Loading...
The URL can be used to link to this page
Your browser does not support the video tag.
Home
My WebLink
About
CT 2022-0003; CARLSBAD BY THE SEA SUMMERHOUSE; PRELIMINARY DRAINAGE STUDY; 2023-12-01
PRELIMINARY DRAINAGE STUDY for FRONT PORCH MEMORY CARE & INDEPENDENT LIVING CT 2022-0003/CUP 2022-0014/CDP 2022-0047 SDP2022-0011 (DEV2022-0063) APN: 2031440400, 2031440500, 2031440600, 2031440700, 2031440800 2710, 2720, 2730 & 2740 OCEAN STREET CARLSBAD, CA 92008 Prepared By: 9449 Balboa Avenue, Suite 270 San Diego, CA 92123 BWE Job #: 13913U Date: November 2022 Rev: January 2023 Rev: May 2023 Rev: August 2023 Rev: December 2023 B \V E 1 TABLE OF CONTENTS 1. Purpose……………………………………………………………………....page 1 2. Background………………………………………………………………… page 1 3. Existing Conditions………………………………………………………… page 1 4. Proposed Improvements………………………………………………….… page 2 5. Soil Characteristics…………………………………………………….…….page 2 6. Methodology……………………………………….……………..…………page 3 7. Calculations …………………………………………………………………page 5 7.a. Impervious and Pervious Areas ……………………………………….. page 5 7.b. Runoff Coefficient ………………………………………………….…. page 5 7.c. Peak Flow Rates …………………………………………………….… page 6 7.c.1 Onsite Hydrology Analysis 7.c.2 Offsite Hydrology Analysis 7.c.3 Offsite Hydraulic Analysis 8. Downstream Drainage Impact Analysis …………...………………………page 10 9. Conclusions…..……………………………………………………….….. page 11 10. References ……………………………………………………………..…. page 12 Attachments Site Vicinity Map……….……………………………………………… Attachment A Site Imagery Map Existing Condition Runoff Coefficient Calculations.…………..……... Attachment B Existing Condition Hydrology Calculations Existing Condition Hydrology Map Proposed Condition Runoff Coefficient Calculations.…..……..….….. Attachment C Proposed Condition Hydrology/Hydraulic Calculations Proposed Condition Hydrology Map Excerpts from Hydrology Manual………….………………………..….Attachment D FEMA Flood Plain Map……………….………………………………...Attachment E Offsite Hydrology & Hydraulic Analysis………………………………..Attachment F CT 04-22; Ocean Estates Properties; Drainage Study; …………...…….Attachment G Record Drawings………………………….…………………………….Attachment H 2 1. Purpose The purpose of this drainage study is to analyze the existing and proposed conditions drainage patterns, and peak flow rates for the Front Porch Memory Care & Independent Living in the City of Carlsbad. To determine the impacts of the proposed development on the existing drainage patterns, the pre- and post-peak flow rates are analyzed and compared for the 100-year storm event using the Rational Method. This report has been prepared in accordance with the requirements of the County of San Diego Hydrology Manual (2003). 2. Background The 0.62 acre parcels, are located in the City of Carlsbad, California. The site is bounded by Garfield Street on the east, Ocean Street on the west, Beach Avenue on the northwest and existing development on the southeast. (See Attachment A for Vicinity & Imagery Maps) The Federal Emergency Management Agency (FEMA) categorizes the site as Zone X, where Zone X is area determined to be outside of 500-year floodplain. Attachment E illustrates the FEMA floodplain mapping within the vicinity of the project site. The proposed development is located outside of the existing 100-year flood plain limits. Further, site is located within multiple residential (R-3) Zone (townhouses, condominiums, and apartments at a density of up to 16 dwelling units per gross acre) per the City of Carlsbad Zoning map. 3. Existing Condition The existing site is currently vacant and comprised of mostly pervious area. The existing site topography is relatively flat with the elevations ranging from 52’ to 42’ above Mean Sea Level. Site slopes from the east to the west towards Ocean Street. Runoff from the majority site area surface flows to the Ocean Street prior to discharging to the existing curb inlet situated at the intersection of Beach Avenue and Ocean Street. Existing curb inlet is connected to a 18” storm drain system (detention system) situated within Ocean Street Right of Way which discharges site runoff to a network of existing storm drain system near the intersection of Christian Way and Ocean Street. The runoff from the site ultimately discharges to the Pacific Ocean via an existing storm drain system situated within Ocean Street. The hydrology of the drainage area within the project boundary can be generally analyzed at one discharge point which is shown graphically in the existing condition hydrology map. Same discharge point is utilized for offsite hydrology analysis. See Attachment B for Existing Condition Hydrology Map. 3 4. Proposed Improvements The proposed development comprised of construction of a new Front Porch Memory Care & Independent Living Facility. The on-site drainage pattern will be altered slightly in the proposed condition without altering the discharge location at the offsite location. Runoff from the site is captured and conveyed via new storm drain system before being piped to the existing curb inlet & 18” storm drain system situated within Ocean Street Right of Way. The hydrology of the drainage area within the project boundary can be generally analyzed at one discharge point as in the existing condition. Same discharge point is utilized for offsite hydrology analysis. See Attachment C for Proposed Condition Hydrology Map. 5. Soil Characteristics The site is comprised of hydrologic soil group B per the County of San Diego Hydrology Manual. Therefore, hydrologic calculations are performed by assuming soil type “B” for this site. See Attachment D for Soil Map. 4 6. Methodology Rational Method: A rational method is utilized to perform hydrologic calculations in this study; Rational Equation: Q = C * I * A Where; Q = Peak discharge, cfs C = Rational method runoff coefficient I = Rainfall intensity, inch/hour A = Drainage area, acre A computer model CivilD is used to automate the hydrology analysis process. This computer version of the rational method analysis allows user to develop a node-link model of the watershed. CivilD computer program has the capability of performing calculations utilizing mathematical functions. These functions are assigned code numbers, which appear in the printed results. The code numbers and their corresponding functions are described below; Sub area Hydrologic Processes; Code 1 - INITIAL subarea input, top of stream Code 2 - STREET flow through subarea, includes subarea runoff Code 3 - ADDITION of runoff from subarea to stream Code 4 - STREET INLET + parallel street & pipe flow + area Code 5 - PIPEFLOW travel time (program estimated pipe size)** Code 6 - PIPEFLOW travel time (user specified pipe size) Code 7 - IMPROVED channel travel time (open or box)** Code 8 - IRREGULAR channel travel time** Code 9 - USER specified entry of data at a point Code 10 - CONFLUENCE at downstream point in current stream Code 11 - CONFLUENCE of mainstreams **NOTE: These options do not include subarea runoff **NOTE: (#) - Required pipe size determined by the hydrology program 5 7. Calculations 7.a. Impervious and Pervious Areas The impervious and pervious areas are calculated for both the existing and proposed site conditions. Impervious area in the proposed condition is increased by 0.55 acres as shown in Table 7-1. Table 7-1 Summary of Areas Area (Acres) Percent Impervious Area Percent Pervious Area Total Imperviou s (Ai) Perviou s (Ap) Existing 0.62 0.00 0.620 0.0% 100.0% Proposed 0.62 0.55 0.070 88.7% 11.3% Percentage Change 0.0% -88.7% 7.b. Runoff Coefficient A conservative assumption is made to determine the runoff coefficient for the site in the existing condition. For onsite area: The runoff coefficients for the site are manually calculated by using the equation from Section 3.1.2 of the County of San Diego Hydrology Manual: C = 0.90 x (% Impervious) + Cp x (1 - % Impervious) Where, Cp = 0.25, Pervious Coefficient Runoff Value for the soil type B (per Table 3-1 of the County of San Diego Hydrology Manual for Undisturbed Natural Terrain/Permanent Open Space, and 0% Impervious). (See Attachment D for details). The equivalent land use type is determined for the site based on the runoff coefficients calculated by using above equation and utilized for the initial basin analysis. Composite runoff coefficients of 0.25 and 0.83 are used for existing and proposed conditions respectively. See existing & proposed conditions runoff coefficient calculations in Attachments B & C respectively. For combined onsite & offsite areas: Runoff coefficients are determined separately for onsite and offsite drainage areas and utilized in the hydrology analysis. Runoff coefficient for offsite area “B” remains unchanged from 0.80 but 6 onsite drainage area “A” changed due to the proposed development. C factor for onsite area increased from 0.25 in the existing conditon to 0.80 in the proposed condition. See existing & proposed conditions runoff coefficients calculations in Attachment F. 7.c. Peak Flow Rates 7.c.1 Onsite Hydrology Analysis: The rational method procedure is used to perform the hydrologic analysis. The existing and proposed conditions peak flow rates for the 100 year storm event are calculated and summarized in Table 7-2 for comparison purpose. The detailed calculations/results for existing and proposed conditions are included in Attachments B and C respectively. Table 7-2 Existing and Proposed Conditions Peak Flow Rates Comparison Drainage Area (acres) 100 Yr Flow (cfs) % Change from Existing Condition Existing Condition Proposed Condition Existing Condition Proposed Condition (Unmitigated) Change from Existing Analysis/Exit Point 1 0.62 0.62 1.00 3.40 2.40 140.00 Drainage Area (acres) 10 Yr Flow (cfs) % Change from Existing Condition Existing Condition Proposed Condition Existing Condition Proposed Condition (Unmitigated) Change from Existing Analysis/Exit Point 1 0.62 0.62 0.65 2.17 1.52 133.85 Peak flow rates in the proposed condition are increased from the existing condition by 2.40 & 1.52 cfs respectively for 100 and 10-yr storm events. Increase in peak flow rate is mainly due to increase in impervious area from the current state of the site (pervious with vegetation). Mitigation of onsite peak flow rate is not provided after analyzing the findings of the offsite hydrology analysis. Mitigation of onsite peak flow rate was provided by utilizing 18” pipe detention constructed within Ocean Street Right of Way. I I 7 7.c.2 Offsite Hydrology Analysis: BWE reviewed an existing drainage report for the Ocean Estate Properties prepared by Alta Consultants dated August 2007. Two major POCs (northerly and southerly) were analyzed in the study. According to the approved drainage report runoff from the site was surface flowing north to an existing inlet situtated near the intersection of Oean Street and Cypress Avenue. But, in the proposed condition, runoff from the site was diverted south by installing 18” storm drain pipe detention within Ocean Street Right of Way. Mitigation of onsite peak flow rate was provided by utilizing partly 18” pipe detention and partly by street detention. Approximately, 700 cf of storage volume was provided via 357.0’ of 18” pipe and 405 cf storage from street detention for this purpose. Actual construction of this detention system is verified from the City of Carlsbad as-built drawing no# 432-3 for Ocean Estates Project. See Attachment F for relevant record drawings. The pre and post-development 100 yr peak flow rates from the watershed (=0.92 ac) were determined to be 2.42 cfs and 5.13 cfs respectively. But, for the project limit (=0.62 ac) the peak flow rates were determined to be 1.40 cfs and 3.29 cfs respectively. The peak 100-year flow rate increase due to the development was 2.71 cfs and approximately 1,105 cf of detention volume would be required to maintain the existing condition peak flow rate of 2.42 cfs. The required detention volume of 1,105 cf was provided partly from 18” storm drain pipe and partly from above ground storage (storage within street crown and curb of Ocean Street fronting the site). See Attachment G for relevant drainage study and figure-1 below for drainage basins & outfall locations. Figure -1: Snip from approved drainage study 8 BWE also performed current condition offsite hydrology analysis to analyze the impact of the onsite drainage to the downstream storm drain system as requested by the City. Only the southerly storm drain sytem where site runoff is currently discharging is analyzed in this study. In the existing condition the onsite storm water runoff is discharged to an existing curb inlet near the intersection of Ocean Street and Beach Avenue via a new onsite storm drain system. Existing curb inlet at his location also captures runoff from offsite areas (runoff from Ocean Street and Beach Avenue Right of Ways). Total drainage area of 1.15 ac is tributary to this curb inlet including onsite as well as offsite tributary drainage areas. Peak 10 and 100-year flow rates are calculated at the curb inlet location and results are summarized in table 7-3 below. Table 7-3 Existing and Proposed Conditions Peak Flow Rates Comparison Area (acres) 100 Yr Flow (cfs) 10 Yr Flow (cfs) Existing/Proposed Condition Existing Condition Proposed Condition (Unmitigated) Existing Condition Proposed Condition (Unmitigated) Analysis/Exit Point 1 1.15 3.82 6.10 2.42 3.85 Peak flow rates in the proposed condition are increased from the existing condition by 2.28 (= 60%) & 1.43 (=60%) cfs respectively for 100 and 10 year storm events. The peak flow rate increase is mainly due to the increase in impervious area in the proposed condition. See Attachment F for offsite hydrology analysis. 7.c.3 Offsite Hydraulic Analysis: Existing 18” pipe/detention system constructed within Ocean Street Right of Way is connected to a southerly existing 18” storm drain system utilizing a type A-8 cleanout with an internal weir & orifice to control the peak flow rate from the proposed site. Drainage area diversion was proposed and approved by the City knowing that the existing system was deficient to convey peak 100-yr flow rate and additional flow couldn’t be added to this system. The existing storm drain system was determined to be undersized for the 100-year storm event. Therefore, mitigation of onsite flow rate alone wouldn’t improve the capacity issue of the existing receiving storm drain system during 100-year storm event. Existing 18” storm drain system is also analyzed for both 10-year and 100-year peak flow rates to determine the conveyance capacities of the system. Downstream control HGLs are set to 42.37’ for 100-year and 40.76’ (weir crest elevation) for 10-year storm event HGL analysis. These control HGLs are obtained from the City’s approved as-built plans of the Ocean Estate Project and the approved drainage report. Based on the available information the existing 18” storm drain system is found to be pressurized for both 10- year and 100-year storm events. In addition, the conveyance capacity of the 18” pipe is 9 impacted/reduced drastically due to the 3.45’ high internal weir constructed inside the type A-8 storm drain cleanout for the purpose of peak flow rate attenuation. See attachment G for relevant drainage study and figure-2 below for HGLs information & existing draiange layout Figure -2: Snips from approved drainage study -APPROXIMATE TOP OF E !STING 10" ACP WATER MAIN [JJ __._ -·---· ~ SE 10 Hydraulic analysis of the existing 18” storm drain system revealed that the system is deficient to convey the peak 100-year flow rate both in the existing and proposed conditions. But, system is found to be adequate to convey the peak flow rate due to 10- year storm event both in the existing and proposed conditions. Existing type B curb inlet (4’ opening) and 18” storm drain system situated with Ocean Street are analyzed by utilizing the calculated peak flow rates for 10 and 100-year storm events. The existing type B inlet is located in sump condition and found to be adequately sized to capture the peak 10 & 100-year flow rates. Only caveat is that ponding depth at the inlet location is higher (7.55”) than the inlet opening (=6”) for peak 100-year flow rate of 6.10 cfs. Therefore, during 100-year storm event a partial inundation of the Ocean Street is anticipated. See Attachment F for offsite hydraulic analysis. 8. Downstream Drainage Impact Analysis The onsite drainage pattern will change minimally due to the proposed development. But, existing drainage pattern of the watershed is preserved in the proposed condition. Runoff from the onsite and offsite aeras concentrates to an existing curb inlet situated near the intersection of Ocean Street and Beach Avenue prior to being conveyed south via an existing 18” storm drain system as in the existing condition. The existing storm drain system situated within Ocean Street is found to be deficient to convey the peak 100-year flow rate from the onsite and offsite areas without exceeding the system capacity. All pipe segments are pressuraized due to peak 100-year storm event. This is true for both existing and proposed site conditions. Existing 18” storm drain pipe at the outfall location is found to be a main bottleneck for the drainage system. 