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33085
uurea��i IN THE CITY OF LA QUINTA, CALIFORNIA a MHAL H�DG�O�OC� BASH REPOIR7 TRACT MAP NO. 33085 NOVEMBER 16, 2007 CVETEL(760)360 -4200 FAX(760)360 =4204 Coachella Valley Engineers 77 -899 Wolf Road, Suite 102, Palm Desert, CA 92211 QRpFESS K. RIC�� �yc w m # NO. 35728 ,f EXP. 6 -30-09 S� 9fF C I V 1 \- �o��• �/ 'ry Of p pX\ DAVID K. RICE — RCE 35728 — EXPIRES 6 -30 -09 AVENUE 50 33 X34 T.5S. 5 4 4 3 T. 6S. VISTA Lo BONITA TRAIL AVENUE 51 OLD ORCHARD Z LANE 0 BETH CIRCLE L 5 4 43 8 9 AVENUE . 52 VICINITY MAP N.T.S. TRACT MAP NO. 33035 HYDROLOGY STUDY t PREPARED BY: Coachella Valley Engineers 77 -899 Wolf Road, Suite 102 Palen Desert, CA, 92211 NOVEMBER 2007 d TABLE OF CONTENTS Cover Sheet Table of Contents Hydrology Report Text (2007) Drainage Area Map — Post Development Retention Basin Sizing Spreadsheets SUH..CLQ..Comparative Analysis Street Carrying Capacity Calculations Catch Basin Design Calculations TENTATIVE TRACT MAP 33085 APPROVED RETENTION BASIN 12/15/2005 APPROVED HYDROLOGY REPORT 12/15/2005 Location Map — Predevelopment Soil Conservation Service Aerial Map Storage Hydrograph ( rational method ) Offsite Topography and Storm Flow Madison Avenue Storm Flow analysis Geotechnical Infiltration Testing Results Riverside County Hydrology Manual Excerpts 0 2 Coachella Land — Storm Water Management 11 /16 /2007Report Prepared by: Coachella Valley Engineers I ' -I ' INTRODUCTION AND PROJECT INFORMATION Q Il IJ t r L� L' The proposed site is located north of Avenue 52, west of Madison Street and south of Beth Circle. The project consists of a 4.32'Acre parcel being developed into 7 residential lots, each approximately 0.5 acres in size. HYDROLOGY Per the Conditions of Approval for T.M. No 33085, the materials within this report comply with the provisions of Section 13.24.120 (Drainage), LQMC, Engineering Bulletin No. 97.03. The storm volumes of 2.6, 3.1, and 4.0 inches for the duration of the 3 hour, 6 hour, and 24 hour / 100 year storm frequencies have been utilized in this analysis. The storm volumes are obtained from the Point Precipitation Frequency Estimates from DOC /NOAA/National Weather Service Office of Hydrologic Development, Hydro meteorological Design Studies Center, W /OHD13 at 1325 East -West Highway Silver Spring, MD 20910 -3283 The. hydrologic soils group map for the Coachella area is included in the appendix of this report. The soil type is a sandy, silty, loamy Indio soil, I -S, and Gilman B Soil, common in this area. The soil classification for the site is type "B ", having high infiltration rates, antecedent moistening conditions rating of AMC II and low runoff potential when saturated. Soil Infiltration testing was performed by 'LandMark Geo- Engineers and Geologists', LCI, Report No. LP05057, at the proposed location for the stormwater retention facility Testing concludes that a rate of 13.0 gallons per hour (20.8 in /hr /sf) can safely be used for infiltration design. As this analysis has been prepared in support of the previously approved study from 2005, a percolation rate of 2.00" /hour has been utilized in this analysis, as was used in the earlier study. As an additional factor of safety, the City of La Quinta has requested that the 100 -year, 3 -hour storm event also be analyzed utilizing a different analysis method (Synthetic Unit Hydrograph), with zero percolation considered. The site Runoff Index number of the hydrologic soil cover complex,- for the pervious area (AMC II), is RC 56. This is for residential landscaping on Group B soils, with 45% impervious cover from RCHM plate D -5.5. For off -site street flows impacting the site, a 90% impervious value was utilized. The pond storage is based on the 100 year, storm event which results in the maximum volume required given the range of storms tested.. The 'Retention Basin Summary Table', included on the Drainage Area map, lists the basin design volumes at different levels within the proposed retention basin. 3 Coachella Land — Storm Water Management 5 /30 /2007Report Prepared by: Coachella Valley Engineers 1.1 HISTORICAL DRAINAGE PATTERN 1 i Along the west boundary of the site, an existing earthen berm exists effectively blocking flows from the west. Along the east boundary, Madison Street, falling from north to south, is at a lower elevation than the site. Beth Circle, which will serve as the access 1l .1 point to this site, fronts the property along a portion of the northern boundary. A high point exists on Beth Circle approximately midway between Madison Street and the proposed Starfruit Trail. Street generated flows east of the high point flow east to Il Madison Street (0.13 acres). North of the high point, street flows on the north side of the centerline in Beth Circle will be collected by two proposed catch basins to be constructed as a part of TM 30378. Street generated flows south of the centerline of Beth Circle 1 (0.10 acres), impact this site from the north. As this site is presently a citrus orchard, flows originating on -site are retained on -site, thereby, the site to the immediate south is 1� not impacted by this site. DEVELOPED DRAINAGE MANAGEMENT PLAN 1_l This drainage analysis has been prepared in support of the approved preliminary 11 hydrology plan per City of La Quinta Resolution No. .2005-098, Conditions of Approval JJ for Tentative Tract 33085, Core Homes, LLC. ri 'r I J I I J Onsite Storm Runoff: The proposed drainage management plan calls for onsite developed storm flows, not percolating within each lot, to surface discharge into Kiwi Court. Collected storm flows will be routed east within the street gutter pan to an adequately sized catch basin, located in a sump condition, near the southeast corner of the site. Collected storm flows will be retained, and percolated, within an on -site retention facility. Offsite Storm Runoff: Per the approved hydrology plan for TM 30378, this site is responsible for collecting, and retaining off -site storm flows from the portions of Beth Circle defined above which impact this site directly, or indirectly via Madison Street. Those off -site drainage areas, #s 11 & 12 from the TM 30378 study, generate estimated storm volumes of 1,169 cf; and 2,769 cf, respectively. The defined site improvements for TM 33085 will thereby be sized to collect and retain these off -site flows. Street flows from off -site drainage area #11 ( 0.10 acres from TM 30378 study) enter the site via Starfruit Trail, surface discharge to Kiwi Court to be routed to the aforementioned catch basin adjacent to the on -site retention facility. Flows generated from east of the high point in Beth Circle enter Madison Street, and are routed south to a proposed catch basin along the west curb in Madison, adjacent to the on -site retention facility. Thereby, the extent of the Madison Street tributary area extends from the northernmost return at Beth Circle to the aforementioned catch basin (0.81 acres). 4 Coachella Land — Storm Water Management 5 /30 /2007Report Prepared by: Coachella Valley Engineers 1 r n 11 G 1] n 1] 11 c �i IJ Retention Basin: The on -site retention facility is to be located on an approximate 0.23 acre parcel located near the southeast portion of the site. As designed, the basin bottom elevation is at 505, with a top of slope elevation of 511. The planned basin shall conform with City of La Quinta standards, including a maximum of 3:1 side slopes, 6 ft maximum depth, 1 ft minimum freeboard as measured from the lowest adjacent street flowline grade. A Maxwell Plus (or equal) drywell system is proposed along the bottom of the basin to collect nuisance flows, and runoff waters from smaller storm events. Storm waters will enter the retention basin at two locations. An onsite catch basin to be located near the east end of Kiwi Court will outfall into the retention basin via a 24" outfall pipe. An additional catch basin is planned along the west curb of Madison Street with an 18" outfall line discharging flows into the basin. Childproof grates are planned at the ends of both outfall pipes. As designed, the proposed retention basin has a maximum cumulative storage capacity (as measured from top of slope to basin bottom) of 41,589 cubic feet. Design calculations reflect that the maximum required retention volume is for the 100 -year, 3- hour storm at 33,425 cubic feet. As an added factor of safety, a storage volume of 35,000 cubic feet has been allowed for which results in a 100 -year ponding depth of 5.66' at an elevation of 510.16. With that 1.10' of freeboard is provided as measured from the water surface level (WSQ to the lowest adjacent street flowline elevation, 511.26 In the event that storm volumes exceed design volumes, excess storm waters will exit the retention facility via the catch basins on Kiwi Court, and Madison Street. - SUMMARY Following the conditions identified in Resolution No. 2005 -098 the defined developed drainage management plan provides for a fail -safe drainage management system that ensures there will be no adverse impacts to downstream properties. 5 Coachella Land — Storm Water Management 5 /30 /2007Report Prepared by: Coachella Valley Engineers rn h FG 512.80 IN THE CITY OF LA QUINTA, COUNTY OF RIVERSIDE, STATE OF CALIFORNIA TRACT MAP N0. 33085 IN THE NE1 /4 OF THE SE1 /4 OF SECTION 4, T.6S., R.7E. SBM RETENTION BASIN SUMMARY TABLE N6 0 00 1 FT. - FREEBOARD ELEV. AREA (SF) AREA CHANGE (SF) VOL /FT (CF) CUMUL VOL. (CF) 411.00 10,367 1,221 9,757 41,589 410.00 9,146 1,221 8,536 31,833 409.001 7,925 1,221 7,315 23,297 408.00 6,704 1,221 6, 093 15,981 407.00 5,482 1,221 4,872 9,890 406.00 4,261 1,221 _ 3,651 5,018 405.00 3,040 610 1,368 1,368 404.50 2,430, 0 0 0 T010 \ 1 FT. FREEBOARD LOT "E" 10,366 S.F. 19011- L.S. /RET. -Tor . SD RETENTION BASIN TOP 511.00 BOTTOM 504.50 �O wsfw= 510.16 WStoo Vol = 35,000CF �o OVERFLOW TO STREET GRAPHIC SCALE 20 0 10 20 40 60 ( IN FEET ) 1 inch = 20 ft. BOT 504.50 -- TOP 511.00 04220 RETENTION BASIN SUMMARY TABLE ELEV. AREA (SF) AREA CHANGE (SF) VOL /FT (CF) CUMUL VOL. (CF) 411.00 10,367 1,221 9,757 41,589 410.00 9,146 1,221 8,536 1 31,833 409.00 7,925 1,221 7,315 1 23,297 408.00 6,704 1,221 6, 093 15,983 407.00 5,482 1,221 4,872 9,890 406.00 4,261 1,221 3,651 5,018 405.00 3,040 610 1,368 1,368 404.50 1 2, 430 0 0 0 0 14' Sandfilter per City of Lo Ouinto Std. 307 DRAINAGE AREA MAP STORM DRAIN /RETENTION BASIN EXHIBIT TRACT 33085 CORE HOMES, L.L.C. OLD ORCHARD LANE (PRIVATE STREEO BETH CIRCLE BETE CIRCLE - OFF' = (PRIVATE MEET) a 515.80 515.40 P 515.20 FL 514.40 DRAINAGE AREA = 0.10 AC. H . TC 513.95 - - - - . d ` 0.5X 0.7X 513.90 20 50 AC. �'� FL 513.60 514. 12 FL 513.40 HP o PE 515.6 (0 TC / \ \ 0 513.76 7 h I 21,780 S.F. h FL 516.30 V I o ` 0.50 AC. J HP r.� "� PE 514.4 2 \ wi �i h Q 21,780 S.F. TC 514.72 . - h 0 I I �6 / �o 0.50 AC. ti U (n I TC 513.44 PE 516.6 TC 514.79 ►� l TC 512.92 TC 512.48 �O / TC 515.27 0.52% 0.50% - 1.05% _ _ KIWI COURT FL 515.70 -rPPf ATE 0.5% 0.50% STREE77 TC 515.21 0-5% TC 514.57 TC 515.15 \ TC 513.43 FL 515.60 TC 514' 41 l TC 513.77 tl C TC 514.63 TC 513.12 I TC 51 TC 514.50 TC 51; I I 4 3 21,78VS.F. 21,780 S.F. 9e 0.50 5.2 0.50 AC. o } �'o PE 515.2 0 o bt PE 516.5 f GRAPHIC SCALE 50 0 25 50 100 150 ( IN FEET ) 1 inch = 50 ft. 0 5 21,780 S.F 0.50 AC. PE 514.1 FL 516.2 FL 515.5 FL 514.9 FL 513.8 FL 513.80 HP Hp 0.5X 0.8X ONSITE DRAINAGE AREA = 4.32 AC. 0.97% TC 512.17 6 21,780 S.F. O 0.50 AC. v� PE 513.9 :TC 511.78 TC 511.73 TC 511.91 Qio= 6.49 CFS Qroo= 10.37 CFS W =41 QPROP MAXWELL - FL 512.60 FL 512.80 I. OX �O$ TOP 511.00 ZTTOM 504.50 oo= 510.16 of . h 0 4 l I 1 � l d 11 � 4 t �ty INK V . O �Q 1 � I LEGE�IQ TC- TOP OF CURB CB - CATCH BASIN SO- STORMDRAIN D/- DRAIN INLET m O O 3 DW - DRY WELL I HP - HIGH POINT (E) - EXISTING LP - LOW POINT FL - FLOW LINE Q - NOTE - - - DRAINAGE FLOWLINE - DRAINAGE FLOW ARROW - DRAINAGE BOUNDARY LINE RETENTION BASIN VOLUME CALCS. FOR TM. #33085 Adjacent Roadway Flowline = 511.26 100 -Yr Pond WSL = 510.16 ELEVATION AREA AREA CHANGE VOL /FT (Avg) SF SF CF 411.00 10,367 1,221 9,757 410.00 409.00 408.00 407.00 9,146 1,221 7,925 1.221 6,704 1,222 5,482 1,221 8,536 7,315 6,093 4,872 406.00 405.00 4,261 1,221 3,040 610 3,651 1,368 4 04.50 2,430 0 0 WSL = 35,000cf CUML VOL CF 41,589 31,833 23,297 15,983 9,890 5,018 1,368 0 i {\ rtf 1\ ansi\ deff0 { \fonttbl { \f0 \fnil \fcharset0 Courier New;)) \viewkind4 \ucl \pard \fang 1033 \f0 \fs20 \par \tab \tab Unit Hydrograph Analysis \par \par \tab \tab Copyright (c) CIVILCADD/CIVILDESIGN, 1989 - 2004, Version 7.0 \par \tab \tab \tab Study date 11/15/07 File: COREHOMES3HR3100.out \par \par \par \tab +++++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++ \par \tab ------------------------------------------------------------------------ \par \par \tab Riverside County Synthetic Unit Hydrology Method \par \tab RCFC & W CD Manual date - April 1978 \par \par \par /tab Program License Serial Number 6078 \par \par \tab --------------------------------------------------------------------- \par \tab English (in -lb) Input Units Used \par \tab English Rainfall Data (Inches) Input Values Used \par \par \tab English Units used in output format \par \par \par \par \tab --------------------------------------------------------------------- \par \tab ------------------------------------------------------------ 7 -------- \par \tab Drainage Area = 5.23(Ac.) = 0.008 Sq. Mi. \par \tab Drainage Area for Depth -Area Areal Adjustment = 5.23(Ac.) = 0.008 Sq. Mi. \par \tab Length along longest watercourse = 610.00(Ft.) \par \tab Length along longest watercourse measured to centroid = 304.00(Ft.) \par \tab Length along longest watercourse = 0.116 Mi. \par \tab Length along longest watercourse measured to cent. roid = 0.058 Mi. \par \tab Difference in elevation = 5.00(Ft.) \par \tab' Slope along watercourse = 43.2787 Ft. /Mi. \par \tab Average Manning's 'N' = 0.015 \par \tab Lag time = 0.026 Hr. \par \tab Lag time = 1.57 Min. \par \tab 25% of lag time = 0.39 Min. \par \tab 40% of lag time = 0.63 Min. \par \tab Unit time = 15.00 Min. \par \tab Duration of storm = 3 Hour(s) \par \tab User Entered Base Flow = 0.00(CFS) \par \par \tab 2 YEAR Area rainfall data: \par \par \par \tabArea(Ac.)[1] Rainfall(In)[2] Weighting[1 "2] \par \tab 5.23 \tab 0.75 \tab \tab 3.92 \par \par \tab 100 YEAR Area rainfall data: \par \par ° \par \tab Area(Ac.)[11 Rainfall(In)[21 Weighting[1*2] \oar \tab 5.23 \tab 2.20 \tab \tab 11.51 \par . \par \tab STORM EVENT (YEAR) = 100.00 \par \tab Area Averaged 2 -Year Rainfall = 0.750(In) \par \tab Area Averaged 100 -Year Rainfall 2.200(l n) \par \par \tab Point rain (area averaged) = 2.200(ln) \par \tab Areal adjustment factor= 100-00% \par \tab Adjusted average point rain= 2.200(In) . \par \par \tab Sub -Area Data: \par \tab Area(Ac.) Runoff Index Impervious % \par \tab 1.490 56.00 0.900 \par \tab 3.740 56.00 0.450 \par \tab Total Area Entered = 5; 23(Ac.) \par \par \par \tab RI RI Infil. Rate Impervious Adj. Infil. Rate Area% F \par \tab AMC2 AMC -3 (In /Hr) (Dec. %) (In /Hr) (Dec.) (In /Hr) \par \tab 56.0 74.8 0.305 0.900 0.058 0.285 0.017 \par \tab 56.0 74.8 0.305 0.450 0.182 0.715 0.130 \par Sum (F) = 0.146 \par \tab Area averaged mean soil loss (F) (In /Hr) = 0.146 \par \tab Minimum soil loss rate ((In /Hr)) = 0.073 \par \tab (for 24 hour storm duration) \par \tab Soil low loss rate (decimal) = 0.670 \par \tab ---------------------- - --------------------------------------------- \par \par \tab \tab \tab U n i t H y d r o g r a p h \par \tab \tab \tab \tab DESERT S -Curve \par \tab -------------------------------------------------------------------- \par \tab \tab \tab Unit Hydrograph Data \par \tab ------------------- - - - - -- - - -- -------------------------------------- \par \tab Unit time period Time % of lag Distribution Unit Hydrograph \par \tab (hrs) Graph % (CFS) \par \tab -------------------------------------------------------------- - ----- \par \tab 1 0.250 954.584 100.000 5.271 \par \tab Sum = 100.000 Sum= 5.271 \par ------------------------------------------------------------- ---- - - - - -- \par \par \par Unit Time Pattern Storm Rain Loss rate(In. /Hr) Effective \par (Hr.) Percent (In /Hr) Max Low (In /Hr) \par 1 0.25 3.70 0.326 0.146 - -- 0.18 \par 2 0.50 4.80 0.422 0.146 - -- 0.28 \par 3 0.75 5.10 0.449 0.146 - -- 0.30 \par 4 1.00 4.90 0.431 0.146 - -- 0.28 \par 5 1.25 6.60 0.581 0.146 - -- 0.43 \par 6 1.50 7.30 0.642 0.146 - -- 0.50 \par 7 1.75 8.40 0.739 0.146 - -- 0.59 \par 8 2.00 9.00 0.792 0.146 0.65 \par 9 2.25 12.30 1.082 0.146 --- 0.94 \par 10 2.50 17.60 1.549 0.146 - -- 1.40 ' \par 11 2.75 16.10 1.417 0.146 = _ 1.27 \par 12 3.00 4.20 0.370 0.146 0.22 \par Sum = ' 100.0 Sum = 7.0 ' \par \tab Flood volume = Effective rainfall 1.76(ln) \par \tab times area 5.2(Ac.) /[(In) /(Ft.)] = 0.8(Ac.Ft) \par \tab Total soil loss = 0.44(ln) t \par \tab Total soil loss = 0.191(Ac.Ft) \par \tab Total rainfall = 2.20(In) \par \tab Flood volume = 33424.5 Cubic Feet \par \tab Total soil loss = 8341.4 Cubic Feet \par \tab -------------------------------------------------------------------- - \par \tab Peak flow rate of this hydrograph = 7.395(CFS) \par \tab ----------------------------------------------------- - - - - -- - - - - -- \par \tab +++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++ \par \tab 3 -HOUR STORM \par \tab Runoff Hydrograph ' \par \tab -------------------------------------------------------------------- \par \tab Hydrograph in 15 Minute intervals ((CFS)) \par \par \tab -------------------------------------------------------------------- \par Time(h +m) Volume Ac.Ft Q(CFS) 0 12.5 5.0 7.5 10.0 \par ------------------------------- - ----------------- -- ------------------- \par 0 +15 0.0195 0.94 V Q ' \par 0 +30 0.0496 1.46 IV Q \par 0 +45 0.0825 1.59 I V Q \par 1+0 0.1135 1.50 VQ I ' \par 1 +15 0.1609 2.29 VQI I I \par 1 +30 0.2149 2.62 I QV I I \par 1 +45 0:2795 3.13 I I Q V I I I \par 2+0 0.3498 3.40 I I Q V1 I I \par 2 +15 0.4518 4.94 I I Q V \par 2 +30 0.6046 7.40 I I I QIV I \par 2 +45 0.7430 6.70 I I I Q` I V I '! \par 3+0 0.7673 1.18 I Q I I I V \par ------------- 7 --------------------------------------------------------- \par \par \par \par \par } I IJ 'I 'I ;J ®IBIS ...'TIi130378..TM33085 As originally agreed in the meeting at city hall and again drographs" as calcu calculate by using submitting the "previously approved syntheti Y the Bondiman Civil Desk computer program. Very simple ...but confusing by the inter mixing of old Hydrology reports.. very old hydrology reports and...very very old hydrology reports shall demonstrate the difference and or similarities of the SUH method to the ration al method.. TM 33085 ... 100year..3hr. storm.. SUH calculations for 0.43 acres of paving runoff area......6584x 0.43/1.02 = 2776CF SUH calculation for 3.73 acres of unimproved area ...... 4662 x 0.87 x 4.3 = 17441 CF Area no. 11 from TM 30378.....1169CF Area no. 12 from TM 30378.....2769CF THEREFORE AS SHOWN ON TM33085 DRAINAGE �4Mj TOTAL VOLUME TO rlc BE COLLECTED IN THE RETENTION BASIN UP Maximum basin volume is 38,148 cfs @ freeboard elevation Water Depth for 24, 155cfs is 4.5 feet. For comparison to the same area for rational analysis for 4.76 acre storm ... 100 year 24 hour storm generates 25,725 CF of stormwater.... Verses:.the SUH method for the 100 year, three hour storm of 20217 cfs of stormwater.. . U n i •t H y d r o g r a p h A T a l y s i s Copyright (c) CIVILCADD /CIVILDESIGN, 1989 - 2004, Version 7.0 ., VDB5W13100 . out Study date 05/07/07 File: .1..+. T.}' ..i'..{.. . {... T T...... T T.. ..t. T T T.1 +. .1.. T.. ..{..t..}..}.'}..1.F.+..F T.t'..'.}.F.. . T ..+... . . T - - - - - - - - - --- - --- Riverside County Synthetic Unit Hydrology Method RCFC & WCD Manual date - April 1978 Program License Serial Number 6078 English (in -lb) Input Units Used Input Values Used English Rainfall Data (Inches) English Units used in output format CITLAQUINTA COACHELLA VALLEY ENGINEERS DICRICE ------------ - - -- -- 0.87(Ac.) = 0.061 Sq. Mi. Drainage Area = 0.07(Ac.) Drainage Area for Depth -Area Areal Adjustment _ 0.000 Sq. mi. .. hours USER Entry of la time Lag time = 0.080 Hr. Lag time 4.80 Min. 254 of 'lag time = 1.20 Min. 40% of lag time, _. -1.92 Min.. Unit time =' * 15-oo Min.. Duration of strm = 3 Hour(s) User Entered Base Flow = 1.04(CFS) 2 YEAR Area rainfall data: Area (Ac.) [1] Rainfall (In) [2] 0.07 1.04 100 YEAR Area rainfall data: Area (A.c.) [1] Rainfall (In) [2] 0.07 2.54 STORM EVENT (YEAR) = 100.00 Weighting[1 *2] 0.07. weighting [1 *2] 0.18 . Rainfall = 1040(In) Area Averaged 2 -Year 2.540(ln) Area.Averaged 100 -Year Rainfall = ( In), Point rain (area averaged) 2 .5 4 0 Areal 00.00 � o real adjustment factor = 2 540(In) Adjusted average point rain = Sub.-Area Data: - Im erg ions % Area(Ac.) Runof f Index p 200 0.070 56.00 5600 0.000 . 0.000 0.30.0 0.800 56. 0.0 0.87(Ac.) Total Area Entered = Adj. Infil. Rate Area% (In /Hr) (Dec.) 0.419 0.080 0.511 0.000 0.373 0.920 Sum (F) = F 0.377 Jos . s (-F' ) RI Infil. Rate impervious RI soil ((In /Hr)) (In /Hr) D c %) AMC2 AMC -2 rate duration) (In /Hr) (for 24 0.511 0.200 56.0 56.0 loss rate 0.034 56.0 56.0 0.511 0.000 0.000 56.0 56.0 0.511 0.300 0.343 DESERTS -Curve ------------------- Adj. Infil. Rate Area% (In /Hr) (Dec.) 0.419 0.080 0.511 0.000 0.373 0.920 Sum (F) = F 0.377 Jos . s (-F' ) (In/Hr) = 0.377 Area averaged mean soil ((In /Hr)) = 0.188 Minimum soil loss rate duration) (for 24 hour storm (decimal) = 0.300 Soil low loss rate ____ ___ ________ - -- U n i t H y d r o g r a p DESERTS -Curve ------------------- Unit Hydrograph Data ---------------- Distribution Unit Hydrograph Unit time period Time % of lag Graph % (CFS) (hrs) - -. -------------------- -- - - - - - - -- - - - - - 57.461 0.504 - -- 1 0.250 312.500 37.948 0.333 2 0.500 625.000 4.591 0.040 3 0.750 937.500 100.000 Sum= 0.877 Sum = _--- ------ rate (In. /Hr) ��= °ct'z'e Unit Time Pattern Storm Rain Loss Max. Low (In/Hr) (Hr.) Percent /Hr) (In) 0113 0.377 . 0.26 1. 0.25 3.70 0.376 0377 - -- 0.377 0.11 2 0.50 4.80 88 0.4 88 0.377 - -- 0.14 3 0.75 5.10 0.518 - -- 0.377 0.12 4 1.00 a.90 0.498. __ 0.377 - 0.29 5 1.25 6.60 0.671 ___ 0.377 0.37 6 1.50 7.30 0.742 0.377 - -- 0 48 7 1.75 8.40 0.853 ___ 0.377 0.54 8 2.00 9.00 0.914 0.8'7 9 2.25 1.250 0.377 --- 0.377 - - - 1.41 10 2.50 17.60 1.788 0.377 - -- 1.26 11 2.75 16.10 1.636 - -- 0.377 0.05 12 3.00 4.20 0.427 Sum = 5.9 Sum = 100.0 1 4B ( In Flood volume = Effective rainfall ) 0 1(Ac.Ft) 0 9 (Ac .) / ( (In) ( Ft ))-- times area . 1.06(In) Total soil loss = 0 077 (Ac . Ft) Total soil loss = . = 2 . 54 (In) �� x �.� L C 5 '� 4 Total rainfall 4662.0 Cubic Feet ` Flood volume = 3359.6 Cubic Feet Total soil loss = -------------------- ---- -- peal,, drograph = 2.180(CFS) flow rate of this hy - _---- - - - - -- + + + + + + + + + + + + + ++ + + + + + + ++ + + + + + + ++ +++++++++++++++++++ F +++++++++++++++ ++ 3 - H O U R S T O R M h H y d r 0 g r a p R u n'o f f ----------------- -- ---- - - - - -- 15 Minute intervals ((CFS)) Hydrog_ r aph in --------------- --- - -- Time(h +m) - - - -- 2.5 5.0 volume Ac.Ft Q(CFS) 0 7.5 10.0 -- - - - - -- 0 +15 -------------------- 0.0242 1.17 . 0 +30 0.04B7 1.18 Q 0 +45 0.0726 1.16 Q V. I 1+ 0 0.0964 1.15 Q V1 1 +15 0.1219 1.23 Q V 1 +30 V 0.1494 1.33 Q 1 +45 0.1786 1.41. Q v 2+ 0 1.48 Q V 0.2092 . � 2 +15 � � 0.2439 1.68 Q v � 2 +30 0.2866 2.06 Q - vI 2 +45 0.3316 2.18 Q 3+ 0 0.3634 1.54 Q V 3 +15 0.3863 1.11 Q 3 +30 0.4079 1.04 Q v----- - - - - -- U n i t H y d ?" o g r a p r1 Z n a 1 Y s i s Copyright (c) CIVILCADD /CIVILDESIGN, 1989 - 2004, Version 7.0 r' l VP1�TDBBEMjDDW3100.out Study date 05/07/07 File: ...................... " .t -................... .. . . ------- - - -- - - - - - - - - - Riverside County Synthetic Unit Hydrology Method RCFC'& WCD Manual date - April 1978 Program License Serial Number 6078 English (in -lb) Input Units Used nt Values Used English Rainfall Data (Inches) nu- English Units used in output format V_- .NDEBOS TM 30399 .. SEMADW CITY OF LA QUINTA COACHELLEY VALLEY: ENGINEERS DKRICE - - --------------------- - - - - -- -- Drainage Psea = 1.02(Ac.) = 0.002 Sq. Mi. Drainage Area for Depth -Area Areal Adjustment = 0.001 Sq. Mi. USER Entry of lag time in hours Lag time = .0.080 Hr. .Lag time = 4.80 Min. 25% of lag time = 1.20 Min. 40% of lag time = 1.92 Min. Unit time = 15.00 Mir_. Duration of storm = 3 Hour (s) 1 0� (CF.S) User Entered Base _low = 2 YEAR Area rainfall data: P.rea(P_c.) [1) Rainfall (in) [2) 0.44 1.04 100.YBAR Area• rainfall data: Prea(Ac.) [1) Rainfall (in) [2) 0.44 2.54 STORM EVENT (YEPP) =' 100.00 0.44 (AC .) _ Weighting[1 *2) 0.46 Weighting[1 *2) 1.12 i i 4 G C) (in) Area Averaged 2 -Year Rainfall = 1.0(in) Area Averaged 100 -Year Rainfall = Point rain (area averaged) _ 2.540(In) Areal adjustment facto' = 100.00 Adjusted average ooint rain. = 2.540 (In) Sub -Area Data: o rious % Area(Ac.) Runoff Index Imp 56.00 0.900 0.440 0.300 0.580 56.00 Total Area Entered = 1.02(Ac.) RI RI Infil. Rate Impervious Adj. Infi1. Rate =_rea% F AMC2 AMC -2 (In /Hr) (Dec. %) (In /Hr) (Dec".) (In /Hr) 0.900 0.097 0.431 56.0 56.0 0.511 0.042 0.373 0.569 56.0 56.0 0.511 0.300 0.212 sum' (F) _ 0.254 0.254 Area averaged mean soil loss (F) (In /Hr) _ Minimum soil loss rate ((In /Hr)) = 0.127 (for 24 hour storm duration) p X50 Soil low loss rate (decimal) _ U n i t H y d r o g r a p h DESERT S -Curve --------------- -- Unit Hydrograph Data - -- Unit time period Time % of lag Distribution Unit Hydrograph Graph % (CFS) (hrs) - -- --- - - - - - -- 57.461 0.591 1 0.250 312.500 0.390 625.000 37.948 2 0.500 A.591 0.047 3 0.750 937.500 1.028 • Sum = 100.000 Sum= •----- ------------ - - - - -- Loss rate(In. /Hr) Effective Unit Time Pattern Storm Pain I Low (In /F.r) (In /Hr) Max 0.12 (gr. ) Percent 0.254 - -- 1 0.25 3.70 0.376 - -- 0.23 4.80 0.488 .0.254 0.26 2 0.50 0.254 0.518 - - -• 3 0.75 5.10 - -_ 0.24 e 1.00 4.90 0.498 0.254 0.42 6.60 0.25_ G.67i 0.49 5 1.25 0.742 0.254 - -- 7.30 - 0.60 6 1.50 B A0 0.853 0.254 0.66 7 1.75 0 0.254 --- 8 2.00 9.00 0.91_ - -_ 1.00 c 0.25- 9 2.25 12.30 1.2,50 _ -- 1.53 17.60 1.788 0.25"_ - -- 1.38 10 2.50 ,•636 0.254 it 2.75 16.10 0.17 12 3.00 4.20 __ � 0.427 0.