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Home My WebLink AboutCT 08-06; HIGHLAND JAMES SUBDIVISION; HYDROLOGIC - HYDRAULIC DRAINAGE REPORT; CDP 15-47, CDP 15-48, CDP 15-49, DWG 483-6B; 2017-01-06TERR MAR CONSULTING ENGINEERS HYDROLOGIC/HYDRAULIC DRAINAGE REPORT ·: 100-year Peak Flow in Pre & Post-Development Conditions for: Highland James Subdivision Project ID (CT 08-06) CDP 15-47, 15-48 & 15-49 Carlsbad, CA, 92008 APN: 207-130-75 to 207-130-78-00 DWG 483-68 & DWG483-6C Prepared by: Terramar Engineering 2888 Loker Avenue East, Suite 30~,,. Carlsbad, CA, 92010 760-603-1900 760-603-1909 (fax) cc,c;;,;::c" ·;'', ·"'.':>'J" Report Prepared: January 6'"'2017 ' . 2888 LOKER AVE EAST STE. 303 111 CARLSBAD • CA 111 92010 • {7 60} 603-1900 TerramarEngineering.com • lnfo@TerramarEng.com TERR MAR CONSULTING ENGINEERS TABLE OF CONTENTS Introduction .......................................................................................................................... . Project Description .................................................................................................................... , ,,,1 !( Location ..................................................................................................................................... ·.· ........... "+ii! Description ................................................................................................................................................ f' Land Use and Zoning .............................................................................................................................. f'ii+ F~MA Considerations ......................................................................................... : .............................. :~~;; Drainage Aspects .............................................................................................................. ·•··l)t 2 Existing Condition ........................................................................................................................ /J~!t. 2 Developed Condition ................................................................................................................ ;::::JI};( ... 3 Hydrology................................................................................................................ . .... 4 Time of Concentration ........................................................................... ::,;~~{;··::················ Rational Method (per Section 3.1 of the SDCHM) ................................. '.<It ... .. Modified Rational Method (per Section 3.4 of the SDCHM) ................................... :; .. /(,' Hydraulics ................................................................................................ . Catch Basin (Weir) ................................................................................ ,,:,,····,;;,-. ,. .................... ,; 6''' ...................... , .. , ... 6 Graded Trapezoidal Weir .................................................................. iJJfL. Pipes ................................................................................................. ::1:,1; .. Conclusions ................................................................................. :,~, .. : APPENDIX A: Maps APPENDIX B: Calculations ; ................................ 7 2888 LOKER AVE EAST STE. 303 • CARLSBAD • CA • 92010 • (760) 603-1900 TerramarEngineering.com • lnfo@TerramarEng.com TERR MAR CONSULTING ENGINEERS HYDROLOGIC/HYDRAULIC DRAINAGE REPORT 100-year Peak Flow in Pre & Post-Development Conditions for Highland James Subdivision, Carlsbad, CA INTRODUCTION This document summarizes the approach used to analyze and compare the hydrologic an:d hydraulic volumetric flows of the existing and proposed conditions of a project site in the City of, ·· · Carlsbad. In accordance with the Carlsbad BMP Design Manual (2016) and the San Diego County Hydrology Manual, this report will show that the proposed condition will miti9,~} fl d. 411:· 1:1: oo 1ng. I'. 