11 9. Conclusions Storm water runoff from the site is collected and conveyed by a system of downspouts, inlets, planters, and storm drain pipes. The proposed development mitigates the storm water quantity impacts to the maximum extent practicable using the best management practices. The existing condition drainage pattern changed slightly in the proposed condition but the discharge location is preserved. Slight increase in peak flow rates for both 10-year and 100-year storm events is anticipated due to the proposed development which would require onsite detention of peak flow rates. Per the approved drainage report peak flow rate mitigation was provided for the site by utilizing 18” pipe detention situated within Ocean Street Right of Way. A total detention volume of 1,105 cf was provided for this purpose. Detention volume was provided partly by utilizing 18” pipe and prtly from above ground storage (street detention). Eventhough the peak flow rate mitigation was provided for the previously proposed development of the site detention credit is applied to this development. Below is the summary of peak flow rate mitigation provided in the previously proposed development of the site for peak 100-year flow rates. Area (acres) 100 Yr Flow (cfs) Existing Condition Proposed Condition (Unmitigated) Difference Analysis/Exit Point 1 Watershed Boundary for Proposed Project 0.62 1.00 3.40 2.40 Watershed Boundary for Previous Project 0.92 2.42 5.13 2.71 Peak 100-year flow rate increase at analysis point 1 due to the previously proposed development is 2.71 cfs (=5.13-2.42). But, from table 7-3 it is determined that the peak 100-year flow rate increase at the same analysis point due to the currently proposed development is 2.28 cfs (=6.10-3.82 cfs). Based on this analysis peak flow rate mitigation required for the later development is smaller than the mitigation required for the previously proposed development. Therefore, onsite detention of peak flow rate is not provided. An offsite hydrology & hydraulic analysis was also performed to determine the impact of the proposed development to the existing receiving drainage system. This study reveals that the existing southerly receiving storm drain system had capacity issues prior to the construction of 18” pipe detention system within Ocean Street Right of Way. Existing storm drain system was not designed to contain 100-year HGL below flow line of the curb & gutter at the inlet locations and accept any additional peak flow rates. 100-year HGL at the existing type B inlet structure situated near the intersection of Ocean Street and Christiansen Way is found to be too high (=43.0’). This is due to an undersized 18” outlet pipe which is pressuraized during peak 100-year flow rate of 35.0 cfs (City of Carlsbad Drawing No. 347-2). At this structure location 36” storm drain pipe and 18” 12 pipe merge to an 18” outlet pipe which discharges flow to the Pacific Ocean Shoreline. 18” storm drain pipe at 26.0% slope is deficient to convey the design peak 100-year flow rate of 35.0 cfs. Capacity issue of the existing receiving drainage system was a concern and will continue to be a concern specially for the peak 100-year flow rate. By matching/maintaining onsite peak flow rate will not solve this issue. Existing 18” outlet pipe to Pacific Ocean Shoreline is found to be deficient and needs to be upgraded to alleviate the existing capacity issue. 10. References · County of San Diego, Hydrology Manual (2003). · CT 04-22; OCEAN VISTA ESTATES; DRAINAGE STUDY; 2007-08-01 · Record Drawings for Ocean Estates Project ATTACHMENT A: Site Vicinity Map Site Imagery VICINITY MAP SITE LOCATION achAcc ssC, os! rra La~dscap ft Construe 10n T p Armyand O Navy Academy Y 0 .. .., .. 8 Magee Park Carlsbad City Beach q 9 Publ1r Beach Access campf11e f Carlsbad VillagelEJ Uni d States A Postal Service T ,. ar m1ama 004 °s ' -Buns -Carlsbad S.Hand~ls Homemade T ce Cream State Stree ~ Farm ·s Mark T Pizza Port Carlsbad ' Bl -v ott Grill ' IMAGERY MAP SITE LOCATION ATTACHMENT B: Existing Conditions Runoff Coefficient Calculations Existing Condition Hydrology Calculations Existing Conditions Hydrology Map Runoff Coefficient Calculation (Existing Condition) Project: Front Porch Soil Type:D C =0.90 × (% Impervious) + Cp × (1 - % Impervious) Cp=0.25 (per table 3-1, County of San Diego Hydrology Manual, Soil Class B) Total Area (ac) Imp. Area (Ai) A 0.62 0.00 0 0.25 Undisturbed area Total 0.62 Notes: *The composite runoff coefficient (C) is calculated for the site by using the following equation: 0.90 × (% Impervious) + Cp × (1 - % Impervious); where Cp = 0.35 per Table 3-1 of the County of San Diego Hydrology Manual. **The composite runoff coefficient (C) calculated for the site and entered back into table 3-1 to determine a more appropriate land use to be used as an input to the CivilD software. Use this value only for initial basin where C cannot be entered directly. Basin # Area (Acres) %imp *Runoff Coef. (C ) **Equivalent Land Use (from Table 3-1) San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2012 Version 7.9 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 11/01/22 ------------------------------------------------------------------------ EXISTING CONDITION HYDROLOGY ANALYSIS EXIT POINT 1 FRONT PORCH - 100YR ANALYSIS ------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Program License Serial Number 6116 ------------------------------------------------------------------------ Rational hydrology study storm event year is 100.0 English (in-lb) input data Units used Map data precipitation entered: 6 hour, precipitation(inches) = 2.500 24 hour precipitation(inches) = 4.500 P6/P24 = 55.6% San Diego hydrology manual 'C' values used ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [UNDISTURBED NATURAL TERRAIN ] (Permanent Open Space ) Impervious value, Ai = 0.000 Sub-Area C Value = 0.250 Initial subarea total flow distance = 86.000(Ft.) Highest elevation = 49.300(Ft.) Lowest elevation = 45.000(Ft.) Elevation difference = 4.300(Ft.) Slope = 5.000 % Top of Initial Area Slope adjusted by User to 38.889 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 100.00 (Ft) for the top area slope value of 38.89 %, in a development type of Permanent Open Space In Accordance With Figure 3-3 Initial Area Time of Concentration = 4.52 minutes TC = [1.8*(1.1-C)*distance(Ft.)^.5)/(% slope^(1/3)] TC = [1.8*(1.1-0.2500)*( 100.000^.5)/( 38.889^(1/3)]= 4.52 Calculated TC of 4.516 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.250 Subarea runoff = 0.082(CFS) Total initial stream area = 0.050(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** IRREGULAR CHANNEL FLOW TRAVEL TIME **** ______________________________________________________________________ Estimated mean flow rate at midpoint of channel = 0.153(CFS) Depth of flow = 0.153(Ft.), Average velocity = 2.184(Ft/s) ******* Irregular Channel Data *********** ----------------------------------------------------------------- Information entered for subchannel number 1 : Point number 'X' coordinate 'Y' coordinate 1 0.00 0.50 2 1.50 0.00 3 3.00 0.50 Manning's 'N' friction factor = 0.020 ----------------------------------------------------------------- Sub-Channel flow = 0.153(CFS) ' ' flow top width = 0.917(Ft.) ' ' velocity= 2.184(Ft/s) ' ' area = 0.070(Sq.Ft) ' ' Froude number = 1.392 Upstream point elevation = 45.000(Ft.) Downstream point elevation = 43.000(Ft.) Flow length = 70.000(Ft.) Travel time = 0.53 min. Time of concentration = 5.05 min. Depth of flow = 0.153(Ft.) Average velocity = 2.184(Ft/s) Total irregular channel flow = 0.153(CFS) Irregular channel normal depth above invert elev. = 0.153(Ft.) Average velocity of channel(s) = 2.184(Ft/s) Adding area flow to channel Rainfall intensity (I) = 6.545(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [UNDISTURBED NATURAL TERRAIN ] (Permanent Open Space ) Impervious value, Ai = 0.000 Sub-Area C Value = 0.250 Rainfall intensity = 6.545(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.250 CA = 0.034 Subarea runoff = 0.140(CFS) for 0.086(Ac.) Total runoff = 0.223(CFS) Total area = 0.136(Ac.) Depth of flow = 0.176(Ft.), Average velocity = 2.398(Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Rainfall intensity (I) = 6.545(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [UNDISTURBED NATURAL TERRAIN ] (Permanent Open Space ) Impervious value, Ai = 0.000 Sub-Area C Value = 0.250 Time of concentration = 5.05 min. Rainfall intensity = 6.545(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.250 CA = 0.068 Subarea runoff = 0.221(CFS) for 0.135(Ac.) Total runoff = 0.443(CFS) Total area = 0.271(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 104.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Rainfall intensity (I) = 6.545(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [UNDISTURBED NATURAL TERRAIN ] (Permanent Open Space ) Impervious value, Ai = 0.000 Sub-Area C Value = 0.250 Time of concentration = 5.05 min. Rainfall intensity = 6.545(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.250 CA = 0.155 Subarea runoff = 0.571(CFS) for 0.349(Ac.) Total runoff = 1.014(CFS) Total area = 0.620(Ac.) End of computations, total study area = 0.620 (Ac.) San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2012 Version 7.9 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 02/03/23 ------------------------------------------------------------------------ EXISTING CONDITION HYDROLOGY ANALYSIS EXIT POINT 1 FRONT PORCH - 10 YEAR STORM ------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Program License Serial Number 6116 ------------------------------------------------------------------------ Rational hydrology study storm event year is 10.0 English (in-lb) input data Units used Map data precipitation entered: 6 hour, precipitation(inches) = 1.600 24 hour precipitation(inches) = 3.000 P6/P24 = 53.3% San Diego hydrology manual 'C' values used ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [UNDISTURBED NATURAL TERRAIN ] (Permanent Open Space ) Impervious value, Ai = 0.000 Sub-Area C Value = 0.250 Initial subarea total flow distance = 86.000(Ft.) Highest elevation = 49.300(Ft.) Lowest elevation = 45.000(Ft.) Elevation difference = 4.300(Ft.) Slope = 5.000 % Top of Initial Area Slope adjusted by User to 38.889 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 100.00 (Ft) for the top area slope value of 38.89 %, in a development type of Permanent Open Space In Accordance With Figure 3-3 Initial Area Time of Concentration = 4.52 minutes TC = [1.8*(1.1-C)*distance(Ft.)^.5)/(% slope^(1/3)] TC = [1.8*(1.1-0.2500)*( 100.000^.5)/( 38.889^(1/3)]= 4.52 Calculated TC of 4.516 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.250 Subarea runoff = 0.053(CFS) Total initial stream area = 0.050(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** IRREGULAR CHANNEL FLOW TRAVEL TIME **** ______________________________________________________________________ Estimated mean flow rate at midpoint of channel = 0.098(CFS) Depth of flow = 0.129(Ft.), Average velocity = 1.953(Ft/s) ******* Irregular Channel Data *********** ----------------------------------------------------------------- Information entered for subchannel number 1 : Point number 'X' coordinate 'Y' coordinate 1 0.00 0.50 2 1.50 0.00 3 3.00 0.50 Manning's 'N' friction factor = 0.020 ----------------------------------------------------------------- Sub-Channel flow = 0.098(CFS) ' ' flow top width = 0.776(Ft.) ' ' velocity= 1.953(Ft/s) ' ' area = 0.050(Sq.Ft) ' ' Froude number = 1.354 Upstream point elevation = 45.000(Ft.) Downstream point elevation = 43.000(Ft.) Flow length = 70.000(Ft.) Travel time = 0.60 min. Time of concentration = 5.11 min. Depth of flow = 0.129(Ft.) Average velocity = 1.953(Ft/s) Total irregular channel flow = 0.098(CFS) Irregular channel normal depth above invert elev. = 0.129(Ft.) Average velocity of channel(s) = 1.953(Ft/s) Adding area flow to channel Rainfall intensity (I) = 4.155(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [UNDISTURBED NATURAL TERRAIN ] (Permanent Open Space ) Impervious value, Ai = 0.000 Sub-Area C Value = 0.250 Rainfall intensity = 4.155(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.250 CA = 0.034 Subarea runoff = 0.089(CFS) for 0.086(Ac.) Total runoff = 0.141(CFS) Total area = 0.136(Ac.) Depth of flow = 0.148(Ft.), Average velocity = 2.140(Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Rainfall intensity (I) = 4.155(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [UNDISTURBED NATURAL TERRAIN ] (Permanent Open Space ) Impervious value, Ai = 0.000 Sub-Area C Value = 0.250 Time of concentration = 5.11 min. Rainfall intensity = 4.155(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.250 CA = 0.068 Subarea runoff = 0.140(CFS) for 0.135(Ac.) Total runoff = 0.282(CFS) Total area = 0.271(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 104.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Rainfall intensity (I) = 4.155(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [UNDISTURBED NATURAL TERRAIN ] (Permanent Open Space ) Impervious value, Ai = 0.000 Sub-Area C Value = 0.250 Time of concentration = 5.11 min. Rainfall intensity = 4.155(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.250 CA = 0.155 Subarea runoff = 0.363(CFS) for 0.349(Ac.) Total runoff = 0.644(CFS) Total area = 0.620(Ac.) End of computations, total study area = 0.620 (Ac.) 9449 BALBOA AVE, STE 270SAN DIEGO, CA 92123 619.299.5550 BWE JOB NO. 13913US1.00 "' ~ ill N N N N 0 N ;:;- '-- 0 0 0 C> + SMH " " o I FOU~REEr SURVl,,Y MONUM~~T ...----:wrrff BRASS ~SC stAMRED "LS) 6929" 1-----, PER ROS 16521 O I n~ I SL ----So ':>"+ I T + I I I ~ I ~'·+ ,I I ,I I ' I I I I I I I I <.> 8 I I 111'-_.__ I 1 I ,. 11 GUY w ::::, z I, 111~------ w > <( 45 :r: u ,j<~+ w w (D I ===-----1=---- + ____ __. I I Ii I I 11 11 ----J,-------.., ,. '· I _..J I \ w ' rs I[) lO I" I[) I[) z ASPH GARFIELD STREET ~ ~()·+ + ------------------------ so---------- DRIVEWAY • + N34"03'03"W 200.07' I I I LOT 2 ASPH + DRIVEWAY LOT 5 MAF 1563~ + CONC I 9.30FS I I I I I A-1 0.05 4S ________ j _________ _l _____ -?-------------45---;=------- (kJj ~ I ~ 8 "J ~·+ @ ¥ ¥ -~ ~ ~·+ ,: / ✓ ( ( ~ ' ::\<:,· -..;f v! ✓ ; ,I ' I ' ASPH I I I j I EXISTING BUILDING T ~~1-~,~-~~=-,~~~~-c-~~-~~-=--~-:::..-~WMj-~_::--~~-~--~-j-2-::-:-~-~-:::-:::'.'.!-~-~~~~1':_~-~~-::-".!V:~j~~~~=::-~-~-==:::-=::-~-~-~wj_~ 1 ~~~o.::;:~~-~-~-~-~'!!~M~-~-~-~-=:.:-~-~-:=:;:-~-~-~·~-~-~-:-;-~~==· 0 ::;::=L~-~ON:;:~F0::~:~-~3/::~. :l;~ON~-P~IP~:~~-~~-~3-~-~ ~~----- FOUND LEAD AND DISC WITH DISC STAMPED "LS 6287 OCEAN STREET STAMPED "LS 7432 Tl " PER ROS 18012 ON CURB PER .CR-'.34507 \ ~"' ~-+~ < Q. i.'I,· + 0 I [:;l 0 'I ~ \ i.'I,· + \ i.'I,· + ASPH 'b ASPH i.'I,· + ' k"J·+ ------ Sise ____________ J --10 I '\. ~"J·' LEGEND OUTER BASIN BOUNDARY MAJOR BASIN BOUNDARY MINOR BASIN BOUNDARY EXISTING STORM DRAIN EXISTING CONTOUR FLOW DIRECTION FLOW PATH FLOW LENGTH NODE ELEVATION HYDROLOGY NODE ANALYSIS/EXIT POINT DRAINAGE BASIN MARKER & AREA (AC) 5 0 ~ SYMBOL --------------so-- ----xxx __ __ .. L=XX.X' --..___313.00FL 310.00IE @ & / ' 10 20 I I SCALE: 1"=10' B\V E CIVIL •STRUCTURAL• SURVEY• PLANNING 30 I O' o_ "' w Cc D z 0 E O' u (f) w D w Cc 0 w => U) (f) w ~ C-e= ~ w I U) c-u w ~ 0 O' o_ >-' DJ z ~ O' 0 "" w O' DJ w "' DJ => 2 z >-' => DJ z DJ 0 0 DJ ~ w 0 "" ~ c-u z w w w I °" :::J u DJ u z I:::: 0 CD I-:E ->< ~w 0~ () 0 c:, _J zo b5 a: -0 >< >-w :r: w a: <( () ~ 0 :::i!: ~ w 0 :::i!: ~ I ~ () a: 0 a... I-z 0 a: LL O' w DJ "" i'= => :::J z <( c-9c u uw -~ zo => er "'o_ (f) (f) w er 0 0 « w t= (f) LL 0 c-w w :r: CD "' 0 >-"' wa> w<C lc:u V) • z □ <(<( w"' UVJ 012 <( u 9449 BALBOA AVE, STE 270SAN DIEGO, CA 92123 619.299.5550 BWE JOB NO. 13913US1.00 ,,-n u: ... I--I 1-,. ,. -' •• I t- ~ -= - @ I I,. 'I r,. -,. ,. ,. .,_ I I I t t I I I I I GARFIELD ------= ;; i. • ,. i- • ,. .-- • I A=1.15 W:, 100=3.82 CFS Q10=2.42 CFS ,,. ,. ,. -- • .... ,. ,. - \ -,. ~ t • t - •· < ' I -,1 ,!- /■ I I ,. ..,_" • ~r-=--"'7 <'i-- -E-k--_,. EXIST. 18" SD DETENTION PIPE CAPW:.ITY L=700 CF (PER AS BUILT DWG NO 432-3) • - l,Ll ,. ,. : ,. \ I I (f.-. I \ I I I I ' EXIST. INLET~• Q100=6.79 CFS \ -~-' - I j I j I I I I 1--"'-- I • #y l 1. I j I I I I I ~ u~ \ I I I >--1 I I r -" I j j I I I I (1 I -<( 1._J ~ I I I I j j z w 1/) z w >-I/) °" :r: u1 I EXIST. lYPE A-8 (/) 0 CLEANOUT WITH WEIR & RIFICE AT BOTTOM (PER AS BUILT DWG NO 432-3) j I qs XIST. 36" SD EXIST. TYPE B INLET ;;pr l I I El OS-- 100= 35.0 CFS ~ r-1--(PER AS BUILT DWG NO 432~ I LEGEND OUTER BASIN BOUNDARY MAJOR BASIN BOUNDARY MINOR BASIN BOUNDARY FLOW DIRECTION FLOW PATH FLOW LENGTH NODE/CONTOUR ELEVATION HYDROLOGY NODE DRAINAGE BASIN MARKER & AREA (AC) POINT OF ANALYSIS 30 15 0 / 30 60 90 ~I~ l __ lf---------11 SCALE: 1 "=30' SYMBOL ------------- L=XXX.X' 306.43' B\V E CIVIL• STRUCTURAL •SURVEY• PLANNING (9 0 L L 1~-(" LJ := ,~, :,;-----;-," --) '·, _u o--;:,-c..:::_:I '.~ ,=: =l <l i:::o r·, r~1 < '..._j I I ,::::, LL c· , =~-,f-u~ ~ 1 1-1 LJ ~ :fJ r1 :'".:; :,11 LJ (j D 7 ::_, --y ~ -=--- z t::: -om~ !:::::: I 00 ~iii~ 8~+ c::, g ~ zo-1-a: 00 00 0 LL -LL >< >-0 WI......, <( w Cl) w w Cl) I ::::> 1--o a >-I - ma: i 0 w _. <( ~ ~ m~ Cl) ::::> _J Cl) a: (5 N ATTACHMENT C: Proposed Conditions Runoff Coefficient Calculations Proposed Condition Hydrology/Hydraulic Calculations Proposed Conditions Hydrology Map Runoff Coefficient Calculation (Proposed Condition) Project: Front Porch Soil Type:D C =0.90 × (% Impervious) + Cp × (1 - % Impervious) Cp=0.25 (per table 3-1, County of San Diego Hydrology Manual, Soil Class B) Total Area (ac) Imp. Area (Ai) A 0.62 0.550 89 0.83 Commercial Total 0.620 Notes: *The composite runoff coefficient (C) is calculated for the site by using the following equation: 0.90 × (% Impervious) + Cp × (1 - % Impervious); where Cp = 0.25 per Table 3-1 of the County of San Diego Hydrology Manual. Basin # Area (Acres) %imp *Runoff Coef. (C ) **Equivalent Land Use (from Table 3-1) San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2012 Version 7.9 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 11/02/22 ------------------------------------------------------------------------ PROPOSED CONDITION HYDROLOGY ANALYSIS EXIT POINT 1 FRONT PORCH - 100YR ANALYSIS ------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Program License Serial Number 6116 ------------------------------------------------------------------------ Rational hydrology study storm event year is 100.0 English (in-lb) input data Units used Map data precipitation entered: 6 hour, precipitation(inches) = 2.500 24 hour precipitation(inches) = 4.500 P6/P24 = 55.6% San Diego hydrology manual 'C' values used ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (Office Professional ) Impervious value, Ai = 0.900 Sub-Area C Value = 0.840 Initial subarea total flow distance = 21.000(Ft.) Highest elevation = 103.000(Ft.) Lowest elevation = 100.000(Ft.) Elevation difference = 3.000(Ft.) Slope = 14.286 % Top of Initial Area Slope adjusted by User to 15.000 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 100.00 (Ft) for the top area slope value of 15.00 %, in a development type of Office Professional In Accordance With Figure 3-3 Initial Area Time of Concentration = 1.90 minutes TC = [1.8*(1.1-C)*distance(Ft.)