Building demolition, like construction, can have a major impact on storm water runoff. Any activity that moves around large amounts of soil will stir up dust and debris. When storms wash this extra sediment into nearby waterways, negative environmental outcomes are the result. For one thing, rainwater can pick up pollution from impervious surfaces such as parking lots; this pollution can then poison downstream ecosystems. Second, silt reduces visibility in streams and rivers, making it harder for predators to hunt. Finally, high sediment levels throw off spawning by covering eggs with a layer of muck. For all of these reasons, it is important for construction and demolition companies to manage projects’ storm water runoff.
Ideally, builders and demolition contractors will work together to reduce polluted storm water runoff during all stages of demolition and construction. Communication and cooperation will help maximize results. First, it makes sense to create a shared Storm Water Pollution Prevention Plan (SWPPP). Here are a couple of things any viable SWPPP should address:
How to prevent storm water runoff. This may involve stockpiling topsoil and covering open areas to prevent erosion. Temporary or permanent seeding are also good solutions here.
How to prevent sedimentation of storm water. One way to do this is to add sediment traps to nearby drains. Earth dikes and silt fencing are other options.
Building demolition contractors and construction workers can collaborate on a sketch of the project area prior to launch. This bird’s eye view should indicate important drainage landmarks. For instance, if a stream runs alongside the project, a stream buffer should be penciled into the sketch. Where will runoff drain into city-maintained systems? How can placement of driving zones reduce runoff pollutants? Such questions and more will arise in your sketch and should be addressed in your SWPPP.
Once you know the lay of the project and how drainage will run, you can establish best management practices (BMPs) for the life of the project. Some BMPs will be structural; these could include sediment ponds and erosion control blankets. Other BMPs will be non-structural and will instead guide workers’ behavior. For example, demolition contractors could be directed to walk and drive only in certain zones and to pick up trash at the site to prevent it being swept downstream.
In addition to the erosion prevention techniques outlined in a SWPPP, demolition companies can improve drainage down the road through green demolition techniques. For example, what was a brick wall can be salvaged for a permeable parking area. The LEED green building certification program awards points for projects that reuse materials in this way.
Improperly managed, open building sites allow tons of sediment to wash into storm drains. For comparison, consider that the erosion rate for bare soil (like at a demolition site) is between 35-45, while the rate for forestland is less than 1. To protect our shared resources, responsible commercial and industrial demolition companies must work together with contractors to minimize runoff and promote healthy drainage in the future.