't1::1:1:: .. '~m:~ ,,J(Jw.,:. In addition to flood control, the proposed drainage of the project site must comply with P .. At Control and Hydromodification Management requirements as mandated by the Carlsq'f!'a~'BfflJ:> Design Manual. According to the Carlsbad Watershed Management Area Analysi{(WMM) prepared by Geosyntec & Rick Engineering (Oct 2014 ), the project site existst1witl;lih" the Hydromodification Exempt area and thus does not require a Hydromodification an . lease refer to the "Storm Water Quality Management Plan" (SWQMP)" prepar Engineering for further discussion of Pollutant Control requirements;< PROJECT DESCRIPTION Location Street Address: 3980 Highland Drive ','.'.1/ City/County/State/Zip: Carlsbad, County of San Diego, California, 9 33°09'13" N, 117°19'44" W ,<, Latitude, Longitude: Description This project consists of a lot subdivision and residential develop . Carlsbad, CA (See Location Map in Appendix A). The site aref ... 49,653 sf. The proposed residential development will result in the existing lot subdivig~<;i~intofive (5) smaller lots which will be the location of 5 residences. The total impervious.~tes: in the existing and proposed conditions is 4,340 sf and 22,146 sf, respectively. · Land Use and Zoning The subject property is the current location of an ·eXlsting residence and appurtenances (hardscape and landscape). .. · · · ··· ,:', :' ,,,; In the proposed condition, all 5 lots will be future locations for residences. Access to lots 4 & 5 are afforded by Highland Avenue to the southwest. Access to lots 1, 2 and 3 are afforded by James Drive to the northeast. Each lot will consist.of a residential building, connected garage, driveway, sidewalk, and landscaping. Zoning: R-1 (Single-family Residential) APN: 207-130-75 to 207-130-78-00 1 2888 LOKER AVE EAST STE. 303 • CARLSBAD • CA • 92010 • (760) 603-1900 TerramarEngineering.com • lnfo@TerrammEng.com -------------------4 TERR MAR CONSULTING ENGINEERS FEMA Considerations Before proceeding with the calculations, the property was investigated from the Federal Emergency Management Agency (FEMA) point of view, to determine if the property is loc~fed totally or partially outside of a flood zone. Community Number: 06073C0764G Effective Date: 5/16/12 Zone: X (unshaded) ZONE X (unshaded) is defined as "The areas of minimal flood hazard, which are the ar§~ outside the Special Flood Hazard Area (SFHA) and higher than the elevation of the 0.2-perc_en annual-chance flood." · ·· DRAINAGE ASPECTS The project site is the future location of five (5) residences on five (5) individu~I cumulative area of the project site is 1.14 acres. The project site generally drains sci northeast (Highland Dr to downstream James Dr). A City storm drain curb inlet alq, · located. near th~ eastern corner of the project site is considered.{··· comparison/compliance (POC). · ----<+ tk. ,,·Y;,'i, Existing Condition The subject site is a residential parcel located on the easterly side ofi property is located at the top of a rise with the east side of the si approximately 15 to 20 feet lower than the west side. A 10-foot, ap extends midway through the site from the south to north. A 2-to-3 f · top of the cut on the north end. The property is presently occu __ · residence with a detached garage and driveway. There is a foci -garage and a 3-foot rock retaining wall behind the house. There is a 12-inch public storm drain that conveys stormwate noff from Highland Drive eastward through the site along its northern perimeter down ta James Drive; however the property does not contain any storm drain infrastructuret:for.J:1~lormwater generated onsite. Existing topography dictates that stormwater runoff sheet flo'Ws:>along the ground surface of the property from west to east and discharge offsite and onto ~ames Drive at the sites eastern edge. In pre-development conditions the entire site m~Y. t,e, considered as a single drainage management area with one point of discharge (at its easternperimeter). ,,-~;/ ?