Drainage and Erosion Control

Slide 1 LHAP 107: Landscape Construction Fundamentals: DRainage Systems Slide 2 Why are we Draining?? Where have you had to install drainage? Sunken Patio House Foundation, Eavestroughs or property Sports-turf (playing field / golf course) Pond Overflow, High water table L.I.D. - bioswales, permeable pavers, rain gardens Slide 3 Grading: Drainage Systems Drainage systems divided into two groups: 1. Subsurface Primarily deals with SURFACE water** Exceptions: High Water tables and very coarse texture media 2. Surface Slide 4 Drainage Systems: type Factors that determine type of system: Soil Texture How does the texture impact flow? Volume of Water Type of System Type of Catchment Capacity of System Slide 5 Drainage Systems: Sub-Surface Rolled Corrugated Plastic Pipe or “Big O” / “Weeping Tile” Perforated or Non Perforated Sleeved or Unsleeved EZ flow Pipe Courtesy: TDS – Turf Drainage Systems Advantages over PVC: Flexibility Easy jointing Cuts with aknife Slide 6 Subsurface Drainage Systems: Rolled Corrugated Plastic Minimum slope for Rolled Corrugated Plastic Pipe is 2%. Installed on a bed of gravel, below frost line whenever possible (to extend the life of the plastic). Slide 7 Subsurface Drainage Systems Drainage tower: many pipes joining and emptying into one catchment Weeping tile connectors with Grates photo credit: J Pick Slide 8 Subsurface Drainage Systems: Perforated PVC Laid in a herringbone pattern Slide 9 Down! Think of how water moves in a trench... Slide 10 Subsurface Drainage Systems Fine textured material over a coarse one Sand = 300 mm perched table Coarse sand or pea gravel = 50-100 mm “choker” Gravel = 100mm perched table Slide 11 Surface / Subsurface: Culverts Slide 12 Subsurface Drainage Systems: Other subsurface drainage systems: Clay or Concrete Pipes True French Drains Slide 13 Surface Drainage Systems: Swales Constructed by creating a shallow trench through the landscape Designed to direct flow of surface water, removing it quickly from sight Slide 14 Grading: Surface drainage - ditches Slide 15 Grading: Surface Drainage Systems Curbs and Gutters Used on street edges, but also useful beside long driveways. Gutter is a very small ditch - think of bowling alleys - used to collect water. Curbs protect adjacent landscaping by directing surface flow away Slide 16 Grading: Drainage System Exterior screen filters large fines. When additional filtration is necessary, a second screen can be installed lower. The basin can also be larger with exit pipes higher up, relying on gravity, or have a pump. Courtesy: Practical Drainage for Sportsturf, Golf, and Horticulture. Keith McIntyre, Brent Jakobsen, Ann Arbor Press, 2000 Flow well Dry Well. Click here to see a video... Slide 17 Erosion Control With proper seed establishment often taking well over a month, Erosion control is necessary in areas of high water movement. Slide 18 Erosion Control Systems… unconventional? Slide 19 Erosion Control: Temporary Systems Click here to view Nilex’s webpage - a company specializing in surface drainage and erosion control aids. Slide 20 Erosion Control: Long-term Installations Slide 21 Vegetated swales Retaining Walls Snow Fence Berms