- 5c Sum = 7.1 Sum = 100.0 �78(In) = E= iective ,ainfall 0.2(Ac.Ft) Flood volume 1.0(Ac.) /(Ft.)l = times area 0.75(.kc Total soil loss = Total soil loss = 2.5a (Ia) >> 2 I Z Cf5 a-7 Total rainfall = _ 6584.3 Cubic Feet Flood volume = 2820.2 Cubic Feet Total soil loss = ------------------ -------------- ------------- 2. 502(CFS) this hydrograPh -------------- Peak flow rate of = ---------------------- + 1-'r .............. T ......... ................... + +'r + + ....... ++ 3 - H O U R S T O R M r a p h R u H y d r e g n o f f ----------------------- in 15 Minute intervals ((CFS)) Hydr graph -- --------------------------------------------------------- --- - - - - 2 5 5 0 7.5' , Time (h +m) Volume Ac . Ft Q (Cr ) 0 10.0 • ---- - --- - -- 0 +15 ---------------- 0.0230 - --- - - - - -- 1.11 V Q I 1 0.0483 1.23 I Q I 1 0 +30 1 0i45 0.07 50 1.29 QV I I I 0.1018 1.30 I Q VI 1+ 0 1 +15 0.1306 1.39 I Q V I 1 +30 0.1617. 1.50 I Q I V 1 - 0. 19 8 1.60 I Q I V 1 Ta 5 0.2297 1.69 Q 1 V 2+ 0 I V 1 2.15 0. 2693 1.91 Q I � I Q1 V I I 2.37 I 2 +30 0.3182 _ Q i I V 1 2 +45 0.3699 2.50 1. 1 V ' _ I 3+ 0 0.4061 1.75 Q I I I I v 3 +15 0.4303 1.1-7 1 Q I �• 3 +30 0.4520 1.05 I . Q - - - - -- . �. v --------------------- ---------------------- ------------- 0 i i 1i i� J Li �J MADISON STREET CARRYING C kPACITY Per TM No. 30' 378, two catch basins are planned along the frontage of that site along the west curb line of Madison Street. The resulting Madison Street drainage area to be intercepted by this site thus includes the west t/2 of Madison Street south of the planned inlet to be located at the PC of the north return at Beth Circle. Madison Beth Circle Total area = (95' x 325') + (30' x 140') = 35,174 sf (0.81 acres) Design Q -10 year: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 1.79 in/hr (10yr — From Plate D -4.1) A, drainage area = 0.81 Acres Q(10) = 0.82 * 1.79 in/hr * 0.81 acres =1.19 CFS Design Q -100 year: C, runoff coefficient = 0.82 (From Plat D -5.7) I, rainfall intensity = 2.86 in/hr (100yr — From Plate D -4.1) A, drainage area = 0.81 acres Q(100) = 0.82 * 2.86 in/hr * 0.81 acres =1.90 CFS 1/7 Madison Street Section: 50' from ROW to centerline, 6" outer curb & gutter, 6" median curb. 34' face to face, Check Spread of Flow per FHWA HEC -22 "Urban Drainage Design Manual" . T = [(Q *n)/ ( Ku )(Sx)expl.67(Sl)exp0.5]exp0.375 Ku = 0.56, n = 0.013, Q = flow rate (cfs), T = width of flow (ft), Sx = cross slope (ft/ft) Sl = longitudinal' slope (ft /ft) '10 - Year: T = [ (1.19cfs *.013) / (.56)(.02)expl.67(.005)exp.5 ]exp.375 T = 8.15' Therefore, 10 -year flow extends from face of curb 8.15' into roadway. Flow height at outer curb is .0.25' 100 — Year: T = [ (1.90cfs * .013) / (. 56) (.02)expl.67(.005)exp.5]exp.375 T = 9.71' Therefore, 100 -year flow extends from face of cub 9.71' into roadway. Flow height at outer curb is 0.28' MADISON STRE ET DOWNSTREAM CARRYING CAPACITY The purpose of this analysis is to consider the storm flows within Madison Street, downstream of the Core Homes site. The reach considered in this analysis extends from Beth Circle (inlets along Vandenbos site intercept storm flows above Beth Circle) to the intersection of Avenue 52 ( L = 2,000 10. Madison Beth Circle (1/2 ROW + Pkwy) Total area = (75' x 2,000') + (30' x 140') = 154,200sf = 3.54acres Design Q -10 year: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 1.79 in/hr (IOyr — From Plate D -4.1) A, drainage area = 3.54 Acres Q(10) = 0.82 * 1.79 in/hr * 3.54acres = 5.20CFS Design Q -100 year: .C, runoff coefficient = 0.82 (From Plat D -5.7) I, rainfall intensity = 2.86 in/hr (100yr — From Plate D -4.1) A, drainage area = 3.54 acres Q(100) = 0.82 * 2.86 in/hr * 3.54 acres = 8.30 CFS 1/Z Madison Street Section: 50' from ROW to centerline, 6" outer curb & gutter, 6" median curb. 34' face to face (2 — 12 ` travel lanes w/ 10' outer bike lane) Check Spread of Flow per FHWA HEC -22 "Urban Drainage Design Manual" T = [(Q *n)/ ( Ku )(Sx)expl.67(Sl)exp0.5]exp0.375 Ku = 0.56, n = 0.013, Q = flow rate (cfs), T = width of flow (ft), Sx = cross slope (ft /ft) Sl = longitudinal slope (ft/ft) 10 - Year: T = [ (5.20cfs * .013) / (.56)(.02)expl.67(.005)exp.5 ]exp.375 T =14.16 Therefore, 10 -year flow extends from face of curb 14.16' into roadway. 100 — Year: T = [ (8.30cfs * .013) / (. 56) (.02)expl.67(.005)exp.5]exp.375 ` T = 16.87' Therefore, 100 -year flow extends from face of cub 16.87' into roadway Given the above calculations, during a 100 -year storm event, the amount of `dry' asphalt is: (34' — 16.87') = 17.131. During a 100 -year storm event, the depth of flow along the outer curb of Madison Street = 0.34. KIWI COURT CARRYING CAPACITY Design Q -10 year: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 1.79 in/hr (1 0yr — From Plate D -4.1) A, drainage area = 4.42 acres Q(10) = 0.82 * 1.79 in/hr * 4.42acres = 6.49 CFS Design 0-100 yean C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 2.86 in/hr (100yr — From Plate D -4.1) A, drainage area = 4.42 acres Q(100) = 0.82 * 2.86 in/hr * 4.42 acres =10.37 CFS Kiwi Court Street Section: . 40' face to face, 6" outer curb, no median curb Check Spread of Flow per FIHWA HEC -22 "Urban Drainage Design Manual T = [(Q *n)/ ( Ku )(Sx)expl.67(S1)exp0.51exp0.375 Ku = 0.56 n = 0.013 Q = flow rate (cfs) T = width of flow (ft) Sx = cross slope (ft/ft) Sl = longitudinal slope (ft/ft) 10 -Year: T = [ (6.49cfs * .013) / (.56)(.02)expl.67(.005)exp.5 lexp.375 T = 15.39 Therefore, 10 -year flow extends from face of curb 15.39' into roadway. Flow height at outer curb is 0.39' 1 100 — Year: T = [ (10.37cfs * .013) / (. 56) (.02)expl.67(.005)exp.5]exp.375 T = 18.34 Therefore, 100 -year flow extends from face of curb 18.34' into roadway. Flow height at outer curb is 0.45' 1 MADISON STREET CATCH BASIN & PIPE PREPARED BY COACHELLA VALLEY ENGINEERS DATE: 5 -30 -07 JOB #: 04220 PROJECT: TR 33085 BASIN GRATE NET EXIT LOSS LOSS AT D.S. 1-IGL10 BY: jsd "B "- 10 PIPE DIA.(IN) Q10(CFS) WS10 OPENING(FT) OPENING(SF) A; END Hv PIPE STORM DRAIN LINE: year GRATE OUTLET DESIGN (DRY WELL) 1.38 0.008 0.008 WS10 IN BASIN 500.008 18 1.19 507.33 2.00 0.008 VELOCITY IN 18 " PIPE Q= • 1.19 0.67 PER SEC. HV= V2 /2G= 0.007 HGL AT U.S. END 5— 07.346 A= 1.77 V =Q /A STORM DRAIN LINE LENGTH OF PIPE(d) 48.00 MANNING "S INDEX(n) 0.012 0.000109 TYPE OF PIPE RCP Sf =[ Q n ] 2 K' =0.463 Sf =[ 0.014280 ]2= (d 8/3(K')] ( 1.366925 ] Hf= 0.0052 Hf =L(Sf) 5 HGL AT U.S.END= 1.2HV= 0.008 10YR WS IN CB= 507.360 DESIGN FOR CATCH BASIN NO. 2 PROP. WIDTH OF OPENING (W)(FT) 4.00 H /h= 0.36 CURB HEIGHT (IN) 6.00 Q /L= 2.50 (PONDED TO TC) DEPTH OF DEPRESSION (IN) 4.00 1.19 0.48 FOOT WIDE OPENING (MIN) DEPTH OF FLOW AT OPENING (H)(FT) 0.30 Q 2 50 USE W(MIN)= 4.00 HEIGHT OF OPENING (h)(IN) 10.00 (Q1L) OK 010 TO OPENING (CFS) 1.19 TC AT OPENING 512.09 VS HGL 507.36 OK Am IMI Lm Cm AM I�Ml LMI MADISON STREET CATCH BASIN & PIPE PREPARED BY COACHELLA VALLEY ENGINEERS DATE: 5 -30 -07 JOB #: 04220 PROJECT: TR 33085 BASIN GRATE NET EXIT LOSS LOSS AT D.S. HGL100 BY: jsd STORM DRAIN LINE: "B" - 100 year PIPE DIA.(IN) Q100(CFS) WS100 OPENING(FT) OPENING(SF) AT GRATE END OF PIPE 1.1HV= 1.2HV= OUTLET DESIGN (DRY WELL) 2.00 1.38 0.020 0.022 WS100 IN BASIN 510.020 18 1.90 510.16 0.022 VELOCITY IN 18 " PIPE Q= 1.90 1.08 PER SEC. HV= V2 /2G= 0.018 HGL AT U.S. END 510.201 A= 1.77 V =Q /A STORM DRAIN LINE LENGTH OF PIPE(d) 48.00 MANNING "S INDEX(n) 0.012 TYPE OF PIPE RCP Sf =[ Q n J Sf =[ 0.022800 ]2= 0.000278 2 K' =0.463 [d 8 /3(K')J 1.366925 ] Hf= 0.0134 Hf =L(Sf) HGL AT U.S.END= 510.215 1.2HV= 0.022 100YR WS IN CB= 510.236 DESIGN FOR MADISON ST. CB PROP. WIDTH OF OPENING (W)(FT) CURB HEIGHT (IN) DEPTH OF DEPRESSION (IN) DEPTH OF FLOW AT OPENING (H)(FT) HEIGHT OF OPENING (h)(IN) Q100 TO OPENING (CFS) TC AT OPENING 4.00 H /h= 0.36 6.00 Q /L= 2.50 (PONDED TO TC) 4.00 0.30 10.00 1.90 512.09 VS HGL Q= 1.90 (Q /L) 2.50 510.24 OK 0.76 FOOT WIDE OPENING (MIN) USE W(MIN)= 4.00 OK raw ONSITE CATCH BASIN & PIPE PREPARED BY COACHELLA VALLEY ENGINEERS DATE: 5 -30 -07 JOB #: 04220 PROJECT: TR33085 BASIN GRATE NET EXIT LOSS LOSS AT D.S. HGL10 BY: jsd DRAIN LINE: "A "- 10year PIPE DIA.(IN) Q10(CFS) WS10 OPENING(FT)OPENING(SF) Al GRATE END F PIPE STORM OUTLET DESIGN (DRY WELL) 2.00 1.38 0.073 0.080 WS100 IN BASIN 507.330 24 6.49 507.33 0.073 0.080 VELOCITY IN 24 " PIPE Q= 6.49 2.07 PER SEC. HV= V2 /2G= 0.066 HGL AT U.S. END 507.482 A= 3.14 V =Q /A STORM DRAIN LINE LENGTH OF PIPE(d) 50.00 MANNING "S INDEX(n) 0.012 0.000699 TYPE OF PIPE RCP §f =[ Q n ] 2 K' =0.463 Sf =[ 0.077880 ]2= [d 8/3(K')] [ 2:946667 ] Hf= 0.0349 Hf =L(Sf) HGL AT U.S.END= 507.517 1.2HV= 0.080 10YR WS IN CB= 507.597 DESIGN FOR ONSITE CB PROP. WIDTH OF OPENING (W)(FT) 5.00 H /h= 0.36 CURB HEIGHT (IN) 6.00 Q /L= 2.50 (PONDED TO TC) DEPTH OF DEPRESSION (IN) 4.00 DEPTH OF FLOW AT OPENING (H)(FT) 0.30 Q= 6.44 2.58 FOOT WIDE OPENING (MIN) HEIGHT OF OPENING (h)(IN) 10.00 (QIL) 2.50 USE W(MIN)= OK Q10 TO OPENING (CFS) 6.44 OK TC AT OPENING 511.93 VS HGL 507.60 OK Cr cw 1� cm Lei ll� -ma ONSITE CATCH BASIN & PIPE PREPARED BY COACHELLA VALLEY ENGINEERS DATE: 5 -30 -07 JOB #: 04220 PROJECT: TR 33085 BASIN GRATE NET EXIT LOSS LOSS AT D.S. HGL100 BY: jsd STORM DRAIN LINE: "A" - 100 Year PIPE DIA.(IN) Q100(CFS) WS100 OPENING(FT) OPENING(SF) Al GIRVTE END HVPIPE OUTLET DESIGN (DRY WELL) 2.00 1.38 0.186 0.203 WS100 IN BASIN 5100.186 24 10.37 510.16 0.203 VELOCITY IN 24 " PIPE Q= 10.37 3.30 PER SEC. HV= V212G= - 0.169 HGL AT U.S. END 510.549 A= 3.14 V =Q /A STORM DRAIN LINE LENGTH OF PIPE(d) 50.00 MANNING "S INDEX(n) 0.012 0.001783 .TYPE OF PIPE RCP Sf =[ Q n ] 2 K' =0.463 Sf =[ 0.124440 ]2= [d 8/3(K')] [ 2.946667 ] Hf= 0.0892 Hf =L(Sf) HGL AT U.S.END= 510.638 1.2HV= 0.203 100YR WS IN CB= 510.841 DESIGN FOR ONSITE CB PROP. WIDTH OF OPENING (W)(FT) 5.00 H /h= 0.36 CURB HEIGHT (IN) 6.00 Q /L= 2.50 (PONDED TO TC) DEPTH OF DEPRESSION (IN) 4.00 DEPTH OF FLOW AT OPENING (H)(FT) 0.30 Q= 10.30 4:12' FOOT WIDE OPENING (MIN) HEIGHT OF OPENING (h)(IN) 10.00 (Q /L) 2.50 USE W(MIN)= 5.00 Q100 TO OPENING (CFS) 10.30 OR TC AT OPENING 511.96 VS HGL 510.84 OK Cw L_M U-� r_ LM LI LM `lam TIME OF CONCENTRATION: INITIAL FLOW: Ti = k *(L ^3/h) ^.2 where: k = 0.39 L, length of initial flow = 465 h, elevation difference over initial flow = 2 STREET CAPACITY: Q= 1.486 *A *R ^2 /3 *S ^1/2 n MADISON STREET CATCH BASIN Ti = 13.53 minutes where: A, X- sectional area of street = 8.5 sf Wetted perimeter = 34.5 R = 0.246 S, slope = 0.0050 ft/ft n, Mannings coefficient = 0.017 Q = 20.63 cfs VELOCITY. in Street: V= Q/A where: Q, capacity, cfs = 20.63 A, area, sf = 8.5 V = 2.43 fps STREET FLOW: Ts = where: L, length of flow = V, street velocity = Ts = W 465 2.43 191.63 secs 3.19 min. DESIGN Q1o: Q = C *I *A where: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 1.79 in /hr (10yr - From Plate D -4.1) A, drainage area = 0.81 AC (Drainage Map) Q = 1.19 cfs DESIGN Q100: Q = C *I *A where: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 2.86 in /hr (100yr - From Plate D -4.1) A, drainage area = 0.81 AC (Drainage Map) Q = 1.90 cfs M iiii I--�- - �"- L�- L�— Lm— �' i� � M IM M M I 1=11 TIME OF CONCENTRATION: CORE HOMES - ONSITE RUNOFF INITIAL FLOW: STREET FLOW: Ti = k *(L ^3 /h) ^.2 Ts = LN where: k = 0.39 where: L, length of initial flow = 500 L, length of flow = 430 . h, elevation difference over initial flow = 4.5 V, street velocity = 2.72 Ti = 12.02 minutes Ts = 157.82 secs 2.63 min. STREET CAPACITY: DESIGN Q1o: Q= 1.486 *A *R ^2 /3 *S ^1/2 Q = C *I *A n where: A, X- sectional area of street = 12 sf Wetted perimeter = 41 R = 0.2927 S, slope = 0.0050 ft/ft n, Mannings coefficient = 0.017 Q = 32.70 cfs VELOCITY, in Street: V= Q/A where: Q, capacity, cfs = 32.70 A, area, sf = 12 V = 2.72 fps where: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 1.79 in /hr (10yr - From Plate D -4.1) A, drainage area = 4.42 AC (Drainage Map) Q = 6.49 cfs DESIGN Q100: Q= where: C, runoff coefficient = I, rainfall intensity = A, drainage area = Q= C *I *A 0.82 (From Plate D -5.7) 2.86 in /hr (100yr - From Plate D -4.1) 4.42 AC (Drainage Map) 10.37 cfs GRAPwC SCATS 111mI Itv�K 6 n I W'v. Aewa ry �4 Q AI rl/I Cbl S t L4 t� IN THE CITY OF LA QUINTA. COUNTY OF RIVERSIDE, STATE OF CALIFORNIA TENTATIVE TRACT MAP NO. 33085 A SUBDIVISION OF A PORTION OF PARCEL 3 OF PARCEL MAP NO. 16457. FILED IN P.M.B. 100148. AND BEING A PORTION OF THE NORTHEAST QUARTER OF THE SOUTHEAST QUARTER INE 114 SE /41 OF SECTION 4. TOWNSHIP 6 SOUTH. RANGE 7 EAST OF THE SAN BERNARDINO MERIDIAN, COUNTY OF RIVERSIDE. STATE OF CALIFORNIA COACHELLA VALLEY ENGINEEP.S. INC. .lam' w 4� lal AY A¢ aA. R. rI ®. \vu• 1 1 rn a r-emw Ls / ®■r t.er•N 1 r•• I maw pp;., cps II ge ` r�aD��Jd I,/3 _.. % ? • Pa p INO 1 /JIAVIOY�t A2 Imcm ei ---- --f-"__ - -- - 8:97lY � Underground Service Alert IsOa11: TOIL FREE 1 -800 227 -2800 m oonno own IV= YOU 4 n 1•u ■rWA1C Iw Ilw�i la w o a1n c� � AI50■A TiP. H�8811 8YC[10Tf e+o AAa moa Ia a 1f1r Iw ma11s+ My mr IJeIK batmim OwN[R /APPIICANI mTZ raTx u .n : r�Tar n■m no (ION aar -an■ nccccc�P�P.f H NUMBER Tn.i7O -0I] A R Ar WWI 4.X AD .37 AC -Wr IT11 LI�RFS atzY+e�e un1Wt rvcan,dr rama srr mrmac =nVff uu ME :K u ow cn+ou el wu..®r cmwc+ .eei �� W1a1111A 11■Irr II ,l �. �OOL1 ZZONE rtaoP me a>51w1iAl Y - a 119 MfW AT 11% 11oO A IC atEDlti WLt -1011 Low aDeu'+ts'0.9■. o-0 R= WM - \Gr 101106lf/ I[9�C11>Hl 1N 4G �M'. WAV m c`um f�61RICT 1H1',MA$ G II[, r,oRnINAAES 'm Imm a1P /111: n.m am o-7 TOP(1� GRAPHY ana aaKr /nea■tO O/ L01va1A 11LLIEr aR•M'lli /� mmnslt �'+ol PASTSPASg O�BEARI„�;,�4GS OI M Pfl �QL Li0/COOIA O+MIRar .PLI/IJ lY YL A IR R)f 1.AMh•n ITO� MI11.4 MP /6 1 /ICI. 1� N PL. Iooqq A1� K OlG OoWl/• 11' 1M16aC aarE 1Y ytJ•Ja!el /m nml " yr po 4m s /s Wert r•r r�:M1 :i■trT�J din r!rT.:7{R�� {r"IYL�r1TJ 0 VICINITY MAP„ PRELIMINARY' NOT FOR CONSTRLIC' a nc on or u ouxlw cn.�« A.P.11. /7i -7r1 " TENTATIVE TRACT MAP NO. 33085 �• p ranE louts.ut o- "' aae 01wo m ■m"m As AwS ■ ' R A 1a■■OIf. J Jem a LOOM ![r 1' Y! W U1 YN ®LL � p JNPa! l0 ccrlw C 1.■ IGa yq TAP lT O(1 Lea ■A1 Q CAI TAM1 -A {WA -� Mc..Vxwm Lm - -_-. r/. L Off -___- LAS L'S Laf ordv 1K Uc - - - - wamrl L/c -�cn— am V6 aa.cn as LIZ —n,— auL lvm Lm —.,w -- -e- aorrmzr L[a111 rtat Zy rm1>rrnv o 'o" ■0" k n e OII na Mr 1Pt batmim OwN[R /APPIICANI mTZ raTx u .n : r�Tar n■m no (ION aar -an■ nccccc�P�P.f H NUMBER Tn.i7O -0I] A R Ar WWI 4.X AD .37 AC -Wr IT11 LI�RFS atzY+e�e un1Wt rvcan,dr rama srr mrmac =nVff uu ME :K u ow cn+ou el wu..®r cmwc+ .eei �� W1a1111A 11■Irr II ,l �. �OOL1 ZZONE rtaoP me a>51w1iAl Y - a 119 MfW AT 11% 11oO A IC atEDlti WLt -1011 Low aDeu'+ts'0.9■. o-0 R= WM - \Gr 101106lf/ I[9�C11>Hl 1N 4G �M'. WAV m c`um f�61RICT 1H1',MA$ G II[, r,oRnINAAES 'm Imm a1P /111: n.m am o-7 TOP(1� GRAPHY ana aaKr /nea■tO O/ L01va1A 11LLIEr aR•M'lli /� mmnslt �'+ol PASTSPASg O�BEARI„�;,�4GS OI M Pfl �QL Li0/COOIA O+MIRar .PLI/IJ lY YL A IR R)f 1.AMh•n ITO� MI11.4 MP /6 1 /ICI. 1� N PL. Iooqq A1� K OlG OoWl/• 11' 1M16aC aarE 1Y ytJ•Ja!el /m nml " yr po 4m s /s Wert r•r r�:M1 :i■trT�J din r!rT.:7{R�� {r"IYL�r1TJ 0 VICINITY MAP„ PRELIMINARY' NOT FOR CONSTRLIC' a nc on or u ouxlw cn.�« A.P.11. /7i -7r1 " TENTATIVE TRACT MAP NO. 33085 �• p ranE louts.ut o- "' aae IN THE CITY OF LA QUINTA, COUNTY OF RIVERSIDE, STATE OF CALIFORNIA ETENT10"N BASIN CONTOURS. TRACT MAP NO. 33085 IN THE NE1 /4 OF THE SE1 /4 OF SECTION 4, T.6S., R.7E. SBM I RETENTION BASIN CAPACITY q- 0 WATER, DEPTH - 0 C. F. I I TC 511.79 I' WATER DEPTH - 3,504 C. F. . \ 2' WATER DEPTH - 7,993 C. F. 3' WATER DEPTH - 13,584 C. F. 4' WATER DEPTH - 20,J94 C.F. 5' WATER DEPTH - 28,541 C. F. 1 FT. FREEBOARD s � s ro\ \ I FG 5 / Jo 1 FT. FREEBOARD a'o `ro 0 GRAPHIC SCALE 20 0 10 20 40 ( IN FEET ) 1 inch = 20 ft. LOT "E" 10,366 S.F. L.S. /RET. TOP 511.10 WS 509.93 BOT 505.10 60 OVERFLOW TO STREET BOT 505.10 TOP 511.10 04220 1 IN THE CITY OF LA QUIN►A, CALIFORNIA ` •1L ■ L�U'y o�o�o C'VE CORE. .HQNES, LLC_ TTM 33085 TEL(760)360 -4200 FAX(760)360 -4204 Coachella Valley Engineers 77 -899 Wolf Road, Suite 102, Palm Desert, CA 92211 / QjpFESS /c' /e F�c y a� WrM NO. 35728 EXP. 6-30-05 9fF C I V OF CP`\ i W 0 W w DAVID K. RICE - RCE 35728 - - EXPIRES 6 -30 -05 AVENUE 1 50 VISTA BONITA TRAIL DTIE T 5S. T 6S. W AVENUE 51 OLD ORCHARD LANE BETH CIRCLE Z: 0 'o AVENUE I 52 I VICINITY MAP N.T.S. CORE HOMES June 28, 2006 HYDROLOGY AND DRAINAGE REPORT ®KE u 4Q 0@0@9 9 HYDROLOGY AND DRAINAGE FACILITY DESIGN REPORT INDEX Cover Sheet i Index Hydrology and Drainage Facility Design Report Location Map — Predevelopment Drainage Area Map — Post Development Soil Conservation Service Aerial Map Retention Basin Storage Summary Data Appendix 1. Soil Engineer Percolation Report 2. Storage Hydrograph Calculation Spread Sheets 3. Retention Basin Design Procedure 4. CVE Design Calculations Deep Well Percolation 5. Offsite Drainage Topography Map 6. Madison Street Storm water Flows 7. Los Angeles County Road Department Flow Nomograph 8. NOAA 3, 6 and 24 Hr Storm Volume Precipitation Table 9. Riverside County Hydrology Manual (RCAM) Excerpts: a )10 and 100 Year Storm Intensity Duration Table b) Rainfall Pattern Table c) Pervious Area Runoff Index Table d) Impervious Cove r /Develo.pment Table e) Runoff Coefficient Curve f) Initial Sub -area Time Of Concentration Homograph 10. City of La Quinta Deep Well Percolation Chamber FINAL HYDROLOGY AND DRAINAGE REPORT TM 33085 JUNE 28, 2006 TRACT MAP 33085 HYDROLOGY REPORT INTRODUCTION AND PROJECT INFORMATION The project is located north of Avenue 52, west of Madison Street and south of Beth Circle. The project consists of a 4.76 Acre parcel being developed into 7 lots, each approximately 0.5 acres in size. HYDROLOGY The drainage area map utilized with this report is attached the attached Tentative Map 33085. The drainage area to be analyzed includes Beth Circle Street Drainage and the 50.00 feet of Madison Street adjacent to the project. The total drainage area is 4.76 acres. The storm volume of 1.79, 2.29, 2.77, and 3.79(4.5) inches for the duration of the 1 hour, 3 hour, 6 hour, and 24 hour / 100 year storm frequency respectively, is for design of the retention basins. '1 The storm volumes are obtained from the Point Precipitation Frequency Estimates from DOC /NOAA/National Weather Service Office of Hydrologic JDevelopment, Hydro meteorological Design Studies Center, W /OHD13 at 1325 East -West Highway Silver Spring, MD 20910 -3283 0- The hydrologic soils group map for the Coachella area is included in the appendix of this report. The soil type is a sandy, silty, loamy Indio soil, I -S, and Gilman B Soil, common in this area. 1 The soil classification for the site is type "B ", having high infiltration rates, antecedent moistening conditions rating of AMC 11 and low runoff potential when saturated. ' The percolation tests have been performed on the site by Landmark j Engineering Geo Technical, LCI, Report No. LP05057. Tests result showed a percolation rate of 13.0 gals /hr /sf or 20.8 in /hr /sf. Per City of La Quinta standards, 2.0 inches per hour will be used. A City of La Quinta newly adopted "deep well percolation well system" will be installed in the retention basin. ( see attached detail in appendix).. tl �J The site Runoff Index number of the hydrologic soil cover complex, for the pervious area (AMC 11), is RC 56. This is for residential landscaping on Group B soils, with 50% impervious cover from RCHM plat D -5.5. The pond storage is based on the 100 year, 24 hour rainfall event. Attached are calculations detailing the capacity of the retention basins for the 3hr, 6hr and 24hr events. HYDRAULICS The runoff from the site will flow down the streets to a retention basin in the southeast corner of the site. Should the retention basin for the streets overflow, water will drain south and east towards Madison Street. Coachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 2 of 7 JUNE 28, 2006 MADISON OFFSITE STREET FLOWS ' City of La Quinta has requested an offsite analysis of the storm water collection capacity of Madison Street at the TM 33085 and the resulting impact on downstream flows. In particular, staff has requested an analysis of the ' intersection of 52nd Avenue and Madison Street. ' Reference to attached Plate A -1 , offsite USGS topographic map for the Madison Street Drainage Area. We can analyze the geography and topography elevations to conclude that at present all storm water and un- improved site drainage north of 50th street will drain to the east of Madison Street intersection and north of 50th Street. This condition has been field verified by visual site observation. South of 50th Street to the east of Madison Street, I have conducted a preliminary drainage analysis of the, Polo Ground territory. This ground is self ' containing when analyzed for site runoff drainage. I have estimated that approximately 18 acres drains onto the Madison Street Drainage. I have disregarded the drain ditch on the easterly Madison Street right '! to. way and concluded that all offsite drainage from the Polo Ground Territory will • be carried by Madison Street final section of street improvement (ROW = 100.00 ft i Westerly offsite drainage including the Van De Bos TM 30378 primarily drains to —1 the west and is carried along by the foothill drainage pattern of the All American Canal. J Coachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 3 of 7 JUNE 28, 2006 For design purposes of —1 M 30385, 1 have concluded that the Beth circle drainage .� collection street and the 50.00 feet of Madison adjacent to the tract will be stored in the "on site" retention basin.. I Offsite drainage area for Madison Street to the north of TM 33085 is (100 x 3200 _ "620,000 SF ( 7.35 AC..) b For future evaluation purpose as reques ted y City of La Quinta Engineering -' Staff, I will evaluate the drainage capacity and volumetric condition for Madison Street. See Appendix Section. CONCLUSION 1. ON SITE RETENTION BASIN STORES 25,725.6 CF OF STORAGE FOR THE 100 YEAR 24 HOUR STORM FOR PROJECT SITE TO CL MADISON STREET. i 2. MADISON STREET FUTURE 100 FEET RIGHT OF WAY AS IMPROVED WILL CARRY THE 100 YEAR STORM FLOW IN THE STREET SECTION! AT A DEPTH OF 0.50 FEET. 3. MADISON STREET UPSTREAM OFFSITE DRAINAGE WILL NOT . OVERFLOW ABOVE THE ROW ELEVATION OF 513.00 DURING A 100 YEAR STORM. tl 4. MADISON STREET UPSTREAM OFFSITE DRAINAGE WILL FLOW TO THE INTERSECTION OF 52ND AND MADISON STREET AND FLOW EASTERLY ON THE NORTHERN RIGHT OF WAY OF 52ND AVENUE. Coachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 4 of 7 K. 28, 2006 \ ' _ •II 0: LID :L' i II II•• •�f'0 IIII I II II n __ •— 19 ,AI low -7 .. i _, II If • _._.y,.;a,,....,,.;;.,,,,,, -'W AiI _- 1 11 1S '. .'. N H �21orH'•.. -�"�s� iu 1 --- ..IYN b'JT .. ..� ............. .I,•, ... h = = -tea• = av =a =v l• == ....................... rlll3tf7VOO r.1 •• IboSloD'W °e _ Q(� 7� =='I 1S an It • � 11 II 11 --------- -- co O�= aaaa= _ir.Tv > �t n m u •�n ii Ld La C O •= �� / - /� /V `' II it 11 •. _ : r ---' -� � is � ••O �J Q O ;., N0S213dj��' l It n if n �••• if CL Sv.. 11 II II n n n n - i •: 11 n 11 11 ' :m •Qi.L,t � •. .. ,•. aa== a= c�a= agraaa = = =a_ _a_ - -_ __° ._ ........ CL OS '•il II -.. -.. \\ • �� 11 II bO'... -• n .. 0 II 11 11 t n If 0 0O .. ... -. - _ -CO J II .. - *1 .. ; 2 In n II II u O II !I II If rl u 1 •: O i ±� = __ m�— •1 N,C'4.:?Ph1H5VlA �I rte— �\ . ... er s I °• s! /off �On L • • ; '..� �v 1.1.x/..\• ''•. -:..0 .. �• �...,�..., '� � �—`�1 a S rte`• • Imo_ Reference: USGS Topographic Map La Quinta, CA Quadrangle Scale 1:25,000 LAND-MARK Project No.: LP05057 Topographic Map Site Coordinates Lat: 33.675N Long: 116.253W Plate A4 ) ......... /___ U ............ .................. .......... ..... .. .... 3 3 ....... uE 14 ......... .... ... C A A IL ........... ......... ............ J, . ... .... ........... .............. y ......... .. ......... ...... ...... It .......... . ..... •t i ........... . . ....... 