Agenda packet — Rancho Mirage City Council, December 4, 2025 (part 3 of 6)

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24 Hour Storm in 15 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:15 0.2 0.04 0.99 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 756.00 0.16 1.68 0.00 0.00 0.00 0:30 0.3 0.06 0.98 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 756.55 0.16 4.27 0.00 0.00 0.00 0:45 0.3 0.06 0.97 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 757.40 0.16 6.86 0.00 0.00 0.00 1:00 0.4 0.08 0.95 0.07 0.0081 0.0041 3.67 0.00 0.00 0.00 0.00 0.00 3.67 758.26 0.16 10.37 0.01 0.00 0.00 1:15 0.3 0.06 0.94 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 759.41 0.16 12.96 0.01 0.00 0.00 1:30 0.3 0.06 0.93 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 760.26 0.16 15.55 0.01 0.00 0.00 1:45 0.3 0.06 0.92 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 761.12 0.16 18.14 0.01 0.00 0.00 2:00 0.4 0.08 0.91 0.07 0.0081 0.0041 3.67 0.00 0.00 0.00 0.00 0.00 3.67 761.97 0.16 21.65 0.02 0.00 0.00 2:15 0.4 0.08 0.90 0.07 0.0081 0.0041 3.67 0.00 0.00 0.00 0.00 0.00 3.67 763.12 0.16 25.16 0.02 0.00 0.00 2:30 0.4 0.08 0.89 0.07 0.0081 0.0041 3.67 0.00 0.00 0.00 0.00 0.00 3.67 764.28 0.16 28.66 0.02 0.00 0.00 2:45 0.5 0.10 0.88 0.09 0.0101 0.0051 4.58 0.00 0.00 0.00 0.00 0.00 4.58 765.43 0.16 33.09 0.02 0.00 0.00 3:00 0.5 0.10 0.87 0.09 0.0101 0.0051 4.58 0.00 0.00 0.00 0.00 0.00 4.58 766.89 0.16 37.51 0.03 0.00 0.00 3:15 0.5 0.10 0.85 0.09 0.0101 0.0051 4.58 0.00 0.00 0.00 0.00 0.00 4.58 768.34 0.16 41.93 0.03 0.00 0.00 3:30 0.5 0.10 0.84 0.09 0.0101 0.0051 4.58 0.00 0.00 0.00 0.00 0.00 4.58 769.80 0.16 46.36 0.03 0.00 0.00 3:45 0.5 0.10 0.83 0.09 0.0101 0.0051 4.58 0.00 0.00 0.00 0.00 0.00 4.58 771.25 0.16 50.78 0.04 0.00 0.00 4:00 0.6 0.12 0.82 0.11 0.0121 0.0061 5.50 0.00 0.00 0.00 0.00 0.00 5.50 772.71 0.16 56.12 0.04 0.00 0.00 4:15 0.6 0.12 0.81 0.11 0.0121 0.0061 5.50 0.00 0.00 0.00 0.00 0.00 5.50 774.46 0.16 61.45 0.04 0.00 0.00 4:30 0.7 0.14 0.80 0.13 0.0141 0.0071 6.42 0.00 0.00 0.00 0.00 0.00 6.42 776.22 0.16 67.71 0.05 0.00 0.00 4:45 0.7 0.14 0.79 0.13 0.0141 0.0071 6.42 0.00 0.00 0.00 0.00 0.00 6.42 778.28 0.16 73.96 0.05 0.00 0.00 5:00 0.8 0.16 0.78 0.15 0.0162 0.0081 7.33 0.00 0.00 0.00 0.00 0.00 7.33 780.34 0.16 81.13 0.06 0.00 0.00 5:15 0.6 0.12 0.77 0.11 0.0121 0.0061 5.50 0.00 0.00 0.00 0.00 0.00 5.50 782.70 0.16 86.47 0.06 0.00 0.00 5:30 0.7 0.14 0.76 0.13 0.0141 0.0071 6.42 0.00 0.00 0.00 0.00 0.00 6.42 784.45 0.16 92.72 0.07 0.00 0.00 5:45 0.8 0.16 0.75 0.15 0.0162 0.0081 7.33 0.00 0.00 0.00 0.00 0.00 7.33 786.51 0.16 99.89 0.07 0.00 0.00 6:00 0.8 0.16 0.74 0.15 0.0162 0.0081 7.33 0.00 0.00 0.00 0.00 0.00 7.33 788.87 0.16 107.06 0.08 0.00 0.00 6:15 0.9 0.18 0.73 0.16 0.0182 0.0092 8.25 0.00 0.00 0.00 0.00 0.00 8.25 791.23 0.16 115.14 0.08 0.00 0.00 6:30 0.9 0.18 0.72 0.16 0.0182 0.0092 8.25 0.00 0.00 0.00 0.00 0.00 8.25 793.89 0.17 123.23 0.09 0.00 0.00 6:45 1 0.20 0.71 0.18 0.0202 0.0102 9.17 0.00 0.00 0.00 0.00 0.00 9.17 796.55 0.17 132.23 0.10 0.00 0.00 7:00 1 0.20 0.70 0.18 0.0202 0.0102 9.17 0.00 0.00 0.00 0.00 0.00 9.17 799.51 0.17 141.23 0.10 0.00 0.00 7:15 1 0.20 0.69 0.18 0.0202 0.0102 9.17 0.00 0.00 0.00 0.00 0.00 9.17 802.47 0.17 150.22 0.11 0.00 0.00 7:30 1.1 0.22 0.68 0.20 0.0222 0.0112 10.08 0.00 0.00 0.00 0.00 0.00 10.08 805.43 0.17 160.14 0.12 0.00 0.00 7:45 1.2 0.24 0.67 0.22 0.0242 0.0122 11.00 0.00 0.00 0.00 0.00 0.00 11.00 808.69 0.17 170.97 0.12 0.00 0.00 8:00 1.3 0.26 0.66 0.24 0.0263 0.0132 11.92 0.00 0.00 0.00 0.00 0.00 11.92 812.25 0.17 182.72 0.13 0.00 0.00 8:15 1.5 0.30 0.66 0.27 0.0303 0.0153 13.75 0.00 0.00 0.00 0.00 0.00 13.75 816.12 0.17 196.29 0.14 0.00 0.00 8:30 1.5 0.30 0.65 0.27 0.0303 0.0153 13.75 0.00 0.00 0.00 0.00 0.00 13.75 820.59 0.17 209.87 0.15 0.00 0.00 8:45 1.6 0.32 0.64 0.29 0.0323 0.0163 14.67 0.00 0.00 0.00 0.00 0.00 14.67 825.06 0.17 224.37 0.16 0.00 0.00 9:00 1.7 0.34 0.63 0.31 0.0343 0.0173 15.58 0.00 0.00 0.00 0.00 0.00 15.58 829.82 0.17 239.77 0.17 0.00 0.00 9:15 1.9 0.38 0.62 0.35 0.0384 0.0193 17.41 0.00 0.00 0.00 0.00 0.00 17.41 834.89 0.17 257.02 0.19 0.00 0.00 9:30 2 0.40 0.61 0.36 0.0404 0.0204 18.33 0.00 0.00 0.00 0.00 0.00 18.33 840.57 0.18 275.17 0.20 0.00 0.00 9:45 2.1 0.42 0.60 0.38 0.0424 0.0214 19.25 0.00 0.00 0.00 0.00 0.00 19.25 846.54 0.18 294.24 0.21 0.00 0.00 10:00 2.2 0.44 0.59 0.40 0.0444 0.0224 20.16 0.00 0.00 0.00 0.00 0.00 20.16 852.82 0.18 314.23 0.23 0.00 0.00 10:15 1.5 0.30 0.58 0.27 0.0303 0.0153 13.75 0.00 0.00 0.00 0.00 0.00 13.75 859.39 0.18 327.80 0.24 0.00 0.00 10:30 1.5 0.30 0.58 0.27 0.0303 0.0153 13.75 0.00 0.00 0.00 0.00 0.00 13.75 863.86 0.18 341.37 0.25 0.00 0.00 10:45 2 0.40 0.57 0.36 0.0404 0.0204 18.33 0.00 0.00 0.00 0.00 0.00 18.33 868.32 0.18 359.52 0.26 0.00 0.00 11:00 2 0.40 0.56 0.36 0.0404 0.0204 18.33 0.00 0.00 0.00 0.00 0.00 18.33 874.29 0.18 377.67 0.27 0.00 0.00 11:15 1.9 0.38 0.55 0.35 0.0384 0.0193 17.41 0.00 0.00 0.00 0.00 0.00 17.41 880.27 0.18 394.90 0.29 0.00 0.00 11:30 1.9 0.38 0.54 0.35 0.0384 0.0193 17.41 0.00 0.00 0.00 0.00 0.00 17.41 885.94 0.18 412.13 0.30 0.00 0.00 11:45 1.7 0.34 0.53 0.31 0.0343 0.0173 15.58 0.00 0.00 0.00 0.00 0.00 15.58 891.60 0.19 427.53 0.31 0.00 0.00 12:00 1.8 0.36 0.53 0.33 0.0364 0.0183 16.50 0.00 0.00 0.00 0.00 0.00 16.50 896.67 0.19 443.84 0.32 0.00 0.00 12:15 2.5 0.51 0.52 0.45 0.0505 0.0255 22.91 0.00 0.00 0.00 0.00 0.00 22.91 902.04 0.19 466.56 0.34 0.00 0.00 12:30 2.6 0.53 0.51 0.47 0.0525 0.0265 23.83 0.00 0.00 0.00 0.00 0.00 23.83 909.52 0.19 490.21 0.36 0.00 0.00 12:45 2.8 0.57 0.50 N/A 0.0622 0.0314 28.24 0.00 0.00 0.00 0.00 0.00 28.24 917.29 0.19 518.25 0.38 0.00 0.00 450

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13:00 2.9 0.59 0.50 N/A 0.0900 0.0454 40.85 0.00 0.00 0.00 0.00 0.00 40.85 926.52 0.19 558.91 0.41 0.00 0.00 13:15 3.4 0.69 0.49 N/A 0.1985 0.1001 90.08 0.00 0.00 0.00 0.00 0.00 90.08 939.90 0.20 648.80 0.47 0.00 0.00 13:30 3.4 0.69 0.48 N/A 0.2059 0.1038 93.45 0.00 0.00 0.00 0.00 0.00 93.45 969.48 0.20 742.04 0.54 0.00 0.00 13:45 2.3 0.46 0.47 0.42 0.0465 0.0234 21.08 0.00 0.00 0.00 0.00 0.00 21.08 1000.16 0.21 762.91 0.55 0.00 0.00 14:00 2.3 0.46 0.47 0.42 0.0465 0.0234 21.08 0.00 0.00 0.00 0.00 0.00 21.08 1007.02 0.21 783.78 0.57 0.00 0.00 14:15 2.7 0.55 0.46 N/A 0.0862 0.0435 39.11 0.00 0.00 0.00 0.00 0.00 39.11 1013.89 0.21 822.68 0.60 0.00 0.00 14:30 2.6 0.53 0.45 N/A 0.0730 0.0368 33.12 0.00 0.00 0.00 0.00 0.00 33.12 1026.69 0.21 855.59 0.62 0.00 0.00 14:45 2.6 0.53 0.45 N/A 0.0799 0.0403 36.26 0.00 0.00 0.00 0.00 0.00 36.26 1037.52 0.22 891.63 0.65 0.00 0.00 15:00 2.5 0.51 0.44 N/A 0.0665 0.0335 30.19 0.00 0.00 0.00 0.00 0.00 30.19 1049.38 0.22 921.60 0.67 0.00 0.00 15:15 2.4 0.48 0.43 N/A 0.0530 0.0267 24.07 0.00 0.00 0.00 0.00 0.00 24.07 1059.24 0.22 945.45 0.69 0.00 0.00 15:30 2.3 0.46 0.43 0.42 0.0465 0.0234 21.08 0.00 0.00 0.00 0.00 0.00 21.08 1067.08 0.22 966.30 0.70 0.00 0.00 15:45 1.9 0.38 0.42 0.35 0.0384 0.0193 17.41 0.00 0.00 0.00 0.00 0.00 17.41 1073.95 0.22 983.50 0.71 0.00 0.00 16:00 1.9 0.38 0.41 0.35 0.0384 0.0193 17.41 0.00 0.00 0.00 0.00 0.00 17.41 1079.60 0.22 1000.69 0.73 0.00 0.00 16:15 0.4 0.08 0.41 0.07 0.0081 0.0041 3.67 0.00 0.00 0.00 0.00 0.00 3.67 1085.26 0.23 1004.13 0.73 0.00 0.00 16:30 0.4 0.08 0.40 0.07 0.0081 0.0041 3.67 0.00 0.00 0.00 0.00 0.00 3.67 1086.39 0.23 1007.57 0.73 0.00 0.00 16:45 0.3 0.06 0.39 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1087.52 0.23 1010.09 0.73 0.00 0.00 17:00 0.3 0.06 0.39 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1088.35 0.23 1012.61 0.73 0.00 0.00 17:15 0.5 0.10 0.38 0.09 0.0101 0.0051 4.58 0.00 0.00 0.00 0.00 0.00 4.58 1089.18 0.23 1016.97 0.74 0.00 0.00 17:30 0.5 0.10 0.38 0.09 0.0101 0.0051 4.58 0.00 0.00 0.00 0.00 0.00 4.58 1090.62 0.23 1021.32 0.74 0.00 0.00 17:45 0.5 0.10 0.37 0.09 0.0101 0.0051 4.58 0.00 0.00 0.00 0.00 0.00 4.58 1092.05 0.23 1025.68 0.74 0.00 0.00 18:00 0.4 0.08 0.37 0.07 0.0081 0.0041 3.67 0.00 0.00 0.00 0.00 0.00 3.67 1093.48 0.23 1029.12 0.75 0.00 0.00 18:15 0.4 0.08 0.36 0.07 0.0081 0.0041 3.67 0.00 0.00 0.00 0.00 0.00 3.67 1094.61 0.23 1032.56 0.75 0.00 0.00 18:30 0.4 0.08 0.35 0.07 0.0081 0.0041 3.67 0.00 0.00 0.00 0.00 0.00 3.67 1095.75 0.23 1035.99 0.75 0.00 0.00 18:45 0.3 0.06 0.35 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1096.88 0.23 1038.51 0.75 0.00 0.00 19:00 0.2 0.04 0.34 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1097.71 0.23 1040.12 0.75 0.00 0.00 19:15 0.3 0.06 0.34 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1098.23 0.23 1042.64 0.76 0.00 0.00 19:30 0.4 0.08 0.34 0.07 0.0081 0.0041 3.67 0.00 0.00 0.00 0.00 0.00 3.67 1099.06 0.23 1046.08 0.76 0.00 0.00 19:45 0.3 0.06 0.33 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1100.20 0.23 1048.60 0.76 0.00 0.00 20:00 0.2 0.04 0.33 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1101.02 0.23 1050.20 0.76 0.00 0.00 20:15 0.3 0.06 0.32 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1101.55 0.23 1052.72 0.76 0.00 0.00 20:30 0.3 0.06 0.32 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1102.38 0.23 1055.24 0.76 0.00 0.00 20:45 0.3 0.06 0.31 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1103.21 0.23 1057.76 0.77 0.00 0.00 21:00 0.2 0.04 0.31 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1104.04 0.23 1059.37 0.77 0.00 0.00 21:15 0.3 0.06 0.31 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1104.57 0.23 1061.88 0.77 0.00 0.00 21:30 0.2 0.04 0.30 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1105.40 0.23 1063.49 0.77 0.00 0.00 21:45 0.3 0.06 0.30 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1105.92 0.23 1066.01 0.77 0.00 0.00 22:00 0.2 0.04 0.30 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1106.75 0.23 1067.61 0.77 0.00 0.00 22:15 0.3 0.06 0.29 0.05 0.0061 0.0031 2.75 0.00 0.00 0.00 0.00 0.00 2.75 1107.28 0.23 1070.13 0.78 0.00 0.00 22:30 0.2 0.04 0.29 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1108.11 0.23 1071.73 0.78 0.00 0.00 22:45 0.2 0.04 0.29 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1108.64 0.23 1073.33 0.78 0.00 0.00 23:00 0.2 0.04 0.29 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1109.16 0.23 1074.94 0.78 0.00 0.00 23:15 0.2 0.04 0.28 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1109.69 0.23 1076.54 0.78 0.00 0.00 23:30 0.2 0.04 0.28 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1110.22 0.23 1078.14 0.78 0.00 0.00 23:45 0.2 0.04 0.28 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1110.74 0.23 1079.74 0.78 0.00 0.00 24:00 0.2 0.04 0.28 0.04 0.0040 0.0020 1.83 0.00 0.00 0.00 0.00 0.00 1.83 1111.27 0.23 1081.34 0.78 0.00 0.00 0 0.00 0.28 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1111.80 0.23 1081.11 0.78 0.00 0.00 Total volume (cf)1100.04 Total Overflow (cf)0.00
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HYDROLOGY CALCULATIONS - program updated 4-14-22 LC
Using the RCFC&WCD Short Cut Unit Hydrograph Method
Area Designations Area 1 VERSION 2 Area=1.14ac
5/7/2024 LOT 12-BACK
Drainage Area (ac.)1.1400 JOB NUMBER 22106
Unit time (minutes)5 5 5 15
100 Year Storm Duration (hrs)1 3 6 24
Total Precipitation (Plates D-4.4,E-5.2, 5.4, 5.6)(in.)2.41 3.10 3.79 5.05 from NOAA interactive website Soils Group A
AMC index II Runoff Number (plate E-6.1)32
Plate E-6.2 Pervious Area Loss Rate (Fp)(in/hr)0.74 (AMC II) Percentage of Impervious Cover (Ai)(%) (plate E-6.3)26.6 20% per the RCFC Hydrology Manual 1AC LOT-PLATE D 5.6 Weighted Average Loss Rate (F=Fp(1-.9Ai))(in./hr.)0.56 (used for 1, 3, and 6 hour storm, the 24 hour storm uses variable maximum loss rate per plate E-1.1 (3 of 6)) Low Loss Rate Percent (%) 90
Retention Basin Percolation Rate (in/hr)0.01 (also used for drywell percolation rate) Percolation is taken incrementally.

Basin volume is calculated using the "truncated pyramid" formula, a more conservative estimate than "averaged end areas" sometimes used (Drywell can be "zeroed out" by reducing numbers to less than .001, but should not entered as zeros or program chokes.) Drywell storage includes 40% of the 1' wide rock bed surrounding the drywell: formula (upper)*PI()*(diam/2)^2+(lower)*PI()*((diam/2)^2+0.4*((diam/2+(grav+0.4166))^2-(diam/2+0.4166)^2)) The drywell wall thickness is assumed at 5" (0.4166) and the gravel bed width is variable "grav" Drywell is zeroed out by reducing to 0.001 since there is none.

Drywell design factors Upper sec. (ft.)=0.001 Lower sec. (ft.)=0.001 Ring diam. (ft.) =0.001 Drywell lower max. (cf)=0.00 Upper max.(cf)=0.00 Gravel bed width around drywell=0.001 Drywell total(cf)=0.00 Ret. Basin design (area, depth) Top =3132 s.f.Bot. =947 s.f.Max. Depth (d)=4 Max. storage=7734.95 (d/3)*(bottom+top+(bottom*top)^0.50) Formulas vol=(h/3)*(bottom+top+(bottom*top)^0.50) area=bottom+(h/d)*(top-bottom)h=(vol*3)/(bottom+top+(bottom*top)^0.5)(values must be non-zero or error occurs) Outside input from:N/A 3.25
1 Hour Storm in 5 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:05 3.7 1.0700 0.5628 N/A 0.5072 0.5830 174.91 0.00 0.00 0.00 0.00 0.00 174.91 947.00 0.07 174.84 0.09 0.00 0.00 0:10 4.8 1.3882 0.5628 N/A 0.8253 0.9487 284.61 0.00 0.00 0.00 0.00 0.00 284.61 996.39 0.07 459.38 0.24 0.00 0.00 0:15 5.1 1.4749 0.5628 N/A 0.9121 1.0484 314.53 0.00 0.00 0.00 0.00 0.00 314.53 1076.77 0.07 773.84 0.40 0.00 0.00 0:20 4.9 1.4171 0.5628 N/A 0.8542 0.9819 294.58 0.00 0.00 0.00 0.00 0.00 294.58 1165.60 0.08 1068.34 0.55 0.00 0.00 0:25 6.6 1.9087 0.5628 N/A 1.3459 1.5471 464.13 0.00 0.00 0.00 0.00 0.00 464.13 1248.79 0.09 1532.38 0.79 0.00 0.00 0:30 7.3 2.1112 0.5628 N/A 1.5483 1.7798 533.94 0.00 0.00 0.00 0.00 0.00 533.94 1379.87 0.10 2066.22 1.07 0.00 0.00 0:35 8.4 2.4293 0.5628 N/A 1.8664 2.1455 643.64 0.00 0.00 0.00 0.00 0.00 643.64 1530.67 0.11 2709.75 1.40 0.00 0.00 0:40 9 2.6028 0.5628 N/A 2.0400 2.3449 703.48 0.00 0.00 0.00 0.00 0.00 703.48 1712.46 0.12 3413.11 1.77 0.00 0.00 0:45 12.3 3.5572 0.5628 N/A 2.9943 3.4420 1032.59 0.00 0.00 0.00 0.00 0.00 1032.59 1911.15 0.13 4445.57 2.30 0.00 0.00 0:50 17.6 5.0899 0.5628 N/A 4.5271 5.2039 1561.16 0.00 0.00 0.00 0.00 0.00 1561.16 2202.80 0.15 6006.58 3.11 0.00 0.00 0:55 16.1 4.6561 0.5628 N/A 4.0933 4.7052 1411.57 0.00 0.00 0.00 0.00 0.00 1411.57 2643.76 0.18 7417.96 3.84 0.00 0.00 1:00 4.2 1.2146 0.5628 N/A 0.6518 0.7492 224.77 0.00 0.00 0.00 0.00 0.00 224.77 3042.46 0.21 7642.52 3.95 0.00 0.00 MAX DEPTH 0 0.0000 0.5628 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3105.89 0.22 7642.31 3.95 0.00 0.00 0 0.0000 0.5628 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3105.83 0.22 7642.09 3.95 0.00 0.00 1:15 0 0.0000 0.5628 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3105.77 0.22 7641.87 3.95 0.00 0.00 Total volume (cf)7643.90 Total Overflow (cf)0.00
452
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3 Hour Storm in 5 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:05 1.3 0.48 0.56 0.44 0.0484 0.0556 16.68 0.00 0.00 0.00 0.00 0.00 16.68 947.00 0.07 16.61 0.01 0.00 0.00 0:10 1.3 0.48 0.56 0.44 0.0484 0.0556 16.68 0.00 0.00 0.00 0.00 0.00 16.68 951.69 0.07 33.22 0.02 0.00 0.00 0:15 1.1 0.41 0.56 0.37 0.0409 0.0470 14.11 0.00 0.00 0.00 0.00 0.00 14.11 956.38 0.07 47.27 0.02 0.00 0.00 0:20 1.5 0.56 0.56 0.50 0.0558 0.0641 19.24 0.00 0.00 0.00 0.00 0.00 19.24 960.35 0.07 66.44 0.03 0.00 0.00 0:25 1.5 0.56 0.56 0.50 0.0558 0.0641 19.24 0.00 0.00 0.00 0.00 0.00 19.24 965.77 0.07 85.62 0.04 0.00 0.00 0:30 1.8 0.67 0.56 N/A 0.1068 0.1227 36.81 0.00 0.00 0.00 0.00 0.00 36.81 971.19 0.07 122.37 0.06 0.00 0.00 0:35 1.5 0.56 0.56 0.50 0.0558 0.0641 19.24 0.00 0.00 0.00 0.00 0.00 19.24 981.57 0.07 141.54 0.07 0.00 0.00 0:40 1.8 0.67 0.56 N/A 0.1068 0.1227 36.81 0.00 0.00 0.00 0.00 0.00 36.81 986.98 0.07 178.29 0.09 0.00 0.00 0:45 1.8 0.67 0.56 N/A 0.1068 0.1227 36.81 0.00 0.00 0.00 0.00 0.00 36.81 997.36 0.07 215.03 0.11 0.00 0.00 0:50 1.5 0.56 0.56 0.50 0.0558 0.0641 19.24 0.00 0.00 0.00 0.00 0.00 19.24 1007.74 0.07 234.20 0.12 0.00 0.00 0:55 1.6 0.60 0.56 0.54 0.0595 0.0684 20.53 0.00 0.00 0.00 0.00 0.00 20.53 1013.16 0.07 254.66 0.13 0.00 0.00 1:00 1.8 0.67 0.56 N/A 0.1068 0.1227 36.81 0.00 0.00 0.00 0.00 0.00 36.81 1018.94 0.07 291.40 0.15 0.00 0.00 1:05 2.2 0.82 0.56 N/A 0.2556 0.2938 88.13 0.00 0.00 0.00 0.00 0.00 88.13 1029.32 0.07 379.46 0.20 0.00 0.00 1:10 2.2 0.82 0.56 N/A 0.2556 0.2938 88.13 0.00 0.00 0.00 0.00 0.00 88.13 1054.19 0.07 467.52 0.24 0.00 0.00 1:15 2.2 0.82 0.56 N/A 0.2556 0.2938 88.13 0.00 0.00 0.00 0.00 0.00 88.13 1079.07 0.07 555.57 0.29 0.00 0.00 1:20 2 0.74 0.56 N/A 0.1812 0.2082 62.47 0.00 0.00 0.00 0.00 0.00 62.47 1103.94 0.08 617.96 0.32 0.00 0.00 1:25 2.6 0.97 0.56 N/A 0.4044 0.4648 139.44 0.00 0.00 0.00 0.00 0.00 139.44 1121.57 0.08 757.33 0.39 0.00 0.00 1:30 2.7 1.00 0.56 N/A 0.4416 0.5076 152.27 0.00 0.00 0.00 0.00 0.00 152.27 1160.93 0.08 909.52 0.47 0.00 0.00 1:35 2.4 0.89 0.56 N/A 0.3300 0.3793 113.79 0.00 0.00 0.00 0.00 0.00 113.79 1203.92 0.08 1023.22 0.53 0.00 0.00 1:40 2.7 1.00 0.56 N/A 0.4416 0.5076 152.27 0.00 0.00 0.00 0.00 0.00 152.27 1236.04 0.09 1175.41 0.61 0.00 0.00 1:45 3.3 1.23 0.56 N/A 0.6648 0.7641 229.24 0.00 0.00 0.00 0.00 0.00 229.24 1279.03 0.09 1404.56 0.73 0.00 0.00 1:50 3.1 1.15 0.56 N/A 0.5904 0.6786 203.58 0.00 0.00 0.00 0.00 0.00 203.58 1343.77 0.09 1608.05 0.83 0.00 0.00 1:55 2.9 1.08 0.56 N/A 0.5160 0.5931 177.93 0.00 0.00 0.00 0.00 0.00 177.93 1401.25 0.10 1785.88 0.92 0.00 0.00 2:00 3 1.12 0.56 N/A 0.5532 0.6359 190.76 0.00 0.00 0.00 0.00 0.00 190.76 1451.48 0.10 1976.53 1.02 0.00 0.00 2:05 3.1 1.15 0.56 N/A 0.5904 0.6786 203.58 0.00 0.00 0.00 0.00 0.00 203.58 1505.34 0.10 2180.01 1.13 0.00 0.00 2:10 4.2 1.56 0.56 N/A 0.9996 1.1490 344.70 0.00 0.00 0.00 0.00 0.00 344.70 1562.82 0.11 2524.60 1.31 0.00 0.00 2:15 5 1.86 0.56 N/A 1.2972 1.4911 447.32 0.00 0.00 0.00 0.00 0.00 447.32 1660.16 0.12 2971.81 1.54 0.00 0.00 2:20 3.5 1.30 0.56 N/A 0.7392 0.8497 254.90 0.00 0.00 0.00 0.00 0.00 254.90 1786.49 0.12 3226.58 1.67 0.00 0.00 2:25 6.8 2.53 0.56 N/A 1.9668 2.2608 678.24 0.00 0.00 0.00 0.00 0.00 678.24 1858.46 0.13 3904.69 2.02 0.00 0.00 2:30 7.3 2.72 0.56 N/A 2.1528 2.4746 742.38 0.00 0.00 0.00 0.00 0.00 742.38 2050.01 0.14 4646.93 2.40 0.00 0.00 2:35 8.2 3.05 0.56 N/A 2.4876 2.8594 857.83 0.00 0.00 0.00 0.00 0.00 857.83 2259.68 0.16 5504.60 2.85 0.00 0.00 2:40 5.9 2.19 0.56 N/A 1.6320 1.8759 562.78 0.00 0.00 0.00 0.00 0.00 562.78 2501.96 0.17 6067.21 3.14 0.00 0.00 2:45 2 0.74 0.56 N/A 0.1812 0.2082 62.47 0.00 0.00 0.00 0.00 0.00 62.47 2660.89 0.18 6129.50 3.17 0.00 0.00 2:50 1.8 0.67 0.56 N/A 0.1068 0.1227 36.81 0.00 0.00 0.00 0.00 0.00 36.81 2678.49 0.19 6166.13 3.19 0.00 0.00 2:55 1.8 0.67 0.56 N/A 0.1068 0.1227 36.81 0.00 0.00 0.00 0.00 0.00 36.81 2688.83 0.19 6202.75 3.21 0.00 0.00 3:00 0.6 0.22 0.56 0.20 0.0223 0.0257 7.70 0.00 0.00 0.00 0.00 0.00 7.70 2699.18 0.19 6210.26 3.21 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2701.30 0.19 6210.08 3.21 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2701.25 0.19 6209.89 3.21 0.00 0.00 3:15 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2701.20 0.19 6209.70 3.21 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2701.14 0.19 6209.51 3.21 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2701.09 0.19 6209.33 3.21 0.00 0.00 3:30 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2701.04 0.19 6209.14 3.21 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2700.98 0.19 6208.95 3.21 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2700.93 0.19 6208.76 3.21 0.00 0.00 Total volume (cf)6213.88 Total Overflow (cf)0.00
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6 Hour Storm in 5 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:05 0.5 0.23 0.56 0.20 0.0227 0.0261 7.84 0.00 0.00 0.00 0.00 0.00 7.84 947.00 0.07 7.78 0.00 0.00 0.00 0:10 0.6 0.27 0.56 0.25 0.0273 0.0314 9.41 0.00 0.00 0.00 0.00 0.00 9.41 949.20 0.07 17.12 0.01 0.00 0.00 0:15 0.6 0.27 0.56 0.25 0.0273 0.0314 9.41 0.00 0.00 0.00 0.00 0.00 9.41 951.84 0.07 26.46 0.01 0.00 0.00 0:20 0.6 0.27 0.56 0.25 0.0273 0.0314 9.41 0.00 0.00 0.00 0.00 0.00 9.41 954.48 0.07 35.81 0.02 0.00 0.00 0:25 0.6 0.27 0.56 0.25 0.0273 0.0314 9.41 0.00 0.00 0.00 0.00 0.00 9.41 957.12 0.07 45.15 0.02 0.00 0.00 0:30 0.7 0.32 0.56 0.29 0.0318 0.0366 10.98 0.00 0.00 0.00 0.00 0.00 10.98 959.75 0.07 56.06 0.03 0.00 0.00 0:35 0.7 0.32 0.56 0.29 0.0318 0.0366 10.98 0.00 0.00 0.00 0.00 0.00 10.98 962.84 0.07 66.98 0.03 0.00 0.00 0:40 0.7 0.32 0.56 0.29 0.0318 0.0366 10.98 0.00 0.00 0.00 0.00 0.00 10.98 965.92 0.07 77.89 0.04 0.00 0.00 0:45 0.7 0.32 0.56 0.29 0.0318 0.0366 10.98 0.00 0.00 0.00 0.00 0.00 10.98 969.00 0.07 88.80 0.05 0.00 0.00 0:50 0.7 0.32 0.56 0.29 0.0318 0.0366 10.98 0.00 0.00 0.00 0.00 0.00 10.98 972.08 0.07 99.71 0.05 0.00 0.00 0:55 0.7 0.32 0.56 0.29 0.0318 0.0366 10.98 0.00 0.00 0.00 0.00 0.00 10.98 975.17 0.07 110.62 0.06 0.00 0.00 1:00 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 978.25 0.07 123.10 0.06 0.00 0.00 1:05 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 981.77 0.07 135.58 0.07 0.00 0.00 1:10 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 985.30 0.07 148.06 0.08 0.00 0.00 1:15 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 988.82 0.07 160.54 0.08 0.00 0.00 1:20 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 992.35 0.07 173.01 0.09 0.00 0.00 1:25 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 995.87 0.07 185.49 0.10 0.00 0.00 1:30 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 999.40 0.07 197.97 0.10 0.00 0.00 1:35 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 1002.92 0.07 210.45 0.11 0.00 0.00 1:40 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 1006.45 0.07 222.92 0.12 0.00 0.00 1:45 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 1009.97 0.07 235.40 0.12 0.00 0.00 1:50 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 1013.50 0.07 247.88 0.13 0.00 0.00 1:55 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 1017.02 0.07 260.35 0.13 0.00 0.00 2:00 0.9 0.41 0.56 0.37 0.0409 0.0471 14.12 0.00 0.00 0.00 0.00 0.00 14.12 1020.55 0.07 274.40 0.14 0.00 0.00 2:05 0.8 0.36 0.56 0.33 0.0364 0.0418 12.55 0.00 0.00 0.00 0.00 0.00 12.55 1024.51 0.07 286.87 0.15 0.00 0.00 2:10 0.9 0.41 0.56 0.37 0.0409 0.0471 14.12 0.00 0.00 0.00 0.00 0.00 14.12 1028.04 0.07 300.92 0.16 0.00 0.00 2:15 0.9 0.41 0.56 0.37 0.0409 0.0471 14.12 0.00 0.00 0.00 0.00 0.00 14.12 1032.00 0.07 314.96 0.16 0.00 0.00 2:20 0.9 0.41 0.56 0.37 0.0409 0.0471 14.12 0.00 0.00 0.00 0.00 0.00 14.12 1035.97 0.07 329.01 0.17 0.00 0.00 2:25 0.9 0.41 0.56 0.37 0.0409 0.0471 14.12 0.00 0.00 0.00 0.00 0.00 14.12 1039.94 0.07 343.05 0.18 0.00 0.00 2:30 0.9 0.41 0.56 0.37 0.0409 0.0471 14.12 0.00 0.00 0.00 0.00 0.00 14.12 1043.91 0.07 357.09 0.18 0.00 0.00 2:35 0.9 0.41 0.56 0.37 0.0409 0.0471 14.12 0.00 0.00 0.00 0.00 0.00 14.12 1047.87 0.07 371.13 0.19 0.00 0.00 2:40 0.9 0.41 0.56 0.37 0.0409 0.0471 14.12 0.00 0.00 0.00 0.00 0.00 14.12 1051.84 0.07 385.18 0.20 0.00 0.00 2:45 1 0.45 0.56 0.41 0.0455 0.0523 15.68 0.00 0.00 0.00 0.00 0.00 15.68 1055.81 0.07 400.79 0.21 0.00 0.00 2:50 1 0.45 0.56 0.41 0.0455 0.0523 15.68 0.00 0.00 0.00 0.00 0.00 15.68 1060.22 0.07 416.40 0.22 0.00 0.00 2:55 1 0.45 0.56 0.41 0.0455 0.0523 15.68 0.00 0.00 0.00 0.00 0.00 15.68 1064.63 0.07 432.01 0.22 0.00 0.00 3:00 1 0.45 0.56 0.41 0.0455 0.0523 15.68 0.00 0.00 0.00 0.00 0.00 15.68 1069.04 0.07 447.62 0.23 0.00 0.00 3:05 1 0.45 0.56 0.41 0.0455 0.0523 15.68 0.00 0.00 0.00 0.00 0.00 15.68 1073.44 0.07 463.23 0.24 0.00 0.00 3:10 1.1 0.50 0.56 0.45 0.0500 0.0575 17.25 0.00 0.00 0.00 0.00 0.00 17.25 1077.85 0.07 480.40 0.25 0.00 0.00 3:15 1.1 0.50 0.56 0.45 0.0500 0.0575 17.25 0.00 0.00 0.00 0.00 0.00 17.25 1082.71 0.08 497.58 0.26 0.00 0.00 3:20 1.1 0.50 0.56 0.45 0.0500 0.0575 17.25 0.00 0.00 0.00 0.00 0.00 17.25 1087.56 0.08 514.76 0.27 0.00 0.00 3:25 1.2 0.55 0.56 0.49 0.0546 0.0627 18.82 0.00 0.00 0.00 0.00 0.00 18.82 1092.41 0.08 533.50 0.28 0.00 0.00 3:30 1.3 0.59 0.56 0.53 0.0591 0.0680 20.39 0.00 0.00 0.00 0.00 0.00 20.39 1097.71 0.08 553.81 0.29 0.00 0.00 3:35 1.4 0.64 0.56 N/A 0.0739 0.0849 25.48 0.00 0.00 0.00 0.00 0.00 25.48 1103.44 0.08 579.21 0.30 0.00 0.00 3:40 1.4 0.64 0.56 N/A 0.0739 0.0849 25.48 0.00 0.00 0.00 0.00 0.00 25.48 1110.62 0.08 604.61 0.31 0.00 0.00 3:45 1.5 0.68 0.56 N/A 0.1194 0.1372 41.16 0.00 0.00 0.00 0.00 0.00 41.16 1117.79 0.08 645.70 0.33 0.00 0.00 3:50 1.5 0.68 0.56 N/A 0.1194 0.1372 41.16 0.00 0.00 0.00 0.00 0.00 41.16 1129.40 0.08 686.78 0.36 0.00 0.00 3:55 1.6 0.73 0.56 N/A 0.1648 0.1895 56.84 0.00 0.00 0.00 0.00 0.00 56.84 1141.00 0.08 743.54 0.38 0.00 0.00 4:00 1.6 0.73 0.56 N/A 0.1648 0.1895 56.84 0.00 0.00 0.00 0.00 0.00 56.84 1157.04 0.08 800.30 0.41 0.00 0.00 4:05 1.7 0.77 0.56 N/A 0.2103 0.2418 72.53 0.00 0.00 0.00 0.00 0.00 72.53 1173.07 0.08 872.75 0.45 0.00 0.00 4:10 1.8 0.82 0.56 N/A 0.2558 0.2940 88.21 0.00 0.00 0.00 0.00 0.00 88.21 1193.54 0.08 960.88 0.50 0.00 0.00 4:15 1.9 0.86 0.56 N/A 0.3013 0.3463 103.90 0.00 0.00 0.00 0.00 0.00 103.90 1218.43 0.08 1064.69 0.55 0.00 0.00 454

