SWPPP stands for Stormwater Pollution Prevention Plan. The name pretty much says it all. A SWPPP is a plan that must be in place on all construction and industrial production sites that disturb more than 1 acre of land. They are also required for a lot of projects that disturb less than 1 acre of land.
The SWPPP tells the EPA, your state, and your municipal separate storm sewer system (MS4) exactly how you plan on keeping sediment, debris, fuels and oils, paint, concrete, and any other pollutant you might generate out of the storm drains, lakes, rivers, streams, oceans, and even groundwater.
A SWPPP is a big deal. A lot of companies, cities, and states have been fined thousands of dollars for either not having a SWPPP or not adhering to the one they have. And that brings us to the next part of our question, why you need one.