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Home My WebLink AboutSDP 2018-0004; ROMERIA POINTE APARTMENTS; Preliminary Drainage Study; 2018-08-1710~~1 ENGINEERING Professional Civil Engineer and Land Surveyor Preliminary Drainage Study for Romeria Pointe Prepared for: BNR INVESTMENT & DEVELOPMENT, LLC 23800 VIA DEL RIO YORBA LINDA, CA 92887 (714) 692-9120 Proiect Site Address 7527 Romeria Street, Carlsbad, CA Prepared by: Michael L. Benesh, R.C.E. 37893 Date: August 17, 2018 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 r Engineering Romer/a Pointe Preliminary Drainage Study Contents Section 1. Certification ........................................................................................... A-2 Section 2. Discussion ............................................................................................. A-2 Section 2.01 Purpose .......................................................................................... A-2 Section 3. Project .................................................................................................... A-3 Section 3.01 Description .................................................................................... A-3 Section 3.02 Topography and Land Use ........................................................ A-3 Section 3.03 Off-Site Drainage ......................................................................... A-3 Section 4. Methodology .......................................................................................... A-4 Section 4.01 Rational Method .......................................................................... A-4 Section 4.02 Hydraulics ...................................................................................... A-5 Section 5. Summary ................................................................................................ A-6 Section 5.01 Post Construction Storm Runoff Impacts .................................. A-6 5.01 . 1 Storm Runoff Entering the Site .................................................... A-6 5.01 .2 Storm Runoff ................................................................................. A-6 Attachment A -Vicinity Map ............................................................................................. A-9 Attachment B -Hydrology Map .......................................................................................... B-1 Attachment C -San Diego County Soils Group Map ...................................................... C-1 Attachment D -San Diego County Hydrology Manual Excerpts ................................... D-1 Attachment E -San Diego County Point Rainfall Maps .................................................... E-1 Attachment F -TC Calculations .......................................................................................... F-1 Attachment G -Rational Method Calculations ................................................................ G-1 Attachment H -Hydraulic Calculatlons ............................................................................. H-1 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 r Engineering Section 1. Certification Declaration of Responsible Charge Romeria Pointe Preliminary Drainage Study I hereby declare that I a m the engineer of work for this project as defined in Section 6703 of the Business and Professions Code, and that the design is consistent with current standards. I understand that the check of project drawing and specifications