\f( Once the runoff discharges onto James Drive it is collected by a curb inlet on James Drive which is part of the municipal separate storm sewer:+~ystem (MS4) owned and operated by the City of Carlsbad. The City MS4 conveys the rur'iofffuH:her downstream to the Agua Hedionda Lagoon with ultimate discharge into the Pac;ific, Ocean along Carlsbad State Beach (at Tamarack jetties and at the discharge for the Encina Power Station). 2 2888 LOKER AVE EAST STE. 303 • CARLSBAD • CA • 92010 • (760) 603-1900 TerramarEngineering.com • lnfo@TerramarEng.com TER MAR ENGINEERS Developed Condition In the proposed condition, the natural drainage pattern of the site is roughly maintained. Ridge$ and swales divide the site into twelve (12) Drainage Management Areas (OMA). The DMAs are designated N1a, N1b, N1c, N2a, N2b, N2c, N3, N4, N5, N6, N? and NB. All DMAs discharge into a private storm drain system via catch basins and the private storm drain system terminate~-, at an existing public curb inlet (City MS4). N1 a+N1 b and N2a+N2b each discharge into . · Bioretention Best Management Practice (BMP) for water quality purposes. Higher flows from the BMPs enter a concrete swale which terminates at catch basins and enters the private storm drain system. N3 through NB flow to catch basins without entering structural BMPs and .cfre ... treated by Site Design BMPs. See the Water Quality Management Plan prepared by Terriffeic\~;:s.r: Engineering for a detail explanation of the methodologies used to design BMPs for · '.• Quality requirements. The DMAs are described below. • OMA N1a is 0.03B-acres {22% impervious) and an area within the public riglt;t"'!w~y (ROW) that flows onto N 1 b. N 1 a consists of landscaping and the driveway for.~ottf that ties into Highland Avenue. ' '" • • • • • • • • OMA N1b is 0.274-acres (41% impervious) and contains proposed Lot 1·(\ run-on from N1a. Runoff discharges into a Bioretention B,iif>t r pollutant . · leaving the BMP are managed by infiltration and an overfl. conveys flows to N 1 c. OMA N1c is 0.014-acres (0% impervious). This OMA conve upstream BMP to the private storm drain system. Runoff flovv~Jo : which terminates at a catch basin. .·.···. f ·::..::: 4, OMA N2a is 0.03B-acres (22% impervious) and an area Wit· (ROW) that flows onto N2b. N2a consists of landscaping agfJ;i. ties into Highland Avenue. 4,.t iTI .. · public right-df.:.way eway for Lot 5 that }lt~I~ _.,, OMA N2b is 0.274-:acres (3B% impervious) and contains··proposed Lot 5. N2b accepts run-on from N2a. Runoff discharges into a Bioretentioq .. B .for pollutant control. Flows leaving the BMP are managed by infiltration and an,.:ove bw weir. The overflow weir conveys flows OMA N2c. DMA N2c is 0.011-acres (0% impervious). This DM/~Fconveys the overflow from the upstream BMP to the private storm drain system. RUnoff flows to a riprap drainage swale which terminates at a catch basin. DMA N3 is O.OB2-acres (62% impervious) arfcl'rio~fains the southern half of Lot 3. Runoff from N3 enters the private storm drain system via a catch basin near the northeastern corner of the OMA. OMA N4 is O.OB2-acres (50% impervious) ati~l~ontains the northern half of Lot 3. Runoff from N4 enters the private storm drain system via a catch basin near the northern edge of the OMA. DMA N5 is O.OB2-acres (65% impervious) and contains the southern half of Lot 2. Runoff from N5 enters the private storm drain system via a catch basin near the northern edge 3 2888 LOKER