Perimeter controls are required by local and federal laws to be installed when it comes to any sort of construction or land disturbing activities. There are many different types of perimeter controls, but the most common are silt fence and bio logs. Although there are many kinds of perimeter controls, they all serve the same purpose of keeping pollutants out of our natural waterbodies. Some examples of pollutants that can come from construction activity include concrete washout, paint, stucco, oil, trash, amongst many others. However, of all these different kinds of pollutants, sediment itself is the number one pollutant. Sediment has nutrients in it such as Nitrogen and Phosphorus. Discharging excess sediment and nutrients into waterbodies can severely impact the plants and animals in our natural waterways. It can also cause different kinds of algae to form in our lakes, rivers, and streams amongst other environmentally harmful aspects. Silt fence and bio logs help stop and collect sediment and other pollutants after a rainstorm. The perimeter controls used on construction sites are inspected weekly via a SWPPP inspection. If any perimeter control is deficient, the SWPPP report must notate this, at which point the perimeter control would need to be maintained in a timely manner that state regulations lay out. Most construction sites drain water from their project via an MS4, or municipal separate storm sewer system. This means that our stormwater and sewer water are sent to two different pipes. The sewer water gets sent to a water treatment facility and the stormwater is typically discharged to a local water body without being treated by the MS4. This is why it is not only important to keep the sediment on site during a construction project, but to also keep it off the street and from flowing into a stormwater inlet after a rain event. Using perimeter controls on construction sites is one of the best ways to ensure sediment and other pollutants are staying on site and are not getting discharged to local waters.   

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