Site Planning: Site Drainage KMUTT First semester 1999-2000 26/5/99 SITE DRAINAGE Storm drainage system Grading procedure Factors influencing drainage system surface drain subsurface drain 09/03/2004 /Apinya/KMUTTarc354Site Drainage /Apinya/KMUTTarc354site drainage03

/Apinya/KMUTTarc354Site Drainage Storm drainage system In grading, SURFACE RUNOFF is the primary method to remove excess water. This is usually in some form of STORM DRAINAGE SYSTEM, which collects, conducts and disposes excess surface water caused by runoff from rainfall. 09/03/2004 /Apinya/KMUTTarc354Site Drainage

/Apinya/KMUTTarc354Site Drainage A storm drainage system is designed to: COLLECT CONDUCT DISPOSE Storm drainage system collect collect Private system conduct Public system Dispose 09/03/2004 /Apinya/KMUTTarc354Site Drainage

/Apinya/KMUTTarc354Site Drainage Storm drainage system A storm drainage system can: 1. Safeguard against erosion by reducing the rate of flow and volume of water 2. Reduce flooding and damage to property and construction 3. Increase useable area 4. Eliminate unnecessary standing water which may lead to pollution and breeding of insects. 5. Provide better growing condition for plants by reducing soil saturation (soil contains too much water lack of oxygen) 6. Improve load-bearing capacity of soils, thereby increasing the build-ability of a site. 09/03/2004 /Apinya/KMUTTarc354Site Drainage

Good Drainage practice Storm drainage system Good Drainage practice 1. Design the grading and drainage plan as to respect, reinforce, and duplicate the existing natural systems. 2. New runoff must never be purposefully redirected from one property onto neighboring property. 3. Surface drainage is generally preferred to underground systems for two reasons: cost and ecology. 4. Avoid the design of a system that necessitates the drainage line through a foundation or under slab. 09/03/2004 /Apinya/KMUTTarc354Site Drainage

Good Drainage practice (Continue). Storm drainage system Good Drainage practice (Continue). 5. Always consider some method to slow runoff water down and let it be absorb into the soil. 6. Slow-moving water will create a bog, while water moving too fast create erosion and unwanted gullies. 7. Paved areas (parking, sport court, etc.) look better when graded almost level-- avoid wildly sloping paved area. 8. Avoid draining large amounts of water from paved areas across pedestrian paths or sidewalk. Install a catch basin or trench drain to collect most runoff before the sidewalk. 9. Always design a secondary drainage route to handle runoff in case of the primary one become clogged. 09/03/2004 /Apinya/KMUTTarc354Site Drainage

/Apinya/KMUTTarc354Site Drainage Grading procedure 1.Topographic characteristic and natural drainage pattern. 2. Locate unusual soil type -- sandy soil, clay. 3. Fixed elevations or points on the site such as roads, trees, adjacent buildings 4. All area that need to be kept dry and elevations 5. The location and extent of the existing sewer system (both public and private system) 09/03/2004 /Apinya/KMUTTarc354Site Drainage

/Apinya/KMUTTarc354Site Drainage 09/03/2004 /Apinya/KMUTTarc354Site Drainage

Grading procedure (*factors) Factors which determine drainage needs are: 1. LAND USE --urban or rural area, function, density and how fast we must drain the water. 2.TOPOGRAPHY --the steeper the area, the faster draining it will be, drainage must be provided above and below steep bank 3. SIZE OF AREA TO BE DRAIN -- determines the size of underground and surface structure. Typically, the larger the area, the larger the underground structures or surface ditches. 4. TYPE OF SOIL -- determines the rate of percolation or amount of water the soil will absorb. 5. VEGETATION -- any thick, matty ground cover will slow down the rate of runoff and reduce the need for elaborate drainage systems. 6. INTENSITY OF RAINFALL -- amount of water from rainfall will affects the type of drainage system . 09/03/2004 /Apinya/KMUTTarc354Site Drainage

Surface drain: Draining level area Most use areas -- play fields, courts, patios, roof garden, etc. require a dry level surface. Level area do not drain well, so we must TILT all use areas slightly to allow water to runoff. REMEMBER to set the building finish floors at least 15 cm. Higher than the outdoor elevation. Sloping plane 09/03/2004 Sloping plane with valley /Apinya/KMUTTarc354Site Drainage Funnel system(+subsurface drainage)

Surface drain: Drainage of steep slope Cut or fill slopes will be erosion. Therefore, must be drained properly with interceptor ditches or terraces. The ditch will carry water to some collection point for dispersal. Ditches constructed in cut areas will usually function without a lining, while those in fill may require a concrete or asphalt lining. 09/03/2004 /Apinya/KMUTTarc354Site Drainage

/Apinya/KMUTTarc354Site Drainage Subsurface drainage: 1. Area drain located at the lowest point in the drainage basin, looks somewhat like a large shower drain. 2. Catch basin like area drain except it has a deep pit to catch sediment and keep it from clogging the pipes. 3. French drain (Trench drain) a linear drain to collect water along the length 4. Culvert A pipe under driveways, paths, etc. 5. Underground pipe pipe used to transport runoff from the collection to distribution. 09/03/2004 /Apinya/KMUTTarc354Site Drainage

/Apinya/KMUTTarc354Site Drainage Subsurface drainage: The closed system is useful in level areas. This method is useful for a variety of specialty problems including: athletic fields or golf course which avoid dangerous catch basins on the field, The cost is expensive. The perforated pipe is installed at the bottom of the gravel with the holds point up. Water fills the gravel and eventually pours into the holds where it can be taken away. This discharge water by gravity through a perforated pipe laid on gravel with the holds pointed down. 09/03/2004 /Apinya/KMUTTarc354Site Drainage

Subsurface drainage: typical sub-drain layout Natural system used in natural area where area drain is needed Herringbone system two way tilt area Gridiron system Interceptor system Depth of underground pipe should be between 75 cm. To 150 cm. Slope of main pipe should be 2-3% max. minor pipe can be at 0.25 minimum. 09/03/2004 /Apinya/KMUTTarc354Site Drainage

/Apinya/KMUTTarc354Site Drainage Drainage system : example Source:Michigan Soil Erosion & Sedimentation Control Guidebook Surface Drainage System: Enclosed Underground Drainage System: 09/03/2004 /Apinya/KMUTTarc354Site Drainage

Drainage system : example Enclosed Underground Drainage with On site storage Combination Drainage System with On site storage 09/03/2004 /Apinya/KMUTTarc354Site Drainage

/Apinya/KMUTTarc354Site Drainage Drainage system : example Source:Michigan Soil Erosion & Sedimentation Control Guidebook 09/03/2004 /Apinya/KMUTTarc354Site Drainage

/Apinya/KMUTTarc354Site Drainage Readings 1. GRADE EASY, Prof. Richard K. Untermann, Department of Landscape Architecture, University of Washington, Seattle. MUST READ 2. Site Planning, Environment, Process, and development, R.Gene Brooks, Prentice Hall, N.J. page 129-171 09/03/2004 /Apinya/KMUTTarc354Site Drainage