Rain Gardens Credits- All images in this presentation are from the following manual: Rain Gardens- A How-to Manual for Homeowners Your Personal Contribution to Cleaner Water Authors- City of Tallahassee Stormwater Management, TAPP- Think About Personal Pollution. The original concept and illustrations were derived from the University of Wisconsin Extension Servicewww.TAPPwater.org

Why use Rain Gardens? Why use Rain Gardens? Increase the amount of water that filters into the ground- recharging groundwater supplies Increase the amount of water that filters into the ground- recharging groundwater supplies Provide protection from flooding and drainage problems Provide protection from flooding and drainage problems Protect streams, lakes and rivers from pollutants Protect streams, lakes and rivers from pollutants Channel water away from structures Channel water away from structures Wildlife habitat Wildlife habitat Page 5

Elements of a Rain Garden Elements of a Rain Garden Diverse mix of flowering plants, sedges, rushes, and grasses Diverse mix of flowering plants, sedges, rushes, and grasses Native plants a good choice- rainfall patterns Native plants a good choice- rainfall patterns Consider bloom time Consider bloom time Mix heights, shapes and textures Mix heights, shapes and textures Mulch- composted yard debris and leaves Mulch- composted yard debris and leaves Add rocks, stones, gravel for more texture and interest Add rocks, stones, gravel for more texture and interest Page 5

Locating the Rain Garden Locating the Rain Garden At least 10 feet from house so water does not seep into foundation At least 10 feet from house so water does not seep into foundation Integrate into existing landscape Integrate into existing landscape Locate next to outdoor gathering areas Locate next to outdoor gathering areas Don’t locate over septic system or drainfield, or under a large tree Don’t locate over septic system or drainfield, or under a large tree Locate in full or partial sun Locate in full or partial sun Encourage additional water filtration- don’t locate in already low spot Encourage additional water filtration- don’t locate in already low spot Add plants to low spot and create new low spot with garden Add plants to low spot and create new low spot with garden Page 6

Size and Shape of Garden Size and Shape of Garden Kidney or teardrop shapes Kidney or teardrop shapes Size depends on: Size depends on: Type of soil Type of soil Size of roof and lawn area Size of roof and lawn area to drain to drain Depth of rain garden Depth of rain garden Page 7

Type of Soil and Drainage Area Clay- slowest rate, so gardens must be larger. Too much clay is poor location Clay- slowest rate, so gardens must be larger. Too much clay is poor location Sandy- highest rate, smaller gardens Sandy- highest rate, smaller gardens The larger the drainage area the larger the garden The larger the drainage area the larger the garden Page 9

Calculating Drainage Area Calculating Drainage Area 10 to 30 feet from a downspout- almost all water comes from roof- calculate portion of roof that drains into garden 10 to 30 feet from a downspout- almost all water comes from roof- calculate portion of roof that drains into garden More than 30 feet from downspout- measure length and width of up lawn and add to roof area More than 30 feet from downspout- measure length and width of up lawn and add to roof area Page 9

Depth of Rain Garden Depth of Rain Garden Typical- 4 to 8 inches Typical- 4 to 8 inches Ground surface of the garden must be level Ground surface of the garden must be level The slope of the lawn determines the depth of the garden The slope of the lawn determines the depth of the garden A steeper slope will allow a deeper garden A steeper slope will allow a deeper garden Page 10

Calculating Slope Calculating Slope One stake at highest point- a second stake at low point – about 15’ away One stake at highest point- a second stake at low point – about 15’ away Use a carpenter’s or string level Use a carpenter’s or string level Measure distance between stakes (width) Measure distance between stakes (width) Measure height from ground to string on downhill stake Measure height from ground to string on downhill stake Page 10

Calculate Slope and Depth Calculate Slope and Depth Page 11

Calculate Square Footage Calculate Square Footage Page 13

Shape of the Garden Shape of the Garden The long side of the garden should face uphill The garden should be longer than it is wide Page 14

Length and Width of the Garden Length and Width of the Garden Choose a width that fits the area- 10’ is typical, but no more that 15’ Choose a width that fits the area- 10’ is typical, but no more that 15’ Should be wide enough for the water to spread evenly over the whole bottom surface Should be wide enough for the water to spread evenly over the whole bottom surface Provide enough space for a variety of plants Provide enough space for a variety of plants Page 14

Digging the Rain Garden Digging the Rain Garden Dig the depth of the garden at the uphill stake Maintain the same depth across the bottom Pile the dirt on the low side to create the berm Page 16

Building the Berm Building the Berm The berm should be as high as or slightly higher than the uphill edge The berm should be as high as or slightly higher than the uphill edge Compact the soil in the berm by tamping hard Compact the soil in the berm by tamping hard Have gently sloping sides and plant to integrate into the rest surrounding garden Have gently sloping sides and plant to integrate into the rest surrounding garden Page 18

Conclusion Conclusion Rain gardens capture stormwater Rain gardens capture stormwater Rain gardens: Rain gardens: –fit with the Florida- Friendly principle of reducing runoff –facilitate a positive way to solve a problem Reduced stormwater equates to cleaner water bodies Reduced stormwater equates to cleaner water bodies