Agenda packet, regular meeting — Coachella City Council, December 17, 2025 (part 4 of 7)

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.801 0.19 0.72 0.61 6.41 1850.53
58 290 4.83 2.4 0.801 0.19 0.72 0.61 6.41 1850.53
59 295 4.92 2.5 0.834 0.19 0.75 0.64 6.76 1956.31
60 300 5.00 2.6 0.867 0.19 0.78 0.67 7.12 2062.10
61 305 5.08 3.1 1.034 0.19 0.93 0.84 8.88 2591.02
62 310 5.17 3.6 1.201 0.19 1.08 1.01 10.64 3119.94
63 315 5.25 3.9 1.301 0.19 1.17 1.11 11.70 3437.30
64 320 5.33 4.2 1.401 0.19 1.26 1.21 12.76 3754.65
65 325 5.42 4.7 1.568 0.19 1.41 1.37 14.52 4283.57
66 330 5.50 5.6 1.868 0.19 1.68 1.67 17.69 5235.64
67 335 5.58 1.9 0.634 0.19 0.57 0.44 4.65 1321.61
68 340 5.67 0.9 0.300 0.19 0.27 0.11 1.12 263.76
69 345 5.75 0.6 0.200 0.19 0.18 0.01 0.06 0.00
70 350 5.83 0.5 0.167 0.19 0.15 0.02 0.18 0.00
71 355 5.92 0.3 0.100 0.19 0.09 0.01 0.11 0.00
72 360 6.00 0.2 0.067 0.19 0.06 0.01 0.07 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.64
FLOOD VOLUME (acft) 1.45
FLOOD VOLUME (cuft) 63008.73
REQUIRED STORAGE (acft) 1.32
REQUIRED STORAGE (cuft) 57661.37
PEAK FLOW RATE (cfs) 17.69
Plate E-2.2

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Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 10.570 CONSTANT LOSS RATE-in/hr n/a UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.1942 LAG TIME - MINUTES 1.62 MINIMUM LOSS RATE (for var. loss) - in/hr 0.097 UNIT TIME-PERCENT OF LAG 925.8 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 4.47 C 0.00180
PERCOLATION RATE (cfs) 0.24
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.036 0.343 0.032 0.004 0.04 0.00
2 30 0.50 0.3 0.054 0.339 0.048 0.005 0.06 0.00
3 45 0.75 0.3 0.054 0.335 0.048 0.005 0.06 0.00
4 60 1.00 0.4 0.072 0.331 0.064 0.007 0.08 0.00
5 75 1.25 0.3 0.054 0.327 0.048 0.005 0.06 0.00
6 90 1.50 0.3 0.054 0.323 0.048 0.005 0.06 0.00
7 105 1.75 0.3 0.054 0.319 0.048 0.005 0.06 0.00
8 120 2.00 0.4 0.072 0.316 0.064 0.007 0.08 0.00
9 135 2.25 0.4 0.072 0.312 0.064 0.007 0.08 0.00
10 150 2.50 0.4 0.072 0.308 0.064 0.007 0.08 0.00
11 165 2.75 0.5 0.089 0.304 0.080 0.009 0.09 0.00
12 180 3.00 0.5 0.089 0.300 0.080 0.009 0.09 0.00
13 195 3.25 0.5 0.089 0.297 0.080 0.009 0.09 0.00
14 210 3.50 0.5 0.089 0.293 0.080 0.009 0.09 0.00
15 225 3.75 0.5 0.089 0.289 0.080 0.009 0.09 0.00
16 240 4.00 0.6 0.107 0.286 0.097 0.011 0.11 0.00
17 255 4.25 0.6 0.107 0.282 0.097 0.011 0.11 0.00
18 270 4.50 0.7 0.125 0.278 0.113 0.013 0.13 0.00
19 285 4.75 0.7 0.125 0.275 0.113 0.013 0.13 0.00
20 300 5.00 0.8 0.143 0.271 0.129 0.014 0.15 0.00
21 315 5.25 0.6 0.107 0.268 0.097 0.011 0.11 0.00
22 330 5.50 0.7 0.125 0.264 0.113 0.013 0.13 0.00
23 345 5.75 0.8 0.143 0.261 0.129 0.014 0.15 0.00
24 360 6.00 0.8 0.143 0.257 0.129 0.014 0.15 0.00
25 375 6.25 0.9 0.161 0.254 0.145 0.016 0.17 0.00
26 390 6.50 0.9 0.161 0.251 0.145 0.016 0.17 0.00
27 405 6.75 1.0 0.179 0.247 0.161 0.018 0.19 0.00
28 420 7.00 1.0 0.179 0.244 0.161 0.018 0.19 0.00
29 435 7.25 1.0 0.179 0.241 0.161 0.018 0.19 0.00
30 450 7.50 1.1 0.197 0.237 0.177 0.020 0.21 0.00
31 465 7.75 1.2 0.215 0.234 0.193 0.021 0.23 0.00
32 480 8.00 1.3 0.232 0.231 0.209 0.002 0.02 0.00
33 495 8.25 1.5 0.268 0.228 0.241 0.041 0.43 167.88
34 510 8.50 1.5 0.268 0.224 0.241 0.044 0.46 198.07
35 525 8.75 1.6 0.286 0.221 0.257 0.065 0.68 398.09
36 540 9.00 1.7 0.304 0.218 0.274 0.086 0.91 597.84
37 555 9.25 1.9 0.340 0.215 0.306 0.125 1.32 967.41
38 570 9.50 2.0 0.358 0.212 0.322 0.146 1.54 1166.63
39 585 9.75 2.1 0.375 0.209 0.338 0.166 1.76 1365.57
40 600 10.00 2.2 0.393 0.206 0.354 0.187 1.98 1564.23
41 615 10.25 1.5 0.268 0.203 0.241 0.065 0.69 401.88
42 630 10.50 1.5 0.268 0.200 0.241 0.068 0.72 429.90
43 645 10.75 2.0 0.358 0.197 0.322 0.160 1.70 1308.09
44 660 11.00 2.0 0.358 0.194 0.322 0.163 1.73 1335.54
45 675 11.25 1.9 0.340 0.191 0.306 0.148 1.57 1192.62
46 690 11.50 1.9 0.340 0.189 0.306 0.151 1.60 1219.49
47 705 11.75 1.7 0.304 0.186 0.274 0.118 1.25 905.90
48 720 12.00 1.8 0.322 0.183 0.290 0.139 1.47 1102.28
49 735 12.25 2.5 0.447 0.180 0.402 0.267 2.82 2318.92
50 750 12.50 2.6 0.465 0.178 0.418 0.287 3.04 2514.71
51 765 12.75 2.8 0.501 0.175 0.451 0.326 3.44 2880.29
52 780 13.00 2.9 0.519 0.172 0.467 0.346 3.66 3075.47
53 795 13.25 3.4 0.608 0.170 0.547 0.438 4.63 3950.71
54 810 13.50 3.4 0.608 0.167 0.547 0.441 4.66 3975.18
55 825 13.75 2.3 0.411 0.165 0.370 0.247 2.61 2128.32
56 840 14.00 2.3 0.411 0.162 0.370 0.249 2.63 2152.16
57 855 14.25 2.7 0.483 0.160 0.434 0.323 3.42 2856.04
58 870 14.50 2.6 0.465 0.157 0.418 0.308 3.25 2709.14
59 885 14.75 2.6 0.465 0.155 0.418 0.310 3.28 2732.00
60 900 15.00 2.5 0.447 0.152 0.402 0.295 3.11 2584.44
61 915 15.25 2.4 0.429 0.150 0.386 0.279 2.95 2436.54
62 930 15.50 2.3 0.411 0.148 0.370 0.263 2.78 2288.29
63 945 15.75 1.9 0.340 0.146 0.306 0.194 2.05 1629.43
64 960 16.00 1.9 0.340 0.143 0.306 0.196 2.08 1650.58
65 975 16.25 0.4 0.072 0.141 0.064 0.007 0.08 0.00
66 990 16.50 0.4 0.072 0.139 0.064 0.007 0.08 0.00
67 1005 16.75 0.3 0.054 0.137 0.048 0.005 0.06 0.00
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

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Item 2.

EFFECTIVE RAIN CALCULATION FORM
68 1020 17.00 0.3 0.054 0.135 0.048 0.005 0.06 0.00
69 1035 17.25 0.5 0.089 0.133 0.080 0.009 0.09 0.00
70 1050 17.50 0.5 0.089 0.131 0.080 0.009 0.09 0.00
71 1065 17.75 0.5 0.089 0.129 0.080 0.009 0.09 0.00
72 1080 18.00 0.4 0.072 0.127 0.064 0.007 0.08 0.00
73 1095 18.25 0.4 0.072 0.125 0.064 0.007 0.08 0.00
74 1110 18.50 0.4 0.072 0.123 0.064 0.007 0.08 0.00
75 1125 18.75 0.3 0.054 0.121 0.048 0.005 0.06 0.00
76 1140 19.00 0.2 0.036 0.120 0.032 0.004 0.04 0.00
77 1155 19.25 0.3 0.054 0.118 0.048 0.005 0.06 0.00
78 1170 19.50 0.4 0.072 0.116 0.064 0.007 0.08 0.00
79 1185 19.75 0.3 0.054 0.115 0.048 0.005 0.06 0.00
80 1200 20.00 0.2 0.036 0.113 0.032 0.004 0.04 0.00
81 1215 20.25 0.3 0.054 0.112 0.048 0.005 0.06 0.00
82 1230 20.50 0.3 0.054 0.110 0.048 0.005 0.06 0.00
83 1245 20.75 0.3 0.054 0.109 0.048 0.005 0.06 0.00
84 1260 21.00 0.2 0.036 0.108 0.032 0.004 0.04 0.00
85 1275 21.25 0.3 0.054 0.106 0.048 0.005 0.06 0.00
86 1290 21.50 0.2 0.036 0.105 0.032 0.004 0.04 0.00
87 1305 21.75 0.3 0.054 0.104 0.048 0.005 0.06 0.00
88 1320 22.00 0.2 0.036 0.103 0.032 0.004 0.04 0.00
89 1335 22.25 0.3 0.054 0.102 0.048 0.005 0.06 0.00
90 1350 22.50 0.2 0.036 0.101 0.032 0.004 0.04 0.00
91 1365 22.75 0.2 0.036 0.100 0.032 0.004 0.04 0.00
92 1380 23.00 0.2 0.036 0.099 0.032 0.004 0.04 0.00
93 1395 23.25 0.2 0.036 0.099 0.032 0.004 0.04 0.00
94 1410 23.50 0.2 0.036 0.098 0.032 0.004 0.04 0.00
95 1425 23.75 0.2 0.036 0.097 0.032 0.004 0.04 0.00
96 1440 24.00 0.2 0.036 0.097 0.032 0.004 0.04 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.79
FLOOD VOLUME (acft) 1.58
FLOOD VOLUME (cuft) 68652.95
REQUIRED STORAGE (acft) 1.29
REQUIRED STORAGE (cuft) 56203.65
PEAK FLOW (cfs) 4.66
Plate E-2.2

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Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

INCR TOTAL INCR TOTAL INCR TOTAL
(ft) (ft) (sf) (sf) (cuft) (cuft) (acre-ft)
465 0 0 15600 0 0 0.00
466 1 1 1520 17120 16360 16360 0.38
467 1 2 1590 18710 17915 34275 0.79
468 1 3 1640 20350 19530 53805 1.24
468.5 0.5 3.5 850 21200 10388 64193 1.47

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.24 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.24 cfs
Basin Characteristics

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Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 1.44 433 433 73 360 465.02 360 0.01
2 10 1.44 433 793 73 721 465.04 721 0.02
3 15 0.91 272 992 73 920 465.06 920 0.02
4 20 1.98 594 1,514 73 1,442 465.09 1,442 0.03
5 25 1.98 594 2,036 73 1,963 465.12 1,963 0.05
6 30 2.79 836 2,800 73 2,727 465.17 2,727 0.06
7 35 1.98 594 3,322 73 3,249 465.20 3,249 0.07
8 40 2.79 836 4,085 73 4,013 465.25 4,013 0.09
9 45 2.79 836 4,849 73 4,776 465.29 4,776 0.11
10 50 1.98 594 5,371 73 5,298 465.32 5,298 0.12
11 55 2.25 675 5,973 73 5,901 465.36 5,901 0.14
12 60 2.79 836 6,737 73 6,664 465.41 6,664 0.15
13 65 3.86 1,159 7,823 73 7,751 465.47 7,751 0.18
14 70 3.86 1,159 8,910 73 8,837 465.54 8,837 0.20
15 75 3.86 1,159 9,996 73 9,924 465.61 9,924 0.23
16 80 3.33 998 10,921 73 10,849 465.66 10,849 0.25
17 85 4.94 1,482 12,331 73 12,258 465.75 12,258 0.28
18 90 5.21 1,562 13,820 73 13,748 465.84 13,748 0.32
19 95 4.40 1,320 15,068 73 14,996 465.92 14,996 0.34
20 100 5.21 1,562 16,558 73 16,485 466.01 16,485 0.38
21 105 6.82 2,046 18,532 73 18,459 466.12 18,459 0.42
22 110 6.28 1,885 20,344 73 20,272 466.22 20,272 0.47
23 115 5.75 1,724 21,995 73 21,923 466.31 21,923 0.50
24 120 6.01 1,804 23,727 73 23,655 466.41 23,655 0.54
25 125 6.28 1,885 25,540 73 25,467 466.51 25,467 0.58
26 130 9.24 2,772 28,239 73 28,167 466.66 28,167 0.65
27 135 11.39 3,418 31,585 73 31,512 466.85 31,512 0.72
28 140 7.36 2,208 33,720 73 33,647 466.96 33,647 0.77
29 145 16.23 4,870 38,517 73 38,445 467.21 38,445 0.88
30 150 17.58 5,273 43,718 73 43,645 467.48 43,645 1.00
31 155 20.00 5,999 49,644 73 49,572 467.78 49,572 1.14
32 160 13.81 4,144 53,716 73 53,643 467.99 53,643 1.23
33 165 3.33 998 54,641 73 54,568 468.04 54,568 1.25
34 170 2.79 836 55,405 73 55,332 468.07 55,332 1.27
35 175 2.79 836 56,168 73 56,096 468.11 56,096 1.29
36 180 0.16 48 56,144 73 56,072 468.11 56,072 1.29

BALANCE IN
BASIN
TIME
Basin Depth Analysis

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Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.18 53 53 73 - 465.00 - 0.00
2 10 0.06 19 19 73 - 465.00 - 0.00
3 15 0.06 19 19 73 - 465.00 - 0.00
4 20 0.06 19 19 73 - 465.00 - 0.00
5 25 0.06 19 19 73 - 465.00 - 0.00
6 30 0.42 125 125 73 52 465.00 52 0.00
7 35 0.42 125 177 73 104 465.01 104 0.00
8 40 0.42 125 229 73 157 465.01 157 0.00
9 45 0.42 125 281 73 209 465.01 209 0.00
10 50 0.42 125 334 73 261 465.02 261 0.01
11 55 0.42 125 386 73 313 465.02 313 0.01
12 60 0.77 231 544 73 471 465.03 471 0.01
13 65 0.77 231 702 73 629 465.04 629 0.01
14 70 0.77 231 860 73 787 465.05 787 0.02
15 75 0.77 231 1,018 73 945 465.06 945 0.02
16 80 0.77 231 1,176 73 1,103 465.07 1,103 0.03
17 85 0.77 231 1,334 73 1,261 465.08 1,261 0.03
18 90 0.77 231 1,492 73 1,419 465.09 1,419 0.03
19 95 0.77 231 1,650 73 1,577 465.10 1,577 0.04
20 100 0.77 231 1,808 73 1,735 465.11 1,735 0.04
21 105 0.77 231 1,966 73 1,893 465.12 1,893 0.04
22 110 0.77 231 2,123 73 2,051 465.13 2,051 0.05
23 115 0.77 231 2,281 73 2,209 465.14 2,209 0.05
24 120 1.12 336 2,545 73 2,473 465.15 2,473 0.06
25 125 0.77 231 2,703 73 2,631 465.16 2,631 0.06
26 130 1.12 336 2,967 73 2,894 465.18 2,894 0.07
27 135 1.12 336 3,231 73 3,158 465.19 3,158 0.07
28 140 1.12 336 3,494 73 3,422 465.21 3,422 0.08
29 145 1.12 336 3,758 73 3,686 465.23 3,686 0.08
30 150 1.12 336 4,022 73 3,949 465.24 3,949 0.09
31 155 1.12 336 4,286 73 4,213 465.26 4,213 0.10
32 160 1.12 336 4,550 73 4,477 465.27 4,477 0.10
33 165 1.47 442 4,919 73 4,846 465.30 4,846 0.11
34 170 1.47 442 5,289 73 5,216 465.32 5,216 0.12
35 175 1.47 442 5,658 73 5,586 465.34 5,586 0.13
36 180 1.47 442 6,028 73 5,955 465.36 5,955 0.14
37 185 1.47 442 6,397 73 6,325 465.39 6,325 0.15
38 190 1.83 548 6,873 73 6,800 465.42 6,800 0.16
39 195 1.83 548 7,348 73 7,275 465.44 7,275 0.17
40 200 1.83 548 7,823 73 7,751 465.47 7,751 0.18
41 205 2.18 654 8,404 73 8,332 465.51 8,332 0.19
42 210 2.53 759 9,091 73 9,019 465.55 9,019 0.21
43 215 2.88 865 9,884 73 9,811 465.60 9,811 0.23
44 220 2.88 865 10,677 73 10,604 465.65 10,604 0.24
45 225 3.24 971 11,575 73 11,503 465.70 11,503 0.26
46 230 3.24 971 12,474 73 12,401 465.76 12,401 0.28
47 235 3.59 1,077 13,478 73 13,405 465.82 13,405 0.31
48 240 3.59 1,077 14,482 73 14,409 465.88 14,409 0.33
49 245 3.94 1,183 15,592 73 15,520 465.95 15,520 0.36
50 250 4.29 1,288 16,808 73 16,735 466.02 16,735 0.38
51 255 4.65 1,394 18,130 73 18,057 466.09 18,057 0.41
52 260 5.00 1,500 19,557 73 19,484 466.17 19,484 0.45
53 265 5.35 1,606 21,090 73 21,018 466.26 21,018 0.48
54 270 5.35 1,606 22,623 73 22,551 466.35 22,551 0.52
55 275 5.71 1,712 24,262 73 24,190 466.44 24,190 0.56

TIME BALANCE IN
BASIN
Basin Depth Analysis

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Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 6.06 1,817 26,007 73 25,934 466.53 25,934 0.60
57 285 6.41 1,923 27,858 73 27,785 466.64 27,785 0.64
58 290 6.41 1,923 29,708 73 29,635 466.74 29,635 0.68
59 295 6.76 2,029 31,664 73 31,592 466.85 31,592 0.73
60 300 7.12 2,135 33,726 73 33,654 466.97 33,654 0.77
61 305 8.88 2,664 36,317 73 36,245 467.10 36,245 0.83
62 310 10.64 3,193 39,437 73 39,365 467.26 39,365 0.90
63 315 11.70 3,510 42,875 73 42,802 467.44 42,802 0.98
64 320 12.76 3,827 46,629 73 46,557 467.63 46,557 1.07
65 325 14.52 4,356 50,913 73 50,840 467.85 50,840 1.17
66 330 17.69 5,308 56,149 73 56,076 468.11 56,076 1.29
67 335 4.65 1,394 57,470 73 57,398 468.17 57,398 1.32
68 340 1.12 336 57,734 73 57,661 468.19 57,661 1.32
69 345 0.06 19 57,680 73 57,608 468.18 57,608 1.32
70 350 0.18 53 57,661 73 57,588 468.18 57,588 1.32
71 355 0.11 32 57,620 73 57,547 468.18 57,547 1.32
72 360 0.07 21 57,568 73 57,496 468.18 57,496 1.32
Basin Depth Analysis

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Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.04 34 34 218 - 465.00 - 0.00
2 30 0.06 51 51 218 - 465.00 - 0.00
3 45 0.06 51 51 218 - 465.00 - 0.00
4 60 0.08 68 68 218 - 465.00 - 0.00
5 75 0.06 51 51 218 - 465.00 - 0.00
6 90 0.06 51 51 218 - 465.00 - 0.00
7 105 0.06 51 51 218 - 465.00 - 0.00
8 120 0.08 68 68 218 - 465.00 - 0.00
9 135 0.08 68 68 218 - 465.00 - 0.00
10 150 0.08 68 68 218 - 465.00 - 0.00
11 165 0.09 85 85 218 - 465.00 - 0.00
12 180 0.09 85 85 218 - 465.00 - 0.00
13 195 0.09 85 85 218 - 465.00 - 0.00
14 210 0.09 85 85 218 - 465.00 - 0.00
15 225 0.09 85 85 218 - 465.00 - 0.00
16 240 0.11 102 102 218 - 465.00 - 0.00
17 255 0.11 102 102 218 - 465.00 - 0.00
18 270 0.13 119 119 218 - 465.00 - 0.00
19 285 0.13 119 119 218 - 465.00 - 0.00
20 300 0.15 136 136 218 - 465.00 - 0.00
21 315 0.11 102 102 218 - 465.00 - 0.00
22 330 0.13 119 119 218 - 465.00 - 0.00
23 345 0.15 136 136 218 - 465.00 - 0.00
24 360 0.15 136 136 218 - 465.00 - 0.00
25 375 0.17 153 153 218 - 465.00 - 0.00
26 390 0.17 153 153 218 - 465.00 - 0.00
27 405 0.19 170 170 218 - 465.00 - 0.00
28 420 0.19 170 170 218 - 465.00 - 0.00
29 435 0.19 170 170 218 - 465.00 - 0.00
30 450 0.21 187 187 218 - 465.00 - 0.00
31 465 0.23 204 204 218 - 465.00 - 0.00
32 480 0.02 15 15 218 - 465.00 - 0.00
33 495 0.43 386 386 218 168 465.01 168 0.00
34 510 0.46 416 584 218 366 465.02 366 0.01
35 525 0.68 616 982 218 764 465.05 764 0.02
36 540 0.91 816 1,580 218 1,362 465.08 1,362 0.03
37 555 1.32 1,185 2,547 218 2,329 465.14 2,329 0.05
38 570 1.54 1,384 3,714 218 3,496 465.21 3,496 0.08
39 585 1.76 1,583 5,079 218 4,861 465.30 4,861 0.11
40 600 1.98 1,782 6,643 218 6,426 465.39 6,426 0.15
41 615 0.69 620 7,045 218 6,828 465.42 6,828 0.16
42 630 0.72 648 7,475 218 7,257 465.44 7,257 0.17
43 645 1.70 1,526 8,783 218 8,566 465.52 8,566 0.20
44 660 1.73 1,553 10,119 218 9,901 465.61 9,901 0.23
45 675 1.57 1,410 11,311 218 11,094 465.68 11,094 0.25
46 690 1.60 1,437 12,531 218 12,313 465.75 12,313 0.28
47 705 1.25 1,124 13,437 218 13,219 465.81 13,219 0.30
48 720 1.47 1,320 14,539 218 14,321 465.88 14,321 0.33
49 735 2.82 2,537 16,858 218 16,640 466.02 16,640 0.38
50 750 3.04 2,732 19,373 218 19,155 466.16 19,155 0.44
51 765 3.44 3,098 22,253 218 22,035 466.32 22,035 0.51
52 780 3.66 3,293 25,329 218 25,111 466.49 25,111 0.58
53 795 4.63 4,168 29,279 218 29,062 466.71 29,062 0.67
54 810 4.66 4,193 33,254 218 33,037 466.93 33,037 0.76
55 825 2.61 2,346 35,383 218 35,165 467.05 35,165 0.81
56 840 2.63 2,370 37,535 218 37,317 467.16 37,317 0.86
57 855 3.42 3,074 40,391 218 40,173 467.30 40,173 0.92
58 870 3.25 2,927 43,100 218 42,882 467.44 42,882 0.98

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 3.28 2,950 45,832 218 45,614 467.58 45,614 1.05
60 900 3.11 2,802 48,417 218 48,199 467.71 48,199 1.11
61 915 2.95 2,654 50,853 218 50,635 467.84 50,635 1.16
62 930 2.78 2,506 53,141 218 52,924 467.95 52,924 1.21
63 945 2.05 1,847 54,771 218 54,553 468.04 54,553 1.25
64 960 2.08 1,868 56,421 218 56,204 468.12 56,204 1.29
65 975 0.08 68 56,272 218 56,054 468.11 56,054 1.29
66 990 0.08 68 56,122 218 55,904 468.10 55,904 1.28
67 1005 0.06 51 55,955 218 55,738 468.09 55,738 1.28
68 1020 0.06 51 55,789 218 55,571 468.08 55,571 1.28
69 1035 0.09 85 55,656 218 55,438 468.08 55,438 1.27
70 1050 0.09 85 55,523 218 55,305 468.07 55,305 1.27
71 1065 0.09 85 55,390 218 55,173 468.07 55,173 1.27
72 1080 0.08 68 55,241 218 55,023 468.06 55,023 1.26
73 1095 0.08 68 55,091 218 54,873 468.05 54,873 1.26
74 1110 0.08 68 54,941 218 54,724 468.04 54,724 1.26
75 1125 0.06 51 54,775 218 54,557 468.04 54,557 1.25
76 1140 0.04 54,591 34 218 54,373 468.03 54,373 1.25
77 1155 0.06 51 54,424 218 54,206 468.02 54,206 1.24
78 1170 0.08 68 54,274 218 54,057 468.01 54,057 1.24
79 1185 0.06 51 54,108 218 53,890 468.00 53,890 1.24
80 1200 0.04 34 53,924 218 53,706 467.99 53,706 1.23
81 1215 0.06 51 53,757 218 53,539 467.99 53,539 1.23
82 1230 0.06 51 53,590 218 53,373 467.98 53,373 1.23
83 1245 0.06 51 53,424 218 53,206 467.97 53,206 1.22
84 1260 0.04 34 53,240 218 53,022 467.96 53,022 1.22
85 1275 0.06 51 53,073 218 52,856 467.95 52,856 1.21
86 1290 0.04 34 52,890 218 52,672 467.94 52,672 1.21
87 1305 0.06 51 52,723 218 52,505 467.93 52,505 1.21
88 1320 0.04 34 52,539 218 52,321 467.92 52,321 1.20
89 1335 0.06 51 52,372 218 52,155 467.92 52,155 1.20
90 1350 0.04 34 52,189 218 51,971 467.91 51,971 1.19
91 1365 0.04 34 52,005 218 51,787 467.90 51,787 1.19
92 1380 0.04 34 51,821 218 51,603 467.89 51,603 1.18
93 1395 0.04 34 51,637 218 51,420 467.88 51,420 1.18
94 1410 0.04 34 51,454 218 51,236 467.87 51,236 1.18
95 1425 0.04 34 51,270 218 51,052 467.86 51,052 1.17
96 1440 0.04 34 51,086 218 50,869 467.85 50,869 1.17
Basin Depth Analysis

Page 14 of 14 ends

Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 100 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 3

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 2.56
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE
MF - CONDOMINIUMS 6.65

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 1.04

RETENTION BASIN

GOLF COURSE

MOUNTAINOUS
LOW LOSS RATE (PERCENT) 90%
LENGTH OF WATERCOURSE (L) 750
LENGTH TO POINT OPPOSITE CENTROID (Lca) 170
ELEVATION OF HEADWATER 471.8
ELEVATION OF CONCENTRATION POINT 468.5
AVERAGE MANNINGS 'N' VALUE 0.02
STORM FREQUENCY (YEAR) 100

POINT RAIN
3-HOUR 2.12
6-HOUR 2.78
24-HOUR 4.47
BASIN CHARACTERISTICS: ELEVATION AREA
465 15000
466 16600
467 18250
468 19960
468.5 20831
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
680
Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT BASIC DATA CALCULATION FORM JOB # 0
SHORTCUT METHOD BY ES R. BAZUA, P.E. DATE 1/17/2025
[1] SOURCE
[2] FREQUENCY-YEARS 100
[3] DURATION:
[4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

2.12 10.250 1.00 2.12 2.78 10.250 1.00 2.78 4.47 10.250 1.00 4.47

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 10.25 SUM [7] 2.12 SUM [9] 10.25 SUM [11] 2.78 SUM [13] 10.25 SUM [15] 4.47 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 2.12 2.78 4.47
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 1.51 1.59 1.71
FLOOD VOLUME (cu-ft) 56,125 59,056 63,525
(acre-ft) 1.29 1.36 1.46
REQUIRED STORAGE (cu-ft) 53,172 53,709 51,340
(acre-ft) 1.22 1.23 1.18
PEAK FLOW (cfs) 19.27 17.04 4.42
MAXIMUM WSEL (ft) 468.04 468.07 467.95

0.142
170.00

0.001
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 3.3
[11] S-FEET/MILE

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 3

10.250
750

0.032
471.8
468.5

0.03 2.0

2.0 4.1

23.2 4.82

0.02 6-HOURS
[6] La-FEET
[7] La-MILES
[8] ELEVATION OF HEADWATER
[9] ELEVATION OF CONCENTRATION POINT
[2] AREA DESIGNATION
[3] AREA - ACRES
[4] L-FEET
[5] L-MILES
5 24-HOURS
[15] LAG TIME-HOURS
[16] LAG TIME-MINUTES

0.23 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 100 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

RATE IMPERVIOUS RATE
(in/hr) (in/hr) (in/hr)
[Plate C-1] [Plate E-6.1] [Plate E-6.2] [Plate E-6.3]
B 56 0.52 90% 0.10 0.00 0.000 0.0000
B 56 0.52 100% 0.05 2.56 0.250 0.0130
B 56 0.52 20% 0.43 0.00 0.000 0.0000B 56 0.52 40% 0.33 0.00 0.000 0.0000B 56 0.52 50% 0.29 0.00 0.000 0.0000B 56 0.52 65% 0.22 6.65 0.649 0.1400B 56 0.52 80% 0.15 0.00 0.000 0.0000B 56 0.52 75% 0.17 0.00 0.000 0.0000B 56 0.52 0% 0.52 1.04 0.101 0.0528B 56 0.52 0% 0.52 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.00 0.000 0.0000 D 93 0.95 90% 0.18 0.00 0.000 0.0000

0.00 0.000 0.0000

0.00 0.000 0.0000
SUM 10.25 SUM 0.2058
VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY)Fm= 0.102877561C= 0.00191Ft=C(24-(T/60))^1.55 = 0.00191 0.10 in/hr LOW LOSS RATE (80-90 PERCENT) = 90%Where:T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,T=1 1/2 unit time for the second period, etc. (24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 10.25
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 2.05
UNIT TIME-PERCENT OF LAG 244.5
TOTAL ADJUSTED STORM RAIN-INCHES 2.12
CONSTANT LOSS RATE-in/hr 0.21
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.23 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.331 0.21 0.30 0.12 1.28 314.48
2 10 0.17 1.3 0.331 0.21 0.30 0.12 1.28 314.48
3 15 0.25 1.1 0.280 0.21 0.25 0.07 0.76 158.02
4 20 0.33 1.5 0.382 0.21 0.34 0.18 1.80 470.93
5 25 0.42 1.5 0.382 0.21 0.34 0.18 1.80 470.93
6 30 0.50 1.8 0.458 0.21 0.41 0.25 2.58 705.62
7 35 0.58 1.5 0.382 0.21 0.34 0.18 1.80 470.93
8 40 0.67 1.8 0.458 0.21 0.41 0.25 2.58 705.62
9 45 0.75 1.8 0.458 0.21 0.41 0.25 2.58 705.62
10 50 0.83 1.5 0.382 0.21 0.34 0.18 1.80 470.93
11 55 0.92 1.6 0.407 0.21 0.37 0.20 2.06 549.16
12 60 1.00 1.8 0.458 0.21 0.41 0.25 2.58 705.62
13 65 1.08 2.2 0.560 0.21 0.50 0.35 3.63 1018.53
14 70 1.17 2.2 0.560 0.21 0.50 0.35 3.63 1018.53
15 75 1.25 2.2 0.560 0.21 0.50 0.35 3.63 1018.53
16 80 1.33 2.0 0.509 0.21 0.46 0.30 3.11 862.07
17 85 1.42 2.6 0.661 0.21 0.60 0.46 4.67 1331.44
18 90 1.50 2.7 0.687 0.21 0.62 0.48 4.93 1409.67
19 95 1.58 2.4 0.611 0.21 0.55 0.40 4.15 1174.98
20 100 1.67 2.7 0.687 0.21 0.62 0.48 4.93 1409.67
21 105 1.75 3.3 0.840 0.21 0.76 0.63 6.50 1879.04
22 110 1.83 3.1 0.789 0.21 0.71 0.58 5.97 1722.58
23 115 1.92 2.9 0.738 0.21 0.66 0.53 5.45 1566.12
24 120 2.00 3.0 0.763 0.21 0.69 0.56 5.71 1644.35
25 125 2.08 3.1 0.789 0.21 0.71 0.58 5.97 1722.58
26 130 2.17 4.2 1.068 0.21 0.96 0.86 8.84 2583.09
27 135 2.25 5.0 1.272 0.21 1.14 1.07 10.93 3208.91
28 140 2.33 3.5 0.890 0.21 0.80 0.68 7.02 2035.49
29 145 2.42 6.8 1.730 0.21 1.56 1.52 15.62 4617.02
30 150 2.50 7.3 1.857 0.21 1.67 1.65 16.93 5008.16
31 155 2.58 8.2 2.086 0.21 1.88 1.88 19.27 5712.21
32 160 2.67 5.9 1.501 0.21 1.35 1.30 13.28 3912.96
33 165 2.75 2.0 0.509 0.21 0.46 0.30 3.11 862.07
34 170 2.83 1.8 0.458 0.21 0.41 0.25 2.58 705.62
35 175 2.92 1.8 0.458 0.21 0.41 0.25 2.58 705.62
36 180 3.00 0.6 0.153 0.21 0.14 0.02 0.16 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.51
FLOOD VOLUME (acft) 1.29
FLOOD VOLUME (cuft) 56125.24
REQUIRED STORAGE (acft) 1.22
REQUIRED STORAGE (cuft) 53171.53
PEAK FLOW RATE (cfs) 19.27
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 10.25
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 2.05
UNIT TIME-PERCENT OF LAG 244.5
TOTAL ADJUSTED STORM RAIN-INCHES 2.78
CONSTANT LOSS RATE-in/hr 0.206
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.23 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.167 0.21 0.15 0.02 0.17 0.00
2 10 0.17 0.6 0.200 0.21 0.18 0.02 0.21 0.00
3 15 0.25 0.6 0.200 0.21 0.18 0.02 0.21 0.00
4 20 0.33 0.6 0.200 0.21 0.18 0.02 0.21 0.00
5 25 0.42 0.6 0.200 0.21 0.18 0.02 0.21 0.00
6 30 0.50 0.7 0.234 0.21 0.21 0.03 0.28 15.59
7 35 0.58 0.7 0.234 0.21 0.21 0.03 0.28 15.59
8 40 0.67 0.7 0.234 0.21 0.21 0.03 0.28 15.59
9 45 0.75 0.7 0.234 0.21 0.21 0.03 0.28 15.59
10 50 0.83 0.7 0.234 0.21 0.21 0.03 0.28 15.59
11 55 0.92 0.7 0.234 0.21 0.21 0.03 0.28 15.59
12 60 1.00 0.8 0.267 0.21 0.24 0.06 0.63 118.17
13 65 1.08 0.8 0.267 0.21 0.24 0.06 0.63 118.17
14 70 1.17 0.8 0.267 0.21 0.24 0.06 0.63 118.17
15 75 1.25 0.8 0.267 0.21 0.24 0.06 0.63 118.17
16 80 1.33 0.8 0.267 0.21 0.24 0.06 0.63 118.17
17 85 1.42 0.8 0.267 0.21 0.24 0.06 0.63 118.17
18 90 1.50 0.8 0.267 0.21 0.24 0.06 0.63 118.17
19 95 1.58 0.8 0.267 0.21 0.24 0.06 0.63 118.17
20 100 1.67 0.8 0.267 0.21 0.24 0.06 0.63 118.17
21 105 1.75 0.8 0.267 0.21 0.24 0.06 0.63 118.17
22 110 1.83 0.8 0.267 0.21 0.24 0.06 0.63 118.17
23 115 1.92 0.8 0.267 0.21 0.24 0.06 0.63 118.17
24 120 2.00 0.9 0.300 0.21 0.27 0.09 0.97 220.75
25 125 2.08 0.8 0.267 0.21 0.24 0.06 0.63 118.17
26 130 2.17 0.9 0.300 0.21 0.27 0.09 0.97 220.75
27 135 2.25 0.9 0.300 0.21 0.27 0.09 0.97 220.75
28 140 2.33 0.9 0.300 0.21 0.27 0.09 0.97 220.75
29 145 2.42 0.9 0.300 0.21 0.27 0.09 0.97 220.75
30 150 2.50 0.9 0.300 0.21 0.27 0.09 0.97 220.75
31 155 2.58 0.9 0.300 0.21 0.27 0.09 0.97 220.75
32 160 2.67 0.9 0.300 0.21 0.27 0.09 0.97 220.75
33 165 2.75 1.0 0.334 0.21 0.30 0.13 1.31 323.33
34 170 2.83 1.0 0.334 0.21 0.30 0.13 1.31 323.33
35 175 2.92 1.0 0.334 0.21 0.30 0.13 1.31 323.33
36 180 3.00 1.0 0.334 0.21 0.30 0.13 1.31 323.33
37 185 3.08 1.0 0.334 0.21 0.30 0.13 1.31 323.33
38 190 3.17 1.1 0.367 0.21 0.33 0.16 1.65 425.91
39 195 3.25 1.1 0.367 0.21 0.33 0.16 1.65 425.91
40 200 3.33 1.1 0.367 0.21 0.33 0.16 1.65 425.91
41 205 3.42 1.2 0.400 0.21 0.36 0.19 1.99 528.50
42 210 3.50 1.3 0.434 0.21 0.39 0.23 2.34 631.08
43 215 3.58 1.4 0.467 0.21 0.42 0.26 2.68 733.66
44 220 3.67 1.4 0.467 0.21 0.42 0.26 2.68 733.66
45 225 3.75 1.5 0.500 0.21 0.45 0.29 3.02 836.24
46 230 3.83 1.5 0.500 0.21 0.45 0.29 3.02 836.24
47 235 3.92 1.6 0.534 0.21 0.48 0.33 3.36 938.82
48 240 4.00 1.6 0.534 0.21 0.48 0.33 3.36 938.82
49 245 4.08 1.7 0.567 0.21 0.51 0.36 3.70 1041.41
50 250 4.17 1.8 0.600 0.21 0.54 0.39 4.05 1143.99
51 255 4.25 1.9 0.634 0.21 0.57 0.43 4.39 1246.57
52 260 4.33 2.0 0.667 0.21 0.60 0.46 4.73 1349.15
53 265 4.42 2.1 0.701 0.21 0.63 0.49 5.07 1451.73
54 270 4.50 2.1 0.701 0.21 0.63 0.49 5.07 1451.73
55 275 4.58 2.2 0.734 0.21 0.66 0.53 5.41 1554.32
56 280 4.67 2.3 0.767 0.21 0.69 0.56 5.76 1656.90

