Loading...
HomeMy WebLinkAboutMP 98-01F; Villages of La Costa Greens RV Storage Site; Conditional Use Permit (CUP) (3)HUNSAKER &ASSOCL\TES SAN PLANNING ENGINEERING SURVEYING IRVINE LOS ANGELES RIVERSIDE SAN DIEGO ECO, INC. TENTATIVE MAP ^'^^ DRAINAGE STUDY for LA COSTA GREENS NEIGHBORHOODS 1.1-1.3 City of Carlsbad, California Prepared for: Real Estate Collateral Management Company 1903 Wright Place Suite 180 Carlsbad, CA 92008 w.o. 2352-141 January 24, 2006 DAVE HAMMAR LEX WILLIMAN ALISA VIALPANDO DAN SMITH RAY MARTIN PRELIMINARY Eric Mosolgo, R.C.E. Water Resources Department Manager Hunsaker & Associates San Diego, Inc. 10179 Huennekens St. San Diego, CA 92121 (858) 558-4500 PH (858) 558-1414 FX www.HunsakerSD.com lnfo@HunsakerSD.com DE:fcc H:\REPORTS\2362M41\TMStudy02.doc W.O. 2352-141 1/24/2006 3:27 PM La Costa Greens Neighborhoods 1.1-1.3 TM Drainage Study TABLE OF CONTENTS SECTION Chapter 1 - Executive Summary 1.1 Introduction 1.2 Summary of Existing Conditions 1.3 Summary of Proposed Development 1.4 Summary of Results 1.5 References Chapter 2 2.1 2.2 2.3 2.4 2.5 Methodology & Model Development County of San Diego Drainage Design Criteria Design Rainfall Determination - 100-Year, 6-Hour Rainfall Isopluvial Map - 100-Year, 24-Hour Rainfall Isopluvial Map Runoff Coefficient Determination Rainfall Intensity Determination - Maximum Overland Flow Length & Initial Time of Concentration Table - Urban Watershed Overland Time of Flow Nomograph - Natural Watershed Time of Concentration or Travel Time Nomograph - Gutter & Roadway Discharge-Velocity Chart - Manning's Equation Nomograph - San Diego County Intensity-Duration Design Chart Rational Method Model Development Summary Chapter 3 - 100-Year Hydrologic Modei for Developed Conditions Chapter 4 - Hydrology Exhibits Exhibit 4.1 Developed Condition Hydrology Map IV Chapter 5 - Appendices V Appendix 5.1 Excerpts from "Mass-Graded Hydrology Study for La Costa Greens Neighborhoods 1.1-1.3 & El Camino Real Widening" (including Mass-Graded Hydrology Map) Appendix 5.2 Excerpts from Drawing No. 397-2H "Grading and Drainage Plans for Poinsettia Lane at La Costa Greens", Sheet 8 AH H:\REPORTS\2352M41\TMStudy02.doc W.O. 2352-141 1/24/2006 1:34 PM La Costa Greens Neighborhoods 1.1-1.3 TM Drainage Study CHAPTER 1 - EXECUTIVE SUMMARY 1.1 - Introduction The La Costa Greens Neighborhood 1.1-1.3 site is located north of Poinsettia Lane and west of Alicante Road in the City of Carlsbad, California. The project site is also bound by El Camino Real directly to the west (see Vicinity Maps on this page). All runoff from the site and surrounding improvements will drain southeast to the Alicante Detention Basin, located on the southeast corner of the Poinsettia Lane- Alicante Road intersection, ultimately draining to an unnamed tributary of San Marcos Creek. Runoff from this tributary eventually discharges into San Marcos Creek towards the Batiquitos Lagoon. mOJECT PROJECT SITE ViaNITYMAP iBJom »^ BOUmMY LA COSTA VICINFTY MAP This study analyzes 100-year developed conditions peak flowrates from the proposed La Costa Greens Neighborhood 1.3 Recreational Vehicle Storage site and 100-year anticipated peak flowrates from a portion ofthe neighboring La Costa Greens Neighborhood 1.3 future multi-family development. The proposed RV Storage site and future multi-family residential site as well as the adjacent La Costa Greens Neighborhoods 1.1 and 1.2 sites have been mass graded perthe "Grading & Erosion Control Plans for La Costa Greens Neighborhoods 1.01-1.03" prepared by Hunsaker & Associates. AH H:\REPORTS\2352\141\TMSludy02.dpc W.O. 2352-141 1/24/2006 1:34 PM La Costa Greens Neighborhoods 1.1-1.3 TM Drainage Study Treatment of storm water runoff from the site has been addressed in a separate report - the "Storm Water Management Plan for La Costa Greens Neighborhoods 1.2 &1.3", prepared by Hunsaker & Associates and dated September 2005. Per County of San Diego drainage criteria, the Modified Rational Method should be used to determine peak design flowrates when the contributing drainage area is less than 1.0 square mile. Since the total watershed area discharging from the site is less than 1.0 square mile, the AES-2003 computer software was used to model the runoff response perthe Modified Rational Method. Methodology used forthe computation of design rainfall events, runoff coefficients, and rainfall intensity values are consistent with criteria set forth in the "2003 San Diego County Hydrology Manuaf. A more detailed explanation of the methodology used (charts, nomographs, tables, etc.) for this analysis is listed in Chapter 2 ofthis report. 1.2 - Summarv of Existing Conditions The La Costa Greens Neighborhoods 1.1-1.3 site is part ofthe La Costa Greens development in the City of Carlsbad, California. The existing La Costa Greens 1.1- 1.3 site has been mass-graded perthe "Grading & Erosion Control Plans for La Costa Greens Neighborhoods 1.01-1.03" and is awaiting future development. Runoff from the mass-graded La Costa Greens Neighborhood 1.3 RV Storage site and the future multi-family residential site flows into a desiltation basin located in the southwest corner ofthe mass-graded site. The runoff then flows southeasterly towards Poinsettia Road, where it is intercepted via an existing U-Type headwall at approximate Sta. 23+00 per Dwg. No. 397-2H, and then via storm drain beneath Poinsettia Road to the Alicante Detention Basin located in the southeast corner of the Poinsettia Lane-Alicante Road intersection. The peak discharge from this basin is drained by a double 8-ft by 5-ft reinforced concrete box and then flows southwards to an unnamed tributary of San Marcos Creek. The runoff then flows in a southerly direction along the site boundary ofthe La Costa Greens Golf Course, west ofthe Phase I development area. All the runoff eventually drains under Alga Road via three 96" RCP culverts, as shown in Drawing No. 397-2, and discharges into San Marcos Creek towards the Batiquitos Lagoon. The existing condition hydrologic analysis ofthe La Costa Greens 1.1-1.3 development was completed and is discussed in the "Mass-Graded Hydrology Study for La Costa Greens Neighborhoods 1.1-1.3 & Ei Camino Real Widening", prepared by Hunsaker & Associates and dated August 23, 2005. The Regional Water Quality Control Board has identified San Marcos Creek as part ofthe Carlsbad Hydrologic Unit, San Marcos Hydrologic Area, and the Batiquitos Hydrologic Subarea (basin number 904.51). AH H:\REPORTS\2352M41\TMStudy02.doc W O. 2352-141 1/24/2006 1:34 PM La Costa Greens Neighborhoods 1.1-1.3 TM Drainage Study 1.3 - Summarv of Proposed Development The proposed La Costa Greens Neighborhoods 1.1-1.3 are to be developed