Loading...
HomeMy WebLinkAboutMS 04-07; 952 PINE AVENUE CONDOMINIUMS; HYDROLOGY AND HYDRAULIC REPORT; 2006-07-14HYDROLOGY and HYDRAULIC REPORT 952 PINE AVENUE CONDOMINIUMS CITY OF CARLSBAD Prepared for: 4 Design Architecture & Planning 707 Mission Avenue Oceanside, CA 92054 Prepared by: bhA. Inc. land planning, civil engineering, surveying 5115 Avenida Encinas, Suite L Carlsbad, CA 92008-4387 (760) 931-8700 September 9, 2005 Revised July 14, 2006 W.O. 710-0964-6002 BR TABLE OF CONTENTS Discussion: Purpose and Scope Project Description Study Method Conditions of Concern Conclusions H. Calculations Existing Hydrology Proposed Hydrology ifi. Exhibits Existing Hydrology Map Proposed Hydrology Map IV. References I. DISCUSSION PURPOSE AND SCOPE: The purpose of this report is to publish the results of hydrology and hydraulic computer analysis for the .proposed condominium conversion for 952 Pine Avenue. The scope is to study the existing and proposed hydrology and hydraulics as it influences existing storm drain facilities in the vicinity during a 100-year frequency storm event. PROJECT DESCRIPTION: Existing Condition: The existing site has a four-unit apartment building located on-site. The four unit apartment building is being converted to condominiums. Runoff from the site sheet flows toward the southwesterly corner, via an existing concrete swale, where an existing catch basin intercepts the runoff. The runoff is then conveyed into the Street gutter of Pine Avenue via two 3-inch sidewalk underdrain pipes. A portion of the property to the east drains onto the subject property, crossing an existing wooden fence. See Exhibit "A" for existing hydrology. Proposed Condition: This is a condominium conversion project. This project is only proposing the reconfiguration of the existing uncovered parking spaces to garages and uncovered parking spaces, no significant change to the land use and imperviousness. After the apartment building is to condominiums, runoff from the site will surface drains in a similar manner to the existing drainage runoff. The existing catch basin will be replaced with a Swalegard swale filter by Kristar Enterprises Inc. The runoff will then be conveyed to the Street gutter via the proposed curb outlet (D-25 per S.D.R.S.D.). The condominium conversion will not affect the existing drainage pattern from the property to the east. The portion of the property to the east will continue to drain on-site. See Exhibit "B" for proposed hydrology. STUDY METHOD: The method of analysis was based on the Rational Method according to the San Diego County Hydrology Manual. The Hydrology and Hydraulic Analysis were done on HydroSoft by Advanced Engineering Software. Drainage basin areas were determined from the proposed grades shown on the Tentative Parcel Map for the property. The Rational Method provided the following variable coefficients: Soil group B will be used for a composite runoff coefficient for the existing and proposed hydrology analyses. The runoff coefficient (C=0.58) for attached residential land use reflects a composite value of landscaping, roof and street runoff per County of San Diego Hydrology Manual County. Initial Time of concentration (in minutes) = Ti = 60x(11.9x(L" 3)IH) 0.385 Rainfall Intensity = I = 7.44x(P6)x(Tc) ^ 0.645 (in/hr) P6 for 100 year storm = 2.5 (in) CONDITIONS OF CONCERN: The conversion of the four apartment units to condominiums at 952 Pine Avenue will not impact the downstream water bodies or their habitat integrity. There will be no change in the vicinities priority hydrologic regime that would be considered a condition of concern for the downstream water bodies and habitat integrity. See Table 1.1 below comparing existing and proposed storm drain flows. Table 1.1 Existing and Proposed Storm Drain Flows Cumulative Flow (cfs) Nodes Existing Condition 1.6 50.1 See Exhibit "A" Proposed Condition 1.6 50.1 See Exhibit "B" _______________ CONCLUSION: The existing and proposed storm drain system for 912 Pine Avenue Condominiums adequately convey a 100-year frequency storm event, and will not affect the existing drainage patterns. II. CALCULATIONS II. CALCULATIONS A. EXISTING HYDROLOGY **************************************•***********************•******* ****** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003, 1985, 1981 HYDROLOGY MANUAL (C) Copyright 1982-2005 Advanced Engineering Software (aes) Ver. 2.0 Release Date: 06/01/2005 License ID 1459 Analysis prepared by: BHA, INC 5115 Avenida Encinas Suite L Carlsbad, CA 92008 (760) 931-8700 ---------------------------------------------------------------------------- FILE NAME: K:\HYDRO\0964\EX1.DAT TIME/DATE OF STUDY: 23:15 07/13/2006 ---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: ---------------------------------------------------------------------------- 2003 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100.00 6-HOUR DURATION PRECIPITATION (INCHES) = 2.500 SPECIFIED MINIMUM PIPE SIZE(INCH) = 3.00 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 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0313 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: Relative Flow-Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top-of-Curb) (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* +--------------------------------------------------------------------------+ I PROPOSED HYDROLOGY I +--------------------------------------------------------------------------+ ** ** * ** ****** * ** *********************** * ** *** ***** *** ****** FLOW PROCESS FROM NODE 10.00 TO NODE 20.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< RESIDENTAIL (14.5 DU/AC OR LESS) RUNOFF COEFFICIENT= .5800 SOIL CLASSIFICATION IS "B" S.C.S. CURVE NUMBER (AMC II) = 80 INITIAL SUBAREA FLOW-LENGTH(FEET) = 78.00 UPSTREAM ELEVATION(FEET) = 65.30 DOWNSTREAM ELEVATION(FEET) = 64.90 ELEVATION DIFFERENCE(FEET) = 0.40 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.300 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 50.38 (Reference: Table 3-1B of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.750 SUBAREA RUNOFF(CFS). = 0.14 TOTAL AREA(ACRES) .0.05 TOTAL RUNOFF(CFS) = 0.14 FLOW PROCESS FROM NODE 20.00 TO NODE 50.00 Is CODE = 51 >>>>>COMPtJTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 64.90 DOWNSTREAM(FEET) = 64.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 192.00 CHANNEL SLOPE = 0.0047 CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 10.000 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.50 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.966 RESIDENTAIL (14.5 DO/AC OR LESS) RUNOFF COEFFICIENT = .5800 SOIL CLASSIFICATION IS "B" S.C.S. CURVE NUMBER (AMC II) = 80 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.24 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.20 AVERAGE FLOW DEPTH(FEET) = 0.14 TRAVEL TIME(MIN.) = 2.68 Tc(MIN.) = 10.98 SUBAREA AREA(ACRES) = 0.09 SUBAREA RUNOFF(CFS) = 0.21 AREA-AVERAGE RUNOFF COEFFICIENT = 0.580 TOTAL AREA(ACRES) = 0.14 PEAK FLOW RATE(CFS) = 0.32 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.16 FLOW VELOCITY(FEET/SEC.) = 1.30 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 50.00 = 270.00 FEET. FLOW PROCESS FROM NODE 50.00 TO NODE 50.00 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK * 1 <<<<< ******************************************************************** ******* FLOW PROCESS FROM NODE 30.00 TO NODE 40.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<(<<< RESIDENTAIL (14.5 DU/AC OR LESS) RUNOFF COEFFICIENT = .5800 SOIL CLASSIFICATION IS "B" S.C.S. CURVE NUMBER (AMC II) = 80 INITIAL SUBAREA FLOW-LENGTH(FEET) = 43.00 UPSTREAM ELEVATION(FEET) = 66.10 DOWNSTREAM ELEVATION(FEET) = 65.30 ELEVATION DIFFERENCE(FEET) = 0.80 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.991 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.587 NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE. SUBAREA RUNOFF(CFS) = 0.15 TOTAL AREA(ACRES) = 0.04 TOTAL RUNOFF(CFS) = 0.15 FLOW PROCESS FROM NODE 40.00 TO NODE 50.00 IS CODE = 51 >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 65.30 DOWNSTREAM(FEET) = 64.