Period 1

Drainage and Erosion Control

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LHAP 103 Site Assessment, Grading/Drain Presentation grading and site assesment

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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

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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

Speaker Notes

Subsurface drainage systems:
Usually characterized by an inlet and an outlet - receives surface water through inlet and transports it to an appropriate outlet (later)
Window Well entry into foundation weeping tile… (make sure it has a catchment or drainage!)
Culverts
Sewers… under patio… playing field edges… tie ins to downspouts… etc etc etc
SURFACE WATER - infiltration rate of clay? Measured in DAYS.
Standard hydraulic conductivity of 5 mm / hour - 60 hours (2.5 DAYS) to drain 50 mm (2 inches) H2O
Most water on a clay soil runs off and will not make it to the percolation into subsurface systems.
ONLY DEALS WITH SUBSURFACE WATER WHEN:
High water table - water comes from beneath and fills the drainage system
Soil is already saturated - dig a test hole; fill with water, time how long it takes to dissipate. This gives the contractor an idea of drainage requirement.
Coarse textured media - discussed later - sandy type soil where infiltration and percolation are extreme.

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

Speaker Notes

Texture from Soil reports and Journeyman mad skills!
Compare Sand Vs Clay soils
UNderstanding volume of water to be moved is essential!
System Type : is surface sufficient? Or Subsurface?
Catchment - can it simply dissipate (ground water recharge), catch basin or catchment pond?

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

Speaker Notes

RCPP
Weeping Tile - specifically refers to PERFORATED RCPP.
holes at regular intervals to allow water to percolate in and through pipe
Should be sleeved to keep fines out
Can be procured NON-PERFORATED (make sure you buy the right product for the right application)
Must be careful when backfilling pipe - easily crushed
“New” product includes styrofoam/other material between weeping tile and sleeve - increases water movement, protects/cushions from compaction, lightweight alternative to gravel; “no muss no fuss”:
NDS shows installation of EZ flow pipe - comes in different lengths (10 ft) and diameter
BUT… expensive & environmental impact??

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).

Speaker Notes

ALL DRAINAGE must be sloped (min 0.5%) - but the corrugations require more slope than smooth PVC
Uses: Weeping tile around foundations / edges of playing fields / sports turf
Slope the field down to the edges and run pipe there
Tie ins for downspouts - don’t have to lift the spout when buried (more on next slide)
leave space for cleaning / blowouts
Backing of retaining walls.

Slide 7

Subsurface Drainage Systems

Drainage

tower: many pipes joining and emptying into one catchment

Weeping tile

connectors with Grates

photo credit: J Pick

Speaker Notes

Can get special grates and modified caps (like an oldschool irrigation head that uses water pressure to pop)
Most systems deal with SURFACE water - Grates are used to screen out fines and other junk
These systems rely on gravity to move the water - OUTPUT MUST BE LOWER THAN INPUT or else the water will just back up

Slide 8

Subsurface Drainage Systems: Perforated PVC

Laid in a herringbone pattern

Speaker Notes

Herringbone pattern is perpendicular to the catch flow when it is being used for catchment of surface water (perforated with no grate)
Imagine eavestrough placement on a roof…
PVC is stronger (although it CAN still crack esp when cold)
Weeping tile OR PVC uses:
Under Sunken Patio (permeable pavers OR polymeric sand to a grate [less pipe required]) to basin with sump
Patios that home sump drains onto
When there are only holes on one side of the pipe, should the holes face up or down??

Slide 9

Down!

Think of how water moves in a trench...

Speaker Notes

Water typically trickles down the sides and fills the bottom first.
If the holes face up, the entire trench needs to fill before the water is taken up.

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

Speaker Notes

Slide credit - J. Pick, School of Environment.
This is a situation where subsurface is dealing with subsurface water:
Surface water infiltrates and percolates (becoming subsurface water)
NOTE: Perforated PVC with holes DOWN.
High water table also better with holes DOWN.
Every other time, it uses an inlet and outlet. In those cases, doesn’t matter if it’s perforated or not b/c so little water can infiltrate fine texture soils.
It drains to a catch basin or collection pond (constructed wetland)

Slide 11

Surface / Subsurface: Culverts

Speaker Notes

Installation of Culverts - short length of subsurface when vehicular traffic interrupts surface drainage
Always remember maintenance - can I mow around that? (Do not cut straight down @ 90 degrees, make a mowable / rocked in slope
Use rock to keep soil from building up and caving in around it - Erosion control
Use rock at the base as well to try and keep the culvert clean
Make sure that it is large enough to satisfy capacity
Hide your mechanics (the ugly culvert)

Slide 12

Subsurface Drainage Systems:

Other subsurface drainage systems:

Clay or Concrete Pipes

True French Drains

Speaker Notes

Clay and Concrete not often used in our systems
True French Drains refer to pipeless systems - fabric lined gravel trenches that use gravity.

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

Speaker Notes

Drain surface water; Manage surface water on site; conserve existing features
Prevent soil loss
Prevent damage to Property
Swale: shallow, sometimes imperceptible to the average eye (.5% slope on each side).
Bioswales incorporate the use of plant material for aesthetics, and also so that their root zones can aid in filtration of water. These can be as simple as a dry riverbed or as complex as a system of filtration ponds (Olds College Constructed Wetlands).

Slide 14

Grading: Surface drainage - ditches

Speaker Notes

Photo Credit - E.Wheale 2015
Ditches are a modified swale with steeper sides,
Typically leading to a water reservoir of some kind, and will require culverts under roads or paths.
The decision about a ditch vs ‘swale’ is determined by the amount of water it needs to accommodate at the highest flow season.
Think about long term impact of erosion control decisions!!!
Current practices include ditches - constructed wetlands in new developments.

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...

Speaker Notes

Dry Riverbed that is active during a rain - adequate outlet / catchment
Rain Gardens
Constructed Wetlands
Irrigation source / Green roof
Use EZ flow / French drains to allow slow percolation back into aquifers (but remember that clay substrates won’t allow for much percolation)

Slide 17

Erosion Control

With proper seed establishment often taking well over a month, Erosion control is necessary in areas of high water movement.

Speaker Notes

Photo Credit: E. Wheale, Olds College turfgrass planting, November 2014.

Slide 18

Erosion Control Systems… unconventional?

Speaker Notes

Photo credit: E. Wheale, Olds College turfgrass development, November 2014
Note the grass growing through the straw bale bottom left, and the collection of grass in the centre ‘v’ where seed was washed in and stopped.

Slide 19

Erosion Control: Temporary Systems

Click here to view Nilex’s webpage - a company specializing in surface drainage and erosion control aids.

Speaker Notes

Picture Credit: E.Wheale. Olds College, just south of LSC. November 2014
Nilex.com (the other link is specifically their landscape materials)
Erosion Control Blankets, (and wind stop/break fencing)
Turf reinforcement mats
Anchor Reinforced Vegetation systems
Scour protection mats
Concrete revetments and mattresses
Gabions
Cellular Confinement
Mud Mats and ‘Rig Mats’
Hydromulches and Tackifiers
Plant material (stoloniferous/rhizomatous) and Stone

Slide 20

Erosion Control:

Long-term Installations

Speaker Notes

Photo Credit: E.Wheale, 2015
Gabions with Jute / Burlap / Coir
Matting holds down the soil and allows the seed to grow up through (Hydro seed with tackifier is another option but big rain causes pain)
Gabion is an erosion control method - cheaper than retaining wall and purposely slows but doesn’t stop water