The interval between storm water discharges for sample collection should be at least how long?

The correct answer is that the interval between storm water discharges for sample collection should be at least 72 hours. This timeframe is important for ensuring that any potential variability in the storm water runoff is accounted for, as storm events can differ significantly in intensity and volume.

Sampling too frequently, such as within 48 hours, may not capture the full spectrum of pollutants present in storm water discharges, as rainfall patterns can lead to different concentrations of contaminants in runoff. The 72-hour interval helps to standardize the data collection process, allowing for a more reliable assessment of water quality over time. This time frame is also consistent with regulatory requirements that aim to ensure thorough monitoring of stormwater discharges and the effectiveness of best management practices implemented at industrial sites.

By adhering to this interval, operators can better understand the impacts of their operations on stormwater and comply with the necessary environmental regulations.