in individual stages. This report and the current development ofthis site incorporates a portion of Neighborhood 1.3 - the proposed RV Storage site. Thus, this portion of the development also includes the construction of a superelevated sen/ice road to the RV site, a temporary AC 6-inch berm to convey road surface flow and the proposed outlet structure intended to service the development in ultimate developed conditions. This report does not include discussion on future development of Neighborhood 1.1 and Neighborhood 1.2 as they are to remain in their current mass-graded state. However, flows from the future multi residential lots have been estimated within this drainage study by applying a runoff coefficient of 0.71 for all areas other than paved surface area draining to the southern outlet location. As such, the flows generated by this study should be quite similar to those undertaken forthe future multi family residential developments, such that the outlet storm drain can be constructed with capacity for future conveyance. Development of the site will not cause any diversion to or from the existing San Marcos Creek watershed. All pipes will be sized forthe 100-year event storm event. Detailed storm drain system calculations will be provided at the final engineering phase. Prior to discharging from the project site, first flush runoff will be treated via a flow- based BMP treatment proposed in accordance with standards set forth by the Regional Water Quality Control Board and the City of Carisbad's Stormwater Standards Manual (see the "Storm Water Management Plan for La Costa Greens Neighborhood's 1.2 & 1.3", prepared by Hunsaker & Associates dated January 2006). 1.4 - Summarv of Results For the Rational Method Analysis, a runoff coefficient of 0.35 was used for undisturbed, natural terrain and a runoff coefficient of 0.87, corresponding to areas that are 95% impervious, was used forthe RV Storage site and subareas consisting mostly of paved streets, sidewalks, and parkways. A runoff coefficient of 0.71, corresponding to high density residential areas with 24.0 DU/acre, was used forthe future multi-family residential development. All runoff coefficients are based on the criteria set forth in the "2003 San Diego County Hydrology Manuaf. AH H:\REPORTS\2352M41\TMStudy02.doc W.O. 2352-141 1/24/2006 1:34 PM La Costa Greens Neighborhoods 1.1-1.3 TM Drainage Study Table 1 below summarizes developed conditions drainage areas and resultant 100- year peak flowrates at the storm drain discharge locations. Developed condition peak flowrates, listed on Table 1, are based on the AES-2003 computer program (see Chapter 2 for methodology and model development and Chapter 3 for the AES model output). Per San Diego County rainfall isopluvial maps, the design 100-year rainfall depth for the site area is 2.8 inches for the 6-hour storm. Watershed delineations and node locations are visually depicted on Exhibit 4.1 (see Chapter 4) for developed conditions and in Appendix 5.1 (see Chapter 5) for mass-graded conditions. Table 1 - Summary of Mass-Graded & Developed Conditions Drainage Location Drainage Area (Ac) 100-Year Peak Flow (cfs) Southern Outlet (Neighborhood 1.3) 5.3 18.6 Poinsettia Lane 36-inch RCP Headwall 42.8 64.4 Per Dwg. 397-2H (attached), a headwall has been constructed to intercept flows discharged from the La Costa Greens Neighborhood 1.1-1.3 site and tributary hillside terrain. This receiving headwall discharges to an existing 36-inch RCP storm drain, with a corresponding design capacity of 63.6 cfs. The proposed ultimate conditions La Costa Greens Neighborhood 1.1-1.3 site drains approximately 64.4 cfs to this receiving headwall, an increase of 0.8 cfs. As this is a very minor increase from that ofthe design flow, the downstream receiving storm drain system will have negligible impacts from the development of the project site. Development ofthe mass-graded La Costa Greens Neighborhood 1.1-1.3 site has been anticipated per the "Master Detention Study for La Costa Greens" prepared by Hunsaker & Associates and dated August 2003. Developed flows from the northern portions of the La Costa Greens development, inclusive of flows from the near by Bressi Ranch, are conveyed via storm drain to the Alicante Detention Basin. Increase in developed flow due to the regional development of the La Costa Greens (inclusive of Neighborhoods 1.1-1.3) project is mitigated by this large detention facility. Final storm drain and inlet design details will be provided at the final engineering stage of the development. AH H:\REPORTS\2352M41\TMStudy02.doc W.O. 2352-141 1/24/2006 1:34 PM La Costa Greens Neighborhoods 1.1-1.3 TM Drainage Study 1.5 - References "San Diego County Hydrology Manual"; Department of Public Works - Flood Control Division; County of San Diego, California; Revised June 2003. "Mass-Graded Hydrology Study for La Costa Greens Neighborhoods 1.1-1.3 & El Camino Real Widening", Hunsaker & Associates San Diego, Inc.; August 23, 2005. "City of Carlsbad Engineering Standards"; City of Carisbad, California; June 2004. Drawing No. 397-2H "Grading and Drainage Plans for Poinsettia Lane at La Costa Greens", Sheets 6-11; Kimley Horn & Associates, Inc.; July 14, 2003. "Storm Water Management Plan (SWMP) for La Costa Greens Neighborhood 1.2 & 1.3"; Hunsaker & Associates San Diego, Inc.; January, 2006. "Master Detention Study for La Costa Greens"; Hunsaker & Associates San Diego, Inc.; August 2003. AH H:\REPORTS\2352\141\TMStudy02.doc W.O. 2352-141 1/24/2006 1:34 PM La Mision Village TM Drainage Study . CHAPTER 2 METHODOLOGY & MODEL DEVELOPMENT AH H;\REPORTS\2352M41\TMStudy02.doc W.O. 2352-141 1/11/2006 10:08 PM SanDiego County Hydrology Manual Section: 2 Date: June 2003 Page: " 3 of 4 2.3 SELECTION OF HYDROLOGIC METHOD AND DESIGN CRITERIA Design Frequency - The flood frequency for determining the design stonn discharge is 50 years for drainage that is upstream of any major roadway and 100 years frequency for • all design storms at a major roadway, crossing the major roadway and thereafter. The 50-year storm flows shall be contarQed within the pipe and not encroach into the travel lane. For the 1 OO-year storm this includes allowing one lane ofa four-lane road (four or more lanes) to be used for conveyance without encroaching onto .private property outside the dedicated street right-of-way. Natural channels that remain natural within private property are excluded from the right-of-way guideline. Design Method - The choice of method to determine flows (discharge) shaU be based on the size of the watershed area. For an area 0 to approximately 1 square mile the Rational Method or the Modified Rational Method shall be used. For watershed areas larger than 1 square mile the NRCS hydrologic method shall be used. .Please check with the governing agency for any variations to these guidelines. 