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Home My WebLink About20042087.tiff Final Drainage Report For Antelope Estates P.U.D. Weld County, Colorado June 25,2003 P�p RE s?.. � , • UBER$ 9F, Prepared For: o••F, Cy�O Daryl Adolf .Cc 'a 3800 GW Bush Avenue eat NUMBER Wellington,CO -‘1"•• 35721 �� 80549 f71Z jl t)3 Prepared By: MENORTHERN ENGINEERING SERVICES, INC. 420 S.Howes,Suite 202 Fort Collins,Colorado 80521 Phone:(970)221-4158 Fax:(970)221-4159 Project Number: AEP:01-044 2004-2087 NORTHERN INE ENGINEERING SERVICES, INC. June 25, 2003 Drew Scheltinga, PE Public Works Director 933 North 11th Ave Greeley, CO 80631 P.O. Box 758 Greeley, CO 80632 RE: Antelope Estates P.U.D. Weld County, Colorado Project Number: 01-044 Dear Mr. Scheltinga: _ Northern Engineering Services, Inc. is pleased to submit this Final Drainage Report for The Antelope Estates P.U.D. for your review. We understand that review by Weld County is to assure general compliance with standard governing criteria. This report was prepared in compliance with technical criteria set forth in the Urban Drainage and Flood Control District (UDFCD) Urban Storm Drainage Criteria Manual. If you should have any questions or comments as you review this report, please feel free to contact us at your convenience. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Mark Oberschniidt, PE, 35721 Project Engineer 420 SOUTH HOWES, SUITE 202 / FORT COLLINS, COLORADO 80521 / 970.221.4158 / FAX 970.221.4159 Final Drainage Report Northern Engineering Services, Inc. Antelope Estates P.U.D. June 25, 2003 Table of Contents VICINITY MAP I INTRODUCTION 1 1 Objective 1 2 Mapping and Surveying 1 3 Site Reconnaissance 1 II SITE LOCATION AND DESCRIPTION 1 1 Site Location 1 2 Site Description 1 III PRE-DEVELOPMENT CONDITIONS 1 1 Major Basin Description 1 2 Pre-development Drainage Patterns 2 3 Off-Site Drainage 2 IV POST-DEVELOPMENT CONDITIONS 2 1 Post Development Description 2 2 Design Criteria and References 2 3 Hydrologic Criteria 3 4 Hydraulic Criteria 3 5 Developed Drainage Patterns 3 6 Storm Sewers 3 7 Swales 3 8 Detention 4 V CONCLUSIONS 4 1 Compliance with Standards 4 VI REFERENCES 4 APPENDICES APPENDIX A- Hydrology Calculations saw i� i '711 J j • " YT\cu 1 +� r " � `` • 5 VICINITY MAP IITS Final Drainage Report Northern Engineering Services, Inc. Antelope Estates P.U.D. June 25, 2003 Final Drainage Report for The Antelope Estates P.U.D. Subdivision Wellington, Colorado June 25, 2003 I INTRODUCTION 1 OBJECTIVE 1.1 This report summarizes the results of a comprehensive analysis of both pre- and post- development hydrologic and hydraulic conditions for the Antelope Estates P.U.D., in Weld County, Colorado. 2 MAPPING AND SURVEYING 2.1 Topography shown on the site plan was taken from USGS quadrangles for the area. 3 SITE RECONNAISSANCE 3.1 Northern Engineering Services, Inc conducted a site visit to verify drainage patterns, culverts, and land use on Saturday June 21, 2003. II SITE LOCATION AND DESCRIPTION 1 SITE LOCATION 1.1 Antelope Estates P.U.D. is located within the northeast quarter of Section 29, Township 9 North, Range 67 West of the 6th Principal Meridian in the County of Weld, State of Colorado. More specifically the site is located at the southwest corner of Weld County Road (WCR) 102 and 17. (See Vicinity Map) 2 SITE DESCRIPTION 2.1 The site is approximately 120 acres and has historically been irrigated farmland. 2.2 The surrounding area is also irrigated farmland with single-family residence on many of the parcels. III PRE-DEVELOPMENT CONDITIONS 1 MAJOR BASIN DESCRIPTION 1.1 The site is not located in major defined basin. Runoff from the site flows to the south and east eventually reaching an creek that is tributary to Coal Bank Creek 1 Final Drainage Report Northern Engineering Services,Inc. Antelope Estates, P.U.D. June 25,2003 1.2 No part of this site is situated in a FEMA defined floodplains as defined on Flood Insurance Rate Map (FIRM) Community Panel Number 080266-0325 C, dated September 22, 1999. 2 PRE-DEVELOPMENT DRAINAGE PA1nERNS 2.1 The site historically is divided into 3 drainage basins by a ridge that runs southeasterly across the center of the property. Each basin has offsite contributing area. • The northern basin (Basin 1) contributes stormwater to an 18-inch CMP culvert near the intersection of CR 17 and 102. _ • The central basin (Basin 2) contributes stormwater to a low point on WCR 17. There is no culvert at this location. It appears that stormwater would pond on the west side until it overflows the street and flows east or overflows the highpoint in the borrow ditch and flows south. • The southern basin (Basin 3) contributes stormwater to the southern property line. 3 OFF-SITE DRAINAGE 3.1 A ridge is located just west and south of the site, which limits the amount of offsite _ drainage through the site. Refer to the topographic map on the Drainage Exhibit for additional detail concerning the offsite drainage areas. 