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HomeMy WebLinkAboutTHE ELLIE AT OLD TOWN NORTH - FDP240015 - SUBMITTAL DOCUMENTS - ROUND 1 - Drainage Related Document FDP DRAINAGE REPORT The Ellie at Old Town North Old Town North 51 Filing Tract A for: Van Horn Development Management,LLC 14143 Denver West Parkway#100 Golden, CO 80401 engineer: TJC Limited 8751 E Hampden Ave, Suite B10, Denver, CO 80231 James W. Allen, PE 303.489.3346 44kc www.jciviLcom October 28, 2024 Final Drainage Report Page 2 of 10 <tj c TABLE OF CONTENTS GENERAL LOCATION AND EXISTING SITE INFORMATION............................................. 4 MASTER DRAINAGE BASIN INFORMATION ........................................................................ 4 FLOODPLAIN INFORMATION .................................................................................................. 5 PROJECTDESCRIPTION............................................................................................................. 5 PROPOSED DRAINAGE FACILITIES........................................................................................ 5 DRAINAGE DESIGN CRITERIA................................................................................................. 8 VARIANCEREQUESTS............................................................................................................... 9 EROSION CONTROL................................................................................................................... 9 CONCLUSION............................................................................................................................... 9 REFERENCES ............................................................................................................................... 9 APPENDICES .............................................................................................................................. 10 Final Drainage Report Page 3 of 10 OC I hereby attest that this report for the preliminary drainage design for the Ellie at Old Town was prepared by me or under my direct supervision, in accordance with the provisions of the Fort Collins Stormwater Criteria Manual. I understand that the City of Fort Collins does not and will not assume liability for drainage facilities designed by others. James W.Allen Licensed Professional Engineer State of Colorado No. 42256 Final Drainage Report AiNt- Page 4 of 10 GENERAL LOCATION AND EXISTING SITE INFORMATION a) Site Location Description i. The site is located in Section 1, Township 7 North, Range 69 West of the 6th Principal Meridian, County of Larimer, State of Colorado. Also known as Old Town North 5th Filing, Tract A. ii. A vicinity map is attached in appendix A. iii. The property is adjacent to Sungia Rd, Blondel St, and Alleys. iv. Adjacent land uses are residential Old Town North filings. V. The project is within North East College Corridor Outfall (NECCO)Basin 810. The project is with Old Town North Filing 3 Basin 7. vi. The existing site generally slopes west to east. There are two existing 18"RCP culverts that outfall the site under Blondel Street. These culverts were constructed for interim flows during the development of the area. These flows were eliminated when the NECCO improvements were completed. The Old Town North drainage report(appendix D) indicates the downstream facilities were sized to accept 5.1 cfs from the parcel (Basin 7). vii. There are no irrigation facilities on-site. viii. The land is currently vacant. ix. The property is covered with natural grass. Slopes range from 2%to 7%. X. Soils consist of Nunn clay loan with Hydrologic Soil Group C. A NRCS Soils Classification Map is attached as appendix B. MASTER DRAINAGE BASIN INFORMATION a) The site is located in the Lower Dry Creek Basin. The site was situated in the Dry Creek floodplain when the original Old Town North plat was recorded in 2004 and Old Town North was developed. The Dry Creek floodway has since been redefined to remove a majority of the site from the Dry Creek floodplain. The immediate area adjacent to the property is fully developed with residential use. i. The subject property is within the Old Town North Third Filing and 2009 NECCO study. The project runoff will conveyed through existing stormwater facilities to the NECCO Detention pond north of Sungia Road. ii. NECCO assumed a 90% imperviousness (developed condition). b) Site Drainage Basins i. The site is composed of one historic sub-basin and no offsite sub-basins: Sub-basin HI —consists of grass covered vacant land. Runoff sheet flows east to the existing 18"RCP culverts under Blondel St. The Old Town North drainage report(appendix D) indicates the downstream facilities were designed to accept 5.1 cfs from this parcel (Basin 7). Final Drainage Report Page 5 of 10 Sub-Basin Design Area 2-Year 100-Year Point (acres) Runoff Runoff cfs cfs H1 H1 0.81 0.26 1.08 c) There are no irrigation facilities on or adjacent to the property. FLOODPLAIN INFORMATION a) The site is within a Zone X according to FEMA Flood Insurance Rate Map No. 08013C0411K(appendix Q. b) The site was situated in the Dry Creek floodplain when the original Old Town North plat was recorded in 2004 and Old Town North was developed. The Dry Creek floodway has since been redefined to remove a majority of the site from the Dry Creek floodplain. PROJECT DESCRIPTION a) The project proposed two apartment buildings with tuck under garages. Surface parking is being provided on the west end of the site. The existing alley will be widened. A rain garden in proposed to meet Ft Collins LID requirements. b) The site is approximately 0.81 acres. PROPOSED DRAINAGE FACILITIES a) The project site is composed of four sub-basins and no offsite sub-basins: Sub-basin A—consists of roof, pavement, and landscaping. Runoff flows off-site undetained to the western ally and conveyed via an existing gutter pan to the south towards Emmaus Ln south of the site at Design Point 1. Sub-basin B—consists of roof, pavement and a rain gardens. Runoff flows down the private drive to a curb cut and into the rain garden. The rain garden outfalls into one of the existing 18"RCP culverts under Blondel St at Design Point 2. Existing 18" Capacity: 801f 18"RCP @ 0.2% capacity=4.71 cfs. 100-year runoff for Basin B is 4.65 cfs and therefore okay. The Old Town North drainage report(appendix D) indicates the culverts were sized to accept 5.1 cfs while a 100-year event would overtop Blondel Street. Final Drainage Report Page 6 of 10 OC Sub-basin C—consists of sidewalks and landscaping. Runoff sheet flows into Sungia Rd and into an existing storm inlet at the corner of Sungia Rd and Blondel St at Design Point 3. Sub-basin D—consists of sidewalks and landscaping. Runoff sheet flows into Blondel St at Design Point 4. Sub-Basin Design Area 2-Year 100-Year Point (acres) Runoff Runoff cfs cfs A 1 0.16 0.31 1.28 B 2 0.47 1.22 4.65 C 3 0.11 0.09 0.36 D 4 0.06 0.07 0.28 b) There is no on-site detention required for this project. c) A rain garden is proposed within Basin B to treat a minimum of 75% of the new impervious area. Site