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 220.00 CHANNEL SLOPE = 0.0059 CHANNEL BASE(FEET) = 1.00 "Z" FACTOR = 50.000 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.50 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.823 RESIDENTAIL (14.5 DU/AC OR LESS) RUNOFF COEFFICIENT = .5800 SOIL CLASSIFICATION IS "B" S.C.S. CURVE NUMBER (AMC II) = 80 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.76 TRAVEL TIME THRU. SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.18 AVERAGE FLOW DEPTH(FEET) = 0.10 TRAVEL TIME(MIN.) = 3.11 Tc(MIN.) = 8.11 SUBAREA AREA(ACRES) = 0.43 SUBAREA RUNOFF(CFS) = 1.20 AREA-AVERAGE RUNOFF COEFFICIENT = 0.580 TOTAL AREA(ACRES) = 0.47 PEAK FLOW RATE(CFS) = 1.31 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.13 FLOW VELOCITY(FEET/SEC.) = 1.30 LONGEST FLOWPATH FROM NODE 30.00 TO NODE 50.00 = 263.00 FEET. FLOW PROCESS FROM NODE 50.00 TO NODE 50.00 IS CODE = 11 ---------------------------------------------------------------------------- >>>>>CONFLUENCE MEMORY BANK # 1 WITH THE MAIN-STREAM MEMORY<(<(< ** MAIN STREAM CONFLUENCE DATA ** STREAM RUNOFF Tc INTENSITY AREA NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE) 1 1.31 8.11 4.823 0.47 LONGEST FLOWPATH FROM NODE 30.00 TO NODE 50.00 = 263.00 FEET. ** MEMORY BANK * 1 CONFLUENCE DATA ** STREAM RUNOFF Pc INTENSITY AREA NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE) 1 0.32 10.98 3.966 0.14 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 50.00 = 270.00 FEET. ** PEAK FLOW RATE TABLE ** STREAM RUNOFF Tc INTENSITY NUMBER (CFS) (MIN.) (INCH/HOUR) 1 1.55 8.11 4.823 2 1.40 10.98 3.966 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 1.55 Tc(MIN.) = 8.11 TOTAL AREA(ACRES) = 0.61 FLOW PROCESS FROM NODE 50.00 TO NODE 50.00 IS CODE = 12 ---------------------------------------------------------------------------- >>>>>CLEAR MEMORY BANK * 1 <<<<< FLOW PROCESS FROM NODE 50.00 TO NODE 50.10 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 64.00 DOWNSTREAM(FEET) = 62.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 20.00. CHANNEL SLOPE = 0.0600 CHANNEL BASE(FEET) = 3.00 "Z" FACTOR = 50.000 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.25 CHANNEL FLOW THRU SUBAREA(CFS) = 1.55 FLOW VELOCITY(FEET/SEC.) = 3.17 FLOW DEPTH(FEET) = 0.07 TRAVEL TIME(MIN.) = 0.11 Tc(MIN.) = 8.21 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 50.10 = 290.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 0.61 TC(MIN.) = 8.21 PEAK FLOW RATE(CFS) = 1.55 END OF RATIONAL METHOD ANALYSIS II. CALCULATIONS B. PROPOSED HYDROLOGY - RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-2005 Advanced Engineering Software (aes) Ver. 2.0 Release Date: 06/01/2005 License ID 1459 Analysis prepared by: BHA, INC 5115 Avenida Encinas Suite L Carlsbad, CA 92008 (760) 931-8700 ---------------------------------------------------------------------------- FILE NAME: K:\HYDRO\0964\EX1.DAT TIME/DATE OF STUDY: 23:15 07/13/2006 ---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: ---------------------------------------------------------------------------- 2003 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100.00 6-HOUR DURATION PRECIPITATION (INCHES) = 2.500 SPECIFIED MINIMUM PIPE SIZE(INCH) = 3.00 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 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0313-0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: Relative Flow-Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top-of-Curb) (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* +--------------------------------------------------------------------------+ I EXISTING HYDROLOGY . I +--------------------------------------------------------------------------+ * ****** ****** *********** *** ****** * *********************** ********* *** * FLOW PROCESS FROM NODE 10.00 TO NODE 20.