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.801 0.21 0.72 0.59 6.10 1759.48
58 290 4.83 2.4 0.801 0.21 0.72 0.59 6.10 1759.48
59 295 4.92 2.5 0.834 0.21 0.75 0.63 6.44 1862.06
60 300 5.00 2.6 0.867 0.21 0.78 0.66 6.78 1964.64
61 305 5.08 3.1 1.034 0.21 0.93 0.83 8.49 2477.55
62 310 5.17 3.6 1.201 0.21 1.08 1.00 10.20 2990.46
63 315 5.25 3.9 1.301 0.21 1.17 1.10 11.23 3298.21
64 320 5.33 4.2 1.401 0.21 1.26 1.20 12.25 3605.96
65 325 5.42 4.7 1.568 0.21 1.41 1.36 13.96 4118.87
66 330 5.50 5.6 1.868 0.21 1.68 1.66 17.04 5042.10
67 335 5.58 1.9 0.634 0.21 0.57 0.43 4.39 1246.57
68 340 5.67 0.9 0.300 0.21 0.27 0.09 0.97 220.75
69 345 5.75 0.6 0.200 0.21 0.18 0.02 0.21 0.00
70 350 5.83 0.5 0.167 0.21 0.15 0.02 0.17 0.00
71 355 5.92 0.3 0.100 0.21 0.09 0.01 0.10 0.00
72 360 6.00 0.2 0.067 0.21 0.06 0.01 0.07 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.59
FLOOD VOLUME (acft) 1.36
FLOOD VOLUME (cuft) 59055.81
REQUIRED STORAGE (acft) 1.23
REQUIRED STORAGE (cuft) 53709.02
PEAK FLOW RATE (cfs) 17.04
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 10.250 CONSTANT LOSS RATE-in/hr n/a UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.2058 LAG TIME - MINUTES 2.05 MINIMUM LOSS RATE (for var. loss) - in/hr 0.103 UNIT TIME-PERCENT OF LAG 733.4 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 4.47 C 0.00191
PERCOLATION RATE (cfs) 0.23
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.036 0.363 0.032 0.004 0.04 0.00
2 30 0.50 0.3 0.054 0.359 0.048 0.005 0.05 0.00
3 45 0.75 0.3 0.054 0.355 0.048 0.005 0.05 0.00
4 60 1.00 0.4 0.072 0.351 0.064 0.007 0.07 0.00
5 75 1.25 0.3 0.054 0.347 0.048 0.005 0.05 0.00
6 90 1.50 0.3 0.054 0.343 0.048 0.005 0.05 0.00
7 105 1.75 0.3 0.054 0.338 0.048 0.005 0.05 0.00
8 120 2.00 0.4 0.072 0.334 0.064 0.007 0.07 0.00
9 135 2.25 0.4 0.072 0.330 0.064 0.007 0.07 0.00
10 150 2.50 0.4 0.072 0.326 0.064 0.007 0.07 0.00
11 165 2.75 0.5 0.089 0.322 0.080 0.009 0.09 0.00
12 180 3.00 0.5 0.089 0.318 0.080 0.009 0.09 0.00
13 195 3.25 0.5 0.089 0.314 0.080 0.009 0.09 0.00
14 210 3.50 0.5 0.089 0.310 0.080 0.009 0.09 0.00
15 225 3.75 0.5 0.089 0.307 0.080 0.009 0.09 0.00
16 240 4.00 0.6 0.107 0.303 0.097 0.011 0.11 0.00
17 255 4.25 0.6 0.107 0.299 0.097 0.011 0.11 0.00
18 270 4.50 0.7 0.125 0.295 0.113 0.013 0.13 0.00
19 285 4.75 0.7 0.125 0.291 0.113 0.013 0.13 0.00
20 300 5.00 0.8 0.143 0.288 0.129 0.014 0.15 0.00
21 315 5.25 0.6 0.107 0.284 0.097 0.011 0.11 0.00
22 330 5.50 0.7 0.125 0.280 0.113 0.013 0.13 0.00
23 345 5.75 0.8 0.143 0.276 0.129 0.014 0.15 0.00
24 360 6.00 0.8 0.143 0.273 0.129 0.014 0.15 0.00
25 375 6.25 0.9 0.161 0.269 0.145 0.016 0.16 0.00
26 390 6.50 0.9 0.161 0.266 0.145 0.016 0.16 0.00
27 405 6.75 1.0 0.179 0.262 0.161 0.018 0.18 0.00
28 420 7.00 1.0 0.179 0.258 0.161 0.018 0.18 0.00
29 435 7.25 1.0 0.179 0.255 0.161 0.018 0.18 0.00
30 450 7.50 1.1 0.197 0.252 0.177 0.020 0.20 0.00
31 465 7.75 1.2 0.215 0.248 0.193 0.021 0.22 0.00
32 480 8.00 1.3 0.232 0.245 0.209 0.023 0.24 5.05
33 495 8.25 1.5 0.268 0.241 0.241 0.027 0.28 39.29
34 510 8.50 1.5 0.268 0.238 0.241 0.030 0.31 70.31
35 525 8.75 1.6 0.286 0.235 0.257 0.052 0.53 266.00
36 540 9.00 1.7 0.304 0.231 0.274 0.073 0.75 461.42
37 555 9.25 1.9 0.340 0.228 0.306 0.112 1.15 821.51
38 570 9.50 2.0 0.358 0.225 0.322 0.133 1.36 1016.37
39 585 9.75 2.1 0.375 0.222 0.338 0.154 1.58 1210.96
40 600 10.00 2.2 0.393 0.218 0.354 0.175 1.79 1405.26
41 615 10.25 1.5 0.268 0.215 0.241 0.053 0.54 279.74
42 630 10.50 1.5 0.268 0.212 0.241 0.056 0.58 308.53
43 645 10.75 2.0 0.358 0.209 0.322 0.149 1.52 1161.74
44 660 11.00 2.0 0.358 0.206 0.322 0.152 1.55 1189.95
45 675 11.25 1.9 0.340 0.203 0.306 0.137 1.40 1052.92
46 690 11.50 1.9 0.340 0.200 0.306 0.140 1.43 1080.54
47 705 11.75 1.7 0.304 0.197 0.274 0.107 1.10 777.97
48 720 12.00 1.8 0.322 0.194 0.290 0.128 1.31 969.93
49 735 12.25 2.5 0.447 0.191 0.402 0.256 2.62 2151.25
50 750 12.50 2.6 0.465 0.188 0.418 0.277 2.84 2342.59
51 765 12.75 2.8 0.501 0.185 0.451 0.315 3.23 2698.57
52 780 13.00 2.9 0.519 0.183 0.467 0.336 3.44 2889.30
53 795 13.25 3.4 0.608 0.180 0.547 0.428 4.39 3739.48
54 810 13.50 3.4 0.608 0.177 0.547 0.431 4.42 3764.62
55 825 13.75 2.3 0.411 0.174 0.370 0.237 2.43 1975.07
56 840 14.00 2.3 0.411 0.172 0.370 0.239 2.45 1999.56
57 855 14.25 2.7 0.483 0.169 0.434 0.314 3.21 2683.50
58 870 14.50 2.6 0.465 0.167 0.418 0.298 3.06 2542.39
59 885 14.75 2.6 0.465 0.164 0.418 0.301 3.08 2565.88
60 900 15.00 2.5 0.447 0.162 0.402 0.285 2.93 2424.08
61 915 15.25 2.4 0.429 0.159 0.386 0.270 2.77 2281.94
62 930 15.50 2.3 0.411 0.157 0.370 0.255 2.61 2139.45
63 945 15.75 1.9 0.340 0.154 0.306 0.185 1.90 1501.78
64 960 16.00 1.9 0.340 0.152 0.306 0.188 1.93 1523.52
65 975 16.25 0.4 0.072 0.150 0.064 0.007 0.07 0.00
66 990 16.50 0.4 0.072 0.147 0.064 0.007 0.07 0.00
67 1005 16.75 0.3 0.054 0.145 0.048 0.005 0.05 0.00
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 7 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
68 1020 17.00 0.3 0.054 0.143 0.048 0.005 0.05 0.00
69 1035 17.25 0.5 0.089 0.141 0.080 0.009 0.09 0.00
70 1050 17.50 0.5 0.089 0.139 0.080 0.009 0.09 0.00
71 1065 17.75 0.5 0.089 0.137 0.080 0.009 0.09 0.00
72 1080 18.00 0.4 0.072 0.134 0.064 0.007 0.07 0.00
73 1095 18.25 0.4 0.072 0.133 0.064 0.007 0.07 0.00
74 1110 18.50 0.4 0.072 0.131 0.064 0.007 0.07 0.00
75 1125 18.75 0.3 0.054 0.129 0.048 0.005 0.05 0.00
76 1140 19.00 0.2 0.036 0.127 0.032 0.004 0.04 0.00
77 1155 19.25 0.3 0.054 0.125 0.048 0.005 0.05 0.00
78 1170 19.50 0.4 0.072 0.123 0.064 0.007 0.07 0.00
79 1185 19.75 0.3 0.054 0.122 0.048 0.005 0.05 0.00
80 1200 20.00 0.2 0.036 0.120 0.032 0.004 0.04 0.00
81 1215 20.25 0.3 0.054 0.118 0.048 0.005 0.05 0.00
82 1230 20.50 0.3 0.054 0.117 0.048 0.005 0.05 0.00
83 1245 20.75 0.3 0.054 0.115 0.048 0.005 0.05 0.00
84 1260 21.00 0.2 0.036 0.114 0.032 0.004 0.04 0.00
85 1275 21.25 0.3 0.054 0.113 0.048 0.005 0.05 0.00
86 1290 21.50 0.2 0.036 0.111 0.032 0.004 0.04 0.00
87 1305 21.75 0.3 0.054 0.110 0.048 0.005 0.05 0.00
88 1320 22.00 0.2 0.036 0.109 0.032 0.004 0.04 0.00
89 1335 22.25 0.3 0.054 0.108 0.048 0.005 0.05 0.00
90 1350 22.50 0.2 0.036 0.107 0.032 0.004 0.04 0.00
91 1365 22.75 0.2 0.036 0.106 0.032 0.004 0.04 0.00
92 1380 23.00 0.2 0.036 0.105 0.032 0.004 0.04 0.00
93 1395 23.25 0.2 0.036 0.104 0.032 0.004 0.04 0.00
94 1410 23.50 0.2 0.036 0.104 0.032 0.004 0.04 0.00
95 1425 23.75 0.2 0.036 0.103 0.032 0.004 0.04 0.00
96 1440 24.00 0.2 0.036 0.103 0.032 0.004 0.04 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.71
FLOOD VOLUME (acft) 1.46
FLOOD VOLUME (cuft) 63525.46
REQUIRED STORAGE (acft) 1.18
REQUIRED STORAGE (cuft) 51340.48
PEAK FLOW (cfs) 4.42
Plate E-2.2

Page 8 of 14 ends

Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

INCR TOTAL INCR TOTAL INCR TOTAL
(ft) (ft) (sf) (sf) (cuft) (cuft) (acre-ft)
465 0 0 15000 0 0 0.00
466 1 1 1600 16600 15800 15800 0.36
467 1 2 1650 18250 17425 33225 0.76
468 1 3 1710 19960 19105 52330 1.20
468.5 0.5 3.5 871 20831 10198 62528 1.44

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.23 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.23 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 1.28 384 384 70 314 465.02 314 0.01
2 10 1.28 384 699 70 629 465.04 629 0.01
3 15 0.76 228 857 70 787 465.05 787 0.02
4 20 1.80 541 1,328 70 1,258 465.08 1,258 0.03
5 25 1.80 541 1,799 70 1,729 465.11 1,729 0.04
6 30 2.58 775 2,504 70 2,434 465.15 2,434 0.06
7 35 1.80 541 2,975 70 2,905 465.18 2,905 0.07
8 40 2.58 775 3,681 70 3,611 465.23 3,611 0.08
9 45 2.58 775 4,386 70 4,317 465.27 4,317 0.10
10 50 1.80 541 4,857 70 4,788 465.30 4,788 0.11
11 55 2.06 619 5,406 70 5,337 465.34 5,337 0.12
12 60 2.58 775 6,112 70 6,042 465.38 6,042 0.14
13 65 3.63 1,088 7,131 70 7,061 465.45 7,061 0.16
14 70 3.63 1,088 8,149 70 8,079 465.51 8,079 0.19
15 75 3.63 1,088 9,168 70 9,098 465.58 9,098 0.21
16 80 3.11 932 10,030 70 9,960 465.63 9,960 0.23
17 85 4.67 1,401 11,361 70 11,291 465.71 11,291 0.26
18 90 4.93 1,479 12,771 70 12,701 465.80 12,701 0.29
19 95 4.15 1,245 13,946 70 13,876 465.88 13,876 0.32
20 100 4.93 1,479 15,356 70 15,286 465.97 15,286 0.35
21 105 6.50 1,949 17,235 70 17,165 466.08 17,165 0.39
22 110 5.97 1,792 18,957 70 18,887 466.18 18,887 0.43
23 115 5.45 1,636 20,523 70 20,453 466.27 20,453 0.47
24 120 5.71 1,714 22,168 70 22,098 466.36 22,098 0.51
25 125 5.97 1,792 23,890 70 23,820 466.46 23,820 0.55
26 130 8.84 2,653 26,473 70 26,403 466.61 26,403 0.61
27 135 10.93 3,279 29,682 70 29,612 466.79 29,612 0.68
28 140 7.02 2,105 31,718 70 31,648 466.91 31,648 0.73
29 145 15.62 4,687 36,335 70 36,265 467.16 36,265 0.83
30 150 16.93 5,078 41,343 70 41,273 467.42 41,273 0.95
31 155 19.27 5,782 47,055 70 46,985 467.72 46,985 1.08
32 160 13.28 3,983 50,968 70 50,898 467.93 50,898 1.17
33 165 3.11 932 51,830 70 51,760 467.97 51,760 1.19
34 170 2.58 775 52,536 70 52,466 468.01 52,466 1.20
35 175 2.58 775 53,241 70 53,172 468.04 53,172 1.22
36 180 0.16 47 53,218 70 53,149 468.04 53,149 1.22

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.17 51 51 70 - 465.00 - 0.00
2 10 0.21 62 62 70 - 465.00 - 0.00
3 15 0.21 62 62 70 - 465.00 - 0.00
4 20 0.21 62 62 70 - 465.00 - 0.00
5 25 0.21 62 62 70 - 465.00 - 0.00
6 30 0.28 85 85 70 16 465.00 16 0.00
7 35 0.28 85 101 70 31 465.00 31 0.00
8 40 0.28 85 117 70 47 465.00 47 0.00
9 45 0.28 85 132 70 62 465.00 62 0.00
10 50 0.28 85 148 70 78 465.00 78 0.00
11 55 0.28 85 163 70 94 465.01 94 0.00
12 60 0.63 188 281 70 212 465.01 212 0.00
13 65 0.63 188 400 70 330 465.02 330 0.01
14 70 0.63 188 518 70 448 465.03 448 0.01
15 75 0.63 188 636 70 566 465.04 566 0.01
16 80 0.63 188 754 70 684 465.04 684 0.02
17 85 0.63 188 872 70 803 465.05 803 0.02
18 90 0.63 188 990 70 921 465.06 921 0.02
19 95 0.63 188 1,109 70 1,039 465.07 1,039 0.02
20 100 0.63 188 1,227 70 1,157 465.07 1,157 0.03
21 105 0.63 188 1,345 70 1,275 465.08 1,275 0.03
22 110 0.63 188 1,463 70 1,393 465.09 1,393 0.03
23 115 0.63 188 1,581 70 1,512 465.10 1,512 0.03
24 120 0.97 291 1,802 70 1,732 465.11 1,732 0.04
25 125 0.63 188 1,920 70 1,850 465.12 1,850 0.04
26 130 0.97 291 2,141 70 2,071 465.13 2,071 0.05
27 135 0.97 291 2,362 70 2,292 465.15 2,292 0.05
28 140 0.97 291 2,582 70 2,513 465.16 2,513 0.06
29 145 0.97 291 2,803 70 2,733 465.17 2,733 0.06
30 150 0.97 291 3,024 70 2,954 465.19 2,954 0.07
31 155 0.97 291 3,245 70 3,175 465.20 3,175 0.07
32 160 0.97 291 3,465 70 3,396 465.21 3,396 0.08
33 165 1.31 393 3,789 70 3,719 465.24 3,719 0.09
34 170 1.31 393 4,112 70 4,042 465.26 4,042 0.09
35 175 1.31 393 4,435 70 4,366 465.28 4,366 0.10
36 180 1.31 393 4,759 70 4,689 465.30 4,689 0.11
37 185 1.31 393 5,082 70 5,012 465.32 5,012 0.12
38 190 1.65 496 5,508 70 5,438 465.34 5,438 0.12
39 195 1.65 496 5,934 70 5,864 465.37 5,864 0.13
40 200 1.65 496 6,360 70 6,290 465.40 6,290 0.14
41 205 1.99 598 6,888 70 6,819 465.43 6,819 0.16
42 210 2.34 701 7,519 70 7,450 465.47 7,450 0.17
43 215 2.68 803 8,253 70 8,183 465.52 8,183 0.19
44 220 2.68 803 8,987 70 8,917 465.56 8,917 0.20
45 225 3.02 906 9,823 70 9,753 465.62 9,753 0.22
46 230 3.02 906 10,659 70 10,589 465.67 10,589 0.24
47 235 3.36 1,009 11,598 70 11,528 465.73 11,528 0.26
48 240 3.36 1,009 12,537 70 12,467 465.79 12,467 0.29
49 245 3.70 1,111 13,578 70 13,509 465.85 13,509 0.31
50 250 4.05 1,214 14,722 70 14,652 465.93 14,652 0.34
51 255 4.39 1,316 15,969 70 15,899 466.01 15,899 0.36
52 260 4.73 1,419 17,318 70 17,248 466.08 17,248 0.40
53 265 5.07 1,522 18,770 70 18,700 466.17 18,700 0.43
54 270 5.07 1,522 20,221 70 20,152 466.25 20,152 0.46
55 275 5.41 1,624 21,776 70 21,706 466.34 21,706 0.50

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 11 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 5.76 1,727 23,433 70 23,363 466.43 23,363 0.54
57 285 6.10 1,829 25,192 70 25,122 466.53 25,122 0.58
58 290 6.10 1,829 26,952 70 26,882 466.64 26,882 0.62
59 295 6.44 1,932 28,814 70 28,744 466.74 28,744 0.66
60 300 6.78 2,034 30,778 70 30,709 466.86 30,709 0.70
61 305 8.49 2,547 33,256 70 33,186 467.00 33,186 0.76
62 310 10.20 3,060 36,246 70 36,177 467.15 36,177 0.83
63 315 11.23 3,368 39,545 70 39,475 467.33 39,475 0.91
64 320 12.25 3,676 43,151 70 43,081 467.52 43,081 0.99
65 325 13.96 4,189 47,269 70 47,200 467.73 47,200 1.08
66 330 17.04 5,112 52,311 70 52,242 468.00 52,242 1.20
67 335 4.39 1,316 53,558 70 53,488 468.06 53,488 1.23
68 340 0.97 291 53,779 70 53,709 468.07 53,709 1.23
69 345 0.21 62 53,771 70 53,701 468.07 53,701 1.23
70 350 0.17 51 53,752 70 53,682 468.07 53,682 1.23
71 355 0.10 31 53,713 70 53,643 468.06 53,643 1.23
72 360 0.07 21 53,664 70 53,594 468.06 53,594 1.23
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.04 33 33 209 - 465.00 - 0.00
2 30 0.05 49 49 209 - 465.00 - 0.00
3 45 0.05 49 49 209 - 465.00 - 0.00
4 60 0.07 66 66 209 - 465.00 - 0.00
5 75 0.05 49 49 209 - 465.00 - 0.00
6 90 0.05 49 49 209 - 465.00 - 0.00
7 105 0.05 49 49 209 - 465.00 - 0.00
8 120 0.07 66 66 209 - 465.00 - 0.00
9 135 0.07 66 66 209 - 465.00 - 0.00
10 150 0.07 66 66 209 - 465.00 - 0.00
11 165 0.09 82 82 209 - 465.00 - 0.00
12 180 0.09 82 82 209 - 465.00 - 0.00
13 195 0.09 82 82 209 - 465.00 - 0.00
14 210 0.09 82 82 209 - 465.00 - 0.00
15 225 0.09 82 82 209 - 465.00 - 0.00
16 240 0.11 99 99 209 - 465.00 - 0.00
17 255 0.11 99 99 209 - 465.00 - 0.00
18 270 0.13 115 115 209 - 465.00 - 0.00
19 285 0.13 115 115 209 - 465.00 - 0.00
20 300 0.15 132 132 209 - 465.00 - 0.00
21 315 0.11 99 99 209 - 465.00 - 0.00
22 330 0.13 115 115 209 - 465.00 - 0.00
23 345 0.15 132 132 209 - 465.00 - 0.00
24 360 0.15 132 132 209 - 465.00 - 0.00
25 375 0.16 148 148 209 - 465.00 - 0.00
26 390 0.16 148 148 209 - 465.00 - 0.00
27 405 0.18 165 165 209 - 465.00 - 0.00
28 420 0.18 165 165 209 - 465.00 - 0.00
29 435 0.18 165 165 209 - 465.00 - 0.00
30 450 0.20 181 181 209 - 465.00 - 0.00
31 465 0.22 198 198 209 - 465.00 - 0.00
32 480 0.24 214 214 209 5 465.00 5 0.00
33 495 0.28 249 254 209 44 465.00 44 0.00
34 510 0.31 280 324 209 115 465.01 115 0.00
35 525 0.53 475 590 209 381 465.02 381 0.01
36 540 0.75 671 1,051 209 842 465.05 842 0.02
37 555 1.15 1,031 1,873 209 1,664 465.11 1,664 0.04
38 570 1.36 1,226 2,889 209 2,680 465.17 2,680 0.06
39 585 1.58 1,420 4,100 209 3,891 465.25 3,891 0.09
40 600 1.79 1,615 5,506 209 5,296 465.34 5,296 0.12
41 615 0.54 489 5,785 209 5,576 465.35 5,576 0.13
42 630 0.58 518 6,094 209 5,884 465.37 5,884 0.14
43 645 1.52 1,371 7,256 209 7,046 465.45 7,046 0.16
44 660 1.55 1,399 8,446 209 8,236 465.52 8,236 0.19
45 675 1.40 1,262 9,498 209 9,289 465.59 9,289 0.21
46 690 1.43 1,290 10,579 209 10,370 465.66 10,370 0.24
47 705 1.10 987 11,357 209 11,148 465.71 11,148 0.26
48 720 1.31 1,179 12,327 209 12,117 465.77 12,117 0.28
49 735 2.62 2,361 14,478 209 14,269 465.90 14,269 0.33
50 750 2.84 2,552 16,821 209 16,611 466.05 16,611 0.38
51 765 3.23 2,908 19,519 209 19,310 466.20 19,310 0.44
52 780 3.44 3,099 22,409 209 22,199 466.37 22,199 0.51
53 795 4.39 3,949 26,148 209 25,939 466.58 25,939 0.60
54 810 4.42 3,974 29,913 209 29,703 466.80 29,703 0.68
55 825 2.43 2,184 31,888 209 31,678 466.91 31,678 0.73
56 840 2.45 2,209 33,887 209 33,678 467.02 33,678 0.77
57 855 3.21 2,893 36,571 209 36,361 467.16 36,361 0.83
58 870 3.06 2,752 39,113 209 38,904 467.30 38,904 0.89

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 3.08 2,775 41,679 209 41,470 467.43 41,470 0.95
60 900 2.93 2,633 44,103 209 43,894 467.56 43,894 1.01
61 915 2.77 2,491 46,385 209 46,176 467.68 46,176 1.06
62 930 2.61 2,349 48,525 209 48,315 467.79 48,315 1.11
63 945 1.90 1,711 50,026 209 49,817 467.87 49,817 1.14
64 960 1.93 1,733 51,550 209 51,340 467.95 51,340 1.18
65 975 0.07 66 51,406 209 51,197 467.94 51,197 1.18
66 990 0.07 66 51,263 209 51,054 467.93 51,054 1.17
67 1005 0.05 49 51,103 209 50,894 467.92 50,894 1.17
68 1020 0.05 49 50,943 209 50,734 467.92 50,734 1.16
69 1035 0.09 82 50,816 209 50,607 467.91 50,607 1.16
70 1050 0.09 82 50,689 209 50,480 467.90 50,480 1.16
71 1065 0.09 82 50,563 209 50,353 467.90 50,353 1.16
72 1080 0.07 66 50,419 209 50,210 467.89 50,210 1.15
73 1095 0.07 66 50,276 209 50,066 467.88 50,066 1.15
74 1110 0.07 66 50,132 209 49,923 467.87 49,923 1.15
75 1125 0.05 49 49,972 209 49,763 467.87 49,763 1.14
76 1140 0.04 49,796 33 209 49,587 467.86 49,587 1.14
77 1155 0.05 49 49,636 209 49,427 467.85 49,427 1.13
78 1170 0.07 66 49,493 209 49,283 467.84 49,283 1.13
79 1185 0.05 49 49,333 209 49,124 467.83 49,124 1.13
80 1200 0.04 33 49,157 209 48,947 467.82 48,947 1.12
81 1215 0.05 49 48,997 209 48,787 467.81 48,787 1.12
82 1230 0.05 49 48,837 209 48,627 467.81 48,627 1.12
83 1245 0.05 49 48,677 209 48,467 467.80 48,467 1.11
84 1260 0.04 33 48,500 209 48,291 467.79 48,291 1.11
85 1275 0.05 49 48,341 209 48,131 467.78 48,131 1.10
86 1290 0.04 33 48,164 209 47,955 467.77 47,955 1.10
87 1305 0.05 49 48,004 209 47,795 467.76 47,795 1.10
88 1320 0.04 33 47,828 209 47,619 467.75 47,619 1.09
89 1335 0.05 49 47,668 209 47,459 467.75 47,459 1.09
90 1350 0.04 33 47,492 209 47,282 467.74 47,282 1.09
91 1365 0.04 33 47,315 209 47,106 467.73 47,106 1.08
92 1380 0.04 33 47,139 209 46,929 467.72 46,929 1.08
93 1395 0.04 33 46,962 209 46,753 467.71 46,753 1.07
94 1410 0.04 33 46,786 209 46,577 467.70 46,577 1.07
95 1425 0.04 33 46,610 209 46,400 467.69 46,400 1.07
96 1440 0.04 33 46,433 209 46,224 467.68 46,224 1.06
Basin Depth Analysis

Page 14 of 14 ends

Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 100 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 4

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 2.33
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE
MF - CONDOMINIUMS 6.56

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 0.9

RETENTION BASIN

GOLF COURSE

MOUNTAINOUS
LOW LOSS RATE (PERCENT) 90%
LENGTH OF WATERCOURSE (L) 620
LENGTH TO POINT OPPOSITE CENTROID (Lca) 70
ELEVATION OF HEADWATER 470.5
ELEVATION OF CONCENTRATION POINT 468
AVERAGE MANNINGS 'N' VALUE 0.02
STORM FREQUENCY (YEAR) 100

POINT RAIN
3-HOUR 2.12
6-HOUR 2.78
24-HOUR 4.47
BASIN CHARACTERISTICS: ELEVATION AREA
464.5 13730
465.5 15200
466.5 16700
467.5 18270
468 19075
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
694
Item 2.

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

2.12 9.790 1.00 2.12 2.78 9.790 1.00 2.78 4.47 9.790 1.00 4.47

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 9.79 SUM [7] 2.12 SUM [9] 9.79 SUM [11] 2.78 SUM [13] 9.79 SUM [15] 4.47 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 2.12 2.78 4.47
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 1.51 1.59 1.71
FLOOD VOLUME (cu-ft) 53,707 56,587 60,936
(acre-ft) 1.23 1.30 1.40
REQUIRED STORAGE (cu-ft) 50,983 51,654 49,570
(acre-ft) 1.17 1.19 1.14
PEAK FLOW (cfs) 18.42 16.28 4.23
MAXIMUM WSEL (ft) 467.67 467.70 467.59
24-HOURS
[15] LAG TIME-HOURS
[16] LAG TIME-MINUTES

0.21 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS 6-HOURS
[6] La-FEET
[7] La-MILES
[8] ELEVATION OF HEADWATER
[9] ELEVATION OF CONCENTRATION POINT
[2] AREA DESIGNATION
[3] AREA - ACRES
[4] L-FEET
[5] L-MILES
5 0.02

1.4 1.4

2.8 21.3

4.61 0.02

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 4

9.790
620

0.013
470.5
468

0.117

70.00 0.000
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 2.5
[11] S-FEET/MILE
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 100 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

RATE IMPERVIOUS RATE
(in/hr) (in/hr) (in/hr)
[Plate C-1] [Plate E-6.1] [Plate E-6.2] [Plate E-6.3]
B 56 0.52 90% 0.10 0.00 0.000 0.0000
B 56 0.52 100% 0.05 2.33 0.238 0.0124
B 56 0.52 20% 0.43 0.00 0.000 0.0000B 56 0.52 40% 0.33 0.00 0.000 0.0000B 56 0.52 50% 0.29 0.00 0.000 0.0000B 56 0.52 65% 0.22 6.56 0.670 0.1446B 56 0.52 80% 0.15 0.00 0.000 0.0000B 56 0.52 75% 0.17 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.90 0.092 0.0478B 56 0.52 0% 0.52 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.00 0.000 0.0000 D 93 0.95 90% 0.18 0.00 0.000 0.0000

0.00 0.000 0.0000

0.00 0.000 0.0000
SUM 9.79 SUM 0.2048
VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY)Fm= 0.102390603C= 0.00190Ft=C(24-(T/60))^1.55 = 0.00190 0.10 in/hr LOW LOSS RATE (80-90 PERCENT) = 90%Where:T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,T=1 1/2 unit time for the second period, etc.