topography and the existing 18" RCP outfall limits the location of the rain garden bottom requiring the use walls to obtain sufficient storage volume and provide 6 inches of freeboard. Total Impervious Area Added 26,184 sft Min Area Treated 75% for RG 19,638 sft Actual Area Treated 19,680 sft The rain garden has walls on all sides varying from 1.0-2.0 ft tall. Approximately 1.0 ft of the wall will extrude from the ground. The rain garden volume was calculated using the MHFD UD-BMP (Version 3.07) spreadsheet. The required WQCV= 568 cft. The rain garden is designed assuming a 12" ponding depth and provides 642 cft. The 4"underdrain discharges into the outlet structure through a 1/2" orifice plate. The outlet structure is a 3 ft x 3 ft concrete box structure built over top the existing 18"RCP. d) LID techniques utilized in this design include minimizing directly connection impervious areas by discharging roof downspouts onto the surface. No stormwater will be piped except for the stormwater discharging from the rain garden. e) Maintenance of the rain garden can be performed from the private drive or Blondel Street(20 ft east of the facility). f) A drainage easement will be provided over the rain garden. Maintenance of Bioretention(Rain Garden) The primary maintenance objective for bioretention, also known as porous landscape detention, is to keep vegetation healthy, remove sediment and trash, and ensure that the facility is draining properly. The growing medium may need to be replaced eventually to Final Drainage Report Page 7 of 10 *C maintain performance. This section summarizes key maintenance considerations for bioretention. Inspection Inspect the infiltrating surface at least twice annually following precipitation events to determine if the bioretention area is providing acceptable infiltration. Bioretention facilities are designed with a maximum depth for the WQCV of one foot and soils that will typically drain the WQCV over approximately 12 hours. If standing water persists for more than 24 hours after runoff has ceased, clogging should be further investigated and remedied. Additionally, check for erosion and repair as necessary. Debris and Litter Removal Remove debris and litter from the infiltrating surface to minimize clogging of the media. Remove debris and litter from the overflow structure. Mowing and Plant Care a) All vegetation: Maintain healthy, weed-free vegetation. Weeds should be removed before they flower. The frequency of weeding will depend on the planting scheme and cover. When the growing media is covered with mulch or densely vegetated, less frequent weeding will be required. b) Grasses: When started from seed, allow time for germination and establishment of grass prior to mowing. If mowing is required during this period for weed control, it should be accomplished with hand-held string trimmers to minimize disturbance to the seedbed. After established, mow as desired or as needed for weed control. Following this period, mowing of native/drought tolerant grasses may stop or be reduced to maintain a length of no less than 6 inches. Mowing of manicured grasses may vary from as frequently as weekly during the summer, to no mowing during the winter. Irrigation Scheduling and Maintenance a) Adjust irrigation throughout the growing season to provide the proper irrigation application rate to maintain healthy vegetation. Less irrigation is typically needed in early summer and fall, while more irrigation is needed during the peak summer months.Native grasses and other drought tolerant plantings should not typically require routine irrigation after establishment, except during prolonged dry periods. b) Check for broken sprinkler heads and repair them, as needed. Completely drain the irrigation system before the first winter freeze each year. Upon reactivation of the irrigation system in the spring, inspect all components and replace damaged parts, as needed. Replacement of Wood Mulch Final Drainage Report Page 8 of 10 OC Replace wood mulch only when needed to maintain a mulch depth of up to approximately 3 inches. Excess mulch will reduce the volume available for storage. Sediment Removal and Growing Media Replacement If ponded water is observed in a bioretention cell more than 24 hours after the end of a runoff event, check underdrain outfall locations and clean-outs for blockages. Maintenance activities to restore infiltration capacity of bioretention facilities will vary with the degree and nature of the clogging. If clogging is primarily related to sediment accumulation on the filter surface, infiltration may be improved by removing excess accumulated sediment and scarifying the surface of the filter with a rake. If the clogging is due to migration of sediments deeper into the pore spaces of the media, removal and replacement of all or a portion of the media may be required. The frequency of media replacement will depend on site-specific pollutant loading characteristics. Based on experience to date in the metro Denver area, the required frequency of media replacement is not known. To date UDFCD is not aware of any rain gardens constructed to the recommendations of these criteria that have required full replacement of the growing media. Although surface clogging of the media is expected over time, established root systems promote infiltration. This means that mature vegetation that covers the filter surface should increase the life span of the growing media, serving to promote infiltration even as the media surface clogs. DRAINAGE DESIGN CRITERIA a) The subject property is within the Old Town North Third Filing and 2009 NECCO study. The project runoff will be conveyed through existing stormwater facilities to the NECCO detention pond north of Sungia Road. NECCO assumed a 90%imperviousness (developed condition). The previous studies have no impact to the proposed design. b) Four-step process a. Where possible, the runoff sheet flows across landscaping before discharging into Sungia Rd and Blondel St. b. A rain garden is proposed to treat a minimum of 75% of the new impervious pavement and roof areas. c. There are no streams within the project area to strengthen. d. A construction erosion control plan will be included with this project. c) Rainfall data is provided in table 3.4.1 IDF Table for Rational Method from the Fort Collins Stormwater Criteria Manual. d) Design frequencies used in this design: Minor: 2-year Major: 100-year e) The Rational method was used to calculate hydrological data following the Fort Collins Stormwater Criteria Manual chapter 5.OThe peak runoff from minor and major storm events are calculated using the Rational Method formula as detailed below: Q=CIA Where: Q= Storm runoff in cubic feet per second (cfs) Final Drainage Report Page 9 of 10 OC C=Runoff Coefficient I=Runoff intensity in inches per hour A=Drainage area in acres Runoff coefficients were obtained from Table 3.2-2. Times of concentration were calculated based on the initial time or overland flow time (for urbanized undeveloped basins <300' overland flow),with a minimum time of concentration of 5 