CLEAN WATER ATLANTA: A COMPREHENSIVE APPROACH TO QA/QC FROM SSES TO REHABILITATION DESIGN

The Clean Water Atlanta sewer system improvement program is one of the most comprehensive programs in the U.S. where the entire public sewer system with diameters 8 inches and larger is being evaluated and improved. The program received its mandate from the Consent Decree (concerning the combined system) and the First Amended Consent Decree (concerning the sanitary system) which require the City of Atlanta to perform significant improvements to it's approximately 1900 miles of sanitary and combined sewer collection system. The main objective of the consent decrees is to reduce the frequency of combined sewer overflows and the elimination of the capacity and maintenance related sanitary sewer overflows. The total cost of the program is expected to exceed 2 billion, of which approximately 900 million is budgeted for SSES, rehabilitation, sewer cleaning and flow monitoring.The program contains many tasks but four in particular are geared to the rehabilitation program and are very closely linked. These include: Sewer System Evaluation Survey (SSES), Hydraulic Modeling, GIS, and Sewer Rehabilitation Design.The City of Atlanta sewer system is divided into ten sewer basins which discharge to one of four major wastewater treatment plants. Each sewer basin is further divided into sewersheds containing 25 to 50 thousand feet of sewer which in turn discharge through a single outfall sewer into the system. A total of 260 sewersheds constitute the City of Atlanta sewer system.The size of Atlanta's sewer system and the task interdependence both underscore the need for a comprehensive and robust quality control and quality assurance procedure at each step. The focus of this paper is the QA/QC process followed in SSES and Rehabilitation & Replacement Design.