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4:20 2 0.91 0.56 N/A 0.3468 0.3986 119.58 0.00 0.00 0.00 0.00 0.00 119.58 1247.76 0.09 1184.18 0.61 0.00 0.00 4:25 2.1 0.96 0.56 N/A 0.3922 0.4509 135.26 0.00 0.00 0.00 0.00 0.00 135.26 1281.51 0.09 1319.35 0.68 0.00 0.00 4:30 2.1 0.96 0.56 N/A 0.3922 0.4509 135.26 0.00 0.00 0.00 0.00 0.00 135.26 1319.70 0.09 1454.53 0.75 0.00 0.00 4:35 2.2 1.00 0.56 N/A 0.4377 0.5032 150.95 0.00 0.00 0.00 0.00 0.00 150.95 1357.88 0.09 1605.38 0.83 0.00 0.00 4:40 2.3 1.05 0.56 N/A 0.4832 0.5554 166.63 0.00 0.00 0.00 0.00 0.00 166.63 1400.49 0.10 1771.91 0.92 0.00 0.00 4:45 2.4 1.09 0.56 N/A 0.5287 0.6077 182.31 0.00 0.00 0.00 0.00 0.00 182.31 1447.54 0.10 1954.12 1.01 0.00 0.00 4:50 2.4 1.09 0.56 N/A 0.5287 0.6077 182.31 0.00 0.00 0.00 0.00 0.00 182.31 1499.01 0.10 2136.33 1.10 0.00 0.00 4:55 2.5 1.14 0.56 N/A 0.5742 0.6600 198.00 0.00 0.00 0.00 0.00 0.00 198.00 1550.48 0.11 2334.22 1.21 0.00 0.00 5:00 2.6 1.18 0.56 N/A 0.6196 0.7123 213.68 0.00 0.00 0.00 0.00 0.00 213.68 1606.38 0.11 2547.79 1.32 0.00 0.00 5:05 3.1 1.41 0.56 N/A 0.8470 0.9737 292.10 0.00 0.00 0.00 0.00 0.00 292.10 1666.71 0.12 2839.78 1.47 0.00 0.00 5:10 3.6 1.64 0.56 N/A 1.0744 1.2351 370.52 0.00 0.00 0.00 0.00 0.00 370.52 1749.19 0.12 3210.18 1.66 0.00 0.00 5:15 3.9 1.77 0.56 N/A 1.2109 1.3919 417.57 0.00 0.00 0.00 0.00 0.00 417.57 1853.82 0.13 3627.62 1.88 0.00 0.00 5:20 4.2 1.91 0.56 N/A 1.3473 1.5487 464.62 0.00 0.00 0.00 0.00 0.00 464.62 1971.74 0.14 4092.10 2.12 0.00 0.00 5:25 4.7 2.14 0.56 N/A 1.5747 1.8101 543.04 0.00 0.00 0.00 0.00 0.00 543.04 2102.95 0.15 4635.00 2.40 0.00 0.00 5:30 5.6 2.55 0.56 N/A 1.9840 2.2806 684.19 0.00 0.00 0.00 0.00 0.00 684.19 2256.31 0.16 5319.04 2.75 0.00 0.00 5:35 1.9 0.86 0.56 N/A 0.3013 0.3463 103.90 0.00 0.00 0.00 0.00 0.00 103.90 2449.54 0.17 5422.76 2.80 0.00 0.00 5:40 0.9 0.41 0.56 0.37 0.0409 0.0471 14.12 0.00 0.00 0.00 0.00 0.00 14.12 2478.84 0.17 5436.70 2.81 0.00 0.00 5:45 0.6 0.27 0.56 0.25 0.0273 0.0314 9.41 0.00 0.00 0.00 0.00 0.00 9.41 2482.78 0.17 5445.94 2.82 0.00 0.00 5:50 0.5 0.23 0.56 0.20 0.0227 0.0261 7.84 0.00 0.00 0.00 0.00 0.00 7.84 2485.39 0.17 5453.61 2.82 0.00 0.00 5:55 0.3 0.14 0.56 0.12 0.0136 0.0157 4.71 0.00 0.00 0.00 0.00 0.00 4.71 2487.56 0.17 5458.14 2.82 0.00 0.00 6:00 0.2 0.09 0.56 0.08 0.0091 0.0105 3.14 0.00 0.00 0.00 0.00 0.00 3.14 2488.84 0.17 5461.11 2.82 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.68 0.17 5460.93 2.82 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.63 0.17 5460.76 2.82 0.00 0.00 6:15 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.58 0.17 5460.59 2.82 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.53 0.17 5460.42 2.82 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.48 0.17 5460.24 2.82 0.00 0.00 6:30 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.43 0.17 5460.07 2.82 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.38 0.17 5459.90 2.82 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.33 0.17 5459.72 2.82 0.00 0.00 6:45 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.29 0.17 5459.55 2.82 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.24 0.17 5459.38 2.82 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.19 0.17 5459.21 2.82 0.00 0.00 7:00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2489.14 0.17 5459.03 2.82 0.00 0.00 Total volume (cf)5467.51 Total Overflow (cf)0.00
455

5 of 6
24 Hour Storm in 15 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:15 0.2 0.04 0.99 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 947.00 0.20 3.98 0.00 0.00 0.00 0:30 0.3 0.06 0.98 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 948.12 0.20 10.05 0.01 0.00 0.00 0:45 0.3 0.06 0.97 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 949.84 0.20 16.13 0.01 0.00 0.00 1:00 0.4 0.08 0.95 0.07 0.0081 0.0093 8.36 0.00 0.00 0.00 0.00 0.00 8.36 951.56 0.20 24.29 0.01 0.00 0.00 1:15 0.3 0.06 0.94 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 953.86 0.20 30.36 0.02 0.00 0.00 1:30 0.3 0.06 0.93 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 955.58 0.20 36.43 0.02 0.00 0.00 1:45 0.3 0.06 0.92 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 957.29 0.20 42.50 0.02 0.00 0.00 2:00 0.4 0.08 0.91 0.07 0.0081 0.0093 8.36 0.00 0.00 0.00 0.00 0.00 8.36 959.00 0.20 50.66 0.03 0.00 0.00 2:15 0.4 0.08 0.90 0.07 0.0081 0.0093 8.36 0.00 0.00 0.00 0.00 0.00 8.36 961.31 0.20 58.82 0.03 0.00 0.00 2:30 0.4 0.08 0.89 0.07 0.0081 0.0093 8.36 0.00 0.00 0.00 0.00 0.00 8.36 963.61 0.20 66.97 0.03 0.00 0.00 2:45 0.5 0.10 0.88 0.09 0.0101 0.0116 10.45 0.00 0.00 0.00 0.00 0.00 10.45 965.92 0.20 77.22 0.04 0.00 0.00 3:00 0.5 0.10 0.87 0.09 0.0101 0.0116 10.45 0.00 0.00 0.00 0.00 0.00 10.45 968.81 0.20 87.47 0.05 0.00 0.00 3:15 0.5 0.10 0.85 0.09 0.0101 0.0116 10.45 0.00 0.00 0.00 0.00 0.00 10.45 971.71 0.20 97.72 0.05 0.00 0.00 3:30 0.5 0.10 0.84 0.09 0.0101 0.0116 10.45 0.00 0.00 0.00 0.00 0.00 10.45 974.60 0.20 107.96 0.06 0.00 0.00 3:45 0.5 0.10 0.83 0.09 0.0101 0.0116 10.45 0.00 0.00 0.00 0.00 0.00 10.45 977.50 0.20 118.21 0.06 0.00 0.00 4:00 0.6 0.12 0.82 0.11 0.0121 0.0139 12.54 0.00 0.00 0.00 0.00 0.00 12.54 980.39 0.20 130.54 0.07 0.00 0.00 4:15 0.6 0.12 0.81 0.11 0.0121 0.0139 12.54 0.00 0.00 0.00 0.00 0.00 12.54 983.88 0.20 142.87 0.07 0.00 0.00 4:30 0.7 0.14 0.80 0.13 0.0141 0.0163 14.63 0.00 0.00 0.00 0.00 0.00 14.63 987.36 0.21 157.30 0.08 0.00 0.00 4:45 0.7 0.14 0.79 0.13 0.0141 0.0163 14.63 0.00 0.00 0.00 0.00 0.00 14.63 991.43 0.21 171.72 0.09 0.00 0.00 5:00 0.8 0.16 0.78 0.15 0.0162 0.0186 16.72 0.00 0.00 0.00 0.00 0.00 16.72 995.51 0.21 188.23 0.10 0.00 0.00 5:15 0.6 0.12 0.77 0.11 0.0121 0.0139 12.54 0.00 0.00 0.00 0.00 0.00 12.54 1000.17 0.21 200.56 0.10 0.00 0.00 5:30 0.7 0.14 0.76 0.13 0.0141 0.0163 14.63 0.00 0.00 0.00 0.00 0.00 14.63 1003.66 0.21 214.98 0.11 0.00 0.00 5:45 0.8 0.16 0.75 0.15 0.0162 0.0186 16.72 0.00 0.00 0.00 0.00 0.00 16.72 1007.73 0.21 231.49 0.12 0.00 0.00 6:00 0.8 0.16 0.74 0.15 0.0162 0.0186 16.72 0.00 0.00 0.00 0.00 0.00 16.72 1012.39 0.21 248.00 0.13 0.00 0.00 6:15 0.9 0.18 0.73 0.16 0.0182 0.0209 18.81 0.00 0.00 0.00 0.00 0.00 18.81 1017.06 0.21 266.59 0.14 0.00 0.00 6:30 0.9 0.18 0.72 0.16 0.0182 0.0209 18.81 0.00 0.00 0.00 0.00 0.00 18.81 1022.31 0.21 285.19 0.15 0.00 0.00 6:45 1 0.20 0.71 0.18 0.0202 0.0232 20.90 0.00 0.00 0.00 0.00 0.00 20.90 1027.56 0.21 305.87 0.16 0.00 0.00 7:00 1 0.20 0.70 0.18 0.0202 0.0232 20.90 0.00 0.00 0.00 0.00 0.00 20.90 1033.40 0.22 326.55 0.17 0.00 0.00 7:15 1 0.20 0.69 0.18 0.0202 0.0232 20.90 0.00 0.00 0.00 0.00 0.00 20.90 1039.25 0.22 347.24 0.18 0.00 0.00 7:30 1.1 0.22 0.68 0.20 0.0222 0.0255 22.99 0.00 0.00 0.00 0.00 0.00 22.99 1045.09 0.22 370.01 0.19 0.00 0.00 7:45 1.2 0.24 0.67 0.22 0.0242 0.0279 25.08 0.00 0.00 0.00 0.00 0.00 25.08 1051.52 0.22 394.86 0.20 0.00 0.00 8:00 1.3 0.26 0.66 0.24 0.0263 0.0302 27.17 0.00 0.00 0.00 0.00 0.00 27.17 1058.54 0.22 421.81 0.22 0.00 0.00 8:15 1.5 0.30 0.66 0.27 0.0303 0.0348 31.35 0.00 0.00 0.00 0.00 0.00 31.35 1066.15 0.22 452.94 0.23 0.00 0.00 8:30 1.5 0.30 0.65 0.27 0.0303 0.0348 31.35 0.00 0.00 0.00 0.00 0.00 31.35 1074.95 0.22 484.06 0.25 0.00 0.00 8:45 1.6 0.32 0.64 0.29 0.0323 0.0372 33.44 0.00 0.00 0.00 0.00 0.00 33.44 1083.74 0.23 517.27 0.27 0.00 0.00 9:00 1.7 0.34 0.63 0.31 0.0343 0.0395 35.53 0.00 0.00 0.00 0.00 0.00 35.53 1093.12 0.23 552.57 0.29 0.00 0.00 9:15 1.9 0.38 0.62 0.35 0.0384 0.0441 39.71 0.00 0.00 0.00 0.00 0.00 39.71 1103.09 0.23 592.04 0.31 0.00 0.00 9:30 2 0.40 0.61 0.36 0.0404 0.0464 41.80 0.00 0.00 0.00 0.00 0.00 41.80 1114.24 0.23 633.61 0.33 0.00 0.00 9:45 2.1 0.42 0.60 0.38 0.0424 0.0488 43.89 0.00 0.00 0.00 0.00 0.00 43.89 1125.98 0.23 677.26 0.35 0.00 0.00 10:00 2.2 0.44 0.59 0.40 0.0444 0.0511 45.98 0.00 0.00 0.00 0.00 0.00 45.98 1138.31 0.24 723.00 0.37 0.00 0.00 10:15 1.5 0.30 0.58 0.27 0.0303 0.0348 31.35 0.00 0.00 0.00 0.00 0.00 31.35 1151.24 0.24 754.10 0.39 0.00 0.00 10:30 1.5 0.30 0.58 0.27 0.0303 0.0348 31.35 0.00 0.00 0.00 0.00 0.00 31.35 1160.02 0.24 785.21 0.41 0.00 0.00 10:45 2 0.40 0.57 0.36 0.0404 0.0464 41.80 0.00 0.00 0.00 0.00 0.00 41.80 1168.81 0.24 826.76 0.43 0.00 0.00 11:00 2 0.40 0.56 0.36 0.0404 0.0464 41.80 0.00 0.00 0.00 0.00 0.00 41.80 1180.55 0.25 868.31 0.45 0.00 0.00 11:15 1.9 0.38 0.55 0.35 0.0384 0.0441 39.71 0.00 0.00 0.00 0.00 0.00 39.71 1192.28 0.25 907.77 0.47 0.00 0.00 11:30 1.9 0.38 0.54 0.35 0.0384 0.0441 39.71 0.00 0.00 0.00 0.00 0.00 39.71 1203.43 0.25 947.22 0.49 0.00 0.00 11:45 1.7 0.34 0.53 0.31 0.0343 0.0395 35.53 0.00 0.00 0.00 0.00 0.00 35.53 1214.58 0.25 982.50 0.51 0.00 0.00 12:00 1.8 0.36 0.53 0.33 0.0364 0.0418 37.62 0.00 0.00 0.00 0.00 0.00 37.62 1224.54 0.26 1019.86 0.53 0.00 0.00 12:15 2.5 0.51 0.52 0.45 0.0505 0.0580 52.24 0.00 0.00 0.00 0.00 0.00 52.24 1235.09 0.26 1071.85 0.55 0.00 0.00 12:30 2.6 0.53 0.51 0.47 0.0525 0.0604 54.33 0.00 0.00 0.00 0.00 0.00 54.33 1249.78 0.26 1125.92 0.58 0.00 0.00 12:45 2.8 0.57 0.50 N/A 0.0622 0.0715 64.38 0.00 0.00 0.00 0.00 0.00 64.38 1265.05 0.26 1190.04 0.62 0.00 0.00 456

6 of 6
13:00 2.9 0.59 0.50 N/A 0.0900 0.1035 93.14 0.00 0.00 0.00 0.00 0.00 93.14 1283.17 0.27 1282.91 0.66 0.00 0.00 13:15 3.4 0.69 0.49 N/A 0.1985 0.2282 205.39 0.00 0.00 0.00 0.00 0.00 205.39 1309.40 0.27 1488.03 0.77 0.00 0.00 13:30 3.4 0.69 0.48 N/A 0.2059 0.2367 213.06 0.00 0.00 0.00 0.00 0.00 213.06 1367.34 0.28 1700.80 0.88 0.00 0.00 13:45 2.3 0.46 0.47 0.42 0.0465 0.0534 48.07 0.00 0.00 0.00 0.00 0.00 48.07 1427.45 0.30 1748.57 0.90 0.00 0.00 14:00 2.3 0.46 0.47 0.42 0.0465 0.0534 48.07 0.00 0.00 0.00 0.00 0.00 48.07 1440.94 0.30 1796.33 0.93 0.00 0.00 14:15 2.7 0.55 0.46 N/A 0.0862 0.0991 89.16 0.00 0.00 0.00 0.00 0.00 89.16 1454.44 0.30 1885.19 0.97 0.00 0.00 14:30 2.6 0.53 0.45 N/A 0.0730 0.0839 75.52 0.00 0.00 0.00 0.00 0.00 75.52 1479.54 0.31 1960.40 1.01 0.00 0.00 14:45 2.6 0.53 0.45 N/A 0.0799 0.0919 82.67 0.00 0.00 0.00 0.00 0.00 82.67 1500.78 0.31 2042.76 1.06 0.00 0.00 15:00 2.5 0.51 0.44 N/A 0.0665 0.0765 68.83 0.00 0.00 0.00 0.00 0.00 68.83 1524.05 0.32 2111.27 1.09 0.00 0.00 15:15 2.4 0.48 0.43 N/A 0.0530 0.0610 54.87 0.00 0.00 0.00 0.00 0.00 54.87 1543.40 0.32 2165.82 1.12 0.00 0.00 15:30 2.3 0.46 0.43 0.42 0.0465 0.0534 48.07 0.00 0.00 0.00 0.00 0.00 48.07 1558.81 0.32 2213.56 1.14 0.00 0.00 15:45 1.9 0.38 0.42 0.35 0.0384 0.0441 39.71 0.00 0.00 0.00 0.00 0.00 39.71 1572.30 0.33 2252.94 1.17 0.00 0.00 16:00 1.9 0.38 0.41 0.35 0.0384 0.0441 39.71 0.00 0.00 0.00 0.00 0.00 39.71 1583.42 0.33 2292.31 1.19 0.00 0.00 16:15 0.4 0.08 0.41 0.07 0.0081 0.0093 8.36 0.00 0.00 0.00 0.00 0.00 8.36 1594.54 0.33 2300.34 1.19 0.00 0.00 16:30 0.4 0.08 0.40 0.07 0.0081 0.0093 8.36 0.00 0.00 0.00 0.00 0.00 8.36 1596.81 0.33 2308.37 1.19 0.00 0.00 16:45 0.3 0.06 0.39 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1599.08 0.33 2314.30 1.20 0.00 0.00 17:00 0.3 0.06 0.39 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1600.75 0.33 2320.24 1.20 0.00 0.00 17:15 0.5 0.10 0.38 0.09 0.0101 0.0116 10.45 0.00 0.00 0.00 0.00 0.00 10.45 1602.43 0.33 2330.35 1.21 0.00 0.00 17:30 0.5 0.10 0.38 0.09 0.0101 0.0116 10.45 0.00 0.00 0.00 0.00 0.00 10.45 1605.29 0.33 2340.47 1.21 0.00 0.00 17:45 0.5 0.10 0.37 0.09 0.0101 0.0116 10.45 0.00 0.00 0.00 0.00 0.00 10.45 1608.15 0.34 2350.58 1.22 0.00 0.00 18:00 0.4 0.08 0.37 0.07 0.0081 0.0093 8.36 0.00 0.00 0.00 0.00 0.00 8.36 1611.00 0.34 2358.61 1.22 0.00 0.00 18:15 0.4 0.08 0.36 0.07 0.0081 0.0093 8.36 0.00 0.00 0.00 0.00 0.00 8.36 1613.27 0.34 2366.63 1.22 0.00 0.00 18:30 0.4 0.08 0.35 0.07 0.0081 0.0093 8.36 0.00 0.00 0.00 0.00 0.00 8.36 1615.54 0.34 2374.65 1.23 0.00 0.00 18:45 0.3 0.06 0.35 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1617.80 0.34 2380.58 1.23 0.00 0.00 19:00 0.2 0.04 0.34 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1619.48 0.34 2384.43 1.23 0.00 0.00 19:15 0.3 0.06 0.34 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1620.56 0.34 2390.36 1.24 0.00 0.00 19:30 0.4 0.08 0.34 0.07 0.0081 0.0093 8.36 0.00 0.00 0.00 0.00 0.00 8.36 1622.24 0.34 2398.38 1.24 0.00 0.00 19:45 0.3 0.06 0.33 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1624.50 0.34 2404.31 1.24 0.00 0.00 20:00 0.2 0.04 0.33 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1626.18 0.34 2408.15 1.25 0.00 0.00 20:15 0.3 0.06 0.32 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1627.26 0.34 2414.08 1.25 0.00 0.00 20:30 0.3 0.06 0.32 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1628.94 0.34 2420.01 1.25 0.00 0.00 20:45 0.3 0.06 0.31 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1630.61 0.34 2425.94 1.25 0.00 0.00 21:00 0.2 0.04 0.31 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1632.29 0.34 2429.78 1.26 0.00 0.00 21:15 0.3 0.06 0.31 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1633.37 0.34 2435.71 1.26 0.00 0.00 21:30 0.2 0.04 0.30 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1635.05 0.34 2439.55 1.26 0.00 0.00 21:45 0.3 0.06 0.30 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1636.13 0.34 2445.48 1.26 0.00 0.00 22:00 0.2 0.04 0.30 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1637.81 0.34 2449.32 1.27 0.00 0.00 22:15 0.3 0.06 0.29 0.05 0.0061 0.0070 6.27 0.00 0.00 0.00 0.00 0.00 6.27 1638.89 0.34 2455.24 1.27 0.00 0.00 22:30 0.2 0.04 0.29 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1640.57 0.34 2459.08 1.27 0.00 0.00 22:45 0.2 0.04 0.29 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1641.65 0.34 2462.92 1.27 0.00 0.00 23:00 0.2 0.04 0.29 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1642.74 0.34 2466.76 1.28 0.00 0.00 23:15 0.2 0.04 0.28 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1643.82 0.34 2470.59 1.28 0.00 0.00 23:30 0.2 0.04 0.28 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1644.90 0.34 2474.43 1.28 0.00 0.00 23:45 0.2 0.04 0.28 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1645.99 0.34 2478.27 1.28 0.00 0.00 24:00 0.2 0.04 0.28 0.04 0.0040 0.0046 4.18 0.00 0.00 0.00 0.00 0.00 4.18 1647.07 0.34 2482.10 1.28 0.00 0.00 0 0.00 0.28 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1648.15 0.34 2481.76 1.28 0.00 0.00 Total volume (cf)2508.09 Total Overflow (cf)0.00
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HYDROLOGY CALCULATIONS - program updated 4-14-22 LC
Using the RCFC&WCD Short Cut Unit Hydrograph Method
Area Designations Area 1 VERSION 2 Area=1.03ac+0.09ac typ street frontage=1.12ac 5/7/2024 LOTs 13-15
Drainage Area (ac.)1.1200 JOB NUMBER 22106
Unit time (minutes)5 5 5 15
100 Year Storm Duration (hrs)1 3 6 24
Total Precipitation (Plates D-4.4,E-5.2, 5.4, 5.6)(in.)2.41 3.10 3.79 5.05 from NOAA interactive website Soils Group A
AMC index II Runoff Number (plate E-6.1)32
Plate E-6.2 Pervious Area Loss Rate (Fp)(in/hr)0.74 (AMC II) Percentage of Impervious Cover (Ai)(%) (plate E-6.3)26.6 20% per the RCFC Hydrology Manual 1AC LOT-PLATE D 5.6 AND 0.09AC TYPICAL STREET FRONTAGE Weighted Average Loss Rate (F=Fp(1-.9Ai))(in./hr.)0.56 (used for 1, 3, and 6 hour storm, the 24 hour storm uses variable maximum loss rate per plate E-1.1 (3 of 6)) Low Loss Rate Percent (%) 90
Retention Basin Percolation Rate (in/hr)0.01 (also used for drywell percolation rate) Percolation is taken incrementally.

Drywell design factors Upper sec. (ft.)=0.001 Lower sec. (ft.)=0.001 Ring diam. (ft.) =0.001 Drywell lower max. (cf)=0.00 Upper max.(cf)=0.00 Gravel bed width around drywell=0.001 Drywell total(cf)=0.00 Ret. Basin design (area, depth) Top =3234 s.f.Bot. =1078 s.f.Max. Depth (d)=4 Max. storage=8238.87 (d/3)*(bottom+top+(bottom*top)^0.50) Formulas vol=(h/3)*(bottom+top+(bottom*top)^0.50) area=bottom+(h/d)*(top-bottom)h=(vol*3)/(bottom+top+(bottom*top)^0.5)(values must be non-zero or error occurs) Outside input from:N/A 3.25
1 Hour Storm in 5 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:05 3.7 1.0700 0.5628 N/A 0.5072 0.5728 171.84 0.00 0.00 0.00 0.00 0.00 171.84 1078.00 0.07 171.76 0.08 0.00 0.00 0:10 4.8 1.3882 0.5628 N/A 0.8253 0.9321 279.62 0.00 0.00 0.00 0.00 0.00 279.62 1122.95 0.08 451.30 0.22 0.00 0.00 0:15 5.1 1.4749 0.5628 N/A 0.9121 1.0300 309.01 0.00 0.00 0.00 0.00 0.00 309.01 1196.10 0.08 760.23 0.37 0.00 0.00 0:20 4.9 1.4171 0.5628 N/A 0.8542 0.9647 289.42 0.00 0.00 0.00 0.00 0.00 289.42 1276.94 0.09 1049.56 0.51 0.00 0.00 0:25 6.6 1.9087 0.5628 N/A 1.3459 1.5199 455.98 0.00 0.00 0.00 0.00 0.00 455.98 1352.65 0.09 1505.45 0.73 0.00 0.00 0:30 7.3 2.1112 0.5628 N/A 1.5483 1.7486 524.57 0.00 0.00 0.00 0.00 0.00 524.57 1471.95 0.10 2029.91 0.99 0.00 0.00 0:35 8.4 2.4293 0.5628 N/A 1.8664 2.1078 632.35 0.00 0.00 0.00 0.00 0.00 632.35 1609.20 0.11 2662.15 1.29 0.00 0.00 0:40 9 2.6028 0.5628 N/A 2.0400 2.3038 691.14 0.00 0.00 0.00 0.00 0.00 691.14 1774.65 0.12 3353.16 1.63 0.00 0.00 0:45 12.3 3.5572 0.5628 N/A 2.9943 3.3816 1014.47 0.00 0.00 0.00 0.00 0.00 1014.47 1955.48 0.14 4367.50 2.12 0.00 0.00 0:50 17.6 5.0899 0.5628 N/A 4.5271 5.1126 1533.77 0.00 0.00 0.00 0.00 0.00 1533.77 2220.92 0.15 5901.12 2.87 0.00 0.00 0:55 16.1 4.6561 0.5628 N/A 4.0933 4.6227 1386.80 0.00 0.00 0.00 0.00 0.00 1386.80 2622.24 0.18 7287.74 3.54 0.00 0.00 1:00 4.2 1.2146 0.5628 N/A 0.6518 0.7361 220.83 0.00 0.00 0.00 0.00 0.00 220.83 2985.10 0.21 7508.36 3.65 0.00 0.00 MAX DEPTH 0 0.0000 0.5628 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3042.84 0.21 7508.15 3.65 0.00 0.00 0 0.0000 0.5628 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3042.78 0.21 7507.94 3.65 0.00 0.00 1:15 0 0.0000 0.5628 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3042.73 0.21 7507.73 3.65 0.00 0.00 Total volume (cf)7509.80 Total Overflow (cf)0.00
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3 Hour Storm in 5 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:05 1.3 0.48 0.56 0.44 0.0484 0.0546 16.38 0.00 0.00 0.00 0.00 0.00 16.38 1078.00 0.07 16.31 0.01 0.00 0.00 0:10 1.3 0.48 0.56 0.44 0.0484 0.0546 16.38 0.00 0.00 0.00 0.00 0.00 16.38 1082.27 0.08 32.62 0.02 0.00 0.00 0:15 1.1 0.41 0.56 0.37 0.0409 0.0462 13.86 0.00 0.00 0.00 0.00 0.00 13.86 1086.54 0.08 46.41 0.02 0.00 0.00 0:20 1.5 0.56 0.56 0.50 0.0558 0.0630 18.91 0.00 0.00 0.00 0.00 0.00 18.91 1090.14 0.08 65.24 0.03 0.00 0.00 0:25 1.5 0.56 0.56 0.50 0.0558 0.0630 18.91 0.00 0.00 0.00 0.00 0.00 18.91 1095.07 0.08 84.07 0.04 0.00 0.00 0:30 1.8 0.67 0.56 N/A 0.1068 0.1206 36.17 0.00 0.00 0.00 0.00 0.00 36.17 1100.00 0.08 120.16 0.06 0.00 0.00 0:35 1.5 0.56 0.56 0.50 0.0558 0.0630 18.91 0.00 0.00 0.00 0.00 0.00 18.91 1109.44 0.08 138.99 0.07 0.00 0.00 0:40 1.8 0.67 0.56 N/A 0.1068 0.1206 36.17 0.00 0.00 0.00 0.00 0.00 36.17 1114.37 0.08 175.08 0.09 0.00 0.00 0:45 1.8 0.67 0.56 N/A 0.1068 0.1206 36.17 0.00 0.00 0.00 0.00 0.00 36.17 1123.82 0.08 211.17 0.10 0.00 0.00 0:50 1.5 0.56 0.56 0.50 0.0558 0.0630 18.91 0.00 0.00 0.00 0.00 0.00 18.91 1133.26 0.08 229.99 0.11 0.00 0.00 0:55 1.6 0.60 0.56 0.54 0.0595 0.0672 20.17 0.00 0.00 0.00 0.00 0.00 20.17 1138.19 0.08 250.08 0.12 0.00 0.00 1:00 1.8 0.67 0.56 N/A 0.1068 0.1206 36.17 0.00 0.00 0.00 0.00 0.00 36.17 1143.44 0.08 286.17 0.14 0.00 0.00 1:05 2.2 0.82 0.56 N/A 0.2556 0.2886 86.58 0.00 0.00 0.00 0.00 0.00 86.58 1152.89 0.08 372.67 0.18 0.00 0.00 1:10 2.2 0.82 0.56 N/A 0.2556 0.2886 86.58 0.00 0.00 0.00 0.00 0.00 86.58 1175.52 0.08 459.17 0.22 0.00 0.00 1:15 2.2 0.82 0.56 N/A 0.2556 0.2886 86.58 0.00 0.00 0.00 0.00 0.00 86.58 1198.16 0.08 545.67 0.26 0.00 0.00 1:20 2 0.74 0.56 N/A 0.1812 0.2046 61.38 0.00 0.00 0.00 0.00 0.00 61.38 1220.80 0.08 606.96 0.29 0.00 0.00 1:25 2.6 0.97 0.56 N/A 0.4044 0.4567 137.00 0.00 0.00 0.00 0.00 0.00 137.00 1236.83 0.09 743.87 0.36 0.00 0.00 1:30 2.7 1.00 0.56 N/A 0.4416 0.4987 149.60 0.00 0.00 0.00 0.00 0.00 149.60 1272.66 0.09 893.38 0.43 0.00 0.00 1:35 2.4 0.89 0.56 N/A 0.3300 0.3726 111.79 0.00 0.00 0.00 0.00 0.00 111.79 1311.79 0.09 1005.08 0.49 0.00 0.00 1:40 2.7 1.00 0.56 N/A 0.4416 0.4987 149.60 0.00 0.00 0.00 0.00 0.00 149.60 1341.02 0.09 1154.59 0.56 0.00 0.00 1:45 3.3 1.23 0.56 N/A 0.6648 0.7507 225.22 0.00 0.00 0.00 0.00 0.00 225.22 1380.14 0.10 1379.71 0.67 0.00 0.00 1:50 3.1 1.15 0.56 N/A 0.5904 0.6667 200.01 0.00 0.00 0.00 0.00 0.00 200.01 1439.05 0.10 1579.62 0.77 0.00 0.00 1:55 2.9 1.08 0.56 N/A 0.5160 0.5827 174.81 0.00 0.00 0.00 0.00 0.00 174.81 1491.37 0.10 1754.33 0.85 0.00 0.00 2:00 3 1.12 0.56 N/A 0.5532 0.6247 187.41 0.00 0.00 0.00 0.00 0.00 187.41 1537.08 0.11 1941.63 0.94 0.00 0.00 2:05 3.1 1.15 0.56 N/A 0.5904 0.6667 200.01 0.00 0.00 0.00 0.00 0.00 200.01 1586.10 0.11 2141.53 1.04 0.00 0.00 2:10 4.2 1.56 0.56 N/A 0.9996 1.1288 338.65 0.00 0.00 0.00 0.00 0.00 338.65 1638.41 0.11 2480.07 1.20 0.00 0.00 2:15 5 1.86 0.56 N/A 1.2972 1.4649 439.48 0.00 0.00 0.00 0.00 0.00 439.48 1727.00 0.12 2919.42 1.42 0.00 0.00 2:20 3.5 1.30 0.56 N/A 0.7392 0.8348 250.43 0.00 0.00 0.00 0.00 0.00 250.43 1841.97 0.13 3169.72 1.54 0.00 0.00 2:25 6.8 2.53 0.56 N/A 1.9668 2.2211 666.34 0.00 0.00 0.00 0.00 0.00 666.34 1907.47 0.13 3835.93 1.86 0.00 0.00 2:30 7.3 2.72 0.56 N/A 2.1528 2.4312 729.35 0.00 0.00 0.00 0.00 0.00 729.35 2081.81 0.14 4565.14 2.22 0.00 0.00 2:35 8.2 3.05 0.56 N/A 2.4876 2.8093 842.78 0.00 0.00 0.00 0.00 0.00 842.78 2272.63 0.16 5407.76 2.63 0.00 0.00 2:40 5.9 2.19 0.56 N/A 1.6320 1.8430 552.91 0.00 0.00 0.00 0.00 0.00 552.91 2493.14 0.17 5960.50 2.89 0.00 0.00 2:45 2 0.74 0.56 N/A 0.1812 0.2046 61.38 0.00 0.00 0.00 0.00 0.00 61.38 2637.78 0.18 6021.69 2.92 0.00 0.00 2:50 1.8 0.67 0.56 N/A 0.1068 0.1206 36.17 0.00 0.00 0.00 0.00 0.00 36.17 2653.79 0.18 6057.67 2.94 0.00 0.00 2:55 1.8 0.67 0.56 N/A 0.1068 0.1206 36.17 0.00 0.00 0.00 0.00 0.00 36.17 2663.21 0.18 6093.66 2.96 0.00 0.00 3:00 0.6 0.22 0.56 0.20 0.0223 0.0252 7.56 0.00 0.00 0.00 0.00 0.00 7.56 2672.63 0.19 6101.03 2.96 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2674.56 0.19 6100.85 2.96 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2674.51 0.19 6100.66 2.96 0.00 0.00 3:15 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2674.46 0.19 6100.48 2.96 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2674.41 0.19 6100.29 2.96 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2674.36 0.19 6100.10 2.96 0.00 0.00 3:30 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2674.31 0.19 6099.92 2.96 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2674.27 0.19 6099.73 2.96 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2674.22 0.19 6099.55 2.96 0.00 0.00 Total volume (cf)6104.87 Total Overflow (cf)0.00
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6 Hour Storm in 5 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:05 0.5 0.23 0.56 0.20 0.0227 0.0257 7.70 0.00 0.00 0.00 0.00 0.00 7.70 1078.00 0.07 7.63 0.00 0.00 0.00 0:10 0.6 0.27 0.56 0.25 0.0273 0.0308 9.25 0.00 0.00 0.00 0.00 0.00 9.25 1080.00 0.07 16.80 0.01 0.00 0.00 0:15 0.6 0.27 0.56 0.25 0.0273 0.0308 9.25 0.00 0.00 0.00 0.00 0.00 9.25 1082.40 0.08 25.97 0.01 0.00 0.00 0:20 0.6 0.27 0.56 0.25 0.0273 0.0308 9.25 0.00 0.00 0.00 0.00 0.00 9.25 1084.80 0.08 35.14 0.02 0.00 0.00 0:25 0.6 0.27 0.56 0.25 0.0273 0.0308 9.25 0.00 0.00 0.00 0.00 0.00 9.25 1087.20 0.08 44.31 0.02 0.00 0.00 0:30 0.7 0.32 0.56 0.29 0.0318 0.0360 10.79 0.00 0.00 0.00 0.00 0.00 10.79 1089.60 0.08 55.02 0.03 0.00 0.00 0:35 0.7 0.32 0.56 0.29 0.0318 0.0360 10.79 0.00 0.00 0.00 0.00 0.00 10.79 1092.40 0.08 65.73 0.03 0.00 0.00 0:40 0.7 0.32 0.56 0.29 0.0318 0.0360 10.79 0.00 0.00 0.00 0.00 0.00 10.79 1095.20 0.08 76.44 0.04 0.00 0.00 0:45 0.7 0.32 0.56 0.29 0.0318 0.0360 10.79 0.00 0.00 0.00 0.00 0.00 10.79 1098.00 0.08 87.15 0.04 0.00 0.00 0:50 0.7 0.32 0.56 0.29 0.0318 0.0360 10.79 0.00 0.00 0.00 0.00 0.00 10.79 1100.81 0.08 97.86 0.05 0.00 0.00 0:55 0.7 0.32 0.56 0.29 0.0318 0.0360 10.79 0.00 0.00 0.00 0.00 0.00 10.79 1103.61 0.08 108.57 0.05 0.00 0.00 1:00 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1106.41 0.08 120.82 0.06 0.00 0.00 1:05 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1109.62 0.08 133.07 0.06 0.00 0.00 1:10 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1112.82 0.08 145.32 0.07 0.00 0.00 1:15 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1116.03 0.08 157.57 0.08 0.00 0.00 1:20 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1119.23 0.08 169.82 0.08 0.00 0.00 1:25 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1122.44 0.08 182.07 0.09 0.00 0.00 1:30 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1125.64 0.08 194.31 0.09 0.00 0.00 1:35 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1128.85 0.08 206.56 0.10 0.00 0.00 1:40 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1132.05 0.08 218.81 0.11 0.00 0.00 1:45 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1135.26 0.08 231.06 0.11 0.00 0.00 1:50 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1138.47 0.08 243.31 0.12 0.00 0.00 1:55 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1141.67 0.08 255.55 0.12 0.00 0.00 2:00 0.9 0.41 0.56 0.37 0.0409 0.0462 13.87 0.00 0.00 0.00 0.00 0.00 13.87 1144.88 0.08 269.34 0.13 0.00 0.00 2:05 0.8 0.36 0.56 0.33 0.0364 0.0411 12.33 0.00 0.00 0.00 0.00 0.00 12.33 1148.48 0.08 281.59 0.14 0.00 0.00 2:10 0.9 0.41 0.56 0.37 0.0409 0.0462 13.87 0.00 0.00 0.00 0.00 0.00 13.87 1151.69 0.08 295.38 0.14 0.00 0.00 2:15 0.9 0.41 0.56 0.37 0.0409 0.0462 13.87 0.00 0.00 0.00 0.00 0.00 13.87 1155.30 0.08 309.17 0.15 0.00 0.00 2:20 0.9 0.41 0.56 0.37 0.0409 0.0462 13.87 0.00 0.00 0.00 0.00 0.00 13.87 1158.90 0.08 322.95 0.16 0.00 0.00 2:25 0.9 0.41 0.56 0.37 0.0409 0.0462 13.87 0.00 0.00 0.00 0.00 0.00 13.87 1162.51 0.08 336.74 0.16 0.00 0.00 2:30 0.9 0.41 0.56 0.37 0.0409 0.0462 13.87 0.00 0.00 0.00 0.00 0.00 13.87 1166.12 0.08 350.53 0.17 0.00 0.00 2:35 0.9 0.41 0.56 0.37 0.0409 0.0462 13.87 0.00 0.00 0.00 0.00 0.00 13.87 1169.73 0.08 364.31 0.18 0.00 0.00 2:40 0.9 0.41 0.56 0.37 0.0409 0.0462 13.87 0.00 0.00 0.00 0.00 0.00 13.87 1173.34 0.08 378.10 0.18 0.00 0.00 2:45 1 0.45 0.56 0.41 0.0455 0.0514 15.41 0.00 0.00 0.00 0.00 0.00 15.41 1176.94 0.08 393.43 0.19 0.00 0.00 2:50 1 0.45 0.56 0.41 0.0455 0.0514 15.41 0.00 0.00 0.00 0.00 0.00 15.41 1180.95 0.08 408.75 0.20 0.00 0.00 2:55 1 0.45 0.56 0.41 0.0455 0.0514 15.41 0.00 0.00 0.00 0.00 0.00 15.41 1184.97 0.08 424.08 0.21 0.00 0.00 3:00 1 0.45 0.56 0.41 0.0455 0.0514 15.41 0.00 0.00 0.00 0.00 0.00 15.41 1188.98 0.08 439.41 0.21 0.00 0.00 3:05 1 0.45 0.56 0.41 0.0455 0.0514 15.41 0.00 0.00 0.00 0.00 0.00 15.41 1192.99 0.08 454.73 0.22 0.00 0.00 3:10 1.1 0.50 0.56 0.45 0.0500 0.0565 16.95 0.00 0.00 0.00 0.00 0.00 16.95 1197.00 0.08 471.60 0.23 0.00 0.00 3:15 1.1 0.50 0.56 0.45 0.0500 0.0565 16.95 0.00 0.00 0.00 0.00 0.00 16.95 1201.41 0.08 488.46 0.24 0.00 0.00 3:20 1.1 0.50 0.56 0.45 0.0500 0.0565 16.95 0.00 0.00 0.00 0.00 0.00 16.95 1205.82 0.08 505.33 0.25 0.00 0.00 3:25 1.2 0.55 0.56 0.49 0.0546 0.0616 18.49 0.00 0.00 0.00 0.00 0.00 18.49 1210.24 0.08 523.74 0.25 0.00 0.00 3:30 1.3 0.59 0.56 0.53 0.0591 0.0668 20.03 0.00 0.00 0.00 0.00 0.00 20.03 1215.05 0.08 543.68 0.26 0.00 0.00 3:35 1.4 0.64 0.56 N/A 0.0739 0.0834 25.03 0.00 0.00 0.00 0.00 0.00 25.03 1220.27 0.08 568.63 0.28 0.00 0.00 3:40 1.4 0.64 0.56 N/A 0.0739 0.0834 25.03 0.00 0.00 0.00 0.00 0.00 25.03 1226.80 0.09 593.57 0.29 0.00 0.00 3:45 1.5 0.68 0.56 N/A 0.1194 0.1348 40.44 0.00 0.00 0.00 0.00 0.00 40.44 1233.33 0.09 633.92 0.31 0.00 0.00 3:50 1.5 0.68 0.56 N/A 0.1194 0.1348 40.44 0.00 0.00 0.00 0.00 0.00 40.44 1243.89 0.09 674.27 0.33 0.00 0.00 3:55 1.6 0.73 0.56 N/A 0.1648 0.1862 55.85 0.00 0.00 0.00 0.00 0.00 55.85 1254.45 0.09 730.03 0.35 0.00 0.00 4:00 1.6 0.73 0.56 N/A 0.1648 0.1862 55.85 0.00 0.00 0.00 0.00 0.00 55.85 1269.04 0.09 785.79 0.38 0.00 0.00 4:05 1.7 0.77 0.56 N/A 0.2103 0.2375 71.26 0.00 0.00 0.00 0.00 0.00 71.26 1283.63 0.09 856.96 0.42 0.00 0.00 4:10 1.8 0.82 0.56 N/A 0.2558 0.2889 86.66 0.00 0.00 0.00 0.00 0.00 86.66 1302.25 0.09 943.53 0.46 0.00 0.00 4:15 1.9 0.86 0.56 N/A 0.3013 0.3402 102.07 0.00 0.00 0.00 0.00 0.00 102.07 1324.91 0.09 1045.51 0.51 0.00 0.00 460