by the City of Carlsbad is confined to a review only and does not relieve me, as engineer of work, of my responsibilities for project design. Michael L Benesh, RCE 37893 Section 2. Discussion Section 2.01 Purpose RCE 37893 11/19/18 Date The purpose of this study is to determine the existing and anticipated 100-year storm runoff and required size of hydraulic structures to protect the proposed and existing slopes and structures on the site, and to identify existing drainage problems that may be caused, or aggravated, by project development. The project is required to meet County of San Diego Hydromodification Mitigation that requirement that the Post-project runoff conditions (flow rates and durations) must not exceed pre-development runoff conditions by more than 10 percent for storms in the range of 0.2 Q2 up to to the ten year storm event. The SWQMP for the project contains the hydromodification management plan and supporting calculations. 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 c· Engineering Section 3. Project Section 3.01 Description Romerla Pointe Preliminary Drainage Study The project is a 0.7 acre site located in the City of Carlsbad, California. The site is bordered by Romeria Drive to the east, Gibraltar Drive to the north and multi-family residential developments to the south and west. The site does not contain any natural drainage channels or significant natural vegetation. The project has previously been graded and consists of two building pads and manufactured 2: 1 slopes. The proposed project includes the construction of a 16 unit apartment complex in 2 buildings. The project parking will be inside the covered parking structure at the lowest level of each building. The construction will include driveways, buildings and the extension of utilities from Romeria Street and Gibraltar Street into the site. The r proposed activities will be typical attached residential living . .. A detailed vicinity map is included in Attachment A. Section 3.02 Topography and Land Use The majority of the runoff from the site drains overland to Romeria Street to the east and Gibraltar Street to the north. The runoff in the streets are picked up in a catch basin on Gibraltar Street just west of the project site. From there it is conveyed to San Marcos Creek by means of a city storm drain system, and a concrete lined watercourse through the golf course north of the project site. A westerly facing slope drains to the property to the west of the project, which in turn drains out to Gibraltar Street and San Marcos Creek. Section 3.03 Off-Site Drainage There does not appear to be any runoff entering the project site from the adjoining properties. There are public streets on the north and east sides of the site and the property to the west is much lower than the site. The property to the south is higher than the project site, but there is an existing berm at the top of the slope that would prevent stormwater run-on. 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 C Engineering Section 4. Methodology Section 4.01 Rational Method Romeria Pointe Preliminary Drainage Study The Rational Method as described in the San Diego County Hydrology Manual, Section 3, (Revised June 2003) shall be used to determine storm runoff. The Rational Method formula is expressed as follows: Q=CIA Where: Q = peak discharge, in cubic feet per second (cfs) C= runoff coefficient, proportion of the rainfall that runs off the surface. The coefficient C has no units and is based on the soil group and the development type for the drainage sub-area. Attachment F includes calculations for the runoff coefficient for each drainage sub-area. I= average rainfall intensity for a duration equal to the Tc for the area, (in/Hr.) A = drainage area contributing to the design location, in acres The following values are used in the calculations: Soil Group D from San Diego County Soils Group Map. See Attachment C. C (Coefficient of Runoff) from Table 3-1. 