Loading...
HomeMy WebLinkAboutPRE-0480-2022 (1150 Laurel) - Prelim Hydro Report Laurel Creek Garden Apartments 1150 Laurel Lane San Luis Obispo, CA 93401 AV Job Number 181058 July 15, 2022 Preliminary Hydrology Report and Post Construction Stormwater Control Plan Prepared for: Patrick Smith 1150 Laurel Creek, LLC San Luis Obispo, CA 93401 Prepared By: Ashley & Vance Engineering, Inc. 1229 Carmel San Luis Obispo, CA 93401 805.545.0010 Laurel Creek Garden Apartments Stormwater Control Plan-181058 Page | 1 July 15, 2022 Attn: Patrick Smith 1150 Laurel Creek San Luis Obispo, CA 93401 Subject: Laurel Creek Garden Apartments Re: Preliminary Stormwater Control Plan-Performance Requirements 1-4 Patrick: Please find enclosed the Stormwater Control Plan for the above-referenced project addressing performance requirements 1-4. Calculations for the volume of water required for treatment and infiltration were prepared using the Post-Construction Stormwater Management Requirements for Development Projects in the Central Coast Region. As detailed in the project conclusion, this project is well suited to meet the City of San Luis Obispo and the Water Board’s goals for stormwater mitigation. Please contact me for any clarifications or supporting information you need concerning this plan. Regards, Juan Alvarez Kathleen Allwine, PE Principal Engineer Laurel Creek Garden Apartments Stormwater Control Plan-181058 Page | 2 Contents Introduction and Background ....................................................................................................................... 3 Site Location Description .............................................................................................................................. 3 Vicinity Map .............................................................................................................................................. 3 Existing Conditions .................................................................................................................................... 3 Proposed Project ....................................................................................................................................... 4 Water Quality Analysis .................................................................................................................................. 4 Performance Requirement 1-Site Design and Runoff Reduction ............................................................. 4 Performance requirement 2-Water Quality Treatment ........................................................................... 4 Performance requirement 3-Runoff Retention ........................................................................................ 4 Performance requirement 4-Peak Management ..................................................................................... 5 Conclusion ..................................................................................................................................................... 5 Drainage Exhibits .......................................................................................................................................... 6 Laurel Creek Garden Apartments Stormwater Control Plan-181058 Page | 3 Introduction and Background This report intends to address the stormwater requirements set forth by the Regional Water Quality Control Board’s Post-Construction Stormwater Management Requirements for Development Projects in the Central Coast Region and meet the City of San Luis Obispo’s requirements outlined in the Drainage Design Manual. Both these goals will be accomplished by incorporating pervious surfaces and providing retention of stormwater. The pervious surfaces will comprise of a combination of landscaping and pervious pavers. The gravel beneath the pavers will be sized to contain the 95th events. This project will result in the creation and replacement of over 22,000 square feet of impervious surface area and as a result, is required to meet