2-3 o CO i j_U5 ; T-o • o ; o 00 cb Oranae County of San Diego Hydrology Manual Rainfall Isopluvials 100 Year Rainfall Event - 6 Hours DPW GIS SanGIS Wc Have San Oicgtj Oivcrcd! N THIS MAP IS PROVIDED WfTHOUT WARRANTY OF ANY KIND. EfWER EXPRESS OR IMPLIED, INCLUDING. BUT NOT UMITED TO. THE IMPUED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Copyngh( SanGIS, All Rights Reservad. This products may conlain information from the SANOAG Regional Infonnation System which cannot be reproduced without the written pemiission of SANOAG. This product may contain information which has been reproduced with permission granted by Thomas Brothers Maps. 3 Miles o— CO i . ..a_ ; . rs i o O I o CO a ca 33°30^ Orange County 32°30' Riverside Coo-nty o CO OJ L s- 32'30' o o O CO CO County of San Diego Hydrology Manual Rainfall Isopluvials 100 Year Rainfall Event - 24 Hours Isopluvial (inches) DPW ^ SMGIS Otpafftmsm of Pafcjfc VKsow We Ha.vc San Dic^o Osvcrcd! N THIS MAP IS PROVIDED WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED. INCLUDING, BUT NOT UMITED TO. THE IMPLIED WARRANTIES OF MERCHANTABIUrr AND FITNESS FOR A PARTICULAR PURPOSE. Copyright SanGIS. All Rights Reserved. This products may contain inforniatien from the SANDAG Regional Information System which cannot tw reproduced without the written pennission of SANDAG. This product may contain information which has been reproduced with permission granted by Thomas Brotfiers Maps. 3 Miles San Diego County Hydrology Manual Date: June 2003 Section: Page: 6 of 2o Table 3-1 RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use Runoff Coefficient "C" Soil Type . NRCS Elements County Elements % IMPER. A B C D Undisturbed Natural Terrain (Natural) Permanent Open Space 0* 0.20 0.25 0.30 0.35 Low Density Residential (LDR) Residential, 1.0 DU/A or less 10 0.27 0.32 0.36 0.41 Low Density Residential (LDR) Residential, 2.0 DU/A or less 20 0.34 0.38 0.42 0.46 Low Density Residential (LDR) Residential, 2.9 DU/A or less 25 0.38 0.41 0.45 0.49 Medium Density Residential (MDR) Residential, 4.3 DU/A or less 30 0.41 0.45 0.48 0.52 Medium Density Residential (MDR) Residential, 7.3 DU/A or less 40 0.48 0.51 0.54 0.57 Medium Density Residential (MDR) Residential, 10.9 DU/A or less 45 0.52 0.54 0.57 0.60 Medium Density Residential (MDR) Residential, 14.5 DU/A or less 50 0.55 0.58 0.60 0.63 High Density Resi • al (HDR) Residential, 24.0 DU/A or less 65 0.66 0.67 0.69 0.71 High Density Residential (HDR) Residential, 43.0 DU/A or less 80 0.76 0.77 0.78 0.79 Commercial/Industrial (N. Com) Neighborhood Commercial 80 0.76 0.77 0.78 0.79 Commercial/Industrial (G. Com) General Commercial 85 0.80 0.80 0.81 0.82 Commercial/Industrial (O.P. Com) Office Professional/Commercial 90 0.83 0.84 0.84 0.85 Commercial/Industrial (Limited I.) Limited Industrial 90 0.83 0.84 0.84 0.85 Commercial/Industrial (General I.) General Industrial 95 0.87 0.87 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 San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 12 of 26 Note that the Initial Time of Concentration should be reflective of the general land-use at the upstream end ofa drainage basin. A single lot with an area of two or less acres does not have a significant effect where the drainage basin area is 20 to 600 acres. Table 3-2 provides limits of the length (Maximum Length (LM)) of sheet flow to be used in hydrology studies. Initial Tj 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. Table 3-2 MAXIMUM OVERLAND FLOW LENGTH (LM) Element* DU/ Acre .5% 1% 2% 3% 5% 10% Element* DU/ Acre LM Ti LM Ti LM Ti LM Ti LM Ti LM 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 5.7 100 4.5 MDR 14.5 50 8.2 65 7.4 80 6.5 90 6.0 100 5.4 100 4.3 HDR 24 50 6.7 65 6.1 75 5.1 90 4.9 95 4.3 100 3.5 HDR 43 50 5.3 65 4.7 75 4.0 85 3.8 95 3.4 100 2.7 N. Com 50 5.3 60 4.5 75 4.0 85 3.8 95 3.4 100 2.7 G.Com , 50 4.7 60 4.1 75 3.6 85 3.4 90 2.9 100 2.4 O.P./Com 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2 Limited I. 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2 General I. 50 3.7 60 3.2 70 2.7 80 2.6 90 2.3 100 1.9 *See Table 3-1 for more detailed description 3-12 100 LU UJ u. UJ o z ? w Q m 8 cc m I EXAMPLE Given: Watercourse Distance (D) = 70 Feet Slope (s) =1.3% Runoff Coefficient (C) = 0.41 Overland Flow Time (T) = 9.5 Minutes SOURCE: Airport Drainage, Federal Aviation Administration, 1965 1.8 (1.1-C) VD" FIGURE Rationaf Formula - Overland Time of Flow Nomograph AE Feet .5000 .4000 ,3000 • 2000 -1000 900 SQO Tc = Tc L AE EQUATION ^11.9Lfy.385 Tir of concentration (hours) WE'.idrcounse Distance (mites) Change in etevaUon along effectfve slope line (See Figure 3-5)(feet) To Hours • SOO .400 .300 "200 • IOO -120 100 90 80 U,70 N. \ \ L \ Miles Feet \ \ 1 — 50 40 — 30 .20 10 0.5 • 4000 3000 -2000 • 1800 16O0 • 1400 . 1200 IOOO 900 800 — 700 — 600 -500 .400 -300 • 200 AE SOURCE: California Division of Highways (1941) and Kirpicli (1940) MtnittBS 240 •180 60 50 — 40 — 30 -20 •18 • 16 •14 '12 •10 —9 8 7 1—6 Tc Nomograph for Determination of Time of Concentration (Tc) or Travel Time (Tt) for Natural Watersheds FIGURE 1^ —1.5'- -n = .01 £ ->l 5 6 7 8 9 10 Discharge (C.F.S.) EXAMPLE: Given: Q » 10 S - 2.5% Chart gives: Depth = 0.4, Velocity = 4.4 f.p.s. SOURCE: San Diego County Department of Special District Services Oesign Manual 30 • 40 50 FIGURE Gutter and Roadway Discharge - Velocity Chart UJ 0. O —I w c-0.3 .0,2 -0.15 0.10 0.09 -0.08 -0.07 0.06 0.05 '- 0.04 . 0,03 0.02 0,01 0,009 0.008 0,007 lr 0,006 0,005 EQUATION: V = 1.49 R^'s s"2 n >0,2 .0,3 .0.4 r 1.0,5 0.6 :o 0.8 {•0,9 1,0 a: a 0,004^^^1^ X r 0,003 0.002 0,001 0,0009 0,0008 0.0007 0,0006 0,0005 - 0,0004 '. 0.0003 - 5 - 6 7 r 8 9 '•- 10 L 20 SOURCE: USDOT, FHWA, HDS-3 (1961) .50 t40 30 -20 V T3 C O O <D tfl ffi a. .... ffi .* r5 10 -2 GENERAL SOLUTION -1,0 i.0,9 •0.8 • 0,7 •0,6 *-0,5 ^0,01 .0,02 •0,03 c ffi o ffi o w w , z I o o . cc r0.07 Lo,08 0,09 -0.10 -0,04 0,05 0.06 -0.3 •0,4 FIGURE Manning's Equation Nomograph 3 4 5 6 Hours Direptlons for Applicafion: (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 Manuai). (2) Adjust 6 hr precipitation (if necessary) so that it is within the range of 45% to 65% of the 24 hr prec*' 'ot applicaple to Desert). (3) Plot 6 hr precipitation on the right side ofthe 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. .year 24 'P. in. Applicafion Fonn: (a) Selected frequency (b) P6= in..P24 = (0) Adjusted Pg^^) = (d) tjj = min. (e) l= in.mr. Note: This chart replaces the intensity-Duration-Frequency curves used since 1965. PS 1 1.5 2 2.5 3-3.5 4 4.5 5 I 5.5 6 Duration 1 1 ( 1 1 1 1 1 1 1 t s 2.63 3.95 6.27 6.59 7.90 9.22 10.54 11.86 13.17 14.49 1S,81 7 2.12 ai8 4.24 5.30 6.36 7.42 8.48 9.64 10.60 _„ 11.66 „. 