2 :L .............. ........... Rx 0 ............. ....... ; MR A.,FF) ....... w Project Sitd ..., ...... .......... .......... LIZ AVF.',4UC Reference: USGS Topographic Map La Quinta, CA Quadrangle Scale 1:25,000 LAND-MARK Project No.: LP05057 Topographic Map Site Coordinates Lat: 33.675N Long: 116.253W Plate A4 MAN V. LANDMARK Project No.: LP05057 USDA Soil Conservation Plate Soil Service Map A-3 1, � I � I 1 1 Coachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 5 of 7 January 05 ( i i h y y 11 f. �x• �� ti$ a li A� P Y`j" yyY,^LSA:+j{ ��: Gea�agineers andlo�c ists{�w r`"-��x.i'{•.'.'J"rc?i?f -ai+Y 41Q�?`art "�.�''v aSa iT9�+ nl?".irt. `: ?��t Company 11 Mr. David Neale Core Homes, LLC 470 S. Market Street San Jose, CA 95113 Geotechnical Investigation Tentative Tract No: 33085 . 4.4 -acre Property La Quinta, California LCI Report lino. LP05057 Dear Mr. Neale: 780 N. 4th Street El Cantrc), CA ) = ^_243 ; (760 370 -3000 1760) 337 -6900 fax 77 -948 Wildcat Drive Palm Desert. CA 92211 ;760) 36Q-06e5 (760) 360 -0521 fax This geotechnical report is provided for design and construction of the proposed single family residential development located on the southwest comer of Beth Circle and Madison Street, between Avenue 51 and Avenue 52 in La Quinta, California. Our geotechnical investigation was conducted in response to your request for our services. The enclosed report describes our soil engineering investigation and presents our professional opinions regarding geotechnical conditions at the site to be considered in the design and construction of the project. The findings of this study indicate the site is underlain by interbedded silty sands, sandy silts, and clayey sandy silts with near surface silty sands. The subsurface soils are very loose to medium dense in nature. Groundwater was not encountered in the borings during the time of field exploration. Elevated sulfate and chloride levels were not encountered in the soil samples tested for this study. However, the soil is moderately corrosive to metal. We recommend a minimum of 2,500 psi concrete Type H Portland Cement with a maximum water /cement ratio of 0.60 (by weight) should be used for concrete placed in contact with native soils of this project. We did not encounter soil conditions that would preclude implementation of the proposed project provided the recommendations contained in this report are implemented in the design and construction of this project. Our findings, recommendations, and application options are related only through reading the full report, and are best evaluated with the active participation of the engineer. of record who developed them. If Tentative Tract No. 33085 — La Ouinta, CA LCI Report No. LP05057 The collapse potential test indicated a slight risk of collapse upon inundation at the project site. Therefore, building foundations are not required to include provisions for mitigating the hydroconsolidationcauwd by soil saturation from landscape irrigation or broken utility lines. 3.8 Soil Infiltration Rate A total of two (2) infiltration tests were conducted on May 19, 2005 at the proposed location for the stormwatef retention basin as shown on the Site and Exploration Plan (Plate A -2). The tests were performed using pipes inside 6 -inch diameter hand auger boreholes made to depths of approximately 3 feet below the existing ground surface, corresponding to the anticipated bottom depth of the stormwater retention basin. The pipes were presoaked and filled with water and successive readings of drop in water levels were made for a total elapsed time of 360 minutes, until a stabilization drop was recorded. A soil infiltration rate of 13.0 gallons per hour per square foot of bottom area may be used for infiltration design. An oil/water separator should be installed at inlets to the stormwater retention basin to prevent sealing of the basin bottom with silt and oil residues. We recommend additional testing should be performed after the completion of rough grading operations, to verify the soil infiltration rate. Landmark Consultants, Inc. Page 9 CORE HOMES TM 33085 Retention Basin Design Procedure Coachella Valley Engineers Spread Table Program cve 04220 Following is an explanation of the calculation procedure of the Excel Spread Table program used by CVE to quickly and accurately size Retention Basins. 1) The Drainage Area map is developed from the Precise - grading plan. 2) Tributary areas displayed near the top of Table 2 are electronically measured from the Drainage Area map /grading plan. 3) The soil names and symbols for the site, listed near the top of Table 2, are copied from the US Soil Conservation Service Soil Survey Map. The corresponding Hydrologic Soil Group designations, (usually*A or B in the Coachella Valley), are determined from table 12 of the SCS Survey. 4) The design Percolation rate listed near the top of Table 2 is usually either 1/2 of the lowest test value in the Soils Report, or a lower rate dictated by the City. For large sites, the nearest test results may be averaged or interpolated for each particular basin location, with city approval. 5) The total rainfall volume for each design storm, entered at the top of Table 2, is excerpted from the Precipitation Frequency Estimate Table, Atlas 14, contained in the NOAA website, 6) The storm period was arbitrarily chosen as 15 minutes for the 3 and 6 -hour storms and 60 minutes for the 24 -hour storm to provide enough points to plot a smooth storage -vs. -time hydrograph curve. 7) The precipitation % data is copied from the RCFD Manual, plate E.5.9, for each storm period and is entered in column 2 of the data table on Table 2. 8) The storm intensity I for each storm period is automatically calculated by multiplying the storm volume of 7 above by the precipitation % in column 2 and listed in column 3 of Table 2. 9) The period runoff coefficient C listed in column 4 on Table 2, is computed from data taken from the RCFCD manual, plate D -5.1; 5.2, 5.3, or 5.4, for the .appropriate Hydrologic Soil Group, A, B, C or D. 10) The period rainfall runoff rate Q listed in Column 5 of Table 2 is computed by multiplying the runoff and intensity data in columns 3 and 4 and the tributary area. 11) The period rainfall runoff inflow volume listed in column 6 on Table 2 is calculated by converting Q from cfs to cubic feet per storm period 12) Retention Basin contour areas listed in column 2 of the Retention Basin Storage table at the top of Table 1 are electronically measured and /or calculated at one -foot vertical intervals from the Drainage Area Map or the grading. plan. 13) The available storage area and volume data listed in columns 3, 4, & 5 of the Storage table are automatically computed from the contour area data. Last updated 09 -09 -05 Pale 1 of 2 I �J cve 04220 CORE HOMES TM 33085 14) The period percolation outflow volume for each storm period listed in column 8 on Table 2 is calculated from the percolation rate and the retention basin water surface area from column 8 of Table 1. 15) The period cumulative runoff inflow volume listed in column 7 on Table 2 is determined by subtracting the previous periods percolation outflow, listed in column 8, from the sum of the current period inflow listed in column 6, and the previous period cumulative inflow listed in column 7. 16) The period required retention volume listed in column 10 on Table 2 is the result of subtracting the current period percolation outflow, listed in column 8, from the current period cumulative inflow listed in column 7. 17) The time required to empty the basin after the end of the design storm, shown at the bottom of Table 1, is calculated by continuing the required retention volume computation after the end of the design .storm, with zero inflow but continuing percolation outflow, until the retention basin is empty. 18) The retention basin water depth listed in column 7 is the sum of the partial water depths from columns 2 to 6. The water depth for each storm period and vertical foot of basin, listed in columns 2 to 6 in Table 1, is calculated by comparing the required cumulative retention volume from column 10 on Table 2 to the available cumulative retention storage volume for each vertical foot of site retention basin storage, from column 5 of the Storage Table. The difference in the values is proportioned to calculate the depth of required storage for each period and vertical foot. 19) 'The surface area of the required storage for each period, listed in column 8 of Table 1 is calculated from the water depth listed in column 7 and the surface areas listed in columns 2 and 3 of the storage Table. 20) The storage curve on Table 1 is the plot of the completed data from.columns 1 and 10 of Table 2, and clearly shows relationship of storm duration to peak storage requirement. 21)' An Elevation Data Table is provided adjacent to the basin storage graph. This data lists the important elevations and shows the relationships between building floor, street TC, FL, and EP, ultimate outflow, maximum retention water surface, and basin bottom elevations. Page2of2 Last updated 09 -09 -05 STORAGE HYDROGRAPH FOR 100 YEAR / 24 HR STORM RETENTION BASIN. PREPARED BY COACHELLA VALLEY ENGINEERS SUBJECT 124 HOUR STORM ADDENDUM ANALYSIS JOB # 04220 T.M. 33085, W of Madison & S of Beth Circle DATE: 9/13/05 BY: DKR TRIB AREA PERC.RATE STORM VOLUME 4.7600 ACRES 2.00 IN /HR 4.50 IN /24HR SHEET 2 OF 2 SOIL GROUP "B ", AMCII, R.I.= 32, R.C. =50 %, PRECIP INTENSITY IMPERV FLOW Q INFLOW VOL /Hr CUML VOL OTHER OUTFLOW PERC /Hr OTHER RETENTION REQD CUML VOL PERIOD 1 100 C (CF) (CF) (CF) (CF) (CF) (CF) (1 Hr) % (IN /Hr) RC =50% (CFS) 0.477 0.123 441.3 441.3 0.0 593.0 0.0 0.0 1 1.2 0.054 479.7 479.7 0.0 630.0 0.0 0.0 2 1.3 0.059 0.478 0.133 675.1 795.2 675.1 0.0 667.0 0.0 8.1 3 1 •g 0.081 0.486 0.188 803.3 0.0 704.0 0.0 99.3 4 2.1 0.095 0.491 0.221 1084.1 1126.3 1517.4 1881.6 2707.0 3712.7 3067.3 3225.4 5230.9 5604.6 4986.6 1183.4 0.0 741.0 0.0 442.4 5 2.8 0.126 0.502 0.301 1568.7 0.0 778.0 0.0 6 2.9 0.131 0.504 0.313 2308.2 0.0 815.0 0.0 14493.93. 2 7 8 g 9 11 12 13 3.8 4.6 6.3 8.2 7.0 7.3 10.8 11.4 10.4 0.171 0.207 0.284 0.369 0.315 0.329 0.486 0.513 0.468 0.518 0.530 0.557 0.587 0.568 0.573 0.628 0.638 0.622 0.422 0.523 0.752 1.031 0.852 0.896 1.453 1.557 1.385 3374.7 0.0 852.0 0.0 2522.7 5229.8 8039.4 0.0 0.0 903.0 958.0 0.0 0.0 4326.8 7081.4 10148.8 0.0 1006.0 0.0 9142.8 12368.1 0.0 1092.0 0.0 11276.1 16507.0 0.0 1178.0 0.0 15329.0 20933.6 24562.2 0.0 1358.0 0.0 19575.6 14 0.0 0.0 0.0 0.0 1358.0 1358.0 1358.0 1448.0 0.0 0.0 0.0 0.0 23204.2 25725.6 24885.9 24152.8 15 8.5 1.4 1.g 1.3 1.2 0.383 0.063 0.086 0.059 0.054 0.592 0.480 0.488 0.478 0.477 1.078 0.144 0.199 0.133 0.123 0.112 0.101 0.091 0.081 3879.5 518.2 714.9 479.7 441.3 403.2 365.3 327.7 290.3 27083.6 26243.9 25600.8 24632.4 23625.7 22580.9 21588.2 20557.9 16 17 1 g 0.0 0.0 0.0 0.0 1448.0 1448.0 1358.0 1358.0 0.0 0.0 0.0 0.0 23184.4 22177.7 21222.9. 20230.2 19 20 21 22 23 24 1.1 1.0 0.9 -0- .8 0.050 0.045 0.041 0.036. 0.475 0.474 0.472 0.471 0.0 1178.0 0.0 19379.9 19670.2 0.0 1178.0 0.0 18492.2 SUBJECT 124 HOUR STORM ADDENDUM ANALYSIS JOB # 04220 IT.M. 330851 W of Madison & S of Beth Circle DATE: 9113/05 RETENTION BASIN STORAGE AND DEPTH CALCULATIONS SHEET 1 OF 2 BY: DLC WATER SURFACE AREA ADJ.AREA 17ELLEV. CHANGE (Avg) VOL 3740.000 AREA (FT) (SF) (SF) (CF) (CF) (SF) 0.000 0.00 D =5.00' 8846 1397 8148 28541 ELEVATION DATA D =4.00' 7449 1278 6810 20WBotElev 0.000 513.90 D =3.00' 6171 1160 5591 13512.00 0.000 0.000 D =2.00' 5011 1044 4499 7Slope 7 511.10 1.00' 3987 927 3514 3N/A 0.000 0.000 jD= o. oo' 3040 0.000 0 0.000 0.386 509.93 0.000 0.000 0.008 0.000 11 505.10 0.386 0.000 12 WATER DEPTH 0.000 0.783 PERIOD D= 4' -5' D= 4' -5' D= 4' -5' D= 1'-2' D= 0' -1' DEPTH SHEET 1 OF 2 BY: DLC WATER SURFACE AREA ADJ.AREA 17ELLEV. 0.000 0.000 0.128 0.139 0.195 0.231 0.340 0.449 0.660 0.963 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.13 0.14 0.19 0.23 0.34 0.45 0.66 0.96 1.39 2.01 2.39 2.78 3.43 4.07 4.51 4.83 4.72 4.64 3159.05 3169.17 3220.72 3254.55 3354.82 3456.47 3651.54 3932.90 5458.54 5020.63 5458.27 5918.74 6719.55 7541.68 8163.82 7062.00 8452.15 8341.89 3159.05 3169.17 3220.72 3254.55 3354.82 3456.47 3651.54 3932.90 5458.54 5020.63 5458.27 5918.74 6719.55 7541.68 8163.82 7062.00 8452.15 8341.89 505.23 505.24 505.29 505.33 505.44 505.55 505.76 506.06 506.49 507.11 507.49 507.88 508.53 509.17 509.61 509.93 509.82 509.74 INC INC INC INC INC INC INC INC INC INC INC INC INC INC PEAK DEC DEC 1 0.000 0.000 2 0.000 0.000 0.000 0.000 3 0.000 0.000 0.000 0.000 4 0.000 0.000 0.000 0.000 5 0.000 0.000 0.000 0.000 6 T. 0.000 0.000 0.000 7 0.000 0.000 0.000 0.000 8 0.000 0.000 0.000 0.000 9 0.000 0.000 0.000 0.386 10 0.000 0.000 0.008 0.000 11 0.000 0.000 0.386 0.000 12 0.000 0.000 0.783 0.000 13 0.000 0.429 0.000 0.000 14 66 0.000 0.000 0.000 15 12 0.000 0.000 0.000 16 21 rn 0.000 0.000 0.000 0.000 17 18 0.000 0.000 18 .39 0.000 0. 000 0.000 0.000 0.000 0.000 0.000 1 0.000 1 0.000 4.52 4.40 4.27 4.15 4.02 1 3.89 8175.86 8003.26 7824.12 7653.92 7477.27 7313.17 8175.86 8003.26 7824.12 7653.92 7477.27 7313.17 509.62 509.50 509.37 509.25 509.12 508.99 DEC DEC DEC DEC DEC #REF! 19 0.520 0.000 0.000 0.000 20 0.397 0.000 0.000 0.000 21 0.269 0.000 0.000 0.000 22 0.147 0.000 0.000 0.000 23 0.0 20 0.000 0.000 1 0.000 0.000 24 0.000 0.894 0.000 FOR 100 YEAR / 6 HR STORM RETENTION BASIN. SHEET 2 OF 2 _ STORAGE HY®ROGRAPH PREPARED BY COACHELLA VALLEY ENGINEERS SUBJECT 61-Ir /100Yr -Core Homes - La Quinta IT.M. 33085, W of Madison & S of Beth Circle - La Quinta JOB # 04220 DATE: 9/13/05 BY: DKR TRIB AREA 4.7600 ACRES SOIL GROUP "B ", AMCII, R.I.= 56, R.C. =50% PERC.RATE 2.00 IN /HR (0.5 IN/15 Min) STORM VOLUME 2.77 IN /6HR 100 YEAW 6 UR P A -57 INFLOW OUTFLOW RETENTION PERIOD PRECIP INTENSITY IMPERV FLOW VOLC� Min COME O(CHE)R PE O(CHE)R R(Q) CUML VOL 1 100 C =50% Q (CFS) (CF) FjOL (CCIF�Min (15min) % (IN /15min) RC 1 1.7 0.047 0.464 0.10M13 0 0 593.0 630.0 2 1.9 0.053 0.466 0.11105.0 05. 0.0 0.0 667.0 0.0 0.0 3 2.1 0.058 0.467 0.12116.5 0'0 704.0 0.0 0.0 4 2.2 0.061 0.468 0.13122.3 0'0 741.0 0.0 0.0 5 2.4 0.066 0.470 0.14133.8 133.8 0'0 778.0 0.0 0.0 6 2.4 0.066 0.470 0.149 133E145.5 8 133.8 0.0 815.0 7 2.4 0.066 0.470 0.149 8 139.7 0.0 852 0 0.0 0.0 g 2.5 0.069 0.471 0.155 7 145.5 903.0 0.0 0.0 9 2.6 0.072 0.472 0.162 15.11 10 2.7 0.075 0.472 0.168 4 15.3 157.3 2.8 0.078 0.473 0.175 169.1 169.1 0.0 1092.0 0.0 0.0 12 3.0 0.083 0.475 0.188 181.0 181.0 0.0 1178.0 0.0 0.0 13 3.2 0.089 0.477 0.201 205.0 205.0 0.0 1358.0 0.0 0.0 14 3.6 0.100 0.480 0.228 247.9 247.9 0.0 1358.0 0.0 0.0 15 4.3 0.119 0.486 0.275 272.8 272.8 0 0 1358.0 0.0 0.0 16 4,7 0.130 0.489 0.303 317.1 317.1 0'0 1358.0 0.0 0.0 17 5.4 0.150 0.495 0.352 369.0 369.0 0.0 1358.0 0.0 0.0 18 6.2 0.172 0.502 0.410 415.4 415.4 0'0 1448.0 0.0 0.0 19 6.9 0.191 0.507 0.462 456.0 456.0 0.0 1448.0 0.0 0.0 20 7.5 0.208 0.512 0.507 676.8 676.8 0.0 1448.0 0.0 21 10.6 0.294 0.538 0.752 981.6 981.6 0.0 1358.0 0.0 L 22 14.5 0.402 0.570 1.091 193.0 193.0 1178.0 0.0 23 3.4 0.094 0.478 0.214 54.4 0 0 1178.0 0.0 0.0 24 1,p 0.028 0.458 0.060 54.4 I L■ �■ ; -■ - �■■-�� fir- �_w- Tom■ L■r L■■ L■I L- i �■■ w -■� -■■ ■ : �■ SUBJECT 6Hr /100Yr -Core Homes - La Quinta JOB # 04220 T.M. 33085, W of Madison & S of Beth Circle - La Quinta DATE: 9113/05 BY: DKR RETENTION BASIN STORAGE AND DEPTH CALCULATIONS JCr e e e .-,. ...... .. - -- ' CHANGE (Avg) VOL AREA ). �.4 ;F �'y .�, -�u� (SF) (SF) (CF) (CF) (SF) 0.00 (FT) D =5.00' 8846 1397 8148 27224 ELEVATION DATA D =4.00' 7449 1278 6810 20414 PE Lot 6 513.90 D =3.00' 6171 1160 5591 13064 Overflow 512.00 D =2.00' 5011 1024 4499 8013 TO SIO e 512.00 6=1.00' 3987 947 3514 3514 CB WS A D =0.00' 3040 0 0 WS Elev 505.15 Bot Elev 505.10 PERIOD WATER DEPTH D= 4' -5' ;;(.FT) 3' -4' D= 2' -3' D= V -2' D= 0' -1' DEPTH (15 Min) (FT) (FT) (FT) (FT) (FT) 1 0.000 000 0.000 0.000 0.027 0.03 2 0.000 0.000 0.000 0.000 0.030 0.03 3 0.000 0.000 0.000 0.000 0.033 0.03 4 0.000 0.000 0.000 0.000 0.035 0.03 5 0.000 0.000 0.000 0.000 0.038 0.04 6 0.000 0.000 0.000 0.000 0.038 0.04 7 0.000 0.000 0.000 0.000 0.038 0.04 8 7000 0.000 0.000 0.000 0.040 0.04 9 0.000 0.000 0.000 0.000 0.041 0.04 10 0.000 0.000 0.000 0.000 0.043 11 0.000 0.000 0.000 0.000 0.045 0.04 12 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.048 0.051 0.05 0.05 13 14 0.000 0.000 0.000 0.000 0.000 0.000 0.000 7000 0.000 0.000 0.000 0.000 0.000 0.000 0.058 0.070 0.077 0.090 0.06 0.07 0.08 0.09 15 16 0.000 0.000 17 18 0.000 0.000 0.000 0.000 0.105 0.10 19 20 21 22 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.118 0.130 0.192 0.279 0.055 0.12 0.13 0.19 0.28 0.05 23 0.000 0.000 0.000 0.000 0.015 0.02 24 0.000 0.000 0.000 0.000 SHEET 1 OF 2 WATER SURFACE AREA ADJ.AI , -e `r � 4 "tea elf ). �.4 ;F �'y .�, -�u� .YyR,:•f{�. ).J O - . r.y;,.�.�..�.,..�� .-:+,r 2. Jrt ), '�'..,�J..��- �+•'3•�..,. 3065.10 65.10 3068.17 68.17 3071.26 23071.26 W505.14INC 3072.82 072.82 3075.94 3075.94 3075.94 3075.94 505.14 FALSE 3075.94 3075.94 505.14 FALSE 3077.51 3077.51 505.14 INC 3079.08 3079.08 505.14 INC 3080.66 3080.66 505.14 INC 3082.25 3082.25 505.14 INC 3085.44 3085.44 505.15 INC 3088.64 3088.64 505.15 INC 3095.12 3095.12 505.16 INC 3106.67 3106.67 505.17 INC 3113.38 3113.38 505.18 INC 3125.34 3125.34 505.19 INC 3139.32 3139.32 505.20 INC 3151.83 3151.83 505.22 INC 3162.76 3162.76 505.23 INC 3222.30 3222.30 505.29 INC 3304.45 3304.45 505.38 PEAK 3091.87 3091.87 505.15 DEC 3054.52 3054.52 505.12 #REF! ela:5 e ME WATER SURFACE AREA ADJ.AI ELEV. (SF) (SF) (FT) 3065.10 65.10 3068.17 68.17 3071.26 23071.26 W505.14INC 3072.82 072.82 3075.94 3075.94 3075.94 3075.94 505.14 FALSE 3075.94 3075.94 505.14 FALSE 3077.51 3077.51 505.14 INC 3079.08 3079.08 505.14 INC 3080.66 3080.66 505.14 INC 3082.25 3082.25 505.14 INC 3085.44 3085.44 505.15 INC 3088.64 3088.64 505.15 INC 3095.12 3095.12 505.16 INC 3106.67 3106.67 505.17 INC 3113.38 3113.38 505.18 INC 3125.34 3125.34 505.19 INC 3139.32 3139.32 505.20 INC 3151.83 3151.83 505.22 INC 3162.76 3162.76 505.23 INC 3222.30 3222.30 505.29 INC 3304.45 3304.45 505.38 PEAK 3091.87 3091.87 505.15 DEC 3054.52 3054.52 505.12 #REF! STORAGE HY ®R ®GRAPH FOR 100 YEAR / 3 HR STORM RETENTION BASIN. PREPARED BY COACHELLA VALLEY ENGINEERS SUBJECT 24Hr /100Yr -Core Homes - La Quinta JOB # 04220 LStreet Drainage Pond 3:1 Sideslope DATE: 9/13/05 VOL /15 n BY: DKR (IN /15min) TRIB AREA= (CFS) 4.7200 ACRES PERC.RATE 0.0 2.00 IN /HR ( 0..5 IN/15 Min) STORM VOLUME 2.29 IN /3HR l 3,7 0.085 2 PERIOD PRECIP INTENSITY IMPERV FLOW 3 SHEET 2 OF 2 SOIL GROUP "B ", AMCII, R.I.= 56, R.C. =50 %0 INFLOW in CUML VOL OTHER (CF) (CF) vu I rL_vev PERC /15Min . OTHER (CF) (CF) 1 100 C Q VOL /15 n (15min) % (IN /15min) RC =50% 0.455 (CFS) (CF) 593.0 0.0 0.182 163.8 1 3,7 0.085 2 4.8 0.110 0.457 0.237 213.2 3 5.1 0.117 0.457 0.252 226.7 4 5 4.9 6.6 0.112 0.151 0.457 0.459 0.242 0.327 217.7 294.7 6 7.3 0.167 0.460 0.363 326.7 7 8.4 0.192 0.462 0.419 377.1 8 9.0 0.206 0.462 0.450 404.8 g 12.3 17.6 0.282 0.467 0.621 558.7 10 0.403 0.474 0.902 811.9 404.8 16.1 4.2 0.369 0.096 0.472 0.456 0.822 0.207 739.4 18 6.2 11 12 SHEET 2 OF 2 SOIL GROUP "B ", AMCII, R.I.= 56, R.C. =50 %0 INFLOW in CUML VOL OTHER (CF) (CF) vu I rL_vev PERC /15Min . OTHER (CF) (CF) • --- READ (CF) 163.8 0.0 593.0 0.0 0.0 213.2 0.0 613.0 0.0 0.0 226.7 0.0 633.0 0.0 0.0 217.7 0.0 653.0 0.0 0.0 294.7 0.0 672.0 0.0 0.0 326.7 691.0 0.0 0.0 -0.0, 0.0 710.0 0.0 0.0 377.1 0.0 0.0 0.0 0.0 0.0 730.0 750.0 760.0 780.0 800.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 51.9 11.3 0.0 404.8 558.7 811.9 791.3 197.5 "ENTI CUM LIIMIIII REF: 24Hr /100Yr -Core Homes - La Quinta JOB # 04220 Street Drainage Pond 3:1 Sideslope DATE: 9/13105 BY: DKf RETENTION BASIS --DEPTH ARE (FT) (Sf D =5.00' 88le D =4.00' 74` D =3.00' 61; D =2.00' 50' D =1.00' 391 D =0.00' 30' SHEET 1 OF 2 1 1 1 11 1 11 I 1 11 1 11 I 1 11 1 11 I 1 11 I 1 11 1 11 1 11 I 111 111 -I 1 11 1 11 • 111 111 1 11 1 11 1 1 11 1 11 _ 1 11 1 11 Y ,1 J r I'. J .S J 1 CORE HOMES DRAINAGE RETENTION PERCOLATION CRITERIA.....REFERENCE LCI REPORT LP 05057...PAGE 9 SOILS TESTING EVALUA7YON. FROM THEE LANDMARK. ENGINEEt2ING '/-ZEPOI'ZT.INtDICATE 7-KA7' T74E PEIRCOLArION RATS IS 13.0 CiALLONS FER -HOUR PE2 SQUAIRE FOOr ........EQuArES rO 1.73 CUBIC FF7- PER �6OU'R ... 20.8 INCHES PE2 �6O ME2EF0RE... . M02E riJAN EXCEEDS ri�E MAXIMUM ALLOWABLE FOR CITY of LAQUINrA... DK..060605 S50 OFFSITE DRAINAGE TOPOGRAPHY -� 11 `, i ! 5 ;' •lip, P 0 0 8 0 I' o U u PA o .� IgAG f I 1 �• M1 3� T17") , • a Coachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 6 of 7 January 05 MADISON STREET STORMFLOWS _. EU oti •� -• • ir a II � � I► u Cn Cn n � II W . II i II 1�1r#'. �I '.o °tip • 5 � l [ IIII If O • II r�l\ 113!7 N-3 v �� I! y E C p ll �� � :, II II r ij - II C- p II II e� _ a . / II Qs G LO LLI ;• M .kk NN e Q `�t I ® .II It II M r II p ll �J Lj_-- (I�') 11 6b IIaM °u�� 3(7N3 �.❑ > '•I .. l._� _ J \1.� it ( it i' `1 : d • II f1 Z n•l) r =:� II y c r e II II I _ b I II M �� ii 116 • Cn b—i 8 I __��.___ yz jl li "Illa� Coachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 7 of 7 January 05 Q`� 7- ic, R1 O 30.' , crl two .. .... . .. ...... i-O 13 El OFFSITE MADISON STREET *100 YEAR STORE! FLOWS CORE HOMES TM 33085 REGIONAL DRAINAGE ANALYSIS CITY LA QUINTA. 20 YEAR STORM CRITERIA MONROE AVENUE OFSITE FLOS OFFSITE DRAINAGE AREA ... 18 ACRES + MADISON STREET ROW = 7.35 ACRES AGRICULTURAL URBAN RUNOF COEFFICIENT = 0.20 10 YEAR STORM RIVFCD PLATE D -4.5 RATIONAL ANALYSIS Q =CIA I = 4.52 X 1.111.68 = 2.44 IN1HR REF...NWS NOAA ATLAS 14..FREQUENCY DATA BASE ATTACHED HEREWITH.. Q20 = 0.20 X 2.44 INIHRX 25.35AC) =12.37 CFS ...............Q100 = 0.20 X 4.52 X 25.35AC = 22.92 CFS NOTE: ANALYSIS ASSUMES THAT OFFSITE RUNOFF WILL NOT BE INTERCEPTED AND COLLECTED BY THE VAN DE BOS PROJECT .....LA QUINTA POLO PARTNERS .... TM 30378 OVERALL STREET SLOPE FROM 51ST STREET ( VISTA BONITA TRAIL )TO 52ND STREET NORTH CL ELEVATION IS EL 516.00 REF: TM 30378 SOUTH CL ELEVATION IS EL 509.30 REF: TM 31572 DISTANCE CL VISTA BONITA TRAIL TO CL 52ND AVENUE ...2640.00 LF OVER ALL SLOPE..6.70 FEET DIVIDED BY 2650.0 = 00.25% REF: LACRD STREET FLOW NOMOGRAPH D -08... FOR S = 0.25% D = 0.67FT A = 7.4 SF Q= 29.0CFS EQUATES TO THE EQUIVALENT OF A 29.018.78 = 3.30 ( RCFCD PLATE D -4.5 ) EQUATES TO WELL OVER A 200 YEAR EQUIVALENT STORM..:; DEPTH OF 20 YEAR FLOW IN MADISON STREET ADJACENT TO THE TM 33085 CURB IS 0.40 FEET.. THEREFORE THE 20 YEAR STORM WILL BE CONTAINED WITHIN THE MADISON STREET SECTION AND NO ' OVERFLOW INTO TM 33085......D = 0.40 FEET IDEPTH OF FLOW FOR THE 100 YEAR FLOW IN MADISON STREET ADJACENT TO TM 33085 IS 0.60 FT THEREFORE THE 100 YEAR STORM WILL BE CONTAINED WITHIN THE MADISON STREET SECTION AND NO t OVERFLOW INTO TM 33085....D = 0.60 FEET TM31582 AS APPROVED BYLA QUINTA TOWN COUNCIL ON AUGUST 7, 2005 DOES NOT INTAKE ANY ' MADISON STREET FLOW THERFORE ALL WILL PND AT THE INTERSECTION OF 52 "D AVENUE AND MADISON _ STREET.... ' VOLUME OF THE PONDED INTERSECTION AT 52ND AVENUE IS APPROXIMATELY 600 FEET LONG EXTENDING UP MADISON STREET AND AREA VOLUME OF 1.0 FT DEEP BY 33 FT WIDE AT 2 % CROSS J SLOPE.. A = 16.5SF X 600 = 9900 CF OF CORNER STORAGE AT THE NORTHWEST CORNER OF 52 "D AND ATIVE TO THE EAST THEREFORE 100 YEAR FLOW WILL FLOW EAT MADISON ... 52 "D AVENUE SLOPE NEG ' FROM THE NORTH EAST QUADRANT OF MADISON AND 52 "D AVENUE 1 CORE HOMES TM 33085 REGIONAL DRAINAGE ANALYSIS CITY LA QUINTA..10 YEAR STORM CRITERIA MONROE AVENUE OFSITE FLOS OFFSITE DRAINAGE AREA...18 ACRES AGRICULTURAL URBAN RUNOF COEFFICIENT = 0.20 10 YEAR STORM RIVFCD PLATE PLATE D -4.5 I= 4.76X1.111.6 =2.82 IN /HR Q= 0.20X2.82.X18= 10.38CFS NOTE 90% OFFSITE RUNOFF WILL BE INTERCEPTED AND COLLECTED BY THE VAN DE BOS PROJECT LA QUINTA POLO PARTNERS TM 30378 0 Page G -20 i 0(CfS) SN 300 Q(cfs) A if t) D(ft.) 10.0 200 300 f e o 200 zoo 12.9 0.83 i? g:,� ' 7.0 loo 4.9 T5 6.0 �� 100 0 7.4 0.6 0.67 6.9 5.0 � ` 0.65 50 40 -0.60 4.0 90 50 5- 30 80 40 3.0 70 20 4.5 0.55 30 60 EXAMPLE (Sou Dashed Lint) 50 10 3.6 -0.50 20 GWa+ 0. 82 ch 20 .67= D50.81 ' S. 10.0% 40 Find D° 0.60 ft. 2-7 -0.45 A- 5.7 ft! 30 b 1 2.0 0.40 1.0 0. 