3.2 All offsite runoff was considered in the design of the storm sewer infrastructure. IV POST-DEVELOPMENT CONDITIONS 1 POST DEVELOPMENT DESCRIPTION 1.1 Development of Antelope Estates P.U.D. will include the following: • 5 single-family residential lots ranging in size from 7.53 to 8.45 acres • 80 acres of open space • A 26-foot wide gravel access road with borrow ditches in a 60-foot public ROW • 3 wells for water supply to the residences 1.2 Drainage improvements in the form of a culvert at the entry to the site and driveway culverts will be called out on the constructions plans. Construction and maintenance of the driveway culverts will be the responsibility of the individual homeowners. 2 DESIGN CRITERIA AND REFERENCES 2.1 Drainage criteria outlined in the Urban Storm Drainage Criteria Manual (USDCM) by the Urban Drainage and Flood Control District (UDFCD) were referenced for this study. 2 - Final Drainage Report Northern Engineering Services, Inc. Antelope Estates,P.U.D. June 25,2003 3 HYDROLOGIC CRITERIA 3.1 The Rational Method was used to estimate peak stormwater runoff within the developed site. The minor 5-year and major 100-year design storms were used in the design of the proposed drainage system, which includes swales and culverts. 3.2 The site is within 7 miles of Wellington and 4 miles of the Larimer / Weld County line. Larimer County has defined Intensity-Duration-Frequency curves for northeastern portion of Larimer County where Wellington is located (Figure 3.3.1-1 — Fort Collins area). Rainfall intensities were taken from Figure 3.3.1-1, based on the — proximity of the site to Wellington. These intensities were utilized in conjunction with the Rational Method to determine peak flows at design points on the site. Percentage impervious values, runoff coefficients, and other criteria related to the Rational Method were obtained from the UDFCD Urban Storm Drainage Criteria Manual. Hydrologic calculations can be found in Appendix A. 3.3 Times of concentration (Tc) for the peak flows were based on the following equation Tc = Ti+Tt. As this development will be predominantly rural the urbanized equation for Tc, L/180+10, was not considered. 4 HYDRAULIC CRITERIA — 4.1 The UDFCD Urban Storm Drainage Criteria Manual were referenced for all hydraulic calculations. 5 DEVELOPED DRAINAGE PA1[ERNS 5.1 The site is divided into three (3) drainage basins designated Basins 1-3. The adjacent offsite basins are designated OS1-OS3 respectively. Refer to the overall basin view on the drainage exhibit for more detail. 5.2 The developed grading will attempt to maintain the existing drainage patterns as much as possible. The proposed access road is along the line of the ridge between basins 1 and 2. 6 STORM SEWERS 6.1 Storm sewers will be limited to driveway culverts and a culvert under the access road into the site. A minimum size of 18-inch is recommended for all driveway culverts. A detail will be provided on the plans. 7 SWALES 7.1 Borrow ditches along the access road are the primary conveyance for stormwater from the site. Existing borrow ditches along both county roads will not be modified with this development. The road and the borrow ditch design will follow the existing topography as closely as possible. 3 Final Drainage Report Northern Engineering Services, Inc Antelope Estates P.U.D. June 25,2003 8 DETENTION — 8.1 No detention is required for this project as there is minimal increase in runoff due to the development. Table I summarizes the changes in runoff due to development. Table 1 Summary of Increases in flow to Design Points Design Q100 Flow Q5 Flow Point Increase cfs % increase Increase cfs % increase 1 0.39 0.33% 0.60 2.01% — 2 0.34 1.00% 0.53 6.25% 3 0.16 0.29% 0.24 1.71% — V CONCLUSIONS 1 COMPLIANCE WITH STANDARDS 1.1 All drainage design considerations are in accordance with the Urban Drainage and — Flood Control District's Drainage Criteria Manual. 