became known as the Overflow Abatement Program (OAP).
In March 1990, the Tennessee Department of Environment and Conservation (TDEC) issued a "Commissioner's Order" to the Metropolitan government of Nashville and Davidson County. This Order imposed a "hook-up" moratorium that restricted the connection of new sewers to Metro's collection system. The Order required Metro to pay a $100,000 penalty and submit a plan to manage the capacity of the Metro system. Additionally, it detailed a schedule of required actions to be taken by Metro. The consequences for non-compliance were penalties assessed at $1 per 1,000 gallons of overflow, up to $500,000 per year. Practically every Order milestone was met during the subsequent ten years.
Over $750 million was invested in the OAP since its beginning and over 260 projects were successfully completed. Today, after elimination of 61 of the most critical overflow points in the sanitary system, separate sanitary overflows (SSOs) have been reduced by 67%, and pump station overflows have been reduced by 91%. The CSO system overflow points have been reduced from 31 to 8. Annual overflow volumes have been reduced from over 21 billion gallons to 2 billion gallons in 2000. Inflow and infiltration (I/I) has been reduced in the system by 2.8 billion gallons per year. On the basis of the MWS's computation of $2.59 per 1,000 gallons for transport and treatment, this recaptured capacity has reduced Metro's operating costs substantially.
There is still a great deal to be done for total compliance with the Clean Water Act.
Questions which are not addressed through this web site, please email Sonia Harvat.