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32211 (2)31 C zzl' (�', LS Hydrology & Drainage Report CITY OF LA QUINTA A.P.N.- 649 -110 -0045 A.P.N. - 649 -150 -018 PARCEL MAP NO. 32211 Feiro Engineering, Inc. P.O. Box 12980 Palm Desert, CA 92255 (760) 346 -8015 (760) 346 -2548 Fax www.feiro.net /QRUr aJ /��\ O 60 �m P. 1 2/31 /06 *n, CIVIL \F OF CALM 128C -007 03/19/04 The purpose of this report is to determine off - site /on -site hydrologic flows along with establishing the 1 -HR., 3 -HR, 6 -HR, and 24 -HR 100 -yr. storm event volumes in order to size any required on -site detention basins. The site is a very narrow pie shaped parcel, bounded on the north by the Whitewater River - CVWD storm water channel, and bounded on the south by another CVWD storm water channel, and on the west by residential lots facing onto Vista Grande. The historical natural runoff pattern prior to any development in the immediate vicinity was generally northwesterly toward the Whitewater River. Due to the fact that the property is located at the confluence of the two CVWD drainage channels, and the fact the present runoff is to the northwest, there is no tributary runoff entering the property. Therefore, the main hydrologic consideration will be that of determining the necessity of any on -site detention, predicated upon the 1 -HR., 3 -HR, 6 -HR, and 24 -HR 100 -yr. storm event volumes in order to size any required on -site detention basins. The U.S.D.A. Soil Survey Map indicates that the hydrologic soil group of the tributary area is primarily "Coachella" (CpA), which is listed as a hydrologic soils group B. The site is mostly covered with normal desert brush and raw land cover. The tributary area is fairly flat, thereby resulting in a runoff index number of 82 for the undeveloped site, and 56 for the developed site. (RCFC &WCD, Plate E -6.1 (1 of 2)). This translates into an infiltration rate for pervious areas of the watershed to be 0.22 in/hr., for the undeveloped site and 0.51 in/hr., for the developed site. (RCFC &WCD, Plate E -2.2). Based upon the above criteria, and using 0% factor for impervious areas of the undeveloped site and a 50% impervious factor for the developed site, and using an AMC -II curve, the RCFCWD synthetic unit hydrograph method reflects that the following storm flows may be generated. 1 -HR. 4,990 Cu.Ft. @ 3.3 CFS, 3 -HR. 5,390 Cu.Ft. @ 2.2 CFS, 6 -HR. 5,390 Cu.Ft. @ 2.0 CFS, and 24 -HR. 2,070 Cu.Ft. @ 0.2 CFS In addition to the on -site runoff, and to correct the runoff deficiency from Tract No. 3505, the 1- HR., 3 -HR, 6 -HR, and 24 -HR 100 -yr. storm event volumes were also calculated for the accumulated runoff from Tract No. 3505. And based upon the above same criteria, the RCFCWD synthetic unit hydrograph method reflects that the following storm flows may be generated from Tract No. 3505. 1 -HR. 19,260 Cu.Ft. @ 12.9 CFS, 3 -HR. 20,800 Cu.Ft. @ 8.5 CFS, 6 -HR. 20,800 Cu.Ft. @ 7.5 CFS, and 24 -HR. 7,980 Cu.Ft. @ 0.9 CFS Therefore, in addition to the minimal on -site detention available, the developer has obtained permission from the CVWD Right -of Way Department to allow the excess runoff to be introduced into the existing storm drain channel to the south of the proposed development. Therefore, because the on -site detention basins will not meet the projected storm capacities, the proposed alternate solution for the runoff will need to be approved by the City Engineer and the Coachella Valley Water District. Ronald K. Feiro . President R.C.E. 52260 OFESS /p� �O �p K. N O O 3 No.C52260 m \ EXP. 12/31/06* T CIV1� \CF CAi-1F0� 7 M MaD 1I III �f AaB IV: L CPA . . ........... 17 16 [i3 Water MaD + • q —if 18 JOY ROA6�; -9, MaB MaD Mai T. MaD S CPA Traile r Park ell 2 . 4 .MILES AVENUE 20 MILE 19 1 M a 21 M a 1::; QM MaD .1 ell CPA Q) int.: X9 P, CPA. Gb NNW W !c CPA V Is Mau VA MaD- 29 C-7 30 a CPA b a r 4�. TO! �p to MaD ..... ..... ... MaD -'-'.Gb "s- 4. MaD CPA CPA Is Well A. LU el MaB' aB .e j Is MaD MaB MaB MaD a MaB w MaD, r1fki 32 31 MaD M a WA 9" Mal E) 1,, y MaD nix z A IN i1a Sp ' RIVERSIDE COUNTY, CALIFORNIA 77 TABLE 12. Soil and water features [Absence of an entry indicates the feature is not a concern. See text for descriptions of symbols and such terms as "rare," "brief," and "perched." The symbol < means less than; > means greater than] Hydro- Flooding High water table Bedrock Soil name and logic map symbol group Frequency Duration Months Depth Kind Months Depth Hardness FE in B A A A A A C B q) D A/D B B None ------ None ------ None:_____ Rare ------- None ------ None______ None______ None______ None______ None______ Frequent___ Occasional_ _ Rare_______ None______ D Badland: f BA. D Borrow pits: D B P. Bull Trail: BtE---------------- Cajon: CeD---------------- J ` Cajon Variant: cb D---------------- Carrizo: CcC---------------- * Carsitas: CdC, CdE, ChC, Ckl F 013 ----------------- .t Carsitas Variant: CmB, CmE_________ Chuckawalla: s Co B, Co D, C nC, C n 'f a: M pB, CsA____ ------ --- - - - - -- ` Fluvaquents: ?' Fa----------------- :f Fluvents: Fe----------------- Gilman: G e B, GbA, G b B, Ge, GcA, GdA, GfA____ Gravel pits and dumps: G P. :.' Impperial: IeA---------------- ' IfA ---------------- ImC 1: Imperial part----- Gullied land part. Imperial: IOC 1: Imperial part ----- Gullied land part. Indio: IP, Is -------------- Ir, It -------------- Lithic Torripsamments: LR1: Lithic Torripsamments pa Rock outcrop part. B A A A A A C B q) D A/D B B None ------ None ------ None:_____ Rare ------- None ------ None______ None______ None______ None______ None______ Frequent___ Occasional_ _ Rare_______ None______ D None______ D None______ D None______ D None______ B None- ____. B None ------ D None ------ -------- - - - - -- ------ - - - - -- >6.0 -------------- -------------- ------ - - - - -- >6.0 -------- - -- - -- -------------- ------------ >6.0 -------- - - - - -- -------------- ------------ >6.0 -------- - - - - -- -------------- ------------ >6.0 _ ------- - - - - -- -------------------------- 2.0 -1.0 Apparent---- - -------------------------- >6.0 -------- - - - - -- -------------- ------ - - - - -- ' >6.0 -------- - - - - -- >6 0 Jan -Dec__ _ _ --------------- ----- - - - - -- -------------- ------------ -------------- ____________ 3.0 -5.0 Apparent----- Jan - Dec____ Very long_____ Apr-Sep ---- 0.5 -2.0 Apparent_____ Jan- pec ---- Very brief____ Jan - Dec____ >6.0 ______________ ____________ ------- - - - - - -- ------ - - - - -- >6.0 -------- - - - - -- -----= - - - - -- -------------------- - - - - -- 3.0 -5.0 Apparent - - - -- Apr - Oct - - -- ----------- --- ------ - - - - -- > 6.0 -------------- ------------ 1.0 -3.0 - ------------------- - - - - -- >6.0 1.5 -5.0 Apparent----- I Jan -Dec--- Apparent_____ >60 ---- - - - - -- >60 ---- - - - - -- > 60 ---- - - - - -- > 60 ---- - - - - -- >60 --- - - - - - -- > 60 ---- - - - - -- 6-20 Rippable. >60 ---- - - - - -- >60 --- - - - - - -- > 60 ---- - - - - -- >60 ---- - - - - -- > 60 ---- - - - - -- > 60 ---- - - - - -- > 60 ---- - - - - -- >60 >60 >60 Jan-Dee ---- I >60 >6.0 _ _ >60 3.0 -5.0 Apparent_____ Jan- Dec____ >60 >6.0 1-------------- I------- - - - - -1 1 -10 Hard. �t i i 1 RUNOFF INDEX NUMBERS OF HYDROLOGIC SOIL -COVER COMPLEXES FOR PERVIOUS AREAS -AMC II Cover Type (3) Quality of So ' Group A tB j C D Cover (2 ) NATURAL COVERS - Barren 78 86 91 93 (Ro6kland, eroded and graded land) Chaparrel, Broadleaf Poor 53 70 80 85 (Manzonita, ceanothus and scrub oak) _ Fair 40 63 75 81 Good 31. 57 71 78 •Chaparrel, Narrowleaf Poor Za 82 88 91 (Chamise and redshank) Fair 55 7 81 86 Grass, Annual or Perennial Poor 67 78 86 89 Fair 50 69 79 84 Good 38 61 74 80 Meadows or Cienegas Poor 63 77 85 88 '(Areas with seasonally high water table, Fair 51 70 80 84 principal vegetation is sod forming grass) Good 30 58 72 78 Open'Brush Poor 62 76 84 88 (Soft wood shrubs - buckwheat, sage, etc.) Fair 46 66 77 83 Good 41 63 75 81 Woodland Poor 45 66 77 83 (Coniferous or broadleaf trees predominate. Fair 36 60 73 79 Canopy density is at least 50 percent) Good 28 55 70 77 Woodland, Grass Poor 57 73 82 86 (Coniferous or broadleaf trees with canopy Fair 44 65 77 82 density from 20 to 50 percent) Good 33 58 72 79 URBAN COVERS - Residential or Commerciai Landscaping Good 32 56 69 75 (Lawn, shrubs, etc.) Turf Poor 58 74 83 87 (Irrigated and mowed grass) Fair 44 65 77 82 Good 33 58 72 79 AGRICULTURAL COVERS - Fallow 76 85 90 92 (Land plowed but not tilled or seeded) R C F C a W C D RUNOFF INDEX NUMBERS FOR HYDROLOGY 1\/MANUAL PERVIOUS AREAS PLATE E -6.1 0 of 2) 0 zzf aid 6-0 �, J = e► O \A fl p _0 �O 60 LQ_ 110 - .4s PI T DA, . .... 1 % • ''�, � �) `:� . \�! •i� °E �' •%'° . -�.i� :: `0� '\mss '0 OD .0 OQ 0 is .Q 00; VJ Q. Ar m co 0 < o U'1 _,�.,� �Q•[. �� V �-Q � ',rC/ /q��}L� °"'jam. � la .b' e LC I V Ol I , �� j a- N3?1.�� . C\ 01 0.0 .0 1 74 .f; 114 3 ;t C� rj Irl b th P 3 0 - <Wv. to ge *"P, 128C- 007- DEV -ON -SITE Unit Hydrograph - 01 Hr- Therm.xls 3/23/04 9:14 AM UNIT PATTERN % STORM RAIN LOSS RATE EFF RAIN Q[CFS] Volume (Cu Ft) 1 3.7 0.555 0.281 0.275 0.4 0 2 4.8 0.720 0.281 0.440 0.6 189 3 5.1 0.765 0.281 0.485 0.7 398 4 4.9 0.735 0.281 0.455 0.6 593 5 6.6 0.990 0.281 0.710 1.0 698 6 7.3 1.095 0.281 0.815 1.2 1,249 7 8.4 1.260 0.281 0.980 1.4 1,670 8 9.0 1.350 0.281 1.070 1.5 2,130 9 12.3 1.845 0.281 1.565 2.2 2,803 10 17.6 2.640 0.281 2.360 3.3 3,818 <Qmax 11 16.1 2.415 0.281 2.135 • 3.0 4,737 12 4.2 0.630 0.281 0.350 0.5 4,887 Total Rain --- > 11.63 Unit Time Period = 5 Min. " Point Rainfall Thermal Airport Rain Gage Riv. Co. 6/86 Pattern % Coef. 0.150 Pery Loss Rate 0.510 " Impery Area % 0.500 Adj. Loss Rate 0.281 * Trib Area (sf) P 60 1.4 AC. EFF. RAIN 0.970 Volume (cf) 4,990 1of1 128C- 007- DEV -ON -SITE Unit Hydrograph - 03 Hr- Therm.xls 3/23/04 9:14 AM UNIT PATTERN % STORM RAIN LOSS RATE EFF RAIN Q[CFS) Volume (Cu Ft) 1 1.3 0.292 0.281 0.011 0.0 0 2 1.3 0.292 0.281 0.011 0.0 5 3 1.1 0.247 0.222 0.025 0.0 15 4 1.5 0.337 0.281 0.056 0.1 40 5 1.5 0.337 0.281 0.056 0.1 64 6 1.8 0.404 0.281 0.123 0.2 117 7 1.5 0.337 0.281 0.056 0.1 141 8 1.8 0.404 0.281 0.123 0.2 194 9 1.8 0.404 0.281 0.123 0.2 247 10 1.5 0.337 0.281 0.056 0.1 271 11 1.6 0.359 0.281 0.079 0.1 305 12 1.8 0.404 0.281 0.123 0.2 358 13 2.2 0.494 0.281 0.213 0.3 450 14 2.2 0.494 0.281 0.213 0.3 542 15 2.2 0.494 0.281 0.213 0.3 633 16 2.0 0.449 0.281 0.168 0.2 706 17 2.6 0.583 0.281 0.303 0.4 836 18 2.7 0.606 0.281 0.325 0.5 976 19 2.4 0.539 0.281 0.258 0.4 1,087 20 2.7 0.606 0.281 0.325 0.5 1,227 21 3.3 0.741 0.281 0.460 0.7 1,425 22 3.1 0.696 0.281 0.415 0.6 1,604 23 2.9 0.651 0.281 0.370 0.5 1,763 24 3.0 0.673 0.281 0.393 0.6 1,932 25 3.1 0.696 0.281 0.415 0.6 2,110 26 4.2 0.942 0.281 0.662 0.9 2,395 27 5.0 1.122 0.281 0.842 1.2 2,757 28 3.5 0.785 0.281 0.505 0.7 2,974 29 6.8 1.526 0.281 1.245 1.8 3,510 30 7.3 1.638 0.281 1.358 1.9 4,094 31 8.2 1.840 0.281 1.560 2.2 4,765 <QmaX 32 5.9 1.324 0.281 1.043 1.5 5,214 33 2.0 0.449 0.281 0.168 0.2 5,287 34 1.8� 0.404 0.281 0.123 0.2 5,340 35 1.8 0.404 0.281 0.123 0.2 5,393 36 0.6 _ 0.135 0.121 0.013 0.0 5,399 Total Rain --- > 12.56 Unit Time Period = 5 Min. * Point Rainfall 1.870 Thermal Airport Rain Gage Riv. Co. 6/86 Pattern % Coef. 0.224 * Pery Loss Rate 0.510 * Impery Area % 0.500 Adj. Loss Rate 0.281 * Trib Area (sf) 61,760 1.4 AC. EFF. RAIN 1.047 Volume (cf) 5,387 1 of 1 128C- 007- DEV -ON -SITE Unit Hydrograph - 06 Hr- Therm.xls 3/23/04 9:14 AM UNIT 1 2 3 4 5 6 7 8 9 10 11 12 PATTERN % 0.5 0.6 0.6 0.6 0.6 0.7 0.7 0.7 0.7 0.7 0.7 0.8 STORM RAIN 0.148 0.178 0.178 0.178 0.178 0.207 0.207 0.207 0.207 0.207 0.207 0.237 LOSS RATE 0.133 0.160 0.160 0.160 0.160 0.187 0.187 0.187 0.187 0.187 0.187 0.213 EFF RAIN 0.015 0.018 0.018 0.018 0.018 0.021 0.021 0.021 0.021 0.021 0.021 0.024 Q[CFS] 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Volume (Cu Ft) 0 8 15 23 31 39 48 57 66 75 84 94 13 0.8 0.237 0.213 0.024 0.0 104 14 0.8 0.237 0.213 0.024 0.0 115 15 0.8 " 0.237 0.213 0.024 0.0 125 16 0.8 0.237 0.213 0.024 0.0 135 17 0.8 0.237 0.213 0.024 0.0 145 18 0.8 0.237 0.213 0.024 0.0 155 19 0.8 0.237 0.213 0.024 0.0 165 20 0.8 0.237 0.213 0.024 0.0 176 21 0.8 0.237 0.213 0.024 0.0 186 22 0.8 0.237 0.213 0.024 0.0 196 23 0.8 0.237 0.213 0.024 0.0 206 24 0.9 0.267 0.240 0.027 0.0 218 25 0.8 0.237 0.213 0.024 0.0 " 228 26 0.9 0.267 0.240 0.027 0.0 239 27 0.9 0.267 0.240 0.027 0.0 251 28 0.9 0.267 0.240 0.027 0.0 262 29 0.9 0.267 0.240 0.027 0.0 274 30 0.9 0.267 0.240 