Performance Requirements 1 through 4. The onsite drainage patterns will shift slightly as a result of this project; however, this report will show that the overall effect to the downstream improvements will be negligible. Site Location Description This site is located at the corner of Orcutt Road and Laurel Lane. Vicinity Map Existing Conditions This Project is located at 1150 laurel Lane. The existing site consists of a large parking lot located on both sides of the existing building. The parking lots slope and drain towards the creek. The southern portion Laurel Creek Garden Apartments Stormwater Control Plan-181058 Page | 4 of the site drains to an existing stormdrain. The site does not receive runon from adjacent lots and does not contribute runon to adjacent lots. Proposed Project This project will include the construction 4 new residential structures and 2 new mixed-use buildings. Drainage from most of the site will drain to underground chambers Water Quality Analysis This project creates and replaces over 22,000 square feet of impervious area and thus is required to meet Performance requirements 1 through 4. Performance Requirement 1-Site Design and Runoff Reduction This site minimizes the amount of pervious surface to the maximum extent practicable. Runoff from hardscape and roof drains will outlet to landscaped and pervious paver areas prior to leaving the site. Performance requirement 2-Water Quality Treatment This site is required to treat the 85th percentile storm for the onsite areas. The runoff will be treated via direct infiltration provided by the gravel section located under the pervious pavers or in the underground chambers located around the site. Performance requirement 3-Runoff Retention This project is required to infiltrate the 95th percentile runoff. The onsite chambers will retain and infiltrate the 95th percentile storm onsite. Laurel Creek Garden Apartments Stormwater Control Plan-181058 Page | 5 Performance requirement 4-Peak Management This project will result in a decrease in impervious area and a result will decrease the flow rates leaving the site for all design storms. 2 5 10 25 50 100 Pre Project run off (cfs) 22.33 26.35 39.24 49.22 56.77 64.25 Post Project run off (cfs) 1.95 3.64 18.11 32.26 38.35 42.85 Conclusion This project retains and allows stormwater to infiltrate for the volume of water required by the Regional Water Quality Control Board. Post construction stormwater runoff is reduced for all design storms. Final drainage design should not be limited to the drainage facilities proposed in this Preliminary Hydrology Report if equivalent alternatives are provided that meet the criteria of the DDM and the Central Coast RWQCB Post Construction Stormwater Management requirements. XXXXXXX X X XX X X XXXX 12'' WSDSDSDSDSDW7.5%1.1%8.2%1.4%8.0% 1.1% 1.4%1.6 % 2.4% 2.0% 3.5 %STORM DRA IN IN LET : 2 4 6 . 6 5 INV ER T : 2 4 0 . 2 5 DROP INLET : 2 4 5 . 3 6 INVER T : 2 4 2 .91SDSDCO W EW G GE Ashley&VanceENGINEERING, INC.1413 Monterey StreetSan Luis Obispo, CA 93401 (805) 545-0010 (323) 744-0010www.ashleyvance.comC I V I L S T R U C T U R A LDRAINAGE EXHIBITN18105810/20/20211150 LAUREL LANESAN LUIS OBISPO, CA 93401PRE-CONSTRUCTIONS:\All Jobs\2018 All Jobs\181058 - 1160 Laurel Creek - Braff\02_Working Drawings\Future Buildout\02_Working Drawings\03_EXHIBITS\HYDROLOGY SHEETS-FUTURE.dwg, PRE, Jul 18, 2022 11:58am, Logan 0100100200HORIZONTAL SCALE: 1" = 100' LEGENDPERVIOUS AREA272,500 SFIMPERVIOUS AREA470,000 SFTOTAL AREA742,500 SF(E) HEAD WALL(E) 48" CULVERT(E) STORMDRAIN OUTLET FOR(E) WAREHOUSE ROOF DRAINSAND PARKING LOT DRAINAGE(E) 4' OPENING IN ASPHALT CURBFOR STORMWATER CONVEYANCE,OUTLETS TO CREEK BANK(E) 30" WIDECONCRETE SWALE(E) CATCH BASIN(E) STORMDRAIN COLLECTSROOF DRAINS AND CATCH BASIN(E) STORMDRAIN SDMH(E) WALL PREVENTSSTORMWATER RUN-ONDRAINS TO "ESCORPDRAINAGE CHANNEL"DRAINS TO CREEK XXXXXXX X X XX X X XXXX 12'' WSDSDSDSDSDW7.5%1.1% 8.2%1.4% 8.0%1.1% 1.4%1.6%2.4%2.0% 3.5%STORM DRA IN INLET : 2 4 6 . 6 5 INV ER T : 2 4 0 . 