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HomeMy WebLinkAboutStorm Drainage Calcs ESE CONSULTAN T S ESE Consultants, Inc. 3103 W. Sheryl Drive ENGINEERING - PLANNING • SURVEYING - ENVIRONMENTAL Meridian, Idaho 83642 TEL: 208-424-0020 STORMWATER MANAGEMENT REPORT FOR DAYSPRING SUBDIVISION NO. 2 O��SS�o L e�ctiF — — II ---=-- - - ❑ 9461370 1p F' O run Pxc \ 1 V 9 9 P J `� ❑ W O�If��W �1 \�,N .m -•1 \e \ L = a Anna Leigh Hirning _� -- Professional Engineer Idaho License No. 9461370 LOCATED IN: February 2026 CITY OF MERIDIAN ADA COUNTY, IDAHO TABLE OF CONTENTS SUBJECT SECTION Project Overview 1 Stormwater Management Design 2 Stormwater Equations 3 Primary Conveyance & Stormwater Facility Calculations 4 Intensity-Duration-Frequency Curve 5 Pipe Flow Calculations 6 Drainage Basin Map 7 SECTION 1 - Project Overview Dayspring Subdivision No.2 is a part of a multi-phase mixed use development located in the City of Meridian,Ada County, Idaho.The development is situated along the south side of West Ustick Road, between North Black Cat Road and North McDermott Road. The applicant proposes to develop forty-one (41) single family residential lots with this phase of the project. The development includes the construction of homes and infrastructure to include roads, sidewalks, a stormwater management facility, utilities, and other improvements typical of residential construction. Existing Conditions The project site is currently bound by a single-family residential development to the east(Tricia's Crossing Subdivision) and vacant agricultural land to the west and south. The project site itself is comprised of existing irrigated farmland with several abandoned houses and ancillary buildings, and irrigation delivery ditches. The existing terrain is relatively flat with slopes generally less than one percent. The site slopes down gradient from north to south. Geotechnical Characteristics A Geotechnical Engineering Report was prepared by ALLWEST for the Dayspring Subdivision (f.k.a. Porter Complex Development), dated September 2, 2020. The soils were generally described as surficial lean clay with sand or sandy lean clays with thickness of 1 to 3 feet, overlaying varying layers and mixtures of native silty and sandy soils. Underlying the silty and sandy soils, were generally observed poorly graded gravels with silt and sand to test pit depths of up to 13' bgs. Groundwater Groundwater was observed by ALLWEST during testing in June of 2020 at depths ranging from 7.5' -13.5' bgs. Additional groundwater monitoring performed by Geotek commenced in August 2024 and is ongoing. There are currently 30 active piezometers onsite, and groundwater is observed at depths ranging from 3.2'-12.3' bgs.Geotek's results are summarized in the attached report dated January 2026. Soil Infiltration ALLWEST performed soil infiltration tests at 8 (eight) locations within the project site which resulted in rates ranging from a low of 0.25 in/hr to a high of greater than 20 in/hr.An infiltration rate of 1 in/hr was utilized for design purposes. SECTION 2 - Stormwater Management Design Design Criteria The Stormwater Management Plan described herein has been designed according to the Ada County Highway District Policy Manual. The proposed Stormwater Management Design has been prepared to meet the following requirements and guidelines: ♦ The Rational Method (Q=CiA) has been utilized to calculate peak flows. Runoff coefficients were used per the ACHD Policy Manual. Rainfall intensities were determined using the ACHD adopted Intensity-Duration-Frequency Curve located in Section 5 of this report. Calculations for the requisite time of concentration (Tc) value are enclosed. The overland flow and gutter flow segments of the Tc were calculated based on the equations provided in the ACHD Policy Manual and enclosed within this report for reference. ♦ Pipe flow calculations are provided to demonstrate that the primary stormwater conveyance system is sized to adequately handle stormwater flows based on the 100-yr storm event. ♦ The residential lot grading was designed to drain approximately the front half of the lot towards the street and is included in the stormwater basin calculations. Stormwater that falls within the back of the lots will be retained on site. Yard drains will be installed in the rear yards during home construction and final landscaping to facilitate