0.027 0.0 285 31 0.9 0.267 0.240 0.027 0.0 297 32 0.9 0.267 0.240 0.027 0.0 308 33 1.0 0.296 0.281 0.016 0.0 315 34 1.0 0.296 0.281 0.016 0.0 322 35 1.0 0.296 0.281 0.016 0.0 328 36 1.0 0.296 0.281 0.016 0.0 335 37 1.0 0.296 0.281 0.016 0.0 342 38 1.1 0.326 0.281 0.046 0.1 362 39 1.1 0.326 0.281 0.046 0.1 381 40 1.1 0.326 0.281 0.046 0.1 401 41 1.2 0.356 0.281 0.075 0.1 433 42 1.3 0.385 0.281 0.105 0.1 478 43 1.4 0.415 0.281 0.134 0.2 536 44 1.4 0.415 0.281 0.134 0.2 594 45 1.5 0.445 0.281' 0.164 0.2 664 46 1.5 0.445 0.281 0.164 0.2 735 47 1.6 0.474 0.281 0.194 0.3 818 48 1.6 0.474 0.281 0.194 0.3 901 49 1.7 0.504 0.281 0.223 0.3 997 50 1.8 0.534 • 0.281 0.253 0.4 1,105 51 1.9 0.563 0.281 0.283 0.4 1,227 52 2.0 0.593 0.281 0.312 0.4 1,361 53 2.1 0.622 0.281 0.342 0.5 1,508 54 2.1 0.622 0.281 0.342 0.5 1,655 55 2.2 0.652 0.281 0.372 0.5 1,814 56 2.3 0.682 0.281 0.401 0.6 1,986 57 2.4 0.711 0.281 0.431 0.6 2,172 58 2.4 0.711 0.281 0.431 0.6 2,357 1 of 2 128C- 007- DEV -ON -SITE Unit Hydrograph - 06 Hr- Therm.xls 3/23/04 9:14 AM UNIT PATTERN % STORM RAIN LOSS RATE EFF RAIN Q[CFS] Volume (Cu Ft) 59 2.5 0.741 0.281 0.461 0.7 2,554 60 2.6 0.771 0.281 0.490 0.7 2,765 61 3.1 0.919 0.281 0.638 0.9 3,039 62 3.6 1.067 0.281 0.787 1.1 3,377 63 3.9 1.156 0.281 0.875 1.2 3,753 64 4.2 1.245 0.281 0.964 1.4 4,167 65 4.7 1.393 0.281 1.113 1.6 4,644 66 .5.6 1.660 0.281 1.379 2.0 5,237 < -Qmax 67 1.9 0.563 0.281 0.283 0.4 5,358 68 0.9 0.267 0.240 0.027 0.0 5,370 69 0.6 0.178 0.160 0.018 0.0 5,377 70 0.5 0.148 0.133 0.015 0.0 5,384 71 0.3 0.089 0.080 0.009 0.0 5,387 _72 _ 0.2 0.059 0.053 0.006 0.0 5,390 Total Rain --- > 12.567 Unit Time Period = 5 Min. * Point Rainfall 2.470 Thermal Airport Rain Gage Riv. Co. 6/86 Pattern % Coef. 0.296 * Pery Loss Rate 0.510 * Impery Area % 0.500 Adj. Loss Rate 0.281 * Trib Area (sf) 61,760 1.4 AC. EFF. RAIN 1.047 Volume (cf) 5,390 2 of 2 128C- 007- DEV -ON -SITE Unit Hydrograph - 24 Hr- Therm.xls 3/23/04 9:14 AM UNIT PATTERN % STORM RAIN LOSS RATE EFF RAIN Q[CFS) Volume (Cu Ft) 1 0.2 0.026 0.023 0.003 0.0 0 2 0.3 0.039 0.035 0.004 0.0 5 3 0.3 0.039 0.035 0.004 0.0 10 4 0.4 0.052 0.046 0.005 0.0 17 5 0.3 0.039 0.035 0.004 0.0 22 6 0.3 0.039 0.035 0.004 0.0 27 7 0.3 0.039 0.035 0.004 0.0 32 8 0.4 0.052 0.046 0.005 0.0 38 9 0.4 0.052 0.046 0.005 0.0 45 10 0.4 0.052 0.046 0.005 0.0 51 11 0.5 0.064 0.058 0.006 0.0 60 12 0.5 0.064 0.058 0.006 0.0 68 13 0.5 0.064 0.058 0.006 0.0 76 14 0.5 0.064 0.058 0.006 0.0 85 15 0.5 0.064 0.058 0.006 0.0 93 16 0.6 0.077 0.070 0.008 0.0 103 17 0.6 0.077 0.070 0.008 0.0 113 18 0.7 0.090 0.081 0.009 0.0 125 19 0.7 0.090 0.081 0.009 0.0 136 20 0.8 0.103 0.093 0.010 0.0 149 21 0.6 0.077 0.070 0.008 0.0 159 22 0.7 0.090 0.081 0.009 0.0 171 23 0.8 0.103 0.093 0.010 0.0 184 24 0.8 0.103 0.093 0.010 0.0 198 25 0.9 0.116 0.104 0.012 0.0 213 26 0.9 0.116 0.104 0.012 0.0 227 9 27 1.0 0.129 0.116 0.013 0.0 244 28 1.0 0.129 0.116 0.013 0.0 261 29 1.0 0.129 0.116 0.013 0.0 277 30 1.1 0.142 0.128 0.014 0.0 296 31 1.2 0.155 0.139 0.015 0.0 315 32 1.3 0.167 0.151 0.017 0.0 337 33 1.5 0.193 0.174 0.019 0.0 362 34 1.5 0.193 0.174 0.019 0.0 387 35 1.6 0.206 0.185 0.021 0.0 413 36 1.7 0.219 0.197 0.022 0.0 442 37 1.9 0.245 0.220 0.024 0.0 473 38 2.0 0.258 0.232 0.026 0.0 506 39 2.1 0.270 0.243 0.027 0.0 541 40 2.2 0.283 0.281 0.003 0.0 545 41 1.5 0.193 0.174 0.019 0.0 570 42 1.5 0.193 0.174 0.019 0.0 595 43 2.0 0.258 0.232 0.026 0.0 628 44 2.0 0.258 0.232 0.026 0.0 661 45 1.9 0.245 0.220 0.024 0.0 693 46 1.9 0.245 0.220 0.024 0.0 724 47 1.7 0.219 0.197 0.022 0.0 753 48 1.8 0.232 0.209 0.023 0.0 782 49 2.5 0.322 0.281 0.042 0.1 836 50 2.6 0.335 0.281 0.054 0.1 906 51 2.8 0.361 0.281 0.080 0.1 1,009 52 2.9 0.374 0.281 0.093 0.1 1,129 53 3.4 0.438 0.281 0.157 0.2 1,332 54 3.4 0.438 0.281 0.157 0.2 1,535 < -Qmax 55 2.3 0.296 0.281 0.016 0.0 1,556 56 2.3 0.296 0.281 0.016 0.0 1,576 57 2.7 0.348 0.281 0.067 0.1 1,663 58 2.6 0.335 0.281 0.054 0.1 1,733 1 of 2 128C- 007- DEV -ON -SITE Unit Hydrograph - 24 Hr- Therm.xls 3/23/04: 9:14 AM 59 2.5 0.322 0.281 0.042 0.1 1,786 60 2.4 0.309 0.281 0.029 0.0 1,823 61 2.3 0.296 0.281 0.016 0.0 1,843 62 1.9 0.245 0.220 0.024 0.0 1,875 63 1.9 0.245 0.220 0.024 0.0 1,906 64 0.4 0.052 0.046 0.005 0.0 1,913 65 0.4 0.052 0.046 0.005 0.0 1,920 66 0.3 0.039 0.035 0.004 0.0 1,925 67 0.3 0.039 0.035 0.004 0.0 1,930 68 0.5 0.064 0.058 0.006 0.0 1,938 69 0.5 0.064 0.058 0.006 0.0 1,946 70 0.5 0.064 0.058 0.006 0.0 1,955 71 0.4 0.052 0.046 0.005 0.0 1,961 72 0.4 0.052 0.046 0.005 0.0 1,968 73 0.4 0.052 0.046 0.005 0.0 1,974 74 0.3 0.039 0.035 0.004 0.0 1,979 75 .0.2 0.026 0.023 0.003 0.0 1,983 76 0.3 0.039 0.035 0.004 0.0 1,988 77 0.4 0.052 0.046 0.005 0.0 1,994 78 0.3 0.039 0.035 0.004 0.0 1,999 79 0.2 0.026 0.023 0.003 0.0 2,003 80 0.3 0.039 0.035 0.004 0.0 2,008 81 0.3 0.039 0.035 0.004 0.0 2,013 82 0.3 0.039 0.035 0.004 0.0 2,018 83 0.2 0.026 0.023 0.003 0.0 2,021 84 0.3 0.039 0.035 0.004 0.0 2,026 85 0.2 0.026 0.023 0.003 0.0 2,029 86 0.3 0.039 0.035 0.004 0.0 2,034 87 0.2 0.026 0.023 0.003 0.0 2,038 88 0.3 0.039 0.035 0.004 0.0 2,043 89 0.2 0.026 0.023 0.003 0.0 2,046 90 0.2 0.026 0.023 0.003 0.0 2,049 91 0.2 0.026 0.023 0.003 0.0 2,053 92 0.2 0.026 0.023 0.003 0.0 2,056 93 0.2 0.026 0.023 0.003 0.0 2,059 94 0.2 0.026 0.023 0.003 0.0 2,063 95 0.2 0.026 0.023 0.003 0.0 2,066 96 _ 0.2 0.026 0.023 0.003 0.0 2,069 Total Rain --- > 1.608 Unit Time Period = 15 Min. * Point Rainfall 3.220 Thermal Airport Rain Gage Riv. Co. 6/86 Pattern % Coef. 0.129 * Pery Loss Rate 0.510 * Impery Area % 0.500 Adj. Loss Rate 0.281 * Trib Area (sf) 61,760 1.4 AC. EFF. RAIN 0.402 Volume (cf) 2,068 2 of 2 128C- 007 -DEV- OFF -SITE Unit Hydrograph - 01 Hr- Therm.xls 3/23/04 9:17 AM UNIT PATTERN % STORM RAIN LOSS RATE EFF RAIN Q[CFS] Volume (Cu Ft) 1 3.7 0.555 0.281 0.275 1.5 0 2 4.8 0.720 0.281 0.440 2.4 730 3 5.1 0.765 0.281 0.485 2.7 1,534 4 4.9 0.735 0.281 0.455 2.5 2,289 5 96.6 0.990 0.281 0.710 3.9 3,468 6 7.3 1.095 0.281 0.815 4.5 4,820 7 8.4 1.260 0.281 0.980 5.4 6,447 8 9.0 1.350 0.281 1.070 5.9 8,223 9 12.3 1.845 0.281 1.565 8.6 10,821 10 17.6 2.640 0.281 2.360 1279 14,740 <Qmax 11 16.1 2.415 0.281 2.135 11.7 18,284 12 4.2 _ 0.63.0 _ 0.281 0.350 1.9 18,865 Total Rain --- > 11.63 Unit Time Period = 5 Min. Point Rainfall 1.250 Thermal Airport Rain Gage Riv. Co. 6/86 Pattern % Coef. 0.150 Pery Loss Rate 0.510 Impery Area % 0.500 Adj. Loss Rate 0.281 * Trib Area (sf) X23 ,400 5.5 AC.' EFF. RAIN 0.970 Volume (cf) 19,261 1 of 1 „ I . 