100 year 6 Hr. Rainfall= 2.7" 100 year 24 Hr. Rainfall =4.8" See Attachment D. See Attachment E. " " " The site is first divided into drainage sub-areas. See the On-Site Hydrology Maps in Attachment B. The time of concentration, Tc, for each sub-area along the drainage path is computed based on the initial time of concentration for the initial area and the travel time to reach each succeeding node. Based on the time of concentration, the rainfall intensity is determined using Figure 3-2 (See Attachment D ). Then applying 404 South Live Oak Park Road Fallbrook, CA 92028 760 731-6603 tJUJJ Engineering Romerla Pointe Preliminary Drainage Study the rational method equation, the peak runoff is determined at each node along the drainage path. Q's are tabulated for each sub-area along the drainage path. The rational method calculations are in Attachment G. Section 4.02 Hydraulics Hydraulic Capacity is determined by use of the Mannings Equation. The Mannings formula is expressed as follows: V = 1.49(R 213 5112 )/n Where: V = velocity (ft./sec.) R = hydraulic radius which h is determined by dividing the area of flow by the wetted perimeter (ft.) s = slope of conduit or channel (ft./ft.) n= Mannings roughness factor for the conduit or channel Autocad Hydraflow Express is used to determine the flow in the parkway culverts. Inlet Capacity is determined using the weir equation. Q=3Lh312 or h=(Q/3L)2/3 Where: Q = flow (cfs) L = perimeter of the inlet (ft.) h = depth of water at the grate (ft.) The calculations are included in Attachment H. 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 ( Engineering Section 5. Summary Romeria Pointe Preliminary Drainage Study Section 5.01 Post Construction Storm Runoff Impacts The proposed project will substantially alter the drainage patterns on the site, but will not alter the off-site or the surrounding area drainage patterns. The Storm water discharge points after development will not divert runoff from existing conditions. The potential polutants generated by the additional impervious areas will be mitigated by directing the flows through biofiltration with cisterns BMPs prior to draining to Gibraltar Street. These biofiltration BMPs will be sized to both treat the storm runoff from the site and provide flow control per the County of San Diego Hydromodification Management Plan and therefore the project will not increase the rate or amount of surface runoff in a manner which would result in flooding on-or off-site. The proposed project will not alter the course of a stream or river, in a manner which would result in erosion or siltation either on-site or off-site. The proposed project will not create or contribute runoff water which would exceed the capacity of existing or planned storm water drainage systems. The potential increases in runoff flows flow from the site will be mitigated by the inclusion of hydromodification BMPs in the site drainage system. The project will not place housing within a 100-year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood Insurance Rate Map or County Floodplain Maps as the site to be developed is not within a floodplain. 