^.5)/(% slope^(1/3)] TC = [1.8*(1.1-0.8400)*( 100.000^.5)/( 15.000^(1/3)]= 1.90 Calculated TC of 1.898 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.840 Subarea runoff = 0.055(CFS) Total initial stream area = 0.010(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 100.000(Ft.) Downstream point/station elevation = 99.600(Ft.) Pipe length = 42.00(Ft.) Slope = 0.0095 Manning's N = 0.013 No. of pipes = 1 Required pipe flow = 0.055(CFS) Nearest computed pipe diameter = 3.00(In.) Calculated individual pipe flow = 0.055(CFS) Normal flow depth in pipe = 1.76(In.) Flow top width inside pipe = 2.95(In.) Critical Depth = 1.70(In.) Pipe flow velocity = 1.87(Ft/s) Travel time through pipe = 0.37 min. Time of concentration (TC) = 2.27 min. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 102.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.272 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.27 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.832 CA = 0.033 Subarea runoff = 0.164(CFS) for 0.030(Ac.) Total runoff = 0.219(CFS) Total area = 0.040(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 99.600(Ft.) Downstream point/station elevation = 98.400(Ft.) Pipe length = 60.00(Ft.) Slope = 0.0200 Manning's N = 0.013 No. of pipes = 1 Required pipe flow = 0.219(CFS) Nearest computed pipe diameter = 6.00(In.) Calculated individual pipe flow = 0.219(CFS) Normal flow depth in pipe = 2.16(In.) Flow top width inside pipe = 5.76(In.) Critical Depth = 2.82(In.) Pipe flow velocity = 3.46(Ft/s) Travel time through pipe = 0.29 min. Time of concentration (TC) = 2.56 min. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.561 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.56 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.831 CA = 0.116 Subarea runoff = 0.547(CFS) for 0.100(Ac.) Total runoff = 0.766(CFS) Total area = 0.140(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.561 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.56 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.831 CA = 0.133 Subarea runoff = 0.109(CFS) for 0.020(Ac.) Total runoff = 0.875(CFS) Total area = 0.160(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.561 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.56 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.830 CA = 0.274 Subarea runoff = 0.929(CFS) for 0.170(Ac.) Total runoff = 1.805(CFS) Total area = 0.330(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.561 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.56 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.830 CA = 0.365 Subarea runoff = 0.601(CFS) for 0.110(Ac.) Total runoff = 2.406(CFS) Total area = 0.440(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.561 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.56 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.830 CA = 0.407 Subarea runoff = 0.273(CFS) for 0.050(Ac.) Total runoff = 2.680(CFS) Total area = 0.490(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 104.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 98.400(Ft.) Downstream point/station elevation = 97.800(Ft.) Pipe length = 60.00(Ft.) Slope = 0.0100 Manning's N = 0.013 No. of pipes = 1 Required pipe flow = 2.680(CFS) Nearest computed pipe diameter = 12.00(In.) Calculated individual pipe flow = 2.680(CFS) Normal flow depth in pipe = 7.77(In.) Flow top width inside pipe = 11.47(In.) Critical Depth = 8.42(In.) Pipe flow velocity = 4.98(Ft/s) Travel time through pipe = 0.20 min. Time of concentration (TC) = 2.76 min. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 104.000 to Point/Station 104.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.762 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.76 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.830 CA = 0.515 Subarea runoff = 0.711(CFS) for 0.130(Ac.) Total runoff = 3.390(CFS) Total area = 0.620(Ac.) End of computations, total study area = 0.620 (Ac.) San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2012 Version 7.9 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 02/03/23 ------------------------------------------------------------------------ PROPOSED CONDITION HYDROLOGY ANALYSIS EXIT POINT 1 FRONT PORCH-10 YEAR STORM ------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Program License Serial Number 6116 ------------------------------------------------------------------------ Rational hydrology study storm event year is 10.0 English (in-lb) input data Units used Map data precipitation entered: 6 hour, precipitation(inches) = 1.600 24 hour precipitation(inches) = 3.000 P6/P24 = 53.3% San Diego hydrology manual 'C' values used ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (Office Professional ) Impervious value, Ai = 0.900 Sub-Area C Value = 0.840 Initial subarea total flow distance = 21.000(Ft.) Highest elevation = 103.000(Ft.) Lowest elevation = 100.000(Ft.) Elevation difference = 3.000(Ft.) Slope = 14.286 % Top of Initial Area Slope adjusted by User to 15.000 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 100.00 (Ft) for the top area slope value of 15.00 %, in a development type of Office Professional In Accordance With Figure 3-3 Initial Area Time of Concentration = 1.90 minutes TC = [1.8*(1.1-C)*distance(Ft.)^.5)/(% slope^(1/3)] TC = [1.8*(1.1-0.8400)*( 100.000^.5)/( 15.000^(1/3)]= 1.90 Calculated TC of 1.898 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.840 Subarea runoff = 0.035(CFS) Total initial stream area = 0.010(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 100.000(Ft.) Downstream point/station elevation = 99.600(Ft.) Pipe length = 42.00(Ft.) Slope = 0.0095 Manning's N = 0.013 No. of pipes = 1 Required pipe flow = 0.035(CFS) Nearest computed pipe diameter = 3.00(In.) Calculated individual pipe flow = 0.035(CFS) Normal flow depth in pipe = 1.34(In.) Flow top width inside pipe = 2.98(In.) Critical Depth = 1.34(In.) Pipe flow velocity = 1.67(Ft/s) Travel time through pipe = 0.42 min. Time of concentration (TC) = 2.32 min. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 102.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.316 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.32 min. Rainfall intensity = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.832 CA = 0.033 Subarea runoff = 0.105(CFS) for 0.030(Ac.) Total runoff = 0.140(CFS) Total area = 0.040(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 99.600(Ft.) Downstream point/station elevation = 98.400(Ft.) Pipe length = 60.00(Ft.) Slope = 0.0200 Manning's N = 0.013 No. of pipes = 1 Required pipe flow = 0.140(CFS) Nearest computed pipe diameter = 6.00(In.) Calculated individual pipe flow = 0.140(CFS) Normal flow depth in pipe = 1.70(In.) Flow top width inside pipe = 5.41(In.) Critical Depth = 2.23(In.) Pipe flow velocity = 3.04(Ft/s) Travel time through pipe = 0.33 min. Time of concentration (TC) = 2.65 min. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.645 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.65 min. Rainfall intensity = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.831 CA = 0.116 Subarea runoff = 0.350(CFS) for 0.100(Ac.) Total runoff = 0.490(CFS) Total area = 0.140(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.645 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.65 min. Rainfall intensity = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.831 CA = 0.133 Subarea runoff = 0.070(CFS) for 0.020(Ac.) Total runoff = 0.560(CFS) Total area = 0.160(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.645 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.65 min. Rainfall intensity = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.830 CA = 0.274 Subarea runoff = 0.595(CFS) for 0.170(Ac.) Total runoff = 1.155(CFS) Total area = 0.330(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.645 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.65 min. Rainfall intensity = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.830 CA = 0.365 Subarea runoff = 0.385(CFS) for 0.110(Ac.) Total runoff = 1.540(CFS) Total area = 0.440(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.645 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.65 min. Rainfall intensity = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.830 CA = 0.407 Subarea runoff = 0.175(CFS) for 0.050(Ac.) Total runoff = 1.715(CFS) Total area = 0.490(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 104.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 98.400(Ft.) Downstream point/station elevation = 97.800(Ft.) Pipe length = 60.00(Ft.) Slope = 0.0100 Manning's N = 0.013 No. of pipes = 1 Required pipe flow = 1.715(CFS) Nearest computed pipe diameter = 12.00(In.) Calculated individual pipe flow = 1.715(CFS) Normal flow depth in pipe = 5.87(In.) Flow top width inside pipe = 12.00(In.) Critical Depth = 6.68(In.) Pipe flow velocity = 4.49(Ft/s) Travel time through pipe = 0.22 min. Time of concentration (TC) = 2.87 min. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 104.000 to Point/Station 104.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 2.868 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm User specified 'C' value of 0.830 given for subarea Time of concentration = 2.87 min. Rainfall intensity = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.830 CA = 0.515 Subarea runoff = 0.455(CFS) for 0.130(Ac.) Total runoff = 2.170(CFS) Total area = 0.620(Ac.) End of computations, total study area = 0.620 (Ac.) Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Nov 3 2022 SD LINE 1- 12 INCH @ 1 PERCENT SLOPE Circular Diameter (ft)= 1.00 Invert Elev (ft) = 10.00 Slope (%)= 1.00 N-Value = 0.013 Calculations Compute by:Known Q Known Q (cfs) = 2.65 Highlighted Depth (ft)= 0.65 Q (cfs)= 2.650 Area (sqft)= 0.54 Velocity (ft/s)= 4.89 Wetted Perim (ft) = 1.88 Crit Depth, Yc (ft) = 0.70 Top Width (ft)= 0.95 EGL (ft)= 1.02 0 1 2 3 Elev (ft)Depth (ft)Section 9.50 -0.50 10.00 0.00 10.50 0.50 11.00 1.00 11.50 1.50 12.00 2.00 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Nov 3 2022 SD LINE 2- 8 INCH @ 1 PERCENT SLOPE Circular Diameter (ft)= 0.66 Invert Elev (ft) = 10.00 Slope (%)= 1.00 N-Value = 0.013 Calculations Compute by:Known Q Known Q (cfs) = 0.75 Highlighted Depth (ft)= 0.39 Q (cfs)= 0.750 Area (sqft)= 0.21 Velocity (ft/s)= 3.56 Wetted Perim (ft) = 1.16 Crit Depth, Yc (ft) = 0.41 Top Width (ft)= 0.65 EGL (ft)= 0.59 0 1 Elev (ft)Section 9.75 10.00 10.25 10.50 10.75 11.00 Reach (ft) S S S S S S S S S S S S S S S S G G G G G G G G G G S S S S S S S S S S S S S S S S W W W W W W W W W W W W W WWW W W W W W W W W W W WWW S S S S S S W SS W SS S OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OH E OHE OHE W S S S S S S S S S W W W W W W W W W W FW FW S S S IRRG IRRG IRRG IRRG IRRG IRRG IRRG IRRG IR R G W SD SD SDSDSDSD SD SD SD SD SD SD SD SD SD SD SD SD SD SD SD S FW IRR W SD SD SD SD SD SD SD SD S SD 7.00' 5. 0 0 ' 10.05'2.95' 6.00' 6.00' W W W W W W W W W W SD S D 44 43 42 40 39 38 37 36 35 33 51 50 51 9449 BALBOA AVE, STE 270SAN DIEGO, CA 92123 619.299.5550 BWE JOB NO. 13913US1.00 z u: SMH ,. + MH---' IE 1--52:--t-~ CONC ENCASED SWR ---s .LI ~ ,,., co Cl 4 3:: 0 z ~ • <Xl z 0 0 z a5 ?.:. -- 0 0 ,I- -~- CONC Ii'' + 0 SMH 42.03RIM 31.14IE NC CRADLEC32.?'i..) a. 195-3Z GARFIELD ST ASPH ASPH GARFIELD STREET ~ ~()·tt 1+ + ·s.<J~r'ie7'dil-sr\-r a-G-. 2~ ~ G) (50.00EG) => ,,>j7'11F--,;:,;,.;,-'k:'7-:r-,;, J'../Y.. DRIVEWAY TION PER 347~2 DRI\IEW . (49A3EG)l DRIVE ,Y • (5C .17EG')j , •. • •. •. • .• 48.99EG)'-1 . . .•· .. ··~·(?.~· .. · . .-.. _.·.-._ ··:~·- ·_\-.\'· :~l-. ~_;_;~-~·~):~\-.------__ -• -.-.-_---.-. •• ~·~:··, ""'rsci.01 : J~: •. .-.: •. /49.79EG),__,...., '. • •. '.. •. •• • 0 "--(49.77EG) _71 G =-,;1 ---..,~ ·~~' --'~-"-'-"--l'T--~ ~-, •••• _ I<~-... :,\. ( . ( 48.98EG)c I< ~·+ t I t I I ·( 4s.44EG) --------I 2.103.00FS -(47.9 :.~--------------1111-■i~-------------.. ii----·@ ,------------~--------- ~\ I< I ~~+ i@1 1~01 I ~~+ ~\ --------r------- 1 ~·+ I J ' ', . , ·., . '. ~ ·,. •. ·. , ' .. . . . . . : __ -1 ... ·. ·.··-. 0 ,(4 i :;3EG). . ' . . . . . . . . ' • ', '. ,. '. '. " ' , " . -r -. . . -- ',. I ••• A-2 ~-+ f •• 0.01 ~II M"P • (47.43EG) -., ,._.. 'i~,_,. ·lJ=~;;;;;;-----0.03,__ ___ •47 I ~ l 1S63C3 11111 -( 46.99EG) I l I @/:9.60FS I ~101 1100.00FS L=42.00' ■ ~ bi; ..;-..,_ ..;-..;-..;-..;--<ac-..,_ ..,_ -,_ ..;- ..;--~ ..,_____I 1 'lli -ialif,1111 -~--------------~ -----------..,_ ---?+ --IP+ I -( 46.14EG) TRENCH ORAi A=0.06 AC 0100=0.35 CFS ( 45.17EG) -@-----,------{]) I< ~· I ------:: LOT -1 --© 0--0--- •. • ' ( 45 60EG) I t I ( 44.84EG) 1------SD LINE #2 . 1 ;_ . . t • . •. '.( 8" @ 1 % , --....,; -1',fl)s.½''----.. ... '-,. . . . · .. , , " ., . " . -' . 45 ------© ,>\~ ~ 44-,.,__ " . '. POST ~ ~-.. ( 44.00EG)--._, 1 ( 43. 96EG) ( 45 17EG)7 L ( 45.17 Gl~ ,I Ill! 7 1 •. . . ----- 2 -·~ _..,-.. . . . -' . LOT] 3~·+ I i I ~---1 5 TO SUMP I I I ____ J SUMP PUM A=0.12 AC 01 00= 0. 70 CFS t ' .. ·, ' " ~-v,,1-• .• .,--~- 18" PIPE DETENTION , + ~~-"--,-~-" l .. , • --,,-;'-,-'-,--L-,.L,~.L, ·•· •• ·._ • .• .. , G) --·-· .. .. • ( 42.96EG) ---.:>, i-;;;r==;~t 6~t.·f 88':Ai MA_IN_________ ------------------------l I 0.11 ,_____,,,,) + t l I II 1c,l.., J I • l c:------c-- I I I . I I I I /~ ---+--_.!.~_-_ ...... .---===,.~-6==+---l""l=t----1-1--------- EXISTING BUI DI G ---++--EXISTING BUILDING EXISTING BUILDING LEGEND OUTER BASIN BOUNDARY MAJOR BASIN BOUNDARY MINOR BASIN BOUNDARY EXISTING STORM DRAIN EXISTING CONTOUR -4"--.J..1!.......!I FLOW DIRECTION FLOW PATH FLOW LENGTH NODE ELEVATION HYDROLOGY NODE ANALYSIS/EXIT POINT DRAINAGE BASIN MARKER & AREA (AC) SYMBOL --------------so-- ----xxx_ _ -- .. L=XX.X' ----..._313. OOFL 310.00IE @ & EXISTING BUILDING ===10 5 0 10 20 30 ~I ~~f----1 __ 1----11 ---SCALE: 1''=10' B\V E CIVIL •STRUCTURAL• SURVEY• PLANNING EXISTING BUILDING ~ ' -- - '' ~ I :r, <( w z 0 E 0 z 0 (.) 0 w Cl) 0 a_ 0 a: a_ I:::: CD -I >< w ~ 0 __J 0 a: 0 >-I Cl) w w Cl) I ::::> I-0 <( >-Io_ ma: i 0 w _. <( ~ ~ m~ Cl) ::::> _J Cl) a: (5 N ,, ,:._} ~ ,. ' w I V' SD SD SD SD SD S 4.00'4.00' W W W 9449 BALBOA AVE, STE 270SAN DIEGO, CA 92123 619.299.5550 BWE JOB NO. 13913US1.00 u: , __ ; z 2: ~ • J I I I I / t r- I I I I t . 8.24FS t I @ I ~ I I <;; 5 I 'fp l ·o. I l I I I I -----t ~ '-. ~ ' • \ I I - \ \ 6.50FL I f \ ~\~ ·\QJ]l I ~f •. 1i l.b~;~~~~1 ~~~~~\~~-~~~==:=r~~/~~~ ( l I I " T I T ----I~ - j I I • ~1 ~-~B~ •-~=e==~~~~Q.~62~~~~G~~=~,Jti' ------,- 1 J-'i _ tfiif ~lU~ _ li/2111·. . ;·,•-,. . .. ,,, :- I I I II I I I I \ ', I \ " EXIST. INL~~ 1 Q100=6.79 CFS~ I .A A=1.15 AC - --..,... ..,.... ..,.... ..,.... ..,.... ..,.... ..,.... +---Ll,3i Q100-6.10 CFS --..,.... Q10=3.85 CFS l-1'1F=-_..,F.': I EXIST. 18" SD ~---0 ETENTION PIPE CAPACITY VOL=700 CF (PER AS BUILT DWG NO 432-3) j ~ l j l j I l --. I I I I j j I I l l I j l <fl 0 I \ I I j j EXIST. TYPE A-8 CLEANOUT WITH WEIR & RIFICE AT BOTTOM (PER AS BUILT DWG NO • 432-3) 30 15 0 ~I~ LEGEND OUTER BASIN BOUNDARY MAJOR BASIN BOUNDARY MINOR BASIN BOUNDARY FLOW DIRECTION FLOW PATH FLOW LENGTH NODE/CONTOUR ELEVATION HYDROLOGY NODE DRAINAGE BASIN MARKER & AREA (AC) POINT OF ANALYSIS / 30 60 90 1 __ 1-------11 SCALE: 1 "=30' SYMBOL --------------. L=XXX.X' 306.43' @ ® .X B\V E CIVIL• STRUCTURAL •SURVEY• PLANNING - : / i L L 1~-(" LJ := ,·, :,;-----;-," --) '·, _u ._ D ""?" L I -,=: =:J <l CO r·, r~1 < '..._j I I ,::::, LL •• , _u=--,f--::u~ ~-< i?r 1-1 LJ ~ =:-:;..,,? -' " ":_<-_:;: :,11 CJ (j D ~-=--- z I::: Qm ~--:::c 0 ><-~ w ~ 0 ~ Cl) 0 0 LL l:H _Jo ~ 0 -a,_ a: ~ ~ a,_ <( w Cl) w w Cl) I ::::> I-0 <( >-Io_ ma: i 0 w _. <( ~ ~ m~ Cl) ::::> _J Cl) a: (5 v: v: L c::: C' C. <( L I (/""; N ~ ,, ' w I V' ATTACHMENT D: Excerpts from Hydrology Manual 243 of 249 San Diego County Hydrology Manual Date: June 2003 SECTION 3 Section: Page: RATIONAL METHOD AND MODIFIED RATIONAL METHOD 3.1 THE RATIONAL METHOD 3 I of26 The Rational Method (RM) is a mathematical formula used to determine the maximum runoff rate from a given rainfall. It has particular application in urban storm drainage, where it is used to estimate peak runoff rates from small urban and rural watersheds for the design of storm drains and small drainage structures. The RM is recommended for analyzing the runoff response from drainage areas up to approximately 1 square mile in size. It should not be used in instances where there is a junction of independent drainage systems or for drainage areas greater than approximately 1 square mile in size. In these instances, the Modified Rational Method (MRM) should be used for junctions of independent drainage systems in watersheds up to approximately 1 square mile in size (see Section 3.4); or the NRCS Hydrologic Method should be used for watersheds greater than approximately 1 square mile in size (see Section 4). The RM can be applied using any design storm frequency ( e.g., 100-year, 50-year, I 0-year, etc.). The local agency determines the design storm frequency that must be used based on the type of project and specific local requirements. A discussion of design storm frequency is provided in Section 2.3 of this manual. A procedure has been developed that converts the 6-hour and 24-hour precipitation isopluvial map data to an Intensity-Duration curve that can be used for the rainfall intensity in the RM formula as shown in Figure 3-1. The RM is applicable to a 6-hour storm duration because the procedure uses Intensity-Duration Design Charts that are based on a 6-hour storm duration. 3.1.1 Rational Method Formula The RM formula estimates the peak rate of runoff at any location in a watershed as a function of the drainage area (A), runoff coefficient (C), and rainfall intensity (I) for a duration equal to the time of concentration (Tc), which is the time required for water to 3-1 24 4 o f 2 4 9 \ I 10 - 0 Lbt~ 1 1 I 1111 trn1mnlmmml 111 LI m1lmummm111I I I 11111 I 11111 I 1111111111111 , •• -·1 11 111111 9°~1:tt~I 8.0 j N'N I :u~1ii1111111111111111111111, C 74~°e~~,~~5 5.0 ' = Intensity (in/hr) 6-Hour Precipitation (in) 4.0 i1-rr,,==Duration (min) 3.o l---+--P~-++-l~H++N-1f-++i"!<:-!+fr4+H~~Hd--~ffi~±t+H+trnlttt-+--t-+t+rrt+titititlitttttt11tt L~~~ " N ' I "',,. "'"' r ~~ 1 ~"' ~ I 1r 'n-...