Drainage Issues in the Landscape

1
Drainage Issues in the Landscape

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

2
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

3
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)

4
Precipitation, ground water, surface water
5
Groundwater Surface Water
6
Run off affected by

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

7
Run Off

• Flooding
• Erosion
• Potential pollutants

8
Physiographic regions and soil types

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

9
Physiographic Regions
10
Soil Structure
11
Soil Texture
12
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.

13
Pore Spaces

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

14
Pore Spaces can decrease due to compaction
15
Soil horizons and water infiltration

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

16
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

17
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

18
B. Impact of drainage problems

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

19
Home Damage
Impact of drainage problems
20
Puddles
Impact of drainage problems

• Mosquitoes
• Mud
• Further damage

21
Eroded topsoil, rills, gullies
Impact of drainage problems
22
Erosion Where do you think it goes?
Impact of drainage problems
23
Lawns and plants (stressed drowned)
Impact of drainage problems
24
Impact of drainage problems

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

25
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

26
Drainage Options

• Horticultural ways to help wet soils
• Slowing/intercepting Runoff
• Slope/grading possibilities
• Underground/subsurface alternatives

27
Drainage Options

• Horticultural Improvements
• Soil
• Plants
• Mulch

28
Drainage Options

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

29
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

30
Native Plants

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

31
Planting Wet Spots

• Plants

Spiderwort
Cardinal Flower
Ferns
32
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

33
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)

34
Planting Wet Spots

• Shrubs

Sweetspire (Itea)
Winterberry Holly (Ilex verticillata)
Sweet Pepperbush (Clethra)
Sweetshrub (Calycarpa)
PHOTOS Floridata.com
35
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)

36
Planting Wet Spots

• Trees

Sweet Bay Magnolia
American Holly
River Birch
Hornbeam
PHOTOS Floridata.com
37
Planting Wet Spots
Odd Ball Plant collections
38
Need More?

• Iris louisiana

39
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!

40
Drainage Options

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

41
Drainage Options

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

42
Drainage Options

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

43
Drainage Options
Rain Barrels Cisterns above or under-ground
44
Roof Top Rainwater Harvesting
45
Rain Barrels have a number of uses!
46
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.

47
Rain GardensCommercial Use

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

48
Drainage Options

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

49
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.)

50
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

51
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.

52
Rain Gardens
53
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

54
Drainage Options

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

55
Drainage Options

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

56
Drainage Options

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

57
Building Terraces

• Height
• Materials
• Reinforcement
• Plants
• Mulch

58
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.

59
Drainage Options

• Swales
• Shallow earthen channels covered with grass

60
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)

61
Drainage Options

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

62
Drainage Options

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

63
Drainage Options

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

64
BEST APPROACH

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

65
Questions?

• www.AdvancedMasterGardener.org