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS
(24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 9.79
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.38
UNIT TIME-PERCENT OF LAG 362.1
TOTAL ADJUSTED STORM RAIN-INCHES 2.12
CONSTANT LOSS RATE-in/hr 0.20
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.21 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.331 0.20 0.30 0.13 1.23 306.00
2 10 0.17 1.3 0.331 0.20 0.30 0.13 1.23 306.00
3 15 0.25 1.1 0.280 0.20 0.25 0.08 0.73 156.57
4 20 0.33 1.5 0.382 0.20 0.34 0.18 1.73 455.43
5 25 0.42 1.5 0.382 0.20 0.34 0.18 1.73 455.43
6 30 0.50 1.8 0.458 0.20 0.41 0.25 2.48 679.59
7 35 0.58 1.5 0.382 0.20 0.34 0.18 1.73 455.43
8 40 0.67 1.8 0.458 0.20 0.41 0.25 2.48 679.59
9 45 0.75 1.8 0.458 0.20 0.41 0.25 2.48 679.59
10 50 0.83 1.5 0.382 0.20 0.34 0.18 1.73 455.43
11 55 0.92 1.6 0.407 0.20 0.37 0.20 1.98 530.15
12 60 1.00 1.8 0.458 0.20 0.41 0.25 2.48 679.59
13 65 1.08 2.2 0.560 0.20 0.50 0.35 3.47 978.46
14 70 1.17 2.2 0.560 0.20 0.50 0.35 3.47 978.46
15 75 1.25 2.2 0.560 0.20 0.50 0.35 3.47 978.46
16 80 1.33 2.0 0.509 0.20 0.46 0.30 2.98 829.02
17 85 1.42 2.6 0.661 0.20 0.60 0.46 4.47 1277.32
18 90 1.50 2.7 0.687 0.20 0.62 0.48 4.72 1352.04
19 95 1.58 2.4 0.611 0.20 0.55 0.41 3.97 1127.89
20 100 1.67 2.7 0.687 0.20 0.62 0.48 4.72 1352.04
21 105 1.75 3.3 0.840 0.20 0.76 0.63 6.21 1800.35
22 110 1.83 3.1 0.789 0.20 0.71 0.58 5.72 1650.91
23 115 1.92 2.9 0.738 0.20 0.66 0.53 5.22 1501.48
24 120 2.00 3.0 0.763 0.20 0.69 0.56 5.47 1576.19
25 125 2.08 3.1 0.789 0.20 0.71 0.58 5.72 1650.91
26 130 2.17 4.2 1.068 0.20 0.96 0.86 8.46 2472.80
27 135 2.25 5.0 1.272 0.20 1.14 1.07 10.45 3070.54
28 140 2.33 3.5 0.890 0.20 0.80 0.69 6.71 1949.78
29 145 2.42 6.8 1.730 0.20 1.56 1.53 14.93 4415.45
30 150 2.50 7.3 1.857 0.20 1.67 1.65 16.18 4789.04
31 155 2.58 8.2 2.086 0.20 1.88 1.88 18.42 5461.49
32 160 2.67 5.9 1.501 0.20 1.35 1.30 12.69 3742.99
33 165 2.75 2.0 0.509 0.20 0.46 0.30 2.98 829.02
34 170 2.83 1.8 0.458 0.20 0.41 0.25 2.48 679.59
35 175 2.92 1.8 0.458 0.20 0.41 0.25 2.48 679.59
36 180 3.00 0.6 0.153 0.20 0.14 0.02 0.15 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.51
FLOOD VOLUME (acft) 1.23
FLOOD VOLUME (cuft) 53707.39
REQUIRED STORAGE (acft) 1.17
REQUIRED STORAGE (cuft) 50982.60
PEAK FLOW RATE (cfs) 18.42
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 9.79
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.38
UNIT TIME-PERCENT OF LAG 362.1
TOTAL ADJUSTED STORM RAIN-INCHES 2.78
CONSTANT LOSS RATE-in/hr 0.205
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.21 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.167 0.20 0.15 0.02 0.16 0.00
2 10 0.17 0.6 0.200 0.20 0.18 0.02 0.20 0.00
3 15 0.25 0.6 0.200 0.20 0.18 0.02 0.20 0.00
4 20 0.33 0.6 0.200 0.20 0.18 0.02 0.20 0.00
5 25 0.42 0.6 0.200 0.20 0.18 0.02 0.20 0.00
6 30 0.50 0.7 0.234 0.20 0.21 0.03 0.28 20.52
7 35 0.58 0.7 0.234 0.20 0.21 0.03 0.28 20.52
8 40 0.67 0.7 0.234 0.20 0.21 0.03 0.28 20.52
9 45 0.75 0.7 0.234 0.20 0.21 0.03 0.28 20.52
10 50 0.83 0.7 0.234 0.20 0.21 0.03 0.28 20.52
11 55 0.92 0.7 0.234 0.20 0.21 0.03 0.28 20.52
12 60 1.00 0.8 0.267 0.20 0.24 0.06 0.61 118.50
13 65 1.08 0.8 0.267 0.20 0.24 0.06 0.61 118.50
14 70 1.17 0.8 0.267 0.20 0.24 0.06 0.61 118.50
15 75 1.25 0.8 0.267 0.20 0.24 0.06 0.61 118.50
16 80 1.33 0.8 0.267 0.20 0.24 0.06 0.61 118.50
17 85 1.42 0.8 0.267 0.20 0.24 0.06 0.61 118.50
18 90 1.50 0.8 0.267 0.20 0.24 0.06 0.61 118.50
19 95 1.58 0.8 0.267 0.20 0.24 0.06 0.61 118.50
20 100 1.67 0.8 0.267 0.20 0.24 0.06 0.61 118.50
21 105 1.75 0.8 0.267 0.20 0.24 0.06 0.61 118.50
22 110 1.83 0.8 0.267 0.20 0.24 0.06 0.61 118.50
23 115 1.92 0.8 0.267 0.20 0.24 0.06 0.61 118.50
24 120 2.00 0.9 0.300 0.20 0.27 0.10 0.93 216.48
25 125 2.08 0.8 0.267 0.20 0.24 0.06 0.61 118.50
26 130 2.17 0.9 0.300 0.20 0.27 0.10 0.93 216.48
27 135 2.25 0.9 0.300 0.20 0.27 0.10 0.93 216.48
28 140 2.33 0.9 0.300 0.20 0.27 0.10 0.93 216.48
29 145 2.42 0.9 0.300 0.20 0.27 0.10 0.93 216.48
30 150 2.50 0.9 0.300 0.20 0.27 0.10 0.93 216.48
31 155 2.58 0.9 0.300 0.20 0.27 0.10 0.93 216.48
32 160 2.67 0.9 0.300 0.20 0.27 0.10 0.93 216.48
33 165 2.75 1.0 0.334 0.20 0.30 0.13 1.26 314.46
34 170 2.83 1.0 0.334 0.20 0.30 0.13 1.26 314.46
35 175 2.92 1.0 0.334 0.20 0.30 0.13 1.26 314.46
36 180 3.00 1.0 0.334 0.20 0.30 0.13 1.26 314.46
37 185 3.08 1.0 0.334 0.20 0.30 0.13 1.26 314.46
38 190 3.17 1.1 0.367 0.20 0.33 0.16 1.59 412.44
39 195 3.25 1.1 0.367 0.20 0.33 0.16 1.59 412.44
40 200 3.33 1.1 0.367 0.20 0.33 0.16 1.59 412.44
41 205 3.42 1.2 0.400 0.20 0.36 0.20 1.91 510.41
42 210 3.50 1.3 0.434 0.20 0.39 0.23 2.24 608.39
43 215 3.58 1.4 0.467 0.20 0.42 0.26 2.57 706.37
44 220 3.67 1.4 0.467 0.20 0.42 0.26 2.57 706.37
45 225 3.75 1.5 0.500 0.20 0.45 0.30 2.89 804.35
46 230 3.83 1.5 0.500 0.20 0.45 0.30 2.89 804.35
47 235 3.92 1.6 0.534 0.20 0.48 0.33 3.22 902.33
48 240 4.00 1.6 0.534 0.20 0.48 0.33 3.22 902.33
49 245 4.08 1.7 0.567 0.20 0.51 0.36 3.55 1000.31
50 250 4.17 1.8 0.600 0.20 0.54 0.40 3.87 1098.28
51 255 4.25 1.9 0.634 0.20 0.57 0.43 4.20 1196.26
52 260 4.33 2.0 0.667 0.20 0.60 0.46 4.53 1294.24
53 265 4.42 2.1 0.701 0.20 0.63 0.50 4.85 1392.22
54 270 4.50 2.1 0.701 0.20 0.63 0.50 4.85 1392.22
55 275 4.58 2.2 0.734 0.20 0.66 0.53 5.18 1490.20
56 280 4.67 2.3 0.767 0.20 0.69 0.56 5.51 1588.18

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.801 0.20 0.72 0.60 5.83 1686.15
58 290 4.83 2.4 0.801 0.20 0.72 0.60 5.83 1686.15
59 295 4.92 2.5 0.834 0.20 0.75 0.63 6.16 1784.13
60 300 5.00 2.6 0.867 0.20 0.78 0.66 6.49 1882.11
61 305 5.08 3.1 1.034 0.20 0.93 0.83 8.12 2372.00
62 310 5.17 3.6 1.201 0.20 1.08 1.00 9.75 2861.89
63 315 5.25 3.9 1.301 0.20 1.17 1.10 10.73 3155.83
64 320 5.33 4.2 1.401 0.20 1.26 1.20 11.71 3449.76
65 325 5.42 4.7 1.568 0.20 1.41 1.36 13.35 3939.66
66 330 5.50 5.6 1.868 0.20 1.68 1.66 16.28 4821.46
67 335 5.58 1.9 0.634 0.20 0.57 0.43 4.20 1196.26
68 340 5.67 0.9 0.300 0.20 0.27 0.10 0.93 216.48
69 345 5.75 0.6 0.200 0.20 0.18 0.02 0.20 0.00
70 350 5.83 0.5 0.167 0.20 0.15 0.02 0.16 0.00
71 355 5.92 0.3 0.100 0.20 0.09 0.01 0.10 0.00
72 360 6.00 0.2 0.067 0.20 0.06 0.01 0.07 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.59
FLOOD VOLUME (acft) 1.30
FLOOD VOLUME (cuft) 56587.21
REQUIRED STORAGE (acft) 1.19
REQUIRED STORAGE (cuft) 51653.82
PEAK FLOW RATE (cfs) 16.28
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 9.790 CONSTANT LOSS RATE-in/hr n/a
UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.2048 LAG TIME - MINUTES 1.38 MINIMUM LOSS RATE (for var. loss) - in/hr 0.102 UNIT TIME-PERCENT OF LAG 1086.4 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 4.47 C 0.00190
PERCOLATION RATE (cfs) 0.21
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.036 0.362 0.032 0.004 0.04 0.00
2 30 0.50 0.3 0.054 0.357 0.048 0.005 0.05 0.00
3 45 0.75 0.3 0.054 0.353 0.048 0.005 0.05 0.00
4 60 1.00 0.4 0.072 0.349 0.064 0.007 0.07 0.00
5 75 1.25 0.3 0.054 0.345 0.048 0.005 0.05 0.00
6 90 1.50 0.3 0.054 0.341 0.048 0.005 0.05 0.00
7 105 1.75 0.3 0.054 0.337 0.048 0.005 0.05 0.00
8 120 2.00 0.4 0.072 0.333 0.064 0.007 0.07 0.00
9 135 2.25 0.4 0.072 0.329 0.064 0.007 0.07 0.00
10 150 2.50 0.4 0.072 0.325 0.064 0.007 0.07 0.00
11 165 2.75 0.5 0.089 0.321 0.080 0.009 0.09 0.00
12 180 3.00 0.5 0.089 0.317 0.080 0.009 0.09 0.00
13 195 3.25 0.5 0.089 0.313 0.080 0.009 0.09 0.00
14 210 3.50 0.5 0.089 0.309 0.080 0.009 0.09 0.00
15 225 3.75 0.5 0.089 0.305 0.080 0.009 0.09 0.00
16 240 4.00 0.6 0.107 0.301 0.097 0.011 0.11 0.00
17 255 4.25 0.6 0.107 0.297 0.097 0.011 0.11 0.00
18 270 4.50 0.7 0.125 0.294 0.113 0.013 0.12 0.00
19 285 4.75 0.7 0.125 0.290 0.113 0.013 0.12 0.00
20 300 5.00 0.8 0.143 0.286 0.129 0.014 0.14 0.00
21 315 5.25 0.6 0.107 0.282 0.097 0.011 0.11 0.00
22 330 5.50 0.7 0.125 0.279 0.113 0.013 0.12 0.00
23 345 5.75 0.8 0.143 0.275 0.129 0.014 0.14 0.00
24 360 6.00 0.8 0.143 0.272 0.129 0.014 0.14 0.00
25 375 6.25 0.9 0.161 0.268 0.145 0.016 0.16 0.00
26 390 6.50 0.9 0.161 0.264 0.145 0.016 0.16 0.00
27 405 6.75 1.0 0.179 0.261 0.161 0.018 0.18 0.00
28 420 7.00 1.0 0.179 0.257 0.161 0.018 0.18 0.00
29 435 7.25 1.0 0.179 0.254 0.161 0.018 0.18 0.00
30 450 7.50 1.1 0.197 0.250 0.177 0.020 0.19 0.00
31 465 7.75 1.2 0.215 0.247 0.193 0.021 0.21 0.00
32 480 8.00 1.3 0.232 0.243 0.209 0.023 0.23 13.15
33 495 8.25 1.5 0.268 0.240 0.241 0.028 0.28 55.92
34 510 8.50 1.5 0.268 0.237 0.241 0.031 0.31 85.41
35 525 8.75 1.6 0.286 0.233 0.257 0.053 0.52 272.18
36 540 9.00 1.7 0.304 0.230 0.274 0.074 0.72 458.69
37 555 9.25 1.9 0.340 0.227 0.306 0.113 1.10 802.48
38 570 9.50 2.0 0.358 0.224 0.322 0.134 1.31 988.46
39 585 9.75 2.1 0.375 0.220 0.338 0.155 1.52 1174.18
40 600 10.00 2.2 0.393 0.217 0.354 0.176 1.72 1359.63
41 615 10.25 1.5 0.268 0.214 0.241 0.054 0.53 284.49
42 630 10.50 1.5 0.268 0.211 0.241 0.057 0.56 311.86
43 645 10.75 2.0 0.358 0.208 0.322 0.150 1.46 1126.65
44 660 11.00 2.0 0.358 0.205 0.322 0.153 1.49 1153.47
45 675 11.25 1.9 0.340 0.202 0.306 0.138 1.35 1022.46
46 690 11.50 1.9 0.340 0.199 0.306 0.141 1.38 1048.71
47 705 11.75 1.7 0.304 0.196 0.274 0.108 1.06 759.60
48 720 12.00 1.8 0.322 0.193 0.290 0.129 1.26 942.83
49 735 12.25 2.5 0.447 0.190 0.402 0.257 2.51 2071.00
50 750 12.50 2.6 0.465 0.187 0.418 0.278 2.72 2253.64
51 765 12.75 2.8 0.501 0.185 0.451 0.316 3.09 2593.53
52 780 13.00 2.9 0.519 0.182 0.467 0.337 3.30 2775.58
53 795 13.25 3.4 0.608 0.179 0.547 0.429 4.20 3587.49
54 810 13.50 3.4 0.608 0.176 0.547 0.432 4.23 3611.39
55 825 13.75 2.3 0.411 0.174 0.370 0.238 2.33 1902.04
56 840 14.00 2.3 0.411 0.171 0.370 0.240 2.35 1925.32
57 855 14.25 2.7 0.483 0.168 0.434 0.314 3.08 2578.46
58 870 14.50 2.6 0.465 0.166 0.418 0.299 2.93 2443.57
59 885 14.75 2.6 0.465 0.163 0.418 0.302 2.95 2465.90
60 900 15.00 2.5 0.447 0.161 0.402 0.286 2.80 2330.36
61 915 15.25 2.4 0.429 0.158 0.386 0.271 2.65 2194.50
62 930 15.50 2.3 0.411 0.156 0.370 0.255 2.50 2058.30
63 945 15.75 1.9 0.340 0.153 0.306 0.186 1.82 1449.14
64 960 16.00 1.9 0.340 0.151 0.306 0.189 1.85 1469.81
65 975 16.25 0.4 0.072 0.149 0.064 0.007 0.07 0.00
66 990 16.50 0.4 0.072 0.147 0.064 0.007 0.07 0.00
67 1005 16.75 0.3 0.054 0.144 0.048 0.005 0.05 0.00
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 7 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
68 1020 17.00 0.3 0.054 0.142 0.048 0.005 0.05 0.00
69 1035 17.25 0.5 0.089 0.140 0.080 0.009 0.09 0.00
70 1050 17.50 0.5 0.089 0.138 0.080 0.009 0.09 0.00
71 1065 17.75 0.5 0.089 0.136 0.080 0.009 0.09 0.00
72 1080 18.00 0.4 0.072 0.134 0.064 0.007 0.07 0.00
73 1095 18.25 0.4 0.072 0.132 0.064 0.007 0.07 0.00
74 1110 18.50 0.4 0.072 0.130 0.064 0.007 0.07 0.00
75 1125 18.75 0.3 0.054 0.128 0.048 0.005 0.05 0.00
76 1140 19.00 0.2 0.036 0.126 0.032 0.004 0.04 0.00
77 1155 19.25 0.3 0.054 0.124 0.048 0.005 0.05 0.00
78 1170 19.50 0.4 0.072 0.123 0.064 0.007 0.07 0.00
79 1185 19.75 0.3 0.054 0.121 0.048 0.005 0.05 0.00
80 1200 20.00 0.2 0.036 0.119 0.032 0.004 0.04 0.00
81 1215 20.25 0.3 0.054 0.118 0.048 0.005 0.05 0.00
82 1230 20.50 0.3 0.054 0.116 0.048 0.005 0.05 0.00
83 1245 20.75 0.3 0.054 0.115 0.048 0.005 0.05 0.00
84 1260 21.00 0.2 0.036 0.113 0.032 0.004 0.04 0.00
85 1275 21.25 0.3 0.054 0.112 0.048 0.005 0.05 0.00
86 1290 21.50 0.2 0.036 0.111 0.032 0.004 0.04 0.00
87 1305 21.75 0.3 0.054 0.110 0.048 0.005 0.05 0.00
88 1320 22.00 0.2 0.036 0.108 0.032 0.004 0.04 0.00
89 1335 22.25 0.3 0.054 0.107 0.048 0.005 0.05 0.00
90 1350 22.50 0.2 0.036 0.106 0.032 0.004 0.04 0.00
91 1365 22.75 0.2 0.036 0.105 0.032 0.004 0.04 0.00
92 1380 23.00 0.2 0.036 0.105 0.032 0.004 0.04 0.00
93 1395 23.25 0.2 0.036 0.104 0.032 0.004 0.04 0.00
94 1410 23.50 0.2 0.036 0.103 0.032 0.004 0.04 0.00
95 1425 23.75 0.2 0.036 0.103 0.032 0.004 0.04 0.00
96 1440 24.00 0.2 0.036 0.102 0.032 0.004 0.04 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.71
FLOOD VOLUME (acft) 1.40
FLOOD VOLUME (cuft) 60935.59
REQUIRED STORAGE (acft) 1.14
REQUIRED STORAGE (cuft) 49570.20
PEAK FLOW (cfs) 4.23
Plate E-2.2

Page 8 of 14 ends

Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

INCR TOTAL INCR TOTAL INCR TOTAL
(ft) (ft) (sf) (sf) (cuft) (cuft) (acre-ft)
464.5 0 0 13730 0 0 0.00
465.5 1 1 1470 15200 14465 14465 0.33
466.5 1 2 1500 16700 15950 30415 0.70
467.5 1 3 1570 18270 17485 47900 1.10
468 0.5 3.5 805 19075 9336 57236 1.31

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.21 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.21 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 1.23 370 370 64 306 464.52 306 0.01
2 10 1.23 370 676 64 612 464.54 612 0.01
3 15 0.73 220 832 64 769 464.55 769 0.02
4 20 1.73 519 1,288 64 1,224 464.58 1,224 0.03
5 25 1.73 519 1,743 64 1,679 464.62 1,679 0.04
6 30 2.48 743 2,423 64 2,359 464.66 2,359 0.05
7 35 1.73 519 2,878 64 2,814 464.69 2,814 0.06
8 40 2.48 743 3,558 64 3,494 464.74 3,494 0.08
9 45 2.48 743 4,238 64 4,174 464.79 4,174 0.10
10 50 1.73 519 4,693 64 4,629 464.82 4,629 0.11
11 55 1.98 594 5,223 64 5,159 464.86 5,159 0.12
12 60 2.48 743 5,903 64 5,839 464.90 5,839 0.13
13 65 3.47 1,042 6,881 64 6,817 464.97 6,817 0.16
14 70 3.47 1,042 7,860 64 7,796 465.04 7,796 0.18
15 75 3.47 1,042 8,838 64 8,774 465.11 8,774 0.20
16 80 2.98 893 9,667 64 9,603 465.16 9,603 0.22
17 85 4.47 1,341 10,944 64 10,881 465.25 10,881 0.25
18 90 4.72 1,416 12,296 64 12,233 465.35 12,233 0.28
19 95 3.97 1,192 13,424 64 13,360 465.42 13,360 0.31
20 100 4.72 1,416 14,776 64 14,712 465.52 14,712 0.34
21 105 6.21 1,864 16,577 64 16,513 465.63 16,513 0.38
22 110 5.72 1,715 18,228 64 18,164 465.73 18,164 0.42
23 115 5.22 1,565 19,729 64 19,665 465.83 19,665 0.45
24 120 5.47 1,640 21,305 64 21,241 465.92 21,241 0.49
25 125 5.72 1,715 22,956 64 22,892 466.03 22,892 0.53
26 130 8.46 2,537 25,429 64 25,365 466.18 25,365 0.58
27 135 10.45 3,134 28,500 64 28,436 466.38 28,436 0.65
28 140 6.71 2,014 30,449 64 30,385 466.50 30,385 0.70
29 145 14.93 4,479 34,865 64 34,801 466.75 34,801 0.80
30 150 16.18 4,853 39,654 64 39,590 467.02 39,590 0.91
31 155 18.42 5,525 45,115 64 45,051 467.34 45,051 1.03
32 160 12.69 3,807 48,858 64 48,794 467.55 48,794 1.12
33 165 2.98 893 49,687 64 49,623 467.59 49,623 1.14
34 170 2.48 743 50,367 64 50,303 467.63 50,303 1.15
35 175 2.48 743 51,046 64 50,983 467.67 50,983 1.17
36 180 0.15 45 51,027 64 50,964 467.66 50,964 1.17

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.16 49 49 64 - 464.50 - 0.00
2 10 0.20 59 59 64 - 464.50 - 0.00
3 15 0.20 59 59 64 - 464.50 - 0.00
4 20 0.20 59 59 64 - 464.50 - 0.00
5 25 0.20 59 59 64 - 464.50 - 0.00
6 30 0.28 84 84 64 21 464.50 21 0.00
7 35 0.28 84 105 64 41 464.50 41 0.00
8 40 0.28 84 125 64 62 464.50 62 0.00
9 45 0.28 84 146 64 82 464.51 82 0.00
10 50 0.28 84 166 64 103 464.51 103 0.00
11 55 0.28 84 187 64 123 464.51 123 0.00
12 60 0.61 182 306 64 242 464.52 242 0.01
13 65 0.61 182 424 64 360 464.52 360 0.01
14 70 0.61 182 543 64 479 464.53 479 0.01
15 75 0.61 182 661 64 597 464.54 597 0.01
16 80 0.61 182 780 64 716 464.55 716 0.02
17 85 0.61 182 898 64 834 464.56 834 0.02
18 90 0.61 182 1,017 64 953 464.57 953 0.02
19 95 0.61 182 1,135 64 1,071 464.57 1,071 0.02
20 100 0.61 182 1,254 64 1,190 464.58 1,190 0.03
21 105 0.61 182 1,372 64 1,308 464.59 1,308 0.03
22 110 0.61 182 1,491 64 1,427 464.60 1,427 0.03
23 115 0.61 182 1,609 64 1,545 464.61 1,545 0.04
24 120 0.93 280 1,826 64 1,762 464.62 1,762 0.04
25 125 0.61 182 1,944 64 1,880 464.63 1,880 0.04
26 130 0.93 280 2,161 64 2,097 464.64 2,097 0.05
27 135 0.93 280 2,377 64 2,313 464.66 2,313 0.05
28 140 0.93 280 2,593 64 2,530 464.67 2,530 0.06
29 145 0.93 280 2,810 64 2,746 464.69 2,746 0.06
30 150 0.93 280 3,026 64 2,963 464.70 2,963 0.07
31 155 0.93 280 3,243 64 3,179 464.72 3,179 0.07
32 160 0.93 280 3,459 64 3,395 464.73 3,395 0.08
33 165 1.26 378 3,774 64 3,710 464.76 3,710 0.09
34 170 1.26 378 4,088 64 4,024 464.78 4,024 0.09
35 175 1.26 378 4,403 64 4,339 464.80 4,339 0.10
36 180 1.26 378 4,717 64 4,653 464.82 4,653 0.11
37 185 1.26 378 5,032 64 4,968 464.84 4,968 0.11
38 190 1.59 476 5,444 64 5,380 464.87 5,380 0.12
39 195 1.59 476 5,857 64 5,793 464.90 5,793 0.13
40 200 1.59 476 6,269 64 6,205 464.93 6,205 0.14
41 205 1.91 574 6,779 64 6,716 464.96 6,716 0.15
42 210 2.24 672 7,388 64 7,324 465.01 7,324 0.17
43 215 2.57 770 8,094 64 8,030 465.06 8,030 0.18
44 220 2.57 770 8,801 64 8,737 465.10 8,737 0.20
45 225 2.89 868 9,605 64 9,541 465.16 9,541 0.22
46 230 2.89 868 10,409 64 10,345 465.22 10,345 0.24
47 235 3.22 966 11,312 64 11,248 465.28 11,248 0.26
48 240 3.22 966 12,214 64 12,150 465.34 12,150 0.28
49 245 3.55 1,064 13,214 64 13,150 465.41 13,150 0.30
50 250 3.87 1,162 14,312 64 14,249 465.49 14,249 0.33
51 255 4.20 1,260 15,509 64 15,445 465.56 15,445 0.35
52 260 4.53 1,358 16,803 64 16,739 465.64 16,739 0.38
53 265 4.85 1,456 18,195 64 18,131 465.73 18,131 0.42
54 270 4.85 1,456 19,587 64 19,524 465.82 19,524 0.45
55 275 5.18 1,554 21,078 64 21,014 465.91 21,014 0.48

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 11 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 5.51 1,652 22,666 64 22,602 466.01 22,602 0.52
57 285 5.83 1,750 24,352 64 24,288 466.12 24,288 0.56
58 290 5.83 1,750 26,038 64 25,974 466.22 25,974 0.60
59 295 6.16 1,848 27,822 64 27,758 466.33 27,758 0.64
60 300 6.49 1,946 29,704 64 29,640 466.45 29,640 0.68
61 305 8.12 2,436 32,076 64 32,012 466.59 32,012 0.73
62 310 9.75 2,926 34,938 64 34,874 466.76 34,874 0.80
63 315 10.73 3,220 38,094 64 38,030 466.94 38,030 0.87
64 320 11.71 3,514 41,544 64 41,480 467.13 41,480 0.95
65 325 13.35 4,004 45,483 64 45,420 467.36 45,420 1.04
66 330 16.28 4,885 50,305 64 50,241 467.63 50,241 1.15
67 335 4.20 1,260 51,501 64 51,437 467.69 51,437 1.18
68 340 0.93 280 51,718 64 51,654 467.70 51,654 1.19
69 345 0.20 59 51,713 64 51,649 467.70 51,649 1.19
70 350 0.16 49 51,698 64 51,634 467.70 51,634 1.19
71 355 0.10 29 51,663 64 51,599 467.70 51,599 1.18
72 360 0.07 20 51,619 64 51,555 467.70 51,555 1.18
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.04 32 32 192 - 464.50 - 0.00
2 30 0.05 47 47 192 - 464.50 - 0.00
3 45 0.05 47 47 192 - 464.50 - 0.00
4 60 0.07 63 63 192 - 464.50 - 0.00
5 75 0.05 47 47 192 - 464.50 - 0.00
6 90 0.05 47 47 192 - 464.50 - 0.00
7 105 0.05 47 47 192 - 464.50 - 0.00
8 120 0.07 63 63 192 - 464.50 - 0.00
9 135 0.07 63 63 192 - 464.50 - 0.00
10 150 0.07 63 63 192 - 464.50 - 0.00
11 165 0.09 79 79 192 - 464.50 - 0.00
12 180 0.09 79 79 192 - 464.50 - 0.00
13 195 0.09 79 79 192 - 464.50 - 0.00
14 210 0.09 79 79 192 - 464.50 - 0.00
15 225 0.09 79 79 192 - 464.50 - 0.00
16 240 0.11 95 95 192 - 464.50 - 0.00
17 255 0.11 95 95 192 - 464.50 - 0.00
18 270 0.12 110 110 192 - 464.50 - 0.00
19 285 0.12 110 110 192 - 464.50 - 0.00
20 300 0.14 126 126 192 - 464.50 - 0.00
21 315 0.11 95 95 192 - 464.50 - 0.00
22 330 0.12 110 110 192 - 464.50 - 0.00
23 345 0.14 126 126 192 - 464.50 - 0.00
24 360 0.14 126 126 192 - 464.50 - 0.00
25 375 0.16 142 142 192 - 464.50 - 0.00
26 390 0.16 142 142 192 - 464.50 - 0.00
27 405 0.18 158 158 192 - 464.50 - 0.00
28 420 0.18 158 158 192 - 464.50 - 0.00
29 435 0.18 158 158 192 - 464.50 - 0.00
30 450 0.19 173 173 192 - 464.50 - 0.00
31 465 0.21 189 189 192 - 464.50 - 0.00
32 480 0.23 205 205 192 13 464.50 13 0.00
33 495 0.28 248 261 192 69 464.50 69 0.00
34 510 0.31 277 346 192 154 464.51 154 0.00
35 525 0.52 464 618 192 427 464.53 427 0.01
36 540 0.72 650 1,077 192 885 464.56 885 0.02
37 555 1.10 994 1,879 192 1,688 464.62 1,688 0.04
38 570 1.31 1,180 2,868 192 2,676 464.69 2,676 0.06
39 585 1.52 1,366 4,042 192 3,850 464.77 3,850 0.09
40 600 1.72 1,551 5,402 192 5,210 464.86 5,210 0.12
41 615 0.53 476 5,686 192 5,495 464.88 5,495 0.13
42 630 0.56 504 5,998 192 5,806 464.90 5,806 0.13
43 645 1.46 1,318 7,125 192 6,933 464.98 6,933 0.16
44 660 1.49 1,345 8,278 192 8,087 465.06 8,087 0.19
45 675 1.35 1,214 9,301 192 9,109 465.13 9,109 0.21
46 690 1.38 1,240 10,349 192 10,158 465.20 10,158 0.23
47 705 1.06 951 11,109 192 10,917 465.25 10,917 0.25
48 720 1.26 1,134 12,052 192 11,860 465.32 11,860 0.27
49 735 2.51 2,263 14,123 192 13,931 465.46 13,931 0.32
50 750 2.72 2,445 16,376 192 16,185 465.61 16,185 0.37
51 765 3.09 2,785 18,970 192 18,778 465.77 18,778 0.43
52 780 3.30 2,967 21,746 192 21,554 465.94 21,554 0.49
53 795 4.20 3,779 25,333 192 25,141 466.17 25,141 0.58
54 810 4.23 3,803 28,944 192 28,753 466.40 28,753 0.66
55 825 2.33 2,094 30,846 192 30,655 466.51 30,655 0.70
56 840 2.35 2,117 32,772 192 32,580 466.62 32,580 0.75
57 855 3.08 2,770 35,350 192 35,159 466.77 35,159 0.81
58 870 2.93 2,635 37,794 192 37,602 466.91 37,602 0.86

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 2.95 2,658 40,260 192 40,068 467.05 40,068 0.92
60 900 2.80 2,522 42,590 192 42,398 467.19 42,398 0.97
61 915 2.65 2,386 44,785 192 44,593 467.31 44,593 1.02
62 930 2.50 2,250 46,843 192 46,651 467.43 46,651 1.07
63 945 1.82 1,641 48,292 192 48,100 467.51 48,100 1.10
64 960 1.85 1,661 49,762 192 49,570 467.59 49,570 1.14
65 975 0.07 63 49,633 192 49,442 467.58 49,442 1.14
66 990 0.07 63 49,505 192 49,313 467.58 49,313 1.13
67 1005 0.05 47 49,360 192 49,169 467.57 49,169 1.13
68 1020 0.05 47 49,216 192 49,024 467.56 49,024 1.13
69 1035 0.09 79 49,103 192 48,911 467.55 48,911 1.12
70 1050 0.09 79 48,990 192 48,798 467.55 48,798 1.12
71 1065 0.09 79 48,877 192 48,686 467.54 48,686 1.12
72 1080 0.07 63 48,749 192 48,557 467.54 48,557 1.11
73 1095 0.07 63 48,620 192 48,428 467.53 48,428 1.11
74 1110 0.07 63 48,491 192 48,300 467.52 48,300 1.11
75 1125 0.05 47 48,347 192 48,155 467.51 48,155 1.11
76 1140 0.04 48,187 32 192 47,995 467.51 47,995 1.10
77 1155 0.05 47 48,042 192 47,851 467.50 47,851 1.10
78 1170 0.07 63 47,914 192 47,722 467.49 47,722 1.10
79 1185 0.05 47 47,769 192 47,578 467.48 47,578 1.09
80 1200 0.04 32 47,609 192 47,418 467.47 47,418 1.09
81 1215 0.05 47 47,465 192 47,273 467.46 47,273 1.09
82 1230 0.05 47 47,320 192 47,129 467.46 47,129 1.08
83 1245 0.05 47 47,176 192 46,984 467.45 46,984 1.08
84 1260 0.04 32 47,016 192 46,824 467.44 46,824 1.07
85 1275 0.05 47 46,872 192 46,680 467.43 46,680 1.07
86 1290 0.04 32 46,711 192 46,520 467.42 46,520 1.07
87 1305 0.05 47 46,567 192 46,375 467.41 46,375 1.06
88 1320 0.04 32 46,407 192 46,215 467.40 46,215 1.06
89 1335 0.05 47 46,262 192 46,071 467.40 46,071 1.06
90 1350 0.04 32 46,102 192 45,911 467.39 45,911 1.05
91 1365 0.04 32 45,942 192 45,751 467.38 45,751 1.05
92 1380 0.04 32 45,782 192 45,590 467.37 45,590 1.05
93 1395 0.04 32 45,622 192 45,430 467.36 45,430 1.04
94 1410 0.04 32 45,462 192 45,270 467.35 45,270 1.04
95 1425 0.04 32 45,302 192 45,110 467.34 45,110 1.04
96 1440 0.04 32 45,142 192 44,950 467.33 44,950 1.03
Basin Depth Analysis

Page 14 of 14 ends

Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 100 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 5

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 1.95
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE
MF - CONDOMINIUMS 4.71

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 2.83

RETENTION BASIN

GOLF COURSE

MOUNTAINOUS
LOW LOSS RATE (PERCENT) 90%
LENGTH OF WATERCOURSE (L) 950
LENGTH TO POINT OPPOSITE CENTROID (Lca) 310
ELEVATION OF HEADWATER 471
ELEVATION OF CONCENTRATION POINT 467
AVERAGE MANNINGS 'N' VALUE 0.02
STORM FREQUENCY (YEAR) 100

POINT RAIN
3-HOUR 2.12
6-HOUR 2.78
24-HOUR 4.47
BASIN CHARACTERISTICS: ELEVATION AREA
463.5 17610
464.5 19400
465.5 21240
466.5 23140
467 24110
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
708
Item 2.