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4:20 2 0.91 0.56 N/A 0.3468 0.3916 117.48 0.00 0.00 0.00 0.00 0.00 117.48 1351.60 0.09 1162.90 0.56 0.00 0.00 4:25 2.1 0.96 0.56 N/A 0.3922 0.4430 132.89 0.00 0.00 0.00 0.00 0.00 132.89 1382.31 0.10 1295.69 0.63 0.00 0.00 4:30 2.1 0.96 0.56 N/A 0.3922 0.4430 132.89 0.00 0.00 0.00 0.00 0.00 132.89 1417.07 0.10 1428.48 0.69 0.00 0.00 4:35 2.2 1.00 0.56 N/A 0.4377 0.4943 148.30 0.00 0.00 0.00 0.00 0.00 148.30 1451.81 0.10 1576.68 0.77 0.00 0.00 4:40 2.3 1.05 0.56 N/A 0.4832 0.5457 163.71 0.00 0.00 0.00 0.00 0.00 163.71 1490.60 0.10 1740.28 0.84 0.00 0.00 4:45 2.4 1.09 0.56 N/A 0.5287 0.5971 179.12 0.00 0.00 0.00 0.00 0.00 179.12 1533.41 0.11 1919.29 0.93 0.00 0.00 4:50 2.4 1.09 0.56 N/A 0.5287 0.5971 179.12 0.00 0.00 0.00 0.00 0.00 179.12 1580.25 0.11 2098.30 1.02 0.00 0.00 4:55 2.5 1.14 0.56 N/A 0.5742 0.6484 194.52 0.00 0.00 0.00 0.00 0.00 194.52 1627.10 0.11 2292.71 1.11 0.00 0.00 5:00 2.6 1.18 0.56 N/A 0.6196 0.6998 209.93 0.00 0.00 0.00 0.00 0.00 209.93 1677.97 0.12 2502.53 1.21 0.00 0.00 5:05 3.1 1.41 0.56 N/A 0.8470 0.9566 286.98 0.00 0.00 0.00 0.00 0.00 286.98 1732.88 0.12 2789.38 1.35 0.00 0.00 5:10 3.6 1.64 0.56 N/A 1.0744 1.2134 364.02 0.00 0.00 0.00 0.00 0.00 364.02 1807.94 0.13 3153.27 1.53 0.00 0.00 5:15 3.9 1.77 0.56 N/A 1.2109 1.3675 410.24 0.00 0.00 0.00 0.00 0.00 410.24 1903.17 0.13 3563.39 1.73 0.00 0.00 5:20 4.2 1.91 0.56 N/A 1.3473 1.5216 456.47 0.00 0.00 0.00 0.00 0.00 456.47 2010.49 0.14 4019.72 1.95 0.00 0.00 5:25 4.7 2.14 0.56 N/A 1.5747 1.7784 533.51 0.00 0.00 0.00 0.00 0.00 533.51 2129.91 0.15 4553.08 2.21 0.00 0.00 5:30 5.6 2.55 0.56 N/A 1.9840 2.2406 672.19 0.00 0.00 0.00 0.00 0.00 672.19 2269.48 0.16 5225.12 2.54 0.00 0.00 5:35 1.9 0.86 0.56 N/A 0.3013 0.3402 102.07 0.00 0.00 0.00 0.00 0.00 102.07 2445.34 0.17 5327.02 2.59 0.00 0.00 5:40 0.9 0.41 0.56 0.37 0.0409 0.0462 13.87 0.00 0.00 0.00 0.00 0.00 13.87 2472.01 0.17 5340.72 2.59 0.00 0.00 5:45 0.6 0.27 0.56 0.25 0.0273 0.0308 9.25 0.00 0.00 0.00 0.00 0.00 9.25 2475.59 0.17 5349.79 2.60 0.00 0.00 5:50 0.5 0.23 0.56 0.20 0.0227 0.0257 7.70 0.00 0.00 0.00 0.00 0.00 7.70 2477.97 0.17 5357.32 2.60 0.00 0.00 5:55 0.3 0.14 0.56 0.12 0.0136 0.0154 4.62 0.00 0.00 0.00 0.00 0.00 4.62 2479.94 0.17 5361.77 2.60 0.00 0.00 6:00 0.2 0.09 0.56 0.08 0.0091 0.0103 3.08 0.00 0.00 0.00 0.00 0.00 3.08 2481.10 0.17 5364.68 2.60 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.86 0.17 5364.51 2.60 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.82 0.17 5364.34 2.60 0.00 0.00 6:15 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.77 0.17 5364.16 2.60 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.73 0.17 5363.99 2.60 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.68 0.17 5363.82 2.60 0.00 0.00 6:30 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.64 0.17 5363.65 2.60 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.59 0.17 5363.48 2.60 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.55 0.17 5363.30 2.60 0.00 0.00 6:45 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.50 0.17 5363.13 2.60 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.46 0.17 5362.96 2.60 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.41 0.17 5362.79 2.60 0.00 0.00 7:00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2481.37 0.17 5362.61 2.60 0.00 0.00 Total volume (cf)5371.59 Total Overflow (cf)0.00
461

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24 Hour Storm in 15 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:15 0.2 0.04 0.99 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1078.00 0.22 3.88 0.00 0.00 0.00 0:30 0.3 0.06 0.98 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1079.02 0.22 9.82 0.00 0.00 0.00 0:45 0.3 0.06 0.97 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1080.57 0.23 15.75 0.01 0.00 0.00 1:00 0.4 0.08 0.95 0.07 0.0081 0.0091 8.21 0.00 0.00 0.00 0.00 0.00 8.21 1082.12 0.23 23.74 0.01 0.00 0.00 1:15 0.3 0.06 0.94 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1084.21 0.23 29.67 0.01 0.00 0.00 1:30 0.3 0.06 0.93 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1085.76 0.23 35.60 0.02 0.00 0.00 1:45 0.3 0.06 0.92 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1087.32 0.23 41.54 0.02 0.00 0.00 2:00 0.4 0.08 0.91 0.07 0.0081 0.0091 8.21 0.00 0.00 0.00 0.00 0.00 8.21 1088.87 0.23 49.52 0.02 0.00 0.00 2:15 0.4 0.08 0.90 0.07 0.0081 0.0091 8.21 0.00 0.00 0.00 0.00 0.00 8.21 1090.96 0.23 57.51 0.03 0.00 0.00 2:30 0.4 0.08 0.89 0.07 0.0081 0.0091 8.21 0.00 0.00 0.00 0.00 0.00 8.21 1093.05 0.23 65.49 0.03 0.00 0.00 2:45 0.5 0.10 0.88 0.09 0.0101 0.0114 10.27 0.00 0.00 0.00 0.00 0.00 10.27 1095.14 0.23 75.53 0.04 0.00 0.00 3:00 0.5 0.10 0.87 0.09 0.0101 0.0114 10.27 0.00 0.00 0.00 0.00 0.00 10.27 1097.77 0.23 85.57 0.04 0.00 0.00 3:15 0.5 0.10 0.85 0.09 0.0101 0.0114 10.27 0.00 0.00 0.00 0.00 0.00 10.27 1100.39 0.23 95.60 0.05 0.00 0.00 3:30 0.5 0.10 0.84 0.09 0.0101 0.0114 10.27 0.00 0.00 0.00 0.00 0.00 10.27 1103.02 0.23 105.64 0.05 0.00 0.00 3:45 0.5 0.10 0.83 0.09 0.0101 0.0114 10.27 0.00 0.00 0.00 0.00 0.00 10.27 1105.64 0.23 115.67 0.06 0.00 0.00 4:00 0.6 0.12 0.82 0.11 0.0121 0.0137 12.32 0.00 0.00 0.00 0.00 0.00 12.32 1108.27 0.23 127.76 0.06 0.00 0.00 4:15 0.6 0.12 0.81 0.11 0.0121 0.0137 12.32 0.00 0.00 0.00 0.00 0.00 12.32 1111.43 0.23 139.85 0.07 0.00 0.00 4:30 0.7 0.14 0.80 0.13 0.0141 0.0160 14.37 0.00 0.00 0.00 0.00 0.00 14.37 1114.60 0.23 153.99 0.07 0.00 0.00 4:45 0.7 0.14 0.79 0.13 0.0141 0.0160 14.37 0.00 0.00 0.00 0.00 0.00 14.37 1118.30 0.23 168.13 0.08 0.00 0.00 5:00 0.8 0.16 0.78 0.15 0.0162 0.0183 16.43 0.00 0.00 0.00 0.00 0.00 16.43 1122.00 0.23 184.32 0.09 0.00 0.00 5:15 0.6 0.12 0.77 0.11 0.0121 0.0137 12.32 0.00 0.00 0.00 0.00 0.00 12.32 1126.23 0.23 196.40 0.10 0.00 0.00 5:30 0.7 0.14 0.76 0.13 0.0141 0.0160 14.37 0.00 0.00 0.00 0.00 0.00 14.37 1129.40 0.24 210.54 0.10 0.00 0.00 5:45 0.8 0.16 0.75 0.15 0.0162 0.0183 16.43 0.00 0.00 0.00 0.00 0.00 16.43 1133.10 0.24 226.73 0.11 0.00 0.00 6:00 0.8 0.16 0.74 0.15 0.0162 0.0183 16.43 0.00 0.00 0.00 0.00 0.00 16.43 1137.33 0.24 242.92 0.12 0.00 0.00 6:15 0.9 0.18 0.73 0.16 0.0182 0.0205 18.48 0.00 0.00 0.00 0.00 0.00 18.48 1141.57 0.24 261.16 0.13 0.00 0.00 6:30 0.9 0.18 0.72 0.16 0.0182 0.0205 18.48 0.00 0.00 0.00 0.00 0.00 18.48 1146.34 0.24 279.40 0.14 0.00 0.00 6:45 1 0.20 0.71 0.18 0.0202 0.0228 20.53 0.00 0.00 0.00 0.00 0.00 20.53 1151.11 0.24 299.69 0.15 0.00 0.00 7:00 1 0.20 0.70 0.18 0.0202 0.0228 20.53 0.00 0.00 0.00 0.00 0.00 20.53 1156.42 0.24 319.98 0.16 0.00 0.00 7:15 1 0.20 0.69 0.18 0.0202 0.0228 20.53 0.00 0.00 0.00 0.00 0.00 20.53 1161.73 0.24 340.27 0.17 0.00 0.00 7:30 1.1 0.22 0.68 0.20 0.0222 0.0251 22.58 0.00 0.00 0.00 0.00 0.00 22.58 1167.04 0.24 362.61 0.18 0.00 0.00 7:45 1.2 0.24 0.67 0.22 0.0242 0.0274 24.64 0.00 0.00 0.00 0.00 0.00 24.64 1172.89 0.24 387.00 0.19 0.00 0.00 8:00 1.3 0.26 0.66 0.24 0.0263 0.0297 26.69 0.00 0.00 0.00 0.00 0.00 26.69 1179.27 0.25 413.45 0.20 0.00 0.00 8:15 1.5 0.30 0.66 0.27 0.0303 0.0342 30.80 0.00 0.00 0.00 0.00 0.00 30.80 1186.19 0.25 444.00 0.22 0.00 0.00 8:30 1.5 0.30 0.65 0.27 0.0303 0.0342 30.80 0.00 0.00 0.00 0.00 0.00 30.80 1194.19 0.25 474.55 0.23 0.00 0.00 8:45 1.6 0.32 0.64 0.29 0.0323 0.0365 32.85 0.00 0.00 0.00 0.00 0.00 32.85 1202.18 0.25 507.15 0.25 0.00 0.00 9:00 1.7 0.34 0.63 0.31 0.0343 0.0388 34.90 0.00 0.00 0.00 0.00 0.00 34.90 1210.71 0.25 541.80 0.26 0.00 0.00 9:15 1.9 0.38 0.62 0.35 0.0384 0.0433 39.01 0.00 0.00 0.00 0.00 0.00 39.01 1219.78 0.25 580.55 0.28 0.00 0.00 9:30 2 0.40 0.61 0.36 0.0404 0.0456 41.06 0.00 0.00 0.00 0.00 0.00 41.06 1229.92 0.26 621.36 0.30 0.00 0.00 9:45 2.1 0.42 0.60 0.38 0.0424 0.0479 43.12 0.00 0.00 0.00 0.00 0.00 43.12 1240.60 0.26 664.22 0.32 0.00 0.00 10:00 2.2 0.44 0.59 0.40 0.0444 0.0502 45.17 0.00 0.00 0.00 0.00 0.00 45.17 1251.82 0.26 709.12 0.34 0.00 0.00 10:15 1.5 0.30 0.58 0.27 0.0303 0.0342 30.80 0.00 0.00 0.00 0.00 0.00 30.80 1263.57 0.26 739.66 0.36 0.00 0.00 10:30 1.5 0.30 0.58 0.27 0.0303 0.0342 30.80 0.00 0.00 0.00 0.00 0.00 30.80 1271.56 0.26 770.19 0.37 0.00 0.00 10:45 2 0.40 0.57 0.36 0.0404 0.0456 41.06 0.00 0.00 0.00 0.00 0.00 41.06 1279.55 0.27 810.98 0.39 0.00 0.00 11:00 2 0.40 0.56 0.36 0.0404 0.0456 41.06 0.00 0.00 0.00 0.00 0.00 41.06 1290.22 0.27 851.78 0.41 0.00 0.00 11:15 1.9 0.38 0.55 0.35 0.0384 0.0433 39.01 0.00 0.00 0.00 0.00 0.00 39.01 1300.90 0.27 890.52 0.43 0.00 0.00 11:30 1.9 0.38 0.54 0.35 0.0384 0.0433 39.01 0.00 0.00 0.00 0.00 0.00 39.01 1311.04 0.27 929.25 0.45 0.00 0.00 11:45 1.7 0.34 0.53 0.31 0.0343 0.0388 34.90 0.00 0.00 0.00 0.00 0.00 34.90 1321.17 0.28 963.88 0.47 0.00 0.00 12:00 1.8 0.36 0.53 0.33 0.0364 0.0411 36.96 0.00 0.00 0.00 0.00 0.00 36.96 1330.23 0.28 1000.56 0.49 0.00 0.00 12:15 2.5 0.51 0.52 0.45 0.0505 0.0570 51.33 0.00 0.00 0.00 0.00 0.00 51.33 1339.83 0.28 1051.61 0.51 0.00 0.00 12:30 2.6 0.53 0.51 0.47 0.0525 0.0593 53.38 0.00 0.00 0.00 0.00 0.00 53.38 1353.19 0.28 1104.71 0.54 0.00 0.00 12:45 2.8 0.57 0.50 N/A 0.0622 0.0703 63.25 0.00 0.00 0.00 0.00 0.00 63.25 1367.09 0.28 1167.67 0.57 0.00 0.00 462

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13:00 2.9 0.59 0.50 N/A 0.0900 0.1017 91.50 0.00 0.00 0.00 0.00 0.00 91.50 1383.56 0.29 1258.89 0.61 0.00 0.00 13:15 3.4 0.69 0.49 N/A 0.1985 0.2242 201.79 0.00 0.00 0.00 0.00 0.00 201.79 1407.43 0.29 1460.39 0.71 0.00 0.00 13:30 3.4 0.69 0.48 N/A 0.2059 0.2326 209.32 0.00 0.00 0.00 0.00 0.00 209.32 1460.16 0.30 1669.40 0.81 0.00 0.00 13:45 2.3 0.46 0.47 0.42 0.0465 0.0525 47.22 0.00 0.00 0.00 0.00 0.00 47.22 1514.86 0.32 1716.31 0.83 0.00 0.00 14:00 2.3 0.46 0.47 0.42 0.0465 0.0525 47.22 0.00 0.00 0.00 0.00 0.00 47.22 1527.13 0.32 1763.21 0.86 0.00 0.00 14:15 2.7 0.55 0.46 N/A 0.0862 0.0973 87.60 0.00 0.00 0.00 0.00 0.00 87.60 1539.41 0.32 1850.48 0.90 0.00 0.00 14:30 2.6 0.53 0.45 N/A 0.0730 0.0824 74.20 0.00 0.00 0.00 0.00 0.00 74.20 1562.25 0.33 1924.35 0.93 0.00 0.00 14:45 2.6 0.53 0.45 N/A 0.0799 0.0902 81.22 0.00 0.00 0.00 0.00 0.00 81.22 1581.58 0.33 2005.25 0.97 0.00 0.00 15:00 2.5 0.51 0.44 N/A 0.0665 0.0751 67.62 0.00 0.00 0.00 0.00 0.00 67.62 1602.75 0.33 2072.53 1.01 0.00 0.00 15:15 2.4 0.48 0.43 N/A 0.0530 0.0599 53.91 0.00 0.00 0.00 0.00 0.00 53.91 1620.35 0.34 2126.10 1.03 0.00 0.00 15:30 2.3 0.46 0.43 0.42 0.0465 0.0525 47.22 0.00 0.00 0.00 0.00 0.00 47.22 1634.37 0.34 2172.98 1.05 0.00 0.00 15:45 1.9 0.38 0.42 0.35 0.0384 0.0433 39.01 0.00 0.00 0.00 0.00 0.00 39.01 1646.64 0.34 2211.65 1.07 0.00 0.00 16:00 1.9 0.38 0.41 0.35 0.0384 0.0433 39.01 0.00 0.00 0.00 0.00 0.00 39.01 1656.76 0.35 2250.32 1.09 0.00 0.00 16:15 0.4 0.08 0.41 0.07 0.0081 0.0091 8.21 0.00 0.00 0.00 0.00 0.00 8.21 1666.88 0.35 2258.18 1.10 0.00 0.00 16:30 0.4 0.08 0.40 0.07 0.0081 0.0091 8.21 0.00 0.00 0.00 0.00 0.00 8.21 1668.94 0.35 2266.05 1.10 0.00 0.00 16:45 0.3 0.06 0.39 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1670.99 0.35 2271.86 1.10 0.00 0.00 17:00 0.3 0.06 0.39 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1672.51 0.35 2277.67 1.11 0.00 0.00 17:15 0.5 0.10 0.38 0.09 0.0101 0.0114 10.27 0.00 0.00 0.00 0.00 0.00 10.27 1674.03 0.35 2287.58 1.11 0.00 0.00 17:30 0.5 0.10 0.38 0.09 0.0101 0.0114 10.27 0.00 0.00 0.00 0.00 0.00 10.27 1676.63 0.35 2297.50 1.12 0.00 0.00 17:45 0.5 0.10 0.37 0.09 0.0101 0.0114 10.27 0.00 0.00 0.00 0.00 0.00 10.27 1679.22 0.35 2307.42 1.12 0.00 0.00 18:00 0.4 0.08 0.37 0.07 0.0081 0.0091 8.21 0.00 0.00 0.00 0.00 0.00 8.21 1681.82 0.35 2315.28 1.12 0.00 0.00 18:15 0.4 0.08 0.36 0.07 0.0081 0.0091 8.21 0.00 0.00 0.00 0.00 0.00 8.21 1683.88 0.35 2323.14 1.13 0.00 0.00 18:30 0.4 0.08 0.35 0.07 0.0081 0.0091 8.21 0.00 0.00 0.00 0.00 0.00 8.21 1685.93 0.35 2331.00 1.13 0.00 0.00 18:45 0.3 0.06 0.35 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1687.99 0.35 2336.81 1.13 0.00 0.00 19:00 0.2 0.04 0.34 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1689.51 0.35 2340.56 1.14 0.00 0.00 19:15 0.3 0.06 0.34 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1690.49 0.35 2346.37 1.14 0.00 0.00 19:30 0.4 0.08 0.34 0.07 0.0081 0.0091 8.21 0.00 0.00 0.00 0.00 0.00 8.21 1692.01 0.35 2354.23 1.14 0.00 0.00 19:45 0.3 0.06 0.33 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1694.07 0.35 2360.04 1.15 0.00 0.00 20:00 0.2 0.04 0.33 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1695.59 0.35 2363.79 1.15 0.00 0.00 20:15 0.3 0.06 0.32 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1696.57 0.35 2369.60 1.15 0.00 0.00 20:30 0.3 0.06 0.32 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1698.09 0.35 2375.40 1.15 0.00 0.00 20:45 0.3 0.06 0.31 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1699.61 0.35 2381.21 1.16 0.00 0.00 21:00 0.2 0.04 0.31 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1701.13 0.35 2384.96 1.16 0.00 0.00 21:15 0.3 0.06 0.31 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1702.11 0.35 2390.76 1.16 0.00 0.00 21:30 0.2 0.04 0.30 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1703.63 0.35 2394.52 1.16 0.00 0.00 21:45 0.3 0.06 0.30 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1704.61 0.36 2400.32 1.17 0.00 0.00 22:00 0.2 0.04 0.30 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1706.13 0.36 2404.07 1.17 0.00 0.00 22:15 0.3 0.06 0.29 0.05 0.0061 0.0068 6.16 0.00 0.00 0.00 0.00 0.00 6.16 1707.11 0.36 2409.87 1.17 0.00 0.00 22:30 0.2 0.04 0.29 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1708.63 0.36 2413.62 1.17 0.00 0.00 22:45 0.2 0.04 0.29 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1709.61 0.36 2417.37 1.17 0.00 0.00 23:00 0.2 0.04 0.29 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1710.59 0.36 2421.12 1.18 0.00 0.00 23:15 0.2 0.04 0.28 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1711.58 0.36 2424.87 1.18 0.00 0.00 23:30 0.2 0.04 0.28 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1712.56 0.36 2428.62 1.18 0.00 0.00 23:45 0.2 0.04 0.28 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1713.54 0.36 2432.37 1.18 0.00 0.00 24:00 0.2 0.04 0.28 0.04 0.0040 0.0046 4.11 0.00 0.00 0.00 0.00 0.00 4.11 1714.52 0.36 2436.12 1.18 0.00 0.00 0 0.00 0.28 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1715.50 0.36 2435.76 1.18 0.00 0.00 Total volume (cf)2464.09 Total Overflow (cf)0.00
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HYDROLOGY CALCULATIONS - program updated 4-14-22 LC
Using the RCFC&WCD Short Cut Unit Hydrograph Method
Area Designations Area 1 VERSION 2 Area=1.02ac+0.09ac typ street frontage=1.11ac 5/7/2024 LOT 16
Drainage Area (ac.)1.1100 JOB NUMBER 22106
Unit time (minutes)5 5 5 15
100 Year Storm Duration (hrs)1 3 6 24
Total Precipitation (Plates D-4.4,E-5.2, 5.4, 5.6)(in.)2.41 3.10 3.79 5.05 from NOAA interactive website Soils Group A
AMC index II Runoff Number (plate E-6.1)32
Plate E-6.2 Pervious Area Loss Rate (Fp)(in/hr)0.74 (AMC II) Percentage of Impervious Cover (Ai)(%) (plate E-6.3)26.6 20% per the RCFC Hydrology Manual 1AC LOT-PLATE D 5.6 AND 0.09AC TYPICAL STREET FRONTAGE Weighted Average Loss Rate (F=Fp(1-.9Ai))(in./hr.)0.56 (used for 1, 3, and 6 hour storm, the 24 hour storm uses variable maximum loss rate per plate E-1.1 (3 of 6)) Low Loss Rate Percent (%) 90
Retention Basin Percolation Rate (in/hr)0.01 (also used for drywell percolation rate) Percolation is taken incrementally.

Drywell design factors Upper sec. (ft.)=0.001 Lower sec. (ft.)=0.001 Ring diam. (ft.) =0.001 Drywell lower max. (cf)=0.00 Upper max.(cf)=0.00 Gravel bed width around drywell=0.001 Drywell total(cf)=0.00 Ret. Basin design (area, depth) Top =3234 s.f.Bot. =1078 s.f.Max. Depth (d)=4 Max. storage=8238.87 (d/3)*(bottom+top+(bottom*top)^0.50) Formulas vol=(h/3)*(bottom+top+(bottom*top)^0.50) area=bottom+(h/d)*(top-bottom)h=(vol*3)/(bottom+top+(bottom*top)^0.5)(values must be non-zero or error occurs) Outside input from:N/A 3.25
1 Hour Storm in 5 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:05 3.7 1.0700 0.5628 N/A 0.5072 0.5677 170.30 0.00 0.00 0.00 0.00 0.00 170.30 1078.00 0.07 170.23 0.08 0.00 0.00 0:10 4.8 1.3882 0.5628 N/A 0.8253 0.9237 277.12 0.00 0.00 0.00 0.00 0.00 277.12 1122.55 0.08 447.27 0.22 0.00 0.00 0:15 5.1 1.4749 0.5628 N/A 0.9121 1.0208 306.25 0.00 0.00 0.00 0.00 0.00 306.25 1195.04 0.08 753.44 0.37 0.00 0.00 0:20 4.9 1.4171 0.5628 N/A 0.8542 0.9561 286.83 0.00 0.00 0.00 0.00 0.00 286.83 1275.17 0.09 1040.18 0.51 0.00 0.00 0:25 6.6 1.9087 0.5628 N/A 1.3459 1.5064 451.91 0.00 0.00 0.00 0.00 0.00 451.91 1350.20 0.09 1492.00 0.72 0.00 0.00 0:30 7.3 2.1112 0.5628 N/A 1.5483 1.7330 519.89 0.00 0.00 0.00 0.00 0.00 519.89 1468.44 0.10 2011.78 0.98 0.00 0.00 0:35 8.4 2.4293 0.5628 N/A 1.8664 2.0890 626.70 0.00 0.00 0.00 0.00 0.00 626.70 1604.46 0.11 2638.38 1.28 0.00 0.00 0:40 9 2.6028 0.5628 N/A 2.0400 2.2832 684.97 0.00 0.00 0.00 0.00 0.00 684.97 1768.43 0.12 3323.22 1.61 0.00 0.00 0:45 12.3 3.5572 0.5628 N/A 2.9943 3.3514 1005.42 0.00 0.00 0.00 0.00 0.00 1005.42 1947.64 0.14 4328.50 2.10 0.00 0.00 0:50 17.6 5.0899 0.5628 N/A 4.5271 5.0669 1520.08 0.00 0.00 0.00 0.00 0.00 1520.08 2210.71 0.15 5848.43 2.84 0.00 0.00 0:55 16.1 4.6561 0.5628 N/A 4.0933 4.5814 1374.42 0.00 0.00 0.00 0.00 0.00 1374.42 2608.45 0.18 7222.66 3.51 0.00 0.00 1:00 4.2 1.2146 0.5628 N/A 0.6518 0.7295 218.86 0.00 0.00 0.00 0.00 0.00 218.86 2968.07 0.21 7441.32 3.61 0.00 0.00 MAX DEPTH 0 0.0000 0.5628 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3025.29 0.21 7441.11 3.61 0.00 0.00 0 0.0000 0.5628 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3025.24 0.21 7440.90 3.61 0.00 0.00 1:15 0 0.0000 0.5628 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3025.18 0.21 7440.69 3.61 0.00 0.00 Total volume (cf)7442.75 Total Overflow (cf)0.00
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3 Hour Storm in 5 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:05 1.3 0.48 0.56 0.44 0.0484 0.0541 16.24 0.00 0.00 0.00 0.00 0.00 16.24 1078.00 0.07 16.16 0.01 0.00 0.00 0:10 1.3 0.48 0.56 0.44 0.0484 0.0541 16.24 0.00 0.00 0.00 0.00 0.00 16.24 1082.23 0.08 32.33 0.02 0.00 0.00 0:15 1.1 0.41 0.56 0.37 0.0409 0.0458 13.74 0.00 0.00 0.00 0.00 0.00 13.74 1086.46 0.08 45.99 0.02 0.00 0.00 0:20 1.5 0.56 0.56 0.50 0.0558 0.0625 18.74 0.00 0.00 0.00 0.00 0.00 18.74 1090.04 0.08 64.65 0.03 0.00 0.00 0:25 1.5 0.56 0.56 0.50 0.0558 0.0625 18.74 0.00 0.00 0.00 0.00 0.00 18.74 1094.92 0.08 83.31 0.04 0.00 0.00 0:30 1.8 0.67 0.56 N/A 0.1068 0.1195 35.85 0.00 0.00 0.00 0.00 0.00 35.85 1099.80 0.08 119.08 0.06 0.00 0.00 0:35 1.5 0.56 0.56 0.50 0.0558 0.0625 18.74 0.00 0.00 0.00 0.00 0.00 18.74 1109.16 0.08 137.74 0.07 0.00 0.00 0:40 1.8 0.67 0.56 N/A 0.1068 0.1195 35.85 0.00 0.00 0.00 0.00 0.00 35.85 1114.04 0.08 173.51 0.08 0.00 0.00 0:45 1.8 0.67 0.56 N/A 0.1068 0.1195 35.85 0.00 0.00 0.00 0.00 0.00 35.85 1123.40 0.08 209.28 0.10 0.00 0.00 0:50 1.5 0.56 0.56 0.50 0.0558 0.0625 18.74 0.00 0.00 0.00 0.00 0.00 18.74 1132.76 0.08 227.93 0.11 0.00 0.00 0:55 1.6 0.60 0.56 0.54 0.0595 0.0666 19.99 0.00 0.00 0.00 0.00 0.00 19.99 1137.65 0.08 247.84 0.12 0.00 0.00 1:00 1.8 0.67 0.56 N/A 0.1068 0.1195 35.85 0.00 0.00 0.00 0.00 0.00 35.85 1142.86 0.08 283.61 0.14 0.00 0.00 1:05 2.2 0.82 0.56 N/A 0.2556 0.2860 85.81 0.00 0.00 0.00 0.00 0.00 85.81 1152.22 0.08 369.34 0.18 0.00 0.00 1:10 2.2 0.82 0.56 N/A 0.2556 0.2860 85.81 0.00 0.00 0.00 0.00 0.00 85.81 1174.65 0.08 455.06 0.22 0.00 0.00 1:15 2.2 0.82 0.56 N/A 0.2556 0.2860 85.81 0.00 0.00 0.00 0.00 0.00 85.81 1197.08 0.08 540.79 0.26 0.00 0.00 1:20 2 0.74 0.56 N/A 0.1812 0.2028 60.83 0.00 0.00 0.00 0.00 0.00 60.83 1219.52 0.08 601.53 0.29 0.00 0.00 1:25 2.6 0.97 0.56 N/A 0.4044 0.4526 135.77 0.00 0.00 0.00 0.00 0.00 135.77 1235.41 0.09 737.22 0.36 0.00 0.00 1:30 2.7 1.00 0.56 N/A 0.4416 0.4942 148.26 0.00 0.00 0.00 0.00 0.00 148.26 1270.92 0.09 885.40 0.43 0.00 0.00 1:35 2.4 0.89 0.56 N/A 0.3300 0.3693 110.79 0.00 0.00 0.00 0.00 0.00 110.79 1309.70 0.09 996.10 0.48 0.00 0.00 1:40 2.7 1.00 0.56 N/A 0.4416 0.4942 148.26 0.00 0.00 0.00 0.00 0.00 148.26 1338.66 0.09 1144.27 0.56 0.00 0.00 1:45 3.3 1.23 0.56 N/A 0.6648 0.7440 223.21 0.00 0.00 0.00 0.00 0.00 223.21 1377.44 0.10 1367.38 0.66 0.00 0.00 1:50 3.1 1.15 0.56 N/A 0.5904 0.6608 198.23 0.00 0.00 0.00 0.00 0.00 198.23 1435.82 0.10 1565.51 0.76 0.00 0.00 1:55 2.9 1.08 0.56 N/A 0.5160 0.5775 173.25 0.00 0.00 0.00 0.00 0.00 173.25 1487.67 0.10 1738.65 0.84 0.00 0.00 2:00 3 1.12 0.56 N/A 0.5532 0.6191 185.74 0.00 0.00 0.00 0.00 0.00 185.74 1532.98 0.11 1924.28 0.93 0.00 0.00 2:05 3.1 1.15 0.56 N/A 0.5904 0.6608 198.23 0.00 0.00 0.00 0.00 0.00 198.23 1581.56 0.11 2122.39 1.03 0.00 0.00 2:10 4.2 1.56 0.56 N/A 0.9996 1.1188 335.63 0.00 0.00 0.00 0.00 0.00 335.63 1633.40 0.11 2457.91 1.19 0.00 0.00 2:15 5 1.86 0.56 N/A 1.2972 1.4518 435.55 0.00 0.00 0.00 0.00 0.00 435.55 1721.20 0.12 2893.34 1.40 0.00 0.00 2:20 3.5 1.30 0.56 N/A 0.7392 0.8273 248.19 0.00 0.00 0.00 0.00 0.00 248.19 1835.15 0.13 3141.40 1.53 0.00 0.00 2:25 6.8 2.53 0.56 N/A 1.9668 2.2013 660.39 0.00 0.00 0.00 0.00 0.00 660.39 1900.06 0.13 3801.66 1.85 0.00 0.00 2:30 7.3 2.72 0.56 N/A 2.1528 2.4095 722.84 0.00 0.00 0.00 0.00 0.00 722.84 2072.84 0.14 4524.36 2.20 0.00 0.00 2:35 8.2 3.05 0.56 N/A 2.4876 2.7842 835.26 0.00 0.00 0.00 0.00 0.00 835.26 2261.96 0.16 5359.46 2.60 0.00 0.00 2:40 5.9 2.19 0.56 N/A 1.6320 1.8266 547.97 0.00 0.00 0.00 0.00 0.00 547.97 2480.50 0.17 5907.26 2.87 0.00 0.00 2:45 2 0.74 0.56 N/A 0.1812 0.2028 60.83 0.00 0.00 0.00 0.00 0.00 60.83 2623.85 0.18 5967.90 2.90 0.00 0.00 2:50 1.8 0.67 0.56 N/A 0.1068 0.1195 35.85 0.00 0.00 0.00 0.00 0.00 35.85 2639.72 0.18 6003.56 2.91 0.00 0.00 2:55 1.8 0.67 0.56 N/A 0.1068 0.1195 35.85 0.00 0.00 0.00 0.00 0.00 35.85 2649.05 0.18 6039.23 2.93 0.00 0.00 3:00 0.6 0.22 0.56 0.20 0.0223 0.0250 7.49 0.00 0.00 0.00 0.00 0.00 7.49 2658.38 0.18 6046.54 2.94 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2660.30 0.18 6046.35 2.94 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2660.25 0.18 6046.17 2.94 0.00 0.00 3:15 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2660.20 0.18 6045.98 2.94 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2660.15 0.18 6045.80 2.94 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2660.10 0.18 6045.61 2.94 0.00 0.00 3:30 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2660.05 0.18 6045.43 2.94 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2660.01 0.18 6045.24 2.93 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2659.96 0.18 6045.06 2.93 0.00 0.00 Total volume (cf)6050.36 Total Overflow (cf)0.00
465