5.01.1 Storm Runoff Entering the Site The project is not subject to storm run-on. The existing drainage pattern keeps water from entering the property. 5.01.2 Storm Runoff The amount of driveway and parking exposed to storm runoff has been kept to a minimum through the use of parking garages located under the proposed residences, but there will still be an increase to the amount of impervious area prredominantly due to the construction of the buildings. This increase in impervious area will cause an increase the storm runoff from the project drainage area. 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 Engineering Romeria Pointe Preliminary Drainage Study Prior to development the project site has no impervious areas as it is graded pads and slopes. After the site is developed, the impervious area will increase to 0.494 acres (21,514 sf), or 69 percent of the site area. A comparison of pre-and post-construction runoff for the site drainage basin is included in Table 5.2 below. Node Area Pre-Post-Net Pre-Const. Post Const. Net (Ac.) Const. Const. Change Runoff, Runoff, Change %Imp %Imp Ql00(CFS) QlO0(CFS) A 0.71 0 69 69% 1.4 3.3 1.9 cfs The hydraulic calculations in Attachment H indicate that the proposed storm drain structures are adequate to protect the site during a 100-year storm event. The on-site storm drain pipes will be sized with the final plans. The storm drain downstream of the project is a 48" diameter RCP at a slope of one percent. The capacity of the pipe slowing full is 143.6 cfs. (Assuming a Mannings fr n=0.013.) The 1.9 cfs increase in peak runoff from the site is less than 1.5 percent of the l capacity of the strom drain. f The results do not take into account the effect of the bio-filtration with cistern BMPs incorporated into the site design. The BMPs have a combined storage capacity of 4,085 cf. Total Runoff in a 24-hour 100-year Storm-Existing Condition C=0.35 (undeveloped) Vol=0.712 acres x 4.8" / ( 12" /') x 43560 sf/ ac x 0.35 = 4,342 cf Total Runoff in a 24-hour 100-year Storm-Proposed Condition C=0.51 /0.713= 0.715 V 0I=4342 cf x 0. 715/0.35 = 8,870 cf BMP Storage: Effective Depth Biofiltration basin= 6" (ponding) + 0.35 x 39"(media & gravel) = 19.65" Total Basin Volume= 19.65"/12"/' x (325 sf +251 sf+ 516 sf+ 39 sf) = 1852 cf 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 Engineering Romeria Pointe Preliminary Drainage Study 48" Pipe Storage= 12.56 cf/ft x (65' + 62' + 103') = 2889 cf Total BMP Storage= 1852 cf+ 2889 cf= 4,741 cf Un-mitigated 100-year runoff= 8870 cf-4741 cf= 4,129 cf< 4,342 cf ✓OK 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 Engineering Romerla Pointe Preliminary Drainage Study Attachment A -Vicinity Map Portion of U.S.G.S. Rancho Santa Fel Quadrangle. 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 Engineering Romer/a Pointe Preliminary Drainage Study Attachment B -Hydrology Map Attachment 8-1: Existing Condition Hydrology Map The full size map is included in folder at back of report. Attachment 8-2: Proposed Condition Hydrology Map. The full size map is included in folder at back of report. 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 111ITB Engineering Romeria Pointe Preliminary Drainage Study Attachment C -San Diego County Soils Group Map Soils Group Map t t Legend SdlGr-.,pe [=:1 0.-.p" -0.