Drainage Issues in the Landscape

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Drainage Issues in the Landscape

• Master Gardeners
• Virginia Cooperative Extension
• Prince William County
• Lorrie Andrew-Spear
• Frank Reilly

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Drainage Issues in the Landscape

• A. Where does the water come from and why doesnt
  it go away?
• B. Impact of drainage problems
• C. Drainage solutions
• www.AdvancedMasterGardener.org

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A. Where does the water come from and why it
doesnt go away

• Precipitation, ground water, surface water
• Watersheds
• Physiographic regions and soil types
• Soil texture and structure (particle sizes, pore
  spaces, well-drained soils vs. not, organic
  component, compaction)
• Soil horizons and water infiltration
• Run off (erosion, potential pollutants)

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Precipitation, ground water, surface water
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Groundwater Surface Water
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Run off affected by

• Impervious surfaces
• Slope
• Vegetation
• Previous moisture
• Infiltration rate

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Run Off

• Flooding
• Erosion
• Potential pollutants

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Physiographic regions and soil types

• Physiographic Regions describe land surface
  features
• Closely related to geology
• Slope, and soils are related

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Physiographic Regions
                                                                                                                                       
        Appalachian Plateaus         Valley and Ridge
        Blue Ridge         Piedmont Plateau
                Coastal Plain                 Coastal Plain
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Soil Structure
Granular Blocky
Prismatic Platy
Columnar Single Grained
Massive
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Soil Texture
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Soil Texture

• Sand are the largest particles and they feel
  "gritty."
• Silt are medium sized, and they feel soft, silky
  or "floury."
• Clay are the smallest sized particles, and they
  feel "sticky" and they are hard to squeeze.

Sand 2.00 - 0.05 mm Silt 0.05 - 0.002 mm Clay lt 0.002 mm
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Pore Spaces

• The smaller the particles
• The smaller the pore spaces
• Water moves slowly
• Less air present

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Pore Spaces can decrease due to compaction
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Soil horizons and water infiltration

• Horizons have different properties
• Some may retard water flow
• Watch out for the builders horizon

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Check for Yourself

• Dig a hole 12 inches deep and fill it with water
• 30 minutes, the soil has a drainage problem
• 24 hours, waterlogged soils may impact plant
  growth

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Drainage Issues in the Landscape

• A. Where does the water come from and why doesnt
  it go away?
• B. Impact of drainage problems
• C. Drainage solutions

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B. Impact of drainage problems

• Home damage
• Puddles (mud, mosquitoes)
• Eroded topsoil, rills, gullies
• Lawns and plants (stressed drowned)

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Home Damage
Impact of drainage problems
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Puddles
Impact of drainage problems

• Mosquitoes
• Mud
• Further damage

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Eroded topsoil, rills, gullies
Impact of drainage problems
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Erosion Where do you think it goes?
Impact of drainage problems
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Lawns and plants (stressed drowned)
Impact of drainage problems
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Impact of drainage problems

• Damage at your home
• Damage Down Stream
• Watershed level
• Neighborhood level
• Keep the water safely on your property

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Drainage Issues in the Landscape

• A. Where does the water come from and why doesnt
  it go away?
• B. Impact of drainage problems
• C. Drainage solutions
• Drainage Options

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Drainage Options

1. Horticultural ways to help wet soils
2. Slowing/intercepting Runoff
3. Slope/grading possibilities
4. Underground/subsurface alternatives

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Drainage Options

• Horticultural Improvements
• Soil
• Plants
• Mulch

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Drainage Options

• Soils
• Add compost organic matter
• Encourage earthworms/microorganisms
• Aerate lawns
• Avoidcompaction

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Drainage Options

• Plant Selection
• Wet Feet
• Erosion control groundcovers on slopes
• Native plants
• Plant lists
• - Extension Publications Trees for Problem
  Landscape Sites www.ext.vt.edu
• - Native plants for Conservation, Restoration and
  Landscaping (comprehensive list)www.dcr.state.va
  .us/dnh/native.htm

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Native Plants

• Group several of the same plant together to
  establish a healthy population.

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Planting Wet Spots

• Plants

Spiderwort
Cardinal Flower
Ferns
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Plants for Wet Sites

• Plants
• Royal fern, maidenhair fern, ostrich fern
• Cardinal flower
• Foam flower
• Bleeding heart
• Solomans seal
• Butterfly weed
• Columbine (native variety Aquilegia canadensis)
• Heavy metal switch grass

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Plants

• Shrubs
• Sweet pepperbush (Clethra alnifolia)
• Red twig dogwood
• Bush blueberry (Vaccinium corymbosum)
• Inkberry holly (Ilex glabra)
• Winterberry holly (Ilex vertilulata)
• Arrowwood Viburnum (Viburnum dentatum)
• Sweetspire (Itea virginica)
• Red Chokeberry (Aronia abutifolia)

