| DETERMINATION OF EVENT MEAN CONCENTRATIONS AND FIRST FLUSH CRITERIA
IN URBAN RUNOFF
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| Lee-Hyung Kim† |
| Department of Civil and Environmental Engineering, Disaster Prevention Research Center, Kongju National University, Chungnam-do, 314-701, Korea |
Corresponding Author:
Lee-Hyung Kim ,Tel: +82-041-850-8667, Fax: +82-041-856-9388, Email: leehyung@kongju.ac.kr
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Received: March 6, 2003; Accepted: July 6, 2003. |
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| ABSTRACT |
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Non-point source pollution has become an important component in watershed planning in United States because of high mass emissions. Land use associated with vehicular activity such as parking lots and streets are especially thought to be high contributors of stormwater pollutants. In order to determine the magnitude of the first flush from freeway runoff, pollutant loading is being measured at eight freeway sites with emphasis on interpretations of event mean concentrations (EMCs) and first flush effects. The EMCs cannot be determined by simple statistical averaging of measured pollutant concentrations because of random characteristics of runoff quality and quantity. Also, it is necessary to develop a definition of first flush effects since this has not been defined clearly. Therefore, this paper will show a new EMC determination method and an appropriate definition and criteria for first flush. Using results of the monitoring and new washoff model, EMCs are determined. The EMC ranges of 95% confidence intervals are from about 102.78 to 216.37 mg/L for TSS, 104.53 to 251.79 mg/L for COD, 5.42-10.58 mg/L for oil & grease and 2.42-10.18 mg/L for TKN. The mass discharge curves that will explain the definition and criteria of first flush are classified into three types: high (>50% mass/30% runoff volume), medium and non-first flush (<50% mass/30% runoff volume). More than 80% of the events exhibited a first flush. |
| Keywords:
Event mean concentrations | first flush | non-point sources | stormwater | washoff |
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