minutes. t; = 1.87(1.1-C5)A/So.33 MANUAL Eqn. (3.3-2) V= 1.49/n RZ/3S1/z MANUAL Eqn. (5-4) tt = L/(60V) MANUAL Eqn. (5-5) tc = t; +tt MANUAL Eqn. (5-3) MAX.tc = L/180+ 10 MANUAL Eqn. (3.3-5) f) No on-site detention is required as part of this project. g) No public streets requiring capacity calculations are required as part of this project. h) The rain garden outlet structure is sized using weir flow calculations. i) No storm sewer pipe networks are included with this project. j) No swale or channels are included with this project. k) No emergency spillways are included with this project. VARIANCE REQUESTS a) No variances are requested as part of this project. EROSION CONTROL a) This report is in compliance with all erosion control materials within the final Erosion Control Report and Plans. CONCLUSION a) Compliance with requirements—this design complies with the requirements of the city of Fort Collins and master drainage plans referenced in this report. b) Drainage plan effectiveness—this design effectively routes developed flows throughout the site and provides water quality for at least 75% of the new impervious areas. This design does not impact adjacent properties. REFERENCES 1. City of Fort Collins Stormwater Criteria Manuel, December 2018. 2. Urban Storm Drainage Criteria Manual, Volumes 1, 2, and 3, Revised March 2024 3. North East College Corridor Outfall(NECCO), August 2009. 4. Old Town North Third Filing, Drainage, Sediment/Erosion Control, and Stormwater Quality Report, June 2017 Final Drainage Report Page 10 of 10 APPENDICES A. Vicinity Map B. FEMA Map C. Soil Information D. Old Town North Third Filing Excerpts E. Drainage Calculations F. Drainage Plans CONIFER ST HICKORY ST CONIFER ST 04 00 �Q\NE��c41i a m cm 3 � E SUNGIA RD 8 z � �'�4U E SUNGIA RD OS�IVD�ST CAJETAN ST J m p Sj E VINE DR VICINITY MAP National Flood Hazard Layer FIRMette (.. FFM Legend 105°4'40"W 40°36'12"N SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT Without Base Flood Elevation(BFE) zone A.V.A99 SPECIAL FLOOD With BFE or Depth zone AE,AO.AH.VE,AR _ I _ HAZARD AREAS Regulatory Floodway ' f r 0.2%Annual Chance Flood Hazard,Areas a ; of 1%annual chance flood with average + i - depth less than one foot or with drainage areas of less than one square mile zonex V Future Conditions 1%Annual 0+AREAOF MIt IMALFLOOD HAZARD +� Chance Flood Hazard Zone X -'r 1 `'one X - Area with Reduced Flood Risk due to M► OTHER AREAS OF Levee.See Notes.zone x -We- ! FLOOD HAZARD Area with Flood Risk due to Levee zone o - W � NO SCREEN Area of Minimal Flood Hazard zonex W I 1 Q Effective LOMRs LL r rz_ 6 n � « M ' +• OTHER AREAS Area of Undetermined Flood Hazard zone D CO kL ~ �,�.�,�r GENERAL -—-- Channel,Culvert,or Storm Sewer City,of Fort C.olhn STRUCTURES I I I I I I r Levee,Dike,or Floodwall +— 's r ' "08010-1 =2 Cross Sections with 1%Annual Chance 1 17•5 Water Surface Elevation e- - - Coastal Transect 17N R691N Q - 4, —513— Base Flood Elevation Line(BFE) rl�r T7N R69W S1 �,� Limit of Study Jurisdiction Boundary LOMR 19-08-0751P' — — Coastal Transect Baseline OTHER W (+i� 1 ' 1 . 1 @tt�N15/2020 FEATURES Protile Baseline �OnC AE LL L Hydrographic Feature Ctp r 1 1ft Digital Data Available N 1 � No Digital Data Available �► '� MAP PANELS Unmapped r LOMR 21 08-Z' --- _ Of!11/19/2021� ® The pin displayed on the map is an approximate OMR 20-OS-0643P U�[ r�i ANNUAL CHANCE FLOOD HAZARD point selected by the user and does not represent f f P,l25/2021 7' an authoritative property location. j. This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap �� ♦ accuracy standards Q ♦�� The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA.This map {� was exported on 4/19/2024 at 2:17 PM and does not reflect changes or amendments subsequent to this date and L`OMR 06-08 B3X _ 4L t time.The NFHL and effective information may change or @tt 19/20' 7 Zone AE a become superseded by new data over time. LOO SWAY W 4/ — �'-� This map image is void if the one or more of the following map �W _ -�T_ - .� �j elements do not appear:basemap imagery,flood zone labels, Q_ LL� a AE legend,scale bar,map creation date,community identifiers, n FIRM panel number,and FIRM effective date.Map images for Feet 1:6,000 10504'3"W 40035'45N unmapped and unmodernized areas cannot be used for 0 250 500 1,000 1,500 2,000 regulatory purposes. Basemap Imagery Source:USGS National Map 2023 Appendix C Soil Map—Larimer County Area,Colorado 3: v v 493800 493810 493820 493630 493840 493850 493860 493870 493880 493890 49,'3900 493910 493920 40°35'59"N — 40°35 59"N 4 P I I F I Soi'I"M•a may n®t be valid a;t this scale. 40°35'57'N 40°35 57"N 493800 493810 4938M 493830 493840 493850 4938M 493870 4938M 493890 493900 493910 493920 3: 3 0 0� Map Scale:1:627 ff printed on A landscape(11"x 8.5")sheet. v N Meters ° 0 5 10 ZO 30 Feet 0 30 60 120 180 Map projection:Web Mercator Comer coordinates:WGS84 Edge tics:L TM Zone 13N WGS84 USDA Natural Resources Web Soil Survey 4/19/2024 Conservation Service National Cooperative Soil Survey Page 1 of 3 Appendix C Soil Map—Larimer County Area,Colorado MAP LEGEND MAP INFORMATION Area of Interest(AOI) - Spoil Area The soil surveys that comprise your AOI were mapped at Area of Interest(AOI) 1:24,000. Q Stony Spot Soils Very Stony Spot Warning:Soil Map may not be valid at this scale. Soil Map Unit Polygons Wet spot Enlargement of maps beyond the scale of mapping can cause Soil Map Unit Lines misunderstanding of the detail of mapping and accuracy of soil 13 Other line placement.The maps do not show the small areas of Sail Map Unit Points Special Line Features contrasting soils that could have been shown at a more detailed .� Special Point Features scale. V Blowout Water Features Streams and Canals Please rely on the bar scale on each map sheet for map Borrow Pit measurements. Transportation X Clay Spot .,. Rails Source of Map: Natural Resources Conservation Service Closed Depression Web Soil Survey URL: ..i Interstate Highways Coordinate System: Web Mercator(EPSG:3857) Gravel Pit US Routes Maps from the Web Soil Survey are based on the Web Mercator Gravelly Spot Major Roads projection,which preserves direction and shape but distorts distance and area.A projection that preserves area,such as the r Landfill Local Roads Albers equal-area conic projection,should be used if more Lava Flow Background accurate calculations of distance or area are required. Marsh or swamp ® Aerial Photography This product is generated from the USDA-NRCS certified data as of the version dates)listed below. Mine or Quarry Soil Survey Area: Larimer County Area,Colorado Miscellaneous Water Survey Area Data: Version 18,Aug 24,2023 Perennial Water Soil map units are labeled(as space allows)for map scales Rock Outcrop 1:50,000 or larger. Saline Spot Date(s)aerial images were photographed: Jul 2,2021—Aug 25, 2021 Sandy Spot The orthophoto or other base map on which the soil lines were Severely Eroded Spot compiled and digitized probably differs from the background imagery displayed on these maps.As a result,some minor Sinkhole shifting of map unit boundaries may be evident. Slide or Slip oa