-0.,pB c:::J 0-U..C SOLANABEAC t 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731 -6603 (l ;;-~ GC; -0 .Q. ; (l 0 C ::, ~ !?. ~ ::, 0 15· <O 0 -:::: .._, ~ ~ ;o 0 3 Cl> 15· (l 0 / ~ 5· C <O Cl> !'2 C Q-/ ;o 0 3 g_ 0 -0 ~ 5· C -< ~ ::, C <O Cl> !'2 C Q- b. 0 0 X ,-... > C co C =--:,, N ~ OD ~ cc (D ~ --, Table J..l Rl'SOFF co1-:rF1CIE'.'iTS H>R lRBX\ .\RE.\S utndUse I Runoff Coetlietent ··c~ Soil Type NRCS Elements Coun Elements %IMPER. A B C D Undisturbed Natural Temim (Natural) Permanent Open Space o• 020 0.25 030 0.35 Low Density Residential (LOR) Residenllal, 1.0 DU/A or less JO 027 0.3:? 036 0.41 Low Density Residential (LOR) Res1denllal, 2.0 Dl!:'A or less w 034 0.38 042 046 Low Density Rcs1de11t1al (LOR) Res1den11al, 2.9 DU/A or less 25 038 0.41 045 0.49 Medium Density Res1denttal (MOR) Residenual, 4.3 DlJiA or less 30 041 045 0.48 0.52 Medium Density Residential (I\IDR) Residential, 7.3 DU/A or less 40 048 0.51 0.54 0.57 Medium Density Residential (MOR) Restdent,al, Io 9 DlJ/A or less 45 0 52 0.54 0.57 0.60 Medium Density Restdenttal (MOR) Res1dent1al. 145 Dl1/A or less 50 0 55 0.58 060 063 High Density Residenltal (HOR) Res1dent1al, 24.0 DlJiA or less 65 0.66 0.67 0.69 0.71 High Den~ity Residential (HDR) Residential. 43.0 DlJ/ A or less 80 076 077 0.78 079 CommerciaL1ndustnal (N Com) Neighborhood Commercial 80 076 0.77 0 78 0.79 Commercialllndustnal (G. Com) General Commercial 85 080 0.80 0.81 082 Commercialllndu.itnal (0.P. Com) Office Professioriali( ommercial 90 0.83 0.84 0.84 085 CommerciaMndustnal ( Limited I.) L1m1ted Industrial 90 0.83 0.84 0.84 085 Commercu~li'l_lldustr,al_i~eneral I.) _ ____!]eit_eml lll!i~tnal 95 087 0.87 0.87 087 "The values associated with 0"1i, impervious may be used for direct cakulation of the runoff coefficient a:s descnbcld in Seelloo 3.1.2 (representing the perv1ous runoff coefficient, Cp, for the $Oil type), or for areas that will remain und1stw·bcld in perpetuity Justification must be given that the area Wlll remain riatural fore\·er (e.g., the area is located m Cleveland Natsonal Forest). DWA "' dwelling units per acre NRCS ~ National Resources Conser.a11on Sero.·1ce ~ i :g -::J' •. n CD-==-CD It.. ::,-s-~ 3 CQ -- Cl) :::, .... C I en m :::, C -· CD CQ 0 0 0 C :::, ~ :::c '< Q. a '1IJ -0 0 CQ 3 !t '< Q i: ~ m S' :::, iW' C ~ CD m i -m S' >< ~ (") ~ CD -, S' ,, Q CQ cit CD c,,, c ~ r \ Engineering Romer/a Pointe Preliminary Drainage Study Element* Natural LDR LDR LDR MDR ~vtDR MDR MDR HDR IIDR XCom G.Com O.P.iCom Limited I. General I. Table 3-2 MAXIMUM OVERLAND FLOW LENGTH (LM) & INITIAL TIME OF CONCENTRATION (Ti) DlJ/ .5'% 1%, 2% 30~, 5% Acre LM T l LM ~c L11,t Ti LM Ti LM Ti 50 13.2 70 12.5 85 10.9 100 10.3 100 8.7 I 50 12.2 70 11.5 85 10.0 100 9.5 100 8.0 2 50 11.3 70 10.5 85 9.2 100 8.8 100 7.4 2.9 50 10.7 70 10.0 85 8.8 95 8.1 100 7.0 4.3 50 10.2 70 9.6 80 8.1 95 7.8 100 6.7 7.3 50 9.2 65 8.4 80 7.4 95 7.0 100 6.0 10.9 50 8.7 65 7.9 80 6.9 90 6.4 100 5.7 I-LS 50 8.2 65 7.4 80 6.5 90 6.0 100 5.4 24 50 6.7 65 6.1 75 5.1 90 4.9 95 4.3 43 50 5.3 65 4.7 75 4.0 85 3.8 95 3.4 50 5.3 60 4.5 75 4.0 85 3.8 95 3.4 50 4.7 60 4.1 75 3.6 85 3.4 90 2.9 50 4 ., ·-60 3.7 70 3. t 80 2.9 90 2.6 50 4 ., ·-60 3.7 70 3.1 80 2.9 90 2.6 50 3.7 60 3.2 70 2.7 80 2.6 90 2.3 *Sec Tahlc 3-1 for more detailed description 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 10% LM T; 100 6.9 100 6.4 100 5.8 100 5.6 l00 5.3 l00 4.8 100 4.5 100 4.3 100 3.5 l00 2.7 100 2.7 l00 2.4 l00 2.2 l00 2.2 100 1.9 Engineering "" --I ~ 7 ~ :::.;. -="' l ,=a ~ ;t1h -------0.Cli!j - ,--w: I A ~~ ! I ,, •• =~ Cl = -a. a ~ --"7 -- ;:: -= /, '-// = ~ I =-,- , ,, I ,, I =-J ':?. L ,,__. :=-, i-:: -. ·-,__ -:-/r. --/-.I ~ -. . . . . ~1 I !