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28545-3T 11111111 11111111 LA QUINTA RESORT AND CLUB HYDROLOGY AND HYDRAULIC REPORT FOR ENTRY DRIVE IMPROVEMENTS `�K 3 PREPARED BY: STANTEC CONSULTING, INC. 73 -733 FRED WARING DRIVE, SUITE 100 PALM DESERT, CA 92260 PREPARED FOR: LA QUINTA RESORT AND CLUB 49 -499 EISENHOWER DRIVE LA QUINTA, CA. 92253 September 18, 2008 Prepared Under the Supervision of: E'�`"C�n'O L o 6—r S (.w_" Brooks D. Franklin R.C.E. 61887 Expiration Date: September 30, 2009 �O('L1 Co a V:\ 2017\ active\ 2017110600 \civil\report\drainage\Hydrology and Hydraulic Report.doc 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 LA,QUINTA RESORT AND CLUB HYDROLOGY AND HYDRAULIC REPORT FOR ENTRY DRIVE IMPROVEMENTS TABLE OF CONTENTS: I PURPOSE AND SCOPE II DESIGN OF PROPOSED IMPROVEMENTS III RATIONAL METHOD CALCULATIONS -100 YEAR IV CATCH BASIN SIZING CALCULATIONS V STORM DRAIN PIPE NETWORK ANALYSIS VI HYDROLOGY MAP. V:\ 2017\ active\ 2017110600 \civil\report\drainage\Hydrology and Hydraulic Report.doe 1 1 L� 1 ' I PURPOSE AND SCOPE The purpose of this report is to provide a hydraulic and hydrologic study to accompany the Entry Drive Improvement Plan for the proposed revisions to the La Quinta Resort's main entry- drive. The. resort. is located on both sides of Eisenhower Drive in the City of La Quinta. The main entry drive is located off of Eisenhower Drive, on the west side, between Avenida ' Fernando (to the north) and Avenue 50 (to the south) and is a full movement, three -way intersection with no traffic signal. ' This report summarizes the hydraulic and hydrology requirements for the entry drive, and considers the existing site and future adjacent improvements. ' The existing entry drive is asphalt concrete and approximately 40' wide by 600' in length. The entry drive is not impacted by adjacent or off -site storm flows (see hydrology map). There are two existing 15 "x15" grated inlets at the westerly end of the entry drive which ' intercept the tributary storm flows. The existing drive is essentially flat with similar elevations at the westerly and easterly ends. With regard to an emergency overflow, should ' the existing grated inlets become plugged, the storm flows would be directed along the entry drive (from west to east) and into Eisenhower Drive. An existing 24" storm drain pipe runs parallel to the entry drive, within the existing planning area to the north. This pipeline accepts the entry drive storm flows (as described above) as well as storm flows from two existing inlets in the hotel "drop off' area. The flows are conveyed via gravity eastward to a combination drywell and pump station wet well. No improvement plans for the 24" onsite gravity storm drain were available from the City or the hotel operator. However, the hotel operator was able to provide existing plans for the pump station wet well and associated 8" PVC force main. These plans indicate that storm flows ,are piped from the wet well (located behind the northerly curb return/entry walls at the entry drive) approximately 1;800 feet south along Eisenhower and then easterly to an existing golf icourse lake on the east side of Eisenhower. Z - c OV ' II DESIGN OF PROPOSED I PREMENTS n The proposed improvements co/e. of a new entry drive with two, twenty -foot lanes (with enhanced concrete pavement overs) divided by an eight -foot planted median. The existing drain inlets will be repl with new catch basins and two additional inlets will be added near the middle of the dri The proposed improvements will be "private ", but will meet the curre Ci o a um�an ar s. Note that the proposed drain "tie. into" a system which is over twenty years old, and is,part gravi art force main. Further, the existing and proposed storm flows at the entry drive are essentially -the same, and the emergency overflows are also the same. Therefore, no.analysis of the pump station or other onsite existing facilities is included in this report. V,\ 2017 \active\2017110600 \civil\report\drainage \Hydrology and Hydraulic Report.doc 1 L_ J pQ.� .✓�. 