Students are given an assignment to go out


into the community to photograph three BMPs being used to protect water qual- ity, and three examples of sites where BMPs should have been put in place but are missing. Students learn to read the landscape as they identify sedimentation basins for catch- ing runoff from large parking lots, vegetated or rock-lined drainage channels, and silt-control fences that keep soil from construction-related disturbances out of waterways. Some note the presence of vegetation buffers along shorelines, and rain gardens to catch runoff from parking lots. Students write a short description of each photo, describing the BMP or recommending a particular BMP if it is missing. I review with students some of the planning and design


decisions that have been made in our community, discussing local growth trends and how they directly affect our water- shed. Using the guidebook Design Guidelines to Enhance Community Appearance and Protect Natural Resources, we look at examples of, and alternatives to, urban sprawl. (Other books or websites on community design or commu- nity character could be used, or students could be asked to do web research on urban sprawl and collect photos of it to share with the class.) It is important for students to understand sprawl visually, rather than only verbally. Therefore, I ask


them to identify new development in our com- munity and document it with digital photos. Students then select one photo and make recommendations for minimizing the visual and environmental impacts of the new development. They print the photo, lay tracing paper over it, draw in the parts of the scene they want to keep as is, and then add “best man- agement” recommendations to show how the new development could be enhanced to better blend into the community and minimize water-qual- ity and other environmental impacts.


Calculating runoff If there is time, I have students calculate the amount of stormwater runoff from the school building.


First, they measure the school building and transfer the dimensions to grid paper. Students then estimate the area of the building by counting the number of squares it occupies on the grid. To obtain the volume of water that falls on this area during a rain event, they multiply the area by the depth of the rainfall as follows:


U.S. measures (per inch of rainfall): 1. Rooftop area in square feet x 0.0833 feet (1 inch) = cubic feet


2. Cubic feet x 7.48 = volume in U.S. gallons Land Use


Urban/commercial (parking lots, city streets)


Possible Pollutants


Runoff Control: Best Management Practices Best Management Practices (BMPs)


Road salt Sediment Automotive fluids Motor oil Thermal warming of runoff water


• Use porous asphalt or pervious concrete • Create vegetated islands in parking lots


• Construct runoff retention ponds to collect runoff and allow time for infiltration


• Leave parking lots unpaved


• Create vegetated or rock-lined drainage channels so that runoff can slowly seep into ground


Managed forest (logging roads)


Residential (lawns, driveways)


Sediment


Pesticides Fertilizers (nutrients) Pet wastes (bacteria) Road salt Detergents


Agriculture (livestock grazing)


Agriculture (cropland)


New construction


• Maintain vegetation buffer along stream to filter out sediment • Do not locate roads immediately adjacent to streams


• Use minimal amounts of pesticides and fertilizers on lawns • Pick up and dispose of pet wastes • Maintain areas of native vegetation to promote infiltration • Irrigate lawns sparingly • Wash car where soapy water will infiltrate into lawn, not run off


Animal wastes (bacteria, nutrients) • Maintain vegetation buffer along streams to slow and filter runoff • Fence along streams to limit or prevent access • Provide off-stream water tank for livestock


Sediment Fertilizer Pesticides


Sediment • Maintain vegetation buffer along streams to slow and filter runoff • Use erosion-control fabric to prevent soil from moving off site GREEN TEACHER 83 Page 11


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56