Let’s start with what is a BMP? In Civil Engineering and Construction, it typically refers to Best Management Practices. The ‘Management’ part can vary, depending on who is using the term BMP’s. A contractor may refer to Managing a Construction Project, but for Civil Engineering the term is almost always used in reference to stormwater and/or surface water runoff. In general, Best Management Practices (BMPs) is a term used to describe thecontrol of water pollution; the best way to manage your land and youractivities to reduce or prevent pollution of surface and groundwater near you1. There are a number of ways that pollution can be introduced to a body of water. Once pollutants are present, it is more difficult and expensive to restore it to its former glory. The use of BMPs that prevent damage to receiving waters is the target.
WHERE DOES THE RAINWATER GO?
Think back to the days of grade school and learning about the water cycle. The very fundamental cycle of water and how it travels is the key to managing this resource in the best possible way. Since water is a universal solvent, it easily picks up pollutants such as debris, metals, pesticides, sediment, bacteria, and more as it travels. If left unchecked, the water can then carry these pollutants into lakes, rivers and streams. For new developments part of their BMP will be a Stormwater Pollution Prevention Plan or “SWPPP”. This Plan is developed and maintained throughout the construction phase of a project to ensure that the newly disturbed ground has a minimal impact on the natural water flow until the project is completed. Another part of the BMPs for a new development will be the Civil Engineer’s Drawings showing how the earth around a building needs to be shaped, what elevations should be used and what the slope of the ground should be. Along with the potential water quality issues, urban development can displace water and create an increase in flooding and add to the amount of water that is causing erosion or sedimentation. These changes can also cause a change in vegetation and decrease of native wild life. This is where Effective Management or ‘Best Management Practices’ (BMPs) become important. Stormwater BMPs are techniques, measures or structural controls used to manage the flow and improve the quality of stormwater runoff and will be incorporated into the Civil Engineers Plans.
CONTROLLING THE FLOW
Typical BMP techniques used to control the flow of water and improve water quality include such measures as detention ponds, grass swales, natural plantings, and natural filters. The techniques used for each development will differ depending on variables such as water table, typical rainfall, wetlands, overland flood routes, surrounding developments, and available drainage.
By: Rashida Pflipsen / Rebecca Luginbill
1 US EPA website: http://www.epa.gov/nrmrl/wswrd/wq/stormwater/bmp.html