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Home My WebLink AboutSDP 2020-0005; CHILDREN'S PARADISE; DRAINAGE REPORT; 2020-05-26DRAINAGE REPORT FOR THE PRESERVE AT QUARRY CREEK 3335 MARRON ROAD (SDP TBD, GR TBD, Drawing No. TBD) May 26, 2020 Wayne W. Chang, MS, PE 46548 Civil Engineering O Hydrology O Hydraulics O Sedimentation P.O. Box 9496 Rancho Santa Fe, CA 92067 (858) 692-0760 FOR REVIEW ONLY NOV v 5 2020 c r:-y Or CARLSBA ~-. ,✓.i G Dl /I k . .,. J TABLE OF CONTENTS Introduction ........................................................................................................................................ I Hydrologic and Hydraulic Analyses .................................................................................................. 2 Conclusion ......................................................................................................................................... 3 APPENDICES A. 100-Year Rational Method Analyses and Supporting Data - .. -.. .. ----- -FOR REVIEW ONLY ... .. -.. ... • -.. ... - .. -- INTRODUCTION The Preserve at Quarry Creek project is located at 3335 Marron Road in the city of Carlsbad (see the Vicinity Map). The site covers 2.12 acres. The southerly portion of the site contains a manufactured 2:1 slope that was created by the past South Coast Materials Quarry mining operation. The northerly portion of the site contains a development pad that was graded as part of the quarry reclamation and slopes gently towards the northwest. The manufactured slope extends above the property boundary and is approximately 160-foot high near the site. The slope contains concrete terrace ditches and down drains that convey storm runoff to the bottom of the slope. One of the down drains outlets onto the pad and contains a tributary area just over 2 acres. The combined slope and pad runoff flows into a bioretention basin at the northwest comer of the pad. Storm runoff is conveyed out of the bioretention basin by a public underground storm drain that continues west along Marron Road and then north along El Saito Flats Street to Buena Vista Creek. PACIFIC OCEAN CITY or ENCINITAS Vicinity Map NOT TO SCALE or N MARCOS -- ... • • ------- The site will be developed into a Children's Paradise Preschool and Infant Center. The project will support the preschool building, a parking lot, and yard areas. The existing bioretention basin will be upgraded to a biofiltration basin for pollutant and flow control. This report contains pre- ( existing condition) and post-project (proposed condition) 100-year hydrologic analyses for the site. The grading plan has been prepared by ACAL Engineering & Surveying, Inc. HYDROLOGIC AND HYDRAULIC ANALYSES Hydro logic analyses were performed to determine the 100-year flow rates under pre-and post- project conditions. The County of San Diego's 2003 Hydrology Manual rational method procedure was used for the 100-year hydro logic analyses. The rational method input parameters are summarized below and the supporting data is included in Appendix A: • Precipitation: The 100-year, 6-and 24-hour precipitation values are 2.90 and 5.10 inches, respectively. • Drainage areas: The drainage basins were delineated from the base topography prepared for the project and the grading plan by ACAL Engineering & Surveying. The existing and proposed condition overall drainage basins were set equal to allow a comparison of results. • Hydrologic soil groups: The hydrologic soil groups were determined from the Natural Resources Conservation Service's (NRCS) Web Soil Survey. The soil group in the majority of the project site is designated as gravel pits. This was assigned to soil group D since the geotechnical engineer determined the site is not subject to full or partial infiltration. A portion of the hillside is in soil group C . • Runoff coefficients: The runoff coefficients were based on the ex1stmg and proposed condition impervious percentages outlined in the County Hydrology Manual. Under existing conditions, the overall drainage area is essentially pervious, so the undisturbed natural terrain category was assumed. Under proposed conditions, the hillside area is pervious, so the undisturbed natural terrain category was assumed. The SWQMP determined that the development pad will be approximately 50 percent impervious, so the medium density residential (14.5 DU/A or less) category was assumed. For drainage subbasins containing both soil group C and D, the percentage of each soil group was determined and used. • Flow lengths and elevations: The flow lengths and elevations were obtained from the base topography and engineering plans. 