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6 Hour Storm in 5 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:05 0.5 0.23 0.56 0.20 0.0227 0.0255 7.64 0.00 0.00 0.00 0.00 0.00 7.64 1078.00 0.07 7.56 0.00 0.00 0.00 0:10 0.6 0.27 0.56 0.25 0.0273 0.0305 9.16 0.00 0.00 0.00 0.00 0.00 9.16 1079.98 0.07 16.65 0.01 0.00 0.00 0:15 0.6 0.27 0.56 0.25 0.0273 0.0305 9.16 0.00 0.00 0.00 0.00 0.00 9.16 1082.36 0.08 25.74 0.01 0.00 0.00 0:20 0.6 0.27 0.56 0.25 0.0273 0.0305 9.16 0.00 0.00 0.00 0.00 0.00 9.16 1084.73 0.08 34.82 0.02 0.00 0.00 0:25 0.6 0.27 0.56 0.25 0.0273 0.0305 9.16 0.00 0.00 0.00 0.00 0.00 9.16 1087.11 0.08 43.91 0.02 0.00 0.00 0:30 0.7 0.32 0.56 0.29 0.0318 0.0356 10.69 0.00 0.00 0.00 0.00 0.00 10.69 1089.49 0.08 54.52 0.03 0.00 0.00 0:35 0.7 0.32 0.56 0.29 0.0318 0.0356 10.69 0.00 0.00 0.00 0.00 0.00 10.69 1092.27 0.08 65.14 0.03 0.00 0.00 0:40 0.7 0.32 0.56 0.29 0.0318 0.0356 10.69 0.00 0.00 0.00 0.00 0.00 10.69 1095.05 0.08 75.75 0.04 0.00 0.00 0:45 0.7 0.32 0.56 0.29 0.0318 0.0356 10.69 0.00 0.00 0.00 0.00 0.00 10.69 1097.82 0.08 86.37 0.04 0.00 0.00 0:50 0.7 0.32 0.56 0.29 0.0318 0.0356 10.69 0.00 0.00 0.00 0.00 0.00 10.69 1100.60 0.08 96.98 0.05 0.00 0.00 0:55 0.7 0.32 0.56 0.29 0.0318 0.0356 10.69 0.00 0.00 0.00 0.00 0.00 10.69 1103.38 0.08 107.59 0.05 0.00 0.00 1:00 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1106.16 0.08 119.73 0.06 0.00 0.00 1:05 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1109.33 0.08 131.87 0.06 0.00 0.00 1:10 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1112.51 0.08 144.01 0.07 0.00 0.00 1:15 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1115.69 0.08 156.15 0.08 0.00 0.00 1:20 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1118.86 0.08 168.29 0.08 0.00 0.00 1:25 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1122.04 0.08 180.43 0.09 0.00 0.00 1:30 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1125.22 0.08 192.57 0.09 0.00 0.00 1:35 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1128.39 0.08 204.71 0.10 0.00 0.00 1:40 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1131.57 0.08 216.84 0.11 0.00 0.00 1:45 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1134.75 0.08 228.98 0.11 0.00 0.00 1:50 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1137.92 0.08 241.12 0.12 0.00 0.00 1:55 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1141.10 0.08 253.26 0.12 0.00 0.00 2:00 0.9 0.41 0.56 0.37 0.0409 0.0458 13.74 0.00 0.00 0.00 0.00 0.00 13.74 1144.27 0.08 266.92 0.13 0.00 0.00 2:05 0.8 0.36 0.56 0.33 0.0364 0.0407 12.22 0.00 0.00 0.00 0.00 0.00 12.22 1147.85 0.08 279.06 0.14 0.00 0.00 2:10 0.9 0.41 0.56 0.37 0.0409 0.0458 13.74 0.00 0.00 0.00 0.00 0.00 13.74 1151.03 0.08 292.72 0.14 0.00 0.00 2:15 0.9 0.41 0.56 0.37 0.0409 0.0458 13.74 0.00 0.00 0.00 0.00 0.00 13.74 1154.60 0.08 306.39 0.15 0.00 0.00 2:20 0.9 0.41 0.56 0.37 0.0409 0.0458 13.74 0.00 0.00 0.00 0.00 0.00 13.74 1158.18 0.08 320.05 0.16 0.00 0.00 2:25 0.9 0.41 0.56 0.37 0.0409 0.0458 13.74 0.00 0.00 0.00 0.00 0.00 13.74 1161.75 0.08 333.71 0.16 0.00 0.00 2:30 0.9 0.41 0.56 0.37 0.0409 0.0458 13.74 0.00 0.00 0.00 0.00 0.00 13.74 1165.33 0.08 347.38 0.17 0.00 0.00 2:35 0.9 0.41 0.56 0.37 0.0409 0.0458 13.74 0.00 0.00 0.00 0.00 0.00 13.74 1168.90 0.08 361.04 0.18 0.00 0.00 2:40 0.9 0.41 0.56 0.37 0.0409 0.0458 13.74 0.00 0.00 0.00 0.00 0.00 13.74 1172.48 0.08 374.70 0.18 0.00 0.00 2:45 1 0.45 0.56 0.41 0.0455 0.0509 15.27 0.00 0.00 0.00 0.00 0.00 15.27 1176.05 0.08 389.89 0.19 0.00 0.00 2:50 1 0.45 0.56 0.41 0.0455 0.0509 15.27 0.00 0.00 0.00 0.00 0.00 15.27 1180.03 0.08 405.08 0.20 0.00 0.00 2:55 1 0.45 0.56 0.41 0.0455 0.0509 15.27 0.00 0.00 0.00 0.00 0.00 15.27 1184.00 0.08 420.27 0.20 0.00 0.00 3:00 1 0.45 0.56 0.41 0.0455 0.0509 15.27 0.00 0.00 0.00 0.00 0.00 15.27 1187.98 0.08 435.46 0.21 0.00 0.00 3:05 1 0.45 0.56 0.41 0.0455 0.0509 15.27 0.00 0.00 0.00 0.00 0.00 15.27 1191.95 0.08 450.65 0.22 0.00 0.00 3:10 1.1 0.50 0.56 0.45 0.0500 0.0560 16.80 0.00 0.00 0.00 0.00 0.00 16.80 1195.93 0.08 467.36 0.23 0.00 0.00 3:15 1.1 0.50 0.56 0.45 0.0500 0.0560 16.80 0.00 0.00 0.00 0.00 0.00 16.80 1200.30 0.08 484.08 0.24 0.00 0.00 3:20 1.1 0.50 0.56 0.45 0.0500 0.0560 16.80 0.00 0.00 0.00 0.00 0.00 16.80 1204.68 0.08 500.79 0.24 0.00 0.00 3:25 1.2 0.55 0.56 0.49 0.0546 0.0611 18.33 0.00 0.00 0.00 0.00 0.00 18.33 1209.05 0.08 519.03 0.25 0.00 0.00 3:30 1.3 0.59 0.56 0.53 0.0591 0.0662 19.85 0.00 0.00 0.00 0.00 0.00 19.85 1213.82 0.08 538.80 0.26 0.00 0.00 3:35 1.4 0.64 0.56 N/A 0.0739 0.0827 24.81 0.00 0.00 0.00 0.00 0.00 24.81 1219.00 0.08 563.52 0.27 0.00 0.00 3:40 1.4 0.64 0.56 N/A 0.0739 0.0827 24.81 0.00 0.00 0.00 0.00 0.00 24.81 1225.47 0.09 588.24 0.29 0.00 0.00 3:45 1.5 0.68 0.56 N/A 0.1194 0.1336 40.08 0.00 0.00 0.00 0.00 0.00 40.08 1231.93 0.09 628.23 0.31 0.00 0.00 3:50 1.5 0.68 0.56 N/A 0.1194 0.1336 40.08 0.00 0.00 0.00 0.00 0.00 40.08 1242.40 0.09 668.22 0.32 0.00 0.00 3:55 1.6 0.73 0.56 N/A 0.1648 0.1845 55.35 0.00 0.00 0.00 0.00 0.00 55.35 1252.86 0.09 723.48 0.35 0.00 0.00 4:00 1.6 0.73 0.56 N/A 0.1648 0.1845 55.35 0.00 0.00 0.00 0.00 0.00 55.35 1267.33 0.09 778.74 0.38 0.00 0.00 4:05 1.7 0.77 0.56 N/A 0.2103 0.2354 70.62 0.00 0.00 0.00 0.00 0.00 70.62 1281.79 0.09 849.27 0.41 0.00 0.00 4:10 1.8 0.82 0.56 N/A 0.2558 0.2863 85.89 0.00 0.00 0.00 0.00 0.00 85.89 1300.24 0.09 935.07 0.45 0.00 0.00 4:15 1.9 0.86 0.56 N/A 0.3013 0.3372 101.16 0.00 0.00 0.00 0.00 0.00 101.16 1322.70 0.09 1036.14 0.50 0.00 0.00 466

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4:20 2 0.91 0.56 N/A 0.3468 0.3881 116.43 0.00 0.00 0.00 0.00 0.00 116.43 1349.14 0.09 1152.48 0.56 0.00 0.00 4:25 2.1 0.96 0.56 N/A 0.3922 0.4390 131.70 0.00 0.00 0.00 0.00 0.00 131.70 1379.59 0.10 1284.09 0.62 0.00 0.00 4:30 2.1 0.96 0.56 N/A 0.3922 0.4390 131.70 0.00 0.00 0.00 0.00 0.00 131.70 1414.03 0.10 1415.69 0.69 0.00 0.00 4:35 2.2 1.00 0.56 N/A 0.4377 0.4899 146.97 0.00 0.00 0.00 0.00 0.00 146.97 1448.47 0.10 1562.57 0.76 0.00 0.00 4:40 2.3 1.05 0.56 N/A 0.4832 0.5408 162.25 0.00 0.00 0.00 0.00 0.00 162.25 1486.90 0.10 1724.71 0.84 0.00 0.00 4:45 2.4 1.09 0.56 N/A 0.5287 0.5917 177.52 0.00 0.00 0.00 0.00 0.00 177.52 1529.33 0.11 1902.12 0.92 0.00 0.00 4:50 2.4 1.09 0.56 N/A 0.5287 0.5917 177.52 0.00 0.00 0.00 0.00 0.00 177.52 1575.76 0.11 2079.52 1.01 0.00 0.00 4:55 2.5 1.14 0.56 N/A 0.5742 0.6426 192.79 0.00 0.00 0.00 0.00 0.00 192.79 1622.18 0.11 2272.20 1.10 0.00 0.00 5:00 2.6 1.18 0.56 N/A 0.6196 0.6935 208.06 0.00 0.00 0.00 0.00 0.00 208.06 1672.60 0.12 2480.14 1.20 0.00 0.00 5:05 3.1 1.41 0.56 N/A 0.8470 0.9480 284.41 0.00 0.00 0.00 0.00 0.00 284.41 1727.02 0.12 2764.44 1.34 0.00 0.00 5:10 3.6 1.64 0.56 N/A 1.0744 1.2026 360.77 0.00 0.00 0.00 0.00 0.00 360.77 1801.42 0.13 3125.08 1.52 0.00 0.00 5:15 3.9 1.77 0.56 N/A 1.2109 1.3553 406.58 0.00 0.00 0.00 0.00 0.00 406.58 1895.79 0.13 3531.53 1.71 0.00 0.00 5:20 4.2 1.91 0.56 N/A 1.3473 1.5080 452.40 0.00 0.00 0.00 0.00 0.00 452.40 2002.15 0.14 3983.78 1.93 0.00 0.00 5:25 4.7 2.14 0.56 N/A 1.5747 1.7625 528.75 0.00 0.00 0.00 0.00 0.00 528.75 2120.50 0.15 4512.39 2.19 0.00 0.00 5:30 5.6 2.55 0.56 N/A 1.9840 2.2206 666.19 0.00 0.00 0.00 0.00 0.00 666.19 2258.83 0.16 5178.42 2.51 0.00 0.00 5:35 1.9 0.86 0.56 N/A 0.3013 0.3372 101.16 0.00 0.00 0.00 0.00 0.00 101.16 2433.12 0.17 5279.41 2.56 0.00 0.00 5:40 0.9 0.41 0.56 0.37 0.0409 0.0458 13.74 0.00 0.00 0.00 0.00 0.00 13.74 2459.55 0.17 5292.99 2.57 0.00 0.00 5:45 0.6 0.27 0.56 0.25 0.0273 0.0305 9.16 0.00 0.00 0.00 0.00 0.00 9.16 2463.10 0.17 5301.98 2.57 0.00 0.00 5:50 0.5 0.23 0.56 0.20 0.0227 0.0255 7.64 0.00 0.00 0.00 0.00 0.00 7.64 2465.46 0.17 5309.44 2.58 0.00 0.00 5:55 0.3 0.14 0.56 0.12 0.0136 0.0153 4.58 0.00 0.00 0.00 0.00 0.00 4.58 2467.41 0.17 5313.85 2.58 0.00 0.00 6:00 0.2 0.09 0.56 0.08 0.0091 0.0102 3.05 0.00 0.00 0.00 0.00 0.00 3.05 2468.56 0.17 5316.73 2.58 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2469.32 0.17 5316.56 2.58 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2469.27 0.17 5316.39 2.58 0.00 0.00 6:15 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2469.23 0.17 5316.22 2.58 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2469.18 0.17 5316.05 2.58 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2469.14 0.17 5315.88 2.58 0.00 0.00 6:30 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2469.09 0.17 5315.71 2.58 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2469.05 0.17 5315.53 2.58 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2469.00 0.17 5315.36 2.58 0.00 0.00 6:45 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2468.96 0.17 5315.19 2.58 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2468.91 0.17 5315.02 2.58 0.00 0.00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2468.87 0.17 5314.85 2.58 0.00 0.00 7:00 0 0.00 0.56 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2468.82 0.17 5314.68 2.58 0.00 0.00 Total volume (cf)5323.63 Total Overflow (cf)0.00
467

5 of 6
24 Hour Storm in 15 minute increments Drywell Drywell Drywell Drywell Overflow Basin Basin Basin Time Pattern Storm Loss Rate Value Effective Flow Flow Outside Retention Period Storage Storage To Retention Period Storage Storage Overflow Overflow %Rain (in/hr)Max.Min.Rain (in/hr)Rate (cfs)Vol. (cf)Input (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Basin (cf)Area (sf)Perc. (cf)Vol. (cf)Depth (ft)Vol. (cf)Rate (cfs) 0:15 0.2 0.04 0.99 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1078.00 0.22 3.85 0.00 0.00 0.00 0:30 0.3 0.06 0.98 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1079.01 0.22 9.72 0.00 0.00 0.00 0:45 0.3 0.06 0.97 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1080.54 0.23 15.60 0.01 0.00 0.00 1:00 0.4 0.08 0.95 0.07 0.0081 0.0090 8.14 0.00 0.00 0.00 0.00 0.00 8.14 1082.08 0.23 23.52 0.01 0.00 0.00 1:15 0.3 0.06 0.94 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1084.15 0.23 29.40 0.01 0.00 0.00 1:30 0.3 0.06 0.93 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1085.69 0.23 35.27 0.02 0.00 0.00 1:45 0.3 0.06 0.92 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1087.23 0.23 41.15 0.02 0.00 0.00 2:00 0.4 0.08 0.91 0.07 0.0081 0.0090 8.14 0.00 0.00 0.00 0.00 0.00 8.14 1088.77 0.23 49.06 0.02 0.00 0.00 2:15 0.4 0.08 0.90 0.07 0.0081 0.0090 8.14 0.00 0.00 0.00 0.00 0.00 8.14 1090.84 0.23 56.98 0.03 0.00 0.00 2:30 0.4 0.08 0.89 0.07 0.0081 0.0090 8.14 0.00 0.00 0.00 0.00 0.00 8.14 1092.91 0.23 64.89 0.03 0.00 0.00 2:45 0.5 0.10 0.88 0.09 0.0101 0.0113 10.17 0.00 0.00 0.00 0.00 0.00 10.17 1094.98 0.23 74.83 0.04 0.00 0.00 3:00 0.5 0.10 0.87 0.09 0.0101 0.0113 10.17 0.00 0.00 0.00 0.00 0.00 10.17 1097.58 0.23 84.78 0.04 0.00 0.00 3:15 0.5 0.10 0.85 0.09 0.0101 0.0113 10.17 0.00 0.00 0.00 0.00 0.00 10.17 1100.19 0.23 94.72 0.05 0.00 0.00 3:30 0.5 0.10 0.84 0.09 0.0101 0.0113 10.17 0.00 0.00 0.00 0.00 0.00 10.17 1102.79 0.23 104.67 0.05 0.00 0.00 3:45 0.5 0.10 0.83 0.09 0.0101 0.0113 10.17 0.00 0.00 0.00 0.00 0.00 10.17 1105.39 0.23 114.61 0.06 0.00 0.00 4:00 0.6 0.12 0.82 0.11 0.0121 0.0136 12.21 0.00 0.00 0.00 0.00 0.00 12.21 1107.99 0.23 126.59 0.06 0.00 0.00 4:15 0.6 0.12 0.81 0.11 0.0121 0.0136 12.21 0.00 0.00 0.00 0.00 0.00 12.21 1111.13 0.23 138.57 0.07 0.00 0.00 4:30 0.7 0.14 0.80 0.13 0.0141 0.0158 14.24 0.00 0.00 0.00 0.00 0.00 14.24 1114.26 0.23 152.58 0.07 0.00 0.00 4:45 0.7 0.14 0.79 0.13 0.0141 0.0158 14.24 0.00 0.00 0.00 0.00 0.00 14.24 1117.93 0.23 166.59 0.08 0.00 0.00 5:00 0.8 0.16 0.78 0.15 0.0162 0.0181 16.28 0.00 0.00 0.00 0.00 0.00 16.28 1121.59 0.23 182.63 0.09 0.00 0.00 5:15 0.6 0.12 0.77 0.11 0.0121 0.0136 12.21 0.00 0.00 0.00 0.00 0.00 12.21 1125.79 0.23 194.61 0.09 0.00 0.00 5:30 0.7 0.14 0.76 0.13 0.0141 0.0158 14.24 0.00 0.00 0.00 0.00 0.00 14.24 1128.93 0.24 208.62 0.10 0.00 0.00 5:45 0.8 0.16 0.75 0.15 0.0162 0.0181 16.28 0.00 0.00 0.00 0.00 0.00 16.28 1132.59 0.24 224.66 0.11 0.00 0.00 6:00 0.8 0.16 0.74 0.15 0.0162 0.0181 16.28 0.00 0.00 0.00 0.00 0.00 16.28 1136.79 0.24 240.70 0.12 0.00 0.00 6:15 0.9 0.18 0.73 0.16 0.0182 0.0203 18.31 0.00 0.00 0.00 0.00 0.00 18.31 1140.99 0.24 258.78 0.13 0.00 0.00 6:30 0.9 0.18 0.72 0.16 0.0182 0.0203 18.31 0.00 0.00 0.00 0.00 0.00 18.31 1145.72 0.24 276.85 0.13 0.00 0.00 6:45 1 0.20 0.71 0.18 0.0202 0.0226 20.35 0.00 0.00 0.00 0.00 0.00 20.35 1150.45 0.24 296.96 0.14 0.00 0.00 7:00 1 0.20 0.70 0.18 0.0202 0.0226 20.35 0.00 0.00 0.00 0.00 0.00 20.35 1155.71 0.24 317.07 0.15 0.00 0.00 7:15 1 0.20 0.69 0.18 0.0202 0.0226 20.35 0.00 0.00 0.00 0.00 0.00 20.35 1160.97 0.24 337.17 0.16 0.00 0.00 7:30 1.1 0.22 0.68 0.20 0.0222 0.0249 22.38 0.00 0.00 0.00 0.00 0.00 22.38 1166.23 0.24 359.31 0.17 0.00 0.00 7:45 1.2 0.24 0.67 0.22 0.0242 0.0271 24.42 0.00 0.00 0.00 0.00 0.00 24.42 1172.03 0.24 383.49 0.19 0.00 0.00 8:00 1.3 0.26 0.66 0.24 0.0263 0.0294 26.45 0.00 0.00 0.00 0.00 0.00 26.45 1178.35 0.25 409.69 0.20 0.00 0.00 8:15 1.5 0.30 0.66 0.27 0.0303 0.0339 30.52 0.00 0.00 0.00 0.00 0.00 30.52 1185.21 0.25 439.97 0.21 0.00 0.00 8:30 1.5 0.30 0.65 0.27 0.0303 0.0339 30.52 0.00 0.00 0.00 0.00 0.00 30.52 1193.13 0.25 470.24 0.23 0.00 0.00 8:45 1.6 0.32 0.64 0.29 0.0323 0.0362 32.56 0.00 0.00 0.00 0.00 0.00 32.56 1201.06 0.25 502.55 0.24 0.00 0.00 9:00 1.7 0.34 0.63 0.31 0.0343 0.0384 34.59 0.00 0.00 0.00 0.00 0.00 34.59 1209.51 0.25 536.89 0.26 0.00 0.00 9:15 1.9 0.38 0.62 0.35 0.0384 0.0430 38.66 0.00 0.00 0.00 0.00 0.00 38.66 1218.50 0.25 575.29 0.28 0.00 0.00 9:30 2 0.40 0.61 0.36 0.0404 0.0452 40.70 0.00 0.00 0.00 0.00 0.00 40.70 1228.55 0.26 615.73 0.30 0.00 0.00 9:45 2.1 0.42 0.60 0.38 0.0424 0.0475 42.73 0.00 0.00 0.00 0.00 0.00 42.73 1239.13 0.26 658.21 0.32 0.00 0.00 10:00 2.2 0.44 0.59 0.40 0.0444 0.0497 44.77 0.00 0.00 0.00 0.00 0.00 44.77 1250.24 0.26 702.71 0.34 0.00 0.00 10:15 1.5 0.30 0.58 0.27 0.0303 0.0339 30.52 0.00 0.00 0.00 0.00 0.00 30.52 1261.89 0.26 732.97 0.36 0.00 0.00 10:30 1.5 0.30 0.58 0.27 0.0303 0.0339 30.52 0.00 0.00 0.00 0.00 0.00 30.52 1269.81 0.26 763.23 0.37 0.00 0.00 10:45 2 0.40 0.57 0.36 0.0404 0.0452 40.70 0.00 0.00 0.00 0.00 0.00 40.70 1277.73 0.27 803.66 0.39 0.00 0.00 11:00 2 0.40 0.56 0.36 0.0404 0.0452 40.70 0.00 0.00 0.00 0.00 0.00 40.70 1288.31 0.27 844.09 0.41 0.00 0.00 11:15 1.9 0.38 0.55 0.35 0.0384 0.0430 38.66 0.00 0.00 0.00 0.00 0.00 38.66 1298.89 0.27 882.48 0.43 0.00 0.00 11:30 1.9 0.38 0.54 0.35 0.0384 0.0430 38.66 0.00 0.00 0.00 0.00 0.00 38.66 1308.93 0.27 920.86 0.45 0.00 0.00 11:45 1.7 0.34 0.53 0.31 0.0343 0.0384 34.59 0.00 0.00 0.00 0.00 0.00 34.59 1318.98 0.27 955.18 0.46 0.00 0.00 12:00 1.8 0.36 0.53 0.33 0.0364 0.0407 36.63 0.00 0.00 0.00 0.00 0.00 36.63 1327.96 0.28 991.53 0.48 0.00 0.00 12:15 2.5 0.51 0.52 0.45 0.0505 0.0565 50.87 0.00 0.00 0.00 0.00 0.00 50.87 1337.47 0.28 1042.12 0.51 0.00 0.00 12:30 2.6 0.53 0.51 0.47 0.0525 0.0588 52.90 0.00 0.00 0.00 0.00 0.00 52.90 1350.71 0.28 1094.75 0.53 0.00 0.00 12:45 2.8 0.57 0.50 N/A 0.0622 0.0697 62.69 0.00 0.00 0.00 0.00 0.00 62.69 1364.48 0.28 1157.15 0.56 0.00 0.00 468

6 of 6
13:00 2.9 0.59 0.50 N/A 0.0900 0.1008 90.69 0.00 0.00 0.00 0.00 0.00 90.69 1380.81 0.29 1247.55 0.61 0.00 0.00 13:15 3.4 0.69 0.49 N/A 0.1985 0.2222 199.99 0.00 0.00 0.00 0.00 0.00 199.99 1404.47 0.29 1447.24 0.70 0.00 0.00 13:30 3.4 0.69 0.48 N/A 0.2059 0.2305 207.45 0.00 0.00 0.00 0.00 0.00 207.45 1456.72 0.30 1654.39 0.80 0.00 0.00 13:45 2.3 0.46 0.47 0.42 0.0465 0.0520 46.80 0.00 0.00 0.00 0.00 0.00 46.80 1510.93 0.31 1700.87 0.83 0.00 0.00 14:00 2.3 0.46 0.47 0.42 0.0465 0.0520 46.80 0.00 0.00 0.00 0.00 0.00 46.80 1523.09 0.32 1747.35 0.85 0.00 0.00 14:15 2.7 0.55 0.46 N/A 0.0862 0.0965 86.81 0.00 0.00 0.00 0.00 0.00 86.81 1535.26 0.32 1833.85 0.89 0.00 0.00 14:30 2.6 0.53 0.45 N/A 0.0730 0.0817 73.53 0.00 0.00 0.00 0.00 0.00 73.53 1557.89 0.32 1907.06 0.93 0.00 0.00 14:45 2.6 0.53 0.45 N/A 0.0799 0.0894 80.50 0.00 0.00 0.00 0.00 0.00 80.50 1577.05 0.33 1987.23 0.96 0.00 0.00 15:00 2.5 0.51 0.44 N/A 0.0665 0.0745 67.01 0.00 0.00 0.00 0.00 0.00 67.01 1598.03 0.33 2053.91 1.00 0.00 0.00 15:15 2.4 0.48 0.43 N/A 0.0530 0.0594 53.43 0.00 0.00 0.00 0.00 0.00 53.43 1615.48 0.34 2107.00 1.02 0.00 0.00 15:30 2.3 0.46 0.43 0.42 0.0465 0.0520 46.80 0.00 0.00 0.00 0.00 0.00 46.80 1629.37 0.34 2153.46 1.05 0.00 0.00 15:45 1.9 0.38 0.42 0.35 0.0384 0.0430 38.66 0.00 0.00 0.00 0.00 0.00 38.66 1641.53 0.34 2191.78 1.06 0.00 0.00 16:00 1.9 0.38 0.41 0.35 0.0384 0.0430 38.66 0.00 0.00 0.00 0.00 0.00 38.66 1651.56 0.34 2230.10 1.08 0.00 0.00 16:15 0.4 0.08 0.41 0.07 0.0081 0.0090 8.14 0.00 0.00 0.00 0.00 0.00 8.14 1661.59 0.35 2237.89 1.09 0.00 0.00 16:30 0.4 0.08 0.40 0.07 0.0081 0.0090 8.14 0.00 0.00 0.00 0.00 0.00 8.14 1663.62 0.35 2245.68 1.09 0.00 0.00 16:45 0.3 0.06 0.39 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1665.66 0.35 2251.44 1.09 0.00 0.00 17:00 0.3 0.06 0.39 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1667.17 0.35 2257.20 1.10 0.00 0.00 17:15 0.5 0.10 0.38 0.09 0.0101 0.0113 10.17 0.00 0.00 0.00 0.00 0.00 10.17 1668.68 0.35 2267.02 1.10 0.00 0.00 17:30 0.5 0.10 0.38 0.09 0.0101 0.0113 10.17 0.00 0.00 0.00 0.00 0.00 10.17 1671.25 0.35 2276.85 1.11 0.00 0.00 17:45 0.5 0.10 0.37 0.09 0.0101 0.0113 10.17 0.00 0.00 0.00 0.00 0.00 10.17 1673.82 0.35 2286.67 1.11 0.00 0.00 18:00 0.4 0.08 0.37 0.07 0.0081 0.0090 8.14 0.00 0.00 0.00 0.00 0.00 8.14 1676.39 0.35 2294.46 1.11 0.00 0.00 18:15 0.4 0.08 0.36 0.07 0.0081 0.0090 8.14 0.00 0.00 0.00 0.00 0.00 8.14 1678.43 0.35 2302.25 1.12 0.00 0.00 18:30 0.4 0.08 0.35 0.07 0.0081 0.0090 8.14 0.00 0.00 0.00 0.00 0.00 8.14 1680.47 0.35 2310.04 1.12 0.00 0.00 18:45 0.3 0.06 0.35 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1682.51 0.35 2315.79 1.12 0.00 0.00 19:00 0.2 0.04 0.34 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1684.01 0.35 2319.51 1.13 0.00 0.00 19:15 0.3 0.06 0.34 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1684.99 0.35 2325.27 1.13 0.00 0.00 19:30 0.4 0.08 0.34 0.07 0.0081 0.0090 8.14 0.00 0.00 0.00 0.00 0.00 8.14 1686.49 0.35 2333.05 1.13 0.00 0.00 19:45 0.3 0.06 0.33 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1688.53 0.35 2338.81 1.14 0.00 0.00 20:00 0.2 0.04 0.33 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1690.03 0.35 2342.52 1.14 0.00 0.00 20:15 0.3 0.06 0.32 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1691.01 0.35 2348.28 1.14 0.00 0.00 20:30 0.3 0.06 0.32 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1692.51 0.35 2354.03 1.14 0.00 0.00 20:45 0.3 0.06 0.31 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1694.02 0.35 2359.78 1.15 0.00 0.00 21:00 0.2 0.04 0.31 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1695.52 0.35 2363.50 1.15 0.00 0.00 21:15 0.3 0.06 0.31 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1696.50 0.35 2369.25 1.15 0.00 0.00 21:30 0.2 0.04 0.30 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1698.00 0.35 2372.96 1.15 0.00 0.00 21:45 0.3 0.06 0.30 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1698.97 0.35 2378.71 1.15 0.00 0.00 22:00 0.2 0.04 0.30 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1700.48 0.35 2382.43 1.16 0.00 0.00 22:15 0.3 0.06 0.29 0.05 0.0061 0.0068 6.10 0.00 0.00 0.00 0.00 0.00 6.10 1701.45 0.35 2388.18 1.16 0.00 0.00 22:30 0.2 0.04 0.29 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1702.95 0.35 2391.89 1.16 0.00 0.00 22:45 0.2 0.04 0.29 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1703.93 0.35 2395.61 1.16 0.00 0.00 23:00 0.2 0.04 0.29 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1704.90 0.36 2399.32 1.16 0.00 0.00 23:15 0.2 0.04 0.28 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1705.87 0.36 2403.04 1.17 0.00 0.00 23:30 0.2 0.04 0.28 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1706.84 0.36 2406.75 1.17 0.00 0.00 23:45 0.2 0.04 0.28 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1707.81 0.36 2410.47 1.17 0.00 0.00 24:00 0.2 0.04 0.28 0.04 0.0040 0.0045 4.07 0.00 0.00 0.00 0.00 0.00 4.07 1708.79 0.36 2414.18 1.17 0.00 0.00 0 0.00 0.28 0.00 0.0000 0.0000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1709.76 0.36 2413.82 1.17 0.00 0.00 Total volume (cf)2442.09 Total Overflow (cf)0.00
469

EXHIBITS
470

FOMOTORENGINEERING
471
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PREL M NARY HYDROLOGY

TENTATVE TRACT MAP NO,

A PORTION OF THE
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OWNER: /
j VICKI S PETERSEN LIVING TRUST /
_ APN: 689-140-018
ZONING: RESIDENTIAL ESTATE
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0 50'
NORTH
100'
SCALE 1"-50'
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STATE OF
NW QUARTER OF SECTION 2, TOWNSHIP 5 SOUTH,

AND MERIDIAN, IN THE COUNTY OF RIVERSIDE,
LOT 7 1.16AC
.J EP 259.36
150' 200'
DIAL
BEFORE

YOU DIG

A PUBLIC SERVICE BY

UNDERGROUND SERVICE ALERT

TWO WORKING

DAYS BEFORE

YOU DIG
NO.
5 EAST, SAN

CALIFORNIA
PLAN
38971

BERNARDINO BASE
(TC261.38) -.

APPROVED
DRAWN BY; DATE:
... .,,_.,_ .... ,APN: 689-090-0'S:ft' ~" _,.,,
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MOBILE HOM &-PA\:.fe (TC.280.25) ""\ (TC260.0J) ""\
LEGEND=
- - -LOT WATERSHEDS
FOR RE~EW PURPOSES ONLY
PHIWP K. FOMOTOR PE., PLS.

R.C.E. NO. 472B4
DATE:

PRELIMINARY

PRELIMINARY HYDROLOGY PLAN
FOIi
TENTATIVE lRACT MAP NO. 38971
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PREPARED BY:
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DATE: 07/09/2024
225 S. CIVIC DRIVE, SUITE 1-5
PALM SPRINGS, CA. 92262
(760) 323-1842 FAX (760) 323-1742

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA
Project Specific
Preliminary Water Quality Management Plan
For: Tentative Tract Map 38971
Located on: Peterson Road, Rancho Mirage, CA 92270
DEVELOPMENT NO. APNs: 689-090-003, 689-130-004, -005, -013, -014, -018 & 689-140-022 DESIGN REVIEW NO. XX-XXX
Prepared for:

Horti Caesaris LLC
9401 Wilshire Blvd., 12th Floor
Beverly Hills, CA 90212-2928
Telephone: 30(210)812-8242
Prepared by:

Phillip Fomotor, PE
Fomotor Engineering
225 S. Civic Drive, Suite 1-5
Palm Springs, CA 92262
Telephone: 760-323-1842
Original Date Prepared: July 9, 2024
Revision Date(s): N/A
472

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024

OWNER'S CERTIFICATION

This project-specific Water Quality Management Plan (WQMP) has been prepared for:

Horti Caesaris LLC
for the project known as: Tentative Tract Map 38971, located on Peterson Road, in the City of Rancho Mirage, County of Riverside, California.

This WQMP is intended to comply with the requirements of The City of Rancho Mirage for the proposed development of an approximately 20.05 acre residential development at: APNs: 689-090-003, 689-130- 004, -005, -013, -014, -018 & 689-140-022, on Peterson Road, in the City of Rancho Mirage, which includes the requirement for the preparation and implementation of a project-specific WQMP.

The undersigned, while owning the property/project described in the preceding paragraph, shall be responsible for the implementation of this WQMP and will ensure that this WQMP is amended as appropriate to reflect up-to-date conditions on the site. This WQMP will be reviewed with the facility operator, facility supervisors, employees, tenants, maintenance and service contractors, or any other party (or parties) having responsibility for implementing portions of this WQMP. At least one copy of this WQMP will be maintained at the project site or project office in perpetuity.

The undersigned is authorized to certify and to approve implementation of this WQMP. The undersigned is aware that implementation of this WQMP is enforceable under City of Rancho Mirage Water Quality Ordinance (Municipal Code Section 7.03.110).