~ .. " I I I I 11 1 11111 11111111 I : ri--. ' I ~ I'~ ~ " ,-. ... 2.0 .... I' ~~ I . , r--, .., °' I'.,... ,,,.. ~ ' ' • ,,,.. i ,....... 'i,. I,, ' 0 I .... ,.._ ' ~ IT ' " 1' ' ' I' C ..... I ~ I ' r--. ...,,.. ~/~ ~ :5 'i--~~ '"'..t ' i--.,,.. ""'""'"~ ~ ~ ro O "" I I ~ r-,. ' ,-. ~ O ~ "'"~ I , '-... ,,.. ~ 6.0 °R a., ~ .., "" ~ ~ 5.5 !!?. L I', I" -.~ 1.0 ~ ,-.. -. ~ ~ 5.0 §l ;:o.9 "" I ~ 4.5 5" -~ ' (") -~ 0.8 • -. ~ ~ 4.0 ~ ~ 07 1111111111~1~ I I r..., r" "' ~ .. 3·5 ~ ,... ' 0 6 ..,_ ', 1 111 1 I IN!I 3 0 • 1 1 111 Ill 1111,ii llll l I J ll ll1I N.lil lllllllll lllll .., " • 1111 . o.51 I I I I I I I I I I 1 1 111 ,~ 111 1 ..., 01I I I I I I I I I I I IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIB I I lllUUlrrtillll 2 • 5 !'HJ .,,_ 0.3 021 I I I I I I I I I I II II 111111111111111'11111111111111 i II 111!1111111!111111 I I I I I I I I I I I I I ll't$W:1:1ffi11 ,-..,-..,-,._,f-t-1-i-l _,_,-l-l-l-o- 0.1 • I l I l I I I I I I I 111I I 11111111111 11,) 11111 1 1111 ·1111 1fll 1ll[l t I I I I ' I I I 1111 11111'1, 5 6 7 8 9 10 15 20 30 Minutes 40 50 Duration 2 3 Hours 4 5 6 2.0 1,5 1.0 Intensity-Duration Design Chart -Template Directions for Application: (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. Application Form: (a) Selected frequency ___ year p (b) P6 = __ in., P24 = __ .~ = %(2) 24 (c) Adjusted P6<2) = __ in. (d) tx = ___ min. (e) I= ___ in./hr. Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. P6 1 -1 1.5 ~ 2 2.5 3 : 3.5 1 4 -4.5 5 ~-5.5 l 6 Duration I I I I I I I I I I I _j ~~3 _3.9sl 5.21_. 6.59. 1.90 9.22110.54 11.86 13. 11 , 14.49115.81 r 2.12 ,3.18,4.24_5.3076.36,7.42 8.48 ,9.54 10.60,11.6612.12 10 1,68 .~.53+ 3.~. 4.21 . 5.05 5.90, 6.74 . 7.58 ~ 8.42 ➔ 9.271 10.11 15 1.30 1.95.._2.59 3.24 3.89 4.54 . 5.19 5.84 6.49 7.13 7,78 20 Toa 1.52 2.15 • 2.69).23 /3.n :_4-1.1 _ 4.85 1 5.39; 5.93 6.46 25 0.93 1.40 1.87 2.33 2.80 3.27 3.73 4.20 4.67 5.13 5.60 30 0.83 1.24 1,66 2.07 2.49 2.90 3.32 3.73 4.15 ➔ 4.56 j 4.98 40 0.69 ·1.03 1.38 1.12·2.01 2.41 2.76 3.10 3.45 3.79 4.13 1 so o.60 ).90. 1.19: 1.49 ·1.79 ,2.09 2.39 2.69 2.98 • 3.28 3.58 60 0.53 0.80 1.06 1.33 1.5911.86 2.12 2.39 2.65 2.92 3.18 90 0.41 ·0.61; 0.821 1.02 1.23 1.431 1.63 1.84 j 2.04 '. 2.25 2.45 120 0.34 0.51 0.68 0.85 1.0211.19 1.36 1.53 1.70 1.87 2.04 1?0 _ 0.29 :o.44 , o.59 : o.73 . o.88 1.03 j 1.10 • 1.32 1.47 ; 1.62 1.76 180 0.26 _0.39,_0.52 ,0.65 ,0.78 0.91 f 1,04 , 1.18 , 1.31 , 1.44 _1.57 240 o.~_o.33.0.43 _0.54 o.65 ,0.76 o.87 o.98 , 1.00 1.19 1.30 300 0.19 _0.28:0,38" 0.47 ,0.56 ,0.66, 0.75 , 0.85 0.94 , 1.03 1.13 360 0.17 0.25 0.33 0.42 0.50 0.58 0.67 0.75 0.84 0.92 1.00 IF '~-UlR El 245 of 249 San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 3 of26 flow from the most remote point of the basin to the location being analyzed. The RM formula is expressed as follows: Where: Q=CIA Q peak discharge, in cubic feet per second ( cfs) C = runoff coefficient, proportion of the rainfall that runs off the surface (no units) I average rainfall intensity for a duration equal to the Tc for the area, in inches per hour (Note: If the computed Tc is less than 5 minutes, use 5 minutes for computing the peak discharge, Q) A drainage area contributing to the design location, in acres Combining the units for the expression CIA yields: (lacrexinch) (43,560ft2] ( lfoot ) ( lhour ) ⇒ 1.oogcfs hour acre 12 inches 3,600 seconds For practical purposes the unit conversion coefficient difference of 0.8% can be ignored. The RM formula is based on the assumption that for constant rainfall intensity, the peak discharge rate at a point will occur when the raindrop that falls at the most upstream point in the tributary drainage basin arrives at the point of interest. Unlike the MRM (discussed in Section 3.4) or the NRCS hydrologic method (discussed in Section 4), the RM does not create hydrographs and therefore does not add separate subarea hydrographs at collection points. Instead, the RM develops peak discharges in the main line by increasing the Tc as flow travels downstream. Characteristics of, or assumptions inherent to, the RM are listed below: • The discharge flow rate resulting from any I is maximum when the I lasts as long as or longer than the Tc, 3-3 246 of 249 San Diego County Hydrology Manual Date: June 2003 Section: Page: • The storm frequency of peak discharges is the same as that ofl for the given Tc• 3 4 of26 • The fraction of rainfall that becomes runoff ( or the runoff coefficient, C) is independent of I or precipitation zone number (PZN) condition (PZN Condition is discussed in Section 4.1.2.4 ). • The peak rate of runoff is the only information produced by using the RM. 3.1.2 Runoff Coefficient Table 3-1 lists the estimated runoff coefficients for urban areas. The concepts related to the runoff coefficient were evaluated in a report entitled Evaluation, Rational Method "C" Values (Hill, 2002) that was reviewed by the Hydrology Manual Committee. The Report is available at San Diego County Department of Public Works, Flood Control Section and on the San Diego County Department of Public Works web page. The runoff coefficients are based on land use and soil type. Soil type can be determined from the soil type map provided in Appendix A. An appropriate runoff coefficient (C) for each type of land use in the subarea should be selected from this table and multiplied by the percentage of the total area (A) included in that class. The sum of the products for all land uses is the weighted runoff coefficient (1:[CA]). Good engineering judgment should be used when applying the values presented in Table 3-1, as adjustments to these values may be appropriate based on site-specific characteristics. In any event, the impervious percentage (% Impervious) as given in the table, for any area, shall govern the selected value for C. The runoff coefficient can also be calculated for an area based on soil type and impervious percentage using the following formula: 3-4 San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 5 of26 Where: C = 0.90 x (%Impervious)+ Cr x (1 -% Impervious) Cr = Pervious Coefficient Runoff Value for the soil type (shown in Table 3-1 as Undisturbed Natural Terrain/Permanent Open Space, 0% Impervious). Soil type can be determined from the soil type map provided in Appendix A. The values in Table 3-1 are typical for most urban areas. However, if the basin contains rural or agricultural land use, parks, golf courses, or other types of nonurban land use that are expected to be permanent, the appropriate value should be selected based upon the soil and cover and approved by the local agency. 249 of 249 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 of a 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;) DU/ .5% 1% 2% 3% 5% Acre LM Ti LM T; LM Ti LM T; LM Ti 50 13.2 70 12 .5 85 10.9 100 10.3 100 8.7 1 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 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 10% LM Ti 100 6.9 100 6.4 100 5.8 100 5.6 100 5.3 100 4.8 100 4.5 100 4.3 100 3.5 100 2.7 100 2.7 100 2.4 100 2.2 100 2.2 100 1.9 24 8 o f 2 4 9 ) I-w w LL z 0 w 0 z <l'. I-Cf) 0 w Cf) 0::: ::::, 0 (.) 0::: w I-<l'. s: 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)VD JVs 20 10 Cf) w I-:::, z ~ ~ w ~ ~ ~ 0 _J LL 0 z :5 O:'. w > 0 FIGURE Rational Formula -Overland Time of Flow Nomograph I 3-3 I San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 11 of26 The sheet flow that is predicted by the FAA equation is limited to conditions that are similar to runway topography. Some considerations that limit the extent to which the FAA equation applies arc identified below: • Urban Areas -This "runway type" runoff includes: I) Flat roofs, sloping at I% ± 2) Parking lots at the extreme upstream drainage basin boundary (at the "ridge" of a catchment area). Even a parking lot is limited in the amounts of sheet flow. Parked or moving vehicles would "break-up" the sheet flow, concentrating runoff into streams that are not characteristic of sheet flow. 3) Driveways are constructed at the upstream end of catchment areas in some developments. However, if flow from a roof is directed to a driveway through a downspout or other conveyance mechanism, flow would be concentrated. 4) Flat slopes are prone to meandering flow that tends to be disrupted by minor irregularities and obstructions. Maximum Overland Flow lengths are shorter for the flatter slopes (sec Table 3-2). • Rural or Natural Areas -The FAA equation is applicable to these conditions since (.5% to 10%) slopes that are unifonn in width of flow have slow velocities consistent with the equation. Irregularities in terrain limit the length of application. I) Most hills and ridge lines have a relatively flat area near the drainage divide. However, with flat slopes of .5% ±, minor irregularities would cause flow to concentrate into streams. 2) Parks, lawns and other vegetated areas would have slow velocities that are consistent with the FAA Equation. The concepts related to the initial time of concentration were evaluated in a report entitled Initial Time of Co11ce11tratio11, Analysis of Parameters (Hill, 2002) that was reviewed by the Hydrology Manual Committee. The Report is available at San Diego County Department of Public Works, Flood Control Section and on the San Diego County Department of Public Works web page. San Diego County Hydrology Manual Date: June 2003 Scccion: Page: 3 14 of26 (b) Natural Or Rural Watersheds -These areas usually have an initial subarea at the upstream end with sheet flow. The sheet flow length is limited to 50 to 100 feet as specified in Table 3-2. The Overland Time of Flow Nomograph, Figure 3-3, can be used to obtain Ti. The initial time of concentration can excessively affect the magnitude of flow further downstream in the drainage basin. For instance, variations in the initial time of concentration for an initial subarea of one acre can change the flow further downstream where the area is 400 acres by I 00%. Therefore, the initial time of concentration is limited (sec Table 3-2). The Rational Method procedure included in the original Hydrology Manual ( 1971) and Design and Procedure Manual ( 1968) included a IO minute value to be added to the initial time of concentration developed through the Kirpich Formula (see Figure 3-4) for a natural watershed. That procedure is superceded by the procedure above to use Table 3-2 or Figure 3-3 to determine Ti for the appropriate sheet flow length of the initial subarea. The values for natural watersheds given in Table 3-2 vary from 13 to 7 minutes, depending on slope. If the total length of the initial subarca is greater than the maximum length allowable based on Table 3-2, add the travel time based on the Kirpich formula for the remaining length of the initial subarea. 3.1.4.2 Travel Time The T1 is the time required for the runoff to flow in a watercourse (e.g., swale, channel, gutter, pipe) or series of watercourses from the initial subarea to the point of interest. The T1 is computed by dividing the length of the flow path by the computed flow velocity. Since the velocity normally changes as a result of each change in flow rate or slope, such as at an inlet or grade break, the total T1 must be computed as the sum of the T1's for each section of the flow path. Use Figure 3-6 to estimate time of travel for street gutter flow. Velocity in a channel can be estimated by using the nomograph shown in Figure 3-7 (Manning's Equation Nomograph}. San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 15 of26 (a) Natural Watersheds -This includes rural, ranch, and agricultural areas with natural channels. Obtain T, directly from the Kirpich nomograph in Figure 3-4 or from the equation. This nomograph requires values for length and change in elevation along the effective slope line for the subarea. See Figure 3-5 for a representation of the effective slope line. This nomograph is based on the Kirpich fonnula, which was developed with data from agricultural watersheds ranging from 1.25 to 112 acres in area, 350 to 4,000 feet in length, and 2.7 to 8.8% slope (Kirpich, 1940). A maximum length of 4,000 feet should be used for the subarea length. Typically, as the flow length increases, the depth of flow will increase, and therefore it is considered a concentration of flow at points beyond lengths listed in Figure 3-2. However, because the Kirpich fonnula has been shown to be applicable ·for watersheds up to 4,000 feet in length (Kirpich, 1940), a subarea may be designated with a length up to 4,000 feet provided the topography and slope of the natural channel are generally unifonn. Justification needs to be included with this calculation showing that the watershed will remain natural forever. Examples include areas located in the Multiple Species Conservation Plan (MSCP), areas designated as open space or rural in a community's General Plan, and Cleveland National Forest. (b) Urban Watersheds -Flow through a closed conduit where no additional flow can enter the system during the travel, length, velocity and T1 are detennincd using the peak flow in the conduit. In cases where the conduit is not closed and additional flow from a contributing subarea is added to the total flow during travel ( e.g., street flow in a gutter), calculation of velocity and T1 is perfonned using an assumed average flow based on the total area (including upstream subareas) contributing to the point of interest. The Manning equation is usually used to detennine velocity. Discharges for small watersheds typically range from 2 to 3 cfs per acre, depending on land use, drainage area, and slope and rainfall intensity. Note: The MRM should be used to calculate the peak discharge when there is a junction from independent subareas into the drainage system. 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 Count Elements % IMPER. A B Undisturbed Natural Terrain (Natural) 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 (IvIDR) Residential, 4.3 DU/A or less 30 0.41 0.45 Medium Density Residential (IvIDR) Residential, 7.3 DU/A or less 40 0.48 0.51 Medium Density Residential (IvIDR) Residential, 10.9 DU/A or less 45 0.52 0.54 Medium Density Residential (IvIDR) Residential, 14.5 DU/A or less 50 0.55 0.58 High Density Residential (HDR) 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/lndustrial (N. Com) Neighborhood Commercial 80 0.76 077 Commercial/lndustrial (G. Com) General Commercial 85 0.80 0.80 Commercial/lndustrial (O.P. Com) Office Professional/Commercial 90 0.83 0.84 Commercial/lndustrial (Limited I.) Limited Industrial 90 0.83 0.84 Commercial/lndustrial General I. General Industrial 95 0.87 0.87 3 6 of26 C D 0.30 0.35 0.36 0.41 0.42 0.46 045 0.49 048 0.52 0.54 0.57 0.57 0.60 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 *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 ATTACHMENT E: FEMA Flood Plain Map National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOODHAZARD AREAS Without Base Flood Elevation (BFE)Zone A, V, A99With BFE or DepthZone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mileZone X Future Conditions 1% Annual Chance Flood HazardZone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to LeveeZone D NO SCREENArea of Minimal Flood Hazard Zone X Area of Undetermined Flood HazardZone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below.The basemap shown complies with FEMA's basemapaccuracy standards The flood hazard information is derived directly from theauthoritative NFHL web services provided by FEMA. This mapwas exported on 10/20/2022 at 1:30 PM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximatepoint selected by the user and does not representan authoritative property location. 1:6,000 117°21'35"W 33°9'50"N 117°20'58"W 33°9'20"N Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020 c:::::::::J 1111111 ATTACHMENT F: FEMA Flood Plain Map Runoff Coefficient Calculation (Existing Condition) Project: Front Porch Soil Type:B C =0.90 × (% Impervious) + Cp × (1 - % Impervious) Cp=0.25 (per table 3-1, County of San Diego Hydrology Manual, Soil Class B) Total Area (ac) Imp. Area (Ai) A 0.62 0.00 0 0.25 Undisturbed area B 0.53 0.45 85 0.80 Commercial Total 1.15 Notes: *The composite runoff coefficient (C) is calculated for the site by using the following equation: 0.90 × (% Impervious) + Cp × (1 - % Impervious); where Cp = 0.25 per Table 3-1 of the County of San Diego Hydrology Manual. Basin # Area (Acres) %imp *Runoff Coef. (C ) Equivalent Land Use (from Table 3-1) Runoff Coefficient Calculation (Proposed Condition) Project: Front Porch Soil Type:B C =0.90 × (% Impervious) + Cp × (1 - % Impervious) Cp=0.25 (per table 3-1, County of San Diego Hydrology Manual, Soil Class B) Total Area (ac) Imp. Area (Ai) A 0.62 0.550 89 0.83 Commercial B 0.53 0.45 85 0.80 Commercial Total 1.15 Notes: *The composite runoff coefficient (C) is calculated for the site by using the following equation: 0.90 × (% Impervious) + Cp × (1 - % Impervious); where Cp = 0.25 per Table 3-1 of the County of San Diego Hydrology Manual. Basin # Area (Acres) %imp *Runoff Coef. (C ) Equivalent Land Use (from Table 3-1) San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2012 Version 7.9 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 04/17/23 ------------------------------------------------------------------------ EXISTING CONDITION HYDROLOGY ANALYSIS EXIT POINT 1 FRONT PORCH - 10 YR STORM ANALYSIS OFFSITE HYDROLOGY ANALYSIS ------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Program License Serial Number 6116 ------------------------------------------------------------------------ Rational hydrology study storm event year is 10.0 English (in-lb) input data Units used Map data precipitation entered: 6 hour, precipitation(inches) = 1.600 24 hour precipitation(inches) = 3.000 P6/P24 = 53.3% San Diego hydrology manual 'C' values used ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Initial subarea total flow distance = 58.000(Ft.) Highest elevation = 58.240(Ft.) Lowest elevation = 56.500(Ft.) Elevation difference = 1.740(Ft.) Slope = 3.000 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 85.00 (Ft) for the top area slope value of 3.00 %, in a development type of General Commercial In Accordance With Figure 3-3 Initial Area Time of Concentration = 3.45 minutes TC = [1.8*(1.1-C)*distance(Ft.)