AVE EAST STE. 303 111 CARLSBAD III CA 111 92010 o (760) 603-1900 TerramarEngineering.com • lnfo@TerramarEng.com TERR MAR CONSULTING ENGINEERS of the OMA. • OMA N6 is 0.082-acres (50% impervious) and contains the northern half of Lot 2. Runoff from N6 enters the private storm drain system via a catch basin near the northern eage of the OMA. • OMA N7 is 0.082-acres (65% impervious) and contains the southern half of Lot 1. Runoff from N4 enters the private storm drain system via a catch basin near the northern edge of the OMA. • OMA N8 is 0.082-acres (49% impervious) and contains the northern half of Lot 1. Ru from N4 enters the private storm drain system via a catch basin near the northern e of the OMA. N8 also contains a 12-inch public storm drain with a 5-ft easement al · northern perimeter that conveys flows from Highland through the site and int<;:>' drain under James Drive (the project does not contribute runoff to this pipeline). N1a, N1b, and N1c will be evaluated as one collective OMA since these DMAs all d point. N2a, N2b, and N2c will also be evaluated as one collective OMA since the, drain to one point. r See Appendix A to see the existing and proposed site layout. HYDROLOGY ; "'i.q,'' u)u,u ,{,'~"'{g.-,, • The methodology for this drainage report follows analyses found within Secti. ·. Diego County Hydrology Manual (hereafter referred to as the "Hydrology 1via· IJUE See Appendix B for the detailed calculations described in the section .... Time of Concentration The time of concentration (tc) is used to determine the peak flQ value represents the time it takes for the entire area to contribut .· flow path length, slope, and surface roughness. An iterative proc First, the initial time of concentration for the initial 100 feet of flow using the following equation. a storm event. The Lo.s .. , tci = 1.8 * (1.1 -C) * -r·· . S3 Where: tci = initial time of concentration in minutes o and is a function of as used to determine tc. distance was determined Equation 1 C = unitless runoff coefficient of the initial.,§r~ijl .. =,0.9*ai + Cp*(1-ai) Cp = unitless runoff coefficient of the natu(?I ~gil (Soil Type B for this site) = 0.25 ai = unitless impervious fraction = impervio'µi:farea I total area L = initial flow path length in feet (maximum 100 ft) s = initial slope of the longest flow pafhas a percent(%) With the initial tci evaluated, the subsequent flow velocity of the concentrated flow will be determined. A final velocity of the channel flow will be estimated and used to estimate the travel time (ti), which represents the time it takes for the concentrated flow to channelize. Summing tci and t1 yields the total time of concentration (tc). With tc, the outlet volumetric flow Q and flow 4 2888 LOKER AVE EAST STE. 303 • CARLSBAD o CA o 92010 • {7 60) 603-1900 TerramarEngineering.com o lnfo@TerramarEng.com TERR MAR CONSULTING ENGINEERS velocity v can be determined. The equations for Q are described in sections "Rational Method"·· and "Hydraulics" (Manning's Equation). The estimated final velocity is then iterated until the value converges on the calculated final velocity. The iteration process will yield the true travel time between the initial area evaluation point (i.e. 100-ft along the longest flowpath) and'tt]e OMA outlet. Subsequently, the process with yield the correct tc and Q. Table 1 in the next section outlines the times of concentration for each OMA (existing and proposed). ' Rational Method (per Section 3.1 of the SDCHM) To determine the 100-yr runoff for each drainage area, the following equation was used. Q = CIA Equatt Where: Q = runoff in cubic feet per second ( cfs) C = unitless runoff coefficient of the initial area I = rainfall intensity in in/hr (see below for equation) A = contributing area in acres We evaluated the rainfall intensity for each OMA using the following equation (from · the Hydrology Manual). •···· I = 7.44P6D-0·645 Where: I= rainfall intensity in in/hr Pa = cumulative precipitation during the most intense 6 hours 0 = duration in minutes To determine the 100-yr runoff (010o) of each OMA, we used Pa fofJh times of concentration for the 100-yr event (analyzed in the prevido determine the 100-yr peak rainfall intensity. The following table o Rational Method analysis. N1a+N1b+N1c 5.0 1\09 N2a+N2b+N2c 5.0( 1:b5 N3 6. 