If the undersigned transfers its interest in the subject property/project, the undersigned shall notify the successor in interest of its responsibility to implement this WQMP.

"I, the undersigned, certify under penalty of law that I am the owner of the property that is the subject of this WQMP, and that the provisions of this WQMP have been reviewed and accepted and that the WQMP will be transferred to future successors in interest."

ATTEST
Owner's Signature

Owner's Printed Name

Owner's Title/Position

Date

Peterson Road,
Rancho Mirage, CA 92270
30(210)-812-8242

THIS FORM SHALL BE NOTARIZED BEFORE ACCEPTANCE OF THE

FINAL PROJECT SPECIFIC WQMP

Notary Signature

Printed Name

Title/Position

Date

473

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA
July 9, 2024 1-i
Contents

SECTION PAGE
Contents ....................................................................................................................................................... i I.Project Description ......................................................................................................................... 1 II.Site Characterization ..................................................................................................................... 5 III.Pollutants of Concern..................................................................................................................... 7 IV.Hydrologic Conditions of Concern .............................................................................................. 8 V.Best Management Practices .......................................................................................................... 9 V.1 SITE DESIGN BMP CONCEPTS, LID/SITE DESIGN AND TREATMENT CONTROL BMPS ...... 9 V.1.A SITE DESIGN BMP CONCEPTS AND LID/SITE DESIGN BMPS ................................. 11 V.1.B TREATMENT CONTROL BMPS ................................................................................ 17 V.1.C MEASURABLE GOAL SUMMARY ............................................................................. 19 V.2 SOURCE CONTROL BMPS ................................................................................................. 20 V.3 EQUIVALENT TREATMENT CONTROL BMP ALTERNATIVES ............................................ 23 V.4 REGIONALLY-BASED BMPS ............................................................................................. 23 VI.Operation and Maintenance Responsibility for BMPs .......................................................... 24 VII.Funding .......................................................................................................................................... 26 TABLES
TABLE 1. POLLUTANT OF CONCERN SUMMARY 7
TABLE 2. BMP SELECTION MATRIX BASED UPON POLLUTANT OF CONCERN REMOVAL EFFICIENCY (1) 10 TABLE 3. IMPLEMENTATION OF SITE DESIGN BMP CONCEPTS 12 TABLE 4. LID/SITE DESIGN BMPS MEETING THE LID/SITE DESIGN MEASURABLE GOAL 16 TABLE 5: TREATMENT CONTROL BMP SUMMARY 18
TABLE 6: MEASURABLE GOAL SUMMARY 19
TABLE 7. SOURCE CONTROL BMPS 20

APPENDICES
A.CONDITIONS OF APPROVAL
B.VICINITY MAP, WQMP SITE PLAN, AND RECEIVING WATERS MAP C.SUPPORTING DETAIL RELATED TO HYDROLOGIC CONDITIONS OF CONCERN (IF APPLICABLE) D.EDUCATIONAL MATERIALS
E.SOILS REPORT (IF APPLICABLE)
F.STRUCTURAL BMP AND/OR RETENTION FACILITY SIZING CALCULATIONS AND DESIGN DETAILS G.AGREEMENTS – CC&RS, COVENANT AND AGREEMENTS, BMP MAINTENANCE AGREEMENTS AND/OR

OTHER MECHANISMS FOR ENSURING ONGOING OPERATION, MAINTENANCE, FUNDING AND

TRANSFER OF REQUIREMENTS FOR THIS PROJECT-SPECIFIC WQMP H.PHASE 1 ENVIRONMENTAL SITE ASSESSMENT – SUMMARY OF SITE REMEDIATION CONDUCTED AND

USE RESTRICTIONS
I.PROJECT-SPECIFIC WQMP SUMMARY DATA FORM
474

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-1
I. Project Description

Project Owner:

Horti Caesaris LLC
9401 Wilshire Blvd., 12th Floor
Beverly Hills, CA 90212-2928
Telephone: 30(210)-812-8242
WQMP Preparer: Phillip Fomotor, PE / Fomotor Engineering 225 S. Civic Drive, Suite 1-5
Palm Springs, CA 92262
760-323-1842
Project Site Address: Peterson Road
Rancho Mirage, CA 92270
Planning Area/
Community Name/
Development Name: Tentative Tract Map 38971

APN Number(s): 689-090-003, 689-130-004, -005, -013, -014, -018 & 689-140-022 Latitude & Longitude: 33.765845, -116.438374
Receiving Water: Project Watershed: Whitewater River
Sub-Watershed: N/A
Project Site Size: 20.05 acres
Standard Industrial Classification (SIC) Code: 6513

Formation of Home Owners' Association (HOA)
or Property Owners Association (POA): Y N

475
[Z] □

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-2
Additional Permits/Approvals required for the Project:

AGENCY Permit required
State Department of Fish and Wildlife, Fish and Game
Code §1602 Streambed Alteration Agreement Y N
State Water Resources Control Board, Clean Water Act
(CWA) Section 401 Water Quality Certification Y N
US Army Corps of Engineers, CWA Section 404 permit Y N US Fish and Wildlife, Endangered Species Act Section 7
biological opinion Y N
Statewide Construction General Permit Coverage Y N
Statewide Industrial General Permit Coverage Y N
Other (please list in the space below as required)
City of Rancho Mirage Grading & Building Permits Y N CVWD Permits Y N

476
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Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-3

PROJECT DESCRIPTION
The proposed project consists of a 20.05 acre proposed residential development, which is located on: Peterson Road, in the City of Rancho Mirage, CA.

The 20.05 acre project area (APNs: 689-090-003, 689-130-004, -005, -013, -014, -018 & 689-140-022) on: Peterson Road, in the City of Rancho Mirage, CA is currently vacant.

The now vacant lots (APNs: 689-090-003, 689-130-004, -005, -013, -014, -018 & 689-140-022) are proposed to have new houses with access driveways, individual surface retention basins, and landscaping.

Construction equipment and materials will consist of typical striping, asphalt and concrete construction materials, and associated equipment for installation. All construction equipment and materials will be stored on APNs: 689-090-003, 689-130-004, -005, -013, -014, -018 & 689-140-022.

No hazardous materials will be allowed to be stored on the property.

Appendix A of this project-specific WQMP includes a complete copy of the final Conditions of Approval. Appendix B of this project-specific WQMP includes:
a. A Vicinity Map identifying the project site and surrounding planning areas in sufficient detail; and
b. A Site Plan for the project. The Site Plan included as part of Appendix B depicts the following project features:
◼ Location and identification of all structural BMPs, including Source Control, LID/Site Design and Treatment Control BMPs.
◼ Landscaped areas.
◼ Paved areas and intended uses (i.e., parking, outdoor work area, outdoor material storage area, sidewalks, patios, tennis courts, etc.).
◼ Number and type of structures and intended uses (i.e., buildings, tenant spaces, dwelling units, community facilities such as pools, recreation facilities, tot lots, etc.).
◼ Infrastructure (i.e., streets, storm drains, etc.) that will revert to public agency ownership and operation.
◼ Location of existing and proposed public and private storm drainage facilities (i.e., storm drains, channels, basins, etc.), including catch basins and other inlets/outlet structures. Existing and proposed drainage facilities should be clearly differentiated.
◼ Location(s) of Receiving Waters to which the project directly or indirectly discharges.
◼ Location of points where onsite (or tributary offsite) flows exit the property/project site.
◼ Delineation of proposed drainage area boundaries, including tributary offsite areas, for each location where flows exit the project site and existing site (where existing site flows are required to be addressed). Each tributary area should be clearly denoted.
477

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA
July 9, 2024 1-4
◼Pre- and post-project topography.

Appendix I is a one page form that summarizes pertinent information relative to this project- specific WQMP.
478

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA
July 9, 2024 1-5
II.Site Characterization
Land Use Designation or Zoning: Existing R-E
Proposed R-E
Current Property Use: The parcels are currently vacant.

Proposed Property Use: A new housing development, new access driveways, individual surface retention basins, and landscaping.

Availability of Soils Report: Y N Note: A soils report is required if infiltration BMPs are utilized. Attach report in Appendix E.

Phase 1 Site Assessment: Y N Note: If prepared, attached remediation summary and use restrictions in Appendix H.
479
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Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-6
Receiving Waters for Urban Runoff from Site

Receiving
Waters
EPA Approved
303(d) List
Impairments
Designated
Beneficial Uses
Proximity to RARE
Beneficial Use
Designated Receiving
Waters
Whitewater River
None Listed

MUN, AGR, GWR, REC

I, REC II, WARM,

COLD, POW
N/A
Coachella Valley
Storm Water
Channel
Pathogens,
Toxaphene

FRSH, REC I, REC II,
WARM, WILD, RARE 11 Miles
Salton Sea Salinity, Selenium MUN, AGR 31 Miles

480

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-7
III. Pollutants of Concern
Table 1. Pollutant of Concern Summary

Pollutant Category Potential for Project
and/or Existing Site
Causing Receiving Water
Impairment
Bacteria/Virus Yes Yes
Heavy Metals No No
Nutrients No No
Pesticides Yes No
Toxic Organic Compounds Yes No
Sediment/Turbidity No No
Trash & Debris Yes No
Oxygen Demanding Substances No No
Oil & Grease Yes No
Toxaphene No No
PCBs No No
Dieltrin No No
DDT No No

481

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-8
IV. Hydrologic Conditions of Concern

Local Jurisdiction Requires On-Site Retention of Urban Runoff:

Yes The project will be required to retain urban runoff onsite in conformance with local ordinance (See Table 6 of the WQMP Guidance document, "Local Land use Authorities Requiring Onsite Retention of Stormwater"). This section does not need to be completed; however, retention facility design details and sizing calculations must be included in Appendix F.

No This section must be completed.

This Project meets the following condition:

Condition A: 1) Runoff from the Project is discharged directly to a publicly-owned, operated and maintained MS4 or engineered and maintained channel, 2) the discharge is in full compliance with local land use authority requirements for connections and discharges to the MS4 (including both quality and quantity requirements), 3) the discharge would not significantly impact stream habitat in proximate Receiving Waters, and 4) the discharge is authorized by the local land use authority.

Condition B: The project disturbs less than 1 acre and is not part of a larger common plan of development that exceeds 1 acre of disturbance. The disturbed area calculation must include all disturbances associated with larger plans of development.

Condition C: The project's runoff flow rate, volume, velocity and duration for the post-development condition do not exceed the pre-development condition for the 2- year, 24-hour and 10-year 24-hour rainfall events. This condition can be achieved by, where applicable, complying with the local land use authority's on-site retention ordinance, or minimizing impervious area on a site and incorporating other Site- Design BMP concepts and LID/Site Design BMPs that assure non-exceedance of pre-development conditions. This condition must be substantiated by hydrologic modeling methods acceptable to the local land use authority.

None: Refer to Section 3.4 of the Whitewater River Region WQMP Guidance document for additional requirements.

Supporting engineering studies, calculations, and reports are included in Appendix C. 2 year – 24 hour 10 year – 24 hour
Precondition Post-condition Precondition Post-condition Discharge (cfs)
Velocity (fps)
Volume (cubic
feet)
Duration (minutes)
482
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Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-9
V. Best Management Practices

This project implements Best Management Practices (BMPs) to address the Pollutants of Concern that may potentially be generated from the use of the project site. These BMPs have been selected and implemented to comply with Section 3.5 of the WQMP Guidance document, and consist of Site Design BMP concepts, Source Control, LID/Site Design and, if/where necessary, Treatment Control BMPs as described herein.

V.1 SITE DESIGN BMP CONCEPTS, LID/SITE DESIGN AND TREATMENT

CONTROL BMPS
Local Jurisdiction Requires On-Site Retention of Urban Runoff:

Yes The project will be required to retain Urban Runoff onsite in conformance with local ordinance (See Table 6 of the WQMP Guidance document, "Local Land use Authorities Requiring Onsite Retention of Stormwater). The LID/Site Design measurable goal has thus been met (100%), and Sections V.1.A and V.1.B do not need to be completed; however, retention facility design details and sizing calculations must be included in Appendix F, and '100%' should be entered into Column 3 of Table 6 below.

No Section V.1 must be completed.

This section of the Project-Specific WQMP documents the LID/Site Design BMPs and, if/where necessary, the Treatment Control BMPs that will be implemented on the project to meet the requirements detailed within Section 3.5.1 of the WQMP Guidance document. Section 3.5.1 includes requirements to implement Site Design Concepts and BMPs, and includes requirements to address Pollutants of Concern with BMPs. Further, sub-section 3.5.1.1 specifically requires that Pollutants of Concern be addressed with LID/Site Design BMPs to the extent feasible.

LID/Site Design BMPs are those BMPs listed within Table 2 below which promote retention and/or feature a natural treatment mechanism; off-site and regionally-based BMPs are also LID/Site Design BMPs, and therefore count towards the measurable goal, if they fit these criteria.

This project incorporates LID/Site Design BMPs to fully address the Treatment Control BMP requirement where and to the extent feasible. If and where it has been acceptably demonstrated to the local land use authority that it is infeasible to fully meet this requirement with LID/Site Design BMPs, Section V.1.B (below) includes a description of the conventional Treatment Control BMPs that will be substituted to meet the same requirements.

In addressing Pollutants of Concern, BMPs are selected using Table 2 below. 483
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Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA
July 9, 2024 1-10
Table 2. BMP Selection Matrix Based Upon Pollutant of Concern Removal Efficiency (1) (Sources: Riverside County Flood Control & Water Conservation District Design Handbook for Low Impact Development Best Management Practices, dated September 2011, the Orange County Technical Guidance Document for Water Quality Management Plans, dated May 19, 2011, and the Caltrans Treatment BMP Technology Report, dated April 2010 and April 2008)
Pollutant of
Concern
Lan
d
s
c
a
p
e

S
w
a
l
e
2, 3
Lan
d
s
c
a
p
e

S
t
r
i
p
2, 3
Bio
f
iltra
t
i
o
n

(wit
h

u
n
d
e
r
d
r
a
i
n
)2, 3
Ext
e
n
d
e
d

D
e
t
e
n
t
i
o
n

Ba
s
i
n
2 Sa
n
d

F
i
l
t
e
r
Ba
s
i
n
2 Infi
l
t
r
a
t
i
o
n

B
a
s
i
n
2 Infi
l
t
r
a
t
i
o
n

T
r
e
n
c
h
2 Pe
r
m
e
a
b
l
e

Pa
v
e
m
e
n
t
2 Bio
r
ete
n
t
i
o
n

(w/o

und
e
r
d
r
a
i
n
)2, 3
Oth
e
r

B
M
P
s

I
n
c
l
u
d
i
n
g

Pro
p
r
i
e
t
a
r
y

B
M
P
s
4, 6

Sediment &
Turbidity M M H M H H H H H
Va
r
i
e
s

b
y

P
r
o
d
u
c
t
5 Nutrients L/M L/M M L/M L/M H H H H
Toxic Organic
Compounds M/H M/H M/H L L/M H H H H
Trash & Debris L L H H H H H L H
Bacteria & Viruses
(also: Pathogens) L M H L M H H H H
Oil & Grease M M H M H H H H H
Heavy Metals M M/H M/H L/M M H H H H
Abbreviations:

L: Low removal efficiency M: Medium removal efficiency H: High removal efficiency Notes:
(1)Periodic performance assessment and updating of the guidance provided by this table may be necessary. (2)Expected performance when designed in accordance with the most current edition of the document, "Riverside County, Whitewater River Region Stormwater Quality Best Management Practice Design Handbook". (3)Performance dependent upon design which includes implementation of thick vegetative cover. Local water conservation and/or landscaping requirements should be considered; approval is based on the discretion of the local land use authority.
(4)Includes proprietary stormwater treatment devices as listed in the CASQA Stormwater Best Management Practices Handbooks, other stormwater treatment BMPs not specifically listed in this WQMP (including proprietary filters, hydrodynamic separators, inserts, etc.), or newly developed/emerging stormwater treatment technologies. (5) Expected performance should be based on evaluation of unit processes provided by BMP and available testing data. Approval is based on the discretion of the local land use authority. (6)When used for primary treatment as opposed to pre-treatment, requires site-specific approval by the local land use authority.
484
I
I
I
I
I
I
I
-

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-11
V.1.A SITE DESIGN BMP CONCEPTS AND LID/SITE DESIGN BMPS

This section documents the Site Design BMP concepts and LID/Site Design BMPs that will be implemented on this project to comply with the requirements detailed in Section 3.5.1 of the WQMP Guidance document.
• Table 3 herein documents the implementation of the Site Design BMP Concepts described in sub-sections 3.5.1.3 and 3.5.1.4.
• Table 4 herein documents the extent to which this project has implemented the LID/Site Design goals described in sub-section 3.5.1.1.

485

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486
□ □ □ □ □ □ □ □ □ □ □ □
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Jul
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9 , 20
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a
r
a
b
l
e

a
n
d

e
q
u
a
l
l
y

e
f
f
e
c
t
i
v
e

S
i
t
e

D
e
s
i
g
n

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M
P

c
o
n
c
e
p
t
(
s
)

as
a
p
p
r
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d

b
y

t
h
e

loc
a
l

l
a
n
d

u
s
e

a
u
t
h
o
r
i
t
y
(No
t
e
:

A
d
d
i
t
i
o
n
a
l

n
a
r
r
a
t
i
v
e

req
u
i
r
e
d

t
o

d
e
s
c
r
i
b
e

B
M
P

a
n
d

h
o
w

i
t

a
d
d
r
e
s
s
e
s

s
i
t
e

d
e
s
i
g
n

c
o
n
c
e
p
t
)
.

Us
e

o
n
e

o
r

m
o
r
e

o
f

t
h
e

f
o
l
l
o
w
i
n
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f
o
r

d
e
s
i
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n

o
f

d
r
i
v
e
w
a
y
s

a
n
d

pri
v
a
t
e

r
e
s
i
d
e
n
t
i
a
l

p
a
r
k
i
n
g

a
r
e
a
s
:

De
s
i
g
n

d
r
i
v
e
w
a
y
s

w
i
t
h

s
h
a
r
e
d

a
c
c
e
s
s
,

f
l
a
r
e
d

(
s
i
n
g
l
e

l
a
n
e

a
t

s
t
r
e
e
t
)
,

o
r

wh
e
e
l

s
t
r
i
p
s

(
p
a
v
i
n
g

o
n
l
y

u
n
d
e
r

t
h
e

t
i
r
e
s
)
.

Un
c
o
v
e
r
e
d

t
e
m
p
o
r
a
r
y

o
r

g
u
e
s
t

p
a
r
k
i
n
g

o
n

r
e
s
i
d
e
n
t
i
a
l

l
o
t
s

p
a
v
e
d

w
i
t
h

per
m
e
a
b
l
e

s
u
r
f
a
c
e
,

o
r

d
e
s
i
g
n
e
d

t
o

d
r
a
i
n

i
n
t
o

l
a
n
d
s
c
a
p
i
n
g
.

487
□ □ □ □ □ □ □ □ □ □ □ □
□ □ □ □ □ □ □ □ □ □ □ □
□ □ □ □ □ □ □ □ □ □ □ □

Wh
i
t
e
w
a
t
e
r

R
i
v
e
r

R
e
g
i
o
n

W
Q
M
P

TTM
3 8
97 1
-Ra
n
c
h
o

M
i
r
a
ge
, C
A

Jul
y

9 , 20
2 4
1-14
Ta
b
l
e

3 .

S
i
t
e

D
e
s
i
g
n

B
M
P
Co
n
c
e
p
t
s (c
o
n
t
i
n
u
e
d
)

Inc
l
u
d
e
d

Br
i
e
f

R
e
a
s
o
n

f
o
r

E
a
c
h

B
M
P

Ind
i
c
a
t
e
d

a
s

N
o

o
r

N
/
A

De
s
i
g
n

Co
n
c
e
p
t

Te
c
h
n
i
q
u
e

Sp
e
c
i
f
i
c

B
M
P

Ye
s

N/A

Site Design BMP Concept 2
(cont'd)

Mi
n
i
m
i
z
e

Dir
e
c
t
l
y

Co
n
n
e
c
t
e
d

Im
p
e
r
v
i
o
u
s

Ar
e
a

(Se
e

W
Q
M
P

Sec
t
i
o
n

3.5 .
1 .
4 )

Oth
e
r

c
o
m
p
a
r
a
b
l
e

a
n
d

e
q
u
a
l
l
y

e
f
f
e
c
t
i
v
e

S
i
t
e

D
e
s
i
g
n

B
M
P

c
o
n
c
e
p
t
(
s
)

as
a
p
p
r
o
v
e
d

b
y

t
h
e

loc
a
l

l
a
n
d

u
s
e

a
u
t
h
o
r
i
t
y
(No
t
e
:

A
d
d
i
t
i
o
n
a
l

n
a
r
r
a
t
i
v
e

req
u
i
r
e
d

t
o

d
e
s
c
r
i
b
e

B
M
P

a
n
d

h
o
w

i
t

a
d
d
r
e
s
s
e
s

s
i
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e

d
e
s
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c
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e
p
t
)
.

Us
e

o
n
e

o
r

m
o
r
e

o
f

t
h
e

fol
l
o
w
i
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g

f
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r

d
e
s
i
g
n

o
f

p
a
r
k
i
n
g

a
r
e
a
s
:

Wh
e
r
e

l
a
n
d
s
c
a
p
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n
g

i
s

p
r
o
p
o
s
e
d

i
n

p
a
r
k
i
n
g

a
r
e
a
s
,

i
n
c
o
r
p
o
r
a
t
e

p
a
r
k
i
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g

are
a

l
a
n
d
s
c
a
p
i
n
g

i
n
t
o

t
h
e

d
r
a
i
n
a
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e

d
e
s
i
g
n
.

Ov
e
r
f
l
o
w

p
a
r
k
i
n
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(
p
a
r
k
i
n
g

s
t
a
l
l
s

p
r
o
v
i
d
e
d

i
n

e
x
c
e
s
s

o
f

t
h
e

P
e
r
m
i
t
t
e
e
's
min
i
m
u
m

p
a
r
k
i
n
g

r
e
q
u
i
r
e
m
e
n
t
s
)

m
a
y

b
e

c
o
n
s
t
r
u
c
t
e
d

w
i
t
h

p
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r
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a
b
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pav
e
m
e
n
t
.

Oth
e
r

c
o
m
p
a
r
a
b
l
e

a
n
d

e
q
u
a
l
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y

e
f
f
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c
t
i
v
e

S
i
t
e

D
e
s
i
g
n

B
M
P

(
o
r

B
M
P
s
)

as
a
p
p
r
o
v
e
d

b
y

t
h
e

loc
a
l

l
a
n
d

u
s
e

a
u
t
h
o
r
i
t
y
(No
t
e
:

A
d
d
i
t
i
o
n
a
l

n
a
r
r
a
t
i
v
e

req
u
i
r
e
d

d
e
s
c
r
i
b
i
n
g

B
M
P

a
n
d

h
o
w

i
t

a
d
d
r
e
s
s
e
s

s
i
t
e

d
e
s
i
g
n

c
o
n
c
e
p
t
)
.

488
□ □ □ □
□ □ □ □
□ □ □ □

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-15
Project Site Design BMP Concepts:
n/a

Alternative Project Site Design BMP Concepts:
n/a

489

Wh
i
t
e
w
a
t
e
r

R
i
v
e
r

Re
g
i
o
n

W
Q
M
P

TTM
3 8
97 1
-Ra
n
c
h
o

M
i
r
a
ge
, C
A

July

9 , 20
2 4
1-16
Ta
b
l
e

4. LID
/
Sit
e

D
e
s
i
g
n

B
M
P
s

Me
e
t
i
n
g

t
h
e

LID
/
S
i
t
e

D
e
s
i
g
n

Me
a
s
u
r
a
b
l
e

G
o
a
l

(1)

(2)

(3)

(4)

(5)

(6)

(7)

DR
A
I
N
A
G
E

SU
B
-AR
E
A

O
R

N
O
.

LID
/
S
I
T
E

D
E
S
I
G
N

B
M
P

TY
P
E
*
PO
T
E
N
T
I
A
L

P
O
L
L
U
T
A
N
T
S

C
O
N
C
E
R
N

W
I
T
H
I
N

DR
A
I
N
A
G
E

S
U
B
-AR
E
A

PO
T
E
N
T
I
A
L

PO
L
L
U
T
A
N
T
S

WI
T
H
I
N

S
U
B
-
AR
E
A

C
A
U
S
I
N
G

RE
C
E
I
V
I
N
G

WA
T
E
R

IM
P
A
I
R
M
E
N
T
S

EF
F
E
C
T
I
V
E
N
E
S
S

L
I
D
/
S
I
T
E

DE
S
I
G
N

B
M
P

A
T

AD
D
R
E
S
S
I
N
G

ID
E
N
T
I
F
I
E
D

PO
T
E
N
T
I
A
L

PO
L
L
U
T
A
N
T
S

BM
P

M
E
E
T
S

WH
I
C
H

DE
S
I
G
N

CR
I
T
E
R
I
A
?

TO
T
A
L

AR
E
A

WI
T
H
I
N

DR
A
I
N
A
G
E

SU
B
-AR
E
A

(Se
e

T
a
b
l
e

2 )

(Refe
r

t
o

T
a
b
l
e

1 )

(Refe
r

t
o

T
a
b
l
e

1 )

(U,

L
,

M
,

H
/
M
,

H
;

s
e
e

Tab
l
e

2 )

(Iden
t
i
f
y

a
s

VBM
P
OR

QBM
P
)
(Near
e
s
t

0 .
1 a
c
r
e
)

TO
T
A
L

P
R
O
J
E
C
T

A
R
E
A

T
R
E
A
T
E
D

W
I
T
H

L
I
D
/
S
I
T
E

D
E
S
I
G
N

B
M
P
s (NE
A
R
E
S
T

0 .
1 A
C
R
E
)

20. 1

* LID
/
S
i
t
e

D
e
s
i
g
n

B
M
P
s

l
i
s
t
e
d

i
n

t
h
i
s

t
a
b
l
e

a
r
e

t
h
o
s
e

t
h
a
t

com
p
l
e
t
e
l
y
add
r
e
s
s

t
h
e

'Tr
e
a
t
m
e
n
t

C
o
n
t
r
o
l

B
M
P

r
e
q
u
i
r
e
m
e
n
t
' for

t
h
e
i
r

dra
i
n
a
g
e

s
u
b
-are
a
.
490

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-17
Justification of infeasibility for sub-areas not addressed with LID/Site Design BMPs n/a

V.1.B TREATMENT CONTROL BMPS
Conventional Treatment Control BMPs shall be implemented to address the project's Pollutants of Concern as required in WQMP Section 3.5.1 where, and to the extent that, Section V.1.A has demonstrated that it is infeasible to meet these requirements through implementation of LID/Site Design BMPs.

The LID/Site Design BMPs described in Section V.1.A of this project-specific WQMP completely address the 'Treatment Control BMP requirement' for the entire project site (and where applicable, entire existing site) as required in Section 3.5.1.1 of the WQMP Guidance document. Supporting documentation for the sizing of these LID/Site Design BMPs is included in Appendix F. *Section V.1.B does not need to be completed.

The LID/Site Design BMPs described in Section V.1.A of this project-specific WQMP do NOT completely address the 'Treatment Control BMP requirement' for the entire project site (or where applicable, entire existing site) as required in Section 3.5.1.1 of the WQMP. *Section V.1.B must be completed.

The Treatment Control BMPs identified in this section are selected, sized and implemented to treat the design criteria of VBMP and/or QBMP for all project (and if required, existing site) drainage sub- areas which were not fully addressed using LID/Site Design BMPs. Supporting documentation for the sizing of these Treatment Control BMPs is included in Appendix F.

491
□

Wh
i
t
e
w
a
t
e
r

R
i
v
e
r

R
e
g
i
o
n

W
Q
M
P

TTM
3 8
97 1
-Ra
n
c
h
o

M
i
r
a
ge
, C
A

Jul
y

9 , 20
2 4
1-18
Ta
b
l
e

5: Tr
e
a
t
m
e
n
t

C
o
n
t
r
o
l

BM
P

Su
m
m
a
r
y

(1)

(2)

(3)

(4)
(5)
(6)
(7)
DR
A
I
N
A
G
E

SU
B
-AR
E
A

O
R

N
O
.

TR
E
A
T
M
E
N
T

CO
N
T
R
O
L

B
M
P

TY
P
E
*
PO
T
E
N
T
I
A
L

PO
L
L
U
T
A
N
T
S

O
F

CO
N
C
E
R
N

W
I
T
H
I
N

DR
A
I
N
A
G
E

S
U
B
-AR
E
A

PO
T
E
N
T
I
A
L

PO
L
L
U
T
A
N
T
S

WI
T
H
I
N

S
U
B
-AR
E
A

CA
U
S
I
N
G

RE
C
E
I
V
I
N
G

WA
T
E
R

IM
P
A
I
R
M
E
N
T
S

EF
F
E
C
T
I
V
E
N
E
S
S

O
F

TR
E
A
T
M
E
N
T

CO
N
T
R
O
L

B
M
P

A
T

AD
D
R
E
S
S
I
N
G

ID
E
N
T
I
F
I
E
D

PO
T
E
N
T
I
A
L

PO
L
L
U
T
A
N
T
S

BM
P

M
E
E
T
S

WH
I
C
H

DE
S
I
G
N

CR
I
T
E
R
I
A
?

TO
T
A
L

AR
E
A

WI
T
H
I
N

DR
A
I
N
A
G
E

SU
B
-AR
E
A

(Se
e

T
a
b
l
e

2 )

(Re
f
e
r

t
o

T
a
b
l
e

1 )

(Re
f
e
r

t
o

T
a
b
l
e

1 )

(U,

L
,

M
,

H
/
M
,

H
; se
e

T
a
b
l
e

2)
(Ide
n
t
i
f
y

a
s

VBM
P
OR
QBM
P
)
(Ne
a
r
e
s
t

0 .
1 acr
e
)

TO
T
A
L

PR
O
J
E
C
T

AR
E
A

T
R
E
A
T
E
D

W
I
T
H

T
R
E
A
T
M
E
N
T

C
O
N
T
R
O
L

B
M
P
s (NE
A
R
E
S
T

0 .
1 A
C
R
E
)

20. 1

492

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-19

V.1.C MEASURABLE GOAL SUMMARY
This section documents the extent to which this project has met the measurable goal described in WQMP Section 3.5.1.1 of addressing 100% of the project's 'Treatment Control BMP requirement' with LID/Site Design BMPs. Projects required to retain Urban Runoff onsite in conformance with local ordinance are considered to have met the measurable goal; for these instances, '100%' is entered into Column 3 of the Table.

Table 6: Measurable Goal Summary
(1) (2) (3)
Total Area Treated with
LID/Site Design BMPs
Total Area Treated with
Treatment Control BMPs % of Treatment Control BMP
Requirement addressed with
LID/Site Design BMPs (Last row of Table 4) (Last row of Table 5)

20.05AC 0 100%

493

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-20
V.2 SOURCE CONTROL BMPS

This section identifies and describes the Source Control BMPs applicable and implemented on this project.

Table 7. Source Control BMPs
BMP Name
Check One If not applicable, state
brief reason Included Not
Applicable
Non-Structural Source Control BMPs
Education for Property Owners, Operators,
Tenants, Occupants, or Employees
Activity Restrictions
Irrigation System and Landscape Maintenance
Common Area Litter Control N/A
Street Sweeping Private Streets and Parking Lots
Drainage Facility Inspection and Maintenance
Structural Source Control BMPs
Storm Drain Inlet Stenciling and Signage
Landscape and Irrigation System Design
Protect Slopes and Channels N/A
Provide Community Car Wash Racks N/A
Properly Design*:

Fueling Areas N/A
Air/Water Supply Area Drainage N/A
Trash Storage Areas N/A
Loading Docks N/A
Maintenance Bays N/A
Vehicle and Equipment Wash Areas N/A
Outdoor Material Storage Areas N/A
Outdoor Work Areas or Processing Areas N/A
Provide Wash Water Controls for Food
Preparation Areas N/A
*Details demonstrating proper design must be included in Appendix F. 494
igJ □
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Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA
July 9, 2024 1-21
Non-Structural Source Control BMPs
Education for Property Owners, Operators, or Employees
Practical informational materials to promote the prevention of Urban Runoff pollution is to be provided by the project proponent to the site occupants/tenants. These materials shall include general housekeeping practices that contribute to the protection of Urban Runoff quality and BMP’s that eliminate or reduce pollution during subsequent property improvements. These materials can be obtained from the Permittee or at www.floodcontrol.co.riverside.ca.us/stormwater/
For employees and contractors maintaining the landscape and drainage facilities, BMP training and education programs must be provided by the HOA to all new employees within 6 months of hire date and annually thereafter. Employee training materials may be derived from educational materials available through the Permittee or from resources such as “Stormwater Best Management Practices Handbook for Industrial and Commerical” (CASQA, 2003). The most recent editions of the CASQA handbooks can be downloaded at www.cabmphandbooks.com .

Activity Restrictions
The HOA shall implement the following restrictions for the purpose of receiving water quality protection.

The restrictions to be included therein shall include:
•Prohibiting the blowing, sweeping, or hosing of debris into streets, storm drain inlets or other conveyances.
•Require trash can and dumpster lids be closed at all times. •Prohibit vehicle washing, maintenance, or repair within the project.

Irrigation System and Landscape Maintenance
•Maintenance of irrigation systems and landscaping shall be consistent with the Permittee’s water conservation ordinance.
•Fertilizer and pesticide usage shall be consistent with the instructions contained on product labels and with regulations administered by California’s Department of Pesticide Regulation. •Provide regular landscape maintenance, including replacement of dead vegetation, repair of erosion rills, proper disposal of green waste.
•Provide regular irrigation system maintenance, including periodic testing and observation of the irrigation system to detect overspray, broken sprinkler heads, and other system failures. •Provide weekly irrigation system and landscape area maintenance. •Responsible party is the HOA for all areas.

Parking Lot Sweeping
•Private parking areas shall be swept at least quarterly, including just prior to the start of the rainy season (October 1st). The HOA is responsible for conducting the periodic sweeping.

Drainage Facility Inspection and Maintenance
•Routine maintenance of the privately owned on-site drainage facilities, including parking lot catch basins, storm drains, and retention systems, at a minimum shall take place in the late summer or early fall prior to the rainy season (October 1st). The drainage facilities must be cleaned if accumulated sediment/debris fills 25% or more of the sediment/debris storage capacity. Drainage facilities shall be inspected annually by the HOA and cleaning frequency shall be assessed. 495

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-22
Structural Source Control BMPs
Storm Drain Inlet Stenciling and Signage
• Provide stenciling or labeling of all storm drain inlets and catch basins, constructed or modified, within the project area with prohibitive language (such as “NO DUMPING ONLY RAIN IN THE DRAIN”) and/or graphical icons to discourage illegal dumping. • The HOA is responsible for maintaining legibility of stencils and signs.

Landscape and Irrigation System Design
Final Project Landscape and Irrigation System Design plans are to employ rain shutoff devices to prevent irrigation during and after precipitation events.

Irrigation system to be designed for each landscape area’s specific water requirements.

Use flow reducers or shutoff valves triggered by a pressure drop to control water loss due to broken sprinkler heads or lines.

The timing and application methods of irrigation water shall be designed to minimize the runoff of excess irrigation water into streets and storm drain catch basins.

Comply with Coachella Valley Water Agency and City of Rancho Mirage water conservation ordinances.

Final Landscape plans to:
• Utilize plants with similar water requirements, group plants with similar water requirements in order to reduce excess irrigation runoff and promote surface infiltration. • Use mulches in planter areas without ground cover to minimize sediment in runoff. • Install appropriate plant materials for the location, in accordance with amount of sunlight and climate, and use native plant material where possible.
• Choose plants that minimize or eliminate the use of fertilizer or pesticides to sustain growth.

Source-Control BMPS Not Required
There are no slopes or channels that will require protection. Community Car Wash Racks will not be necessary for this facility.

Appendix D includes copies of the educational materials (described in Section 3.5.2.1 of the WQMP Guidance document) that will be used in implementing this project-specific WQMP.

496

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-23
V.3 EQUIVALENT TREATMENT CONTROL BMP ALTERNATIVES
N/A

V.4 REGIONALLY-BASED BMPS
N/A
497

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-24
VI. Operation and Maintenance Responsibility for
BMPs

Appendix G of this project-specific WQMP includes copies of CC&Rs, Covenant and Agreements, BMP Maintenance Agreement and/or other mechanisms used to ensure the ongoing operation, maintenance, funding, transfer and implementation of the project-specific WQMP requirements.

BMP Operation and
Maintenance
Activities
BMP Start
Date
Frequency Parties
Responsible
Records
Education for
HOA, and
Employees
Educational
materials are
included in this
WQMP
At the
completion
of project
To HOA and
Employees at
the time of
occupancy.

To all new
employees and
contractors
within 6
months of hire
date and
annually
thereafter
HOA Records of
distribution and
implementation
of education
materials shall
be kept by the
HOA.

Activity
Restrictions
As outlined in this
WQMP
For HOA
and
employees
Ongoing HOA N/A
Irrigation
System and
Landscape
Maintenance
Inspect
landscaping and
irrigation systems
and repair/replace
if needed
At the
completion
of project
The
landscaping
and irrigation
systems shall
be monitored
monthly
HOA Records of
Irrigation
System and
Landscape
Maintenance
shall be kept by
the HOA.

Sweeping
Parking Lots
Sweep onsite
parking lot areas
At the
completion
of project
At least
quarterly,
including just
prior to the start
of the rainy
season
(October 1st).

HOA N/A
Drainage
Facility
Routine
maintenance,
including parking
At the
completion
of project
Maintenance
annually as a
minimum, just
HOA Records of
Drainage
Facility
498

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-25
Inspection and
Maintenance
lot catch basins,
storm drains, and
retention systems,
cleaned if
accumulated
sediment/debris
fills 25% or more
of the
sediment/debris
storage capacity in
the upper chamber
prior to the
rainy season
(October 1st).