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

2.12 9.490 1.00 2.12 2.78 9.490 1.00 2.78 4.47 9.490 1.00 4.47

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 9.49 SUM [7] 2.12 SUM [9] 9.49 SUM [11] 2.78 SUM [13] 9.49 SUM [15] 4.47 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 2.12 2.78 4.47
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 1.31 1.30 1.28
FLOOD VOLUME (cu-ft) 45,222 44,840 44,164
(acre-ft) 1.04 1.03 1.01
REQUIRED STORAGE (cu-ft) 41,999 39,086 31,405
(acre-ft) 0.96 0.90 0.72
PEAK FLOW (cfs) 17.21 15.14 3.54
MAXIMUM WSEL (ft) 465.64 465.51 465.13

0.180
310.00

0.002
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 4
[11] S-FEET/MILE

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 5

9.490
950

0.059
471
467

0.05 2.8

2.8 5.7

22.2 4.72

0.27 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 100 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

RATE IMPERVIOUS RATE
(in/hr) (in/hr) (in/hr)
[Plate C-1] [Plate E-6.1] [Plate E-6.2] [Plate E-6.3]
B 56 0.52 90% 0.10 0.00 0.000 0.0000
B 56 0.52 100% 0.05 1.95 0.205 0.0107
B 56 0.52 20% 0.43 0.00 0.000 0.0000B 56 0.52 40% 0.33 0.00 0.000 0.0000B 56 0.52 50% 0.29 0.00 0.000 0.0000B 56 0.52 65% 0.22 4.71 0.496 0.1071B 56 0.52 80% 0.15 0.00 0.000 0.0000B 56 0.52 75% 0.17 0.00 0.000 0.0000B 56 0.52 0% 0.52 2.83 0.298 0.1551B 56 0.52 0% 0.52 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.00 0.000 0.0000 D 93 0.95 90% 0.18 0.00 0.000 0.0000

0.00 0.000 0.0000

0.00 0.000 0.0000
SUM 9.49 SUM 0.2729
VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY)Fm= 0.136428767C= 0.00253Ft=C(24-(T/60))^1.55 = 0.00253 0.14 in/hr LOW LOSS RATE (80-90 PERCENT) = 90%Where:T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,T=1 1/2 unit time for the second period, etc. (24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 9.49
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 2.83
UNIT TIME-PERCENT OF LAG 176.4
TOTAL ADJUSTED STORM RAIN-INCHES 2.12
CONSTANT LOSS RATE-in/hr 0.27
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.27 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.331 0.27 0.30 0.06 0.55 82.80
2 10 0.17 1.3 0.331 0.27 0.30 0.06 0.55 82.80
3 15 0.25 1.1 0.280 0.27 0.25 0.01 0.07 0.00
4 20 0.33 1.5 0.382 0.27 0.34 0.11 1.03 227.65
5 25 0.42 1.5 0.382 0.27 0.34 0.11 1.03 227.65
6 30 0.50 1.8 0.458 0.27 0.41 0.19 1.76 444.94
7 35 0.58 1.5 0.382 0.27 0.34 0.11 1.03 227.65
8 40 0.67 1.8 0.458 0.27 0.41 0.19 1.76 444.94
9 45 0.75 1.8 0.458 0.27 0.41 0.19 1.76 444.94
10 50 0.83 1.5 0.382 0.27 0.34 0.11 1.03 227.65
11 55 0.92 1.6 0.407 0.27 0.37 0.13 1.27 300.08
12 60 1.00 1.8 0.458 0.27 0.41 0.19 1.76 444.94
13 65 1.08 2.2 0.560 0.27 0.50 0.29 2.72 734.65
14 70 1.17 2.2 0.560 0.27 0.50 0.29 2.72 734.65
15 75 1.25 2.2 0.560 0.27 0.50 0.29 2.72 734.65
16 80 1.33 2.0 0.509 0.27 0.46 0.24 2.24 589.79
17 85 1.42 2.6 0.661 0.27 0.60 0.39 3.69 1024.36
18 90 1.50 2.7 0.687 0.27 0.62 0.41 3.93 1096.79
19 95 1.58 2.4 0.611 0.27 0.55 0.34 3.20 879.50
20 100 1.67 2.7 0.687 0.27 0.62 0.41 3.93 1096.79
21 105 1.75 3.3 0.840 0.27 0.76 0.57 5.38 1531.35
22 110 1.83 3.1 0.789 0.27 0.71 0.52 4.89 1386.50
23 115 1.92 2.9 0.738 0.27 0.66 0.46 4.41 1241.64
24 120 2.00 3.0 0.763 0.27 0.69 0.49 4.65 1314.07
25 125 2.08 3.1 0.789 0.27 0.71 0.52 4.89 1386.50
26 130 2.17 4.2 1.068 0.27 0.96 0.80 7.55 2183.20
27 135 2.25 5.0 1.272 0.27 1.14 1.00 9.48 2762.62
28 140 2.33 3.5 0.890 0.27 0.80 0.62 5.86 1676.21
29 145 2.42 6.8 1.730 0.27 1.56 1.46 13.83 4066.32
30 150 2.50 7.3 1.857 0.27 1.67 1.58 15.03 4428.46
31 155 2.58 8.2 2.086 0.27 1.88 1.81 17.21 5080.31
32 160 2.67 5.9 1.501 0.27 1.35 1.23 11.65 3414.47
33 165 2.75 2.0 0.509 0.27 0.46 0.24 2.24 589.79
34 170 2.83 1.8 0.458 0.27 0.41 0.19 1.76 444.94
35 175 2.92 1.8 0.458 0.27 0.41 0.19 1.76 444.94
36 180 3.00 0.6 0.153 0.27 0.14 0.02 0.14 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.31
FLOOD VOLUME (acft) 1.04
FLOOD VOLUME (cuft) 45221.59
REQUIRED STORAGE (acft) 0.96
REQUIRED STORAGE (cuft) 41998.54
PEAK FLOW RATE (cfs) 17.21
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 9.49
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 2.83
UNIT TIME-PERCENT OF LAG 176.4
TOTAL ADJUSTED STORM RAIN-INCHES 2.78
CONSTANT LOSS RATE-in/hr 0.273
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.27 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.167 0.27 0.15 0.02 0.16 0.00
2 10 0.17 0.6 0.200 0.27 0.18 0.02 0.19 0.00
3 15 0.25 0.6 0.200 0.27 0.18 0.02 0.19 0.00
4 20 0.33 0.6 0.200 0.27 0.18 0.02 0.19 0.00
5 25 0.42 0.6 0.200 0.27 0.18 0.02 0.19 0.00
6 30 0.50 0.7 0.234 0.27 0.21 0.02 0.22 0.00
7 35 0.58 0.7 0.234 0.27 0.21 0.02 0.22 0.00
8 40 0.67 0.7 0.234 0.27 0.21 0.02 0.22 0.00
9 45 0.75 0.7 0.234 0.27 0.21 0.02 0.22 0.00
10 50 0.83 0.7 0.234 0.27 0.21 0.02 0.22 0.00
11 55 0.92 0.7 0.234 0.27 0.21 0.02 0.22 0.00
12 60 1.00 0.8 0.267 0.27 0.24 0.03 0.25 0.00
13 65 1.08 0.8 0.267 0.27 0.24 0.03 0.25 0.00
14 70 1.17 0.8 0.267 0.27 0.24 0.03 0.25 0.00
15 75 1.25 0.8 0.267 0.27 0.24 0.03 0.25 0.00
16 80 1.33 0.8 0.267 0.27 0.24 0.03 0.25 0.00
17 85 1.42 0.8 0.267 0.27 0.24 0.03 0.25 0.00
18 90 1.50 0.8 0.267 0.27 0.24 0.03 0.25 0.00
19 95 1.58 0.8 0.267 0.27 0.24 0.03 0.25 0.00
20 100 1.67 0.8 0.267 0.27 0.24 0.03 0.25 0.00
21 105 1.75 0.8 0.267 0.27 0.24 0.03 0.25 0.00
22 110 1.83 0.8 0.267 0.27 0.24 0.03 0.25 0.00
23 115 1.92 0.8 0.267 0.27 0.24 0.03 0.25 0.00
24 120 2.00 0.9 0.300 0.27 0.27 0.03 0.26 0.00
25 125 2.08 0.8 0.267 0.27 0.24 0.03 0.25 0.00
26 130 2.17 0.9 0.300 0.27 0.27 0.03 0.26 0.00
27 135 2.25 0.9 0.300 0.27 0.27 0.03 0.26 0.00
28 140 2.33 0.9 0.300 0.27 0.27 0.03 0.26 0.00
29 145 2.42 0.9 0.300 0.27 0.27 0.03 0.26 0.00
30 150 2.50 0.9 0.300 0.27 0.27 0.03 0.26 0.00
31 155 2.58 0.9 0.300 0.27 0.27 0.03 0.26 0.00
32 160 2.67 0.9 0.300 0.27 0.27 0.03 0.26 0.00
33 165 2.75 1.0 0.334 0.27 0.30 0.06 0.58 91.00
34 170 2.83 1.0 0.334 0.27 0.30 0.06 0.58 91.00
35 175 2.92 1.0 0.334 0.27 0.30 0.06 0.58 91.00
36 180 3.00 1.0 0.334 0.27 0.30 0.06 0.58 91.00
37 185 3.08 1.0 0.334 0.27 0.30 0.06 0.58 91.00
38 190 3.17 1.1 0.367 0.27 0.33 0.09 0.89 185.97
39 195 3.25 1.1 0.367 0.27 0.33 0.09 0.89 185.97
40 200 3.33 1.1 0.367 0.27 0.33 0.09 0.89 185.97
41 205 3.42 1.2 0.400 0.27 0.36 0.13 1.21 280.95
42 210 3.50 1.3 0.434 0.27 0.39 0.16 1.53 375.93
43 215 3.58 1.4 0.467 0.27 0.42 0.19 1.84 470.90
44 220 3.67 1.4 0.467 0.27 0.42 0.19 1.84 470.90
45 225 3.75 1.5 0.500 0.27 0.45 0.23 2.16 565.88
46 230 3.83 1.5 0.500 0.27 0.45 0.23 2.16 565.88
47 235 3.92 1.6 0.534 0.27 0.48 0.26 2.48 660.85
48 240 4.00 1.6 0.534 0.27 0.48 0.26 2.48 660.85
49 245 4.08 1.7 0.567 0.27 0.51 0.29 2.79 755.83
50 250 4.17 1.8 0.600 0.27 0.54 0.33 3.11 850.81
51 255 4.25 1.9 0.634 0.27 0.57 0.36 3.43 945.78
52 260 4.33 2.0 0.667 0.27 0.60 0.39 3.74 1040.76
53 265 4.42 2.1 0.701 0.27 0.63 0.43 4.06 1135.73
54 270 4.50 2.1 0.701 0.27 0.63 0.43 4.06 1135.73
55 275 4.58 2.2 0.734 0.27 0.66 0.46 4.38 1230.71
56 280 4.67 2.3 0.767 0.27 0.69 0.49 4.69 1325.69

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.801 0.27 0.72 0.53 5.01 1420.66
58 290 4.83 2.4 0.801 0.27 0.72 0.53 5.01 1420.66
59 295 4.92 2.5 0.834 0.27 0.75 0.56 5.33 1515.64
60 300 5.00 2.6 0.867 0.27 0.78 0.59 5.64 1610.61
61 305 5.08 3.1 1.034 0.27 0.93 0.76 7.22 2085.49
62 310 5.17 3.6 1.201 0.27 1.08 0.93 8.81 2560.37
63 315 5.25 3.9 1.301 0.27 1.17 1.03 9.76 2845.30
64 320 5.33 4.2 1.401 0.27 1.26 1.13 10.71 3130.23
65 325 5.42 4.7 1.568 0.27 1.41 1.30 12.29 3605.11
66 330 5.50 5.6 1.868 0.27 1.68 1.60 15.14 4459.89
67 335 5.58 1.9 0.634 0.27 0.57 0.36 3.43 945.78
68 340 5.67 0.9 0.300 0.27 0.27 0.03 0.26 0.00
69 345 5.75 0.6 0.200 0.27 0.18 0.02 0.19 0.00
70 350 5.83 0.5 0.167 0.27 0.15 0.02 0.16 0.00
71 355 5.92 0.3 0.100 0.27 0.09 0.01 0.09 0.00
72 360 6.00 0.2 0.067 0.27 0.06 0.01 0.06 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.30
FLOOD VOLUME (acft) 1.03
FLOOD VOLUME (cuft) 44839.99
REQUIRED STORAGE (acft) 0.90
REQUIRED STORAGE (cuft) 39085.84
PEAK FLOW RATE (cfs) 15.14
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 9.490 CONSTANT LOSS RATE-in/hr n/a
UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.2729 LAG TIME - MINUTES 2.83 MINIMUM LOSS RATE (for var. loss) - in/hr 0.136 UNIT TIME-PERCENT OF LAG 529.1 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 4.47 C 0.00253
PERCOLATION RATE (cfs) 0.27
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.036 0.482 0.032 0.004 0.03 0.00
2 30 0.50 0.3 0.054 0.476 0.048 0.005 0.05 0.00
3 45 0.75 0.3 0.054 0.471 0.048 0.005 0.05 0.00
4 60 1.00 0.4 0.072 0.465 0.064 0.007 0.07 0.00
5 75 1.25 0.3 0.054 0.460 0.048 0.005 0.05 0.00
6 90 1.50 0.3 0.054 0.454 0.048 0.005 0.05 0.00
7 105 1.75 0.3 0.054 0.449 0.048 0.005 0.05 0.00
8 120 2.00 0.4 0.072 0.443 0.064 0.007 0.07 0.00
9 135 2.25 0.4 0.072 0.438 0.064 0.007 0.07 0.00
10 150 2.50 0.4 0.072 0.433 0.064 0.007 0.07 0.00
11 165 2.75 0.5 0.089 0.427 0.080 0.009 0.08 0.00
12 180 3.00 0.5 0.089 0.422 0.080 0.009 0.08 0.00
13 195 3.25 0.5 0.089 0.417 0.080 0.009 0.08 0.00
14 210 3.50 0.5 0.089 0.412 0.080 0.009 0.08 0.00
15 225 3.75 0.5 0.089 0.407 0.080 0.009 0.08 0.00
16 240 4.00 0.6 0.107 0.401 0.097 0.011 0.10 0.00
17 255 4.25 0.6 0.107 0.396 0.097 0.011 0.10 0.00
18 270 4.50 0.7 0.125 0.391 0.113 0.013 0.12 0.00
19 285 4.75 0.7 0.125 0.386 0.113 0.013 0.12 0.00
20 300 5.00 0.8 0.143 0.381 0.129 0.014 0.14 0.00
21 315 5.25 0.6 0.107 0.376 0.097 0.011 0.10 0.00
22 330 5.50 0.7 0.125 0.371 0.113 0.013 0.12 0.00
23 345 5.75 0.8 0.143 0.367 0.129 0.014 0.14 0.00
24 360 6.00 0.8 0.143 0.362 0.129 0.014 0.14 0.00
25 375 6.25 0.9 0.161 0.357 0.145 0.016 0.15 0.00
26 390 6.50 0.9 0.161 0.352 0.145 0.016 0.15 0.00
27 405 6.75 1.0 0.179 0.347 0.161 0.018 0.17 0.00
28 420 7.00 1.0 0.179 0.343 0.161 0.018 0.17 0.00
29 435 7.25 1.0 0.179 0.338 0.161 0.018 0.17 0.00
30 450 7.50 1.1 0.197 0.334 0.177 0.020 0.19 0.00
31 465 7.75 1.2 0.215 0.329 0.193 0.021 0.20 0.00
32 480 8.00 1.3 0.232 0.324 0.209 0.023 0.22 0.00
33 495 8.25 1.5 0.268 0.320 0.241 0.027 0.25 0.00
34 510 8.50 1.5 0.268 0.315 0.241 0.027 0.25 0.00
35 525 8.75 1.6 0.286 0.311 0.257 0.029 0.27 0.00
36 540 9.00 1.7 0.304 0.307 0.274 0.030 0.29 13.81
37 555 9.25 1.9 0.340 0.302 0.306 0.037 0.35 73.64
38 570 9.50 2.0 0.358 0.298 0.322 0.060 0.57 263.09
39 585 9.75 2.1 0.375 0.294 0.338 0.082 0.78 452.20
40 600 10.00 2.2 0.393 0.290 0.354 0.104 0.99 640.96
41 615 10.25 1.5 0.268 0.285 0.241 0.027 0.25 0.00
42 630 10.50 1.5 0.268 0.281 0.241 0.027 0.25 0.00
43 645 10.75 2.0 0.358 0.277 0.322 0.080 0.76 441.57
44 660 11.00 2.0 0.358 0.273 0.322 0.085 0.80 476.21
45 675 11.25 1.9 0.340 0.269 0.306 0.071 0.67 357.77
46 690 11.50 1.9 0.340 0.265 0.306 0.075 0.71 391.68
47 705 11.75 1.7 0.304 0.261 0.274 0.043 0.41 119.79
48 720 12.00 1.8 0.322 0.257 0.290 0.065 0.61 305.68
49 735 12.25 2.5 0.447 0.253 0.402 0.194 1.84 1407.47
50 750 12.50 2.6 0.465 0.250 0.418 0.215 2.04 1592.60
51 765 12.75 2.8 0.501 0.246 0.451 0.255 2.42 1930.06
52 780 13.00 2.9 0.519 0.242 0.467 0.276 2.62 2114.43
53 795 13.25 3.4 0.608 0.239 0.547 0.369 3.51 2909.26
54 810 13.50 3.4 0.608 0.235 0.547 0.373 3.54 2940.13
55 825 13.75 2.3 0.411 0.231 0.370 0.180 1.71 1290.76
56 840 14.00 2.3 0.411 0.228 0.370 0.183 1.74 1320.84
57 855 14.25 2.7 0.483 0.224 0.434 0.258 2.45 1961.36
58 870 14.50 2.6 0.465 0.221 0.418 0.244 2.32 1837.90
59 885 14.75 2.6 0.465 0.218 0.418 0.247 2.35 1866.75
60 900 15.00 2.5 0.447 0.214 0.402 0.233 2.21 1742.46
61 915 15.25 2.4 0.429 0.211 0.386 0.218 2.07 1617.74
62 930 15.50 2.3 0.411 0.208 0.370 0.204 1.93 1492.59
63 945 15.75 1.9 0.340 0.205 0.306 0.135 1.28 908.87
64 960 16.00 1.9 0.340 0.201 0.306 0.138 1.31 935.56
65 975 16.25 0.4 0.072 0.198 0.064 0.007 0.07 0.00
66 990 16.50 0.4 0.072 0.195 0.064 0.007 0.07 0.00
67 1005 16.75 0.3 0.054 0.192 0.048 0.005 0.05 0.00
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 7 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
68 1020 17.00 0.3 0.054 0.189 0.048 0.005 0.05 0.00
69 1035 17.25 0.5 0.089 0.187 0.080 0.009 0.08 0.00
70 1050 17.50 0.5 0.089 0.184 0.080 0.009 0.08 0.00
71 1065 17.75 0.5 0.089 0.181 0.080 0.009 0.08 0.00
72 1080 18.00 0.4 0.072 0.178 0.064 0.007 0.07 0.00
73 1095 18.25 0.4 0.072 0.176 0.064 0.007 0.07 0.00
74 1110 18.50 0.4 0.072 0.173 0.064 0.007 0.07 0.00
75 1125 18.75 0.3 0.054 0.171 0.048 0.005 0.05 0.00
76 1140 19.00 0.2 0.036 0.168 0.032 0.004 0.03 0.00
77 1155 19.25 0.3 0.054 0.166 0.048 0.005 0.05 0.00
78 1170 19.50 0.4 0.072 0.164 0.064 0.007 0.07 0.00
79 1185 19.75 0.3 0.054 0.161 0.048 0.005 0.05 0.00
80 1200 20.00 0.2 0.036 0.159 0.032 0.004 0.03 0.00
81 1215 20.25 0.3 0.054 0.157 0.048 0.005 0.05 0.00
82 1230 20.50 0.3 0.054 0.155 0.048 0.005 0.05 0.00
83 1245 20.75 0.3 0.054 0.153 0.048 0.005 0.05 0.00
84 1260 21.00 0.2 0.036 0.151 0.032 0.004 0.03 0.00
85 1275 21.25 0.3 0.054 0.149 0.048 0.005 0.05 0.00
86 1290 21.50 0.2 0.036 0.148 0.032 0.004 0.03 0.00
87 1305 21.75 0.3 0.054 0.146 0.048 0.005 0.05 0.00
88 1320 22.00 0.2 0.036 0.145 0.032 0.004 0.03 0.00
89 1335 22.25 0.3 0.054 0.143 0.048 0.005 0.05 0.00
90 1350 22.50 0.2 0.036 0.142 0.032 0.004 0.03 0.00
91 1365 22.75 0.2 0.036 0.141 0.032 0.004 0.03 0.00
92 1380 23.00 0.2 0.036 0.139 0.032 0.004 0.03 0.00
93 1395 23.25 0.2 0.036 0.138 0.032 0.004 0.03 0.00
94 1410 23.50 0.2 0.036 0.138 0.032 0.004 0.03 0.00
95 1425 23.75 0.2 0.036 0.137 0.032 0.004 0.03 0.00
96 1440 24.00 0.2 0.036 0.137 0.032 0.004 0.03 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.28
FLOOD VOLUME (acft) 1.01
FLOOD VOLUME (cuft) 44164.39
REQUIRED STORAGE (acft) 0.72
REQUIRED STORAGE (cuft) 31405.17
PEAK FLOW (cfs) 3.54
Plate E-2.2

Page 8 of 14 ends

Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

INCR TOTAL INCR TOTAL INCR TOTAL
(ft) (ft) (sf) (sf) (cuft) (cuft) (acre-ft)
463.5 0 0 17610 0 0 0.00
464.5 1 1 1790 19400 18505 18505 0.42
465.5 1 2 1840 21240 20320 38825 0.89
466.5 1 3 1900 23140 22190 61015 1.40
467 0.5 3.5 970 24110 11813 72828 1.67

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.27 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.27 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.55 165 165 82 83 463.50 83 0.00
2 10 0.55 165 248 82 166 463.51 166 0.00
3 15 0.07 20 185 82 104 463.51 104 0.00
4 20 1.03 310 413 82 331 463.52 331 0.01
5 25 1.03 310 641 82 559 463.53 559 0.01
6 30 1.76 527 1,086 82 1,004 463.55 1,004 0.02
7 35 1.03 310 1,313 82 1,231 463.57 1,231 0.03
8 40 1.76 527 1,758 82 1,676 463.59 1,676 0.04
9 45 1.76 527 2,203 82 2,121 463.61 2,121 0.05
10 50 1.03 310 2,431 82 2,349 463.63 2,349 0.05
11 55 1.27 382 2,731 82 2,649 463.64 2,649 0.06
12 60 1.76 527 3,176 82 3,094 463.67 3,094 0.07
13 65 2.72 817 3,911 82 3,829 463.71 3,829 0.09
14 70 2.72 817 4,645 82 4,563 463.75 4,563 0.10
15 75 2.72 817 5,380 82 5,298 463.79 5,298 0.12
16 80 2.24 672 5,970 82 5,888 463.82 5,888 0.14
17 85 3.69 1,106 6,994 82 6,912 463.87 6,912 0.16
18 90 3.93 1,179 8,091 82 8,009 463.93 8,009 0.18
19 95 3.20 961 8,970 82 8,888 463.98 8,888 0.20
20 100 3.93 1,179 10,067 82 9,985 464.04 9,985 0.23
21 105 5.38 1,613 11,598 82 11,517 464.12 11,517 0.26
22 110 4.89 1,468 12,985 82 12,903 464.20 12,903 0.30
23 115 4.41 1,324 14,227 82 14,145 464.26 14,145 0.32
24 120 4.65 1,396 15,541 82 15,459 464.34 15,459 0.35
25 125 4.89 1,468 16,927 82 16,845 464.41 16,845 0.39
26 130 7.55 2,265 19,110 82 19,028 464.53 19,028 0.44
27 135 9.48 2,845 21,873 82 21,791 464.66 21,791 0.50
28 140 5.86 1,758 23,549 82 23,467 464.74 23,467 0.54
29 145 13.83 4,148 27,616 82 27,534 464.94 27,534 0.63
30 150 15.03 4,510 32,044 82 31,962 465.16 31,962 0.73
31 155 17.21 5,162 37,124 82 37,042 465.41 37,042 0.85
32 160 11.65 3,496 40,539 82 40,457 465.57 40,457 0.93
33 165 2.24 672 41,129 82 41,047 465.60 41,047 0.94
34 170 1.76 527 41,573 82 41,492 465.62 41,492 0.95
35 175 1.76 527 42,018 82 41,936 465.64 41,936 0.96
36 180 0.14 43 41,980 82 41,898 465.64 41,898 0.96

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.16 47 47 82 - 463.50 - 0.00
2 10 0.19 57 57 82 - 463.50 - 0.00
3 15 0.19 57 57 82 - 463.50 - 0.00
4 20 0.19 57 57 82 - 463.50 - 0.00
5 25 0.19 57 57 82 - 463.50 - 0.00
6 30 0.22 66 66 82 - 463.50 - 0.00
7 35 0.22 66 66 82 - 463.50 - 0.00
8 40 0.22 66 66 82 - 463.50 - 0.00
9 45 0.22 66 66 82 - 463.50 - 0.00
10 50 0.22 66 66 82 - 463.50 - 0.00
11 55 0.22 66 66 82 - 463.50 - 0.00
12 60 0.25 76 76 82 - 463.50 - 0.00
13 65 0.25 76 76 82 - 463.50 - 0.00
14 70 0.25 76 76 82 - 463.50 - 0.00
15 75 0.25 76 76 82 - 463.50 - 0.00
16 80 0.25 76 76 82 - 463.50 - 0.00
17 85 0.25 76 76 82 - 463.50 - 0.00
18 90 0.25 76 76 82 - 463.50 - 0.00
19 95 0.25 76 76 82 - 463.50 - 0.00
20 100 0.25 76 76 82 - 463.50 - 0.00
21 105 0.25 76 76 82 - 463.50 - 0.00
22 110 0.25 76 76 82 - 463.50 - 0.00
23 115 0.25 76 76 82 - 463.50 - 0.00
24 120 0.26 78 78 82 - 463.50 - 0.00
25 125 0.25 76 76 82 - 463.50 - 0.00
26 130 0.26 78 78 82 - 463.50 - 0.00
27 135 0.26 78 78 82 - 463.50 - 0.00
28 140 0.26 78 78 82 - 463.50 - 0.00
29 145 0.26 78 78 82 - 463.50 - 0.00
30 150 0.26 78 78 82 - 463.50 - 0.00
31 155 0.26 78 78 82 - 463.50 - 0.00
32 160 0.26 78 78 82 - 463.50 - 0.00
33 165 0.58 173 173 82 91 463.50 91 0.00
34 170 0.58 173 264 82 182 463.51 182 0.00
35 175 0.58 173 355 82 273 463.51 273 0.01
36 180 0.58 173 446 82 364 463.52 364 0.01
37 185 0.58 173 537 82 455 463.52 455 0.01
38 190 0.89 268 723 82 641 463.53 641 0.01
39 195 0.89 268 909 82 827 463.54 827 0.02
40 200 0.89 268 1,095 82 1,013 463.55 1,013 0.02
41 205 1.21 363 1,376 82 1,294 463.57 1,294 0.03
42 210 1.53 458 1,752 82 1,670 463.59 1,670 0.04
43 215 1.84 553 2,223 82 2,141 463.62 2,141 0.05
44 220 1.84 553 2,694 82 2,612 463.64 2,612 0.06
45 225 2.16 648 3,259 82 3,177 463.67 3,177 0.07
46 230 2.16 648 3,825 82 3,743 463.70 3,743 0.09
47 235 2.48 743 4,486 82 4,404 463.74 4,404 0.10
48 240 2.48 743 5,147 82 5,065 463.77 5,065 0.12
49 245 2.79 838 5,903 82 5,821 463.81 5,821 0.13
50 250 3.11 933 6,754 82 6,672 463.86 6,672 0.15
51 255 3.43 1,028 7,699 82 7,617 463.91 7,617 0.17
52 260 3.74 1,123 8,740 82 8,658 463.97 8,658 0.20
53 265 4.06 1,218 9,876 82 9,794 464.03 9,794 0.22
54 270 4.06 1,218 11,012 82 10,930 464.09 10,930 0.25
55 275 4.38 1,313 12,242 82 12,160 464.16 12,160 0.28

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 11 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 4.69 1,408 13,568 82 13,486 464.23 13,486 0.31
57 285 5.01 1,503 14,989 82 14,907 464.31 14,907 0.34
58 290 5.01 1,503 16,409 82 16,327 464.38 16,327 0.37
59 295 5.33 1,598 17,925 82 17,843 464.46 17,843 0.41
60 300 5.64 1,693 19,536 82 19,454 464.55 19,454 0.45
61 305 7.22 2,167 21,621 82 21,539 464.65 21,539 0.49
62 310 8.81 2,642 24,181 82 24,100 464.78 24,100 0.55
63 315 9.76 2,927 27,027 82 26,945 464.92 26,945 0.62
64 320 10.71 3,212 30,157 82 30,075 465.07 30,075 0.69
65 325 12.29 3,687 33,762 82 33,680 465.25 33,680 0.77
66 330 15.14 4,542 38,222 82 38,140 465.47 38,140 0.88
67 335 3.43 1,028 39,168 82 39,086 465.51 39,086 0.90
68 340 0.26 78 39,164 82 39,082 465.51 39,082 0.90
69 345 0.19 57 39,139 82 39,057 465.51 39,057 0.90
70 350 0.16 47 39,104 82 39,022 465.51 39,022 0.90
71 355 0.09 28 39,051 82 38,969 465.51 38,969 0.89
72 360 0.06 19 38,988 82 38,906 465.50 38,906 0.89
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.03 31 31 246 - 463.50 - 0.00
2 30 0.05 46 46 246 - 463.50 - 0.00
3 45 0.05 46 46 246 - 463.50 - 0.00
4 60 0.07 61 61 246 - 463.50 - 0.00
5 75 0.05 46 46 246 - 463.50 - 0.00
6 90 0.05 46 46 246 - 463.50 - 0.00
7 105 0.05 46 46 246 - 463.50 - 0.00
8 120 0.07 61 61 246 - 463.50 - 0.00
9 135 0.07 61 61 246 - 463.50 - 0.00
10 150 0.07 61 61 246 - 463.50 - 0.00
11 165 0.08 76 76 246 - 463.50 - 0.00
12 180 0.08 76 76 246 - 463.50 - 0.00
13 195 0.08 76 76 246 - 463.50 - 0.00
14 210 0.08 76 76 246 - 463.50 - 0.00
15 225 0.08 76 76 246 - 463.50 - 0.00
16 240 0.10 92 92 246 - 463.50 - 0.00
17 255 0.10 92 92 246 - 463.50 - 0.00
18 270 0.12 107 107 246 - 463.50 - 0.00
19 285 0.12 107 107 246 - 463.50 - 0.00
20 300 0.14 122 122 246 - 463.50 - 0.00
21 315 0.10 92 92 246 - 463.50 - 0.00
22 330 0.12 107 107 246 - 463.50 - 0.00
23 345 0.14 122 122 246 - 463.50 - 0.00
24 360 0.14 122 122 246 - 463.50 - 0.00
25 375 0.15 137 137 246 - 463.50 - 0.00
26 390 0.15 137 137 246 - 463.50 - 0.00
27 405 0.17 153 153 246 - 463.50 - 0.00
28 420 0.17 153 153 246 - 463.50 - 0.00
29 435 0.17 153 153 246 - 463.50 - 0.00
30 450 0.19 168 168 246 - 463.50 - 0.00
31 465 0.20 183 183 246 - 463.50 - 0.00
32 480 0.22 199 199 246 - 463.50 - 0.00
33 495 0.25 229 229 246 - 463.50 - 0.00
34 510 0.25 229 229 246 - 463.50 - 0.00
35 525 0.27 244 244 246 - 463.50 - 0.00
36 540 0.29 260 260 246 14 463.50 14 0.00
37 555 0.35 319 333 246 87 463.50 87 0.00
38 570 0.57 509 596 246 351 463.52 351 0.01
39 585 0.78 698 1,049 246 803 463.54 803 0.02
40 600 0.99 887 1,689 246 1,444 463.58 1,444 0.03
41 615 0.25 229 1,673 246 1,427 463.58 1,427 0.03
42 630 0.25 229 1,656 246 1,410 463.58 1,410 0.03
43 645 0.76 687 2,098 246 1,852 463.60 1,852 0.04
44 660 0.80 722 2,574 246 2,328 463.63 2,328 0.05
45 675 0.67 604 2,932 246 2,686 463.65 2,686 0.06
46 690 0.71 637 3,323 246 3,077 463.67 3,077 0.07
47 705 0.41 366 3,443 246 3,197 463.67 3,197 0.07
48 720 0.61 551 3,749 246 3,503 463.69 3,503 0.08
49 735 1.84 1,653 5,156 246 4,910 463.77 4,910 0.11
50 750 2.04 1,838 6,749 246 6,503 463.85 6,503 0.15
51 765 2.42 2,176 8,679 246 8,433 463.96 8,433 0.19
52 780 2.62 2,360 10,793 246 10,547 464.07 10,547 0.24
53 795 3.51 3,155 13,703 246 13,457 464.23 13,457 0.31
54 810 3.54 3,186 16,643 246 16,397 464.39 16,397 0.38
55 825 1.71 1,537 17,933 246 17,688 464.46 17,688 0.41
56 840 1.74 1,567 19,254 246 19,008 464.52 19,008 0.44
57 855 2.45 2,207 21,216 246 20,970 464.62 20,970 0.48
58 870 2.32 2,084 23,054 246 22,808 464.71 22,808 0.52

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 2.35 2,113 24,920 246 24,674 464.80 24,674 0.57
60 900 2.21 1,988 26,663 246 26,417 464.89 26,417 0.61
61 915 2.07 1,864 28,280 246 28,035 464.97 28,035 0.64
62 930 1.93 1,738 29,773 246 29,527 465.04 29,527 0.68
63 945 1.28 1,155 30,682 246 30,436 465.09 30,436 0.70
64 960 1.31 1,181 31,618 246 31,372 465.13 31,372 0.72
65 975 0.07 61 31,433 246 31,187 465.12 31,187 0.72
66 990 0.07 61 31,248 246 31,002 465.12 31,002 0.71
67 1005 0.05 46 31,048 246 30,802 465.11 30,802 0.71
68 1020 0.05 46 30,848 246 30,602 465.10 30,602 0.70
69 1035 0.08 76 30,679 246 30,433 465.09 30,433 0.70
70 1050 0.08 76 30,509 246 30,263 465.08 30,263 0.69
71 1065 0.08 76 30,340 246 30,094 465.07 30,094 0.69
72 1080 0.07 61 30,155 246 29,909 465.06 29,909 0.69
73 1095 0.07 61 29,970 246 29,724 465.05 29,724 0.68
74 1110 0.07 61 29,786 246 29,540 465.04 29,540 0.68
75 1125 0.05 46 29,586 246 29,340 465.03 29,340 0.67
76 1140 0.03 29,370 31 246 29,125 465.02 29,125 0.67
77 1155 0.05 46 29,170 246 28,925 465.01 28,925 0.66
78 1170 0.07 61 28,986 246 28,740 465.00 28,740 0.66
79 1185 0.05 46 28,786 246 28,540 464.99 28,540 0.66
80 1200 0.03 31 28,570 246 28,325 464.98 28,325 0.65
81 1215 0.05 46 28,370 246 28,125 464.97 28,125 0.65
82 1230 0.05 46 28,170 246 27,925 464.96 27,925 0.64
83 1245 0.05 46 27,970 246 27,725 464.95 27,725 0.64
84 1260 0.03 31 27,755 246 27,509 464.94 27,509 0.63
85 1275 0.05 46 27,555 246 27,309 464.93 27,309 0.63
86 1290 0.03 31 27,340 246 27,094 464.92 27,094 0.62
87 1305 0.05 46 27,140 246 26,894 464.91 26,894 0.62
88 1320 0.03 31 26,925 246 26,679 464.90 26,679 0.61
89 1335 0.05 46 26,725 246 26,479 464.89 26,479 0.61
90 1350 0.03 31 26,509 246 26,264 464.88 26,264 0.60
91 1365 0.03 31 26,294 246 26,048 464.87 26,048 0.60
92 1380 0.03 31 26,079 246 25,833 464.86 25,833 0.59
93 1395 0.03 31 25,864 246 25,618 464.85 25,618 0.59
94 1410 0.03 31 25,648 246 25,402 464.84 25,402 0.58
95 1425 0.03 31 25,433 246 25,187 464.83 25,187 0.58
96 1440 0.03 31 25,218 246 24,972 464.82 24,972 0.57
Basin Depth Analysis

Page 14 of 14 ends

Item 2.

IV STREET FLOWRATE CAPACITY
On-site street curb and gutter systems will be designed to convey runoff to the on-site retention basin systems via surface flow. The project site will be designed to ensure that surface runoff generated during the 100 year storm event can be contained within the street right of way per City of Coachella drainage standards
In terms of on-site drainage, the site is divided into 4 separate quadrants, each draining to a separate surface retention basin. Within each quadrant, the maximum tributary area contributing runoff to any single street is 5 acres. Rational method calculations based on the 100 year design storm for 5 acres drainage area are provided in this section to quantify the maximum flowrate (Q) that must be conveyed by any on-site interior street. Manning’s equation for open channel flow has then been used to show that the 100 year maximum flowrate (Q) can be contained within the street section right of way.

Q(100) MAX. = 10.92 CFS
MAX. STREET CAPACITY = 13.86 CFS
722
Item 2.

Riverside County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software,(c) 1989 - 2005 Version

7.1 Rational Hydrology Study Date: 09/25/24
File:CALHOUN100STREET.out
------------------------------------------------------------------ ------
CALHOUN 100 YEAR - 5 ACRE STUDY

------------------------------------------------------------------ ------
********* Hydrology Study Control Information ********** English (in-lb) Units used in input data file
------------------------------------------------------------------ ------
Program License Serial Number 6253
------------------------------------------------------------------ ------
Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation District 1978 hydrology manual
Storm event (year) = 100.00 Antecedent Moisture Condition = 2 2 year, 1 hour precipitation = 0.350(In.)
100 year, 1 hour precipitation = 1.330(In.)
Storm event year = 100.0
Calculated rainfall intensity data:
1 hour intensity = 1.330(In/Hr)
Slope of intensity duration curve = 0.5900
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++
Process from Point/Station 100.000 to Point/Station
200.000
**** INITIAL AREA EVALUATION ****
__________________________________________________________________ ____
Initial area flow distance = 1000.000(Ft.)
Top (of initial area) elevation = 450.000(Ft.)
Bottom (of initial area) elevation = 446.500(Ft.)
Difference in elevation = 3.500(Ft.)
Slope = 0.00350 s(percent)= 0.35
TC = k(0.370)*[(length^3)/(elevation change)]^0.2
Initial area time of concentration = 18.171 min.

Rainfall intensity = 2.691(In/Hr) for a 100.0 year storm 723
Item 2.

CONDOMINIUM subarea type
Runoff Coefficient = 0.812
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 1.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 56.00
Pervious area fraction = 0.350; Impervious fraction = 0.650 Initial subarea runoff = 10.922(CFS)
Total initial stream area = 5.000(Ac.)
Pervious area fraction = 0.350
End of computations, total study area = 5.00 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.

Area averaged pervious area fraction(Ap) = 0.350
Area averaged RI index number = 56.0
724
Item 2.
725
Item 2.

V APPENDIX
726
Item 2.
727
Item 2.