12.72 10 i.sa 2.53 3.37 4.21 S.OS 5.90 6.74 7,58 10.60 _„ 11.66 „. 10.11 15 1.30 1.9S 2.S9 3.24 8.89 4,54 5.19 5,84 6.49 7.13 7,78 20 1.08 1.62 2.15 2,69 3.23 3.77 4.31 4.85 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 4.98" iO 0.83 1.24 1.86 2.07 249 2.90 3.32 3.73 4.15 4.55 5.60 4.98" 40 0.69 1.03 1.38 1,78 2-07 2.41 2.76 3.10 3.45 3,79 4.13 $0 0.60 0.90 1.18 1.49 1.7S 2.09 2.39 2.69 2.98 3.26 isis 60 0.63 0.80 1.06 1.33 1.S9 1.86 2.12 T.63"" 2.39 2.65 2.92 3,18 90 a41 0.61 0.82 1.02 1,23 1.43 2.12 T.63"" 1.84 2.04 2.25 2,45 120 0.34 0J51 asd 0.8$ 1.02 1.19 1.36 1.53 1.70 1.87 2.04 ISO 0.29 0.44 0.59 073 0.88 1.03 I.ia 1.32 1.47 1.62 1.76 180 0.26 0.39 0.52 0.6S 078 0.91 1.04 1.18 1.31 1.44 1.57 240 a43 0.54 0.65 0.76 0.87 0.98 1.08 1.19 1.30 3001 0.19 [0.28 0.38 0.47 0.56 0.66 0.75 0.85 0.94 1-03 1,13 3601 0.17 10.25 0.33 0.42 0.50 0.58 0.67 0.75 0.84 0.92 i.OO FIGURE Intensity-Duration Design Chart - Template La Costa Greens Neighborhoods 1.1-1.3 TIVI Drainage Study Modified Rational Method Hvdrologic Analvsis Computer Software Package - AES-2003 Design Storm - 100-year return interval Land Use - Commercial & Multi-family residential; Soil Type - Hydrologic soil group D was assumed for all areas. Group D soils have very slow infiltration rates when thoroughly wetted. Consisting chiefly of clay soils with a high swelling potential, soils with a high permanent water table, soils with clay pan or clay layer at or near the surface, and shallow soils over nearly impervious materials. Group D soils have a very slow rate of water transmission. Runoff Coefficient - In accordance with the County of San Diego standards, runoff coefficients were based on land use. Rainfall Intensity - Initial time of concentration values were determined using the County of San Diego standards. The rainfall intensity-duration-frequency curve for the San Diego County was used to determine rainfall intensities. Method of Analysis - The Rational Method is the most widely used hydrologic model for estimating peak runoff rates. Applied to small urban and semi-urban areas with drainage areas less than 0.5 square miles, the Rational Method relates storm rainfall intensity, a runoff coefficient, and drainage area to peak runoff rate. This relationship is expressed by the equation: Q = CIA, where: Q = The peak runoff rate in cubic feet per second at the point of analysis. C = A runoff coefficient representing the area - averaged ratio of runoff to rainfall intensity. I = The time-averaged rainfall intensity in inches per hour corresponding to the time of concentration. A = The drainage basin area in acres. To perform a node-link study, the total watershed area is divided into subareas which discharge at designated nodes. The procedure for the subarea summation model is as follows: (1) Subdivide the watershed into an initial subarea (generally 1 lot) and subsequent subareas, which are generally less than 10 acres in size. Assign upstream and downstream node numbers to each subarea. (2) Estimate an initial Tc by using the appropriate nomograph or overland flow velocity estimation. AH H:\REPORTS\2352\141\TMStudy02.rioc W,0. 2352-141 1/11/2006 10:08 PM La Costa Greens Neighborhoods 1.1-1.3 TiVI Drainage Study (3) Using the initial Tc, determine the corresponding values of I. Then Q = C I A. (4) Using Q, estimate the travel time between this node and the next by Manning's equation as applied to the particular channel or conduit linking the two nodes. Then, repeat the calculation for Q based on the revised intensity (which is a function of the revised time of concentration) The nodes are joined together by links, which may be street gutter flows, drainage swales, drainage ditches, pipe flow, or various channel flows. The AES-99 computer subarea menu is as follows: SUBAREA HYDROLOGIC PROCESS 1. Confluence analysis at node. 2. Initial subarea analysis (including time of concentration calculation). 3. Pipeflow travel time (computer estimated). 4. Pipeflow travel time (user specified). 5. Trapezoidal channel travel time. 6. Street flow analysis through subarea. 7. User - specified information at node. 8. Addition of subarea runoff to main line. 9. V-gutter flow through area. 10. Copy main stream data to memory bank 11. Confluence main stream data with a memory bank 12. Clear a memory bank At the confluence point of two or more basins, the following procedure is used to combine peak flow rates to account for differences in the basin's times of concentration. This adjustment is based on the assumption that each basin's hydrographs are triangular in shape. (1). If the collection streams have the same times of concentration, then the Q values are directly summed, Qp = Qa + Qb; Tp = Ta = Tb AH H:\REPORTa2352M41\TMStudy02.doc W.O. 2352-141 1/11/2000 10:08 PM La Costa Greens Neighborhoods 1.1-1.3 TM Drainage Study (2). If the collection streams have different times of concentration, the smaller of the tributary Q values may be adjusted as follows: (i) . The most frequent case is where the collection stream with the longer time of concentration has the larger Q. The smaller Q value is adjusted by the ratio of rainfall intensities. Qp = Qa + Qb (la/lb); Tp = Ta (ii) . In some cases, the collection stream with the shorter time of concentration has the larger Q. Then the smaller Q is adjusted by a ratio of the T values. Qp = Qb + Qa (Tb/Ta); Tp = Tb AH H:\REPORTS\2352\141\TMStully02.doc W.O. 2352-141 1/11/2006 10:08 PM La IViision Viliage TM Drainage Study CHAPTER 3 100-YEAR HYDROLOGIC MODEL FOR DEVELOPED CONDITIONS AH H:\REPORTSC352M41\TMStudy02.doc W.O. 2352-141 1/11/2006 10:08 PM ****************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-2003 Advanced Engineering Software (aes) Ver. l.SA Release Date: 01/01/2003 License ID 1239 Analysis prepared by: HUNSAKER & ASSOCIATES - SAN DIEGO 10179 Huennekens Street San Diego, Ca. 92121 (858) 558-4500 *****ii********i.ir*ieii******it DESCRIPTION OF STUDY *************************** * LA COSTA GREENS NEIGHBORHOOD 1.3 - RV STORAGE SITE * * lOO-YEAR DEVELOPED CONDITION HYDROLOGY ANALYSIS FOR TENTATIVE MAP * * H&A W.O. #2352-141 JAN, 2006 * *•****************-*-*********•**********************•*************•*********** FILE NAME: H:\AES2003\2352\141\DEV100.DAT TIME/DATE OF STUDY: 11:55 01/24/2006 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: 2003 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100.00 6-HOUR DURATION PRECIPITATION (INCHES) = 2.800 SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90 SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD NOTE: USE MODIFIED RATIONAL METHOD PROCEDURES FOR CONFLUENCE ANALYSIS •USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) 1 15.0 9.5 0.020/0.020/ 0.50 1.50 0.0313 0.125 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 1. Relative Flow-Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top-of-Curb) 2. (Depth)*(Velocity) Constraint = 5.