0.90 Q80 5 4 Q70 1.3 0.35 0.60 Q `off 3 0,50 2 c� 0.6 1= =0.83 0.40 0.85 0.30 'j Q �D 0.30 1.0 I Q(cfs) IF 020 50' 2.0 0.49 0.25 e' 2' 31.67' 8.33' 1.0 l 030 009 _ �� ° M 0.25 -0.20 0.10 QOB o -z ap °N Q07 o 'Q � p -� ✓_ _�- 0.10= D30.1T 0.10 0.17 .17 -{ 0.06 0.17 10 1-0.67 - 0.13 -0.15 005 - 0.099 �- I M- NOTE, THE 0 DETERMINED FROM THIS CHART - 0.059 0.10 IS FOR ONE HALF OF STREET. -' LOS ANGELES .C' ®UN3�° ROAD DEPARTMENT" REFERENCE SHEET STREET FLOW -1 MAJOR HWY. -Chart 5 of 5 r D -OE i Vc DOC NILink LOGO POINT PRECIPITATION FREQUENCY ESTIMATES I Lmk FROM NOAH ATLAS 14 to California 33.68 N 116.25 W 68 feet ' from "Precipitation- Frequency Atlas of the United States" NOAA Atlas 14, Volume 1, Version 3 G.M. Bonnin, D. Todd, B. tin, T. Parzybok, M.Yekta, and D. Riley NOAA, National Weather Service, Silver Spring, Maryland, 2003 Extracted: Thu Jun 16 2005 t Confidence its. Seasonality , Location Maps_ -_ -. Other Info; Grids Maps Help Do C1 Precipitation Frequency Estimates (inches) ❑ARI* 5 10 15 30 0 3 6 12 24 48 4Y 7y l Y 2 y 3 y ears min min min min mr hr hr hr hr da da da da da �y )�C� 1.59 1.75 2.00 2.17 0.12 0.18 0.23 0.31 0.38 0.51 0.59 0.79 0.98 1.06 1.19 1.30 1.40 1.49 ���� C� 0.20 0.30 0.37 0.50 0.61 0.80 0.91 1:20 1.45 1.62 1.85 2.00 2.17 2.32 2.48 2.73 3.11 3.38 10 0.26 0.40 0.49 0.66 0.82 1.04 1.18 1.51 1.82 2.06 2.39 2.58 2.77 2.98 3.16 3.47 3.94 4.30 25 0.36 0.56 0.69 0.93 1.15 1.42 1.57 1.97 2 �3 2.70 3.19 3.42 3.65 3.93 4.14 4.52 5.10 5.57 '50 0.46 0.70 0.87 1.17 1.44 1.75 1.91 2.35 2.75 3.22 3.88 4.14 4.38 4.72 4.95 5.37 6.02 6.59 100 0.57 0.87 1.08 1.45 1.79 2.14 2.29 2.77 3.19 3.79 4.64 4.94 5.18 5.59 5.82 6.29 7.00 7.68 ' 200 0.70 1.07 1.32 1.78 2.21 2.58 2.73 3.21 3.66 4.40 5.50 5.83 6.55 6.76 7.26 8.03 8.83 500 0.91 1.39 1.72 2.31 2.86 3.25 3.38 3.88 4.33 5.29 6.79 7.14 7.33 7.95 8.12 8.66 9.48 10.44 1000 1.10 1.67 2.08 2.79 3.46 3.86 3.95 4.44 4.88 6.03 7.89 8.27 8.39 9.12 9.24 9.80 10.64 11.74 ' These precipitation frequency estimates are based on a partial duration series. ARI is the Average Recurrence Interval. Text VefSlOn Of.tabl8_ _ _ Please refer to the documentation for more information. NOTE: Formatting forces estimates near zero to appear as zero. pf2_Jun162005153246.png ' ❑x pf Jun162005153246.png i, i i Confidence Limits - The upper bound of the confidence mtervar at yu-/a commence tum � ul_ .a- • - - - -- "These precipitation frequency estimates are based on a partial duration series. ARI is the Average Recurrence Interval. Please refer to the documentation for more information. NOTE: Formatting prevents estimates near zero to appear as zero. 91-- irnA1) MA\na ?7n\R Pnnrt.,\050504 HWrolog:yTrecipitation Frequency Data Server 0422... 8/31/2005 rrec>pltdtlUll rrequency uata server * Lower bound of the 90% confidence interval Precipitation Frequency Estimates (inches) dd 5 10 1� 30 60 120 3 6 12 24 48 jdayjg][&[N� ears min min min min min min hr hr hr hr hr d (years) ❑ ❑ ❑�❑ � 1.53 0.10 0.15 0.19 0.25 0.31 0.42 0.49 0.65 0.80 0.91 1.03 1.12 1._1 1.29 1.38 C� 0.16 0.24 0.30 0.40 0.50 0.66 0.75 0.98 1.19 1.39 1.59 1.72 1.85 2.00 2.14 2.38 10 0.21 0.32 0.39 0.53 0.66 0.85 0.96 1.23 1.47 1.75 2.04 2.21 2.36 2.56 2.71 3.00 25 0.29 0.44 0.54 0.73 0.90 1.15 1.27 1.58 1.87 2.27 2.71 2.91 3.08 3.34 3.52 3.90 50 ;0.36 0.54 0.67 0.91 1.12 1.39 1..52 1.87 2.19 2.68 3.24 3.49 3.65 3.97 4.18 4.61 100 0.43 0.66 0.82 1.10 1.36 1.66 1.80 2.18 2.50 3.12 3.83 4.10 4.30 4.64 4.87 5.36 200 0.52 0.79 0.98 1.32 1.63 1.97 2.10 2.49 2.84 3.58 4.48 4.76 4.93 5.37 5.59 6.12 500 0.65 0.99 1.23 1.66 2.05 2.41 2.53 2.94 3.29 4.24 5.42 5.73 5.85 6.40 6.58 7.19 1000 0.76 1.16 1.44 1.94 2.40 2.77 2.89 3.30 3.65 4.76 6.18 6.52 6.62 7.24 7.39 8.04 The lower bound of the confidence interval at 90% confidence level is the value which 5% of the simulated quantile values for a given frequency are less than. "These precipitation frequency estimates are based on a partial duration maxima series.'ARI is the Average Recurrence Interval. Please refer to the documentation for more information. NOTE: Formatting prevents estimates near zero to appear as zero. Maps - overview map These maps were produced using a direct map request from the U.S. Census Bureau Mapping and Cartograohic Resources Tiger Map Server. F27 detai=ma please read disclaimer for more information. Fz-map legend Other Maps/]Photographs - 45 1160 day da; 1.73 1.8 3.38 M i 7.83 8.51 1 View USGS digital orthophoto qundran -0le (DOOI covering this location from TerraServer; USGS Aerial Photograph may also be available from this site. A DOQ is a computer - generated image of an aerial photograph in which image displacement caused by terrain relief and camera .tilts has been removed. It combines the image characteristics of a photograph with the geometric qualities of a map. Visit the USGS for more information. Watershed /Stream Flow Information - Find the Watershed for this location using the U.S. Environmental Protection Agency's site. Climate Data Sources - Precipitation frequency results are based on data from a variety of sources, but largely NCDC The following links provide general information about observing sites in the area, regardless of if their data was used in this study. For detailed information about the stations used in this study, please refer to our documentation. Using the National Climatic Data Center's (NCDC) station search engine, locate other climate stations within: I, ,^nAA\r%A ^- )n\T) o.,. +. \n5n5iid Rvrlrnlnov \PrerinitationFreauencv Data Server 0422. P n 1 /7(1(15 rreclpltduulu rrequency 1Jata server v � v i t +/ -30 minutes OR,,, ±/-1 degree of this location (33.0- 116.25). Digital ASCII data can be obtained I- directly from NCDC. Find Natural Resources Conservation Service (NRCS) SNOTEL (SNOwpack TELemetry) stations by visiting the Western Regional Climate Center's state - specific SNOT.EL station maps. Hydrometearological Design Studies Center DOC/NOAA/National Weather Service 1325 East -West Highway Silver Spring, SID 20910 (301) 713 -1669 Questions?: CSC Oucationsru noaa.eov Disclaimer r.cncn� u.,a. �, , ,.,gyp, or;nitation Frequenev Data Server 0422... 8/31/2005 Ire 77, _7 R 1EL . 'T� 5 W I Z I SQ, �X L P212 P.1 1w- 56 :41 Sk Ai 'I E,.s Ile 1'c� R.O. FLOOD CONTROL RIVERSIDE COUNTY A N D -4 D1 STRICT VATION WATER CONSER -HOUR Z'... -24 -YEAR 100 I %'_4, AWAL PRECIpITATION Z. P: -A 4 14" 4-" PI A7fr 774 T.. 1 °m 4 :�: � J j I u AC L." — 4 m C ' .Se.� />w \,w.xvia `�� l` ''3 "��'•mhd�._`��' ^J r, _� 4i• \�'•+'.�: Sa O� LO `,9.J.i ' �1.df Y c.�,,, .J' C,v�; .. � �/ . `'. �� • roi so�:�. •.� arRll r G COVF? , OKNI.� I T6N • • M WANI Z NIL ggil I i 'Al—k-07 i * 01 MAIN -Illigmm low 05� Be- 4 NMI A! OOD CONTROL RIVERSIDE COUNTY' FL A N N DISTRIC T WATER CONSERVATIO Y. 100-Y EAR, .6 - HO U. R PRECIPITADON 3.5 3 2.5 2 1.5 t .5 0 100 I 50 from mapz,then connect x one hour: .50 and 100- . DEPTH VERSUS PERIOD FOR DURATION SERIES P LA-rE D-4.5 � 3 3.5 3 2.5 2 1.5 t .5 0 100 I 50 from mapz,then connect x one hour: .50 and 100- . DEPTH VERSUS PERIOD FOR DURATION SERIES P LA-rE D-4.5 l�7 l7 O ll1 --C z C-' N z 7'1 M' 1 Z x rn m 1 cn tD RAINFALL PATTERNS IN IN PERCEN TIME 3--HOUR STORM PER 100 6-HOUR STOF tINC S -NIN 10 ^NIN IS -MIN ]0 -NIN PER PC RI PER 100 PER100 PERIOD PERIOD PERIOD PERIOD /CRI00 PER 100 100 SB 2.• sv t.s 1 1.] 2.6 )•1 e.5 1 .S 1.1 I.l )•6 2 1.] L e •.e I0 .0 2 .e I.z I.] I.v 2.1 4.) ..e TD 1.1 J.) S.1 I).9 7 .6 4 1.1 2.2 •.9 13 1.5 ).) •.9 17.. S .6 l,. 2.4 9.3 S 1•S I.e ).] J.♦ 6.6 1.) 29,9 20.) 6 .7 I.S 2.4 S.0 6 t 1.5 •.1 B.• 10 7 .7 1.6 2.♦ 6.e e 1.0 •.2 9.0 •2 a .1 1.6 2.3 9.0 9 l.e 4.] 12.) 2• 9 .7 1.6 2.6 11.6 l0 1.5 5.1 17.6 S.T l0 ,T 1.6 2.T 1•.• Il 1.6 6.6 16.1 z9 11 ,7 1.6 2.e 2S.t 12 l.e 5.9 •.2 ••T 12 .0 1.7 ].0 ••. 1 2.2 7.3 J• 13 .e 1.7 ].2 1. 2.2 e.s L•7 14 .6 1.e ]•6 IS i•2 1••1 ]9 1s 91 16 2.0 14.1 16 17 .B .e 1.9 t.0 •.1 S.• 17 2.6 ).e •S 1 l.9 IB 2.7 2.. 1.1 19 .e 2.1 6.9 19 2.. 20 .0 2.3 7,5 20 2.7 21 .B 2.S 10.6 21 ).) 22 .e 2.6 1..4 22 J.t 2. .9 J.2 1.0 2. )•0 25 .a ].4 25 J.1 26 .9 ).9 26 4.2 21 .9 •.2 27 S.0 29 .9 •.S 29 .0 4 .0 29 6.a 30 .9 S.1 30 7•) J1 .9 6.7 J1 0.2 32 .9 e.l 32 3.9 )] 1.0 10.] l) 2.0 J• 1 )• 1.90 ]S 1.0 1.1 JS l.e 36 1.0 ,S 36 .6 37 1.0 ]6 1.1 ] 9 1.1 .0 1.1 •1 1.2 .2 1.) U l.• •9 1.. •S 1.5' .6 1.5 67 1.6 •e 1.6 IN IN PERCEN TIME S-MIM' PERIOD PER 100 •9 1.7 s6 I.e 51 1.9 52 22 I 2.1 S• 2.l 5s ] S6 I.J S7 2.. SB 2.• sv t.s 60 2.6 6 ,) 62 ].6 6) ].9 6. •.z 6S ••T 66 S.6 61 1.9 69 .9 69 6 TD .s TI •] 72 .2 NOTES: I. 3 and 6 -hour patterns based on the Indio area thunderstorm of September 24,1939. 2. 24 -hour patterns based on the general storm of March 2 d 3,1938. 1=1 M 24 -HOUR STC TIME 1S -MIN 30 -M14 60 -.IM PER10D PEPI00 ►ERIOR PERIOD I 2 2.6 st I ] 2.9 S] J•4-. i ] 6 l.e • .• 1 2.1 s ,) 2.6 i 59 6 ,) 2.4 t 61 7 .] 1.0 J.e 1 .4 1.1 ♦.0 9 ♦ 4 67 Ip .♦ •J 69 I1 .S 1.] 1.0 12 .S l.6 TJ 13 7. •• to.e I• ,S 2.0 11.• 14 7e 6 10.4 16. •a 2.5 e.S IT .6 ].0 1.• ID .7 ].] 1.0 10 .t ].9 1.3 20 .e •.l 1.2 21 90 •2 1.1 z2 .T •.0 1.0 2J a I.e 9 2• a J.S e 25 .9 S.1 26 9 S.T 27 1.0 6.e 2e 1.0 ••6 z9 1.0 1.3 ]0 1.1 s.1 JI 1.2 ••T 32 1•J J.0 ]] J• 1.5 •6 35 a )6 L•7 )7 1.9 )e 2.0 •4 i ]9 91 •2 .. 2.0 •� •S 1.9 •6 l.9 •1 1.1 •e 1.e i i I iRM 15 -MIM TIME PERIOD PERIOD ' •9 2.9 SO 2.6 st z•B ; 52 2.9 S] J•4-. i S• I 7.• f 55 2.J 56 2.] 57 2.7 i 56 2.6 i 59 2.6 i 60 2.4 t 61 2.1 62 2•) 6J 1.9 6. t 9 I 65 4 66 4 67 •] 6e •J 69 5 70 •S 71 S 12 •4 7J 7. •• 15 •J 76 2 77 J 7e 6 19 ) e0 z el •) oz •) eJ ) 0• 2 aS ) 66 .2 61 •) ee •2 e9 . J 90 •2 91 .2 92 .2 97 .t 9• t vs .t ♦6 •t ' RUNOFF INDEX NUMBERS OF HYDROLOGIC SOIL -COVER COMSPLEXES FOR PEEWIOUS AREAS -AMC II Quality of Soil Group Cover Type (3) Cover (2) A B CT D A i r i NATURAL COVERS AGRICULTURAL COVERS - 76 85 90 92 Fallow (Land plowed but not tilled or seeded) .RUNOFF . INDEX NUMBERS FOR HYDROLOGY iMANUAL PERVIOUS AREAS PLATE E-6.1 0 of 2) 78 B6 91 93 Barren (Rockland, eroded and graded land) Chaparrel, Broadleaf Poor 53 70 BO 85 (Manzonita, ceanothus and scrub oak) Fair 40 63 75 81 Good 31 57 71 78 Chaparrel, Narrowleaf Poor 71 82 BB 91 (Chamise and redshank) Fair 55 72 81 86 Grass, Annual or Perennial Poor Fair 67 50 78 69 86 79 89 84 Good 38 61 74 80 Meadows or Cienegas Poor Fair 63 51 77 70 85 80 88 84 (Areas with seasonally high water table, 78 principal vegetation is sod form -ng grass) Good 30 58 72 Poor 62 76 84 88 Open Brush (Soft wood shrubs - buckwheat, sage, etc.) Fair 46 66 77 83 Good 41 63 75 61 Poor 45 66 77 83 Woodland (Coniferous or broadleaf trees predominate. Fair 36 60 73 79 Canopy density is at least 50 percent) Good 28 55 70 77 Poor 57 73 82 86 Woodland, Grass (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.) Poor 58 74 B3 87 Turf (Irrigated and mowed grass) Fair 44 65 77 82 Good 33 58 72 79 AGRICULTURAL COVERS - 76 85 90 92 Fallow (Land plowed but not tilled or seeded) .RUNOFF . INDEX NUMBERS FOR HYDROLOGY iMANUAL PERVIOUS AREAS PLATE E-6.1 0 of 2) I 11 ACTUAL IMPERVIOUS COVER Recommended Value Land Use (1) Range- Percent For Average Conditions- Percent(2 Natural or Agriculture 0 - 10 0 Single Family Residential: (3) 40,000 S. F. (1 Acre) Lots 10 - 25 20 20,000 S. F. (� Acre) Lots 30 - 45 40 7,200 - 10,000 S. F. Lots 45 - 55 50 Multiple Family Residential: Condominiums 45 - 70 65' Apartments 65 - 90 80 Mobile Home Park 1 60 - 85 I .75 Commercial, Downtown 80 -100 90 Business or Industrial Notes: . 1. Land use should be based on ultimate development of the watershed. Long range master plans for the County and incorporated cities should be reviewed to insure reasonable land use assumptions. 2. Recommended values are based on average conditions which may not apply to a particular study area. The percentage impervious may vary greatly even on comparable sized lots due to differences in dwelling size, improvements, etc: Landscape practices should also. be considered as it is common in some areas to use ornamental grav- els underlain by impervious plastic materials in place of lawns and shrubs. A field investigation of a study. area should always be made, and a review of aerial photos, where available may assist in estimat ing the percentage of impervious cover in developed areas. 3. For typical horse ranch subdivisions increase impervious area 5 per- cent over the values recommended in the table above. RCFC 11 WCE" JHYDRJLDGY MANUAL IMPERVIOUS. COVER FOR DEVELOPED AREAS PLATE E-6.3 1 RUNOFF COEFFICIENT CURVE DATA The data in the following tables may be used to develop runoff coefficient (C) curves for any combination of runoff index (RI). number and antecedent mositure condition (AMC). For an RI number with an AMC of II (from Plate D -5.5) enter the tables on the following pages and plot the "C" curve data directly on Plate D-5.B. "C" curve data is given for even RI numbers only, but values may easily be interpolated for odd RI numbers. For an AMC of I or III enter the tabulation on this page with the RI for AMC II, and read the appropriate RI for AMC I or III. Use this revised RI to enter the tables on the following pages to deter- mine "C ". For example if RI = 40 for AMC II, then RI = 22 for AMC I and RI = 60 for AMC III. AMC ADJUSTMENT RELATIONSHIPS 01 FOR RI FOR ANC I1 ANC CONOITIONSt OTHER RI FOR ANC II R[ FOR ANC CO.0I710NSf O7NER - AMC I APC I, ANC I ANC III l0 -- ll -- 22 24 SS 56 35 36 74 75 12 ^ 13 -- 25 27 S7 S8 37 38 75 T6 IA ^ 28 59 39 77 IS 16 -- 30 31 60 61 •0 Al 70 76 17 ^ 33 62 42 79 1B -- 3A 63 A3 00 l9 -- 36 64 ♦• 0l 20 -- 37 65 AS 82 21 IO 22 10 38 39 66 67 A6 AT e2 e3 23 11 2A it •1 12 6e 69 6e 50 eA 6A 25 12 26 12 43 AA TO 71 51 52 eS e6 27 13 28 I 46 A7 72 73 53 54 06 e7 29 14 4.9 74 55 06 30 IS 31 16 50 SI TS 76 S7 Se 116 89 32 16 33 IT S2 53 77 7e S9 60 89 90 34 to 50 79 62 91 3S 18 36 19 55 56 00 01 63 6a 91 - 92 37 20 38 21 57 50 02 03 66 67 92 93 - 39 21 19 eA 68 93 AO 22 •1 27 60 61 85 86 70 72 94 94 42 24 43 25 62 63 07 88 73 75 9S 9S AA 2S 6A 89 76 96 AS 26 46 27 DS 66 90 91 76 e0 96 97 A7 29 67 92 el 97 48 29 66 93 R3 90 A9 30 69 94 eS 90 SO 31 TO 95 67 90 SI 31 TO 96 89 99 52 32 71 97 91 99 53 33 SA 34 T2 73 90 99 94 97 99 -- R F C D RUNOFF COEFFICIENT HYDROLOGY JNiIANUAL CURVE DATA PLATE D -5.7 0 of 12) D m CJ 1 .d� O a 0 � (J1 L. x z n 0 C � 0 fIl 0 Fri D "T'1J D � z RUNOFF COEFFICIENTS FOR RI INDEX NO. ■ 28 IMPERVIOUSI INTENSITY - INCHES /HOUR PERCENT .0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 5.0 6.0 0. S. 10. I5. 20. 25. 30. 35. 40. 45. 50. 55. 60. 65. 70. 75. 80. 85. 90. 95. 100. .00 .11 .20 .27 .33 .38 .42 .45 .48 .53 .57 .04 .1S .24 .31 .36 .41 .44 .4A •.51 .55 .59 .09 .19 .27 .34 .39 .43 AT .50 .53 .57 .61 .13 .23 .31 .3T .42 .46 .49 .S2 .55 .59 .62 .18 .27 .34 .40 :45 .48 .52 .54 .57 .61 .64 .22 .31 .36 .43 .47 .Sl .54 .57 .59 .63 .65 .27 .35 .41 .46 .50 .S4 .56 .59 .61 .64 .67 .31 .39 AS .49 .53 .56 .59 .61 .63 .66 .69 36 A3 .48 .52 .56 .59 .61 .63 .65 .68 .70 . . .40 .47 .52 .56 .59 .61 .64 .66 .67 .70 .72 .45 .51 .55 .59 .62 .64 .66 .68 .69 .72 .74 .49 .55 .59 .62 .64 .67 .66 .70 .71 .74 .75 .54 .59 .62 .65 .67 .69 .71 .72 .73 .75 .77 .58 .63 .66 .68 .70 02 .73 .74 .75 .7T .T9 .63 .66 .69 .71 .73 .74 .T6 IT .78 .79 .80 .67 .70 .73 .74 .76 IT .78 .T9 .80 .81 .82 .72 .74 .76 .77 .79 .80 .RO .RI .82 .83 .83 .76 .78 .80 .81 At .02 .83 .83 .84 .85 .85 .81 .82 .83 .84 .64 .85 .85 .86 .86 .86 .87 .86 .86 .87 .87 .87 .87 .AS .RR .08 .88 .88 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 RUNOFF COEFFICIENTS FOR RI INDEX NO. : 32 IMPERVIOUS I INTENSITY - INCHES /HOUR PERCENT .0 .5 1.0 IoS 200 2.5 3.0 3.5 4.0 5.0 6.0 0. 5. 10. iS. 20. 25. 30. 35. 40. 45. S0. 55. 60. 65. T0, 75. 80. 85. 90. 95. 100. .00 .13 .23 .31 .37 .42 .46 .50 .53 .S7 .61 .04 .17 .27 .34 .40 .45 .48 .52 955 .59 .63 .o9 .21 .30 .37 .43 .47 .51 .54 .56 .61 .64 .13 .25 .33 .40 .45 .49 .53 .56 .58 .62 .65 .18 .29 .3T .43 .48 .132 .55 .58 .60 .64 .67 .22 .33 .40 .46 .50 .S4 .57 .60 .62 .66 .68 .27 .36 .43 .49 .S3 .57 .59 .62 .64 .67 .70 .31 .40 .47 .52 .56 eS9 .62 .64 .66 .69 .71 .36 .44 .50 .55 .58 .61 .64 .66 .68 .70 .73 .40 .48 .53 .58 .61 .64 .66 .69 .69 .72 .74 .45 .52 .57 .61 .64 .66 .66 .70 .71 .74 .76 .49 .56 .60 .64 .66 .68 .70 .72 .73 .75 IT .54 .59 .63 .66 .69 .71 .73 .74 .74 .77 .T8 .58 .63 .67 .69 .72 sT3 .75 .76 .77 .79 .80 .63 .67 . TO . T2 .74 .76 .77 .78 .79 .80 .81 .67 :71 .T3 .7S .7T TO .79 :80 .01 .82 .83 .72 .75 .77 .70 .79 .80 .81 .82 .83 .83 .64 .T6 09 .80 .81 .82 .83 .63 .84 .84 .85 .86 .81 .82 .83 .84 .85 .8S .R6 .0O .86 .87 .8T .86 .86 .67 .87 .87 .88 .80 .88 .88 .88 .89 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 � m - RUNOFF COEFFICIENTS FOR RI INDEX NO. = 30 IMPERVIOUS I INTENSITY - TNCHES /HOUR PERCENT .0 .5 1.0 1.5 2.0 2.5 7.0 3.5 4.0 5.0 6.0 O. 5. 10. 15. 20. 25. 30. 35. 40. 45. 50. 55. 60. 65. 70. 7S. 80. 85. 90. 95. 100. .00 .12 .22 .29 .35 .40 .44 .AR .51 .55 .59 .04 .16 .25 .32 .38 .43 .46 .50 .53 .57 .61 .09 .20 .29 .35 .41 .45 .49 .52 .55 .59 .62 .13 .24 .32 .38 .43 .48 .51 .54 .57 .61 .64 •18 .28 .36 .41 .46 .50 .53 .55 .59 .62 .65 .22 .32 .39 .44 .49 .53 .56 .58 .60 .64 .67 .27 .36 .42 .47 .52 .SS .58 .60 .62 •66 .68 .31 .40 .46 .51 .54 .58 .60 .62 .64 .68 .70 .36 .43 .49 .54 .57 .60 .63 .65 .66 .69 .72 .40 .47 .53 .5T .60 .63 .65 .6T .68 .71 .T3 .45 .51 .56 .60 .63 .65 .67 .F9 .70 .73 .75 .49 .55 .S9 .63 .65 .68 .69 .T1 .72 .T4 .76 .54 .59 .63 .66 .6R TO .72 .73 .74 .T6 .78 .58 .63 .66 .69 .71 .73 .74 .75 .76 .78 .79 .63 .67 .70 .72 .74 .7S .76 .77 .7R .80 .1)1 .63 .71 .73 .75 .76 .18 .79 .79 .80 .81 .82 .67 .72 .74 .76 .78 .T9 .80 .81 .R2 .82 .83 .84 .76 .78 .80 .81 .82 .83 .83 .84 .84 .85 .85 .81 .82 .83 .84 .85 as As .R6 '.86 .87 .87 .86 .90 .86 .90 .87 .90 .07 .90 .07 .90 .88 .90 .88 .90 .88 .90 .88 .90 .88 .90 .88 .90 RUNOFF COEFFICIENTS FOR RI INDEX NO. - 34 IMPERVIOUSI INTENSITY - INCHES /HOAR PERCENT .0 .5 1.0 1.5 ?.0 2.5 3.0 3.5 4.0 5.0 6.0 0. S. 10. I5. 20. 25. 30. 35. 40. 45. S0. 55. 60. 65. 70. 7S. 80. 85. 90. 95. 100. .25 .33 .39 .44 .48 .52 .SS X61 .00 .15 .28 .36 .42 .4T .50 .S4 .56 .64 .04 .18 .32 .39 .44 .49 .52 .56 .58 .62 .66 .09 .22 .26 .35 .42 .47 .51 .55 .ST .60 .64 .67 .13 .30 .38 .44 .49 .133 .ST .59 .62 .65 .68 .16 .41 .47 .52 .56 .59 .61 .63 .67 .70 .22 .33 .4S .50 .54 .50 .61 .63 .65 .69 .71 .2T .37 .48 .S3 .5T .60 .63 .65 .67 .70 .T2 .31 .41 AS .56 .60 .63 .65 .67 .69 .72 .74 .36 .51 .54 .59 .62 .65 .6T .69 .71 .73 .15 .40 .49 .62 .6S .67 .69 It .72 .75 .76 .45 .S2 .58 .61 .64 .67 .69 .71 .73 .74 .76 .78 .49 .56 .67 TO .T2 .T3 .75 .76 .78 .T9 .S4 .60 .64 .67 TO .72 .74 .75 .7T .78 .79 .0.1 .58 .64 It .T3 .7S .T6 IT .79 .79 .81 .82 .63 .6T .74 .T6 IT .79 .60 .SO at .82 .83 .67 .71 IT .79 .80 .81 .82 .R2 .83 .04. .85 .72 .75 .79 .80 .81 .82 .83 .84 .84 .85 .85 .86 .76 :84 .84 .RS as .86 .R6 .86 .07 .87 .81 ;8 6 .82 . 86 .81 .87 e87 e88 .R8 .88 .88 .88 •09 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 .t• �- w CD m 400 _c m 350 v 300 .c 0 250 ^ J v L d 200 J 150 C E 50 a 0 d a> 0 35 m CL 30 N 25 C E c_ 20 '19 18 17 16 0 15 14 i? 13 c 12 � II w 0 Q> 9 E 8 7 LIMITATIONS'. Tc' L 100 1000 90 900 80 800 70 700 60 .t• �- w CD m 400 _c m 350 v 300 .c 0 250 ^ J v L d 200 J 150 C E 50 a 0 d a> 0 35 m CL 30 N 25 C E c_ 20 '19 18 17 16 0 15 14 i? 13 c 12 � II w 0 Q> 9 E 8 7 LIMITATIONS'. I. Maximum length =1000' 2. Maximum. area = 10 Acres a > H a .� U 500 400 300 a o' o` > 200 N o E 100 `a ..- 60 c 0 0 d 50 40 E a °' cn o � 30 o rl) c c 20 C 10 8 6 K Ai Undeveloped 0 Good Cover ® 2 Undeveloped 0 c 1. Fair Cover ^ .6 Undeveloped Poor Cover _ 0 0 .4 .3 `Zl 2 Single Family > (1/4 Acre) a� Commercial 0 m (Pav c iv 6 100 5 4 R C FC C ® HYDROLOGY MANUAL KEY L—H Tc —K —Tc' Tc 5 —, .ri!FO U Q 7 _ C a� 8 a 0 au 9 p 10 E v II 12 c 0 14 N 15 16 S 17 E IS —S 19 20 ~ c 0 v C 25 C 0 U 0 30 EXAMPLE: E (1) L =550', H =5.0, K= Single Family(1 /4 Ac.) 35 Development , Tc = 12.6 min. (2) L =550', H =5.0'1 K = Commercial 40 Development , Tc = 9.7 min. Reference: Bibliography item Igo. 35. PLATE D -3 W Z_ J 3 w W H to I i l 7� C OPEN CHANNEL 1- W W F- In I The 100-Year flood shall be captained within street R/W limits The 10 -Year flood shall be contained within the Top of curbs. Initiate a storm drain or channel when either condition is exceeded. W Z J t 41 W ¢1 H 1 Cn M UNDERGROUND STORM DRAIN TYPICAL I1 FREE BOARD -T DWELLING UNIT PAD 0 NOTES: Protection criteria shown are the Districts typical minimum requirments. Special conditions, or other authorities may require stricter controls;ie; for reasons.of traffic or pedestrian safety, maintenance problems behind curbs, etc., lover maximum depths of floes in streets may be required.Also see Riv. Co. Ord. No. 460. R CFC 8 W C® FLOOD PROTECTION r]Y-DROLOGY 1\AANUAL CRITERIA PLATE A -2 - --• -- 3 4 DETAIL -K it \� = 6 8 1 n 2 :�i \% MAXWELL PLUS DRAINAGE SYSTEM \� (OR EQUAL) s NTS \�. , �•• W 'ice /\y \/� \\'iii � \viii\ � \ /'�i \i\ ii.r"` . �: '- %: / ®MIN. 6" ID DRILLED SHAFT • �r; Og SUPPORT BRACKET - FORMED 12 GA i = 8 STEEL FUSION BONDED EPDXY COATED. T ��� 9 OVERFLOW PIPE - SCHEDULE 40 PVC. ` =•:: • ..+ � ` MATED TO DRAINAGE BELOW BASE SEAL (B DRAINAGE PIPE - ADS HIGHWAY GRADE WITH MDI -A COUPLER SUSPEND PIPE 7 DURING BACKFILL OPERATIONS TO \\ \ \� Lr ?z.��� t • ., , \\ PREVENT BUCKLING OR BREAKAGE. ,/ ;�_ •� BASE SEAL - GEOTEXTILE, POLY LINER OR �. CONCRETE SLURRY. / ©ROCK - CLEAN & WASHED, SIZED BETWEEN Q1 MANHOLE CONE - A4001FIED FLAT BOTTOM. & I" TO BEST COMPLEMENT SOIL CONDITIONS 02 STABILIZED BACKFILL - i SACK ®FLOFAST' DRAINAGE SCREEN - SCHEDULE 40 PVC 0, 120 SLOTTED WELL SCREEN WITH 32 CONCRETE SLURRY IN PAVED AREAS. SLOTS PER ROW /FT, 96" OVERALL LENGTH Q3 BOLTED RING &GRATE /COVER -CLEAN CAST IRON WITH WORDING 'STORM WATER ONLY VYITH MDI -B COUPLER. X I IN RAISED LETTERS SECURED TO CONE WITH © MIN. 4' 0 SHAFT - DRILLED TO MAINTAIN �\ MORTAR. RIM ELEVATION = 0.02' OF PLAN PERMEABILITY OF DRAINAGE SOILS. ® GRADED BASIN OR PAVING — (BY OTHERS) ® FABRIC SEAL — UV RESISTANT GEOTEXTILE — \� ? i • \ TO BE REMOVED BY CUSTOMER AT PROJECT 50 COMPACTED BASE MATERIAL — (BY OTHERS) COMPLETION.\ © PUREFLO DEBRIS SHIELD — ROLLED 16 GA. © CONNECTOR PIPE — 4" 0 SCH 40 PVC WITH. STEEL X 24" LENGTH WITH VENTED FLOW REGULATOR. \\ ANIT— S /PI-ION AND INTERNAL 265' MAX. ABSORBENT — HYDROPHOBIC PETRO— /' \ \' SWO FLATTENED EXPANDED STEEL ® CHEMICAL SPONGE. MIN. 100 OZ. CPACITY. \\ �\ SCREEN X 12" LENGTH FUSION BONDED O NON WOVEN FILTER FABRIC PER EPDXY COTED SEC. B8 -103 CAL. STD. SPEC \ 4x (7 )PRECAST LINER - 4000 PSI CONCRETE DATE 7 -84 48" ID, 54" OD CENTER IN HOLE AND ALIGN * FREEBOARD TO MAXIMIZE BEARING SURFACE. ¢FREEBOARD DEPTH VARIES WITH INLET i PIPE ELVATION. INCREASE INTERCEPTOR / \\ SETTLING CLAMBER DEPTH AS NEEDED \ �� TO MAINTAIN ALL INLET PIPE ELEVATIONS ABOVE CONNECTOR PIPE OVERFLOW. ^I U-1 ca a w U z 4 0 Z_ EL 0 W 4 0 ti 3 0 0 Z v 4 Sladden 77 -725 Enfield Lane, Suite 100, Palm Desert, CA 92211 (760) 772 -3893 Fax (760) 772 -3895 6782 Stanton Ave., Suite A, Buena Park, CA 90621 (714) 523 -0952 Fax (714) 523 -1369 450 Egan Avenue, Beaumont, CA 92223 (951) 845 -7743 Fax (951) 845 -8863 December 3, 2007 Core Homes, LLC 470 South Market Street San Jose, California 95113 Attention: Mr. David Neale Project: Tentative Tract 33085 51St Avenue and Madison Street La. Quinta, California Project No. 544 -4809 07 -11 -797 Subject: . Supplemental Field Exploration and Infiltration/Percolation Testing As requested, we have performed supplemental subsurface exploration and percolation/infiltration testing on the subject site to evaluate the infiltration potential of the near surface soil. The percolation rates determined should be helpful in assessing storm water retention system design needs. The preliminary plans prepared by Coachella Valley Engineers indicate that it is proposed to collect stormwater runoff within a shallow retention basin located in the southeast corner . of the project site. Our supplemental. investigation included the excavation of one exploratory bore to a depth of approximately 15 feet below the bottom of the proposed -i!etention basin and:2 percolation test holes. to .depths_of.appxozimately 3 feet below the bottom of the retention basin. The approximate bore and test holes locations are indicated on the attached plan. Percolation testing was performed on November 6,.2007. Testing was performed. in general accordance with the U.S. Bureau of Reclamation (BOR) Test Method for Unsaturated Soil above Groundwater. 'The infiltration rates determined are reported in approximate inches per hour: Testing indicated fairly steady infiltration rates of 6.0 and .6.2 inches per hour for tests A and B, respectively. Tests results are summarized below: Test Hole Rate (inches] hour) A 6.0 B 61 December 3, 2007 -2- Project No. 544 -4809 07 -11 -797 It should be noted that the infiltration rates determined are ultimate rates based upon field test results. An appropriate safety factor should be applied to account for subsoil inconsistencies and potential silting of the percolating soil. The safety factor should be determined with consideration to other factors in the stormwater retention system design (particularly storm water volume estimates) and the safety factors associated with the design components. As previously described, one exploratory bore was excavated to a depth of approximately 22 feet below the existing ground- surface to evaluate the soil conditions as it may impact stormwater retention system performance. The bore indicated that the majority of the underlying soil consists of fine - grained silty sand but prominent silt layers were observed at depths of approximately 5 to 7 feet below existing grade: The retention basin should extend into the silty sand below the silt /clay layers (6 to 7 feet below existing grade. The underlying silty sand contained numerous thin interbedded silt lenses that were typically thin (less than 1/2 inch thick) and are inherently limited in lateral extent. The bore log is also attached to this memo. We appreciate the opportunity to provide service to you on this project. If you have questions regarding this letter or the data included, please contact the w Respectfully submitted, SLADDEN ENGINEERING Nicholas S. Devlin Project Engineer Copie §: 2 /Core Homes, LLC 4 /Coachella Valley Engineers Principal Engineer Sladden Engineering Sladden Engineering SITE PLAN WITH APPROXIMATE PERCOLATION TEST HOLE LOCATIONS mc VT�w 1344ft Ommm WL EM94 . ..... CA AL m AM. vw m fl�, � ti. JAw CM A d10 L Ail 16 Ww '! 