Sodic Spot USDA Natural Resources Web Soil Survey 4/19/2024 Conservation Service National Cooperative Soil Survey Page 2 of 3 Appendix C Soil Map—Larimer County Area,Colorado Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 73 Nunn clay loam,0 to 1 percent 1.6 100.0% slopes Totals for Area of Interest 1.6 100.0% USDA Natural Resources Web Soil Survey 4/19/2024 Conservation Service National Cooperative Soil Survey Page 3 of 3 Appendix C Map Unit Description:Nunn clay loam,0 to 1 percent slopes---Larimer County Area,Colorado Larimer County Area, Colorado 73—Nunn clay loam, 0 to 1 percent slopes Map Unit Setting National map unit symbol: 2ting Elevation: 4,100 to 5,700 feet Mean annual precipitation: 14 to 15 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 135 to 152 days Farmland classification: Prime farmland if irrigated Map Unit Composition Nunn and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Nunn Setting Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Pleistocene aged alluvium and/or eolian deposits Typical profile Ap - 0 to 6 inches: clay loam Bt1 - 6 to 10 inches: clay loam Bt2- 10 to 26 inches: clay loam Btk-26 to 31 inches: clay loam Bk1 -31 to 47 inches: loam Bk2-47 to 80 inches: loam Properties and qualities Slope: 0 to 1 percent Depth to restrictive feature: More than 80 inches Drainage class:Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum content: 7 percent Maximum salinity: Nonsaline (0.1 to 1.0 mmhos/cm) Sodium adsorption ratio, maximum: 0.5 Available water supply, 0 to 60 inches: High (about 9.1 inches) Interpretive groups Land capability classification (irrigated): 3e USDA Natural Resources Web Soil Survey 4/19/2024 Conservation Service National Cooperative Soil Survey Page 1 of 2 Appendix C Map Unit Description:Nunn clay loam,0 to 1 percent slopes---Larimer County Area,Colorado Land capability classification (nonirrigated): 4e Hydrologic Soil Group: C Ecological site: R067BY042CO - Clayey Plains Hydric soil rating: No Minor Components Heldt Percent of map unit: 10 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape: Linear Across-slope shape: Linear Ecological site: R067BY042CO- Clayey Plains Hydric soil rating: No Wages Percent of map unit: 5 percent Landform:Terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Ecological site: R067BY002CO- Loamy Plains Hydric soil rating: No Data Source Information Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 18, Aug 24, 2023 USDA Natural Resources Web Soil Survey 4/19/2024 Conservation Service National Cooperative Soil Survey Page 2 of 2 Apendix D Page 4 Drainage, Sediment/Erosion Control,and Stormwater Quality Report Old Town North Third Filing;Fort Collins, Colorado a. Runoff from the front lots of the single family lots fronting Osiander Street and included in Sub-basin A is directed to the Old Town North detention Pond. Refer to original Old Town North Drainage Plan in Appendix IV. 3. A majority of the Old Town North Third Filing property is included in the 2009 North East College Corridor Outfall (NECCO) study. Old Town North Third Filing runoff will be conveyed to the NECCO detention Pond north of Suniga Road via storm sewer. a. A majority of the Old Town North Third Filing site is included in NECCO Basin 810 and was modeled as a developed basin. b. NECCO implemented an area of 8.2 acres for Basin 810 at 90% imperviousness (developed condition) in the SWMM model. 4. A portion of the North East College Corridor Outfall (NECCO) improvements were constructed adjacent to Old Town North Third Filing on the south side of Suniga Road with the Aspen Heights Subdivision project to the north. a. The section of storm sewer constructed in Suniga Road to convey runoff from the south side of Suniga Road to the north side of Suniga Road is a 36" diameter RCP. The storm sewer profile included with the Aspen Heights Subdivision Utility Plans is included with this report for immediate reference. Refer to Appendix IV. i. Reference Sheet 32 of 43 (record drawing) of the "Utility Plans for l Suniga Road to Blue Spruce Drive to Redwood Street and Redwood Street from Lupine Drive to Cajetan Street"by Owen Consulting Group, Inc.; Owen Project Number: 155-101 FC; Plans dated April 29, 2015; City Engineer approval date: 05/18/2015; Plan revision date: 10/28/2015 (As-Built storm). b. The existing NECCO 36" RCP storm sewer is currently bulkheaded at both ends with no outfall. Suniga Street existing inlets accept storm runoff and snowmelt runoff to this section of storm sewer with no outfall. Therefore, the NECCO 36" RCP storm sewer acts as a temporary storage facility. There is approximately 960 LF of existing NECCO 36" RCP storm sewer according to Sheet 32 of 43 (record drawing)of the"Utility Plans for Suniga Road to Blue Spruce Drive to Redwood Street and Redwood Street from Lupine Drive to Cajetan Street". C. The NECCO Regional Detention Pond on the north side of Suniga Road is not complete. It is currently built to accommodate Aspen Heights Subdivision in an interim condition. Our understanding is that the NECCO regional Pond and outfall will be completed in 2 to 4 years. r � Offi ci a l Co Page 6 Apendix D Drainage, Sediment/Erosion Control,and Stormwater Quality Report Old Town North Third Filing; Fort Collins,Colorado b. Refer to Aspen Heights Offsite Streets Sheet 30 of 43: Swale Plan and Profile included in Appendix W. C. Refer to Aspen Heights Offsite Streets Sheet 31 of 43: Swale Plan and Profile included in Appendix IV. 3. Two (2) 14"x23" elliptical RCP culverts were placed under Blondel Street and a channel was constructed on the Old Town north property with Aspen Heights construction. Our understanding is that the culverts and channel were constructed to convey interim historic flows from the west to Dry Creek and the Lake Canal. Our understanding is that these flows are eliminated when the NECCO improvements are completed. a. The two (2) 14"x23" elliptical RCP culverts convey a 10-year storm flow of 20.8 cfs. b. The 50-year storm flow to this point is 35.8 cfs. C. The 100-year storm peak flow is 46.8 cfs. d. Refer to Appendix for April 27, 2015 e-mail from Larry Owen to Michael Palizzi provided by Mr. Larry Owen discussing the Blondel Street culvert capacity and interim peak flows. 4. After development of Aspen Heights Subdivision,.construction of Suniga Road and Redwood Street, and the construction of the interim channel on the Old Town North property with the Aspen Heights Subdivision for conveyance of historic flows from the west, runoff from a majority of the Old Town North Third Filing site has no outfall. The channel berm was built up higher than existing grades on the east and dammed the historic outfall point for this property. a. Refer to Topographical Survey for Block 6, Tracts JJ and KK, Old Town North by Intermill Land Surveying. IV. DRAINAGE DESIGN CRITERIA A. Regulations 1. Stormwater management improvements are designed in compliance with the requirements of the City of Fort Collins Stormwater Criteria Manual adopted December 2011. (Manual). The Manual incorporates most of the Urban Storm Drainage Criteria Manual (USDCM) with amendments that are unique to Fort Collins. 