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Home My WebLink AboutParcel Map 19580-1 Parcel 3 Hydrology StudyHYDROLOGY REPORT FOR Home 2 Temecula A? /:I�- //9?5" Single Oak Drive Temecula, CA June 27", 2015 Prepared By: �COF SS/0 Omega Engineering Consultants �p Q�EW 4340 Viewridge Ave, Suite B San Diego, CA 92123 Ph: (858)634-8620 No. C 50940 * F.XP.91301jj �r CN�� tiP fA , &" LI/5�7/z Vnrew J. KIXI RC 50040 Registrationpires 9-30-2017 D TABLE OF CONTENTS -SITE AND PROJECT DESCRIPTION page 1 -METHODOLOGY page I -CULVERT DESIGN AND ANALYSIS page I -EXISTING CONDITIONS page 1 -DEVELOPED CONDITIONS page I -EXISTING RUNOFF ANALYSIS page 2 -DEVELOPED RUNOFF ANALYSIS page 2 -RESULTS AND CONCLUSIONS page 3 -I O-YEAR HYDROLOGY CALCS page 4 -I00-YEAR UNMITIGATED HYDROLOGY CALCS page 5 - 100-YEAR ORIFICE MITIGATED HYDROLOGY CALCS page G -PONDING VOLUME CALCULATIONS page 7 LIST OF FIGURES FIGURE 1: VICINITY MAP FIGURE 2: PROPOSED HYDROLOGY MAP FIGURE 3: EXISTING HYDROLOGY MAP APPENDICES APPENDIX 1.0: HYDROLOGIC SOIL GROUP MAP APPENDIX 2.0: TIME OF CONCENTRATION NOMOGRAPH APPENDIX 3 A: INTENSITY DURATION CURVE r SITE AND PROJECT DESCRIPTION This Hydrology and Hydraulics report has been prepared as part of a conceptual design for the proposed hotel on a vacant lot between Single Oak Drive and Rancho California Road. The structure and associated hardscape will cover the majority of the existing mass graded pad. See Figures 1-3 for more detail. METHODOLOGY This drainage report has been prepared in accordance with current County of Riverside regulations and procedures. All of the proposed conduits and conveyances have been designed to intercept and convey the I00Wyear storm. Sizing calculations shall be included in the final hydrology report. The Modified Rational Method was used to compute the anticipated runoff. See the attached calculations for particulars. The following references have been used in preparation of this report: (1) Handbook of Hydraulics, E.F. Brater & H.W. King, 6t1' Ed., 1976. (2) Modern Sewer Design, American Iron & Steel Institute, 1" Ed., 1980. (3) County of Riverside Hydrology Manual, 1978 j EXISTING CONDITIONS: The existing site consists of a mass graded pad with a 3:1 cut slope along the westerly boundary. The cut slope has several large eucalyptus trees and the pad is lightly vegetated with weeds. The pad slopes to the north east at 2.0 % and drains via an existing driveway apron to the southerly gutter of Single Oak Drive. Runoff flows along the gutter for 750 feet until it is intercepted by a curb inlet on Business Park Drive � The site is 2.66 acres in area and is not subject to stormwater run-on from offsite areas. The existing site is entirely pervious with no permanent structures in place. DEVELOPED CONDITIONS: This project proposes the construction of a new hotel with associated hardscape. The proposed building will be located in the center of the lot. The project will disturb the majority of the site and increase the impervious area from 0.0% to 49.8% . This will increase the 100 year peak runoff flow rates produced by the site from 5.44 cfs to 8.28 cfs. This will be offset by the use of outlet control and detention in the bioretention area along the northerly boundary of the site. The proposed site will discharge via a proposed parkway drain to the southerly gutter of Single Oak Drive. Runoff will thence flow along gutter until it is intercepted by the existing curb inlet on Business Park Drive, The confluenced flow discharged by the proposed site will not exceed the existing 100-yr storm peak flow. In addition to detaining onsite stormwater, the bioretention facilities will treat stormwater for various pollutants before it is discharged from the site. See Water Quality Management Plan (WQMP) for details. 