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< RESIDENTAIL (14.5 DU/AC OR LESS) RUNOFF COEFFICIENT = .5800 SOIL CLASSIFICATION IS "B" S.C.S. CURVE NUMBER (AMC II) = 80 INITIAL SUBAREA FLOW-LENGTH(FEET) = 78.00 UPSTREAM ELEVATION(FEET) = 65.30 DOWNSTREAM ELEVATION(FEET) = 64.90 ELEVATION DIFFERENCE(FEET) = 0.40 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.300 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH .= 50.38 (Reference: Table 3-1B of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.750 SUBAREA RUNOFF(CFS) = 0.14 TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) = 0.14 FLOW PROCESS FROM NODE 20.00 TO NODE 50.00 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW(<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 64.90 DOWNSTREAM(FEET) = 64.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 192.00 CHANNEL SLOPE = 0.0047 CHANNEL BASE(FEET) = 0.00 "Z" FACTOR = 10.000 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.50 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.966 RESIDENTAIL (14.5 DU/AC OR LESS) RUNOFF COEFFICIENT = .5800 SOIL CLASSIFICATION IS "B" S.C.S. CURVE NUMBER (AMC II) = 80 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.24 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.20 AVERAGE FLOW DEPTH(FEET) = 0.14 TRAVEL TIME(MIN.) = 2.68 Tc(MIN.) = 10.98 SUBAREA AREA(ACRES) = 0.09 SUBAREA RUNOFF(CFS) AREA-AVERAGE RUNOFF COEFFICIENT = 0.580 TOTAL AREA(ACRES) = 0.14 PEAK FLOW RATE(CFS) = 0.32 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.16 FLOW VELOCITY(FEET/SEC.) = 1.30 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 50.00 = 270.00 FEET. * **** ** **** ***************** ** * ** *** *************** * ******** FLOW PROCESS FROM NODE 50.00 TO NODE 50.00 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK * 1 <<<<< FLOW PROCESS FROM NODE 30.00 TO NODE 40.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< RESIDENTAIL (14.5 DU/AC OR LESS) RUNOFF COEFFICIENT = .5800 SOIL CLASSIFICATION IS "B" S.C.S. CURVE NUMBER (AMC II) = 80 INITIAL SUBAREA FLOW-LENGTH(FEET) = 43.00 UPSTREAM ELEVATION(FEET) = 66.10 DOWNSTREAM ELEVATION(FEET) = 65.30 ELEVATION DIFFERENCE(FEET) = 0.80 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.991 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.587 NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE. SUBAREA RUNOFF(CFS) = 0.15 TOTAL AREA(ACRES) = 0.04 TOTAL RUNOFF(CFS) = 0.15 FLOW PROCESS FROM NODE 40.00 TO NODE 50.00 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 65.30 DOWNSTREAM(FEET) = 64.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 220.00 CHANNEL SLOPE = 0.0059 CHANNEL BASE(FEET) = 1.00 "Z" FACTOR = 50.000 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.50 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.823 RESIDENTAIL (14.5 DU/AC OR LESS) RUNOFF COEFFICIENT = .5800 SOIL CLASSIFICATION IS "B" S.C.S. CURVE NUMBER (AMC II) = 80 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.76 TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.18 AVERAGE FLOW DEPTH(FEET) = 0.10 TRAVEL TIME(MIN.) = 3.11 Tc(MIN.) = 8.11 SUBAREA AREA(ACRES) = 0.43 SUBAREA RUNOFF(CFS) = 1.20 AREA-AVERAGE RUNOFF COEFFICIENT = 0.580 TOTAL AREA(ACRES) = 0.47 PEAK FLOW RATE(CFS) = 1.31 END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.13 FLOW VELOCITY(FEET/SEC.) = 1.30 LONGEST FLOWPATH FROM NODE 30.00 TO NODE 50.00 = 263.00 FEET. ********************************************************************* ******* FLOW PROCESS FROM NODE 50.00 TO NODE 50.00 IS CODE = 11 ---------------------------------------------------------------------------- >>>>>CONFLUENCE MEMORY BANK # 1 WITH THE MAIN-STREAM MEMORY<<<<< ** MAIN