The URL can be used to link to this page

Home My WebLink AboutCT 2017-0006; Roosevelt Townhomes; Hydrology Report For 2569 Roosevelt Street; 2020-02-20---.... .. • .. - • ... • .. • .. ... .. .. ... .. .. • . ., ... .. .. .. -.. - ,.. - .. .. - RECORD COPY HYDROLOGY REPORT FOR 2569 ROOSEVELT STREET APN: 203-101-35 DATE: FEBRUARY 20, 2020 PREPARED BY: J&o.jM~, Imtial SAN DIEGO LAND SURVEYING AND ENGINEERING INC. 9665 CHESAPEAKE DRIVE, SUITE 445 r::~("""'•-·· r.\;J ,n,.' I I-r , r· ,....,. ~' /E _ -\.: ., u ,. , ::: \ L f I. ·-~:NFC: SAN DIEGO, CA. 92123 CITY OF CARLSBAD GRADING PLAN NUMBER GP 2019-0032 PROJECT NUMBER CT 2017-0006 DWG. NO. 520-9A ~=NT c,/,h,Q ~, Date --.. --.. -... .. ., -.. .. .. -.. .. -... • .. .. .. • -• .. .. .. • • • -.. TABLE OF CONTENTS PROJECT DESCRIPTION STANDARDS AND METHODS ANALYSIS CONCLUSIONS CERTIFICATION STATEMENT APPENDICES VICINITY MAP COUNTY OF SAN DIEGO STORM DRAIN MANUAL TABLE 3-1, RUNOFF COEFFICIENTS FOR URBAN AREA COUNTY OF SAN DIEGO STORM DRAIN MANUAL TABLE 3-2, TIME OF CONCENTRATION CHART COUNTY OF SAN DIEGO STORM DRAIN MANUAL FIGURE 3-2, INTENSITY DURATION DESIGN CHART EXHIBITS HYDROLOGY MAP -EXISTING CONDITION HYDROLOGY MAP -PROPOSED CONDITION 1 1 2 3 4 APPENDIX A APPENDIX B APPENDIX C APPENDIX D EXHIBIT A EXHIBIT B • • • -• • • ... • • • • -.. • .. -... • .. • • .. • • • -.. .. • • • -... PAGE 1 PROJECT DESCRl:PTION: EXISTING PROJECT SITE DESCRIPTION: The site is 0.2207 acres in size and is occupied by a family home . The general direction of drainage is to the southwest and the adjacent property. The project is immediately adjacent to Roosevelt Street. This public road drains to the north. There are wood fences on the north, west and south property lines. The east property line is Roosevelt Street. Therefor none or minimal offsite water drains onto the site. See the 30 scale drainage areas map in Exhibit A for more detail of the project . The existing impervious area is 2,504 SF. or 0.0575 AC . 26.1% PROPOSED PROJECT DESCRIPTION: The proposed project will consist of removal of the existing home and the construction of five new single family home. The rear of the site will be raised with a 3' high retaining wall so that the entire site will drain to the public right of way. The entire site will be disturbed by grading and construction. The public improvements will consist of additional water services, sewer lateral, a new driveway and sidewalk. See the 30 scale drainage areas map in Exhibit B for more detail of the proposed project . The proposed impervious area is 3,509 SF. or 0.0805 AC . 36.5% STANDARDS AND METHODS: PURPOSE OF CALCULATIONGS: Calculate the storm runoff generated by the residential site and the impact to the downstream lands . • • • • • • • • • • • • .. .. .. .. -.. .. -.. • .. • -------• - PAGE 2 HYDROLOGIC MODEL AND METHODS USED: This report uses the "Rational Method" as demonstrated in the County of San Diego Storm Drain Manual. Q = CIA WATER QUALITY DESIGN STORM: The design storm for this report shall be the 100 year storm . ANALYSIS PRE-DEVELOPMENT RUNOFF VOLUMES AND PEAK FLOWS: Runoff factor "C" for medium residential ( 4. 