Mar 272012
 

Slopes

Sheet flows: Land 1 to 1 ½ % slope, adjacent to building: 2%

Drainage ditches: 2 to 10%

Grass slopes: Maximum 25%; turf: <25% for mowing; 25% max. grassland Un-mowed (planted banks) lawns: Maximum 50% (ivy) [>50%: Avoid erosion]

Flat: 4% or less- Considered
level <4% ; 4% intensive activity Moderate: 4--> 10% slope effect to climb/ descend
easy grade 4%to 10%; 4-10% informal
Steep: 10-50 % steep/ unusable
step grade> 10%; >10% limited
>10% is costly & more complications,
split level = very usual
Grassy recreational <3%; 5%< erosion Un-retained earth cuts: 50% to 100% depending on soil Walk next to buildings max= 4% Minimum slope of land 0.5%, 5% slopes of parking 2% away from building Streets 10% max Storm drains: 0.3% to 1% Short ramp 15% Pedestrians 10% Parking stalls must have slopes of .5 to 10% max if slope is 25 ft in 100 ft run (25%) the area must be regarded as steep. Vehicular slope limit is 15%. Vehicular parking lot ramp: 12% at 32’. Rise @ 8 ft long transitions. If the slope is greater than 10%, then slope of transitions is to be ½ slope of central portion. 12%/2= 6% and 6% of 8 ft= 5.76 “ rise. Pipes are sloped for self- cleansing (0.3% minimum) Drainage ditch = 10% max

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