STREAM CONFLUENCE DATA ** STREAM RUNOFF Tc INTENSITY AREA NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE) 1 1.31 8.11 4.823 0.47 LONGEST FLOWPATH FROM NODE 30.00 TO NODE 50.00 = 263.00 FEET. ** MEMORY BANK # 1 CONFLUENCE DATA ** STREAM RUNOFF Tc INTENSITY AREA NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE) 1 0.32 10.98 3.966 0.14 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 50.00 = 270.00 FEET. ** PEAK FLOW RATE TABLE ** STREAM RUNOFF Pc INTENSITY NUMBER (CFS) (MIN.) (INCH/HOUR) 1 1.55 8.11 4.823 2 1.40 10.98 3.966 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) = 1.55 Tc(MIN.) = 8.11 TOTAL AREA(ACRES) = 0.61 ********************************************************************* ******* FLOW PROCESS FROM NODE 50.00 TO NODE 50.00 IS CODE = 12 ---------------------------------------------------------------------------- >>>>>CLEAR MEMORY BANK * 1 <<<<< * *************** * ******** **** **** *** ********* ** ****** * FLOW PROCESS FROM NODE 50.00 TO NODE 50.10 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<( >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 64.00 DOWNSTREAM(FEET) = 62.80 CHANNEL LENGTH THRU SUBAREA(FEET) = 20.00 CHANNEL SLOPE = 0.0600 CHANNEL BASE(FEET) = 3.00 "Z" FACTOR = 50.000 MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 0.25 CHANNEL FLOW THRU SUBAREA(CFS) = 1.55 FLOW VELOCITY(FEET/SEC.) = 3.17 FLOW DEPTH(FEET) = 0.07 TRAVEL TIME(MIN.) = 0.11 Tc(MIN.) = 8.21 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 50.10 = 290.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 0.61 TC(MIN.) = 8.21 PEAK FLOW RATE(CFS) = 1.55 END OF RATIONAL METHOD ANALYSIS III. EXHIBITS. IV. REFERENCES 20 10 0 20 40 60 SCALE: 1" 20' 5' '5 :, 5SSS 555 IT 5,55S5 ,;5' '5 10 30, 40 0.1 ,/(v} \\" \ 5' ': zi .' ''i,' \\\\ 5'5\ \ \,S •S. . :- -' S 5,•' Oi'\'\\ - / 'S 5' \ - ( EXIUP'JT ' PROPOSED HyDRo Tr ,cGy bk&n Cl-, F land pannn ChAl ~,-,urveylng 5115 AVENDA ENCNAS SUITE CARLSBAD,: CA. 92008-4387 (760) 931-8700 .................................................................... . ......... San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 12 of 26 Note that the Initial Time of Concentration should be reflective of the general land-use at the upstream end of a dainage basin. A single lot with an area of two or less acres does not have a significant effect were 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 T1 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) & INITIAL TIME OF CONCENTRATION (T Element* DU/ Acre .5% 1% 2% 3% 5% 10% L74 -Ti L 1 Tj LM TiL,1 Tj LM T1 LM T1 Natural 501 13.2 70 12.5 85 10.9 100 10.3 100 8.7 100 6.9 LDR 1 1 50 12.2 70 11.5 1 85 10.0 1 100 9.5 1 100 8.0 1 100 6.4 LDR 2 50 11.3 70 10.5 85 9.2 100 8.8 1 100 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 1 10.2 701 9.6 80 1•8.1 95 7.8 100 6.7 100 5.3 MDR 7.3 501 9.2 65 8.4 80 7.41 95 7.0 100 6.0 1001 4.8 MDR 10.9 50 1 8.7 65 7.9 80 6.9 90 6.4 100 5.7 1001 4.5 MDR 14.5 501 8.2 65 7.4 80 6.5 90 6.0 100 5.4 1001 4.3 HDR 24 501 6.7 65 1 6.1 75 1 5.1 90 1 4.9 95 4.3 100 3.5 RDR 43. 50 1 5.3 65 4.7 75 4.0 85 3.8 1 95 3.4 100 2.7 N. Corn 50 5.3 60 4.5 75 4o 85 3.8 95 3.4 100 2.7 G. Corn 50 4.7 60 4.1 75 3.6 85 3.4 90 2.9 100 2.4 O.P./Com 50 4.2 601 3.7 701 3.1 80 2.9 90 2.6 100 2.2 Limited L. • 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 1 2.6 901 2.3 1 1001 1.9 *See Table 3-1 for more detailed description ''A9 s." 3-12 z so slope—i 77-3 _ 2. 1 1.5 _ / 30 b 75 051 rob Lii LL. 0 - W I Ii z o 0, W :- 10 S uj 0 EXAMPLE: Given: Watercourse Distance (D) = 70 Feet Slope(s)=1.3% T =1.8(1.1W Runoff Coefficient (C) = 0.41 sy- Overland Flowmne Cr) = 9.5 Minutes SOURCE Airport Drainage. Federal Aviation Administration, 1965 FIGV RE Rational Formula - Overland Time of Flow Nomograph 34 San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 6 of 26 Table 3-1 RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use S I. 