128C- 007 -DEV- OFF -SITE Unit Hydrograph - 03 Hr- Therm.xls 3/23/04 9:17 AM UNIT PATTERN % STORM RAIN LOSS RATE EFF RAIN Q[CFS] Volume (Cu Ft) 1 1.3 0.292 0.281 0.011 0.1 0 2 1.3 0.292 0.281 0.011 0.1 19 3 1.1 0.247 0.222 0.025 0.1 60 4 1.5 0.337 0.281 0.056 0.3 153 5 1.5 0.337 0.281 0.056 0.3 246 6 1.8 0.404 0.281 0.123 0.7 451 7 1.5 0.337 0.281 0.056 0.3 544 8 1.8 0.404 0.281 0.123 0.7 749 9 1.8 0.404 0.281 0.123 0.7 954 10 1.5 0.337 0.281 0.056 0.3 1,047 11 1.6 0.359 0.281 0.079 0.4 1,178 12 1.8 0.404 0.281 0.123 0.7 1,3873 13 2.2 0.494 0.281 0.213 1.2 1,737 14 2.2 0.494 0.281 0.213 1.2 2,091 15 2.2 0.494 0.281 0.213 1.2 2,445 16 2.0 0.449 0.281 0.168 0.9 2,724 17 2.6 0.583 0.281 0.303 1.7 3,227 18 2.7 0.606 0.281 0.325 1.8 3,768 19 2.4 0.539 0.281 0.258 1.4 4,196 20 2.7 0.606 0.281 0.325 1.8 4,737 21 3.3 0.741 0.281 0.460 2.5 5,500 22 3.1 0.696 0.281 0.415 2.3 6,190 23 2.9 0.651. 0.281 0.370 2.0 6,805 24 3.0 0.673. 0.281 0.393 2.1 7,457 25 3.1 0.696 0.281 0.415 2.3 8,146 26 4.2 0.942 0.281 0.662 3.6 9,246 27 5.0 1.122 0.281 0.842 4.6 10,643 28 3.5 0.785 0.281 0.505 2.8 11,482 29 6.8 1.526 0.281 1.245 6.8 13,550 30 7.3 1.638 0.281 1.358 7.4 15,805 31 8.2 1.840 0.281 1.560 8.5 18,395 <Qmax 32 5.9 1.324 0.281 1.043 5.7 20,127 33 2.0 0.449 0.281 0.168 0.9 20,407 34 1.8 0.404 0.281 0.123 0.7 20,612 35 1.8 0.404 0.281 0.123 0.7 20,817 _ 36 0.6 0.135 0.121 0.013 0.1 20,839 Total Rain --- > 12.56 Unit Time Period = 5 Min. * Point Rainfall 1.870 Thermal Airport Rain Gage Riv. Co. 6/86 Pattern % Coef. 0.224 Pery Loss Rate 07510 * Impery Area % 0.500 Adj. Loss Rate 0.281 Trib Area (sf) X23 ,400 5.5 AC. EFF. RAIN 1.047 Volume (cf) 20,793 1 of 1 128C- 007 -DEV- OFF -SITE Unit Hydrograph - 06 Hr- Therm.xls 3/23/04 9:17 AM UNIT PATTERN % STORM RAIN LOSS RATE EFF RAIN Q[CFS) Volume (Cu Ft) 1 0.5 0.148 0.133 0.015 0.1 0 2 0.6 0.178 0.160 0.018 0.1 29 3 0.6 0.178 0.160 0.018 0.1 59 4 0.6 0.178 0.160 0.018 0.1 88 5 0.6 0.178 0.160 0.018 0.1 118 6 0.7 0.207 0.187 0.021 0.1 152 7 0.7 0.207 0.187 0.021 0.1 187 8 0.7 0.207 0.187 0.021 0.1 221 9 0.7 0.207 0.187 0.021 0.1 255 10 0.7 0.207 0.187 0.021 0.1 290 11 0.7 0.207 0.187 0.021 0.1 324 12 0.8 0.237 0.213 0.024 0.1 364 13 0.8 0.237 0.213 0.024 0.1 403 14 0.8 0.237 0.213 0.024 0.1 442 15 0.8 0.237 0.213 0.024 0.1 481 16 0.8 0.237 0.213 0.024 0.1 521 17 0.8 0.237 0.213 0.024 0.1 560 18 0.8 0.237 0.213 0.024 0.1 599 19 0.8 0.237 0.213 0.024 0.1 639 20 0.8 0.237 0.213 0.024 0.1 678 21 0.8 0.237 0.213 0.024 0.1 717 22 0.8 0.237 .0.213 0.024 0.1 757 23 0.8 0.237 0.213 0.024 0.1 796 24 0.9 0.267 0.240 0.027 0.1 840 25 0.8 0.237 0.213 0.024 0.1 879 26 0.9 0.267 0.240 0.027 0.1 924 27 0.9 0.267 0.240 0.027 0.1 968 28 0.9 0.267 0.240 0.027 0.1 1,012 29 0.9 0.267 0.240 0.027 0.1 1,056 30 0.9 0.267 0.240 0.027 0.1 1,101 31 0.9 0.267 0.240 0.027 0.1 1,145 32 0.9 0.267 0.240 0.027 0.1 1,189 33 1.0 0.296 0.281 0.016 0.1 1,215 34 1.0 0.296 0.281 0.016 0.1 1,242 35 1.0 0.296 0.281 0.016 0.1 1,268 36 1.0 0.296 0.281 0.016 0.1 1,294 37 1.0 0.296 0.281 0.016 0.1 1,321 38 1.1 0.326 0.281 0.046 0.2 1,396 39 1.1 0.326 0.281 0.046 0.2 1,472 40 1.1 0.326 0.281 0.046 0.2 1,547 41 1.2 0.356 0.281 0.075 0.4 1,672 42 1.3 0.385 0.281 0.105 0.6 1,846 43 1.4 0.415 0.281 0.134 0.7 2,068 44 1.4 0.415 0.281 0.134 0.7 2,291 45 1.5 0.445 0.281 0.164 0.9 2,563 46 1.5 0.445 0.281 0.164 0.9 2,835 47 1.6 0.474 0.281 0.194 1.1 3,156 48 1.6 0.474 0.281 0.194 1.1 3,478 49 1.7 0.504 0.281 0.223 1.2 3,848 50 1.8 0.534 0.281 0.253 1.4 4,267 51 1.9 0.563 0.281 0.283 1.5 4,736 52 2.0 0.593 0.281 0.312 1.7 5,253 53 2.1 0.622 0.281 0.342 1.9 5,820 54 2.1 0.622 0.281 0.342 1.9 6,387 55 2.2 0.652 0.281 0.372 2.0 7,003 56 2.3 0.682 0.281 0.401 2.2 7,668 57 2.4 0.711 0.281 0.431 2.4 8,382 58 2.4 0.711 0.281 0.431 2.4 9,096 1,of2 128C- 007 -DEV- OFF -SITE Unit Hydrograph - 06 Hr- Therm.xls 3/23/04 9:17 AM UNIT PATTERN % STORM RAIN LOSS RATE EFF RAIN Q[CFS] Volume (Cu Ft) 59 2.5 0.741 0.281 0.461 2.5 9,860 60 2.6 0.771 0.281 0.490 2.7 10,672 61 3.1 0.919 0.281 0.638 3.5 11,730 62 3.6 1.067 0.281 0.787 4.3 13,034 63 3.9 1.156 0.281 0.875 4.8 14,485 64 4.2 1.245 0.281 0.964 5.3 16,084 65 4.7 1.393 0.281 1.113 6.1 17,928 66 5.6 1.660 0.281 1.379 7.5 20,214 < -Qmax 67 1.9 0.563 0.281 0.283 1.5 20,683 68 0.9 0.267 0.240 0.027 0.1 20,727 69 0.6 0.178 0.160 0.018 0.1 20,757 70 0.5 0.148 0.133 0.015 0.1 20,781 71 0.3 0.089 0.080 0.009 0.0 20,796 7.2 0.2 0.059 0.053 0.006 0.0 20,806 Total Rain --- > 12.567 Unit Time Period = 5 Min. * Point Rainfall 2.470 Thermal Airport Rain Gage Riv. Co. 6/86 Pattern % Coef. 0.296 * Pery Loss Rate 0.510 * Impery Area % 0.500 Adj. Loss Rate 0.281 * Trib Area (sf) 238,400 5.5 AC. EFF. RAIN 1.047 Volume (cf) 20,805 2 of 2 128C- 007 -DEV- OFF -SITE Unit Hydrograph - 24 Hr- Therm.xls 3/23/04 9:18 AM UNIT PATTERN % STORM RAIN LOSS RATE EFF RAIN Q[CFS) Volume (Cu Ft) 1 0.2 0.026 0.023 0.003 0.0 0 2 0.3 0.039 0.035 0.004 0.0 19 3 0.3 0.039 0.035 0.004 0.0 38 4 0.4 0.052 0.046 0.005 0.0 64 5 0.3 0.039 0.035 0.004 0.0 83 6 0.3 0.039 0.035 0.004 0.0 103 7 0.3 0.039 0.035 0.004 0.0 122 8 0.4 0.052 0.046 0.005 0.0 147 9 0.4 0.052 0.046 0.005 0.0 173 10 0.4 0.052 0.046 0.005 0.0 199 11 0.5 0.064 0.058 0.006 0.0 231 12 0.5 0.064 0.058 0.006 0.0 263 13 0.5 0.064 0.058 0.006 0.0 295 14 0.5 0.064 0.058 0.006 0.0 327 15 0.5 0.064 0.058 0.006 0.0 359 16 0.6 0.077 0.070 0.008 0.0 397 17 0.6 0.077 0.070 0.008 0.0 436 18 0.7 0.090 0.081 0.009 0.0 481 19 0.7 0.090 0.081 0.009 0.0 526 20 0.8 0.103 0.093 0.010 0.1 577 21 0.6 0.077 0.070 0.008 0.0 615 22 0.7 0.090 0.081 0.009 0.0 660 23 0.8 0.103 0.093 0.010 0.1 711 24 0.8 0.103 0.093 0.010 0.1 763 25 0.9 0.116 0.104 0.012 0.1 820 26 0.9 0.116 0.104 0.012 0.1 878 27 1.0 0.129 0.116 0.013 0.1 942 28 1.0 0.129 0.116 0.013 0.1 1,006 29 1.0 0.129 0.116 0.013 0.1 1,070 30 1.1 0.142 0.128 0.014 0.1 1,141 31 1.2 0.155 0.139 0.015 0.1 1,218 32 1.3 0.167 0.151 0.017 0.1 1,301 33 1.5 0.193 0.174 0.019 0.1 1,397 34 1.5 0.193 '0.174 0.019 0.1 1,493 35 1.6 0.206 0.185 0.021 