1.2 The drainage system proposed within this report and the supporting construction "— documents provides adequate conveyance for the developed stormwater runoff from Antelope Estates PUD. There will be no adverse affects due to stormwater runoff to the downstream areas because of the development of this site. VI REFERENCES — 1) Drainage Criteria Manual, Urban Drainage and Flood Control District, Wright Water Engineers, Inc., Denver, Colorado, Updated June 2001. 2) Larimer County Rainfall IDF Curves for Region 1 figure 3.3.1-1 4 - 1 1 1 1 1 1 1 1 1 1 1 7 1 1 1 1 1 1 1 i .# ) APPENDIX C: INLET CALCULATIONS .--) 1 I I I I I I I I I I I I I I I I I I ) ) ) 6/23/2u03 Northern Engineering Services Inc. aep-rational .xls By: meo Antelope Estates PUD Flow Summary Proj . No. AEP:01-044 Flow Summary for Antelope Estates PUD Notes Design Upstream Total C5 C100 Tc 15 1100 Q5 O100 Point Basins Area acres min iph iph cfs cfs Historic Flows _ 1 1,OS1, 129.42 0.156 0.503 50.50 1.47 1.81 29.75 117.84 2 2,OS2, 29.25 0.152 0.501 36.00 1.89 2.31 8.41 33.88 3 3,OS3, 46.86 0.150 0.500 32.50 2.02 2.45 14.20 57.40 Developed Flows 1 1,OS1, 129.42 0.159 0.505 50.50 1.47 1.81 30.34 118.23 2 2,OS2, 29.25 0.162 0.506 36.00 1.89 2.31 8.93 34.22 _ 3 3,063, 46.86 0.153 0.501 32.50 2.02 2.45 14.44 57.57 Summary of Increases in flow to Design Points O5 Flow Design O100 Flow Increase Point Increase cfs % increase cfs % increase 1 0.39 0.33% 0.60 2.01% 2 0.34 1.00% 0.53 6.25% 3 0.16 0.29% 0.24 1.71% Page 1 of 11 6/23/2003 Northern Engineering Services Inc. aep-rational.xls By: meo Antelope Estates PUD Dbasins-Summary — Proj . No. AEP:01-044 Sub-basin Information For Rational Calculations Developed Basins Single Street- Historic Developed Sub- Family Local Open Street Street basin Home ac ac Space ac Streets areas Areas 1 16.24 3 .31 51.09 CR 102 & 17 2 .57 0 .74 2 9.72 0.78 12. 03 CR 17 0.04 0.74 3 6 .17 0 .00 22.10 NA 0.00 0.00 - OS1 15. 00 1 .63 42.15 CR 102 1.63 OS2 0 .00 0.51 6.21 CR 17 0.51 OS3 0.00 0.00 18 .59 NA 0.00 — Area Area C5 C10 C100 Travel %imp — Basin sf acres ft 1 3077124 70.64 0.16 0.26 0 .51 666 1.7% 2 981356 22.53 0.16 0.26 0 .51 805 2 .1% - 3 1231274 28.27 0.15 0.25 0 .50 1500 0 .7% OS1 2560524 58.78 0.16 0.26 0 .50 1000 1 .4% OS2 292809 6 .72 0.16 0 .26 0.50 656 1.7% - OS3 809852 18.59 0.15 0 .25 0.50 916 0.0% Average 0.16 0.26 0.50 1.2% Assumptions Assumed Single Family Residence in basin OS1 occupied 5 acres per lot — Basins 1-3 are all undeveloped for historic calculations Basins OS1- OS3 will not change with development Open Space is the remaining area in each basin Historic Basins Single Street- Sub- Family Local Open — basin Home ac ac Space ac 1 0 .00 2 .57 68.07 2 0 .00 0 .04 22.49 - 3 0.00 0 .00 28.27 OS1 15.00 1.63 42 .15 OS2 0.00 0 .51 6.21 - OS3 0.00 0 .00 18.59 Page 2 of 11 — 6/23/2003 Northern Engineering Services Inc. aep-rational.xls By: meo Antelope Estates PUD C-dbasins Proj . No. AEP:01-044 Determine Composite Runoff Coefficient for Developed Sub-basins Percentage of land use breakdown Single Sub- Family Street- basin Home Local Open Space Check 1 23 .0% 4 .7% 72 .3% 100% 2 43.1% 3 .5% 53 .4% 100% 3 21.8% 0.0% 78.2% 100% OS1 25.5% 2 .8% 71.7% 100% OS2 0 .0% 7.6% 92 .4% 100% OS3 0.0% 0 .0% 100 .0% 100% Area Land Use Breakdown Single Sub- Family Street- Open Space Total basin Area ac Home ac Local ac ac Area ac 1 70.64 16.24 3 .31 51. 09 70.64 2 22.53 9.72 0.78 12 .03 22.53 3 28.27 6.17 0.00 22 .10 28.27 OS1 58.78 15.00 1.63 42.15 58.78 OS2 6.72 0 .00 0.51 6.21 6.72 OS3 18.59 0.00 0 .00 18.59 18.59 .- Determine Runoff Coefficient for 5-yr Storm Single Sub- Family Street- - basin C Home Local Open Space Total 1 0.160 2 .75 0.89 7.66 11.31 2 0.163 1.65 0 .21 1.80 3 .66 3 0 .154 1 .05 0 .00 3.32 4.36 OS1 0.158 2 .54 0 .44 6.32 9.30 OS2 0 .159 0 .00 0.14 0.93 1.07 - OS3 0.150 0.00 0 .00 2 .79 2 .79 Determine Runoff Coefficient for 10-yr Storm Single — Sub- Family Street- basin C Home Local Open Space Total 1 0.259 4 .34 1.16 12.77 18.28 2 0.261 2 .60 0 .27 3 .01 5.88 3 0.254 1 .65 0.00 5.53 7.17 OS1 0 .257 4.01 0 .57 10.54 15.12 OS2 0.258 0 .00 0.18 1.55 1.73 OS3 0 .250 0.00 0 .00 4.65 4.65 — Page 3 of 11 6/23/2003 Northern Engineering Services Inc. aep-rational.xls By: meo Antelope Estates PUD C-dbasins Proj . No. AEP:01-044 — Determine Runoff Coefficient for 100-yr Storm Single Sub- Family Street- — basin C Home Local Open Space Total 1 0.505 8.30 1.84 25.55 35.68 2 0.507 4 .97 0.43 6 .02 11.41 —. 3 0.502 3 .15 0.00 11. 05 14.20 OS1 0.504 7.66 0.91 21. 