When looking to protect storm water at construction sites, there are three solid lines of defense that are commonly used in order to keep sediment and other debris from entering the storm water. One or more of these methods is required in order to prevent sediment which may contain various chemicals from the construction site, or other debris from polluting the storm water. In many areas, the choice of the method is up to the construction company. The choice is dependent on the climate, the expected amount of excavation needed, and the contractor’s personal preference. Three of the more common ways utilized by construction companies and contractors to protect from storm water runoff contamination are: silt fences, hay or straw bales and filters.
Silt fences are used for large scale projects where a lot of drainage and runoff is expected. In a nutshell, a fence is built that is a large scale filtering system. A silt fence must be buried at least four to six inches into the ground in most places in order to meet code requirements. This allows for the fence to be stable and secure against the elements. Obviously, in order to be effective, the silt fence must be installed at a position which the drainage will be flowing. This method may or may not be used with straw or hay bales as an added filtration option. A drawback to using a silt fence is the time needed to put it up and take it down. It must be regularly cleaned to prevent build up of debris and the materials can be reused if they are in good shape.
Straw or Hay Bales
One of the benefits to using straw or hay bales is the simplicity of the process. Rather than the construction of a large filtering system, such as is needed with a silt fence, the hay or straw is placed at the points of drainage. Usually, code requirements are such that they must be secured into the ground, usually buried to a certain depth. After the project is complete, the bales are simply discarded. Using them for compost, etc. is discouraged because of the potential chemical contaminants that may be in the bales.
Often a basket or other filtering system is used to collect sediment and debris at the curb inlets. These are reusable, easy to clean and economical. A benefit for the use of the inlet filters is the ease of their installation and maintenance. Rather than needing to bury a fence or bales, it takes a comparatively short time and little man power to install, maintain and remove an inlet filter, ensuring that savings is made for the contractor and construction site safety is maintained for all.