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Home My WebLink AboutSDP 2019-0014; CARLSBAD OAKS NORTH LOT 2; PRELIMINARY HYDROLOGY STUDY; 2020-03-19TABLE OF CONTENTS 1.0 Project Description 1.1 Project Purpose 1.2 Project Proposed facilities 2.0 Vicinity Map 3.0 Site Map 4.0 Description of Watershed 4.1 Existing Conditions Topography 4.2 Existing Conditions + Project Conditions Topography 4.3 Hydrologic Unit Contribution 5.0 Methodology 5.1 Hydrology Software 5.2 Routing Software 5.3 Hydraulics Software 6.0 Calculations 6.1 Determine the Watershed that affects the project 6.2 Calculate Runoff Coefficient 6.3 Calculate Storm Flows using the Rational Method 7.0 Mitigation Measures 7 .1 Mitigation of Increased Runoff 7.2 Check Capacity of Existing Downstream Storm Drain Facilities 8.0 Summary 9.0 References 10.0 Declaration Of Responsible Charge 11.0 Attachments Attachment A -Site Map Attachment B -Figures & Tables from the SD Hydrology Manual 2003 Attachment C -Watershed Information Watershed Map Soils Index Map Rainfa11 Isopluvial Maps Attachment D -Previously Approved Improvement Plans Attachment E -Post Developed Q Calculations Attachment F -Post Developed Hydrology Map Hydrology Study Hydrology Study 1.0 PROJECT DESCRIPTION 1.1 Project Purpose The purpose of this project is to receive approval from the City of Carlsbad on a Site Development Plan (Minor) to construct a parking lot in Lot 2 as well as the associated infrastructure and improvements on existing 7 .52 acre parcel. 1.2 Project Proposed Facilities The project is proposing to build a parking lot with a total of 191,239 square feet of AC pavement. As part of this project, associated improvements will include the 343 parking spaces and 10% of the site will be landscaped throughout the parking areas, slopes and, frontages. All necessary utilities (storm, sewer, water, dry, etc.) will be installed as part of the project and tie into existing stubs provided for the site by City of Carlsbad DWG No. 415-9. Normal uses of such a development will generate storm water runoff with the potential to carry pollutants to off-site tributaries. Biofiltration basins are planned to be incorporated throughout the site to treat and detain runoff from impervious and landscaped areas. Carlsbad Oaks North Ventures LP C/0 TechBilt Companies 1s the recorded owner of the project sites. 2 Hydrology Study northeast corner of the site (installed as part of the Carlsbad Oaks mass grading operations). Once collected in this desiltation basin, the runoff flows through an existing storm drainage pipe to an existing storm drain structure that outlets into a storm drainage detention basin formed by the intersection of Faraday A venue and El Fuerte Street (as referenced and designed in the Rancho Carlsbad Channel & Basin Project Hydrology Study, by Rick Engineering -circa 1985). Once released from the detention basin (installed and sized to detain the future Carlsbad Oaks Business Park 100-year flows as well as runoff from the construction of Faraday Avenue) the flows are discharged into Agua Hedionda Creek back to the north of Faraday Avenue and ultimately Agua Hedionda Lagoon and the Pacific Ocean. This represents the Carlsbad Hydrologic Unit, Aqua Hedionda HA, Los Monos HSA (904.31 ). 