Rain Garden Installation

baxter — Thu, 01 Apr 2010 04:47:55 +0000

Last month, at the Bellevue Home Show, Lifestyle Landscapes made two presentations describing Rain Gardens and Developing a Sustainable Landscape. The attendees at the Rain Garden Seminar have requested we post information about selecting a garden site. We discussed a number of criteria pertaining to the sizing of a Rain Garden. The following slides include this information. If, after reviewing this information, you have unanswered questions, give us a call and we will be happy to provide answers – 206 621-2626.

Size of Rain Garden

Percolation Test

Dig a hole at least 2’ deep and 1-2 feet in diameter. •
Put a ruler in the hole and fill the hole with 8-12 inches of water. In Summer, fill and let drain three times. On the third time record the depth every hour. When the rate of change stabilizes i.e. is the same for three hours, that’s the infiltration rate in inches/hour.

Percolation Test Results

If hole drains at less than .5” / hour it is draining poorly. More than .5” / hour is draining well.

If the rate is less than .25” / hour but more than .1” / hour, then the location may be OK but there may be standing water for long periods of time.

If the rate is less than .1” / hour, choose another location.

6″ ponding depth – Infiltration rate – Rain Garden Sizing

.25 ————–9.80% (.98)

.5—————-6.40% (.64)

1—————-4.00% (.40)

Example: Drained area 2500 sq ft x .98 = 245sq ft of rain garden
When infiltration rate is 0.25

Choosing a Contractor

For the design, seek a qualified landscape designer to incorporate the garden seamlessly into your landscape, and to choose plants for the specific micro-climates of your site.

For the installation seek a contractor experienced with rain gardens. If your contractor is not familiar with the concept their actions could adversely affect the function of the rain garden.

Make sure they are building you a rain garden, not a pond, the goal is water infiltration.

Baxter

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Rain Garden Installation