For large project sites that discharge to an impaired water, the NPDES permit requires an additional inspection within 24-hours of each rain event of 0.25″ or more. The ESCP Coordinator can monitor rain levels at construction sites using a rain gauge, but in cases where it may not always be feasible, using a permanent local rain gauge is permitted. Government agencies such as NOAA and the USGS provide rain gauge data to the public and can be found on the links to the right.
NPDES permitees are also required to maintain a rain gauge log, which will track storm event information. See the Rain Reporting Spreadsheet to the right for a template.
Note: If there is a storm event that continues for multiple days, and each day of the storm produces 0.25″ or more of rain, inspections must be conducted within 24-hours of the first day of the storm and within 24 hours after the end of the storm. Inspections are only required during the project’s normal working hours, so if a storm event occurs during off-hours, an inspection shall be conducted on the day that work resumes.