4.2 Existing Conditions+ Project Conditions Topography The Carlsbad Oaks Lots 2 Industrial project layout proposes to install a large parking field across the site. The main drive aisle accessing the site from El Fuerte Street at the southeastern end of the site. The parking lot drains north east towards the biofiltration systems. Once within the water quality treatment systems, the stormwater infiltrates through the treatment medium into underdrains that route the flows to the private onsite storm drainage system. This system uses new piping to direct the flows to the existing storm drain structure installed as part of the Carlsbad Oaks Business Park project and ties into the existing storm drainage system within El Fuerte Street heading north toward its outfall location. As calculated below, and summarized further in Section 8, Lot 2 discharges peak 100-year flows at less than those shown on DWG No. 415-9E. On Sheet 8 of that drawing set, the Lot 2 project pipe flowrate is shown as 29.65 CFS being conveyed into the main storm drain. The existing infrastructure was sized assuming the Carlsbad Oaks Business Park pads (CT 97-13) were to be developed at a high C-factor to account for the development of the lots into industrial use. The original mass grading relied on the Rancho Carlsbad Channel & Basin Project Hydrology Study to detain the flows once they were discharged across Faraday Avenue. Drainage patterns and basin areas have been detailed and are further shown in the Attachments on the Post-Development Hydrology Basin Map. The proposed condition flowrate is 29.16 CFS, less than the allowable 29.65 CFS. 4.3 Hydrologic Unit Contribution The project site is within the Carlsbad Hydrologic Unit, Agua Hedionda HA, Los Monos HSA (904.31 ). After drainage leaves the site, it flows northeast into Agua Hedionda Creek. After undergoing detention at the control facility located at the intersection of Faraday Avenue and El Fuerte Street the flow then continues along 4 Hydrology Study Agua Hedionda Creek towards Agua Hedionda Lagoon and the Pacific Ocean south of Tamarack. 5.0 METHODOLOGY This study complies with the 2003 San Diego Hydrology Manual. The rational method as presented in Section 3 of that manual and workbook examples were followed. 5.1 Hydrology Software The "Rational Hydrology Method, San Diego County (2003 Manual)" module of the CIVILCADD/CIVIL DESIGN Engineering software version 7.9 is used in this study. This software was also used to developed hydrographs from the rational method results. This procedure also complies with the 2003 San Diego Hydrology Manual as presented in Section 6. 5.2 Routing Software No routing calculations were performed for this site at this time. Should further routing be required upon further development of the site and possible site plan changes causing discharge rates to increase above the predeveloped rates, the existing hydromodification/water quality treatment ponds can be used as flow control facilities. In order to show this is the case, Hydraflow Hydrographs 2004 by Intelisolve would then be used in this step. The hydrograph developed from the rational method is then manually entered into this software and routed into each detention pond. 5.3 Hydraulics Software The hydraulics calculations were performed on the Hydaflow Express Extension v .10.4 http://www.autodesk.com/civil3d-stonnwater. For the pipe flows on Lot 2 no increase in flows being released from the private storm drainage system at the single discharge point at the southwest comer of the site are expected versus the mass-graded (pre-developed) conditions that the infrastructure was designed for. Therefore, all downstream effects from stormwater velocities have already been accounted for by the reports and the plans approved for construction of the original Carlsbad Oaks Business Park infrastructure. 