0.31 N4 .:9;7 ~0:0.21 NS tes ~~ ",· 0.32 N6 ··1:0:1 0.21 N? 8.3 0.26 NB 8.9 0.22 5 vent and the for the duration to results from the 2888 LOKER AVE EAST STE. 303 • CARLSBAD • CA • 92010 • (760) 603-1900 TerramarEngineering.com • lnfo@TerramarEng.com TERR MAR CONSULTING ENGINEERS Modified Rational Method {per Section 3.4 of the SDCHM) The runoff values in the previous section represent the flows leaving each OMA. Each flow will enter the private storm drain system via a catch basin and confluence before leaving the site and entering the City MS4. To quantify the confluence flow, we used the process outline~ in Section 3.4 of the Hydrology Manual. At each confluence point, the times of concentration and :".:;, runo~ values were used in combination with the following set of equations to determine tn~!t resulting flow. ~;;;" Junction Equation: T1 < T2 < T3 T1 T1 Qn = Q1 + T2 Qz + T3 Q3 12 Q Tz Q Qyz = Qz + Ii 1 + y3 3 /3 /3 QT3 = Q3 + 11 Q1 + 12 Qz The greatest value of OT1, QT2, and QT3 will be accepted as the resulting corresponding time of concentration (e.g. if QT2 was greatest, Tc = Tz}. This i~;i approach, because friction losses were not considered in the coQf1: F · reduce flow velocity, thus reducing volumetric flow. '' HYDRAULICS See Appendix B for the detailed calculations described in the section. Catch Basin {Weir) Runoff from each OMA will enter the private storm drain system catch basin will have a grate of dimension 1 'x1 ', thus providing1"ia'i· head for the catch basins is either a maximum 3". To determin~I. inlet, the following equation was used. Qw = CwLH1.s Where: Ow = volumetric flow of weir in cfs . Cw = unitless discharge coefficient of weir = 3.J;(tyR,igal) L = length of weir = 4 ft · .. > H = available weir head = 3" ·'tf '·· .... ·· ''a catch basin. Each "tfi of 4'. The available ow capacity of the curb Equation 4 The flow capacity for the weir was determined to b~:4i''.55 cf1( The maximum 100-yr runoff flowing to a catch basin is 1.09 cfs. Therefore, the weirs are sufficiently sized to convey the 100- yr runoff flows for their respective OMAs. ·· See Appendix B for the detailed analysis. 6 2888 LOKER AVE EAST STE. 303 • CARLSBAD • CA • 92010 • (760} 603-1900 TerramarEngineering.com • lnfo@TerramarEng.com TERR MAR CONSULTING ENGINEERS Graded Trapezoidal Weir DMAs N1 and N2's runoff collect in Bioretention BMPs. Lower flows will infiltrate into the soil,. while larger flows will overflow into a concrete channel via a trapezoidal weir graded into the§ sloped sides of the Bioretention basin. The concrete channel will convey flow to a catch basin; the analysis for determining the flow capacity of the catch basin was described in the previous+ section. To determine the flow capacity of the weir, the weir equation from the previous section (Equation 4) was used. The graded weir was designed as a Cipoletti weir (i.e. 4:1 side slopes with available head of 3", and bottom (crest) width of 3' (used as weir length). The discharge/ coefficient C will be 3.367 as per Equation 7-7 of the USSR Water Measurement Manual ( With this information and equation 4, the flow capacity of the graded trapezoidal weir wa · determined to be 1.26 cfs, which is greater than both N1 and N2's 100-yr runoff flow of 1.05 cfs, respectively. Therefore, the graded weirs are sufficiently sized. Pipes The