infiltration of lot drainage. ♦ High groundwater observed through the site necessitated the use of Vertical Sand Filters for the storage and infiltration of the 100-year storm event. An infiltration rate of 1 inch per hour has been used for the design of the vertical sand filters. Sand and grease traps are provided for pretreatment for the vertical sand filters which have been designed so the bottom of facility elevation is higher than the anticipated seasonal groundwater. ♦ Within Phase 2 there are ten (10) proposed vertical sand filters. Basins 2.1, 2.2 and 2.9 are located along the west side of N Dayspring Way, Basin 2.10 is located on the south side of W Deering Dr, Basins 2.4 and 2.6 are located on the southwest side of N Tricia Way, Basin 2.3 is located on the northeast side of N Tricia Way, Basin 2.5 is located on the southeast side of N Bebee River Way, Basin 2.7 is located on the south side of W Aura Dr, and Basin 2.8 is located on the east side of N Barnstead Way. ♦ Phase 2 includes four (4) temporary stormwater retention ponds that have been sized for the 100-year event and designed to provide a minimum of 3' between the bottom of facility elevation and the anticipated seasonal groundwater. Basins 2.11 &2.12 are located at the west end of N Dayspring Way and Basins 2.13 and 2.14 are located at the south end of N Barnstead Way. The temporary stormwater retention ponds are located within proposed temporary storm drain easements and will be removed and replaced with the development of future phases. SECTION 3 - Stormwater Equations Stormwater Conveyance (ACHD Policy Manual 8011.2) Q = iA where= Q = Discharge rate (ofs) C _ Coefficient of Runoff(dimensionless) i = Rainfall intensity (in/hr) for a duration equal to the time of concentration (Tc) over the contribuking area and for the design frequency. A = Site area (acres) Tc = Time of concentration Coefficient of Runoff(ACHD Policy Manual 8011.2.1) Estimated Runoff Coefficients for Various Surfaces Type of Surface Runoff Coefficients "C" Business Downtown areas 0.70-0.95 Urbannelghtwhoods 0.50-0.70 Residential Single Family 0.35.0.50 Multifamily 0.60.0.75 Residential1Fural) 0.25.0.40 ApartmentDwellingAreas 0.70 Industrial and Commerclal Light areas 0.80 Heavy areas 0.90 Parks,{emeterles 0.10-0.25 Playgrounds 0.20-0.35 Railroad yard areas 0.20.0.40 UnlmpFaved areas 0.10.0.30 StFBBtS Asphalt 0.95 Gan{Fete 0.95 Brick 0.95 Roofs 0.95 Grant 0.75 Fields:Sandy sail Soll Type Slope A B { Flat 0.2% 0.04 0.07 0.11 0.1S Average,2.6% 0.09 0.12 0.15 4.20 Steep' % 0.13 0.18 0.2n :'.?a Adapted from ASCE Design Storm Runoff Volume (ACHD Policy Manual 8011.3.2) V=CiA(3600) V: Design storm runoff volume required for storage C: Coefficient of Runoff is Rainfall Intensity per IDF Curve 1-hour 100-year storm event, i=0.96 1-hour 2-year storm event, i=0.26 A: Total catchment area(acres) Time of Concentration Tc=Tc-G+Tc-s Tc : Total time of concentration LG Tc-c — 60 • VG Tc-G : Gutter time of concentration LG : Length of gutter flow VG : Gutter flow velocity VG=KukSP0.5 Ku : Empirical coefficient(3.281) k : Intercept coefficient(0.619) Sp : Slope (percent) 0.007(nL)08 TC-S (p,)0.5S0.4 Tc-s : Overland time of concentration L : Length of overland(sheet) flow n : Manning's Roughness Coefficient(0.24) Pz : 2-year 24-hour rainfall(1.2 in.) S : Slope (ft/ft) Manning's Roughness Coefficient(ACHD Policy Manual 8011.5.3) Typical Range of Manning's Coefficient (n) for Channels and Pipes, Cpnd411; Matoridl Man:3ing's n' Closw conIJUItS Concrete pipe 0-010- 0.015 O M P 0-011 -0.037 Plastic (Smooth) 0.015 Plastic (cone aw) 0-018-0-025 PavamsnUgutter sections 0-012-0-016 rngi ll Open C han neK5 Concrete 0-011 -0.015 Rubble or riprap 0-020- 0.035 Vegetation 0.020-0.1 SO Base Soil 0-016 - 0.025 Rock Cut 0.025 - 0.045 Natural channels(minor streams, ROD mdth at flood stage <30 m(100 h)] Fairly regular sacs 0.025 - 0.050 Irr&gclar 9Ocbon with p6019 0 040 - 0.150 Lower values are usually For well-constructed and maintained{snnootherl pipes and channels Table 3-2. Manning's Roughness Coefficient(n)for Overland Sheet Flow,`' Surface Description n Smooth asphalt 0.011 Smooth concrete 0.012 Ordinary concrete lining 0.013 Good wood 0.014 Brick with cement mortar 0.014 Vitrified clay 01015 Cast iron 0.015 Corrugated metal pipe 0,024 Cement rubble surface M24 Fallow (no residue) 0.05 Cultivated soils Residue