6.0 CALCULATIONS One hydrologic calculation will be done at this stage. Due to the 100-year peak flowrates already being determined for existing conditions as part of DWG No. 415-9, the only cakulation to be done as part of this report is the 100-year tlowrates expected from the postdeveloped conditions. These numbers will be used to size the proposed storm drain pipes and to doublecheck if the existing stonn drain outlet facilities are adequate. Since this project met all conditions within the parameters of the software used, no further hydraulic calculations were 5 Hydrology Study used. The capacity of the brow ditch at the south end of the site was checked to ensure it could handle the 100-year peak flow. The 100-year peak flowrates at the brow ditch is 3.01 I CFS, at this worst-case scenario the maximum depth of water would be 0.64' which is less than the provided 12" depth of the brow ditch. This is the worst case scenario, all other flows through this ditch will be less. 6.1 Determine the Watershed that affects the project Please see the "Watershed Map" in Attachment C 6.2 Calculate Runoff Coefficient Based on NRCS maps show that this project site is in type "D" soil. The previous hydrology calculations done as part of the Carlsbad Oaks infrastructure and mass grading operation also showed type "D" soils. Therefore, we are going to use all coefficients for that type of soil. As stated in section 3.1.2 of the San Diego Hydrology Manual on the second paragraph, "impervious percentage (% Impervious) as given in Table 3-1 for any area, shall govern the selected value for D." For all areas to remain pervious post-construction a "c" factor of c=0.35 is used. The remainder of the site's "c" factors will be based on the percentage of imperviousness within that subarea. The Land use chosen from table 3-1 of the San Diego Hydrology Manual (see attachment B) with a corresponding impervious area to that land use to be used in the hydrology software. 6.3 Calculate Storm Flows using the Rational Method The 100-year post developed storm flows were calculated for this project to be 29.16 CFS. These are less than those shown on the approved drawings that originally developed the pads. Please see "Post Developed Q Calculations" in Attachment E for the developed conditions. 7.0 MITIGATION MEASURES A Storm Water Quality Management Plan (SWQMP) has been prepared for this project to discuss treatment and flow control of the lower flows (2-year and 10- year). This Hydrology study analyzes the higher I 00-year flows. 7.1 Mitigate Increase Runoff As discussed above, the postdeveloped runoff rate is 29.16 CFS for Lot 2 at the outfall in El Fuerte Street. The flowratc shown on DWG No. 415-9 downstream of this project's collection point is 29.65 CFS for Lot 2 (see Attachment D). The proposed site development decreases the expected peak flows and therefore no further mitigation is required. 6 • Hydrology Study 7.2 Check Capacity of Existing Downstream Storm Drain Facilities Since peak flows are reduced, no further capacity analysis of downstream stomi drain facilities is necessary. 