flows within pipes must be evaluated for both the private and public storm d ensure that the system is sufficiently sized for the 100-yr storm eve To capacities of the storm drain pipes, Manning's Equation (shown bel · 5 Q _ 1.486 A3 S2; P --*z* z n P3 Where: Op = volumetric flow in the pipe in cfs n = unitless Manning's roughness coefficient = 0.013 (t A = cross-section area of flow in ft2 P = wetted perimeter of flow in ft S = slope of pipe in ft/ft For the private storm drain system, the flows per pipe were first d · ined using the Modified Rational Method described in a previous section. Once the flows for each section of pipe were determined, Manning's Equation was used to check that the pipes would flow as open channels (no pressure head) during the 100-yr storm event. See Appendi>s,~A for the layout of the private storm drain pipes. The following table summarizes the fh:;>w;deptn in each conduit. 1.80% 0.30 1.96% ro.22 2.00 P4 1.58% 0.25 1.80 PS 17.4 1.44% 8 0.30 1.48 0.011 1.68 1.71 P6 117 4.08% 6 0.14 0.97 0.011 1.09 1.34 P7 38.6 0.40% 10 0.39 1.61 0.011 1.31 1.64 P8 11.7 0.70% 12 0.76 0.64 2.12 0.012 2.99 3.23 7 2888 LOKER AVE EAST STE. 303 111 CARLSBAD III CA • 92010 111 (760) 603-1900 TerramarEngineering.com • lnfo@TerramarEng.com MAR CONSULTING ENGINEERS For Table 2: L = pipe length S = pipe slope . Q100 = 100-yr flow going to pipe as determined by the Modified Rational Methotl d = pipe diameter ·· .. Ax = cross-sectional area of flow within pipe P = wetted perimeter of flow within pipe h = depth of flow within pipe n = Manning's roughness coefficient= 0.011 for PVC or 0.012 for RCP 01u11 = full conduit flow The following table outlines the results from the hydraulics analysis for the public pipes (Gitt, MS4). 1.8 12.6 ft2 4.7 12.6 ft 0.013 0.01 ft/ft 143.6 cfs 155.1 cfs 1.2% 2.1% 0.8% For Table 3: d = pipe diameter in inches A = full pipe cross-section in ft 2 = TTd2/4 P = full pipe perimeter in ft = TTd Q1 = full pipe volumetric flow in cfs > Om = max pipe volumetric flow in cfs = 1.08Qr''.::'.~ · Oe = 100-yr runoff for the existing condition§:~·1':92, cfs On = 100-yr runoff for the proposed conditiqrf= 2.99 cfs 6.Q = increase in runoff= 1.07 cfs The slopes and dimensions of the city storm drain pipes ar~feferenced from Project No. 2-13 (Plans & Profiles for the Sewer, Water, & Storm Drain Improvements in Holiday Manor), Drawing No. 135-5, dated 09/06/1962. ;" 8 2888 LOKER AVE EAST STE. 303 ill CARLSBAD ill CA ® 92010 e (760) 603-1900 TerramarEngineering.com ® lnfo@TerramarEng.com TERR MAR CONSULTING ENGINEERS CONCLUSIONS This report quantifies a 1.07 cfs increase in peak flow discharge rates associated with the proposed development of the subject property (pre-development peak flow rate= 1.92 cfs, p&st- development peak flow rate= 2.99 cfs). This increase constitutes a 2.3% and 0.8% increase in the flow in the downstream 18" and 48" diameter storm drain pipes, respectively, which sh'ould not have a significant impact on the City storm drain infrastructure. "I hereby declare that I am the engineer of work for this project. That I have exercise ·. ·. responsible charge over the design of the project as defined in section 6703 of Business q Professions code and that the design is consistent with current standards. I understand tha · · check of project drawings and specifications by the City of Carlsbad is confined to a revie and does not relieve me, as engineer of work, my responsibilities for project desigr# Hydro/ogic/Hydraulic Drainage Report of the Highland James Subdivision in Car/sbad,;}f ·. ··. prepared by me (or under my supervision) in accordance with the criteria established by t Diego County Hydrology Manual, the Carlsbad BMP Design Manual and in accorda, standard practices". 