cover s 20% 0_06 Residue cover> 20°fo 0.17 Range(natural) 0_13 Grass Short grass prairie 0.15 Dens@ grasses 0.24 Bermuda grass 0.41 Woods' Light underbrush 0.40 Dense underbrush 4_$4 -When selecting n, consider cover to a height of about K mm. This is only part of the plant cover that will obstruct sheet Flow, SECTION 4 Primary Conveyance & Stormwater Facility Calculations BASIN CATCHMENT AREA 2.1 BASIN CHARACTERISTICS Basin Area: 0.92 1 Acres Runoff Coefficient,C: 0.60 Rainfall Intensity,is 0.96 in/hr Infiltration Rate,r: 1.0 in/hr TIME OF CONCENTRATION Overland Flow Gutter Flow Sub-Catchment Length,L Slope,s Tc-s Elev 1 Elev 2 Length,LG Slope,Sp Gutter Velocity,VG Tc-G Total Tc (ft) M (min.) (ft) (ft) (ft) M (ft/sec) (min.) (min.) 2.1A 14.5 2.00 5.0 2539.5 2537.9 225 0.72 1.73 2.2 7.1 2.16 12.0 2.00 4.3 2539.2 2537.9 174 0.78 1.79 1.6 5.9 CONVEYANCE Sub-Catchment C Area,A i2 i2s i100 Q2 Q25 Q100 (acres) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs) 2.1A 0.60 0.52 0.69 1.85 2.58 0.22 0.58 0.80 2.113 0.60 0.39 0.69 1.85 2.58 0.16 0.43 0.60 Total 0.91 0.38 1.01 1.41 SAND&GREASE TRAP No.of S&G Baffle Throat Vault Size Traps Spacing Width Throat Area Flow Rate, Q100 Throat Velocity, V Flow Rate Check Velocity Check (galon) (inch) (inch) 2 (ft) (cfs) (fps) Q100<3.33 cfs V<0.5 fps 1000 20 48 6.67 1.41 0.21 TRUE TRUE STORAGE VOLUMES(Vertical Sand Filter) Chamber 1 Req'd Volume, V2-YR L1 W1 d1 Pipe Volume,VP1 Volume,VR1 Storage Volume,V1 (ft) (ft) (ft) (ft) (ft3) (ft3) (ft3) 517 80 3 5 140 424 564 Chamber 2 Rock Void Design Infiltration Bed Infiltration Time to Drain Req'd Volume,V100-YR L2 W2 d2 Pipe Volume,VP2 Volume,VR2 Rate,I Volume,V2i Storage Volume,V2 90% (ft) (ft) (ft) (ft) (ft) (ft) (in/hr) (ft') (ft) (hrs) 1,908 80 5 62 1,815 1.0 77 1,954 22.39 BASIN CATCHMENT AREA 2.2 BASIN CHARACTERISTICS Basin Area: I 1.19 Acres Runoff Coefficient,C: 0.60 Rainfall Intensity,is 0.96 in/hr Infiltration Rate,r: 1.0 in/hr TIME OF CONCENTRATION Overland Flow Gutter Flow Sub-Catchment Length,L Slope,s Tc-s Elev 1 Elev 2 Length,LG Slope,Sp Gutter Velocity,VG Tc-G Total Tc (ft) M (min.) (ft) (ft) (ft) M (ft/sec) (min.) (min.) 2.2A 11.0 2.00 4.0 2541.0 2538.8 281 0.77 1.78 2.6 6.6 2.2B 75.0 1.00 24.4 2543.4 2538.8 550 0.84 1.86 4.9 29.4 CONVEYANCE Sub-Catchment C Area,A i2 i2s iloo Q2 Q25 Q100 (acres) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs) 2.2A 0.60 0.46 0.69 1.85 2.58 0.20 0.53 0.74 2.2B 0.60 0.71 0.41 1.09 1.52 0.17 0.46 0.65 Tota 1 1.19 0.37 1.00 1.39 SAND&GREASE TRAP No.of 5&G Baffle Throat Vault Size Traps Spacing Width Throat Area Flow Rate, Q100 Throat Velocity, V Flow Rate Check Velocity Check (galon) (inch) (inch) 2 (ft) (cfs) (fps) Qloo<3.33 cfs V<0.5 fps 1000 20 48 6.67 1.39 0.21 TRUE TRUE STORAGE VOLUMES(Vertical Sand Filter) Chamber 1 Req'd Volume, V2-YR Ll Wl dl Pipe Volume,Vvl Volume,VRl Storage Volume,Vl (ft) (ft) (ft) (ft) (ft3) (ft3) (ft) 668 100 3 5 175 1 530 1 705 Chamber 2 Rock Void Design Infiltration Bed Infiltration Time to Drain Req'd Volume,V100-YR L2 W2 d2 Pipe Volume,VR2 Volume,VR2 Rate,I Volume,V2i Storage Volume,V2 90% (ft) (ft) (ft) (ft) (ft) (ft) (in/hr) (ft') (ft) (hrs) 2,468 100 5 78 2,469 1.0 104 2,651 21.32 BASIN CATCHMENT AREA 2.3 BASIN CHARACTERISTICS Basin Area: I 1.80 Acres Runoff Coefficient,C: 0.50 Rainfall Intensity,is 0.96 in/hr Infiltration Rate,r: 1.0 in/hr TIME OF CONCENTRATION Overland Flow Gutter Flow Sub-Catchment Length,L Slope,s TC-5 Elev 1 Elev 2 Length,LG Slope,Sp Gutter Velocity,VG Tc-G Total Tc (ft) M (min.) (ft) (ft) (ft) M (ft/sec) (min.) (min.) 2.3 27.0 1 1.00 10.8 2543.4 1 2538.E 1 818 1 0.58 1 1.55 8.8 19.6 CONVEYANCE Sub-Catchment C Area,A i2 i25 i100 Q2 Q25 Q100 (acres) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs) 2.3 0.50 1.80 0.5 1.32 1.84 0.45 1.19 1.66 Total 1.80 0.45 1.19 1.66 SAND&GREASE TRAP No.of S&G Baffle Throat Vault Size Traps Spacing Width Throat Area Flow Rate, Q100 Throat Velocity, V Flow Rate Check Velocity Check (galon) (inch) (inch) (ft) (cfs) (fps) Q100<3.33 cfs V<0.5 fps 10" 20 48 6.67 1.66 0.25 TRUE TRUE STORAGE VOLUMES(Vertical Sand Filter) Chamber 1 Req'd Volume, V2-YR Ll W1 d1 Pipe Volume,VRl Volume,VR1 Storage Volume,Vl (ft) (ft) (ft) (ft) (ft3) (ft') (ft) 842 1 131 758 1 888 Chamber 2 Rock Void Design Infiltration Bed Infiltration Time to Drain Req'd Volume,V100-YR L2 W2 d2 Pipe Volume,VR2 Volume,VR2 Rate,I Volume,V2i