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 Area (acres)1234All others Total Single family Town homes Multi-family School/ church Commercial All other Total

Characteristics of Land Development in Rocky Ridge Low density Medium density pre 1960 High density Strip commercial Office parks Directly connected imperviousness Impervious areas draining to pervious areas Pervious Areas Total100

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 ft 2 –Bottom area: 300 ft 2 –Depth: 1 ft –Vertical stand pipe: 0.5 ft. dia 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 = acres Total area: 0.95 acres –Pond areas different depth: 0 ft 0 acres4 ft 0.95 acres 1 ft 0.1 acres5 ft 1.15 acres 2 ft 0.3 acres6 ft 1.25 acres 3 ft 0.5 acres7 ft 1.31 acres

Runoff Volume Changes Base conditions With biofiltration With pondWith biofilt. and pond Runoff volume (10 6 ft 3 /yr) Average Rv Average CN % reduction in volume n/a41%0%41%

Particulate Solids Changes Base conditions With biofiltration With pondWith biofilt. and pond Particulate solids (lbs/yr) 30,25027,6503,6603,320 Part. size controlled (flw-wgt  meters) n/a % reduc. in discharges n/a9%88%89%

Residential Area Source Areas Area (acres)Large lots Small lots Total area Roofs Driveways Sidewalks Landscaped areas Subtotals Streets0.57 Undeveloped area 1.07 Total area: 5.60 acres

Example Area Calculations for Workshop Problem RoofsConcrete around buildings Street areas (widths) SidewalksParking 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 acres1.03 acres 3.98 acres8.07 acres 17.3%13.9%5.2%0.3%5.0%19.3%39.0%