9 2888 LOKER AVE EAST STE. 303 • CARLSBAD o CA • 92010 • (760) 603-1900 TerramarEngineering.com • lnfo@TerramarEng.com TERR MAR CONSULTING ENGINEERS APPENDIX A Pre-Development Conditions Exhibit (with Location Map) Post-Development Conditions Exhibit 2888 LOKER AVE EAST STE. 303 o CARLSBAD 4111 CA • 92010 ® (760) 603-1900 TerramarEngineering.com 4111 lnfo@TerramarEng.com I I ? ? I" l ~~~:;· =_ -~ :;:::""'" ~ :::::::::::;_:---/ .,,,,.,,,,,,..,,...,".., »., .,,,_.,,.,,..""""" -----~-------------------- -v_ -G --~· .... /... ..,,!.-·- ~-~ -~/'----_--. ---·" ---------------------,,,. er -~--~ :ll,S~ ~ 1_: 7::-.::;:.;== ~ -~ -_1_ -~~t~-~-~---------"·----I 1 ~'>=L'Q.::::--'i -- L l f I .... h-.," y ~,, -, ... - _I I - '- I I 1,.~~ ... I I I , .._... I I \ I \Jj \I ·~ .. r=rt·'-11 '__ ~---------__ -I'-/.____,_ EX ---' --1 DWY = ,. EX ~d: ~"' DWY ~ ,_ --6 II s~~\",,,.-- I Ill I (V LEGEND (E): EXISTING, (N): NEW I PROPOSED (E) PROPERTY LINE ---(E) MAJOR CONTOUR ., .. ,,,,,______ ,_,_ .. ,,,.,., ,.,.,._,.,___ (E) MINOR CONTOUR ---12" SD -(E) 12" RCP STORM DRAIN PIPE ---18" SD -(E) 18" RCP STORM DRAIN PIPE ---48" SD-(E)48"RCPSTORMDRAINPIPE § (E) STORM DRAIN INLET (E) RETAINING WALL --(E)AC PAVEMENT ~ (E)BUILDING (E) CONCRETE tf'.{D (E)VEGETATION ---DRAINAGEDIRECTION -OMA BOUNDARY (N) SD PIPE. SEE REPORT FOR DNl!Et,llill!J!l,IS. 'E ~~-I' ~ X, $WO = 1-92 els · 'l,"~7'" · f :·'·'< ' 'I ~ • J O SD • ' --,-' ' · ·, ·' .. J '" ' """140 AMES-D -48" S /. ---····"'-"', -=~7 EX ,e:J::--=~-10" S'S' RIVE . -·1·--A I "'·· --... -.. · DWY -" . --·2·""' -·-----00 .j ,,,.. "'1"8" SD-L -------·---~1":x J "" ,-, I 48"•.n) \ ~.""-' -IQ" SS _/ -48" SD- ,-~ • 10"- -'~" ~ --- I .-.. PROPOSED SITE er 0 @ ~ (!) :i: VICINITY MAP NTS PRE-DEVELOPMENT CONDITION DRAINAGE AREA MAP _,....,,...,., •• ~,,,...,..;« 1::::--- L.,,,. I ... ~. :: "' ._, -- ·bv·· ~: --...:.: _......... ...,,,.~,,.V.==~ """"'""··- .. ·····"=·· "", ''"'"''' ''""--· ·····-·-~ F@QI)- r··· .... ..... - ,;\ \ 5\~ ... ··~ \' ...• l.. I ,J "· ~ ... 11 ''l >.,,. EX~·~ 1 9wv = ·~ EX~ 'Vl...l>"t:;:::! DWY L '\ ----\ \ ~.. '' .. · .. " ··£ .... • ~ PUBLIC 18" SD Q1 ' o --48" SD-_ ,, · 00=2.99cfs , ~··. -~·u~!'-ii;;,r-_ JAtE'~DRIVE4 ~" _:!II /_ 48" SD---48'' SJJ,~ --48" SD- ~-~ r - "',_«, W "h"'".W ~ ~ ' \ LEGEND (E): EXISTING, (N): NEW I PROPOSED (E) PROPERTY LINE ---(E) MAJOR CONTOUR ·--·····-(E) MINOR CONTOUR (N) MAJOR CONTOUR (N) MINOR CONTOUR (E) CURB & GUTIER (E) RETAINING WALL (N) RETAINING WALL ------------(N) EARTHEN SWALE FLOWLINE .@BJ iYiM; Nii if@&&lf..RW (N)RIPRAPSWALE ti (N) SD CATCH BASIN ~ ..,,. (N)BMPSIGN (N) TREE WELL 10' CANOPY (N) TREE WELL 5' CANOPY LOCAL DEPRESSION ~ L,,,""',-, . ..c• (E)CONCRETE ~ (N) BIORETENTION BMP -----SD h~i~~:i~~SSEE REPORT FOR ---DRAINAGE DIRECTION ~ ~-(N)BUILDING ~ (N) HARDSCAPE --DMABOUNDARY ---12" SD -(E)12"RCPSTORMDRAINPIPE ---18" SD -(E)1B"RCPSTORMDRAINPIPE DMALABEL ---48" SD-(E)4B"RCPSTORMDRAINPIPE § (E) STORM DRAIN INLET OMA AREA(SF} TYPE/NOTES N1a 1,635 SF DRAINS TO STRUCTURAL BMP-BIORETENTION BASIN PR-1A N1b 11,917 SF DRAINS TO STRUCTURAL BMP-BIORETENTION BASIN PR-1A N1c 605SF SELF-MITIGATING AREA (SMA-1) N2a 1,669 SF DRAINS TO STRUCTURAL BMP-BIORETENTION BASIN PR-1B N2b 11,917 SF DRAINS TO STRUCTURAL BMP -BIORETENTION BASIN PR-1 B N2c 484SF SELF-MITIGATING AREA (SMA-2) N3 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-1) N4 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-2) NS 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-3) N6 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-4) N7 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-5) NB 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-6) OMA EXHIBIT NOTES: 1. ENTIRE SITE IS UNDERLAIN WITH HYDROLOGIC SOIL GROUP B 2. THE APPROXIMATE DEPTH TO GROUNDWATER IS GREATER THAN 15 FT 3. THE SITE DOES NOT CONTAIN ANY EXISTING NATURAL HYDROLOGIC FEATURES (WATERCOURSES, SEEPS, SPRINGS, WETLANDS) 