2 5 DROP INLE T : 2 4 5 . 3 6 INV ER T : 2 4 2 . 9 1SDSD CO W EW G GEDN Ashley&VanceENGINEERING, INC.1413 Monterey StreetSan Luis Obispo, CA 93401 (805) 545-0010 (323) 744-0010www.ashleyvance.comC I V I L S T R U C T U R A LDRAINAGE EXHIBITN18105807/18/20221150 LAUREL LANESAN LUIS OBISPO, CA 93401POST-CONSTRUCTIONS:\All Jobs\2018 All Jobs\181058 - 1160 Laurel Creek - Braff\02_Working Drawings\Future Buildout\02_Working Drawings\03_EXHIBITS\HYDROLOGY SHEETS-FUTURE.dwg, POST, Jul 18, 2022 12:02pm, Logan 0100100200HORIZONTAL SCALE: 1" = 100' LEGENDPERVIOUS AREA76,855 SFIMPERVIOUS AREA665,645 SFTOTAL AREA742,500 SFSTORMWATER COMPLIANCE FOR POST DEVELOPED PROJECTRUNOFF (ACCEPTABLE ALTERNATIVES TO THE CONCEPTUALSTORMWATER FACILITIES MAY BE PROPOSED WITH FINALDESIGN):1. THIS SITE IS LOCATED WITHIN THE CITY OF SAN LUISOBISPO.2. THIS SITE IS WITHIN WATERSHED MANAGEMENT ZONE 1.3. THIS PROJECT MUST COMPLY WITH CITY OF SAN LUISOBISPO TIER 4 STORMWATER MITIGATION REQUIREMENTS.4. THE PROPOSED CHAMBERS SHOWN ON THIS EXHIBIT HAVEBEEN PRELIMINARILY SIZED TO DISCHARGE AT A RATE THATDOES NOT EXCEED PRE-PROJECT PEAK FLOWS FOR THE 2THROUGH 10 YEAR STORM EVENTS.5. THIS PROJECT WILL DISTURB MORE THAN ONE ACRE AND ASTORMWATER POLLUTION PREVENTION PLAN IS REQUIREDIDENTIFYING INTERIM STORMWATER RUNOFF CONTROLMEASURES TO BE IN PLACE DURING CONSTRUCTION AND FORFINAL STABILIZATION.PARCEL 3 1 Post Project West 3 Post Project South 5 Post Project Parcel 3 2 (new Pond) 4 (new Pond) 6 parcel 3 95th storage 7 (new Pond) Routing Diagram for HydroCAD_SBUH_Template_SLO Prepared by Ashley & Vance Engineering Inc, Printed 7/18/2022 HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Subcat Reach Pond Link HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 2HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Area Listing (selected nodes) Area (sq-ft) CN Description (subcatchment-numbers) 551,000 98 (1, 3, 5) 10,000 80 (5) 561,000 98 TOTAL AREA Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 3HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points Runoff by SBUH method, Split Pervious/Imperv. Reach routing by Stor-Ind method - Pond routing by Stor-Ind method Runoff Area=118,000 sf 100.00% Impervious Runoff Depth=1.77"Subcatchment 1: Post Project West Tc=10.0 min CN=0/98 Runoff=2.86 cfs 17,448 cf Runoff Area=340,000 sf 100.00% Impervious Runoff Depth=1.77"Subcatchment 3: Post Project South Tc=10.0 min CN=0/98 Runoff=8.25 cfs 50,273 cf Runoff Area=103,000 sf 90.29% Impervious Runoff Depth=1.66"Subcatchment 5: Post Project Parcel 3 Tc=0.0 min CN=80/98 Runoff=3.35 cfs 14,220 cf Peak Elev=102.47' Storage=13,846 cf Inflow=2.86 cfs 17,448 cfPond 2: (new Pond) Discarded=0.05 cfs 11,715 cf Primary=0.00 cfs 0 cf Outflow=0.05 cfs 11,716 cf Peak Elev=103.37' Storage=42,228 cf Inflow=8.25 cfs 50,273 cfPond 4: (new Pond) Discarded=0.10 cfs 25,948 cf Primary=0.00 cfs 1 cf Outflow=0.11 cfs 25,948 cf Peak Elev=103.23' Storage=11,598 cf Inflow=3.35 cfs 14,220 cfPond 6: parcel 3 95th storage Discarded=0.03 cfs 7,534 cf Primary=0.04 cfs 363 cf Outflow=0.07 cfs 7,897 cf Inflow=0.04 cfs 363 cfPond 7: (new Pond) Primary=0.04 cfs 363 cf Total Runoff Area = 561,000 sf Runoff Volume = 81,941 cf Average Runoff Depth = 1.75" 1.78% Pervious = 10,000 sf 98.22% Impervious = 551,000 sf Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 4HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Post Project West Runoff = 2.86 cfs @ 9.96 hrs, Volume= 17,448 cf, Depth= 1.77" Routed to Pond 2 : (new Pond) Runoff by SBUH method, Split Pervious/Imperv., Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Type I 24-hr _95th Rainfall=2.00" Area (sf) CN Description * 118,000 98 118,000 98 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 1: Post Project West Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)3 2 1 0 Type I 24-hr _95th Rainfall=2.00" Runoff Area=118,000 sf Runoff Volume=17,448 cf Runoff Depth=1.77" Tc=10.0 min CN=0/98 2.86 cfs Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 5HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Summary