8.0 SUMMARY This project will not negatively impact the existing downstream storm drain facilities. The resulting I 00-year flowrates from the proposed development are less than those calculated and accounted for as part of the Carlsbad Oaks Business Park project (CT 97- 13) where pads were graded out and infrastructure installed to account for the expected development type that this site conforms to. 9.0 REFERENCES County of San Diego, Department of Public Works, Flood Control Section, June 2003 San Diego County Hydrology Manual 7 Hydrology Study ATTACHMENT B FIGURES & TABLES FROM THE SD HYDROLOGY MANUAL 2003 San Diego County Hydrology Manual Date: June 2003 Table 3-1 Section: Page: RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use Runoff Coefficient "C" Soil T·-e NRCS Elements Coun"' Elements %IMPER. A B Undisturbed Natural Terrain (Natural) Pennanent Open Space o• 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 DU/A or less 45 0.52 0.54 Medium Density Residential (MDR) 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 (HDR) Residential, 43.0 DU/A or less 80 0.76 0.77 Commercial/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 3 6 of26 C ;. D , 0.30 0.35 , >-, 0.36 '-0.41 -0.42 '-0.46 -0.45 '>-0.49 - 0.48 " 0.52 , 0.54 -,. 0.57 - " 0.57 0.60 -y 0.60 " 0.63 --0.69 -,. 0.71 -0.78 -,. 0.79 - 0.78 -,. 0.79 - 0.81 .,__ 0.82 - 0.84 '>-0.85 , 0.84 .,__ '-0.85 - 0.87 0.87 • . -h-"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 pe . . . . coefficient, Cp, for the sot! type), or for areas that will remam undisturbed m perpetuity. Justification must be given that the area will remain natural forever (e.g., the area is located in Cleveland Na1ional Forest). DU/A= dwelling units per acre NRCS = National Resources Conservation Service 3-6 11 • • • San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 12 of26 Note that the Initial Time of Concentration should be reflective of the general land-use at the upstream end ofa drainage basin. A single lot with an area of two or less acres does not have a significant effect where the drainage basin area is 20 to 600 acres. Table 3-2 provides limits of the length (Maximum Length (LM)) of sheet flow to be used in hydrology studies. Initial Ti values based on average C values for the Land Use Element are also included. These values can be used in planning and design applications as described below. Exceptions may be approved by the "Regulating Agency" when submitted with a detailed study. Element* Natural LDR LDR LDR MDR MDR MDR MDR HDR HDR N.Com G.Com O.P./Com Limited I. General I. Table 3-2 MAXIMUM OVERLAND FLOW LENGTH (LM) & INITIAL TIME OF CONCENTRATION (T;l DU/ .5% 1% 2% 3% 5% Acre LM T, LM T, LM T; LM T, LM T; 50 13.2 70 12.5 85 J0.9 100 10.3 JOO 8.7 I 50 12.2 70 11.5 85 JO.O 100 9.5 I 100 I 8.0 2 50 I 1.3 70 10.5 85 9.2 JOO 8.8 JOO ' 7.4 2.9 50 J0.7 70 10.0 85 8.8 95 8.1 100 7.0 4.3 50 J0.2 70 9.6 80 8.1 95 7.8 JOO 6.7 7.3 50 9.2 65 8.4 80 7.4 95 7.0 JOO 6.0 J0.9 50 8.7 65 7.9 80 6.9 90 6.4 JOO 5.7 14.5 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 4.2 60 3.7 70 3.1 80 2.9 90 2.6 50 4.2 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 *See Table 3-1 for more detailed description 3-12 14 10% LM T, 100 6.9 100 6.4 100 5.8 100 5.6 100 5.3 JOO 4.8 100 4.5 100 4.3 100 3.5 100 2.7 100 2.7 100 2.4 JOO 2.2 100 2.2 100 1.9 8. ,, <I) • ~ -0 ;F. 20 18 " 14 12 10 9 8 7 8 5 4 3 2 1.8 1.6 1.4 1.2 10 0.9 0.8 0.7 0.6 05 0.4 - - l-+---1.5'____,. I I+---" = .015-+ I ----------'2,2%!.._ ___ ___( i..,.; n = .0175 ~~~~~~~~~:;,;;,-1'1!%'-~;;,; Concrete --->\'to h Paved Gutter ept RESIDENTIAL STREET 0•13 ONE SIDE ONLY I I .... v, r-v' I ..::...Z.