First Flush definition

First Flush means the initial or early stages of stormwater runoff from a storm event which commonly delivers a disproportionately large amount of previously accumulated pollutants due to the rapid rate of runoff. The first flush is commonly used as the Water Quality Treatment Volume (WQTV) and is defined in the City of Cookeville Stormwater Management Design Guidelines.

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First Flush means within the first 30 minutes of the formation of a discrete storm water discharge.

First Flush means the delivery of a disproportionately large load of pollutants in surface runoff during the early parts of storms due to the rapid runoff of accumulated pollutants.

Examples of First Flush in a sentence

• As previously described, the First Flush Project supplements the Surface Water Project, providing data on the first significant surface water flows of the season.

• The First Flush Project supplements the Ambient Surface Water Quality Monitoring Project (Surface Water Project), providing data on the first significant surface water flows of the season.

• The First Flush Project is a run-based system comprised of two sample runs: Lummi Bay First Flush and Portage Bay First Flush.

• In summary, the Water Resources Specialist II is responsible for maintaining and storing all documents and records associated with the First Flush Project.

• Water quality data collected as part of the First Flush Project are compared to Surface Water Project data as well as with water quality criteria to determine whether these waters meet the Water Quality Standards for Surface Waters of the Lummi Indian Reservation (Lummi Nation Water Quality Standards; 17 Lummi Administrative Regulation [LAR] 07).

• The First Flush Project provides the targeted, non-random sampling of water quality monitoring sites when sites are flowing following the first significant rains at the onset of the wet season.

• Detailed information for each parameter and instrument is provided in the parameter and instrument SOPs. This section provides a summary of required activities for each parameter and instrument as well as general QA/QC procedures for the First Flush Project.

• The goal of the First Flush Project is for sample sites to be sampled once per year during surface water flow following the first significant rains of the season.

• Information regarding data quality allows for comparison of data collected at different times over the period of record within the Surface Water Project and with other Lummi Nation water quality projects (e.g., First Flush, Department of Health Support, ZAPS Continuous Monitoring Study), as well as comparison with non-WQM Program sources of data, assuming quality control information is available for non-Program data.

• Since fecal coliform concentrations in surface waters typically peak after major rain events, the First Flush Project aims to capture the first pulse of runoff after soils and wetlands have become saturated.

More Definitions of First Flush

First Flush means a method for the removal of sediment and debris from the collection

First Flush means a method for the removal of sediment and debris from the collection surface by diverting initial rainfall from entry into the storage unit.

First Flush effect means that the timing of a rainfall event and the volume of run-off generated affects the concentrations of contaminants present. However, the total amount of each substance deposited on surfaces and that eventually ends up in the run-off will, over a sufficiently long period (e.g. a year), be more or less the same (except perhaps in the case of spills). This means that the total load of contaminants discharged into the receiving environment by urban run-off over that same period will be, approximately the same, whether they are all discharged in a small number of intense rainfall events or a longer period of prolonged rainfall.

First Flush. , means the transport of solids in a combined sewer system that: