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Home My WebLink AboutPD 2019-0037; CANHAM RESIDENCE; HYDROLOGY AND HYDRAULICS REPORT; 2020-01-27 HYDROLOGY & HYDRAULICS REPORT PROJECT: Canham Residence 7164 Aviara Drive, Carlsbad PD2019-0037 GR2019-00042, DWG 521-6A APN: 215-610-20-00 PREPARED FOR: Tom and Ellen Canham 285 Grande Way, Apt. 1804 Naples, FL 34110 PREPARED BY: Kristin L. Greene, P.E. dk GREENE CONSULTING, INC. P.O. Box 143 Bonsall, CA 92003 J.N. 19-01 I hereby declare that I am the engineer of work for this project, that I have exercised responsible charge over the design of the project as defined in Section 6703 of the Business and Professions code, and that the design is consistent with current standards. January 27, 2020 Kristin L. Greene, P.E. C57860 Date EXPIRES: JUNE 30, 2020 d<Greene Consultlng, Inc. ii Contents 1.0 PROJECT INFORMATION .......................................................................................................... 1 1.1 SITE AND PROJECT DESCRIPTION ......................................................................................................... 1 1.2 EXISTING SITE TOPOGRAPHY AND DRAINAGE CONDITION ........................................................................ 3 1.3 PROPOSED SITE TOPOGRAPHY AND DRAINAGE CONDITION ..................................................................... 5 2.0 HYDROLOGY AND HYDRAULIC CALCULATIONS ......................................................................... 5 2.1 METHOD OF CALCULATION ................................................................................................................ 5 2.2 SOIL TYPE, IMPERVIOUSNESS, SELECTION OF “C” .................................................................................. 6 2.3 SUMMARY TABLE OF Q VALUES .......................................................................................................... 7 3.0 REPORT SUMMARY ................................................................................................................. 7 3.1 RECOMMENDATIONS ........................................................................................................................ 7 APPENDIX A ......................................................................................................................................... 9 EXISTING HYDROLOGY MAP .......................................................................................................................... 10 PROPOSED HYDROLOGY MAP........................................................................................................................ 11 APPENDIX B ....................................................................................................................................... 12 HYDROLOGY CALCULATION SPREADSHEET ....................................................................................................... 13 COUNTY OF SAN DIEGO HYDROLOGIC TABLES AND FIGURES 100 YEAR RAINFALL EVENT – 6 HOURS ........................ 14 COUNTY OF SAN DIEGO HYDROLOGIC TABLES AND FIGURES 100 YEAR RAINFALL EVENT – 24 HOURS ...................... 15 SOILS MAP FROM NRCS WEB SOIL SURVEY .................................................................................................... 21 LIST OF FIGURES FIGURE 1‐1. VICINITY MAP .................................................................................................................................................. 1 FIGURE 1‐2. GOOGLE EARTH PLAN VIEW ................................................................................................................................ 2 FIGURE 1‐3. THE SITE LOOKING EASTERLY TOWARD AVIARA DRIVE .............................................................................................. 3 FIGURE 1‐4. EXISTING OUTLET POINT TO THE WEST.................................................................................................................. 4 • ckGreene Consulting, Inc. 1 Hydrology & Hydraulics Report City of Carlsbad 1.0 Project Information 1.1 Site and Project Description This project provides for the development of a one-story single-family home with an attached garage. A vicinity map is shown below. Figure 1-1. Vicinity Map The lot is surrounded on the north, south and west by existing single-family residences of the same type. On the east, there is an existing golf course and an environmentally sensitive area. This report will focus on the Drainage Study in response to the grading and improvements associated with the development. In the pre-development condition, the site has two basins that outlet to the east and to the west. In the post-development VICINITY MAP HTS pl(lf'( ck Greene Consulting, Inc. 2 condition, the site will drain toward the street in order to protect the environmental sensitive area toward the west. This report will evaluate the Q100 for the existing condition and compare it to the Q100 for the proposed condition by using the Modified Rational Method and County of San Diego’s Hydrology Manual to evaluate peak flows. Figure 1-2. Google Earth Plan View ck Greene Consulting, Inc. 3 1.2 Existing Site Topography and Drainage Condition Topography of the site was provided by Dale Greene, LS. The site has approximately 8 feet of elevation difference from the higher elevation at the north property line, to lowest elevation at the east property line. Figure 1-3. The Site Looking Westerly Toward Aviara Drive The site is currently graded per Carlsbad Tract Map 85-35. There is an existing fill slope on the northerly property line and a fill slope along the southerly property line. Generally, the existing 15,788 sq. ft. site drains partially westerly and partially easterly. There is no “run-on” associated with this site. dc:Greene Consulting, Inc. 4 Figure 1-4. Existing Outlet Point to the East See Appendix A, Existing Hydrology Map. dc:Greene Consulting, Inc. 5 1.3 Proposed Site Topography and Drainage Condition The proposed grading and drainage pattern will mimic the existing drainage condition and pattern, to the maximum extent practicable. The existing grading will be maintained. The site will be developed with a one-story single-family home. All the runoff from the lot (0.36 ac.) will drain to the west (Basin A). Basin A (0.19 ac) is divided into three drainage sub-basins, A-1, A-2, A-3 will drain westerly toward the existing street and into public drainage system. See Appendix A, Proposed Hydrology Map. 2.0 Hydrology and Hydraulic Calculations 2.1 Method of Calculation This Hydraulics & Hydrology Report was prepared using the following Manual: “San Diego County Hydrology Manual, June 2003.” The Rational Method was used to determine the 100-year Storm Q values. The Rational Method uses the following formula to establish 100-year flow: Q = C I A where: Q = The peak runoff in cubic feet per second. C = Runoff coefficient representing the ration of runoff to rainfall. I = Time average intensity in inches per hour. A = Area of sub-basin in acres. ck Greene Consulting, Inc. 6 2.2 Soil Type, Imperviousness, Selection of “C” According to the soils report prepared for this project, by David Skelly of GeoSoils, Inc, the soils Group should be classified as “D”. According to the United States Department of Agriculture Natural Resources Conservation Service Web Soil Survey online tool, the site soil is classified as “Soil Group D”. See Appendix B, Soils Map. The runoff coefficient “C” will be based on this soils group for both the existing and proposed condition. The “C” for the existing conditions will be based on 0% imperviousness (Cpre =0.35). The proposed condition “C” value will be based on the proposed condition of 54% impervious (8,448 sq. ft./15,788 sq. ft.) which will result in Cpost = 0.65. See Appendix B, County of San Diego Hydrologic Tables and Figures, Table 3-1. • cl<Greene Consulting, Inc. 7 2.3 Summary Table of Q Values Calculations were conducted for this project and are provided in the spreadsheet table in the Appendices. PRE VS. POST SUMMARY Node Pre Development Discharge Q100 (cfs) Post Development Discharge Q100 (cfs) Difference (cfs) Basin A 0.58 1.15 +0.57 The difference between the pre and post condition is shown above. The development increases the impervious area. The existing storm drain system in Aviara Drive was sized to accommodate this infill project and this increase in runoff for Basin A. Calculations and maps of the existing and proposed hydrology are provided in Appendices A and B. 3.0 Report Summary 3.1 Recommendations This development project encompasses a single-family home, driveway and landscaped areas on approximately 15,788 sq. ft. The proposed development does increase the impervious surface and therefore generates an increase in runoff. However, downstream facilities were sized and located to handle ultimate development and therefore can accommodate the additional runoff created by this development. In my professional opinion, the proposed project will not substantially alter the existing drainage pattern of the area. The project has been designed to maintain the historical drainage pattern. The small increase from the existing condition to the post- development condition will not create downstream flooding or overwhelm the existing drainage facilities due to the development of this project. ck Greene Consulting, Inc. 8 APPENDICES • cl<Greene Consulting, Inc. 9 Appendix A Existing Hydrology Map Proposed Hydrology Map ck Greene Consulting, Inc. dk Greene Consulting, Inc. BONSALL, CA 92003 (760) 310-9408 P.O. BOX 143 ELEVATIONS ARE BASED ON MONUMENT NO. CLSB 44 RECORD OF SURVEY 17271 DRAINAGE LEGEND DRAINAGE PATH BASIN DELINEATION OUTFALL 1 FLOW LENGTH ¾¾¾ L=215 EXISTING HYDROLOGY MAP E XPIRES :6 /3 0 /2020VICINITY NTS PKwY SITE clcGreene Consulting, Inc. MAP 4' GENERAL UTIL. EASEMENT PER MAP NO. 12412 ' --·------------I ----------------.---... -- i ,.__ ----....... APN 215-610-19 LOT 251 MAP 12412 BASIN "A" 0.34 ACRES (14,712 SF) TOP=252' BOTTOM=243.5' L=l25' I ._ I ._ -N 87'31'28" E 170.91'--- --- I I I I I ---- i I I I I I I I I I I I I I I I I I I I I I I I I I I I I i ; I ; I I / I ,I I : I I f I I f / I / I I I I / I / I I I I I / I / I I I I I I I I I I _., I I j / I I I I I I / / I I I , I 1 l I I , I I II I I , I I I I I I J / I I -,~-------- / I I I J j I I , l I I I I I l I J I l I I I I ,I ' I I I / / I ,,./ _1...1 // / ,,/ /,,,,. ,,,.,,,, I .,./I / ,,,, ,,,-,1----------I .'I//// /.. ,,.-✓ ,,.1,,/ /,~ ,/ I / ,,, I .,,. 1/'/' I ,,... ... ,,. I I ,,. / ,,..,,. I I l I .,, I I · I // f I l I I I . l ,,,,,/,, I I !J I I f I I f I I I -/ //1 / ,,,/ I I I I I I l I I I /11/ I 11 , I , ,1 1 I I / I I I / F I I I I , I I I '// i I /;/( )·~ /' / / ,l / ,Is:. J j I ! ;: l I l l ,I ;E> ' I r ,f ,-/ I I I /I~ / / ,' / ' lo~ / I I , I ,I' 11'/ // ,,fl / ~ J I l I /"i / (/) I I I I I : I I I ' I I I I I I I ' -- , I I I / I I II I / I I I J I I I I ', ,' ! ! I I -- I r I ! ' I I - - - ------ APN 215-611-01 LOT 253 MAP 12412 0 10 20 30 ----------- BENCH MARK "AS BUILT" RCE __ _ EXP, ___ _ DATE REVIEWED BY: INSPECTOR DATE 1-------+----+---------------t-----t----t-----t---------i I SH1EET I CITY OF ARL BAD I SHE1ETS I ENGINEERING DEPARTMENT 1------11---+----------------t-------t-----t---,-, :::E:::::::;:::::::;:::',.':::;HYD;;::;R~O~LO~ClY~P~L:;'Af{~F~O~R:~· :::::::::==:==::::'....'==~ CANHAM RESIDENCE 7164 A \TIARA DRIVE GR2019-0042 APPROVED: JASON S. GELDERT DESCRIPTION:_________________ CITY ENGINEER RCE 63912 EXPIRES 9 30 20 DATE LOCATION: 1-----+--+-,,----------------t-------t--t-----i-----, ~:;::::=::::===::::::;';:::::::::::::::::::::::::::::::::::==::::::::::::'.::;;::::~~==:::: RECORDED:____________________ DATE INITIAL ELEVA 770N: _.,.24,,,0,.-.2.,,6 ________ DA TUM: .....JN.,.,G...,V""Pu1,.92..,9'---I-E-N_G_IN-EE_R.J.O_F_W,--0-R--IK DWN BY: PROJECT NO. DRAWING NO. CHKD BY: ---PD2019-0037 521-64 OA TE INITIAL DATE INITIAL REVISION DESCRIPTION 01HER APPROVAL CITY APPROVAL RVWD BY: dk Greene Consulting, Inc. BONSALL, CA 92003 (760) 310-9408 P.O. BOX 143 ELEVATIONS ARE BASED ON MONUMENT NO. CLSB 44 RECORD OF SURVEY 17271 DRAINAGE LEGEND DRAINAGE PATH BASIN DELINEATION OUTFALL 1 FLOW LENGTH ¾¾¾ L=215 PROPOSED HYDROLOGY MAP E XPIRES:6 /3 0 /2020VICINITY MAP NTS PKwY SITE NOTE: PRIOR TO ANY WORK CONDUCTED IN THE CITY'S RIGHT OF WAY OR EASEMENT, THE CONTRACTOR SHALL APPLY FOR AND OBTAIN A RIGHT OF WAY PERMIT. BASIN "A-4" BASIN "A-2" 0.01 ACRES (561 SF)--. TOP= BOTTOM= L=16' APN 215-610-19 LOT 251 MAP 12412 EXISTING SINGLE FAMILY RESIDENCE ALL -NON RETAINING EXISTING PRIVACY W i I I I I I / I I I B IN "A-5"/ I .10 ACRES /(4,354 SF) Ii TOP=246.39/ BOTTOM=141 I L=209' I __ ., - I I I I I I I I I I i ; I ; I I I ! I II I I I I I I I / I I I I I I I I I II I I I I I I I II I I , I 1 l I I , I I II I I , I I II I I 0.10 ACRES (4,184 SF) TOP=246.58 BOTTOM=242.17 I J / I I ~,-------- / I I EX. CONCRETE CURB, GUTTER AND SIDEWALK\ EX. FIRE HYDRANT L= 164'4' GENERAL UTIL. EASEMENT PER MAP NO. 12412 (241 a SC-1 ---~------Q SIDEWALK U DRAIN PIPE PER ----- A( 100)= 1. 02 cfs SDRSD ,REPLACESIDEWALK ________________ ....:,.F.,,.., ... JOINT TO JOINT de Greene Consulting, Inc. 4' WIDE EASEMENT DEDICATED TO<...._,, PACIFICL BELL PER DOC. NO. 1990-0636009 DATED 11/29/1990 PROPOSED RETAINING WALL PER SDRSD C-6 ,' I I JI I I , l I I I I I 9~~ .,_.~~ /' . t ~----- l I J l I I I I 1' I I I'l l I / / / ' . ~ ' E . . l j 1/ J 1 -I I II ,,,.,,,,, / / y ,_.,,.,..,. .,,1 ....... ____ ,,,..,,,........ ,I • ,./' ,,..✓ ,,.,..., /' I ;,_;;?it>~ ----. . i-11"!'--:ii.---,L------ · .. 2o/o ~ BASIN "A-1" ;::;::;J--,--.LJ--,---'---,-----'---,----L..::~L,,--'--,.7// (,/(,/II ,I/ ///_/ I I I / /,/ •. ·. 0.09 ACRES (2,533 SF) I I · ,1 ,,,,,// PROPOSED GARAGE PAD EL=246.19 PROPOSED PRIVACY WALL PER ARCH. PLAN TOP= BOTTOM= L=54' PROPOSED HOUSE PAD EL=246.19 FF EL=246.86 D FOOTI E FOUNDATION I I !J I I I I I I / / / _,,, UIRED1 / / / 1,,.// / I I / I I I / 111/,,1 I ;f I I I I I I I I I I / I / I -< -< -< -< -< -< --+--►-►- TOP OF SLOPE HOA SETBACK 0~/1 /1 / l /§ 1i 7:::11 r";::// /I / / "-1.J.J /ff"/ -- ~u>.,. EX. 2:1 FILL SL kQ TOP OF SLOPE HOA SETBACK POOL PER SEPARATE PERMIT -J I I I ; 1';,C ~/ t / / 2 /,.,, Ci'! 0 1 I I I O I' 7-8,l / / / g / ' J..:..I I I f I-./ !..._ I / I / .l:' ,Fs:-/I// g ~ , 1 , ,, 2 ;r I / I / ~ ,~ I ,' I ,' .::. I I ,. I ·~ // // / / /rJ I ~ I I I I I I I / I / / / /' i (/) l I I f I J I l I '< ' I I J I I I I I I I I JI I I I J I JI I I I I I ' I J I I I I I I I / I I I I I I I ,/ / ! ! I I ' ----,, EXc;"l,ROUGHT IRON FENCE --...,\\ I I I ! I ,I, I ' I I , I I PROPOSED WROUGHT IRON FENCE PROPOSED V JUNCTION BOX PROPOSED WROUGHT IRON FENCE PRIVACY FENCE/WALL PER ARCH PLAN 0 10 20 30 APN 215-611-01 LOT 253 MAP 12412 BASIN "A-3" 0.05 ACRES (2,206 SF) TOP= BOTTOM= L=30' BENCH MARK DESCRIPTION: __________________ >---+------,>-------------------+----+---1----->----, LOCATION: __________________ 1----+----+~---------------+---t----+-----+----1 RECORDED: __________________ _ DATE INITIAL DA TE INITIAL DA TE INITIAL ELEVA TTON: _~24=0=.26~-------DA TUM: NGYP 1929 ENGINEER OF WORK REVISION DESCRIPTION 01HER APPROVAL CITY APPROVAL - - - ------ "AS BUILT" RCE __ _ EXP.____ DATE REVIEWED BY: INSPECTOR DATE I S~EET I CITY OF CARLSBAD I SHE1ETS I ENGINEERING DEPARTMENT PROPO~ED HYDROLOGY PLAJ,{ FOR: CANHAM RESIDENCE 7164 A \TIARA DRIVE GR2019-0042 APPROVED: JASON S. GELDERT CITY ENGINEER RCE 63912 EXPIRES 9 /30 /20 DATE DWN BY: PROJECT NO. DRAWING NO. CHKD BY: PD2019-0037 521-64 RVWD BY: 12 Appendix B Hydrology Calculation Spreadsheet County of San Diego Hydrologic Tables and Figures Soils Map ck Greene Consulting, Inc. 13 Hydrology Calculation Spreadsheet SYSTEMAREA(AC)CU/SELEVATION(FT)D/SELEVATION(FT)LENGTH(FT)SLOPE(%)P6(IN)Ti from Figure 3-3TC (MIN) 3-4SUM OF TC(MIN)I(IN/HR)Q(CFS)Basin A 100 yr0.34 0.35 252.0 243.5 125.0 6.8 2.5 8.0 0.0 8.0 4.90.58Total Area0.340.58SYSTEMAREA(AC)CU/SELEVATION(FT)D/SELEVATION(FT)LENGTH(FT)SLOPE(%)P6(IN)Ti from Figure 3-3TC (MIN) 3-4SUM OF TC(MIN)I(IN/HR)Q(CFS)BASIN ABasin A-1 100 yr0.12 0.65 247.1 246.9 16.0 1.2 2.5 3.0 0.0 5.0 6.6 0.51Basin A-2 100 yr0.10 0.65 246.6 243.0 146.0 2.5 2.5 7.3 0.0 7.3 5.2 0.34Basin A-3 100 yr0.10 0.65 246.4 241.0 209.0 2.6 2.5 8.5 0.0 8.5 4.7 0.30Total Area0.321.15** Difference in areas is due to the existing east side slope and the pool, which are self mitigating.Pre PostDifferenceBasin A100 yr 0.58 1.150.57POST DEVELOPMENT CONDITION SUMMARYBasin A Total QPRE DEVELOPMENT CONDITION SUMMARYBasin A Total Q I I r r l I I II II I I - 14 County of San Diego Hydrologic Tables and Figures 100 Year Rainfall Event – 6 Hours SITELat. 33°06’ Long. 117°17’ P6 = 2.5 County of San Diego Hydrology Manual Rainfall I. ·opluvia/s 100 Year Rainfall Event -6 Rours lsop).Mal (nchn) 15 County of San Diego Hydrologic Tables and Figures 100 Year Rainfall Event – 24 Hours SITE Lat. 33°06’ Long. 117°17’ P24 = 4.5 rT 1W l-+-< ........ County of San Diego Hydrology Manual Rainfall lsopluvials 100 Year Rainfall E\•ent -24 Hours s lsopruv!al (lnth&s) DPW GIS .,_._,,,,_,..,_ ~----3 o 3 Miles ~ 16 2.7 100 2.5 4.5 56 See Appendix B, Hydrology Calculation Spreadsheet 100 90 8-0 70 8.0 5.0 40 30 2.0 0.3 02 o., 1'. ........ .... ~ , ... .............. ......._ ' ............... i-.., ~ ~ .................. .... ....... 1-. '--~ , ........ ..... :--' ........ ..... ............... ....... ... --~ r-.... 'I......., .... , ,, ~ .... ....... , ............... .... ' I .... , 1,, ~~ ( . ---.. + t I . . . . ' • ( u.. 6 8 7 8 9 10 15 11 I I (I I I '1' r-.. .... I' I ..... f' I ' ... ~ " I' ~ 11,,. ' i"' r.:. ' I ... ~ I ... • ... ' I' I'-. ... ... I ... ... ~ I' ... ... l ~ I 1111111111 II • I I 1' ■ I I 1111111111 1111 Ill 111 I 111111111111 I 1111 1111111 I 11111111111 I 111 111 1111 I EOUATIO I I = 1.« Ps o-0-645 I I • Int ty (wvlv) P5 = 6-Hour Precip,tation (in) I D = Duration (min) I ,. .... 'i .... ... ... .... ~ ... 'l' I' i r. .... f' .... .... ~ ~ ... ~ 1, ... ~ I ..... ;._ I ~ ~ .... ... .... i'\,. .... ' I 1, ... , ;, ... . ,1 ... .... I i i1' .... .... ~ ... . ~ ;,-.... ' ' I I .... I I ... . 11 I .......... ' I I 1, ~ ... I ... .... ' I ,. I I Ii-." . ...... -I .l. l II II ' I .... 30 2S 2.0 1 S 1.0 20 :,0 40 50 1 2 3 Hours 5 8 Minutes Dir.Ilion Intensity-Duration Design Chart -Template Dlrectlona fM Appllc:.tlon: ( 1) Fl'Qffl preop1atJon maps d ~ 6 hr 30d 24 hr amoun fo, the selected frequency. These maps are included in lho CQny Hydrology Manual (10, 50. end 100 yr~ Included In the O ign nd Proooduro Ma I) (2) AdJust 6 hr preapitation [if necessary) so that it s lho range ol 45% to 65% or tho 24 hr precipitation (not epplicaple to Oesen). (3) PIOl 6 Iv precipitation on lho right side or tho cl\an . (4) Draw a line through the po nt parau to the plOtted Un (5) This line is the intensily~uration curve for lho location being lyied. AppUc•tlon Form: (a) Selected lrequoncy __ year p (b) P5 = __ in .. P24 = __ .~ = %«2) 24 (C) Adjusted P5(1.)• __ in . (d)'x• __ mn.} (e) I • ___ 111.1hr. Note: This chart replaoes the Intensity-Duration-Frequency curve used since 1965. P6 u 2 ' eu,.-I I I 5 2.63 395 1 ' 1 11 1 1 144 16. I 7 2 12 3. 18 4.24 6.30 0.38 H2 0.48 954 1000 11 ee 12.12 10 1.811 253 3 37 4 21 606 S90 6.74 7.58 8A2 927 10-11 15 1.30 I 95 2.59 12• 3.119 • SC 6.19 6. .. 8-'9 713 1.18 20 1.08 1.62 2.15 2.1511 3.ZI :I.TT • 31 Oil 5.39 &.93 11.46 25 093 I 40 1.87 233 2.80 3,27 3,73 420 4e7 513 6.80 >O 043 I 24 100 207 249°290 3,32 3,73 415 4.54 •98 40 099 I 03 1 1.72 207 2.41 2.76 3.10 3,45 379 413 50 000 0.90 1.19 1.49 1.79 2.09 2.39 2.69 299 3.211 3.!58 60 OM oeo 100 133 159 ue 212 239 285 2fi2 3.18 90 0'1 081 0.82 11)12 123 143 163 1 .. 2.04 22:S 745 120 0.3' 051068 0-16 11)12 119 136 1.!13 170 1.87 2.04 150 0.29 o.u 0~9 0.73 OM 1Cl3 118 132 I., 1$2 1.78 190 028 039062 085 078091 104 118 1.:11 14' 1 S7 240 0.22 033 043 0-54 ·o-66·076 0-81 0-111 1.08 119 130 300 0.19 021 038 0-47 0-116 065 0.78 0111 09' 103 1.13 HO 0.17 025 033 0.42 060 068 Oe7 075 0.84 OS2 100 3-1 17 Existing Impervious Surface = 0% impervious - C = 0.35 Proposed Impervious Surface = ଼,ସସ଼ ௦௤.௙௧.ଵହ,଻଼଼ ௦௤.௙௧. = 0.54 => C = 0.65 Existing C=0.35 Proposed C=0.65 Sau Diego Couuty Hydrology Manual Date: June 2003 Table 3-1 Section: Page: R OFF COEFFICIE rTs FOR RBA_ AREAS Land Use Runoff Coefficient "C" Soil Type NRCS Elements County Elen1ents %IMPER. A B ndisturbed atural Terrain aniral) Permanent Open Space 0* 0.20 0.25 Low Density Residential (LDR) Residential, 1.0 DU/A or less 10 0.27 0.32 Low Density Residential (LDR) Residential, 2.0 DU/A or less 20 0.34 0.38 Low Density Residential (LDR) Residential, 2.9 DU/A or less 25 0.38 0.41 Medium Density Residential (MDR) Residential, 4.3 DU/A or less 30 0.41 0.45 Medium Density Residential (MDR) Residential, 7.3 DU/A or less 40 0.48 0.51 Medium Density Residential (MDR) Residential, 10.9 D /A or less 45 0.S2 0.S4 Medium Density Residential (MDR) Residential, 14.S D /A or less so 0.SS 0.58 High Density Residential (HDR) Residential, 24.0 D -1A or less 65 0.66 0.67 High Density Residential (HDR) Residential, 43.0 DU/A or less 80 0.76 0.77 Commercial/Industrial (N. Com) eighborhood 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.S7 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 0.8S 0.85 0.87 *The values associated with 0% in1pervious may be used for direct calculation of the rnnoff coefficient as described in Section 3.1.2 (representing the pervious rnnoff coefficient, Cp, for the soil type). or for areas that will remain undisturbed in perpetuity. Justification must be given that the area will remain naniral forever (e.g., the area is located in Cleveland ational Forest). D IA= dwelling units per acre NRCS = l ational Resources Conservation Service 18 Table 3-2 MAXIMUM OVERLAND FLOW LE. GTH (½1) & INITIAL TIME OF CO::\'CE::\'TRATION (Ti) Element* DU/ .5% 1% 2% 3% 5% 10% Acre LM Ti LM Ti LM Ti LM Ti LM Ti LM Ti Natrn-al 50 13.2 70 12.5 85 10.9 100 10.3 100 8.7 100 6.9 LDR 1 50 L.2 70 11.5 85 10.0 100 9.5 100 8.0 100 6.4 LDR -50 11.3 70 10.5 85 9.2 100 8.8 100 7.4 100 5.8 LDR 2.9 50 10.7 70 10.0 85 8.8 95 8.1 100 7.0 100 5.6 MDR 4.3 50 10.2 70 9.6 80 8.1 95 7.8 100 6.7 100 5.3 MDR 7.3 50 9.2 65 8.4 80 7.4 95 7.0 100 6.0 100 4.8 MDR 10.9 50 8.7 65 7.9 80 6.9 90 6.4 100 5.7 100 4.5 MDR 14.5 50 8.2 65 7.4 80 6.5 90 6.0 100 5.4 100 4.3 HDR 24 50 6.7 65 6.1 75 5.1 90 4.9 95 4.3 100 3.5 HDR 43 50 5.3 65 4.7 75 4.0 85 3.8 95 3.4 100 2.7 N.Com 50 5.3 60 4.5 75 4.0 85 3.8 95 3.4 100 2.7 G.Com 50 4.7 60 4.1 75 3.6 85 3.4 90 2.9 100 2.4 O.P./Com 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2 Limited I. 