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~ qus{vts{{x !# qtszzvws{|x ! q|srwvysyx ~!~ qwsr}vzrsx #! qysruvzuszx ! qsuuvz|stx !# qzrsuvzstx zD-/.E7EI6IE+B[-/,/B.TqDXx/*IEL6I/*EBIGE*I6QN/6-/Q6*/R+B[-/,/B.T6B6NT*E*+[76-IE6NR,-6IE+B*/-E/*qDH2xs `,LQ/-*EB76-/BIG/*E*6-/DX/*IEL6I/*6IN+]/-6BR,77/-Q+,BR*+[IG/r.+B[ER/B./EBI/-S6NsVG/7-+Q6QENEITIG6I7-/.E7EI6IE+B[-/,/B.T/*IEL6I/*q[+- 6PES/BR,-6IE+B6BR6S/-6P/-/.,--/B./EBI/-S6Nx]ENNQ/P-/6I/-IG6BIG/,77/-Q+,BRq+-N/**IG6BIG/N+]/-Q+,BRxE*ts1*IEL6I/*6I,77/-Q+,BR*6-/B+I .G/.W/R6P6EB*I7-+Q6QN/L6EL,L7-/.E7EI6IE+BqD5Dx/*IEL6I/*6BRL6TQ/GEPG/-IG6B.,--/BINTS6NERD5DS6N,/*s DN/6*/-/[/-I+`abbbIN6*z}R+.,L/BI[+-L+-/EB[+-L6IE+Bs \6.WI+V+7 :>%i 728 Item 2.

Initial Study/Mitigated Negative Declaration
City of Coachella Calhoun Street Housing Development/TTM 39051 November 2025 Initial Study/Mitigated Negative Declaration E
Appendix E
Calhoun Street Housing Development Preliminary Water Quality Management Plan 729
Item 2.
730
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision

OWNER'S CERTIFICATION
This project-specific Preliminary Water Quality Management Plan (WQMP) has been prepared for:

Rod Vandenburg by The Altum Group for the project known as Calhoun Street Subdivision at 49-251 Calhoun Street, Coachella, CA 92236.
.

This Preliminary WQMP is intended to comply with the requirements of The City of Coachella for ASSESSOR’S PARCEL NUMBERS: 612-260-010 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 the WQMP and will ensure that the WQMP is amended as appropriate to reflect up-to-date conditions on the site. This Preliminary 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 the WQMP. At least one copy of the Final WQMP will be maintained at the project site or project office in perpetuity.

The undersigned is authorized to certify and to approve implementation of the Final WQMP. The undersigned is aware that implementation of the WQMP is enforceable under The City of Coachella Water Quality Ordinance (City of Coachella Ordinance 1057, Section 5 Chapter 13.6).

If the undersigned transfers its interest in the subject property/project, the undersigned shall notify the successor in interest of its responsibility to implement the WQMP. "I, the undersigned, certify under penalty of law that I am the owner of the property that is the subject of the WQMP, and that the provisions of the 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
Rod Vandenburg
Owner's Title/Position

Date
43-584 Via Magellan Drive
Palm Desert, CA 92201
(760) 799-8227

THIS FORM SHALL BE NOTARIZED BEFORE ACCEPTANCE OF THE

FINAL PROJECT SPECIFIC WQMP
Notary Signature

Printed Name

Title/Position

Date
731
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-i
Contents

SECTION PAGE
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 ............................................ 24 V.4 REGIONALLY-BASED BMPS ............................................................................................. 24 VI. Operation and Maintenance Responsibility for BMPs ......................................................... 25 VII. Funding ....................................................................................................................................... 28 TABLES
TABLE 1. POLLUTANT OF CONCERN SUMMARY 7
TABLE 2. BMP SELECTION MATRIX BASED UPON POLLUTANT OF CONCERN REMOVAL EFFICIENCY 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
732
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-1
I. Project Description
Project Owner: Pacific Coast Properties
43-584 Via Magellan Drive
Palm Desert, CA 92201
Telephone: (760) 799-8227
Ron Vandenburg - Owner
WQMP Preparer:

James R. Bazua, PE
44-600 Village Court Suite 100
Palm Desert, CA 92260
Telephone: (760) 346 – 4750
[email protected]
_________________________________________
James Bazua Date
RCE 58394 Exp. 12/31/26
Project Site Address: 49-251 Calhoun Street
Coachella, CA 92236
Planning Area/
Community Name/
Development Name: General Neighborhood
APN Number(s): 612-260-010
Latitude & Longitude: 33.6915, -116.2099
Receiving Water: Coachella Valley Stormwater Channel
Project Site Size: 39.98 acres
Standard Industrial Classification (SIC) Code: 6552 Land Subdividers and Developers Formation of Home Owners' Association (HOA)
or Property Owners Association (POA): Y N
733
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 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
South Coast Air Quality Management District – PM10
Approval to comply with Rule 403
Y N
Other: City of Coachella Grading Permit and Building Permit Y N 734
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-3
Project Description
The proposed Calhoun Street Subdivision (Project) is located at 49-251 Calhoun Street, at Calhoun Street & Avenue 49, Coachella, CA 92236. The Accessor’s Parcel Number is 612-260-010. The total Project area is 39.98 acres and is vacant under the existing condition. Proposed improvements will consist of the construction of a 257-lot residential subdivision that will disturb 100% of the existing vacant land. Included in project construction activities are clearing and grubbing, rough and precise grading, construction of roadways, buildings for each lot, landscaping areas, and a 1.96 acre park on the east side of the project along Calhoun Street.

Under post development conditions, storm runoff generated on-site will surface flow via local surface streets toward on-site retention basin collection systems. The on-site retention basin systems are designed to store 100% of runoff generated during the worst case 100-year design storm event.

Flows exceeding the storage capacity of the on-site retention basin systems in an emergency overflow condition will exit the project and flow onto Calhoun Street, then follow a northerly direction, toward Avenue 48, where it will continue east until entering the existing MS4 storm drain inlet facility on Van Buren Street, then continues underground toward the east (approximately 1 mile) until it empties into the Coachella Valley Storm Channel.

Appendix A of the project-specific Final WQMP will include a complete copy of the Conditions of Approval. Appendix B of this project-specific Preliminary 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. 735
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-4
 Pre- and post-project topography.

Appendix I is a one-page form that summarizes pertinent information relative to the project-specific WQMP.
736
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-5
II. Site Characterization
Land Use Designation or Zoning: General Neighborhood
Current Property Use: Vacant Land
Proposed Property Use: General Neighborhood – Residential Subdivision Availability of Soils Report: Y N Note: A soils report is required if infiltration BMPs are utilized. Report will be included with Final WQMP Appendix E.

Phase 1 Site Assessment: Y N Note: If prepared, attached remediation summary and use restrictions in Appendix H.
737
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 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
Coachella Valley
Stormwater Channel
DDT, Dieldrin,
Pathogens, Toxaphene,
Toxicity, Total
Ammonia
FRSH, REC 1, REC 2,

WARM, WILD, RARE
Designated as RARE
(18.0 miles)
738
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 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 YES NO
Nutrients YES NO
Toxic Organic Compounds YES YES
Sediment/Turbidity YES NO
Trash & Debris YES NO
Oil & Grease YES NO
Toxaphene NO YES
1) Pathogens are disease causing virus or bacteria. Pathogens are an impairment in the Coachella Valley Storm Water Channel from Dillon Road to the Salton Sea. 2) Toxaphene is an insecticide which was banned from use in the United States in 1990.

Therefore, it is not a potential for the project but is currently a receiving water impairment. 3) Petroleum hydrocarbons are one of the most common organic compounds associated with street and parking lots and is a potential pollutant for the site. See Section V.2 for a description of appropriate Source Control BMPs.
4) Oil and Grease associated with landscaping and onsite operations are potential pollutants for the development. See Section V.2 for a description of appropriate Source Control BMP’s. 5) PCBs, Dieldrin, and DDT are banned substances in the US. 739
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 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 SiteDesign BMP concepts and LID/Site Design BMPs that assure non-exceedance of predevelopment 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)
740
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 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. 741
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 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
Landscape Swale2, 3
Landscape Strip2, 3
Biofiltration
(with underdrain)2, 3
Extended Detention
Basin2
Sand Filter Basin2
Infiltration Basin2
Infiltration Trench2
Permeable
Pavement2
Bioretention
(w/o underdrain)2, 3
Other BMPs Including
Proprietary BMPs4, 6
Sediment &
Turbidity M M H M H H H H H
Varies by Product5
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.
742
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 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.
743
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-12
Table 3. Implementation of Site Design BMP Concepts
Included
Brief Reason for BMPs
Indicated as No or N/A
Design
Concept Technique Specific BMP Yes No N/A Site Design BMP Concept 1 Minimize Urban
Runoff,
Minimize
Impervious
Footprint, and
Conserve
Natural Areas
(See WQMP
Section 3.5.1.3)
Conserve natural areas by concentrating or clustering
development on the least environmentally sensitive portions of a site while leaving the remaining land in a natural, undisturbed condition.

Conserve natural areas by incorporating the goals of the MultiSpecies Habitat Conservation Plan or other natural resource plans.

Preserve natural drainage features and natural depressional storage areas on the site.

Maximize canopy interception and water conservation by
preserving existing native trees and shrubs, and planting additional native or drought tolerant trees and large shrubs.

Use natural drainage systems.

Where applicable, incorporate Self-Treating Areas
Where applicable, incorporate Self-Retaining Areas
Increase the building floor to area ratio (i.e., number of stories above or below ground).

Construct streets, sidewalks and parking lot aisles to minimum widths necessary, provided that public safety and a walkable environment for pedestrians are not compromised.

Reduce widths of streets where off-street parking is available.

Minimize the use of impervious surfaces, such as decorative concrete, in the landscape design.

Other comparable and equally effective Site Design BMP
concept(s) as approved by the local land use authority (Note:

Additional narrative required to describe BMP and how it addresses site design concept).
744
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-13
Table 3. Site Design BMP Concepts (continued)
Included
Brief Reason for Each BMP
Indicated as No or N/A Design
Concept Technique Specific BMP Yes No N/A Site Design BMP Concept 2 Minimize
Directly
Connected
Impervious
Area
(See WQMP
Section

3.5.1.4)
Design residential and commercial sites to contain and infiltrate roof runoff, or direct roof runoff to landscaped swales or buffer areas.

Drain impervious sidewalks, walkways, trails, and patios into adjacent landscaping.

Incorporate landscaped buffer areas between sidewalks and streets.

Use natural or landscaped drainage swales in lieu of underground piping or imperviously lined swales.

Where soil conditions are suitable, use perforated pipe or gravel filtration pits for low flow infiltration.

Maximize the permeable area by constructing walkways, trails, patios, overflow parking, alleys, driveways, low-traffic streets, and other lowtraffic areas with open-jointed paving materials or permeable surfaces such as pervious concrete, porous asphalt, unit pavers, and granular materials.

Use one or more of the following:

Rural swale system: street sheet flows to landscaped swale or gravel shoulder, curbs used at street corners, and culverts used under driveways and street crossings.

Urban curb/swale system: street slopes to curb; periodic swale inlets drain to landscaped swale or biofilter.

Dual drainage system: first flush captured in street catch basins and discharged to adjacent vegetated swale or gravel shoulder; high flows connect directly to MS4s.

Other comparable and equally effective Site Design BMP concept(s) as approved by the local land use authority (Note: Additional narrative required to describe BMP and how it addresses site design concept).

Use one or more of the following for design of driveways and private residential parking areas:

Design driveways with shared access, flared (single lane at street), or wheel strips (paving only under the tires).

Uncovered temporary or guest parking on residential lots paved with a permeable surface, or designed to drain into landscaping. 745
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-14
Table 3. Site Design BMP Concepts (continued)
Included Brief Reason for Each BMP
Design Indicated as No or N/A
Concept Technique Specific BMP Yes No N/A Site Design BMP Concept 2 (cont'd) Minimize
Directly
Connected
Impervious
Area
(See WQMP
Section

3.5.1.4)
Other comparable and equally effective Site Design BMP concept(s) as approved by the local land use authority (Note: Additional narrative required to describe BMP and how it addresses site design concept).

Use one or more of the following for design of parking areas:

Where landscaping is proposed in parking areas, incorporate parking area landscaping into the drainage design.

Overflow parking (parking stalls provided in excess of the Permittee's minimum parking requirements) may be constructed with permeable pavement.

Other comparable and equally effective Site Design BMP (or BMPs) as approved by the local land use authority (Note: Additional narrative required describing BMP and how it addresses site design concept). 746
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-15
Project Site Design BMP Concepts:

The site design BMPs will include a Infiltration Basin system BMP designed to capture 100% of the 100 year storm event per City of Coachella standards.

Alternative Project Site Design BMP Concepts:

N/A
747
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-16
Table 4. LID/Site Design BMPs Meeting the LID/Site Design Measurable Goal (1) (2) (3) (4) (5) (6) (7)

DRAINAGE

SUB-AREA
ID OR NO.

LID/SITE DESIGN BMP
TYPE*

POTENTIAL POLLUTANTS

OF CONCERN WITHIN

DRAINAGE SUB-AREA

POTENTIAL

POLLUTANTS
WITHIN SUBAREA CAUSING

RECEIVING
WATER

IMPAIRMENTS

EFFECTIVENESS

OF LID/SITE

DESIGN BMP AT

ADDRESSING

IDENTIFIED

POTENTIAL

POLLUTANTS

BMP MEETS
WHICH
DESIGN
CRITERIA?
TOTAL
AREA
WITHIN

DRAINAGE

SUB-AREA
(See Table 2) (Refer to Table 1) (Refer to Table 1) (U, L, M, H/M, H; see Table 2)
(Identify as
VBMP OR QBMP) (Nearest 0.1 acre)
TOTAL PROJECT AREA TREATED WITH LID/SITE DESIGN BMPs (NEAREST 0.1 ACRE) 39.98 * LID/Site Design BMPs listed in this table are those that completely address the 'Treatment Control BMP requirement' for their drainage sub-area.
748
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-17
Justification of infeasibility for sub-areas not addressed with LID/Site Design BMPs Not applicable; Treatment Control & Site Design BMP’s are addressed by the Infiltration Basin design system.

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 subareas 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. 749
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-18
Table 5: Treatment Control BMP Summary
(1) (2) (3) (4) (5) (6) (7)

DRAINAGE

SUB-AREA
ID OR NO.

TREATMENT

CONTROL BMP
TYPE*

POTENTIAL

POLLUTANTS OF

CONCERN WITHIN

DRAINAGE SUB-AREA

POTENTIAL

POLLUTANTS

WITHIN SUB-AREA

CAUSING

RECEIVING
WATER

IMPAIRMENTS

EFFECTIVENESS OF

TREATMENT

CONTROL BMP AT

ADDRESSING

IDENTIFIED

POTENTIAL

POLLUTANTS

BMP MEETS
WHICH
DESIGN
CRITERIA?
TOTAL
AREA
WITHIN

DRAINAGE

SUB-AREA
(See Table 2) (Refer to Table 1) (Refer to Table 1) (U, L, M, H/M, H; see Table 2)
(Identify as

VBMP OR QBMP)
(Nearest 0.1
acre)
TOTAL PROJECT AREA TREATED WITH TREATMENT CONTROL BMPs (NEAREST 0.1 ACRE) 0.0 750
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 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)

39.98 ac 0.0 ac 100%
751
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 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
Included brief reason 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
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
Provide Community Car Wash Racks Not part of the project design.

Properly Design*:

Fueling Areas
Air/Water Supply Area Drainage No facilities.

Trash Storage Areas
Loading Docks No facilities.

Maintenance Bays No facilities.

Vehicle and Equipment Wash Areas No facilities.

Outdoor Material Storage Areas No facilities.

Outdoor Work Areas or Processing Areas No facilities.

Provide Wash Water Controls for Food
Preparation Areas No facilities.
*Details demonstrating proper design must be included in Appendix F. 752
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-21

5.2.1 Non-Structural Source Control BMPs

5.2.1.1 Education
Yes
The owner, as responsible party for implementing the Final WQMP, will ensure that owner's employees, operators, and managers are properly trained and attend continuing education classes.

5.2.1.2 Activity Restrictions
Yes
Certain activities within the project area may be restricted to enable the owner/operator to meet the City's water quality requirements. For example, maintenance of vehicles (which contributes to storm water contamination by oil and grease) is not authorized in this area.

5.2.1.3 Irrigation System and Landscape Maintenance
Yes
Owner shall ensure that the irrigation systems within the project site are operating properly.

Owner shall also ensure that the ground's landscaping is maintained regularly so that the project site is in compliance with all City water quality requirements.

5.2.1.4 Common Area Litter Control
Yes
Owner shall ensure that employees regularly patrol the site in an effort to keep it free of litter so that the project site is in compliance with all City water quality requirements.

5.2.1.5 Street Sweeping
Yes
Owner shall ensure that the streets is regularly swept so that the project site is in compliance with all City water quality requirements. Streets/driveways and parking lots shall be swept at least quarterly, including just prior to start of the rainy season (October 1st). The frequency shall be no less than the frequency of street sweeping by the Co-Permittee on public streets.

5.2.1.6 Drainage Facility Inspection and Maintenance
Yes
Owner shall ensure that drainage facilities within the project area are regularly inspected (at least annually) and maintained properly so that the project site is in compliance with all City water quality requirements. At a minimum, routine maintenance of drainage facilities should take place in the late summer or early fall prior to the start of the rainy season (October 1st).

5.2.2 Structural Source Control BMPs

5.2.2.1 MS4 Stenciling and Signage
No
The existing site does not drain directly to MS4 facilities as the redevelopment area will 753
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-22
include a retention basin infiltration facility (BMP) which will intercept a 100% of the postdevelopment storm flow. Also, no curb inlets are proposed on-site.

5.2.2.2 Landscape and Irrigation System Design
Yes
The project will be designed to include native, drought-tolerant plants. These plants use less water, and help reduce the use of fertilizers and pesticides. The irrigation system will be programmable and utilize drip emitters, limiting excess irrigation runoff. The landscape and irrigation system will be designed in accordance with the City's water quality requirements.

5.2.2.3 Protect Slopes and Channels
Yes
Project plans shall include Source Control BMPs to decrease the potential for erosion of slopes.

The following design principles shall be considered, and incorporated and implemented where determined applicable and feasible by the local land use authority:
• Convey runoff safely from the tops of slopes.
• Plant slopes with native or drought tolerant vegetation.

5.2.2.4 Provide Community Car Wash Racks
No
The project site will not include community car wash racks as part of the project design.

5.2.2.5 Fueling Areas
No
Project development does not include the construction of fueling areas.

5.2.2.6 Air/Water Supply Area Drainage
No
The project site will not include air/water supply areas.

5.2.2.7 Trash Storage Areas
Yes
The project site will include trash storage areas. Trash storage (or trash enclosures) will be located on-site. Also, trash dumpsters will have attached covers and shall be leak proof. The entire trash storage surface area will be concrete.

5.2.2.8 Loading Docks
No
The project site will not include loading docks.

5.2.2.9 Maintenance Bays
No
The project site will not include maintenance bays.

5.2.2.10 Vehicle and Equipment Wash Areas
No
The project site will not include vehicle and equipment wash areas. 754
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-23

5.2.2.11 Outdoor Material Storage Areas
No
The project site will not Outdoor Material Storage Areas

5.2.2.12 Outdoor Work Areas or Processing Areas
No
The project site will not include outdoor work areas or processing areas.

5.2.2.13 Wash Water Areas for Food Preparation Areas
No
The project site will not include outdoor work areas or processing areas.

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 the project-specific WQMP. 755
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-24
V.3 EQUIVALENT TREATMENT CONTROL BMP ALTERNATIVES
The project site will not include any other treatment control alternatives.

V.4 REGIONALLY-BASED BMPS
100% of the runoff generated on-site during 100 year design frequency storm will be retained onsite in an infiltration type retention basin. 756
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-25
VI. Operation and Maintenance Responsibility for
BMPs
Appendix G of the project-specific WQMP will include 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.

Operations and maintenance (O&M) will be performed, as necessary, by Pacific Coast Properties, their agents, and/or their assignees. The BMPs for the project are a infiltration type retention basins designed with a capacity to store the runoff generated during the 100-year storm event.

Maintenance of the site and on-site storm drain and retention basin system consists primarily of the removal of trash and debris, repair and removal/reinstallation of facilities if damaged or saturated by native material (due to wind and water erosion) or sediment and organic material from human activity. Any removed material must be hauled away to an approved disposal facility. See Appendix D for a recommended “Infiltration System Maintenance Plan”.

Routine inspection and required maintenance of all BMPs and the site should begin immediately upon completion of construction and continue throughout the life of the project. Records of all inspection and repair/modifications shall be kept by the owner. The following persons shall be responsible for all O&M and inspections, until such time as another staff member is designated:

Rod Vandenburg
Pacific Coast Properties
43-584 Via Magellan Drive
Coachella, CA 92201
Telephone: (760) 403- 6647
757
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-28
(1) (2) (3) (4) (5) (6)

ALL BMPS REQUIRING

MAINTENANCE

DESCRIPTION OF O&M

ACTIVITIES

START DATE O&M

FREQUENCY
PARTY

RESPONSIBLE

FOR O&M

SELF INSPECTION AND

RECORD KEEPING

REQUIREMENTS

EDUCATION FOR

PROPERTY OWNERS

OPERATORS, OR

EMPLOYEES

MATERIALS WILL BE

AVAILABLE TO EMPLOYEES,

MAINTENANCE CREWS AND
CONTRACTORS. PROVIDE

EDUCATIONAL MATERIALS

ON AN ANNUAL BASIS AND

UPON HIRING OF
EMPLOYEES.

AT PROJECT

COMPLETION

ANNUALLY PACIFIC COAST PROPERTIES

SEE ATTCHED EXAMPLE OF
TRAINING / EDUCATION LOG.

RECORD TRAINING OF

EMPLOYEES

ACTIVITY RESTRICTIONS

PROVIDE ACCESS TO WQMP

FOR ALL EMPLOYEES AND

CONTRACTORS THAT

PERFORM MAINTENANCE
WORK.

AT PROJECT

COMPLETION

ANNUALLY PACIFIC COAST PROPERTIES SEE ATTACHED EXAMPLE OF BMP OPERATION AND MAINTENANCE LOG

IRRIGATION SYSTEM

AND LANDSCAPE

MANAGEMENT

INSPECT ALL COMMON

LANDSCAPE AREAS AND

REPLACE DEAD
VEGETATION. INSPECT,

ADJUST AND REPAIR
IRRIGATION SYSTEM.

UPON COMPLETION

OF LANDSCAPED

AREAS WEEKLY DURING REGULAR

MAINTENANCE

PACIFIC COAST

PROPERTIES

SEE ATTACHED EXAMPLE OF

BMP OPERATION AND

MAINTENANCE LOG

COMMON AREA LITTER

CONTROL

INSPECT AND REMOVE ALL

LITTER AND DEBRIS

LOCATED IN ALL COMMON

AREAS, INCLUDING STREETS,

PARKWAYS AND SIDEWALKS

AT PROJECT

COMPLETION AS NEEDED PACIFIC COAST PROPERTIES SEE ATTACHED EXAMPLE OF BMP OPERATION AND MAINTENANCE LOG

STREET SWEEPING

INSPECT FOR SEDIMENT

DURING ROUTINE

MAINTENANCE ADJUST

FREQUENCY OF SWEEPING

OPERATIONS

PROJECT

COMPLETION

BI-MONTHLY

AND AS NEEDED

PACIFIC COAST

PROPERTIES

SEE ATTACHED EXAMPLE OF

BMP OPERATION AND

MAINTENANCE LOG
758
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-29

DRAINAGE FACILITY

PROTECTION

INSPECT ALL CATCH BASINS

AND STORM DRAIN PIPES,

REMOVE LITTER DEBRIS AND

ANY LIQUIDS
UPON

INSTALLATION OF

STORM DRAIN

SYSTEM ADDITIONS

QUARTERLY AND

AFTER A

QUALIFYING

RAIN EVENT OF

0.5” /24HRS

PACIFIC COAST

PROPERTIES

SEE ATTACHED EXAMPLE OF

BMP OPERATION AND

MAINTENANCE LOG

LANDSCAPE AND

IRRIGATION SYSTEM
DESIGN

INSPECT AND REPAIR

LANDSCAPE IRRIGATION
TIMERS. INSPECT AND

REPAIR ALL SPRINKLER

HEADS AS NEEDED,

UPON COMPLETION OF LANDSCAPED AREAS WEEKLY PACIFIC COAST PROPERTIES SEE ATTACHED EXAMPLE OF BMP OPERATION AND MAINTENANCE LOG

TRASH STORAGE AREA

INSPECT INTEGRITY OF

STRUCTURAL ELEMENTS

REPLACE CONTAINERS WHEN
NEEDED

AT PROJECT

COMPLETION

MONTHLY AND

AS NEEDED

PACIFIC COAST

PROPERTIES

SEE ATTACHED EXAMPLE OF

BMP OPERATION AND

MAINTENANCE LOG

RETENTION BASIN

INSPECT AND REMOVE

LITTER AND DEBRIS,

MAINTAIN LANDSCAPE,

REMOVE DEAD VEGETATION

AT PROJECT

COMPLETION

QUARTERLY

DURING DRY

SEASON,

MONTHLY

DURING RAINY
SEASON

PACIFIC COAST

PROPERTIES

SEE ATTACHED EXAMPLE OF

BMP OPERATION AND

MAINTENANCE LOG
759
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
January 17, 2025 1-28
VII.Funding
Source funding and long term funding of operations and maintenance of the project BMP will be provided by Pacific Coast Properties (Owner), their agents, and/or assignees. Funding will be addressed in a covenant agreement entered into between City of Coachella and the Owner before approval of the Final WQMP.
760
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
Appendix A
Conditions of Approval
N/A
Planning Commission Resolution
Dated
761
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
Appendix B
Vicinity Map, WQMP Site Plan, and Receiving Waters Map
762
Item 2.
763
Item 2.
764
Item 2.
765
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
Appendix C
Supporting Detail Related to Hydrologic Conditions of Concern N/A
766
Item 2.

Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
Appendix D
Educational Materials
767
Item 2.

What is stormwater runoff?
Why is stormwater runoff a problem?
The effects of pollution
Stormwater runoff occurs when precipitation
from rain or snowmelt flows over the ground.

Impervious surfaces like driveways, sidewalks,
and streets prevent stormwater from
naturally soaking into the ground.

Stormwater can pick up debris, chemicals, dirt, and other pollutants and flow into a storm sewer system or directly to a lake, stream, river, wetland, or coastal water. Anything that enters a storm sewer system is discharged untreated into the waterbodies we use for swimming, fishing, and providing drinking water.

Polluted stormwater runoff can have
many adverse effects on plants, fish,
animals, and people.

Sediment can cloud the water
and make it difficult or
impossible for aquatic plants to
grow. Sediment also can
.

destroy aquatic habitats
Excess nutrients can cause
algae blooms. When algae die,
they sink to the bottom and decompose
in a process that removes oxygen from
the water. Fish and other aquatic
organisms can’t exist in water with low
dissolved oxygen levels.

Bacteria and other pathogens can wash
into swimming areas and create health
hazards, often making beach closures
necessary.

Debris—plastic bags, six-pack rings, bottles, and
cigarette butts—washed into waterbodies can choke, suffocate, or disable aquatic life like ducks, fish, turtles, and birds.

Household hazardous wastes like insecticides, pesticides, paint, solvents, used motor oil, and other auto fluids can poison aquatic life.

Land animals and people can become sick or die from eating diseased fish and shellfish or ingesting polluted water.

Polluted stormwater often
affects drinking water
sources. This, in turn, can
affect human health and
increase drinking water
treatment costs.

After the Storm
EPA 833-B-03-002
January 2003
For more information contact:
or visit
www.epa.gov/npdes/stormwater
www.epa.gov/nps
A Citizen’s Guide to
Understanding Stormwater

WHEN IT RAINS

IT DRAINS

WHEN IT RAINS
IT DRAINS Internet Address (URL) HTTP://www.epa.gov
Recycled/Recyclable Printed With Vegetable
Oil Based Inks on 100% Postconsumer,
Process Chlorine Free Recycled Paper
●
●
768
Item 2.

Auto care
Washing your car and
degreasing auto parts at home
can send detergents and other
contaminants through the
storm sewer system. Dumping
automotive fluids into storm
drains has the same result as
dumping the materials directly
into a waterbody.

Pet waste
Pet waste can be
a major source of
bacteria and
excess nutrients
in local waters.
When walking
your pet,
remember to pick up the
waste and dispose of it
properly. Flushing pet
waste is the best disposal
method. Leaving pet waste
on the ground increases
public health risks by
allowing harmful bacteria
and nutrients to wash into
the storm drain and
eventually into local
waterbodies.

Septic
systems
Leaking and
poorly
maintained
septic
systems release nutrients and
pathogens (bacteria and
viruses) that can be picked up
by stormwater and discharged
into nearby waterbodies.

Pathogens can cause public
health problems and
environmental concerns.

Lawn care
Excess fertilizers
and pesticides
applied to lawns
and gardens wash
off and pollute
streams. In
addition, yard
clippings and
leaves can wash
into storm drains and contribute
nutrients and organic matter to streams.

Education is essential to changing people's behavior.

Signs and markers near storm drains warn residents
that pollutants entering the drains will be carried
untreated into a local waterbody. Recycle or properly dispose of household products that contain chemicals, such as insecticides, pesticides, paint, solvents, and used motor oil and other auto fluids.

Don’t pour them onto the ground or into storm drains.

Use a commercial car wash that treats or
recycles its wastewater, or wash your car on
your yard so the water infiltrates into the
ground.

Repair leaks and dispose of used auto fluids
and batteries at designated drop-off or
recycling locations.

Don’t overwater your lawn. Consider
using a soaker hose instead of a
sprinkler.

Use pesticides and fertilizers
sparingly. When use is necessary, use
these chemicals in the recommended
amounts. Use organic mulch or safer
pest control methods whenever
possible.

Compost or mulch yard waste. Don’t
leave it in the street or sweep it into
storm drains or streams.

Cover piles of dirt or mulch being
used in landscaping projects.

Inspect your system every
3 years and pump your
tank as necessary (every 3
to 5 years).

Don't dispose of
household hazardous
waste in sinks or toilets.

Dirt, oil, and debris that collect in
parking lots and paved areas can be
washed into the storm sewer system
and eventually enter local
waterbodies.

Sweep up litter and debris from
sidewalks, driveways and parking lots,
especially around storm drains.

Cover grease storage and dumpsters
and keep them clean to avoid leaks.

Report any chemical spill to the local
hazardous waste cleanup team.

They’ll know the best way to keep
spills from harming the environment.

Erosion controls that aren’t maintained can cause
excessive amounts of sediment and debris to be
carried into the stormwater system. Construction
vehicles can leak fuel, oil, and other harmful fluids
that can be picked up by stormwater and
deposited into local waterbodies.

Divert stormwater away from disturbed or
exposed areas of the construction site.

Install silt fences, vehicle mud removal areas,
vegetative cover, and other sediment and
erosion controls and properly maintain them,
especially after rainstorms.

Prevent soil erosion by minimizing disturbed
areas during construction projects, and seed
and mulch bare areas as soon as possible.

Uncovered fueling stations allow spills to be
washed into storm drains. Cars waiting to be
repaired can leak fuel, oil, and other harmful
fluids that can be picked up by stormwater.

Clean up spills immediately and properly
dispose of cleanup materials.

Provide cover over fueling stations and
design or retrofit facilities for spill
containment.

Properly maintain fleet vehicles to prevent
oil, gas, and other discharges from being
washed into local waterbodies.

Install and maintain oil/water separators.

Lack of vegetation on streambanks can lead to erosion. Overgrazed pastures can also contribute excessive amounts of sediment to local waterbodies. Excess fertilizers and pesticides can poison aquatic animals and lead to destructive algae blooms. Livestock in streams can contaminate waterways with bacteria, making them unsafe for human contact.

Keep livestock away from streambanks and provide
them a water source away from waterbodies.

Store and apply manure away from waterbodies and in
accordance with a nutrient management plan.

Vegetate riparian areas along waterways.

Rotate animal grazing to prevent soil erosion in fields.

Apply fertilizers and pesticides according to label
instructions to save money and minimize pollution.

Permeable Pavement
Rain Barrels
Rain Gardens and
Grassy Swales
Vegetated Filter Strips
—Traditional concrete and
asphalt don’t allow water to soak into the ground.

Instead these surfaces rely on storm drains to
divert unwanted water. Permeable pavement
systems allow rain and snowmelt to soak through,
decreasing stormwater runoff.
—You can
collect rainwater from
rooftops in mosquitoproof containers. The
water can be used later on
lawn or garden areas.
—Specially
designed areas planted
with native plants can provide natural places for
rainwater to collect
and soak into the
ground. Rain from
rooftop areas or paved
areas can be diverted
into these areas rather
than into storm drains.
—Filter strips are areas of
native grass or plants created along roadways or
streams. They trap the pollutants stormwater
picks up as it flows across driveways and streets.

Residential landscaping
Improperly managed logging operations can result in erosion and sedimentation.

Conduct preharvest planning to prevent erosion and lower costs.

Use logging methods and equipment that minimize soil disturbance.

Plan and design skid trails, yard areas, and truck access roads to minimize stream crossings and avoid disturbing the forest floor.

Construct stream crossings so that they minimize erosion and physical changes to streams.

Expedite revegetation of cleared areas.

Commercial
Stormwater Pollution Solutions
Construction
Agriculture Automotive
Facilities
Forestry
769
Item 2.
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771
Item 2.
772
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773
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774
Item 2.
775
Item 2.

Infiltration System
Inspection and Maintenance Checklist
Property Address: Property Owner:

Treatment Measure No.: Date of Inspection: Type of Inspection:  Monthly  P re-Wet Season  Afte r he a vy runoff(1” or greater)
Inspector(s):  End of We t S e a s on  Other:_____________

Defect Conditions When Maintenance Is Needed Maintenance Needed?
(Yes/No)
Comments (Describe maintenance
completed and if needed maintenance
was not conducted, note when it will be
done)
Results Expected When Maintenance
Is Performed

1. Standing Water When water stands in the infiltration system between storms and does not drain within 3
days after rainfall.

There should be no areas of standing
water once inflow has ceased. Any of
the following may apply: sediment or
trash blockages removed, improved
grade from head to foot of infiltration
system.

2. Trash and Debris
Accumulation
Trash and debris accumulated in the infiltration
system.

Trash and debris removed from
infiltration system and disposed of
properly.

3. Sediment Evidence of sedimentation in system. Material removed and disposed of properly so that there is no clogging or
blockage.

4. Inlet/Outlet Inlet/outlet areas clogged with sediment or debris, and/or eroded.

Material removed and disposed of
properly so that there is no clogging or
blockage in the inlet and outlet areas.

5. Overflow
Spillway
Clogged with sediment or debris, and/or
eroded.

Material removed and disposed of
properly so that there is no clogging or
blockage, and system is restored to
design condition.

6. Miscellaneous Any condition not covered above that needs attention in order for the infiltration system to
function as designed.

Meet the design specifications.
776
Item 2.

Infiltration System Maintenance Plan
for
Routine Maintenance Activities
The principal maintenance objective is to prevent sediment buildup and clogging, which reduces pollutant removal efficiency and may lead to system failure. Routine maintenance activities, and the frequency at which they will be conducted, are shown in Table 1.

Table 1
Routine Maintenance Activities for Infiltration Systems No. Maintenance Task Frequency of Task
1 Remove obstructions, debris and trash from infiltration system and dispose of properly. Drywells may cleaned by vacuuming the upper chamber with a vacuum truck.

Monthly, or as needed after storm
events
2 Inspect system to ensure that it drains between storms, and within 3 days after rainfall. Check drywell/observation well 2-3 days after storm to confirm drainage.

Monthly during wet season, or as
needed after storm events
3 For drywells, replace filter material (and screen if it is damaged) in accordance with City of Rancho Mirage
Standard Detail No. 306 (see attached).

Monthly, or as needed after storm
events
4 Monitor drywell/observation well to confirm that system has drained during dry season.

Annually, during dry season
5 Remove any trash, grass clippings and other debris in the streets, gutters or parking area (see BMP SC-43) and
near the system perimeter. Dispose of properly.

As needed
6 Inspect infiltration system using the inspection checklist. Monthly, or after storm events 1” or greater, and after removal of
accumulated debris or material
Mosquito Abatement
Standing water shall not remain in the treatment measures for more than three days, to prevent mosquito generation.

Inspections
The Infiltration System Inspection and Maintenance Checklist provided shall be used to conduct inspections monthly (or as needed), identify needed maintenance, and record maintenance that is conducted.
777
Item 2.