7!z th WP �g 1K, 'A", fZ1 To e 10, CA Z IL TQUI luwm Irk QRwHw SC" ... . ...... r Mg!At-4�0'O.ZZ's'a, AX NORTH SCALE: As Shown MAP SOURCE: Coachella Valley Engineers LEGEND JOB NAME: Tract 33085, 51st Avenue& Madison St APPROXIMATE TEST HOLE LOCATION JOB NO. 544 -4809 t NORTH REPORT NO: 07-11-797 Sladden Engineering P-\ 2004 \04220 \dwg\04220_70D_BORE_X.dwg D9/21/2D07 08,29-09 AM EST Tentative Tract 33085 51st Avenue and Madison Street, La Quinta Date: 11/6/2007 Bore No. 1 Job Number: 5444809 I 0 3 Q� V j 3 Description 1 r° o Remarks 0 III' jjll.,il, Ground Surface Elevation –14 Feet AMSL Native Soil li�ll i;iij III S and: Fine Grained Grey. in color 5 2/3/4 Sandy Silt ML 26.0 61.0 Greyish Brown in color _ Bottom of Basin –8 Feet AMSL _ 1/2/2 Sandy Silt with Silty Clay CL 34.6 83.0 Greyish Brown in color 10 2%2/5 Silty Sand: Fine Grained and Silty Clay Interbedded SM 24.6 78.5 Brown in color _ j �IIIII 4/6/7 Silty Sand: Fine Grained and Silty Clay Interbedded SM 28.1 73.6 Brown in color 15. miil Iii i Ij 4/4/5 Sand: Fine Grained and Silty Clay Inferbedded SM 31.1 65.3 Grey & Brown in color I 1 il I l 4/4/7 Silty Sand: Fine Grained SM 19.8 48.5 Greyish Brown in color 20 q..I I' ! ii�! j 3/4/5 Sand: Fine Grained and Silty Clay Interbedded SM 32.1. 79.9 Grey & Olive in color 2s 30 Califdmia Split -spoon Sample Total Depth -22 Feet Bedrock not encountered - tinrecovered Sample Groundwater not encountered - Standard Penetration Test Sample 35 . 40 Note: The stratification lines represent the approximate _ boundaries between the soil types; the transition may be _ gradual. 45 50 Sladden Engineering IN THE CITY OF LA QUINTA, CALIFORNIA ���Q� �]�DC�o�o � G�C��C��1�0•�l O OCR � BASIN R TRACT MAP NO. 33085 NOVEMBER 16, 2007 C VE TEL(760)360-4200 FAX(760)360 -4204 Coachella Valley Engineers 77 -899 Wolf Road, Suite 102, Palm Desert, CA 92211 /QRpFESS /pH�\ K. R I CFI F�c w m * NO. 35728 ,^ E�6-30-09Of C/ I� DAVID K. RICE — RCE 35728 — EXPIRES 6 -30 -09 32 S3 AVENUE 5 4 W 50 33 1 34 T.5S. 43 T. 6S. W VISTA BONITA TRAIL 11 4 AVENUE 51 OLD ORCHARD z LANE 0 Lo z BETH CIRCLE 4 43 AVENUE 52 g 9 0 VICINITY MAP N.T.S. 11 j TRACT MAP NO. 33085 ' HYDROLOGY STUDY !' PREPARED BY: ' Coachella Valley Engineers 77 -899 Wolf Road, Suite 102 . ' Palm Desert, CA 92211 ' NOVEMBER 2007 TABLE OF CONTENTS Cover Sheet Table of Contents Hydrology Report Text (2007) Drainage Area Map — Post Development Retention Basin Sizing Spreadsheets SUH..CLQ..Comparative Analysis Street Carrying Capacity Calculations Catch Basin Design Calculations TENTATIVE TRACT MAP 33085 APPROVED RETENTION BASIN 12/15/2005 APPROVED HYDROLOGY REPORT 12/15/2005 Location Map — Predevelopment Soil Conservation' Service Aerial Map Storage Hydrograph ( rational method ) Offsite Topography and Storm Flow Madison Avenue Storm Flow analysis Geotechnical Infiltration Testing Results Riverside County Hydrology Manual Excerpts 2 ' Coachella Land — Storm Water Management 11/ 1 6/2007Report Prepared by: Coachella Valley Engineers 1 INTRODUCTION AND PROJECT INFORMATION The proposed site is located north of Avenue 52, west of Madison Street and south of Beth Circle. The project consists of a 4.32 Acre parcel being developed into 7 residential lots, each approximately 0.5 acres in size. HYDROLOGY Per the Conditions of Approval for T.M. No 33085, the materials within this report comply with the provisions of Section 13.24.120 (Drainage), LQMC, Engineering Bulletin No. 97.03. The storm volumes of 2.6, 3.1, and 4.0 inches for the duration of the 3 hour, 6 hour, and 24 hour / 100 year storm frequencies have been utilized in this analysis. The storm volumes are obtained from the Point Precipitation Frequency Estimates from DOC /NOAA/National Weather Service Office of Hydrologic Development, Hydro meteorological Design Studies Center, W /OHD13 at 1325 East -West Highway Silver Spring, MD 20910 -3283 ' The. hydrologic soils group map for the Coachella area is included in the appendix of this report. The soil type is a sandy, silty, loamy Indio soil, I -S, and Gilman B Soil, common in this area. ' The soil classification for the site is type "B ", having high infiltration rates, antecedent moistening conditions rating of AMC II and low runoff potential when saturated. 1 1 Soil Infiltration testing was performed by 'LandMark Geo- Engineers and Geologists %, LCI, Report No. LP05057, at the proposed location for the stormwater retention facility Testing concludes that a rate of 13.0 gallons per hour (20.8 in /hr /sf) can safely be used for infiltration design. As this analysis has been prepared in support of the previously approved study from 2005, a percolation rate of 2.00" /hour has been utilized in this analysis, as was used in the earlier study. As an additional factor of safety, the City of La Quinta has requested that the 100 -year, 3 -hour storm event also be analyzed utilizing a different analysis method (Synthetic Unit Hydrograph), with zero percolation considered. The site Runoff Index number of the hydrologic soil cover complex, for the pervious area (AMC II), is RC 56. This is for residential landscaping on Group B soils, with 45% impervious cover from RCHM plate D -5.5. For off -site street flows impacting the site, a 90% impervious value was utilized. The pond storage is based on the 100 year, storm event which results in the maximum volume required given the range of storms tested. The 'Retention Basin Summary, Table', included on the Drainage Area map, lists the basin design volumes at different levels within the proposed retention basin. 3 Coachella Land — Storm Water Management 5 /30 /2007Report Prepared by: Coachella Valley Engineers HISTORICAL DRAINAGE PATTERN Along the west boundary of the site, an existing earthen berm exists effectively blocking flows from the west. Along the east boundary, Madison Street, falling from north to south, is at a lower elevation than the site. Beth Circle, which will serve as the access point to this site, fronts the property along a portion of the northern boundary. A high point exists on Beth Circle approximately midway between Madison Street and the proposed Starfruit Trail. Street generated flows east of the high point flow east to Madison Street (0.13 acres). North of the high point, street flows on the north side of the centerline in Beth Circle will be collected by two proposed catch basins to be constructed as a part of TM 30378. Street generated flows south of the centerline of Beth Circle (0.10 acres), impact this site from the north. As this site is presently a citrus orchard, flows originating on -site are retained on -site, thereby, the site to the immediate south is not impacted by this site. ' DEVELOPED DRAINAGE MANAGEMENT PLAN This drainage analysis has been prepared in support of the approved preliminary ' hydrology plan per City of La Quinta Resolution No. .2005-098, Conditions of Approval for Tentative Tract 33085, Core Homes, LLC. 7 L 7 J n, IJ Onsite Storm Runoff: The proposed drainage management plan calls for onsite developed storm flows, not percolating within each lot, to surface discharge into Kiwi Court. Collected storm flows will be routed east within the street gutter pan to an adequately sized catch basin, located in a sump condition, near the southeast corner of the site. Collected storm flows will be retained, and percolated, within an on -site retention facility. Offsite Storm Runoff: Per the approved hydrology plan for TM 30378, this site is responsible for collecting, and retaining off -site storm flows from the portions of Beth Circle defined above which impact this site directly, or indirectly via Madison Street. Those off -site drainage areas, #s 11 & 12 from the TM 30378 study, generate estimated storm volumes of 1,169 cf, and 2,769 cf, respectively. The defined site improvements for TM 33085 will thereby be sized to collect and retain these off -site flows. Street flows from off -site drainage area #11 ( 0.10 acres from TM 30378 study) enter the site via Starfruit Trail, surface discharge to Kiwi Court to be routed to the aforementioned catch basin adjacent to the on -site retention facility. Flows generated from east of the high point in Beth Circle enter Madison Street, and are routed south to a proposed catch basin along the west curb in Madison, adjacent to the on -site retention facility. Thereby, the extent of the Madison Street tributary area extends from the northernmost return at Beth Circle to the aforementioned catch basin (0.81 acres). ¢ Coachella Land — Storm Water Management 5 /30 /2007Report Prepared by: Coachella Valley Engineers ' Retention Basin: The on -site retention facility is to be located on an approximate 0.23 acre parcel located ' near the southeast portion of the site. As designed, the basin bottom elevation is at 505, with a top of slope elevation of 511. The planned basin shall conform with City of La Quinta standards, including a maximum of 3:1 side slopes, 6 ft maximum depth, 1 ft ' minimum freeboard as measured from the lowest adjacent street flowline grade. A Maxwell Plus (or equal) drywell system is proposed along the bottom of the basin to collect nuisance flows, and runoff waters from smaller storm events. ' Storm waters will enter the retention basin at two locations. An onsite catch basin to be located near the east end of Kiwi Court will outfall into the retention basin via a 24" ' outfall pipe. An additional catch basin is planned along the west curb of Madison Street with an 18" outfall line discharging flows into the basin. Childproof grates are planned at the ends of both outfall pipes. ' As designed, the proposed retention basin has a maximum cumulative storage capacity (as measured from top of slope to basin bottom) of 41,589 cubic feet. Design calculations reflect that the maximum required retention volume is for the 100 -year, 3- ' hour storm at 33,425 cubic feet. As an added factor of safety, a storage volume of 35,000 cubic feet has been allowed for which results in a 100 -year ponding depth of 5.66' at an elevation of 510.16. With that 1.10' of freeboard is provided as measured ' from the water surface level (WSL) to the lowest adjacent street flowline elevation, 511.26 ' In the event that storm volumes exceed design volumes, excess storm waters will exit the retention facility via the catch basins on Kiwi Court, and Madison Street. SUMMARY Following the conditions identified in Resolution No. 2005 -098 the defined developed ' drainage management plan provides for a fail -safe drainage management system that ensures there will be no adverse impacts to downstream properties. I 5 Coachella Land — Storm Water Management 5 /30 /2007Report Prepared by: Coachella Valley Engineers 1111 FG 512.80 IN THE CITY OF LA QUINTA, COUNTY OF RIVERSIDE, STATE OF CALIFORNIA RETENTION BASIN CONTOURS TRACT MAP N0. 33085 IN THE NE1 /4 OF THE SE1 /4 OF SECTION 4, T.6S., R.7E. SBM RETENTION BASIN SUMMARY TABLE 1� O -o °o 1 FT. - FREEBOARD ELEV. AREA (SF) AREA CHANGE (SF) VOL /FT (CF) CUMUL VOL. (CF) 411.00 10,367 1,221 9,757 41,589 410.00 9,146 1,221 8,536 31,833 409.001 7,925 1,221 7,315 23,297 408.00 6,704 1,221 6,093 15,983 407.00 5,482 1,221 4,872 9,890 406.00 4,261 1,221 3,651 5,018 405.00 3,0401 610 1,368 1,368 404.50 1 2,4301 0 1 0 1 0 r0,o\ S,�00 \ 1 FT. FREEBOARD LOT "E" 10,366 S.F. Bob. L.S. /RET. 150v '`SO RETENTION BASIN ooh TOP 511.00 BOTTOM 504.50 10 WSioo= 510.16 WStw Vol = 35,000CF OVERFLOW TO STREET BOT 504.50 TOP 511.00 GRAPHIC SCALE 20 0 10 20 40 60 ( IN FEET ) 1 inch = 20 ft. 04220 RETENTION BASIN SUMMARY TABLE ELEV. AREA (SF) AREA CHANGE (SF) VOL /FT (CF) CUMUL VOL. (CF) 411.00 10,367 1,221 9,757 41,589 410.00 9,146 1,221 8,536 31,833 409.00 7,925 1,221 7,315 23,297 408.00 6,704 1,221 6,093 15,983 407.00 5,482 1,221 4,872 9,890 406.00 4,261 1,221 3,651 5,018 405.00 3,040 610 1,368 1,368 404.50 2,430 0 0 0 Al 14' Sandfilter per City of Lo Quinta Std. 307 DRAINAGE AREA MAP STORM DRAIN /RETENTION BASIN EXHIBIT TRACT 33085 CORE HOMES, L.L.C. FL 515.80 FL 515.40 515.20 FL 514.40 HP \ \ . TC 513.95 to FL 516.30 HP I� TC 515.27 0.5% 05% rr s OLD ORCHARD LANE (PR VATE SMEEO BETH CIRCLE BETE CIRCLE - OFFSITE (PR VATE MWO DRAINAGE AREA = 0.10 AC. ' 0.5% 1 C 513.90 21,78 A S.F. ° � � � � FL 513.60 P 514.12 PE 515.6 I � I TC 513.76 7 `} to to I 21,780 S.F. h ►� '^ � � PE 914.4 (n' TC 513.44 TC 512.92 TC 512.48 1.05 %_ TC 515.21 e96 TC 514.57 5 \ TC 514.63 TC 51 0.52% v.�vti � ONSITE DRA17VAGE KIWI COURT AREA = 4.32 AC. �PRA/ATE STREET) 0.50% � I TC 512.22 TC 514.50 'o 0 �� 6 I I 4 0.50 AC. 3 2 21,76 0 S.F. 21,780 S.F. TC 514.72 0.50 AC. PE 515.2 0.50 AC. PE 516.6 TO 514.79 o O TC 515.27 0.5% 05% rr s OLD ORCHARD LANE (PR VATE SMEEO BETH CIRCLE BETE CIRCLE - OFFSITE (PR VATE MWO DRAINAGE AREA = 0.10 AC. ' 0.5% 1 C 513.90 21,78 A S.F. ° � � � � FL 513.60 P 514.12 PE 515.6 I � I TC 513.76 7 `} to to I 21,780 S.F. h ►� '^ � � PE 914.4 (n' TC 513.44 TC 512.92 TC 512.48 1.05 %_ TC 515.21 e96 TC 514.57 5 \ TC 514.63 TC 51 0.52% v.�vti � ONSITE DRA17VAGE KIWI COURT AREA = 4.32 AC. �PRA/ATE STREET) 0.50% � I TC 512.22 TC 514.50 6 I I 4 0.50 AC. 3 21,76 0 S.F. 21,780 S.F. k 0.50 AC. PE 515.2 0.50 AC. PE 516.5 o O II O II FL 516.2 HP 0.5% I FL 515.5 FL 514.9 0.8X l GRAPHIC SCALE 50 0 25 50 100 150 ( IN FEET ) 1 inch = 50 ft. 0' 7X FL 513.40 �/00 o LO Mi nj / W) h 0Ix 0 /Oq° 77 TC 513.01 0.97.`8 C 513.12 ( I TC �51J.07 TC TC 5 f 1.82 5 Ce 12 suMP 21,780 S.F. TC 511.93 } }p 0.50 AC. Oro= 6.49 CFS o I I PE 514.1 0,w= 10.37 CFS W=4' &PROP MAXWELL - FL 512.60 FL 513.8 FL 513.80 FL 512.80 LZ HP 1.0% X04. TOP 513.00 TTOM 51 504.50 oo= 0.16 oI i S I. h TC 512.22 6 fTC512.17 21,780 S.F. 0.50 AC. PE 513.9 TC 511.73 77 TC 513.01 0.97.`8 C 513.12 ( I TC �51J.07 TC TC 5 f 1.82 5 Ce 12 suMP 21,780 S.F. TC 511.93 } }p 0.50 AC. Oro= 6.49 CFS o I I PE 514.1 0,w= 10.37 CFS W=4' &PROP MAXWELL - FL 512.60 FL 513.8 FL 513.80 FL 512.80 LZ HP 1.0% X04. TOP 513.00 TTOM 51 504.50 oo= 0.16 oI i S I. h . 1 IAJ 1 1 � � II O � 4 l �Q W TLC -PTO OF CURB CB- CATCH BASIN SD - STORMDRAIN o h p n DI - DRAIN INLET DW- DRY WELL HP - HIGH POINT (E) - EXISTING LP - LOW POINT FL - FLOW LINE m - NOTE - - - DRAINAGE FLOWLINE - DRAINAGE FLOW ARROW - DRAINAGE BOUNDARY LINE RETENTION BASIN VOLUME CALCS. FOR TM #33085 Adjacent Roadway Flowline = 511.26 100 -Yr Pond WSL = 510.16 ELEVATION AREA AREA CHANGE VOL/FT (Avg) CUML VOL SF SF CF CF 411.00 10,367 1,221 9,757 41,589 410.00 9,146 1,221 8,536 31,833 409.00 7,925 1,221 7,315 6,093 23,297 408.00 6,704 1,222 15,983 407.00 5,482 1,221 4,872 9,890 406.00 4,261 1,221 3,651 5,018 405.00 3,040 610 1,368 1,368 404.50 2,430 0 0 0 Vol. @ WSL = 35,OOOcf ' O rtfl\ ansi\ deff0 (\fonttbl( \f0 \fnil \fcharset0 Courier New;)) \viewkind4 \uc 1 \pard \fang 1033 \f0 \fs20 \par\tab\tab Un it Hydrograph Analysis ' \par .. \par \tab \tab Copyright (c) CIVILCADD /CIVILDESIGN, 1989 - 2004, Version 7.0 \par \tab \tab \tab Study date 11/15/07 File: COREHOMES3HR3100.out \par \par \par \tab +++++++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++ ' \par \tab ------------------------------------------------------------------------ \par \par \tab Riverside County Synthetic Unit Hydrology Method \par \tab RCFC & WCD Manual date - April 1978 \par \par \par \tab Program License Serial Number 6078 \par \par \tab ------------------ 7 -------------------------------------------------- \par \tab English (in -lb) Input Units Used ' \par \tab English Rainfall Data (Inches) Input Values Used \par \par \tab English Units used in output format \par ' \par \par \par \tab --------------------------------------------------------------------- \par \tab -------------------- -- ---------------------------------------------- \par \tab Drainage Area = 5.23(Ac.) = 0.008 Sq. Mi. 1 i \par \tab Drainage Area for Depth -Area Areal Adjustment = 5.23(Ac.) = 0.008 Sq. Mi. \par \tab Length along longest watercourse = 610.00(Ft.) \par \tab Length along longest watercourse measured to centroid = \par \tab Length along longest watercourse = 0.116 Mi. \par \tab Length along longest watercourse measured to centroid = \par \tab Difference in elevation = 5.00(Ft.) \par \tab Slope along watercourse = 43.2787 Ft. /Mi. \par \tab Average Manning's 'N' = 0.015 \par \tab Lag time = 0.026 Hr. \par \tab Lag time = 1.57 Min. \par \tab 25% of lag time = 0.39 Min. \par \tab 40% of lag time = 0.63 Min. \par \tab Unit time = 15.00 Min. \par \tab Duration of storm = 3 Hour(s) \par \tab User Entered Base Flow = 0.00(CFS) \par \par \tab 2 YEAR Area rainfall data: \par \par \par \tab Area(Ac.)[1] Rainfall(In)[2] Weighting[) *2] \par \tab 5.23 \tab 0.75 \tab \tab 3.92 \par \par \tab 100 YEAR Area rainfall data: \par 304.00(Ft.) 0.058 Mi. 1 r � I � I �I I� \par \par \tab Area(Ac.)[1] Rainfall(In)[2] Weighting[1 *2] \par \tab 5.23 \tab 2.20 \tab \tab 11.51 \par \par \tab STORM EVENT (YEAR) = 100.00 \par \tab Area Averaged 2 -Year Rainfall = 0.750(In) \par \tab Area Averaged 100 -Year Rainfall = 2.200(In) \par \par \tab Point rain (area averaged) = 2.200(ln) \par \tab Areal adjustment factor= 100.00% \par \tab Adjusted average point rain = 2.200(ln) \par \par \tab Sub -Area Data: \par \tab Area(Ac.) Runoff Index Impervious % \par \tab 1.490 56.00 0.900 \par \tab 3.740 56.00 0.450 \par \tab Total Area Entered = 5.23(Ac.) \par \par \par \tab RI RI Infil. Rate Impervious Adj. Infil. Rate Area% F \par \tab AMC2 AMC -3 (In /Hr) (Dec. %) (In /Hr) (Dec.) (In /Hr) \par \tab 56.0 74.8 0.305 0.900 0.058 0.285 0.017 \par \tab 56.0 74.8 0.305 0.450 0.182 0.715 0.130 \par Sum (F) = 0.146 \par \tab Area averaged mean soil loss (F) (In /Hr) = 0.146 \par \tab Minimum soil loss rate ((In /Hr)) = 0.073 \par \tab (for 24 hour storm duration) \par \tab Soil low loss rate (decimal) = 0.670 \par \tab --------------------------------------------------------------------- \par \par \tab \tab \tab U n it H y d r o g rap h \par \tab \tab \tab \tab DESERT S -Curve \par \tab -------------------------------------------------------------------- \par \tab \tab \tab Unit Hydrograph Data \par \tab --------------------------------------------------------------------- \par \tab Unit time period Time % of lag Distribution Unit Hydrograph \par \tab (hrs) Graph % (CFS) \par \tab --------------------------------------------------------------------- \par \tab 1 0.250 954.584 100.000 5.271 \par \tab Sum= 100.000 Sum= 5.271 \par -------------------- 7 -------------------------------------------------- \par \par \par Unit Time Pattern Storm Rain Loss rate(In. /Hr) Effective \par (Hr.) Percent (In /Hr) Max I Low (In /Hr) \par 1 0.25 3.70 0.326 0.146 - -- 0.18 \par 2 0.50 4.80 0.422 0.146 - -- 0.28 \par 3 0.75 5.10 0.449 0.146. - -- 0.30 \par 4 1.00 4.90 0.431 0.146 - -- 0.28 \par 5 1.25 6.60 0.581 0.146 - -- 0.43 \par 6 1.50 7.30 0.642 0.146 - -- 0.50 \par 7 1.75 8.40 0.739 0.146 - -- 0.59 ' \par 8 2.00 9.00 0.792 0.146 - -- 0.65 \par 9 2.25 12.30 1.082 0.146 0.94 \par 10 2.50 17.60 1.549 0.146 - -- 1.40 ' \par 11 2.75 16.10 1.417 0.146 = - 1.27 \par 12 3.00 4.20 0.370 0.146 0.22 \par Sum = 100.0 Sum = 7.0 ' \par \tab Flood volume = Effective rainfall 1.76(In) \par \tab times area 5.2(Ac.) /((In) /(Ft.)] = 0.8(Ac.Ft) \par \tab Total soil loss = 0.44(in) ' \par \tab Total soil loss = 0.191(Ac.Ft) \par \tab Total rainfall = 2.20(ln) \par \tab Flood volume = 33424.5 Cubic Feet \par \tab Total soil loss = 8341.4 Cubic Feet ' \par \tab -------------------------------------------------------------------- \par \tab Peak flow rate of this hydrograph = 7.395(CFS) \par \tab -------------------------------------------------------------------- \par \tab +++++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++ \par \tab 3 -HOUR STORM \par \tab Runoff Hydrograph \par \tab -------------------------------------------------------------------- ' \par \tab Hydrograph in 15 Minute intervals ((CFS)) \par \par \tab -------------------------------------------------------------------- \par Time(h +m) Volume Ac.Ft Q(CFS) 0 2.5 5.0 7.5 10.0 \par ----------------------------------------------------------------------- \par 0 +15 0.0195 0.94 V Q I I I ' \par 0 +30 0.0496 1.46 IV Q \par 0 +45 0.0825 1.59 I V Q I I \par 1+0 0.1135 1.50 1 VQ I I I I \par 1+15 0.1609 2.29 1 VQI I I I \par 1+30 0.2149 2.62 1 QV \par 1+45 0.2795 3.13 1 I Q V I I I \par 2+0 0.3498 3.40 I 1 Q VI I I \par 2 +15 0.4518 4.94 1 I Q V I I \par 2 +30 0.6046 7.40 I 1 1 QIV I j \par 2 +45 0.7430 6.70 I 1 1 Q' I VI \par 3+0 0.7673 1.18 I Q I I I V \par ------------- 7 --------------------------------------------------------- \par t \par \par \par i \par } 11 r 1 IJ iJ I � I IF IF HYDROLOGY CALCULATIONS ...TM30378..TM33085 As originally agreed in the meeting at city hall and again reinforced yesterday, I am submitting the "previously approved synthetic unit hydrographs" as calculated by using the Bondiman Civil Desk computer program. Very simple ...but confusing by the inter mixing of old Hydrology reports.. very old hydrology reports and—very very old hydrology reports ... I shall demonstrate the difference and or similarities of the SUH method to the rational method.. TM 33085 ... 100year..3hr. storm.. SUH calculations for 0.43 acres of paving runoff area......6584x 0.43/1.02 = 2776CF SUH calculation for 3.73 acres of unimproved area ...... 4662 x 0.87 x 4.3 = 17441 CF Area no. 11 from TM 30378.....1169CF Area no. 12 from TM 30378.....2769CF THEREFORE AS SHOWN ON TM33085 DRAINAGE MAP..TOTAL VOLUME TO BE COLLECTED IN THE RETENTION BASIN IS:....24,155 CF Maximum basin volume is 38,148 cfs @ freeboard elevation Water Depth for 24, 155cfs is 4.5 feet. For comparison to the same area for rational analysis for 4.76 acre storm ... 100 year 24 hour,storm generates 25,725 CF of stormwater.... Verses-the SUH method for the 100 year, three hour storm of 20217 cfs of stormwater.. . U n i t H y d r o g r a p h " A n a l y s i s Copyright (c) CIVILCADD /CIVILDESIGN, 1989 - 2004, Version 7.0 ' Study date- 05/07/07 File: VDB5W13100.out +++++++++++++++++++++++++++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ++ + + + + ++ ---------------- --------------------- - Riverside County Synthetic Unit Hydrology Method RCFC & WCD Manual date - April 1978 Program License Serial Number 6078 English (in -lb) Input Units Used English Rainfall Data (Inches) Input Values Used English Units used in output format CITLAQUINTA COACHELLA VALLEY ENGINEERS DKRICE ------------------------------------------- Drainage Area = 0.87(Ac.) = 0.001 Sq. Mi. - Drainage Area for Depth -Area Areal Adjustment = 0.07(Ac.) - 0.000 Sq. Mi. USER Entry of lag time in hours Lag time = 0.080 Hr. Lag time = 4.B0 Min. 25% of lag time = 1.20 Min. 40% of lag time. = 1.92 Min. Unit time 15.00 Min.. Duration of storm = 3 Hour(s) User Entered Base Flow = 1.04(CFS) 2 YEAR Area rainfall data: Area (Ac.) (1] Rainfall (In) [2) Weighting.( 1*-21 0.07 1.04 0.07 100 YEAR Area rainfall data:' Area (Ac.) [1] Rainfall (In) (2) Weighting [1 *2] 0.07 2.54 0.18 STORM EVENT (YEAR) = 100.00 Area Averaged 2 -Year Rainfall •= 1.040(In)' Area.Averaged 100 -Year Rainfall = 2.540(In) Point rain (area averaged) = 2.540(In). Areal adjustment factor = 100.00 Adjusted average point rain = 2.540(In) Sub -Area Data: Area(Ac.) Runoff Index Impervious .% 0.070 56.00 0.200 0.000 56.00 0.000 0.800 56.00 0.30.0 Total Area Entered = 0.87(Ac.) RI RI Infil. Rate Impervious Adj. Infil. RateDeAr;a% F AMC2 AMC -2 (In /Hr) (Dec . %) (In /Hr) (In /Hr) 56.0 56.0 0.511 0.200 0.419 0.080 0.034 56.0 56.0 0.511 0.000 0.511 0.000 0.000 56.0 56.0 0.511 0.300 0.373 0.920 0.343 Sum (F) _ 0.377 Area averaged mean soil loss (F) (In /Hr) = 0.377 Minimum soil loss rate ((In /Hr)) = 0.186 (for 24 hour storm duration) Soil low loss rate (•decimal) _ 0.300 U n i t H y d r o g r a p h DESERT'-.S -Curve Unit Hydrograph Data ------------------------------- Unit time period Time % of lag Disttrribu%tion Unit HCFS)graph Graph (hrs) 1 0.250 312.500 57.461 0.504 2 0.500 625.000 37.948 0.333 3 0.750 937.500 4.591 0.040 Sum = 100.000 Sum= 0.877 Unit Time Pattern Storm Rain Loss rate(In. /Hr) Effective (In/ Hr) (Hr.) Percent (In /Hr) Max Low 0.377 0.113 0.26 1. 0.25 3.70 0.376 0.377 - -- 0.11 2 0.50 4.80 0.488 0.377 - -- 0.14 3 0.75 5.10 0.518 0.377 - -- 0.12 4 1.00 4.90 0.498 0.377 - -- 0 29 5 1.25 6.60 0.671 0.377 - -- 0.37 6 1.50 7.30 0.742 0.377 - -- 0 a8 7 1.75 8.40 0.853 0.377 - -- 0.54 8 2.00 9.00 0.914 lu 9 2.25 12.30 1.250 0.377 - -- 0.87 10 2.50 17.60 1.788 0.377 1.41 11 2.75 - -- 16.10 1.636 0.377 1'26 12 3.00 4.20 0.427 0.377 --- 0.05 Sum = 100.0 Sum = 5.9 Flood volume = Effective rainfall 1.48(In) times area 0.9(Ac.) /[(In) /(Ft.)] = 0.1(Ac.Ft) Total soil loss = 1.06(In) ' Total soil loss = 0.077(Ac.Ft) -�`44 ` Total rainfall = 2.54(In) �( .