08 29.64 0S2 0.504 0.00 0 .28 3 .11 3 .39 — 083 0.500 0.00 0 .00 9.30 9.30 Determine Percent Impervious for each Basin Single — Sub- Family Street- basin %impery Home Local Open Space Total 3% 22% 0% 1 1.72% 0.49 0 .73 0 .00 1.22 2 2.06% 0.29 0 .17 0.00 0.46 3 0 .65% 0 .19 0.00 0.00 0.19 OS1 1.38% 0.45 0.36 0.00 0 .81 O82 1.67% 0.00 0 .11 0 .00 0.11 OS3 0 .00% 0 .00 0.00 0.00 0.00 Page 4 of 11 6/23/2003 Northern Engineering Services Inc. aep-rational .xls By: meo Antelope Estates PUD C-dbasins Proj . No. AEP:01-044 Determine Composite Runoff Coefficient for Historic Sub-basins Area Land Use Breakdown Single Check Sub- Family Street- Open Space Total basin Area ac Home ac Local ac ac Area ac 1 70.64 0.00 2.57 68.07 70.64 2 22 .53 0 .00 0.04 22 .49 22.53 3 28.27 0.00 0.00 28.27 28.27 _ OS1 58.78 15.00 1.63 42.15 58.78 OS2 6.72 0.00 0.51 6.21 6.72 OS3 18.59 0 .00 0.00 18.59 18.59 Determine Runoff Coefficient for 5-yr Storm Single Sub- Family Street- basin C Home Local Open Space Total Delta C5 1 0.154 0.00 0.69 10.21 10.90 0.0057 2 0 .150 0 .00 0.01 3 .37 3 .38 0 .0123 3 0.150 0.00 0.00 4.24 4 .24 0.0043 OS1 0.158 2 .54 0.44 6.32 9.30 0 .0000 OS2 0 .159 0 .00 0 .14 0 .93 1.07 0.0000 OS3 0 .150 0 .00 0.00 2.79 2 .79 0 .0000 Determine Runoff Coefficient for 10-yr Storm Single Sub- Family Street- Delta — basin C Home Local Open Space Total C10 1 0 .254 0 .00 0.90 17.02 17.92 0. 0050 2 0 .250 0.00 0.01 5.62 5.64 0 .0107 3 0.250 0 .00 0 .00 7.07 7.07 0.0037 OS1 0.257 4 .01 0.57 10.54 15.12 0 .0000 0S2 0 .258 0.00 0 .18 1.55 1.73 0 .0000 0S3 0.250 0.00 0 .00 4 .65 4.65 0.0000 — Page 5 of 11 6/23/2003 Northern Engineering Services Inc. aep-rational .xls By: meo Antelope Estates PUD C-dbasins Proj . No. AEP:O1-044 - Determine Runoff Coefficient for 100-yr Storm Single Sub- Family Street- Delta basin C Home Local Open Space Total C100 1 0.502 0 .00 1 .43 34.04 35.46 0 .0031 2 0.500 0 .00 0.02 11.25 11.27 0.0065 3 0.500 0.00 0 .00 14.14 14.14 0.0024 OS1 0.504 7.66 0.91 21.08 29.64 0 .0000 OS2 0.504 0.00 0.28 3 .11 3 .39 0 .0000 0S3 0.500 0. 00 0.00 9.30 9.30 0.0000 Determine Percent Impervious for each Basin — Single Sub- Family Street- Delta basin %impery Home Local Open Space Total Imp % 3% 22% 0% 1 0.800% 0.00 0.57 0.00 0.57 0.0092 2 0.039% 0.00 0.01 0.00 0.01 0.0202 _ 3 0.000% 0.00 0.00 0.00 0.00 0.0065 OS1 1.376% 0.45 0.36 0.00 0.81 0.0000 052 1.670% 0.00 0 .11 0.00 0.11 0.0000 0S3 0.000% 0.00 0 .00 0.00 0.00 0.0000 Composite Historic C values DP Basins Area ac. C5 C100 1 1,OS1, 129.42 0.156 0.503 2 2,0S2, 29.25 0.152 0.501 3 3,053, 46.86 0.150 0.500 Page 6 of 11 6/23/2003 Northern Engineering Services Inc. aep-rational .xls By: meo Antelope Estates PUD Dpointsummary Proj . No. AEP:01-044 Design Point Summary for developed Conditions Composite Runoff DP Contributing Area Coefficients % Imp Sub-basins ac C5 C10 C100 1 1,O51, 129.42 0.159 0.258 0.505 2% 2 2,O52, 29.25 0 .162 0.260 0.506 2% 3 3,O53, 46 .86 0.153 0.252 0.501 0% Design Point Summary for Historic Conditions DP Contributing Area Composite Runoff % Imp Sub-basins ac C5 C10 O100 1 1,O51, 129 .42 0 .16 0.50 '- 2 2,O52, 29.25 0.15 0.50 3 3,O53, 46.86 0 .15 _ 0.50 Page 7 of 11 6/23/2003 Northern Engineering Services Inc. aep-rational .xls By: meo Antelope Estates PUD DP- Tc Proj . No. AEP:01-044 TIME OF CONCENTRATION TO DESIGN POINTS FROM MULTIPLE BASINS Town of Wellington Colorado Overland Flow. Time of Concentration: Velocity (Gutter Flow), V = 20 50.5 ME=_ (0.395*( 1 . I -05)'L^0.5)/S^0.33 Velocity (Swale Flow), V = 15 So.5 Cutter/Swale Flow. Time of Concentration: Pipe C factor = I .486AR213/n Tt = L / G0V Pipe Velocity based on 18" pipe T, = T, + Tt (Equation RO-2) Note: Actual Tc rounded to the nearest 0.5 minutes C5 assumes all overland flow is grass unless otherwise noted Slopes for Travel times are average slopes over the travel distance Overland Flow Gutter Flow Swale Flow i Design Length, L Slope, 5 T, Length, L Slope, 5 Vel, V Tt Length, L Slope, S Vel, V Tt Point C5 (ft) (%) (min) (ft) (To) (ft/s) (min) (ft) (To) (ft/s) (min) 1 0. 15 500 4.00 24.5 0 0.00 0.00_ 0.0 3280.00 2 .00 2. 12 25.8 2 0. 15 500 4.00 24.5 0 0.00 0.00 0.0 1437.00 2 .00 2. 12 11 .3 3 0. 1 5 500 4.00 24.5 0 0.00 0.00 _ 0.0 1000.00 2.00 _ 2. 