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* -^ + I Per the 2003 San Diego County Hydrology Manual: used C=0.35 for natural | I subareas, C=0.85 for subareas that are 95% impervious (streets and the | I RV Storage), and C=0.71 for the futur* multi-family development. | + + -i. + I WEIGHTED C USED - C = 0.77. SEE ATTACHED CALCULATIONS. | I I I I + • -^ * Jr***************************************************************-*****-****** FLOW PROCESS FROM NODE 1.00 TO NODE 2.00 IS CODE = 21 >»>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT = .7700 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 65.00 UPSTREAM ELEVATION(FEET) = 322.50 DOWNSTREAM ELEVATION(FEET) = 321.85 ELEVATION DIFFERENCE(FEET) = 0.65 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.789 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 65.00 (Reference: Table 3-lB of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.377 NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINtJTE. SUBAREA RUNOFF (CFS) = 0,80 TOTAL AREA (ACRES) = 0,14 TOTAL RUNOFF (CFS) = 0,80 ******************************************************************************** FLOW PROCESS FROM NODE 2.00 TO NODE 4.00 IS CODE = 62 »>»COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<< »»> (STREET TABLE SECTION # 1 USED) <<«< ^ = == = = = = = = = = = =s =:=:=!=; =s = = = = = = = = = = = = = = = = =r = = = == =1 = = = = = = = = = = = = = = = = = = = = = = = = = = = 5= = = = = UPSTREAM ELEVATION (FEET) = 321.85 DOWNSTREAM ELEVATION (FEET) = 314.50 STREET LENGTH(PEET) = 697.80 CURB HEIGHT(INCHES) = 6.0 STREET HALFWIDTH(FEET) = 15.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK (FEET) = 9.50 INSIDE STREET CROSSFALL(DECIMAL) = 0.020 OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020 SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1 Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 4,29 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW: STREET FLOW DEPTH(FEET) =0,37 HALFSTREET FLOOD WIDTH(FEET) = 12,39 AVERAGE FLOW VELOCITY(FEET/SEC,) = 2,59 PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC,) = 0,97 STREET FLOW TRAVEL TIME(MIN.) = 4,48 Tc(MIN,) = 9,27 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4,954 *USER SPECIFIED (StJBAREA) : USER-SPECIFIED RUNOFF COEFFICIENT = ,7700 S,C,S, CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT = 0,770 SUBAREA AREA (ACRES) = 1,79 SUBAREA RUNOFF (CFS) = 6.83 TOTAL AREA (ACRES) = 1,93 PEAK FLOW RATE (CFS) = 7,36 END OF SUBAREA STREET FLOW HYDRAULICS: DEPTH(FEET) = 0.43 HALFSTREET FLOOD WIDTH(FEET) = 15,00 FLOW VELOCITY(FEET/SEC.) = 2.91 DEPTH*VELOCITY(FT*FT/SEC.) = 1.24 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 4.00 = 762.80 FEET, *************************************-*•************************************** FLOW PROCESS FROM NODE 4,00 TO NODE 4,00 IS CODE = 1 >>»>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<« TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN,) = 9,27 RAINFALL INTENSITY(INCH/HR) =4.95 TOTAL STREAM AREACACRES) = 1.93 PEAK FLOW RATE(CFS) AT CONFLUENCE = 7.36 ***************************************************************************** FLOW PROCESS FROM NODE 3.00 TO NODE 9.00 IS CODE = 21 >»>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««< S = = = = = = = = = = = = = = = = = = = = = = = =: = s: = = = = = = = = = = = = = = = = = = = = = = = =; = = = = = = = = = = =: = = = = = = = = = = = = = = *USER SPECIFIED(StraAREA): USER-SPECIFIED RUNOFF COEFFICIENT = .8700 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00 UPSTREAM ELEVATION(FEET) = 320.50 DOWNSTREAM ELEVATION(FEET) = 319.90 ELEVATION DIFFERENCE(FEET) = 0.60 SUBAREA OVERLAND TIME OF FLOW (MIN.) = 3.207 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.377 NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE, SUBAREA RUNOFF (CFS) = 0.32 TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) = 0.32 **************************************************************************** FLOW PROCESS FROM NODE 9.00 TO NODE 10.00 IS CODE = 51 »»>COMPUTE TRAPEZOIDAL CHANNEL FLOW«<<< »»>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT) <<<<< ELEVATION DATA: UPSTREAM (FEET) = 319,90 DOWNSTREAM (FEET) = 316,50 CHANNEL LENGTH THRU SUBAREA(FEET) = 148,00 CHANNEL SLOPE = 0.0230 CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 50.000 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.40 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.377 NOTE: RAINFALL INTENSITY IS BASED ON TC = 5-MINUTE. *USER SPECIFIED (StJBAREA) : USER-SPECIFIED RUNOFF COEFFICIENT = ,8700 S.C.S. CURVE NUMBER (AMC II) = 0 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.70 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.39 AVERAGE FLOW DEPTH(FEET) = 0.12 TRAVEL TIME(MIN.) = 1.03 Tc(MIN.) = 4.24 SUBAREA AREA (ACRES) = 0,43 SUBAREA RUNOFF (CFS) = 2,76 AREA-AVERAGE RUNOFF COEFFICIENT = 0,870 TOTAL AREA(ACRES) = 0,48 PEAK FLOW RATE(CFS) = 3,08 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0,15 FLOW VELOCITY(FEET/SEC,) = 2,75 LONGEST FLOWPATH FROM NODE 3,00 TO NODE 10,00 = 208,00 FEET, **************************************************************************** FLOW PROCESS FROM NODE 10,00 TO NODE 4.00 IS CODE = 51 »»>COMPUTE TRAPEZOIDAL CHANNEL FLOW««< >>»>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM (FEET) = 316.50 DOWNSTREAM (FEET) = 314.50 CHANNEL LENGTH THRU SUBAREA (FEET) = 100.00 CHANNEL SLOPE = 0.0200 CHANNEL BASE (FEET) = 10.00 "Z" FACTOR = 2.000 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH (FEET) = 0.50 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.377 NOTE: RAINFALL INTENSITY IS BASED ON Tc = S-MINOTE. *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT = .8700 S.C.S. CURVE NUMBER (AMC II) = 0 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 3.08 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.96 AVERAGE FLOW DEPTH(FEET) = 0.10 TRAVEL TIME(MIN.) = 0.56 Tc{MIN.) =4.80 SUBJVREA AREA (ACRES) = 0.00 SUBAREA RUNOFF (CFS) = 0,00 AREA-AVERAGE RUNOFF COEFFICIENT = 0,870 TOTAL AREA(ACRES) = 0,48 PEAK FLOW RATE (CFS) = 3.08 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0,10 FLOW VELOCITY(FEET/SEC.) = 2.96 LONGEST FLOWPATH FROM NODE 3.00 TO NODE 4,00 = 308.