Drainage Issues in the Drainage Issues in the LandscapeLandscape

Virginia Cooperative ExtensionVirginia Cooperative ExtensionPrince William CountyPrince William County

Master GardenersMaster GardenersLorrie Andrew-SpearLorrie Andrew-Spear

Frank ReillyFrank Reilly

Shameless CommercialShameless Commercial

• Gardening SeriesGardening Series

• Help LineHelp Line

Drainage Issues in the Drainage Issues in the LandscapeLandscape

• A. Where does the water come from and why A. Where does the water come from and why doesn’t it go away?doesn’t it go away?

• B. Impact of drainage problemsB. Impact of drainage problems

• C. Drainage solutionsC. Drainage solutions

A. Where does the water A. Where does the water come from and why it come from and why it doesn’t go awaydoesn’t go away• Precipitation, ground water, surface waterPrecipitation, ground water, surface water• WatershedsWatersheds• Physiographic regions and soil typesPhysiographic regions and soil types• Soil texture and structure (particle sizes, pore Soil texture and structure (particle sizes, pore

spaces, well-drained soils vs. not, organic spaces, well-drained soils vs. not, organic component, compaction)component, compaction)

• Soil horizons and water infiltrationSoil horizons and water infiltration• Run off (erosion, potential pollutants)Run off (erosion, potential pollutants)

Precipitation, ground water, Precipitation, ground water, surface watersurface water

Groundwater – Surface Groundwater – Surface WaterWater

WatershedsWatersheds

• What is a What is a watershed?watershed?

• What is your What is your watershed?watershed?

• How can you How can you find out?find out?

• http://www.epa.gov/shttp://www.epa.gov/surf/urf/

• http://www4.pwcgohttp://www4.pwcgov.org/website/pwc-v.org/website/pwc-gisgis//

Prince William County Prince William County WatershedsWatersheds• This county crosses 3 This county crosses 3

watershedswatersheds. . • Find environmental Find environmental

information for each of information for each of these watersheds: these watersheds: – 0207000802070008 Middle Middle

Potomac-Catoctin; Potomac-Catoctin; state(s): DC, MD, VA, WVstate(s): DC, MD, VA, WV

– 0207001002070010 Middle Middle Potomac-Anacostia-Potomac-Anacostia-Occoquan; state(s): DC, Occoquan; state(s): DC, MD, VAMD, VA

– 0207001102070011 Lower Potomac; Lower Potomac; state(s): MD, VAstate(s): MD, VA

Run OffRun Off

• FloodingFlooding

• ErosionErosion

• Potential pollutantsPotential pollutants

Run off affected by:Run off affected by:

• Impervious Impervious surfacessurfaces

• SlopeSlope

• VegetationVegetation

• Previous moisturePrevious moisture

• Infiltration rateInfiltration rate

Physiographic regions and Physiographic regions and soil typessoil types

• Physiographic Regions describe land Physiographic Regions describe land surface featuressurface features

• Closely related to geologyClosely related to geology

• Slope, and soils are relatedSlope, and soils are related

                                                                                                                                      

                Appalachian Plateaus Appalachian Plateaus                 Valley and RidgeValley and Ridge

                Blue RidgeBlue Ridge                 Piedmont PlateauPiedmont Plateau

                                Coastal PlainCoastal Plain

Physiographic Regions Physiographic Regions

Soil StructureSoil Structure

GranularGranular BlockyBlocky

PrismatiPrismaticc

PlatyPlaty

ColumnaColumnarr

Single Single GrainedGrained

MassiveMassive

Soil TextureSoil Texture

Soil TextureSoil Texture

• Sand Sand are the largest particles and they feel "gritty."are the largest particles and they feel "gritty."• Silt Silt are medium sized, and they feel soft, silky or are medium sized, and they feel soft, silky or

"floury.""floury."• Clay Clay are the smallest sized particles, and they feel are the smallest sized particles, and they feel

"sticky" and they are hard to squeeze."sticky" and they are hard to squeeze.

Sand Sand 2.00 - 0.05 2.00 - 0.05 mmmm

Silt Silt 0.05 - 0.002 0.05 - 0.002

mmmm Clay Clay < 0.002 mm < 0.002 mm

Pore SpacesPore Spaces

• The smaller the The smaller the particlesparticles

• The smaller the The smaller the pore spacespore spaces

• Water moves Water moves slowlyslowly

• Less air presentLess air present

Pore Spaces can decrease due Pore Spaces can decrease due to compactionto compaction

Soil horizons and water Soil horizons and water infiltrationinfiltration

• Horizons have Horizons have different propertiesdifferent properties

• Some may retard Some may retard water flowwater flow

• Watch out for the Watch out for the “builder’s horizon”“builder’s horizon”

Check for YourselfCheck for Yourself

• Dig a hole 12 inches Dig a hole 12 inches deep and fill it with deep and fill it with waterwater

• 30 minutes, the soil 30 minutes, the soil has a drainage has a drainage problem problem

• 24 hours, 24 hours, waterlogged soils waterlogged soils may impact plant may impact plant growth growth

B. Impact of drainage problemsB. Impact of drainage problems

• Home damageHome damage

• Puddles (mud, mosquitoes)Puddles (mud, mosquitoes)

• Eroded topsoil, rills, gulliesEroded topsoil, rills, gullies

• Lawns and plants (stressed – drowned)Lawns and plants (stressed – drowned)

Home DamageHome Damage

PuddlesPuddles

• Mosquitoes Mosquitoes

• MudMud

• Further damage Further damage

Eroded topsoil, rills, gulliesEroded topsoil, rills, gullies

Erosion – Where do you think it Erosion – Where do you think it goes?goes?

Lawns and plants (stressed Lawns and plants (stressed drowned)drowned)

Drainage ProblemsDrainage Problems

• Damage at your homeDamage at your home

• Damage Down StreamDamage Down Stream– Watershed levelWatershed level– Neighborhood levelNeighborhood level

• Keep the water safely on your Keep the water safely on your propertyproperty