2. The latest versions of the USDCM software were used for runoff calculations. Page 11 Drainage, Sediment/Erosion Control,and Stormwater Quality Report Old Town North Thud Filing-, Fort Collins, Colorado C. Specific Details—Culverts and Channel 1. The two(2) 14"x23" elliptical RCP culverts that were placed under Blondel Street with Aspen Heights construction will remain in place. Although identified as temporary culverts in all Aspen Heights drawings, these culverts will most likely remain in place, primarily to accommodate Tract F, Old Town North redevelopment. 2. The two (2) 14"x23" elliptical RCP culverts that were placed under Redwood Street with Aspen Heights construction will remain in place.No Old Town North Third Filing runoff is directed to these culverts. They are there specifically for the purpose of conveying historic flows prior to completion of the NECCO system and could possibly be used if Lot 1, Block 12, Aspen Heights Subdivision is developed. Flows from these culverts will be conveyed across the project through the North Channel System. 3. The North Channel System consists of a trapezoidal channel with a 5' bottom width and 4:1 side slopes. The channel has a main channel bed slope of 0.0039 ft/ft. The channel is sized to accommodate the required freeboard at Q100*1.33= 82.9 cfs. The resultant Froude Number= 0.50. 4. Pairs (2) of 18" NRCP culverts will be placed under the sidewalks that cross the North Channel system. The culverts will not overtop during the I Oyr event, and will overtop 0.42' during the 100-year event. Please see the culvert calculations in Appendix I. D. Specific Detail—Street Capacities 1. The street capacities in Suniga Road upstream of Design Points 2, 3 and 3a are not exceeded for either the Minor and Major storm events. The inlets installed on Suniga Road are not to address capacity, but only to intercept the 100-year event flow before it leaves the Project site. The inlet calculations are found in Appendix I. 2. A typical cross section of the bump outs on Osiander Street was analyzed and the street capacity was found to be 6.44 cfs to the crown elevation, satisfying both the Minor and Major storm event requirements. 3. Emmaus Lane requires inlets at design points, 4, 4ac, 5 and 6 to address street capacity and intercept the entire major storm event at the sag location located at design point 4ac. 4. Street capacity calculations are presented in Appendix I. Apendix D rJI CALL. BEFORE � YOU DIG r CALL UTILITY N0TIFlCATNON CENTER OF COLORADO AT 1-800-922-1987 1 uolt.4"A.r 1F - IM�J COY.IA d Q!�N8N7/ I I-�1 — )•m 9MS EllT 2 E 1 .PROPERTY LIPPE �� � KEYh1AP 2�j WOM S WALE TO 11.00' rnooE s�ALa ro 11.00' - �� �Z O BOTTOM N"A01 AT CVLVEATS BOTTO1d%*I"AT CULVERTS ti j11° `~- _ O a B E TFAPEZOOAL axx. AaA •*•� O U(9 SKIS uLOPrtESS..'TYP� - -- - - - ---- - A o � W 6 BLONOEL CULVERT 0+00.00 TNRU 1+01.00 STATION \ la7sme aetrrlr� 1� f EASMNr 0#00 uF-1 H a x � B \ o ►►►yyy +470 +970 � 6 PROPOSED GRADE of L LM1AL tusrrx as < W IE.+L�iN •a srs awc x 0W 1.59' ] a AN Il vl S VJ Ii9L 2 _7 +fOO 4960 6 0400 STATION lum E li r DRAINAGE SMUIE 5Th 0400.00 T11RU B+00.00 GRAPHICSCALE r STAW Sv 2s Sv —1ja 200' 0+00 t+oo 2+00 3#00 woo 6+00 4+00 7+00 wao +950 +950 1 INCH-50 FEET NT - +170[ — — T -- --- --•- — -- — - ——=—— —— — — — —— 4fro car 0r raRr cOUFlrs, cotoRADO o _ 1 U11UT7 PLAIT APPROVAL APPROYEO: �_ tl CNCll CR DATE O +960 _ _ _ -- _D — - 4NO CNCCKEO f: A M[A50 A OA E a. Ur1UrT // i 0 5€f CULVERT CHECKED BY: i PROryLE.THIS SHEET - S ORYNAT DAi rd/41�N� 4`;:' 1 +950 A CN[CKCD lY: a0400 IEM S4#00 N 7#00 CIItCK[0 DYI 1 A 1 IS>•t01 Ff .'# -1 ENYIAOHVCNTAL PLAWNO A E 19 APR 2YU INKY.' - CHECKED BY: 30 43 C- 4 q :) Developed Site Hydrology Old Town North Third Filing DesIgn Point Basins Area(ac) %Imp C", Q,(Cfs) 01'r,"(0s) Notes 1 2 3 3a 4 4e5 5a 6 6a 7 8 9 10 6.65 55% 0.37 0.77 4.7 33.9 2 2 0.16 75% 0.64 0.88 0.2 1.4 3 3 0.53 60% 0,41 0.79 0.8 4.2 3a 38 0.60 60% 0.41 0.79 0.7 4.5 4 4 0.57 64% 0.44 0,81 0.7 4.6 4a 4a 0.60 64% 0.44 0.81 0.7 4,8 4b 4b 0.10 95% 0.80 1.00 0.2 1.0 4c 4b 0.33 65% 0.45 0.82 0A 2.7 4ac_ 4a,4c 0.93 84% 0.44 0.81 1.1 9.1 _ 5 5 0.46 58% 0.39 0.78 0.5 3.6 �I 5a 5a 0.09 94% 0.78 1.00 0.2 0.9 L 6 6 0.33 64% 0.44 0.81 0.4 2.7 ® 6a 7 0,58 76% 0,54 0.88 0.9 1A 7 7 0.68 75% 0,64 0.88 0.9 5.1 8 5,5a,6,6a,7,8 2.87 56% 0.28 0.73 1.5 13.9 Bypasses O„=20.8 cfs and Q,ee=46.8 efs o8sae flows coming from the west. �r 9 9 0,48 13% 0.13 0.67 02 32 10 10 0.40 38% 0.27 0.73 0.3 2.9 11 11 058 60% 0.41 0.79 0.7 4.5 Conveyed south to Old Town North detention pond 12 12 0.36 60% 0.41 079 0.4 2.8 Conveyed south to Ohl Town North detention pond •Mluhi-unit detached recommended values used for single family denskies over 6 units/acre SWMM Basins Site Basins Area(ac.) %imp OTN Central 4.4a.4b.4c.10 2.00 60.5% O East 2. -7 46.0% OTN West 5,5a,6,6a.7,8 287 562% Site 6.55 55A% Site LID Treated Area Calculation: De,tp P.i,,t li-- %irrl, T.Wr%,-(�qft) Are.(Wft) LID6MP Area(sqft) 11IMPTireatment Ratio Met UD Treated Area(sqlt) 8 5,Sa.6,6a,7.6 56.2% 125,153 70,317 Rain Ga+den 1,405 - 70,317 ® 9 2,3,3e,9 55.7% 72,834 40 601 Rain Gaaden - 40,601 10 to 38.4% 17.424 6.693 UDFCD-GS - - 6.693 Total LID Treated Impervious Area= 117,611 Total Site Impervious Area= 192.411 Percentage of site imper0ous area treated by LID= 64% ERNST r.„rhrrarno -- - _ pendix D 1 SCOURSTCa' GRAPHIC S C LE 'H L EXISTING OVERHEAD ELECTRIC TRANSMISSION LINE & POLE � � !r�'�fl� � 100 1 ,-�- j EXISTING FIBER OPTIC LIItiIE1110 '1 f inch 80 t . _ 91, h EXISTING SANITARY SEVER Wf MN INSTALS 06" SCOLI � � . (`•�_ —1 rr� EX[STING 150 +UNITARY SEWER � � - - - " .� -- •i .ALn EXISTING WATER LINE W/'SERVIPCE jIo �PO ' . CCO RE GI _ - __,► _`_ €� - —_ EXISTING GAS LIFE , A s. EXISTING ELECTRIC LINE 20 LF (2) 18" NRCP W/ FE5 ­! A�* INSTALL 6'X6' SCOUR'STOP `l � � � � _ PROPOSED SANITARY SEWER 'W,/WH PROPOSED WJ4TI<RC LINE " y - - _.- PROPOSED GAS LINE - � PROPOSED ELECTRICLINE ._. , _ _. _ ., -...•._ .-,-.- - - -`- 02 PROPOSED ELECTRICAL CONDUITIN I 6 EXISTING FIRE FYa�IaL4NT Cf}IJIINJITIt1N INLET _- _ yJBLOCK 12 r k r 'RC / 'F i 3 CRST -- Y - -'h- INSTALL X6' S E LOT I r fiA . 84 DRY Ex a � kI - - _ _ xi •, - 00 4TILJT�' E,0.Sc 'EN 1# F+IEiC.� w/ t9 ! }by '�; F' � 7�I: 1tl3hl IrdL.ET .. -' _ _ _ _� 25' ovERla�lr wire �-�'�.. �'�'Y_ �� �i h 'fo Am Vrs 13 �Y !Ir 4I 1,. - - i ni.i 9 _ _ r i •• _.. IP. �A1' - - lIi1�1P�fl I%J �, ,� _..'•° -. .-v; _' _;•. - - s � , - '' ill �rn� ASPEN H�I,n,lep;y � _ �h t I. r• %k R�• SUBDIVISIONI ' J 40 I _ y , 1 A 1` rt ` , i,�` ° .. , �' 9"I 9 d r Y r,SRC �"� i i A —' 4 x23 HERGP CL III �•�.. 14: x� �IERCP L LII. - ,. _ Isaw I h - . I _ . - � � .i ��---- - - _ 10 TYRE R Ir�I�I _ R � .+'� � - � �'d"'F�GP'�L II �' r ' I5 YID i I C a a.r3 V akti '" '+E"`.., � � 5"Tyres I� `-,: •- , ,, , '� •. ',,w � : a, 6 _ I, . .� � �7 T R r�Ie# _ _� . . d 62 18 MCP CI_III 25" T R Ilnlel 48L ei ��� • ., .... , - � X9 SCR �� ,$ !4 Sf ,. . , , , • A� 5 'i y .I,,•,r I}} pp,,yy -- . .« V••` - . !1 • I -V'- t �. �Irr" � ' i�'. . • r " - , - I CT - ".a.P rrY '. �: IY - .