<r I ........._ "" To I I I I ·/J.s I ·/J,s -----• l"x I --'-I " I I I ' •~r--:..:v•a -----.... I ~" ~· ' ----I I ~ I ~ Ji'/ I ----I I ----- I .::, I ' V.::-6 I --1. "' ,,fl -, -I t.! ·• I '--I ~G' 4., K Ill I i'I -~ I -----r--V .::-s J I -t--c,.f:/_ t ~-s,:_t-1 r-----I ~off I - I f --rt.::-~' ---------- I I 1-------q', ,, .s.~ i,-4..,t J I I " " ti I'---.. b' I I ,s, --4."I ' I ...... v.::-Jr c:J' ......._o'I ' ~ I ' f1 ........._ ,._Ji'/ I ·/J.s oj I --I r--'c~J i I I --v • ., I I' I'-I id'3/ ,,,;-_) -.......... -Sr "' I I ·/J.s. I I ,SI ~ I ~ I "-' ,, Q~ ~ I I ' I ' I v. ---~ I --........__::: < f.JJ.s_ ----- J ~ ~v-II ----t-J --------I ,-' I ' I /'-... I '-r--/J.s. r-.... 2 3 4 5 6 7 6 9 10 20 30 40 50 Discharge (C.F.S.) EXAMPLE: Given: Q • 10 S • 2.5o/o Chart gives: Depth"' 0.4, Velocity= 4.4 f.p.s. SOURCE: San Diego County Department of Special District Services Design Manual FIGURE Gutter and Roadway Discharge ~ Velocity Chart 3-6 18 ATTACHMENT C WATERSHED INFORMATION Soils Index Map Point Rainfall Isopluvial maps Hydrology Study ATTACHMENT D PREVIOUSLY APPROVED IMPROVEMENT PLANS Hydrology Stud~, Hydrology Study ATTACHMENT E POST DEVELOPED Q CALCULATIONS Steps Taken To Analyze This Condition The Rational Method as outlined in section 3 of the June 2003 San Diego County Hydrology Manual is followed here. The software that we are using is the "Rational Hydrology Method, San Diego County (2003 Manual)" module of the CIVILCADD/CIVIL DESIGN Engineering software version 7.9. Please see the subsequent pages for the calculations. These calculations are for the QI 00. The results are outlined/summarized in Section 8. Runoff from tbis stream Time of concentration = Rainfall ir.tensity = 21.2551CFS) 8.28 min. 5.23l(In/Hr) Program is now starting with '.'-lain Stream No. 2 ++++++++++ffffffffff++++++ff+ff++f++++++++++++++++T+++++++++++++++f+f+ Process from Point/Station 201.000 to Point/Station 2C2.COC **** INITIAL AREA EVALJATION **** Decimal fraction soil group Decimal fraction soil group Decimal fraction soil group :iecimal fraction soil group [COMMERCIAL area ty,:,e (Genera: Commercial J Impervious value, Ai= 0.8~0 Sub-Area C Value= 0.820 A C. 000 B C. 000 C C. 000 C 1. 000 Initial suOarea total flow distance Highest elevation= 266.220(Ft.J Lowest elevation= 265.SlC(Ft.1 99.000(Ft.) Elevation difference= C.710(E-'t,) Slope= 0.717 \; Top of Initial Arca Slope adjusted Oy Jser to 1.202 % D/ITIAL ARE:A TIME: OF CONCENTRATION CALCULATIONS: The l'.1aximum overland flow dislance is 60.00 (Ft) for the top area slope value of General Commercial 1.20 ~, in a developnent type of In Accordance With Figure 3-3 Initial Area Time of Concentration TC= [l.8*(1.l-C)*distancelFt.)~.5)/(t TC= [l.8*(1.l-0.820C)*( 60.000".5)/I 3.67 :rinules slope" (1/3)] l.202A(l/3) )= Calculated TC of 3.672 ninules is less than 5 minutes, 3. 67 resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (1) = 7.246(In/H::.-) for a 100.C year sto::.-m Effective runoff coefficient used for area (Q=KC1A) is C = 0.820 Subarea runoff= 0.784(CFS) Total initial stream area = 0.132(Ac.l +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-++ Process fron Po.i.nl/Slalion 202.COO to Point/Station 2C3.0CO **** IRREGULAR CHAN~E:L FLOW TR/..VEL TIME: **** Estimated mean Depth of flow ~ flow rate at midpoint of channel 0.1141Ft.), Average velocity= *****•• Irregular Channel Data•••******** Inforl'.1a~ion entered for subchannel number 1 : Point number ' 2 3 'X' coordinate o.oc 30.0C 57.0C Manning's 'N' friction factor 'Y' coordinate 1.05 0.00 0.25 0.013 Sub-Channel flow 2.861 (CFS) flow top width~ 15.554(Ft.) velocity= 3.2301Ft/s) area -0.8861Sq.Ft) Froude number~ 2.385 Upstream point elevation= Downstream point elevation Flow length~ 138.COO(Ft. 265.0301Ft.) 260.000IFt. Travel time C.71 min. Time of concentration~ 4.38 min. Depth of flow -C.114(Ft.) Average velocity~ 3.230(Ft/s) Total i::.