3 DU/A) with a soil type of "D" from table 3-1 "Runoff Coefficients for Urban Areas" from the above manual and attached in Appendix "B" is 0. 52. See Exhibit "A" for plan view of the drainage area . Time of concentration is composed of "Maximum Overland Flow Length" plus "Travel Time" to point of discharge. The maximum overland flow length is taken form Table 3-2, included in Appendix C, for medium density residential (4.3 DU/A) with a grade of 2% is 8 .1 mins. for the first 80 feet. The "Travel Time" for the remaining 75 feet is 6.7 mins. The total Tc= 14.8 mins. Using the 100 year storm and the rainfall intensity-duration- frequency curves from the chart in Appendix "D". Determine rainfall intensity "I". For 14.8 min., 100 year storm, the rainfall intensity= 3.28. Zone Existing Area El= 0.0307 acres This area consists of the portion of the site that drains to Roosevelt Street . Ql00 =CIA= .52 x 3.28 x 0.0307 = 0.05 CFS Zone Existing Area E2 = 0.1900 acres This area consists of the portion of the site that drains to the rear adjacent property. Ql00 =CIA= .52 x 3.28 x 0.1900 0.32 CFS Tota1 project runoff: Ql00 = 0.5 + 0.32 = 0.37 CFS • • • • • .. • .. • .. .. .. • • .. ... ◄ ◄ • .. .. .. .. • .. .. .. • • • • • .. PAGE 3 POST-PROJECT RUNOFF VOLUMES AND PEAK FLOWS: Runoff factor "C" for high density residential (24.0 DU/A) with a soil type of "D" from table 3-1 "Runoff Coefficients for Urban Areas" from the above manual and attached in Appendix "B" is 0.71. See Exhibit "B" for plan view of the drainage area . Time of concentration is composed of "Maximum Overland Flow Length" plus "Travel Time" to point of discharge. The maximum overland flow length is taken form Table 3-2, included in Appendix C, for medium density residential (4.3 DU/A) with a grade of 2% is 8 .1 mins. for the first 80 feet. The "Travel Time" for the remaining 75 feet is 6.7 mins. The total Tc= 14.8 mins . Using the 100 year storm and the rainfall intensity-duration- frequency curves from the chart in Appendix "D". Determine rainfall intensity "I". For 14.8 min., 100 year storm, the rainfall intensity= 3.28 . Zone Proposed Area Pl= 0.2207 acres This area consists of the portion of the site that drains to Chelsea Road . Ql00 CIA .71 X 3.28 X 0.2207 0.51 CFS Tota1 project runoff: Ql00 = 0.51 CFS CONCLUSIONS: The most important design change from the existing condition is that the amount of area that drains to the public street is now 100% of the site. No impact to the adjacent properties is anticipated. The runoff of the proposed site is an increase over the existing site. This is mitigated by the fact that the runoff is directed to the improved public street. The brick pavers (impervious paving will reduce, to negligible, the runoff of small storms and reduce the runoff of large storms so as to not exceed the capacity of the completely improved public street to carry the storm runoff down stream . The overall increase in runoff ( 0. 