-s C F 5 "'i I 1 Flood volume = 4662.0 Cubic Feet ' Total 33596 Cubic -Feet soil loss _ = --- -_ - -- - Peak flow rate of this hydrograph = 2.180(CFS) ---- _______ -------- ----- ______ --- ---- ---- _ __ ---- _ __ ---- _ --- ----- ____ + + ++ +++++++++++++++++++++++++++++++++++ + + + + + + + + + + ± + + + + + + + + + + + + + + + + 3 - H O U R S T 0 R M ---- - R u n o f f H y d r o g r a p h - ---- -------------- ----- - ---- ---- Hydrograph in 15 Minute intervals ((CFS)) ' ----------------------------- Time(h +m) ;------------------------------------ Volume Ac.Ft Q(CFS) 0 2.5 5.0 7.5 10.0 1 0 +15 - _- -_ - -__ 0.0242 1.17 V Q 0 +30 0.0487 1.18 Q 0 +45 0.0726 1.16 Q V 1+ 0 0.0964 1.15 Q VI 1 I 1.23 I Q V 1 1 +15 0.1219 1 +30 0.1494 1.33 I Q I' I 1 +45 0. 1.786 1.41 Q I V 2+ 0 0.2092 .1.48 Q •I V 2 +15 0.2439 1.68 Q I I V I' 2 +30 0.2866 2.06 Q I V I 2 +_4 5 0.3316 2.18 Q I I V 3+ 0 0.3634 1.54 Q I V 3 +15 0.3863 1.11 Q I V ;i 3 +30 0.4079 1.04 Q V II� lu U n i t H y d r o g r a p h A n a l y s i s Copyright (c) CIVILCADD /CIVILDESIGN, 1989 - 2004, Version 7.0 Study date 05/07/07 File: VA9DBBEM DW3100.out '+.. .+. {. +.....'i'.... + +..{'..,". .. ..{..'F..... '.. ..{'.}..F.. . j....j.T. ..j.T.+..{...{....{. +T.}..}. ..{' Riverside County Synthetic Unit Hydrology Method RCFC & WCD Manual date - April 1978 Program License Serial Number 6078 English (in -lb) Input Units Used English Rainfall Data (Inches) Input Values Used English Units used in output format VANDEBOS TM 30399..BEMADW CITY OF LA QUINTA COACHELLEY VALLEY:ENGINEERS DKRICE ---------------------------------------------- - - - - -- Drainage Area = 1.02(Ac.) = 0.002 Sq. Mi. - Drainage Area for Depth -Area Areal Adjustment = 0.44(Ac.) - 0.001 Sq. Mi. USER Entry of lag time in hours Lag time = 0.080 Hr. .Lag time = 4.80 Min. 25% of lag time = 1.20 Min. 40% of lag time = 1.92 Min. Unit time = 15.00 Min. Duration of storm = 3 Hours) User Entered Base Flow = 1.04(CF.S) 2 YEAR Area rainfall data: Rainfall(In)[2] Weighting[1 *2] 0.44 1.04 0.46 100 YEAR Area rainfall data: Area (Ac.) [ll Rainfall (In) [2] weighting [1 *2J 0.44 2.54 1.12 STORM EVENT (YEAR) = 100.00 0 I Area Averaged 2 -Year Rainfall = 1.040(In) Area Averaged 100 -Year Rainfall = 2.540(In) Point rain (area averaged) = 2.540(In) Areal adjustment factor = 100.00 % Adjusted average point rain.= 2.540(In) Sub -Area Data: Area(Ac.) Runoff Index Impervious 0.440 56.00 0.900 0.580 56.00 0.300 Total Area Entered = 1.02(Ac.) RI RI Infil. Rate Impervious AMC2 AMC -2 (In /Hr) (Dec. %) (In /Hr) 1.00 5 1.25 56.0 56.0 0.511 0.900 0.042 2.00 9 2.25 56.0 56.0 0.511 0.300 0.212 Adj. Infil. Pate Area% (In /Hr) (Dec.) 0.097 0.431 0.373 0.569 0.254 Area averaged mean soil loss (F) (In /Hr) = 0.254 Minimum soil loss rate ((In /Hr)) = 0.127 (for 24 hour storm duration) Soil low loss rate (.decimal) = 0.450 ------------------------------- - - - - -- U n i t H y d r o g r a p h DESERT S -Curve Unit Hydrograph Data ------------------------------------- - - - - -- Sum (F) = F Unit time period Time % of lag . Distribution Unit Hydrograph (hrs) Graph % (CFS) -------------------------------------- - - - - -- 1 0.250 312.500 57.461 0.591 2 0.500 625.000 37.948 0.390 3 0.750 937.500 4.591 0.047 Sum = 100.000 Sum= 1.028 ----------------------------------------- - - - - -- Unit Time Pattern Percent 3.70 4.80 5.10 4.90 6.60 7.30 8.^_0 9.00 12.30 17.60 16.10 Storm Rain (In /Hr) 0.376 0.488 0.518 0:498 0.671 0.742 0.853 0.914 1.250 1.788 1.636 Loss rate(In. /Hr) Max Low 0.254 --- .0.254 --- 0.254 --- 0.254 - -- 0.254 - -- 0.254 - -- 0.254 - -- 0 X54 --- 0.254 - -- 0.254 - -- 0.25- - -- Effective (In /Hr) 0.12 0.23 0.26 0.24 0.42 0.49 0.60 0.66 1.00 1.53 1.38 (Hr.) 1 0.25 2 0.50 3 0.75 4 1.00 5 1.25 6 1.50 7 1.75 8 2.00 9 2.25 10 2.50 11 2.75 Pattern Percent 3.70 4.80 5.10 4.90 6.60 7.30 8.^_0 9.00 12.30 17.60 16.10 Storm Rain (In /Hr) 0.376 0.488 0.518 0:498 0.671 0.742 0.853 0.914 1.250 1.788 1.636 Loss rate(In. /Hr) Max Low 0.254 --- .0.254 --- 0.254 --- 0.254 - -- 0.254 - -- 0.254 - -- 0.254 - -- 0 X54 --- 0.254 - -- 0.254 - -- 0.25- - -- Effective (In /Hr) 0.12 0.23 0.26 0.24 0.42 0.49 0.60 0.66 1.00 1.53 1.38 - -- 0.17 12 3.00 4.20 0.427 0' S" 4 Sum = 7.1 Sum = 100.0 Flood volume = Effective rainfall 1.78(In) 0 2(Ac.Ft) times area 1.0 (Ac . ) / [ (In) / (F t .) ] _ Total soil loss = 0.76(In) Total soil loss = 0.065(Ac.Ft) Total rainfall = 2.54 (In) 6.4 Si �� C 5 Flood volume = 6584.3 Cubic Feet Z7% Total soil loss = 2820.2 Cubic Feet Peak flow rate of this hydrograph = 2.502(CFS) -------------------------- + + + + + + + + + + + + + + + + + + + + + + + + ++ ++++++++++++++++++++++++++++++++++ + + + + + + 3 - H O U R S T O R R u n o f f H y d r o g r a p h Hydrograph in 15 Minute intervals ((CFS)) -- , Time(h +m) volume Ac.Ft Q(CFS) 0 2.5 5.0 7.5' 10.0 0 +15 0.0230 1.11 ------ - - - - -- 0 +30 0.0483 1.23 I Q 0 +45 0.0750 1.29 I QV 1+ 0 0.1018 1.30 I Q VI 1 +15 0.1306 1.39 I Q V 1 +30 0.1617. 1.50 I Q I V 1 +e5 0.1948 1.60 I Q I V 2+ 0 0.2297 1.69 I Q I V I 2 +15 0.2693 1.91 V I I Q 2 +30 0.3182 2.37 QI I V 2 +45 0.3699 2.50 Q I I v I 3+ 0 0.4061 1.75 I v I Q v 3 +15 0.4303 1.17 I Q 3 +30 0.4520 1.05 I Q V -------------------- - - - - -- ------------------- I MADISON STREET CARRYING CAPACITY ' Per TM No. 30378, two catch basins are planned along the frontage of that site along the west curb line of Madison Street. The resulting Madison Street drainage area to be intercepted by this site thus includes the west `/z of Madison Street south of the planned inlet to be located at the PC of the north return at Beth Circle. Madison Beth Circle Total area = (95' x 325') + (30' x 140') = 35,174 sf (0.81 acres) ' Design 0-10 year: C, runoff coefficient = 0.82 (From Plate D -5.7) ' I, rainfall intensity = 1.79 in/hr (I Oyr — From Plate D -4.1) A, drainage area = 0.81 Acres ' Q(10) = 0.82 * 1.79 in/hr * 0.81acres =1.19 CFS Design 0-100 year: ' C, runoff coefficient = 0.82 (From Plat D -5.7) I, rainfall intensity = 2.86 in/hr (100yr — From Plate D -4.1) ' A, drainage area = 0.81 acres Q(100) = 0.82 * 2.86 in/hr * 0.81 acres =1.90 CFS ' % Madison Street Section: 50' from ROW to centerline, 6" outer curb & gutter, 6" median curb. ' 34' face to face, Check Spread of Flow per FH`VA HEC -22 "Urban Drainage Design Manual" ' T = [(Q *n)/ ( Ku )(Sx)expl.67(S1)exp0.5]exp0.375 Ku = 0.56, n = 0.013, Q = flow rate (cfs), T = width of flow (ft), Sx = cross slope (ft /ft) ' S1= longitudinal slope (ft/ft) 10 - Year: T = [ (1.19cfs * .013) / (.56)(.02)expl.67(.005)exp.5 ]exp.375 T = 8.15' Therefore, 10 -year flow extends from face of curb 8.15' info roadway. Flow height at outer curb is .0.25' ' 100 — Year: T = [ (1.90cfs * .013) / (. 56) (.02)expl.67(.005)exp.5]exp.375 T = 9.71' Therefore, 100 -year flow extends from face of cub 9.71' into roadway. Flow height at outer curb is 0.28' n MADISON STREET DOWNSTREAM CARRYING CAPACITY The purpose of this analysis is to consider the storm flows within Madison Street, downstream of the Core Homes site. The reach considered in this analysis extends from Beth Circle (inlets along Vandenbos site intercept storm flows above Beth Circle) to the intersection of Avenue 52 ( L = 2,000 If). Madison . Beth Circle (1/2 ROW + Pkwy) - Total area = (75' x 2;000') + (30' x 140') = 154,200sf = 3.54acres Design 0-10 year: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 1.79 in/hr (IOyr — From Plate D -4.1) A, drainage area = 3.54 Acres Q(10) = 0.82 * 1.79 in/hr * 3.54acres = 5.20CFS ' Design 0-100 year: C, runoff coefficient = 0.82 (From Plat D -5.7) ' I, rainfall intensity = 2.86 in/hr (100yr — From Plate D -4.1) A, drainage area = 3.54 acres ' Q(100) = 0.82 * 2.86 in/hr * 3.54 acres = 8.30 CFS '/Z Madison Street Section: ' 50' from ROW to centerline, 6" outer curb & gutter, 6" median curb. 34' face to face (2 — 12 ` travel lanes w/ 10' outer bike lane) I Check Spread of Flow per FHWA HEC -22 "Urban Drainage Design Manual" T = [(Q *n)/ ( Ku )(Sx)expl.67(Sl)exp0.5]exp0.375 I Ku = 0.56, n = 0.013, Q = flow rate (cfs), T = width of flow (ft), Sx = cross slope (ft/ft) S1= longitudinal slope ( ft/ft) ' 10 - Year: T = [ (5.20cfs * .013) / (.56)(.02)exp1.67(.005)exp.5 ]exp.375 T = 14.16 Therefore, 10 -year flow extends from face of curb 14.16' into roadway. t100 — Year: T = [ (8.30cfs * .013) / (. 56) (.02)expl.67(.005)exp.5]exp.375 T = 16.87' Therefore, 100 -year flow extends from face of cub 16.87' into roadway. Given the above calculations, during a 100 -year storm event, the amount of `dry' asphalt is: (34' — 16.87) = 17.13'. During a 100 -year storm event, the depth of flow along the outer curb of Madison Street = 0.34. KIWI COURT CARRYING CAPACITY Design Q -10 year: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 1.79 in/hr (IOyr — From Plate D -4.1) A, drainage area .= 4.42 acres Q(10) = 0.82 * 1.79 in/hr * 4.42acres = 6.49 CFS Design 0-100 year: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 2.86 in/hr (100yr — From Plate D -4.1) A, drainage area = 4.42 acres Q(100) = 0.82 * 2.86 in/hr * 4.42 acres =10.37 CFS Kiwi Court Street Section: 40' face to face, 6" outer curb, no median curb Check Spread of Flow per FHWA HEC -22 "Urban Drainage Design Manual T = [(Q *n)/ ( Ku )(Sx)expl.67(Sl)exp0.5]exp0.375 Ku = 0.56 n = 0.013 Q = flow rate (cfs) T = width of flow (ft) Sx = cross slope ( ft/ft) S1= longitudinal slope (ft/ft) 10 - Year: T = [ (6.49cfs * .013) / (.56)(.02)expl.67(.005)exp.5 ]exp.375 T = 15.39 Therefore, 10 -year flow extends from face of curb 15.39' into roadway. Flow height at outer curb is 0.39' 100 — Year: T = [ (10.37cfs * .013) / (. 56) (.02)expl.67(.005)exp.5]exp.375 T =18.34 Therefore, 100 -year flow extends from face of curb 18.34' into roadway. Flow height at outer curb is 0.45' MADISON STREET CATCH BASIN & PIPE PREPARED BY COACHELLA VALLEY ENGINEERS DATE: 5 -30 -07 JOB #: 04220 PROJECT: TR 33085 BY: jsd PIPE BASIN GRATE NET EXIT LOSS LOSS AT D.S. HGL10 STORM DRAIN LINE: "B "- 10 year DIA.(IN) Q10(CFS) WS10 OPENING(FT) OPENING(SF) AT GRATE END OF PIPE . OUTLET DESIGN (DRY WELL) 1.1HV= 1.2HV= 18 1 1.19 1 507.33 2.00 1.387 0.008 0.008 WS10 IN BASIN 507.330 0.008 VELOCITY IN 18 " PIPE Q= • 1.19 0.67 PER SEC. HV= V2 /2G= 0.007 0.008 A= 1.77 V =Q/A HGL AT U.S. END 507.346 STORM DRAIN LINE LENGTH OF PIPE(d) 48.00 MANNING "S INDEX(n) 0.012 TYPE OF PIPE RCP Sf =[ Q n ] 2 K' =0.463 Sf =[ 0.014280 ]2= 0.000109 [d 873(K')] [ 1.366925 ] Hf =L(Sf) Hf= 0.0052 HGL AT U.S.END= 507.351 1.2HV= 0.008 10YR WS IN CB= 507.360 DESIGN FOR CATCH BASIN NO. 2 PROP. WIDTH OF OPENING (W)(FT) CURB HEIGHT (IN) DEPTH OF DEPRESSION (IN) DEPTH OF FLOW AT OPENING (H)(FT) HEIGHT OF OPENING (h)(IN) Q10 TO OPENING (CFS) TC AT OPENING 4.00 H /h= 0.36 6.00 Q/L= 2.50 4.00 0.30 10.00 1.19 512.09 VS HGL (PONDED TO TC) Q= 1.19 0.48 FOOT WIDE OPENING (MIN) (Q/L) 507.36 OK 2.50 USE W(MIN)= 4.00 OK MADISON STREET CATCH BASIN & PIPE PREPARED BY COACHELLA VALLEY ENGINEERS DATE: 5 -30 -07 48.00 MANNING "S INDEX(n) 0.012 JOB #: 04220 TYPE OF PIPE RCP . Sf =[ Q n ] 2 K' =0.463 Sf =[ 0.022800 ]2= 0.000278 [d 8/3(K')] PROJECT: TR 33085 Hf =L(Sf) Hf= 0.0134 BY: jsd PIPE BASIN GRATE NET EXIT LOSS LOSS AT D.S. HGL100 STORM DRAIN LINE: "B" - 100 year DIA.(IN) Q100(CFS) WS100 OPENING(FT) OPENING(SF) AT GRATE END OF PIPE OUTLET DESIGN (DRY WELL) 1.1 HV= 1.2HV= 18 1 1.90 1 510.16 2.00 1.38 0.020 0.022 WS100 IN BASIN 510.160 0.020 VELOCITY IN 18 " PIPE Q= 1.90 1.08 PER SEC. HV= V2 /2G= 0.018 0.022 A= 1.77 V =Q/A HGL AT U.S. END 510.201 STORM DRAIN LINE LENGTH OF PIPE(d) 48.00 MANNING "S INDEX(n) 0.012 TYPE OF PIPE RCP . Sf =[ Q n ] 2 K' =0.463 Sf =[ 0.022800 ]2= 0.000278 [d 8/3(K')] [ 1.366925 ] Hf =L(Sf) Hf= 0.0134 HGL AT U.S.END= 510.215 1.2HV= 0.022 100YR WS IN CB= 510.236 DESIGN FOR MADISON ST. CB PROP. WIDTH OF OPENING (W)(FT) CURB HEIGHT (IN) DEPTH OF DEPRESSION (IN) DEPTH OF FLOW AT OPENING (H)(FT) HEIGHT OF OPENING (h)(IN) Q100 TO OPENING (CFS) TC AT OPENING 4.00 H /h= 0.36 6.00 Q/L= 2.50 4.00 0.30 10.00 1.90 512.09 VS HGL (PONDED TO TC) Q= 1.90 0.76 FOOT WIDE OPENING (MIN) (Q /L) 510.24 OK 2.50 USE W(MIN)= 4.00 OK ONSITE CATCH BASIN & PIPE PREPARED BY COACHELLA VALLEY ENGINEERS. DATE: 5 -30 -07 JOB #: 04220 PROJECT: TR33085 BY: jsd PIPE BASIN GRATE NET EXIT LOSS LOSS AT D.S. HGL10 STORM DRAIN LINE: "A "- 10year DIA.(IN) Q10(CFS) WS10 OPENING(FT) OPENING(SF) AT GRATE END OF PIPE OUTLET DESIGN (DRY WELL) 1.1 HV= 1.2HV= 24 1 6.49 1 507.33 2.00 1.38 0.073 0.080 WS100 IN BASIN 507.330 0.073 VELOCITY IN 24 " PIPE Q= 6.49 2.07 PER SEC. HV= V2 /2G= 0.066 0.080 A= 3.14 V =Q/A HGL AT U.S. END 507.482 STORM DRAIN LINE LENGTH OF PIPE(d) 50.00 MANNING "S INDEX(n) 0.012 TYPE OF PIPE RCP Sf =[ Q n ] 2 K' =0.463 Sf =[ 0.077880 ]2= 0.000699 [d 8 /3(K')] [ 2:946667 ] Hf =L(Sf) Hfh 0.0349 HGL AT U.S.END= 507.517 1.2HV= 0.080 10YR WS IN CB= 507.597 DESIGN FOR ONSITE CB PROP. WIDTH OF OPENING (W)(FT) CURB HEIGHT (IN) DEPTH OF DEPRESSION (IN) DEPTH OF FLOW AT OPENING (H)(FT) HEIGHT OF OPENING (h)(IN) Q10 TO OPENING (CFS) TC AT OPENING 5.00 H /h= 0.36 6.00 Q /L= 2.50 4.00 0.30 10.00 6.44 511.93 VS HGL (PONDED TO TC) Q= 6.44 2.58 FOOT WIDE OPENING (MIN) (Q /L) 507.60 OK 2.50 USE W(MIN)= 4.00 OK ONSITE CATCH BASIN & PIPE PREPARED BY COACHELLA VALLEY ENGINEERS DATE: 5 -30 -07 H /h= 0.36 6.00 Q /L= 2.50 (P (PC 4.00 JOB #: 04220 Q= 10.00 (Q /L) 10.30 PROJECT: TR 33085 VS HGL 510.84 OK BY: jsd PIPE BASIN GRATE NET EXIT LOSS LOSS AT D.S. STORM DRAIN LINE: "A" - 100 Year DIA.(IN) Q100(CFS) WS100 OPENING(FT) OPENING(SF) AT GRATE END OF PIPE OUTLET DESIGN (DRY WELL) 1.1 HV= 1.2HV= 24 1 10.37 1 510.16 2.00 1.38 0.186 0.203 WS100 IN BASIN VELOCITY IN 24 " PIPE Q= 10.37 3.30 PER SEC. HV= V2 /2G= 0.169 A= 3.14 V =Q /A HGL AT U.S. END STORM DRAIN LINE LENGTH OF PIPE(d) 50.00 MANNING "S INDEX(n) 0.012 TYPE OF PIPE RCP Sf =[ Q n ] 2 K' =0.463 Sf =[ 0.124440 ]2= 0.001783 [d 8/3(K')] ( 2.946667 ] Hf =L(Sf) Hf= HGL AT U.S.END= 1.2HV= 100YR WS IN CB= DESIGN FOR ONSITE CB PROP. WIDTH OF OPENING (W)(FT) CURB HEIGHT (IN) DEPTH OF DEPRESSION (IN) DEPTH OF FLOW AT OPENING (H)(FT) HEIGHT OF OPENING (h)(IN) Q100 TO OPENING (CFS) TC AT OPENING 5.00 H /h= 0.36 6.00 Q /L= 2.50 (P (PC 4.00 0.30 Q= 10.00 (Q /L) 10.30 511.96 VS HGL 510.84 OK TO TC) 10.30 4.12 FOOT WIDE OPENING (MIN) 2.50 USE W(MIN)= 5.00 OK HGL100 510.160 0.186 0.203 510.549 0.0892 510.638 0.203 510.841 I� � l� � � I� I� � � l� � I� I� ■� l� � � I� s TIME OF CONCENTRATION: INITIAL FLOW: Ti = k *(L ^3/h) ^.2 where: k = L, length of initial flow = h, elevation difference over initial flow = Ti = STREET CAPACITY: MADISON STREET CATCH BASIN STREET FLOW: Ts = L/V 0.39 where: 465 L, length of flow = 465 2 V, street velocity = 2.43 13.53 minutes Ts = 191.63 secs Q= 1.486 *A *R "2 /3 *S ^1/2 n where: A, X- sectional area of street = 8.5 sf Wetted perimeter = 34.5 R = 0.246 S, slope = 0.0050 ft/ft n, Mannings coefficient = 0.017 Q = 20.63 cfs VELOCITY. in Street: V= Q/A where: Q, capacity, cfs = 20.63 A, area, sf = 8.5 V = 2.43 fps 3.19 min. DESIGN Q1o: Q = C *I *A where: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 1.79 in /hr (10yr -From Plate D -4.1) A, drainage area = 0.81 AC (Drainage Map) Q = 1.19 cfs DESIGN Qioo: Q = C *I *A where: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 2.86 in /hr (100yr - From Plate D -4.1) A, drainage area = 0.81 AC (Drainage Map) Q = 1.90 cfs TIME OF CONCENTRATION: INITIAL FLOW: Ti = k *(L ^3/h) ^.2 where: k = L, length of initial flow = h, elevation difference over initial flow = Ti = STREET CAPACITY: CORE HOMES - ONSITE RUNOFF STREET FLOW: Ts = L/V 0.39 where: 500 L, length of flow = 430 . 4.5 V, street velocity = 2.72 12.02 minutes Ts = 157.82 secs Q= 1.486 *A *R ^2 /3 *S ^1/2 n where: A, X- sectional area of street = 12 sf Wetted perimeter = 41 R = 0.2927 S, slope = 0.0050 ft/ft n, Mannings coefficient = 0.017 Q = 32.70 cfs VELOCITY. in Street: V= Q/A where: Q, capacity, cfs = 32.70 A, area, sf = 12 V = 2.72 fps 2.63 min. DESIGN Qio: Q = C *I *A where: C, runoff coefficient = 0.82 (From Plate D -5.7) I, rainfall intensity = 1.79 in /hr (10yr - From Plate D -4.1) A, drainage area = 4.42 AC (Drainage Map) Q = 6.49 cfs DESIGN Qloo: Q= where: C, runoff coefficient = I, rainfall intensity = A, drainage area = Q= C *I *A 0.82 (From Plate D -5.7) 2.86 in /hr (100yr - From Plate D -4.1) 4.42 AC (Drainage Map) 10.37 cfs � m � � � m m � � � i � � � � � m m m v.• LA Lo m P. z�aaa as I 1 1 1 4I 1 SSC:St1Ve, : A. 5FE A..L }iS.. I i .9 1 L' 1 I 1 't 1 1 I 1 Em". •ul ywu 1'tla a7L b R Ln A1¢LL -- °ui —a•I- UnAwWwoW Swvlm Alert Cog: TOIL RIEE 1 -800 227 -2800 1•D �a 11•7 INIwf vow am GRAPMC SCALE IN THE CITY OF LA QUINTA. COUNTY OF RIVERSIDE. STATE OF CALIFORNIA TENTATIVE TRACT MAP NO. 33085 A SUBDIVISION OF A PORTION OF PARCEL 3 OF PARCEL MAP NO. 16457. FILED IN P.M.B. 100 /48. AND BEING A PORTION OF THE NORTHEAST QUARTER OF THE SOUTHEAST QUARTER (NE I /4 SEI /4) OF SECTION 4. TOWNSHIP 6 SOUTH. RANGE 7 EAST OF THE SAN BERNARDINO MERIDIAN, COUNTY OF RIVERSIDE. STATE OF CALIFORNIA COACHELLA VALLEY ENGINEERS. INC. SEPTEMBER. 2005 l r.NO.T 1•rA1 LY•• ���� a vru.valu+aa/ :L.rS ��// ��/ a aa..ya ru An •m. `PL IIImI �JY Iw1 >. ,ul�• inl R lA al[nF ��o I Bel a�I•L' �C•Y I•� sore 5 1 :S.•.r. I I � df�w � p\'I a •@ : - Ji w.a'7V�aw .tee 81111 h, bT ��yTp — :R �4 YI -�YT� .TI ... VrR �.0 - f 1a • a rU m J'. :. .� @� L1a�J i4 $3$313 _ LaI•rtwT 1fOJ' TIP. 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LI/ID f AA 01AAAr S .MOO( (STRICT 00100!.1 IL•LAr U&M BCN= Wn= THOMAS GUIDE COORDINATES AM LIATOL LIN mar am aw 0--7 TOPOGRAPHY saa swxr IOVaMM BY aooAL VUL& DANAM AC. NPlamt JmI BASIS OF BEARINGS /wy�n/r`)�an:�ai Axamw awma 111A>07 wp An � n N PJ16 f ILLY`~ al aR CMW O ArAMUC SaN Of asj= � ✓•a@1r � �1L� Lam• A EBB. art-. rrr. a ta. � r.• :�L-a tr1�Al i 1_ "u �I "IJE®rovA OVICINITY MAP T 'PRELIMINARY' NOT FOR CONSTF a nA arr or u OYML rxsmu A.P.N. 772.27M113 TENTATIVE TRACT MAP NCO. 33085 LL =/Ii• - 1 •f A M Ar f !art• 1� IN THE CITY OF LA QUINTA, COUNTY OF RIVERSIDE, STATE OF CALIFORNIA RETENTION BASIN CONTOURS TRACT MAP N0. 33085 IN THE NE1 /4 OF THE SE1 /4 OF SECTION 4, T.6S., R.7E. SBM RETENTION BASIN CAPACITY C 0' WATER DEPTH - 0 C.F TC 511.79 1' WATER DEPTH - J,504 C.F. \ 2' WATER DEPTH - 7,99J C. F. 3 WATER DEPTH 13, 584 C. F. \ \ 4 ' WATER DEPTH - 20,394 C.F. 5' WATER DEPTH - 28,541 C.F. AFL \ 1 FT FREEBOARD SS \ I I r°10 \ � I . s °s LOT 1 / o 1 FT _ FREEBOARD a'o `ro 0 10,366 S.F. L.S. /RET. TOP 511.10 WS 509.93 BOT 505.10 GRAPHIC SCALE 20 0 10 20 40 60 ( IN FEET ) 1 inch = 20 ft. OVERFLOW TO STREET BOT 505. 10 TOP 511. 10 04220 IN THE CITY OF LA QUINTA, CALIFORNIA CORE HOMES, LL-C:. TTM 33085 CVE TEL(760)360 -4200 FAX(760)360 -4204 Coachella Valley Engineers 77 -899 Wolf Road, Suite 102, Palm Desert, CA 92211 / Q?,pFESS /pHq\ K. R A. /Cc�lF�c Cn * NO. 35728 ,k� IXP. V1 1M5 \� of CP��F W 0 W A• DAVID K. RICE — RCE 35728 — EXPIRES 6 -30 -05 AVENUE 1 50 VISTA BONITA TRAIL CIz T.5S. T. 6S. W AVENUE 51 OLD ORCHARD LANE BETH CIRCLE 0 0 I AVENUE 1 52 1 AV -IEX VICINITY MAP N.T.S. CORE HOMES HYDROLOGY AND DRAINAGE REPORT CORE HOMES Un WO W June 23, 2006 HYDROLOGY AND DRAINAGE FACILITY DESIGN REPORT INDEX Cover Sheet Index Hydrology and Drainage Facility Design Report Location Map — Predevelopment Drainage Area Map — Post Development Soil Conservation Service Aerial Map Retention Basin Storage Summary Data Appendix 1. Soil Engineer Percolation Report 2. Storage Hydrograph Calculation Spread Sheets 3.. Retention Basin Design Procedure 4. CVE Design Calculations Deep Well Percolation 5. Offsite Drainage Topography Map 6. Madison Street Storm water Flows 7. Los Angeles County Road Department Flow Nomograph 8. NOAA 3, 6 and 24 Hr Storm Volume Precipitation Table ,9. Riverside County Hydrology Manual (RCAM) Excerpts: a )10 and 100 Year Storm Intensity Duration Table b) Rainfall Pattern Table c) Pervious Area Runoff Index Table d) Impervious Cover /Development Table e) Runoff Coefficient Curve f) Initial Sub -area Time Of Concentration Homograph 10. City of La Quinta Deep Well Percolation Chamber l �1 � I � I � I I I I I FINAL HYDROLOGY AND DRAINAGE REPORT TM 33085 JUNE 28, 2006 TRACT MAP 33085 HYDROLOGY REPORT INTRODUCTION AND PROJECT INFORMATION The project is located north of Avenue 52, west of Madison Street and south of Beth Circle. The project consists of a 4.76 Acre parcel being developed into 7 lots, each approximately 0.5 acres in size. HYDROLOGY The drainage area map utilized with this report is attached the attached Tentative Map 33085. The drainage area to be analyzed includes Beth Circle Street Drainage and the 50.00 feet of Madison Street adjacent to the project. The total drainage area is 4.76 acres. The storm volume of 1.79, 2.29, 2.77, and 3.79(4.5) inches for the duration of the 1 hour, 3 hour, 6 hour, and 24 hour/ 100 year storm frequency respectively, is for design of the retention basins. ' The storm volumes are obtained from the Point Precipitation Frequency Estimates from DOC /NOAA/National. Weather Service Office of Hydrologic ' Development, Hydro meteorological Design Studies Center, W /OHD13 at 1325 East -West Highway Silver Spring, MD 20910 -3283 The hydrologic soils group map for the Coachella area is included in the ' appendix of this report. The soil type is a sandy, silty, loamy Indio soil, I -S, and Gilman B Soil, common in this area. 1 � I � I � I I I I I 1 The soil classification for the site is type "B ", having high infiltration rates, antecedent moistening conditions rating of AMC II and low runoff potential when saturated. The percolation tests have been performed on the site by Landmark Engineering Geo Technical, LCI, Report No. LP05057. Tests result showed a percolation rate of 13.0 gals /hr /sf or 20.8 in /hr /sf. Per City of La Quinta standards, 2.0 inches per hour will be used. A City of La Quinta newly adopted "deep well percolation well system" will be installed in the retention basin. ( see attached detail in appendix). The site Runoff Index number of the hydrologic soil cover complex, for the pervious area (AMC II), is RC 56. This is for residential landscaping on Group B soils, with 50% impervious cover from RCHM plat D -5.5. The pond storage is based on the 100 year, 24 hour rainfall event. Attached are calculations detailing the capacity of the retention basins for the 3hr, 6hr and 24hr events. HYDRAULICS The runoff from the site will flow down the streets to a retention basin in the southeast corner of the site. Should the retention basin for the streets overflow, water will drain south and east towards Madison Street. iCoachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 2 of 7 JUNE 28, 2006 n MADISON OFFSITE STREET FLOWS City of La Quinta has requested an offsite analysis of the storm water collection capacity of Madison Street at the TM 33085 and the resulting impact on downstream flows. In particular, staff has requested an analysis of the intersection of 52nd Avenue and Madison Street. Reference to attached Plate A -1 , offsite USGS topographic map for the Madison Street Drainage Area. We can analyze the geography and topography elevations to conclude that at present all storm water and un- improved site drainage north of 50th street will drain to the east of Madison Street intersection and north of 50th Street. This condition has been field verified by visual site observation. South of 50th Street to the east of Madison Street, I have conducted a preliminary drainage analysis of the Polo Ground territory. This ground is self containing when analyzed for site runoff drainage. I have estimated that approximately 18 acres drains onto the Madison Street Drainage. I have disregarded the drain ditch on the easterly Madison Street right to way and concluded that all offsite drainage from the Polo Ground Territory will be carried by Madison Street final section of street improvement (ROW = 100.00 ft ). Westerly offsite drainage including the Van De Bos TM 30378 primarily drains to the west and is carried along by the foothill drainage pattern of the All American Canal. Coachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 3 of 7 JUNE 28, 2006 For design purposes of TM 30385, 1 have concluded that the Beth circle drainage collection street and the 50.00 feet of Madison adjacent to the tract will be stored in the "on site" retention basin. Offsite drainage area for Madison Street to the north of TM 33085 is (100 x 3200 = 320,000 SF ( 7.35 AC..) For future evaluation purpose as requested by City of La Quinta Engineering Staff, I will evaluate the drainage capacity and volumetric condition for Madison Street. See Appendix Section. CONCLUSION 1. ON SITE RETENTION BASIN STORES 25,725.6 CF OF STORAGE FOR THE 100 YEAR 24 HOUR STORM FOR PROJECT SITE TO CL MADISON STREET. 2. MADISON STREET FUTURE 100 FEET RIGHT OF WAY AS IMPROVED WILL CARRY THE 100 YEAR STORM FLOW IN THE STREET SECTION AT A DEPTH OF 0.50 FEET. 3. MADISON STREET UPSTREAM OFFSITE DRAINAGE WILL NOT OVERFLOW ABOVE THE ROW ELEVATION OF 513.00 DURING A 100 YEAR STORM. 4. MADISON STREET UPSTREAM OFFSITE DRAINAGE WILL FLOW TO THE INTERSECTION OF 52ND AND MADISON STREET AND FLOW EASTERLY ON THE NORTHERN RIGHT OF WAY OF 52ND AVENUE. Coachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 4 of 7 JUNE 28, 2006 .. ...... ... 