^.5)/(% slope^(1/3)] TC = [1.8*(1.1-0.8000)*( 85.000^.5)/( 3.000^(1/3)]= 3.45 Calculated TC of 3.452 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.800 Subarea runoff = 0.169(CFS) Total initial stream area = 0.050(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** IRREGULAR CHANNEL FLOW TRAVEL TIME **** ______________________________________________________________________ Estimated mean flow rate at midpoint of channel = 0.337(CFS) Depth of flow = 0.067(Ft.), Average velocity = 2.283(Ft/s) ******* Irregular Channel Data *********** ----------------------------------------------------------------- Information entered for subchannel number 1 : Point number 'X' coordinate 'Y' coordinate 1 0.00 0.50 2 0.12 0.00 3 20.00 0.30 Manning's 'N' friction factor = 0.016 ----------------------------------------------------------------- Sub-Channel flow = 0.337(CFS) ' ' flow top width = 4.433(Ft.) ' ' velocity= 2.283(Ft/s) ' ' area = 0.148(Sq.Ft) ' ' Froude number = 2.203 Upstream point elevation = 56.500(Ft.) Downstream point elevation = 51.350(Ft.) Flow length = 90.000(Ft.) Travel time = 0.66 min. Time of concentration = 4.11 min. Depth of flow = 0.067(Ft.) Average velocity = 2.283(Ft/s) Total irregular channel flow = 0.337(CFS) Irregular channel normal depth above invert elev. = 0.067(Ft.) Average velocity of channel(s) = 2.283(Ft/s) Adding area flow to channel Calculated TC of 4.109 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Rainfall intensity = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.120 Subarea runoff = 0.337(CFS) for 0.100(Ac.) Total runoff = 0.506(CFS) Total area = 0.150(Ac.) Depth of flow = 0.078(Ft.), Average velocity = 2.526(Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** IRREGULAR CHANNEL FLOW TRAVEL TIME **** ______________________________________________________________________ Estimated mean flow rate at midpoint of channel = 0.809(CFS) Depth of flow = 0.092(Ft.), Average velocity = 2.862(Ft/s) ******* Irregular Channel Data *********** ----------------------------------------------------------------- Information entered for subchannel number 1 : Point number 'X' coordinate 'Y' coordinate 1 0.00 0.50 2 0.12 0.00 3 20.00 0.30 Manning's 'N' friction factor = 0.016 ----------------------------------------------------------------- Sub-Channel flow = 0.809(CFS) ' ' flow top width = 6.134(Ft.) ' ' velocity= 2.862(Ft/s) ' ' area = 0.283(Sq.Ft) ' ' Froude number = 2.348 Upstream point elevation = 51.350(Ft.) Downstream point elevation = 41.900(Ft.) Flow length = 162.000(Ft.) Travel time = 0.94 min. Time of concentration = 5.05 min. Depth of flow = 0.092(Ft.) Average velocity = 2.862(Ft/s) Total irregular channel flow = 0.809(CFS) Irregular channel normal depth above invert elev. = 0.092(Ft.) Average velocity of channel(s) = 2.862(Ft/s) Adding area flow to channel Rainfall intensity (I) = 4.187(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Rainfall intensity = 4.187(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.264 Subarea runoff = 0.600(CFS) for 0.180(Ac.) Total runoff = 1.105(CFS) Total area = 0.330(Ac.) Depth of flow = 0.104(Ft.), Average velocity = 3.094(Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Rainfall intensity (I) = 4.187(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Time of concentration = 5.05 min. Rainfall intensity = 4.187(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.424 Subarea runoff = 0.670(CFS) for 0.200(Ac.) Total runoff = 1.775(CFS) Total area = 0.530(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Rainfall intensity (I) = 4.187(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [UNDISTURBED NATURAL TERRAIN ] (Permanent Open Space ) Impervious value, Ai = 0.000 Sub-Area C Value = 0.250 Time of concentration = 5.05 min. Rainfall intensity = 4.187(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.503 CA = 0.579 Subarea runoff = 0.649(CFS) for 0.620(Ac.) Total runoff = 2.424(CFS) Total area = 1.150(Ac.) End of computations, total study area = 1.150 (Ac.) San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2012 Version 7.9 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 04/17/23 ------------------------------------------------------------------------ PROPOSED CONDITION HYDROLOGY ANALYSIS EXIT POINT 1 FRONT PORCH - 1O YR STORM ANALYSIS OFFSITE HYDROLOGY ANALYSIS ------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Program License Serial Number 6116 ------------------------------------------------------------------------ Rational hydrology study storm event year is 10.0 English (in-lb) input data Units used Map data precipitation entered: 6 hour, precipitation(inches) = 1.600 24 hour precipitation(inches) = 3.000 P6/P24 = 53.3% San Diego hydrology manual 'C' values used ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Initial subarea total flow distance = 58.000(Ft.) Highest elevation = 58.240(Ft.) Lowest elevation = 56.500(Ft.) Elevation difference = 1.740(Ft.) Slope = 3.000 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 85.00 (Ft) for the top area slope value of 3.00 %, in a development type of General Commercial In Accordance With Figure 3-3 Initial Area Time of Concentration = 3.45 minutes TC = [1.8*(1.1-C)*distance(Ft.)^.5)/(% slope^(1/3)] TC = [1.8*(1.1-0.8000)*( 85.000^.5)/( 3.000^(1/3)]= 3.45 Calculated TC of 3.452 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.800 Subarea runoff = 0.169(CFS) Total initial stream area = 0.050(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** IRREGULAR CHANNEL FLOW TRAVEL TIME **** ______________________________________________________________________ Estimated mean flow rate at midpoint of channel = 0.337(CFS) Depth of flow = 0.067(Ft.), Average velocity = 2.283(Ft/s) ******* Irregular Channel Data *********** ----------------------------------------------------------------- Information entered for subchannel number 1 : Point number 'X' coordinate 'Y' coordinate 1 0.00 0.50 2 0.12 0.00 3 20.00 0.30 Manning's 'N' friction factor = 0.016 ----------------------------------------------------------------- Sub-Channel flow = 0.337(CFS) ' ' flow top width = 4.433(Ft.) ' ' velocity= 2.283(Ft/s) ' ' area = 0.148(Sq.Ft) ' ' Froude number = 2.203 Upstream point elevation = 56.500(Ft.) Downstream point elevation = 51.350(Ft.) Flow length = 90.000(Ft.) Travel time = 0.66 min. Time of concentration = 4.11 min. Depth of flow = 0.067(Ft.) Average velocity = 2.283(Ft/s) Total irregular channel flow = 0.337(CFS) Irregular channel normal depth above invert elev. = 0.067(Ft.) Average velocity of channel(s) = 2.283(Ft/s) Adding area flow to channel Calculated TC of 4.109 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 4.216(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Rainfall intensity = 4.216(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.120 Subarea runoff = 0.337(CFS) for 0.100(Ac.) Total runoff = 0.506(CFS) Total area = 0.150(Ac.) Depth of flow = 0.078(Ft.), Average velocity = 2.526(Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** IRREGULAR CHANNEL FLOW TRAVEL TIME **** ______________________________________________________________________ Estimated mean flow rate at midpoint of channel = 0.809(CFS) Depth of flow = 0.092(Ft.), Average velocity = 2.862(Ft/s) ******* Irregular Channel Data *********** ----------------------------------------------------------------- Information entered for subchannel number 1 : Point number 'X' coordinate 'Y' coordinate 1 0.00 0.50 2 0.12 0.00 3 20.00 0.30 Manning's 'N' friction factor = 0.016 ----------------------------------------------------------------- Sub-Channel flow = 0.809(CFS) ' ' flow top width = 6.134(Ft.) ' ' velocity= 2.862(Ft/s) ' ' area = 0.283(Sq.Ft) ' ' Froude number = 2.348 Upstream point elevation = 51.350(Ft.) Downstream point elevation = 41.900(Ft.) Flow length = 162.000(Ft.) Travel time = 0.94 min. Time of concentration = 5.05 min. Depth of flow = 0.092(Ft.) Average velocity = 2.862(Ft/s) Total irregular channel flow = 0.809(CFS) Irregular channel normal depth above invert elev. = 0.092(Ft.) Average velocity of channel(s) = 2.862(Ft/s) Adding area flow to channel Rainfall intensity (I) = 4.187(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Rainfall intensity = 4.187(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.264 Subarea runoff = 0.600(CFS) for 0.180(Ac.) Total runoff = 1.105(CFS) Total area = 0.330(Ac.) Depth of flow = 0.104(Ft.), Average velocity = 3.094(Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Rainfall intensity (I) = 4.187(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Time of concentration = 5.05 min. Rainfall intensity = 4.187(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.424 Subarea runoff = 0.670(CFS) for 0.200(Ac.) Total runoff = 1.775(CFS) Total area = 0.530(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Rainfall intensity (I) = 4.187(In/Hr) for a 10.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Time of concentration = 5.05 min. Rainfall intensity = 4.187(In/Hr) for a 10.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.920 Subarea runoff = 2.077(CFS) for 0.620(Ac.) Total runoff = 3.852(CFS) Total area = 1.150(Ac.) End of computations, total study area = 1.150 (Ac.) San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2012 Version 7.9 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 04/17/23 ------------------------------------------------------------------------ EXISTING CONDITION HYDROLOGY ANALYSIS EXIT POINT 1 FRONT PORCH - 100YR ANALYSIS OFFSITE HYDROLOGY ANALYSIS ------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Program License Serial Number 6116 ------------------------------------------------------------------------ Rational hydrology study storm event year is 100.0 English (in-lb) input data Units used Map data precipitation entered: 6 hour, precipitation(inches) = 2.500 24 hour precipitation(inches) = 4.500 P6/P24 = 55.6% San Diego hydrology manual 'C' values used ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Initial subarea total flow distance = 58.000(Ft.) Highest elevation = 58.240(Ft.) Lowest elevation = 56.500(Ft.) Elevation difference = 1.740(Ft.) Slope = 3.000 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 85.00 (Ft) for the top area slope value of 3.00 %, in a development type of General Commercial In Accordance With Figure 3-3 Initial Area Time of Concentration = 3.45 minutes TC = [1.8*(1.1-C)*distance(Ft.)^.5)/(% slope^(1/3)] TC = [1.8*(1.1-0.8000)*( 85.000^.5)/( 3.000^(1/3)]= 3.45 Calculated TC of 3.452 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.800 Subarea runoff = 0.263(CFS) Total initial stream area = 0.050(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** IRREGULAR CHANNEL FLOW TRAVEL TIME **** ______________________________________________________________________ Estimated mean flow rate at midpoint of channel = 0.527(CFS) Depth of flow = 0.079(Ft.), Average velocity = 2.552(Ft/s) ******* Irregular Channel Data *********** ----------------------------------------------------------------- Information entered for subchannel number 1 : Point number 'X' coordinate 'Y' coordinate 1 0.00 0.50 2 0.12 0.00 3 20.00 0.30 Manning's 'N' friction factor = 0.016 ----------------------------------------------------------------- Sub-Channel flow = 0.527(CFS) ' ' flow top width = 5.241(Ft.) ' ' velocity= 2.552(Ft/s) ' ' area = 0.206(Sq.Ft) ' ' Froude number = 2.266 Upstream point elevation = 56.500(Ft.) Downstream point elevation = 51.350(Ft.) Flow length = 90.000(Ft.) Travel time = 0.59 min. Time of concentration = 4.04 min. Depth of flow = 0.079(Ft.) Average velocity = 2.552(Ft/s) Total irregular channel flow = 0.527(CFS) Irregular channel normal depth above invert elev. = 0.079(Ft.) Average velocity of channel(s) = 2.552(Ft/s) Adding area flow to channel Calculated TC of 4.040 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.120 Subarea runoff = 0.527(CFS) for 0.100(Ac.) Total runoff = 0.790(CFS) Total area = 0.150(Ac.) Depth of flow = 0.092(Ft.), Average velocity = 2.824(Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** IRREGULAR CHANNEL FLOW TRAVEL TIME **** ______________________________________________________________________ Estimated mean flow rate at midpoint of channel = 1.265(CFS) Depth of flow = 0.109(Ft.), Average velocity = 3.199(Ft/s) ******* Irregular Channel Data *********** ----------------------------------------------------------------- Information entered for subchannel number 1 : Point number 'X' coordinate 'Y' coordinate 1 0.00 0.50 2 0.12 0.00 3 20.00 0.30 Manning's 'N' friction factor = 0.016 ----------------------------------------------------------------- Sub-Channel flow = 1.265(CFS) ' ' flow top width = 7.251(Ft.) ' ' velocity= 3.200(Ft/s) ' ' area = 0.395(Sq.Ft) ' ' Froude number = 2.415 Upstream point elevation = 51.350(Ft.) Downstream point elevation = 41.900(Ft.) Flow length = 162.000(Ft.) Travel time = 0.84 min. Time of concentration = 4.88 min. Depth of flow = 0.109(Ft.) Average velocity = 3.199(Ft/s) Total irregular channel flow = 1.265(CFS) Irregular channel normal depth above invert elev. = 0.109(Ft.) Average velocity of channel(s) = 3.199(Ft/s) Adding area flow to channel Calculated TC of 4.884 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.264 Subarea runoff = 0.949(CFS) for 0.180(Ac.) Total runoff = 1.739(CFS) Total area = 0.330(Ac.) Depth of flow = 0.123(Ft.), Average velocity = 3.465(Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 4.884 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Time of concentration = 4.88 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.424 Subarea runoff = 1.054(CFS) for 0.200(Ac.) Total runoff = 2.793(CFS) Total area = 0.530(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 4.884 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [UNDISTURBED NATURAL TERRAIN ] (Permanent Open Space ) Impervious value, Ai = 0.000 Sub-Area C Value = 0.250 Time of concentration = 4.88 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.503 CA = 0.579 Subarea runoff = 1.021(CFS) for 0.620(Ac.) Total runoff = 3.814(CFS) Total area = 1.150(Ac.) End of computations, total study area = 1.150 (Ac.) San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2012 Version 7.9 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 04/17/23 ------------------------------------------------------------------------ PROPOSED CONDITION HYDROLOGY ANALYSIS EXIT POINT 1 FRONT PORCH - 100YR ANALYSIS OFFSITE HYDROLOGY ANALYSIS ------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Program License Serial Number 6116 ------------------------------------------------------------------------ Rational hydrology study storm event year is 100.0 English (in-lb) input data Units used Map data precipitation entered: 6 hour, precipitation(inches) = 2.500 24 hour precipitation(inches) = 4.500 P6/P24 = 55.6% San Diego hydrology manual 'C' values used ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION **** ______________________________________________________________________ Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Initial subarea total flow distance = 58.000(Ft.) Highest elevation = 58.240(Ft.) Lowest elevation = 56.500(Ft.) Elevation difference = 1.740(Ft.) Slope = 3.000 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 85.00 (Ft) for the top area slope value of 3.00 %, in a development type of General Commercial In Accordance With Figure 3-3 Initial Area Time of Concentration = 3.45 minutes TC = [1.8*(1.1-C)*distance(Ft.)^.5)/(% slope^(1/3)] TC = [1.8*(1.1-0.8000)*( 85.000^.5)/( 3.000^(1/3)]= 3.45 Calculated TC of 3.452 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.800 Subarea runoff = 0.263(CFS) Total initial stream area = 0.050(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** IRREGULAR CHANNEL FLOW TRAVEL TIME **** ______________________________________________________________________ Estimated mean flow rate at midpoint of channel = 0.527(CFS) Depth of flow = 0.079(Ft.), Average velocity = 2.552(Ft/s) ******* Irregular Channel Data *********** ----------------------------------------------------------------- Information entered for subchannel number 1 : Point number 'X' coordinate 'Y' coordinate 1 0.00 0.50 2 0.12 0.00 3 20.00 0.30 Manning's 'N' friction factor = 0.016 ----------------------------------------------------------------- Sub-Channel flow = 0.527(CFS) ' ' flow top width = 5.241(Ft.) ' ' velocity= 2.552(Ft/s) ' ' area = 0.206(Sq.Ft) ' ' Froude number = 2.266 Upstream point elevation = 56.500(Ft.) Downstream point elevation = 51.350(Ft.) Flow length = 90.000(Ft.) Travel time = 0.59 min. Time of concentration = 4.04 min. Depth of flow = 0.079(Ft.) Average velocity = 2.552(Ft/s) Total irregular channel flow = 0.527(CFS) Irregular channel normal depth above invert elev. = 0.079(Ft.) Average velocity of channel(s) = 2.552(Ft/s) Adding area flow to channel Calculated TC of 4.040 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.120 Subarea runoff = 0.527(CFS) for 0.100(Ac.) Total runoff = 0.790(CFS) Total area = 0.150(Ac.) Depth of flow = 0.092(Ft.), Average velocity = 2.824(Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** IRREGULAR CHANNEL FLOW TRAVEL TIME **** ______________________________________________________________________ Estimated mean flow rate at midpoint of channel = 1.265(CFS) Depth of flow = 0.109(Ft.), Average velocity = 3.199(Ft/s) ******* Irregular Channel Data *********** ----------------------------------------------------------------- Information entered for subchannel number 1 : Point number 'X' coordinate 'Y' coordinate 1 0.00 0.50 2 0.12 0.00 3 20.00 0.30 Manning's 'N' friction factor = 0.016 ----------------------------------------------------------------- Sub-Channel flow = 1.265(CFS) ' ' flow top width = 7.251(Ft.) ' ' velocity= 3.200(Ft/s) ' ' area = 0.395(Sq.Ft) ' ' Froude number = 2.415 Upstream point elevation = 51.350(Ft.) Downstream point elevation = 41.900(Ft.) Flow length = 162.000(Ft.) Travel time = 0.84 min. Time of concentration = 4.88 min. Depth of flow = 0.109(Ft.) Average velocity = 3.199(Ft/s) Total irregular channel flow = 1.265(CFS) Irregular channel normal depth above invert elev. = 0.109(Ft.) Average velocity of channel(s) = 3.199(Ft/s) Adding area flow to channel Calculated TC of 4.884 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.264 Subarea runoff = 0.949(CFS) for 0.180(Ac.) Total runoff = 1.739(CFS) Total area = 0.330(Ac.) Depth of flow = 0.123(Ft.), Average velocity = 3.465(Ft/s) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 4.884 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Time of concentration = 4.88 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.424 Subarea runoff = 1.054(CFS) for 0.200(Ac.) Total runoff = 2.793(CFS) Total area = 0.530(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION **** ______________________________________________________________________ Calculated TC of 4.884 minutes is less than 5 minutes, resetting TC to 5.0 minutes for rainfall intensity calculations Rainfall intensity (I) = 6.587(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 1.