2 .. .. .. -- .. .. • ... .. -·--·---- """' Table 1 summarizes the 100-year rational method results. The table indicates that the project will cause a 3.5 cfs increase in the 100-year flow rate. This increase is allowable because the receiving storm drain system was designed assuming the site is developed . Condition C I, in/hr A, ac Q100, cfs Existing (Node 20) 0.33 6.43 3.50 7.5 Proposed (Node 38) 0.44 7.12 3.50 10.9 Table 1. Rational Method Analyses The on-site storm drain system is private. Normal depth hydraulic analyses for preliminary sizing of the private storm drain pipes are provided by the "pipeflow" routines in the proposed condition CivilDesign Rational Method output. This is the typical procedure for private storm drain pipes. The private storm drains will be designed based on normal depth results and refined in a subsequent submittal. For proposed condition nodes 32 to 22, the tributary drainage area of 0.55 acres was added at the beginning rather than end of the pipe in order to conservatively size the pipe. CONCLUSION Hydrologic and hydraulic analyses have been performed for the Children's Paradise Preschool and Infant Center proposed at The Preserve at Quarry Creek -3335 Marron Road. The analyses were based on the grading plan by ACAL Engineering & Surveying, Inc. The project will increase the 100-year flow rate, but the receiving storm drain system was designed to accommodate the developed site, so detention is not required . 3 ... - - -------- ,. .. .. -.. .. ---... .. ... APPENDIX A 100-YEAR RATIONAL METHOD ANALYSES AND SUPPORTING DATA I I I I I I I I I I I I I J 1" = 50' ~ 0 50 LEGEND: DRAINAGE BASIN BOUNDARY --OVERLAND FLOW PATH 3.62 AC DRAINAGE BASIN AREA (I[] RATIONAL METHOD NODE NUMBER @ HYDROLOGIC SOIL GROUP I EXISTING CONDITION RATIONAL METHOD WORK MAP 7 I I M}\RRON ROAD -_/_ I 1.40 AC X147.7 -7.9 ---------- X 146.8 144.S-------- X144 9-- X'44.7 ---- X 147.4 / / / X 149.0 X 149.( X148.6 X149.0 V 149.4 150.6 X ~ ----u P,_L - ~ - I I I I I I I I J 1" = 50' ~ 0 50 LEGEND: DRAINAGE BASIN BOUNDARY --OVERLAND FLOW PATH PROPOSED DRAINAGE FACILITY 3.62 AC DRAINAGE BASIN AREA (IQ] RATIONAL METHOD NODE NUMBER @ HYDROLOGIC SOIL GROUP ( PROPOSED CONDITION RATIONAL METHOD WORK MAP 7 I MARRON ROAD -_, ...,..- --- X147.7 -7.9 X 146.8 X 147.4 1445~ X144.9.__ '>(144.7 ---- (_ I I I ---= _.._,_ -- X 147.6 ,-- X149.( x 148.6 X 149.0 ~---- v 149.4 150.6 X \___J 'p._-2 -- ' 1- 1 ,. I \ \ \ \ I \ I,,\ ~ 1--. 'r-.... I"-.... ' .._"'r--,. 10.0 9.0 8.0 70 "'-.... , .... ...... ... ....... ·, I ""'I ~ ......... 6.0 I . 5.0 I..._ '-........ ~ .i:::: vi Q) .i:::: 4.0 I 3.0 I 2.0 I g 1.0 ~0.9 -~0.8 ~0.7 0.6 05 : ' 04 I 0.3 l 0.2 ! 0.1 r-...., " . ' .......... r-.... " I -· - ~ 1--+-'- i r 5 6 ...... ' .... r-.... .... .... .... r-....r--. .... ..... "11111 11111 ..... .... ... "-r-.. .... .... ' r-.... "i-.. .... .... , ... ""r-.... r-.... i'o...._ 7 8 9 10 I'-. r--. '"', "'i,. • I'-. .. '"' .. .. " "" .. i-.,. .... , • .... ,, .... .. "' l'oi,. 1111 .. i... .. " ~ .. Iii, " ~ ~ .. . . ~ "i-. ~ .. .. ~ ~ .. .. i'o.i', l',i', .. "'i,. • i'o. "' "" .. .. 1 .... "'i,. .. ""t--. .. ""' ~ "'i--i-." .. 15 20 30 Minutes .. " "/" ~ .. " .. ...... " .... ~ . "'" "'~ " ~~ .. 40 50 Duration EQUATION I = 7.44 P6 D-0-645 I = Intensity (in/hr) P6 = 6-Hour Precipitation (in) D = Duration (min) "r-.. ... ........ r-,..r-. r-.... r-.... r-. ' " r-.. r-...." .. r-. r-..r-. ""Iii .. Iii "i-.. r--. ... r-..r-. 1, r-. r-....r-.. ,.... r-. 2 "', 'I" 1 .. "' "', "' .... I• "', ,..,.. ~ ~ "r-. ,.. ,.... ~ I• I""' "' ~ "' -.. I• "'r,. l•r,. -"'" ""' 3 Hours ~ ~ ~ " ~ .. ~ 4 5 6 a, ± g ... "Cl al n 6.0 "§: 5.5 i 5.0 g· 4.5 5" n 4.0 il 3.5 ~ 3.0 2.5 2.0 1.5 1.0 Intensity-Duration Design Chart -Template Directions for Appllcatlon: (1) From precipitation maps determine 6 hr and 24 hr amounts for the selected frequency. These maps are included in the County Hydrology Manual (10, 50, and 100 yr maps included in the Design and Procedure Manual). (2) Adjust 6 hr precipitation (if necessary) so that it is within the range of 45% to 65% of the 24 hr precipitation (not applicaple to Desert). (3) Plot 6 hr precipitation on the right side of the chart. (4) Draw a line through the point parallel to the plotted lines. (5) This line is the intensity-duration curve for the location being analyzed. Appllcatlon Fonn: (a) Selected frequency ....!.QQ:_ year p (b) p6 = 2.9 in. p24 = 5.1 ___§_ = 56.9 %(2) --' --'P24 -- (c) Adjusted p6(2l = ~ in. (d) tx = ___ min. See rational method calculations (e) 1 = ___ in./hr. for Tc and I. Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. P6 7 1 l 1.sn12.s7 3 T 3.ti • + 4.5 5 --,... 5.5 1 & ;Duration t I 1 1,1--.-r-r 111 ' I I I I t I I 7 6.59 7.90 9.22 10.54~11.86 13.17 14.49 15.81 ________ ....., ___ _,_ 8.48 i 9.54 [10.60 11.66 12.72 1 .74 7.58j_8.42 9.27 10.11 1 .19 5.84 6.49 7.13 7.78 5.93 6.46 3.73 4.20 4.67 5.13 5.60 30 1.24 1.66 2.07 2.49 2.90 3.32t 3.73 4.15 4.56 4 98 40 1.03 1.38 1.72 2.07 2.41 2.76 3.10 3.45 3.79i 4.13 50 0.90 1.19 1.49 1_;_79 2.09 2.39 2.69 l 2.98t 3.28 3.58 60 0.80 1.06 . 1.33 1 .59 1.86 2.12 2.39 2.65 2.92 3. 18 I 90 o.61 o.82 1.02 123 1.43 1.63 1.84n 2.04 2.25 2.45 120 0.51 0.68 0.85 1.02 1.19 1.36 1.53 1.70 1.87 2.04 150 0.44 0.59 0.73 0.88 1.03 1. 18 1.32 1.47\t i .62 _j_ 1.76 180 0. 0.91 1.04 1.18 1.31 t.44..J_1.57 2.40 0.33 0.43 0.54 0.65 0.76 0.87 0.98 1.08 1.19 1.30 300 ..Q.,19 0.28 0.38 0.47 0.56 0.66 0.75 Q_.85~.94 1.03 1.13 380 0.17 0.25 0.33 0.42 0.50 0.58 0.67 0.75 I 0.84 0.92 1.00 F I GU R E @] 330->n!.. 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'--4 1.ru,ntv ·· :.-.,... •d C nty ·-·· · p.: 33•15 I 'ii;.•.: --ti \SI (l 0 ('I ~ OJ -:, .: :'.(.: _; Rivers, e ou . . . . --... ••---:-.; ..:-.___ ·--..:-,._ · .. ·-.._ · .. _ ~:< .-··· .if I '\. i -._ "-' • .' ,• I J .:~ •• _,..-___ "'Q __ .• -···... . . -. . -. .,-.... :· ·-.. ., ··-... • -.. -· -· -. .. ·r·--· :J. ... :-.... ·--s~ .. ~---· -· -. --. --s ·-J. --·:::.--·---=---: .. ·-.. \& ___ ........ .-~.: ':\ '·-.. ·-.:----!;-0. ····:::.-·· ___ \• .. ·-.::.-.:.:<i·•· ..... ·• ... ____ - '"00' 3 "O (I) "" §I () 0 C .¾ ~~ 1~' ' · \f ;) '\<~1< \ ~ .. ,r., I ,·,:-. . ·~ ~ ~ )<,.' , ~/ ; . \/:;;: 'xli·s t¥) ·.•·~~ t i .. ...-->~~:r;<----\., . .:: ___ .... _.... -----+ MeX 32°3a 32'30' ~ "' 8 ' > ' ~ I t g • + ~ ,_ ll. ll. ~ t 1o t-1o r :: :: > :: + I r r County of San Diego Hydrology Manual • Rainfall Isopluvials 100 Year Rainfall Event -24 Hours lsopluvial (Inches) P24=5.1" DPW *GIS ~ S~GIS ~~=-').•'.! H.t-... \Jr. l '►.q:u < ·m ... rui! N nelW#■~WrTHOI.ITWAMNtr'fOIFNlrlOHD,lmEREllfl'I' + °"-.""·"""""""""'"""'""°"'""_,..w_..,.., O,MElll(:HNi1'AIII.J1'rNIOFfflri£SSFOlll.t.l"IUfflCl&Nl~ s ~s.,as,,.,..,..,...,..,.., n...--... ~ .............. &IIHCWI~ _.....,.....,._...,.__.....,. ... _,.......~. n.~..,__,.........,wNdl._.,_,.....,__ ~...-.. n-.......... 3 0 3 MIies ~ San Diego County Hydrology Manual Date: June 2003 Table 3-1 Section: Page: RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use I Runoff Coefficient "C" Soil Type NRCS Elements Coun Elements % IMPER. A B Undisturbed Natural Terrain (Natural) Permanent Open Space 0* 0.20 0.25 Low Density Residential (LOR) Residential, 1.0 DU/A or less 10 0.27 0.32 Low Density Residential (LOR) Residential, 2.0 DU/A or less 20 0.34 0.38 Low Density Residential (LOR) Residential, 2.9 DU/A or less 25 0.38 0.41 Medium Density Residential (MOR) Residential, 4.3 DU/A or less 30 0.41 0.45 Medium Density Residential (MOR) Residential, 7.3 DU/A or less 40 0.48 0.5 1 Medium Density Residential (MOR) Residential, 10.9 DU/A or less 45 0.52 0.54 Medium Density Residential (MOR) Residential, 14.5 DU/A or less 50 0.55 0.58 High Density Residential (HOR) Residential, 24.0 DU/A or less 65 0.66 0.67 High Density Residential (HOR) Residential, 43.0 DU/A or less 80 0.76 0.77 Comm ercial/Industrial (N. Com) Neighborhood Commercial 80 0.76 0.77 Commercial/Industrial (G. Com) General Commercial 85 0.80 0.80 Commercial/Industrial (O.P. Com) Office Professional/Commercial 90 0.83 0.84 Commercial/Industrial (Limited I.) Limited Industrial 90 0.83 0.84 Commercial/Industrial (General I.) General Industrial 95 0.87 0.87 C 0.30 0.36 0.42 0.45 0.48 0.54 0.57 0.60 0.69 0.78 0.78 0.81 0.84 0.84 0.87 3 6 of26 D 0.35 0.41 0.46 0.49 0.52 0.57 0.60 0.63 0.71 0.79 0.79 0.82 0.85 0.85 0.87 *The values associated with 0% impervious may be used for direct calculation of the runoff coefficient as described in Section 3.1.2 (representing the pervious runoff coefficient, Cp, for the soil type), or for areas that will remain undisturbed in perpetuity. Justification must be given that the area will remain natural forever (e.g., the area is located in Cleveland National Forest). DU/A = dwelling units per acre NRCS = National Resources Conservation Service 3-6 Gj UJ u... z UJ (.) z <{ ..... (/) 0 w (/) 0:: ::> 0 (.) O'.'