_! ~ I ~ } -/ -/ ~ 'l I ,, I I/ ';.1 ~ I J I J JI ' J J I . I . I{.. I J ,J V I Romer/a Pointe Preliminary Drainage Study --- I:::: E -,, J. . ~ "'9op1-lan (lll(t!N) :~,~~:: I ' ' ;"-J -✓ -, ·r r 1'/Ji /:J ti 'I ,_ ..... -/! 1/lf=. , .. ... , I -,,. I v- f---J ( I I I I I I / -,__ ,, ,, ,, ,, ' ,, , ,r I ,r li r ,. ~n. ·- --:~;,,a,~i~1a~~~~ij _..~y,.._._, • ._., ... N..,,_ __ _ ~-••~~a~aiiai~,i~s a ~=-~~~•~riNN--... --o •-,~~"~~,~~~~~a~~~ ....... " .......... ~ ...... -oo ~-!!!Sif!!!!!!~~!o "-?!!~l!!~!!!t~!~8 ,-.~~~!!~~!~~!5i!i? h !!~:!~!!~~ ~ ,za1, •• ~-~ ----0000000 --'~S?; ·-!!U ., ,-;--.. .. -_,_ :', I :T: ::=r- ,...j... ::_s_ ~ t ,._ , . -'~ I -,-.-,, ... ,, I I ,, --11 L =b ·-ii---·-7 :' ! !" -1 /:~-~ ~ ---r T I ,, 1-, --. -I ,, -,_ 1-J -= -· ~ , ~ -j.,-;, r-;;.::::;. , -~ j ,~ :; ,... ·-~ r. .,_ -. I - r ,--. :-::~-""'= I I - ,__ ~ _I '/ -t ,, I - J - I I 0 .. I --:=,-,= -I >--,_,_ -;-,--,-- ._ >- .... ,.. . ., ., ~r~o O 0 -- II .. 0 I I i- .... 0 ;.. .... -r- ++ I I tf: 11 -~ Iii . - ---I lil .. T ~ ➔ e ,_ .. W-• ·1 ... I • "' -0 404 South Live Oak Park Road Fallbrook, CA 92028 7 60 731-6603 J . j u i t f Engineering Romer/a Pointe Prellmlnary Drainage Study " te ,. 12 10 • • 10 o, o,e 07 oe OS -- - - ,_,5_1 ~, ,__,,. 01~1 .... ----~-n• 0175 ~ ~ c~= ~> P...0 RUIDENTW. STRE~ OM~ .. DIONlV I I "---v !-I j ........._ .. to -~· I --. I --....... I I I J ---~ ~,IJ L..... j .. I ........ I ~....._ I j -s... -l/ I --I I I " v ~" I _o • -! --;,." --I ~ ·• I ~ ...... i l ~ .. ), I ~ ..... J I ~ ~ 3/ t r£ i---,....~'? I ,I) --...... ~-1. f J 'r~ ~, , ... ~---1 I ....... ~'t I --I ........ l i ~, ]/ I -...i;'I r---. I J ....... ~Jr I k l '-. I ~ ..... I I r---,;.:_~lD I I ...._, I ~ I ..... .... I "· -........::..~,,, Cf. II I ~ UAMf'Ll!C Ctwo•0■10 S■J.ill, ...J ( C:~an 11"'" Doplh = U . Yoloe•y = 4 4 Ip•• ' <.JJ I ....... ....... I ....._ I -...J , .......... I ........ I .......... ~. , ... I I ~ I .......... r---.... ..... I I' 6 • 1 I I 10 n1~hnro-(Ct= A I .,... "• I I I -.......!<r L ',. It I -~ ,......___ I I ............ I ~ ........ I '--I I.. J ' ................ I I ) ~~ I I I " I ~ ,....__ .. j ..... 1 "-II I <:>"!J I. kl/ ... ~fl I ,J'~I .... , ~ ... , r---........J ,.... r--...... ~I .... , .-0 ID SOURCE San [)ego Coun!y Oepartmanl or Specilll Oisw-ct S.W:.a 0.0,, Man.al t I C, l II I' Gullwt Imel ,-OIKlwily Dh11:IMnyw • Vulu.:lly Chilrl I a-6 I 404 South Live Oak Park Road Fallbrook. CA 92028 7 60 731 -6603 IlJI Engineering Romerfa Pointe Preliminary Drainage Study Attachment E -San Diego County Point Rainfall Maps ...... OCEAN --,------j ... 1 00 Year -6 Hour Rainfall August 17, 2018 Page E-1 C:\MLB Projecls\County of Son Diego\ 17-sd:JOO Romeno Ca\Oroinage Sludy\Romerio Preliminary Drainage Study.docx IlB Engineering Romeria Pointe Preliminary Drainage Study . ~ -Cl I _,._ l\ +- +- ,.- Sc~-· c..-. . . .'\.) ~ • #. -•" , ... •·: _____ _ , # -.. . . . : ~ .. __ --r:~( --..