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2 General I. 50 3.7 60 3.2 70 2.7 80 2.6 90 2.3 100 1.9 *See Table 3-1 for more detailed description 19 1-w w 11. ~ w (.) z ~ (/) ci w (/) er: :::, 0 (.) er: i EXAMPLE: Given: Watercourse Distance (D) = 70 Feet Slope (s) = 1.3% Runoff Coefficient (C) = 0.41 Overland Flow Time (T) = 9.5 Minutes SOURCE: Airport Drainage. Federal Aviation Administration, 1965 T = 1.8 (1.1-C) \/o 3'ifs F I G Rational Formula -Overland Time of Flow Nomograph 3.3 20 6E Feet 5000 41000 EQUATION Tc • (1:;~')°'385 Tc L 6E Time of concontration {hours) • Watercourse Distance (mlloc) Change In elevaUon along effective slope line (See Figure 3-S)Cleetl 3000 2000 1000 900 800 ,:00 ~, 500' ' ' 300 200 6E 100 so "° 30 20 10 '~.., ~ ' ' ' ' ' ' ' ' SOURCE: Cal~omia DMslon ol Highways (1941) and Ki"pich (1940) L Mlkts FHt '1 ' 3000 0.5 ' 2000 1600 1600 1400 1200 1000 900 600 700 600 500 400 300 200 L ' Nomogroph for Determination of ' ' Tc Hours Minutes ' ' ' Tc go so "° 30 & • Time of Concentrofton (Tc) or Travel Time (Tl) for Natural Vtbtersheds f I G R E ~ 21 Soils Map from NRCS Web Soil Survey This property was determined to be Hydrologic Soil Group D per the United States Department of Agriculture Natural Resources Conservation Service (NRCS) Web Soil Survey online tool. Report -Hydrologic Soil Group and Surface Runoff Absence of an entry indicates that the data were not estimated. The dash indicates no documented presence. San Diego County Area, California Map symbol and soil name CfC-Chesterton fine sandy loam, S to 9 percent slopes Chesterton LvF3-Loamy alluvial land-Huerhuero complex, 9 to SO percent slopes, severely eroded Huerhuero Loamy alluvial land Pct. of map unit Surface Runoff Hydrologic Soil Group 85 Very high D 30 Very high D 30 High B 1/28/2020 Open Channel Flow Calculator www.eng.auburn.edu/~xzf0001/Handbook/Channels.html 1/1 The open channel flow calculator Select Channel Type: Circle Depth from Q Select unit system: Feet(ft) Channel slope: .01 ft/ft Water depth(y): 0.38 ft Radius (r) .25 ft Flow velocity 3.2406 ft/s LeftSlope (Z1): RightSlope (Z2): to 1 (H:V) Flow discharge .51 ft^3/s Input n value .013 or select n Calculate!Status:Calculation finished Reset Wetted perimeter1.05 ft Flow area 0.16 ft^2 Top width(T)0.43 ft Specific energy0.54 ft Froude number 0.94 Flow status Subcritical flow Critical depth0.37 ft Critical slope 0.0104 ft/ft Velocity head0.16 ft Copyright 2000 Dr. Xing Fang, Department of Civil Engineering, Lamar University. to 1 (H:V) 6" pipe okay for all Basin A ~ ~~ f--T ---l l---1 ---I ' / )V(L ~I, ~]1 zl z2 I " I b z I--b -l ~ Rectangle Trapezoid Triangle Circle I I 'f I I I " I 11 II I Ill I 11 II r I 111 I I 11 I I I II I II I I I 11 II I I 11 II I 11 II I 111