-regular channel flow - Irregular channel nornal depth Average velor:ity of channel Is) Adding area flow to channel 2.861 (CFS) above inve::.-t elev. 3.;::>J0(Ft./s) 2. 861 (CFS) 3.23C (Ft/s) 0, 114 (Ft.) CARLSBAD OAKS NORTH LOT 2 Page3of8 Calculated TC of 4.384 m'.nu-:es 's ·ess than 5 :r1nutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 7,246(In/Hr) for a lOC.0 year storm Decimal fraction soil g:::oup F<. 0.000 Decimal fraction soil g:::oup Decimal fraction soil g:::oup Decimal fraction soil g:::oup [COMMERCI11_L area type (General Cor-u-iercial Impervious value, Ai= O.B~C Sun~Area C Value= 0.820 ' 0. 000 C 0. 000 D 1. 000 Rainfall intensity = 7. 246 (In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.820 CA= 0.681 Subarea runoff= 4.153(CFS) for 0.699(Ac.) Total runoff = 4. 9n (CFS) To-:al area = Depth of flow= 0.140(Ft.), Average veloci-:y = 0.83~(Ac. 3. 702 (Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 203.000 to Point/Station 204.000 **** PlPlcl''LOW 'l'RAVtL 'Ill":!:; (User specified size) **.,...,.. Jpstrearn point/station elevation = Downstrean point/station elevation Pipe length 23.00(Ft.) Slope ~o. oi pipes= 1 Required pipe flow Given pipe size= 18.CO(In.) 258.000(Ft.) 257.890(Ft.) 0.0048 Manning's N 4. 937 (CFS) Calculated individual pipe flow 4.937(CFS) :--lornal flow depth in pipe= 10.SS(In.) Flow top width inside pipe= 17.6l(In.) Critical Depth= 10.25(In.) Pipe flow velocity= 4.42(Fl/s) Travel time through pipe= 0.09 min. Time of concentration (TC) = 4.47 min. 0.013 ++++++++++++++++++++++++++t++++++++++++.-+tt+++++++++++++++++++++++++++ P,cocess from Point/Station 204.000 to Point/Stalion 204.000 *.,..** CONFLUENCE OF ~INOR STREAMS**.,...,.. JI.long Main Stream number, 2 in nornal stream number 1 Strean flow area= 0.83111'.c.) Runoff from this stream 4.937 (CFS) Time of concentration Rainfall intensity= 4.47 min. 7 .246 (In/H:-) +++;-+++++++++tt+tt+tt++t++t++++++++++++ l +I+ I I+ I++ l++++t++++++++++++t++ Process from Point/Station 301.000 to Point/Station 302.000 *.,..** I~ITIAL AREA EVALUATION**** Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group D [UNDIS~URBED NATURAL TERRAIN (Permanent Open Space ) Impervious value, Ai -0.000 Sub-Area C Value= 0.350 0.000 0.000 0.000 1.000 Initial subarea total flow distance 106.000(Ft.) Highest elevation= 300.780(Ft.) Lowest elevation= 268.190(Pt.) Elevation difference J:>.590(Ft.) Slope= 30.745-% INITIAL AREA TIME OF CONCF.NTRATTON CALCULATIONS: The maximum overland flow distance is 1C8.00 (Ft) for the top a:-ea slope value of Permanent Open Space 30. 7!':-~, in a development type of In Acco:-dance With Figure 3-3 Initial Area Ti~e of Concentration TC -[1.!!*(l.l-C)*distance(Ft.)A.5)/("c 4. 31 minutes slope ( 1 /31 J CARLSBAD OAKS NORTH LOT 2 Page4of8 TC= [l.8*;1.1-o.3sooi•( 1co.con~.s1/( 30.745~0/3Jl= 4.31 Calculated TC of 4.309 minutes is less than 5 minutes, :::esettlng TC to 5.0 mlnutes for ra:nfall intensi:y calcu_at:ons Rainfall intensity (I) = 7.246(In/Hr) for a 100.0 year storn Effective runoff coefficient used fo::: a:::ea (Q=KCIA) is C = 0. 