for Subcatchment 3: Post Project South Runoff = 8.25 cfs @ 9.96 hrs, Volume= 50,273 cf, Depth= 1.77" Routed to Pond 4 : (new Pond) Runoff by SBUH method, Split Pervious/Imperv., Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Type I 24-hr _95th Rainfall=2.00" Area (sf) CN Description * 340,000 98 340,000 98 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 3: Post Project South Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)9 8 7 6 5 4 3 2 1 0 Type I 24-hr _95th Rainfall=2.00" Runoff Area=340,000 sf Runoff Volume=50,273 cf Runoff Depth=1.77" Tc=10.0 min CN=0/98 8.25 cfs Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 6HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Summary for Subcatchment 5: Post Project Parcel 3 [46] Hint: Tc=0 (Instant runoff peak depends on dt) Runoff = 3.35 cfs @ 9.87 hrs, Volume= 14,220 cf, Depth= 1.66" Routed to Pond 6 : parcel 3 95th storage Runoff by SBUH method, Split Pervious/Imperv., Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Type I 24-hr _95th Rainfall=2.00" Area (sf) CN Description * 93,000 98 * 10,000 80 103,000 96 Weighted Average 10,000 80 9.71% Pervious Area 93,000 98 90.29% Impervious Area Subcatchment 5: Post Project Parcel 3 Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)3 2 1 0 Type I 24-hr _95th Rainfall=2.00" Runoff Area=103,000 sf Runoff Volume=14,220 cf Runoff Depth=1.66" Tc=0.0 min CN=80/98 3.35 cfs Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 7HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Summary for Pond 2: (new Pond) Inflow Area = 118,000 sf,100.00% Impervious, Inflow Depth = 1.77" for _95th event Inflow = 2.86 cfs @ 9.96 hrs, Volume= 17,448 cf Outflow = 0.05 cfs @ 24.07 hrs, Volume= 11,716 cf, Atten= 98%, Lag= 847.1 min Discarded = 0.05 cfs @ 24.07 hrs, Volume= 11,715 cf Primary = 0.00 cfs @ 24.07 hrs, Volume= 0 cf Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Peak Elev= 102.47' @ 24.07 hrs Surf.Area= 8,004 sf Storage= 13,846 cf Plug-Flow detention time= 1,683.1 min calculated for 11,716 cf (67% of inflow) Center-of-Mass det. time= 1,527.6 min ( 2,249.3 - 721.8 ) Volume Invert Avail.Storage Storage Description #1A 100.00' 11,133 cf 87.25'W x 91.74'L x 5.50'H Field A 44,024 cf Overall - 16,191 cf Embedded = 27,833 cf x 40.0% Voids #2A 100.75' 16,191 cf ADS_StormTech MC-3500 d +Cap x 144 Inside #1 Effective Size= 70.4"W x 45.0"H => 15.33 sf x 7.17'L = 110.0 cf Overall Size= 77.0"W x 45.0"H x 7.50'L with 0.33' Overlap 144 Chambers in 12 Rows Cap Storage= 14.9 cf x 2 x 12 rows = 357.6 cf 27,324 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 100.00'0.250 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 1.00' #2 Primary 102.47'18.0" Vert. Orifice/Grate X 2.00 C= 0.600 Limited to weir flow at low heads Discarded OutFlow Max=0.05 cfs @ 24.07 hrs HW=102.47' (Free Discharge) 1=Exfiltration ( Controls 0.05 cfs) Primary OutFlow Max=0.00 cfs @ 24.07 hrs HW=102.47' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.00 cfs @ 0.22 fps) Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 8HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Pond 2: (new Pond) Inflow Outflow Discarded Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)3 2 1 0 Inflow Area=118,000 sf Peak Elev=102.47' Storage=13,846 cf 2.86 cfs 0.05 cfs 0.05 cfs 0.00 cfs Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 9HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Summary for Pond 4: (new Pond) Inflow Area = 340,000 sf,100.00% Impervious, Inflow Depth = 1.77" for _95th event Inflow = 8.25 cfs @ 9.96 hrs, Volume= 50,273 cf Outflow = 0.11 cfs @ 24.12 hrs, Volume= 25,948 cf, Atten= 99%, Lag= 849.7 min Discarded = 0.10 cfs @ 24.12 hrs, Volume= 25,948 cf Primary = 0.00 cfs @ 24.12 hrs, Volume= 1 cf Routed to Pond 7 : (new Pond) Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Peak Elev= 103.37' @ 24.12 hrs Surf.Area= 17,533 sf Storage= 42,228 cf Plug-Flow detention time= 1,712.6 min calculated for 25,948 cf (52% of inflow) Center-of-Mass det. time= 1,521.3 