1 I 11 i EXISTING RUNOFF ANALYSIS: All of the existing site drains via overland flow to a single outlet point at the northeasterly corner of the site. Only one basin (EX-1) was required for existing calculations. The basin was found to have the following characteristics. Fil, Area: 2.66 acres Impervious %: 0.0% Length: 420 ft s J Elevation Change: 24 ft Time of Concentration: 10.5 mins Peak 100-year discharge: 4.55 cfs The time of concentration was calculated using to the Riverside County Hydrology Manual r-, nomograph late D-3 found in Appendix 2 of this report). Intensities were estimated using the j g p �p pP P }• g 1 values found in the hydrology manual on plate 4.1 (included as appendix 3 of this report, and the runoff coefficient was found via the equation on plate D-3. See the attached calculations for details. DEVELOPED RUNOFF ANALYSIS: The developed site calculations divide the site into two separate basins (A-1 & B-1) both of which drain to a confluence flow via overland flow and concentrated gutter and pipe flow. Basin A-1 was found to have the following characteristics. Area: 1.79 acres Impervious %: 47% Length: 500 ft Elevation Change: 24 ft Time of Concentration: 9.25 mins Peak 100-year discharge: 5.55 cfs Basin B--1 was found to have the following characteristics. Area: 0.87 acres Impervious %: 55% Length: 540 ft Elevation Change: 24 ft Time of Concentration: 7.75 mins Peak 100-year discharge: 2.91 efs The two flows were confluenced according to the equations on Plate D•-1 of the county hydrology manual. The confluenced 100 year flow was found to be 8.28 cfs. This flow will be reduced to match the existing peak flow of 4.55 using an outlet control structure and ponding within the bioretention area along the northerly boundary. See detention sizing calculations for required storage volume. 2 RESULTS AND CONCLUSIONS The redevelopment of the site shall result in an increase in peak runoff volumes and flow rates for the 100 year event. This is due to the increase in impervious area of the site. The impervious area percentage of the existing site is 0.0% and the proposed site will be 49.8%. The result is a peak discharge flow rate that is higher than the existing condition. This increase will be mitigated through the use storage in the northerly bioretention, and an outlet control orifice. The result will be a proposed discharge that is equal to or less than the existing conditions. The required storage volume is 1,534 cf, which is equivalent to 1.1' additional ponding in the northerly bioretention area. Outlet control orifice calculations can be found in the calculations section at the end of this report It is the opinion of Omega Engineering Consultants that the project will not cause adverse effects to the downstream facilities or receiving waters. A separate Water Quality Management Plan (WQMP) has been prepared to discuss the water quality impacts for the proposed development. E U 3 r 4 i 4 n .S u 1] 1� LJ 2 IIIIIIIIIIIIIIIIIIIIII oil 1111111111111111111111 LU rq n L1 1 J I -"Yfy l 0 LL z 0 U 7 Q V 0 LU f � Q z 0 Q Nlllllllullllllllllllll r--: Lj P-1 a S u 2 �NIIWIIIIIIIIIIIII ■f11111111A11111111111 Illlflllll■1111111111111 LL �1�1111�1111�1111111111111 LU IIIIIII�IIIIIIIIIIIIIIII v 4[Q+ a CO �7 N_ m d u y V N m N Q ori m a � I 06E OSE OLE 09E osE 0VE ❑EE ozE ols p) 00E 06Z oSz Q OLZ 09Z _ 0sZ .