By Johnathan Clayton, Lead Compliance Manager - Florida // 2021-01-21
During most construction activities, there is some form of concrete that will be utilized, whether it is mixed by hand in wheelbarrows or poured from cement mixing trucks. No matter how the concrete is applied or transported to the site, there will inevitably be remaining concrete waste that is not used and needs to be washed out of the equipment. This remaining waste should be contained in a watertight concrete washout area to ensure that none of the liquid and/or solid materials are able to leave the construction site. Concrete waste that is dumped directly onto soil or roadways, can easily be washed down streets and stormwater inlets which will eventually lead to local lakes, rivers, or coastal waters.
There are many different types of concrete washout areas that can be used depending on the needs at the construction site. The State of Florida E&SC Designer and Review manual describes a washout area as listed below.
“Shallow excavations lined with a material to prevent infiltration of washout material. A soil tracking prevention device at the access point. Signs throughout the construction site identifying the location. Development of a containment structure. Maintenance and termination plan”
The Designer Manual also explains that there are innovative ways to design and maintain washout areas other than the one mentioned above. In Florida, however, the small, excavated pit is a common type of concrete washout area utilized. The pit should be excavated a minimum of 24” and dimensions of 25’ x 25’. The soil excavated from the pit should be utilized to build a small berm on three sides of the pit. The pit should be completely lined with plastic and silt fence installed at the top of the berm. A track out control device, normally a gravel pad, should be installed at the entry point to the washout area. The concrete washout area should be installed a minimum of 50’ away from any stormwater inlet.
Once a concrete washout area is installed and begins to be utilized, it is important that the area is routinely inspected and inspected after each rain event to ensure that the containment area is not overflowing. If a concrete washout area is routinely being filled by rainfall, consider covering it during rainfall. When inspecting a concrete washout, areas that should be inspected include perimeter control of the concrete washout area, access points, signage, track out control device (if installed), level of solid/liquid material, washout liner, etc. Consider scheduling maintenance of the concrete washout area prior to reaching capacity to avoid any pollutant escaping the designated area. Moving equipment to concrete washout areas can be time-consuming, but it is important that concrete waste is contained to ensure that waterways are not contaminated.