PROGRAM IMPLEMENTATION
Program Implementation
Section 10 – Public Education and Outreach Page 10-1

10. PUBLIC EDUCATION AND OUTREACH

WATERSHED SPECIFIC EDUCATIONAL ACTIVITIES CONDUCTED DURING THE

REPORTING PERIOD
This section provides an overview of watershed specific education activities conducted by the Permittees. During the reporting period Appendix E contains images of most public education materials that are described in this section.

Program Overview
The Riverside County NPDES Permittees have established an ongoing watershed based public education and outreach program known as the “Only Rain Down the Storm Drain” pollution prevention program. The specific objectives of the public education program include:
• Fostering a broad public awareness of water pollution concerns; • Increasing public acceptance of pollution prevention activities to curtail everyday human behaviors that contribute to water quality problems;
• Educating/informing the general public, regulators and key local government and state decision makers on Urban Runoff conditions in Riverside County; and • Promoting stewardship of local water resources.

The “Only Rain Down the Storm Drain” program implements the public awareness objectives by focusing on three areas of pollutant reduction/prevention:
• Public Behavior;
• Proper Management of Pollutants; and
• Business Specific Education Outreach.

In addition, when attempting to make use of the finite resources available to the Public Education Program, the Permittees use these management goals to ensure that resources are used effectively:
• Focusing on pollutants of concern specific to each watershed region; • Coordinating public education efforts with adjacent storm water management programs and other related education programs to share resources, coordinate outreach efforts, and avoid costly duplication of effort; and
• Adapt public education programs and objectives, based on effectiveness analysis, to address changing MS4 programs and objectives.

Program Highlights
The public education program continues to develop changes for the better. Highlights include:
• The public education program has developed surveys in both English and Spanish. The purpose of these surveys is to evaluate the effectiveness of the public education program and are distributed to the public at community events. The results of these surveys are contained in Appendix E. Two surveys were also developed for the K-3 and 4 through 6 grades education outreach programs.
778
Item 2.

PROGRAM IMPLEMENTATION
Program Implementation
Section 10 – Public Education and Outreach Page 10-2
• The public education web page continues to be revamped and improved. • The program continues to update brochures and develop outreach programs specific to the needs of the MS4.
• As part of the on-going effectiveness evaluation for the municipal training programs, testing has been incorporated into the training for evaluation of its efficiency. In addition, the overall training program was evaluated and is included in the Assessment and Enhancement Analysis of the NPDES Traning Program, August 2006 in Appendix E. • Each month, the County hosts a New Employee Orientation to an average of forty new employees. All the attendees receive “Only Rain Down the Storm Drain” materials and promotionals. The Toll Free 800 Number the message to call to report illegal storm drain disposal is incorporated into all materials.

Santa Ana Pollutants of Concern
Based on monitoring data collected to date, the current 303(d) list and discussions among the CoPermittees, and stakeholders, the following preventative pollutants of concern were established for this watershed. More discussion on the selection of preventative pollutants of concern can be found in the monitoring section of this report. After each identified pollutant, specific BMP outreach activities are identified to address the pollutant:
• Sedimentation associated with Urban Development and Land Uses o Specific section on construction, municipal, industrial/commercial and new development training focusing on the need to address sedimentation within the watershed;
o Distribution of dust pans at public education outreach events to promote dry cleaning of drive ways and impervious surfaces;
o Construction BMP Poster;
o School/Student program incorporates education on controlling soil erosion; o The “After the Storm” and Storm Water Pollution, what you should know brochures o General Construction Activities & Outdoor Activities brochure • Nutrients and pathogens associated with Urban Development and Land Uses o Specific section on construction, municipal, industrial/commercial and new development training focusing on the need to address increased nutrients within the watershed;
o Pet Waste “What’s the Scoop” brochure;
o Partnership with SGA Advertising to place pet waste information in pet stores, veterinarian clinics, kennels and pet grooming facilities; o Coordination with Riverside County Animal Control Department to distribute “What’s the Scoop” and “After the Storm” brochures to families adopting pets; o The Agricultural Commissioner assist in educating on water conservation, fertilizer management and integrated pest management practices. In conjunction with County Waste Management’s Composting Workshop, the “After the Storm” brochure and 779
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Household Hazardous Waste flyer is included in the adult informational packet. o "Keep Our Water Clean" video to cover proper use of fertilizers as well as excess runoff from sprinklers;
o Earth Day mailing inserts were developed to inform residents about the problem of storm water pollution and provide simple pollution prevention activities in gardening; o Adult presentations conducted by RCRCD discussing the effects of fertilizers and pesticides on local waterways;
o The “After the Storm” brochure; and
o Construction BMP Activities brochure and poster.

In addition, the District has developed other outreach materials to focus on other pollutants and pollutant causing activities/businesses commonly associated with urban runoff. Outreach methods can be combined to focus on specific pollutants that may exist within the watershed. 24-hour Watershed-Wide Outreach Portals
The Permittees maintain three 24-hour/7 days per week watershed wide portals to receive and distribute information regarding the “Only Rain Down the Storm Drain” program. These portals include a website, 1-800 number, and an e-mail address.

Storm Water Protection Program Website
The District operates a website that provides information on how to report illegal dumping, clogged storm drains, facility signage and worn or missing curb markers, as well as provide information on upcoming activities, opportunities for public participation in program development and general information about Urban Runoff pollution prevention techniques. The website is located at:
http://www.floodcontrol.co.riverside.ca.us/stormwater/
Almost all of the District’s outreach materials have been scanned into an electronic .pdf format and are available for download. Online Order forms and phone numbers are also available to assist in obtaining information that might not be available online.

The website contains pages specific to the following target audiences:
• General Public/Residents
• Businesses
• Developers
• Contractors
• Schools and Teachers
• Kids Page
In addition the website contains links to:
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• Assist viewers in locating their watershed
• An online media library
• Materials order form
• 1-800 information to report storm drain pollution
The District tracks the number of hits to its public education website. The website was completely revamped during the previous reporting period and the web-page counter replaced this reporting period. Results of the webpage counter report are included in Appendix E.

Storm Water toll free 1-800 Hotline
On October 1994, a Toll Free “800” telephone number for reporting suspected Urban Runoff pollution and obtaining pollution prevention information was established.

1. This call line offers easy to understand instructions for connecting to County Environmental Health or Waste Management to obtain grasscycling, composting, or household hazardous waste collection dates and locations.

2. The 24-hour Hotline also allows callers to report clogged catch basin inlets, illegal dumping and other illicit discharge violations.

3. Finally, the hotline allows people to order public education materials and/or request storm water presentations for schools or community groups. The Permittees advertise the hotline in all appropriate County telephone directories, public education outreach materials, and in other appropriate venues and locations. Callers to the hotline are given options to seek emergency services if the spill is of a suspicious origin or a safety issue.

The 1-800 line diverts callers to appropriate Permittee departments based on caller selections.

Callers requesting information on pollution collection activities are diverted to either County Environmental Health or Waste Management depending on their specific selection. Callers reporting illicit discharges are directed to County Code Enforcement, who accepts the calls and then re-directs them to appropriate Permittee Code Enforcement Departments. Calls for public education materials or presentations are directed to the district’s front desk and then to the District’s Public Education Staff. School presentation inquiries are directed to the Riverside County Conservation District office, who have been contracted to provide education to elementary schools in the Santa Ana Region. The specific text to the hotline is included as Exhibit A.

The provider of the 1-800 line, Riverside County Communication, tracks the number of incoming calls to the line. This tracking mechanism was discontinued during past reporting period but restored this reporting period.
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Exhibit A
“ONLY RAIN DOWN THE STORM DRAIN” POLLUTION PREVENTION PROGRAM TOLL FREE 1-800 LINE DIALOGUE
Thank you for calling the “Only Rain Down the Storm Drain” Pollution Prevention Program. To better serve the needs of our County communities, please listen carefully to the following options:

If this is an emergency, or you wish to report a significant release or threatened releases of hazardous material into the storm drain or elsewhere in the environment, please hang up and immediately Dial 911. (Si esta llamada es una emergencia o decea reportar desechos de contaminantes peligrosos en las alcantarillas o en el medio ambiente, por favor cuelge y llame 911.)
For water service connection, disconnection, or any other water utility information, call your local water service provider.

To report illegal dumping at residential, commercial, industrial or construction sites, please call Environmental Health at 951.955.8982, or press #1 to be directly connected.

For information regarding Household Hazardous Waste Collection Events, please Press #2.

To report clogged storm drains, please call your local municipal public works department. To report faded or missing “Only Rain Down the Storm Drain” storm drain markers, please press #3.

For General or specific business pollution prevention information or to receive other pollution prevention information please press #3.
(Drop Off Dialogue)
Thank you for your interest in obtaining information on storm drain pollution protection. Basic, construction, industrial, commercial and children’s storm water protection outreach packets are available. For a quick response to your request, please slowly and clearly leave your name, address, city and zip code. Also state the type and quantity of the materials you are interested in receiving. Should you need additional assistance, provide your area code and phone number and someone will contact you as soon as possible.

To inquire about our free storm water classroom presentations, workshops, youth group activities and other outreach programs, please press #4.
(Drop Off Dialogue)
The “Only Rain Down the Storm Drain” public education program offers classroom presentations, workshops, youth group activities, special event opportunities and other programs. For inquiries for the Temecula or Murrieta area, please press #1 (Drops to Mission Resource Conservation District) For inquiries in all other Riverside County areas, press 2 (drops to Riverside/Corona Resource Conservation District).

For Grasscycling and composting information or workshops, please PRESS #5. (to 951.486.3200) For additional assistance regarding our storm drain pollution prevention program during regular business office hours, Monday through Thursday from 7:30 am to 5:30 pm and on Friday from 7:30 am to 4:30 pm 782
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E-mail
The Permittees also maintain an e-mail address that can be used to report illicit discharges or request storm water related public information. The e-mail address is:

[email protected]
E-mails are received by the District’s Public Information Specialist and are responded to, in most cases, within 2 business days.

Program Coordination with other Stakeholders
The “Only Rain Down the Storm Drain” program has used partnerships to leverage and increase available resources. The Permittees utilize every opportunity to work with Co-permittees, local environmental groups, and other public, private and business organizations to maximize use of existing distribution outlets, events, programs and materials. Impressions, attendance, and other measures of effectiveness relative to these programs are included in Appendix E (Public Education) of this Watershed Annual Report.

To facilitate statewide awareness of storm water public education, educate local and state decision makers, and assist in the development of more effective public education outreach programs, the District participates in the following public education committees:
• Public Information Public Participation Committee (PIPP) – A subcommittee of the California Storm Water Quality Association, and
• Western Regional Pollution Prevention Network (WRPPN) To leverage education outreach resources and coordinate public education activities with other environmental programs, the Permittees closely coordinate and/or have existing partnerships with the following entities/organizations:
• Household Hazardous Waste Information Exchange (HHWIE); This is an eGroup that provides household hazardous waste affiliates the ability to better communicate, share ideas and the latest in legislative rulings.
• Riverside-Corona Resource Conservation District (RCRCD); • Partnership to provide student education outreach in the Santa Ana and Whitewater Watersheds
• Partnership to provide adult education outreach activities in the Santa Ana and Whitewater Watersheds
• Partnership to provide support services for public education outreach activities at community events
• Mission Resource Conservation District (RCRCD);
• Partnership to provide student education outreach in the Santa Ana and Santa Margarita Watersheds
• Partnership to provide adult education outreach activities in the Santa Ana and Santa Margarita Watersheds
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o Partnership to provide support services for public education outreach activities at community events
• California Regional Environmental Education Community Network (CREEC) o A network whose mission is to develop a communication network which provides educators with access to high quality environmental education resources to enhance the environmental literacy of California students.
• Santa Ana River Watershed Clean Up Stakeholders Group in coordination with Riverside Corona Conservation District, Keep Riverside Clean and Beautiful and the California Coastal Commission’s Coast. This collaboration of environmental partners support and encourage volunteers, allies and groups to gather for a day to remove trash and debris from the Santa Ana River that might otherwise flow downstream, through the river to the ocean. • In addition the “Only Rain Down the Storm Drain” program also coordinates with the following City/County departments to distribute appropriate storm water education outreach materials:
o City/County/District Front Counters
o County Waste Management
o County Public Health Department
o Agriculture Department
o County Executive Offices
o Code Enforcement
o County Parks
o Animal Control;
o Economic Development Agency
o County Assessor/Recorders Office
o Bio-terrorism
o Fleet Services
o Human Resources
o Library System
o Central Mail
Stamp on every piece of mail sent by the County that identifies the 1-800 Number and requests that citizens call it to report storm drain pollution. o County Safety
o County DPSS
o Transportation and Land Management
In general, brochures and promotional items are provided to these departments for distribution in public lobbies, training sessions, through customer interactions and new employee orientations.

Finally, the “Only Drain Down the Storm Drain” Program also coordinates with the following state and/or local government or business entities to distribute public education information:
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• Western Riverside Council of Governments
• Santa Ana Regional Water Quality Control Board
• Orange County Watershed & Coastal Resources Division
• Santa Ana Watershed Association
• South Coast Air Quality Management District
• Santa Rosa Plateau
• Bureau of Reclamation
• Elsinore Valley Municipal Water District
• Metropolitan Water District
• Lake Elsinore/San Jacinto Watershed Authority
• Eastern Municipal Water District
• The Water Education Center
• Rancho California Water District
• Valley Greeters
• Department of Water Resources Southern District
• Western Municipal Water District
• Business Industrial Association (BIA)
• Caltrans
Outreach Tools to Change Public Behavior
The “Only Rain Down the Storm Drain” program conducts a wide range of outreach activities to residents, students, community groups, new home owners, homeowner associations; informing them of how their “everyday activities” may contribute to the pollution of Receiving Waters, and encouraging them to adopt alternatives that will lessen or eliminate pollution-causing behaviors.

Program efforts include providing information on pollution prevention techniques and informing residents about the proper disposal of household hazardous wastes, construction materials, used motor oil, pet waste and litter. Public education materials and media emphasize the theme that all citizens have a role to play in reducing and preventing the polluting of Receiving Waters. The goal is to present a clear and consistent message that explains the simple connections between people’s everyday activities and their impacts upon Receiving Water quality.

As the public education and outreach program continues to be implemented and enhanced, the Permittees hope to broaden public awareness of Urban Runoff quality problems, promote proper disposal of household hazardous waste and motor oil, encourage illegal discharge reporting, foster good stewardship of Receiving Waters, and take personal responsibility for their actions in preventing pollution.

While public education outreach at events indicates that most people are willing to act in an environmentally responsible manner if given simple ways to change their behavior to avoid polluting our water bodies; most are unaware of the sources of pollution from everyday urban land use. The “Only Rain Down the Storm Drain” pollution prevention program using various media forms educates the County’s population about modified behaviors to prevent storm water pollution by focusing on residents, general public, students, home gardeners, do-it-yourselfers, mobile businesses, etc.
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Direct Outreach Methods
The “Only Rain Down the Storm Drain” program interfaces directly via program staff, or through contracts and partnerships, to the public through attendance at community events, school education programs, adult education programs and/or by providing classroom based training. Specific outreach activities, segregated by target audiences, are described below.

General Community Outreach
The “Only Rain Down the Storm Drain” program participates in various community events to ensure that our message is delivered to the largest possible municipal audience. At these community events, surveys, to assess overall program effectiveness, have been used.

In addition, the “Only Rain Down the Storm Drain” program has partnered with County Environmental Health to ensure that a storm drain pollution prevention material is available and distributed at all Household Hazardous Waste and Antifreeze, Batteries, Oil and Paint Collection Centers and/or Events throughout each of the Watershed Region’s within Riverside County. These events provide free disposal sites for receiving common pollutants that can impair Receiving Waters.

Elementary School Outreach
Elementary (K-6)
The Riverside County Resource Conservation District (RCRCD) continues to provide a variety of K-6 education programs for the “Only Rain Down the Storm Drain” Program. The K-6 education program includes materials such as the Storm Water Pollution Prevention Patrol workbook, the Fancy Fin hands-on classroom presentation and accompanying coloring book, various word match and crossword activity sheets and videos. A second story line featuring Fancy Fin and her friend Phinnious J. Green (a Pacific Tree Frog) educate students about point and non-point pollution and their effects on the environment and other creatures in the watershed. School materials are offered to all public and provide schools in the Santa Ana Watershed Region, as well as to youth groups such as the boy and girl scouts.

Secondary Schools
A video entitled “How to Conduct an Environmentally Friendly Car Wash and Make Money Too” was developed for the “Car Wash Challenge” program. An accompanying flyer is also used which informs students/groups of the potential storm water problems generated from car wash runoff, and provides practical BMPs to minimize or eliminate contaminated runoff. The original focus of the program was high school clubs. However, after contacting several high schools, it was discovered that car washing fundraisers are relatively rare and revenue deficient in comparison with other high 786
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school fund raising activities. Nevertheless, church groups, scout troops and other organizations do conduct car wash fundraisers. Thus, the scope of the Car Wash Challenge program has been expanded to include these additional fundraising organizations.

Adult Outreach
Valley Greeters is a “Welcoming Wagon” business taking discount coupons, product samples and general vicinity information door to door to new residents and homeowners to the Temecula, Murrieta and Lake Elsinore area. For the past four years, Valley Greeters has included our MS4 materials, (After the Storm; What’s the Scoop; Pool, Spa and Fountain Maintenance and HHW Collection Schedule). This information is accompanied with a handy full size dustpan, shop cloth and vehicle air freshener. Every material and promotional is clearly imprinted with the 1-800 Toll Free number for reporting illegal discharges into the storm drain. Young family members receive a copy of Fancy Finn and box of crayons. This business is solely dependent on the status of the construction economy and by January, 07 experienced a considerable slowdown.

The “Only Rain Down the Storm Drain” program contracts with the Riverside/Corona Resource Conservation District for public outreach. Storm Water Pollution Prevention presentations are given to community groups who call and request such services.

Steve Groner & Associates has been retained to prepare and present workshops at major home improvement stores throughout Riverside County. The workshops include passing out reading material regarding targeted BMPs to the public through established corporate partnerships (paint, hardware, home show coordinators, home improvement, garden centers, nurseries and pet stores).

All commercial employees are informed about storm water impacts that could occur from the improper application of all types of home and garden hazardous chemicals. In turn, the employees are then able to share with customers on the proper use and disposal of products that are potential storm drain pollutants. Attendees at the workshop receive “Only Rain Down the Storm Drain” promotionals to help emphasize the storm water pollution prevention message. Fixed advertising tools such as counter displays, tear sheets have been placed throughout to attract attention.

Brochures
Residential: After the Storm; Storm Water Pollution and the Solutions, Household Hazardous Waste Collection Schedule, Outdoor Activities; Swimming Pool, Jacuzzi and Fountain Maintenance; and What’s the Scoop (Pet waste).

Outreach Materials
In addition to the brochures mentioned above, the program utilizes other effective outreach materials such as, magnets, a billboard ad, videos, newspaper supplements, flyers, door knob hangers, calendars, promotionals items, workbooks, curriculum, shop rags, shelf talkers, tear sheets, posters and print ads to cultivate interest in the program. 787
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A door hanger is also being utilized to help address problem discharges that are commonly observed in residential settings. The door hanger notifies the recipient that a problem discharge was observed flowing in to the street and offering help by following recommended pollution prevention activities. The door hanger is provided to all cities and is used by various County departments and the NPDES staff when conducting field or site activities/inspections.

Mailing Inserts/Slugs
The “Only Rain Down the Storm Drain” Pollution Prevention Program encourages advertising the County’s Household Hazardous Waste Collection events via the use of mail inserts. The inserts are included in various utility bills and special notice mass mailings.

In addition, the “Only Rain Down the Storm Drain” program has coordinated with the County Mail Department to have the postage meter carry the “Only Rain Down the Storm Drain” message and the 1-800 Toll Free number to report an illegal storm drain disposal or spill. In 05/06, over 5,000,000 pieces of outgoing County mail were stamped with the message. In November of 06, the postage system was replaced with more sophisticated postage meter units but the cost of the ink in the new system far exceeded the costs and benefits from other media options and therefore this media venue was dissolved.

Media Outreach
The “Only Rain Down the Storm Drain” Program continues to utilize various mass media to reach the public and promote the storm water pollution prevention. Special newspaper inserts, fliers, and advertisements help increase public awareness of storm water pollution and environmental protection.
• Our Sixth Edition of a four-page insert called the National Pollution Prevention or P-2, (National Pollution Prevention Week recognization), was distributed Countywide through the PennySaver. The insert included topics on proper disposal of pet waste, pesticide alternatives, motor oil recycling, grass-cycling, pool and spa best management practices, storm drain marking program, storm water school presentations, general storm drain pollution protection, business storm water pollution information, household hazardous waste (HHW) collection events, syringe disposal program, composting workshops and motor oil specific recycling locations. The insert is released to over 650,500 Riverside County homes generating an increase of calls to the 800 Toll Free Hotline and District IC/ID investigations.

Cooperative Used Oil Program
The Western Riverside Council of Governments (WRCOG) is responsible for administering the Used Oil Block Cycle Grant on behalf of ten cities within WRCOG’s boundaries. These cities include: Banning, Beaumont, Canyon Lake, Lake Elsinore, Murrieta, Norco, Perris, Riverside, San Jacinto and Temecula.
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The objective of the Used Oil Block Grant is to make it convenient for Do-It-Yourselfers (DIYers) to recycle their used oil and to make it easy for them to find a Certified Center accepting used oil.

In order for these centers to be certified, they need to apply for certification with the California Integrated Waste Management Board (CIWMB). As a grant recipient, WRCOG contacts noncertified centers in the jurisdiction to interest them in becoming certified used motor oil collection center. The goal is to see a significant decrease in the amount of illegally dumped motor oil by adding more oil collection centers within close proximity to users.

Through the same grant funding source, WRCOG also provides used oil containers for distribution to DIYers who need proper containers for automotive fluids. Through WRCOG efforts, all certified centers in the County are in compliance to state and local mandates.

The Storm Drain Pollution Prevention Program assists WRCOG’s efforts by making available our MS4 information and supporting promotionals for distributions to their targeted groups.

At various venues, WRCOG staff obtain participant responses to a ten question survey. The survey examines the public’s understanding on:
o used oil recycling,
o used oil drop-off locations,
o curbside programs, and other local recycling programs.

The program also maintains an English and Spanish 800 hotline that can be used to get answers to any recycling question a resident may have regarding, “where the nearest Certified Center is located?” and “where can I find a used oil container?”. The phone number is printed on all distributed materials including the oil containers.

Cleanest County in the West Program
Through another grant funding source, WRCOG created the “Cleanest County in the West” program to address issues relating to litter and illegal dumping. The program was designed to assist jurisdictions in meeting the 50% diversion goals mandated by Assembly Bill 939. AB 939 was a state mandate signed in 1989 that required cities to reduce their waste by 50% by the Year 2000.

The core of the program is the elementary school assembly. WRCOG partners with Radio Disney AM 1290 to present an interactive and informational presentation for children in grades K-6th. This program continually reinforces the responsibility of everyone to recycle and pick up litter.

WRCOG at the end of the assembly gives the school two recycling containers for the collection of cans and bottles. During the 06/07 school year, over 18,000 students and 600 teachers have experienced the assembly. Each student receives an environmental activity book and an application to join the Riverside County Kids Recycle Club where they will receive a quarterly newspaper. This club has over 200 members.
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Like the “Only Rain Down the Storm Drain” Program which promotes litter reduction and recycling throughout the Santa Ana Region, WRCOG also participates in events to promote litter reduction and beverage container recycling. These events gives staff an opportunity to assess how informed the local community is regarding recycling and also allows us to distribute brochures and informational flyers that will assist people in finding the nearest recycling center. During these events promotional items made from recycled content are also given out to show examples on how used items such as money can be recycled into new things such as a pencil, a promotional product first used by the “Only Rain Down the Storm Drain” Program. This particular promotional item especially increases the interest of the people visiting out booth and demonstrates how almost anything can be recycled and reused.

Outreach tools specific to Business Specific
The “Only Rain Down the Storm Drain” Program conducts a wide range of outreach activities to businesses; informing them of how their “everyday activities” may contribute to the pollution of Receiving Waters, and encouraging them to adopt alternatives that will lessen or eliminate polluting-causing activities. Program efforts include providing information on pollution prevention techniques and informing businesses about the proper disposal of wastes. Public education materials and media emphasize the theme that all businesses have a role to play in reducing and preventing the polluting of Receiving waters. The goal is to present a clear and consistent message that explains the simple connections between a business’ everyday activities and their impacts upon Receiving Water quality.

Originally, the business education program mainly consisted of the development and distribution of formal BMP guidance and outreach to business associations. The program has now expanded to include direct outreach to businesses through classroom formats, advertising in business trade papers and providing exhibits at various business specific symposiums.

Discussion of the current Business Specific Outreach tools implemented by the Permittees are discussed below.

Direct Business Outreach Activities
The “Only Rain Down the Storm Drain” Program partners with various entities to provide training and education. Currently, the District has allowed AEI-CASC Engineering, a consultant who provides the Permittees internal education programs to train developers and consultants regarding the new WQMP/SUSMP requirements for Riverside County. The District has partnered with Riverside/Corona Resource Conservation District, to develop a Water Quality Design class that focuses on sub-regional solutions and low impact development. This class was offered for the first time through UCR extension in October 2005. Additionally, the District presented at Construction Storm Water Compliance Workshop hosted by the Building Industry Association of Southern California (BIA/SC) on March 22, 2006. The workshop focused on state and municipal construction requirements for contractors, developers, and consultants. 790
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Through the Compliance Assistance Program (CAP), a partnership with County Environmental Health restaurants and businesses that handle hazardous wastes are reviewed for potential storm water impacts from their activities. Each business is provided with storm drain pollution prevention public education outreach information specific to their activities.

Steve Groner Associates has been retained to prepare and present workshops at major home improvement stores throughout Riverside County. The workshops include a handout educating the store’s employees about storm water impacts that could occur from improper application of paint, pesticides or fertilizers. Attendees at the workshop also receive “Only Rain Down the Storm Drain” information and promotionals to help highlight the storm water protection message.

Employees are then able to share with customers the proper use and disposal of products that are potential storm drain pollutants. Point of purchase displays, tearsheets, and counter displays have been installed at strategic locations to educate the public directly.

Each new business trade in Riverside County that is listed in the Inland Business Press newspaper is provided with an “Only Rain Down the Storm Drain” Pollution Prevention packet.

Brochures
Commercial: After the Storm; Food Facilities; Outdoor Cleaning Activities and Non-Point Source Discharges; Automotive Maintenance & Car Care. Note: (Staff is revising the Outdoor Activity brochure to include broader examples of urban pollution causing activities such as, power washers and mobile vehicle maintenance operators).

Industrial: After the Storm; Outdoor Cleaning Activities and Non-Point Source Discharges; and Your Facility May Need a Storm Water Permit.

Construction: After the Storm; Outdoor Cleaning Activities and Non-Point Source Discharges; General Construction & Site Supervision The revision to the construction brochure is pending the finalization of the construction permit.

Posters
BMP posters for automotive, food service establishments (available in Spanish) and construction employees are available. The posters address activities associated with the automotive repair industry, and the food/restaurant industry that may pose a threat to water quality. There are also two new posters for the Fueling Stations and Service Bay Service centers. All the posters recommend storm water BMPs and are designed to serve as informative and attractive visual reminders for employees.

Media Outreach
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water quality. The ad also provided links to the District’s and CASQA’s website for more detailed BMP information.

Supplemental Environmental Projects (SEP)
In an effort to change the behaviors of large storm drain pollution prevention offenders in the County, Environmental Health established a Supplemental Environmental Project (S.E.P.). The S.E.P. requires from the violator a monetary fine and/or the violator’s cooperation for the development of a public education tool on the effects of polluted urban run off. S.E.P.’s to date include:
• A Downs Energy SEP project resulted in the development of a billboard ad that has been greeting commuters traveling Westbound on the 60 Freeway lanes.

Outreach tools specific to Pollutants
“Only Rain Down the Storm Drain” Pollution Prevention Program conducts a wide range of outreach activities focusing on reduction of certain pollutants in the receiving waters. These outreach activities focus on sources of those pollutants whether it is residential, business, municipal or some other state or federal source. Education materials explain how “everyday activities” of potential sources may contribute to the pollution of receiving waters, and encourage the sources to adopt alternative approaches to pollutant management that will lessen or eliminate pollutingcausing activities. Program efforts include providing information on pollution prevention techniques and informing sources about the proper disposal of pollutants. Public education materials and media emphasize the theme that all citizens/businesses have a role to play in reducing and preventing the polluting of receiving waters. The goal is to present a clear and consistent message that explains the simple connections between a business’ everyday activities and their impacts upon receiving water quality.

Each subsection that follows identifies how existing outreach materials previously described address specific potential pollutant sources in the watershed.

Use of pesticides, fertilizers, and herbicides
A. The Riverside County Agricultural Commissioner's Pesticide Applicator's License renewal information package includes materials on the proper use of pesticides and offers information on training workshops. The license renewal process requires continuing education of applicants and detailed record keeping of pesticide applications. Municipal employees that are responsible for the application of pesticides are encouraged to obtain and maintain credentials as Certified Applicators and/or licensed Pest Control Advisors.

B. The "Home Garden Care” materials are being revised to draw and attract the interest of the general public and amateur gardener. The new materials will include Integrated Pest Management and plant selection and materials from the State Water Resource Control Board, Central Contra Costa IPM Outreach Program, University of California and The 792
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Orange County Storm Water Program are being used. All the materials selected offer alternatives to using chemically based pesticides, herbicides and fertilizers.

C. The "Keep Our Water Clean" video covers proper use of pesticides, fertilizers and herbicides as well as excess runoff from sprinklers.

D. The September annual “Only Rain Down The Storm Drain’s” participation in the National Pollution Prevention Week insert informs residents about the problem of storm water pollution and provides simple pollution prevention activities in gardening.

E. The “Only Rain Down The Storm Drain” adult presentations conducted by RCRCD discusses the effects of pesticides and fertilizers on local waterways. The materials distributed following the presentation promote alternatives to pesticide use in the yard and garden.

F. The 2006 Environmental Calendar included a wide array of storm water protection information. It is designed to attract the adult audience by listing best management practices, scheduled special events, household hazardous waste collection sites, used oil collection sites, composting workshops, citywide clean ups, and each of the watersheds along with geographical information. Throughout the calendar the main message is “Only Rain Down The Storm Drain” and the hotline number to call for additional home garden care information.

G. Steve Groner Associates has been retained to prepare and present employee workshops at major home improvement stores throughout Riverside County. This information is then passed on to the public via the shelf talkers accessible to the public or when an employee is addressed with a question. The workshops include information on BMPs the public should be aware of for pesticide and fertilizer application, use, and storage. 793
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Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
Appendix E
Soils Report
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Whitewater River Region Preliminary WQMP
Calhoun Street Subdivision
Appendix F
Structural BMP and/or Retention Facility Sizing Calculations and Design Details
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SW CORNER – CALHOUN ATREET AT 49TH AVENUE

SUBDIVISION

PRELIMINARY HYDROLOGY REPORT
TABLE OF CONTENTS:

I PURPOSE AND SCOPE

II DESIGN METHODOLOGY

III RCFCD SYNTHETIC UNIT HYDROGRAPH CALCULATIONS

IV STREET FLOWRATE CAPACITY
V APPENDIX – REFERENCE MATERIAL
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I. PURPOSE AND SCOPE
This report was prepared in support of the Calhoun Street at 49th Avenue Subdivision entitlement package submittal. The purpose of this preliminary report is to analyze the existing and proposed drainage patterns, discuss the on-site drainage design and size the proposed on-site drainage facilities to meet the City of Coachella drainage ordinance requirements.

The existing project site is an undeveloped lot at the southwesterly corner of the intersection of Calhoun Street and 49th Avenue in Coachella, CA. The proposed project improvements include the addition of residential lots with an interior access drive serving the lots on a

38.76 acre parcel. The site is bound to the north and east with fully improved public streets, to the east by a residential subdivision under development and to the south by an existing residential subdivision. The project proposes to obtain access to the site from Calhoun Street to the east, and from 49th Avenue to the north. The site will be drain via street surface flow to a series of on-site retention basins designed to capture and and store the storm run off generated during the 100 year design storm event. In general, the existing site is not subject to offsite storm flows.

II. DESIGN METHODOLOGY AND CALCULATIONS
The Calhoun Street project will provide five (5) on-site storm drain infiltration retention basin systems designed to capture and store the runoff generated from the “worst case” 100 year design storm based on City of Coachella requirements. The five retention basins have a combined volume capacity designed to store the runoff generated on-site during the 100 year design storm as well as runoff from the Calhoun Street half street project frontage and the 49 Avenue full width street frontage within the public right of way. The low point on the existing project site occurs on the project’s easterly frontage. Runoff that exceeds the capacity of the on-site retention basin storage systems in an emergency overflow condition is designed to overflow onto interior surface streets and exit via surface flow onto Calhoun Street following the historical drainage pattern toward the south.

Riverside County Flood Control District Synthetic Unit Hydrograph methods are used to quantify the runoff volume generated and stored on-site during the 100 year “worst case” design storm return period. The program data and results prepared for this project are included in the Appendix of this report. The program model typically accounts for the volume of runoff lost due to infiltration in the basins and the allowable design retention basin infiltration rate of 10 gal./s.f./day (0.67 in/hr) established by City of Coachella will be applied over the surface area of the basin bottoms. The combined capacity of all five on-site basins will be compared to the total design runoff volume calculated for the Calhoun Street project to show that runoff generated during the 100 year design storm can be stored within the basins at a depth not to exceed 3ft and the runoff generated during the 10 year storm event can be stored within the on-site basins at a depth not to exceed 1.5 feet in accordance with City of Coachella retention basin criteria.

City of Coachella requires that runoff water stored on-site must be evacuated completely via infiltration within a period of 72 hours in order to comply with vector control concerns. In order to help facilitate this requirement, City of Coachella has limited the maximum depth of 798
Item 2.
stored runoff within any basin to 1.5’ during the 10 year storm event and the maximum depth of any on-site retention basin must not exceed 3.5 feet.

On-site street curb and gutter systems will be designed to convey runoff to the on-site retention basin systems via surface flow. The project site will be designed to ensure that surface runoff generated during the 10 year storm is contained below the top of the proposed street curbs and runoff generated during the 100 year storm event is contained within street right of way. Street flowrates (Q) will be calculated by applying the Rational Method using CivilD software.

DESIGN CRITERIA
The following Riverside County Flood Control District (RCFCD) parameters were used in the preparation of the analyses:

 2 year – 1 hour Precipitation 0.35” (NOAA)
 10 year – 1 hour Precipitation 0.70” (NOAA)
 10 year – 3 hour Precipitation 1.04” (NOAA)
 10 year – 6 hour Precipitation 1.36” (NOAA)
 10 year – 24 hour Precipitation 1.04” (NOAA)
 100 year – 1 hour Precipitation 1.37” (NOAA)
 100 year – 3 hour Precipitation 2.12” (NOAA)
 100 year – 6 hour Precipitation 2.78” (NOAA)
 100 year – 24 hour Precipitation 4.47” (NOAA)
 Hydrologic Soil Type “B” US Dept. of Agriculture, SCS  Runoff Index Number 56 (RCFC&WCD Plate E-6.1)
 Assumed Design Percolation Rate 0.67 in/hr
 Slope Intensity Duration Curve 0.59 (RCFC&WCD Plate D-4.6)

799
Item 2.

III RCFCD SYNTHETIC UNIT HYDROGRAPH CALCULATED RETENTION

VOLUMES

SUBAREA
100 YR.

VOLUME

REQUIRED
(CU.FT.)
BASIN
VOLUME

PROVIDED
(CU.FT.)
100 YR.