� - - 4-_.� - - ..�' S - - ,. •s.., • IA - ,- �'. I ! I '.' -. 16 _ ' a- � '. r f}.S8 4.79 � - _. , I _' 1� •i 1 - -= - fit' • r 3 Deln,+er 16 Coa•nb1n4tlor, L IL IL 2 0-0 Y, r - .i+P �iw �,,..- �� j. I'4 ' _ a .. ,_ ®_ � -__ S Illlllla� -- _ • � - �. - _ — -�. � u , , .I • '' !-•' ,wfrw. h' '..y { yip r -i-9 +• ' m , - - - - . —.. - i:. .- -.T ' f 1�fMfa? y _•_'_'+, ,I _ '�' �'�` - e•iaJ - - � � Yw .,,. r.<. r : " " 't•' . .a : Tw"p yTs„—r TIPJ a I ai+t- - _ z. l I 7 •,I F}, _ .,� • r ' r 7 1r" �-r'��lv}/r�R '. ...,, I s+r+ .... . -. _._. .v _ �+�i'f � � - .a4 G®I+.,L7' ° ' i '� �� _ F,.;�.. r . , •Y ,. r �- � ,�' - 3_ _-1 _ t _ _ r -- __ --� - .max: - _ � � �► `� ` � �'' _ #: ,`. ; • 1 i•. '11 _ c•_4ti.ZaY..il..,f - e yy � yy 1 - L k .i► ,'v'Y:', � "' ►� __ - --'Et".�.- :t tr1' I y =_.. - ! I I� 1, Im " � .A I� `d � y �n- .�r�r � i � I M � I �, - +�' +a. • �- 4 Denver 16 Clom I c I r! I'' S. '� € A f g 1 I r r tr"yys `fP...... p `` •.I I r! f y ,N 7 � � � � , � � !� � _ � I Jr Ain --» � � � I ' � �, I. •rl � 1 16 I Ayj Iis [y, t w Xi�. � � ..+.` +{� i'�. iF P� ,�• #r ,��y. � f I� ! 1• 4 j A L� � �rp kl•1' ��' H� �� - � I 'f I 1 1 I � \ ) Canvsr 16 Combinan � 6 � � 'r<t ,��1,� _ * 1 +7 '+' ryl." i- � �'-M1�", �,S',�.. � 1� � � �+r' ..,v... � Y+i 'y-�j"" "'k"aw+.i_w« •..-,z �I., �,� IL. I � ° � � � IdY�O'�9 I I; ti � -` } i r AF T 4 . ! d r ,a. r jam' DIY " .9""1 9 `rp"Y' I iwc.,,r -•- .. M bi1� , ` .-... .-.-« �W7 - - ._ . -'"•`�� �r i'•1 M 1 h,ww. ,5 •J' �, II � � 4�r h LEGEND f . •,wa,A i,•6 ;r'•i.Y.r :,a 4,,w`4n r �'�", $"3_c�%P'c• '.r.adssyr. {�'� 4, I ' � r !-,"� ■a� -ai,'� CONTOUR �j �A I 1'• �' � ,4 " , + � _ . a- �-�--- �I[il• r:I' _ A / 1« i- . .n rv,-.. s+- .•p- I V 4 O N 1 �1 -'.✓ .> "i ��-• - o • I' �IiI N Ill,! 1 A FL�11 S IRS I _ d.k Y III ..r.+. ay..• ,r{t •'- — - I, 1 S's' f A * t �• r- 1 �� E�tISI•II�PG 5' CONTOUR .. - '�^ _:.3..4 `..6 F � _� `"-,-•-+' 'wyr •,..ice �i•�'' �- � l � � � � PROPOSED 'I' CONTOUR ,�... _ D Iy -�9M1.1, - _ r.� ��y ��. � tl � �. �t mow.«:.�-., - Ate'" � 1� «y, 2R, ,ter: RIt~' ISED 5' E;INTf]I31Z p•- . -._ r .p�� 4 ewe— ,nt it kL66 Y y'� � '� '� 'A 'R••r V P fff fk !1 Il• r Fpy„ •� '.#_-'^.u-,.ay+.-.�.._1'_p°..,Ar _T '_.j f _ �P�,l{ ��•—Y�.•,.i'-'��xi+~r_,9_=,'_g'.+-�."."w�,I�)�, 'S _�,4�••1 �.,,y�• .�� .�. ++._Y-%ipJnd�►Y`'1!" �,T•'t..+.s-' __'.1�". #' ��.`i-rY.YY,��$."�.Y�I �`'• 'w7 I � ,Al^P �I" BASIN RCllOARY S BA IN BOUNDARY ts f _ r "'"�l e. �� :�` T"•,1 } [�■y^yy �"�.,.r "wrgrl.,wyi� -` -9 ' ' _" " . rr,.av +- - -^ '�"-.T'..sa—'-�•- # iM T(u�aR aY.l t • i 'Y' 'l .� " •.. ..r. "--,._, I-C - _ .. — 1 City of Fort Collins, Colorado {° A = BASIN DI=SI'GNATICN PIIA� PRCVArAG = AREA IN ACRES � id Site Hydrology COEFFICIENT (104 YR, EVENT) 6 hIl'I�RDwEC?: ® �C CCI�lI�I"riSITE RUNOFF � OW Town of Thrlyd Filing -- - N APPROVED FLOOD?LAIN USE PERMIT Clra e�Y�lry€r� chile . - �wr,. �t ` - .'� _ IIwI7'd1MG ANY CHECKED BY..Ac) [] DESIGN POINT DESIGNATION f ..I.. QClIi Pltlt7ft T' I3� _ - -. . � Yi._ ��� WORK PROPOSED WI I sIII:�C THE EXIST1N!U WI t xaA5rEwkrER UTILITY ew-z PROPOSED STORM SEDER .,�� .__ � T m 2 � - �' � ��3 OBI I.T9 •-_ ��, �� FL�ClE1©FLAG I�,RTiI:I�r CI"IEGI�EI} BY, ,,,....-- �, A I�[C�-RISIa � 1�'II='1P5, I� I�,€�}LIII�EL7 T -�, 1 _ _ _� a ' y • PRIOR Tel BE`GIT+NIN AN'Y WOR<KW1T11II�I se�4:�l�rt UrtLrr C+a4C ► lu r des111 EXISTING STORM SEWER # 4 `#5T 65 U44 ��d ��" �� _. - . - ...,._.__ � HEF'L{�ODWA�Y. CHECKED BY M"S MO RECREAM - ere FLOW DIRECTION 41 #10 VA _ 02 10 -- rR�FIC EFpQINEER DATE— « --- - — — F F 3I1.T I� - 0. . .® ..:sv,_.. ., _z, _ ._.._v._ . -__ CHECKED BY, u�,r Kw�r WEv�a�l,l 5 of ®. _ s 6 RIP RAP 6+ 031 0_im _ -- 61 - -- -- - - I'm "._....,. .A CHECKED BY - - _ - 0-4 IN 0!4 �i k�, .� Z:67 in 1� - _.III - �� ��� �� �8cbcl s #onf,�' 11 ��TT'� -- --_.�._. _ ., . ...r_ --------- - - � I �'liasa ,P1e�zu hard baaea� rrr#swad by tea GYt� of ;IP�arrt Ca�s -s _ -- --- ----- ------_ - ---- — - -- ,far a0jrr@pj only, The roVja�r Nola& a•n! JMPIY r,xap-rrn3jbLUJy by -- --- - - 0.4---�3 '__-- 0 - ------ - -y.. lb .lam doIini the ni'r f r cY� ins ra P � y Ilr 1� all 0] ! or the City of Fort IConLaB for aalolurao)y and oarr-datuaaa of CURD SOCK —_' - � "i � --- � .` ._ s �� �w LNe calculations. PuLbarmore. the review does act Imply that 11 s A 0.I:E III 01 I_� � �'7�+I7�G�l ilh�l � '� �u��tt� of ReAna 012 Me � am the ftal gr�ent!'Ltea Oil I�T9 .6+ �.al $a0-.OiT'r�r'�Ni4r, I rarluJrald 1�r roviow alau.,I,N L he onastmed la "'v reamon as avoepleg �L RJkCI{IIhYG CONTROL PJwp ibe 42ty of fort C,�llana for lyda3PlUabmJ qt�at ftanalat �l �of 1��' a shown that may be " raqulrocd dutft t1h@ ocrmLmolian phos a" M OF REVISIONS Duke Gr �r,I. [).la1�G, / .,R.I 1 r CORPORATION TITLE ] TER DRAINAGE PLAN - PROJECT N4, - I$HEL'" rar, '� SHEAR F•+ Ifi��gg r T� Tr�TT I��LYi�r � � LI11't� '�} �� 1 1 1._l _ SHEETS I se By CMacrSplia" field 'Book W.S. - GREELEY ASSOCU`T°ES, LI 4836 S. CGLLECE AVE. SUM 12. FORT IC!p'L.LINS, COLORADO 80525 [,1) TOW NORTHTHIRD FILING DI]l� SY [eacriplNl�rl - kale " " _ +N ro'hr 13,, 19 27 '±�''.S. PHONE: (�970) 226-51334 (970) 226-4451 �'C?�L'T"' COLLINS, �'�I�I�R�� I Appendix E Table 3.2-2. Surface Type- Runoff Coefficients Surface Type Runoff Coefficients Hardscape or Hard Surface Asphalt, Concrete 0.95 Rooftop 0.95 Recycled Asphalt 0.80 Gravel 0.50 Pavers 0.50 Landscape or Pervious Surface Lawns, Sandy Soil, Flat Slope< 2% 0.10 Lawns, Sandy Soil,Avg Slope 2-7% 0.15 Lawns, Sandy Soil, Steep Slope >7% 0.20 Lawns, Clayey Soil, Flat Slope <2% 0.20 Lawns, Clayey Soil, Avg Slope 2-7% 0.25 Lawns, Clayey Soil, Steep Slope>7% 0.35 3.2.1 Composite Runoff Coefficients Drainage sub-basins are frequently composed of land that has multiple surface types or zoning classifications. In such cases a composite runoff coefficient must be calculated for any given drainage sub-basin. The composite runoff coefficient is obtained using the following formula: Y(C,xAi) C= i-1 A Equation 5-2 t Where: C= Composite Runoff Coefficient C; = Runoff Coefficient for Specific Area (A;), dimensionless A; =Area of Surface with Runoff Coefficient of C;, acres or square feet n = Number of different surfaces to be considered At=Total Area over which C is applicable, acres or square feet 3.2.2 Runoff Coefficient Frequency Adjustment Factor The runoff coefficients provided in Table 3.2-1 and Table 3.2-2 are appropriate for use with the 2-year storm event. For any analysis of storms with higher intensities, an adjustment of the runoff coefficient is required due to the lessening amount of infiltration, depression retention, evapotranspiration and other losses that have a proportionally smaller effect on high-intensity storm runoff. This adjustment is Appendix E TJ C Project Ellie "C" CALCULATIONS Date 10/28/2024 PAVEMENT 0.95 ROOFS 0.95 GRAVEL 0.50 LANDSCAPE/UNDEVELOPED 0.15 2-7% OVERALL PAVEMENT GRAVEL BASIN (ACRE) OVERALL (SF) (SF) (SF) ROOFS (SF) LANDSCAPE (SF) 2 YR C 100 YR C H1 0.81 35,197 - - - 35,197 0.15 0.18 Site Total 0.81 35,197 - - - 35,197 0.15 0.18 OVERALL PAVEMENT GRAVEL BASIN (ACRE) OVERALL (SF) (SF) (SF) ROOFS (SF) LANDSCAPE (SF) 2 YR C 100 YR C A 0.16 7,130 3,445 - 1,054 2,631 0.65 0.79 B 0.47 20,348 6,146 - 13,534 668 0.92 1.00 C 0.11 4,932 1,105 - - 3,827 0.33 0.40 D 0.06 2,787 900 - - 1,887 0.41 0.49 Site Total 0.81 35,197 11,596 - 14,588 9,013 0.75 0.89 Total Imperviouss Area Added 26,184 SIFT Min Area Treated (75%for RG) 19,638 SIFT Actual Area Treated 19,680 SIFT OKAY! T:\Projects\E11ie\03_Project Reports\Drainage\Calcs\C Calu-C-CALCS 10/28/2024 Appendix E TJC Project Ellie TIME OF CONCENTRATION-DEVELOPED Date: 10/28/2024 ti=1.87(1.1-CS)4L/S"" MANUAL Eqn.