. UJ ..... <{ ~ ,ool Yrr ope §U/J ~ ✓ I ✓I ..,.,., 130 Cl) UJ ..... ::> z 0 20 ~ z UJ ~ ~ ~ 0 ....J u. 0 z :5 0:: UJ > 0 ---0 EXAMPLE: Given: Watercourse Distance (D) = 70 Feet Slope (s) = 1.3% Runoff Coefficient (C) = 0.41 Overland Flow Time (T) = 9.5 Minutes T = 1.8 (1.1-C) VD 3'fs SOURCE: Airport Drainage, Federal Aviation Administration, 1965 F IG U R E Rational Formula -Overland Time of Flow Nomograph 3-3 33" 10'47'N 33" 10'31"N ~ ~ !il ~ § ~ § ~ I I i ,: !::i ~ s 471700 471700 ,: !::i !-. s N A Hydrologic Soil Group-San Diego County Area, California 471770 4718<0 471910 471!Bl 4721B) 4721:!J 471770 4718<0 471910 471!Bl 4721B) 4721:!J Map Scale: 1:3,330 f printed CJ1 A landscape (11" X 8.5") sheet ----======--------========Meters o ~ ro m m ----=====--------========fffl 0 150 :m 8ll 00) Map prujecron: Web "'1ert:ator Comer coordinates: WGS84 Edge tx:s: lJTM l.one llN WGS84 USDA Natural Resources Web Soil Survey National Cooperative Soil Survey -a Conservation Service 41ZBJ 47ml 472100 47ZHl 47ml 472<m 47240 ,: ~ !:; s ,: ~ !:; s § !ii ~ ~ § ~ § ~ I I i 3/4/2020 Page 1 of 4 33" 10'47'N 33" 10'31"N Hydrologic Soil Group-San Diego County Area, California MAP LEGEND MAP INFORMATION Area of Interest (AOI) LJ Area of Interest (AOI) Soils Soil Rating Polygons D A D AID DB D BID DC D CID DD D Not rated or not available Soil Rating Lines A AID -B -BID C CID D ~ • Not rated or not available Soil Rating Points Cl A Cl AID ■ B ■ BID USDA Natural Resources --Conservation Service Cl l!I C CID ■ D □ Not raled or not available Water Features Streams and Canals Transportation H-t Rails -Interstate Highways -US Routes Major Roads Local Roads Background • Aerial Photography Web Soil Survey National Cooperative Soil Survey The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: San Diego County Area, California Survey Area Data: Version 14, Sep 16, 2019 Soil map units are labeled (as space allows) for map scales 1 :50,000 or larger. Date(s) aerial images were photographed: Nov 3, 2014-Nov 22,2014 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. 3/4/2020 Page 2 of 4 Hydrologic Soil Group-San Diego County Area, California Hydrologic Soil Group Map unit symbol Map unit name Rating CmrG Cieneba very rocky D coarse sandy loam, 1 30 to 75 percent slopes Dao Diablo clay, 9 to 15 C ➔•=ot slopes,••~ MAAT l oaE2 blo clay, 15 to 30 C percent slopes, eroded, warm MAAT FeE2 Fallbrook rocky sandy C loam, 9 to 30 percent l slopes, eroded GP Gravel pits -+- LsE Linne clay loam, 9 to 30 C percent slopes Totals for Area of Interest USDA Natural Resources -aa Conservation Service Web Soil Survey National Cooperative Soil Survey Acres In AOI 4.2 4.2 1 13.7 --+--1.6 16.0 I 0.5 40.3 Percent of AOI 10.3% 10.5% 34.1% 4.1% i 39.8% 1.2% 100.0% --- 3/4/2020 Page 3 of 4 -----.. --- ----------- .. - ... -.. Hydrologic Soil Group-San Diego County Area, California Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (AID, 8/0, and C/D). The groups are defined as follows: Group A Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (AID, 8/D, or C/0), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes . Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher USDA Natural Resources ~iiiii Conservation Service Web Soil Survey National Cooperative Soil Survey 3/4/2020 Page 4 of 4 - ---- -- --- --- • ----.. ----- San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software, (c)1991-2009 Version 7.8 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 05/26/20 The Preserve at Quarry Creek 3335 Marron Road Existing Conditions 100-Year Storm Event ********* Hydrology Study Control Information********** Program License Serial Number 4028 Rational hydrology study storm event year is English (in-lb) input data Units used Map data precipitation entered: 6 