I know what you’re thinking. I know what a BMP is! It’s that awesome format that I used to save my artwork from Microsoft Paint in Windows 95! Unfortunately, no. Well sort of. In the context of Civil Engineering, it’s referring to Best Management Practice.
Seeing as how it’s a bit rainy today in San Diego, It seems like a good time to talk about BMP’s.
BMP’s are basically split up into two separate categories: Construction level, and Permanent. Construction level BMP’s are measures put into place that help prevent pollutants from the construction site from reaching storm sewers. Permenant BMP’s are BMP’s that are set into place that will continue to clean water after the construction is complete. There is much to talk about here, especially with the California General Permit going into full effect in 2011. I think one important point to mention that most people might not know is that anything that gets into a storm sewer goes straight to the ocean.
Before being an engineer, I always had the notion that some sort of filtration happens before storm water hits the water body. Namely in San Diego, the beaches. Just think about it, if someone were to pour vinegar down the sewer (NO! don’t really do it!) that vinegar would go straight to the ocean. It would affect swimmers, surfers, sea life, plant life. So its important to us to make sure that no pollutants get into any storm sewer, because frankly, we love the beach.
There are a multitude of different filters we can use to filter out different pollutants. When an engineer designs a SWPPP or Storm Water Pollution Prevention Plan, they customize (or at least they should be) the BMP to the pollutant, to the site conditions.
This is a photo is an example of a BMP that was taken from a Costco parking lot near Escondido, California. The designer did an innovative design, in presenting a green island area for plants, and also a basin so that pollutants such as oil and dirt can be settled out before the water heads off site. Specific plants can do an excellent job in filtering water. You can also see a storm drain inlet in the middle that serves as an overflow should the water level get too high. If you look closely you can see oils in the water that this BMP captured. This is our first nominee for a Civy in the BMP category.
As a designer, there are some great resources on the web for BMP’s. My personal favorite is CASQA. Unfortunately, their BMP manual has gone to a fee service, but Google around. There is some great reading here too.