Storage Volume,V2 90% (ft) (ft) (ft) (ft) (ft) (ft) (in/hr) (ft') (ft) (hrs) 3,110 75 4.5 58 2,947 1.0 138 3,142 20.36 BASIN CATCHMENT AREA 2.4 BASIN CHARACTERISTICS Basin Area: I 1.39 Acres Runoff Coefficient,C: 0.50 Rainfall Intensity,is 0.96 in/hr Infiltration Rate,r: 1.0 in/hr TIME OF CONCENTRATION Overland Flow Gutter Flow Sub-Catchment Length,L Slope,s Tc-s Elev 1 Elev 2 Length,LG Slope,Sp Gutter Velocity,VG Tc-G Total Tc (ft) M (min.) (ft) (ft) (ft) M (ft/sec) (min.) (min.) 2.4 23.0 1 1.00 9.5 2542.1 1 2538.E 1 671 1 0.52 1 1.46 7.6 17.1 CONVEYANCE Sub-Catchment C Area,A i2 i25 i100 Q2 Q25 Q100 (acres) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs) 2.4 0.50 1.39 0.55 1 1.45 2.02 0.38 1.01 1.40 Total 1.39 0.38 1.01 1.40 SAND&GREASE TRAP No.of 5&G Baffle Throat Vault Size Traps Spacing Width Throat Area Flow Rate, Q100 Throat Velocity, V Flow Rate Check Velocity Check (galon) (inch) (inch) (ft) (cfs) (fps) Q100<3.33 cfs V<0.5 fps 10" 20 48 6.67 1.40 0.21 TRUE TRUE STORAGE VOLUMES(Vertical Sand Filter) Chamber 1 Req'd Volume, V2-YR Ll W1 d1 Pipe Volume,VRl Volume,VR1 Storage Volume,Vl (ft) (ft) (ft) (ft) (ft3) (ft') (ft') 651 1 122 581 1 703 Chamber 2 Rock Void Design Infiltration Bed Infiltration Time to Drain Req'd Volume,V100-YR L2 W2 d2 Pipe Volume,VR2 Volume,VR2 Rate,I Volume,V2i Storage Volume,V2 90% (ft) (ft) (ft) (ft) (ft) (ft) (in/hr) (ft') (ft) (hrs) 2,402 70 4.5 54 2,246 1.0 105 2,405 20.59 BASIN CATCHMENT AREA 2.5 BASIN CHARACTERISTICS Basin Area: I 0.79 Acres Runoff Coefficient,C: 0.50 Rainfall Intensity,is 0.96 in/hr Infiltration Rate,r: 1.0 in/hr TIME OF CONCENTRATION Overland Flow Gutter Flow Sub-Catchment Length,L Slope,s Tc-s Elev 1 Elev 2 Length,LG Slope,Sp Gutter Velocity,VG Tc-G Total Tc (ft) M (min.) (ft) (ft) (ft) M (ft/sec) (min.) (min.) 2.5A 75.0 1.00 24.4 2542.3 2540.2 285 0.73 1.73 1 2.7 27.2 2.5B 26.0 1.00 10.5 2541.1 2540.2 80 1.16 2.19 0.6 11.1 CONVEYANCE Sub-Catchment C Area,A iz i25 i100 Q2 Q25 Q100 (acres) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs) 2.5A 0.50 0.56 0.42 1.11 1.55 0.12 0.32 0.45 2.5B 0.50 0.21 0.67 1.79 2.49 0.07 0.19 0.26 Total 0.79 0.19 0.51 0.71 SAND&GREASE TRAP No.of S' Baffle Throat Flow Rate, Vault Size Traps Spacing Width Throat Area Q100 Throat Velocity, V Flow Rate Check Velocity Check (galon) (inch) (inch) (ft) (cfs) (fps) Q100<3.33 cfs V<0.5 fps 1000 20 48 6.67 0.71 0.11 TRUE TRUE STORAGE VOLUMES(Vertical Sand Filter) Chamber 1 Req'd Volume, V2-YR Ll Wl dl Pipe Volume,VPl Volume,VRl Storage Volume,Vl (ft) (ft) (ft) (ft) (ft) (ft3) (ft) 370 40 4.5 5 69 332 401 Chamber 2 Rock Void Design Infiltration Bed Infiltration Time to Drain Req'd Volume,V100-YR L2 W2 dz Pipe Volume,VP2 Volume,VR2 Rate,I Volume,V2i Storage Volume,V2 90% (ft) (ft) (ft) (ft) (ft') (ft') (in/hr) (ft) (ft') (hrs) 1,365 40 5 31 1,348 1.0 57 1,435 21.68 BASIN CATCHMENT AREA 2.6 BASIN CHARACTERISTICS Basin Area: I 1.89 Acres Runoff Coefficient,C: 0.50 Rainfall Intensity,is 0.96 in/hr Infiltration Rate,r: 1.0 in/hr TIME OF CONCENTRATION Overland Flow Gutter Flow Sub-Catchment Length,L Slope,s Tc-s Elev 1 Elev 2 Length,LG Slope,Sp Gutter Velocity,VG Tc-G Total Tc (ft) M (min.) (ft) (ft) (ft) M (ft/sec) (min.) (min.) 2.6A 75.0 1.00 24.4 2542.9 2541.1 283 0.61 1.58 3.0 27.4 2.66 75.0 1.00 24.4 2544.8 2541.1 616 0.59 1.56 6.6 31.0 CONVEYANCE Sub-Catchment C Area,A i2 i2s i100 Q2 Q25 Q100 (acres) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs) 2.6A 0.50 0.5t 0.42 1.11 1.55 0.12 0.31 0.43 2.66 0.50 1.34 0.4 1.04 1.46 0.27 0.70 0.98 Tota 1 1.90 0.39 1.01 1.41 SAND&GREASE TRAP No.of 5&G Baffle Throat Vault Size Traps Spacing Width Throat Area Flow Rate, Q100 Throat Velocity, V Flow Rate Check Velocity Check (galon) (inch) (inch) 2 (ft) (cfs) (fps) Q100<3.33 cfs V<0.5 fps 1000 20 48 6.67 1.41 0.21 TRUE TRUE STORAGE VOLUMES(Vertical Sand Filter) Chamber 1 Req'd Volume, V2-YR L1 W1 d1 Pipe Volume,VP1 Volume,VR1 Storage Volume,V1 (ft) (ft) (ft) (ft) (ft3) (ft3) (ft) 885 75 1 7 4 131 1 788 1 918 Chamber 2 Rock Void Design Infiltration Bed Infiltration Time to Drain Req'd Volume,V100-YR L2 W2 d2 Pipe Volume,VP2 Volume,VR2 Rate,I Volume,V2i Storage Volume,V2 90% (ft) (ft) (ft) (ft) (ft) (ft) (in/hr) (ft) (ft) (hrs) 3,266 75 4 58 3,157 1.0 166 3,380 17.75 BASIN CATCHMENT AREA 2.7 BASIN CHARACTERISTICS Basin Area: I 1.69 Acres Runoff Coefficient,C: 0.50 Rainfall Intensity,is 0.96 in/hr