1 1 E 1 Fl 1 1 J t 1 1 1 1 1 III RATIONAL METHOD CALCULATIONS —100 YEAR In accordance with the Riverside County Flood Control Hydrology Manual and City of La Quinta Engineering Bulletin #06 -16, Rational Method calculations are typically used to 7i .estimate flow rates to model street flow capacities and size catch basins. However, since the tributary areas are small (varies from 0.12 acre to 0.18 acre) and the proposed inlets are all in sump conditions, we have utilized a simplified approach to developing storm flows as suggested in Engineering Bulletin #06 -16. Conservatively using 5cfs /acre for a 100 -year storm event we have: INLET INLET TYPE INLET SI TRIBUTARY 160 -YEAR Highway Pavements (HEC -12), the interception capacity of the combination inlet in a sag condition is essentially equal to that of a grate alone in weir flow, unless the grate AREA FLOW CB -1 COMBINATION 2' 3' 5,010 S.F. 0.6 cfs inlets are considered advisable for use in sags because of their ability to INLET IN A SAG continue to provide inlet capacity even when clogging of the grate occurs. ' All combination curb opening — grate inlets proposed at the La Quinta Resort entry drive CB -2 COMBINATION 2 3' curb to top of grate). A copy of the inlet capacity chart for inlets in sump conditions 5,980 S.F. 0.7 cfs INLET IN A SAG CB -3 COMBINATION 'x3' 7,800 S.F. 0.9 cfs INLET IN A SAG CB -4 COMBINATION ' 7,800 7,800 S.F. 0.9 cfs INLET IN A SAG ' IV CATCH BASIN SIZING CALCULATIONS According to the Federal Highway Administration's (FHWA) guidelines for Drainage of Highway Pavements (HEC -12), the interception capacity of the combination inlet in a sag condition is essentially equal to that of a grate alone in weir flow, unless the grate opening becomes clogged. In the. event that the grate portion of the inlet becomes ' clogged, the inlet acts as an orifice and the curb opening portion of the inlet is used to provide the inlet capacity. rCombination inlets are considered advisable for use in sags because of their ability to continue to provide inlet capacity even when clogging of the grate occurs. ' All combination curb opening — grate inlets proposed at the La Quinta Resort entry drive are Nyloplast 2' X 3' Diagonal Curb Inlet Grates with 7" hood settings (7" from top of curb to top of grate). A copy of the inlet capacity chart for inlets in sump conditions (from FHWA HEC -12, Chart 11) is attached. 1 The chart shows that the inlet capacity for a grated inlet is 5.7 cfs after a recommended factor of safety of 2.0 (or 50% clogging) is applied. Therefore, all inlets have the capacity to intercept the 100 -year storm flow. r V:\2017\active\20171 10600 \civil\report\drainage \Hydrology and Hydraulic Report.doc 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 V STORM DRAIN PIPE NETWORK ANALYSIS The storm drain pipe network analysis (or hydraulic calculations) were prepared using the StormCAD software. The catch basins and pipe segments are named so that the report and plan correspond. Catch basins are identified as CB -1 to CB -4 and pipe segments are identified as P -1 to P -4. The "tie -in" pipe is the existing 24" storm drain pipe north of the entry drive. Note the analysis was performed only for the 100 -year event since all of the inlets were in sump condition. Further, since the existing 24" "tie -in" pipe drains into a drywell, with an overflow connection to the pump station wet well, we utilized this overflow elevation in our calculations as the corresponding depth of ponding in the "tie in" pipe, for both pipe segments P -2 and P -4. Based on an elevation of 38.17, the hydraulic grade line for P-4 at the "tie -in" is above the pipe soffit. The hydraulic calculations indicate that proposed 12" pipes are satisfactory to convey the storm flows to the existing 24 " storm drain. Note that the existing piping is only 6" diameter PVC pipe. Velocites for the proposed pipe vary between 5.4 to 12.5 fps. See attached StormCAD reports. Vl 11YDROLOGY MAP See attached hydrology map. VA2017active\ 2017110600 \6vil\rep0rt\drainage\Hydrology and Hydraulic Report.doc 1 1 1 1 1 1 _ ,� n } : _ I depth measurements zom,�xperlment d,,, sts wer "e not taken:at the weir, and :drawdou�n occurs 11 � een t #e1po nt where m�asureMents<were�made and the weu¢N �a; 11- b x x Fi 5 y ,", ',weir locati ©n xfor a'`de ressed curbo enin inlet is at the ed e of the utter and the effcti�e�veir r 11 P, P. g g 11, e his dependenton the width of the depressed gutter�ancl the length of the curb opening The weir' ., , r� } =t ovation for a curboperiu`g inlet &that is not depressed its at the lip tof the curb opening, and its length is % A that of the inlet Limited expenments and extrapolation ofAthe resuts ofgtests on depressed inlets = 111111%, I n cafe that�the wSelr coefficient, for curb opening inlets without depression is approximately egla 40 that ,. k f a depressedcub opening m�let f 4 , ` [' equation for the x t'e cept�o ,capa arty of�a depx:essed�,curb opening rile operating as a , , is' � , , r a a„,�, x h -- s ,� t r i.