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 IS CODE = 1 >»>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< >>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<« TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE: TIME OF CONCENTRATION(MIN.) = 4.80 RAINFALL INTENSITY(INCH/HR) = 7.38 TOTAL STREAM AREA (ACRES) = 0.4 8 PEAK FLOW RATE(CFS) AT CONFLUENCE = 3.08 ** CONFLUENCE DATA ** STREAM RUNOFF Tc INTENSITY AREA NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE) 1 7.36 9.27 4.954 1.93 2 3.08 4.80 7.377 0.48 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS. , ** PEAK FLOW RATE TABLE ** STREAM RUNOFF Tc INTENSITY NUMBER (CFS) (MIN.) (INCH/HOUR) 1 6.89 4.80 7.377 2 9.43 9.27 4.954 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE (CFS) = 9.43 Tc(MIN.) = 9.27 TOTAL AREA (ACRES) = 2.41 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 4.00 = 762.80 FEET. **************************************************************************** FLOW PROCESS FROM NODE 4.00 TO NODE 5.00 IS CODE = 51 >>>»COMPUTE TRAPEZOIDAL CHANNEL FLOW«<<< »>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT) <<<« ELEVATION DATA: UPSTREAM (FEET) = 314.50 DOWNSTREAM (FEET) = 309.00 CHANNEL LENGTH THRU StJBAREA (FEET) = 330.50 CHANNEL SLOPE = 0,0166 CHANNEL BASE(FEET) = 10.00 "Z" FACTOR = 2.000 MANNING'S FACTOR = 0,015 MAXIMUM DEPTH (FEET) = 0,50 100 YEAR RAINFALL INTENSITY (INCH/HOUR) = 4,604 *USER SPECIFIED (SUBAREA) : USER-SPECIFIED RUNOFF COEFFICIENT = ,7100 S.CS. CURVE NUMBER (AMC II) = 0 TRAVEL TIME COMPUTED USING ESTIMATED FLOW (CFS) = 12.90 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY (FEET/SEC.) = 4.94 AVERAGE FLOW DEPTH(FEET) = 0.25 TRAVEL TIME(MIN.) = 1.12 Tc(MIN.) = 10.39 SUBAREA AREA (ACRES) = 2.12 SUBAREA RUNOFF (CFS) = 6.93 AREA-AVERAGE RUNOFF COEFFICIENT = 0.753 TOTAL AREA (ACRES) = 4,53 PEAK FLOW RATE (CFS) = 15,69 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH (FEET) = 0,28 FLOW VELOCITY (FEET/SEC,) = 5.32 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 5.00 = 1093.30 FEET. **************************************************************************** FLOW PROCESS FROM NODE 5.00 TO NODE 14,00 IS CODE = 31 >»»COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<«<< ELEVATION DATA: UPSTREAM(FEET) = 305.00 DOWNSTREAM(FEET) = 270.00 FLOW LENGTH(FEET) = 120.00 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 6.7 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 26.42 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 15.69 PIPE TRAVEL TIME(MIN.) = 0.08 Tc(MIN.) = 10.46 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 14.00 = 1213.30 FEET. **************************************************************************** FLOW PROCESS FROM NODE 14.00 TO NODE 14.00 IS CODE = 1 >»»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN.) = 10.46 RAINFALL INTENSITY (INCH/HR) = 4.58 TOTAL STREAM AREA (ACRES) = 4.53 PEAK FLOW RATE(CFS) AT CONFLUENCE = 15.69 WEIGHTED C USED - C = 0.77, SEE ATTACHED CALCULATIONS. **************************************************************************** FLOW PROCESS PROM NODE 7.00 TO NODE 8,00 IS CODE = 21 >>»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<« *USER SPECIFIED (SUBjyiEA) : USER-SPECIFIED RUNOFF COEFFICIENT = .7700 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH (FEET) = 70.00 UPSTREJW1 ELEVATION (FEET) = 314.50 DOWNSTREAM ELEVATION (FEET) = 313.30 ELEVATION DIFFERENCE(FEET) = 1.20 SUBAREA OVERLAND TIME OF FLOW (MIN.) = 4.153 100 YEAR RAINFALL INTENSITY (INCH/HOUR) = 7.377 NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE. SUBAREA RUNOFF (CFS) = 0.4 0 TOTAL AREA(ACRES) = 0.07 TOTAL RUNOFF(CFS) = 0.40 **************************************************************************** FLOW PROCESS FROM NODE 8.00 TO NODE 11.00 IS CODE = 62 >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA«<<< »>>> (STREET TJVBLE SECTION # 1 USED) <<<<< UPSTREjyi ELEVATION (FEET) = 313,30 DOWNSTREAM ELEVATION (FEET) = 302,50 STREET LENGTH(FEET) = 416.80 CURB HEIGHT(INCHES) = 6.0 STREET HALFWIDTH(PEET) = 15,00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 9.50 INSIDE STREET CROSSFALL (DECIMAL) = 0.020 OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020 SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1 Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 2.19 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW: STREET FLOW DEPTH(FEET) = 0,28 HALFSTREET FLOOD WIDTH(FEET) = 7.59 AVERAGE FLOW VELOCITY(FEET/SEC.) = 3.15 PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.88 STREET FLOW TRAVEL TIME(MIN.) = 2.21 Tc(MIN.) = 6.36 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.317 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT = .7700 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT = 0.770 SUBAREA AREA (ACRES) = 0.73 SUBAREA RUNOFF (CFS) = 3.55 TOTAL AREA (ACRES) = 0.80 PEAK FLOW RATE (CFS) = 3,89 END OF SUBAREA STREET FLOW HYDRAULICS: DEPTH(FEET) =0,32 HALFSTREET FLOOD WIDTH(FEET) = 9,86 FLOW VELOCITY(FEET/SEC.) = 3.57 DEPTH*VELOCITY(FT*PT/SEC.) = 1.15 LONGEST FLOWPATH FROM NODE 7.00 TO NODE 11.00 = 486.80 FEET. **************************************************************************** FLOW PROCESS FROM NODE 11.00 TO NODE 14.00 IS CODE = 31 >>>»COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< »>»USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 295.00 DOWNSTREAM(FEET) = 270.00 FLOW LENGTH(FEET) = 224.50 MANNING'S N = 0.013 ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000 DEPTH OF FLOW IN 18.0 INCH PIPE IS 4.2 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 12.59 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 3.89 PIPE TRAVEL TIME(MIN.) = 0.30 Tc{MIN.) = 6.66 LONGEST FLOWPATH FROM NODE 7.00 TO NODE 14.00 = 711.30 FEET. **************************************************************************** FLOW PROCESS PROM NODE 14.00 TO NODE 14.00 IS CODE = 1 >>»>DESIGNATE INDEPENDENT STREAM POR CONFLUENCE<<<« >»>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<«< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE: TIME OF CONCENTRATION(MIN,) = 6,66 RAINFALL INTENSITY(INCH/HR) =6.13 TOTAL STREAM AREA (ACRES) = 0,80 PEAK FLOW RATE(CFS) AT CONFLUENCE = 3,89 ** CONFLUENCE DATA ** STREAM RUNOFF To INTENSITY KREA NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE) 1 15,69 10,46 4,582 4,53 2 3.89 6.66 6.134 0.80 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS. ** PEAK FLOW RATE TABLE ** STREAM RUNOFF Tc INTENSITY NtJMBER (CFS) (MIN.) (INCH/HOUR) 1 15.61 6.66 6.134 2 18,60 10,46 4,582 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 18.60 Tc(MIN.) = 10.46 TOTAL AREA (ACRES) = 5.33 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 14.00 = 1213.30 FEET. **************************************************************************** FLOW PROCESS FROM NODE 14.00 TO NODE 200.00 IS CODE = 52 >>»>COMPUTE NATURAL VALLEY CHANNEL FLOW<«<< >>»>TRAVELTIME THRU StJBAREA<<<<< ELEVATION DATA: UPSTREAM(FEET) = 257.00 DOWNSTREAM(FEET) = 176.