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] (General Commercial ) Impervious value, Ai = 0.850 Sub-Area C Value = 0.800 Time of concentration = 4.88 min. Rainfall intensity = 6.587(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KCIA) is C = 0.800 CA = 0.920 Subarea runoff = 3.267(CFS) for 0.620(Ac.) Total runoff = 6.060(CFS) Total area = 1.150(Ac.) End of computations, total study area = 1.150 (Ac.) Hydraflow Storm Sewers Extension for Autodesk® Civil 3D® Plan 2 ___________________ 1 _____________________ Outfall -- Project File: 18 inch-EX-Ocean Street-1 0YR.stm I Number of lines: 2 I Date: 4/26/2023 Storm Sewers v2022.00 Hydraulic Grade Line Computations Page 1 Line Size Q Downstream Len Upstream Check JL Minor coeff loss Invert HGL Depth Area Vel Vel EGL Sf Invert HGL Depth Area Vel Vel EGL Sf Ave Enrgy elev elev head elev elev elev head elev Sf loss (in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (ft) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (%) (ft) (K) (ft) 2 18 2.42 38.95 40.94 1.50 1.77 1.37 0.03 40.97 0.053 61.750 39.26 40.97 1.50 1.77 1.37 0.03 41.00 0.053 0.053 0.033 1.00 0.03 1 18 2.42 37.31 40.76 1.50 1.77 1.37 0.03 40.79 0.053 296.60 ~38.87 40.92 1.50 1.77 1.37 0.03 40.95 0.053 0.053 0.158 0.66 0.02 Project File: 18 inch-EX-Ocean Street-1 0YR.stm I Number of lines: 2 I Run Date: 4/26/2023 ; c = cir e = ellip b = box Storm Sewers v2022.00 Storm Sewer Profile 0 C ' U") - Elev. (ft) oN~ 0-str--: 8w(") 6 -o w 2 E > en c.? E 54.00 50.00 46.00 / 42.00 38.00 ')( 1'-'-fllll f -tl cw. u.;:,, /0 34.00 0 25 50 75 100 125 150 175 200 225 250 275 ----HGL----EGL Reach (ft) Proj. file: 18 inch-EX-Ocean Street-1 0YR.stm C :, ...J OE ' Or--u, 0 "'com (C) N .. <D -st co co (J) (")(") + w w w N ro .£ > > u5 C:::EE ~ 300 325 N C :, ...J 0 ' '°co U") ON (") N" co -st (J) U") (") + wu:j (") ro .£ > u5 C:::E 54.00 50.00 46.00 42.00 - 38.00 bl.I . II t -1 tj' (i 10 .50% 350 34.00 375 Storm Sewers Hydraflow Storm Sewers Extension for Autodesk® Civil 3D® Plan 2 ___________________ 1 _____________________ Outfall -- Project File: 18 inch-PR-Ocean Street-1 0YR.stm I Number of lines: 2 I Date: 4/26/2023 Storm Sewers v2022.00 Hydraulic Grade Line Computations Page 1 Line Size Q Downstream Len Upstream Check JL Minor coeff loss Invert HGL Depth Area Vel Vel EGL Sf Invert HGL Depth Area Vel Vel EGL Sf Ave Enrgy elev elev head elev elev elev head elev Sf loss (in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (ft) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (%) (ft) (K) (ft) 2 18 3.85 38.95 41.21 1.50 1.77 2.18 0.07 41.28 0.134 61.750 39.26 41.29 1.50 1.77 2.18 0.07 41.36 0.134 0.134 0.083 1.00 0.07 1 18 3.85 37.31 40.76 1.50 1.77 2.18 0.07 40.83 0.134 296.60 ~38.87 41.16 1.50 1.77 2.18 0.07 41.23 0.134 0.134 0.399 0.66 0.05 Project File: 18 inch-PR-Ocean Street-1 0YR.stm I Number of lines: 2 I Run Date: 4/26/2023 ; c = cir e = ellip b = box Storm Sewers v2022.00 Storm Sewer Profile 0 C ' U") - Elev. (ft) oN~ Os:tr--: 8w(") 6 -o w 2 E > en c.? E 54.00 50.00 46.00 / 42.00 38.00 ')( 1'-'-fllll f -tl cw. u.;:,, /0 34.00 0 25 50 75 100 125 150 175 200 225 250 275 ----HGL----EGL Reach (ft) Proj. file: 18 inch-PR-Ocean Street-10YR.stm C :, ...J OE ' Or--u, 0 "'com (C) N .• <D s:t co co (J) (")(") + w w w N ro .£ > > u5 C:::EE ~ 300 325 N C :, ...J 0 ' '°co U") ON (") N" co s:t (J) U") (") + wu:j (") ro .£ > u5 C:::E 54.00 50.00 46.00 42.00 - 38.00 bl.I . II t -1 tj' (i 10 .50% 350 34.00 375 Storm Sewers Hydraflow Storm Sewers Extension for Autodesk® Civil 3D® Plan 2 ___________________ 1 ____________________ Outfall -- Project File: 18 inch-EX-Ocean Street-1 00YR.stm I Number of lines: 2 I Date: 4/25/2023 Storm Sewers v2022.00 Hydraulic Grade Line Computations Page 1 Line Size Q Downstream Len Upstream Check JL Minor coeff loss Invert HGL Depth Area Vel Vel EGL Sf Invert HGL Depth Area Vel Vel EGL Sf Ave Enrgy elev elev head elev elev elev head elev Sf loss (in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (ft) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (%) (ft) (K) (ft) 2 18 3.82 38.95 42.81 1.50 1.77 2.16 0.07 42.88 0.132 61.750 39.26 42.89 1.50 1.77 2.16 0.07 42.96 0.132 0.132 0.082 1.00 0.07 1 18 3.82 37.31 42.37 1.50 1.77 2.16 0.07 42.44 0.132 296.60 ~38.87 42.76 1.50 1.77 2.16 0.07 42.84 0.132 0.132 0.393 0.66 0.05 Project File: 18 inch-EX-Ocean Street-1 00YR.stm I Number of lines: 2 I Run Date: 4/25/2023 ; c = cir e = ellip b = box Storm Sewers v2022.00 Storm Sewer Profile 0 C ' U") - Elev. (ft) oN~ 0-str--: 8w(") 6 -o w 2 E > en c.? E 54.00 50.00 46.00 / 42.00 38.00 ')( 1'-'-fllll f -tl cw. u.;:,, /0 34.00 0 25 50 75 100 125 150 175 200 225 250 275 ----HGL----EGL Reach (ft) Proj. file: 18 inch-EX-Ocean Street-100YR.stm C :, ...J OE ' Or--u, 0 "'com (C) N .. <D -st co co (J) (")(") + w w w N ro .£ > > u5 C:::EE ~ 300 325 N C :, ...J 0 ' '°co U") ON (") N" co -st (J) U") (") + wu:j (") ro .£ > u5 C:::E 54.00 50.00 46.00 42.00 - 38.00 bl.I . II t -1 tj' (i 10 .50% 350 34.00 375 Storm Sewers Hydraflow Storm Sewers Extension for Autodesk® Civil 3D® Plan 2 ___________________ 1 _____________________ Outfall -- Project File: 18 inch-PR-Ocean Street-1 00YR.stm I Number of lines: 2 I Date: 4/25/2023 Storm Sewers v2022.00 Hydraulic Grade Line Computations Page 1 Line Size Q Downstream Len Upstream Check JL Minor coeff loss Invert HGL Depth Area Vel Vel EGL Sf Invert HGL Depth Area Vel Vel EGL Sf Ave Enrgy elev elev head elev elev elev head elev Sf loss (in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (ft) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (%) (ft) (K) (ft) 2 18 6.10 38.95 43.49 1.50 1.77 3.45 0.19 43.68 0.338 61.750 39.26 43.70 1.50 1.77 3.45 0.19 43.89 0.337 0.338 0.208 1.00 0.19 1 18 6.10 37.31 42.37 1.50 1.77 3.45 0.19 42.56 0.338 296.60 ~38.87 43.37 1.50 1.77 3.45 0.19 43.56 0.337 0.338 1.001 0.66 0.12 Project File: 18 inch-PR-Ocean Street-1 00YR.stm I Number of lines: 2 I Run Date: 4/25/2023 ; c = cir e = ellip b = box Storm Sewers v2022.00 Storm Sewer Profile 0 C ' U') - Elev. (ft) oN~ Os:tr--: 8w("') 6 -ci w 2 E > en c.? .!: 54.00 50.00 46.00 / 42.00 38.00 ')( 1'-'-fllll f -tl cw. u.;:,, /0 34.00 0 25 50 75 100 125 150 175 200 225 250 275 ----HGL----EGL Reach (ft) Proj. file: 18 inch-PR-Ocean Street-1 00YR.stm C :, ...J O.!: ' Or--u, 0 "'com (C) N .. <D "St co co (J) ("')("') + w w w N ro .£ > > u5 C:::.!:.!: ~ 300 325 N C :, ...J 0 ' '°co U') ON ("') N' co "St (J) U') ("') + wu:j ("') ro .£ > u5 C:::.!: 54.00 50.00 46.00 42.00 - 38.00 bl.I . II t -1 tj' (i 10 .50% 350 34.00 375 Storm Sewers Inlet Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Friday, Apr 21 2023 Type B-inlet (Existing condition) Curb Inlet Location = Sag Curb Length (ft) = 4.00 Throat Height (in) = 6.00 Grate Area (sqft) = -0- Grate Width (ft) = -0- Grate Length (ft) = -0- Gutter Slope, Sw (ft/ft) = 0.080 Slope, Sx (ft/ft) = 0.020 Local Depr (in) = -0- Gutter Width (ft) = 1.50 Gutter Slope (%) = -0- Gutter n-value = -0- Calculations Compute by:Known Q Q (cfs)= 3.82 Highlighted Q Total (cfs)= 3.82 Q Capt (cfs)= 3.82 Q Bypass (cfs) = -0- Depth at Inlet (in) = 5.81 Efficiency (%)= 100 Gutter Spread (ft) = 19.72 Gutter Vel (ft/s) = -0- Bypass Spread (ft) = -0- Bypass Depth (in) = -0- All dimensions in feet Inlet Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Friday, Apr 21 2023 Type B-inlet (proposed condition) Curb Inlet Location = Sag Curb Length (ft) = 4.00 Throat Height (in) = 6.00 Grate Area (sqft) = -0- Grate Width (ft) = -0- Grate Length (ft) = -0- Gutter Slope, Sw (ft/ft) = 0.080 Slope, Sx (ft/ft) = 0.020 Local Depr (in) = -0- Gutter Width (ft) = 1.50 Gutter Slope (%) = -0- Gutter n-value = -0- Calculations Compute by:Known Q Q (cfs)= 6.10 Highlighted Q Total (cfs)= 6.10 Q Capt (cfs)= 6.10 Q Bypass (cfs) = -0- Depth at Inlet (in) = 7.55 Efficiency (%)= 100 Gutter Spread (ft) = 26.95 Gutter Vel (ft/s) = -0- Bypass Spread (ft) = -0- Bypass Depth (in) = -0- All dimensions in feet ATTACHMENT F: FEMA Flood Plain Map I I I I I I I I I I I I I I I I I I I INTRODUCTION: This report covers the watershed of the Ocean Estates project which is technically within two basins. The proposed project is for the construction of 4 residential lots and 1 common lot within the existing R-3 multifamily zone area. The project area is approximately 0.64 acres located between Garfield Street and Ocean Street and south of Beech Avenue. The hydrology calculations are based on nmoff coefficient of C = 0. 79 per Table 3.1, High Density Residential (HDR)@43.0 DU/A. PROCEDURE: A) 100 YEAR STORM FREQUENCY The first attempt to analyze the effect of a 100 year-storm :frequency to the existing drainage system at the intersection of Ocean Street and Christiansen Way without project runoff diverted to the south was found to be inadequate in discharging runoff into the existing 18" drainage outfall. Most of the storm water in a 100 year storm would overtop the catch ha.sins by 2.51 feet and flow to some curb low points of discharge (See Attachment A, page 1 through 2). The problem of flooding could be solved by reconstructing the existing curb inlet at(Node No. 5) and the existing 18" drainage pipe outfall, but because of close proximity of existing structures· and undermining of footings during construction this is riot a viable option to solve the problem; The post and pre-development runoff within the watershed boundary limits of the ·proposed project an area of 0.92 acre generates a runoff volume for detention of 1,013 cubic feet a.ta flow rate of 5.13 cu.ft./sec.( See Attachment A, page 5 of 9 pages). The construction of the detention pipe system and the storage capacity of the street east of the road centerline crown can store a total volume of 1,105 cubic feet of runoff which exceeds the required storage volume before flowing to the north (see Attachment A, page 6 of9 pages). The study went further to analyze the effect of post-development runoff within the subject property development, an area of 0.62 acre, that will affect the X-gutter and channel at Sta 29+30 (See Attachment, page 7 to 9). • The project post-development runoff generates a flow rate of 3.29 cu.ft.per sec. with water surface elevation of 42.12 and a :freeboard of 0.08' below the·proposed street crown elevation of 42.20 (See X-Section of the Channel). c The existing pre-development runoff:from the site generates a flow rate of 1.40 cu.ft.per sec. The difference between the post-development and existing pre .. development runoff is 1.89 cu.ft.per sec. The project post-development contribution of runoff creates only a depth water in the channel of0.23' and a :freeboard of 0.17' B)50YEARSTORMFREQUENCY Further analysis was conducted on a 50-year storm :frequency and the effect to the existing drainage system without project runoff participation. Hydraulics calculation reveale.d that with project runoff to the south flooding would occur at elevation 42.98 around node No.3 by.0.30' depth at the street intersection of Ocean Street and Christiansen Way (See Attachment B, page 3 of 3 pages). At this depth excess storm water will begin to sheet flow towards the north. No further hydrology & hydraulics calculations were prepared to include project post-development. I I I I I I I I I I I I I I I I I I I C) 10 YEAR STORM FREQUENCY The pre-development runoff based on the IO-year storm frequency of the proposed project currently sheet flows to the north. The increase of the flow rate of post-development storm water from this project will be diverted to the south through an 18" detention pipe that will temporarily store and hold 700 cu.ft. of storm water for 5.07 minutes and then resume the flow rate of 4.11 cu. ft. per sec. into a proposed 18" parallel drainage pipe. At this peak runoff it creates a hydraulic grade line of 42.34 which is higher than the street crown elevation. Only partial diversion to the south is accomplished as the improved channel@ sta. 29+30 x-gutter takes over the excess runoff. In addition the street crown storage east of the Ocean Street centerline crown can temporarily store another 405 cu.ft. The project has the total storage capacity of 1105 cu.ft. of storm water in 5 .13 minutes total time of detention (See Attachment D, page 6 of 6 pages) before any excess runoff begins to flow to the north. All of the drainage system south of the project . sustaining a 10 year storm frequency will be in channel flow with no apparent flooding to occur. As the storm begins to subside the stored volume of water will begin to discharge through the l~ 2" orifices. Within 3 hours and 20 minutes the detention pipe will be empty. CONCLUSION: The flooding of the downstream area to the north from the project area will be diminished temporarily due to the construction of the detention pipe and the storage capacity of the street crown easterly of the centerline fronting the project. The detention system reduces temporarily the 100 year storm runoff of the north watershed area from Q = 17.57 cfs without detention to Q =16.31 cfs with detention. The pre-development watershed runoff within the project lot line limits generates Q =1.40 cfs and the post-development - runoff generates Q =3.29 cfs. The detention requirement due to the proposed project is only 1013 cu.ft which is less than the proposed volume storage of the detention system of 1,105 cu.ft. Any storm water that exceeds the capacity of this detention system will begin flowing to the north. The 50 year storm frequency will generate a runoff from existing development of Q =27.37 cfs. that will cause flooding at the intersection of Christiansen Way & Ocean Street Any runoff from the project site will increase flooding to the south. Our proposed detention pipe is equipped with a weir in the cleanout that allows the 10 year storm frequency post-development runoff of 4 .11 cfs to pass the detention basin and into the proposed 18" R.C.P. in channel flow. No flooding to the south will occur during a 10 year storm frequency. I I .. I I I I I I I CHARTS & TABLES I I I I I I 1. .;i I I , • I I .. . -. . . -. ----·;-.-.:-·· •• -- I I I I I I I I I I I I I I I I I I ,. San Diego Count'; Hvdrologv r.fanual • Date: J11ne 2003 • • -· Section: Page: 3 12 of26 Note that the Initial Time of Concentration should be reflecti\·e of the _-'::neral land-use at the upstream end of a drainage.basin. A single lot with an area of n...-o or less acres does not ha\·e a significant effect where the drainage basin area is 20 to 600 acres. l Table 3-2 provides limits of the length (Maximum Length (L11)) of sheet flo\v 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 applicatfons as described below. Exceptions may be. approved by the "Regulating Agency" whe·n submitted with a detailed study. Table 3-2 l\.'1AXI1\1Ul\1 OVERLAND FLO\V LENGTH (Lj\1) & INITIALTI1\1E OF CONCENTRATION (Ti) -Element* DU/ .5% 1% 2% 3% 5% 10% Acre L11 Ti LM Ti ,LM Ti LM Ti Lii Ti . L1--1 Ti Natural. 50 13.2 70 12.5 85 10.9 100 10.3 100 8.7 100 6._9 LDR 1 50 12.2 70 11.5 85 10.0 100 9.5 100 8.0 100 6.4 LDR 2 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 JOO . 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 l 50 4.7 60 4.1 75 3.6 85 3.4 90 2.9 100. Z.4 0.P./Com 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 • 2.i Limited I. 50 4.2 60 3.7 70 3.1 80 2.9 90' 2.6 10·0 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 3-12 ------------------- .. San Diego County Hydrology Manual Date: June 2003 Table 3-1 Section: Page: RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use Runoff Coefficient "C" Soil Type . NRCS Elements County 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 (HDR) Residential, 24.0 DU/A or less 65 0.66 0.67 High Density Residential-(HDR) Resideritial, 43.0 DU/A, or less 80 0.76 0.77 Commercial/Industrial (N. Com) Neighborhood Commercial 80 0.76-0.77' Commercial/Industrial (O. 