hour, precipitation(inches) = 2.900 24 hour precipitation(inches) = 5.100 P6/P24 = 56.9% San Diego hydrology manual 'C' values used 100.0 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 10.000 to Point/Station 12.000 **** INITIAL AREA EVALUATION**** Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [UNDISTURBED NATURAL TERRAIN (Permanent Open Space ) Impervious value, Ai= 0.000 Sub-Area C Value= 0.300 0.000 0.000 1.000 0.000 Initial subarea total flow distance 61.000(Ft.) Highest elevation= 259.l00(Ft.) Lowest elevation= 229.200(Ft.) Elevation difference 29.900(Ft.) Slope= 49.016 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 100.00 (Ft) for the top area slope value of 49.02 %, in a development type of Permanent Open Space In Accordance With Figure 3-3 • - • --- • • Initial Area Time of Concentration= 3.93 minutes TC= [l.8*(1.l-C)*distance(Ft.)A.5)/(% slopeA(l/3)] TC= [l.8*(1.1-0.3000)*( 100.000A.5)/( 49.016A(l/3)]= 3.93 Calculated TC of 3.935 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 7.64l(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.300 Subarea runoff= 0.138(CFS) Total initial stream area= 0.060(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 12.000 to Point/Station 14.000 **** IMPROVED CHANNEL TRAVEL TIME**** Upstream point elevation= 229.200(Ft.) Downstream point elevation 216.000(Ft.) Channel length thru subarea 296.000(Ft.) Channel base width 0.500(Ft.) Slope or 'Z' of left channel bank= Slope or 'Z' of right channel bank= 2.000 2.000 Estimated mean flow rate at midpoint of channel Manning's 'N' = 0.016 Maximum depth of channel l.000(Ft.) Flow(q) thru subarea = 0.585(CFS) Depth of flow= 0.160(Ft.), Average velocity Channel flow top width= l.14l(Ft.) Flow Velocity= 4.45(Ft/s) Travel time 1.11 min. Time of concentration= 5.04 min. Critical depth= 0.250(Ft.) Adding area flow to channel Rainfall intensity (I) = Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [UNDISTURBED NATURAL TERRAIN (Permanent Open Space ) Impervious value, Ai= 0.000 Sub-Area C Value= 0.300 7.598(In/Hr) for a 0.000 0.000 1.000 0.000 0.585(CFS) 4.449(Ft/s) 100.0 year storm Rainfall intensity= 7.598(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.300 CA= 0.135 Subarea runoff= 0.888(CFS) for 0.390(Ac.) Total runoff= l.026(CFS) Total area= 0.450(Ac.) Depth of flow= 0.213(Ft.), Average velocity= 5.186(Ft/s) Critical depth= 0.336(Ft.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 14.000 to Point/Station 16.000 2 - - **** IMPROVED CHANNEL TRAVEL TIME**** Upstream point elevation= 216.000(Ft.) Downstream point elevation 139.000(Ft.) Channel length thru subarea = 185.000(Ft.) Channel base width 0.500(Ft.) Slope or 'Z' of left channel bank= Slope or 'Z' of right channel bank= 2.000 2.000 Estimated mean flow rate at midpoint of channel Manning's 'N' = 0.016 Maximum depth of channel 1.000(Ft.) Flow(q) thru subarea = 2.993(CFS) Depth of flow= 0.209(Ft.), Average velocity Channel flow top width= l.334(Ft.) Flow Velocity= 15.65(Ft/s) Travel time 0.20 min. Time of concentration= 5.24 min. Critical depth= 0.563(Ft.) Adding area flow to channel Rainfall intensity (I) = Decimal fraction soil group A 7.412(In/Hr) 0.000 Decimal fraction soil group B 0.000 Decimal fraction soil group C = 0.428 Decimal fraction soil group D 0.572 [UNDISTURBED NATURAL TERRAIN (Permanent Open Space ) Impervious value, Ai= 0.000 Sub-Area C Value= 0.329 for a 2.993(CFS) 15.65l(Ft/s) 100.0 year storm Rainfall intensity= 7.412(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.322 CA= 0.677 Subarea runoff= 3.994(CFS) for 1.650(Ac.) Total runoff= 5.020(CFS) Total area= 2.l00(Ac.) Depth of flow= 0.269(Ft.), Average velocity= 17.957(Ft/s) Critical depth= 0.715(Ft.