Which dates must the operator record in the SWPPP when modifications or updates occur?

The requirement for operators to record specific dates in the Stormwater Pollution Prevention Plan (SWPPP) is critical for effective monitoring and compliance during a construction project. The correct choice includes the dates of major activities that can significantly affect erosion and stormwater runoff management.

Recording the dates of major grading ensures that any large-scale earth-moving activities are tracked, as these activities can increase the potential for soil erosion and sediment runoff into nearby water bodies. Additionally, noting when activities cease is essential for understanding when potential discharges to stormwater systems may reduce, allowing for better management practices to be implemented during inactive periods. Furthermore, recording when stabilization measures start is vital because these measures, such as applying seed or mulch, play an essential role in preventing future erosion and controlling sediment discharge.

The other choices, while also important for overall stormwater management, do not specifically focus on the critical activities impacting stormwater control measures in the context of modifications or updates in the SWPPP.

Overall, option B includes specific actions relevant to project modifications, highlighting the need for operators to keep accurate records that influence the site's environmental management during construction.