(3.3-2) V=1.49/n R2"S"2 MANUAL Eqn.(5-4) tt=L/(60V) MANUAL Eqn.(5-5) tc=ti+tt MANUAL Eqn.(5-3) MAX.t�=L/180+10 MANUAL Eqn.(3.3-5) SUB-BASIN DATA INITIAL/OVERLAND TRAVEL TIME(Tt) COMP Tc CHECK FINAL REMARKS AVG.SLOPE Tc (Urbanized Basins) Tc Design Point BASIN(S) AREA C LENGTH AVG.SLOPE Ti LENGTH S n R VEL Tt TOTAL Tc=(L/180)+10 (Acres) N (ft/ft) (fps) (min) LENGTH(ft) (min) (min) H1 H1 0.81 0.15 300 2.0 24.48 0.0 0.0 24.48 300 11.7 11.7 1 A 0.16 0.65 45 4.0 3.53 76 0.01 0.12 0.50 0.8 1.6 5.15 121 10.7 5.2 2 B 0.47 0.92 45 2.0 1.76 214 0.008 0.12 1.00 1.1 3.2 4.97 259 11.4 5.0 3 C 0.11 0.33 15 2.0 4.44 200 0.01 0.12 0.50 0.8 4.3 8.70 215 11.2 8.7 4 D 0.06 0.41 12 4.0 2.84 200 0.01 0.12 0.50 0.8 4.3 7.10 212 11.2 7.1 T:\Projects\El1ie\03_Project Reports\Drainage\Calcs\C Calac-CONC.TIME 10/28/2024 Appendix E Table 3.4-1. IN Table for Rational Method Duration Intensity Intensity Intensity Duration Intensity Intensity Intensity 2-year 10-year 100-year 2-year 10-year 100-year (min) (in/hr) (in/hr) (in/hr) (min) (in/hr) (in/hr) (in/hr) 5 2.85 4.87 9.95 39 1.09 1.86 3.8 6 2.67 4.56 9.31 40 1.07 1.83 3.74 7 2.52 4.31 8.80 41 1.05 1.80 3.68 8 2.40 4.10 8.38 42 1.04 1.77 3.62 9 2.30 3.93 8.03 43 1.02 1.74 3.56 10 2.21 3.78 7.72 44 1.01 1.72 3.51 11 2.13 3.63 7.42 45 0.99 1.69 3.46 12 2.05 3.50 7.16 46 0.98 1.67 3.41 13 1.98 3.39 6.92 47 0.96 1.64 3.36 14 1.92 3.29 6.71 48 0.95 1.62 3.31 15 1.87 3.19 6.52 49 0.94 1.6 3.27 16 1.81 3.08 6.30 50 0.92 1.58 3.23 17 1.75 2.99 6.10 51 0.91 1.56 3.18 18 1.70 2.90 5.92 52 0.9 1.54 3.14 19 1.65 2.82 5.75 53 0.89 1.52 3.10 20 1.61 2.74 5.60 54 0.88 1.50 3.07 21 1.56 2.67 5.46 55 0.87 1.48 3.03 22 1.53 2.61 5.32 56 0.86 1.47 2.99 23 1.49 2.55 5.20 57 0.85 1.45 2.96 24 1.46 2.49 5.09 58 0.84 1.43 2.92 25 1.43 2.44 4.98 59 0.83 1.42 2.89 26 1.4 2.39 4.87 60 0.82 1.4 2.86 27 1.37 2.34 4.78 65 0.78 1.32 2.71 28 1.34 2.29 4.69 70 0.73 1.25 2.59 29 1.32 2.25 4.60 75 0.70 1.19 2.48 30 1.30 2.21 4.52 80 0.66 1.14 2.38 31 1.27 2.16 4.42 85 0.64 1.09 2.29 32 1.24 2.12 4.33 90 0.61 1.05 2.21 33 1.22 2.08 4.24 95 0.58 1.01 2.13 34 1.19 2.04 4.16 100 0.56 0.97 2.06 35 1.17 2.00 4.08 105 0.54 0.94 2.00 36 1.15 1.96 4.01 110 0.52 0.91 1.94 37 1.16 1.93 3.93 115 0.51 0.88 1.88 38 1.11 1.89 3.87 120 0.49 0.86 1.84 Appendix E TJC Project Ellie Date: 10/28/2024 2-YEAR DIRECT RUNOFF TOTAL RUNOFF TRAVELTIME REMARKS DESIGN BASIN(S) AREA RUNOFF tc INTENSITY RUNOFF tc SUM INTENSITY RUNOFF DESIGN SLOPE PIPE LENGTH VEL Tt Tc POINT (ACRES) COEFF (MIN) C*A (IN/HR) (CFS) (MIN) C*A (IN/HR) (CFS) Q N SIZE (FT) (FPS) (MIN) (MIN) H1 H1 0.81 0.15 11.7 0.12 2.13 0.26 1 A 0.16 0.65 5.2 0.11 2.85 0.31 2 B 0.47 0.92 5.0 0.43 2.85 1.23 3 C 0.11 0.33 8.7 0.04 2.30 0.09 4 D 0.06 0.41 7.1 0.03 2.52 0.07 T:\Projects\Ellie\03_Project Reports\Drainage\Calc\C Cal"-2-Yr 10/28/2024 Appendix E TJC Project Ellie Date: 10/28/2024 100-YEAR DIRECT RUNOFF TOTAL RUNOFF TRAVELTIME REMARKS DESIGN BASIN(S) AREA RUNOFF tc INTENSITY RUNOFF tc SUM INTENSITY RUNOFF DESIGN SLOPE PIPE LENGTH VEL Tt Tc POINT (ACRES) COEFF (MIN) C*A (IN/HR) (CFS) (MIN) C*A (IN/HR) (CFS) Q N SIZE (FT) (FPS) (MIN) (MIN) H1 H1 0.81 0.18 11.7 0.15 7.42 1.08 1 A 0.16 0.79 5.2 0.13 9.95 1.28 2 B 0.47 1.00 5.0 0.47 9.95 4.65 3 C 0.11 0.40 8.7 0.04 8.03 0.36 4 D 0.06 0.49 7.1 0.03 8.80 0.28 T:\Projects\Ellie\03_Project Reports\Drainage\Calc\C Calcx-100-Yr 10/28/2024 Appendix E MHFD In/et, Version 5.03(Ay gust 2023 AREA Drive Capacity T"''^'r This worksheet uses the NRCS vegetal T Manning's method to determine v Manning's n for grass-lined channels. d ' d mokx An override Manning's n can be entered for other channel materials. I- T—B--� Analysis of Trapezoidal Channel(Grass-Lined uses SCS Method) NRCSS Vegetal Retardance(A,B,C,D,or E) A,B,C,D,or E= Manning's n(Leave cell D16 blank to manually enter an n value) n= 0.012 Channel Invert Slope So= 0.0080 ft/ft Bottom Width B= 0.00 ft Left Side Slope Z1= 50.00 ft/ft Right Side Sloe Z2= 50.00 ft/ft Check one of the following soil es: Chw e 0— Soil Type: Max.Velocity W-0 Max Froude No.(F-0 Non-Cohesive Non-Cohesive 5.0 fps 0.60 Cohesive Cohesive 7.0 fps 0.80 Paved Paved N/A N/A Minor Storm Maor Storm Maximum Allowable Top Width of Channel for Minor&Major Storm TM"= 20.00 20.00 ft Maximum Allowable Water Depth in Channel for Minor&Major Storm dMnx= 1.00 1.00 I t Allowable Channel Capacity Based On Channel Geometry Minor Storm Major Storm MINOR STORM Allowable Capacity is based on Tap Width Criterion 4.8 4.8 cfs MAJOR STORM Allowable Capacity is based on Top Width Criterion daib„,= 0.20 0.20 ft Water Depth in Channel Based On Design Peak Flow Design Peak Flow Q,= 1.3 4.7 cfs ,Water Depth d= 0.12 0.20 ft Minor storm max.allowable capacity GOOD-greater than the design flow given on sheet'Inlet Management' Major storm max.allowable capacity GOOD-greater than the design flow given on sheet'Inlet Management' MHFD-Inlet_v5.03,Drive Capacity 10/28/2024,2:41 PM Appendix E Design Procedure Form: Rain Garden(RG) UD-BMP(Version 3.07,March 2018) Sheet 1 of 2 Designer: Jim Allen Company: Tic Date: October 28,2024 Project: Ellie Location: E Sungia&Blonde[ 1.Basin Storage Volume A)Effective Imperviousness of Tributary Area,la la= 92.0 % (100%if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio(i=la/100) i= 0.920 C) Water Quality Capture Volume(WQCV)for a 12-hour Drain Time WQCV= 0.34 watershed inches (WQCV=0.8*(0.91*i3-1.19*i2+0.78*i) D) Contributing Watershed Area(including rain garden area) Area= 20,348 sq ft E) Water Quality Capture Volume(WQCV)Design Volume VWQCV= 568 cu ft Vol=(WQCV/12)*Area F) For Watersheds Outside of the Denver Region,Depth of dS=0 in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER=0cu ft Water Quality Capture Volume(WQCV)Design Volume H) User Input of Water Quality Capture Volume(WQCV)Design Volume VWQCV USER= cu ft (Only if a different WQCV Design Volume is desired) 2.Basin Geometry A)WQCV Depth(12-inch maximum) DwQcv= 12 in B)Rain Garden Side Slopes(Z=4 min.,horiz.dist per unit vertical) Z= 0.00 ft/ft (Use"0"if rain garden has vertical walls) C)Mimimum Flat Surface Area AM;,,= 374 sq ft D)Actual Flat Surface Area AActua,= 642 sq ft E)Area at Design Depth(Top Surface Area) AT,= 642 sq ft F)Rain Garden Total Volume VT= 642 cu ft (VT=((ATop+AAC1 y)/2)*Depth) 3.Growing Media Choose One ®18"Rain Garden Growing Media [C)Other(Explain): 4.Underdrain System Choose One A)Are underdrains provided? G YES (j NO B)Underdrain system orifice diameter for 12 hour drain time i)Distance From Lowest Elevation of the Storage y= 2.5 ft Volume to the Center of the Orifice ii)Volume to Drain in 12 