area measurements from site plans and introduction to winslamm analyses
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Area Measurements from Site Plans and Introduction to WinSLAMM Analyses. Robert Pitt Dept. of Civil and Environmental Engineering University of Alabama Tuscaloosa, AL 35487. Little Shades Creek Subwatersheds. Characteristics of Land Development in Rocky Ridge. Summary of Measured Areas. - PowerPoint PPT PresentationTRANSCRIPT
Area Measurements from Site Plans and Introduction to
WinSLAMM Analyses
Robert PittDept. of Civil and Environmental Engineering
University of AlabamaTuscaloosa, AL 35487
Little Shades Creek Subwatersheds
Area (acres) 1 2 3 4 All others
Total
Single family
339 448 676 401 1747 3611
Town homes
0 20 8 0 94 122
Multi-family 0 47 13 0 27 87
School/
church
0 0 38 13 58 109
Commercial 8 8 17 7 42 82
All other 70 153 199 164 621 1207
Total 417 676 951 585 2589 5218
Characteristics of Land Development in Rocky Ridge Low density
Medium density pre 1960
High density
Strip commercial
Office parks
Directly connected imperviousness
6.11 8.98 15 90.6 60.19
Impervious areas draining to pervious areas
4.7 6.2 9 0 1.14
Pervious Areas 89.19 84.82 76 9.4 38.67
Total 100 100 100 100 100
Summary of Measured Areas
• Totally connected impervious areas: 25.9 acres– parking 15.3 acres– roofs (flat) 8.2 acres– streets (1.2 curb-miles and 33 ft wide) 2.4 acres
• Landscaped/open space 15.4 acres
• Total Area 41.3 acres
Stormwater Controls• Biofiltration areas
– 52 units of 40 ft by 8 ft– Surface area: 320 ft2
– Bottom area: 300 ft2
– Depth: 1 ft – Vertical stand pipe: 0.5 ft. dia. 0.75 ft high– Broad-crested weir overflow: 8 ft long, 0.25 ft wide
and 0.9 ft high– Amended soil: sandy loam
Stormwater Controls (cont.)
• Wet detention pond– Surface area at pond surface:
• 3% of 25.9 paved acres = 0.78 acres• 0.5% of 15.4 unpaved acres = 0.077 acres• Total area: 0.95 acres
– Pond areas different depth:• 0 ft 0 acres 4 ft 0.95 acres• 1 ft 0.1 acres 5 ft 1.15 acres• 2 ft 0.3 acres 6 ft 1.25 acres• 3 ft 0.5 acres 7 ft 1.31 acres
Runoff Volume ChangesBase conditions
With biofiltration
With pond With biofilt. and pond
Runoff volume (106 ft3/yr)
2.85 1.67 2.85 1.67
Average Rv 0.59 0.35 0.59 0.35
Average CN 98 96 98 96
% reduction in volume
n/a 41% 0% 41%
Particulate Solids ChangesBase conditions
With biofiltration
With pond With biofilt. and pond
Particulate solids (lbs/yr)
30,250 27,650 3,660 3,320
Part. size controlled (flw-wgt meters)
n/a n/a 3.2 3.7
% reduc. in discharges
n/a 9% 88% 89%
Residential Area Source AreasArea (acres) Large
lotsSmall lots
Total area
Roofs 0.39 0.52 0.91
Driveways 0.15 0.12 0.27
Sidewalks 0.06 0.04 0.10
Landscaped areas
1.61 1.07 2.68
Subtotals 2.21 1.75 3.96
Streets 0.57
Undeveloped area
1.07
Total area: 5.60 acres
Example Area Calculations for Workshop Problem
Roofs Concrete around buildings
Street areas (widths)
Sidewalks Parking islands
Large landscaped areas
Parking
0.49 (35)
0.3 (20)
0.29 (40)
3.57 acres
2.88 acres
1.08 acres
0.07 acres 1.03 acres
3.98 acres 8.07 acres
17.3% 13.9% 5.2% 0.3% 5.0% 19.3% 39.0%