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 16.000 to Point/Station 18.000 **** IMPROVED CHANNEL TRAVEL TIME**** Upstream point elevation= 139.000(Ft.) Downstream point elevation 130.000(Ft.) Channel length thru subarea 250.000(Ft.) Channel base width 0.500(Ft.) Slope or 'Z' of left channel bank= 5.000 Slope or 'Z' of right channel bank= 5.000 Estimated mean flow rate at midpoint of channel Manning's 'N' = 0.040 Maximum depth of channel 1.000(Ft.) Flow(q) thru subarea = 6.285(CFS) Depth of flow= 0.578(Ft.), Average velocity 3 6.285(CFS) 3.205(Ft/s) - - --.. ... Channel flow top width= 6.283(Ft.) Flow Velocity= 3.20(Ft/s) Travel time 1.30 min. Time of concentration= 6.54 min. Critical depth= 0.582(Ft.) Adding area flow to channel Rainfall intensity (I) = Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [UNDISTURBED NATURAL TERRAIN (Permanent Open Space ) Impervious value, Ai= 0.000 Sub-Area C Value= 0.349 6.425(In/Hr) for a 0.000 0.000 0.014 0.986 100.0 year storm Rainfall intensity= 6.425(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.333 CA= 1.166 Subarea runoff= 2.473(CFS) for l.400(Ac.) Total runoff= 7.493(CFS) Total area= 3.500(Ac.) Depth of flow= 0.62l(Ft.), Average velocity= 3.349(Ft/s) Critical depth= 0.625(Ft.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 18.000 to Point/Station 20.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** Upstream point/station elevation= 124.450(Ft.) Downstream point/station elevation 122.500(Ft.) Pipe length 30.00(Ft.) Slope 0.0650 Manning's N 0.013 No. of pipes= 1 Required pipe flow 7.493(CFS) Nearest computed pipe diameter 12.00(In.) Calculated individual pipe flow 7.493(CFS) Normal flow depth in pipe= 8.3l(In.) Flow top width inside pipe= ll.08(In.) Critical depth could not be calculated. Pipe flow velocity= 12.92(Ft/s) Travel time through pipe 0.04 min. Time of concentration (TC) 6.58 min. End of computations, total study area= 3.500 (Ac.) 4 .. ... -.. .. .... - ----.. San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software, (c)1991-2009 Version 7.8 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 05/26/20 The Preserve at Quarry Creek 3335 Marron Road Proposed Conditions 100-Year Storm Event ********* Hydrology Study Control Information********** Program License Serial Number 4028 Rational hydrology study storm event year is English (in-lb) input data Units used Map data precipitation entered: 6 hour, precipitation(inches) = 2.900 24 hour precipitation(inches) = 5.100 P6/P24 = 56.9% San Diego hydrology manual 'C' values used 100.0 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 10.000 to Point/Station 12.000 **** INITIAL AREA EVALUATION**** Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [UNDISTURBED NATURAL TERRAIN (Permanent Open Space ) Impervious value, Ai= 0.000 Sub-Area C Value= 0.300 0.000 0.000 1.000 0.000 Initial subarea total flow distance 61.000(Ft.) Highest elevation= 259.l00(Ft.) Lowest elevation= 229.200(Ft.) Elevation difference 29.900(Ft.) Slope= 49.016 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 100.00 (Ft) for the top area slope value of 49.02 %, in a development type of Permanent Open Space In Accordance With Figure 3-3 .. --- - - - -- "' - .. --- Initial Area Time of Concentration= 3.93 minutes TC= [1.8*(1.l-C)*distance(Ft.)A.5)/(% slopeA(l/3)] TC= [1.8*(1.1-0.3000)*( 100.000A.5)/( 49.016A(l/3)]= 3.93 Calculated TC of 3.935 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 7.64l(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.300 Subarea runoff= 0.138(CFS) Total initial stream area= 0.060(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 12.000 to Point/Station 14.000 **** IMPROVED CHANNEL TRAVEL TIME**** Upstream point elevation= 229.200(Ft.) Downstream point elevation 216.000(Ft.) Channel length thru subarea 296.000(Ft.) Channel base width 0.500(Ft.) Slope or 'Z' of left channel bank= Slope or 'Z' of right channel bank= 2.000 2.000 Estimated mean flow rate at midpoint of channel Manning's 'N' = 0.016 Maximum depth of channel 1.000(Ft.) Flow(q) thru subarea = 0.585(CFS) Depth of flow= 0.160(Ft.), Average velocity Channel flow top width= 1.14l(Ft.) Flow Velocity= 4.45(Ft/s) Travel time 1.11 min. Time of concentration= 5.04 min. Critical depth= 0.250(Ft.) Adding area flow to channel Rainfall intensity (I) = Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [UNDISTURBED NATURAL TERRAIN (Permanent Open Space ) Impervious value, Ai= 0.000 Sub-Area C Value= 0.300 7.598(In/Hr) for a 0.000 0.000 1.000 0.000 0.585(CFS) 4.449(Ft/s) 100.0 year storm Rainfall intensity= 7.598(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.300 CA= 0.135 Subarea runoff= 0.888(CFS) for 0.390(Ac.) Total runoff= 1.026(CFS) Total area= 0.450(Ac.) Depth of flow= 0.213(Ft.), Average velocity= 5.186(Ft/s) Critical depth= 0.336(Ft.