1 2 7.9 Note: 1) Minimal Development is occurring in the area so for the sake of time of concentration L/180+10 is ignored and a rural condition is assumed ) Page 1 11 1 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ) ) ) 6/23/2u03 Northern Engineering Services Inc. aep-rational.xls By: meo Antelope Estates PUD DP- Tc Proj . No. AEP:01-044 Pipe Flow Tc Comp. Actual Design Length, L Slope, S Vel, V Tt Tc Travel L/180+ T, Point (ft) (To) (ft/s) (mm) (min) Length (ft) 10 (min) 1 0.0 0.0 0.0 0.00 50.3 3780 31 .00 50.5 see note 1 2 0.0 0.0 0.0 0.00 35.8 1937 20.76 36.0 see note 1 3 0.0 0.0 0.0 0.00 32.4 1500 18.33 32.5 see note 1 Page 9 of 11 6/23/2003 Northern Engineering Services Inc. aep-rational.xls By: meo Antelope Estates Typical Lot — Proj . No. AEP: 01-044 Typical Single Family Lot Typical Lot size 572 x 572 equals 327184 sf 7.51 acres Assumptions I A*I Roof area 4000 sf 90% 3600.00 Concrete Patio 300 sf 100% 300.00 — Concrete D/W 2500 sf 100% 2500 .00 Concrete Walks 300 sf 100% 300.00 7100 sf 6700.00 — Remainder is lawn 320084 sf 0% 0.00 Assume Lawn in clayey soil — Percent Impervious (I) taken from Table RO-3 - UDFCD Vol 1 Percent Impervious for Single Family Lots 3 .0% *1 *1 - rounded up to nearest 1% — Determine C factor Assume soil is NRCS soil type C & D — CCD =KCD + (0.858*i3 - 0.786*i2 + 0.774*i+ 0.04) Values of Correction Factors KcOQ K4 _ — NRCS Storm Return Period Soil Types 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr C&D 0.00 t-0.10*i+0.11_-0.18*i+0.211 0.28*i+0.33 -0.33*i+0.4C-0.39*i+0.4 — Kap 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr A 0.00 -0.10 -0.18 -0.28 -0.33 -0.39 B 0.00 0.11 0 .21 0.33 0.40 0.46 Cep 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr — Local 0.06 0.17 0 .27 0 .38 0.45 0.51 Page 10 of 11 — 6/23/2003 Northern Engineering Services Inc. aep-rational.xls By: meo Antelope Estates Typical Street Proj . No. AEP:01-044 Determine Composite C for ROW Street Data for Determining Runoff Coefficients Input Data ROW Width Width EOS Street ft EOS ft Local 60 .00 26.00 Output Data Total Gravel Impery Grass Street Width ft Width ft Width ft Local 26.00 26.00 34.00 Average Impervious Gravel is assumed to be 50* impervious Grass is assumed to be 0% impervious — Grass Width is the ROW width less the Total Impery Width Percent ,— Street Impervious Local 22.00% *1 *1 - rounded up to nearest 1% Determine C, factor Assume soil is NRCS soil type C & D CCD =K CD + (0.858*i3 - 0.786*i2 + 0.774*i+ 0.04) _ Values of Correction Factors Kcm& KA NRCS Storm Return Period Soil Types 2-yr 5-yr I 10-yr 25-yr 50-yr 100-yr 61 C&D 0.00 0.10*i+0.11f-0.18*i+0.21 0.28*i+0.33 -0.33*i+0.40 0.39*i+0.4 I Local r 22% KDD 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr A 0 .00 -0.10 -0.18 -0.28 -0.33 -0.39 B 0 .00 0.11 0 .21 0 .33 0.40 0 .46 Cep 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr Local 0 .18 0.27 0 .35 0 .45 0.51 0 .56 Page 11 of 11 Culvert Designer/Analyzer Report Ex Culvert © WCR 102 and 17 Comments:Based on drainage area we can safely assume the culvert would be overtopped therefore model overtopping road-road elevations asumed Analysis Component Storm Event Check Discharge 118.23 cfs Peak Discharge Method: User-Specified Design Discharge 117.84 cfs Check Discharge 118.23 cfs Tailwater Conditions:Constant Tailwater Tailwater Elevation N/A ft Name Description Discharge HW Elev. Velocity Culvert-1 1-18 inch Circular 10.49 cfs 103.04 ft 6.69 ft/s Weir Roadway 107.81 cfs 103.04 ft N/A Total 118.31 cfs 103.04 ft N/A Title:Antelope Estates Project Engineer d:\...\aep\drainage\stormsewer\aep-ex culverts.cvm Northern Engineering Services Inc uIvertMaste r v2..0 Mark[2005b] 1 06/24/03 01:19:15 PM ©Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666of 3 Page 13 Culvert Designer/Analyzer Report Ex Culvert @ WCR 102 and 17 Component:Culvert-1 Culvert Summary _ Computed Headwater Eleva 103.04 ft Discharge 10.49 cfs Inlet Control HW Elev. 102.75 ft Tailwater Elevation N/A ft Outlet Control HW Elev. 103.04 ft Control Type Outlet Control Headwater Depth/Height 2.03 Grades Upstream Invert 100.00 ft Downstream Invert 99.74 ft Length 26.00 ft Constructed Slope 0.010000 ft/ft Hydraulic Profile Profile CompositeM2PressureProfile Depth, Downstream 1.25 ft Slope Type Mild Normal Depth N/A ft Flow Regime Subcritical Critical Depth 1.25 ft Velocity Downstream 6.69 ft/s Critical Slope 0.033271 ft/ft Section Section Shape Circular Mannings Coefficient 0.024 Section Material CMP Span 1.50 ft Section Size 18 inch Rise 1.50 ft Number Sections 1 Outlet Control Properties Outlet Control HW Elev. 103.04 ft Upstream Velocity Head 0.55 ft Ke 0.90 Entrance Loss 0.49 ft Inlet Control Properties Inlet Control HW Elev. 102.75 ft Flow Control Submerged Inlet Type Projecting Area Full 1.8 ft2 K 0.03400 HDS 5 Chart 2 M 1.50000 HDS 5 Scale 3 0.05530 Equation Form 1 y 0.54000 Title:Antelope Estates Project Engineer: Mark d:\...