0.1 1,596 36 1.7 0.219 0.197 0.022 0.1 1,705 37 1.9 0.245 0.220 0.024 0.1 1,827 38 2.0 0.258 0.232 0.026 0.1 1,955 39 2.1 0.270 0.243 0.027 0.1 2,090 40 2.2 0.283 0.281 0.003 0.0 2,104 41 1.5 0.193 0.174 0.019 0.1 2,200 42 1.5 0.193 0.174 0.019 0.1 2,296 43 2.0 0.258 0.232 0.026 0.1 2,424 44 2.0 0.258 0.232 0.026 0.1 2,552 45 1.9 0.245 0.220 0.024 0.1 2,674 46 1.9 0.245 0.220 0.024 0.1 2,796 47 1.7 0.219 0.197 0.022 0.1 2,905 48 1.8 0.232 0.209 0.023 0.1 3,020 49 2.5 0.322 0.281 0.042 0.2 3,227 50 2.6 0.335 0.281 0.054 0.3 3,498 51 2.8 0.361 0.281 0.080 0.4 3,896 52 2.9 0.374 0.281 0.093 0.5 4,359 53 3.4 0.438 0.281 0.157 0.9 5,143 54 3.4 0.438 0.281 0.157 0.9 5,926 < -Qmax 55 2.3 0.296 0.281 0.016 0.1 6,004 56 2.3 0.296 0.281 0.016 0.1 6,083 57 2.7 0.348 0.281 0.067 0.4 6,417 58 2.6 0.335 0.281 0.054 0.3 6,688 1 of 2 128C- 007 -DEV- OFF -SITE Unit Hydrograph - 24 Hr- Therm.xls 3/23/04 9:18 AM 59 2.5 0.322 0.281 0.042 0.2 6,895 60 2.4, 0.309 0.281 0.029 0.2 7,037 61 2.3 0.296 0.281 0.016 0.1 7,115 62 1.9 0.245 0.220 0.024 0.1 7,237 63 1.9 0.245 0.220 0.024 0.1 7,359 64 0.4 0.052 0.046 0.005 0.0 7,385 65 0.4 0.052 0.046 • 0.005 0.0 7,410 66 0.3 0.039 0.035 0.004 0.0 7,429 67 0.3 0.039 0.035 0.004 0.0 7,449 68 0.5 0.064 0.058 0.006 0.0 7,481 69 0.5 0.064 0.058 0.006 0.0 7,513 70 0.5 0.064 0.058 0.006 0.0 7,545 71 0.4 0.052 0.046 0.005 0.0 7,570 72 0.4 0.052 0.046 0.005 0.0 7,596 73 0.4 0.052 0.046 0.005 0.0 7,622 74 0.3 0.039 0.035 0.004 0.0 7,641 75 0.2 0.026 0.023 0.003 0.0 7,654 76 0.3 0.039 0.035 0.004 0.0 7,673 77 0.4 0.052 0.046 0.005 0.0 7,699 78 0.3 0.039 0.035 0.004 0.0 7,718 79 0.2 0.026 0.023 0.003 0.0 7,731 80 0.3 0.039 0.035 0.004 0.0 7,750 81 0.3 0.039 0.035 0.004 0.0 7,769 82 0.3 0.039 0.035 0.004 0.0 7,788 83 0.2 0.026 0.023 0.003 0.0 7,801 84 0.3 0.039 0.035 0.004 0.0 7,820 85 0.2 0.026 0.023 0.003 0.0 7,833 86 0.3 0.039 0.035 0.004 0.0 7,853 87 0.2 0.026 0.023 0.003 0.0 7,865. 88 0.3 0.039 0.035 0.004 0.0 7,885 89 0.2 0.026 0.023 0.003 0.0 7,897 90 0.2 0.026 0.023 0.003 0.0 7,910 91 0.2 0.026 0.023 0.003 0.0 7,923 92 0.2 0.026 0.023 0.003 0.0 7,936 93 0.2 0.026 0.023 0.003 0.0 7,949 94 0.2 0.026 0.023 0.003 0.0 7,961 95 0.2 0.026 0.023 0.003 0.0 7,974 96 0.2 0.026 0.023 0.003 0.0 7,987 Total Rain --- > 1.608 Unit Time Period = 15 Min. * Point Rainfall 3.220 Thermal Airport Rain Gage Riv. Co. 6/86 Pattern % Coef. 0.129 Pery Loss Rate 0.510 " Impery Area % 0.500 Adj. Loss Rate 0.281 Trib Area (sf) 238,400 5.5 AC. EFF. RAIN 0.402 Volume (cf) 7,984 2 of 2 41. Hydrology Study City of La Quinta ,Parcel Map No. 32211 Vista Grande Feiro Engineering, Inc. P.O. Box 12980 Palm Desert, CA 92255 (760) 346 -8015 (760) 346 -2548 Fax www.feiro.net QRpFESS /pN C) O G� va Q o.C52260 rZ, EXP. 12/31 /06 CIV1�- ��\P qTF OF intmdurtinn The purpose of this report is to analyze the existing hydrologic characteristics of the proposed development of a 1.4 acre site on Vista Grande in the City of La Quinta and to calculate storm and runoff characteristics to be used in the design of the proposed development. Existing Conditions: The site soil is classified as "CpA, Coachella fine sand ", a hydrologic group "B" soil. The Geotechnical Investigation confirms this by describing the soil, "fine- grained windblown sands ". This project is located at the southwest corner of the intersection of the Whitewater River and the La Quinta Evacuation Channel. 84% of the projects perimeter is adjacent to these major Coachella Valley drainage courses. The side slopes of both drainage courses are lined with a concrete armor to prevent erosion. At the top of the slopes, an approximate 1' high berm prevents runoff from the site from flowing into the wash over the slopes. The site topography is very flat and any stormwater that does not percolate will eventually flow westerly to Vista Grande, due to the remainder of the site being surrounded by a berm. The project is also located at the easterly terminus of Vista Grande Road. An existing residential subdivision of approximately 20 homes as well as a small portion of an adjacent apartment complex flows to the end of Vista Grande and into a catch basin in the southerly curb and gutter. The catch basin connects to an 18" RCP and transitions into a 24" CMP that lastly flows southeasterly into the La Quinta Evacuation Channel. Proposed Drainage Concept: The developer requested and was granted, at the public hearing, the right to retain a portion of the site in a small on -site retention basin and allow the excess to flow onto Vista Grande. This was considered due to the very unusual geometry of the site and the existing elevation and drainage of Vista Grande. This drainage concept is clearly permitted within the Conditions of Approval, specifically #33 that states, "...unless otherwise approved by the City Engineer." The approval letter is attached. Predicted flow in the 18" RCP: The existing tributary area combined with the tributary area of the proposed development that enters catch basin #1 is approximately 3.88 acres. Using the RCFC &WD rational method, it was determined that the Q developed during a 24 -hour duration 100 -year storm event from the tributary site would yield approximately 22.2 CFS. Then using Manning's formula, the flow capacity of an 18" reinforced concrete pipe at 7/8 full was determined to be approximately 22.5 CFS. Clearly, an 18" reinforced concrete pipe flowing full at a slope of 5.70% can endure an ultimate flowrate of 22.8 CFS. Attached are the charts and graphs from the Hydrology Manual along with the supporting calculations. Predicted flow in the 30" RCP: The existing tributary area combined with the tributary area of the proposed development that enters catch basin #2 is approximately 7.08 acres. Using the RCFC &WD rational method, it was determined that the Q developed during a 24 -hour duration 100 -year 'storm event from the tributary site would yield approximately 40.7 CFS. Then using Manning's formula, the flow capacity of a 30" reinforced concrete pipe at 2/3 full was determined to be approximately 48.5 CFS. Clearly, an 18" reinforced concrete pipe flowing full at a slope of 2.98% can endure an ultimate flowrate of 40.7 CFS. Attached are the charts and graphs from the