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 l.) General Industrial 9_5 0.87 0.87 C 0.30 0.36 0.42 0.45 0.48 0.54 0.57 0.60 0.69 0.18 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 Fdrest). DU/ A = dwelling units per acre NRCS = National Resources Conservation Service 3-6 I I I I I I I I I I I I I I I I I I I ATTACHMENT A EXISTING DEVELOPMENT HYDROLOGY & HYDRAULICS CA(CULATIONS . . Storm Frequency= 100 Years (No Project Participation) I I I I I I I I I I I I I I I I I I I RUNOFF CALCULATION Page 1 of 9 Pages Project Name: Ocean Vista Estates, Carlsbad Soil Classification = '.'D" Job No. 257 -06 Date: April 26, 2007 • Existing Development Hydrology ATTACHMENT A Frequency= 100 Yr. Storm C= 0.79 Table 3-1 6 Hour Precipitation P6= 2.5 Fig. 3-1 NOTE: This calculation is being prepared to analyze the outfall runff generated from Basins B,C & D in conjuntion with the existing runoff per DWG. # 347-2 Sheet# 2 without project participation From Node 4 to Node 3 Area B A= 3.78 Ac. Distance Travel L= 560 Ft Effective Slope s = 3.24% Initial Time of Concentration Ti= 6.88 Miin .. Table 3-2 Maximum Traveled Distance Lm= 95.60 Ft Interpolated Trial Runoff Q= 14.13 Cfs. Initial Q = 2 Cfs Street Cross Slope Sx= 2.00% Cb & Gut Chi. Flow ManninQ's RouQhness n= 0.015 Depth of Water @ Gutter Y= 0.33 Ft Velocity of Gutter VQ= 5.27 Ft./Sec. Remaining Distance Travel Lr= 464.40 Ft RenaiminQ Time to Travel Tr= 1.47 Min. Time of Concentration Tc= 8.35 Min. Intensity I= 4.73 Ins/Hr CxA CA= 2.99 Designed Runoff Q100= 14.13 CFS From Node 3 to Node 5 Area C A= 0.14 Ac. Designed Runoff Q100 = 14.13 CFS Pipe Length L= 42.50 Ft. Pipe Diameter d= 1.50 Ft. Friction Slope Sf= 1.81% Pipe Flowing Full. ManninQ's Coef. .n = 0.013 Depth of Water y= 1.50 Ft. Velocity V= 8.00 Ft./Sec. Velocity Head hv= 0.99 Ft. Travel Time Ti= 0.51 Min. Time of Concentration Tc= a.a6 Min. Intensity I= 4.55 ln~/Hr AxC AC= 0.11 Runoff q= 0.50 CFS Total Designed Runoff Q100 = ·14.6~ CFS From Node 5 to Node 6 .. Area D A= 0.16 Ac. Designed Runoff Q100 = 14.63 CFS Pipe Length L= 74.64 Ft. I I I I I I I I I I I I I I I I I I I RUNOFF CALCULATION Page 2 of9 Pages . Project Name: Ocean Vista Estates, Carlsbad Soil Classification = "D" Job No. 257-06 Date: April 26, 2007 Existing Development Hydrology ATTACHMENT A Frequency= 100 Yr. Storm c::: 0.79 Table 3-1 6 Hour Precipitation P6= 2.5 Fig. 3-1 Pipe Diameter d= 1.50 Ft. Friction Slope Sf= 1.94% Manning's Coef. .n = 0.013 Depth of Water y= 1.50 Ft. -Velocity V= 8.28 Ft./Sec. Velocity Head hv= 1.06 Ft. Travel Time Ti= 0.15 Min. Time of Concentration Tc= 9.01 Min. Intensity I= 4.51 Ins/Hr CxA A.x.C = 0.13 Area Runoff q= 0.57 CFS Deaigned Runoff Q100 = 15.20 CFS Existing Runoff in the 36" RCP Q100 = 24.51 CFS See Hydroloav Report for Assumed Time of Concetrration Tc= 11.93 Min. R.P. 94-06. Dwa. # 347-2E I= 4.06 Ins/Hr Revised Dated, 6/1/98 CONFLUENCE @ NODE 6 = 0100 = Tc I - Node 146 of Report of RP. 84-06 24.51 11.93 4.06 (See Exhibit A) Area B.C.D 15.20 9.01 4 .. 51 Confluenc Q = 38.20 From Node 6 to Outfall Designed Runoff Q100 = 39.20 CFS .. Pipe Length L= 74.64 Ft. Pipe Diameter d= 1.50 Ft. Pipe Slope So= 26.00% Manning's Coef. .n = 0.013 .. Depth of Water y= 0.95 'Ft. Velocity V= 33.09 Ft./Sec. Velocity Head hv= 17.01 Ft. Critical Depth de = de= 1.50 Ft. Critical Velocity Ve = Ve= 21.61 Ft./Sec. Critical Velocity Head hvc = hvc= 7.25 Ft. Coeff. Manhole Entrance ke =· 0.18 Manhole Loss Mh= 1.31 Ft. Total Head H= 10.06 Ft. Invert Eleveation I.E= 35.28 ' . Hydraulic Grade Line HGL= 45.34 NOTE: At this point the street intersection is floodded 2.51 ft. above Curb Inlet gutter flow line elevation 42.83. The area is flooded at the intersection of Christiansen Ave. & Ocean St. I I I I I I I I I I I I I I I I I I I HYDROLOGY & HYDRAULICS CALCULATIONS Project: Ocean Vista Estates, Carlsbad Job No. 257-06 Project VVatershed Analysis Frequency= 100 Yr. Storm C= 6 Hour Precipitation P6= Drainage Study Within Property Watershed Area Of the Project A= 0.92 Distance Travel L= 246 Effective Slope s = 6.70% Initial Time of Concentration Ti= 4.03 Maximum Traveled Distance Lm= 96.70 Trial Runoff Q= 5.13 Street Cross Slope Sx= 2.00% Manning's Roughness n= 0.015 Depth of Water @ Gutter Y= 0.20 Velocity of Gutter Vg= 5.37 Remaining Distance Travel Lr= 149.30 Remaining Time to Travel Tr= 0.46 Total Time of Concentration Tc= 4.49 Intensity I= 7.06 CxA CA= 0.73 Designed Runoff Q100 = 5.13 Total Runoff into the Curb Inlet Q100 = 5.13 Hydraulics ~ Node 2 to Node 3 Designed Runoff Q100= 3.32 Pipe Length L= 362.00 Pipe Diameter d= 1.50 Slope So= 0.50% Manning's Coef. .n = 0.013 Depth of Water y= 0.70 Velocity V= 4.08 Velocity Head hv= 0.26 Critical Depth de = de= 0.69 Critical Velocity Ve = Ve= 4.15 Critical Velocity Head hvc = hvc= 0.27 Capacity of the 18" R.C.P. Q= 7.42 Page3 of9 Pages Soil Classification = "D" Date: June 14, 2007 ATTACHMENT A 0.79 Table 3-1 2.5 Fifi. 3-1 Node ·1 to node 2 Ac. Ft Miin .. Table_3-2 Ft Interpolated Cfs. Initial Q = 2 Cfs Cb & Gut Chi. Flow Ft Ins/Hr CFS CFS CFS Project Generated Runoff Ft. Ft. Ft. Ft./Sec. Ft. Ft. Ft./Sec. Ft. CFS I ~ ~ ~ •1 •1 •1 •1 •1 ., •1 •1 •1 •• •• •• •• •.- 1 I Given pipe size= 36.00(In.) Calculated individual Pipe flow = 24.512(CFS) Normal flow depth in pipe= 10.69(In.) Flow top width-inside pipe= 32.90(In.) Critical Depth= 19.lS(In.) Pipe flow velocity= 13.95(Ft/s) Travel time through pipe= 0.04 min. Time of concentratio~ (TC) = 11.93 min. +++++++++++++++t+++++++t+++++++++++++++++++++t++++++++++++++++++++++++ Process from Point/Station 142.000 to Point/Station 142.000 **** CONFLUENCE OF MAIN STREAMS**** • The rollowing aata insiae Main Stream is listed: In Main Stream number: 1 .. . Stream flow area = Q_--.-:r;flf(Ac~; ---Runoff from this stream = --m_,..5.J-2 (CFS) Time of -concentration = ,:.!_r:·J) .. m.in--;:: Rainfall intensity = 4. 0-59 (In/Hr)· Program is now starting with Main Stream No. 2 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 144.000 to Point/Station 146.000 **** INITIAL AR.EA EVALUATION ***.* • • ff/U' Decimal rraction soil group A -i.000 . Decimal -fraction soil group B == 0 .. 000 ... Decimal fraction soil group C = 0.000· Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] Initial subarea flow distance = 120.00(Ft.) Highest elevation= 66.22(Ft.) Lowest elevation= 58.44(Ft.) Elevation difference= 7.78(Ft.) Time of concentration calculated by the urban areas overland flow method (App X-C) = 4.23 min. TC= [1.8*(1.1-C)*distanceA.5)7.{% slopeA(l/3)] TC= [1.8*(1.1-0.7000)*{120.00~.5)/( 6.48~(1/3)]= 4.23 Setting time of concentration to 5 minutes Rainfall intensity (I) = 7.114 for a 100.0 year storm Effective runoff coefficient used for area {Q=KCIA) is C = 0.700 Subarea runoff= 0.548(CFS) Total initial stream area= 0.ll0(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 146.000 to Point/Station 147.000 **** STREET FLOW TRAVEL TIME + SUBAREA FJ;..iOW ADDITION **** If / 1 'I'oJ;> or street segment elevation= 58.440(F't.J Eno of street segment elevation= 45.150(Ft.) Length of street segment = 390.000(Ft.) Height of curb above gutter flowline = 6.0(In.) Width of half street (curb to crown) = 20.000(Ft.) Distance from crown to crossfall grade break EXHIBIT A (Excerpt from Hydrology Report R.P. 94=06) A .,.J .- I I I I I I I I I I I I I I I I I I I RUNOFF CALCULATION Page4 of 9 Pages Project Name: Ocean Vista Estates, Carlsbad Soil Classification = "D" ' Job No. 257-06 Date: June 19, 2007 North \PJatershed 1~rea Hydrology Frequency = 'l 00 Yr. Stom1 C= 0.79 Table 3-1 6 Hour Precipitation P6= '2.5 Fig. 3-1 (A) North Area Drainage Stud Without Diversion From Node 1a to Node 2fi Area No A= 5.80 Ac. Distance Travel L= 960 Ft Effective Slope s = 1.15% ,_ Initial Time of Concentration Ti= 7.67 Miin .. Table 3..:2 Maximum Traveled Distance Lm= 70.25 Ft Interpolated Trial Runoff Q= 17.57 Cfs. Initial Q = 2 Cfs Depth of Water @ Gutter Y= 0.55 Velocity of Gutter Vg= 3.80 Remaining Distance Travel Lr= 889.75 Ft Renaming Time to Travel Tr= 3.90 Min. Tr= LrNg/60 Time of Concentration Tc= 11.57 Min. Intensity I= 3.83 Ins/Hr CxA CA= 4.58 DesiQned Runoff Q= 17.57 CFS (A) North Area Drainage Stud -Area "A" Diverted to The South From Node 1a to Node 2fi Area Nd A= 4.88 Ac. Distance Travel L= 960 Ft Effective Slope s = 1.15% Initial Time of Concentration Ti= 5.95 Miin .. Table 3-2 Maximum Traveled Distance Lm= 62.25 Ft Interpolated Assumed Runoff Q= 16.31 Cfs. Initial Q = 2 Cfs Depth of Water @ Gutter Y= 5.20 Velocity of Gutter Vg= 3.76 Remaining Distance Travel Lr= 897.75 Ft Renaming Time to Travel Tr= 3.98 Min. Tr= LrNg/60 Time of Concentration Tc= 9.93 Min, Intensity I= 4.23 Ins/Hr CxA CA= 3.86 Designed Runoff Q= 16.31 CFS I I I I I I I I I I I I I I I I I I I HYDROLOGY & HYDRAULICS CALCULATIONS Project: Ocean Vista Estates, Carlsbad Job No. 257-06 Project Watershed Analysis Frequency= 100 Yr. Storm 6 Hour Precipitation Drainage Study Within Property Watershed POST-DEVELOPMENT Area Of the Project A= Distance Travel L= Effective Slope s = Initial Time of Concentration Ti= Maximum Traveled Distance Lm= Trial Runoff Q= Street Cross Slope Sx= Manning's Roughness n= Depth of Water @ Gutter Y= Velocity of Gutter Vg= Remaining Distance Travel Lr= Remaininq Time to Travel Tr= Total Time of Concentration Tc= Intensity I= CxA CA= Desiqned Runoff Q100 = Existina 40% Impervious PRE-DEVELOPMENT Area Of the Project A= Distance Travel L= Effective Slope s = Initial Time of Concentration Ti= Maximum Traveled Distance Lm= Trial Runoff Q= Street Cross Slope Sx= Manning's Roughness n= Depth of Water @ Gutter Y= Velocity of Gutter Vg= Remainina Distance Travel Lr= Remaininq Time to Travel Tr= Total Time of Concentration Tc= Intensity I= CxA CA= Designed Runoff Q100 = DETENTION PIPE INPUT VARIABLES· Six (6)Hour Precipitation Amount (Inches) Pe= Total Time of Concentration (Min.) Tc= Coefficient of Runoff C= Area ( 813, 814, & 815) A= Time to Peck {Tp = 1.1072 x Tc) Tp = Page5 of 9 Pages Soil Classification = "D" ' Date: June 14, 2007 ATTACHMENT A C= 0.79 Table 3-1 P6= 2.5 Fig. 3-1 Node 1 to node 2 0.92 Ac. 246 Ft 6.70% 4.03 Miin .. Table 3-2 96.70 Ft I nterpqlate.d 5.13 Cfs. Initial Q = 2 Cfs 2.00% Cb & Gut Chi. Flow 0.015 0.20 5.37 149.30 Ft 0.46 4.49 7.06 Ins/Hr 0.73 5.13 CFS C= 0.57 Table 3-1 0.92 Ac. 246 Ft 6.70% 8.09 Miin .. Table 3-2 100 Ft Interpolated 1.49 Cfs. Initial Q = 2 Cfs 2.00% Cb & Gl!t Chi: Flow 0.015 0.12 3.94 146.00 Ft 0.62 '. 8.71 4.61 Ins/Hr 0.52 2.42 CFS - , 100 Year .. 2.50 Fig. 3-1 4.49 See Post-Development Hydroloav 0.79 Table 3-1 0.92 Ac. 4.97 Mi.nutes I I I I I I I I I I I I I I I I I I I HYDROLOGY & HYDRAULICS CALCULATIONS Page6 of9 Pages Project: Ocean Vista Estates, Carlsbad Soil Classific~tion = "D" -Job No. 257-06 Date: June 14, 2007 Project Watershed Analysis ATTACHMENT A Frequency= 100 Yr. Storm 6 Hour Precipitation Time of Hydrograph to Begin Tb= -Minutes Time of Hydrograph to End (Te =Tp+1.5xTp) Te= 12.43 Minu_tes ITc = 7.44 x P6fTcA.645 ITc= 7.06 Ins/hr. Qp = C x ITc X A, (C.F.S.) Qp= 5.13 See Post-Development Hvdroloav DETENTION PIPE (Cont'd) ' SURROUNDING FLOW (Qs) Depth of Precipitation for 2 Hours (D120 = 0.67 D120 = 1.70 Inches Depth of Precipitation for Hydrograph (DH = PE DH= 0.73 Inches Surrounding Intensity: ls= 60(D120 -DH)/ (12 Is= 0.53 lns./hr. Qs = C x Is x A ,(C.F.S.) Qs= 0.39 CFS OUTFLOW ( Existing Condition) Runoff (CFS) Qn= 2.42 See Pre-Development Hydroloav RESERVOIR STORAGE D1 = Qp-Qs D1 = 4.74 CFS D2 = Qn-Qs D2= 2.03 CFS Volume in Acre-Foot Ac/Ft= 0.02 . 1,012.52 Cu.Ft NOTE: The storm water within the project limits for a 100 year storm frequency ge'nerates post-development runoff of Q = 4. 75 CFS and pre-development runoff of Q = 2.1 O CFS. A required volume of 1,013 cu.ft. is necessary to store the 100 year storm. The detention pipe system and the street crown storage has the capacity of 1,105 cu. ft. which exceed post-development runoff volume ' I I I I I I I I I I I I I I I I I I I HYDROLOGY & HYDRAULICS CALCULATIONS Project: Ocean Vista Estates, Carlsbad Job No. 257-06 Project V\Jatershsd Analysis Frequency= 100 Yr. Storm 6 Hour Precipitation Drainage Study Within Property Lot Line Limits POST-DEVELOPMENT Impervious Area Pervious Area Total Area Percentage of Imperviousness - Ar~a Of tbe Project A= Distance Travel L= Effective Slope s = Initial Time of Concentration Ti= Maximum Traveled Distance Lm= Trial Runoff Q= $tr,eet Cross Slope Sx= Mannin~:i's Rouqhness n= Depth of Water @ Gutter Y= Velocity of Gutter Vg= Remaining Distance Travel Lr= Remaining Time to Travel Tr= Time of Concentration Tc= Intensity I= CxA CA= Designed Runoff Q100 = PRE-DEVELOPMENT Area 0.f the Project A= Distance Travel L= Effective Slope s = Initial Time of Concentration Ti= Maximum Traveled Distance Lm= Trial Runoff Q= Gutter Side Slope SS= Manning's RouQhness n= Depth of Water @ Gutter Y= Velocity of Gutter Va= Remainina Distance Travel Lr= Remainina Time to Travel Tr= Time of Concentration Tc= Intensity I= CxA CA= Designed Runoff Q100 = Page7 of 9 Pages Soil Classification = "D" Date: June 14, 2007 ATTACHMENT A C= 0.85 Table 3-1 PS= 2.5 Fig. 3-1 Node 1 to node 2 21304 2245 23549 90.47% 0.62 Ac. 185 Ft 0.50% 4.20 Miin .. Table 3-2 50.00 Ft Interpolated 3.29 Cfs. Initial Q = 2 Cfs 2.00% Cb & Gut Chi. Flow 0.015 0.27 1.81 135.00 Ft 1.24 Min. Tr= LrNg/6O 5.44 Min. 6.24 Ins/Hr 0.53 3.29 CFS C= 0.35 Table 3-1 0.62 Ac. 185 Ft 0.50% 4.20 Miin ... Table 3-2 50.00 Ft Interpolated 1.40 Cfs. Initial Q = 2 Cfs 2.00% Channel Flow 0.015 0.10 2.40 135.00 Ft 0.94 Min. Tr= LrNa/6O 5.14 Min. 6.47 Ins/Hr 0.22 1.40 CFS I I I I I I I I I I I I I I I ·I I I I HYDROLOGY & HYDRAULICS CALCULATIONS Pages of9 Pages Project: Ocean Vista Estates, Carlsbad Soil Classification = "D" Job No. 257-06 Date: June 14, 2007 Project Watershed Analysis ATTACHMENT A Frequency= 100 Yr. Storm 6 Hour Precipitation DETENTION PIPE INPUT VARIABLES 100 Year Six (6)Hour Precipitation Amount (Inches) P6 = 2.50 Fig. 3-1 Total Time of Concentration (Min.) Tc= 5.44 See Post-Development Hydroloav Coefficient of Runoff C= 0.85 Table 3-1 Area ( 813, 814, & 815) A= 0.62 Ac. Time to Peck (Tp = 1.1072 x Tc) Tp= 6.02 Minutes Time of Hydroaraph to Begin Tb= -Minutes Time of Hydrograph to End (Te =Tp+1.5xTp) Te= 15.06 Minutes ITc = 7.44 x P6/TcA_545 ITc= 6.24 Ins/hr. Qp = C x ITc x A, {C.F.S.) Qp= 3.29 See Post-Development HydrolOQV SURROUNDING FLOW (Qs) Depth of Precipitation for 2 Hours (D120 = 0.6i D120 = 1.70 Inches Depth of Precipitation for Hydrograph (DH = P DH= 0.78 Inches Surrounding Intensity: Is= 60(0120 -DH)/ (1~ Is= 0.52 lns./hr. -- Qs d: C x Is x A ,(C.F.S.) Qs= 0.27 CFS OUTFLOW ( Existing Condition) Runoff (CFS) Qn= 1.40 See Pre-Development Hydroloav RESERVOIR STORAGE D1 = Qp-Qs D1= 3.02 CFS D2 = Qn -Qs D2= 1.13 CFS Ts1 =Beain Surroundinq Time Ts1 = 0.5_0 Minute_s Ts2 = End Surrounding Time Ts2 = 2.35 Minutes Volume in Acre-Foot Ac/Ft= 0.02 850.59 Cu.Ft NOTE: The storm water within the project limits for a 100 year storm frequency generates post-development runoff of Q = 3.29 CFS and pre-development runoff of Q = 1 .40 CFS. A required volume of 556 cu.ft. is necessary to store the 100 year storm. The detention pipe system and the street crown storage has the capacity of 1,105 cu.ft. which exceeds the required volume before flowing to the north I I I I I I I I I I I I I I I I I I I HYDROLOGY & HYDRAULICS CALCULATIONS Page 9 of 9 Pages Project: Ocean Vista Estates, Carlsbad Soil Classification = "D" Job No. 257-06 Date: June 14, 2007 Project Watershed Analysis ATTACHMENT A Frequency= 100 Yr. Storm 6 Hour Precipitation RUNOFF CAPACITY OF THE X-GUTTER@ INTERSECTION OF OCEAN ST. & BEACH AVE. Sta. 29+30 X-Gutter Slope S= 0.67% Width W= 10 Ft. Depth d= 0.08 Ft. Manning's Roughness n= 0.015 Wetted Area A= 0.4 Sq. Ft. Hydravulics Radius R= 0.04 Ft. Runoff Capacity Q= 0.38 Cfs. RUNOFF CAPACITY OF THE CHANNEL@. THE INTERSECTION UP TO THE ST. CROWN ELEVATION Wetted Area A= 2.16 Sq. Ft. Hydraulics Radius R= 0.10291 Ft. Manning Roughness n= 0.015 Channel Slope S= 0.67% Runoff Capacity Q= 3.84 Cfs. > 3.29 Cfs Post Generated Runoff Determine the Water Surface Elevation of the Channel (See Channel Section P'rofile) _ Horiz:Vert. Slope 10.91:1 Left Side Slope 21 = 10.91 Horiz:Vert. Slope 23.44: 1 Left Side Slope 22= 23.42 Runoff Capacity of the Gutter Qg= 0.38 Cfs. Channel Slope S= 0.67% Manning's Roughness n= 0.015 Flow Line Elev. Of Channel F.L. = 41.80 • Post-Development Runoff Qpost= 3.29 Cfs. Depth of Water @ Flow Line v= 0.32 Ft. Hydraulic Grade Line W.S. 42.12 Street Crown Elevation Crown= 42.20 Free Board F.L. 0.08 Ft. Determine the Water Surface Elevation of the Channel of Post-Development Runoff Minus Pre- Development (Existing) Runoff. Q = 3.29 -1.40 = 1.89 Cfs Horiz:Vert. Slope 10.91:1 Left Side Slope 21 = 10.91 Horiz:Vert. Slope 23.44: 1 Left Side Slope 22= 23.42 Runoff Capacity of the Gutter Qg= 0.38 Cfs. Channel Slope S= 0.67% Manning's Roughness n= 0.015 Flow Line Elev. Of Channel F.L. = 41.80 Post-Development Runoff Qpost = 1.89 Cfs. Project Development Increase Depth of Water @ Flow Line y= 0.23 Ft. Runoff Hydraulic Grade Line w.s. 42.03 Street Crown Elevation Crown= 42.20 Free Board F.L. 0.17 Ft. I I I I I I I 1. I I· I I I I I I I I I ATTACHMENT B EXISTING DEVELOPMENT HYDROLOGY & HYDRAULICS CALCULATIONS Storm Frequency= 50 Years (No Project Participation) I I I I I I -I I I I I I I I I I I I I RUNOFF CALCULATION Page 1 of 3 Pages Project Name: Ocean Vista Estates, Carlsbad Soil Classification = "D" • Job No. 257-06 Date: April 26, 2007 Existing Development Hydrology ATTACHMENT 8 Frequency = 50 Yr. Storm C= 0.79 Table 3-1 6 Hour Precipitation PG= 2.00 Fig. 3-1 NOTE: This calculation is being prepared to analyze the outfall runoff generated from Basins 8,C & D in conjunction with the existing runoff per DWG. # 347-2 Sheet# 2 without project participation From Node 4 to Node 3 Area B A= 3.78 Ac. Distance Travel L= 560 Ft Effective Slope s = 3.24% .. Initial Time of Concentration Ti= 4.83 MJin .. Table 3-2 Maximum Traveled Distance Lm= 90.60 Ft Interpolated Trial Runoff Q= 8.48 Cfs. Initial Q = 2 Cfs Street Cross Slope Sx= 2.00% Cb & Gut Chi. Flow Manning's Roughness n= 0.015 Depth of Water @ Gutter Y= 0.27. Velocity of Gutter • Va= 4.63 Remainina Distance Travel Lr= 469.40 Ft Remaining Time to Travel Tr= 8.20 Min. Time of Concentration Tc= 13.03 Min. Intensity I= 2.84 Ins/Hr CxA CA= 2.99 Designed Runoff Qso= 8.48 CFS From Node 3 to Node 5 Area C A= 0.14 Ac. Desiqned Runoff Qso = 8.48 CFS Pipe Lenqth L= 42.50 Ft. ,. Pipe Diameter d= 1.50 Ft. Friction Slope Sf= 0.65% Manninq's Coef. .n = 0.013 Depth of Water y= 1.50 Ft. Velocity V= 4.80 Ft./Sec. -- Velocity Head hv = 0.36 Ft. Travel Time Ti= 0.31 Min. Time of Concentration Tc= 13.34 • Min. Intensity I= 2.80 Ins/Hr Axe AC= 0.11 Runoff q= 0.31 CFS Total Desioned Runoff Q100 = 8.79 CFS From Node 5 to Node 6 Area D A= 0.16 Ac. Designed Runoff Qso= 8.79 CFS Pipe Length L= 74.64 Ft. I I I I I I I I I I I I I I I I I I I RUNOFF CALCULATION Project Name: Ocean Vista Estates, Carlsbad Job No. 257-06 Existing Development Mydrology Frequency 50 Yr. Storm 6 Hour Precipitation Pipe Diameter d= Friction Slope Sf= Manning's Coef. .n = Depth of Water v= Velocity V= Velocity Head hv= Travel Time Ti= Time of Concentration Tc= Intensity I= CxA AxC= Area Runoff q= Designed Runoff Q50 = Q Q100 = 24.50 (Confluence@ Node 142 =) Qso = 20.07 Node 6) Q10 = 16.519 CONFLUENCE Qso= Confluence @ Node 142 20.07 Node6 9.14 Confuence Q = 27.37 From Node 6 to Outfall Designed Runoff Qso= Pipe Length L= Pipe Diameter d= Pipe Slope So= Manning's Coef. .n = Depth of Water y= Velocity V= Velocity Head hv= Critical Depth de = de= Critical Velocity Ve = Ve= Critical Velocity Head hvc = hvc = Coef. Manhole Entrance ke= Manhole Loss Mh= Invert Elevation 1.E= Hydraulic Grade Line HGL= Page2 of 3 Pages Soil Classification = "D" Date: April 26, 2007 • ATTACHMENT B C= 0.79 Table 3-1 P6= 2.00 Fig. 3-1 1.50 Ft. 0.70% 0.013 1.50 Ft. 4.97 Ft/Sec. 0.38 Ft. 0.25 Min. 13.59 Min. 2.77 Ins/Hr 0.13 0.35 CFS 9.14 CFS Tc I Prorate 11.93 4.06 See Hydroloav Report for 10.86 3.30 RP. 94-06. Dwg. # 347-2E 9.51 2.71 Revised Datea, 6/1/98 Tc I Watershed Area 10.86 3.30 10.28 13.59 2.77 27.37 CFS 74.64 Ft. 1.50 Ft. 26.00% 0.013 0.76 Ft. 30.47 Ft./Sec. 14.42 Ft. 1.49 Ft. 15.50 3.73 0.18 0.67 Ft. 35.28 41.17 .. I I I I I I I I I I I I I I I I I I I HYDRAULICS Project Name: Ocean Vista Estates, Carlsbad Job No. 257-06 Hydraulic of Existing Pipe Frequency= 50 Yr. Storm 6 Hour Precipitation Node 6 to Node 5 Designed Runoff Q50 = Pipe Length L= Pipe Diameter d= Friction Slope Sf= Manning's Coef. .n = Depth of Water y= Velocity V= Velocity Head hv= ExistinQ Hydraulic Grade Line HGL(in) = Hydraulic Grade Line (out) HGL{out) = Manhole Entrance Loss Coef. Ke= Manhole Loss Myles= Bend Angle= Bend Loss MHb= Hydraulic "Grade Line (in) HGL {in)= Node 5 to Node 3 Designed Runoff Q50 = Pipe LenQth L= Pipe Diameter d= Friction Slope Sf= Manning's Coef. .n = Depth of Water y= Velocity V= Velocity Head hv= ExistinQ Hydraulic Grade Line HGL(in) = Hydraulic Grade Line {out) HGL(out) = Manhole Entrance Loss Coef. Ke= Manhole Loss Mh= Bend Angle= Bend Loss MHb= Hydraulic "Grade Line {in) HGL (in)= Page3 of 3 Pages Soil Classification = "D" Date: April 26, 2007 ATTACHMENT 8 9.14 CFS 74.64 Ft. 1.50 Ft. 0.76% 0.013 1.50 Ft. 5.17 Ft./Sec. 0.42 Ft. 41.17 41.74 0.18 0.07 66.00 0.09 42.23 Ex T.C.4q.26 Gutter 42.45 8.79 CFS 42.76 Ft. 1.50 Ft. 0.70% 0.013 1.50 Ft. 4.97 Ft./Sec. 0.38 Ft. 42.23 42.53 0.18 0.07 66.00 0.08 42.98 Ex T.C.42.49 Gutter41:68 FLOODED I I I I I I I I I I . ~. _.