\aep\drainage\stormsewer\aep-ex culverts.cvm Northern Engineering Services Inc CulvertMaster v2.0[2005b1 06/24/03 01:19:15 PM O Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 2 of 3 Culvert Designer/Analyzer Report Ex Culvert CO WCR 102 and 17 Component:Weir Hydraulic Component(s): Roadway Discharge 107.81 cfs Allowable HW Elevation 103.04 ft Roadway Width 26.00 ft Overtopping Coefficient 2.71 US Low Point 102.00 ft Headwater Elevation 103.04 ft Discharge Coefficient(Cr) 2.71 Submergence Factor(Kt) 1.00 Tailwater Elevation -9,999.00 ft _ Sta(ft) Elev. (ft) 100.00 103.00 150.00 102.00 200.00 103.00 Title: Antelope Estates Project Engineer: Mark d:\...\aep\drainage\stormsewer\aep-ex culverts.cvm Northern Engineering Services Inc CulvertMaster v2.0 12005b] _ 06/24/03 01:19:15 PM O Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 3 of 3 Rating Table Report Ex Culvert @ WCR 102 and 17 Range Data: Minimum Maximum Increment Discharge 110.00 120.00 0.50 cfs Sischarge(cif.}iW Elev. (tt) 110.00 103.01 110.50 103.02 111.00 103.02 111.50 103.02 _ 112.00 103.02 112.50 103.02 113.00 103.02 113.50 103.03 114.00 103.03 114.50 103.03 115.00 103.03 115.50 103.03 116.00 103.03 116.50 103.04 117.00 103.04 117.50 103.04 P4.3 X _\ \ 118.00 103.04 `�-- S u ps.., , V N\.) 10o \-)x-s4 O C c\2'\ N inks ok*N h 118.50 103.04 U 119.00 103.04 - . roLC" W,\\ 4 OVkr � U�apQ� 119.50 103.05 1 u 120.00 103.05 Title:Antelope Estates Project Engineer: Mark ._ d:\...\aep\drainage\stormsewer\aep-ex culverts.cvm Northern Engineering Services Inc CulvertMaster v2.0[2005b] 06/24/03 01:20:35 PM ©Haestad Methods, Inc. 37 Brookside Road Waterbury,CT 06708 USA +1-203-755-1666 Page 1 of 1 titbit'hwes'ter₹ ......1..nty.','iV/i;w.,;_. miles of Wellington _.. Wellington Rainfall Intensity for Wellington — Larimer County Stormwater Manual Fig 3.3.1-1 Rainfall Intensities (in/hr) DURATION DURATION (MINUTES) 2-yr 5-yr 10-yr 100-yr (MINUTES) 2-yr 5-yr 10-yr 100-yr — 2 3 4 5 5.0 3.26 4.68 5.60 9.02'r 73.0 0.84 1:17 - 1.40 2,27 5.5 3.19 ' =4.57 .5.47 8.83 = 73.5 0.83: '1.17 _ ' 1,40':,".2i26 . _ 6.0 3.11 .. 4.46.. . '-.5,84 ' 8,64 74.0 0.83 ::1s16 > 139; .=2:24 6.5 3.04.. ' 435,, 5.22 : 8.44 'i 74.5 '0.82 1416" 1301 2,23rt 7.0 2.96+. '.e4.24, h'°5.09; ;-x8.25.: 75.0 0,82 1.15 f 1.30 . 2.22 7.5 2.89 ;'4..10 :,4L96. .'0.067 75.5 0,82 1'14-`: 1.3*=:2,20' - 8.0 2,82`, 4.02 4.8a. - 7;87.1 76.0 '`0.81r '' 1,:14 13 . ajar, 8.5 2.74..' -3.91' .4.70 " 7.68 = 76.5 . 0.81 . "'1;13 ' 1.364.:'`2,37 9.0 2.67 . '3.80 4.58 . 7.48 77.0 0.80- , - 1.13 336.', . 2.15 9.5 2.59 .3.69`- -4.45: ...7.29 77.5 0.80! .:1.1'2 ....1.352.;.c - 2.13 10.0 2.52 3.58 4.32 7.10 78.0 '.0.80' .,1.11 1.34., ,11 10.5 2.48 -.3,52` .4;26' - '6,99 = 78.5 ;0,79. ',17,11.;.' .1,34 2.09,:. 11.0 ` 244; •, ,346 a 4.20 6.83 79.0 ' '.0.79` 1..10 -1.3a, 2.08:n` - 11.5 2.41 /-341+ ,4'x44, . 6.77' ': 79.5 .,0.78 X1.10.'' 133 ,�2.06I 12.0 2 37 f 3.35 `;4:.08 '..."''.64.6.' 80.0 0.78 1.09 1.32 2.04 12.5 2,33" ' -329 4:02., ` 6;56. 80.5 ' 0.78: 1`.09-` '''1.82;.' ,`2.04'- -- - 13.0 2.29 .,;3.23,, :3.96 6.44 -. 81.0 "0..77` 1.08. 1.31i:7<,'.r 2.04 13.5 2,25 ' 317. ' 3.90 ' `. 6.33 ! 81.5 0,77.: ::1.08 :1.31` 2.03 14.0 2.22 312 .3.84_ :.6,22' 82.0 0.76 11 07 1,30 .: 2.03 ; - 14.5 2.18; ".3.06: 3,78 ' 6.11 82.5 x:0.76., :'1`,07' 130"- -_2:03:- 15.0 2.14 3.00 3,72 6.00' 83.0 0.76 `1;06 1.30 . 2,03- 15.5 `' 2.11;' '2,96.-- :3.67 T .5.91! ' 83.5 0,75 :1,06- 1:201- "2.03 _ 16.0 208.:'293 '-,3.62 :;'5.82 ! 84.0 .`0.75.: -',1;05' `` 1.29' 2.02 16.5 2.05 ' , 2.89. 3.56 5.741 4 84.5 - 0.74 1.05 1.28 2.02 17.0 2,02 .2861 ''3.51 5.65: 85.0 0.74 1.04 1.28 2.02' 17.5 1.99 ";2 82'7"/ '"1:3,46',7". l'.'5.56= 85.5 0.'74 _1.04' :1.27c :-2.01. 18.0 1.96'. = 2.78 3.41 :.5.47f 86.0 0,73'', .=1,03: = 1.27;,. 2.00 18.5 1.93≤ , 2.75 -.3.36.- '5.38 86.5 0.73 ' "1'.03 . 1,26c, 1.99 19.0 1.90 2371 3.30 -5.30.:" 87.0 0,72 1:022 1.26 1.98 - - 19.5 1.87 2,68. 3.25 5.21 87.5 0.72 1.02 ' 1.25 1.97 20.0 1.84 2.64 3.20 5.12 88.0 0.72:: 1.02 1.24. 1.96, 20.5 1.82 2.61 ' 3:17' 5.06 88.5 0.71' ' 1.01 . 1,24. 1<95 21.0 1.60 2.58= 3.1a' 5.00' 89.0 0.71 1,01 1.23 1.94'' - 21.5 1.78 2.55 3.10 4,93x" 89.5 0.70 1,00 'r 1.23 1.93 22.0 1.76 2.52 3.06 4.87 90.0 0.70 1.00 1.22 1.92 r 22.5 1.74 2.49 3.03 4.81x:! 90.5 0.70 1.00 1,21 1.91 23.0 1.72 2.46 ' 3.00 4,75, 91.0 0.70 1 0.99 1.21 1.90 23.5 1.70 2.43 2.96 4.69 91.5 0.69 ! 0.99 , 1,20 1.90 t. 24.0 1,68 2.40 ' 2.93 4.62` 92.0 0.69 0.98 1.20 1.89` - 24.5 1.66 2.37 2:89 4.56 92.5 0.69 0.98 1.19 1.88' 25.0 1.64 2.34 2,86 4.50 93.0 0.69 0.98 1.18 1.87r 25.5 1.62 2.32 2,63 4.46 93.5 0.69 ,, 0.97 > 1.18 1.86 - - DURATION DURATION (MINUTES) 2-yr 5-yr 10-yr 100-yr (MINUTES) 2-yr 5-yr 10-yr 100-yr 26.0 1.61 9.30 ;2.80 4.42.:_ 94.0 ,10.68' .0.97`': 1.17 '1,86 26.5 159' e_997 ,::,;',478:,::::,,,:::44:9.?::: 94.5 ':,0;68, 0.96'; 1,17 . ,„.1.85,: 27.0 ,"1.'":":4-59,,,',,(:,;925 "',';',!