min ( 2,243.1 - 721.8 ) Volume Invert Avail.Storage Storage Description #1A 100.00' 24,140 cf 137.42'W x 127.59'L x 5.50'H Field A 96,431 cf Overall - 36,081 cf Embedded = 60,351 cf x 40.0% Voids #2A 100.75' 36,081 cf ADS_StormTech MC-3500 d +Cap x 323 Inside #1 Effective Size= 70.4"W x 45.0"H => 15.33 sf x 7.17'L = 110.0 cf Overall Size= 77.0"W x 45.0"H x 7.50'L with 0.33' Overlap 323 Chambers in 19 Rows Cap Storage= 14.9 cf x 2 x 19 rows = 566.2 cf 60,221 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 100.00'0.250 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 1.00' #2 Primary 103.37'18.0" Vert. Orifice/Grate X 3.00 C= 0.600 Limited to weir flow at low heads Discarded OutFlow Max=0.10 cfs @ 24.12 hrs HW=103.37' (Free Discharge) 1=Exfiltration ( Controls 0.10 cfs) Primary OutFlow Max=0.00 cfs @ 24.12 hrs HW=103.37' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.00 cfs @ 0.12 fps) Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 10HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Pond 4: (new Pond) Inflow Outflow Discarded Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)9 8 7 6 5 4 3 2 1 0 Inflow Area=340,000 sf Peak Elev=103.37' Storage=42,228 cf 8.25 cfs 0.11 cfs 0.10 cfs 0.00 cfs Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 11HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Summary for Pond 6: parcel 3 95th storage Inflow Area = 103,000 sf, 90.29% Impervious, Inflow Depth = 1.66" for _95th event Inflow = 3.35 cfs @ 9.87 hrs, Volume= 14,220 cf Outflow = 0.07 cfs @ 23.08 hrs, Volume= 7,897 cf, Atten= 98%, Lag= 792.6 min Discarded = 0.03 cfs @ 23.08 hrs, Volume= 7,534 cf Primary = 0.04 cfs @ 23.08 hrs, Volume= 363 cf Routed to Pond 7 : (new Pond) Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Peak Elev= 103.23' @ 23.08 hrs Surf.Area= 5,089 sf Storage= 11,598 cf Plug-Flow detention time= 1,668.1 min calculated for 7,897 cf (56% of inflow) Center-of-Mass det. time= 1,482.9 min ( 2,199.8 - 716.9 ) Volume Invert Avail.Storage Storage Description #1A 100.00' 7,130 cf 65.75'W x 77.40'L x 5.50'H Field A 27,990 cf Overall - 10,164 cf Embedded = 17,826 cf x 40.0% Voids #2A 100.75' 10,164 cf ADS_StormTech MC-3500 d +Cap x 90 Inside #1 Effective Size= 70.4"W x 45.0"H => 15.33 sf x 7.17'L = 110.0 cf Overall Size= 77.0"W x 45.0"H x 7.50'L with 0.33' Overlap 90 Chambers in 9 Rows Cap Storage= 14.9 cf x 2 x 9 rows = 268.2 cf 17,294 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 100.00'0.250 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 1.00' #2 Primary 103.18'6.0" Vert. Orifice/Grate X 4.00 C= 0.600 Limited to weir flow at low heads #3 Primary 103.44'6.0" Vert. Orifice/Grate X 3.00 C= 0.600 Limited to weir flow at low heads Discarded OutFlow Max=0.03 cfs @ 23.08 hrs HW=103.23' (Free Discharge) 1=Exfiltration ( Controls 0.03 cfs) Primary OutFlow Max=0.03 cfs @ 23.08 hrs HW=103.23' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.03 cfs @ 0.75 fps) 3=Orifice/Grate ( Controls 0.00 cfs) Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 12HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Pond 6: parcel 3 95th storage Inflow Outflow Discarded Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)3 2 1 0 Inflow Area=103,000 sf Peak Elev=103.23' Storage=11,598 cf 3.35 cfs 0.07 cfs 0.03 cfs 0.04 cfs Type I 24-hr _95th Rainfall=2.00"HydroCAD_SBUH_Template_SLO Printed 7/18/2022Prepared by Ashley & Vance Engineering Inc Page 13HydroCAD® 10.20-2d s/n 08034 © 2021 HydroCAD Software Solutions LLC Summary for Pond 7: (new Pond) [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 443,000 sf, 97.74% Impervious, Inflow Depth = 0.01" for _95th event Inflow = 0.04 cfs @ 23.08 hrs, Volume= 363 cf Primary = 0.04 cfs @ 23.08 hrs, Volume= 363 cf, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Pond 7: (new Pond) Inflow Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)0.04 0.038 0.036 0.034 0.032 0.03 0.028 0.026 0.024 0.022 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Inflow Area=443,000 sf 0.04 cfs 0.04 cfs