BASIN

STORAGE
DEPTH
10 YR. BASIN

STORAGE
DEPTH
1 9,580 12,250 2.45 0.72
2 57,661 64,193 3.19’ 0.99’
3 53,709 62,528 3.07’ 0.94’
4 51,654 57,236 3.20 0.99
5 41,999 72,828 2.14’ 0.54
800
Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 1

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 1.18
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE

MF - CONDOMINIUMS

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 0.83

RETENTION BASIN

GOLF COURSE

MOUNTAINOUS
LOW LOSS RATE (PERCENT) 90%
LENGTH OF WATERCOURSE (L) 1000
LENGTH TO POINT OPPOSITE CENTROID (Lca) 15
ELEVATION OF HEADWATER 471.5
ELEVATION OF CONCENTRATION POINT 468.8
AVERAGE MANNINGS 'N' VALUE 0.02
STORM FREQUENCY (YEAR) 100

POINT RAIN
3-HOUR 1.04
6-HOUR 1.36
24-HOUR 2.23
BASIN CHARACTERISTICS: ELEVATION AREA
465 3025
466 3700
467 4430
468 5215
468.5 5630
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
801
Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT BASIC DATA CALCULATION FORM JOB # 0
SHORTCUT METHOD BY ES R. BAZUA, P.E. DATE 1/17/2025
[1] SOURCE
[2] FREQUENCY-YEARS 100
[3] DURATION:
[4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

1.04 2.010 1.00 1.04 1.36 2.010 1.00 1.36 2.23 2.010 1.00 2.23

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 2.01 SUM [7] 1.04 SUM [9] 2.01 SUM [11] 1.36 SUM [13] 2.01 SUM [15] 2.23 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 1.04 1.36 2.23
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 0.40 0.39 0.26
FLOOD VOLUME (cu-ft) 2,906 2,880 1,903
(acre-ft) 0.07 0.07 0.04
REQUIRED STORAGE (cu-ft) 2,439 2,140 370
(acre-ft) 0.06 0.05 0.01
PEAK FLOW (cfs) 1.56 1.34 0.19
MAXIMUM WSEL (ft) 465.72 465.64 465.10

0.189

15.00 0.000
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 2.7
[11] S-FEET/MILE

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 1

2.010
1000

0.003
471.5
468.8

0.02 1.0

1.0 2.0

14.3 3.78

0.05 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 10 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

RATE IMPERVIOUS RATE
(in/hr) (in/hr) (in/hr)
[Plate C-1] [Plate E-6.1] [Plate E-6.2] [Plate E-6.3]
B 56 0.52 90% 0.10 0.00 0.000 0.0000
B 56 0.52 100% 0.05 1.18 0.587 0.0305
B 56 0.52 20% 0.43 0.00 0.000 0.0000B 56 0.52 40% 0.33 0.00 0.000 0.0000B 56 0.52 50% 0.29 0.00 0.000 0.0000B 56 0.52 65% 0.22 0.00 0.000 0.0000B 56 0.52 80% 0.15 0.00 0.000 0.0000B 56 0.52 75% 0.17 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.83 0.413 0.2147B 56 0.52 0% 0.52 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.00 0.000 0.0000 D 93 0.95 90% 0.18 0.00 0.000 0.0000

0.00 0.000 0.0000

0.00 0.000 0.0000
SUM 2.01 SUM 0.2453
VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY)Fm= 0.122626866C= 0.00227Ft=C(24-(T/60))^1.55 = 0.00227 0.12 in/hr LOW LOSS RATE (80-90 PERCENT) = 90%Where:T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,T=1 1/2 unit time for the second period, etc. (24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 2.01
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.00
UNIT TIME-PERCENT OF LAG 502.5
TOTAL ADJUSTED STORM RAIN-INCHES 1.04
CONSTANT LOSS RATE-in/hr 0.25
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.05 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.162 0.25 0.15 0.02 0.03 0.00
2 10 0.17 1.3 0.162 0.25 0.15 0.02 0.03 0.00
3 15 0.25 1.1 0.137 0.25 0.12 0.01 0.03 0.00
4 20 0.33 1.5 0.187 0.25 0.17 0.02 0.04 0.00
5 25 0.42 1.5 0.187 0.25 0.17 0.02 0.04 0.00
6 30 0.50 1.8 0.225 0.25 0.20 0.02 0.05 0.00
7 35 0.58 1.5 0.187 0.25 0.17 0.02 0.04 0.00
8 40 0.67 1.8 0.225 0.25 0.20 0.02 0.05 0.00
9 45 0.75 1.8 0.225 0.25 0.20 0.02 0.05 0.00
10 50 0.83 1.5 0.187 0.25 0.17 0.02 0.04 0.00
11 55 0.92 1.6 0.200 0.25 0.18 0.02 0.04 0.00
12 60 1.00 1.8 0.225 0.25 0.20 0.02 0.05 0.00
13 65 1.08 2.2 0.275 0.25 0.25 0.03 0.06 3.60
14 70 1.17 2.2 0.275 0.25 0.25 0.03 0.06 3.60
15 75 1.25 2.2 0.275 0.25 0.25 0.03 0.06 3.60
16 80 1.33 2.0 0.250 0.25 0.22 0.00 0.01 0.00
17 85 1.42 2.6 0.324 0.25 0.29 0.08 0.16 33.70
18 90 1.50 2.7 0.337 0.25 0.30 0.09 0.18 41.22
19 95 1.58 2.4 0.300 0.25 0.27 0.05 0.11 18.65
20 100 1.67 2.7 0.337 0.25 0.30 0.09 0.18 41.22
21 105 1.75 3.3 0.412 0.25 0.37 0.17 0.33 86.38
22 110 1.83 3.1 0.387 0.25 0.35 0.14 0.28 71.33
23 115 1.92 2.9 0.362 0.25 0.33 0.12 0.23 56.28
24 120 2.00 3.0 0.374 0.25 0.34 0.13 0.26 63.80
25 125 2.08 3.1 0.387 0.25 0.35 0.14 0.28 71.33
26 130 2.17 4.2 0.524 0.25 0.47 0.28 0.56 154.11
27 135 2.25 5.0 0.624 0.25 0.56 0.38 0.76 214.31
28 140 2.33 3.5 0.437 0.25 0.39 0.19 0.39 101.43
29 145 2.42 6.8 0.849 0.25 0.76 0.60 1.21 349.77
30 150 2.50 7.3 0.911 0.25 0.82 0.67 1.34 387.39
31 155 2.58 8.2 1.023 0.25 0.92 0.78 1.56 455.12
32 160 2.67 5.9 0.736 0.25 0.66 0.49 0.99 282.04
33 165 2.75 2.0 0.250 0.25 0.22 0.00 0.01 0.00
34 170 2.83 1.8 0.225 0.25 0.20 0.02 0.05 0.00
35 175 2.92 1.8 0.225 0.25 0.20 0.02 0.05 0.00
36 180 3.00 0.6 0.075 0.25 0.07 0.01 0.02 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.40
FLOOD VOLUME (acft) 0.07
FLOOD VOLUME (cuft) 2906.38
REQUIRED STORAGE (acft) 0.06
REQUIRED STORAGE (cuft) 2438.86
PEAK FLOW RATE (cfs) 1.56
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 2.01
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.00
UNIT TIME-PERCENT OF LAG 502.5
TOTAL ADJUSTED STORM RAIN-INCHES 1.36
CONSTANT LOSS RATE-in/hr 0.245
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.05 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.082 0.25 0.07 0.01 0.02 0.00
2 10 0.17 0.6 0.098 0.25 0.09 0.01 0.02 0.00
3 15 0.25 0.6 0.098 0.25 0.09 0.01 0.02 0.00
4 20 0.33 0.6 0.098 0.25 0.09 0.01 0.02 0.00
5 25 0.42 0.6 0.098 0.25 0.09 0.01 0.02 0.00
6 30 0.50 0.7 0.114 0.25 0.10 0.01 0.02 0.00
7 35 0.58 0.7 0.114 0.25 0.10 0.01 0.02 0.00
8 40 0.67 0.7 0.114 0.25 0.10 0.01 0.02 0.00
9 45 0.75 0.7 0.114 0.25 0.10 0.01 0.02 0.00
10 50 0.83 0.7 0.114 0.25 0.10 0.01 0.02 0.00
11 55 0.92 0.7 0.114 0.25 0.10 0.01 0.02 0.00
12 60 1.00 0.8 0.131 0.25 0.12 0.01 0.03 0.00
13 65 1.08 0.8 0.131 0.25 0.12 0.01 0.03 0.00
14 70 1.17 0.8 0.131 0.25 0.12 0.01 0.03 0.00
15 75 1.25 0.8 0.131 0.25 0.12 0.01 0.03 0.00
16 80 1.33 0.8 0.131 0.25 0.12 0.01 0.03 0.00
17 85 1.42 0.8 0.131 0.25 0.12 0.01 0.03 0.00
18 90 1.50 0.8 0.131 0.25 0.12 0.01 0.03 0.00
19 95 1.58 0.8 0.131 0.25 0.12 0.01 0.03 0.00
20 100 1.67 0.8 0.131 0.25 0.12 0.01 0.03 0.00
21 105 1.75 0.8 0.131 0.25 0.12 0.01 0.03 0.00
22 110 1.83 0.8 0.131 0.25 0.12 0.01 0.03 0.00
23 115 1.92 0.8 0.131 0.25 0.12 0.01 0.03 0.00
24 120 2.00 0.9 0.147 0.25 0.13 0.01 0.03 0.00
25 125 2.08 0.8 0.131 0.25 0.12 0.01 0.03 0.00
26 130 2.17 0.9 0.147 0.25 0.13 0.01 0.03 0.00
27 135 2.25 0.9 0.147 0.25 0.13 0.01 0.03 0.00
28 140 2.33 0.9 0.147 0.25 0.13 0.01 0.03 0.00
29 145 2.42 0.9 0.147 0.25 0.13 0.01 0.03 0.00
30 150 2.50 0.9 0.147 0.25 0.13 0.01 0.03 0.00
31 155 2.58 0.9 0.147 0.25 0.13 0.01 0.03 0.00
32 160 2.67 0.9 0.147 0.25 0.13 0.01 0.03 0.00
33 165 2.75 1.0 0.163 0.25 0.15 0.02 0.03 0.00
34 170 2.83 1.0 0.163 0.25 0.15 0.02 0.03 0.00
35 175 2.92 1.0 0.163 0.25 0.15 0.02 0.03 0.00
36 180 3.00 1.0 0.163 0.25 0.15 0.02 0.03 0.00
37 185 3.08 1.0 0.163 0.25 0.15 0.02 0.03 0.00
38 190 3.17 1.1 0.180 0.25 0.16 0.02 0.04 0.00
39 195 3.25 1.1 0.180 0.25 0.16 0.02 0.04 0.00
40 200 3.33 1.1 0.180 0.25 0.16 0.02 0.04 0.00
41 205 3.42 1.2 0.196 0.25 0.18 0.02 0.04 0.00
42 210 3.50 1.3 0.212 0.25 0.19 0.02 0.04 0.00
43 215 3.58 1.4 0.228 0.25 0.21 0.02 0.05 0.00
44 220 3.67 1.4 0.228 0.25 0.21 0.02 0.05 0.00
45 225 3.75 1.5 0.245 0.25 0.22 0.02 0.05 0.69
46 230 3.83 1.5 0.245 0.25 0.22 0.02 0.05 0.69
47 235 3.92 1.6 0.261 0.25 0.24 0.02 0.03 0.00
48 240 4.00 1.6 0.261 0.25 0.24 0.02 0.03 0.00
49 245 4.08 1.7 0.277 0.25 0.25 0.03 0.06 5.33
50 250 4.17 1.8 0.294 0.25 0.26 0.05 0.10 15.17
51 255 4.25 1.9 0.310 0.25 0.28 0.06 0.13 25.02
52 260 4.33 2.0 0.326 0.25 0.29 0.08 0.16 34.86
53 265 4.42 2.1 0.343 0.25 0.31 0.10 0.20 44.70
54 270 4.50 2.1 0.343 0.25 0.31 0.10 0.20 44.70
55 275 4.58 2.2 0.359 0.25 0.32 0.11 0.23 54.54
56 280 4.67 2.3 0.375 0.25 0.34 0.13 0.26 64.38

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.392 0.25 0.35 0.15 0.29 74.22
58 290 4.83 2.4 0.392 0.25 0.35 0.15 0.29 74.22
59 295 4.92 2.5 0.408 0.25 0.37 0.16 0.33 84.06
60 300 5.00 2.6 0.424 0.25 0.38 0.18 0.36 93.90
61 305 5.08 3.1 0.506 0.25 0.46 0.26 0.52 143.11
62 310 5.17 3.6 0.588 0.25 0.53 0.34 0.69 192.31
63 315 5.25 3.9 0.636 0.25 0.57 0.39 0.79 221.83
64 320 5.33 4.2 0.685 0.25 0.62 0.44 0.88 251.36
65 325 5.42 4.7 0.767 0.25 0.69 0.52 1.05 300.56
66 330 5.50 5.6 0.914 0.25 0.82 0.67 1.34 389.13
67 335 5.58 1.9 0.310 0.25 0.28 0.06 0.13 25.02
68 340 5.67 0.9 0.147 0.25 0.13 0.01 0.03 0.00
69 345 5.75 0.6 0.098 0.25 0.09 0.01 0.02 0.00
70 350 5.83 0.5 0.082 0.25 0.07 0.01 0.02 0.00
71 355 5.92 0.3 0.049 0.25 0.04 0.00 0.01 0.00
72 360 6.00 0.2 0.033 0.25 0.03 0.00 0.01 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.39
FLOOD VOLUME (acft) 0.07
FLOOD VOLUME (cuft) 2879.82
REQUIRED STORAGE (acft) 0.05
REQUIRED STORAGE (cuft) 2139.79
PEAK FLOW RATE (cfs) 1.34
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 2.010 CONSTANT LOSS RATE-in/hr n/a
UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.2453 LAG TIME - MINUTES 1.00 MINIMUM LOSS RATE (for var. loss) - in/hr 0.123 UNIT TIME-PERCENT OF LAG 1507.5 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 2.23 C 0.00227
PERCOLATION RATE (cfs) 0.05
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.018 0.433 0.016 0.002 0.00 0.00
2 30 0.50 0.3 0.027 0.428 0.024 0.003 0.01 0.00
3 45 0.75 0.3 0.027 0.423 0.024 0.003 0.01 0.00
4 60 1.00 0.4 0.036 0.418 0.032 0.004 0.01 0.00
5 75 1.25 0.3 0.027 0.413 0.024 0.003 0.01 0.00
6 90 1.50 0.3 0.027 0.408 0.024 0.003 0.01 0.00
7 105 1.75 0.3 0.027 0.403 0.024 0.003 0.01 0.00
8 120 2.00 0.4 0.036 0.399 0.032 0.004 0.01 0.00
9 135 2.25 0.4 0.036 0.394 0.032 0.004 0.01 0.00
10 150 2.50 0.4 0.036 0.389 0.032 0.004 0.01 0.00
11 165 2.75 0.5 0.045 0.384 0.040 0.004 0.01 0.00
12 180 3.00 0.5 0.045 0.379 0.040 0.004 0.01 0.00
13 195 3.25 0.5 0.045 0.375 0.040 0.004 0.01 0.00
14 210 3.50 0.5 0.045 0.370 0.040 0.004 0.01 0.00
15 225 3.75 0.5 0.045 0.365 0.040 0.004 0.01 0.00
16 240 4.00 0.6 0.054 0.361 0.048 0.005 0.01 0.00
17 255 4.25 0.6 0.054 0.356 0.048 0.005 0.01 0.00
18 270 4.50 0.7 0.062 0.352 0.056 0.006 0.01 0.00
19 285 4.75 0.7 0.062 0.347 0.056 0.006 0.01 0.00
20 300 5.00 0.8 0.071 0.343 0.064 0.007 0.01 0.00
21 315 5.25 0.6 0.054 0.338 0.048 0.005 0.01 0.00
22 330 5.50 0.7 0.062 0.334 0.056 0.006 0.01 0.00
23 345 5.75 0.8 0.071 0.330 0.064 0.007 0.01 0.00
24 360 6.00 0.8 0.071 0.325 0.064 0.007 0.01 0.00
25 375 6.25 0.9 0.080 0.321 0.072 0.008 0.02 0.00
26 390 6.50 0.9 0.080 0.317 0.072 0.008 0.02 0.00
27 405 6.75 1.0 0.089 0.312 0.080 0.009 0.02 0.00
28 420 7.00 1.0 0.089 0.308 0.080 0.009 0.02 0.00
29 435 7.25 1.0 0.089 0.304 0.080 0.009 0.02 0.00
30 450 7.50 1.1 0.098 0.300 0.088 0.010 0.02 0.00
31 465 7.75 1.2 0.107 0.296 0.096 0.011 0.02 0.00
32 480 8.00 1.3 0.116 0.292 0.104 0.012 0.02 0.00
33 495 8.25 1.5 0.134 0.288 0.120 0.013 0.03 0.00
34 510 8.50 1.5 0.134 0.284 0.120 0.013 0.03 0.00
35 525 8.75 1.6 0.143 0.280 0.128 0.014 0.03 0.00
36 540 9.00 1.7 0.152 0.276 0.136 0.015 0.03 0.00
37 555 9.25 1.9 0.169 0.272 0.153 0.017 0.03 0.00
38 570 9.50 2.0 0.178 0.268 0.161 0.018 0.04 0.00
39 585 9.75 2.1 0.187 0.264 0.169 0.019 0.04 0.00
40 600 10.00 2.2 0.196 0.260 0.177 0.020 0.04 0.00
41 615 10.25 1.5 0.134 0.256 0.120 0.013 0.03 0.00
42 630 10.50 1.5 0.134 0.253 0.120 0.013 0.03 0.00
43 645 10.75 2.0 0.178 0.249 0.161 0.018 0.04 0.00
44 660 11.00 2.0 0.178 0.245 0.161 0.018 0.04 0.00
45 675 11.25 1.9 0.169 0.242 0.153 0.017 0.03 0.00
46 690 11.50 1.9 0.169 0.238 0.153 0.017 0.03 0.00
47 705 11.75 1.7 0.152 0.235 0.136 0.015 0.03 0.00
48 720 12.00 1.8 0.161 0.231 0.145 0.016 0.03 0.00
49 735 12.25 2.5 0.223 0.228 0.201 0.022 0.04 0.00
50 750 12.50 2.6 0.232 0.224 0.209 0.008 0.02 0.00
51 765 12.75 2.8 0.250 0.221 0.225 0.029 0.06 9.79
52 780 13.00 2.9 0.259 0.218 0.233 0.041 0.08 31.95
53 795 13.25 3.4 0.303 0.214 0.273 0.089 0.18 118.58
54 810 13.50 3.4 0.303 0.211 0.273 0.092 0.19 124.46
55 825 13.75 2.3 0.205 0.208 0.185 0.021 0.04 0.00
56 840 14.00 2.3 0.205 0.205 0.185 0.000 0.00 0.00
57 855 14.25 2.7 0.241 0.202 0.217 0.039 0.08 28.68
58 870 14.50 2.6 0.232 0.199 0.209 0.033 0.07 18.11
59 885 14.75 2.6 0.232 0.196 0.209 0.036 0.07 23.61
60 900 15.00 2.5 0.223 0.193 0.201 0.030 0.06 12.88
61 915 15.25 2.4 0.214 0.190 0.193 0.024 0.05 2.07
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 7 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
62 930 15.50 2.3 0.205 0.187 0.185 0.018 0.04 0.00
63 945 15.75 1.9 0.169 0.184 0.153 0.017 0.03 0.00
64 960 16.00 1.9 0.169 0.181 0.153 0.017 0.03 0.00
65 975 16.25 0.4 0.036 0.178 0.032 0.004 0.01 0.00
66 990 16.50 0.4 0.036 0.176 0.032 0.004 0.01 0.00
67 1005 16.75 0.3 0.027 0.173 0.024 0.003 0.01 0.00
68 1020 17.00 0.3 0.027 0.170 0.024 0.003 0.01 0.00
69 1035 17.25 0.5 0.045 0.168 0.040 0.004 0.01 0.00
70 1050 17.50 0.5 0.045 0.165 0.040 0.004 0.01 0.00
71 1065 17.75 0.5 0.045 0.163 0.040 0.004 0.01 0.00
72 1080 18.00 0.4 0.036 0.160 0.032 0.004 0.01 0.00
73 1095 18.25 0.4 0.036 0.158 0.032 0.004 0.01 0.00
74 1110 18.50 0.4 0.036 0.156 0.032 0.004 0.01 0.00
75 1125 18.75 0.3 0.027 0.153 0.024 0.003 0.01 0.00
76 1140 19.00 0.2 0.018 0.151 0.016 0.002 0.00 0.00
77 1155 19.25 0.3 0.027 0.149 0.024 0.003 0.01 0.00
78 1170 19.50 0.4 0.036 0.147 0.032 0.004 0.01 0.00
79 1185 19.75 0.3 0.027 0.145 0.024 0.003 0.01 0.00
80 1200 20.00 0.2 0.018 0.143 0.016 0.002 0.00 0.00
81 1215 20.25 0.3 0.027 0.141 0.024 0.003 0.01 0.00
82 1230 20.50 0.3 0.027 0.139 0.024 0.003 0.01 0.00
83 1245 20.75 0.3 0.027 0.138 0.024 0.003 0.01 0.00
84 1260 21.00 0.2 0.018 0.136 0.016 0.002 0.00 0.00
85 1275 21.25 0.3 0.027 0.134 0.024 0.003 0.01 0.00
86 1290 21.50 0.2 0.018 0.133 0.016 0.002 0.00 0.00
87 1305 21.75 0.3 0.027 0.131 0.024 0.003 0.01 0.00
88 1320 22.00 0.2 0.018 0.130 0.016 0.002 0.00 0.00
89 1335 22.25 0.3 0.027 0.129 0.024 0.003 0.01 0.00
90 1350 22.50 0.2 0.018 0.127 0.016 0.002 0.00 0.00
91 1365 22.75 0.2 0.018 0.126 0.016 0.002 0.00 0.00
92 1380 23.00 0.2 0.018 0.125 0.016 0.002 0.00 0.00
93 1395 23.25 0.2 0.018 0.124 0.016 0.002 0.00 0.00
94 1410 23.50 0.2 0.018 0.124 0.016 0.002 0.00 0.00
95 1425 23.75 0.2 0.018 0.123 0.016 0.002 0.00 0.00
96 1440 24.00 0.2 0.018 0.123 0.016 0.002 0.00 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.26
FLOOD VOLUME (acft) 0.04
FLOOD VOLUME (cuft) 1902.84
REQUIRED STORAGE (acft) 0.01
REQUIRED STORAGE (cuft) 370.13
PEAK FLOW (cfs) 0.19
Plate E-2.2

Page 8 of 14 ends

Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

INCR TOTAL INCR TOTAL INCR TOTAL
(ft) (ft) (sf) (sf) (cuft) (cuft) (acre-ft)
465 0 0 3025 0 0 0.00
466 1 1 675 3700 3363 3363 0.08
467 1 2 730 4430 4065 7428 0.17
468 1 3 785 5215 4823 12250 0.28
468.5 0.5 3.5 415 5630 2711 14961 0.34

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.05 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.05 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.03 10 10 14 - 465.00 - 0.00
2 10 0.03 10 10 14 - 465.00 - 0.00
3 15 0.03 8 8 14 - 465.00 - 0.00
4 20 0.04 11 11 14 - 465.00 - 0.00
5 25 0.04 11 11 14 - 465.00 - 0.00
6 30 0.05 14 14 14 - 465.00 - 0.00
7 35 0.04 11 11 14 - 465.00 - 0.00
8 40 0.05 14 14 14 - 465.00 - 0.00
9 45 0.05 14 14 14 - 465.00 - 0.00
10 50 0.04 11 11 14 - 465.00 - 0.00
11 55 0.04 12 12 14 - 465.00 - 0.00
12 60 0.05 14 14 14 - 465.00 - 0.00
13 65 0.06 18 18 14 4 465.00 0.00 4
14 70 0.06 18 21 14 7 465.00 0.00 7
15 75 0.06 18 25 14 11 465.00 11 0.00
16 80 0.01 3 13 14 - 465.00 - 0.00
17 85 0.16 48 48 14 34 465.01 34 0.00
18 90 0.18 55 89 14 75 465.02 75 0.00
19 95 0.11 33 108 14 94 465.03 94 0.00
20 100 0.18 55 149 14 135 465.04 135 0.00
21 105 0.33 100 235 14 221 465.07 221 0.01
22 110 0.28 85 307 14 292 465.09 292 0.01
23 115 0.23 70 363 14 349 465.10 349 0.01
24 120 0.26 78 427 14 413 465.12 413 0.01
25 125 0.28 85 498 14 484 465.14 484 0.01
26 130 0.56 168 652 14 638 465.19 638 0.01
27 135 0.76 228 866 14 852 465.25 852 0.02
28 140 0.39 116 968 14 954 465.28 954 0.02
29 145 1.21 364 1,318 14 1,304 465.39 1,304 0.03
30 150 1.34 401 1,705 14 1,691 465.50 1,691 0.04
31 155 1.56 469 2,160 14 2,146 465.64 2,146 0.05
32 160 0.99 296 2,442 14 2,428 465.72 2,428 0.06
33 165 0.01 3 2,431 14 2,417 465.72 2,417 0.06
34 170 0.05 14 2,430 14 2,416 465.72 2,416 0.06
35 175 0.05 14 2,430 14 2,416 465.72 2,416 0.06
36 180 0.02 5 2,420 14 2,406 465.72 2,406 0.06

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.02 5 5 14 - 465.00 - 0.00
2 10 0.02 6 6 14 - 465.00 - 0.00
3 15 0.02 6 6 14 - 465.00 - 0.00
4 20 0.02 6 6 14 - 465.00 - 0.00
5 25 0.02 6 6 14 - 465.00 - 0.00
6 30 0.02 7 7 14 - 465.00 - 0.00
7 35 0.02 7 7 14 - 465.00 - 0.00
8 40 0.02 7 7 14 - 465.00 - 0.00
9 45 0.02 7 7 14 - 465.00 - 0.00
10 50 0.02 7 7 14 - 465.00 - 0.00
11 55 0.02 7 7 14 - 465.00 - 0.00
12 60 0.03 8 8 14 - 465.00 - 0.00
13 65 0.03 8 8 14 - 465.00 - 0.00
14 70 0.03 8 8 14 - 465.00 - 0.00
15 75 0.03 8 8 14 - 465.00 - 0.00
16 80 0.03 8 8 14 - 465.00 - 0.00
17 85 0.03 8 8 14 - 465.00 - 0.00
18 90 0.03 8 8 14 - 465.00 - 0.00
19 95 0.03 8 8 14 - 465.00 - 0.00
20 100 0.03 8 8 14 - 465.00 - 0.00
21 105 0.03 8 8 14 - 465.00 - 0.00
22 110 0.03 8 8 14 - 465.00 - 0.00
23 115 0.03 8 8 14 - 465.00 - 0.00
24 120 0.03 9 9 14 - 465.00 - 0.00
25 125 0.03 8 8 14 - 465.00 - 0.00
26 130 0.03 9 9 14 - 465.00 - 0.00
27 135 0.03 9 9 14 - 465.00 - 0.00
28 140 0.03 9 9 14 - 465.00 - 0.00
29 145 0.03 9 9 14 - 465.00 - 0.00
30 150 0.03 9 9 14 - 465.00 - 0.00
31 155 0.03 9 9 14 - 465.00 - 0.00
32 160 0.03 9 9 14 - 465.00 - 0.00
33 165 0.03 10 10 14 - 465.00 - 0.00
34 170 0.03 10 10 14 - 465.00 - 0.00
35 175 0.03 10 10 14 - 465.00 - 0.00
36 180 0.03 10 10 14 - 465.00 - 0.00
37 185 0.03 10 10 14 - 465.00 - 0.00
38 190 0.04 11 11 14 - 465.00 - 0.00
39 195 0.04 11 11 14 - 465.00 - 0.00
40 200 0.04 11 11 14 - 465.00 - 0.00
41 205 0.04 12 12 14 - 465.00 - 0.00
42 210 0.04 13 13 14 - 465.00 - 0.00
43 215 0.05 14 14 14 - 465.00 - 0.00
44 220 0.05 14 14 14 - 465.00 - 0.00
45 225 0.05 15 15 14 1 465.00 0.00 1
46 230 0.05 15 15 14 1 465.00 0.00 1
47 235 0.03 10 11 14 - 465.00 - 0.00
48 240 0.03 10 10 14 - 465.00 - 0.00
49 245 0.06 19 19 14 5 465.00 0.00 5
50 250 0.10 29 35 14 21 465.01 21 0.00
51 255 0.13 39 60 14 46 465.01 46 0.00
52 260 0.16 49 94 14 80 465.02 80 0.00
53 265 0.20 59 139 14 125 465.04 125 0.00
54 270 0.20 59 184 14 170 465.05 170 0.00
55 275 0.23 69 238 14 224 465.07 224 0.01

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 11 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 0.26 78 303 14 289 465.09 289 0.01
57 285 0.29 88 377 14 363 465.11 363 0.01
58 290 0.29 88 451 14 437 465.13 437 0.01
59 295 0.33 98 535 14 521 465.16 521 0.01
60 300 0.36 108 629 14 615 465.18 615 0.01
61 305 0.52 157 772 14 758 465.23 758 0.02
62 310 0.69 206 965 14 951 465.28 951 0.02
63 315 0.79 236 1,186 14 1,172 465.35 1,172 0.03
64 320 0.88 265 1,438 14 1,424 465.42 1,424 0.03
65 325 1.05 315 1,738 14 1,724 465.51 1,724 0.04
66 330 1.34 403 2,127 14 2,113 465.63 2,113 0.05
67 335 0.13 39 2,152 14 2,138 465.64 2,138 0.05
68 340 0.03 9 2,147 14 2,133 465.63 2,133 0.05
69 345 0.02 6 2,139 14 2,125 465.63 2,125 0.05
70 350 0.02 5 2,130 14 2,116 465.63 2,116 0.05
71 355 0.01 3 2,119 14 2,105 465.63 2,105 0.05
72 360 0.01 2 2,107 14 2,093 465.62 2,093 0.05
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.00 3 3 42 - 465.00 - 0.00
2 30 0.01 5 5 42 - 465.00 - 0.00
3 45 0.01 5 5 42 - 465.00 - 0.00
4 60 0.01 6 6 42 - 465.00 - 0.00
5 75 0.01 5 5 42 - 465.00 - 0.00
6 90 0.01 5 5 42 - 465.00 - 0.00
7 105 0.01 5 5 42 - 465.00 - 0.00
8 120 0.01 6 6 42 - 465.00 - 0.00
9 135 0.01 6 6 42 - 465.00 - 0.00
10 150 0.01 6 6 42 - 465.00 - 0.00
11 165 0.01 8 8 42 - 465.00 - 0.00
12 180 0.01 8 8 42 - 465.00 - 0.00
13 195 0.01 8 8 42 - 465.00 - 0.00
14 210 0.01 8 8 42 - 465.00 - 0.00
15 225 0.01 8 8 42 - 465.00 - 0.00
16 240 0.01 10 10 42 - 465.00 - 0.00
17 255 0.01 10 10 42 - 465.00 - 0.00
18 270 0.01 11 11 42 - 465.00 - 0.00
19 285 0.01 11 11 42 - 465.00 - 0.00
20 300 0.01 13 13 42 - 465.00 - 0.00
21 315 0.01 10 10 42 - 465.00 - 0.00
22 330 0.01 11 11 42 - 465.00 - 0.00
23 345 0.01 13 13 42 - 465.00 - 0.00
24 360 0.01 13 13 42 - 465.00 - 0.00
25 375 0.02 15 15 42 - 465.00 - 0.00
26 390 0.02 15 15 42 - 465.00 - 0.00
27 405 0.02 16 16 42 - 465.00 - 0.00
28 420 0.02 16 16 42 - 465.00 - 0.00
29 435 0.02 16 16 42 - 465.00 - 0.00
30 450 0.02 18 18 42 - 465.00 - 0.00
31 465 0.02 19 19 42 - 465.00 - 0.00
32 480 0.02 21 21 42 - 465.00 - 0.00
33 495 0.03 24 24 42 - 465.00 - 0.00
34 510 0.03 24 24 42 - 465.00 - 0.00
35 525 0.03 26 26 42 - 465.00 - 0.00
36 540 0.03 27 27 42 - 465.00 - 0.00
37 555 0.03 31 31 42 - 465.00 - 0.00
38 570 0.04 32 32 42 - 465.00 - 0.00
39 585 0.04 34 34 42 - 465.00 - 0.00
40 600 0.04 35 35 42 - 465.00 - 0.00
41 615 0.03 24 24 42 - 465.00 - 0.00
42 630 0.03 24 24 42 - 465.00 - 0.00
43 645 0.04 32 32 42 - 465.00 - 0.00
44 660 0.04 32 32 42 - 465.00 - 0.00
45 675 0.03 31 31 42 - 465.00 - 0.00
46 690 0.03 31 31 42 - 465.00 - 0.00
47 705 0.03 27 27 42 - 465.00 - 0.00
48 720 0.03 29 29 42 - 465.00 - 0.00
49 735 0.04 40 40 42 - 465.00 - 0.00
50 750 0.02 14 14 42 - 465.00 - 0.00
51 765 0.06 52 52 42 10 465.00 10 0.00
52 780 0.08 74 84 42 42 465.01 42 0.00
53 795 0.18 161 203 42 160 465.05 160 0.00
54 810 0.19 167 327 42 285 465.08 285 0.01
55 825 0.04 37 322 42 280 465.08 280 0.01
56 840 0.00 1 280 42 238 465.07 238 0.01
57 855 0.08 71 309 42 267 465.08 267 0.01
58 870 0.07 60 327 42 285 465.08 285 0.01

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 0.07 66 351 42 309 465.09 309 0.01
60 900 0.06 55 364 42 321 465.10 321 0.01
61 915 0.05 44 366 42 324 465.10 324 0.01
62 930 0.04 33 357 42 315 465.09 315 0.01
63 945 0.03 31 345 42 303 465.09 303 0.01
64 960 0.03 31 334 42 292 465.09 292 0.01
65 975 0.01 6 298 42 256 465.08 256 0.01
66 990 0.01 6 262 42 220 465.07 220 0.01
67 1005 0.01 5 225 42 183 465.05 183 0.00
68 1020 0.01 5 187 42 145 465.04 145 0.00
69 1035 0.01 8 153 42 111 465.03 111 0.00
70 1050 0.01 8 119 42 77 465.02 77 0.00
71 1065 0.01 8 85 42 43 465.01 43 0.00
72 1080 0.01 6 49 42 7 465.00 7 0.00
73 1095 0.01 6 13 42 - 465.00 - 0.00
74 1110 0.01 6 6 42 - 465.00 - 0.00
75 1125 0.01 5 5 42 - 465.00 - 0.00
76 1140 0.00 3 3 42 - 465.00 - 0.00
77 1155 0.01 5 5 42 - 465.00 - 0.00
78 1170 0.01 6 6 42 - 465.00 - 0.00
79 1185 0.01 5 5 42 - 465.00 - 0.00
80 1200 0.00 3 3 42 - 465.00 - 0.00
81 1215 0.01 5 5 42 - 465.00 - 0.00
82 1230 0.01 5 5 42 - 465.00 - 0.00
83 1245 0.01 5 5 42 - 465.00 - 0.00
84 1260 0.00 3 3 42 - 465.00 - 0.00
85 1275 0.01 5 5 42 - 465.00 - 0.00
86 1290 0.00 3 3 42 - 465.00 - 0.00
87 1305 0.01 5 5 42 - 465.00 - 0.00
88 1320 0.00 3 3 42 - 465.00 - 0.00
89 1335 0.01 5 5 42 - 465.00 - 0.00
90 1350 0.00 3 3 42 - 465.00 - 0.00
91 1365 0.00 3 3 42 - 465.00 - 0.00
92 1380 0.00 3 3 42 - 465.00 - 0.00
93 1395 0.00 3 3 42 - 465.00 - 0.00
94 1410 0.00 3 3 42 - 465.00 - 0.00
95 1425 0.00 3 3 42 - 465.00 - 0.00
96 1440 0.00 3 3 42 - 465.00 - 0.00
Basin Depth Analysis

Page 14 of 14 ends

Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 2

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 2.51
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE
MF - CONDOMINIUMS 7.46

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 0.6

RETENTION BASIN

GOLF COURSE

MOUNTAINOUS
LOW LOSS RATE (PERCENT) 90%
LENGTH OF WATERCOURSE (L) 724
LENGTH TO POINT OPPOSITE CENTROID (Lca) 100
ELEVATION OF HEADWATER 472
ELEVATION OF CONCENTRATION POINT 468.5
AVERAGE MANNINGS 'N' VALUE 0.02
STORM FREQUENCY (YEAR) 100

POINT RAIN
3-HOUR 1.04
6-HOUR 1.36
24-HOUR 2.23
BASIN CHARACTERISTICS: ELEVATION AREA
465 15600
466 17120
467 18710
468 20350
468.5 21200
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
815
Item 2.