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 1529.50 CHANNEL SLOPE = 0.0530 CHANNEL FLOW THRU SUBAREA(CFS) = 18.60 FLOW VELOCITY (FEET/SEC) = 6.76 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 3.77 Tc(MIN.) = 14.23 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 200.00 = 2 742.80 FEET. **************************************************************************** FLOW PROCESS PROM NODE 14.00 TO NODE 200.00 IS CODE = 81 »>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 100 YEAR RAINFALL INTENSITY (INCH/HOUR) = 3.757 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT = .3500 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT = 0.4197 SUBAREA AREA (ACRES) = 25.65 SUBAREA RUNOFF (CFS) = 33.73 TOTAL AREA(ACRES) = 30.98 TOTAL RUNOFF(CFS) = 48.85 TC(MIN.) = 14.23 I Node 200 is the nomenclature used in the "Mass-Graded Hydrology Study ( I for La Costa Greens Neighborhoods 1.1-1,3 & El Camino Real Widening" j I at the headwall off approximate Sta. 23+00 along Poinsettia Lane. | + + **************************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 200.00 IS CODE = 1 >>>»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN.) =14.23 RAINFALL INTENSITY(INCH/HR) = 3.76 TOTAL STREAM AREA(ACRES) = 30.98 PEAK FLOW RATE(CFS) AT CONFLUENCE = 4 8.85 **************************************************************************** FLOW PROCESS FROM NODE 205.00 TO NODE 206.00 IS CODE = 21 »>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<«<< *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT = ,3500 S,C,S. CtJRVE NUMBER (AMC II) = 0 INITIAL StJBAREA FLOW-LENGTH (FEET) = 1000.00 UPSTREAM ELEVATION (FEET) = 328.00 DOWNSTREAM ELEVATION(FEET) = 202.00 ELEVATION DIFFERENCE(FEET) = 126.00 SUBAREA OVERLAND TIME OF FLOW (MIN.) = 6,267 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMtJM OVERLAND FLOW LENGTH = 100,00 (Reference: Table 3-IB of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6,377 SUBAREA RUNOFF(CFS) = 16.18 TOTAL AREA(ACRES) = 7.25 TOTAL RUNOFF(CPS) = 16.18 **************************************************************************** FLOW PROCESS FROM NODE 206.00 TO NODE 200.00 IS CODE = 52 »>»COMPUTE NATURAL VALLEY CHANNEL FLOW<«« >>>»TRAVELTIME THRU SUBAREA<«<< ELEVATION DATA: UPSTREAM(PEET) = 202.00 DOWNSTREAM(FEET) = 176,00 CHANNEL LENGTH THRU SUBAREA (FEET) = 3 99,00 CHANNEL SLOPE = 0 , 0SS2 CHANNEL FLOW THRU SUBAREA (CFS) = 16,18 FLOW VELOCITY (FEET/SEC) = 7,23 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME (MIN. ) = 0.92 Tc (MIN. ) = 7.19 LONGEST FLOWPATH FROM NODE 205.00 TO NODE 200.00 = 1399.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 206.00 TO NODE 200.00 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««< 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.838 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT = .3500 S.C.S. CURVE NtJMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT = 0.3500 SUBAREA AREA (ACRES) = 4.54 SUBAREA RUNOFF (CFS) = 9.28 TOTAL AREA(ACRES) = 11.79 TOTAL RUNOFF(CFS) = 24.09 TC(MIN.) = 7.19 The data from Node 205 to Node 206 and from Node 206 to Node 200 has been obtained from the "Mass-Graded Hydrology Study for La Costa Greens I Neighborhoods 1.1-1.3 & El Camino Real Widening". See Appendix 5.1. **************************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 200.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONPLUENCE<<<<< >>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< TOTAL NUMBER OP STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE: TIME OF CONCENTRATION(MIN.) = 7.19 RAINFALL INTENSITY (INCH/HR) = 5.84 TOTAL STREAM AREA (ACRES) = 11.79 PEAK FLOW RATE(CFS) AT CONFLUENCE = 24.09 ** CONFLUENCE DATA ** STREAM RUNOFF Tc INTENSITY AREA NUMBER (CPS) (MIN.) (INCH/HOUR) (ACRE) 1 48.85 14.23 3.757 30.98 2 24.09 7.19 5.838 11,79 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS, ** PEAK PLOW RATE TABLE ** STREAM RUNOFF Tc INTENSITY NUMBER (CPS) (MIN,) (INCH/HOUR) 1 55,53 7,19 5.838 2 64.36 14.23 3.757 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 64.36 Tc(MIN.) = 14,23 TOTAL AREA(ACRES) = 42,77 LONGEST PLOWPATH FROM NODE 1.00 TO NODE 200.00 = 2742.80 FEET. END OF STUDY SUMMARY: TOTAL AREA (ACRES) PEAK FLOW RATE (CFS) = 42 64 77 TC(MIN.) 36 = 14.23 END OP RATIONAL METHOD ANALYSIS Rational Method Results at: Subarea 1 0.87 0.71 Development Area (ac) 0.78 1.15 C = Sum of Areas 0.8 1.2 0.0 0,0 0,0 0,0 0,0 0,0 0,0 = 1.9 ac. 38.4% impervious % Impervious 95 0 = 1.9 ac. 38.4% impervious Weighted Average C = 0,77 Rational Method Results at: Subarea 2 0.87 0.71 Development Area (ac) 0.30 0.50 C = Sum of Areas 0.3 0,5 0.0 0,0 0.0 0.0 0.0 0.0 0.0 = 0.8 ac. 35.6% impervious % impervious 95 0 = 0.8 ac. 35.6% impervious Weighted Average C = 0.77 La iVIision Viliage TM Drainage Study CHAPTER 4 HYDROLOGY EXHIBITS Exhibit 4.1 Developed Conditions Hydrology Map AH H:\REPORTS\2352\141\TMStudy02.iloc W.O. 2352-141 1/11/2008 10:08 PM La Mision Viilage TM Drainage Study CHAPTER 5 APPENDICES Appendix 5.2 Excerpts from Drawing No. 397-2H ''Grading and Drainage Plans for Poinsettia Lane at La Costa Greens'', Sheet 8 AH H:\REPORTSa352M41\TMStudy02.llo<: W.O. 2352-141 1/11/2006 10:08 PM 2m .^tSH-fitfioerSTi-* 226 "T-.rf H---t— 11+ rt-f J .2*'.^ad'. i li3Sp-D) I : ^LHSO.SS'. m -1--,..L„i_ -i..^4-l!SO=LZi,°"f£K.-4- j ; I ! i ; bffisff/4t eROUNQ. g y -t~r- i-t-- iRSlULEMi aSETTIALANE i»i(o:?x !0f00-?5,J;C/=5 i -2©0- spi.iylsj^..v.j'p.'.l.-[ ^ 'CH - j5D=jrn—r I 2,.fi5*,.,.L.,.L. .1 180.56": j I --!--! ™r-<-- -ii-f^a-ei)-^-i.-i.-+-4 - r 21 22 •••ir^ Kimley-Hofn iHL_J and Assodates, Inc, EnolrMarIng, Wanning ond Envlronmontal Consultants 517 Fourth Avenuo - Sulta 301 - Son Oiago, Co, - 92101 Tell I6I9I234-94I Foxi (619123<-9433 ru mum mm. it^it AND STREET IkmaVEHENTS SEE OWG. »3»T-21. CAUTIONI 1 LOCATIOH OF EXISTING UTILITIES ON TIESE PLANS ARE APPROXIMATE ANO SHALL BE VERIFIED BY CONTRACTOR PRIOR TO CONSTRUCTION. SrO/?)l/ DRA/N DATA m. XLTA OR BRG. RAOUS LENGTH REMARKS A=6-0r38-1434.00' ISO. 85' 24- RCP (1350-0) i= 10-54:26' 1434. 00' 211. 9T 24- RCP (1350-0) (3). A'S-ie-16-1434. 00' 131. IT 36- RCP (1350-0) (ii N75-00'09-£ 4$. 79' 36- RCP 11350-0) A-28-29'29-43.50' 21. 63' IB' RCP 11350-0) s N20-35'32-W 52.48' IS- RCP (1350-0) ' N65-35'3I•m 7. 45' 36' RCP (1350-D) . N20-30'31•W 31.33' 36- RCP (1350-D) ' i-30-I6'42' 90. 00' 46. 24' 36' RCP (1350-D)' II70-37'35'E 221. 05' 36- RCP (I3S0-D) A-2a-29'29-43. 50' 23. 08' 36- RCP (I350-O) . Nia'02'03'e 11.31' 18- RCP (1350-0) « to O' ENGINEER OF WORK TIMOTHY J. DEWITT R,C,E. 46579 DATE VALLgfclTOS WATEft DISTRICT (FOR oRtam ona) 7-l.