Hydrology Manual along with the supporting calculations. Predicted flows in curb and gutter: The predicted flowrates for the 10 -year and 100 -year storms along the proposed westerly curb and gutter are 3.8 cfs and 6.1 cfs respectively. Conversely, predicted flowrates for the 10 -year and 100 -year storms along the proposed easterly curb and gutter are 1.2 cfs and 1.9 cfs respectively. The arrival of the anticipated runoff volumes were solely based on the tributary area and rainfall data from the RCFC &WD hydrology manual. The tributary area used to calculate these values includes the existing half -width street section of Vista Grande. The tributary area for the anticipated flowrates is 1.07 acres along the westerly curb & gutter and 0.34 acres along the easterly curb & gutter. The runoff coefficient is measured from the Runoff Coefficient Curve Table (Plate D -5.1) which is 0.85. Lastly, the rainfall'intensity is determined from the Rainfall Intensity Curve Data charts (Plate D -4.1), which are 4.14 in/hr for the 10 -year storm and 6.76 in/hr for the 100 - year storm. Attached are the charts and graphs from the Hydrology Manual along with the supporting calculations. Ronald K. Feiro President R.C.E. 52260 1 R) K. S /pN �O e �p K. o C, 0 No.C52260 m rri EXP. 12/31/06 CIVIL ��\P qTF OF CAUFO In the City of La Quinta Hydrology Map Cherokee Homes ■ ■ I. ■ ■ .� ■ •� • i � ■ I' ■ ■ ■ ■ ■ ■ � it ■ • J • • �i • • . • �j FLOWRATE CALCULATION (100 -YR STORM): Q =C *I *A C = 0.85 / = 6.76 in /hr A = 1.41 + 5.71 = 7.08 AC. Q = (0.85) *(6.76) *(7.08) Q= 40.7 cfs FESS�O QRp �O �p K. FFk9l O c� No.C52260 On EXP. 12/31/06 CIVI GRAPHIC SCALE (IN PM) I I=E - 200 R va &x 12M 1n the Ci o La Quinta OWI £ngineenng �" art ad'm ro 9= Land Surveying (760 346 -25M Hydrology Map Fox (760) .HB - ?NB �■^I m,,m,,,,,,,�,,je Parcel Map No. 32211 APN 649- 110- 0041649- 150 -018 FOR: Cherokee Homes FLOWRATE DATA 10 -YEAR 100 -YEAR 7R /B. AREA RUNOFF RAINFALL RAINFALL 10 -YEAR 100 -YE4R AREA COEFF: INTENSITY INTENSITY FLOWRATE FLOWRATE (ACRES) (IN /HR) (IN/HR) (CFS) (CFS) o a o 1 2.81 0.85 4.14 6.76 9.9 16.1 0 2 2.86 0.85 4.14 6.76 10.1 16.4 3 1.07 0.85 4.14 6.76 3.8 6.1 4 0.34 0.85 4.14 6.76 1.2 1.9 va &x 12M 1n the Ci o La Quinta OWI £ngineenng �" art ad'm ro 9= Land Surveying (760 346 -25M Hydrology Map Fox (760) .HB - ?NB �■^I m,,m,,,,,,,�,,je Parcel Map No. 32211 APN 649- 110- 0041649- 150 -018 FOR: Cherokee Homes 18" RCP . STORM DRAIN NOT TO SCALE FLOWRATE CALCULATION (100 -YR STORM): PREDICTED 100 -YR INTO CATCH BASIN /1 Q = C *I *A C = 0.85 I = 6.76 [IN/HR] A = 2.81 + 1.07 = 3.88 AC. Q = (0.85) *(6.76) *(3.88) 0 = 22.2 CFS — PREDICTED FLOW IN 18" RCP QROFESS /p �O �p K. FF�� t� No.C52260 rZi EXP. 12/31/06 it � A'1.�Fp��\P A = (PI) *R' 115.750$ 18" A = (Pl) *(0.75) 2 A = 1.76 [SF] 18" RCP CAPACITY Q = A (1.49) (R)213 (S)'12 [CFS] n R = A /WP A = 1.64 [SF] WP = 3.63 [FT] R = 1.64 [SF]/ 3.63 [LF] R = 0.45 [FT] Q = 1.64 (1.49) (0.18)21(0.057)'12 [CFSI .015 0 = 22.8 CFS — PROPOSED 18" RCP CAPACITY. 18" RCP VELOCITY V = (1.49) (R) 213 (S)' 12 [FPS] n A = 1.64 [SF] WP = 3.63 [FT] R = 1.64 [SF]/ 3.63 [LF] R = 0.45 [FT] V = (1.49) (0.18)21(0.057)'12 [FPS] .015 V = 139 FPS - PROPOSED 18" RCP VELOCITY. 30 " RCP STORM DRAIN FLOWRATE CALCULATION (100 —YR STORM) PREDICTED 100 -YR FLOW INTO CATCH BASIN 12 Q =C *I *A C = 0.85 I = 6.76 [IN /HR] A = 2.81 + 1.07 + 0.34 + 2.86 = =7.08 AC. Q = (0.85) *(6.76) *(7.08) Q = 40.7 CFS - PREDICTED FLOW IN 30" RCP QRpFESS /O �O �p K. 0— c� No.C52260 On ul EXP. 12/31/06 *,-r.7 `Sq CiV1�- �OF' I I 130 " 120" I I 30" RCP CAPACITY Q = A (1.49) (R)213 (S)'12 n R = A /WP A = 3.48 [SF] WP = 4.78 [FT] R = 3.48 [SF]/ 4.78 [LF] R = 0.73 [FT] A = (PI) *R' A = (Pl) *(1.25) 2 A = 4.91 [SF] [CFS] Q = 3.48 (1.49) (0.7J)213(0.0298)'12 [CFS] .015 Q = 48.2 CFS - PROPOSED 18" RCP CAPACITY. 30" RCP VELOCITY V = (1.49) (R) 213 (S)' 12 [FPS] n A = 3.48 [SF] WP = 4.78 [FT] R = 3.48 [SF]/ 4.78 [LF] R = 0.73 [FT] V = (1.49) (0.73) 213(0.0298)'12 [FPS] .015 V = 13.9 FPS — PROPOSED 30" RCP VELOCITY. W'L Y R/W El Y R/W 10' i VARIES 39' -28' i i FINISH -------------------------------- i GRADE VARIES 19.5 -14' VARIES 19.5 -14' i i-------- - - - - -- --------- - - - - -- 3" AC OVER 6" AB 6" CURB i— — AND GUTTER i �J 6" CURB AND GUTTER PROPOSED ROUGH GRADE LINE AT BOTTOM OF ROAD BASE (SUBGRADE) W'LY CURB & GUTTER NOT TO SCALE FLOWRATE CALCULATION (100 -YR STORM): PREDICTED 100 -YR FLOW INTO CATCH BASIN #1 FROM PROPOSED DEVELOPMENT 0 =C *I *A C = 0.85 1 = 6.76 [IN/HR] A = 1.07 AC. 0 = (0.85) *(6.76) *(1.07) 0 = 6.1 CFS — PREDICTED FLOW W'LY CURB & GUTTER 0 =6.1 CFS < 21.5 CFS — OK QROf ESS / &-V-1 �p4!, Z ti c� No.C52260 rn EXP. 12/31/06 civ or 0 = A (1.49) (R)'(S) "2 [CFSJ n R = A /WP R = 1.8 [SF]/ 13.8 [L F] R = 0.13 [FTJ PROPOSED 6' RETAINING WALL /PRIVACY WALL EXISTING GROUND 0 = 6.30 (1.49) (0.13)'(0.031)' C 0.02 FSJ 0 = 21.5 [CFS% — PROPOSED STREET CAPACITY 0 100 —YR. WITH D„ = 3.25 [IN] @ 100 —YR STORM PREDICTED VELOCITY V = (1.49) (R)'(S)'12 [CFSJ n A = 1.8 [SF] WP = 13.8 [FTJ R = 1.8 [SF]/ 13.8 [L F] R = 0.13 [FTJ V = (1.49) (0.13)'(0.031)'12 [CFS] 0.02 V = 3.41 FPS — PROPOSED WILY CURB & GUTTER VELOCITY. V =341 FPS <6FPS —OK W'L Y R/W El Y R/W I I I I I I 1 10' 1 I I 1 I I I I I VARIES 39' -28' I 1 FINISH -------------------------------- GRADE I I I I I I VARIES 19.5 -14' VARIES 19.5 -14' I I-------- - - - - -- --------- - - - - -- 3" AC OVER 6" AB 6" CURB AND GUTTER I J I ? y 29, —� 6" CURB AND GUTTER PROPOSED ROUGH GRADE LINE AT BOTTOM OF ROAD BASE (SUBGRADE) E'LY CURB & GUTTER NOT TO SCALE _FLOWRATE CALCULATION (100 -YR STORM): PREDICTED 100 -YR FLOW INTO CATCH BASIN 12 FROM PROPOSED DEVELOPMENT 0 =C *I *A C = 0.85 / = 6.76 [IN/HR] A = 0.34 AC. 0 = (0.85) *(6.76) *(0.34) Q = 1.9 CFS - PREDICTED FLOW W'LY CURB & GUTTER 0= 1.9 CFS < 21.5 CFS - OK QROFESS /p �O �p K. ,rFk9� O 0 No.C52260 m ul. EXP. 12/31/06 :b 0 = A (1.49) (R)O(S)'12 [CFS] n R = A /WP R = 0.8 [SF]/ 8.9 [LF] R = 0.09 [FTJ PROPOSED 6' RETAINING WALL /PRIVACY WALL EXISTING GROUND z --- 0 = 6.30 (1.49) (0.09)0(0.031)' C 0.02 FSJ O = 16.56 [CFSJ — PROPOSED STREET CAPACITY @ 100 —YR. WITH D" = 2.10 [IN] @ 100 —YR STORM PREDICTED VELOCITY V = (1.49) (R)O(S)'12 [CFS] n A = 0.8 [SF] WP = 8.9 [f -TJ R = 0.8 [SF]/ 8.9 [L F] R = 0.09 [FT] V = (1.49) (0.09)x(0.031)'12 [CFS] 0.02 V = 263 FPS — PROPOSED ELY CURB & GUTTER VELOCITY. V =263 FPS <6 FPS —OK SHEET NO. 11 RIVERSIDE COUNTY, CALIFORNIA, COACHELLA VALLEY AREA (LA QUINTA QUADRANGLE) 17'30" MaB CPA \ MaD s ag iph MaD m MaB a Ld MaD iN R so AS— .0 M CPA v M-00, Sipho MaB CPA 65 2 7 7. 