Date of Award
Summer 2005
Document Type
Thesis - Restricted
Degree Name
Master of Science (MS)
Department
Civil, Construction, and Environmental Engineering
First Advisor
Melching, Charles S.
Second Advisor
Crandall, Clifford J.
Third Advisor
Switzenbaum, Michael
Abstract
In early 2003, the Illinois Environmental Protection Agency (IEPA) initiated an Use Attainability Analysis (UAA) for the Chicago Waterway System (CWS) with Camp, Dresser & McKee (CDM). As a result of the UAA, dissolved oxygen (DO) was found to be a concern for the CWS. DO data from monitoring indicate that water quality processes are complex and vary under a wide range of flows. Therefore, water-quality management problems of interest to the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) require analysis of unsteady flow conditions. A model capable of simulation of the effects of flow and loading variations in time on water quality in the CWS was developed and tested by the Institute for Urban Environmental Risk Management at Marquette University with usage of the DUFLOW program. This model is to be used to evaluate pollution mitigation alternatives identified in the UAA and to determine the pollution mitigation methods and levels of pollution mitigation needed to achieve DO concentrations greater than 4, 5, and 6 mg/L throughout the study reaches. Once a model is calibrated its forecasting ability should be validated during verification runs before application to pollution mitigation scenarios. The main purpose of this study is to verify the DUFLOW model of the CWS and test its behavior under uncertain storm loading. Because detailed storm data were used for the CWS water-quality model calibration (07/12/01-11/09/01) and such data were not collected for the verification period (05/01/02-09/24/02), a new approach to verification was applied to evaluate periods after storms resulting in combined sewer overflows (CSOs). In this approach event mean concentrations are randomly generated on the basis of observed event mean concentrations for the pump stations, combined sewer overflows points, and tributaries. Multiple simulations of water-quality in the CWS were performed, and the range of simulated DO concentrations is compared to the observed DO concentrations. The standard verification confirmed the DO prediction ability of the DUFLOW water quality model. Although the average errors for most locations were greater than 30%, the verification results are similar to the calibration results. The new approach to verification was used to analyze storm load influence on DO concentrations in the CWS. The effect of storm pollutants on water quality can be split into two phases: direct influence and sediment influence. The first phase lasts until the time needed to pass the wave through the downstream boundary, equal to the time needed to drain the system. Substantial impact of storm loading remains in the CWS a few weeks in reaches upstream of the Stickney WRP, whereas in reaches downstream of the Stickney WRP the impact remains for a few days. The second phase lasts longer, more than the time between the two consecutive storms. During this phase, DO in the system is affected much less than during the direct influence phase.
Recommended Citation
Neugebauer, Anna, "Verification of a Continuous Water Quality Model under Uncertain Storm Loads" (2005). Master's Theses (1922-2009) Access restricted to Marquette Campus. 4598.
https://epublications.marquette.edu/theses/4598