-»> 5/26/0} KHA GRAPHC SCALE f= VSf EMKER OF HOnt BENCHMARK; DESCRIPTIONiSTAWMRD STREET SUmET UOmjDEHr LOCATION: Srt.2ae.e9 EC OH CEKTERUHE OF EL CmiHO REAL RECORD FROM:S>W DIEQO OOUHTY VERTICAL CONTROL RS-l800.2BB'e9 ELEVATION: 311.407 USJ. SjUBf s/eer 3. REVISED swim OIAIII AMD REVISION OESCRIPTION DATB WTIAI, OTHEF APreOVAL l/lj/t^/^ff "AS BUILT" m m,. wa SHEET CITY OF CARLSBAD ^W)^ 8 11 ENBWmiG DEPARTMENT C.°l emamMD OMMWE PIMS ran POINSETTIA LANE AT LA COSTA GREENS srK^l^3oa)•ro^hsaa> APPROVED! an ENGINgR RJtS.J".** riv^Jltt&h D/fTE PROJECT NO, CT99-03 DRAWING NO. 39r-2H VWD 02-001 La Mision Village TM Drainage Study CHAPTER 5 APPENDICES Appendix 5.1 Excerpts from "Mass-Graded Hydrology Study for La Costa Greens Neighborhoods 1.1-1.3 & El Camino Real Widening" AH H:\REPORTS«352M4i™Study02.doc W.O. 2352-141 1/11/2006 10:08 PM MASS-GRADED HYDROLOGY STUDY for LA COSTA GREENS NEIGHBORHOODS 1.1 -1.3 & EL CAMINO REAL WIDENING City of Carlsbad, California Prepared for: Real Estate Collateral Management Company c/o Morrow Development 1903 Wright Place Suite 180 Carlsbad, CA 92008 w.o. 2352-138 August 23, 2005 Hunsaker & Associates San Diego, Inc. Raymond L. Martin, R.C.E. Vice President AH:ah H:\REPORTS\2352\138 Greens 1.1 thru 1,3\3in SUBMITTAL\A03.doc W.0.23S2-138 1/11/2006 11:22 PM ************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-99 Advanced Engineering Software (aes) Ver. l.SA Release Date: 01/01/99 License ID 1239 Analysis prepared by: Hunsaker & Associates - San Diego, Inc. 10179 Huennekens Street San Diego, Ca. 92121 (858) 558-4500 ************************** DESCRIPTION OF STUDY ************************** * CAMINO REAL WIDENING AND LA COSTA GREENS NEIGHBORHOODS 1.1 THRU 1.3 * * lOO-YEAR MASS-GRADED CONDITION HYDROLOGY ANALYSIS * * W.0.# 2352-138 PREPARED BY: AH * ************************************************************************** FILE NAME: H:\AES99\2352\138\MG100.DAT TIME/DATE OF STUDY: 18: 3 8/18/2005 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: 1985 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100.00 6-HOUR DURATION PRECIPITATION (INCHES) = 2.800 SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE =0.90 SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED + + I BEGIN BASIN #1 - EL CAMINO REAL WIDENING, LA COSTA GREENS NEIGHBORHOODS | I 1.1 THROUGH 1.3, AND LA COSTA GREENS RV STORAGE AREA (NODE SERIES 100) j I I + + **************************************************************************** FLOW PROCESS FROM NODE 101.00 TO NODE 102.00 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): INDUSTRIAL DEVELOPMENT RUNOFF COEFFICIENT = .9500 INITIAL SUBAREA FLOW-LENGTH = 2 0 0.00 UPSTREAM ELEVATION = 316.00 DOWNSTREAM ELEVATION = 314.60 ELEVATION DIFFERENCE = 1.40 URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 4.300 TIME OF CONCENTRATION ASSUMED AS 6-MINUTES 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6,559 **************************************************************************** FLOW PROCESS FROM NODE 204.00 TO NODE 200.00 IS CODE = 52 >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA<<<<< UPSTREAM NODE ELEVATION = 2 85.00 DOWNSTREAM NODE ELEVATION = 176.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 1664.00 CHANNEL SLOPE = 0.0655 CHANNEL FLOW THRU SUBAREA(CFS) = 20.08 FLOW VELOCITY(FEET/SEC) = 7.68 (PER PLATE D-6.1) TRAVEL TIME(MIN.) = 3.61 TC(MIN.) = 18.22 **************************************************************************** FLOW PROCESS FROM NODE 204.00 TO NODE 200.00 IS CODE = 8 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.204 *USER SPECIFIED(SUBAREA): RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500 SUBAREA AREA(ACRES) = 25.65 SUBAREA RUNOFF(CFS) = 36.98 TOTAL AREA(ACRES) = 31.36 TOTAL RUNOFF(CFS) = 57.06 TC(MIN) = 18.22 **************************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 200.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< TOTAL NUMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE: TIME OF CONCENTRATION(MIN.) = 18.22 RAINFALL INTENSITY(INCH/HR) = 3.20 TOTAL STREAM AREA(ACRES) = 31.36 PEAK FLOW RATE(CFS) AT CONFLUENCE = 57.06 **************************************************************************** FLOW PROCESS FROM NODE 205.00 TO NODE 206.00 IS CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500 NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION (APPENDIX X-A) WITH 10-MINUTES ADDED = 13.54(MINUTES) INITIAL SUBAREA FLOW-LENGTH = 1000.00 UPSTREAM ELEVATION = 32 8.00 DOWNSTREAM ELEVATION = 202.00 ELEVATION DIFFERENCE = 126.00 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.880 SUBAREA RUNOFF(CFS) = 12.66 TOTAL AREA(ACRES) = 7.25 TOTAL RUNOFF(CFS) = 12.66 **************************************************************************** FLOW PROCESS FROM NODE 206.00 TO NODE 200.00 IS CODE = 52 >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA<<<<< UPSTREAM NODE ELEVATION = 2 02.0 0 DOWNSTREAM NODE ELEVATION = 176.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 3 99.00 CHANNEL SLOPE = 0.0652 CHANNEL FLOW THRU SUBAREA(CFS) = 12.66 FLOW VELOCITY(FEET/SEC) = 6.78 (PER PLATE D-6.1) TRAVEL TIME(MIN.) = 0.98 TC(MIN.) = 14.52 **************************************************************************** FLOW PROCESS FROM NODE 2 06.00 TO NODE 200.00 IS CODE = 8 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.709 *USER SPECIFIED(SUBAREA): RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500 SUBAREA AREA(ACRES) = 4.54 SUBAREA RUNOFF(CFS) = 7.58 TOTAL AREA(ACRES) = 11.79 TOTAL RUNOFF(CFS) = 20.24 TC(MIN) = 14.52 **************************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 200.00 IS CODE = 1 >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<< >>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< TOTAL NIMBER OF STREAMS = 2 CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE: TIME OF CONCENTRATION(MIN.) = 14.52 RAINFALL INTENSITY(INCH/HR) = 3.71 TOTAL STREAM AREA(ACRES) = 11.79 PEAK FLOW RATE(CFS) AT CONFLUENCE = 2 0.24 ** CONFLUENCE DATA ** STREAM RUNOFF Tc INTENSITY AREA NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE) 1 57.06 18.22 3.204 31.36 2 20.24 14.52 3.709 11.79 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS. ** PEAK FLOW RATE TABLE ** STREAM RUNOFF Tc INTENSITY NUMBER (CFS) (MIN.) (INCH/HOUR) 1 69.53 14.52 3.709 2 74.54 18.22 3.204 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 74.54 Tc(MIN.) = 18.22 TOTAL AREA(ACRES) = 43.15 END BASIN #2 - LA COSTA GREENS SOUTH LOT (NODE SERIES 200) END OF STUDY SUMMARY: PEAK FLOW RATE(CFS) = 74.54 Tc(MIN.) = 18.22 TOTAL AREA(ACRES) = 43.15 END OF RATIONAL METHOD ANALYSIS 1