3730 42'30" BM : 61:.--' ........ 7 a4 t C:) 8 L xt . ...... (::D igk.fte, FJ5 0 d. .�. ��• I ..� . . ....... .. . ............ Trailer Park j gi 0 aFE i Trailer :P-J' ;4� N 48 ft ............ UE LL-- A VE ell it Well.. .... ....... ii .......... W.11 r C) --GOl Z: ............. 0-1, . . U) ...... ...... .......... P T ...... C2 ❑ 33 VENUE LWell 49 .32 bp Water it It co n Q� it) 0 50 :.':• ' 1 n AVENUE. ' it -7-�� .50 ' z Well 0 In We I Q: bj tL tL -n 11 ...................... co ...... . co vl n............. C, It cn .. ............. It v) 000aa� it 11 It It Traile P a k, J�L 0 17 Well ... ........ AVENUL it —17 L P Pu!*n I .. .... % .. ... . . . . . . 1 )111 Q - -- — - -- - - - - - -- 7777 _ _..._.. _ 11N 1, 1' .. wyFNG t 3� 2. :�� r�• Ijl /�I�i)•i!�:{ f` �t �� ............ . . .', :�:•q�Y -'N... iT• ttu• :�.i:i::ir it�.I {!Igll•.I' (1'' �l �ia ii:. ':ii :i:a i isii•.Y: ar:a:•�i� :: 33" : oii' .............. l�.lfi!{�.e� °, :.•: •t 3CS ('• .a:.. •.io •Y•{'v`•1•• _ L! •••.•1a .i1�% :I, r1• �.a •i d)♦••:• raA'. ...+`! :• ('- �' �• .. �Y t. f :z 1 I F -- .'VW T t C t • Lf 0 a t t � ,..�'.` .fir, ,�. .•� ...� ..... ♦VE'N /� .. .- ..:...a.,� - �_....a.v i.-rM' _.: ^ -. .. S��i1: - eJ.yi!. <f ..i!aara.!:•e.r... - - � 1. %• f 3 ry'• 1 J • .,. 1 Pn1i•' a I i r ,a.a •. :: ••. % +dal: i► t•. <� a ..—. .... •. c'.1;(yG!n.a LMY•: 1 , I • ;• ij. # �: _ ......_... ill. r .... f projeevsUd y Reference: USGS Topographic Map La Quinta, CA Quadrangle Scale 1:25,000 LANDMARK, Project No.: LP05057 Topographic Map Site Coordinates Lat: 33.675N Long: 116.253W Paatq A -4• 1' .. wyFNG t 3� 1 I F -- .'VW T t C t • Lf 0 a t t � ,..�'.` .fir, ,�. .•� ...� ..... ♦VE'N /� .. .- ..:...a.,� - �_....a.v i.-rM' _.: ^ -. .. S��i1: - eJ.yi!. <f ..i!aara.!:•e.r... - - � 1. %• f 3 ry'• 1 J • .,. 1 Pn1i•' a I i r ,a.a •. :: ••. % +dal: i► t•. <� a ..—. .... •. c'.1;(yG!n.a LMY•: 1 , I • ;• ij. # �: _ ......_... ill. r .... f projeevsUd y Reference: USGS Topographic Map La Quinta, CA Quadrangle Scale 1:25,000 LANDMARK, Project No.: LP05057 Topographic Map Site Coordinates Lat: 33.675N Long: 116.253W Paatq A -4• A7 de LANDMARK • OBEMBf/SB.� Campan y Project No.: LP05057 USDA Soil Conservation Soil Service Man Plate A -3 APPENDIX Coachella Land — Storm Water Management Report ' Prepared by: Coachella Valley Engineers Page: 5 of 7 January 05 t&6-Enqineers and '/ 11 a DO&WEE/SSE Company 7810 N. 4th Strait ' I May 23, 2005 El Centro, ca 9 2_243 17601 370 -3000 (780) 337 -6900 fax t 77 -940 Wildcat Drive Mr. David Neale Palm Desert, C4 .92211 Core Homes, LLC (760) 360-0665 ' 470 S. Market Street (760) 360-0521 fax San Jose, CA 95113 ' I Geotechnical Investigation Tentative Tract No: 33085 4.4 -acre Property I La Quinta, California LCI Report No. LP05057 11 Dear Mr. Neale: This geotechnical report is provided for design and construction of the proposed single family residential development located on the southwest corner of Beth Circle and Madison Street, between Avenue 51 and Avenue 52 in La Quinta, California. Our geotechnical investigation was conducted in response to your request for our services. The enclosed report describes our soil engineering investigation and presents our professional opinions regarding geotechnical conditions at the site to be considered in the design and construction of the project. t� The findings of this study indicate the site is underlain by interbedded silty sands, sandy silts, and clayey sandy silts with near surface silty sands. The subsurface soils are very loose to medium dense ,I in nature. Groundwater was not encountered in the borings during the time of field exploration. Elevated sulfate and chloride levels were not encountered in the soil samples tested for this study. However, the soil is moderately corrosive to metal. We recommend a minimum of 2,500 psi concrete Type U Portland Cement with a maximum water /cement ratio of 0.60 (by weight) should be used for concrete placed in contact with native soils of this project. We did not encounter soil conditions that would preclude implementation of the proposed project provided the recommendations contained in this report are implemented in the design and ' construction of this project. Our findings, recommendations, and application options are related only through reading the full report, and are best evaluated with the active participation of the engineer. tof record who developed them. I r, It k 4 c Tentative Tract No-33085 — La Quinta, CA LCI Report No. LP05057 The collapse potential test indicated a slight risk of collapse upon inundation at the project site. Therefore, building foundations are not required to include provisions for mitigating the hydroconsolidation caused by soil saturation from landscape irrigation or broken utility lines. 3.8 Soil Infiltration Rate A total of two (2) infiltration tests were conducted on May 19, 2005 at the proposed location for the stormwater retention basin as shown on the Site and Exploration Plan (Plate A -2). The tests were performed using pipes inside 6 -inch diameter hand auger boreholes made to depths of approximately 3 feet below the existing ground surface, corresponding to the anticipated bottom depth of the stormwater retention basin. The pipes were presoaked and filled with water and successive readings of drop, in water levels were made for a total elapsed time of 360 minutes, until a stabilization drop was recorded. A soil infiltration rate of 13.0 gallons per hour per square foot of bottom area may be used for infiltration design. An oil/water separator should be installed at inlets to the stormwater retention basin to prevent sealing of the basin bottom with silt and oil residues. We recommend additional testing should be performed after the completion of rough grading operations, to verify the soil infiltration rate. Landmark Consultants, Inc. Page 9 ' CORE HOMES TM 33035 ' Retention Basin Design Procedure ' Coachella Valley Engineers Spread Table Program cve 04220 ' Following is an explanation of the calculation procedure of the Excel Spread Table program used by CVE to quickly and accurately size Retention Basins. 1) The Drainage Area map is developed from the Precise - grading plan. ' 2) Tributary areas displayed near the top of Table 2 are electronically measured from the Drainage Area map /grading plan. ' 3) The soil names and symbols for the site, listed near the top of Table 2, are copied from the US Soil Conservation Service Soil Survey Map. The corresponding Hydrologic Soil Group designations, (usually'A or B in the Coachella Valley), are determined from table ' 12 of the SCS Survey. 4) The design Percolation rate listed near the top of Table 2 is usually either 1/2 of the ' lowest test value in the Soils Report, or a lower rate dictated by the City. For large sites, the nearest test results may be averaged or interpolated for each particular basin location, with city approval. ' 5) The total rainfall volume for each design storm, entered at the top of Table 2, is excerpted from the Precipitation Frequency Estimate Table, Atlas 14, contained in the NOAA website, ' 6) The storm period was arbitrarily chosen as 15 minutes for the 3 and 6 -hour storms and 60 minutes for the 24 -hour storm to provide enough points to plot a smooth storage -vs. ' -time hydrograph curve. 7) The precipitation % data is copied from the RCFD Manual, plate E.5.9, for each storm period and is entered in column 2 of the data table on Table 2. ' 8) The storm intensity I for each storm period is automatically calculated by multiplying the storm volume of 7 above by the precipitation % in column 2 and listed in column 3 ' of Table 2. 9) The period runoff coefficient C listed in column 4 on Table 2, is computed from data ' taken from the RCFCD manual, plate D -5.1, 5.2, 5.3, or 5.4, for the appropriate Hydrologic Soil Group, A, B, C or D. 10) The period rainfall runoff rate Q listed in Column 5 of Table 2 is computed by multiplying tthe runoff and intensity data in columns 3 and 4 and the tributary area. 11) The period rainfall runoff inflow volume listed in column 6 on Table 2 is calculated by ' converting Q from cfs to cubic feet per storm period 12) Retention Basin contour areas listed in column 2 of the Retention Basin Storage table at the top of Table 1 are electronically measured and /or calculated at one -foot vertical intervals from the Drainage Area Map or the grading. plan. 13) The available storage area and volume data listed in columns 3, 4, & 5 of the Storage table are automatically computed from the contour area data. Pale 1 of 2 ' Last updated 09 -09 -05 ' CORE HOMES TM 33085 cve 04220 ' 14) The period percolation outflow volume for each storm period listed in column 8 on Table 2 is calculated from the percolation rate and the retention basin water surface tarea from column 8 of Table 1. 15) The period cumulative runoff inflow volume listed in column 7 on Table 2 is determined by subtracting the previous periods percolation outflow, listed in column 8, from the sum ' of the current period inflow listed in column 6, and the previous period cumulative inflow listed in column 7. ' 16) The period required retention volume listed in column 10 on Table 2 is the result of subtracting the current period percolation outflow, listed in column 8, from the current period cumulative inflow listed in column 7. ' 17) The time required to empty the basin after the end of the design storm, shown at the bottom of Table 1, is calculated by continuing the required retention volume ' computation after the end of the design . storm, with zero inflow but continuing percolation outflow, until the retention basin is empty. 18) The retention basin water depth listed in column 7 is the sum of the partial water depths ' from columns 2 to 6. The water depth for each storm period and vertical foot of basin, listed in columns 2 to 6 in Table 1, is calculated by comparing the required cumulative retention volume from column 10 on Table 2 to the available cumulative retention ' storage volume for each vertical foot of site retention basin storage, from column 5 of the Storage Table. The difference in the values is proportioned to calculate the depth of required storage for each period and vertical foot. ' 19) The surface area of the required storage for each period, listed in column 8 of Table 1 is calculated from the water depth listed in column 7 and the surface areas listed in tcolumns 2 and 3 of the storage Table. 20) The storage curve on Table 1 is the plot of the completed data from columns 1 and 10 of Table 2, and clearly shows relationship of storm duration to peak storage requirement. ' 21)' An Elevation Data Table is provided adjacent to the basin storage graph. This data lists the important elevations and shows the relationships between building floor, street TC, ' FL, and EP, ultimate outflow, maximum retention water surface, and basin bottom elevations. ' Page 2 of 2 Last updated 09 -09 -05 STORAGE HYDROGRAPH FOR 100 YEAR / 24 HR STORM RETENTION BASIN. SHEET 2 OF 2 PREPARED BY COACHELLA VALLEY ENGINEERS SUBJECT 124 HOUR STORM ADDENDUM ANALYSIS JOB # 04220 IT.M. 33085, W of Madison & S of Beth Circle DATE: 9/13/05 BY: DKR TRIB AREA 4.7600 ACRES PERC.RATE 2.00 IN /HR SOIL GROUP "B ", AMCII, R.I.= 32, R.C. =50 %, STORM VOLUME 4.50 IN /24HR 100 YEAR/ 24 HOUR PLATE E-5. PERIOD PRECIP INTENSITY IMPERV FLOW INFLOW OUTFLOW RETENTION 1 100 C Q VOL /Hr CUML VOL OTHER PERC /Hr OTHER REQD CUML VOL (1 Hr) % (IN /Hr) RC =50% (CFS) (CF) (CF) (CF) (CF) (CF) (CF) 0.477 1 1.2 0.054 0.123 441.3 441.3 0.0 593.0 0.0 0.0 2 1.3 1 0.059 0.478 0.133 479.7 479.7 0.0 630.0 0.0 0.0 3 1.8 0.081 0.486 0.188 675.1 675.1 0.0 667.0 0.0 8.1 4 2.1 0.095 0.491 0.221 795.2 803.3 0.0 704.0 0.0 99.3 5 2.8 0.126 0.502 0.301 1084.1 1183.4 0.0 741.0 0.0 442.4 6 2.9 0.131 0.504 0.313 1126.3 1568.7 0.0 778.0 0.0 790.7 7 3.8 0.171 0.518 0.422 1517.4 2308.2 0.0 815.0 0.0 1493.2 8 4.6 1 0.207 0.530 0.523 1881.6 3374.7 0.0 852.0 0.0 2522.7 9 6.3 0.284 0.557 0.752 2707.0 5229.8 0.0 903.0 0.0 4326.8 10 8.2 0.369 0.587 1.031 3712.7 8039.4 0.0 958.0 0.0 7081.4 11 7.0 0.315 0.568 0.852 3067.3 10148.8 0.0 1006.0 0.0 9142.8 12 7.3 0.329 0.573 0.896 3225.4 12368.1 0.0 1092.0 0.0 11276.1 13 10.8 0.486 0.628 1.453 5230.9 16507.0 0.0 1178.0 0.0 15329.0 14 11.4 1 0.513 0.638 1.557 5604.6 20933.6 0.0 1358.0 0.0 19575.6 15 10.4 1 0.468 0.622 1.385 4986.6 24562.2 0.0 1358.0 0.0 23204.2 16 8.5 0.383 0.592 1.078 3879.5 27083.6 0.0 1358.0 0.0 25725.6 17 1.4 0.063 0.480 0.144 518.2 26243.9 0.0 1358.0 0.0 24885.9 18 1.9 0.086 0.488 0.199 714.9 25600.8 0.0 1448.0 0.0 24152.8 19 1.3 0.059 0.478 0.133 479.7 24632.4 0.0 1448.0 0.0 23184.4 20 1.2 0.054 0.477 0.123 441.3 23625.7 0.0 1448.0 0.0 22177.7 21 1.1 0.050 0.475 0.112 403.2 22580.9 0.0 1358.0 0.0 21222.9. 22 1.0 0.045 0.474 0.101 365.3 21588.2 0.0 1358.0 0.0 20230.2 23 0.9 0.041 0.472 0.091 327.7 20557.9 0.0 1178.0 0.0 19379.9 24 0.8 0.036 1 0.471 1 0.081 290.3 1 19670.2 0.0 1178.0 0.0 18492.2 f� fllllll• � fllll� fi♦ flll• III fly flli• fli• � flllir � f� fi♦ � fll� SUBJECT 124 HOUR STORM ADDENDUM ANALYSIS JOB # 04220 IT.M. 33085, W of Madison & S of Beth Circle DATE: 9/13/05 RETENTION BASIN STORAGE AND DEPTH CALCULATIONS SHEET 1 OF 2 BY: DLC PERIOD WATER DEPTH WATER SURFACE D= 4' -5' D= 4' -5' D= 4' -5' D= V -2' D= 0' -1' DEPTH AREA ADJ.AREA ELEV. (HR) (FT) (FT) (FT) (FT) (FT) (FT) (SF) (SF) (FT) 1 0.000 0.000 0.000 0.000 0.128 0.13 3159.05 3159.05 505.23 2 0.000 0.000 0.000 0.000 0.139 0.14 3169.17 3169.17 505.24 INC 3 0.000 0.000 0.000 0.000 0.195 0.19 3220.72 3220.72 505.29 INC 4 0.000 0.000 0.000 0.000 0.231 0.23 3254.55 3254.55 505.33 INC 5 0.000 0.000 0.000 0.000 0.340 0.34 3354.82 3354.82 505.44 INC 6 0.000 0.000 0.000 0.000 0.449 0.45 3456.47 3456.47 505.55 INC 7 0.000 0.000 0.000 0.000 0.660 0.66 3651.54 3651.54 505.76 INC 8 0.000 0.000 0.000 0.000 0.963 0.96 3932.90 3932.90 506.06 INC 9 0.000 0.000 0.000 0.386 0.000 1.39 5458.54 5458.54 506.49 INC 10 0.000 0.000 0.008 0.000 0.000 2.01 5020.63 5020.63 507.11 INC 11 0.000 0.000 0.386 0.000 0.000 2.39 5458.27 5458.27 507.49 INC 12 0.000 0.000 0.783 0.000 0.000 2.78 5918.74 5918.74 507.88 INC 13 0.000 0.429 0.000 0.000 0.000 3.43 6719.55 6719.55 508.53 INC 14 0.066 0.000 0.000 0.000 0.000 4.07 7541.68 7541.68 509.17 INC 15 0.512 0.000 0.000 0.000 0.000 4.51 8163.82 8163.82 509.61 INC 16 0.821 0.000 0.000 0.000 0.000 4.83 7062.00 7062.00 509.93 PEAK 17 0.718 0.000 0.000 0.000 0.000 4.72 8452.15 8452.15 509.82 DEC 18 0.639 0.000 0.000 0.000 0.000 4.64 8341.89 8341.89 509.74 DEC 19 0.520 0.000 0.000 0.000 0.000 4.52 8175.86 8175.86 509.62 DEC 20 0.397 0.000 0.000 0.000 0.000 4.40 8003.26 8003.26 509.50 DEC 21 0.269 0.000 0.000 0.000 0.000 4.27 7824.12 7824.12 509.37 DEC 22 0.147 0.000 0.000 0.000 0.000 4.15 7653.92 7653.92 509.25 DEC 23 0.020 0.000 0.000 0.000 0.000 4.02 7477.27 7477.27 509.12 DEC 24 0.000 0.894 0.000 0.000 0.000 3.89 7313.17 7313.17 508.99 #REF! STORAGE HYDROGRAPH FOR 100 YEAR / 6 HR STORM RETENTION BASIN. SHEET 2 OF 2 PREPARED BY COACHELLA VALLEY ENGINEERS SUBJECT 6Hr /100Yr -Core Homes - La Quinta JOB # 04220 IT.M. 33085, W of Madison & S of Beth Circle - La Quinta DATE: 9/13/05 BY: DKR TRIB AREA 4.7600 ACRES PERC.RATE 2.00 IN /HR ( 0.5 IN/15 Min) SOIL GROUP "B ", AMCII, R.I.= 56, R.C. =50% STORM VOLUME 2.77 IN /6HR 100 YEARF6 HOUR P -5. PERIOD PRECIP INTENSITY IMPERV FLOW INFLOW OUTFLOW RETENTION 1 100 C Q VOL /15 Min CUML VOL OTHER PERC /15Min OTHER REQD CUML VOL (15min) % (IN /15min) RC =50% (CFS) (CF) (CF) (CF) (CF) (CF) (CF) 1 1.7 0.047 0.464 0.104 93.6 93.6 0.0 593.0 0.0 0.0 2 1.9 0.053 0.466 0.117 105.0 105.0 0.0 630.0 0.0 0.0 3 2.1 0.058 0.467 0.129 116.5 116.5 0.0 667.0 0.0 0.0 4 2.2 0.061 0.468 0.136 122.3 122.3 0.0 704.0 0.0 0.0 5 2.4 0.066 0.470 0.149 133.8 133.8 0.0 741.0 0.0 0.0 6 2.4 0.066 0.470 0.149 133.8 133.8 0.0 778.0 0.0 0.0 7 2.4 0.066 0.470 0.149 133.8 133.8 0.0 815.0 0.0 0.0 8 2.5 0.069 0.471 0.155 139.7 139.7 0.0 852.0 0.0 0.0 9 2.6 0.072 0.472 0.162 145.5 145.5 0.0 903.0 0.0 0.0 10 2.7 0.075 0.472 0.168 151.4 151.4 0.0 958.0 0.0 0.0 11 2.8 0.078 0.473 0.175 157.3 157.3 0.0 1006.0 0.0 0.0 12 3.0 0.083 0.475 0.188 169.1 169.1 0.0 1092.0 0.0 0.0 13 3.2 0.089 0.477 0.201 181.0 181.0 0.0 1178.0 0.0 0.0 14 3.6 0.100 0.480 0.228' 205.0 205.0 0.0 1358.0 0.0 0.0 15 4.3 0.119 0.486 0.275 247.9 247.9 0.0 1358.0 0.0 0.0 16 4.7 0.130 0.489 0.303 272.8 272.8 0.0 1358.0 0.0 0.0 17 5.4 0.150 0.495 0.352 317.1 317.1 0.0 1358.0 0.0 0.0 18 6.2 0.172 0.502 0.410 369.0 369.0 0.0 1358.0 0.0 0.0 19 6.9 0.191 0.507 0.462 415.4 415.4 0.0 1448.0 0.0 0.0 20 7.5 0.208 0.512 0.507 456.0 456.0 0.0 1448.0 0.0 0.0 21 10.6 0.294 0.538 0.752 676.8 676.8 0.0 1448.0 0.0 0.0 22 14.5 0.402 0.570 1.091 981.6 981.6 0.0 1358.0 0.0 0.0. 23 3.4 0.094 0.478 0.214 193.0 193.0 0.0 1178.0 0.0 0.0 24 1.0 0.028 0.458 0.060 54.4 54.4 0.0 1178.0 0.0 0.0 -■- ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ SUBJECT 6Hr /100Yr -Core Homes - La Quinta JOB # 04220 T.M. 33085, W of Madison & S of Beth Circle - La Quinta SHEET 1 OF 2 DATE: 9/13/05 BY: DKR RETENTION BASIN STORAGE AND DEPTH CALCULATIONS PERIOD WATER . ,r 4 y -. � • ' f,}�rw5r .�. -tit; - l tm D= 0' -1' DEPTH AREA ADJ.AREA ELEV. (15 Min) (FT) (FT) (FT) (FT) (FT) (FT) (SF) (SF) (FT) 1 0.000 0.000 0.000 0.000 0.027 C■■■:■■■ 3065.10 3065.10 505.13 2 0.000 0.000 0.000 0.000 0.030 0.03 3068.17 3068.17 505.13 INC 3 0.000 0.000 0.000 0.000 0.033 0.03 3071.26 3071.26 505.13 INC 4 0.000 0.000 0.000 0.000 0.035 0.03 ■■■ 3072.82 505.13 INC 5 0.000 Oil:■ 0.000 0.000 0.038 0.04 3075.94 3075.94 505.14 INC 6 0.000 0.000 0.000 0.000 0.038 0.04 3075.94 3075.94 505.14 FALSE 7 0.000 0.000 0.000 0.000 0.038 0.04 3075.94 3075.94 505.14 FALSE 8 0.000 0.000 0.000 0.000 0.040 0.04 3077.51 3077.51 505.14 INC 9 0.000 0.000 0.000 0.000 0.041 0.04 3079.08 3079.08 505.14 INC 10 0.000 0.000 0.000 0.000 0.043 0.04 3080.66 3080.66 505.14 INC 11 0.000 0.000 0.000 0.000 0.045 0.04 3082.25 3082.25 505.14 INC 12 0.000 0.000 0.000 0.000 0.048 ■■■■■■■■■■■ 3085.44 3085.44 505.15 INC 13 0.000 0.000 0.000 0.000 0.051 0.05 3088.64 ■■■■ 505.15 INC 14 0.000 0.000 0.000 0.000 0.058 0.06 3095.12 3095.12 505.16 INC 15 0.000 0.000 0.000 0.000 0.070 0.07 3106.67 3106.67 505.17 INC 16 0.000 0.000 0.000 0.000 0.077 0.08 3113.38 3113.38 505.18 INC 17 0.000 0.000 0.000 0.000 0.090 0.09 3125.34 3125.34 505.19 INC 18 0.000 0.000 0.000 0.000 0.105 0.10 3139.32 3139.32 z.. INC 19 0.000 0.000 PERIOD WATER DEPTH WATER SURFACE D= 4' -5' D= 3'4' D= 2' -3' D= 1' -2' D= 0' -1' DEPTH AREA ADJ.AREA ELEV. (15 Min) (FT) (FT) (FT) (FT) (FT) (FT) (SF) (SF) (FT) 1 0.000 0.000 0.000 0.000 0.027 0.03 3065.10 3065.10 505.13 2 0.000 0.000 0.000 0.000 0.030 0.03 3068.17 3068.17 505.13 INC 3 0.000 0.000 0.000 0.000 0.033 0.03 3071.26 3071.26 505.13 INC 4 0.000 0.000 0.000 0.000 0.035 0.03 3072.82 3072.82 505.13 INC 5 0.000 0.000 0.000 0.000 0.038 0.04 3075.94 3075.94 505.14 INC 6 0.000 0.000 0.000 0.000 0.038 0.04 3075.94 3075.94 505.14 FALSE 7 0.000 0.000 0.000 0.000 0.038 0.04 3075.94 3075.94 505.14 FALSE 8 0.000 0.000 0.000 0.000 0.040 0.04 3077.51 3077.51 505.14 INC 9 0.000 0.000 0.000 0.000 0.041 0.04 3079.08 3079.08 505.14 INC 10 0.000 0.000 0.000 0.000 0.043 0.04 3080.66 3080.66 505.14 INC 11 0.000 0.000 0.000 0.000 0.045 0.04 3082.25 3082.25 505.14 INC 12 0.000 0.000 0.000 0.000 0.048 0.05 3085.44 3085.44 505.15 INC 13 0.000 0.000 0.000 0.000 0.051 0.05 3088.64 3088.64 505.15 INC 14 0.000 0.000 0.000 0.000 0.058 0.06 3095.12 3095.12 505.16 INC 15 0.000 0.000 0.000 0.000 0.070 0.07 3106.67 3106.67 505.17 INC 16 0.000 0.000 0.000 0.000 0.077 0.08 3113.38 3113.38 505.18 INC 17 0.000 0.000 0.000 0.000 0.090 0.09 3125.34 3125.34 505.19 INC 18 0.000 0.000 0.000 0.000 0.105 0.10 3139.32 3139.32 505.20 INC 19 0.000 0.000 0.000 0.000 0.118 0.12 3151.83 3151.83 505.22 INC 20 0.000 0.000 0.000 0.000 0.130 0.13 3162.76 3162.76 505.23 INC 21 0.000 0.000 0.000 0.000 0.192 0.19 3222.30 3222.30 505.29 INC 22 0.000 0.000 0.000 0.000 0.279 0.28 3304.45 3304.45 505.38 PEAK 23 0.000 0.000 0.000 0.000 0.055 0.05 3091.87 3091.87 505.15 DEC 24 0.000 0.000 7000 0.000 0.015 0.02 3054.52 3054.52 505.12 #REF! �� f' f� fi>• � � f� � � � � � � f� � � i� � iii• STORAGE HYDROGRAPH FOR 100 YEAR / 3 HR STORM RETENTION BASIN. PREPARED BY COACHELLA VALLEY ENGINEERS SUBJECT 24Hr /100Yr -Core Homes - La Quinta JOB # 04220 IStreet Drainage Pond 3:1 Sideslope DATE: 9/13/05 RETENTION BY: DKR 1 100 TRIB AREA= Q 4.7200 ACRES CUML VOL PERC.RATE PERC /15Min 2.00 IN /HR (0..5 IN/15 Min STORM VOLUME 2.29 IN /3HR SHEET 2 OF 2 SOIL GROUP "B ", AMCII, R.I.= 56, R.C. =50% PERIOD PRECIP INTENSITY IMPERV FLOW INFLOW OUTFLOW RETENTION 1 100 C Q VOL /15 Min CUML VOL OTHER PERC /15Min OTHER REQD CUML VOL (15min) % (IN /15min) RC =50% (CFS) (CF) (CF) (CF) (CF) (CF) (CF) 0.455 1 3.7 0.085 0.182 163.8 163.8 0.0 593.0 0.0 0.0 2 4.8 0.110 0.457 0.237 213.2 213.2 0.0 613.0 0.0 0.0 3 5.1 0.117 0.457 0.252 226.7 226.7 0.0 633.0 0.0 0.0 4 4.9 0.112 0.457 0.242 217.7 217.7 0.0 653.0 0.0 0.0 5 6.6 0.151 0.459 0.327 294.7 294.7 0.0 672.0 0.0 0.0 6 7.3 0.167 0.460 0.363 326.7 326.7 0.0 691.0 0.0 0.0 7 8.4 0.192 0.462 0.419 377.1 377.1 0.0 710.0 0.0 0.0 8 9.0 0.206 0.462 0.450 404.8 404.8 0.0 730.0 0.0 0.0 9 12.3 0.282 0.467 0.621 558.7 558.7 0.0 750.0 0.0 0.0 10 17.6 0.403 0.474 0.902 811.9 811.9 0.0 760.0 0.0 51.9 11 16.1 0.369 0.472 0.822 739.4 791.3 0.0 780.0 0.0 11.3 12 4.2 0.096 0.456 0.207 186.2 197.5 0.0 800.0 0.0 0.0 REF: 24Hr /100Yr -Core Homes - La Quinta JOB # 04220 Street Drainage Pond 3:1 Sideslope SHEET 1 OF 2 DATE: 9/13/05 BY: DKR RETENTION BASIN STORAGE AND DEPTH CALCULATIONS PERIOD WATER DEPTH WATER SURFACE D= 4' -5' D= 3'-4' D= 2' -3' D= V -2' D= 0' -1' DEPTH AREA ADJ.AREA ELEV. (15 Min) (FT) (FT) (FT) (FT) (FT) (FT) (SF) (SF) (FT) 1 0.00 0.00 0.00 0.00 0.05 0.05 3084.15 3084.15 505.15 2 0.00 0.00 0.00 0.00 0.06 0.06 3097.46 3097.46 505.16 INC 3 0.00 0.00 0.00 0.00 0.06 0.06 3101.11 3101.11 505.16 PEAK 4 0.00 0.00 0.00 0.00 0.06 0.06 3098.68 3098.68 505.16 DEC 5 0.00 0.00 0.00 0.00 0.08 0.08 3119.44 3119.44 505.18 INC 6 0.00 0.00 0.00 0.00 0.09 0.09 3128.05 3128.05 505.19 INC 7 0.00 0.00 0.00 0.00 0.11 0.11 3141.65 3141.65 505.21 INC 8 0.00 0.00 0.00 0.00 0.12 0.12 3149.11 3149.11 505.22 INC 9 0.00 0.00 0.00 0.00 0.16 0.16 3190.58 3190.58 505.26 INC 10 0.00 0.00 0.00 0.00 0.23 0.23 3258.82 3258.82 505.33 PEAK 11 0.00 0.00 0.00 0.00 0.23 0.23 3253.28 3253.28 505.33 DEC 12 0.00 0.00 0.00 0.00 0.06 0.06 3093.23 3093.23 505.16 t CORE HOMES DRAINAGE RETENTION PERCOLATION CRITERIA. • ..•REFERENCE LCI REPORT LP 05057...PAGE 9 SOILS TESTING EVALUATION FROM THEE LANDMARX ENGINEERING JREPORT.INDICATE 7-ffA7 7WE PERCOLATION 2ATE" IS 13.0 GALLONS PER -HOUR PER SQUA2E FOOT ........EpUATES 7-0 1.73 CUBIC FEET PER �60UR...20.8 INGfES PER HOUR... MEREFORE... . MORE TVAN EXCEEDS ME MAXIMUM ALLOWABLE FOR CITY OF LAQUINTA... DK..060605 i OFFSITE DRAINAGE TOPOGRAPHY -z I • . f it i ot ' i AG . co • 6. ••, i - 1 e Coachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 6 of 7 January 05 r �r MADISON STREET STORMFLOWS _. EU I Oti t • If uj - u . Y .�\ O........._...__= fl co ................. ii 000 W , II II 11 - OS II fi = =il •.II (< '� W `� ;..:, II o 113nN3,1 /���I y£ _ II II p II III n \ ` Q• II •■ • IlO Q ;• if � J , all J CD (�� o � �a e 416 O (j to } M .�� W a I � it O Q O O C H J 1 II 6f' IIaM�tl�� 3nN3 0 y II Rl if n _ / II Ih ■ 9 r ' - -- II •, II II yZ p II q o 3n rr ` 9 r --� I 111Q Coachella Land — Storm Water Management Report Prepared by: Coachella Valley Engineers Page: 7 of 7 January 05 t; OF CALIFORNIA 10-31852 VD 43 OF MAPS, RIVERSIDE COUNTY RECC . R 7 E., S.B.M. t 4) {yj10.11 J t �5g8.�s �� Comm''. MClly Council s 23' i ❑ Community D6v. Ini06ls ' C' ,A 4 ' / 506.57 Case kPliS.a ? 49.50 `�... 50 !l ' t hibll 11 r,Wim Conditions, i j p i 08.331 I .94 (I.il 1 .305.17 'Sof 4 2 509.24 I 10. ! 1 �O'.. 8.4 j• t I ` 11 .505.19 .89 50 94 i .505.2 i p 50. 72' I: c 504.81 LL .5c 343J I .5-3.7 0 0 96 504.79 3 ' Z I PAR�� 1, ,. P�{r Jw .1 N t P.l�il. 7127 ,5 l .50g.Is .504.58 .567. `• blb. I 30 5 Av 02 8.72Li . ND b7.63 504.53 a f ` .S Is.. LOW ! _ 144 f "C F .64 a �r A 7 I .SD9.3� i I 07.21 .504.90 .°.09.1 5.72 LC 01'T 4 polo I OO A �/ -- 1_\ `08.1 ASPM . ' 509.44 . .. ' ... ......: /� 507.53 - ,:4..' •\ .' .508.23 � . ._- � u 1 ,.�i.t a i,1 � 1 I � •" M * 06:38 I ��� .�:i. 597.59 �i 1 c 1 •mil �R��v J �\� ✓. 7✓�J �f 7 tv 1. Amo9` ` I.B. a051141---o22 6.27 :11 OFFSITE MADISON STREET 100 YEAR STORM FLOWS ' CORE HOMES TM 33085 REGIONAL DRAINAGE ANALYSIS ' CITY LA QUINTA. 