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Planting Wet Spots

• Shrubs

Sweetspire (Itea)
Winterberry Holly (Ilex verticillata)
Sweet Pepperbush (Clethra)
Sweetshrub (Calycarpa)
PHOTOS Floridata.com
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Plants

• Trees
• River Birch (Betula nigra)
• American Hornbeam (Carpinus carolinia)
• American Holly (Ilex opaca)
• Sweetbay Magnolia (Magnolia virginiana)
• Tupelo (Nyssa sylvatica)
• Swamp White Oak (Quercus bicolor)
• Pussy Willow (Salix discolor)
• Bald Cypress (Taxodium distichum)

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Planting Wet Spots

• Trees

Sweet Bay Magnolia
American Holly
River Birch
Hornbeam
PHOTOS Floridata.com
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Planting Wet Spots
Odd Ball Plant collections
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Need More?

• Iris louisiana

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Drainage Options

• Mulch
• Organic bark, shredded or nuggets
• Different needs for drainage mulch!
• Depth of 2-4 inches
• Advantages
• Breaks raindrops/prevents erosion
• Aesthetic
• Weed control
• No volcanoes!

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Drainage Options

• Slowing/intercepting Runoff
• Gutters/downspouts, splashblocks/extenders
• Rain Barrel/cistern
• Rain garden

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Drainage Options

• Gutters/downspouts
• Leaf guard to prevent stoppages
• Repair leaks
• Check slope

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Drainage Options

• Splashblocks/extenders
• Slope AWAY from foundation
• Extend downspout roll-out, perforated extension
  (above ground or buried)solid pipe
• Drop inlet

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Drainage Options
Rain Barrels Cisterns above or under-ground
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Roof Top Rainwater Harvesting
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Rain Barrels have a number of uses!
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Drainage Options

• Rain Gardens
• Shallow landscapedareas built to slow down and
  hold rain runoff, allowing it to soak into the
  ground, instead of flowing into storm drains.

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Rain GardensCommercial Use

• Parking Lots
• Neighborhood Common Areas, Parks, Schools
• New Commercial Developments (LID)

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Drainage Options

• Rain Garden Advantages
• Prevent Erosion
• Help prevent local (yard) flooding.
• Soak up to 30 more water than lawns.
• Prevent pollution

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Where to Build a Rain Garden

• Between area to be drained (roof, driveway or
  yard) and storm drain or street
• Where downspout or other area can drain to it
  across a grassy area, or filter strip
• At least 10 feet from your houses foundation
• An oval or oblong shape approximately 5-7 of the
  size of the area draining to it (roof, etc.)

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Testing Drainage

• Dig test hole
• One foot deep
• One foot long/wide
• Fill with water until saturated
• Fill again to top and let stand
• If doesnt drain in 24 hours, the site is not
  suitable for Rain Garden

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Building Rain Gardens

• Call Miss Utility!!!
• Remove grass and 3-6 inches of soil to make a
  level bottom.
• Mix in compost, sand, topsoil, and other soil
  conditioners for better drainage.

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Rain Gardens
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Drainage Options

• Slope/re-grading possibilities
• To slow and/or redirect flow of runoff
• But BEWARE Dont create more problems for
  yourself or your neighbors

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Drainage Options

• Slope/grading possibilities
• Filling low spots
• Terracing slopes
• Swales and berms
• Dry creek beds

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Drainage Options

• Filling low spots
• If adding soil to low areas be sure water has
  somewhere to go
• Incorporate the new soil

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Drainage Options

• Terracing Slopes
• Prevents runoff erosion of slopes
• Makes better planting beds level, more stable

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Building Terraces

• Height
• Materials
• Reinforcement
• Plants
• Mulch
• Terraces can work for drives too

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Drainage Options

• Berms
• Earthen mounds used to direct drainage (among
  other uses)
• A site designer should evaluate the entire sites
  drainage before considering a berm of significant
  size.

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Drainage Options

• Swales
• Shallow earthen channels covered with grass

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Building A Dry Creek Bed

• Mimic streams shape meander?
• At least twice as wide as deep (good size is
  three feet wide by18 inches deep)
• Add rocks/plants
• Lead to dispersal area or pond (NOT street)

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Drainage Options

• Underground/subsurface alternatives
• Hire Assistance for underground drainage options
  to ensure proper diversion and dispersal of
  water
• French Drain
• Underground drainage system

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Drainage Options

• French Drain
• Gravel-filled trench
• Perforated pipe
• Covered withfabric
• Slope to aid drainage
• Call Miss Utility FIRST

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Drainage Options

• Underground Drainage System
• Hire a professional contractor qualified to
  create drainage systems.

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BEST APPROACH

• Use as many options as you can get from the tool
  box.

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Questions?

• www.AdvancedMasterGardener.org