10� ffif 14 p MaD Cp. rr -&i MaD VE E J� ­A' 57. 011 n Fe aD t, A • -MILE u__ AVE •% 19 M aB 1 :t 1v MaB A t a % 3;, -Mat) V A` EWVE� CPA w tt CPA 30,1e' 77,%-U _*c `MaD CPA Is MaD. T a r, f° CpA MaD ;Well �11 'MaR L MaD 116*15' .ni 33-45' RIVERSIDE COUNTY, CALIFORNIA 77 TABLE 12. Soil and water features [Absence of an entry indicates feature perched." The symboln< mea s less than; descriptions eans greater than] and such terms as "rare," Hydro- Flooding High water table Bedrock Soil name and logic map symbol group Frequency I Duration Months Depth Kind Months Depth Hardness Ft In Badland: BA. Borrow pits: B P. Bull Trail: BtE----------------- Cajon CaD----------------- Ca'on Variant: Bb D ----------------- Carrizo CcC ----------------- Carsitas: CdC, Cd E, ChC, CkB. CfB ------------------ Carsitas Variant: C m B, C m E___________ Chuckawalla: Co B, Co D, C nC, C n E. la: C CPB, CsA______ I---------------- Fluvaquents: Fa------------------- Fluvents: Fe------------------- Gilman: G a B, G bA, G b B, GeA. GcA, GdA, GfA______ Gravel pits and dumps: G P. Imperial : IeA------------------ IfA------------------ I mC 1: Imperial part_ _ _ _ _ _. j Gullied land part. Imperial: PM I. Imperial part ------ Gullied land part. Indio: . IPA Is --------------- Ir, It --------------- Lithic Torripsamments: LRI: Lithic Torripsamments part Rock outcrop part. B A A A A A C B (P D A/D B B D D D raw B B .I D None - - - - -- -------- - - - - -- ------ - - - - -- >6.0 None - - - - -- -------- - - - - -- --- -- - - - - -- >6.0 None - - - - -- -------------------- - - - - -- >6.0 Rare- - - - - -- -------------------- - - - - -- >6.0 None - - - - -- -------------------- - - - - -- >6.0 None - - - - -- -------- - - - - -- ------ - - - - -- 2.0 -4.0 None - - - - -- -------------------- - - - - -- >6.0 None - - -- -- ----- --------------- - -- - -- >6.0 None - - - - -- -------------------- - - - - -- >6.0 None - - - - -- ----------------------- -- .0-5. Frequent___ Very long_____ Apr-Sep ---- 0.5 -2.0 Occasional__ Very brief _ _ _ _ Jan - Dec__ _ _ >6.0 Rare- - - - - -- ----------------- --- - - - - -- >6.0 None - - - - -- --------- -------- --- - - - - -- 3.0 -5.0 None - - - - -- -------- ----------- - - - - -- > 6. None - - - - -- -------------------- - - - - -- 1.0-3. None - - - - -- I -------------------- - - - - -- >6. I None------ I-------------- I------ - - - - -- None______ -------- - - - - -- None-------------- - - - - -- 1.5 -5.0 -------------------- - - - - -- >60 ---- - - - - -- -------------- ------ - - - - -- >60 ---- - - - - -- -------------- ------ - - - - -- >60 ---- - - -- -- ------- - - - - -- ------ - - - - -- >60 ---- - - - - -- ------------ >60 ---- - - - - -- ------------- Apparent_____ Jan-Dee ---- >60 __________ -------- - -- - -- ------ - - - - -- 6-20 Rippable. -------- - - - - -- ------ - - - - -- >60 ---- - - - - -- ------ - - - - -- >60 ---- - - - - -- _ ------------- Apparent_____ Jan-Dee ---- >60 __________ Apparent - - - -- Jan- ,Dec -- -- >60 -- -- -- - - -- ------ >60 ---- - - - - -- >60 ---------- Apparent ----- Apr- Oct_ _ _ _ >60 Apparent----- Apparent____ >60 Jan - Dec____ >60 ------ - - - - -- >60 Jan- Dec___- >6.0 _ ___________ 3.0 -5.0 Apparent_____ Jan- Dec___. I None ------ I -------------- I----------- >6.0 1-------------- I------ - - - - -- >60 ---- - - - - -- > 60 ---- - - - - -- > 60 - --- - - - - -- 1-10 Hard. RUNOFF INDEX NUMBERS OF HYDROLOGIC SOIL -COVER COMPLEXES FOR PERVIOUS AREAS -AMC II Cover Type (3) Quality of So A Group A B C D Cover (2) NATURAL COVERS - Barren 78 86 91 93 (Rockland, eroded and graded land) Chaparrel, Broadleaf Poor 53 70 80 85 (Manzonita, ceanothus and scrub oak) Fair 40 63 75 81 Good 31 57 71 78 Chaparrel, Narrowleaf Poor 71 82 88 91 (Chamise and redshank) Fair 55 72 81 86 Grass, Annual or Perennial Poor 67 78 86 89 Fair 50 69 79 84 Good 38 61 74 80 Meadows or Cienegas Poor 63 77 85 88 (Areas with seasonally high water table, Fair 51 70 80 84 principal vegetation is sod forming grass) Good 30 58 72 78 Open Brush Poor 62 76 84 88 (Soft wood shrubs - buckwheat, sage, etc.) Fair 46 66 77 83 Good 41 63 75 81 Woodland Poor 45 66 77 83 (Coniferous or broadleaf trees predominate. Fair 36 60 73 79 Canopy density is at least 50 percent) Good 28 55 70 77 Woodland, Grass Poor 57 73 82 86 (Coniferous or broadleaf trees with canopy Fair 44 65 77 82 density from 20 to 50 percent) Good 33 58 72 79 URBAN COVERS - Residential or Commercial Landscaping Good 32 56 69 75 (Lawn, shrubs, etc.) Turf Poor 58 74 83 87 (Irrigated and mowed grass) Fair 44 65 77 82 Good 33 58 72 79 AGRICULTURAL COVERS - Fallow 76 85 90 92 (Land plowed but not tilled or seeded) R C F C a W C D RUNOFF INDEX NUMBERS r�YDRJLOGY MANUAL FOR PERVIOUS AREA PLATE D -5.5 0 of 2) r -D-I m CT O N RUNOFF COEFFICIENTS FOR RI INDEX NO. = 52 RUNOFF COEFFICIENTS FOR RI INDEX NO. = 54 < ^ IMPERVIOUS INTENSITY - INCHES /HOUR IMPERVIOUS INTENSITY - INCHES /HOUR C ! PERCENT PERCENT .0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 5.0 6.0 .0 1.0 1.5 P.0 2.5 3.0 3.5 4.0 5.0 6.0 .5 0 0. .00 .26 .40 .49 .56 .60 .64 .67 .69 .T2 .75 0. .00 .28 .42 .51 .57 .62 .65 .68 .7O .73 .76 S. .04 .29 .43 .51 .57 -62 .65 .68 .70 .73 .75 S. -04 .31 .45 .53 .59 .63 .67 .69 .71 -T4 .76 .09 .32 .45 .53 .59 .63 -66 .69 .71 .74 .76 10. .09 .34 .47 .55 .61 .65 .68 .70 .72 .75 .77 47 15. .13 .36 .48 .56 .61 .65 .68 .70 .72 .75 .77 15. .13 .37 .49 .57 .62 .66 .69 .71 .73 .76 .78 `< 20. .18 .39 .50 .58 .63 .66 .69 .71 .73 -76 .78 20. .18 .40 .52 .59 .64 .68 -70 .77. .74 ,77 .79 25. .22 .42 .53 .60 .64 .68 .70 .72 .74 .77 .79 25. .22 .43 .54 .61 .66 .69 .71 .73 .75 .78 .79 ._ 30. 35. .27 .31 .45 .48 .55 .58 .62 .64 .66 .68 .69 .71 .72 .73 .74 .75 .75 -76 .78 .78 .79 .80 30. 