Inspect
annually and
cleaning
frequency to be
assessed.

Inspect after a
rain event
Inspection and
Maintenance
shall be kept by
the HOA.

Storm Drain
Inlet Stenciling
and Signage
maintain legibility
of stencils and
signs
At the
completion
of project
Inspect
annually

HOA N/A
Landscape and
Irrigation
System Design
Maintain
Landscape and
Irrigation system
in accordance with
the original design
At the
completion
of project
Inspect and
maintain
weekly

HOA N/A

499

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

July 9, 2024 1-26
VII. Funding

The HOA is responsible for funding the operation and maintenance of the BMP’s outlined in this report

500

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

Appendix A
Conditions of Approval

To be added when available.
501

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA

Appendix B
WQMP Site Plan, and Receiving Waters Map
502

FOMOTOR ENGINEERING
TENTATIVE TRACT MAP NO. 38971
503
-" \ \, 11 I -" ) I r";"'«P258.33) r (EP258.51)
'"I-'(
(TC/~">7.65) I f---+--+--.'-::'-= ---------
0c;FS {57 .5o)
J
v\
I I
'-J
""'·
OWNER:

ED BRYANT
'
I
I MP 8> PROPOSE D/ (~
\ RETENTION BASIN Q_EP
1 '4£U TO . 1/SI\JE.,_ SL()I S
SEE PREb!M. ~JITTll,b G
REPORT FOR p 7;111L-Sr , \ (. I 1-tOT <> -
\42480 SOFT.

I '0,98 AC. "I
r -PAIX:259.3
,_}
r,,,d'-:% I
'L
' t "
o\ Ct_~'-/~ ~ '°'
-~ ::::7 l J""'"'j' I r -:.1,' ,-\. .,, I \
, ~~ -~ _ --... , ).. I , t
' "'"V ',, 1 L--0

ANY STORM WATER BASIN OVERFLOW FROM THE SITE WOULD INFILTRATE OR BE

CONVEYED EVENTUALLY TO THE WHITEWATER RIVER/ COACHELLA VALLEY STORM WATER CHANNEL COLLECTOR.

ENGINEER:
225 S, CIVIC DRIVE, SUITE 1-5
PALM SPRINGS, CA. 92262
(760) 323-1842 FAX (760) 323-1742
~
.-----~R:

MOBILE ~&-1'A61',
0 7 7m
PREPARED UNDER THE DIRECT SUPERVISION OF:

PHIi/iP K FOMOTOR P.£ Pl S: __ DATE
R.CE __ 47284_EXP.

YIGIN[[Y MAP
N.T.S.
11 ACREAGE:

GROSS: ±20.05 ACRES
ABBREVIATIONS:

EXIST
PL
RW
BMP
APN
REQ'D
CB
SD

EXISTING

PROPERTY LINE

RIGHT OF WAY

BEST MANAGEMENT PRACTICE

ASSESSOR'S PARCEL NUMBER

REQUIRED

CATCH BASIN

STORM DRAIN

OVERFLOW WATER WOULD INFILTRATE

INTO THE BASIN OR

EVENTUALLY FLOW INTO THE

WHITEWATER RIVER/COACHELLA VALLEY

STORM WATER CHANNEL RECEIVING
WATER COLLECTOR.

FRANK SINATRA RD
0: Q Q
0: Q
0 "' I Q
£i 0 z
0 0
~ ~ ,i "i "' u "' z

MIRAGE COVE RD
WQMP LEGEND:
-----
I I I I I I I 1111 I I I I 11
b{8::8::8::8::8

VICINITY AND RECEIVING WATER MAP

ONSITE STORM WATER FLOW DIRECTION

OFFSITE STORM WATER FLOW DIRECTION

ONSITE TRIBUTARY AREA BOUNDARY
INDICATES NEW LANDSCAPED AREAS-APPX. 80% OF EACH LOT
INDICATES NEW AC PAVEMENT/CONCRETE/IMPERMEABLE AREAS-45,304 S.F.

LEGEND
IS£!
-(i_--
--(10)--

BOUNDARY

LOT LINE / RIGHT OF WAY

PROPOSED STORM DRAIN

CENTERLINE

EXISTING CONTOUR
- - - - - - - - - - -WATERSHED BOUNDARY
PREPARED 07-09-2024

CITY OF CATHEDRAL CITY

PROJECT

DESCRIPTION PRELIMINARY WQMP SITE
FOR
TENTATIVE TRACT MAP NO.

PL.AN
38971
SHEET 1
OF 1
PRIVATE REFERENCE#
CITY REFERENCE #

Whitewater River Region WQMP Guidance

June 2014 10
Figure 2. Whitewater River Region Receiving Waters Map
504
I
1,'
" I

BROWN CREEK
D WHITEWATER MS4 PERMfT BOUNDARY
c::J WHITEWATER RIVER WATERSHED BOUNDARY
~ RECEIVING WATERS -LINES
.. RECEIVING WATERS -POLYS
t::lll COUNTY BOUNDARY
-.,-,... ........ ,..._ __ ,

BIG MORONGO CREEK
•• ~lit
I I

WEST MAGNESIA CANYON CHANNEL
I l
PALM VALLEY STORMT ER C?EI.

GRAPEVINE,CA ~
CARRIZO CREEK ·
r-~••-• •~-c-

EDRAL CANYON CHANNEL
RAr CANYON CHANNEL
17 IA CANYON CHANNEL
HANNEL

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA
Appendix C
Supporting Detail Related to Hydrologic Conditions of Concern See App. “F” For Hydrology Study and BMP sizing calculations

NOT APPLICABLE
505

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA
Appendix D
Educational Materials
506

        

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             













 


 

 


 



 


 





 
 
  




 




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
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
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



 




507
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O@ ootj 0W w~ere street ~ows actually 90?

    
     


    



     


 
     
  








    

  




 








 







  

     
   
 
     
  
   




 
 

  
     
  
 
  


  

 
    



  

  
 





 





     
    


 

   
    

  









 



  
 
  
 

 
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HIJl/l l1itJIIJCI OU/! WattJrways!

  

  


   

 




 


 


 


 











  




 

  

  
    

 


 

 






 

    

      





 
  
     
   




   

 

 






509


    
 
  

   

 
  

  

   
 


    
 
 
     

 
 




   

  
  


    

      

 
  


 

 
  


 

    



   
    
   





   


  

 
  

  



 
 



   
    

  

    

   



 
 



 

    
 

  







   
 
510

511
11e111o1 telephone numbers and linkS:

R IV ERSIDE C OUNTY WATER A GEN CIES :

Cily 01 aanrlnn
Ci1y ol Beaumonl
c,1v 01 SIYlhe
City of Coachella
Cc<>cholla ¼llov Wa101· Dlslrlct
Cily of •:orona
Desan Cenir.r. CSA 161
Ees1ern Municiµ•I Wiler Oistricl
Elsmore Val c y MWD
Farm Mutual W8'.er Compa,w
Ci!_yofl--lc.m~t
ldyllw,I4 Wa:er Olstrlcl
Ju1.1pa Community Services 01s1rlct
l..,ke Hornet MWD
Lee Lake Wn ter 01!.trict
March Air Force 3ase
Mlsslor SprintJ5 'Nater Oist.rict
Ci1y or Palm Spmg•
R:inr..M C,qh;:iltem
Rancho Califomio W.:tcr Oislnct
Rlpl~y. CSA #62
Cily ol Riverside
Rt1hlrln nc C~rnunhy $.e,~lc-,e~ 01~rrlr1
S~ant Valley Club. Inc
Vall~y Sanit3ry C-.s lnc:t
W0$18fl\ Mt>1leJpel Waler o,sir,~
Y1r.Alr,1' \/AtlAy WAIAr0iRhlr.t
CALL 1-800-506 -2555 to :
051)022-313(
(~51 J 769-852(
(760)922-6161
(760) 395-350;
(760\ 308-2651
(951) 736•225£
(760!227-320~
(951 928-3777
im1~~~~;i~
NS1!'l65-371~
(351 659-214~
(951 360-879E
(951) 658-(1241
(951)277-1414
(951!656-700C 760 32!1-644E
!1ao 323-825~
(•~fi1) 7R0"1?7,
(951) 296-890C
(raol 922-4951 (951 351-617(
(9~ 1 684.75.(1(
(951 849-4501
(160J3d7-235E
(951) 789-600(
(~M)7A7,!\117
Repon cogged slorm dtalns or !lk,g,I sll>rm dmlr di,,flO"..al fmn rocJ
•~e.is, •IDO'n drl!ini ;1J1d'Or water tx,die,.

FtndOUI fl>OUI our Y!lrk>US SlOfm CJ'Jifl pc,IIUtlon J)(elOOliOn matefl(IS Loc,ll) 11-c da:os and l!m!tS ol HOU$Gh0k1 Hal/Wd011$ war.to (~HW) C~lor Event.
f°?l?ql lesl wJolt neiglborhood, orclnsrc:om p,nettlatk'Yl1'.

Loc.r~e other C:x.tn.t)' ~nvronmcn1aJSOM;eS
Receive urasscyc;11ng 1nrcrmafo,, aod cumpos.1119 worlsnop l'lfon,aticn.

Or vlsK our (Riversi:le County FloOd Conuol 0lstrcl webslle at ~~on1roI.co,riversl(le.ca .u$
Other links to additional storm drain pollution inlcrmatlon:

Cnt1,1y ti RivA,siM: Frvironn1e:n1~1 .,.~ltt
~•t Q.rg
Qltllomil; StAle 'Witl.;tr RQ.sc,urce Conserv;itlon Boord· ~tcb,CJ!,!,/OY/islormw1rn1nls.h1n1I
C~Ulomlo W3:@t Cuahty T:isk Force:

WWW C{lbOlD')80dboQkS conv
Unil!Jd S:.ate Environ monl .:JI P,otoclion Agoncy (E.P.\):
~.,92ili)ootintr.'o2Itomeb rogc~~~
(t':t'mf'tl;mN" ::i~c:;i~t1".-" inlrwm~bnn;
Rners1,1e Co,mt y Only Rain In lhe Stom, Drern Polluf1Q11 Proteclloo Progrum gra1e fu lly a c lnowlecfoes ,ne 8.:iy A rea ~iormwau:r Maoag~o"1Agorn;lo,A ssooIa:ion amt the Cf3.iolr19 Ew Ipn,a11I lra<le ~C'.I011hon \cir 1n10rmatio1, p«'JVUed 11, lh,!'.t•rochwe s1ormlater Piollulion
What you shoulcl know for ...

Swimming Pool.

Jacuzzi and
Fountain Maintenance
Do you kn ow , .. where the water actually goes?
Storm Drains are not
connected to sanitarv
sewer svstems and
treatment plants!
The pri mary purpose of storm d rai ns is to carry rain water away from developed areas to prevent fl oodi ng. Un trea ted storm wa ter and lhe pollutants it carries fl ow directl y into ri vers, lakes , and streams . Wastewater from res idential swimming pools, j acu zzis, fi shponds. and fountains of ten contain chemica ls used for saniti zi ng or cleansing pu rposes . Tox ic chemi cals (such as chlorine or copper-based algaeci des) can damage the environment when wastewa ter is allowed to flow into our local rive rs, la ke s, and streams by way of th e storm drain system . Each of us can do our pa rt to hel p clean our water, and that adds up to a poll ution sol ution .

The Cities and County of Riverside have adopted ordinances f or storm drain pollution management t o maintain discharge co ntrol and prevent illegal sto rm drain discharge. In accorda nce witn state and federa l law, these local storm water o rdinances prohibit the discharge of pollutants into the storm drain system or local surface waters. The Only Rain in th e Storm Drain Pollution Prog ram informs residents and businesses of storm drain pollution prevention activities such as those described in this brochure.

PL EASE NOTE : Th e discharge o f po ll utan ts into the street, g utte rs , storm dra in sy stem, or wa terways-without a Re giona l Water Qua lity Control bo ard permit or wai ver -is stric tly pro hibited by local ord ina nces and sta te and federal law.

512
Bo YOll#'r Pa,, 10 PftlJIBt:I DIITt WattJrwa,sJ
Us~ These Guidelines For Proper Draining ot Your Swimming Pool, Jacuzzi and Fountain Water Dis c harg e Regulations
Requirements for pool draining
may differfrorn city to city.

Check with your water
agency to see if disposal to lhe
sanitary sewer line Is ---r---=..--'-"'--~
allowed for pool discharges
(see reverse side for Riverside Count'{ water
purveyors).

If sf!-Ner discharge Is allowed, a l1ose can be
run from your swimming pool pu 11p to the
washing macti ine drain or a sink or bathtub. f
sewer discharge is not allowed. or if your
house is served by a septic tank , review the
options presented below.

Di scharg e Options
Refinishing Po o l Surfaces
I f you are resurfacing your pool , or
resurfacing the pool patio area, be sure to
hose down mixers. tools and trailers in a dirt
area where rinse water won't now into tre
street. gutter or storm drain . Local storm
water ordinances st rictly pro h ibit t h e
dlscha ·ge of pol lutants into tl1e storm dra n
system .

Residues from acid washing and similar
activiti es require special handling . Never
discha rge low or high pH wastewater into the
street, gutteror storm drein .

If your local sewer agency will not accept pool water Into their sys,em , or if you are on a septic tank system . fo llow these g uidelines :

1. Reduce or eliminate solids (e.g., debris , leaves or dirt) In the pool water.

2. Allow the chemicals in the pool water to dissipate. This could take up to seven (7) days depending on the time of year. Create a co-oo : let your neighbor s>iare your pool while theirs is bei ng prepared fer draining , then use their pool whi le yours is being drained, Chlorinated water shou ld not be discharged into the storr, drain or surface waters. This ncludes large pools such as community swimming pools or spas .

3. When the pool water is free of all chemicals (verify by a home pool water test kit) drain pool water to landscaped a reas, lawns, yards, or any areas that will absorb the water.

4. You may have to drain the pool water over a period of a few days to allowthe landscape areas lo absorb most of the water.

5. Contrcl Ire flow of the dra ining pool water to prevent soil erosion . Do not allow sediment to enter the street, gutter or storm drain.

6. Avoid discharging pool water into the stree t and storm drain system. Wa ter runoff that enters 11,e street can pick up motor oil , pet waste, tra sh and other pollutants, eventually carrying them Into the storm drain syste m ond loca l surface waters .

Cl eaning Filters
Discharge of pool nite r rinse water and
backflush to a stream, ditch, or storm drain is
prohibited. Backflush from pool filters must be
discharged to the sanitary sewer, on -s ite
septic tank and drainlield system (if propetly
designed and adequately sized ), or a
seepage pit. Alternatively, pool filter rinse
water and backwash may be diver.ad to dirt or
landscaped areas . Filter media and other
solids sh oul d be picked up and disposed of in
the trash .

C hemica l Storage and
Handling
Use only the amount
indicated on product
labels .

Store chlorine and
other chemicals in a
covered area to
preven t runoff .

Keep out of reach
of children and
pets .

Chlorine kits . available at
retail swimming pool equipment and
supply stores, should be used to monitor
the chlorine and pH levels .

Chlorine and other pool chemicals shollld
never be allowed to flow into the gutter or
the storm drain system .

A lga ec ide s ___Iii::-::

Avoid using copper
based a l gaec ,des
unless a b so l ute l y
necessary. Control
algae with chlorine ,
organic polymers or
other alter'latives to
r.opper-b::isi:Hi 11onl •
chemicals. Copper is -=-
a heavy metal that can _ 1111111111
be toxic to aquatic life .

Proper Di sposal of Pool
Chemicals
If you need to dispose of unwanted
pool chemicals , first try giving them
to a neighbor w ith a pocl. If that
doesn't work, bring unwanted
pool chemicals to o Hou~chold
HaLardous Wast e (HHW )
Collection Event. There's no cosl
for bringing HHW items to collection
events -it's FREEi Call 1 -8OO•506-
2555 lor a schedule of HHW events i n
your c ommunity.

NEVER put unu sed chemica ls
into the trash , onto the ground
or down a s torm drain .

513
Site Design & Landscape Planning SD-10
Description
Design Objectives
0 Maximize Infiltration
0 Provide Retention
0 Slow Runoff
0 !V1inimize Impervious Land
Coverage
Prohibit Dumping of Improper
Materials
Contain Pollutants
Collect and Convey
Each project site possesses unique topographic, hydrologic, and vegetative features, some of which are more suitable for development than others. Integrating and incorporating appropriate landscape planning methodologies into the project design is the most effective action that can be done to minimize surface and groundwater contamination from stormwater.

Approach
Landscape planning should couple consideration of land suitability for urban uses ,vith consideration of community goals and projected grovv1h. Project plan designs should conserve natural areas to the extent possible, nuLximize natural water storage and infiltration opportunities, and protect slopes and channels.

Suitable Applications
Appropriate applications include residential, commercial and industrial areas planned for development or redevelopment.

Design Considerations
Design requirements for site design and landscapes planning should conform to applicable standards and specifications of agencies with jurisdiction and be consistent v,ith applicable General Plan and Local Area Plan policies.

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SD-10 Site Design & Landscape Planning
Designing New Installations
Begin the development of a plan for the landscape unit ,vith attention to the follmving general principles:
■ Formulate the plan on the basis of clearly mticulated community goals. Carefully identify conflicts and choices between retaining and protecting desired resources and comnrnnity grmvth.
■ IVIap and assess land suitability for urban uses. Include the following landscape features in the assessment: ,vooded land, open unwooded land, steep slopes, erosion-prone soils, foundation suitability, soil suitability for waste disposal, aquifers, aquifer recharge areas, wetlands, floodplains, surface waters, agricultural lands, and various categories of urban land use. \1Vhen appropriate, the assessment can highlight outstanding local or regional resources that the community determines should be protected (e.g., a scenic area, recreational area, threatened species habitat, farmland, fish run). Mapping and assessment should recognize not only these resources but also additional areas needed for their sustenance_
Project plan designs should conserve natural areas to the extent possible, maximize natural ,vater storage and infiltration opp01tunities, and protect slopes and channels.

Conserue Natzll'al Areas during Landscape Planning
If applicable, the follmving items are required and must be implemented in the site layout during the subdivision design and approval process, consistent with applicable General Plan and Local Area Plan policies:
~ Cluster development on least-sensitive portions of a site while leaving the remaining land in a natural undisturbed condition.
■ Limit clearing and grading of native vegetation at a site to the minimum amount needed to build lots, allow access, and provide fire protection.
■ l\faximize trees and other vegetation at each site by planting additional vegetation, clustering tree areas, and promoting the use of native and/or drought tolerant plants_ ■ Promote natural vegetation b~, using parking lot islands and other landscaped areas. ■ Preserve riparian areas and ,vetlands.
1\!laximize Natural l'Vater Storage and Infiltration Opportunities l'Vithin the Landscape Unit ■ Promote the conservation of forest cover. Building on land that is already deforested affects basin hydrology to a lesser extent than conve1ti11g forested land. Loss of forest cover reduces interception storage, detention in the organic forest floor layer, and water losses by evapotranspiration, resulting in large peak runoff increases and either their negative effects or the expense of countering them with structural solutions. ■ Maintain natural storage reservoirs and drainage conidors, including depressions, areas of permeal)le soils, swales, and intermittent streams. Develop and implement policies and 2 of 4 California Stormwater BMP Handbook
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regulations to discourage the clearing, filling, and channelization of these features. Utilize them in drainage networks in preference to pipes, culverts, and engineered ditches. ■ Evaluating infiltration oppo1tunities by referring to the stonnwater management manual for the jurisdiction and pay particular attention to the selection criteria for avoiding groundwater contamination, poor soils, and hydrogeological conditions that cause these facilities to fail. If necessary, locate developments ,vith large amounts of impen,ious surfaces or a potential to produce relatively contaminated runoff a-way from ground·water recharge areas.

Protection of Slopes and Channels during Landscape Design ■ Convey runoff safely from the tops of slopes.
■ Avoid disturbing steep or unstable slopes.
■ Avoid disturbing natural channels.
■ Stabilize disturbed slopes as quickly as possible.
■ Vegetate slopes with native or drought tolerant vegetation. ■ Control and treat flows in landscaping and/or other controls prior to reaching existing natural drainage systems.
■ Stabilize temporary and permanent channel crossings as quickly as possible, and ensure that increases in run-off velocity and frequency caused by the project do not erode the channel. ■ Install energy dissipaters, such as 1iprap, at the outlets of new storm drains, culverts, conduits, or channels that enter unlined channels in accordance ,vith applicable specifications to minimize erosion. Energy dissipaters shall be installed in such a way as to minimize impacts to receiving ,vaters.
■ Line on-site conveyance channels where appropriate, to reduce erosion caused by increased flow velocity due to increases in tributary impervious area. The first choice for linings should be grass or some other vegetative surface, since these materials not only reduce runoff velocities, but also provide water quality benefits from filtration and infiltration. If velocities in the channel are high enough to erode grass or other vegetative linings, riprap, concrete, soil cement, or geo-grid stabilization are other alternatives. ■ Consider other design principles that are comparable and equally effective.

Redeveloping Existing Installations
Various jurisdictional stonnwater management and mitigation plans (SUSMP, WQI\1P, etc.) define ··redevelopment'' in terms of amounts of additional impervious area, increases in gross floor area and/or e:),,.'terior construction, and land disturbing activities with structural or impervious surfaces. The definition of .. redevelopment'' must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment. If the definition applies, the steps outlined under "designing new installations'' above should be followed.

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SD-10 Site Design & Landscape Planning
Redevelopment may present significant opportunity to add features ,vhich had not previously been implemented. Examples include incorporation of depressions, areas of permeable soils, and s,vales in newly redeveloped areas. \Vhile some site constraints may exist due to the status of already existing infrastructure, opportunities should not be missed to maximize infiltration, slow runoff, reduce impervious areas, disconnect directly connected impenious areas.

Other Resources
A 1\fanual for the Standard Urban Stormwater l\Iitigation Plan (SUSlVlP), Los Angeles County Department of Public \Yorks, May 2002.

Storm water Management l\fanual for \'\'estem ·washington, \Vashington State Department of Ecology, August 2001.

Model Standard Urban Storm \1Vater Mitigation Plan (SUSJ'VlP) for San Diego County, Port of San Diego, and Cities in San Diego County, Februar!' 14, 2002. lVlodel \Vater Quality Management Plan (\VQMP) for County of Orange, Orange County Flood Control Dist1ict, and the Incorporated Cities of Orange County, Draft February 2003.

Ventura Countywide Technical Guidance Manual for Stormwater Quality Control 1\1easures, July 2002.
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517
Efficient Irrigation SD-12
Design Objectives
0 Maximize Infiltration
0 Provide Retention
0 Slow Runoff
fli·1inimize Impervious Land
Coverage
Prohibit Dumping of Improper
Materials
Description
Contain Pollutants
Collect and Convey
Irrigation \Yater provided to landscaped areas may result in excess irrigation water being conveyed into stonnv.rnter drainage systems.

Approach
Project plan designs for development and redevelopment should include application methods of irrigation water that minimize runoff of excess irrigation water into the stormwater conveyance system.

Suitable Applications
Appropriate applications include residential, commercial and industiial areas planned for development or redevelopment. (Detached residential single-family homes are typically excluded from this requirement.)
Design Considerations
Designing New Installations
TI1e following methods to reduce excessive irrigation runoff should be considered, and incorporated and implemented where determined applicable and feasib1e by the Pennittee:
■ Employ rain-triggered shutoff devices to prevent irrigation after precipitation. ■ Design irrigation systems to each landscape area's specific water requirements. ■ Include design featuring flmv reducers or shutoff valves triggered by a pressure drop to control water loss in the event of broken sprinkler heads or lines.
■ Implement landscape plans consistent with County or City water conservation resolutions, which may include provision of water sensors, programmable inigation times (for short cycles), etc.

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SD-12 Efficient Irrigation
■ Design timing and application methods of irrigation water to minimize the runoff of excess irrigation water into the storm water drainage system.
■ Group plants with similar water requirements in order to reduce excess irrigation runoff and promote surface filtration. Choose plants \Vith lovv· irrigation requirements (for example, native or drought tolerant species). Consider design features such as:

Using mulches (such as wood chips or bar) in planter areas ,vithout ground cover to minimize sediment in runoff
Installing appropriate plant materials for the location, in accordance with amount of sunlight and climate, and use native plant materials where possible and/or as recommended by the landscape architect
Leaving a vegetative barrier along the property boundary and interior watercourses, to act as a pollutant filter, where appropriate and feasible Choosing plants that minimize or eliminate the use offertilizer or pesticides to sustain growth
■ Employ other comparable, equally effective methods to reduce irrigation water runoff.

Redeveloping Existing Installations
Various jurisdictional stormwater management and mitigation plans (SUSrvIP, v\TQivIP, etc.) define "redevelopment'' in terms of amounts of additional impervious area, increases in gross floor area and/or e::-..1:erior construction, and land disturbing acti,,ities with structural or impervious smfaces. TI1e definition of'' redevelopment" must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment. If the definition applies, the steps outlined under "designing new installations·· above should be followed.

Other Resources
A Manual for the Standard Urban Stormwater rvfitigation Plan (SUSl'vIP), Los Angeles County Department of Public Works, 1fay 2002.
l\fodel Standard Urban Storm \\Tater Mitigation Plan (SUSIVIP) for San Diego County, Port of San Diego, and Cities in San Diego County, February 14, 2002.

Model 'Nater Quality rvianagement Plan (WQMP) for County of Orange, Orange County Flood Control District, and the Incorporated Cities of Orange County, Draft February 2003.

Ventura Countywide Technical Guidance IVIanual for Stormwater Quality Control JVIeasures, July 2002.
2 of 2 California Storrnwater BMP Handbook
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519
Storm Drain Signage
Description
SD-13
Design Objectives
tv1aximize Infiltration
Provide Retention
Slow Runoff
Minimize Impervious Land
Coverage
0 Prohibit Dumping of Improper
Materials
Contain Pollutants
Collect and Convey
v\Taste materials dumped into storm drain inlets can have severe impacts on receiving and ground waters. Posting notices regarding discharge prohibitions at storm drain inlets can prevent waste dumping. Storm drain signs and stencils are highly visible source controls that are typically placed directly adjacent to storm drain inlets.

Approach
TI1e stencil or affixed sign contains a brief statement that prohibits dumping of improper materials into the urban runoff conveyance system. Storm drain messages have become a popular method of alerting the public about the effects of and the prohibitions against \vaste disposal.

Suitable Applications
Stencils and signs alert the public to the destination of pollutants discharged to the storm drain.

Signs are appropriate in residential, commercial, and industrial areas, as well as any other area where contributions or clumping to storm drains is likely.

Design Considerations
Storm drain message markers or placards are recommended at all storm drain inlets within the boundary of a development project. The marker should be placed in clear sight facing toward anyone approaching the inlet from either side. All storm drain inlet locations should be identified on the development site map.

Designing New Installations
TI1e follmving methods should be considered for inclusion in the project design and show on project plans:
■ Provide stenciling or labeling of all storm drain inlets and catch basins, constructed or modified, ,vi thin the project area \\ith prohibitive language. Examples include "NO DUMPING January 2003 California Stormwater BMP Handbook
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520
SD-13 Storm Drain Signage
-DRAINS TO OCEAN'' and/ or other graphical icons to discourage illegal dumping. ■ Post signs v,rith prohibitive language and/or graphical icons, which prohibit illegal clumping at public access points along channels and creeks ,vithin the project area.

Note -Some local agencies have approved specific signage and/or storm drain message placards for use. Consult local agency storm water staff to determine specific requirements for placard types and methods of application.

Redeveloping Existing Installations
Various jurisdictional stonnwater management and mitigation plans (SUSMP, "\VQTvIP, etc.) define "redevelopment'' in terms of amounts of additional impenious area, increases in gross floor area and/ or exterior construction, and land disturbing activities with structural or impervious surfaces. If the project meets the definition of "redevelopment'', then the requirements stated under" designing new installations'' above should be included in all project design plans.

Additional Information
.Nlaintenance Considerations
■ Legibility of markers and signs should be maintained. If required by the agency with jurisdiction over the project, the owner/operator or homemvner's association should enter into a maintenance agreement with the agency or record a deed restriction upon the property title to maintain the legibility of placards or signs.

Placement
■ Signage on top of curbs tends to weather and fade.
■ Signage on face of curbs tends to be worn by contact ,'\1ith vehicle tires and sweeper brooms.

Supplemental Information
Exa1nples
■ J\fost 1\!1S4 programs have storm drain signage programs. Some MS4 programs will provide stencils, or arrange for volunteers to stencil storm drains as pait of their outreach program.

Other Resources
A :rvianual for the Standard Urban Stormwater Mitigation Plan (SUSTvIP), Los Angeles County Depmtment of Public ·works, l'vlay 2002.
l\fodel Standard Urban Storm "\·Vater :rvlitigation Plan (SUSl'vIP) for San Diego County, Port of San Diego, and Cities in San Diego County, February 14, 2002.

Model ·water Quality l\fanagement Plan (\VQMP) for County of Orange, Orange County Flood Control District, and the Incorporated Cities of Orange County, Draft February 2003.

Ventura Countywicle Technical Guidance 1\Ianual for Stonnwater Quality Control Measures, July 2002.
2 of 2 California Storrnwater BMP Handbook
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521
Trash Storage Areas
Description
Trash storage areas are areas where a trash receptacle (s) are located for use as a repository for solid wastes. Stormwater runoff from areas where trash is stored or disposed of can be polluted. In addition, loose trash and debris can be easily transported by ,vater or ,vind into nearby storm drain inlets, channels, and/or creeks. vVaste handling operations that may be sources of stormwater pollution include dumpsters, litter control, and waste piles.

Approach
This fact sheet contains details on the specific measures required to prevent or reduce pollutants in stonnwater runoff associated ,vith trash storage and handling. Preventative measures including enclosures, containment structures, and impervious pavements to mitigate spills, should be used to reduce the likelihood of contamination.

Suitable Applications
SD-32
Design Objectives
Maximize Infiltration
Provide Retention
Slow Runoff
Minimize Impervious Land
Coverage
Prohibit Dumping of Improper
Materials
0 Contain Pollutants
Collect and Convey
Appropriate applications include residential, commercial and industrial areas planned for development or redevelopment. (Detached residential single-family homes are typically excluded from this requirement.)
Design Considerations
Design requirements for waste handling areas are governed by Building and Fire Codes, and by current local agency ordinances and zoning requirements. The design criteria described in this fact sheet are meant to enhance and be consistent with these code and ordinance requirements.

Hazardous waste should be handled in accordance with legal requirements established in Title 22, California Code of Regulation.
'\\Tastes from commercial and industrial sites are typically hauled by either public or commercial carriers that may have design or access requirements for ·waste storage areas. The design criteria in this fact sheet are recommendations and are not intended to be in conflict with requirements established by the waste hauler. The waste hauler should be contacted prior to the design of your site trash collection areas. Conflicts or issues should be discussed with the local agency.

Designing New Installations
Trash storage areas should be designed to consider the following structural or treatment control BlV1Ps:
■ Design trash container areas so that drainage from adjoining roofs and pavement is diwrted around the area(s) to avoid run-on. This might include henning or grading the ,vaste handling area to prevent run-on of stonnwater.
■ Make sure trash container areas are screened or walled to prevent off-site transport of trash.

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SD-32 Trash Storage Areas
■ Use lined bins or dumpsters to reduce leaking of liquid ,vaste. ■ Prmide roofs, mvnings, or attached lids on all trash containers to minimize direct precipitation and prevent rainfall from entering containers. ■ Pave trash storage areas with an impervious surface to mitigate spills. ■ Do not locate storm drains in immediate vicinity of the trash storage area. ■ Post signs on all dumpsters informing users that hazardous materials are not to be disposed of therein.

Redeveloping Existing Installations
Various jurisdictional stormwater management and mitigation plans (SUSt,IP, '1,NQMP, etc.) define .. redevelopment'' in terms of amounts of additional impervious area, increases in gross floor area and/or exierior construction, and land disturbing activities ,vith structural or impervious surfaces. The definition of .. redevelopment" must be consulted to determine whether or not the requirements for ne,v development apply to areas intended for redevelopment. If the definition applies, the steps outlined under "designing new installations'' above should be follmved.

Additional Information
.NI aintenance Considerations
The integrity of structural elements that are subject to damage (i.e., screens, covers, and signs) must be maintained by the mvner/operator. Maintenance agreements between the local agency and the owner/operator may be required. Some agencies will require maintenance deed restrictions to be recorded of the property title. If required by the local agency, maintenance agreements or deed restrictions must be executed by the mvner/operator before improvement plans are approved.

Other Resources
A Manual for the Standard Urban Stonnwater Mitigation Plan (SUS:rvIP), Los Angeles County Department of Public Works, 1viay 2002.
:rviodel Standard Urban Storm Water Ivlitigation Plan (SUS1vIP) for San Diego County, Port of San Diego, and Cities in San Diego County, February 14, 2002.

Model Water Quality Management Plan (\\TQMP) for County of Orange, Orange County Flood Control District, and the Incorporated Cities of Orange County, Draft Februmy 2003.

Ventura Countywide Technical Guidance lVIanual for Stonnwater Quality Control lVIeasures, July 2002.
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523
Building & Grounds Maintenance SC-41
Description
Storm water runoff from building and grounds maintenance activities can be contaminated with toxic hydrocarbons in solvents, fertilizers and pesticides, suspended solids, heavy metals, abnormal pH, and oils and greases. Utilizing the protocols in this fact sheet will prevent or reduce the discharge of pollutants to stormwater from building and grounds
maintenance activities by washing and cleaning up with as little water as possible, following good landscape management
practices, preventing and cleaning up spills immediately, keeping debris from entering the storm drains, and maintaining the stormwater collection system.

Approach
Reduce potential for pollutant discharge through source control pollution prevention and BMP implementation. Successful implementation depends on effective training of employees on applicable BMPs and general pollution prevention strategies and objectives.

Pollution Prevention
■ Switch to non-toxic chemicals for maintenance when
possible.
■ Choose cleaning agents that can be recycled.
■ Encourage proper lawn management and landscaping,
including use of native vegetation.

January 2003 California Stormwater BMP Handbook
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Objectives
■ Cover
■ Contain
■ Educate
■ Reduce/Minimize
■ Product Substitution
Targeted Constituents
Sediment
Nutrients
Trash
Metals
Bacteria
Oil and Grease
Organics
✓
✓
✓
✓
SQA
Stormwater
Quality
Association
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524
SC-41 Building & Grounds Maintenance
■ Encourage use of Integrated Pest Management techniques for pest control. ■ Encourage proper onsite recycling of yard trimmings.
■ Recycle residual paints, solvents, lumber, and other material as much as possible.

Suggested Protocols
Pressure Washing of Buildings, Rooftops, and Other Large Objects ■ In situations where soaps or detergents are used and the surrounding area is paved, pressure washers must use a water collection device that enables collection of wash water and associated solids. A sump pump, wet vacuum or similarly effective device must be used to collect the runoff and loose materials. The collected runoff and solids must be disposed of properly.
11 If soaps or detergents are not used, and the surrounding area is paved, wash runoff does not have to be collected but must be screened. Pressure washers must use filter fabric or some other type of screen on the ground and/or in the catch basin to trap the particles in wash water runoff.
■ If you are pressure washing on a grassed area (with or without soap), runoff must be dispersed as sheet flow as much as possible, rather than as a concentrated stream. The wash runoff must remain on the grass and not drain to pavement.

Landscaping Activities
■ Dispose of grass clippings, leaves, sticks, or other collected vegetation as garbage, or by composting. Do not dispose of collected vegetation into waterways or storm drainage systems.
■ Use mulch or other erosion control measures on exposed soils.

Building Repair, Remodeling, and Construction
■ Do not dump any toxic substance or liquid waste on the pavement, the ground, or toward a storm drain.
■ Use ground or drop cloths underneath outdoor painting, scraping, and sandblasting work, and properly dispose of collected material daily.
■ Use a ground cloth or oversized tub for activities such as paint mixing and tool cleaning. ■ Clean paintbrushes and tools covered with water-based paints in sinks connected to sanitary sewers or in portable containers that can be dumped into a sanitary sewer drain. Brushes and tools covered with non-water-based paints, finishes, or other materials must be cleaned in a manner that enables collection of used solvents (e.g., paint thinner, turpentine, etc.) for recycling or proper disposal.
■ Use a storm drain cover, filter fabric, or similarly effective runoff control mechanism if dust, grit, wash water, or other pollutants may escape the work area and enter a catch basin. This is particularly necessary on rainy days. The containment device(s) must be in place at the beginning of the work day, and accumulated dirty runoff and solids must be collected and disposed of before removing the containment device(s) at the end of the work day. 2 of 5 California Stormwater BMP Handbook
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Building & Grounds Maintenance SC-41
■ If you need to de-water an excavation site, you may need to filter the water before discharging to a catch basin or off-site. If directed off-site, you should direct the water through hay bales and filter fabric or use other sediment filters or traps. ■ Store toxic material under cover during precipitation events and when not in use. A cover would include tarps or other temporary cover material.

Mowing, Trimming, and Planting
■ Dispose ofleaves, sticks, or other collected vegetation as garbage, by composting or at a permitted landfill. Do not dispose of collected vegetation into waterways or storm drainage systems.
■ Use mulch or other erosion control measures when soils are exposed. ■ Place temporarily stockpiled material away from watercourses and drain inlets, and berm or cover stockpiles to prevent material releases to the storm drain system. ■ Consider an alternative approach when bailing out muddy water: do not put it in the storm drain; pour over landscaped areas.
■ Use hand weeding where practical.