•12,79,'„,,;1. 95.0 0.68 0.96 '1.16:: ;1.84 27.5 1 56 .:`1'223 ,`2:70 `':4.31 95.5 0.68- . 0.94:: 1,15 "',1.83_ - 28.0 1.54' 2.21; (,[:,,'2;67.p,",;,-,:-,4,27:: 96.0 0.67 10:95` 1.15`a' 1.82 28.5 1.53 .;2.19 2.64 :':',;;;',4,29-.1,,,' 96.5 ;0.67 1'0.95,; 1.1 ' 11:82 29.0 1:.51::!::':1';/1:1:Z10`;:-.`2:11'2,,[5.0.!:',-:"4.20 97.0 0.67 0.94;:-, 1 14 .. 1.81 29.5 1.50 ..:2.14:. ;,i$51:');1','::::::4i46±')4.1,6': 97.5 l'0.67w x 0.94; 1113 ,,ar180;; 30.0 1 48 2.12 2.54 4.12 98.0 0.626 0.94 'x.12 . 1.r79 ? 30.5 f,,,:f:4,24,27.5 =2.14" :2.52 '!';',4,0(r, 98.5 1fO.66 0.93, 4 t=1.12 , #,;:i1.7 , 31.0 1,45 2 08= 2.50 4.04,. 99.0 , 0.68,i.„Fasam y Tip: I# ._ 31.5 144, ri`2.06 ,.2.49 "4.01':? 99.5 5 xk0.92....` WAS 11.77 32.0 1.42 -.;'2.04N `2.47`-;x3.97: 100.0 0.65-- ../.:0,92H. 1,1© . '1.76 32.5 t 41 ' , 2 02 2.45 3 r 3;93 100.5 .005 s. 0392 t 1 X10 r:;:1x7,5?'. 33.0 1:1140 s 200 2.43 '3.89 ' 101.0 0.64; 0.9'1` 1A0 .1 74 : 33.5 2,-,::',1199i..-, 1 98 ?2.41:a.H v.;',:3.95,,';: 101.5 .10.64 0.91 . ` .0 1 as.1.74 34.0 (-„'„,,..t3721."-,,"„, . # 96 ,:2.40 . 3.82 102.0 0.643, x`0.90 ,I`106 ,73 34.5 135 i 94 ,A('!4.19:9,1„1'0,'10;76';:::: 102.5 064ra ' 90 1 08 1 7*2 35.0 i 1.34 : :41'.92 2,36 ::.'9,74'. 103.0 A;(14013;' e(O X108 1.7 `; 35.5 1 "33 190' 4 371;`1 103.5 x.0.63 i`T0.89 ,;0,9:4", 1;1.70 36.0 1.32 - 1 89 :.2.31 3.68 ' 104.0 0.63 A 111189 } ` 0 . "`1.7cml: 36.5 ,: 1.31 ,,,187' 2.29 ; '3.65 : 104.5 :0.62` ?.Q8$. '1` ,1.06= t,-1.69 . 37.0 130 1.86` '2.26 3.62. 105.0 062: 088 :tat,: 1.68 37.5 t 29 ;184 2:24 14.0,45:9,i.,.59,'' 105.5 0621` 0.88'i`^ 10 t :1.67 - 38.0 1 28 ,',1.62 :2.22, :.3.56''-, 106.0 x61 0.87"x. 1.05., ;1:661. 38.5 127 181 2.19 E3.53k 106.5 '061 '. .cc087 : 1. -1366- , 39.0 126 ;1`'79 X2.17 ' .`3,50 , 107.0 iiithorrA x0.86 . 104 x1.65-` 39.5 1.25` ,n1.71 '`2.14 : `3.47 107.5 '0,.61 '70.86 iii.3i0V, 40.0 "'I:24"H: I:126 2.12 3.44 108.0 0.60`' z 0x86 1.02" lilit034, 40.5 =1.23 '1'.74 2.11 : 3.42' 108.5 060:' ,085"`; 102* 1.62 41.0 1.22 1. 73 2.0 3.39; 109.0 ir0.60 85 .71.01x I62- :' 41.5 ;11..21 :1.71 2.08 : ,.3,37-'° 109.5 ;0.59` '0.84 `:= 1,01`x', 1.61' ', 42.0 ':, 1-.2.0,14, 'ii 1.70 ?'2.07 '::3.34:, 110.0 ',-,0,591; .0.84 1.00 1.60 42.5 120 .,1 68., .;E:"2.06 ' 3.32 110.5 0.591,: g'-',0464,:g 1.00 :_,1.59 43.0 !,,,71';..W.,1 1.66"",',.i: :,2:2:':04,/,i., 3;30` 111.0 0 58: 083= 09911. '"i1,58;,: 43.5 1.18 1.65 2.04 3.27:: 111.5 x:0.58 ,?0.83: 0,99,° 1.58 44.0 1.17. ,•1.63, 2.02 . 3.25'- 112.0 0.5841 , 0.82,` '»„0.98 1;57 44.5 `11.16 1..62 2.01 ' '..,,-:2;.R2,,,,,, 112.5 0;58: . 0.82 0.98 , 1.56 45.0 1.15 1.60 2.00 3.20 ' 113.0 0.57:: ,.0.82. 0.98' : 1.55 45.5 ;1.14 1}.59 1.98 3.18; 113.5 0.57. .0.81 ; 0.97 = ,,,!:-[ 5.;:v,,, 46.0 :1-13 . 1.58 ::,,,,1,99,:-E,:',:',3,15,, 114.0 .:',::0,97,,k,:,,:,...001,-;. ':0,97 , 1.54 . 46.5 1,12 1.56 1.95 .3.13x, 114.5 0.56;, :0.80 ' ;;:404,:i :,1.53 47.0 ;1.11 . 1.55. 1.93 3.10 115.0 0,56 0.80 ! 0.96 1.52 47.5 1.11 1.54 1.91 ' 3.08 115.5 :,116,6".::!:::4480.,,.:',..--:0:',;001,;): 1.51 — 48.0 1.10 1,53 1.89 3.05 ' 116.0 0.55 .0,79: ''0.95'. 1.51 r 48.5 1.09 1.52 1.87 !::,:13.03::: 116.5 „1"0,55,1, 0.79 ::,10,99.',1: 1.50 49.0 1.08 1.56 ,.4:66,:,- 0.99:::, 117.0 ,,":0:64'! 0.79 0.94 1.50` — 49.5 1.07 1.49 1.84 2.98 117.5 va.54 0.79 0.94 ' 1.49 DURATION DURATION (MINUTES) 2-yr 5-yr 10-yr 100-yr (MINUTES) 2-yr 5-yr 10-yr 100-yr 50.0 1.06 1.48 1.82 2.95 118.0 0,54 0.78 0.94 _ 1.48 50.5 1.05 ' 1.47.' i $i 2.93 118.5 0.53 0.78 . 0.93 44.14404. 51.0 1.05 "1.46 1 80 2.92 . 119.0 0.53 "0.78 - 4.93 1.47 51.5 1.04 ,':1.46t fig 2.94 119.5 0.52 0.77 . 0.92= 1.47 52.0 1',03 ; 1 45' 1.78 2.88 ' 120.0 0.52 0,77 0.92 1.46 52.5 : 103 "4144`. _:1x77 2,87 53.0 53.5 `t`1;0f 1.4211 '1"75 r 2.63 54.0 r '1 00 . :.1 2.81 fi 3 .0 ar «,r 54.5 19th ," #P13r 2:80 55.0 0.99 40 1.72- 2.78 55.5 j1449, .'+1.39 56.0 = a9& 1.3911 ,{a17. 56.5 098 57.0 f 0:97 r0a kft60f 57.5 €..97 111..37 58.0 } fl 96 `# Yes#467 267. 58.5 0.9611 "op 1.6 1i 2.65 59 0 095 4I1 4t ' '1c..66 2.64;-59.5 z0.95t , 65 .6r 60.0 094 133, ` 1`.64 2.60,: 60.5 * 094 "1.32x# .4#140v4.:4;940,544; 61.0 ti., 0.9:,` 11` 32. `('1.62" 61.5 093 61131 ar.1.62 2.5611! 62.0 '092 ` 30 @1.61 62.5 zr0.92P .4A1 '. 4.1S0 .2.54 63.0 ,,0.92 RISC 63.5 0.91, 'T1.28 1.58 2.52 64.0 If091 ilibr41#39 - 64.5 i.:t09,0t, ° 1.27 1.57 . 2.49.0: 65.0 090 t 26 1.56 2.48: 65.5 n'!..1.10.