35. .27 •31 .46 .49 .56 .59 .63 .65 .67 .69 .70 .72 .73 .74 .75 .76 .76 .77 .78 -79 .80 .81 40. .36 .S2 .60 .66 .69 .72 .74 .76 .77 .79 .81 40. .36 .53 .61 .67 .70 .73 .75 .77 .78 .80 .81 45. .40 .55 .63 .68 .71 .74 .76 .77 .78 .80 .82 45. .40 .56 .64 .69 .72 .75 .76 .78 .79 .81 .82 50. .45 .58 .65 .70 .73 .75 .77 .78 .79 .81 .82 50. .45 .59 .66 .71 .74 .76 .78 .79 .80 .82 .83 v 55. .49 .61 .68 .72 .75 .77 .78 .79 .80 .82 .83 55. .49 .62 .68 .73 .75 .77 .79 .80 .81 .83 .84 b 60. .54 .64 .70 .74 .76 .78 .80 Al . .82 .83 -84 60. .54 .65 .71 .74 .7T .79 .80 .81 .82 .83 .84 65. .58 .68 .73 .76 .78 -80 Al . .82 .83 .84 .85 65. .58 .68 .73 .76 .79 .80 .81 .82 .83 .84 .85 r 70. .63 .71 .7S .78 .80 .81 .82 .A3 .84 •8S .85 70. .63 .71 .76 .7A .80 .82 .83 .83 .84 .85 .86 75. .67 .74 .78 .80 .81 .83 .83 .84 .85 .86 .86 7S. .67 .74 .78 .80 .R2 .83 .64 .84 .85 .86 .86 80. .72 .77 .80 .82 .83 .84 AS .85 .86 .86 .87 80. .72 .78 .80 .82 .A3 .84 .85 .86 .86 .87 .87 85. .76 .80 .83 .84 .85 .86 .86 .86 .87 ,87 .88 85. .76 .81 .83 .84 .85 .86 .86 .87 AT .88 .88 90. .81 .84 .85 .86 .87 .87 .87 .88 .88 .88 .88 90. .81 .84 .85 .86 .87 .87 AS .88 .88 .88 .89 95. .86 .87 .88 .88 .88 .89 .89 .89 .89 .89 .89 95. .86 .87 .88 .88 .AB .89 .q9 .89 .89 .89 .89 100. .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 100. -90 .90 .90 -90 .90 .90 .90 .90 .90 .90 ,90 RUNOFF COEFFICIENTS FOP RI INDEX NO. = 56 RUNOFF COEFFICIENTS FOR RI INDEX NO. = 58 IMPERVIOUS INTENSITY - INCHES /HOUR IMPERVIOUS INTENSITY - INCHES /HOUR PERCENT PERCENT .� .0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 5.0 6.0 J .0 .5 1.0 1.5 ?.0 2.5 3.0 3.5 ♦.O 5.0 6.0 C 0. .00 .31 .46 ,55 .61 .65 .68 .71 .73 .75 08 Z 0. .00 .29 .44 .53 .59 .63 .67 .69 .71 .74 .77 Q S. .04 .32 .46 .55 .61 .65 .68 .70 .72 .75 .77 S. .04 .34 .48 .57 .62 .66 .69 .72 .73 .76 .78 C7 10. -09 .3S .49 .57 .62 .66 .69 .71 .73 .76 .78 10. .09 .37 .50 ,58 .64 -67 ,70 .72 04 .77 .79 C n 15. .13 .38 .51 .59 .64 .67 .70 .72 .74 .77 .79 15. .13 .40 .52 .60 .65 .69 .71 .73 .75 .78 .79 20. .18 .41 .53 .60 .65 .69 .71 .73 .75 .78 .79 20. -18 .43 .55 .62 .67 .70 .72 •74 .76 •78 .80 25. .22 .44 .55 .62 .67 .70 .73 .74 .76 -78 .80 25. .22 .46 .57 -64 .68 .71 .74 -75 .77 -79 .81 30. .27 -47 .58 .64 .68 .71 .74 .75 .77 .79 .81 30. .27 .48 .59 .65 -69 .72 .76 -78 .80 .81 35. .31 .50 .60 .66 .70 -73 .75 .77 .78 .80 .81 35. .31 .51 .61 .67 .71 .74 .75 .76 .77 .79 .81 .82 Q 40. -36 .53 .62 .68 .71 .74 .76 .78 .79 .81 .82. 40. .36 .54 .63 .69 .72 .75 .77 .78 09 .81 .83 45. .40 .56 .65 .70 .73 .75 .77 .79 .80 .81 .83 45. .40 .57 .66 -71 .74 .76 .78 .79 .80 .82 .83 0 'T� 50. .45 .60 .67 .71 .75 .77 .78 .80 .81 .02 .83 50. .45 .60 .68 .72 .75 .77 .79 .AO .81 .83 .84 D 55. .49 .63 .69 .73 .76 .78 .80 .81 .82 .83 .84 55. .49 .63 .70 .74 .77 .79 .AO .81 .82 .83 .84 60. .S4 .66 .72 .75 .78 .79 .81 .82 .83 .84 .85 60. .54 .66 .72 .76 .78 -80 .81 .82 .83 .84 .85 D �6 .58 .69 .74 .77 .79 .81 .A2 .83 .83 .85 65. .SB .69 .75 .7B .80 .81 .82 .83 .84 .85 .86 �. .63 .72 .76 .79 .B1 .82 .83 .8♦ .8♦ .BS :8, 70. .63 .72 .T7 .T9 .81 -82 .83 .84 .85 .86 .86 (� 75. .67 ,75 .78 .81 .82 -83 .84 .85 .85 .86 .87 7S- .67 .75 .79 .81 .83 .84 .85 .85 .86 .86 .87 Z 80. .72 .78 .81 .83 .84 .85 .85 .86 .86 .87 .87 80. .72 .TS .81 .83 .84 .85 .86 .86 -86 -87 -88 .,., 85. .76 .81 .83 .94 .85 .86 .87 .87 .87 .88 -88 85. 06 .81 .83 .85 .86 .86 .8T .87 .87 .88 .88 90. .61 .84 .85 .86 .81 .87 .88 .88 .88 .88 .89 90. .81 .84 .86 .86 .87 .87 .88 .98 .88 .89 '.'89 95. .86 .87 .88 .88 .88 .89 .89 .A9 .89 .89 .89 95- -86 .87 .88 .88 .89 .89 .89 .89 .89 -89 .89 100. .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 100. .90 .90 .96 .90 .90 .90' .90 .90 :9D .70 :"90 0 � sp zl ...- � 0 D r r m v .A 0 MIRA LOMA DURATION FREQUENCY MINUTES 10 100 YEAR YEAP 5 6 7 8 9 10 11 12 13 14 is 16 17 18 19 20 22 24 26 28 30 32 34 36 38 40 45 50 55 60 65 70 75 80 85 2.84 2.58 2.37 2.21 2.08 1.96 1.87 1.78 1.71 1.64 1.58 1.53 1.48 1.44 1.40 1.36 1.29 1.24 1.18 1.14 1.10 1.06 1.03 1.00 .97 .94 .89 .84 .80 .76 .T3 .70 .68 .65 .63 SLOPE _ .530 4.4i 4.01 3.75 3.49 3.21 3.10 2.95 2.82 2.7C 2.60 2.50 2.42 2.34 2.27 2.21 2.15 2.04 1.95 1.81 1.80 1.73 1.61 1.62 1.51 1.52 1.4S 1.4C 1.32 1.26 1.20 1.15 1.11 1.01 1.03 1.00 RAINFALL INT MURRIETA - TEMECULA 6 RANCHO CALIFORNIA DURATION FREQUENCY MINUTES 1 0 10 100 10 100 YEAR YEAR YEAR 5 3.45 5.10 6 3.12 4.61 7 2.87 4.24 8 2.67 3.94 9 2.50 3.69 10 2.36 3.48 11 2.24 3.30 12 2.13 3.15 13 2.04 3.01 14 1.96 2.89 15 1.89 2.79 16 1.82 2.69 17 1.76 2.60 18 1.71 2.52 19 1.66 2.45 20 1.61 2.38 22 1.53 2.26 24 1.46 2.15 26 1.39 2.06 28 1.34 1.98 30 1.29 1.90 32 1.24 1.84 34 1.20 1.78 36 1.17 1.72 38 1.13 1.67 40 1.10 1.62 45 1.03 1.52 50 .97 1.44 55 .92 1.36 60 .88 1.30 65 .84 1.24 70 .81 1.19 75 .78 1.15 80 .75 1.11 85 .73 1.07 SLOPE = .550 ENSITY -INCHE NORCO FREQUENCY DURATION FREQUENCY MINUTES 10 1 0 10 100 kjfA YEAR YEAR 5 2.77 4.16 6 2.53 3.79 7 2.34 3.51 8 2.19 3.29 9 2.07 3.10 10 1.96 2.94 11 1.87 2.80 12 1.79 2.68 13 1.72 2.58 14 1.66 2.48 15 1.60 2.40 16 1.55 2.32 17 1.50 2.25 18 1.46 2.19 19 1.42 2.13 20 1.39 2.08 22 1.32 1.98 24 1.26 1.90 26 1.22 1.82 28 1.17 1.76 30 1.13 1.70 32 1.10 1.64 34 1.06 1.59 36 1.03 1.55 38 1.01 1.51 40 .98 1.47 45 .92 1.39 50 .88 1.31 55 .84 1.25 60 .80 1.20 65 .T7 1.15 70 .74 1.11 75 .72 1.07 80 .69 1.04 85 .67 1.01 SLOPE = .500 :S PER HOUR PALM SPRINGS DURATION FREQUENCY MINUTES 10 1 0 YEAR kjfA 5 4.23 6.76 6 3.80 7 3.48 5.56 8 3.22 5.15 9 3.01 4.81 10 2.83 4.52 11 2.67 4.28 12 2.54 4.07 13 2.43 3.88 14 2.33 3.72 15 2.23 3.58 16 2.15 3.44 17 2.08 3.32 18 2.01 3.22 19 1.95 3.12 20 1.89 3.03 22 1.79 2.86 24 1.70 2.72 26 1.62 2.60 28 1.56 2.49 30 1.49 2.39 32 1.44 2.30 34 1.39 2.22 36 1.34 2.15 38 1.30 2.09 40 1.27 2.02 45 1.18 1.89 50 1.11 1.78 55 1.05 1.68 60 1.00 1.60 65 .95 1.53 70 .91 1.46 75 .88 1.41 80 .85 1.35 85 .82 1.31 SLOPE = .580 PERRIS VALLEY DURATION FREQUENCY MINUTES 10 100 YEAR YEAR 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 22 24 26 28 30 32 34 36 38 40 45 50 55 60 65 70 T5 80 85 2.64 2.41 2.24 2.09 1.98 1.88 1.79 1.72 1.65 1.59 1.54 1.49 1.45 1.41 1.37 1.34 1.28 1.22 1.18 1.13 1.10 1.06 1.03 1.00 .98 .95 .90 .85 .81 .78 .75 .72 .70 .68 .66 3.78 3.46 3.21 3.01 2.84 2.69 2.57 2.46 2.37 2.29 2.21 2.14 2.08 2.02 1.97 1.92 1.83 1.75 1.69 1.63 1.57 1.52 1.48 1.44 1.40 1.37 1.29 1.22 1.17 1.12 1.08 1.04 1.00 .97 .94 SLOPE = .490