4. THE SITE DOES NOT CONTAIN ANY CRITICAL COARSE SEDIMENT YIELD AREAS TO BE PROTECTED 5. PROPOSED DESIGN FEATURES AND SURFACE TREATMENTS USED TO MINIMIZE IMPERVIOUSNESS INCLUDE TREE WELLS (BMP SD-1) AND IMPERVIOUS AREA DISPERSION (BMP SD-5) SUCH THAT EACH OF THE DMAs N3 THOURGH NB MAY BE CONSIDERED SELF RETAINING AREAS VIA QUALIFYING SITE DESIGN BMPS POST-DEVELOPMENT CONDITION DRAINAGE AREA MAP TERR MAR CONSULTING ENGINEERS APPENDIX B NRCS Web Soil Survey Hydraulic Soil Group Hydrology Calculations Hydraulics Calculations 2888 LOKER AVE EAST STE. 303 • CARLSBAD • CA • 92010 e (760) 603-1900 TerramarEngineering.com • lnfo@TerramarEng.com • ' '' • • • I -• • • • ,11111111111•11·· .I ••• I • .• ;-1 , .• ~I , .• f , .• I • .• •I • .• I 11 , .,,. ,,--/\ . • .( ". ' //,/,,_/ \ I • ~, ,,...--. V / / ': / V ~ / ~ / \~ ,._ / \() ,..,.. .. fi ' .. ,/ ... . \ ..,. .// ''t / _,.// \ -'\ \,. //' . -~~ ~>/ / \ -: . ~-~ ~ ~ -°'\ -\ -.. \ ... ;.-\ - • ,, \ 1;:t • "' \ \ /' ~ -.;, \\\ /,/ -~ $~. : -' // ,I i#li..,.,!S:·" \. ·, , ..,:, ~•--I \.· --\ ~ ... ·• .. \ • z .... , •t .• • I .• • I •t :.1• .. I •• ~ . . . ~·:· I • I• I • t t • .. I• t .. . .. . .. -.. . . . Hydrologic Soil Group-San Diego County Area, California Hydrologic Soil Group Carlsbad gravelly loamy B 0.2 sand, 15 to 30 percent slopes MIC Marina loamy coarse B 0.5 sand, 2 to 9 percent slopes MIE Marina loamy coarse B 0.4 sand, 9 to 30 percent slopes Totals for Area of Interest 1.1 Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (AID, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (AID, B/D, or CID), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. USDA Natural Resources ""ffl Conservation Service Web Soil Survey National Cooperative Soil Survey 21.4% 40.7% 37.9% 100.0% 4/7/2016 Page 3 of 4 Speck Carlsbad 100-yr Hydrology Calculations Site Parameters ~ N2c I 0.25 2.60lin 11917 484 N2a + N2b + N2c N3 3571 N4 3571 NS 3571 N6 3571 N7 3571 N8 3571 49653 0.274 0.011 0.323 0.082 0.082 0.082 0.082 0.082 0.082 1.14 4545 0.38 0 0.00 4906 0.35 0.48 0.014 0.121 194 2202 0.62 0.65 0.013 0.018 97 1782 0.50 0.57 0.013 0.010 143 2309 0.65 0.67 0.013 0.014 90 1798 0.50 0.58 0.013 0.008 118 2172 0.61 0.65 0.013 0.010 123 1765 0.49 0.57 0.013 0.013 139 22146 Appendix B.2 100 4.89 6.85 0.323 1.05 50 0.072 0.26 4.0 941 7,91 0.131 s.01 6.831 1.051 31 0.2101 0.131 7.9 97 6.55 5.76 0.082 0.31 50 0.063 0.20 1.5 100 9.46 4.54 0.047 0.12 50 0.050 0.13 1.0 431 1.71 0.271 9.71 4.461 0.211 101 0.1121 0.131 1.7 90 6.56 5.75 0.082 0.32 50 0.067 0.22 1.4 100 9.97 4.39 0.051 0.13 50 0.053 0.14 0.9 181 1.61 0.121 10.11 4.351 0.211 101 0.1151 0.131 1.6 100 8.18 4.99 0.043 0.14 50 0.052 0.14 1.0 231 1.81 0.141 8.31 4.931 0.261 101 0.1221 0.151 1.8 100 8.72 4.79 0.057 0.16 50 0.052 0.14 1.1 391 1.91 0.221 8.91 4.711 0.221 101 0.1091 0.121 1.9 Page 1 of 1 Appendix B.3 Speck Carlsbad 100-yr Hydraulics Calculations Confluence Schematic J N2a+ N2b +N2c Pl N7 on I P3 I I N8 P2 I N6 I QT2 P4 NS QT3 PS N4 QTS I P8 I Out I I Nla+Nl b+Nlc P6 QT4 P7 N3 - P3 N2a, N2b, N2c, 16.8 1.96% 4.75 6.85 1.36 6.2 8 204 0.40 0.22 1.19 0.011 1.36 2.00 N7,N8 P4 N2a, N2b, N2c, 41.9 1.58% 4.75 6.85 1.45 5.7 8 223 0.45 0.25 1.30 0.011 1.45 1.80 N6, N7, N8 PS N2a, N2b, N2c, 17.4 1.44% 4.75 6.85 1.68 5.6 8 255 0.54 0.30 1.48 0.011 1.68 1.71 NS, N6, N7, N8 P6 Nla, Nlb, Nlc 117 4.08% 4.75 6.85 1.09 7.6 6 223 0.34 0.14 0.97 0.011 1.09 1.34 P7 Nla, Nlb, Nlc, 38.6 0.40% 4.75 6.85 1.31 3.3 10 222 0.56 0.39 1.61 0.011 1.31 1.64 N3 P8 All 11.7 0.70% 4.75 6.85 2.99 4.7 12 243 0.76 0.64 2.12 0.012 2.99 3.23 NS 6.56 5.75 .OT3' 3.1 3.367 in 4 3 ft 1.8 12.6 ft2 0.22 3 3 in 4.7 12.6 ft 4 4 1.55 1.26 cfs 0.013 0.013 0.1 0.1 1.09 1.09 cfs 0.245 0.01 ft/ft 1.0 1.0 142% 116% 52.0 143.6 cfs 0.011 0.011 56.2 155.1 cfs 0.058 0.005 3.4% 1.2% 0.54 0.16 5.8% 2.1% 0.59 0.17 2.3% 0.8% Page 1 of 1