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

1.04 10.570 1.00 1.04 1.36 10.570 1.00 1.36 2.23 10.570 1.00 2.23

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 10.57 SUM [7] 1.04 SUM [9] 10.57 SUM [11] 1.36 SUM [13] 10.57 SUM [15] 2.23 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 1.04 1.36 2.23
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 0.49 0.49 0.40
FLOOD VOLUME (cu-ft) 18,821 18,747 15,460
(acre-ft) 0.43 0.43 0.35
REQUIRED STORAGE (cu-ft) 16,281 14,878 6,850
(acre-ft) 0.37 0.34 0.16
PEAK FLOW (cfs) 8.76 7.61 1.44
MAXIMUM WSEL (ft) 465.99 465.91 465.42
24-HOURS
[15] LAG TIME-HOURS
[16] LAG TIME-MINUTES

0.24 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS 6-HOURS
[6] La-FEET
[7] La-MILES
[8] ELEVATION OF HEADWATER
[9] ELEVATION OF CONCENTRATION POINT
[2] AREA DESIGNATION
[3] AREA - ACRES
[4] L-FEET
[5] L-MILES
5 0.03

1.6 1.6

3.2 25.5

5.05 0.02

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 2

10.570
724

0.019
472
468.5

0.137
100.00

0.001
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 3.5
[11] S-FEET/MILE
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 10 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

RATE IMPERVIOUS RATE
(in/hr) (in/hr) (in/hr)
[Plate C-1] [Plate E-6.1] [Plate E-6.2] [Plate E-6.3]
B 56 0.52 90% 0.10 0.00 0.000 0.0000
B 56 0.52 100% 0.05 2.51 0.237 0.0123
B 56 0.52 20% 0.43 0.00 0.000 0.0000B 56 0.52 40% 0.33 0.00 0.000 0.0000B 56 0.52 50% 0.29 0.00 0.000 0.0000B 56 0.52 65% 0.22 7.46 0.706 0.1523B 56 0.52 80% 0.15 0.00 0.000 0.0000B 56 0.52 75% 0.17 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.60 0.057 0.0295B 56 0.52 0% 0.52 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.00 0.000 0.0000 D 93 0.95 90% 0.18 0.00 0.000 0.0000

0.00 0.000 0.0000

0.00 0.000 0.0000
SUM 10.57 SUM 0.1942
VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY)Fm= 0.097085525C= 0.00180Ft=C(24-(T/60))^1.55 = 0.00180 0.10 in/hr LOW LOSS RATE (80-90 PERCENT) = 90%Where:T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,T=1 1/2 unit time for the second period, etc.

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS
(24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 10.57
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.62
UNIT TIME-PERCENT OF LAG 308.6
TOTAL ADJUSTED STORM RAIN-INCHES 1.04
CONSTANT LOSS RATE-in/hr 0.19
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.24 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.162 0.19 0.15 0.02 0.17 0.00
2 10 0.17 1.3 0.162 0.19 0.15 0.02 0.17 0.00
3 15 0.25 1.1 0.137 0.19 0.12 0.01 0.15 0.00
4 20 0.33 1.5 0.187 0.19 0.17 0.02 0.20 0.00
5 25 0.42 1.5 0.187 0.19 0.17 0.02 0.20 0.00
6 30 0.50 1.8 0.225 0.19 0.20 0.03 0.32 24.03
7 35 0.58 1.5 0.187 0.19 0.17 0.02 0.20 0.00
8 40 0.67 1.8 0.225 0.19 0.20 0.03 0.32 24.03
9 45 0.75 1.8 0.225 0.19 0.20 0.03 0.32 24.03
10 50 0.83 1.5 0.187 0.19 0.17 0.02 0.20 0.00
11 55 0.92 1.6 0.200 0.19 0.18 0.01 0.06 0.00
12 60 1.00 1.8 0.225 0.19 0.20 0.03 0.32 24.03
13 65 1.08 2.2 0.275 0.19 0.25 0.08 0.85 182.33
14 70 1.17 2.2 0.275 0.19 0.25 0.08 0.85 182.33
15 75 1.25 2.2 0.275 0.19 0.25 0.08 0.85 182.33
16 80 1.33 2.0 0.250 0.19 0.22 0.06 0.59 103.18
17 85 1.42 2.6 0.324 0.19 0.29 0.13 1.38 340.63
18 90 1.50 2.7 0.337 0.19 0.30 0.14 1.51 380.20
19 95 1.58 2.4 0.300 0.19 0.27 0.11 1.11 261.48
20 100 1.67 2.7 0.337 0.19 0.30 0.14 1.51 380.20
21 105 1.75 3.3 0.412 0.19 0.37 0.22 2.30 617.64
22 110 1.83 3.1 0.387 0.19 0.35 0.19 2.04 538.50
23 115 1.92 2.9 0.362 0.19 0.33 0.17 1.77 459.35
24 120 2.00 3.0 0.374 0.19 0.34 0.18 1.91 498.92
25 125 2.08 3.1 0.387 0.19 0.35 0.19 2.04 538.50
26 130 2.17 4.2 0.524 0.19 0.47 0.33 3.49 973.81
27 135 2.25 5.0 0.624 0.19 0.56 0.43 4.54 1290.40
28 140 2.33 3.5 0.437 0.19 0.39 0.24 2.56 696.79
29 145 2.42 6.8 0.849 0.19 0.76 0.65 6.92 2002.74
30 150 2.50 7.3 0.911 0.19 0.82 0.72 7.58 2200.61
31 155 2.58 8.2 1.023 0.19 0.92 0.83 8.76 2556.77
32 160 2.67 5.9 0.736 0.19 0.66 0.54 5.73 1646.57
33 165 2.75 2.0 0.250 0.19 0.22 0.06 0.59 103.18
34 170 2.83 1.8 0.225 0.19 0.20 0.03 0.32 24.03
35 175 2.92 1.8 0.225 0.19 0.20 0.03 0.32 24.03
36 180 3.00 0.6 0.075 0.19 0.07 0.01 0.08 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.49
FLOOD VOLUME (acft) 0.43
FLOOD VOLUME (cuft) 18821.12
REQUIRED STORAGE (acft) 0.37
REQUIRED STORAGE (cuft) 16280.67
PEAK FLOW RATE (cfs) 8.76
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 10.57
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.62
UNIT TIME-PERCENT OF LAG 308.6
TOTAL ADJUSTED STORM RAIN-INCHES 1.36
CONSTANT LOSS RATE-in/hr 0.194
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.24 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.082 0.19 0.07 0.01 0.09 0.00
2 10 0.17 0.6 0.098 0.19 0.09 0.01 0.10 0.00
3 15 0.25 0.6 0.098 0.19 0.09 0.01 0.10 0.00
4 20 0.33 0.6 0.098 0.19 0.09 0.01 0.10 0.00
5 25 0.42 0.6 0.098 0.19 0.09 0.01 0.10 0.00
6 30 0.50 0.7 0.114 0.19 0.10 0.01 0.12 0.00
7 35 0.58 0.7 0.114 0.19 0.10 0.01 0.12 0.00
8 40 0.67 0.7 0.114 0.19 0.10 0.01 0.12 0.00
9 45 0.75 0.7 0.114 0.19 0.10 0.01 0.12 0.00
10 50 0.83 0.7 0.114 0.19 0.10 0.01 0.12 0.00
11 55 0.92 0.7 0.114 0.19 0.10 0.01 0.12 0.00
12 60 1.00 0.8 0.131 0.19 0.12 0.01 0.14 0.00
13 65 1.08 0.8 0.131 0.19 0.12 0.01 0.14 0.00
14 70 1.17 0.8 0.131 0.19 0.12 0.01 0.14 0.00
15 75 1.25 0.8 0.131 0.19 0.12 0.01 0.14 0.00
16 80 1.33 0.8 0.131 0.19 0.12 0.01 0.14 0.00
17 85 1.42 0.8 0.131 0.19 0.12 0.01 0.14 0.00
18 90 1.50 0.8 0.131 0.19 0.12 0.01 0.14 0.00
19 95 1.58 0.8 0.131 0.19 0.12 0.01 0.14 0.00
20 100 1.67 0.8 0.131 0.19 0.12 0.01 0.14 0.00
21 105 1.75 0.8 0.131 0.19 0.12 0.01 0.14 0.00
22 110 1.83 0.8 0.131 0.19 0.12 0.01 0.14 0.00
23 115 1.92 0.8 0.131 0.19 0.12 0.01 0.14 0.00
24 120 2.00 0.9 0.147 0.19 0.13 0.01 0.16 0.00
25 125 2.08 0.8 0.131 0.19 0.12 0.01 0.14 0.00
26 130 2.17 0.9 0.147 0.19 0.13 0.01 0.16 0.00
27 135 2.25 0.9 0.147 0.19 0.13 0.01 0.16 0.00
28 140 2.33 0.9 0.147 0.19 0.13 0.01 0.16 0.00
29 145 2.42 0.9 0.147 0.19 0.13 0.01 0.16 0.00
30 150 2.50 0.9 0.147 0.19 0.13 0.01 0.16 0.00
31 155 2.58 0.9 0.147 0.19 0.13 0.01 0.16 0.00
32 160 2.67 0.9 0.147 0.19 0.13 0.01 0.16 0.00
33 165 2.75 1.0 0.163 0.19 0.15 0.02 0.17 0.00
34 170 2.83 1.0 0.163 0.19 0.15 0.02 0.17 0.00
35 175 2.92 1.0 0.163 0.19 0.15 0.02 0.17 0.00
36 180 3.00 1.0 0.163 0.19 0.15 0.02 0.17 0.00
37 185 3.08 1.0 0.163 0.19 0.15 0.02 0.17 0.00
38 190 3.17 1.1 0.180 0.19 0.16 0.02 0.19 0.00
39 195 3.25 1.1 0.180 0.19 0.16 0.02 0.19 0.00
40 200 3.33 1.1 0.180 0.19 0.16 0.02 0.19 0.00
41 205 3.42 1.2 0.196 0.19 0.18 0.00 0.02 0.00
42 210 3.50 1.3 0.212 0.19 0.19 0.02 0.19 0.00
43 215 3.58 1.4 0.228 0.19 0.21 0.03 0.36 36.21
44 220 3.67 1.4 0.228 0.19 0.21 0.03 0.36 36.21
45 225 3.75 1.5 0.245 0.19 0.22 0.05 0.54 87.96
46 230 3.83 1.5 0.245 0.19 0.22 0.05 0.54 87.96
47 235 3.92 1.6 0.261 0.19 0.24 0.07 0.71 139.71
48 240 4.00 1.6 0.261 0.19 0.24 0.07 0.71 139.71
49 245 4.08 1.7 0.277 0.19 0.25 0.08 0.88 191.46
50 250 4.17 1.8 0.294 0.19 0.26 0.10 1.05 243.21
51 255 4.25 1.9 0.310 0.19 0.28 0.12 1.23 294.96
52 260 4.33 2.0 0.326 0.19 0.29 0.13 1.40 346.71
53 265 4.42 2.1 0.343 0.19 0.31 0.15 1.57 398.47
54 270 4.50 2.1 0.343 0.19 0.31 0.15 1.57 398.47
55 275 4.58 2.2 0.359 0.19 0.32 0.16 1.74 450.22
56 280 4.67 2.3 0.375 0.19 0.34 0.18 1.92 501.97

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.392 0.19 0.35 0.20 2.09 553.72
58 290 4.83 2.4 0.392 0.19 0.35 0.20 2.09 553.72
59 295 4.92 2.5 0.408 0.19 0.37 0.21 2.26 605.47
60 300 5.00 2.6 0.424 0.19 0.38 0.23 2.43 657.22
61 305 5.08 3.1 0.506 0.19 0.46 0.31 3.30 915.97
62 310 5.17 3.6 0.588 0.19 0.53 0.39 4.16 1174.73
63 315 5.25 3.9 0.636 0.19 0.57 0.44 4.68 1329.98
64 320 5.33 4.2 0.685 0.19 0.62 0.49 5.19 1485.23
65 325 5.42 4.7 0.767 0.19 0.69 0.57 6.06 1743.98
66 330 5.50 5.6 0.914 0.19 0.82 0.72 7.61 2209.74
67 335 5.58 1.9 0.310 0.19 0.28 0.12 1.23 294.96
68 340 5.67 0.9 0.147 0.19 0.13 0.01 0.16 0.00
69 345 5.75 0.6 0.098 0.19 0.09 0.01 0.10 0.00
70 350 5.83 0.5 0.082 0.19 0.07 0.01 0.09 0.00
71 355 5.92 0.3 0.049 0.19 0.04 0.00 0.05 0.00
72 360 6.00 0.2 0.033 0.19 0.03 0.00 0.03 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.49
FLOOD VOLUME (acft) 0.43
FLOOD VOLUME (cuft) 18747.03
REQUIRED STORAGE (acft) 0.34
REQUIRED STORAGE (cuft) 14877.95
PEAK FLOW RATE (cfs) 7.61
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 10.570 CONSTANT LOSS RATE-in/hr n/a UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.1942 LAG TIME - MINUTES 1.62 MINIMUM LOSS RATE (for var. loss) - in/hr 0.097 UNIT TIME-PERCENT OF LAG 925.8 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 2.23 C 0.00180
PERCOLATION RATE (cfs) 0.24
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.018 0.343 0.016 0.002 0.02 0.00
2 30 0.50 0.3 0.027 0.339 0.024 0.003 0.03 0.00
3 45 0.75 0.3 0.027 0.335 0.024 0.003 0.03 0.00
4 60 1.00 0.4 0.036 0.331 0.032 0.004 0.04 0.00
5 75 1.25 0.3 0.027 0.327 0.024 0.003 0.03 0.00
6 90 1.50 0.3 0.027 0.323 0.024 0.003 0.03 0.00
7 105 1.75 0.3 0.027 0.319 0.024 0.003 0.03 0.00
8 120 2.00 0.4 0.036 0.316 0.032 0.004 0.04 0.00
9 135 2.25 0.4 0.036 0.312 0.032 0.004 0.04 0.00
10 150 2.50 0.4 0.036 0.308 0.032 0.004 0.04 0.00
11 165 2.75 0.5 0.045 0.304 0.040 0.004 0.05 0.00
12 180 3.00 0.5 0.045 0.300 0.040 0.004 0.05 0.00
13 195 3.25 0.5 0.045 0.297 0.040 0.004 0.05 0.00
14 210 3.50 0.5 0.045 0.293 0.040 0.004 0.05 0.00
15 225 3.75 0.5 0.045 0.289 0.040 0.004 0.05 0.00
16 240 4.00 0.6 0.054 0.286 0.048 0.005 0.06 0.00
17 255 4.25 0.6 0.054 0.282 0.048 0.005 0.06 0.00
18 270 4.50 0.7 0.062 0.278 0.056 0.006 0.07 0.00
19 285 4.75 0.7 0.062 0.275 0.056 0.006 0.07 0.00
20 300 5.00 0.8 0.071 0.271 0.064 0.007 0.08 0.00
21 315 5.25 0.6 0.054 0.268 0.048 0.005 0.06 0.00
22 330 5.50 0.7 0.062 0.264 0.056 0.006 0.07 0.00
23 345 5.75 0.8 0.071 0.261 0.064 0.007 0.08 0.00
24 360 6.00 0.8 0.071 0.257 0.064 0.007 0.08 0.00
25 375 6.25 0.9 0.080 0.254 0.072 0.008 0.08 0.00
26 390 6.50 0.9 0.080 0.251 0.072 0.008 0.08 0.00
27 405 6.75 1.0 0.089 0.247 0.080 0.009 0.09 0.00
28 420 7.00 1.0 0.089 0.244 0.080 0.009 0.09 0.00
29 435 7.25 1.0 0.089 0.241 0.080 0.009 0.09 0.00
30 450 7.50 1.1 0.098 0.237 0.088 0.010 0.10 0.00
31 465 7.75 1.2 0.107 0.234 0.096 0.011 0.11 0.00
32 480 8.00 1.3 0.116 0.231 0.104 0.012 0.12 0.00
33 495 8.25 1.5 0.134 0.228 0.120 0.013 0.14 0.00
34 510 8.50 1.5 0.134 0.224 0.120 0.013 0.14 0.00
35 525 8.75 1.6 0.143 0.221 0.128 0.014 0.15 0.00
36 540 9.00 1.7 0.152 0.218 0.136 0.015 0.16 0.00
37 555 9.25 1.9 0.169 0.215 0.153 0.017 0.18 0.00
38 570 9.50 2.0 0.178 0.212 0.161 0.018 0.19 0.00
39 585 9.75 2.1 0.187 0.209 0.169 0.019 0.20 0.00
40 600 10.00 2.2 0.196 0.206 0.177 0.020 0.21 0.00
41 615 10.25 1.5 0.134 0.203 0.120 0.013 0.14 0.00
42 630 10.50 1.5 0.134 0.200 0.120 0.013 0.14 0.00
43 645 10.75 2.0 0.178 0.197 0.161 0.018 0.19 0.00
44 660 11.00 2.0 0.178 0.194 0.161 0.018 0.19 0.00
45 675 11.25 1.9 0.169 0.191 0.153 0.017 0.18 0.00
46 690 11.50 1.9 0.169 0.189 0.153 0.017 0.18 0.00
47 705 11.75 1.7 0.152 0.186 0.136 0.015 0.16 0.00
48 720 12.00 1.8 0.161 0.183 0.145 0.016 0.17 0.00
49 735 12.25 2.5 0.223 0.180 0.201 0.043 0.45 188.01
50 750 12.50 2.6 0.232 0.178 0.209 0.054 0.57 298.56
51 765 12.75 2.8 0.250 0.175 0.225 0.075 0.79 493.67
52 780 13.00 2.9 0.259 0.172 0.233 0.086 0.91 603.61
53 795 13.25 3.4 0.303 0.170 0.273 0.134 1.41 1052.67
54 810 13.50 3.4 0.303 0.167 0.273 0.136 1.44 1077.14
55 825 13.75 2.3 0.205 0.165 0.185 0.041 0.43 167.88
56 840 14.00 2.3 0.205 0.162 0.185 0.043 0.45 191.72
57 855 14.25 2.7 0.241 0.160 0.217 0.081 0.86 554.66
58 870 14.50 2.6 0.232 0.157 0.209 0.075 0.79 492.99
59 885 14.75 2.6 0.232 0.155 0.209 0.077 0.82 515.85
60 900 15.00 2.5 0.223 0.152 0.201 0.071 0.75 453.52
61 915 15.25 2.4 0.214 0.150 0.193 0.064 0.68 390.86
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

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Item 2.

EFFECTIVE RAIN CALCULATION FORM
62 930 15.50 2.3 0.205 0.148 0.185 0.057 0.61 327.85
63 945 15.75 1.9 0.169 0.146 0.153 0.024 0.25 9.93
64 960 16.00 1.9 0.169 0.143 0.153 0.026 0.28 31.09
65 975 16.25 0.4 0.036 0.141 0.032 0.004 0.04 0.00
66 990 16.50 0.4 0.036 0.139 0.032 0.004 0.04 0.00
67 1005 16.75 0.3 0.027 0.137 0.024 0.003 0.03 0.00
68 1020 17.00 0.3 0.027 0.135 0.024 0.003 0.03 0.00
69 1035 17.25 0.5 0.045 0.133 0.040 0.004 0.05 0.00
70 1050 17.50 0.5 0.045 0.131 0.040 0.004 0.05 0.00
71 1065 17.75 0.5 0.045 0.129 0.040 0.004 0.05 0.00
72 1080 18.00 0.4 0.036 0.127 0.032 0.004 0.04 0.00
73 1095 18.25 0.4 0.036 0.125 0.032 0.004 0.04 0.00
74 1110 18.50 0.4 0.036 0.123 0.032 0.004 0.04 0.00
75 1125 18.75 0.3 0.027 0.121 0.024 0.003 0.03 0.00
76 1140 19.00 0.2 0.018 0.120 0.016 0.002 0.02 0.00
77 1155 19.25 0.3 0.027 0.118 0.024 0.003 0.03 0.00
78 1170 19.50 0.4 0.036 0.116 0.032 0.004 0.04 0.00
79 1185 19.75 0.3 0.027 0.115 0.024 0.003 0.03 0.00
80 1200 20.00 0.2 0.018 0.113 0.016 0.002 0.02 0.00
81 1215 20.25 0.3 0.027 0.112 0.024 0.003 0.03 0.00
82 1230 20.50 0.3 0.027 0.110 0.024 0.003 0.03 0.00
83 1245 20.75 0.3 0.027 0.109 0.024 0.003 0.03 0.00
84 1260 21.00 0.2 0.018 0.108 0.016 0.002 0.02 0.00
85 1275 21.25 0.3 0.027 0.106 0.024 0.003 0.03 0.00
86 1290 21.50 0.2 0.018 0.105 0.016 0.002 0.02 0.00
87 1305 21.75 0.3 0.027 0.104 0.024 0.003 0.03 0.00
88 1320 22.00 0.2 0.018 0.103 0.016 0.002 0.02 0.00
89 1335 22.25 0.3 0.027 0.102 0.024 0.003 0.03 0.00
90 1350 22.50 0.2 0.018 0.101 0.016 0.002 0.02 0.00
91 1365 22.75 0.2 0.018 0.100 0.016 0.002 0.02 0.00
92 1380 23.00 0.2 0.018 0.099 0.016 0.002 0.02 0.00
93 1395 23.25 0.2 0.018 0.099 0.016 0.002 0.02 0.00
94 1410 23.50 0.2 0.018 0.098 0.016 0.002 0.02 0.00
95 1425 23.75 0.2 0.018 0.097 0.016 0.002 0.02 0.00
96 1440 24.00 0.2 0.018 0.097 0.016 0.002 0.02 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.40
FLOOD VOLUME (acft) 0.35
FLOOD VOLUME (cuft) 15459.88
REQUIRED STORAGE (acft) 0.16
REQUIRED STORAGE (cuft) 6850.04
PEAK FLOW (cfs) 1.44
Plate E-2.2

Page 8 of 14 ends

Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.24 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.24 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.17 51 51 73 - 465.00 - 0.00
2 10 0.17 51 51 73 - 465.00 - 0.00
3 15 0.15 44 44 73 - 465.00 - 0.00
4 20 0.20 59 59 73 - 465.00 - 0.00
5 25 0.20 59 59 73 - 465.00 - 0.00
6 30 0.32 97 97 73 24 465.00 24 0.00
7 35 0.20 59 83 73 11 465.00 11 0.00
8 40 0.32 97 107 73 35 465.00 35 0.00
9 45 0.32 97 131 73 59 465.00 59 0.00
10 50 0.20 59 118 73 46 465.00 46 0.00
11 55 0.06 17 63 73 - 465.00 - 0.00
12 60 0.32 97 97 73 24 465.00 24 0.00
13 65 0.85 255 279 73 206 465.01 206 0.00
14 70 0.85 255 461 73 389 465.02 389 0.01
15 75 0.85 255 644 73 571 465.03 571 0.01
16 80 0.59 176 747 73 674 465.04 674 0.02
17 85 1.38 413 1,087 73 1,015 465.06 1,015 0.02
18 90 1.51 453 1,468 73 1,395 465.09 1,395 0.03
19 95 1.11 334 1,729 73 1,657 465.10 1,657 0.04
20 100 1.51 453 2,109 73 2,037 465.12 2,037 0.05
21 105 2.30 690 2,727 73 2,654 465.16 2,654 0.06
22 110 2.04 611 3,265 73 3,193 465.20 3,193 0.07
23 115 1.77 532 3,725 73 3,652 465.22 3,652 0.08
24 120 1.91 572 4,224 73 4,151 465.25 4,151 0.10
25 125 2.04 611 4,762 73 4,690 465.29 4,690 0.11
26 130 3.49 1,046 5,736 73 5,663 465.35 5,663 0.13
27 135 4.54 1,363 7,026 73 6,954 465.43 6,954 0.16
28 140 2.56 769 7,723 73 7,651 465.47 7,651 0.18
29 145 6.92 2,075 9,726 73 9,653 465.59 9,653 0.22
30 150 7.58 2,273 11,927 73 11,854 465.72 11,854 0.27
31 155 8.76 2,629 14,483 73 14,411 465.88 14,411 0.33
32 160 5.73 1,719 16,130 73 16,057 465.98 16,057 0.37
33 165 0.59 176 16,233 73 16,161 465.99 16,161 0.37
34 170 0.32 97 16,257 73 16,185 465.99 16,185 0.37
35 175 0.32 97 16,281 73 16,209 465.99 16,209 0.37
36 180 0.08 24 16,232 73 16,160 465.99 16,160 0.37

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.09 26 26 73 - 465.00 - 0.00
2 10 0.10 31 31 73 - 465.00 - 0.00
3 15 0.10 31 31 73 - 465.00 - 0.00
4 20 0.10 31 31 73 - 465.00 - 0.00
5 25 0.10 31 31 73 - 465.00 - 0.00
6 30 0.12 36 36 73 - 465.00 - 0.00
7 35 0.12 36 36 73 - 465.00 - 0.00
8 40 0.12 36 36 73 - 465.00 - 0.00
9 45 0.12 36 36 73 - 465.00 - 0.00
10 50 0.12 36 36 73 - 465.00 - 0.00
11 55 0.12 36 36 73 - 465.00 - 0.00
12 60 0.14 41 41 73 - 465.00 - 0.00
13 65 0.14 41 41 73 - 465.00 - 0.00
14 70 0.14 41 41 73 - 465.00 - 0.00
15 75 0.14 41 41 73 - 465.00 - 0.00
16 80 0.14 41 41 73 - 465.00 - 0.00
17 85 0.14 41 41 73 - 465.00 - 0.00
18 90 0.14 41 41 73 - 465.00 - 0.00
19 95 0.14 41 41 73 - 465.00 - 0.00
20 100 0.14 41 41 73 - 465.00 - 0.00
21 105 0.14 41 41 73 - 465.00 - 0.00
22 110 0.14 41 41 73 - 465.00 - 0.00
23 115 0.14 41 41 73 - 465.00 - 0.00
24 120 0.16 47 47 73 - 465.00 - 0.00
25 125 0.14 41 41 73 - 465.00 - 0.00
26 130 0.16 47 47 73 - 465.00 - 0.00
27 135 0.16 47 47 73 - 465.00 - 0.00
28 140 0.16 47 47 73 - 465.00 - 0.00
29 145 0.16 47 47 73 - 465.00 - 0.00
30 150 0.16 47 47 73 - 465.00 - 0.00
31 155 0.16 47 47 73 - 465.00 - 0.00
32 160 0.16 47 47 73 - 465.00 - 0.00
33 165 0.17 52 52 73 - 465.00 - 0.00
34 170 0.17 52 52 73 - 465.00 - 0.00
35 175 0.17 52 52 73 - 465.00 - 0.00
36 180 0.17 52 52 73 - 465.00 - 0.00
37 185 0.17 52 52 73 - 465.00 - 0.00
38 190 0.19 57 57 73 - 465.00 - 0.00
39 195 0.19 57 57 73 - 465.00 - 0.00
40 200 0.19 57 57 73 - 465.00 - 0.00
41 205 0.02 5 5 73 - 465.00 - 0.00
42 210 0.19 57 57 73 - 465.00 - 0.00
43 215 0.36 109 109 73 36 465.00 36 0.00
44 220 0.36 109 145 73 72 465.00 72 0.00
45 225 0.54 161 233 73 160 465.01 160 0.00
46 230 0.54 161 321 73 248 465.02 248 0.01
47 235 0.71 212 461 73 388 465.02 388 0.01
48 240 0.71 212 600 73 528 465.03 528 0.01
49 245 0.88 264 792 73 719 465.04 719 0.02
50 250 1.05 316 1,035 73 962 465.06 962 0.02
51 255 1.23 368 1,330 73 1,257 465.08 1,257 0.03
52 260 1.40 419 1,677 73 1,604 465.10 1,604 0.04
53 265 1.57 471 2,075 73 2,003 465.12 2,003 0.05
54 270 1.57 471 2,474 73 2,401 465.15 2,401 0.06
55 275 1.74 523 2,924 73 2,851 465.17 2,851 0.07

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 11 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 1.92 575 3,426 73 3,353 465.20 3,353 0.08
57 285 2.09 626 3,980 73 3,907 465.24 3,907 0.09
58 290 2.09 626 4,533 73 4,461 465.27 4,461 0.10
59 295 2.26 678 5,139 73 5,066 465.31 5,066 0.12
60 300 2.43 730 5,796 73 5,723 465.35 5,723 0.13
61 305 3.30 989 6,712 73 6,639 465.41 6,639 0.15
62 310 4.16 1,247 7,887 73 7,814 465.48 7,814 0.18
63 315 4.68 1,403 9,217 73 9,144 465.56 9,144 0.21
64 320 5.19 1,558 10,702 73 10,629 465.65 10,629 0.24
65 325 6.06 1,817 12,446 73 12,373 465.76 12,373 0.28
66 330 7.61 2,282 14,656 73 14,583 465.89 14,583 0.33
67 335 1.23 368 14,951 73 14,878 465.91 14,878 0.34
68 340 0.16 47 14,925 73 14,852 465.91 14,852 0.34
69 345 0.10 31 14,883 73 14,810 465.91 14,810 0.34
70 350 0.09 26 14,836 73 14,764 465.90 14,764 0.34
71 355 0.05 16 14,779 73 14,707 465.90 14,707 0.34
72 360 0.03 10 14,717 73 14,644 465.90 14,644 0.34
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.02 17 17 218 - 465.00 - 0.00
2 30 0.03 25 25 218 - 465.00 - 0.00
3 45 0.03 25 25 218 - 465.00 - 0.00
4 60 0.04 34 34 218 - 465.00 - 0.00
5 75 0.03 25 25 218 - 465.00 - 0.00
6 90 0.03 25 25 218 - 465.00 - 0.00
7 105 0.03 25 25 218 - 465.00 - 0.00
8 120 0.04 34 34 218 - 465.00 - 0.00
9 135 0.04 34 34 218 - 465.00 - 0.00
10 150 0.04 34 34 218 - 465.00 - 0.00
11 165 0.05 42 42 218 - 465.00 - 0.00
12 180 0.05 42 42 218 - 465.00 - 0.00
13 195 0.05 42 42 218 - 465.00 - 0.00
14 210 0.05 42 42 218 - 465.00 - 0.00
15 225 0.05 42 42 218 - 465.00 - 0.00
16 240 0.06 51 51 218 - 465.00 - 0.00
17 255 0.06 51 51 218 - 465.00 - 0.00
18 270 0.07 59 59 218 - 465.00 - 0.00
19 285 0.07 59 59 218 - 465.00 - 0.00
20 300 0.08 68 68 218 - 465.00 - 0.00
21 315 0.06 51 51 218 - 465.00 - 0.00
22 330 0.07 59 59 218 - 465.00 - 0.00
23 345 0.08 68 68 218 - 465.00 - 0.00
24 360 0.08 68 68 218 - 465.00 - 0.00
25 375 0.08 76 76 218 - 465.00 - 0.00
26 390 0.08 76 76 218 - 465.00 - 0.00
27 405 0.09 85 85 218 - 465.00 - 0.00
28 420 0.09 85 85 218 - 465.00 - 0.00
29 435 0.09 85 85 218 - 465.00 - 0.00
30 450 0.10 93 93 218 - 465.00 - 0.00
31 465 0.11 102 102 218 - 465.00 - 0.00
32 480 0.12 110 110 218 - 465.00 - 0.00
33 495 0.14 127 127 218 - 465.00 - 0.00
34 510 0.14 127 127 218 - 465.00 - 0.00
35 525 0.15 136 136 218 - 465.00 - 0.00
36 540 0.16 144 144 218 - 465.00 - 0.00
37 555 0.18 161 161 218 - 465.00 - 0.00
38 570 0.19 170 170 218 - 465.00 - 0.00
39 585 0.20 178 178 218 - 465.00 - 0.00
40 600 0.21 187 187 218 - 465.00 - 0.00
41 615 0.14 127 127 218 - 465.00 - 0.00
42 630 0.14 127 127 218 - 465.00 - 0.00
43 645 0.19 170 170 218 - 465.00 - 0.00
44 660 0.19 170 170 218 - 465.00 - 0.00
45 675 0.18 161 161 218 - 465.00 - 0.00
46 690 0.18 161 161 218 - 465.00 - 0.00
47 705 0.16 144 144 218 - 465.00 - 0.00
48 720 0.17 153 153 218 - 465.00 - 0.00
49 735 0.45 406 406 218 188 465.01 188 0.00
50 750 0.57 516 704 218 487 465.03 487 0.01
51 765 0.79 711 1,198 218 980 465.06 980 0.02
52 780 0.91 821 1,802 218 1,584 465.10 1,584 0.04
53 795 1.41 1,270 2,854 218 2,637 465.16 2,637 0.06
54 810 1.44 1,295 3,931 218 3,714 465.23 3,714 0.09
55 825 0.43 386 4,099 218 3,882 465.24 3,882 0.09
56 840 0.45 409 4,291 218 4,073 465.25 4,073 0.09
57 855 0.86 772 4,846 218 4,628 465.28 4,628 0.11
58 870 0.79 711 5,339 218 5,121 465.31 5,121 0.12

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 0.82 734 5,855 218 5,637 465.34 5,637 0.13
60 900 0.75 671 6,308 218 6,090 465.37 6,090 0.14
61 915 0.68 609 6,699 218 6,481 465.40 6,481 0.15
62 930 0.61 546 7,027 218 6,809 465.42 6,809 0.16
63 945 0.25 228 7,037 218 6,819 465.42 6,819 0.16
64 960 0.28 249 7,068 218 6,850 465.42 6,850 0.16
65 975 0.04 34 6,884 218 6,666 465.41 6,666 0.15
66 990 0.04 34 6,700 218 6,482 465.40 6,482 0.15
67 1005 0.03 25 6,508 218 6,290 465.38 6,290 0.14
68 1020 0.03 25 6,316 218 6,098 465.37 6,098 0.14
69 1035 0.05 42 6,140 218 5,923 465.36 5,923 0.14
70 1050 0.05 42 5,965 218 5,747 465.35 5,747 0.13
71 1065 0.05 42 5,790 218 5,572 465.34 5,572 0.13
72 1080 0.04 34 5,606 218 5,388 465.33 5,388 0.12
73 1095 0.04 34 5,422 218 5,204 465.32 5,204 0.12
74 1110 0.04 34 5,238 218 5,020 465.31 5,020 0.12
75 1125 0.03 25 5,046 218 4,828 465.30 4,828 0.11
76 1140 0.02 4,845 17 218 4,627 465.28 4,627 0.11
77 1155 0.03 25 4,653 218 4,435 465.27 4,435 0.10
78 1170 0.04 34 4,469 218 4,251 465.26 4,251 0.10
79 1185 0.03 25 4,277 218 4,059 465.25 4,059 0.09
80 1200 0.02 17 4,076 218 3,858 465.24 3,858 0.09
81 1215 0.03 25 3,884 218 3,666 465.22 3,666 0.08
82 1230 0.03 25 3,691 218 3,474 465.21 3,474 0.08
83 1245 0.03 25 3,499 218 3,281 465.20 3,281 0.08
84 1260 0.02 17 3,298 218 3,081 465.19 3,081 0.07
85 1275 0.03 25 3,106 218 2,888 465.18 2,888 0.07
86 1290 0.02 17 2,905 218 2,687 465.16 2,687 0.06
87 1305 0.03 25 2,713 218 2,495 465.15 2,495 0.06
88 1320 0.02 17 2,512 218 2,294 465.14 2,294 0.05
89 1335 0.03 25 2,320 218 2,102 465.13 2,102 0.05
90 1350 0.02 17 2,119 218 1,901 465.12 1,901 0.04
91 1365 0.02 17 1,918 218 1,701 465.10 1,701 0.04
92 1380 0.02 17 1,718 218 1,500 465.09 1,500 0.03
93 1395 0.02 17 1,517 218 1,299 465.08 1,299 0.03
94 1410 0.02 17 1,316 218 1,098 465.07 1,098 0.03
95 1425 0.02 17 1,115 218 897 465.05 897 0.02
96 1440 0.02 17 914 218 697 465.04 697 0.02
Basin Depth Analysis

Page 14 of 14 ends

Coachella City CouncilDecember 17, 2025

Coachella City Council
December 17, 2025