Infiltration Rate,r: 1.0 in/hr TIME OF CONCENTRATION Overland Flow Gutter Flow Sub-Catchment Length,L Slope,s Tc-s Elev 1 Elev 2 Length,LG Slope,Sp Gutter Velocity,VG Tc-G Total Tc (ft) M (min.) (ft) (ft) (ft) M (ft/sec) (min.) (min.) 2.7A 75.0 1.00 24.4 2544.8 2541.8 561 0.54 1.49 6.3 30.7 2.76 75.0 1.00 24.4 2542.9 2541.8 233 0.47 1.39 2.8 27.2 CONVEYANCE Sub-Catchment C Area,A i2 i2s i100 Q2 Q25 Q100 (acres) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs) 2.7A 0.50 1.1u 0.40 1.05 1.47 0.22 0.58 0.81 2.76 0.50 0.59 0.42 1.11 1.55 0.12 0.33 0.46 Total 1.69 0.34 0.90 1.27 SAND&GREASE TRAP No.of 5&G Baffle Throat Vault Size Traps Spacing Width Throat Area Flow Rate, Q100 Throat Velocity, V Flow Rate Check Velocity Check (galon) (inch) (inch) 2 (ft) (cfs) (fps) Qloo<3.33 cfs V<0.5 fps 1000 20 48 6.67 1.27 0.19 TRUE TRUE STORAGE VOLUMES(Vertical Sand Filter) Chamber 1 Req'd Volume, V2-YR Ll Wl dl Pipe Volume,Vpj Volume,VRl Storage Volume,Vl (ft) (ft) (ft) (ft) (ft3) (ft3) (ft) 791 65 1 5 6 113 1 735 1 848 Chamber 2 Rock Void Design Infiltration Bed Infiltration Time to Drain Req'd Volume,V100-YR L2 W2 d2 Pipe Volume,VR2 Volume,VR2 Rate,I Volume,V2i Storage Volume,V2 90% (ft) (ft) (ft) (ft) (ft) (ft) (in/hr) (ft) (ft) (hrs) 2,920 65 6 50 3,022 1.0 106 3,178 24.88 BASIN CATCHMENT AREA 2.8 BASIN CHARACTERISTICS Basin Area: I 1.57 Acres Runoff Coefficient,C: 0.50 Rainfall Intensity,is 0.96 in/hr Infiltration Rate,r: 1.0 in/hr TIME OF CONCENTRATION Overland Flow Gutter Flow Sub-Catchment Length,L Slope,s Tc-s Elev 1 Elev 2 Length,LG Slope,Sp Gutter Velocity,VG Tc-G Total Tc (ft) M (min.) (ft) (ft) (ft) M (ft/sec) (min.) (min.) 2.3A 25.0 1.00 10.1 2542.8 2541.3 260 0.58 1.54 2.8 13.0 2.3B 75.0 1.00 24.4 2542.9 2541.3 321 0.47 1.39 3.8 28.3 CONVEYANCE Sub-Catchment C Area,A i2 i2s i100 Q2 Q25 Q100 (acres) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs) 2.3A 0.50 0.6u 0.63 1.68 2.34 0.19 0.50 0.70 2.3B 0.50 0.97 0.42 1.10 1.53 0.20 0.53 0.74 Total 1.57 0.39 1.04 1.44 SAND&GREASE TRAP No.of 5&G Baffle Throat Vault Size Traps Spacing Width Throat Area Flow Rate, Q100 Throat Velocity, V Flow Rate Check Velocity Check (galon) (inch) (inch) 2 (ft) (cfs) (fps) Q100<3.33 cfs V<0.5 fps 1000 20 48 6.67 1.44 0.22 TRUE TRUE STORAGE VOLUMES(Vertical Sand Filter) Chamber 1 Req'd Volume, V2-YR L1 W1 d1 Pipe Volume,VP1 Volume,VR1 Storage Volume,V1 (ft) (ft) (ft) (ft) (ft3) (ft3) (ft) 735 110 3 5 193 1 583 1 776 Chamber 2 Rock Void Design Infiltration Bed Infiltration Time to Drain Req'd Volume,V100-YR L2 W2 d2 Pipe Volume,VP2 Volume,VR2 Rate,I Volume,V2i Storage Volume,V2 90% (ft) (ft) (ft) (ft) (ft) (ft) (in/hr) (ft') (ft) (hrs) 2,713 110 5 86 2,606 1.0 110 2,801 22.20 BASIN CATCHMENT AREA 2.9 BASIN CHARACTERISTICS Basin Area: I 1.36 Acres Runoff Coefficient,C: 0.60 Rainfall Intensity,is 0.96 in/hr Infiltration Rate,r: 1.0 in/hr TIME OF CONCENTRATION Overland Flow Gutter Flow Sub-Catchment Length,L Slope,s Tc-s Elev 1 Elev 2 Length,LG Slope,Sp Gutter Velocity,VG Tc-G Total Tc (ft) M (min.) (ft) (ft) (ft) M (ft/sec) (min.) (min.) 2.9A 30.0 1.00 11.7 2541.0 2540.2 175 0.49 1.42 2.1 13.8 2.9B 36.0 2.00 10.3 2543.3 2540.2 567 0.56 1.52 6.2 16.5 CONVEYANCE Sub-Catchment C Area,A i2 i25 i100 Q2 Q25 Q100 (acres) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs) 2.9A 0.60 0.34 0.61 1.63 2.28 0.12 0.33 0.47 2.913 0.60 1.02 0.56 1.48 2.07 0.34 0.91 1.27 Total 1.36 0.47 1.24 1.73 SAND&GREASE TRAP No.of 5&G Baffle Throat Vault Size Traps Spacing Width Throat Area Flow Rate, Q100 Throat Velocity, V Flow Rate Check Velocity Check (galon) (inch) (inch) 2 (ft) (cfs) (fps) Qloo<3.33 cfs V<0.5 fps 1000 20 48 6.67 1.73 0.26 TRUE TRUE STORAGE VOLUMES(Vertical Sand Filter) Chamber 1 Req'd Volume, V2-YR Ll Wl dl Pipe Volume,VPl Volume,VRl Storage Volume,Vl (ft) (ft) (ft) (ft) (ft3) (ft3) (ft) 764 70 6 4.5 122 1 707 1 829 Chamber 2 Rock Void Design Infiltration Bed Infiltration Time to Drain Req'd Volume,V100-YR L2 W2 dz Pipe Volume,VP2 Volume,VR2 Rate,I Volume,V2i Storage Volume,V2 90% (ft) (ft) (ft) (ft) (ft) (ft) (in/hr) (ft) (ft) (hrs) 2,820 70 4.5 54 2,813 1.0 131 2,999 19.34 BASIN CATCHMENT AREA 2.10 BASIN CHARACTERISTICS Basin Area: I 0.76 Acres Runoff Coefficient,C: 0.72 Rainfall Intensity,is 0.96 in/hr Infiltration Rate,r: 1.0 in/hr TIME OF CONCENTRATION Overland Flow Gutter Flow Sub-Catchment Length,L Slope,s Tc-s Elev 1 Elev 2 Length,LG