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 14.000 to Point/Station 16.000 2 ... .. .. --- ... - -- ... ... ... .. --... - **** IMPROVED CHANNEL TRAVEL TIME**** Upstream point elevation= 216.000(Ft.) Downstream point elevation 142.000(Ft.) Channel length thru subarea 180.000(Ft.) Channel base width 0.500(Ft.) Slope or 'Z' of left channel bank= Slope or 'Z' of right channel bank= 2.000 2.000 Estimated mean flow rate at midpoint of channel Manning's 'N' = 0.016 Maximum depth of channel 1.000(Ft.) Flow(q) thru subarea = 2.893(CFS) 2.893(CFS) Depth of flow= 0.206(Ft.), Average velocity 15.438(Ft/s) Channel flow top width= 1.323(Ft.) Flow Velocity= 15.44(Ft/s) Travel time 0.19 min. Time of concentration= 5.24 min. Critical depth= 0.555(Ft.) Adding area flow to channel Rainfall intensity (I) = Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [UNDISTURBED NATURAL TERRAIN 7.415(In/Hr) for a 0.000 100.0 year storm 0.000 0.452 0.548 (Permanent Open Space ) Impervious value, Ai= 0.000 Sub-Area C Value= 0.327 Rainfall intensity= 7.415(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.321 CA= 0.649 3.787(CFS) for 1.570(Ac.) Subarea runoff= Total runoff= Depth of flow= Critical depth= 4.812(CFS) Total area= 2.020(Ac.) 0.265(Ft.), Average velocity= 17.678(Ft/s) 0. 703 (Ft.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 16.000 to Point/Station 18.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** Upstream point/station elevation= 131.000(Ft.) Downstream point/station elevation 129.000(Ft.) Pipe length 106.00(Ft.) Slope 0.0189 Manning's N 0.013 No. of pipes= 1 Required pipe flow 4.812(CFS) Nearest computed pipe diameter 12.00(In.) Calculated individual pipe flow 4.812(CFS) Normal flow depth in pipe= 9.66(In.) Flow top width inside pipe= 9.51(In.) Critical Depth= 10.88(In.) Pipe flow velocity= 7.l0(Ft/s) Travel time through pipe= 0.25 min. 3 -- --- - • - -- Time of concentration (TC) 5.49 min. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 20.000 to Point/Station 18.000 **** SUBAREA FLOW ADDITION**** Rainfall intensity (I) = Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [UNDISTURBED NATURAL TERRAIN (Permanent Open Space ) Impervious value, Ai= 0.000 Sub-Area C Value= 0.350 7.196(In/Hr) for a 0.000 0.000 0.000 1.000 Time of concentration= 5.49 min. 100.0 year storm Rainfall intensity= 7.196(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.323 CA= 0.684 Subarea runoff 0.ll0(CFS) for 0.l00(Ac.) Total runoff= 4.922(CFS) Total area= 2.120(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 18.000 to Point/Station 22.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** Upstream point/station elevation= 129.000(Ft.) Downstream point/station elevation 124.450(Ft.) Pipe length 66.00(Ft.) Slope 0.0689 Manning's N No. of pipes= 1 Required pipe flow 4.922(CFS) Nearest computed pipe diameter 12.00(In.) Calculated individual pipe flow 4.922(CFS) Normal flow depth in pipe= 6.19(In.) Flow top width inside pipe= 11.99(In.) Critical Depth= 10.95(In.) Pipe flow velocity= 12.06(Ft/s) Travel time through pipe= 0.09 min. Time of concentration (TC) = 5.58 min. 0.013 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 18.000 to Point/Station 22.000 **** CONFLUENCE OF MAIN STREAMS**** The following data inside Main Stream is listed: In Main Stream number: 1 Stream flow area= 2.120(Ac.) Runoff from this stream 4.922(CFS) Time of concentration Rainfall intensity= 5.58 min. 7.120(In/Hr) 4 ----- -- ---.. .. ... .. .. .. - .. -- Program is now starting with Main Stream No. 2 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 30.000 to Point/Station 32.000 **** INITIAL AREA EVALUATION**** Decimal fraction soil group A 0.000 Decimal fraction soil group B 0.000 Decimal fraction soil group C 0.000 Decimal fraction soil group D 1. 000 [MEDIUM DENSITY RESIDENTIAL (14.5 DU/A or Less ) Impervious value, Ai = 0.500 Sub-Area C Value= 0.630 Initial subarea total flow distance 55.000(Ft.) Highest elevation= 146.000(Ft.) Lowest elevation= 140.000(Ft.) Elevation difference 6.000(Ft.) Slope= 10.909 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 100.00 (Ft) for the top area slope value of 10.91 %, in a development type of 14.5 DU/A or Less In Accordance With Figure 3-3 Initial Area Time of Concentration TC= [l.8*(1.l-C)*distance(Ft.)A.5)/(% TC= [l.8*(1.1-0.6300)*( 100.000A.5)/( 3.81 minutes slopeA(l/3)] 10.909A(l/3)]= Calculated TC of 3.815 minutes is less than 5 minutes, 3.81 resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 7.64l(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.630 Subarea runoff= 0.24l(CFS) Total initial stream area= 0. 