� r.x - a. < e - r a > - y,�, k �' a ,i« - , i}`' 3 yae. 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'a r e Fn"'t . .. �# r) ,tin % S �tr�, '� "1 � t , - '� y , �" � ilea , .t's , . x�, � p illr � � � �3 'C' ;�r � ����I 4. /A� t �l i 7 .z 'It ). i y • 'Chart 11 .Grate rnlet capacrty;in sump conditions :s x 1, �� "� le, 11 4 e k $ e q 3 t d §_ x g f V.. r€ '� a t f F —x - .rc a` b� fwNmRmmK%*: +� ' y„ { 4 ,z CB-1 CB-2 Me In P -1 V-2 c Vi T N. Z r N X U1 Bentley Systems, Inc. Haestad Methods Solution Bentley StormCAD V8 XM Edition Pipel.stc Center [08.09.061.00] 27 Siemon Company Drive Suite 200 W Page 1 of 1, 9/22/2006 Watertown, CT 06795 USA +1- 203 - 755 -1666 1 1 J 1 1 1 I J AASHTO Expansion, Ke 0.35 0.5 Contraction, Kc 0.25 1.3 Bend Angle vs. Bend Loss Curve Generic Structure Loss Governing Upstream Pipe Pipe with Maximum QV Selection Method ' Calculation Detailed Summary. (CB -1, CB -2, P -1 AND P -2) Element Details ID 13 Notes Label Base Calculation Options Hydraulic Summary Flow Profile Method Backwater Analysis Average Velocity Method Actual Uniform Flow Velocity Number of Flow Profile 5 Minimum Structure 0.00 ft Steps Headloss Hydraulic Grade 0.001 ft 5.000 min Convergence Test ' Inlets Neglect Side Flow? FALSE Active Components for Grate and Curb ' Combination Inlets In Sag Neglect Gutter Cross TRUE Active Components for Grate and Curb Slope For Side Flow? Combination Inlets on ' Grade H EC -22 Elevations Considered 0.5 ft 1 Equal Within Consider Non -Piped False Half Bench Submerged 0.95 Plunging Flow Flat Submerged 1 0.15 Flat Unsubmerged 1 0.75 Depressed Submerged 1 0.07 AASHTO Expansion, Ke 0.35 0.5 Contraction, Kc 0.25 1.3 Bend Angle vs. Bend Loss Curve Generic Structure Loss Governing Upstream Pipe Pipe with Maximum QV Selection Method 1 1 1 i 1 rl t t 1.. Catchment Summary Conduit Summary Node Summary CB -1 Catch Basin Tie In 0.7 0.7 CB -2 Catch Basin Tie In 0.6 1.3 Inlet Summary Pipel.stc Bentley Systems. Inc. Haestad Methods Solution Bentley StormCAD V8 XM Edition Center [08.09.081.00] 9/22/200B . 27 Siemon Company Drive Suite 200 W Watertown, Page 1 of 1 CT 06795 USA +1 -203- 755 -1666 CB-3 P -3 Bentley Systems, Inc. Haestad Methods Solution Pipe2.stc Center 27 Siemon Company Drive Suite 200 W 9122/2008 Watertown, CT 06795 USA +1- 203 - 755 -1666 - Tie In 0 a T N c7 Z w 0 Bentley StormCAD V8 XM Edition [08.09.081.00) Page 1 of 1 1 ' Calculation Detailed Summary (CB -3, CB-4, P -3 AND P-4) Element Details ' ID 13 Notes Label Base Calculation Options ' Hydraulic Summary Flow Profile Method Backwater Analysis Average Velocity Method Actual Uniform Flow Velocity Number of Flow Profile 5 Minimum Structure 0.00 ft Steps Headloss Hydraulic Grade 0.001 ft 5.000 min Convergence Test ' Inlets Neglect Side Flow? FALSE Active Components for Grate and Curb ' Combination Inlets In Sag Neglect Gutter Cross TRUE Active Components for Grate and Curb Slope For Side Flow? ' Combination Inlets on Grade HEC -22 Elevations Considered 0.5 ft 1 ' Equal Within Consider Non -Piped False Half Bench Submerged 0.95 Plunging Flow ' Flat Submerged 1 0.15 Flat Unsubmerged 1 0.75 ' Depressed Submerged 1 0.07 AASHTO Expansion, Ke 0.35 0.5 Contraction, Kc 0.25 1.3 1 1 1 1 1 Bend Angle vs. Bend Loss Curve Generic Structure Loss Governing Upstream Pipe Pipe with Maximum QV Selection Method i 1 1 1 f� 1 1 1 1 1 1 1 1 1 1 1 1 1 Catchment Summary Conduit Summary l abet r orrduitbee p ' C °ndurt Shape ��randi } 5 bne a t�tifiai aw IN P -3 Circular Pipe - 12.0 Circular Pipe In 0.9 in P-4 Circular Pipe - 12.0 Circular Pipe JlTi In 1.8 in Node Summary Inlet Summary Pipe2.stc Bentley Systems, Inc. Haestad Methods Solution Bentley StormCAD VS XM Edition Center [08.09.081.00) 9/22/2008 27 Siemon Company Drive Suite 200 W Watertown, Page 1 of 1 CT 06795 USA +1- 203 - 755 -1666 1 1 �i s