Fertilizer and Pesticide Management
■ Follow all federal, state, and local laws and regulations governing the use, storage, and disposal of fertilizers and pesticides and training of applicators and pest control advisors. ■ Use less toxic pesticides that will do the job when applicable. Avoid use of copper-based pesticides if possible.
■ Do not use pesticides if rain is expected.
■ Do not mix or prepare pesticides for application near storm drains. ■ Use the minimum amount needed for the job.
■ Calibrate fertilizer distributors to avoid excessive application. ■ Employ techniques to minimize off-target application ( e.g., spray drift) of pesticides, including consideration of alternative application techniques. ■ Apply pesticides only when wind speeds are low.
■ Fertilizers should be worked into the soil rather than dumped or broadcast onto the surface. ■ Irrigate slowly to prevent runoff and then only as much as is needed. ■ Clean pavement and sidewalk if fertilizer is spilled on these surfaces before applying irrigation water.
■ Dispose of empty pesticide containers according to the instructions on the container label.

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SC-41 Building & Grounds Maintenance
■ Use up the pesticides. Rinse containers, and use rinse water as product. Dispose of unused pesticide as hazardous waste.
■ Implement storage requirements for pesticide products with guidance from the local fire department and County Agricultural Commissioner. Provide secondary containment for pesticides.

Inspection
■ Inspect irrigation system periodically to ensure that the right amount of water is being applied and that excessive runoff is not occurring. Minimize excess watering and repair leaks in the irrigation system as soon as they are observed.

Training
■ Educate and train employees on pesticide use and in pesticide application techniques to prevent pollution.
■ Train employees and contractors in proper techniques for spill containment and cleanup. ■ Be sure the frequency of training takes into account the complexity of the operations and the nature of the staff.

Spill Response and Prevention
■ Keep your Spill Prevention Control and Countermeasure (SPCC) Plan up-to-date. ■ Place a stockpile of spill cleanup materials, such as brooms, dustpans, and vacuum sweepers (if desired) near the storage area where it will be readily accessible. ■ Have employees trained in spill containment and cleanup present during the loading/unloading of dangerous wastes, liquid chemicals, or other materials. ■ Familiarize employees with the Spill Prevention Control and Countermeasure Plan. ■ Clean up spills immediately.

Other Considerations
Alternative pest/weed controls may not be available, suitable, or effective in many cases.

Requirements
Costs
■ Cost will vary depending on the type and size of facility. ■ Overall costs should be low in comparison to other BMPs.

Maintenance
Sweep paved areas regularly to collect loose particles. Wipe up spills with rags and other absorbent material immediately, do not hose down the area to a storm drain. 4 of 5 California Stormwater BMP Handbook
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Supplemental Information
Further Detail of the BMP
Fire Sprinkler Line Flushing
Building fire sprinkler line flushing may be a source of non-stormwater runoff pollution. The water entering the system is usually potable water, though in some areas it may be non-potable reclaimed wastewater. There are subsequent factors that may drastically reduce the quality of the water in such systems. Black iron pipe is usually used since it is cheaper than potable piping, but it is subject to rusting and results in lower quality water. Initially, the black iron pipe has an oil coating to protect it from rusting between manufacture and installation; this will contaminate the water from the first flush but not from subsequent flushes. Nitrates, poly phosphates and other corrosion inhibitors, as well as fire suppressants and antifreeze may be added to the sprinkler water system. Water generally remains in the sprinkler system a long time (typically a year) and between flushes may accumulate iron, manganese, lead, copper, nickel, and zinc. The water generally becomes anoxic and contains living and dead bacteria and breakdown products from chlorination. This may result in a significant BOD problem and the water often smells. Consequently dispose fire sprinkler line flush water into the sanitary sewer.

Do not allow discharge to storm drain or infiltration due to potential high levels of pollutants in fire sprinkler line water.

References and Resources
California's Nonpoint Source Program Plan http://www.swrcb.ca.gov/nps/index.html Clark County Storm Water Pollution Control Manual
http://www.co.clark.wa.us/pubworks/bmpman.pdf
King County Storm Water Pollution Control Manual http://dnr.metrokc.gov/wlr/dss/spcm.htm Mobile Cleaners Pilot Program: Final Report. 1997. Bay Area Stormwater Management Agencies Association (BASMAA). http: // www.basmaa.org/ Pollution from Surface Cleaning Folder. 1996. Bay Area Stormwater Management Agencies Association (BASMAA). http://www.basmaa.org/
Santa Clara Valley Urban Runoff Pollution Prevention Program http://www.scvurppp.org The Storm Water Managers Resource Center http://www.stormwatercenter.net/ January 2003 California Stormwater BMP Handbook
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528
Parking/Storage Area Maintenance SC-43
Description
Parking lots and storage areas can contribute a number of substances, such as trash, suspended solids, hydrocarbons, oil and grease, and heavy metals that can enter receiving waters through stormwater runoff or non-stormwater discharges. The protocols in this fact sheet are intended to prevent or reduce the discharge of pollutants from parking/ storage areas and include using good housekeeping practices, following appropriate cleaning BMPs, and training employees.

Approach
The goal of this program is to ensure stormwater pollution prevention practices are considered when conducting activities on or around parking areas and storage areas to reduce potential for pollutant discharge to receiving waters. Successful implementation depends on effective training of employees on applicable BMPs and general pollution prevention strategies and objectives.

Pollution Prevention
■ Encourage alternative designs and maintenance strategies for impervious parking lots. (See New Development and
Redevelopment BMP Handbook)
■ Keep accurate maintenance logs to evaluate BMP
implementation.

529
SC-43 Parking/Storage Area Maintenance
Suggested Protocols
General
■ Keep the parking and storage areas clean and orderly. Remove debris in a timely fashion. ■ Allow sheet runoff to flow into biofilters (vegetated strip and swale) and/or infiltration devices.
■ Utilize sand filters or oleophilic collectors for oily waste in low quantities. ■ Arrange rooftop drains to prevent drainage directly onto paved surf aces. ■ Design lot to include semi-permeable hardscape.
■ Discharge soapy water remaining in mop or wash buckets to the sanitary sewer through a sink, toilet, clean-out, or wash area with drain.

Controlling Litter
■ Post "No Littering" signs and enforce anti-litter laws. ■ Provide an adequate number oflitter receptacles.
■ Clean out and cover litter receptacles frequently to prevent spillage. ■ Provide trash receptacles in parking lots to discourage litter. ■ Routinely sweep, shovel, and dispose of litter in the trash.

Surface Cleaning
■ Use dry cleaning methods (e.g., sweeping, vacuuming) to prevent the discharge of pollutants into the storm water conveyance system if possible.
■ Establish frequency of public parking lot sweeping based on usage and field observations of waste accumulation.
■ Sweep all parking lots at least once before the onset of the wet season. ■ Follow the procedures below if water is used to clean surfaces:

Block the storm drain or contain runoff.

Collect and pump wash water to the sanitary sewer or discharge to a pervious surface.

Do not allow wash water to enter storm drains.

Dispose of parking lot sweeping debris and dirt at a landfill. ■ Follow the procedures below when cleaning heavy oily deposits:
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Clean oily spots with absorbent materials.

Use a screen or filter fabric over inlet, then wash surfaces.

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Do not allow discharges to the storm drain.

Vacuum/pump discharges to a tank or discharge to sanitary sewer.

Appropriately dispose of spilled materials and absorbents.

Surface Repair
■ Preheat, transfer or load hot bituminous material away from storm drain inlets. ■ Apply concrete, asphalt, and seal coat during dry weather to prevent contamination from contacting stormwater runoff. ■ Cover and seal nearby storm drain inlets where applicable (with waterproof material or mesh) and manholes before applying seal coat, slurry seal, etc. Leave covers in place until job is complete and all water from emulsified oil sealants has drained or evaporated. Clean any debris from these covered manholes and drains for proper disposal. ■ Use only as much water as necessary for dust control, to avoid runoff. ■ Catch drips from paving equipment that is not in use with pans or absorbent material placed under the machines. Dispose of collected material and absorbents properly.

Inspection
■ Have designated personnel conduct inspections of parking facilities and stormwater conveyance systems associated with parking facilities on a regular basis. ■ Inspect cleaning equipment/sweepers for leaks on a regular basis.

Training
■ Provide regular training to field employees and/ or contractors regarding cleaning of paved areas and proper operation of equipment. ■ Train employees and contractors in proper techniques for spill containment and cleanup.

Spill Response and Prevention
■ Keep your Spill Prevention Control and Countermeasure (SPCC) Plan up-to-date. ■ Place a stockpile of spill cleanup materials where it will be readily accessible or at a central location. ■ Clean up fluid spills immediately with absorbent rags or material. ■ Dispose of spilled material and absorbents properly.

Other Considerations
Limitations related to sweeping activities at large parking facilities may include high equipment costs, the need for sweeper operator training, and the inability of current sweeper technology to remove oil and grease.

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Requirements
Costs
Cleaning/ sweeping costs can be quite large. Construction and maintenance of stormwater structural controls can be quite expensive as well.

Maintenance
■ Sweep parking lot regularly to minimize cleaning with water. ■ Clean out oil/water/sand separators regularly, especially after heavy storms. ■ Clean parking facilities regularly to prevent accumulated wastes and pollutants from being discharged into conveyance systems during rainy conditions.

Supplemental Information
Further Detail of the BMP
Surface Repair
Apply concrete, asphalt, and seal coat during dry weather to prevent contamination from contacting stormwater runoff. Where applicable, cover and seal nearby storm drain inlets (with waterproof material or mesh) and manholes before applying seal coat, slurry seal, etc. Leave covers in place until job is complete and all water from emulsified oil sealants has drained or evaporated. Clean any debris from these covered manholes and drains for proper disposal.

Only use only as much water as is necessary for dust control to avoid runoff.

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Drainage System Maintenance SC-44
Description
As a consequence of its function, the stormwater conveyance system collects and transports urban runoff and storm water that may contain certain pollutants. The protocols in this fact sheet are intended to reduce pollutants reaching receiving waters through proper conveyance system operation and maintenance.

Approach
Pollution Prevention
Maintain catch basins, stormwater inlets, and other storm water conveyance structures on a regular basis to remove pollutants, reduce high pollutant concentrations during the first flush of storms, prevent clogging of the downstream conveyance system, restore catch basins' sediment trapping capacity, and ensure the system functions properly hydraulically to avoid flooding.

Suggested Protocols
Catch Basins/Inlet Structures
■ Staff should regularly inspect facilities to ensure compliance with the following:

Immediate repair of any deterioration threatening
structural integrity.

Cleaning before the sump is 40% full. Catch basins
should be cleaned as frequently as needed to meet this
standard.

Stenciling of catch basins and inlets (see SC34 Waste
Handling and Disposal).

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Objectives
■ Cover
■ Contain
■ Educate
■ Reduce/Minimize
Targeted Constituents
Sediment
Nutrients
Trash
Metals
Bacteria
Oil and Grease
Organics
✓
✓
✓
SQA
Stormwater
Quality
Association
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■ Clean catch basins, storm drain inlets, and other conveyance structures before the wet season to remove sediments and debris accumulated during the summer. ■ Conduct inspections more frequently during the wet season for problem areas where sediment or trash accumulates more often. Clean and repair as needed. ■ Keep accurate logs of the number of catch basins cleaned. ■ Store wastes collected from cleaning activities of the drainage system in appropriate containers or temporary storage sites in a manner that prevents discharge to the storm drain.
■ Dewater the wastes if necessary with outflow into the sanitary sewer if permitted. Water should be treated with an appropriate filtering device prior to discharge to the sanitary sewer. If discharge to the sanitary sewer is not allowed, water should be pumped or vacuumed to a tank and properly disposed. Do not dewater near a storm drain or stream.

Storm Drain Conveyance System
■ Locate reaches of storm drain with deposit problems and develop a flushing schedule that keeps the pipe clear of excessive buildup.
■ Collect and pump flushed effluent to the sanitary sewer for treatment whenever possible.

Pump Stations
■ Clean all storm drain pump stations prior to the wet season to remove silt and trash. ■ Do not allow discharge to reach the storm drain system when cleaning a storm drain pump station or other facility.
■ Conduct routine maintenance at each pump station.
■ Inspect, clean, and repair as necessary all outlet structures prior to the wet season.

Open Channel
■ Modify storm channel characteristics to improve channel hydraulics, increase pollutant removals, and enhance channel/creek aesthetic and habitat value. ■ Conduct channel modification/improvement in accordance with existing laws. Any person, government agency, or public utility proposing an activity that will change the natural (emphasis added) state of any river, stream, or lake in California, must enter into a Steam or Lake Alteration Agreement with the Department of Fish and Game. The developer-applicant should also contact local governments (city, county, special districts), other state agencies (SWRCB, RWQCB, Department of Forestry, Department of Water Resources), and Federal Corps of Engineers and USFWS.

Illicit Connections and Discharges
■ Look for evidence of illegal discharges or illicit connections during routine maintenance of conveyance system and drainage structures:
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Are there any odors associated with the drainage system? Record locations of apparent illegal discharges/illicit connections? Track flows back to potential dischargers and conduct aboveground inspections. This can be done through visual inspection of upgradient manholes or alternate techniques including zinc chloride smoke testing, fluorometric dye testing, physical inspection testing, or television camera inspection.

Eliminate the discharge once the origin of flow is established. ■ Stencil or demarcate storm drains, where applicable, to prevent illegal disposal of pollutants.

Storm drain inlets should have messages such as "Dump No Waste Drains to Stream" stenciled next to them to warn against ignorant or intentional dumping of pollutants into the storm drainage system.
■ Refer to fact sheet SC-10 Non-Stormwater Discharges.

Illegal Dumping
■ Inspect and clean up hot spots and other storm drainage areas regularly where illegal dumping and disposal occurs.
■ Establish a system for tracking incidents. The system should be designed to identify the following:

Illegal dumping hot spots
Types and quantities (in some cases) of wastes
Patterns in time of occurrence (time of day/night, month, or year) Mode of dumping (abandoned containers, "midnight dumping" from moving vehicles, direct dumping of materials, accidents/spills)
Responsible parties
■ Post "No Dumping" signs in problem areas with a phone number for reporting dumping and disposal. Signs should also indicate fines and penalties for illegal dumping. ■ Refer to fact sheet SC-10 Non-Stormwater Discharges.

Training
■ Train crews in proper maintenance activities, including record keeping and disposal. ■ Allow only properly trained individuals to handle hazardous materials/wastes. ■ Have staff involved in detection and removal of illicit connections trained in the following:

OSHA-required Health and Safety Training (29 CFR 1910.120) plus annual refresher training (as needed).

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OSHA Confined Space Entry training (Cal-OSHA Confined Space, Title 8 and Federal OSHA 29 CFR 1910.146).

Procedural training (field screening, sampling, smoke/dye testing, TV inspection).

Spill Response and Prevention
■ Investigate all reports of spills, leaks, and/or illegal dumping promptly. ■ Clean up all spills and leaks using "dry" methods (with absorbent materials and/or rags) or dig up, remove, and properly dispose of contaminated soil. ■ Refer to fact sheet SC-11 Spill Prevention, Control, and Cleanup.

Other Considerations (Limitations and Regulations)
■ Clean-up activities may create a slight disturbance for local aquatic species. Access to items and material on private property may be limited. Trade-offs may exist between channel hydraulics and water quality/riparian habitat. If storm channels or basins are recognized as wetlands, many activities, including maintenance, may be subject to regulation and permitting.
■ Storm drain flushing is most effective in small diameter pipes (36-inch diameter pipe or less, depending on water supply and sediment collection capacity). Other considerations associated with storm drain flushing may include the availability of a water source, finding a downstream area to collect sediments, liquid/sediment disposal, and prohibition against disposal of flushed effluent to sanitary sewer in some areas. ■ Regulations may include adoption of substantial penalties for illegal dumping and disposal. ■ Local municipal codes may include sections prohibiting discharge of soil, debris, refuse, hazardous wastes, and other pollutants into the storm drain system.

Requirements
Costs
■ An aggressive catch basin cleaning program could require a significant capital and O&M budget.
■ The elimination of illegal dumping is dependent on the availability, convenience, and cost of alternative means of disposal. The primary cost is for staff time. Cost depends on how aggressively a program is implemented. Other cost considerations for an illegal dumping program include:
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Purchase and installation of signs.

Rental of vehicle(s) to haul illegally-disposed items and material to landfills.

Rental of heavy equipment to remove larger items (e.g., car bodies) from channels.

Purchase of landfill space to dispose of illegally-dumped items and material.

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■ Methods used for illicit connection detection (smoke testing, dye testing, visual inspection, and flow monitoring) can be costly and time-consuming. Site-specific factors, such as the level of impervious area, the density and ages of buildings, and type of land use will determine the level of investigation necessary.

Maintenance
■ Two-person teams may be required to clean catch basins with vactor trucks. ■ Teams of at least two people plus administrative personnel are required to identify illicit discharges, depending on the complexity of the storm sewer system. ■ Arrangements must be made for proper disposal of collected wastes. ■ Technical staff are required to detect and investigate illegal dumping violations.

Supplemental Information
Further Detail of the BMP
Storm Drain Flushing
Flushing is a common maintenance activity used to improve pipe hydraulics and to remove pollutants in storm drainage systems. Flushing may be designed to hydraulically convey accumulated material to strategic locations, such as an open channel, another point where flushing will be initiated, or the sanitary sewer and the treatment facilities, thus preventing resuspension and overflow of a portion of the solids during storm events. Flushing prevents "plug flow" discharges of concentrated pollutant loadings and sediments. Deposits can hinder the designed conveyance capacity of the storm drain system and potentially cause backwater conditions in severe cases of clogging.

Storm drain flushing usually takes place along segments of pipe with grades that are too flat to maintain adequate velocity to keep particles in suspension. An upstream manhole is selected to place an inflatable device that temporarily plugs the pipe. Further upstream, water is pumped into the line to create a flushing wave. When the upstream reach of pipe is sufficiently full to cause a flushing wave, the inflated device is rapidly deflated with the assistance of a vacuum pump, thereby releasing the backed up water and resulting in the cleaning of the storm drain segment.

To further reduce impacts of storm water pollution, a second inflatable device placed well downstream may be used to recollect the water after the force of the flushing wave has dissipated. A pump may then be used to transfer the water and accumulated material to the sanitary sewer for treatment. In some cases, an interceptor structure may be more practical or required to recollect the flushed waters.

It has been found that cleansing efficiency of periodic flush waves is dependent upon flush volume, flush discharge rate, sewer slope, sewer length, sewer flow rate, sewer diameter, and population density. As a rule of thumb, the length ofline to be flushed should not exceed 700 feet. At this maximum recommended length, the percent removal efficiency ranges between 65- 75% for organics and 55-65% for dry weather grit/inorganic material. The percent removal efficiency drops rapidly beyond that. Water is commonly supplied by a water truck, but fire hydrants can also supply water. To make the best use of water, it is recommended that reclaimed water be used or that fire hydrant line flushing coincide with storm sewer flushing.

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References and Resources
California's Non point Source Program Plan http://www.swrcb.ca.gov/nps/index.html Clark County Storm Water Pollution Control Manual
http://www.co.clark.wa.us/pubworks/bmpman.pdf
Ferguson, B.K. 1991. Urban Stream Reclamation, p. 324-322, Journal of Soil and Water Conservation.

King County Storm Water Pollution Control Manual http://dnr.metrokc.gov/wlr/dss/spcm.htm Oregon Association of Clean Water Agencies. Oregon Municipal Stormwater Toolbox for Maintenance Practices. June 1998.

Santa Clara Valley Urban Runoff Pollution Prevention Program http://www.scvurppp.org The Storm Water Managers Resource Center http://www.stormwatercenter.net United States Environmental Protection Agency (USEPA). 2002. Pollution Prevention/Good Housekeeping for Municipal Operations Storm Drain System Cleaning. On line: http://www.epa.gov/npdes/menuofbmps/poll 16.htm 6 of 6 California Stormwater BMP Handbook
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Non-Stormwater Discharges SC-10
Description
Non-stormwater discharges (NSWDs) are
flows that do not consist entirely of
stormwater. Some non-stormwater
discharges do not include pollutants and
may be discharged to the storm drain if local
regulations allow. These include
uncontaminated groundwater and natural
springs. There are also some non
stormwater discharges that typically do not
contain pollutants and may be discharged to
the storm drain with conditions. These
include: potable water sources, fire hydrant
flushing, air conditioner condensate,
landscape irrigation drainage and landscape
watering, emergency firefighting, etc. as
discussed in Section 2.

However there are certain non-stormwater
discharges that pose an environmental
concern. These discharges may originate
from illegal dumping of industrial material
or wastes and illegal connections such as
internal floor drains, appliances, industrial
processes, sinks, and toilets that are illegally
connected to the nearby storm drainage
system through on-site drainage and piping.

These unauthorized discharges ( examples of
which may include: process waste waters,
cooling waters, wash waters, and sanitary
wastewater) can carry substances such as
paint, oil, fuel and other automotive fluids,
chemicals and other pollutants into storm
drains.

Non-stormwater discharges will need to be
addressed through a combination of
detection and elimination. The ultimate
goal is to effectively eliminate unauthorized
non-stormwater discharges to the
stormwater drainage system through
implementation of measures to detect,
correct, and enforce against illicit
connections and illegal discharges of
Objectives
■ Cover
■ Contain
■ Educate
■ Reduce/Minimize
■ ProductSubstitution
Targeted Constituents
Sediment
Nutrients
Trash
Metals
Bacteria
Oil and Grease
Organics
Minimum BMPs Covered e Good Housekeeping
~. Preventative
~ Maintenance
✓
✓
✓
✓
✓
✓
--------------
•· · Spill and Leak = Prevention and
Response
✓
~ MWiatetriMal Handling &t ~ as e anagemen
~ Erosion and
? Sediment Controls
-~ Employee Training
"-7 Program __ ✓
~ Quality Assurance
'-ii' Record Keeping ✓

CALIFORNIA STORMWATER

QUALITY ASSOCIATION
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pollutants on streets and into the storm drain system and downstream water bodies.

Approach
Initially the Discharger must make an assessment of non-stormwater discharges to determine which types must be eliminated or addressed through BMPs. The focus of the following approach is the elimination of unauthorized non-stormwater discharges. See other BMP Fact Sheets for activity-specific pollution prevention procedures.

General Pollution Prevention Protocols
□ Implement waste management controls described in SC-34 Waste Handling and Disposal.
□ Develop clear protocols and lines of communication for effectively prohibiting non stormwater discharges, especially those that are not classified as hazardous. These are often not responded to as effectively as they need to be. □ Stencil or demarcate storm drains, where applicable, to prevent illegal disposal of pollutants. Storm drain inlets should have messages such as "Dump No Waste Drains to Stream" or similar stenciled or demarcated next to them to warn against ignorant or unintentional dumping of pollutants into the storm drainage system. □ Manage and control sources of water such as hose bibs, faucets, wash racks, irrigation heads, etc. Identify hoses and faucets in the SWPPP, and post signage for appropriate use.

Non-Stormwater Discharge Investigation Protocols
Identifying the sources of non-stormwater discharges requires the Discharger to conduct an investigation of the facility at regular intervals. There are several categories of non stormwater discharges:
□ Visible, easily identifiable discharges, typically generated as surface runoff, such as uncontained surface runoff from vehicle or equipment washing; and □ Non-visible, (e.g., subsurface) discharges into the site drainage system through a variety of pathways that are not obvious.

The approach to detecting and eliminating non-stormwater discharges will vary considerably, as discussed below:

Visible and identifiable discharges
□ Conduct routine inspections of the facilities and of each major activity area and identify visible evidence of unauthorized non-stormwater discharges. This may include:
✓ Visual observations of actual discharges occurring;
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✓ Evidence of surface staining, discoloring etc. that indicates that discharges have occurred;
✓ Pools of water in low lying areas when a rain event has not occurred; and ✓ Discussions with operations personnel to understand practices that may lead to unauthorized discharges.
□ If evidence of non-stormwater discharges is discovered:
✓ Document the location and circumstances using Worksheets 5 and 6 (Section 2 of the manual), including digital photos;
✓ Identify and implement any quick remedy or corrective action (e.g., moving uncovered containers inside or to a proper location); and ✓ Develop a plan to eliminate the discharge. Consult the appropriate activity specific BMP Fact Sheet for alternative approaches to manage and eliminate the discharge.
□ Consult the appropriate activity-specific BMP Fact Sheet for alternative approaches to manage and eliminate the discharge. Make sure the facility SWPPP is up-to-date and includes applicable BMPs to address the non-stormwater discharge.

Other Illegal Discharges (Non visible)
fllicit Connections
□ Locate discharges from the industrial storm drainage system to the municipal storm drain system through review of "as-built" piping schematics. □ Isolate problem areas and plug illicit discharge points. □ Locate and evaluate discharges to the storm drain system. □ Visual Inspection and Inventory:
✓ Inventory and inspect each discharge point during dry weather. ✓ Keep in mind that drainage from a storm event can continue for a day or two following the end of a storm and groundwater may infiltrate the underground stormwater collection system.
✓ Non-stormwater discharges are often intermittent and may require periodic inspections.

Review Infield Piping
□ A review of the "as-built" piping schematic is a way to determine if there are any connections to the stormwater collection system.

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□ Inspect the path of loading/unloading area drain inlets and floor drains in older buildings.
□ Never assume storm drains are connected to the sanitary sewer system.

Monitoring for investigation/detection of illegal discharges □ If a suspected illegal or unknown discharge is detected, monitoring of the discharge may help identify the content and/ or suggest the source. This may be done with a field screening analysis, flow meter measurements, or by collecting a sample for laboratory analysis. Section 5 and Appendix D describe the necessary field equipment and procedures for field investigations.
□ Investigative monitoring may be conducted over time. For example if, a discharge is intermittent, then monitoring might be conducted to determine the timing of the discharge to determine the source.
□ Investigative monitoring may be conducted over a spatial area. For example, if a discharge is observed in a pipe, then monitoring might be conducted at accessible upstream locations in order to pinpoint the source of the discharge. □ Generally, investigative monitoring requiring collection of samples and submittal for lab analysis requires proper planning and specially trained staff.

Smoke Testing
Smoke testing of wastewater and stormwater collection systems is used to detect connections between the two piping systems. Smoke testing is generally performed at a downstream location and the smoke is forced upstream using blowers to create positive pressure. The advantage to smoke testing is that it can potentially identify multiple potential discharge sources at once.
□ Smoke testing uses a harmless, non-toxic smoke cartridges developed specifically for this purpose.
□ Smoke testing requires specialized equipment (e.g., cartridges, blowers) and is generally only appropriate for specially trained staff. □ A Standard Operating Procedure (SOP) for smoke testing is highly desirable. The SOP should address the following elements:
✓ Proper planning and notification of nearby residents and emergency services is necessary since introducing smoke into the system may result in false alarms; ✓ During dry weather, the stormwater collection system is filled with smoke and then traced back to sources;
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✓ Temporary isolation of segments of pipe using sand bags is often needed to force the smoke into leaking pipes; and
✓ The appearance of smoke in a waste vent pipe, at a sewer manhole, or even the base of a toilet indicates that there may be a connection between the sanitary and storm water systems.
□ Most municipal wastewater agencies will have necessary staff and equipment to conduct smoke testing and they should be contacted if cross connections with the sanitary sewer are suspected. See SC-44 Drainage System Maintenance for more information.

Dye Testing
□ Dye testing is typically performed when there is a suspected specific pollutant source and location (i.e., leaking sanitary sewer) and there is evidence of dry weather flows in the stormwater collection system.
□ Dye is released at a probable upstream source location, either the facility's sanitary or process wastewater system. The dye must be released with a sufficient volume of water to flush the system.
□ Operators then visually examine the downstream discharge points from the stormwater collection system for the presence of the dye. □ Dye testing can be performed informally using commercially available products in order to conduct an initial investigation for fairly obvious cross-connections. □ More detailed dye testing should be performed by properly trained staff and follow SOPs. Specialized equipment such as fluorometers may be necessary to detect low concentrations of dye.
□ Most municipal wastewater agencies will have necessary staff and equipment to conduct dye testing and they should be contacted if cross connections with the sanitary sewer are suspected.
1V Inspection of Drainage System
□ Closed Circuit Television (CC1V) can be employed to visually identify illicit connections to the industrial storm drainage system. Two types of CCTV systems are available: (1) a small specially designed camera that can be manually pushed on a stiff cable through storm drains to observe the interior of the piping, or (2) a larger remote operated video camera on treads or wheels that can be guided through storm drains to view the interior of the pipe.
□ CCTV systems often include a high-pressure water jet and camera on a flexible cable.

The water jet cleans debris and biofilm off the inside of pipes so the camera can take video images of the pipe condition.

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□ CCTV units can detect large cracks and other defects such as offsets in pipe ends caused by root intrusions or shifting substrate.
□ CCTV can also be used to detect dye introduced into the sanitary sewer. □ CCTV inspections require specialized equipment and properly trained staff and are generally best left to specialized contractors or municipal public works staff. fllegal Dumping
□ Substances illegally dumped on streets and into the storm drain systems and creeks may include paints, used oil and other automotive fluids, construction debris, chemicals, fresh concrete, leaves, grass clippings, and pet wastes. These wastes can cause stormwater and receiving water quality problems as well as clog the storm drain system itself.
□ Establish a system for tracking incidents. The system should be designed to identify the following:
✓ Illegal dumping hot spots;
✓ Types and quantities (in some cases) of wastes;
✓ Patterns in time of occurrence (time of day /night, month, or year); ✓ Mode of dumping (abandoned containers, "midnight dumping" from moving vehicles, direct dumping of materials, accidents/spills); ✓ An anonymous tip/reporting mechanism; and
✓ Evidence ofresponsible parties (e.g., tagging, encampments, etc.). □ One of the keys to success of reducing or eliminating illegal dumping is increasing the number of people at the facility who are aware of the problem and who have the tools to at least identify the incident, if not correct it. Therefore, train field staff to recognize and report the incidents.

Once a site has been cleaned:
□ Post "No Dumping" signs with a phone number for reporting dumping and disposal. □ Landscaping and beautification efforts of hot spots may also discourage future dumping, as well as provide open space and increase property values. □ Lighting or barriers may also be needed to discourage future dumping. □ See fact sheet SC-11 Spill Prevention, Control, and Cleanup.

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Inspection
□ Regularly inspect and clean up hot spots and other storm drainage areas where illegal dumping and disposal occurs.
□ Conduct field investigations of the industrial storm drain system for potential sources of non-stormwater discharges.
□ Pro-actively conduct investigations of high priority areas. Based on historical data, prioritize specific geographic areas and/ or incident type for pro-active investigations.

Spill and Leak Prevention and Response
□ On paved surfaces, clean up spills with as little water as possible. Use a rag for small spills, a damp mop for general cleanup, and absorbent material for larger spills. If the spilled material is hazardous, then the used cleanup materials are also hazardous and must be sent to a certified laundry (rags) or disposed of as hazardous waste. □ Never hose down or bury dry material spills. Sweep up the material and dispose of properly.
□ Use adsorbent materials on small spills rather than hosing down the spill. Remove the adsorbent materials promptly and dispose of properly. □ For larger spills, a private spill cleanup company or Hazmat team may be necessary. □ See SC-11 Spill Prevention Control and Cleanup.

Employee Training Program
□ Training of technical staff in identifying and documenting illegal dumping incidents is required. The frequency of training must be presented in the SWPPP, and depends on site-specific industrial materials and activities.
□ Consider posting a quick reference table near storm drains to reinforce training. □ Train employees to identify non-stormwater discharges and report discharges to the appropriate departments.
□ Educate employees about spill prevention and cleanup. □ Well-trained employees can reduce human errors that lead to accidental releases or spills. The employee should have the tools and knowledge to immediately begin cleaning up a spill should one occur. Employees should be familiar with the Spill Prevention Control and Countermeasure Plan. Employees should be able to identify work/jobs with high potential for spills and suggest methods to reduce possibility. □ Determine and implement appropriate outreach efforts to reduce non-permissible non-stormwater discharges.

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□ Conduct spill response drills annually (if no events occurred) in order to evaluate the effectiveness of the plan.
□ When a responsible party is identified, educate the party on the impacts of his or her actions.

Quality Assurance and Record Keeping
Performance Evaluation
□ Annually review internal investigation results; assess whether goals were met and what changes or improvements are necessary.
□ Obtain feedback from personnel assigned to respond to, or inspect for, illicit connections and illegal dumping incidents.
□ Develop document and data management procedures.
□ A database is useful for defining and tracking the magnitude and location of the problem.
□ Report prohibited non-stormwater discharges observed during the course of normal daily activities so they can be investigated, contained, and cleaned up or eliminated. □ Document that non-stormwater discharges have been eliminated by recording tests performed, methods used, dates of testing, and any on-site drainage points observed. □ Annually document and report the results of the program. □ Maintain documentation of illicit connection and illegal dumping incidents, including significant conditionally exempt discharges that are not properly managed. □ Document training activities.

Potential Limitations and Work-Arounds
Some facilities may have space constraints, limited staffing and time limitations that may preclude implementation of BMPs. Provided below are typical limitations and recommended "work-arounds."
□ Many facilities do not have accurate, up-to-date 'as-built' plans or drawings which may be necessary in order to conduct non-stormwater discharge assessments. ✓ Online tools such as Google Earth TM can provide an aerial view of the facility and may be useful in understanding drainage patterns and potential sources of non stormwater discharges
✓ Local municipal jurisdictions may have useful drainage systems maps.

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□ Video surveillance cameras are commonly used to secure the perimeter of industrial facilities against break-ins and theft. These surveillance systems may also be useful for capturing illegal dumping activities. Minor, temporary adjustments to the field of view of existing surveillance camera systems to target known or suspected problem areas may be a cost-effective way of capturing illegal dumping activities and identifying the perpetrators.

Potential Capital Facility Costs and Operation & Maintenance Requirements
Facilities
□ Capital facility cost requirements may be minimal unless cross-connections to storm drains are detected.
□ Indoor floor drains may require re-plumbing if cross-connections are detected. □ Leaky sanitary sewers will require repair or replacement which can have significant costs depending on the size and industrial activity at the facility.

Maintenance (including administrative and staffing)
□ The primary effort is for staff time and depends on how aggressively a program is implemented.
□ Costs for containment, and disposal of any leak or discharge is borne by the Discharger.
□ Illicit connections can be difficult to locate especially if there is groundwater infiltration.
□ Illegal dumping and illicit connection violations requires technical staff to detect and investigate them.

Supplemental Information
Permit Requirements
The IGP authorizes certain Non-Storm Water Discharges (NSWDs) provided BMPs are included in the SWPPP and implemented to:
□ Reduce or prevent the contact of authorized NSWDs with materials or equipment that are potential sources of pollutants;
□ Reduce, to the extent practicable, the flow or volume of authorized NSWDs; □ Ensure that authorized NSWDs do not contain quantities of pollutants that cause or contribute to an exceedance of a water quality standards (WQS); and, September 2014 California Stormwater BMP Handbook
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□ Reduce or prevent discharges of pollutants in authorized NSWDs in a manner that reflects best industry practice considering technological availability and economic practicability and achievability."
References and Resources
Center for Watershed Protection, 2004. Illicit Discharge Detection and Elimination: A Guidance Manual for Program Development and Technical Assessments, EPA Cooperative Agreement X-82907801-0.

Dublin San Ramon Sanitation District. http://www.dsrsd.com/wwrw/smoketest.html .

Sacramento Stormwater Management Program, Best Management Practices for Industrial Storm Water Pollution Control, Available online at:
http://www.msa.saccounty.net/sactostormwater/documents/guides/industrial-BMP manual.pdf.

Santa Clara Valley Urban Runoff Pollution Prevention Program. http://www.scvurppp.org .

Southern California Coastal Water Research Project, 2013. The California Microbial Source Identification Manual: A Tiered Approach to Identifying Fecal Pollution Sources to Beaches, Technical Report 804.

The Storm Water Managers Resource Center, http://www.stormwatercenter.net/ .

US EPA. National Pollutant Discharge Elimination System. Available online at:
http://cfpub.epa.gov/npdes/stormwater /menuotbmps/index.cfm?action=factsheet res ults&view=specific&bmp= 111.

WEF Press Alexandria, Virginia, 2009.Existing Sewer Evaluation and Rehabilitation:

WEF Manual of Practice No. FD-6 ASCE/EWRI Manuals and Reports on Engineering Practice No. 62, Third Edition.

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Description
Many activities that occur at an industrial or
commercial site have the potential to cause
accidental spills. Preparation for accidental
spills, with proper training and reporting
systems implemented, can minimize the
discharge of pollutants to the environment.

Spills and leaks are one of the largest
contributors of stormwater pollutants. Spill
prevention and control plans are applicable to
any site at which hazardous materials are stored
or used. An effective plan should have spill
prevention and response procedures that
identify hazardous material storage areas,
specify material handling procedures, describe
spill response procedures, and provide locations
of spill clean-up equipment and materials. The
plan should take steps to identify and
characterize potential spills, eliminate and
reduce spill potential, respond to spills when
they occur in an effort to prevent pollutants
from entering the stormwater drainage system,
and train personnel to prevent and control
future spills. An adequate supply of spill clean
up materials must be maintained onsite.

Approach
General Pollution Prevention Protocols
□ Develop procedures to prevent/mitigate
spills to storm drain systems.
□ Develop and standardize reporting
procedures, containment, storage, and
disposal activities, documentation, and
follow-up procedures.
□ Establish procedures and/or controls to
minimize spills and leaks. The procedures
should address:
✓ Description of the facility, owner and
address, activities, chemicals, and
quantities present;
Objectives
■ Cover
■ Contain
■ Educate
■ Reduce/Minimize
■ ProductSubstitution
Targeted Constituents
Sediment
Nutrients
Trash
Metals
Bacteria
Oil and Grease
Organics
Minimum BMPs Covered
8 Good Housekeeping
~ Preventative
~ Maintenance
Spill and Leak {!) Prevention and
Response
~ Material Handling &
~ WasteMana ement
~ Erosion and Sediment V Controls
✓
✓
✓
✓
~ Employee Training ✓
_ _ _ Prog_~r_a_m ________ _ 4 Quality Assurance
'-ii' Record Keeping

CALIFORNIA STORMWATER

QUALITY ASSOCIATION
✓
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✓ Facility map of the locations of industrial materials; ✓ Notification and evacuation procedures;
✓ Cleanup instructions;
✓ Identification of responsible departments; and
✓ Identify key spill response personnel.
□ Recycle, reclaim, or reuse materials whenever possible. This will reduce the amount of process materials that are brought into the facility .