14 CFS) is directed to the street . • • 1111 .. • .. .. • .. f/1 • • • • .. -• -.. -.. -• • • • .. -• .. • .. .. PAGE 4 CERTIFICATION STATEMENT: This Hydrology Report has been prepared under the direction of the following registered civil engineer. The registered civil engineer (Engineer) attests to the technical information contained herein and the engineering data upon which the following design, recommendations, conclusions and decisions are based. The selection, sizing, and design of storm water treatment and other control measures in this report meet the requirements of the Regional Water Quality Control Board Order R9-2013-0001 and subsequent amendments. ENGINEER OF WORK: MICHAEL LEE SMITH, RCE 35471 MY REGISTRATION EXPIRES ON 9/30/2021 DATE: 02-20-2020 -• • • • .. • ,. -• • • .. .. .. .. .. .. 41 .. -.. .. .. .. ti • .. • .. • .. .. " .. APPENDIX A VICINITY MAP • • • • -- • • • • .. 111 • .. • • • • .. • -.. • .. • • • • ... ,. • ◄ • .. • • • • SITE VICINITY MAP CITY OF OCEANSIDE PACIFIC OCEAN 78 VICINITY MAP NO SCALE NOT TO SCALE 11111 • 4 • .. • • .. • .. .. .. .. .. .. • • • Ill .. 4 .. COUNTY TABLE 3-1, APPENDIX B OF SAN DIEGO STORM DRAIN MANUAL RUNOFF COEFFICIENTS FOR URBAN AREA I I I I & • ll I • • San Diego County Hydrology Manual Date: June 2003 l I • • I t .. . ' j .. . a I • I t I Section: Page: Table3-l RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use I Runoff Coefficient ''C" Soil Type NRCS Elements Coun Elements %IMPER. A B Undisturbed Natural Terrain (Natural) Pennanent Open Space o• 0.20 0.25 Low Density Residential (LDR) Residential, 1.0 DU/A or less 10 0.27 0.32 Low Density Residential (LDR) Residential, 2.0 DU/A or less 20 0.34 0.38 Low Density Residential (LDR) Residential, 2.9 DU/A or less 25 0.38 0.41 Medium Density Residential (MOR) Residential, 4.3 DU/A or less 30 0.41 0.45 Medium Density Residential (MOR) Residential, 7.3 DU/A or less 40 0.48 0.51 Medium Density Residential (MOR) Residential, 10.9 DU/A or less 45 0.52 0.54 Medium Density Residential (MOR) Residential, 14.5 DU/A or less 50 0.55 0.58 High Density Residential (HOR) Residential, 24.0 DU/A or less 65 0.66 0.67 High Density Residential (HOR) Residential, 43.0 DU/ A or less 80 0.76 0.77 Commercial/Industrial (N. Com) Neighborhood Commercial 80 0.76 0.77 Commercial/Industrial (G. Com) General Commercial 85 0.80 0.80 Commercial/Industrial (O.P. Com) Office Professional/Commercial 90 0.83 0.84 Commercial/Industrial (Limited I.) Limited Industrial 90 0.83 0.84 Commercial/Industrial (General I.) General Industrial 9S 0.87 0.87 • I C 0.30 0.36 0.42 0.45 0.48 0.54 0.57 0.60 0.69 0.78 0.78 0.81 0.84 0.84 0.87 ll I 3 6 of26 D 0.35 0.41 0.46 0.49 a I l:t'.1 >< -V, 1-3 -z Cl @-' 0.57 0.60 0.63 ~ 0.79 "'d :;,:, 0.79 0 "'d 0.82 0 Cl) tt'l 0.85 t:, 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 Forest). DU/A= dwelling units per acre NRCS = National Resources Conservation Service 3-6 l I • • > 1-t, 1-t, tr:l z 0 ->< c::i -.. ... • • • • • • • -• .. .. - • .. 