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An Evaluation of the Factors Affecting the Quality of Highway Runoff in the Austin, Texas AreaBy Lynton B. Irish, JR., P.E. William G. Lesso, Ph.D. Michael E. Barrett, M.S., Joseph F. Malina, JR., P.E., Randall J. Charbeneau, P.E., George H. Ward, Ph.D. ABSTRACT The main goals of this portion of the research project were the identification of the variables which affect the build-up and wash-off of constituents from highways in the Austin, TX area and development a water quality model which incorporated these variables. This project marked the first scientific use of a rainfall simulator in conjunction with active traffic. Twenty-one variables were identified for each storm event and multiple regression analysis was used to determine the relationship of each variable to the quality of the highway runoff. The majority of variations observed in highway storm water loading in the Austin area may be explained by causal variables measured during the rain storm event, the antecedent dry period, and the previous rain storm event. The examination of the controlling variables in each model adds insight into the applicability of the model and the mitigation of constituent loading. Highway runoff constituents, in general, fall into one of three categories: (1) those constituents, such as suspended solids, that are influenced by conditions during the dry period and may be mitigated by dry period activities such as street sweeping and others; (2) those constituents that are most influenced by conditions during the rainfall event and may only be mitigated through the use of runoff controls; and (3) those constituents that are influenced equally by both periods. The constituents that are significantly affected by conditions during the preceding storm event, generally are those constituents that are controlled by the dry period variables. The highlighted links that follow are connected to Adobe pdf files of the corresponding material. To view them you must have the Adobe Acrobat Reader 3.0. View the Whole Report...(2.4Mb) |
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