NH: Residential Rain Gardens
-
Upload
sotirakou964 -
Category
Self Improvement
-
view
685 -
download
0
description
Transcript of NH: Residential Rain Gardens
![Page 1: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/1.jpg)
Residential Rain Gardens
They are… • Shallow depressions that allow
water to collect and infiltrate • Effective at removing
particulates and some nutrients from stormwater runoff
• Planted with native or adapted plants that tolerate wet and dry conditions
• Additions to the landscape installation and/or maintenance services you offer
They are not…
• Suitable for every site Limiting factors:
• Poorly drained areas
• Underlying ledge
• Heavy clay soils
• High water table
• Mosquito pools
• Located near basements or septic systems
• High tech or hard to install
![Page 2: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/2.jpg)
Residential Rain Garden Installation
• October 2010 installation at Portsmouth, NH
• Rain garden training for professional landscapers
• Co sponsors: UNH Cooperative Extension, UNH Stormwater Center, Hodgson Brook Restoration Project, Northeast States & Caribbean Islands Regional Water Center, NH Landscape Assoc. and New England Grows!
![Page 3: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/3.jpg)
Sizing the rain garden
Measure area of impervious surface to be drained
½ garage roof = 416 square feet
![Page 4: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/4.jpg)
Size: An average size is about 1/3 the size of the drainage area and 4-8” deep.
With an adjustment for the slope here, the size of the rain garden needed was about 150 square feet (4 inch depth).
outflow
![Page 5: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/5.jpg)
Perc test
An infiltration rate of 1.5” per hour minimum is recommended.
![Page 6: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/6.jpg)
Outline with flags, string or paint
Call Dig Safe now! Then remove the layer of sod, saving it to use on the berm later, or move it to another spot.
![Page 7: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/7.jpg)
Excavation
The soil removed from the middle can be used to berm the edges on a sloped site.
![Page 8: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/8.jpg)
Hand excavation
Finish up with shovels and rakes to get the surface contoured as desired.
![Page 9: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/9.jpg)
Inflow
Sometimes landscape fabric is pinned underneath inflows and outflows to protect soil against erosion.
![Page 10: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/10.jpg)
Leveling
Check the depth using strings a carpenter’s level and measuring tape; adjust as needed.
![Page 11: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/11.jpg)
More leveling
The bottom should be very level so water infiltrates evenly throughout.
![Page 12: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/12.jpg)
Add soil amendments
Compost, lime, nutrients based on soil test and site. Be aware of state/local restrictions within shoreland protection zones.
![Page 13: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/13.jpg)
Grading outflow
You may protect the outflow and inflow areas with rocks to protect against erosion during heavy flow. Besides, all those rocks we dug up have to go somewhere ….
![Page 14: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/14.jpg)
Grading outflow
Recheck depth and grade; remember water flows downhill!
![Page 15: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/15.jpg)
Placing plants
Rain garden plants remove water through their roots and release it to the atmosphere. Their roots also help keep the soil in place and maintain organic matter.
![Page 16: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/16.jpg)
Placing plants
Mostly native plants are used; in this case, herbaceous perennials and grasses are mixed together. In larger rain gardens, shrubs and/or a tree or two may be added. Plant selection is planned for wet to dry zones within the garden, depending on soil and site characteristics. Most rain gardens don’t stay very wet very long.
![Page 17: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/17.jpg)
Planting
Fall is a good time for root establishment, even though tops are going dormant.
![Page 18: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/18.jpg)
Minimize compaction
Be gentle and avoid compacting the soil, which reduces drainage. Plant from the edges as much as possible.
![Page 19: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/19.jpg)
Mulching
Three inches of shredded hardwood mulch is commonly used. Chips or nuggets may float. Recycled, shredded yard waste can covered with an inch of a more attractive hardwood mulch, as shown here.
![Page 20: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/20.jpg)
Finished rain garden
![Page 21: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/21.jpg)
Maintenance requirements
Water and weed as needed for first season.
Replenish mulch until plants provide adequate ground cover.
Inspect for signs of problems, such as a plugged inflet, uneven flow or gullies during and after a rain event. Does the rain garden overflow through the outlet during a heavy rain?
Look for sediment accumulation in the rain garden. This means it is working! As it accumulates, you will need to remove it occasionally with a flat shovel.
As with other gardens, plants will self-select over time. Don’t fight the site!
![Page 22: NH: Residential Rain Gardens](https://reader033.fdocuments.net/reader033/viewer/2022052523/5552e4d2b4c90532498b51ec/html5/thumbnails/22.jpg)
For more information on rain gardens in the northeast:
• Vermont, Maine and Rutgers (New Jersey) all have excellent rain garden manuals on line
• This presentation and links to other sites will be posted on our web page
http://extension.unh.edu/Agric/AGNLT.htm
Presentation by Dr. Cathy Neal, Extension Professor and Landscape Horticulture Specialist, Univ. of New Hampshire, Durham NH. Additional photos courtesy of Margaret Hagen of UNH Cooperative Extension and Candace Dolan of the Hodgson Brook Restoration Project.