40 Questions
What is the main purpose of external drainage?
To maintain soil's structural capability and improve trafficability
What happens to excess rain or irrigation water that does not infiltrate the soil?
It flows to areas of lower elevation
Why is it important to remove excess water from the surface?
To maintain aesthetic conditions and prevent damage to turf, buildings, and hardscapes
What type of water is considered clean and can be discharged directly into an approved water course or soakaway?
Surface water
What type of water is contaminated by domestic waste and requires treatment?
Effluent
What are the main forms of excess water in building drainage?
Surface water and effluent
What is the purpose of a soakaway?
To discharge surface water into an approved water course
Why is external drainage detrimental to the turf and other plant life?
Because it causes poor aesthetic conditions and destroys turf and plant life
What is the primary function of a roof drainage system?
To collect water and debris from the roof
What is the purpose of a gutter in a roof drainage system?
To collect water and debris from the roof
What is the benefit of having a gutter system in a roof drainage system?
It protects the landscaping from soil erosion and the home's foundation from cracking
What type of gutter is located on the outside of a building?
Eaves gutter
What is the function of a downspout in a roof drainage system?
To allow water to flow from the gutter to the ground
What is the purpose of a roof drainage system in terms of soil erosion?
To reduce the risk of soil erosion
What is the location of a valley gutter in a building?
At the intersection of sloping surfaces of a roof
What are the three types of gutters mentioned in the passage?
Eaves gutter, box gutter, and valley gutter
What type of drains are channel drains a variation of?
Surface drains
In a standard channel drain installation, what is the purpose of sloping the hardscape surface?
To direct water to the channel drain
What is the purpose of erecting a string line at each end of the drain run?
To guide the laying of the channels to the required level
Where should the channel installation begin?
At the discharge end of the run
What is the purpose of using stakes or rebar to anchor the channel?
To secure the channel to the trench bed
What is backfilled into the trench after the channel installation is complete?
Either concrete, sand, or soil, depending on the application
What is the purpose of a concrete base in a channel drain installation?
To provide additional support for heavy loads
What is the purpose of a catch basin in a drainage system?
To collect and redirect surface water
What type of areas are prefabricated drains ideal for?
Heavy use areas such as athletic fields and golf courses
What should cover the prefabricated drain in subsurface drainage?
Sand
What is the purpose of using temporary wood stakes during prefabricated drain installation?
To center the drain in the trench
What is the primary purpose of terracing?
To move surface runoff water from sloping areas
Why should excavated soil not be used as backfill?
It may contain silt or fines
What is the purpose of flooding the sand with water during prefabricated drain installation?
To promote proper compaction
What is the formula to calculate roof catchment capacity?
Annual rainfall (in mm) x Roof surface area (in m2)
What is the purpose of the Flo-Well unit and Pop-up emitter?
To act as discharged points
What is the least expensive method of removing undesired surface water runoff?
Natural surface drain swales
How deep should the drainage trenches be?
Deep enough to allow appropriate soil cover over the drain
What is the purpose of a conducting system in a drainage system?
To channel all around the edge of a sloping roof
What are the two types of terraces used in turf drainage?
Bench terraces and tile outlet terraces
What is the final step in prefabricated drain installation?
Placing the sod back over the trench
What are the three major phases of a drainage system?
Collection, conduction, and dispose
Where can culverts be installed?
Under flat work, gravel, or dirt
What is the purpose of a drainage system?
To collect, conduct, and dispose of drainage water
Study Notes
Excess Water Removal
- Excess water is detrimental to turf and other plant life and needs to be removed to maintain soil's structural capability and improve trafficability.
- Excess rain or irrigation water will naturally flow to areas of lower elevation.
- Surface water is considered clean and can be discharged directly into an approved water course or soakaway.
Forms of Excess Water
- Surface water
- Subsurface water
- Effluent (water contaminated by domestic waste)
Drainage Systems
- Swales: natural surface drain swales are the least expensive method of removing undesired surface water runoff.
- Terraces: used to move surface runoff water from sloping areas.
- Culverts: installed under flat work, gravel, or dirt to allow water to pass under an obstruction.
Good Design Practice
- A drainage system has 3 major phases: collection, conduction, and disposal of drainage water.
- The design process involves determining the size of the catchment system, conducting system, and disposal system.
Roof Drainage System
- A roof drainage system is installed on the roof to divert water and debris off the roof.
- Components include gutter systems and downspouts.
- Gutters collect water and debris from the roof and flow toward the downspout and onto the ground.
- Three types of gutters: eaves gutter, box gutter, and valley gutter.
Channel Drain Installation
- Channel drains are used in hardscapes such as patios, walkways, swimming pools, parking lots, and driveways.
- The hardscape surface is slightly sloped in one direction or plane to the perimeter channel drain.
- Standard installation involves excavating a trench, laying the channel, and backfilling with concrete, sand, or soil.
Catch Basins and Inlets Installation
- Catch basins are structures with a grate on top used to collect surface water.
- Ideal for heavy use areas such as athletic fields and golf courses.
- Subsurface drainage involves installing a prefabricated drain and covering it with sand to the surface.
Prefabricated Drain Installation
- The sod is cut and removed from the trench, and the trench is backfilled with select sand.
- The drain is placed in the trench and centered using temporary wood stakes.
- The trench is backfilled with sand to bring the backfill up to the top of the trench.
- The sod is then placed back over the trench.
This quiz covers the importance of removing excess water from turf surfaces, the detrimental effects of waterlogging, and the benefits of proper drainage for soil structure and plant life.
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