41 .. -,. • • .. • • 411 • • • • .. APPENDIX C COUNTY OF SAN DIEGO STORM DRAIN MANUAL FIGURE 3-1, TIME OF CONCENTRATION CHARTS .. • • • • • • ... .. ... .. ... .. ... .. -.. .. • • -.. • • • • .. • • • • -- 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 . Table 3-2 MAXIMUM OVERLAND FLOW LENGTH (LM) & INITIAL TIME OF CONCENTRATION {Ti) Element* DU/ .5% 1% 2% 3% 5% 10% 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 LOR I 50 12.2 70 11.5 85 10.0 100 9.5 100 8.0 100 6.4 LOR 2 50 11.3 70 10.5 85 9.2 100 8.8 100 7.4 100 5.8 LOR 2.9 50 l0.7 70 10.0 85 8.8 95 8.1 100 7.0 100 5.6 MOR 4.3 50 10.2 70 9.6 80 8.1 95 7.8 100 6.7 100 5.3 MOR 7.3 50 9.2 65 8.4 80 7.4 95 7.0 100 6.0 100 4.8 MOR 10.9 50 8.7 65 7.9 80 6.9 90 6.4 100 5.7 100 4.5 MOR 14.5 50 8.2 65 7.4 80 6.5 90 6.0 100 5.4 100 4.3 HOR 24 50 6.7 65 6.1 75 5. I 90 4.9 95 4.3 100 3.5 HOR 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 • --.. - .. .. - .. • .. ,. ◄ 411 .. .. ,. .. ◄ • • • .. • • • • • 11 • • APPENDIX D COUNTY OF SAN DIEGO STORM DRAIN MANUAL FIGURE 3-1, INTENSITY DURATION DESIGN CHART l I I _t 10.0 9.0 8.0 7.0 6.0 5.0 lo 3.0 2.0 0 9 8 7 6 5 0. 0. 4 0 .3 0 .2 "' " ' ..... -.. "' '" " 0 .1' • r,,.,, .... !lo.. ' • r,,.,, ' " . " 'r-,,, • r,,.. ""' ' . " ... """" ·r,,. • l • • .. ' ' . ' "!lo.. ... 'I' , ... i,,. .,ro~ . r--.. ' .. , ... ""~~~~ , ... '~ ~ ~~ I" "" • "'~~ l"r,,. ~ .. ~~ I"' ""' ~ ~ .. , ~ .. "' .... ,, "' ~ ~ , .. ~~ ... -~ ~~ . "" ~ ~ .. ,, ~~ ~ ... , "'"" ~~ ~~ 5 6 7 8 9 10 15 20 30 Minutes • I l I • j j • • • EQUATION I = 7.44 P5 D-0.645 I I = Intensity (In/hr) Ps = 6-Hour Precipitation (in) D = Duration (min) ~, " . " , ... I" " ' I"' I".., ... ' ,,.. ~ . ' I""' I" ... I"' ""' • ""~ ~~ "i"o ..... 'r--""~ ~ I"' ~ ... " "' " ,. ~ " .. ... • I"""" ... ~ ""' ""' "" """ 40 50 1 2 3 4 5 6 Duration Hours • I 0) i .. l 6.0 °& 5.5 i 5.0 :::i 4.5 5' n 4.0 i 3.5 .!!?. 3.0 2.5 2.0 1.5 1.0 Intensity-Duration Design Chart • Template • • . , • • • • • J • • Dlractlons for Appllcallon: (1) From precipitation maps determine 6 hr and 24 hr amounts for the selected frequency. These maps are induded in the County Hydrology Manual (10, 50, and 100 yr maps induded 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 appHcaple 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. Appllcatlon Form: (a) Selected frequency IO O year (b) P6 = 2, < in., P24 = ~, '=>,~ = S<.o %c2i 2 _ 24 (c) Adjusted P6<2> = _.!2._ in. (d)tx= ~min. ~l".>T, 14. 8' PtteP. (e) I= 3-°l.'j( in.lhr. Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. 10 14.