14.2 Storm Drainage II Flashcards
In gravity systems, water is always going to flow _________
downwards
What’s soil boring?
Structural subsoil investigation
What is the purpose of the water table?
Controls if you must dewater the site
T/F Ground water is ALWAYS predictable
False.
What are perforated pipes?
Tiny hole piping design that allows water to enter/exit at various points along the tube
What consists in foundation drains/subsoil drains? (ex. basement)
- Perforated Pipes
- Open joint pipes
- utilize finer fill (back fill)
What is the purpose of a solid interceptor/sediment basin?
To catch/retain solid particles in a mainline
How does a solid interceptor/sediment basin work?
Water flows through inlet. Slows water down. Drops the sediment .Flows out through outlet
What to look for in a site investigation?
Surface Contours, discharge locations, water table, flooding considerations, provision for future development.
What is a surface contour?
The slope of the site.
Where does the water in State College get discharged to?
Storm Drain -> Cheasepeake Bay
Other Possible Discharge Locations:
Public Sewer, water ways, surface absorption, dry wells (French Drains).
T/F You can build on top of the flood plane
TRUE. Must calculate 1/2” off flood plane.
How is storm water managed?
GPM before > GPM after. Run off cannot exceed than before
What design considerations should you consider at an intersection?
Place drains above intersection on UPHILL side.
What design considerations should you consider for a series inlet?
Bypass 25% of water. Place 300’ max apart. Locate inlets at low points. place manholes (change in directions). pipe must remain STRAIGHT.
What’s a drainage inlet?
Inlet that’s free from debris/sediment. Dry.
What’s a catch basin?
Catches debris, requires maintenance. Outlet is raised higher.
What’s a manhole?
NOT an inlet. Used for change in direction or elevation.
What’s a drop manhole?
Manhole that can be emptied so that maintenance worker can go down in.
T/F a manhole is a type of inlet.
FALSE.
What materials are used for manholes?
Brick and Pre-cast concrete
What does the term “invert” mean on a manhole drawing?
The channel at the bottom of a manhole that directs water to flow from the inlet to the outlet.