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 Residential (HDR) Residential, 24.0 DTJ/A or less 65 0.66 0.67 0.69 0.71 High Density Residential (I-IDR) Residential, 43.0 DU/A or less 80 0.76 0.77 0.78 . 0.79 Commercial/Industrial (N. Corn) Neighborhood Commercial 80 0.76 0.77 0.78 0.79 Commercial/Industrial (C. Corn) General Commercial 85 0.80 0.80 . 0.81 0.82 Commercial/Industrial (O.P. Corn) 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 fordirect calculation of the iunoff 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 Storm Water Standards 4/03/03 VI. RESOURCES & REFERENCES APPENDIX A STORM WATER REQUIREMENTS APPLICABILITY CHECKLIST f,t ?2. PIV4E AVE Complete Sections 1 and 2 of the following checklist to determine your project's permanent and construction storm water best management practices requirements. This form must be completed and submitted with your permit application. Section 1. Permanent Storm Water BMP Requirements: If any answers to Part A are answered "Yes," your project is subject to the "Priority Project Permanent Storm Water BMP Requirements," and "Standard Permanent Storm Water BMP Requirements" in Section III, "Permanent Storm Water BMP Selection . : Procedure" in the Storm Water Standards manual. . . .. If all answers to Part A are UNOn and gny answers to Part B are "Yes," your project is only subject to the "Standard Permanent Storm Water BMP Requirements". If every question in Part A and B is answered "No," your project is exempt from permanent storm water requirements. Part A flAfArminp Priority Prnirt Permanent Storm Water BMP Reauirements. Does the project meet the definition of one or more of.the priority project categories?* es No Detached residential development of 10 or more units - Attached residential development of 10 or more units X Commercial development greater than 100,000 square feet - Automotive repair shop - Restaurant - x Steep hillside development greater than 5,000 square feet Project discharging to receiving waters within Environmentally Sensitive Areas 8. Parking lots greater than or equal to 5,000 ft or with at least 15 parking spaces, and potentially exposed to urban runoff - Hi 9. Streets, roads, highways, and freeways which would create a new paved surface that is 5,000 square feet or greater - * Refer to the definitions section in the Storm Water Standards for expanded definitions of the priority project categories. - Limited Exclusion: Trenching and resurfacing work associated with utility projects are not considered priority projects. Parking lots, buildings and other structures associated with utility projects are priority projects if one or more of the criteria in Part A is met. If all answers to Part A are "No", continue to Part B. 30 Lt). 0. 7/0 - - 10 Storm Water Standards 4/03/03 Part B: Determine Standard Permanent Storm Water Requirements. Does the project propose: Yes No New impervious areas, such as rooftops, roads, parking lots, driveways, paths and sidewalks? - - New pervious landscape areas and irrigation systems? - Permanent structures within 100 feet of any natural water body? Trash storage areas? Liquid or solid material loading and unloading areas? - Vehicle or equipment fueling, washing, or maintenance areas? - Require a General NPDES Permit for Storm Water Discharges Associated with Industrial Activities (Except construction)?