35C Suba:::ea runoff= 0.203(CFS) Total initial strean area = O.OSO(Ac.) +++++++-++++++++++++++++++++++++++++++++++++++++++++++++++++-+++++++++ P:::oces.s from Point/Stat:i.on 302.0CC to Point/Station 303.000 **** IRREG~LAR CHAN~EL FLOW TRAVEL TIME**** Estimated nean Depth of flow = flow rate at midpoint of channel 0.876(Ft.), Average velocity= ******* Irregular Channel Data*•********* Information entered for subchannel number 1 : Point number ' 'X' coordinate 0.00 'Y' coordinate 32.50 2 67.00 2.00 3 68.CO 0.00 4 69.00 1.00 Manning's 'N' friction facto::: C.015 Sub-Channel flow 1.641 (CFS) flow top width= 1.3H(Ft.) velocity= 2. 851 (~·t/s) area= 0.576(Sq.Ft) Froude number = 0. 759 Upstrean point elevation = Downstream point elevation Flow length= 931.000(Ft.) Travel time 5.44 min. 268.19C(Fl.) 263. 530 (Fl.) T.i.mc o( concentration = 9. 75 nin. Depth of flow= 0.876(Fl.) Average velocity= 2.851(Ft/sl Total irregular channel flow= 1.5~1(0'S) irregular channel normal depth above invert elev. Average, velocity of channel (s) Adding area flow to channel Rainfall inten&ity (I) = Decimal fraction soil group A Decimal fraction soil group B Decimal fraction soil group C Decimal fraction soil group C [JNDISTDRBED NATURAL TERRAIN (Permanent Open Space ) Impervious value, Ai~ C.CCO Sub-Area C Value = 0.35C 2. 851 (Fl/s) 4. 709 (In/Hr) o.oco 0.000 0.000 1.000 for a 1. 641 (CFS) 2.8~1 (Ft/s) C.876(Ft.) lOC.O year storri Rainfall intensity= 4.709(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = C.3SC CA= 0.639 Subarea runoff = Total runoff = Depth of flow = 2.808(CFSJ for 1.747(Ac. 3.Cll (CFS) 'I'otal area = 1.C9C(Ft.), Average velocity= l.827(Ac.) 3.394(Ft/s) t++t++t++t+++++t++t++t++t+~++*+++tt++++tttttttttttt+1+++++++ I l I I l I >l l > Process from Point/Station 303.000 to Point/Station 204.000 •••• PIPEFLOW TRAVEL TIO'!E (Use::-specified slze) *+** Upstream point/station elevation Downstream point/station elevation Pipe length 72.0C(Ft.) Slope No. of pipes = 1 Required pipe flo;.• Given pipe size~ 18.CC(In.) 760.330(Ft.) 260.170(Ft.) 0.0077 Manning's ~ 3.011 (CFS) Calculated individual pipe flow 3.011 (C"S) ~ormal flow depth in pipe= 1C.J4(Tn.) Flow top width inside pipe= 17.8E(ln.) O.Cl3 CARLSBAD OAKS NORll-1 LOT 2 Page 5 of8 Critical Depth -7.92(In,) Pipe flow velocity 2.941Ft/sl 0.41 min. Travel time through pipe= Time of concentration (TC) = 10.16 min. +++++++t++t+tt++++++++++++tt+t++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 204.0CO to Point/Station 204.000 •*•• CONFLUENCE OF MINOR STREAMS**** Along Main Stream number: 2 in nornal stream number 2 Stream flow area= 1.827(Ac.) Runoff from this stream 3.0ll(CFS) Time of concentration - Rainfall intensity - Summary of stream data: 10.16 min. 4.S86(In/Hr) St::::eam No. Flow rate (CFS) ,c (min) Rainfa_l :n:ensity (In/Hr) ' 4. 937 4 .17 I. 24 6 2 3. 011 10.16 4. 586 Qmax (1) 1. 000 1. 000 4. 937) • 1. 000 C.440 3. 011) • 6.262 Qmax (2) 0. 633 1.000 • 4. 937) l.COC 1.000 • 3. 011) • 6 .137 Total of 2 streams to confluence: Flow rates before confluence point: 4.937 3.011 Maximum flow :::ates at confluence using aoove data: 6.262 6.137 Area of streams before confluence: 0.831 1.827 Results of confluence: Total flO".; rate = 6.262 (CFS) Time of concentration 4.471 nin. Effective stream area after confluence 2.658(Ac.) ++t+tt+tt++t+++++++ + ++Jtt+tt+tt++t+++ttt I I lt++++++++++tt+tt++++++++ + + f Process from Point/Station 204.000 to Point/Station 205.000 **** PIPEFLOW TRAVEL TIME (User specified size) **** Upstream point/station elevation= Downstream point/station elevation Pipe length 456.00(Ft.) Slope No. of pipes = 1 Required pipe flow Given pipe size= 18.CC(In,) 257.790(Ft.) 2SS.870(Ft.) 0.0041 ~anning's N 6.262(CFS) Calculated individual pipe flow 6.262 (CFS) Normal flow depth in pipe= 13.7l(ln.) Flow top width inside pipe = 15. 