Hours V0112= 568 cu ft iii)Orifice Diameter,3/8"Minimum Do= 1/2 in Ellie RG Size,RG 10/28/2024,1:46 PM Appendix E Design Procedure Form: Rain Garden(RG) Sheet 2 of 2 Designer: Jim Allen Company: TJC Date: October 28,2024 Project: Ellie Location: E Sungia&Blondel 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric Choose One Q YES A) Is an impermeable liner provided due to proximity Q NO of structures or groundwater contamination? PROVIDE A 30 MIL(MIN)PVC LINER WITH CDOT CLASS B GEOTEXTILE ABOVE IT. USE THE SAME GEOTEXTILE BELOW THE LINER IF THE SUBGRADE IS ANGULAR 6. Inlet/Outlet Control Choose One Q Sheet Flow-No Energy Dissipation Required A) Inlet Control QQ Concentrated Flow-Energy Dissipation Provided Choose One 7.Vegetation Q Seed(Plan for frequent weed control) Q Plantings Q sand Grown or Other High Infiltration Sod 8. Irrigation Choose One Q YES A) Will the rain garden be irrigated? ONO Notes: Ellie RG Size,RG 10/28/2024,1:46 PM Appendix E [I i RAM GA TJ C Project Ellie Townhomes Ft Collins Date 10/28/2024 Raingarden #1 Outlet Weir 3x3 Box Inlet Step 1 Calculate head over weir at 2-yr runoff Weir Flow Qweir=C*L*H3/2 Solve for H Where, 2 -Year Qwelr= discharge (cfs) = 1.22 C = weir coefficient= 3.4 L = weir length (ft) = 9 H = head (ft) = 0.12 Step 2 Calculate head over weir at 100-yr runoff Weir Flow Qweir=C*L*H3/2 Solve for H Where, 100 -Year Qwelr= discharge (cfs) = 4.65 C = weir coefficient= 3.4 L = weir length (ft) = 9 H = head (ft) = 0.28 Appendix E MHFD-Culvert, Version 4.00(May 2020) Project: Ellie TH Pipe ID: Existing 18" RCP TC �r � angle kkw Aron / , u Design Information (Input) Pipe Invert Slope So= 0.0020 ft/ft Pipe Manning's n-value n = 0.0130 Pipe Diameter D= 18.00 inches Design discharge Q= 4.65 cfs Full-Flow Capacity(Calculated) Full-flow area Af= 1.77 sq ft Full-flow wetted perimeter Pf= 4.71 ft Half Central Angle Theta = 3.14 radians Full-flow capacity Qf= 4.71 cfs Calculation of Normal Flow Condition Half Central Angle(0<Theta<3.14) Theta= 2.24 radians Flow area An = 1.53 sq ft Top width Tn = 1.18 ft Wetted perimeter Pn = 3.35 ft Flow depth Yn= 1.21 ft Flow velocity Vn = 3.04 fps Discharge Qn = 4.65 cfs Percent of Full Flow Flow= 98.7% of full flow Normal Depth Froude Number Frn= 0.47 subcritical Calculation of Critical Flow Condition Half Central Angle(0<Theta-c<3.14) Theta-c= 1.68 radians Critical flow area Ac= 1.00 sq ft Critical top width Tc= 1.49 ft Critical flow depth Yc= 0.83 ft Critical flow velocity Vc= 4.65 fps Critical Depth Froude Number Fri= 1.00 MHFD-Culvert_v4.0,Pipe 6/18/2024,4:05 PM Appendix E Stormwater Detention and Infiltration Design Data Sheet SDI-Design Data v2.00, Released January 2020 Stormwater Facility Name: Bioretention Pond Facility Location&Jurisdiction: Blondel and Suniga User Input: Watershed Characteristics User Defined User Defined User Defined User Defined Rain Garden{RGi Bioretenfion s RG Stage[ft] Area[ft^2] Stage[ft] Discharge[cfs] Watershed Area = 0.47 acres 0.00 642 0.00 0.01 Watershed Length = 250 ft 1.00 642 1.00 0.02 Watershed Length to Centroid = 120 ft 1.10 642 1.10 4.65 Watershed Slope= 0.010 ft/ft 1.20 642 1.20 10.00 Watershed Imperviousness= 92.0% percent Percentage Hydrologic Soil Group A= Chours percent Percentage Hydrologic Soil Group B= percent Percentage Hydrologic Soil Groups C/D= percent Target WQCV Drain Time= Location for 1-hr Rainfall Depths(use dropdown): User Input After providing required inputs above including 1-hour rainfall depths,click'Run CUHP'to generate runoff hydrographs using the embedded Colorado Urban Hydrograph Procedure. Once CUHP has been run and the Stage-Area-Discharge information has been provided,click'Process Data'to interpolate the Stage-Area-Volume-Discharge data and generate summary results in the table below. Once this is complete,click'Print to PDF'. After completing and printing this worksheet to a pdf,go to: https://maperture.digitaldataservices.com/qvh/?viewer=cswdif Create a new stormwater facility,and attach the PDF of this worksheet to that record. Routed Hydrograph Results Design Storm Return Period = WQCV 2 Year 5 Year 10 Year 50 Year 100 Year One-Hour Rainfall Depth = N/A 2.85 3.00 4.87 5.00 9.95 in CUHP Runoff Volume= 0.013 0.107 0.113 0.189 0.194 0.394 acre-ft Inflow Hydrograph Volume= N/A 0.107 0.113 0.189 0.194 0.394 acre-ft Time to Drain 97%of Inflow Volume= 10.9 11.4 11.3 9.3 9.1 4.6 hours Time to Drain 99%of Inflow Volume= 11.2 13.7 13.7 12.9 12.8 10.9 hours Maximum Ponding Depth = 0.89 1.06 1.07 1.06 1.09 1.14 ft Maximum Ponded Area = 0.01 0.01 1 0.01 0.01 0.01 0.01 acres Maximum Volume Stored = 0.013 0.016 0.016 0.016 0.016 0.017 acre-ft SDI-Detention System,Design Data 10/28/2024,2:42 PM Appendix E Stormwater Detention and Infiltration Desiqn Data Sheet 100YR IN 8 100YR OUT �50YR IN 7 50YR OUT 6 —10YR IN ———10YR OUT 5 —5YR IN ••••••5YR OUT 3 q —2YRIN 0 2YR OUT 3 WQCV IN ••••••WQCV OUT 2 IL 1%1 ok X It Y Y 0 0.1 TIMH[hr] 10 1.4 �100YR 1.2 —50YR —10YR 1 —5YR x —2YR Ss a 0.8 0 Z —WQCV zz 20.6 0.4 0.2 0 0.1 1 10 100 DRAIN TIME[hr] SDI_Detention System,Design Data 10/28/2024,2:42 PM LEGEND EXISTING 1 ' CONTOUR 5730 PROPOSED 1 ' CONTOUR 5730 OVERLAND FLOW -00. EMERGENCY OVERFLOW PATH BASIN BOUNDARY HIGH POINT LOW POINT RAIN WATER LEADER BASIN DESIGNATION A 2 YR RUNOFF COEFFICIENT 1.2 7a 100 YR RUNOFF COEFFICIENT BASIN AREA EX STM MH (ACRES) RIM: 4970.04' EX STM MH DESIGN POINT EAST SUNIGA ROAD 36" RCP INV. (W): 4957.52' RIM: 4968.28' 3 (115' ROW) 36" RCP INV. (E): 4957.31' 24" RCP INV. (S): 4958.05' 1 4" PVC INV. (N): 4965.08' 36" RCP INV. (W): 4957.08' 3 36" RCP INV. 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I EMERGENCY OVERFLOW PATH TVC LIMITED BASIN BOUNDARY 8751 E HAMPDEN AVE HIGH POINT SUITE B10 DENVER, CO 80231 LOW POINT 303.840,4742 RAIN WATER LEADER www.tjcivil.com BASIN DESIGNATION A 2 YR RUNOFF COEFFICIENT 1.2 70 100 YR RUNOFF COEFFICIENT BASIN AREA 70 EX STM MH (ACRES) RIM: 4970.04' EX STM MH DESIGN POINT EAST SUNIGA ROAD 36" RCP INV. (W): 4957.52' RIM: 4968.28' 3 (115' ROW) 36" RCP INV. (E): 4957.31' 24" RCP INV. (S): 4958.05' 1 4" PVC INV. (N): 4965.08' 36" RCP INV. (W): 4957.08' 3 36" RCP INV. (E): 4957.05' 3 EX VERTICAL CURB �c)� �T EX STORM INLET -w-www-^w w- `. 4970 -- ---.- - -- -. . ` ..z w-.w� wow- •w. :w-:w -w-w w,--w-w-w �w=:w w=w w-W :=w=w=w:�w�=�w� W. wTw- ma �. �'_ - --- -- --- ----. � - - - - - --- -- -- '� . �. - s_-_- _- 4969 ' O x-+ QCN =_ x x x x x x x x x x X x -x x`_ x X X X - X x� x x x x x Xx -5�-- _ 4971 -__�- _ 14970- x X x x -- -- _ -ST ST ST -ST ST 5T'' ST -y T ST -Sr.�-ST -�ST-ST $T..-LL ST` �T -57--=-:ST- =---�T s.cr - \ ------ x X . . - :. 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N1=15 :M-16 M-17 M=18. ..M-20 I I ' I EX GUjETER PAN � I Z RUNOFF SUMMARY 20 10 0 20 40 DESIGN POINT BASIN AREA 2 YR CxCf 2 YR RUNOFF 100 YR CxCf 100 YR RUNOFF I SCALE: 1" = 20' (ACRES) (CFS) (CFS) 1 A 0.16 0.65 0.31 0.79 1.28 2 B 0.47 0.92 1.23 1.00 4.65 a 3 C 0.11 0.33 0.09 0.40 0.36 .o 4 D 0.06 0.41 0.07 0.49 0.28 0 / o 0 U I CD 0 a� w m U N O H a cl- E DESIGNED BY: JWA CHECKED BY: TBM N 0 N OCT PROJECT NO. 2336 N o SHEET OF 0 1 2