050 (Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 32.000 to Point/Station 22.000 **** SUBAREA FLOW ADDITION**** Calculated TC of 3.815 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 7.64l(In/Hr) for a 100.0 year storm Decimal fraction soil group A 0.000 Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [MEDIUM DENSITY RESIDENTIAL (14.5 DU/A or Less ) Impervious value, Ai= 0.500 Sub-Area C Value= 0.630 0.000 0.000 1.000 Time of concentration Rainfall intensity= 3.81 min. 7.64l(In/Hr) for a 5 100.0 year storm - - ---- - - ---- - Effective runoff coefficient used for total area (Q=KCIA) is C = 0.630 CA= 0.378 Subarea runoff= 2.648(CFS) for 0.550(Ac.) Total runoff= 2.888(CFS) Total area= 0.600(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 32.000 to Point/Station 22.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** Upstream point/station elevation= 138.740(Ft.) Downstream point/station elevation 134.000(Ft.) Pipe length 460.00(Ft.) Slope 0.0103 Manning's N 0.013 No. of pipes= 1 Required pipe flow 2.888(CFS) Nearest computed pipe diameter 12.00(In.) Calculated individual pipe flow = 2.888(CFS) Normal flow depth in pipe= 8.ll(In.) Flow top width inside pipe= ll.23(In.) Critical Depth= 8.75(In.) Pipe flow velocity= 5.ll(Ft/s) Travel time through pipe= 1.50 min. Time of concentration (TC) = 5.31 min. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 34.000 to Point/Station 22.000 **** SUBAREA FLOW ADDITION**** Rainfall intensity (I) = Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [MEDIUM DENSITY RESIDENTIAL (14.5 DU/A or Less Impervious value, Ai= 0.500 Sub-Area C Value= 0.600 7.347(In/Hr) for a 0.000 0.000 1.000 0.000 Time of concentration= 5.31 min. 100.0 year storm Rainfall intensity= 7.347(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.615 CA= 0.744 Subarea runoff 2.578(CFS) for 0.610(Ac.) Total runoff= 5.466(CFS) Total area= l.210(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 36.000 to Point/Station 22.000 **** CONFLUENCE OF MAIN STREAMS**** The following data inside Main Stream is listed: In Main Stream number: 2 Stream flow area= l.210(Ac.) 6 --... ---- - ---- ... -------• Runoff from this stream Time of concentration= Rainfall intensity= Summary of stream data: 5.466(CFS) 5.31 min. 7.347(In/Hr) Stream No. Flow rate (CFS) TC (min) Rainfall Intensity (In/Hr) 1 4.922 5.58 7.120 2 5.466 5.31 7.347 Qmax(l) = 1.000 * 1.000 * 4.922) + 0.969 * 1.000 * 5.466) + 10.220 Qmax(2) 1.000 * 0.953 * 4.922) + 1.000 * 1.000 * 5. 466) + 10.155 Total of 2 main streams to confluence: Flow rates before confluence point: 4.922 5.466 Maximum flow rates at confluence using above data: 10.220 10.155 Area of streams before confluence: 2.120 1.210 Results of confluence: Total flow rate= 10.220(CFS) Time of concentration 5.578 min . Effective stream area after confluence 3. 330 (Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 22.000 to Point/Station 22.000 **** SUBAREA FLOW ADDITION**** Rainfall intensity (I) = Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [MEDIUM DENSITY RESIDENTIAL (14.5 DU/A or Less Impervious value, Ai= 0.500 Sub-Area C Value= 0.626 7.120(In/Hr) 0.000 = 0.000 0.118 = 0.882 Time of concentration= 5.58 min. for a 100.0 year storm Rainfall intensity= 7.120(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.438 CA= 1.535 Subarea runoff 0.706(CFS) for 0.170(Ac.) Total runoff= 10.926(CFS) Total area= 3.500(Ac.) 7 ----- - - - ----- -- - -- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 22.000 to Point/Station 38.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** Upstream point/station elevation= 124.450(Ft.) Downstream point/station elevation 122.500(Ft.) Pipe length 30.00(Ft.) Slope= 0.0650 Manning's N 0.013 No. of pipes= 1 Required pipe flow 10.926(CFS) Nearest computed pipe diameter 15.00(In.) Calculated individual pipe flow 10.926(CFS) Normal flow depth in pipe= 8.93(In.) Flow top width inside pipe= 14.72(In.) Critical depth could not be calculated. Pipe flow velocity= 14.35(Ft/s) Travel time through pipe 0.03 min. Time of concentration (TC) 5.61 min. End of computations, total study area= 3.500 (Ac.) 8