·. I I I I I I I I --· I ATTACHMENT C EXISTING DEVELOPMENi HYDROLOGY & HYDRAULICS CALCULATIONS Storm Frequency= 10 Years (No Project Participation) I I I I I I I I I I I I I I I I I I RUNOFF CALCULATION Page 1 of 3 Pages Project Name: Ocean Vista Estates, Carlsbad Soil Classification = "D" Job No. 251-06 Date: June 19, 2007 Existing Development Hydrology ATTACHMENT C Frequency = 10 Yr. Storm C= 0.79 Table 3-1 6 Hour Precipitation PG= 1.6 Fig. 3-1 NOTE: This calculation is being prepared to analyze the outfall runoff generated from Basins B,C & D in conjunction with the existing runoff per DWG. # 347-2 Sheet# 2 without the participation of the project. storm water runoff From Node 4 to Node 3 Area B A= 3.78 Ac. Distance Travel L= 560 Ft Effective Slope s = 3.24% Initial Time of Concentration Ti= 4.83 Miin .. Table 3-2 -- Maximum Traveled Distance Lm= 90.60 Ft Interpolated Trial Runoff Q= 6.79 Cfs. Initial Q = 2 Cfs Street Cross Slope Sx= 2.00% Cb & Gut Chi. Flow Manning's Roughness n= 0.015 Depth of Water @ Gutter Y= 0.25 Ft Velocity of Gutter Vg= 4.38 Ft./Sec. Remaining Distance Travel Lr= 469.40 Ft Remaining Time to Travel Tr= 8.20 Min. Time of Concentration Tc= 13.03 Min. Intensity I= 2.27 Ins/Hr CxA CA= 2.99 DesiQned Runoff Qso= 6.79 CFS From Node 3 to Node 5 Area C A= 0.14 Designed Runoff Q10= 6.79 CFS Pipe Length L= 42.50 Ft. Pipe Diameter d= 1.50 Ft. Pipe Slope So= 1.80% Manning's Coef. .n = 0.013 Depth of Water y= 0.73 Ft. Velocity V= 7.90 Ft.!Sec. Velocity Head hv= 0.97 Ft. Travel Time Ti= 0.50 Min. Time of Concentration Tc= 13.53 Intensity I= 2.22 Ins/Hr AxC AC= 0.11 Runoff q= 0.25 Total Designed Runoff Q10= 7.04 .. I I I I I I I I I I I I I I I I I I I RUNOFF CALCULATION Project Name: Ocean Vista Estates, Carlsbad Job No. 257-06 Existing Development Hydrology Frequency= 10 Yr. Storm 6 Hour Precipitation From Node 5 to Node 6 Area D A= Designed Runoff Q10= Pipe Length L= Pipe Diameter d= Pipe Slope So= Manning's Coef. .n = Depth of Water v= Velocity V= Velocity Head hv = Travel Time Ti= Time of Concentration Tc= Intensity I= CxA Ax.C= Area Runoff q= Deigned Runoff Q10= Confluence @ Node 6 Q10= Q1= 7.32 Node 142 Q2= 16.52 Confluence Q = 22.91 From Node 6 to Outfall Designed Runoff Q10= Pipe Length L= Pipe Diameter d= Pipe Slope So= Manning's Coef. .n = Depth of Water v= Velocity V= Velocity Head hv= Criitical Depth de= Critical Velocity Head twc = Ve= Critical Velocity Head hvc = hvc= Coeff. Manhole Entrance ke= Manhole Loss Mh= Invert Elevation I.E= Hydraulic Grade Line HGL= Page2 of 3 Pages Soil Classification = "D" Date: June 19, 2007 ATTACHMENT C C= 0.79 Table 3-1 PG= 1.6 Fig. 3-1 0.16 7.04 CFS 69.00 Ft. 1.50 Ft. 2.00% 0.013 0.73 Ft. 8.29 Ft.lS$C. 1.07 Ft. 0.14 Min. 13.67 Min. 2.20 lns./hr. 0.13 0.28 CFS 7.32 CFS Tc I 13.67 2.20 11.94 2.71 Per Drainage Report R.P.94-06 11.94 22.91 CFS 74.64 Ft. 1.50 Ft. 26.00% 0.01_3 0.69 Ft. 29.12 Ft./Sec. 13.1'7 Ft. 1.48 Ft. 13.01 2.63 Ft. 0.18 4.28 Ft. 35.28 39.56 I I I I I I I I I I I I I I I I I I I HYDRAULICS Project Name: Ocean Vista Estates, Carlsbad Job No. 257-06 Hydraulic of Existing Pipe Frequency= 10 Yr. Storm 6 Hour Precipitation Node 6 to Node 5 Designed Runoff Q10= Pipe Length L= Pipe Diameter d= Friction Slope Sf= Manning's Coef. .n= Depth of Water y= Velocity V= Velocity Head hv= Existing Hydraulic Grade Line HGL(Ex) = Hydraulic Grade Line (out) HGL(out) = Manhole Entrance Loss Coef. Ke= Manhole Loss Mhloss = Bend Anole = Bend Loss MHb= Hydraulic "Grade Line (in) HGL (in)= Node 5 to Node 3 Desioned Runoff Q10= Pipe Lenoth L= Pipe Diameter d= Friction Slope Sf= Mannino's Coef. .n= Depth of Water v= Velocity V= Velocity Head hv= Hydraulic Grade Line HGL(ln) = Hydraulic Grade Line (out} HGL(out) = Manhole Entrance Loss Coef. Ke= Manhole Loss Mhloss = Hvdraulic "Grade Line (in) HGL (in)= Page3 of 3 Pages Soil Classification = "D" Date: June 19, 2007 ATTACHMENT C 7.04 CFS 69.00 Ft. 1.50 Ft. 0.45% 0.013 1.50 Ft. 3.98 Ft./Sec. 0.25 Ft. 39.56 Assumed Per Imp. Plan 39.87 0.18 0.04 Ft. 66.00 Deorees 0.05 Ft. 40.16 Ex T.C. 43.60 Gutter 42.83 6.79 CFS 42.76 Ft. 1.50 Ft. 0.42% 0.013 1.50 Ft. 3.84 Ft./Sec. 0.23 Ft. 40.16 40.34 0.18 0.04 40.61 I I I I I I I I I I I I I I I I I I I · ATTACHMENT D POST DEVELOPMENT HYDROLOGY & HYDRAULICS CALCULATIONS , Storm Frequency= 10 Years I I I I ' I I I I I I I I I I I I I I I RUNOFF CALCULATION Project Name: Ocean Vista Estates, Carlsbad Job No. 257-06 Post Development Hydrology Frequency= 10 Yr. Storm 6 Hour Precipitation INITIAL HYDROLOGY (OVERLAND TIME) From Node 1 to node 2 . Area Of the Project Distance Travel Effective Slope Initial Time of Concentration Maximum Traveled Distance Trial Runoff Street Cross Slope Manning's Roughness Depth of Water @ Gutter Velocity of Gutter Remaining Distance to Travel Remainina Time to Travel Time of Concentration Intensity CxA . Desianed Runoff Existing 40% Impervious PRE-DEVELOPMENT Area Of the Project Distance Travel Effective Slope Initial Time of Concentration Maximum Traveled Distance Trial Runoff Street Cross Slope Manning's Roughness Depth of Water @ Gutter Velocity of Gutter Remainin_q Distance Travel Remaining Time to Travel Total Time of Concentration Intensity CxA Desianed Runoff SURROUNDING FLOW (Qs) Depth of Precipitation for 2 Hours (D120 = 0.6785 x Ps) Depth of Precipitation for Hydro (DH = Ps xTc".355/5.83) Surrounding Intensity: Is= 60(D120-D1-1) / (1 40 -2.5Tc) Qs = C x Is x A ,(C.F.S.) Page 1 of 6 Pages Soil Classification = -"D" Date: June 19; 2007 SCENARIO No.2 ATTACMENTD C= 0.79 Table 3-1 PG= 1.6 Fig. 3.,.1 A= 0.92 Ac. L= 246 Ft . ' s = 6.70% Ti= 4.03 Miin .. Table 3-2 Lm= 96.70 Ft Interpolated Q= 2.69 Cfs. lniti13I Q = 2 Cfs Sx= 2.00% Cb & Gut Chi. Flow n= 0.015 Y= 0.15 Vg= 4.57 Lr= 149.30 Tr= 0.54 Tc= 4.57 Min. I= 4.47 Ins/Hr CA= 0:92 ' ,, Q100= 4.11 CF$ C= 0.57 Table 3-1 A= 0.92 Ac. L= 246 ft s = 6.70% Ti= 8.0,9 .Miin .. Table 3-2 Lm= 100 Ft Interpolated Q= 1.55 Cfs. Initial Q = 2 Cfs Sx= 2.00% Cb & Gut Chi. Flow n= 0.015 Y= 0.12 Va= 3.98 Lr= 146.00 Ft Tr= 0.61 Tc= 8.70 I= 2.95 Ins/Hr CA= 0.52 Q100 = 1.55 .. CFS D120 = 1.09 lnche_s DH= 0.13 Inches Is= 0.53 lns./hr. Qs= 0.38 CFS I I I I I I I I I I I I I I I I I I I RUNOFF CALCULATION Page2 of 6 Pages Project Name: Ocean Vista Estates, Carlsbad Soil Classification = ''D" Job No. 257-06 Date: June 19, 2007 Post Development Hydrology ATTACMENT D Frequency= 10 Yr. Storm C= 0.79 Table 3-1 6 Hour Precipitation P6= 1.6 Fig. 3-1 . OUTFLOW ( Existing Condition) Runoff (CFS) Qn= 1.55 See Pre-Development Hydrology From Node 2 to Node 3 (DETENTION PIPE) TOTAL STORAGE OF 18" R.C.P. & CLEANOUT .. Lem:ith of Pipe Lp = 362.00 Ft. Diameter of Pipe d= 1.50 Ft. Volume of Pipe Storage Vp= 639.38 Cu.Ft. Depth of Water @ A4-Cleanout y= 3.80 Ft. Volume of Storage@ C.O. Vco= 60.80 Cu.Ft. Total Volume of Storage Total Vol.= 700.18 Cu.Ft. TOTAL TIME OF DETENTION PRIOR TO SPILLOVER Time to Peck (Tp = 1.1072 x Tc) Tp= 5.06 Miin .. Detention Storage . Inflow Time of Hydrograph to End (Te =1.5xTp) Te= 7.59 Miin .. Analysis & Design Total of Time of Detention Prior to Spillover Tt= 12.66 Miin .. ·County .of San Diego Volume of Hydrograph Vol.= 0.02 Ac/fFt April, 1996 Edition or 972.75 Cu.Ft. Inflow Volume Note: Within the Time Span of 5.07 Minutes only 700.18 Cu.Ft. of Storm Water can be stored in the Detention Basin. 273 Cu.Ft. will be spillover into the cleanout and resumed the flow rate of Q = 4.11 Cu.ft./sec From Node 3 to Node 5 Designed Runoff Q10= 4.11 CFS Pipe Length L= 42.76 Ft. Pipe Diameter d= 1.50 Ft. Pipe Flow Full Friction Slope So= 0.14% Under Pressure Manning's Coef. .n = 0.013 Depth of Water y= 1.34 Ft. Velocity V= 2.47 Ft./Sec. Velocity Head hv= 0.10 Ft. Travel Time Ti= 0.29 Min. Time of Concentration Tc= 12.95 Min. Intensity I= 2.28 lns./Hr. From Node 4 to Node 3 Area B A= 3.78 Ac. Distance Travel L= 560 Ft Effective Slope s = 3.44% .. Initial Time of Concentration Ti= 4.83 Miin .. Table 3-2 Maximum Traveled Distance Lm= 90.60 Ft Interpolated Trial Runoff Q= 6.79 Cfs. Initial Q = 2 Cfs Street Cross Slope Sx= 2.00% Cb & Gut Chi. Flow Manning's Roughness n= 0.015 .. Depth of Water @ Gutter Y= 0.25 Ft Velocity of Gutter Vg= 4 .. 38 Ft./Sec. . ! I r I I I I I I I I I I I I I I I I I I I RUNOFF CALCULATION Project Name: Ocean Vista Estates, Carlsbad Job No. 257-06 Post Development Hydrology Frequency= 10 Yr. Storm 6 Hour Precipitation RemaininQ Distance Travel • Remaining Time to Travel Time of Concentration Intensity CxA Designed Runoff From Node 3 to Node 5 Area C Designed Runoff Pipe Length Pipe Diameter Friction Slope Manning's Coef. Depth of Water Velocity Velocity Head Travel Time Time of Concentration Intensity CxA Area Runoff Desiqned Runoff Confluence @ Node 5 Q1= Q2= Confluence Q = From Node 5 to Node 6 Area D Designed Runoff Pipe Length Pipe Diar)leter Friction Slope Manning's Coef. Depth of Water Velocity Velocity Head Travel Time Time of Concentration Intensity CxA Area Runoff Designed Runoff Lr= Tr= Tc= I= CA= Q10= A= Q= L= d= Sf= .n = y= V= hv= Ti= Tc= I= AxC= q= Q10= Q10= 7.04 4.11 11.06 A= Q10= L= d= Sf= .n = y= V= hv= Ti= Tc= I= AxC= q.= Q= Page3 of6 Pages I Soil Classification = •:011 ; Date: June 19, 2007 ATTACMENT D ' C= 0.79 Table 3-1 PG= 1.6 Fig. 3-.1 I 469.40 Ft 8.20 Min. 13.03 Min. ' 2.27 Ins/Hr 2.99 6.79 CFS : 0.14 Ac. : 6.79 CFS r 42.76 Ft. ' 1.50 Ft. Pipe Flow Full t 0.42% Under Pressure I 0.013 l 1.50 Ft. 3.84 Ft./Sec. ! i 0.23 Ft. .. i ' 0.19 Min. ! 13.22 Miiri .. I 2.25 Ins/Hr I t 0.11 I 0.25 CFS I 7.04 CFS I ·i Tc I l 13.22 2.25 ' ; 12.95 2.28 I • 12.95 0.16 AC 11.06 CFS 74.64 Ft. 1.50 Ft. Pipe Flow Full 1.11% Under Pressure 0.013 1.50 Ft. 6.26 Ft./Sec. 0.61 Ft. 0.20 Min. 7.24 Miin .. 3.32 lns./Hr. 0.13 0.42 CFS 11.48 CFS I I I I I I I I I I I I I I I I I I I HYDRAULICS • Project Name: Ocean Vista Estates, Carlsbad Job No. 257-06 Hydraulic of Existing Pipe Frequency= 10 Yr. Storm 6 Hour Precipitation Confluence @ Node 6 Q1= (See Exhibit B) Node 142 Q2= Confluence Q = Node 6 to Outflow DesiQned Runoff Pipe Diameter Pipe Slope Manning's Coef. Depth of Water Velocity Velocity Head Critical Depth Critical Velocity Critical Velocity Head Entrance Loss Coef Entrance Loss Total Head Invert Elevation@ Node 6 Hydraulic Grade Line Node 6 to Node 5 Designed Runoff Pipe Length Pipe Diameter Friction Slope Manning's Coef. Depth of Water Velocity Velocity Head Existing Hydraulic Grade Line Hydraulic Grade Line (out) Manhole Entrance Loss Coef. Manhole Loss Bend Bend Loss Hvdraulic "Grade Line (in) Node 5 to Node 3 (On Existing 18" RCP) DesiQned Runoff Pipe Length Pipe Diameter Friction Slope Manning's 'Coef. Q10= 11.48 16.52 25.87 Q10= d= So= .n = y= V= hv= de= Ve= hvc= Ke= MH loss= H= I.E.= HGL= Q10= L= d= Sf= .n = y= V= hv= HGL(Ex) = HGL(out) = Ke= Mhloss = AnQle = MHb= HGL (in)= Q10= L= d= Sf= .n = Page4 of 6 Pages Soil Classification = "D" Date: June 19, 2007 ATTACMENTD Tc I 7.24 3.32 ... 11.94 2.71 • Draina·ge Report R..P.9"1-06 11.94 25.87 CFS 1.50 Ft. 26.00% 0.013 0.74 Ft. Pipe in Channel Flow 30.04 Ft./Sec. 14.01 Ft. 1.49 Ft. 14.66 Ft./Sec. 3.34 Ft. 0.18 0.60 Ft. 5.42 Ft. 35.28 40.70 11.06 CFS 69.00 Ft. 1.50 Ft. 1.11% Pipe Flow Full 0.013 Under Pressure 1.50 Ft. 6.26 Ft/Sec. 0.61 Ft. 40.70 41.47 0.18 0.11 Ft. 66.00 0.13 Ft. 42.19 Ex T . .C. 43.60 Gutter 42.83 .I 6.79 CFS· 42.76 Ft. 1.50 Ft. Pipe F!ow Full 0.42% Under Pressure 0.013 I I I I I I I I I I I I I I I I I I I HYDRAULICS Project Name: Ocean Vista Estates, Carlsbad Job No. 257-06 Hydraulic of Existing Pipe Frequency= 10 Yr. Storm Depth of Water v= Velocity V= Velocity Head hv= Hydraulic Grade Line HGL(ln) = Hydraulic Grade Line (out) HGL(out) = Manhole Entrance Loss Coef. Ke= Manhole Loss Mhloss = Hydraulic "Grade Line (in) HGL (in)= Bend Angle= Bend Loss MHb= Hydraulic "Grade Line (in) HGL (in)= Node 5 to Node 3 (On Proposed 18" RCP Parallel Line) Designed Runoff Q10_= Pipe Length L= Pipe Diameter d= Friction Slope Sf= Manning's Coef. .n = Depth of Water y= Velocity V= Velocity Head hv= Hydraulic Grade Line HGL(ln) = Hydraulic Grade Line (out) HGL(out) = Manhole Entrance Loss Coef. Ke= Manhole Loss Mhloss = Bend Angle= Bend Loss MHb= Hydraulic "Grade Line (in) HGL (in)= SPILLWAY {End Contration Weir) Designed Runoff Q= Coef. Oc Contration Ce= Height of Weir Y= Ratio of Head/Height Above Bottom HIP= Length of Weir Lw= Head H= Hydraulic Grade Line HGL= Elevation of the Weir Elev. Weir= NOTE: * Handbookk of Hydraulics by Brater & King, Page 5-14, Fig. 5-3 (b) .. Pages of 6 Pages Soil Classification = "D" Date: June 19, 2007 ATTACMENTD 1.50 Ft. 3.84 Ft./Sec. 0.23 • Ft. 42.19 42.37 . - 0.18 0.04 42.19 66.00 0.05 42.51 Ex T.C. 42.49 Gutter 41.68 4.11 CFS 33.00 Ft. 1.50 Ft. Pipe Flow Full 0.15% Under Pressure 0.013 1.50 Ft. 2.33 Ft./Sec. 0.08 Ft 42.19 42.24 0.18 • 0.02 Ft 66.00 0.02 Ft 42.34 Top C.O. 42.49 . 4.11 CFS 3.08 * 3.40 Ft. 0.14 4 Ft 0.48 Ft. 41.24 Gutter Line !=lev. of Curb & Gutter 40.76 . . I I I I I I I I I I I I I I I I I I I HYDRAULICS Page6 of 6 Pages Project Name: Ocean Vista Estates, Carlsbad Soil Classification = \'D" Job No. 257 -06 Date: June 19, 2007 Hydraulic of Existing Pipe ATTACMENTD Frequency = 10 Yr. Storm ORIFICE .. Head H= 3.80 Ft Volume of Detention to be DischarQe Vol.= 700.18 Cu.Ft. Equivalent Area of Water Surface Aws=· 184.26 Sq.Ft. Area of the Orifice 2.00 Inch -a= Number of Orifice No.= 1.00 Coefficient of DischarQe C= 0.67 Time of Discharge to Empty T= 3.32 Hrs. Draw Time EFFECT OF THE 405.00 CU.FT OF STREET CROWN STORAGE PRIOR TO SPILLOVER TO THE NORTH Storage Capacity Surface Area As= 1,869.00 Sq.Ft. Maximum Depth of Water Y= 0.65 Ft. Street Crown StorarQe Volume of Water Vol.= 404.96 Cu.Ft. 18" Detention Pipe Storage Volume Pipe Vol.= 700.18 Cu.Ft. Total Detention Volume Total Vol-= 1,105.14 Cu.Ft. Time to Fill the Detention Storage Volume Qp= 4.11 CFS Time to Peak = 5.06 Min: Up-Peak Rate Increase== 0.0135234 Cu.ft/sec"2 Up-Peak Vol. = 624.02 cu:_Ft. Total Volume= 1,105 Cu.Ft. Balance Volume = 481 Cu.Ft. Drawtime = 7.59 Min. Peak Rate Decrease = 0.00902 Cu.ft/sec"2 Addon Time == 3.8708362 Min. Q = 1,105.14 Cu.ft. Total time to fill== 5.13 Min. Check== 481.12277 1,105.14 Cu.Ft. OK ~ \ ~ ~ 11 11 11 11 11 11 11 11 11 It 11 11 11 11 11 11 11 Given pipe size= 36.00(In.) Calculated individual PiPe flow = 16.519(CFS) Normal flow depth in ploe = 8.74(In.) Flow top width inside plpe = 30.87{In.) Critical Depth= 15.SS(In.) Pipe flow velocity= 12.~6{Ft/s) T~avel time throug~ pipe= 0.0~ min .. Time of concentration (TC) = 11.94 min .. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++~ Process from Point/Station 142.000 to Point/Station 142.0Do· **** CONFLUENCE OF MAIN STREAMS**** Tne rollowing aaca insiae Main scream is liscea: In Main Stream number: 1 Stream flow area= 7.340(Ac.) Runoff from this stream= 16.519{CFS) Time of concentration= 11.94 min. . Rainfall intensity= 2.706(In/Hr) Program is now starting with Main Stream No. 2 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Statioh 144,000 to Point/Station· 146.000 **** INITIAL AREA EVALUATION**** -11, fh_u; Decimal rraccion soil group A= 1.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 0.000 [COMMERCIAL area type ] Initial subarea flow distance = 120.00{Ft.) Highest elevation= 66.22{Ft.) Lowest elevation= 58.44(Ft.) • Elevation difference= 7.78(Ft.) ·•Time of concentration calculated by the urban areas overland flow method (App X-C) = 4.23 min. TC= [l.8*{1.1-C)*distanceA.517.(% slopeA(l/3)) TC= [l.8*(1.1-0.7000)*(120.00~.5)/( 6.48~(1/3)]= Setting time of concentration to 5 minutes Rainfall intensity (I) = 4.743 for a 10.0 year Effective runoff coefficient used for area (Q=KCIA) Subarea runoff= 0.365{CFS) Total initial stream area= 0 . 110 ( Ac . ) · • 4.23 storm is C = 0.700 -++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 146.000 to Point/Station 147.000 **** STREET FLOW TRAVEL TIME+ SUBAREA FLOW ADDITION**** A 17 To~ oI screec segmenc elevacion = ~8.440{Ft.) Ena of street segment elevation= 45.lSO(Ft.) Length of street segment = 390.000(Ft.) Height of curb above gutter flowline = 6.0(In.) Width of half street (curb to crown) = 20.000(Ft.) Distance from crown to crossfall grade break = EXHIBITB (Excerpt from Hydrology Report R.P. 94=06) ·--I,- ATTACHMENT F: FEMA Flood Plain Map