20 YEAR STORM CRITERIA MONROE AVENUE OFSITE FLOS iOFFSITE DRAINAGE AREA 18 ACRES + MADISON STREET ROW =,7.35 ACRES ... ' AGRICULTURAL URBAN RUNOF COEFFICIENT= 0.20 10 YEAR STORM RIVFCD PLATE D -4.5 RATIONAL ANALYSIS Q =CIA I = 4.52 X 1.1 /1.68 = 2.44 IN /HR REF... NWS NOAA ATLAS 14..FREQUENCY DATA BASE ATTACHED HEREWITH.. Q20 = 0.20 X 2.44 IN /HRX 25.35AC) = 12.37 CFS ...............Q100 = 0.20 X 4.52 X 2535AC = 22.92 CFS NOTE: ANALYSIS ASSUMES THAT OFFSITE RUNOFF WILL NOT BE INTERCEPTED AND COLLECTED BY THE VAN DE BOS PROJECT .....LA QUINTA POLO PARTNERS .... TM 30378 OVERALL STREET SLOPE FROM 51ST STREET ( VISTA BONITA TRAIL )TO 52ND STREET NORTH CL ELEVATION IS EL 516.00 REF: TM 30378 SOUTH CL ELEVATION IS EL 509.30 REF: TM 31572 ' DISTANCE CL VISTA BONITA TRAIL TO CL 52ND AVENUE LF ...2640.00 OVER ALL SLOPE-6.70 FEET DIVIDED BY 2650.0 = 00.25% REF: LACK STREET FLOW NOMOGRAPH D -08... FOR S = 0.25% D = 0.67FT tA = 7.4 SF Q = 29.0 CFS ' EQUATES TO THE EQUIVALENT OF A 29.0 1 8.78 = 3.30 RCFCD PLATE D ( -4.5 ) EQUATES TO WELL OVER A 200 YEAR EQUIVALENT STORM.. DEPTH OF 20 YEAR FLOW IN MADISON STREET ADJACENT TO THE TM 33085 CURB IS 0.40 FEET.. THEREFORE THE 20 YEAR STORM WILL BE CONTAINED WITHIN THE MADISON STREET SECTION AND NO OVERFLOW INTO TM 33085......D = 0.40 FEET DEPTH OF FLOW FOR THE 100 YEAR FLOW IN MADISON STREET ADJACENT TO TM 33085 IS 0.60 FT THEREFORE THE 100 YEAR STORM WILL BE CONTAINED WITHIN THE MADISON STREET SECTION AND NO OVERFLOW INTO TM 33085....D = 0.60 FEET TM31582 AS APPROVED BYLA QUINTA TOWN COUNCIL ON AUGUST 7, 2005 DOES NOT INTAKE ANY MADISON STREET FLOW THERFORE ALL WILL PND AT THE INTERSECTION OF 52ND AVENUE AND MADISON STREET.... VOLUME OF THE PONDED INTERSECTION AT 52ND AVENUE IS APPROXIMATELY 600 FEET LONG EXTENDING UP MADISON STREET AND AREA VOLUME OF 1.0 FT DEEP BY 33 FT WIDE AT 2 % CROSS SLOPE.. A = 16.5SF X 600 = 9900 CF OF CORNER STORAGE AT THE NORTHWEST CORNER OF 52ND AND MADISON... 52ND AVENUE SLOPE NEGATIVE TO THE EAST THEREFORE 100 YEAR FLOW WILL FLOW EAT FROM THE NORTH EAST QUADRANT OF MADISON AND 52ND AVENUE CORE HOMES TM 33085 REGIONAL DRAINAGE ANALYSIS CITY LA QUINTA..10 YEAR STORM CRITERIA MONROE AVENUE OFSITE FLOS OFFSITE DRAINAGE AREA ... 18 ACRES AGRICULTURAL URBAN RUNOF COEFFICIENT = 0.20 10 YEAR STORM RIVFCD PLATE PLATE D -4.5 1= 4.76X1.1/1.6= 2.82IN/HR Q = 0.20 X 2.82 X 18 = 10.38 CFS NOTE 90% OFFSITE RUNOFF WILL BE INTERCEPTED AND COLLECTED BY THE VAN DE BOS PROJECT LA QUINTA POLO PARTNERS TM 30378 n v Page G -20 a(ds) SC%) 300 Q(cfs) 10.0 A(ft.) D(fQ 90 200 300 12.9 0.83 8.0 ` 200 200 12.5 7.0- 1 2.2 g82 I :e1. 0.7$ 1 6.0 ` 100 100 .99 0.72 5,0-- 7.4 0.67 _ 0.65 4.0 100 50 _ 90 50 30 s- -0.60 80 40 3.0 70 20 4.5 0.55 EXAMPLE (Sao Dashed Line) 60- 30 2-0 Ghow - 0. 82 cfs 50 20 10 3.6 -0.50 S. 10.0% .671Ds-0.81 40 Find D • 0.60 ft. A - 5.7 ftt 2.7 0.45 K) 1.0 0.90 0 2.0 0.40 Q80 5 Q7b 4 0.60 Q `o0 3 1.3 0.35 0.50 Q40 D. 1= =0.83 2 0.30 0"o 0.85 0.30 1.0 Q(cf s) 0.20 Riw S0, 2.0 0.49 0.25 8' 2' 31.67' 8.33' 1.0 0.10 0.09 - - 0.25 -0.20 Q08 0 o t- _ �. p011. Z " o.a Q07 - ✓ 0.103D =0.17 0.06 0.10 0.17 .17 Q05 0.17 1-01-0.67 0.13 -0.15 0.099- �- NOTE THE 0 DETERMINED FROM THIS CHART 0.059 0.10 IS FOR ONE HALF OF STREET. LOS ANGELES .COUNTY ROAD DEPARTMENT STREET FLAW REFERENCE SHEET MAJOR HWY. -Chart 5 of 5 D -08 G L?uuu 11 1'i GLjUc;jj%.;y oco POINT PRECIPITATION FREQUENCY ESTIMATES NOAA Link FROM NOAA ATLAS 14 toLink t o t California 33.68 N 116.25 W 68 feet from "Precipitation- Frequency Atlas of the United States" NOAA Atlas 14, Volume 1, Version 3 G.M. Bonnin, D. Todd, B. Lin, T. Parzybok, M.Yekta, and D. Riley NOAA, National Weather Service, Silver Spring, Maryland, 2003 Extracted: Thu Jun 16 2005 urJ Text version of :table ' e precipitation frequency estimates are based an a partial duration series. ARI is the Average Recurrence Interval. - - These refer to the documentation for more information. NOTE: Formatting forces estimates near zero to appear as zero. xx pf2_Jun162005153246.png ❑x pf Jun162005153246.png Confidence Limits - * Upper bound of the 90% confidence interval Precipitation Frequency Estimates (inches) ARI ** 5 10 15 30 6120 3 6 12 24 MS 4 7 10 20 30 45 60 n min min min min [hr][hr][hr] hr day day day day day day day 10.15 0.23 0.29 0.39 0.48 0.63 0.73 0.97 1.19 1.26 1.39 1.52 1.62 1.74 1.84 2.02 2.32 2.49 0.24 gfl 0.46 0.62 0.76 FO-981 1.11 1.47 1.77 1.93 2.15 2.35 2.49 2.69 2.85 3.14 3.59 3.89 10 0.32 0.49 0.60 0.81 F _611 1.27 E4fl 1.86 E2fl 2.44 Efl 3.02 3.17 3.44 3.65 3.99 4.55 4.95 25 0.45 0.68 0.84 1.14 1.41 1.71 E]Eifl 2.84 3.20 3.71 4.02 4.17 4.54 4.79 5.21 5.88 6.41 50 0.56 0.86 1.06 1.43 1.77 2.12 2.31 2.87 3.34 3.83 4.51 4.86 5.02 5.47 5.73 6.21 6.95 7.60 100 0.70 1.06 1.32 1.77 2.20 Efl 2.78 3.40 3.89 4.52 5.41 5.83 5.99 6.47 6.73 7.32 8.10 8.88 200 0.86 1.31 I Efl Efl EE 3.12 E3fl 3.96 4.48 5.28 6.44 6.90 7.04 7.64 7.87 8.52 9.36 10.25 500 1.12 1.70 2E 2.84 Efl 3.97 4.18 4.84 F53-3]F6 .41 8.04 8.56 8.62 9.33 9.53 10.23 11.16 12.20 1000 1.36 2.07 2.57 3.46 4.28 4.73 4.92 5.58 6.06 7.34 9.39 9.97 10.05 10.79 10.96 11.68 12.62 13.81 ' The uDaer bound of the confidence interval at 90 %confidence level is the value which 5 %nf the simulated nuantilp vahipe fnr a nivan front ionry nro nroafor rtinn "These precipitation frequency estimates are based on a partial duration series. ARI is the Average Recurrence Interval. Please refer to the documentation for more information. NOTE: Formatting prevents estimates near zero to appear as zero. file: //P:\2004 \04220\Reports \050504 Hydroloay\Precipitation Frequency Data Server 0422... 8/31/2005 rrecipttatiUn rrequency 1Jata server rage of 3 * Lower bound of the 90% confidence interval 'Precipitation Frequency Estimates (inches) ARI 5 1� 30 60 Z ]] - 3 6 12 24 N 4 W 10 20 30 45 Z Fmin�flm ** 0000a000 (years) min m mtn hr hr hr da da da da da 0.10 0.15 0.19 0.25 0.31 0.42 0.49 0.65 0.80 0.91 1.03 1.12 1.21 1.29 1.38 1.53 1.73 1.86 0.16 0.24 0.30 0.40 0.50 0.66 0.7fl 0.98 Efl EE 1.59 1.72 1.85 2.00 2.14 2.38 2.67 2.89 ' 10 0.21 0.32 0.39 0.53 0.66 0.85 0.96 1.23 1.47 1.75 2.04 2.21 2.36 2.56 2.71 3.00 3.38 3.66 25 E2fl 0.44 E]ff 0.90 1.15 1.27 1.58 1.87 2.27 2.71 2.91 3.08 3.34 3.52 3.90 4.34 4.73 50 0.36 0.54 0.67 0.91 1.12 1.39 1.52 1.87 2.19 2.68 3.24 3.49 3.65 3.97 4.18 4.61 5.10 5.55 ' 100 0.43 0.66 0.82 1.10 1.36 1.66 1.80 2.18 2.50 3.12 3.83 4.10 4.30 4.64 4.87 5.36 5.90 6.42 200 0.52 0.79 0.98 1.32 1.63 FE 2.10 E4fl 2.84 3.58 4.48 4.76 4.93 5.37 5.59 6.12 6.71 7.30 500 0.65 0.99 1.23 1.66 2.05 2.41 2.53 2.94 3.29 4.24 5.42 5.73 5.85 6.40 6.58 7.19 7.83 8:51 1000 0.76 1.16 1.44 1.94 2.40 2.77 2.39 3.30 3.65 4.76 6.18 6.52 6.62 7.24 7.39 8.04 8.67 9.49 The lower bound of the confidence interval at 90 % con fdence level is the value which 5% of the simulated quantile values for a given frequency are less than. ' "These precipitation frequency estimates are based on a partial duration maxima series. ARI is the Average Recurrence Interval. Please refer to the documentation for more information. NOTE: Formatting prevents estimates near zero to appear as zero. Maps - aoverview map These maps were produced using a direct map request from the U.S. Census Bureau Maooina and Cartmraohic Resources ' Tiger Mao Server. ❑x detailed map Please read disclnhner jor more information. ' map legend Other Maps/Photographs - i View USGS digital ortho hp oto quadrangle (DOQ) covering this location from TerraServer; USGS Aerial Photograph ' may also be available from this site. A DOQ is a computer - generated image of an aerial photograph in which image displacement caused by terrain relief and camera tilts has been removed. It combines the image characteristics of a photograph with the geometric qualities of a map. Visit the USGS for more information. 1 Watershed /Stream Flow Information - ' Find the Watershed for this location using the U.S. Environmental Protection Agency's site. ' Climate Data Sources - Precipitation frequency results are based on data from a variety of sources, but largely NCDC The following links provide t general information about observing sites in the area, regardless of if their data was used in this study. For detailed information about the stations used in this study, please refer to our documentation. ' Using the National Climatic Data Center's (NCDC) station search engine, locate other'climate stations within: r file: //P: \2004 \04220 \Renorts \050504 Hvdrnlncry \PrPr.initation Freauencv Data Server 0422.. R /i1 / ?f105 rreclp>.Uduu11 rrequency 1)ata server rage s of 3 J , +/ -30 minutes OR +/ -1 degree of this location (33.68/- 116.25). Digital ASCII data can be obtained directly from NCDC. Find Natural Resources Conservation Service (NRCSI SNOTEL (SNOwpack TELemetry) stations by visiting the Western Regional Climate Center's state - specific SNOTEL station n1apss. Hydrometeorological Design Studies Center DOC/NOAA/National Weather Service 1325 East -West Highway Silver Spring, MD 20910 (301) 713 -1669 Questions ?: 1• D— SC.Oucstions!a ;noaa.eov Disclaimer file: //P:\2004 \04220\Reports \050504 Hvdrolol?v \Preciuitation Frequencv Data Server 0422... 8/31/2005 c rJG' `t Om ��A C _V1 ;ps A .—T I - 0P. f Vs , If ous d P.1,I ;7 'Pay '911 oi. c rJG' `t Om ��A C _V1 ;ps A .—T I - 0P. f Vs , If ous d P.1,I ;7 0, :eg WEIN Lv Moil up 11111c. MIN 4Rg— w—w-g"t RIVERSIDE COUNTY FLOOD CONTROL A N 0 WATER CONSERVATION DISTqIC T. 100—YEAR—.6— HOUR PRECIPITATION '407 R4 0, :eg WEIN Lv Moil up 11111c. MIN 4Rg— w—w-g"t RIVERSIDE COUNTY FLOOD CONTROL A N 0 WATER CONSERVATION DISTqIC T. 100—YEAR—.6— HOUR PRECIPITATION f 3.5 3 (n 2 2.5 Z r = 2 F- 0- a J LiQ 1.5 Z 1 .5 / 3.5 3 2.5 2 1.5 5 0 L I I i. I 10 2 5 10 25 50 100 RETURN PERIOD IN YEARS NOTE: I. For intermediate return periods plot 2 -year and 100 -year one hour values from maps, then connect points and read value for desired return period. For example given 2 -year one hour =.50 and 100 - year one hour = 1.60 °,25 -year one hour = 1.16�� Reterence:NOAA Atlas 2,Volume3I- California,1973. RAINFALL DEPTH VERSUS RCFC B WC D RETURN PERIOD FOR rJYDROLOGY (MANUAL PARTIAL DURATION SERIES PLATE D-4.5 a- m n �-n o n <gD z n D l-" D_ z z D r •v r m M z m x z 1) RAINFALL 'PATTERNS IN PERCENT 3-.HOUR STORM T1MC S -MIN IO -MIN IS -MIN 30 -MIN PERIOD PERIOD PERIOD PERIOD PERIOD 1 1.3 2.6 .3.1 e.S 2 1.7 2.6 4.e 10.0 ) 1.1 ],l 5.1 IJ.9 • I.S ).) 1,9 17.1 S I.S ).) e.6 29.9 6 1.0 J./ 1.) 20.J 7 I.S 1./ e.1 61 e 1.8 1,2 9.0 5.6 9 1.0 S.) IzJ I. 10 I.S S.1 11.E ,] 11 1.6 6.1 16.1 71 12 I.e S,9 1,2 .2 17 2.z 7.) .• 79 1• 2.2 e.S el .) is 2.z 11.1 .] e/ 16 eS .] e6 .2 e7 .) ee .2 e9 le i.7 2.• 91 .z 19 2.1 91 .2 91 20 2.7 .t 96 .2 21 J.3 22 1.1 2) z.9 21 ).0 25 ].1 26 1.2 27 S.0 2e ).s 29 6.e ]0 7.J )1 e.2 ] 2 S.9 )) 2.0 34 I.e JS 1.0 )6 .6 6 -HOUR STORM DIME S -MIN 10 -MIN IS -MIN JO•NIN PERIOD PERIOD PERIOD PERIOD PE 00 1 .S 1.1 l.7 .7.6 2 •6 t,2 1.9 1.J ] .6 1.) 2.1 ♦.e • ,6 1.1 2.2 1,9 S .6 1./ z.1 S.J 6 .7 1.5 2.1 S.e 1 .7 1.6 2.4 p.e e 1 t.6 2.S 9.0 z.e tl.e 10 11 .7 1.6 2.e 25.1 12 .e 1.1 ).0 1.• 13 .e 1.7 ].2 1• .0 I.e 7,6 1S /•) 16 17 .e 2.0 S.1 is .e 2.0 6.2 19 .e 2.1 6.9 20 .0 2.2 7.3 21 .e 2.3 10.6 22 a 2.e 11.45 21 .9 ).z 1.0 25 .8 ].S 26 .9 ),9 z1 .9 1,2 2e .9 I,s 29 .9 1.e JO 9 S.1 ] 1 .9 6.1 J2 .9 e.1 ) ) I.0 10.J J• 1.0 2.e 35 1.0 I.1 J6 1.0 S 77 1.0 ]e 1.1 J9 1.1 .0 1.1 11 1.2 12 I,J •7 t.• •• 1.• 15 1.S' /6 I.S /7 1.6 •6 1.0 TIME S -MIM. PERIOD PERIOD w t.7 456 1.e SI 1.9 st z.o 5 ].1 451 z.l 4545 z.z 56 2,7 57 2.• Se 2.1 59 2.S 60 2.6 61 J.1 62 ),1 6J ].9 61 •.2 es 1.7 66 5.6 67 1.9 ee ,9 I. ,e 70 ,S 71 ,] 72 .2 M NOTES: L I. 3 and 6 -hour patterns based on the Indio area thunderstorm of September 24,1939. 2. 24 -hour patterns based on the general storm of March 2 a 3,1938. 24 -HOUR STORM TIM[ IS -M1N ]0 -MIN 61•MIN PERIOD PERIOD PCRI00 P[RIOO 2 ) 7 IJ .J 1 •1 S 3 6 ] t .] 1.0 J.e e ./ 1.1 1.e 9 .♦ 1.3 6.3 10 .♦ 1.1 e.2 tl .45 1.) 1.0 12 ,S 1.6 1.] Il le,e 14 11.1 IS .s t.l 10.1 16- .6 z.S p.5 17 .6 7.0 1.1 le .7 ].J 1.9 19 .7 ].9 1.1 20 .e 1.J 1.2 21 .6 J.0 1.1 22 .1 1.0 1.0 2) 0 ).e v 21 a ),s e 25 .9 5.1 26 .9 S.7 27 1,0 6.e 2e 1.0 1.e z9 1.0 S.) 30 1 .1 S.l ) 1 1.2 1.7 ]2 1.) 7.e )] I.S e )1 I.S .6 )S J6 1./ ,9 ]7 1.9 ,e )e 2.0 ,s )9 2.1 .7 •0 2.2 s 11 1.5 .6 •z I.s .s •] 2.0 S 11 t.o .s 1S 1.9 .S 16 1,9 .1 17 1,1 .1 1e l.e .• TINE IS•MIN PERIOD PER 100 /9 2.3 so 2.e S1 2.e Sz 2. 9 5 ].1 SI 7.1 SS 2.) 56 2.] S7 2.7 se z.6 59 2.6 60 2.5 el 2.1 0z 2.J 6) 1.9 6/ 1.9 65 .1 66 .1 eT ,] ee ,] 69 s TO S 71 .S 72 77 ./ 71 .• 75 .] 76 .2 77 ) 7e .• 79 ] e0 .2 el .) 0) .] e/ ,2 eS .] e6 .2 e7 .) ee .2 e9 .l 90 .t 91 .z 92 .2 91 .2 91 t +s .t 96 .2 RUNOFF INDEX NUMBERS OF HYDROLOGIC SOIL -COVER COMPLEXES FOR PERVIOUS AREAS -AMC II Cover Type (3) Quality of Soil 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 C® RUNOFF INDEX NUMBERS ]YDROLOGY MANUAL FOR PERVIOUS AREAS PLATE E-6.1 0 of 2) 1.. Land Use (1) ACTUAL IMPERVIOUS COVER Recommended Value Range- Percent For Average Conditions- Percent(2 Natural or Agriculture I 0 - 10 I 0 Single Family Residential: (3) 40,000 S. F. (1 Acre) Lots - 70 10 - 25 Apartments 20 20,000 S. F. (� Acre) Lots 80 30 - 45 60 40 7,200 - 10,000 S. F. Lots 45 - 55 50 Multiple Family Residential: Condominiums 45 - 70 65' Apartments 65 - 90 80 Mobile Home Park 60 - 85 75 Commercial, Downtown 80 -100 90 Business or Industrial Notes: 1. Land use should be based on ultimate development of the watershed. Long range master plans for the County and incorporated cities should be reviewed to insure reasonable land use assumptions. 2. Recommended values are based on average conditions which may not apply to a particular study area. The percentage impervious may vary greatly even on comparable sized lots due to differences in dwelling size, improvements, etc. Landscape practices should also be considered as it is common in some areas to use ornamental grav- els underlain by impervious plastic materials in place of lawns and shrubs. A field investigation of a study.area should always be made, and a review of aerial photos, where available may assist in estimat- ing the percentage of impervious cover in developed areas. 3. For typical horse ranch subdivisions increase impervious area 5 per- cent over the values recommended in the table above. RCFC 0 WV HYDROLOGY MANUAL IMPERVIOUS COVER FOR DEVELOPED AREAS PLATE E-6.3 RUNOFF COEFFICIENT CURVE DATA The data in the following tables may be used to develop runoff coefficient (C) curves for any combination of 'runoff index (RI) number and antecedent mositure condition (AMC). For an RI number with an AMC of II (from Plate D -5.5) enter the tables on the following pages and plot the "C" curve data directly on Plate D-5.8. "C" curve data is given for even RI numbers only, but values may easily be interpolated for odd RI numbers. For an AMC of I or III enter the tabulation on this page with the RI for AMC II, and read the appropriate RI for AMC I or III. Use this revised RI to enter the tables on the following pages to deter- mine "C ". For example if RI = 40 for AMC II, then RI = 22 for AMC I and RI = 60 for AMC III. AMC ADJUSTMENT RELATIONSHIPS RI ►OR AMC II 10 RI FOR OTHER AMC CONDITIONS, AMC I AMC III RI FOR AMC II RI FOR OTMEP AMC CONDITIONS, AMC I AMC III 3S 74 -- 22 SS 11 -- 2A 56 36 7S 12 -- 2S 57 37 75 ' 1 -- 27 Se 3e 76 14 -- 2e 59 39 77 • IS -- 70 60 AO 7e 16 -- )1 61 •1 7e 17 -- )) 62 42 79 le -- )A 6) •7 00 19 -- )6 6 A •• el • 20 -- 77 65 As e2 21 10 3e 66 46 e2 22 1 79 67 47 e] 27 11 41 6e •e 0A 2• it 42 69 SO e♦ 25 12 A) 70 51 es 26 l2 A• 71 52 e6 27 13 46 72 S] e6 2e 14 47 73 S• 67 29 1,6 4.9 74 ss as 3 0 IS SO 7S 57 ee 71 16 11 76 Se e9 12 16 s2 77 s9 e9 33 11 17 7e 60 96 34 is SA 79 62 91 DS 1e ss ee 63 91 36 19 S6 el 64 92 37 20 57 62 66 92 De 21 se es 67 93 39 21 S9 eA 6e 93 •0 _ —22 60 eS' 70 94 Al 23 61 e6 72 94 42 T• 62 e7 73 9s •) 21 6] a 7s 95 - •• 2s 64 e9 76 96 •s 26 eS 99 7e 96 46 27 66 01 e0 97 47 2e 67 92 e1 97 Ae 29 be 97 e] 9e 49 30 69 94 as 9e s0 .. • 71 TO 95 e7 9e 11 31 70 96 e9 99 S2 72 11 97 91 99 S3 » 72 ve 9A 99 S• 74 13 99 97 -- RCFC 1YDROL OGY WC® 1\/JA NUAL PLATE D-5.7 0 of 12) X7 v w n IMPERVIOUS PERCENT 0. RUNOFF COEFFICIENTS FOR INTENSITY .0 .5 1.0 1.5 2.0 RI INDEX NO. ■ - INCHES /HOUR 2.5 3.0 3.5 28 4.0 5.0 6.0 .00 .11 .20 .27 .33 .36 .42 :45 .48 .53 .57 r .00 .13 .23 .31 .37 .42 .46 .50 .53 .57 S. 04 .1S . .24 .31 .36 .41 .44 .48 .51 .55 .59 .52 .55 10. .09 .19 .27 .34 .39 .43 .47 .50 .53 .57 .61 .51 .54 15. .13 .23 .31 .37 .42 .46 .49 .52 .55 .59 .62 .49 .53 20. .IB .27 .34 .40 .45 .48 .52 .54 .S7 .61 .64 .48 .S2 25. .22 .31 .38 .43 .47 .51 .54 .57 .59 .63 .65 .46 .SO 30. .27 .35 .41 .46 .50 .S4 .56 .59 .51 .64 .67 .4] .49 35. .31 .39 .45 .49 .53 .56 .59 .61 .63 .66 .69 D ^ 40. .36 .43 .48 .52 .56 .59 .61 .63 .65 .68 .70 .36 .4♦ 45. .40 .47 .52 .56 .59 .61 .64 .66 .67 .70 .72 45. .40 50 . .45 .51 .55 .59 .62 .64 .66 .68 .69 .72 .74 m v 55. . 49 .55 .59 .62 .64 .67 .68 .70 .71 .74 .75 D -n 60. .54 .59 .62 .65 .67 .69 .71 .72 .73 .75 .77 (- .81 65. .58 .63 .66 .68 .70 .72 .73 . T4 .75 .77 .79 .78 .72 70. .63 .66 .69 .71 .73 .74 .76 .77 .78 .79 .80 .79 .80 TS. .67 .70 .73 .74 .76 .77 .78 09 .80 .81 .82 09 .80 80. .72 .74 .76 .77 09 .80 .80 Al . .82 .83 .83 .s0 .81 85. .76 .78 .80 .81 Al . .82 .83 .83 .84 .8S .84 .81 at 90. .81 .82 .83 .84 .84 .85 .85 .86 .86 .86 .87 .83 .83 95. .86 .86 .87 .87 .87 .87 AS .MR .88 .88 .88 .85 .8S 100. .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 RUNOFF COEFFICIENTS FOR RI INDEX NO. a 32 RUNOFF COEFFICIENTS FOR R1 INDEX NO. - 30 IMPERVIOUS INTENSITY - TNCHES /HOUR PERCENT .0 .5 1.0 1.5 2.0 2.5 7.0 3.5 4.0 5.0 6.0 0. .00 C z IMPERVIOUS PERCENT 0. .0 .5 1.0 INTENSITY - INCHES /HOUR 1.5 2.0 2.5 3.0 3.5 4.0 5.0 6.0 .00 .13 .23 .31 .37 .42 .46 .50 .53 .57 .61 .04 .16 .25 S. .04 .17 .27 .34 .40 .45 .48 .52 .55 .59 .63 .35 n .45 10. .09 .21 .30 .37 .43 .47 .51 .54 .56 .61 .64 .51 .54 .57 15. .13 .2S .33 .40 .45 .49 .53 .56 .SO .62 .65 .62 .65 25. 20. .18 .29 .37 .43 .48 .S2 .SS .58 .60 .64 .67 .27 .36 .42 2S. .22 .33 .40 .46 .SO .S4 .S7 .60 .62 .66 .68 .51 m .58 30. .27 .36 .4] .49 .53 .S7 .59 .62 .64 .67 .70 i .65 0 35. .31 .40 .47 .S2 .S6 .S9 .62 .64 .66 .69 .71 .71 .73 S0. 40. .36 .4♦ .SO .SS .58 .61 .6♦ .66 .6B .70 .73 .49 .SS m 45. .40 .48 .53 .S8 .61 .64 .66 .68 .69 .72 .74 m 0 m 50. .45 .52 .57 .61 .64 .66 .68 .70 .71 .74 .76 .74 D -n S5. .49 .S6 .60 .64 .66 .68 .70 .T2 .73 .75 .77 0 .81 7S. 60. .S4 .S9 .63 .66 .69 .71 .73 .74 .75 .77 .78 .72 D (7 6S. .58 .63 .b1 .69 .72 .73 IS .76 .7T .79 .80 .81 .82 - 70. .63 .67 . TO . T2 .74 . T6 .77 .78 09 .80 .81 �l .R6 m 7S. .67 .71 .T3 .75 .77 .78 .79 .s0 .81 .82 .83 .88 .88 Z 80. .72 .7S .77 .78 .79 .80 .81 at .83 .83 .84 85. .76 .79 .80 .81 .82 .83 .83 .84 .84 .85 .86 O 90. .81 .8f .83 .84 .85 .8S .86 .86 .86 .87 .87 -w 9S. .86 .86 .67 .87 .87 .88 .88 .88 .88 .88 .89 N 100. ..90 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 RUNOFF COEFFICIENTS FOR R1 INDEX NO. - 30 IMPERVIOUS INTENSITY - TNCHES /HOUR PERCENT .0 .5 1.0 1.5 2.0 2.5 7.0 3.5 4.0 5.0 6.0 0. .00 .12 .22 .29 .35 .40 ,44 .40 .51 .55 .59 S. .04 .16 .25 .32 .38 .43 .46 .50 .53 .57 .6l 10. .09 .20 .29 .35 .41 .45 .49 .52 .55 .59 .62 15. .13 .24 .32 .38 .43 .48 .51 .54 .57 .61 .64 20. .18 .28 .36 .41 .46 .50 .53 .55 .59 .62 .65 25. .22 .32 .39 .44 .49 .53 .56 .58 .60 .64 .67 30. .27 .36 .42 .4T .52 .55 .58 .60 .62 .66 .68 35. .31 .40 .46 .51 .54 .58 .60 .62 .64 .68 .70 40. .36 .43 .49 .54 .57 .60 .63 .65 .66 .69 .72 45. .40 .47 .53 .57 .60 .63 .65 .67 .68 .71 .73 S0. .45 .51 .56 .60 .63 .65 .67 .69 .70 .73 .75 5S. .49 .SS .S9 .63 .65 .68 .69 .71 .72 .74 .76 60. .54 .59 .63 .66 .6R .70 .72 .73 .74 .76 .78 65. .SR .63 .66 .69 .71 .73 .74 .75 .76 .78 .79 70. .63 .67 .70 .72 .74 .75 . 76 .77 .78 .80 .81 7S. .67 .71 .73 .7S .76 .78 .79 .79 .80 .81 .82 '80. .72 .74 .76 .78 .79 .80 .81 . R2 .82 .83 .84 85. .76 .78 .80 .81 .82 .83 .83 .84 .84 .85 as 90. .81 .82 .83 .84 .85 as AS .R6 .86 .87 .87 95. .86 .86 .87 .87 .07 .88 .88 .88 .88 .88 .88 100. .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 RUNOFF COEFFICIENTS FOR RI INDEX NO. s 34 IMPERViOUSI INTENSITY - INCHES /HOUR PERCENT .0 .S 1.0 1.5 7.0 2.5 3.0 3.S 4.0 5.0 6.0 0. .00 .1S .25 .33 .39 .44 .48 .52 .SS .59 .63 S. .04 .18 .28 .36 .42 .47 .SO .S4 .56 .61 .64 10. .09 .22 .32 .39 .44 .49 .52 .56 .58 .62 .66 I5. .13 .26 .35 .42 .47 .51 .SS .ST .60 .64 .67 20. .18 .30 .38 .44 .49 .53 .57 .59 .62 .6S .68 25. .22 .33 .41 .47 .52 .56 .59 .61 .63 .67 .70 30. .27 .37 .4S .50 .S4 .58 .61 .63 .65 .69 .71 35. .31 .41 .48 .S3 .ST .60 .63 .6S .67 .70 .72 40. .36 ,4S .51 .56 .60 .63 .65 .67 .69 .72 .74 4S. .40 .49 .S4 .59 .62 .65 .67 .69 .71 .73 .7S S0. .45 .52 .58 .62 .6S .67 .69 .71 .72 .7S .76 SS. .49 .56 .61 .64 .67 .69 .71 .73 .74 .76 .78 60. .S4 .60 .64 .67 TO .72 .73 .75 .76 .78 .T9 65. .58 .64 .67 .70 .T2 .74 .7S .17 .78 .79 .8.1 70. .63 .67 .71 .73 .75 .76 .77 .79 .79 .81 .82 7S. .67 .71 .74 .76 .77 09 .80 .80 .81 .82 .83 80. .72 .7S .7T .79 .80 .81 .82 .R2 .83 .84. .85 85. .76 .79 .80 .81 .62 .83 .84 .84 .8S .85 .86 90. .81 .82 .84 .84 AS .8S .86 .R6 .86 .87 .87 95. .86 .86 .87 .87 .87 .88 .88 .86 .88 .88 .89 100. .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 .90 LIMITATIONS: Tc' L 100 1000 90 900 80 800 70 1700 60 LIMITATIONS: Tc c I. Maximum length = 1000' 2. Maximum area = 10 Acres a 50 :7 600 a c o— V 500 0 my 400 300 c (V > 200 c o N 6. ' p °1 •- a ~ E � 0 - 500 aCi 0 0 a 50 40 E CL o' N o v 3 0 m c _v m 35 W r•, 10 a m 8 400 3 30 c Ai 0` Undeveloped m 350 Good Cover 25 o Undeveloped � 1. Fair Cover 300 _c Undeveloped Poor Cover E .4 l,Ll .2 / c 20 - (1/4 Acre) z 19 o - 250 18 17 • 20 16 v o a� 15 o, o 14 d 200 25 13 J Q 12 U c � II 0 w 0 150 9 E i- 8 7 6 100 i 5 4 LIMITATIONS: Tc I. Maximum length = 1000' 2. Maximum area = 10 Acres a :7 > H c o— V 500 my 400 300 c o v` > 200 c o N 6. ' p °1 •- a ~ E 100 0 - 80 60 aCi 0 0 a 50 40 E CL o' N o v 3 0 o c 20 ` 10 8 3 6 K Ai (/) Undeveloped 0 _ Good Cover °' m 2 Undeveloped 0 c 1. Fair Cover ., .6 Undeveloped Poor Cover 0 c o .4 l,Ll .2 / Single Family 50 > / (1/4 Acre) z Commercial Ow • 20 c o a� 'o ,l o R C FC 6 T V® HYDROLOGY MANUAL KEY L-H Tc -K --Tc' :�FE Tc 5I :�FE EXAMPLE: E i= (1) L =550', H =5.0, K= Single Family(1 /4 Ac.) 35 Development , Tc = 12.6 min. (2) L =550'2 H = 5.0',.K = Commercial 40 Development , Tc = 9.7 min. Reference: Bibliography item No. 35. PLATE D -3 U Q :7 c 8 a 0 m 9 0 10 E v U- - 12- o` 14 '~ N 15 w 16 E E 17 18 19 • 20 c o 'o C 25 0 U 0 30 EXAMPLE: E i= (1) L =550', H =5.0, K= Single Family(1 /4 Ac.) 35 Development , Tc = 12.6 min. (2) L =550'2 H = 5.0',.K = Commercial 40 Development , Tc = 9.7 min. Reference: Bibliography item No. 35. PLATE D -3 �f A . W z_ J 3 F— W W I` N I I iF OPEN CHANNEL The 100 -Year flood shall be contained within street R/W limits. The 10 -Year flood shall-be contained within the Top of curbs. Initiate a storm drain or channel when either condition is exceeded. w f— z W J W in (4j f 41 W cr_� F- Cn l M I TYPICAL I FREE BOARD UNDERGROUND STORM DRAIN J DWELLING UNIT PAD NOTES: Protection criteria shown are the Districts typical minimum requirments. Special conditions, or other authorities may require stricter controls; ie; for reasons of traffic or pedestrian safety, maintenance problems behind curbs, etc., lower maximum depths of flow in streets may be required.Also see Riv. Co. Ord. No. 460. RCFC 8 WC D -HYDROLOGY ]MANUAL FLOOD PROTECTION CRITERIA ' PLATE A -2 I s 2 \/ 5 j\ 6 \j Q CQ W U R a O 2 O a 0 3 Lb 0 0 W Al \ i k R . �1DETAIL K .� \\ ® MIN. 6" 0 DRILLED SHAFT 6 �i MAXWELL PLUS DRAINAGE SYSTEM i\ (OR EQUAL) %\ NTS CL ® OVERFLOW PIPE - SCHEDULE 40 PVC. SEAL MATED TO DRAINAGE BELOW BASE s 2 \/ 5 j\ 6 \j Q CQ W U R a O 2 O a 0 3 Lb 0 0 W Al \ i k R . i. ® MIN. 6" 0 DRILLED SHAFT O SUPPORT BRACKET - FORMED 12 GA STEEL FUS I ON BONDED EPDXY COATED. ® OVERFLOW PIPE - SCHEDULE 40 PVC. SEAL MATED TO DRAINAGE BELOW BASE (O DRAINAGE PIPE - ADS HIGHWAY GRADE 7 WITH MD/-A COUPLER SUSPEND PIPE OPERATIONS TO DURING BACKF /LL PREVENT BUCKLING OR BREAKAGE. / © BASE SEAL - GEOTEXTILE, POLY LINER OR CONCRETE SLURRY. ©ROCK -CLEAN &WASHED, 5 /ZED BETWEEN I MANHOLE CONE - MODIFIED FLAT BOTTOM. & I" TO BEST COMPLEMENT SOIL CONDITIONS [� STABILIZED BACKFILL - 1 SACK ® FLOFAST* DRAINAGE SCREEN - SCHEDULE CONCRETE SLURRY IN PAVED AREAS. 40 PVC 0, 120 SLOTTED WELL SCREEN WITH 32 Q BOLTED RING & GRATE /COVER - CLEAN SLOTS PER ROW /FT, 96" OVERALL LENGTH CAST IRON WITH WORDING STORM WATER ONLY" WITH MDl -B COUPLER. IN RAISED LETTERS SECURED TO CONE WITH ©M /N. 4' m SHAFT - DRILLED TO MAINTAIN MORTAR. RIM ELEVATION = 0.02' OF PLAN PERMEABILITY OF DRAINAGE SOILS. O GRADED BASIN OR PAVING - (BY OTHERS) ® FABRIC SEAL - UV RESISTANT GEOTEXT /LE - I 5 COMPACTED BASE MATERIAL - (BY OTHERS) O TO BE REMOVED BY CUSTOMER AT PROJECT © PUREFLO DEBRIS SHIELD - ROLLED 16 GA. COMPLETION. © CONNECTOR PIPE - 4" 0 SCH 40 PVC WITH— STEEL X 24" LENGTH WITH VENTED FLOW REGULATOR. — AN /T- SIPHON AND INTERNAL 265' MAX. ® ABSORBENT - HYDROPHOBIC PETRO- SWO FLATTENED EXPANDED STEEL CHEMICAL SPONGE. MIN. 100 OZ. CPACITY. SCREEN X 12" LENGTH FUSION BONDED COTED 09 NON WOVEN FILTER FABRIC PER EPDXY 07 PRECAST LINER - 4000 PSI CONCRETE SEC B8 DATE* 7 -84 3 CAL. STD. SPEC 48" ID, 54" OD CENTER IN HOLE AND ALIGN SECTIONS TO MAXIMIZE BEARING SURFACE. *FREEBOARD DEPTH VARIES WITH INLET PIPE ELVAT/ON. INCREASE INTERCEPTOR/ SETTLING CHAMBER DEPTH AS NEEDED TO MAINTAIN ALL INLET PIPE ELEVATIONS ABOVE CONNECTOR PIPE OVERFLOW. s 2 \/ 5 j\ 6 \j Q CQ W U R a O 2 O a 0 3 Lb 0 0 W