Spill and Leak Prevention and Response
Spill Prevention
□ Develop procedures to prevent/mitigate spills to storm drain systems . Develop and standardize reporting procedures, containment, storage, and disposal activities, documentation, and follow-up procedures.
□ If illegal dumping is observed at the facility:
✓ Post "No Dumping" signs with a phone number for reporting illegal dumping and disposal. Signs should also indicate fines and penalties applicable for illegal dumping.
✓ Landscaping and beautification efforts may also discourage illegal dumping. ✓ Bright lighting and/ or entrance barriers may also be needed to discourage illegal dumping.
□ Store and contain liquid materials in such a manner that if the container is ruptured, the contents will not discharge, flow, or be washed into the storm drainage system, surface waters, or groundwater.
□ If the liquid is oil, gas, or other material that separates from and floats on water, install a spill control device (such as a tee section) in the catch basins that collects runoff from the storage tank area.

Preventative Maintenance
□ Place drip pans or absorbent materials beneath all mounted taps, and at all potential drip and spill locations during filling and unloading of tanks. Any collected liquids or soiled absorbent materials must be reused/recycled or properly disposed. □ Store and maintain appropriate spill cleanup materials in a location known to all near the tank storage area; and ensure that employees are familiar with the site's spill control plan and/or proper spill cleanup procedures.

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□ Sweep and clean the storage area monthly if it is paved, do not hose down the area to a storm drain.
□ Check tanks (and any containment sumps) daily for leaks and spills. Replace tanks that are leaking, corroded, or otherwise deteriorating with tanks in good condition.

Collect all spilled liquids and properly dispose of them. □ Label all containers according to their contents (e.g., solvent, gasoline). □ Label hazardous substances regarding the potential hazard ( corrosive, radioactive, flammable, explosive, poisonous).
□ Prominently display required labels on transported hazardous and toxic materials (per US DOT regulations).
□ Identify key spill response personnel.

Spill Response
□ Clean up leaks and spills immediately.
□ Place a stockpile of spill cleanup materials where it will be readily accessible (e.g., near storage and maintenance areas).
□ On paved surfaces, clean up spills with as little water as possible. ✓ Use a rag for small spills, a damp mop for general cleanup, and absorbent material for larger spills.
✓ If the spilled material is hazardous, then the used cleanup materials are also hazardous and must be sent to a certified laundry (rags) or disposed of as hazardous waste.
✓ If possible use physical methods for the cleanup of dry chemicals ( e.g., brooms, shovels, sweepers, or vacuums).
□ Never hose down or bury dry material spills. Sweep up the material and dispose of properly.
□ Chemical cleanups of material can be achieved with the use of adsorbents, gels, and foams. Use adsorbent materials on small spills rather than hosing down the spill.

Remove the adsorbent materials promptly and dispose of properly. □ For larger spills, a private spill cleanup company or Hazmat team may be necessary.

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Reporting
□ Report spills that pose an immediate threat to human health or the environment to the Regional Water Quality Control Board or local authority as location regulations dictate.
□ Federal regulations require that any oil spill into a water body or onto an adjoining shoreline be reported to the National Response Center (NRC) at 800-424-8802 (24 hour).
□ Report spills to 911 for dispatch and clean-up assistance when needed. Do not contact fire agencies directly.
□ Establish a system for tracking incidents. The system should be designed to identify the following:
✓ Types and quantities (in some cases) of wastes;
✓ Patterns in time of occurrence (time of day/night, month, or year); ✓ Mode of dumping (abandoned containers, "midnight dumping" from moving vehicles, direct dumping of materials, accidents/spills); ✓ Clean-up procedures; and
✓ Responsible parties.

Employee Training Program
□ Educate employees about spill prevention and cleanup. □ Well-trained employees can reduce human errors that lead to accidental releases or spills:
✓ The employee should have the tools and knowledge to immediately begin cleaning up a spill should one occur; and
✓ Employees should be familiar with the Spill Prevention Control and Countermeasure Plan.
□ Employees should be educated about aboveground storage tank requirements.

Employees responsible for aboveground storage tanks and liquid transfers should be thoroughly familiar with the Spill Prevention Control and Countermeasure Plan and the plan should be readily available.
□ Train employees to recognize and report illegal dumping incidents.

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Other Considerations (Limitations and Regulations)
□ State regulations exist for facilities with a storage capacity of 10,000 gallons or more of petroleum to prepare a Spill Prevention Control and Countermeasure (SPCC) Plan (Health & Safety Code Chapter 6.67).
□ State regulations also exist for storage of hazardous materials (Health & Safety Code Chapter 6.95), including the preparation of area and business plans for emergency response to the releases or threatened releases.
□ Consider requiring smaller secondary containment areas (less than 200 sq. ft.) to be connected to the sanitary sewer, prohibiting any hard connections to the storm drain.

Requirements
Costs (including capital and operation & maintenance)
□ Will vary depending on the size of the facility and the necessary controls. □ Prevention of leaks and spills is inexpensive. Treatment and/ or disposal of contaminated soil or water can be quite expensive.

Maintenance (including administrative and staffing)
□ Develop spill prevention and control plan, provide and document training, conduct inspections of material storage areas, and supply spill kits. □ Extra time is needed to properly handle and dispose of spills, which results in increased labor costs.

Supplemental Information
Further Detail of the BMP
Reporting
Record keeping and internal reporting represent good operating practices because they can increase the efficiency of the facility and the effectiveness of BMPs. A good record keeping system helps the facility minimize incident recurrence, correctly respond with appropriate cleanup activities, and comply with legal requirements. A record keeping and reporting system should be set up for documenting spills, leaks, and other discharges, including discharges of hazardous substances in reportable quantities.

Incident records describe the quality and quantity of non-stormwater discharges to the storm sewer. These records should contain the following information:
□ Date and time of the incident;
□ Weather conditions;
□ Duration of the spill/leak/ discharge;
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□ Cause of the spill/leak/ discharge;
□ Response procedures implemented;
□ Persons notified; and
□ Environmental problems associated with the spill/leak/ discharge.

Separate record keeping systems should be established to document housekeeping and preventive maintenance inspections, and training activities. All housekeeping and preventive maintenance inspections should be documented. Inspection documentation should contain the following information:
□ Date and time the inspection was performed;
□ Name of the inspector;
□ Items inspected;
□ Problems noted;
□ Corrective action required; and
□ Date corrective action was taken.

Other means to document and record inspection results are field notes, timed and dated photographs, videotapes, and drawings and maps.

Aboveground Tank Leak and Spill Control
Accidental releases of materials from aboveground liquid storage tanks present the potential for contaminating stormwater with many different pollutants. Materials spilled, leaked, or lost from tanks may accumulate in soils or on impervious surfaces and be carried away by stormwater runoff.

The most common causes of unintentional releases are:
□ Installation problems;
□ Failure of piping systems (pipes, pumps, flanges, couplings, hoses, and valves); □ External corrosion and structural failure;
□ Spills and overfills due to operator error; and
□ Leaks during pumping of liquids or gases from truck or rail car to a storage tank or vice versa.

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Storage of reactive, ignitable, or flammable liquids should comply with the Uniform Fire Code and the National Electric Code. Practices listed below should be employed to enhance the code requirements:
□ Tanks should be placed in a designated area.
□ Tanks located in areas where firearms are discharged should be encapsulated in concrete or the equivalent.
□ Designated areas should be impervious and paved with Portland cement concrete, free of cracks and gaps, in order to contain leaks and spills. □ Liquid materials should be stored in UL approved double walled tanks or surrounded by a curb or dike to provide the volume to contain 10 percent of the volume of all of the containers or 110 percent of the volume of the largest container, whichever is greater. The area inside the curb should slope to a drain. □ For used oil or dangerous waste, a dead-end sump should be installed in the drain. □ All other liquids should be drained to the sanitary sewer if available. The drain must have a positive control such as a lock, valve, or plug to prevent release of contaminated liquids.
□ Accumulated stormwater in petroleum storage areas should be passed through an oil/water separator.

Maintenance is critical to preventing leaks and spills. Conduct routine inspections and:
□ Check for external corrosion and structural failure.
□ Check for spills and overfills due to operator error. □ Check for failure of piping system (pipes, pumps, flanges, coupling, hoses, and valves).
□ Check for leaks or spills during pumping of liquids or gases from truck or rail car to a storage facility or vice versa.
□ Visually inspect new tank or container installation for loose fittings, poor welding, and improper or poorly fitted gaskets.
□ Inspect tank foundations, connections, coatings, and tank walls and piping system.

Look for corrosion, leaks, cracks, scratches, and other physical damage that may weaken the tank or container system.
□ Frequently relocate accumulated stormwater during the wet season.

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□ Periodically conduct integrity testing by a qualified professional.

Vehicle Leak and Spill Control
SC-11
Major spills on roadways and other public areas are generally handled by highly trained Hazmat teams from local fire departments or environmental health departments. The measures listed below pertain to leaks and smaller spills at vehicle maintenance shops.

In addition to implementing the spill prevention, control, and clean up practices above, use the following measures related to specific activities:

Vehicle and Equipment Maintenance
□ Perform all vehicle fluid removal or changing inside or under cover to prevent the run-on of stormwater and the runoff of spills.
□ Regularly inspect vehicles and equipment for leaks, and repair immediately. □ Check incoming vehicles and equipment (including delivery trucks, and employee and subcontractor vehicles) for leaking oil and fluids. Do not allow leaking vehicles or equipment onsite.
□ Always use secondary containment, such as a drain pan or drop cloth, to catch spills or leaks when removing or changing fluids.
□ Immediately drain all fluids from wrecked vehicles.
□ Store wrecked vehicles or damaged equipment under cover. □ Place drip pans or absorbent materials under heavy equipment when not in use. □ Use absorbent materials on small spills rather than hosing down the spill. □ Remove the adsorbent materials promptly and dispose of properly. □ Promptly transfer used fluids to the proper waste or recycling drums. Don't leave full drip pans or other open containers lying around.
□ Oil filters disposed of in trashcans or dumpsters can leak oil and contaminate stormwater. Place the oil filter in a funnel over a waste oil recycling drum to drain excess oil before disposal. Oil filters can also be recycled. Ask your oil supplier or recycler about recycling oil filters.
□ Store cracked batteries in a non-leaking secondary container. Do this with all cracked batteries, even if you think all the acid has drained out. If you drop a battery, treat it as if it is cracked. Put it into the containment area until you are sure it is not leaking.

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Vehicle and Equipment Fueling
□ Design the fueling area to prevent the run-on of stormwater and the runoff of spills:

Cover fueling area if possible.

Use a perimeter drain or slope pavement inward with drainage to a sump.

Pave fueling area with concrete rather than asphalt.
□ If dead-end sump is not used to collect spills, install an oil/water separator. □ Install vapor recovery nozzles to help control drips as well as air pollution. □ Discourage "topping-off of fuel tanks.
□ Use secondary containment when transferring fuel from the tank truck to the fuel tank.
□ Use absorbent materials on small spills and general cleaning rather than hosing down the area. Remove the absorbent materials promptly. □ Carry out all Federal and State requirements regarding underground storage tanks, or install above ground tanks.
□ Do not use mobile fueling of mobile industrial equipment around the facility; rather, transport the equipment to designated fueling areas.
□ Keep your Spill Prevention Control and Countermeasure (SPCC) Plan up-to-date. □ Train employees in proper fueling and cleanup procedures.

Industrial Spill Prevention Response
For the purposes of developing a spill prevention and response program to meet the stormwater regulations, facility managers should use information provided in this fact sheet and the spill prevention/response portions of the fact sheets in this handbook, for specific activities.

The program should:
□ Integrate with existing emergency response/hazardous materials programs (e.g., Fire Department).
□ Develop procedures to prevent/mitigate spills to storm drain systems. □ Identify responsible departments.

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□ Develop and standardize reporting procedures, containment, storage, and disposal activities, documentation, and follow-up procedures.
□ Address spills at municipal facilities, as well as public areas. □ Provide training concerning spill prevention, response and cleanup to all appropriate personnel.

References and Resources
California's Nonpoint Source Program Plan. http://www.swrcb.ca.gov/nps/index.html .

Clark County Storm Water Pollution Control Manual. Available online at:
http://www.co.clark.wa.us/pubworks/bmpman.pdf .

King County Storm Water Pollution Control Manual. Available online at:
http://dnr.metrokc.gov/wlr /dss/spcm.htm.

Orange County Stormwater Program, Best Management Practices for Industrial/Commercial Business Activities. Available online at:
http://ocwatersheds.com/documents/bmp/industrialcommercialbusinessesactivities Santa Clara Valley Urban Runoff Pollution Prevention Program. http: // www.scvurppp.org .

The Stormwater Managers Resource Center. http://www.stormwatercenter.net/ .

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Waste Handling & Disposal SC-34
Description
Improper storage and handling of solid wastes
can allow toxic compounds, oils and greases,
heavy metals, nutrients, suspended solids, and
other pollutants to enter stormwater runoff.

The discharge of pollutants to stormwater from
waste handling and disposal can be prevented
and reduced by tracking waste generation,
storage, and disposal; reducing waste
generation and disposal through source
reduction, reuse, and recycling; and preventing
run-on and runoff.

Approach
Reduce potential for pollutant discharge
through source control pollution prevention
and BMP implementation. Successful
implementation depends on effective training
of employees on applicable BMPs and general
pollution prevention strategies and objectives.

General Pollution Prevention Protocols
□ Accomplish reduction in the amount of
waste generated using the following source
controls:
✓ Production planning and sequencing;
✓ Process or equipment modification;
✓ Raw material substitution or
elimination;
✓ Loss prevention and housekeeping;
✓ Waste segregation and separation; and
✓ Close loop recycling.
□ Establish a material tracking system to
increase awareness about material usage.

This may reduce spills and minimize
contamination, thus reducing the amount of
waste produced.
□ Recycle materials whenever possible.

Objectives
■ Cover
■ Contain
■ Educate
■ Reduce/Minimize
■ ProductSubstitution
Targeted Constituents
Sediment
Nutrients
Trash
Metals _______ ✓
Bacteria ✓
Oil and Grease _____ ✓
Organics ✓
Minimum BMPs Covered
Good Housekeeping ✓
~ Preventative ✓
~ Maintenance
~ Spill and Leak Prevention ✓
W and Resp'-o_n_s_e ______ _
~ Material Handling & ✓
~ Waste Management
~ Erosion and Sediment
-ti' Controls
I;'!\ Employee Training ✓
~ Program
,. Quality Assurance Record ✓
'-i1 Keeping

CALIFORNIA STORMWATER

QUALITY ASSOCIATION
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□ Use the entire product before disposing of the container. □ To the extent possible, store wastes under cover or indoors after ensuring all safety concerns such as fire hazard and ventilation are addressed. □ Provide containers for each waste stream at each work station. Allow time after shift to clean area.

Good Housekeeping
□ Cover storage containers with leak proof lids or some other means. If waste is not in containers, cover all waste piles (plastic tarps are acceptable coverage) and prevent stormwater run-on and runoff with a berm. The waste containers or piles must be covered except when in use.
□ Use drip pans or absorbent materials whenever grease containers are emptied by vacuum trucks or other means . Grease cannot be left on the ground. Collected grease must be properly disposed of as garbage.
□ Dispose of rinse and wash water from cleaning waste containers into a sanitary sewer if allowed by the local sewer authority. Do not discharge wash water to the street or storm drain. Clean in a designated wash area that drains to a clarifier. □ Transfer waste from damaged containers into safe containers. □ Take special care when loading or unloading wastes to minimize losses. Loading systems can be used to minimize spills and fugitive emission losses such as dust or mist. Vacuum transfer systems can minimize waste loss.
□ Keep the waste management area clean at all times by sweeping and cleaning up spills immediately.
□ Use dry methods when possible (e.g., sweeping, use of absorbents) when cleaning around restaurant/food handling dumpster areas . If water must be used after sweeping/using absorbents, collect water and discharge through grease interceptor to the sewer.
□ Stencil or demarcate storm drains on the facility 's property with prohibitive message regarding waste disposal.
□ Cover waste piles with temporary covering material such as reinforced tarpaulin, polyethylene, polyurethane, polypropylene or hypalon.
□ If possible, move the activity indoor after ensuring all safety concerns such as fire hazard and ventilation are addressed.

Preventative Maintenance
□ Prevent stormwater run-on from entering the waste management area by enclosing the area or building a berm around the area.
□ Prevent waste materials from directly contacting rain.

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□ Cover waste piles with temporary covering material such as reinforced tarpaulin, polyethylene, polyurethane, polypropylene or hypalon.
□ Cover the area with a permanent roof if feasible.
□ Cover dumpsters to prevent rain from washing waste out of holes or cracks in the bottom of the dumpster.
□ Check waste containers weekly for leaks and to ensure that lids are on tightly.

Replace any that are leaking, corroded, or otherwise deteriorating. □ Sweep and clean the waste management area regularly. Use dry methods when possible (e.g., sweeping, vacuuming, use of absorbents) when cleaning around restaurant/food handling dumpster areas. If water must be used after sweeping/using absorbents, collect water and discharge through grease interceptor to the sewer.
□ Inspect and replace faulty pumps or hoses regularly to minimize the potential of releases and spills.
□ Repair leaking equipment including valves, lines, seals, or pumps promptly.

Spill Response and Prevention Procedures
□ Keep your spill prevention and plan up-to-date.
□ Have an emergency plan, equipment and trained personnel ready at all times to deal immediately with major spills.
□ Collect all spilled liquids and properly dispose of them. □ Store and maintain appropriate spill cleanup materials in a location known to all near the designated wash area.
□ Ensure that vehicles transporting waste have spill prevention equipment that can prevent spills during transport. Spill prevention equipment includes:
✓ Vehicles equipped with baffles for liquid waste; and
✓ Trucks with sealed gates and spill guards for solid waste.

Material Handling and Waste Management
Litter Control
□ Post "No Littering" signs and enforce anti-litter laws. □ Provide a sufficient number oflitter receptacles for the facility. □ Clean out and cover litter receptacles frequently to prevent spillage.

Waste Collection
□ Keep waste collection areas clean.

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□ Inspect solid waste containers for structural damage regularly. Repair or replace damaged containers as necessary.
□ Secure solid waste containers; containers must be closed tightly when not in use. □ Do not fill waste containers with washout water or any other liquid. □ Ensure that only appropriate solid wastes are added to the solid waste container.

Certain wastes such as hazardous wastes, appliances, fluorescent lamps, pesticides, etc., may not be disposed of in solid waste containers (see chemical/ hazardous waste collection section below).
□ Do not mix wastes; this can cause chemical reactions, make recycling impossible, and complicate disposal. Affix labels to all waste containers.

Chemical/Hazardous Wastes
□ Select designated hazardous waste collection areas on-site. □ Store hazardous materials and wastes in covered containers and protect them from vandalism.
□ Place hazardous waste containers in secondary containment. □ Make sure that hazardous waste is collected, removed, and disposed of only at authorized disposal areas.
□ Hazardous waste cannot be reused or recycled; it must be disposed ofby a licensed hazardous waste hauler.

Employee Training Program
□ Educate employees about pollution prevention measures and goals. □ Train employees how to properly handle and dispose of waste using the source control BMPs described above.
□ Train employees and subcontractors in proper hazardous waste management. □ Use a training log or similar method to document training. □ Ensure that employees are familiar with the site's spill control plan and/or proper spill cleanup procedures.

Quality Assurance and Record Keeping
□ Keep accurate maintenance logs that document minimum BMP activities performed for waste handling and disposal, types and quantities of waste disposed of, and any improvement actions.
□ Keep accurate logs of spill response actions that document what was spilled, how it was cleaned up, and how the waste was disposed.

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□ Establish procedures to complete logs and file them in the central office.

Potential Capital Facility Costs and Operation & Maintenance Requirements
Facilities
□ Capital costs will vary substantially depending on the size of the facility and the types of waste handled. Significant capital costs may be associated with reducing wastes by modifying processes or implementing closed-loop recycling. □ Many facilities will already have indoor covered areas where waste materials will be stored and will require no additional capital expenditures for providing cover. □ If outdoor storage of wastes is required, construction of berms or other means to prevent stormwater run-on and runoff may require appropriate constructed systems for containment.
□ Capital investments will likely be required at some sites if adequate cover and containment facilities do not exist and can vary significantly depending upon site conditions.

Maintenance
□ Check waste containers weekly for leaks and to ensure that lids are on tightly.

Replace any that are leaking, corroded, or otherwise deteriorating. □ Sweep and clean the waste management area regularly. Use dry methods when possible (e.g., sweeping, use of absorbents) when cleaning around restaurant/food handling dumpster areas. If water must be used after sweeping/using absorbents, collect water and discharge through grease interceptor to the sewer. □ Inspect and replace faulty pumps or hoses regularly to minimize the potential of releases and spills.
□ Repair leaking equipment including valves, lines, seals, or pumps promptly.

References and Resources
Minnesota Pollution Control Agency, Industrial Stormwater Best Management Practices Guidebook. Available online at: http://www.pca.state.mn.us/index.php/view document.html?gid=1055z.

New Jersey Department of Environmental Protection, 2013. Basic Industrial Stormwater General Permit Guidance Document NJPDES General Permit No NJ0088315, Revised. Available online at:
http://www.nj.gov/dep/dwq/pdf/5G2 guidance color.pdf.

Orange County Stormwater Program, Best Management Practices for Industrial/Commercial Business Activities. Available online at:
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Oregon Department of Environmental Quality, 2013. Industrial Stormwater Best Management Practices Manual-BMP 26 Fueling and Liquid Loading/Unloading Operations. Available online at:
http: // www.deq.state.or.us/wq/wgpermit/ docs/IndBMP021413.pdf.

Sacramento Stormwater Management Program. Best Management Practices for Industrial Storm Water Pollution Control. Available online at:
http://www.msa.saccounty.net/sactostormwater/documents/guides/industrial-BMP manual.pdf.

Sacramento County Environmental Management Stormwater Program: Best Management Practices. Available online at:
http://www.emd.saccounty.net/EnvHealth/Stormwater/Stormwater-BMPs.html .

Santa Clara Valley Urban Runoff Pollution Prevention Program. http://www.scvurppp w2k.com/
US EPA. National Pollutant Discharge Elimination System -Industrial Fact Sheet Series for Activities Covered by EPA's Multi Sector General Permit. Available online at:
http://cfpub.epa.gov/npdes/stormwater /swsectors.cfm.

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Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA
Appendix E
Soils Report
564

565
ladden Ill Ill ng1neer1ng
45090 Golf Center Parkway, Suite F, Indio, CA 92201 (760) 863-0713 Fax (760) 863-0847 6782 Stanton Avenue, Suite C, Buena Park, CA 90621 (714) 523-0952 Fax (714) 523-1369 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863 www.Sladdenengineering.com
December 7, 2022 Project No. 544-22493
22-12-717
Evangelos Pistiolis
40-315 Challa Lane
Rancho Mirage, California 92270
Project:

Subject:

Proposed Residential Subdivision
APN's 689-130-005, 014,017,018
APN' s 689-090-003 & 689-140-022
Peterson Road
Rancho Mirage, California
Geotechnical Update
Ref: Geotechnical Investigation report prepared by Sladden Engineering dated October 19, 2010; Project No. 544-10159, Report No. 10-10-237
In accordance with your request, we have reviewed the above referenced Geotechnical Investigation report as it relates to the design and construction of the residential subdivision proposed for the approximately 20-acre site (identified as APN's 689-130-005, 014,017,018, 689- 090-003 & 689-140-022) located on Peterson Road in the City of Rancho Mirage, California. It is our understanding that the proposed residential structures will be of relatively lightweight wood-frame or light gauge steel-frame construction and will be supported by conventional shallow spread footings and concrete slabs on grade.

The referenced report includes recommendations pertaining to the construction of residential structure foundations. Based upon our review of the referenced report, our previous experience of the project site and our understanding of the proposed construction, it is our opinion that the structural values and remedial grading recommendations included in this report remain applicable for the design and construction of the residential subdivision development.

The proposed residential buildings may be supported upon conventional shallow spread footings. Conventional shallow spread footings should be bottomed into properly compacted engineered fill material a minimum of 12 inches below lowest adjacent grade. Continuous footings should be at least 12 inches wide and isolated pad footings should be at least 2 feet wide.

Continuous footings and isolated pad footings should be designed utilizing allowable bearing pressures of 1800 psf and 2000 psf, respectively. Allowable increases of 250 psf for each additional 1 foot of width and 250 psf for each additional 6 inches of depth may be utilized, if desired. The maximum allowable bearing pressure should be 2500 psf. The recommended allowable bearing pressures may be increased by one-third for wind and seismic loading.

Sladden Engineering

566
December 7, 2022 -2-Project No. 544-22493
22-12-717
Static settlement resulting from the anticipated foundation loads should be tolerable provided that the recommendations included in this report are considered in foundation design and construction. The ultimate static settlement is expected to be less than 1.0 inch when using the recommended allowable foundation bearing pressures. As a practical matter, differential static settlement between footings can be assumed as one-half of the total static settlement.

Lateral forces may be resisted by friction along the base of the foundations and passive resistance along the sides of the footings. A friction coefficient of 0.45 times the normal dead load forces is recommended for use in design. Passive resistance may be estimated using an equivalent fluid weight of 300 pd. If used in combination with the passive resistance, the frictional resistance should be reduced by one third.

The bearing soil is non-expansive and falls within the "very low" expansion category in accordance with 2019 California Building Code (CBC) classification criteria. Slab thickness and reinforcement should be determined by the structural engineer. We recommend a minimum floor slab thickness of 4.0 inches and minimum reinforcement of #3 bars at 24 inches on center in both directions. All slab reinforcement should be supported on concrete chairs to ensure that reinforcement is placed at slab mid-height.

Slabs with moisture sensitive surfaces should be underlain with a moisture vapor retarder consisting of a polyvinyl chloride membrane such as 10-mil Visqueen, or equivalent. All laps within the membrane should be sealed and at least 2 inches of clean sand should be placed over the membrane to promote uniform curing of the concrete. To reduce the potential for punctures, the membrane should be placed on a pad surface that has been graded smooth without any sharp protrusions. If a smooth surface cannot be achieved by grading, consideration should be given to placing a 1-inch thick leveling course of sand across the pad surface prior to placement of the membrane.

Minor retaining walls may be necessary to accomplish the proposed construction. Lateral pressures for use in retaining wall design may be estimated using an equivalent fluid weight of 35 pd for level drained native backfill conditions. For walls that are to be restrained at the top, the equivalent fluid weight should be increased to 55 pd for level drained native backfill conditions. Back drains should be provided for the full height of the walls. Seismic pressures should be incorporated into any retaining walls greater than 6 feet in height. Seismic deign pressures may be provided once specific wall heights and locations are known.

The seismic design category for a structure may be determined in accordance with Section 1613 of the 2019 CBC or ASCE7-16. According to the 2019 CBC, Site Class D may be used to estimate design seismic loading for the proposed structures. The 2019 CBC Site Specific Seismic Hazard Analyses are attached. The project Structural Engineer should verify that all design parameters provided are applicable for the subject project.

Sladden Engineering

567
December 7, 2022 -3-Project No. 544-22493
22-12-717
In order to provid e fo r firm and uniform found at io n bearing condi ti o ns, the primary foundation bear in g soil shoul d be ove r-excava ted and r ccom pacted. Over -excava tion shou ld ex t end to a minimum d epth of 5 feet below ex istin g gra d e o r 5 f eet bel ow the b otto m of th e foot ings, wh ich eve r is d ee per . Once adequate r emova l s h ave been verifi ed, the exposed native soi l shou ld be moi sture conditioned to near opt imu m m oisture content and compacted to at l eas t 90 percen t r elative com pa cti on. Th e previously r emoved ma terial m ay t hen be placed in thin lifts at n ear o ptimum moi sture content and compa cted lo at leas t 90 p e rcent r elati ve compaction compac ted eng in ee r ed fil l. Rem ovals should ex tend at least 5 feet latera ll y beyo nd t he foo ting li mits.

W e apprecia te th e opportunity to provid e serv ice to you o n thi s p roject. If you have any qu es tions regardin g th is letter or th e r efer enced report, p lease contact the undersi g ned.

Resp ec tfu ll y su b mit ted,

SLADDEN ENGINEERING
Brett L. A nd er son
Pr i ncipal En g i n ee r
SER/cg
Copies: pdf/ Addressee
Matthew J. Cohrt
Prin ci pa l Geol ogi st
Stadden E11gi11eeri11g

56 8
Project: Peterson Road, Rancho Mirage
Project Number: 544-22493
Client: Evangelos Pistiolis
Site lat/Long: 33.7690/-116.4391
Contro lling Seism ic Source: San Andreas

REFERENCE NOTAT ION
Site Class C, D, D default, or E
Site Class D -Table 11.4-1 F.

Site Class D -21.3{i i) Fv

0.2•(S0.ifS05) To
Soi/Sr,, Ts
Fundamental Period {12 .8.2) T
Seismic Design Maps or Fig 22-14 TL
VALU E
D measured

1.0 2.5

0.140

0.698
Period
8 Equation 11.4-4 -2/3*SM1 501 0,709~
Equation 11.4-2 -Fv*S1 SMl 1.0S42'
Cr -At Perods =1.0, Cr=CR 1 ¼1 0.894
• Cod. based deslen nlu, See accompanying data for Site Specific Design values. ~
Stadden Engin eering

RISK COEFFICIENT

REFE RENCE NOTATION VALU E
Fv (Table 11.4-2)[Used for General Spectrum) Fv 1.7
Design Maps s, I 1.524
Design Maps S1 I 0.626
Equation 11.4-1 -F A *S5 SMs _52
Equation 11.4-3 -2/3*5.,,5 Sos 1.011:·
Design Maps PGA I 0.668
Table 11.8-1 F PGA 1.1
Equation 11.8-1-FPGA*PGA PGA.,, 0.735
Section 21.5.3 80"/4 of PGA.,, 0.588
Design Maps ~ I 0.913
Design Maps ¼1 I 0.894
Cr -At Periods between 0.2 and 1.0 Period Cr
use trendline formula to complete 0.200 0.913

0.300 0.911

0.400 0.908

0.500 0.906

0.600 0.904

0.680 0.902

1.000 0.894
Mapped values from https://seism1cmaps.org/

56 9
(g)
Sladden Engineering
Period UGHM

0.010 0.84,,

0.100 J..4111

0.200 1.868

0.300 2.145

0.500 2123

0.750 750

1.000 1.497

2.000 0.867

3.000 0.597

4.000 0.441

5.000 0.337
3,,00

2.50 RTHM

0.816

1.392

1.853

2.050

1.967

1.606

1.346

0.710

0.527

0.386

0.297
Max Di rectional
Scale Factor'

1.19 1.19

1.20 1.22

1.23 1.24

1.24 1.24

1.25 1.25

1.26 PROBABILISTIC SPECTRA'
2% in 50 year Exceedence
Probabilistic
MCE

0.971

1.656
2224

2.501

2.419

1.991

1.669
0 .955
0 .659

0.483
0 .374
Project No: 544-22493
1 Data Sources:
https://earthguake.usn.gov/hazards/interactive/
https ://earthquake.usgs.gov/designmaps/rtgm/
2 Shahi-Ba ker RotD100/RotD50 Factors (2014)
Probabilistic PGA: 0.844
Is Probabilistic Sac....,<l.2F,? NO
PROBABILISTIC MCER ,_UGHM
SPECTRAL RESPONSE ACCELERATIONS 1---RTHM
---Probabilistic MCER
~

2.00 ~ I t •
~
~1 so ~I/ i ~,,; ' i ,, ··1 f . ' -<· t I
.!!
8 ~
LOO Jf : • ~--: I ~ I
QS0 -1--------+--

0.000 1.000 2.000 3.000
Period (seconds)
4000 5.000

57 0
~
Sladden Engineering
Period

0.010

0.020

0.030

0.050

0.075

0.100

0.150

0.200

0.250

0.300

0.400

0.500

0.750

1.000

1.500

2.000

3.000

4.000

5.000

2.50 2.00
j
~ 1.50 ..._
C
.!!
!
.!!
8 ;;t l.00

DETERMINISTIC SPECTRUM
largost Amplitudes of Ground Motions Considering Al sourcos calculated usi,. Weighted M•n of Attenuation Equations' Ccntrolli,. source: San Andreas
Is Probabilistic Sa1_, =F,... •o.s? YES
1 HGAWest 2 GMPE worbhee! one!
Uniform Califcmt. E,arthquake RuptUre
fore<as,. Version 3. (UCERF3) -Tome
Dependent Model
1 Sls•hH!•ker Roclll00/RotD50 facton
[20141
_._OeterminisOC:

MCER

0.50 -,.---,...,....--............... -+-......---,---.---+-----~-..-,.....,.---+----.__-+ + -i---j ~00------------------------------------------'

0.000 1.000 2.000 3.000 4.000 5.000
___ P_en_·~ {seconds)

57 1
~
Period Probabilistic
MCE

0.010 0.971

0.100 1.656
0 .200 2 .224

0.300 2 .501
0 .500 2.419

0.750 1 .991
1 .000 1.669
2 .000 0.95S

3.000 0 .659

4.000 0.483
5 .000 0.374
SDS:

SOl:

SMS:

SM1:

Site Specific PGAm:

SITE SPEQFIC SPECTRA ------
Deterministic Site-Specific

MCE MCE

0.772 0.772

1.197 1.1 97

1.669 1.669

1.882 1.882

1.840 1.840

1.495 1.495

1.252 1.252

0.688 0.688

0.476 0.476

0.337 0.337

0.253 0.2 53
ASCE 7-16: Section 21.4
Site Specific
Calculated I Design
Value Value

1.129 I 1.129

0.952

1.694

1.429

0.649

0.952

1.694

1.429

0.649
Site Class: D measured
Seismic Design Category-Short* D
Seismic Design Category-ls* D
* Risk Categories I, II, or Ill
Sladden Engineering
Design Response
Spectrum (Sa )
ASCE 7 SECTION 11.4.6 80"/4 General
Period General Spectrum Response Spectrum

0.S15 0.005 0.428 0.343

0.798 0.010 0.450 0.360

1.113 0.020 0.494 0.395
l.255 0 .030 0.537 0.430

1.2is 0.050 0.625 0 .500
0 .997 0 .060 0.668 0.535

0.835 0 .075 0.734 0.587
0 .459 0 .090 0.799 0.639

0.317 0.100 0.843 0.674
0 .225 0.110 0.887 0.709

0.169 0.120 0.930 0.744

0.136 1.000 0.800

0.150 1 .016 0.813

0.160 1.016 0 .813

0.170 1.016 0.813
0 .180 1.016 0.813

0.200 1.016 0.813
0 .250 1.016 0.813

0.300 1.016 0.813

0.400 1.016 0.813

0.500 1.016 0.813

0.600 1.016 0.813

0.690 1.016 0.813

0.750 0.946 0.757
0 .850 0.835 0.668
0 .900 0.788 0.631

0.950 0.747 0.597

1.000 0.709 0.568

1.500 0.473 0.378

2.000 0.355 0.284

3.000 0 .236 0.189

4.000 0.177 0 .142

5.000 0.142 0.114
Project No: 544-22493

57 2

3.00 SPECTRAL RESPONSE ACCELERATIONS
+
f

2.50 I "' : ' • I I I I
➔

2.00 I / ., I I I I ' ' I • I
t i ill .. ·\ N .. • I • , I l I ._1.50 ., ·7' . ~ '
Qi .., ..,
<t

1.00 ,JJ.auu ueJ 0(

0.5 0 K
0 .00

0.000
½-
I -+
-1-
-t
1 .CXXl
-
l

2.CXXl 3.000 4.000 S.CXXl
Period (secon ds)
-Probab ilistic MCE
-Deterministic MCE
-,,_ Site-Specific MCE
Design Response Spectrum
~ ASCE 7 Sect ion 11.4.6 General Spectrum
~ 80% Gener al Response Spectrum

Whitewater River Region WQMP
TTM 38971-Rancho Mirage, CA
Appendix F
Hydrology Report, Structural BMP and/or Retention Facility Sizing Calculations and Design Details
573

PRELIMINARY HYDROLOGY STUDY
for
TENTATIVE TRACT MAP 38971

RANCHO MIRAGE, CALIFORNIA
Prepared for:

Horti Caesaris LLC
9401 Wilshire Blvd., 12th Floor
Beverly Hills, CA 90212-2928
Prepared by:FOMOTOR

ENGINEERING
225 S. Civic Drive, Suite 1-5
Palm Springs, California 92262
Phone (760)323-1842
Fax (760)323-1742
July 9, 2024
574

Table of Contents
I.Report
II.Reference Material
a.Vicinity Map
b.Flood Insurance Rate Map ( U.S. Department of Homeland Security Federal Emergency Management Act Map Service Center)
c.Hydrologic Soils Group Maps (From US Department of Agriculture Soil Conservation Service)
d.Point Precipitation Frequency (National Oceanic and Atmospheric Administration’s Precipitation Frequency Data Server)
e.City of Rancho Mirage Retention Basin Standard Detail 310. f.Impervious Cover for Developed Areas – Plate D-5.6 (RCFC&WCD Hydrology Manual).
g.Runoff Index– Plate D-5.5-Pg 1 (RCFC&WCD Hydrology Manual). h.Pervious Area Loss Rate – Plate E-6.2 (RCFC&WCD Hydrology Manual).
i.SUH Shortcut Method Basin and Runoff Calculation Spreadsheet VI.Exhibit
i.Preliminary Hydrology Exhibit
575

FOMOTOR ENGINEERING Preliminary Hydrology Study
Tentative Tract Map 38971

Page 1 ends

Rancho Mirage City CouncilDecember 4, 2025

Rancho Mirage City Council
December 4, 2025