Slope,Sp Gutter Velocity,VG Tc-G Total Tc (ft) M (min.) (ft) (ft) (ft) M (ft/sec) (min.) (min.) 2.10A 20.0 1.00 8.5 2543.3 2540.3 531 0.58 1.54 5.7 14.2 2.10E 30.0 2.00 8.9 2541.0 2540.3 146 0.50 1.44 1.7 10.6 CONVEYANCE Sub-Catchment C Area,A i2 i25 i100 Q2 Q25 Q100 (acres) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs) 2.10A 0.70 0.5 0.61 1.61 2.24 0.25 0.66 0.93 2.10B 0.80 0.17 0.68 1.82 2.53 0.09 0.25 0.34 Total 0.76 0.34 0.91 1.27 SAND&GREASE TRAP No.of 5&G Baffle Throat Vault Size Traps Spacing Width Throat Area Flow Rate, Q100 Throat Velocity, V Flow Rate Check Velocity Check (galon) (inch) (inch) 2 (ft) (cfs) (fps) Qloo<3.33 cfs V<0.5 fps 1000 20 48 6.67 1.27 0.19 TRUE TRUE STORAGE VOLUMES(Vertical Sand Filter) Chamber 1 Req'd Volume, V2-YR Ll Wl dl Pipe Volume,VPl Volume,VRl Storage Volume,Vl (ft) (ft) (ft) (ft) (ft3) (ft3) (ft') 514 70 4 4.5 122 1 455 1 577 Chamber 2 Rock Void Design Infiltration Bed Infiltration Time to Drain Req'd Volume,V100-YR L2 W2 dz Pipe Volume,VP2 Volume,VR2 Rate,I Volume,V2i Storage Volume,V2 90% (ft) (ft) (ft) (ft) (ft) (ft) (in/hr) (ft') (ft) (hrs) 1,897 70 4.5 54 1,805 1.0 85 1,944 20.19 TEMPORARY BASIN CATCHMENT AREA 2.11 BASIN CHARACTERISTICS Basin Area: I 0.04 Acres Runoff Coefficient,C: 1 0.50 Rainfall Intensity,is I 0.96 in/hr STORAGE VOLUMES Temporary Basin Req'd Volume Botom Top Area V100YR Depth Area Basin Volume (ft') (ft) (ft') (ft') (ft') 69 0.5 96.00 182.0 69.5 TEMPORARY BASIN CATCHMENT AREA 2.12 BASIN CHARACTERISTICS Basin Area: I 0.04 Acres Runoff Coefficient,C: 1 0.50 Rainfall Intensity,is I 0.96 in/hr STORAGE VOLUMES Temporary Basin Req'd Volume Botom Top Area V100YR Depth Area Basin Volume (ft') (ft) (ft') (ft') (ft') 69 0.5 96.00 182.0 69.5 TEMPORARY BASIN CATCHMENT AREA 2.13 BASIN CHARACTERISTICS Basin Area: 0.07 1 Acres Runoff Coefficient,C: 0.50 Rainfall Intensity,is I 0.96 in/hr STORAGE VOLUMES Temporary Basin Req'd Volume Botom Top Area V100YR Depth Area Basin Volume (ft') (ft) (ft') (ft') (ft') 121 0.5 221.00 347.0 142.0 TEMPORARY BASIN CATCHMENT AREA 2.14 BASIN CHARACTERISTICS Basin Area: I 0.06 Acres Runoff Coefficient,C: 1 0.50 Rainfall Intensity,is I 0.96 in/hr STORAGE VOLUMES Temporary Basin Req'd Volume Botom Top Area V100YR Depth Area Basin Volume (ft') (ft) (ft') (ft') (ft') 104 0.5 221.00 347.0 142.0 SECTION 5 Intensity-Duration-Frequency Curve ACHD Intensity-Duration-Frequency Intensity(inches per hour) Design Storm 2 5 10 25 50 100 Tc(hr) Tc(min) 0.17 10 0.69 1.15 1.48 1.85 2.20 2.58 0.25 15 0.59 0.97 1.22 1.56 1.86 2.18 0.33 20 0.49 0.81 1.01 1.30 1.54 1.81 0.42 25 0.43 0.71 0.89 1.14 1.35 1.58 0.50 30 0.41 0.67 0.85 1.08 1.29 1.51 0.58 35 0.34 0.56 0.70 0.90 1.07 1.25 0.67 40 0.31 0.51 0.64 0.82 0.98 1.15 0.75 45 0.29 0.48 0.60 0.77 0.91 1.07 0.83 50 0.27 0.45 0.56 0.72 0.85 1.00 0.92 55 0.26 0.43 0.54 0.69 0.82 0.96 1 60 0.26 0.43 0.54 0.69 0.82 0.96 2 120 0.16 0.25 0.31 0.39 0.46 0.54 3 180 0.13 0.19 0.23 0.29 0.34 0.40 6 360 0.09 0.12 0.14 0.18 0.21 0.25 12 720 0.06 0.08 0.10 0.12 0.14 0.16 24 1440 0.04 0.06 0.06 0.08 0.09 0.10 Intensity Duration Frequency - 2 3 - -5 -x-10 2.5 -�25 50 2 f 100 L s a v 1.5 c 41 41 �x � 1 c \X�X --x__ 0.5 _ \X�x�x_X-x-x -------------------------- X 0 10 15 20 25 30 35 40 45 50 55 60 120 180 360 720 1440 Duration (minutes) SECTION 6 Pipe Flow Calculations Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.1A TO SDMH 2.1 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.46 Q (cfs) = 1.410 Area (sqft) = 0.35 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.97 Slope (%) = 0.50 Wetted Perim (ft) = 1.49 N-Value = 0.010 Crit Depth, Yc (ft) = 0.51 Top Width (ft) = 1.00 Calculations EGL (ft) = 0.71 Compute by: Known Q Known Q (cfs) = 1.41 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.1 B TO SDCB 2.1A Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.29 Q (cfs) = 0.600 Area (sqft) = 0.19 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.16 Slope (%) = 0.50 Wetted Perim (ft) = 1.14 N-Value = 0.010 Crit Depth, Yc (ft) = 0.33 Top Width (ft) = 0.91 Calculations EGL (ft) = 0.44 Compute by: Known Q Known Q (cfs) = 0.60 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 v 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.2B TO SDCB 2.2A Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.31 Q (cfs) = 0.650 Area (sqft) = 0.21 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.11 Slope (%) = 0.50 Wetted Perim (ft) = 1.18 N-Value = 0.010 Crit Depth, Yc (ft) = 0.34 Top Width (ft) = 0.93 Calculations EGL (ft) = 0.46 Compute by: Known Q Known Q (cfs) = 0.65 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.2A SDMH 2.2 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.46 Q (cfs) = 1.390 Area (sqft) = 0.35 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.92 Slope (%) = 0.50 Wetted Perim (ft) = 1.49 N-Value = 0.010 Crit Depth, Yc (ft) = 0.50 Top Width (ft) = 1.00 Calculations EGL (ft) = 0.70 Compute by: Known Q Known Q (cfs) = 1.39 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.3 TO SDMH 2.3 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.51 Q (cfs) = 1.660 Area (sqft) = 0.40 Invert Elev (ft) = 100.00 Velocity (ft/s) = 4.10 Slope (%) = 0.50 Wetted Perim (ft) = 1.59 N-Value = 0.010 Crit Depth, Yc (ft) = 0.55 Top Width (ft) = 1.00 Calculations EGL (ft) = 0.77 Compute by: Known Q Known Q (cfs) = 1.66 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 Noor 100.50 _ 0.50 100.00 0.00 99.50 —0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.4 TO SDMH 2.4 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.46 Q (cfs) = 1.400 Area (sqft) = 0.35 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.95 Slope (%) = 0.50 Wetted Perim (ft) = 1.49 N-Value = 0.010 Crit Depth, Yc (ft) = 0.50 Top Width (ft) = 1.00 Calculations EGL (ft) = 0.70 Compute by: Known Q Known Q (cfs) = 1.40 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.5B TO SDCB 2.5A Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.19 Q (cfs) = 0.260 Area (sqft) = 0.10 Invert Elev (ft) = 100.00 Velocity (ft/s) = 2.48 Slope (%) = 0.50 Wetted Perim (ft) = 0.90 N-Value = 0.010 Crit Depth, Yc (ft) = 0.21 Top Width (ft) = 0.79 Calculations EGL (ft) = 0.29 Compute by: Known Q Known Q (cfs) = 0.26 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 v 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.5A TO SDMH 2.5 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.32 Q (cfs) = 0.710 Area (sqft) = 0.22 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.26 Slope (%) = 0.50 Wetted Perim (ft) = 1.20 N-Value = 0.010 Crit Depth, Yc (ft) = 0.35 Top Width (ft) = 0.93 Calculations EGL (ft) = 0.49 Compute by: Known Q Known Q (cfs) = 0.71 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 Noor 100.00 0.00 99.50 —0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.6B TO SDCB 2.6A Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.32 Q (cfs) = 0.980 Area (sqft) = 0.22 Invert Elev (ft) = 100.00 Velocity (ft/s) = 4.50 Slope (%) = 1.00 Wetted Perim (ft) = 1.20 N-Value = 0.010 Crit Depth, Yc (ft) = 0.42 Top Width (ft) = 0.93 Calculations EGL (ft) = 0.63 Compute by: Known Q Known Q (cfs) = 0.98 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 Noor 100.00 0.00 99.50 —0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.6A TO SDMH 2.6 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.38 Q (cfs) = 1.410 Area (sqft) = 0.27 Invert Elev (ft) = 100.00 Velocity (ft/s) = 5.13 Slope (%) = 1.00 Wetted Perim (ft) = 1.33 N-Value = 0.010 Crit Depth, Yc (ft) = 0.51 Top Width (ft) = 0.97 Calculations EGL (ft) = 0.79 Compute by: Known Q Known Q (cfs) = 1.41 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 NZ 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDMH 2.6 TO S&G TRAP 2.6 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.46 Q (cfs) = 1.410 Area (sqft) = 0.35 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.97 Slope (%) = 0.50 Wetted Perim (ft) = 1.49 N-Value = 0.010 Crit Depth, Yc (ft) = 0.51 Top Width (ft) = 1.00 Calculations EGL (ft) = 0.71 Compute by: Known Q Known Q (cfs) = 1.41 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.7B TO SDCB 2.7A Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.26 Q (cfs) = 0.460 Area (sqft) = 0.16 Invert Elev (ft) = 100.00 Velocity (ft/s) = 2.80 Slope (%) = 0.50 Wetted Perim (ft) = 1.07 N-Value = 0.010 Crit Depth, Yc (ft) = 0.28 Top Width (ft) = 0.88 Calculations EGL (ft) = 0.38 Compute by: Known Q Known Q (cfs) = 0.46 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 v 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.7A TO SDMH 2.7 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.44 Q (cfs) = 1.270 Area (sqft) = 0.34 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.79 Slope (%) = 0.50 Wetted Perim (ft) = 1.45 N-Value = 0.010 Crit Depth, Yc (ft) = 0.48 Top Width (ft) = 0.99 Calculations EGL (ft) = 0.66 Compute by: Known Q Known Q (cfs) = 1.27 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.8B TO SDCB 2.8A Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.27 Q (cfs) = 0.740 Area (sqft) = 0.17 Invert Elev (ft) = 100.00 Velocity (ft/s) = 4.30 Slope (%) = 1.00 Wetted Perim (ft) = 1.09 N-Value = 0.010 Crit Depth, Yc (ft) = 0.36 Top Width (ft) = 0.89 Calculations EGL (ft) = 0.56 Compute by: Known Q Known Q (cfs) = 0.74 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 v 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.8A TO SDMH 2.8 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.39 Q (cfs) = 1.440 Area (sqft) = 0.28 Invert Elev (ft) = 100.00 Velocity (ft/s) = 5.07 Slope (%) = 1.00 Wetted Perim (ft) = 1.35 N-Value = 0.010 Crit Depth, Yc (ft) = 0.51 Top Width (ft) = 0.98 Calculations EGL (ft) = 0.79 Compute by: Known Q Known Q (cfs) = 1.44 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDMH 2.8 TO S&G TRAP 2.8 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.47 Q (cfs) = 1.440 Area (sqft) = 0.36 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.95 Slope (%) = 0.50 Wetted Perim (ft) = 1.51 N-Value = 0.010 Crit Depth, Yc (ft) = 0.51 Top Width (ft) = 1.00 Calculations EGL (ft) = 0.71 Compute by: Known Q Known Q (cfs) = 1.44 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.9B TO SDCB 2.9A Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.44 Q (cfs) = 1.270 Area (sqft) = 0.34 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.79 Slope (%) = 0.50 Wetted Perim (ft) = 1.45 N-Value = 0.010 Crit Depth, Yc (ft) = 0.48 Top Width (ft) = 0.99 Calculations EGL (ft) = 0.66 Compute by: Known Q Known Q (cfs) = 1.27 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.9A TO SDMH 2.9 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.52 Q (cfs) = 1.730 Area (sqft) = 0.41 Invert Elev (ft) = 100.00 Velocity (ft/s) = 4.17 Slope (%) = 0.50 Wetted Perim (ft) = 1.61 N-Value = 0.010 Crit Depth, Yc (ft) = 0.56 Top Width (ft) = 1.00 Calculations EGL (ft) = 0.79 Compute by: Known Q Known Q (cfs) = 1.73 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 _ 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.10B TO SDCB 2.10A Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.22 Q (cfs) = 0.340 Area (sqft) = 0.13 Invert Elev (ft) = 100.00 Velocity (ft/s) = 2.63 Slope (%) = 0.50 Wetted Perim (ft) = 0.98 N-Value = 0.010 Crit Depth, Yc (ft) = 0.25 Top Width (ft) = 0.83 Calculations EGL (ft) = 0.33 Compute by: Known Q Known Q (cfs) = 0.34 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Dec 22 2025 100 YR - SDCB 2.10A TO S&G TRAP 2.10 Circular Highlighted Diameter (ft) = 1.00 Depth (ft) = 0.44 Q (cfs) = 1.270 Area (sqft) = 0.34 Invert Elev (ft) = 100.00 Velocity (ft/s) = 3.79 Slope (%) = 0.50 Wetted Perim (ft) = 1.45 N-Value = 0.010 Crit Depth, Yc (ft) = 0.48 Top Width (ft) = 0.99 Calculations EGL (ft) = 0.66 Compute by: Known Q Known Q (cfs) = 1.27 Elev (ft) Section Depth (ft 102.00 2.00 101.50 1.50 101.00 1.00 100.50 0.50 100.00 0.00 99.50 -0.50 0 1 2 3 Reach (ft) SECTION 7 Drainage Basin Map DAYSPRING \ \ SUBDIVISION NO. 1 \ \ \ l \ 0"' \ W gOW1A 2c \ \ BLOCK 07 \ \ 2.1 o.s2 0 NOT A PART \ \ asv 113 \ \ BLOCK 08 16C,/ W FAR ROUGH DR \ \ 2.2 2.2A'' 22B I \ \ 3 BLOCK 10 FUTURE ` 2 3 4 5 6 7 8 9 10 15C AMENITY SITE 2.9 _ 1C 2.3 I 1C 36 a .80 o W CROSSRIDGE ST BLOCK 09 12/ / 2.4 3 2 29A 2.12Q��� / 4 5 1 6 7 8 9 10 11 12 04 0 �' 3 / 2.8 ti oc _ P%r 4 / .57 14C •\ �92 04 0 2.9B', BLOCK 15 � 010� 1C 13C / I 2.10 1C BLOCK 14 3 20 2J 2s 19 18 17 2.6 16 15 14 \ 2.7e a � oss o� .76 0 21CB� \\ 2.8A 1.69 a .89 ac - -- OR 5 �28g ` 2 - — AURA 040E \\ gNN� 210A A �m� /s7 '10 C �� iI — iC 9 6 z _ ll' ia'- o 0 72.sA 2 3 2 7 1C BLOCK 13 BLOCK 12 2 I z I I BLOCK 11 _ 2.14 2.5 2.13 .06 0 .07 o 79 0 ALLEY F(PUBLIC) FUTURE PHASE I I I I� I FUTURE PHASE I I LEGEND BASIN BOUNDARY LINE 21 BASIN NUMBER s2 o BASIN AREA FEET SUB—BASIN BOUNDARY LINE 2,A SUB—BASIN NUMBER 150 0 75 150 SUB—BASIN AREA TIME OF CONCENTRATION e a ROADWAY INLET GRAPHIC SCALE 1 inch--150 ft.Horizontal CEZCE 00HSML4QH7Z DAYSPRING SUBDIVISION NO. 2 Toll Brothers ENGINEERING • PLANNING • SURVEYING • ENVIRONMENTAL ESE Consultants, RAINAGE CATCHMENT PLAN Inc.lnc. AMERICA'S LUXURY HOME BUILDER* T:208-424-0020 3103 W.Sheryl Drive•Suuiteite too 00•Meridian,ID 83642 February 6, 2026 - Meridian, Idaho