-., ___ _ --l 100 Year -24 Hour Rainfall August 17, 2018 Page E-2 C:\MLB Projecls\Counly of Son Diego\ I 7-sd300 Romerlo Co\Drolnoge Sludy\Romena Preliminary Drainage Sludy.docx C Engineering Attachment F -TC Calculations Existing Condition Tc, Initial Area 1 Total Area = 0.623 Acres % Imp = 0% Use Natural L=231' Initial Slope > 10% Ti=6.9 Min., Lm=l00' L= 131 ', h=25' Tt=( l 1.9(L/5280)3/h)0.385 = 0.011 hrs= 0.6 min Tc=6.9 + 0.6 = 7.5 min. Romerla Pointe Preliminary Drainage Study Overland Flow The other existing area on the site is assumed to have a Tc=S min. due to the short travel lengths and small areas. The proposed areas are also assumed to have a T c=S.0 minutes due to the short travel lengths and small areas. August 17, 2018 Page F-1 C:\MLB Projects\County of San Diego\ l 7-sd300 Romeria Ca\Drainage Sludy\Romeria Prefiminary Drainage Sludy.docx Engineering Romerfa Pointe Preliminary Drainage Study Attachment G -Rational Method Calculations The Rational Method as described in the San Diego County Hydrology Manual, Section 3, (Revised June 2003) shall be used to determine storm runoff. The Rational Method formula is expressed as follows: Q=CIA Where: Q = peak discharge, in cubic feet per second (cfs) C = runoff coefficient, proportion of the rainfall that runs off the surface. The coefficient C has no units and is based on the soil group and the development type for the drainage sub-area. Attachment F includes calculations for the runoff coefficient for each drainage sub-area. I= average rainfall intensity for a duration equal to the Tc for the area, (in/Hr.) A = drainage area contributing to the design location, in acres The following values are used in the calculations: Soil Groups from San Diego County Soils Group Maps. See Attachment C. C (Coefficient of Runoff) from Table 3-l. l 00 year 6 Hr. Rainfall = 2.7" l 00 year 24 Hr. Rainfall =4.8" See calculations on the folowing pages. August 17, 2018 See Attachment D. See Attachment E. II " C:\MLB Projects\County of San Diego\ 17-sd300 Romelta Ca\Drainage Study\Romeria Preliminary Drainage Sludy.docx Page G-1 '"' Rational Method Calculation Form Project: Romeria Points Drainage Soil %Imp A Area Type Area Acres 10 D 85% 0.136 11 D 90% 0.059 12 D 72% 0.015 14 D 0% 0.010 18 D 0% 0.006 15 D 0% 0.067 16 D 81% 0.390 17 D 0% 0.030 ConflA C CA ICA I In./Hr. 0.82 0.110 0.110 7.11 0.85 0.050 0.160 6.77 0.75 0.010 0.170 6.46 0.35 0.000 0.170 6.39 0.35 0.000 0.170 6.39 0.35 0.020 0.190 6.13 0.80 0.310 0.310 7.11 0.35 0.010 0.320 7.11 ~ Frequency 100 Year Developed Condition P6=2.7 in./hr. Q Slope CFS 0.8 0.02 1.1 0.12 1.1 1.1 0.04 1.1 1.2 0.03 2.2 2.3 3.3 Section V '/Sec. 6" pipe 4 611 pipe 7 611 pipe 10 Street 3.5 L Tt Ft. Min. 90 0.4 150 0.4 75 0.1 90 0.4 Tc Min. 5.0 5.4 5.8 5.9 5.9 6.3 5.0 5.0 5.0 n Page G-2 Calculated by MB Date: 8/16/2018 Remarks Assumed -Small Area Add-In Area Add-In Area Add-In Area Add-In Area Add-In Area Assumed -Small Area Add-In Area ,, Rational Method Calculation Form Project: MUP 10-037 Drainage Soil %Imp A Area Type Area Acres 1 D 0% 0.623 2 D 0% 0.089 Confl 0.712 C CA ECA 0.35 0.220 0.220 0.35 0.030 0.030 0.35 0.250 0.250 I -" Frequency 100 Year Existing Condition P6=2.7 in./hr Q Slope Section In./Hr. CFS 5.48 1.2 7.11 0.2 5.48 1.4 V '/Sec. L Tt Tc Ft. Min. Min. 7.5 5.0 7.5 ~- Page G-3 Calculated by MB Date: 8/16/2018 Remarks See Attachment F Assumed -Small Area { I Engineering Attachment H -Hydraulic Calculations. BMP Overflow Drains: Romerla Pointe Preliminary Drainage Study The biofilter BMPs include overflow inlets that allow the larger strom events to be drained without overflowing the basins. BMP-3 has the largest QlOO peak flow at 2.2 cfs. The riser is a 24" diameter with a grate located 6" above the basin bottom and 6" below the top of the basin. The weir equation for determining the capacity of the inlet is: Q=3Lh3!2or h=(Q/3L)2l3 Wher: L = 6.28' Q = 2.2 cfs h =(2.2/{3*6.28))2'3 = 0.24' < 0.5' ✓OK Parkway Culverts: Autocad Hydraflow Express is used to determine the flow in the parkway culverts. The culvert below BMP-3 will have the highest flow of 2.2 cfs. The culverts dimensions are: Width= 2.0' Height= 4" Slope= 0.02 Peak Q l 00 = 2.2 cfs The results are on the following page. August 17, 2018 C:\MLB Projects\County of San Diego\ 17-sd300 Romelia Ca\Drainage Study\Romena Preliminary Drainage Study.docx Page H-1 lf1Il1JJ Engineering Channel Report H)dJ3llow E,qnu Ext..!sion for Autodfflte.AutoCAOI) Civil 30e by Aulodffk, Inc. Gibraltar Street Parkway Culverts Rectangular Bottom Width (ft) Total Depth (ft) Invert Elev (ft) Slope(%) N-Value Calculations Compute by: Known Q (cfs) Elev (ff) 01.00 00.75 00.50 00.25 00.00 99.75 0 August 17, 2018 - .5 = 2.00 = 0.33 = 100.00 = 2.00 = O.Q15 KnownQ = 2.20 Section .. 7 --=- 1.5 Reach (fl) Romeria Pointe Preliminary Drainage Study Highlighted Depth (ft) Q (cfs) Area (sqrt) Velocity (tt/s) Wette<1 Perim (ff) cm Depth, Ye (fl) Top Width (fl) EGL (ft) 2 2.5 Thursday, Aug 18 2018 = 0.24 = 2.200 = 0-48 = 4.58 = 2.48 = 0.33 = 2.00 = 0.57 3 Depth (ft) 1.00 0.75 0.50 0.25 0.00 -0.25 Page H-2 C:\MLB Projects\County of Son Olego\t 7-sd300 Romef\o Co\Droinoge Sludy\Romerio Preliminary Drainage Study.docx ------- ·<'::< ·--·---·-·~- Q-- --f ,_-_--_-_--' i ! ----... - -------------- D R om e 2 0,089 AC (0 SF IMP) 0%IMP ------- • r I a _,_/ I 1,;;_, __ !. D r • r v e / ' -----· / . ___ .. - 'r I. ------"'"~:....---- ' ' ' ' "· -2:. '-, ' ' ' --•·:;·-------------· ' \ -' . ' - ' . -. '. ' \\ . ' " - ' ' \' -'l. ' ' \ ' - -- ' --~- X - - '.. / ,, ':,,~-"" '>< <. ✓-', ' " ' , / / / / /4 1/ ~ Notes: • • • Underlying Hydrologic Soils Group for the entire project is Soils Group D, There are no wells, springs or watercourses on the developed project site_ The existing site is previously graded but has no impervious surfaces. Legend: Drainage Area# Area Impervios Cover % Impervious Drainage Area Boundary 0 I 0,00 AC (10 SF IMP) ------ 20 10 I I Feet Scale: 1"=10' SHEET and Lgnd S urvryors Attachment B1 Preliminary Drainage Study Romeria Pointe Existing Condition Hydrology Map 1 40;1---South Liv~0{k Park Road, :EaJ!brook, CA 92028 __./Phone 760,:/-31-6603 ___ ----_______ _ \_ E-Maj],•lv!L]l_enesn(@pacbell.net --' ,,...,, __ .-~>,,-...::_ __ ,.,--OF 1 96.1 EG 7 I I I I : 1. I l I I I I I I . I 0.136 AC ~ (5016 SF IMP) 'o '? 85% IMP ~~ ,__.,., Q100 = SD r 0.8 cfs -----~- ---,__ . ,\ i' ~c::, 'o "-"' -'-,----'",, 17 0.030 AC (0 SF IMP) 0%IMP ' ' -,., . , .. ' .. . 'I · .. ·~ .... ·. '' .. -, ... ~---· ' . . )'; 1.5 - II . II . ~ ~ 11 0.059 AC (2301 SF IMP) 90% IMP 7' ,,···· .. ' '' 6 80,2 FS/TG 16 0.390 AC (13691 SF IMP) 81% IMP 15 0,067 AC (0 SF IMP) 0%IMP • , ' ' ' "', .--'" -~/ ~/// ,,/ ,.-.. -/ / // \ \ \ ,/ \ \ \ \ Notes: • Underlying Hydrologic Soils Group for the entire project is Soils Group D. • There are no wells, springs or watercourses on the developed project site. Legend: Impervious Surface (Parking, building, sidewalk) Storm Drain Drain Inlet Drainage Area # Area Impervios Cover % Impervious Drainage Area Boundary 0 I ESSJ 1-s- ------ trj 20 10 I Feet I Scale: 1"=10' SHEET ··;:Eiigin~erin~// Professional CivjYbngineers and Lgnd Survryors Attachment B2 Preliminary Drainage Study Romeria Pointe Developed Condition Hydrology Map 1 404-South LiYe,0itk Park Road, fallbrook, CA 92028 /Phone 760 731-6603 .•· · · ,· E-M'!,i1:•K1LB,neslf@p~cbell.net ,.-' .,.,, , OF 1