* Commercial or industrial waste handling or storage, excluding typical office or household waste? Any grading or ground disturbance during construction? - Any new storm drains, or alteration to existing storm drains? - *To find out if your project is required to obtain an individual General NPDES Permit for Storm Water Discharges Associated with Industrial Activities, visit the State Water Resources Control Board web site at, www.swrcb.ca.gov/stormwtr/industrial.htrnl Section 2. Construction Storm Water BMP Requirements: If the answer to question I of Part C is answered "Yes," your project is subject to Section IV, "Construction Storm Water BMP Performance Standards," and must prepare a Storm Water Pollution Prevention Plan (SWPPP). If the answer to question us "No," but the answer to any of the remaining questions is "Yes," your project is subject to Section IV, "Construction Storm Water BMP Performance Standards," and must prepare a Water Pollution Control Plan (WPCP). If every question in Part C is answered "No," your project is exempt from any construction storm water BMP requirements. If any of the answers to the questions in Part C are "Yes," complete the construction site prioritization in Part D, below. Part C: Determine Construction Phase Storm Water Requirements. Would the project meet any of these criteria during construction? Yes No Is the project subject to California's statewide General NPDES Permit for Storm Water - - Discharges Associated With Construction Activities? - Does the project propose grading or soil disturbance? - Would storm water or urban runoff have the potential to contact any portion of the construction area, including washing and staging areas? Would the project use any construction materials that could negatively affect water quality if discharged from the site (such as, paints, solvents, concrete, and stucco)? 31 Storm Water Standards 4/03/03 Part D: Determine Construction Site Priority In accordance with the Municipal Permit, each construction site with construction storm water BMP requirements must be designated with a priority: high, medium or low. This prioritization must be completed with this form, noted on the plans, and included in the SWPPP or WPCP. Indicate the project's priority in one of the check boxes using the criteria below, and existing and surrounding conditions of the project, the type of activities necessary to complete the construction and any other extenuating circumstances that may pose a threat. to water quality. The City reserves the right to adjust the priority of the projects both before and during construction. [Note: The construction priority does NOT change construction BMP requirements that apply to projects; all construction BMP requirements must be identified on a case-by-case basis. The construction priority does affect the frequency of inspections that will be conducted by City staff. See Section lV.1 for more details on construction BMP requirements:] Li A) High Priority Projects where the site is 50 acres or more and grading will occur during the rainy season Projects 5 acres or more. 3) Projects 5 acres or more within or directly adjacent to or discharging directly to a coastal lagoon or other receiving water within an environmentally sensitive area Projects, active or inactive, adjacent or tributary to sensitive water bodies Li B) Medium Priority Capital Improvement Projects where grading occurs, however a Storm Water Pollution Prevention Plan (SWPPP) is not required under the State General Construction Permit (i.e., water and sewer replacement projects, intersection and street re-alignments, widening, comfort stations, etc.) Permit projects in the public right-of-way where grading occurs, such as installation of sidewalk, substantial retaining walls, curb and gutter for an entire street frontage, etc. , however SWPPPs are not required. Permit projects on private property where grading permits are required, however, Notice Of Intents (NOls) and SWPPPs are not required. C) Low Priority Capital Projects where minimal to no grading occurs, such as signal light and loop installations, street light installations, etc. Permit projects in the public, right-of-way where minimal to no grading occurs, such as pedestrian ramps, driveway additions, small retaining walls, etc. Permit projects.on private property where grading permits are not required, such as small retaining walls, single-family homes, small tenant improvements, etc.