~ 1.._;- ~ ~ & .. I ! I . ' I I I I • I . , C I I I l-I 1 · i I l l - ' , ' I I j -· I ,·:t~ ' . I ' ; ·I I s2°45' u ' 7 l -'"I' ., , ! ' j 1 i · , I ~1 ~-i-t r-,-.--,--,--, ----:-----------.---. ----.J --I I;' . I ~-i 1 •.• •• ,•. If it . ' -; .. , . . \VI e X -(, -------.--·-~~ .. , .~ --I 1 in , I -; ' ' I j • I ' I <r-I I • CD I ~ I I l s-30' ! I I I - "7 -1 I j I I ~- County of San Diego Hydrology Manual Rainfall Isopluvia/s 100 Year Rainfall Event-24 Boun lsopluvial (inches) l-Ls- DPW ~GIS _,, ..... _ ---- N -+-E ntSMAP•l'IICMOEOWfflOll'W_,.,Ol,.,,,ICIND, PTHEJIE)O'RESS 011-.ICLUll9IG,.,,-N<JfLM!U>TO. THE..uEDW-,,U 01'-Aa!T't NllJ-FDII• PAllllCI.INt !'1-. Coll,lltlN_.,,_,._ ,_.....,. ____ .. MNCWI_ ______ .. ___ .. _...-, .. ..-. ----------__,.,__, __ _ s 3 0 IL- 3 MIies I I I I I I I I I I I ' I -r I ' I I I • • I • i I ..j. r .i--s iTh-..... _ ~I ! ' . I ! ~i ~t 'ci .... ,,,,,. ' ! ~~_'..----r~---?~~:+:~~~mfrJ I 32"45' 32"30' "1 ' l l 0 .o ~. IC)) '? , ... • I ~ l ! i 8 . ,.._ ... ... J_. I I I I . ·!: c6 ' l : I :i --I --. 1 t ·-l I 1 I r - + j -, I i I I i •. ! . , I • ---..j '•• t I •., I I • • l 1'-•t .••~•j t \. - I I • -· J .,., . .. . ... .. . .. . .~-..... ! • • • . .·· so: c:s···· ' -~· e -..,.----,------, . i 1 I : . -r-. C • I -r-·-·r I I j -.----, , ! 33'30' ----t-• l ..1 • •;•••..,t : I : . .. ... .· ~--· ·-· .. - J ;~ -~ J ;-r: ---r-' I saw- , ~--• .. -·'t· ., 32"30' 1 -i County of San Diego Hydrology Manual Rainfall Isop/uvials 100 Year Rainfall Event -6 Boan lsopluvial (inches) DPW 41tGIS _,,Moi<_ ---- N + ~-==-~~~---=~ 0# MEM:IWl!'Aam' IHD l'ffllESI FOR A ~Nl'TICIANI l'URPOIE ao,,.wo-.,. ..... -==-=-===.=:=-=--_,.._ .. -. ________ _,..__ ...-.-.. ---s 3 0 2- 3 MIies ?"5 --.. • • .. .. • • .. • .. • -• - • .. • .. • .. .. • .. • 1111 .. • .. • • • EXHIBIT A EXISTING CONDITIONS DRAINAGE AREAS MAP "" "" ···•··--··---------- I I I I I I I " I I I I I I I I I I ----,----- I ,, : ZONE E2 If' f' I EXHIBIT A HYDROLOGY MAP EXISTING CONDITIONS SCALE 1" = 30' PROJECT AREA AREA = 9,613 SF. OR 0.2207 AC. ZONE E1 AREA = 1,336 SF. OR 0.0307 AC. ZONE E2 AREA = 8,277 SF. OR 0. 1900 AC. IMPERVIOUS AREA AREA = 2,504 SF. OR 0.0575 AC. 26.1% OF SITE • .. ... 11 ... 41 ... .. ... .. .. .. .. .. .. .. .. • • • -• .. • • • .. --• .. .. • --• EXHIBIT B PROPOSED CONDITIONS DRAINAGE AREAS MAP I I I I I I I I " t .. I fiJ ... I I I I I l ' ~ '.::=::::::=::: ----t-=--- V y y y y V ~ D --~------~ ....... ------ i L __ 11 :1 ~ :1 I I I I :(~\ nw,sro,w S1UCCO 8UILDIHO 11 I 11 /_ 11 :1 ,---------1, I ~ """"""""""·" ....... I DtlSffHO 8UILDIHO ----~·············-S·.r I ------,- DtlSffHO 8UILDIHO 1 I I EXHIBIT B HYDROLOGY MAP PROPOSED CONDITIONS SCALE 1" = 30' PROJECT AREA AREA = 9,613 SF. OR 0.2207 AC. ZONE P1 AREA = 9,613 SF. OR 0.2207 AC. IMPERVIOUS AREA AREA = 3,509 SF. OR 0.0805 AC. 36. 5% OF SITE LEGEND ----ZONE P1 --+ DIRECTION OF DRAINAGE ----BUILDING PAD ~ BRICK PAVERS VZZZZZ7A PLANTER ----LOT LINE