� 017Z i OEZ Oi OC 0zz ozz = ooz 061 E +L, .s cr Low �► $Z [- 0L L 09Z OST otiT OEEI `- l oz, OIi ooi 0s 08 oL 09 os ot, OE OZ 01 0 v o o v o o v o 0 0 of oo ri 6 Sri 4 m N t-i o Temecula Home2 Suites Hydraulic Analysis of basin outlet structure DETENTION BASIN ORIFICE EQUATION Weir Formula for Orifices and Short Tubes (free & submerged) Q = Ca(2gh)"-7 (Eq. 4-10, Brater & King, Handbook of Hydraulics) 1kA ITM or Q = the flow rate, ft3lsec C = the orifice coefficient of discharge a = the open area of the orifice g = the acceleration due to gravity h = head on the horizontal centerline of the orifice Q = Ca(2 *32.2)11)112 Q = Ca(64.4h)r12 ( C = 0.52 for reentrant tube, from page 4-19, Brater & King, Handbook of Hydraulics) Q = 4.172a(h)r/2 a = Q 1(4.172(I1)112) Detention Basin Cale Given: Q = 2.71cfs Assume: h = 3.43ft Then: a =n .349 sf — 8" Diameter Opening Therefore, 100-yr flow control will be accomplished by the maximum capacity of the 8" storm drain under the proposed maximum head conditions. The invert of the 8" storm drain will be constructed 4.1 feet lower than the invert of the emergency overflow spillway. (Center line of the orifice will be 3.43 ft lower than spillway) FIJI Rational Method Hydrograph Program "Rick RatHydro" @ 1992, 2001 Rick Engineering Company 1 Time of concentration: 9 min 6 Hour Rainfall: 3 in Basin Area 2.67 ac Runoff Coefficient: 0.85 (Calc`d weighted average of sub -basins) i -f Peak developed ❑ischarge: 8.28 Required retention volume: 1,534 cf Time (Min) Inflow (cfs) Discharge Rate(cfs) 0 0.00 5.44 9 0.00 5.44 18 0.40 5.44 27 0.40 5.44 36 0.40 5.44 45 0.40 5.44 54 0.50 5.44 63 0.50 5.44 72 0.50 5.44 81 0.50 5.44 90 0.50 5.44 99 0.50 5.44 108 0.60 5.44 117 0.60 5.44 126 0.60 5.44 135 0.60 5.44 144 0.70 5.44 153 0.70 5.44 162 0.80 5.44 171 0.80 5.44 180 0.90 5.44 189 0.90 5.44 198 1.10 5.44 207 1.20 5.44 216 1.40 5.44 225 1.60 5.44 234 2.40 5.44 243 7.20 5.44 252 8.28 5.44 261 1.90 5.44 270 1.30 5.44 279 1.00 5.44 288 0.80 5.44 297 0.70 5.44 306 0.70 5.44 315 0.60 5.44 324 0.50 5.44 333 0.50 5.44 342 0.50 5.44 351 0.40 5.44 360 0.40 5.44 369 0.00 5.44 PQ 15 �o �o PSG R� �R�Lfi S1t4GLE OAK�R� SITE VICINITY MAP NO SCALE HOME 2 TEMECULA PROPOSED HYDROLOGY EXHIBIT LEGEND. - PROJECT BOUNDARY . . . . . — AREA LIMITS - � . . . . . . . . . . . . . ?AINAGE DIRECTION ARROW . . . . . . . . . . . an min SIN NUMBER . . . . . . . . . . . . . . . . . A-1 TABLE OF BASIN DA TA .4SIN AREA IMPERVIOUS % LENGTH (FT) HEIGHT (FT) Oloo 1 2.66 A C 007, 420 24 5.44 CFS SCALE.' 1" = 601 0 30 60 120 OMEGA ENGINEERING CONSULTANTS 4344 viEWRIDGE AVENUE, SUITE B SAN DIEGCI, CALIFGRIVIA 92123 PFI.• (858) 634-8624 Ff1X.• (858) 634-862 7 0 J 0 0 2 X W J 1-1 701216�ml o7:11D7:(0]RMZHAal:ll: S2Tl�"i [IMENA ENSINEEHING LFUNUULIA I a I APPENDICES --7 -7 �■?.tt i` r f ra I� + r(� ►L ,ram' � �-,7re� � rr � . �;� ��''�� i +wi ELI `r��'�•�� A,r ��- • ` 'r ��ly �r4a�1 1 • e � � • �� 7 _ (�v f�,,• Sri i'� ir�i�s¢■ �3 tr/' �i}+�6T �,�� I `+S �'c�z +1a rtA ,■qr;tt`�� rXjn �' I �ti{ e f f Y �r ol _1trA ��,p4t��l� � �� lr;� ��j4� Y�i�,�11�� J ,�,�,�� .% ;�_f♦ .,�� ,�,> ��=emu ,^�,[�.Li J,N _ -Y�.. , �� ,� � L (/ L is �1-y� A�A ��►';�, 1 'y]+�►!f, �t�`•`� p1}.. !.� rp �a.Ob� J ?�S' L �� '}�.r� : j �� i' Fy'ri?� # at I ... f�� •'� �}%y��/� ��"3Y�� . �1 �� fi � � �i��:/) r,�7 wr� � � I � �� t • ti,�`1.��p�� x *��wl�y. �" f�y� ��'idAS�iC��yk4�i }\:'17 ��i�� it m. �� r +�aiT1'�.i�l� Y_t� �� • dt��*�1�.:'i .YlC��f� `�� 7T. �1�u�1r:�,GY• f1. 1��6.+A�i1.�Y TC1 LIMITATIONS: , L 100 I. Maximum length =1000' TC . 1000 90 2. Maximum area = 10 Acres 5 -, i 900 80 ^ L 800 70 H 0 500 ^ , � � 400 300c cSO 700 200 7 .. w V .� E 100 fo0 a50 so 1111 1 v a� a10 8 0 •- a ; K A i a 6 1 j l I �}pp �. 0 30 Undeveloped 0 w 12 a• -� Good Cover z J m 350 r 25 Undeveloped .0 Un eveiope ._ 0 . c _ Fair Cover :s 14 w 7 300 E 2D 0 ..4 15 .c r'. PoarUndeYeCoved •� Is ; l 7 I Single mily 17 E J _j 250 16 A I8 119 Co er ' I 0 .0 v 4 Pa 20-12 m 200 13 �' o `2 2 1 i C 25 _1 F71=7710.5 minutes KEY 9 L-wH-Tc --K-Tc' o 30 A -'I= 9.25 minutes 8 EXAMPLE: E L7 (1j L =550% H =5.0, K = Single Familyt114 Ac.) 35 _ B-I= 7.75 minutes Development , TC =12.6 min. -, 6 (2) L =550', H =5.0', K = Commercial 10p Development , Tc = 9.7 min. 40 5 J 4 i RCFC & WC D HY17Pti1OGY �VJANUAL Reference; Bibliography item No. 35. 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