Estimated Compliance with the Proposed Stage 2 Disinfection By-Products Rule for Eleven Water Utilities in North Carolina
Public Deposited- Last Modified
- February 28, 2019
- Creator
-
Han, Nora J.
- Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
- Abstract
- Eleven water utilities in North Carolina were examined to assess their potential compliance with the impending Stage 2 Disinfection By-Products (DBP) Rule. The Stage 2 Rule will require that all utilities meet the 80 μg/L maximum contaminant level (MCL) for four trihalomethanes (THM4) and the 60 μg/LMCL for five haloacetic acids (HAAS) on a locational running annual average (LRAA)basis. This represents a major departure from past DBP regulation for which compliance was based on a system-wide running annual average (RAA). Additionally, while compliance has previously been based on DBP levels for samples collected primarily at locations with average distribution system residence times, the Stage 2 Rule will base compliance on DBP levels collected at locations with maximum THM4 and HAAS concentrations. To assess potential compliance with the proposed Rule, it was necessary to estimate maximum THM4 and HAAS concentrations in the distribution systems for each utility using historical quarterly THM4 and HAAS values. The approach taken was to use the US EPA Water Treatment Plant (WTP)Model and available data to extrapolate to the most remote locations in the distribution system to estimate DBP levels at these locations from which maximum LRAAs could be calculated. In addition, because historic quarterly THM4 and HAAS measurements are taken as much as five months apart, the WTP Model was utilized to predict monthly DBP values from which LRAAs were calculated. The results show that several of the utilities may have difficulties complying with the new Rule with regard to one or both of the MCLs for THM4 and HAAS. In addition, significant variations in LRAA concentrations were observed for the eleven utilities evaluated. These variations could be due to a number of factors (e.g.changes in source water quality, changes in treatment practices). A site-by-site analysis of raw water quality and treatment process trains was beyond the scope of this study but should be conducted by the individual utilities to better prepare them for the forthcoming Stage 2 DBP Rule.
- Date of publication
- May 2005
- DOI
- Resource type
- Rights statement
- In Copyright
- Advisor
- Weinberg, Howard
- DiGiano, Francis A.
- Singer, Philip
- Degree
- Master of Science in Environmental Engineering
- Academic concentration
- Environmental Engineering
- Degree granting institution
- University of North Carolina at Chapel Hill
- Graduation year
- 2005
- Language
- Deposit record
- 8daa46ae-58bd-4ddf-8097-0c44062f7d48
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