Document Type

Thesis - University Access Only

Award Date

2016

Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Delvin E. DeBoer

Abstract

With the promulgation of Stage 2 Disinfectants/Disinfection By-product (D/DBP) Rule on January 4, 2006, most water distribution systems are required to perform an initial distribution system evaluation to find monitoring sites for regulated DBPs, including trihalomethanes and haloacetic acids. In the Stage 2 D/DBP rule, the method of calculating the average value of DBPs concentration is different than required for the prior Stage 1 D/DBP rule. The purpose of this thesis was to examine relationships between disinfection practices and DBP concentrations in South Dakota regional rural water systems. These relationships would provide a basis for locating potential DBP monitoring sites in regional rural water systems as required by the Initial Distribution System Evaluation (IDSE), thus helping systems to comply with the DBP regulations. Since some regional rural water systems also practice booster chlorination, another minor intention was to analyze the booster chlorination process to determine its impact on DBP formation. Historical water quality data were collected from Mid Dakota Rural Water System and Randall Community Water District. These systems both use Missouri River reservoirs as their water source and treat the water using coagulation and filtration. However, the Mid Dakota Rural Water System uses chloramine as the final disinfectant, where as the Randall system uses free chlorine as its final disinfectant. Data from these systems were analyzed using ArcGIS® and Excel® software to identify factors impacting DBP formation and reveal their trends and spatial variability with respect to distribution system parameters. The IDSE process of selecting DBP monitoring sites assumes the highest trihalomethane concentration will occur at the location of lowest chlorine residual. Areas of low chlorine residual were identified from the GIS plots and new sample site locations were found based on low chlorine residual and other factors. Test results from samples collected at the new sites generally confirmed the DBP/chlorine residual relationship. Results of booster chlorination experiments showed that booster chlorination in the Randall Community Water District system had minor impacts on DBP formation.

Library of Congress Subject Headings

Water -- Purification -- Disinfection -- By-products
Water-supply, Rural -- South Dakota

Publisher

South Dakota State University

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Rights Statement

In Copyright