AWWA ACE93146

Since 1984, the South Central Connecticut Regional WaterAuthority (RWA) has routinely experienced positive coliform samples in its distribution system as a result of the presence of a biofilm. The change in coliform analytical methodology from the cell density to the presence/absence (PA) method as required by the June 1989 Total Coliform Rule (TCR) significantly increased the likelihood that the RWA would exceed the new Maximum Contaminant Level (MCL) from environmental coliforms associated with biofilm. Since the Total Coliform Rule did not permit variances, the RWA actively supported intensive AWWA efforts to have EPA provide a variance for systems which exceeded the Total Coliform Rule MCL as a result of biofilms in their distribution systems. Accordingly, in January, 1991, the EPA published the methods and criteria by which utilities could qualify for a variance to the TCR. The RWA immediately began working with the Connecticut Department of Health Services (DHS), in particular the Water Supply and Epidemiology sections, to document the necessary public health information and perform those investigations needed to meet the EPA criteria in order to obtain a variance to the EPA TCR. In June 1992, the RWA officially applied for the variance, and in September 1992, the DHS granted the variance. This paper presents the RWA's experience with implementing the distribution system best management practices required by the EPA TCR variance criteria for obtaining and complying with a Total Coliform Rule variance.