`0810..K„1.28 3 1.55 2.47;'' - 66.0 4,4A141:4.;;41111.414201111 66.5 ;10.89 N.:#2'411 6:442.11 67.0 #'t0.88 1�24: .1.51 -'2.42'.;:67.5 -088 ,,23 1.50 :2.41 68.0 i'.44100,1; 68.5 ;087. .,.1 ` 148. . 219 ' 69.0 69.5 g!,7142tffi.086 't4S 2.35 70.0 0.86 1,20 1.44 2.34;5 70.5 086 , x1.20 , .1.43 2.33= - 71.0 0.85, '1.19 143` .2.32` 71.5 72.0 ;0.84#:#144410:41 72.5 0.84 1118 1.41 2.28 Runoff Coefficient vs. Watershed Imperviousness Based on Runoff Coefficient estimating equation published by Urbonas,et.al.(1990)&WEF(1998) — Basic equation for NRCS Soil Types C&D: Ccu =Kco+ (0.858.1'- 0.786'1°+ 0.774*i+ 0.04) — Basic equation for NRCS Soil Type A: CA =KA + (131*!' - 1.44*1'+ 1.135'1- 0.12) in which use values for CA >0 — in which: i = 10/100,imperviousness ratio I. =watershed imperviousness in percent CA =Runoff Coefficient for NRCS Soil Type A KA =Correction factor for CA when the storm return period is greater than 2-years C cn =Runoff Coefficient for NRCS Soil Types C and D Kw =Correction factor for C cc when the storm return period is greater than 2-years - Values of Correction Factors Kcps KA NRCS Storm Return Period - Soil Types 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr C&D 0.00 [-0.10*i+0.11][-0.18*i+0.21](-0.28*1+0.33][-0.33'1+0.40](-0.39*i+0.46. A 0.00 (-0.08*i+0.09]I-0.14*i+0.VI[-0.19*i+0.241[-0.22*1+0.28]t-0.25*i+0.32 Values of Runoff Coefficient C cn Values of Runoff Coefficient CA Imperv. Type C and D NRCS Hydrologic Soil Groups TypeA NRCS Hydrologic Soils Group Ratio(i) 2.yr 5-yr 10-yr 25-yr 50-yr 100-yr 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 2 3 4 5 6 7 2 3 4 5 6 7 0% 0.04 0.15 0.25 0.37 0.44 0.50 0.00 0.09 0.17 0.24 0.28 0.32 5% 0.08 0.18 0.28 0.39 0.46 _ 0.52 0.00 0.09 0.16 0.23 0.27 0.31 - 10% 0.11 0.21 0.30 0.41 0.48 0.53 0.00 0.08 0.16 0.22 0.26 0.30 15% 0.14 0.24 0.32 0.43 0.49 0.54 0.02 0.10 0.17 0.23 0.27 0.30 20% 0.17 0.26 0.34 0.44 0.50 0.55 0.06 0.13 0.20 0.26 0.30 0.33 25% 0.20 0.28 0.36 0.46 0.52 0.56 0.09 0.16 0.23 0.29 0.32 0.35 30% 0.22 0.30 0.38 0.47 0.53 0.57 0.13 0.19 0.25 0.31 0.34 0.37 35% 0.25 0.33 0.40 0.48 0.54 0.57 0.16 0.22 0.28 0.33 0.36 0.39 40% 0.28 0.35 0.42 0.50 0.55 0.58 0.19 0.25 0.30 0.35 0.38 0.41 - 45% 0.31 0.37 0.44 0.51 0.56 0.59 0.22 0.27 0.33 0.37 0.40 0.43 50% 0.34 0.40 0.46 0.53 0.57 0.60 0.25 0.30 0.35 0.40 0.42 0.45 55% 0.37 0.43 0.48 0.55 0.59 0.62 0.29 0.33 0.38 0.42 0.45 0.47 60% 0.41 0.46 0.51 0.57 0.61 0.63 0.33 0.37 0.41 0.45 0.47 0.50 - 65% 0.45 0.49 0.54 0.59 0.63 0.65 0.37 0.41 _ 0.45 0.49 0.51 0.53 70% 0.49 0.53 0.57 0.62 0.66 0.68 0.42 0.45 0.49 0.53 0.54 0.56 75% 0.54 0.58 0.62 0.66 0.69 0.71 0.47 0.50 0.54 0.57 0.59 0.61 80% 0.60 0.63 0.66 0.70 0.73 0.74 0.54 0.56 0.60 0.63 0.64 0.66 85% 0.66 0.68 0.71 0.75 0.78 0.79 0.61 0.63 0.66 0.69 0.70 0.72 90% 0.73 0.75 0.77 0.80 0.83 0.83 0.69 0.71 0.73 0.76 0.77 0.79 95% 0.80 0.82 0.84 0.87 0.89 0.89 0.78 0.80 0.82 0.84 0.85 0.86 - 100% 0.89 0.90 0.92 0.94 0.96 0.96 0.89 0.90 0.92 0.94 0.95 0.96 Notes: For Type B Soils,use the average of coefficients C co and CA. When the Runoff Coefficient in above table is<0,use 0. - When compositing the Runoff Coefficient for different soil types,use the table values above regardless if they are<O. 9 II1IIIII Fig. 3.3.I-I LARIMER COUNTY RAINFALL INTENSITY-DURATION CURVE 8 AREA I - FORT COLLINS AREA 7 BASED ON DATA AND PROCEDURES FROM N.O.A.A. ATLAS 2 , PRECIPITATION - FREQUENCY ATLAS OF THE WESTERN UNITED STATES- VOLUME- COLORADO.L.= 6 0 a N • 5 I cofLI ?swa? ue E `x'49 2 ,Q 9 q9 41'pear I — • 0 30 60 90 120 _ 150 180 STORM DURATION ( Minutes ) 3.3--3 I 1 1 II To determine if flood insurance is available in this community, contact your Insurance agent,or can the National Flood Insurance ______i Program at(800) 638-6620, —.-- 7 I ilk ist APPROXIMATE SCALE I2003000 FEET E �� 12 35I NATIONAL FLOOD INSURANCE PR® I1111OGRAM c , '\ FIRM / i FLOOD INSURANCE RATE MAP 13 WELD - I COUNTY, COLORADO UNINCORPORATED AREA • 7-1 I PANEL 325 OF 1075 I (SEE MAP INDEX FOR PANELS NOT PRINTED) ZONE A 23 Soh 114 *"."--Cif \ \k,,,,, 1 ,_(:, _ ---i I COMMUNITY-PANEL NUMBER 080266 0325 C vn of ZONE C MAP REVISED: PierceA SEPTEMBER 28, 1982 N NOTT INCLUDED 6 \251 `+ Spring Creek federal emergency management agency "C" CDAIAC . . I ----\ N. II ZONE II \-. ,� - _____ ---\_,_______J 19 � I 20 \ II II R I OR- I I S 1TE r 28 1 M ________:---;-----\ . 0 II WO?. 10O II \ '\N... _.__ 31 32 it I v 33 N J / II --• )119N 1 \ c.,,,—/ / J1=------ TBN --I K \ Final Drainage Report contains an oversized Map Please see Original File Hello