Drainage:
• Begins with grading all water on top surface away from building & out to right- away
• Gutters, flumes, berm, gentle wrap of paved surfaces direct water to drains, catch basins & penetration soil works
Pipe (trench) perforated outside next to foundation footing
-To reduce hydrostatic pressure on water.
“Not”
-Maintain uniform or increase hydrostatic pressure
-Decrease vapor pressure in basement room
Drainage: Connecting on site drainage to existing city drainage
Wastewater collection: Always flows by gravity, pipes at constant slope, mains are below street level (one to two pipes). Grades to transport solids is ½% to 2%, and diameters are up to 4 ft and 20 ft long
Surface water management: Natural or mechanical site drainage systems
Green codes: Minimum volume of water to ground water
Runoff: Amount water- What does not seep into ground beyond saturation. Seepage is function o f porosity, slope, vegetation
5 year storm: Residential
25- 50 year storm: Shopping center
Drainage systems: Culvert, guiters, “sheet flows”, pipes
“Check dams”: To reduce speed at high slopes
Final/ finished ground surface: + positive drainage; Free of un-drained depressions. No water stagnation
To control or avoid erosion: Use channels, pipes, hard surface, lower grade, finally connect to underground pipes
Below traffic & surge pressures (-3 to -4ft in colder area).
Deep excavation may be cost prohibitive.
Destructive wears must be prevented.
Simpler the better: Minimum pipe length, access, slopes, …, filters
Green Code: Swales, surface drainage, native grasses used as green codes
Sub surface drains are function of permeability, depth of drain, size of drain, slope of drain, spacing of joints, perforated PVC/clay
Vapor extraction: Site contamination leads to ground water contamination: Clean up to remediate unsaturated zone: Vapor extraction “not” in situ incineration, bio degradation, photolysis
Extraction/treatment: Ground water remediation projects: Extraction/ treatment “Not” with in situ aeration, biological barriers/filters, gas chromatography
Water detention areas: Used for control surface water run off,
Not: To create swimming & recreation
To create aesthetically pleasing vistas
To act as reservoir during drought
Permeable water aquifer
Aquifer: Underground permeable material through which water flows
Permeability: A measure of ease with a particular fluid flows through voids. “Not” compressibility, osmosis, or cohesion
Hydrostatic pressure: Fluid force exerting pressure on building.
“Not” dynamic, water, or wedge
If 5 yr storm is not adequate: Go for 10 year storm (100 year too costly), or use growth vegetation area for absorb or swales
To reduce complex drainage system:
Create thick ground cover of plant materials to absorb and slow down
Drainage to collect, conduct, and dispose rain
Paving does not absorb
Best is to greater absorption and percolation- Reduce erosion
Earth berm only diverts flow
Probability of poor drainage:
Flat site, high water table, no storm drain system
Septic tank: Soil must be pervious (permeable). Slope= 1 inch in 24 ft 1 inch/24 ft (not ¼”/ft- too fast). 100 ft from any body of water.
Rain water: Keep natural runoff and runoff after construction the same. Removal of vegetation decreases transpiration, impervious surfaces reduce infiltration.
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