34 (In.} Critical Depth= 11.60(In.) Pipe flow velocity= 4.33(Ft/s) Travel time through pipe= 1.79 min. Time of concentration (TC) = 6.26 min. 0. C13 ++++++++++++++++++ttttt++++++++++++++++++t++t+++++++++++++++++++++++++ Process fron Point/Station 205.000 to Point/Station 103.000 **** PIPEFLOW TRAVEL TI~F. (:Jser specified size) **** Upstream point/station elevation - Oownstream point/station elevation Pipe length 71.CO(Ft.) Slope No. of pipes -1 Required pipe flow Given pipe size= 18.00(In.) Calculated individual pipe flow 2SS.77C(Ft.) 255.SlC(Ft. 0.0037 Manning's N 6.262 (CFS) 6.262(CFSJ 0. 013 CARLSBAD OAKS NORTH LOT 2 Page6of8 Normal flow depth in pipe = Flow top width inside pipe = C1:itical Depth= ll.60(In.) 14.53(In.) 14.20(In.) Pipe flow velocity= 4.lO(Ft/s) T1:avel tine through pipe= 0.29 min. Time of concentration (TC) = 6. 55 min. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 ~••• CONFLOE~CE OF "1AIN STREAMS**** The following data inside Main Stream is listed; In Main Stream number: 2 Stream flow aree = Runoff from this strean Time of concentration = Rainfell intensity= Summary of stream data: 2.658(Ac.) 6.262(CFS) 6.~~ min. 6.086(In/Hr) Stream Ne. Flow rate (CFS) TC (min) Rainfall Intensity (In/Hr) 1 21 .255 8.28 2 6 . 262 6.55 Qmax (1) 1.000 LOCO • 21.255) 0.860 • 1. 000 6.262) Qnax 12) 1. 000 C. 791 • 21.255) 1. coo 1 .000 • 6. 262) Total of 2 main streams to confluence; Flow retes oefore confluence point: 21.255 6.262 5.23: 6.086 26.638 23.071 Maximum flow rates at confluence using above data: 26.638 23.071 Aree of streans before confluence: 4. 955 2. 658 Results of confluence; Total flow rate~ 26.638(CFS) Time of concentration 8.285 min. Effective stream area after confluence 7.613(Ac.) +++++++++tt+tt+tt+tt++t++++++++t+t+++++ft++++ ttttt + +t t +' l l I l +I+ I I+++++ Process from Point/Station 103.000 to Point/Station 104.000 **** PIPEFLOiil TRAVEL TIME {Oser specified size) **** Upstream point/station elevation = Downstream point/station elevation Pipe length 39.00(Ft.) Slope No. of pipes= 1 Required pipe flow Given pipe size= 30.00(In.) 242.530(Ft.) 239.000(Ft.) 0.0905 ~anning's N 26.638(CFS) Calculated individual pipe flow 26. 638 (CFS) Normal flow depth in pipe -9.47(In.) Flow top width inside pipe -27.89(In.) Critical Depth= 21.12(In.) Pipe flow velocity= 20.C6(Ft./s) Trevel time through pipe= C.03 min. Time of concentration (TC) = 8.32 min. 0.013 ++++++++++++++++++++t++t++t+++++++++t+++++++++++++++++++++++++++++++++ Process from Point/Station 1C4.0CO to Point/Station 104.00C **** SUBP.REA FLOW ADDITION **** Rainfall intensity (I) = 5.218 (In/Hr) for a 100.0 year storm CARLSBAD OAKS NORTH LOT 2 Page7of8 Decimal fraction soi~ group A Decimal fraction soil group B Decimal £::action soil group C Decimal fraction soil group D [LOW DENSITY RESIDENTIAL (l.0 DU/A or Less ) Impervious value, Ai= 0.100 Sub-Area C Value= 0.410 0.000 0.000 0.000 1. 000 Time of concentration= 8.32 min. Rainfall intensity= 5.218{In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.689 CA= 5.589 Subarea runoff= Total 1:unoff = 2.524(CFS) for 0.499(Ac.) 29.162(CFS) To::al area End of computations, total study area = 8 .112 8.L2(Ac. !Ac.) CARLSBAD OAKS NORTH LOT 2 Page 8 of 8 Hydrology Study ATTACHMENT F POST DEVELOPED HYDROLOGY MAP