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Home My WebLink AboutTHE HUMAN BEAN COFFEE DRIVE THRU - PDP - 28-04A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTw "V <L kor St -7 P 10 Ch Al Vill O.Vot m --- ------- - > 5w Alp Martiner Park sycam r](La St aw rj -:inPQ!t- Av- 3I Dr Brow, sitk4 st Lupine Or #***"o ; st SITE SpLjeqa Cir st 0 44. Park - z 1 It I Lr. VICINITY MAP NOT TO SCALE C) C3 Buckingham St Buckingham E Lincoln Ave Unk,N Grimns VICINITY MAP NOT TO SCALE C) C3 Buckingham St Buckingham E Lincoln Ave Unk,N Grimns APPENDIX A MAPS AND FIGURES I I I I I I I I I 6. REFERENCES 1. City of Fort Collins, "Storm Drainage Design Criteria and Construction Standards" (SDDCCS), May 1984. 2. Soil Survey of Larimer County Area, Colorado. United States Department of Agriculture Soil Conservation Service and Forest Service, 1980. 3. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria Manual", Volumes 1 and 2, dated June 2001, and Volume 3, dated September 1992. Drainage and Erosion Control Report The Human Bean - North College Avenue Page November 24, 2004 5.3 Tracking Mud on City Streets It is unlawful to track or cause to be tracked mud or other debris onto city streets or rights -of - way unless so approved by the Director of Engineering in writing. Wherever construction vehicles access routes or intersect paved public roads, provisions must be made to minimize the transport of sediment (mud) by runoff or vehicles tracking onto the paved surface. Stabilized construction entrances are required per the detail shown on the Erosion Control Plan, with base material consisting of 6" coarse aggregate. The contractor will be responsible for clearing mud tracked onto city streets on a daily basis. 5.4 Maintenance All temporary and permanent erosion and sediment control practices must be maintained and repaired as needed to assure continued performance of their intended function. Straw bale dikes or silt fences will require periodic replacement. Sediment traps (behind straw bale barriers) shall be cleaned when accumulated sediments equal approximately one-half of trap storage capacity. Maintenance is the responsibility of the developer. 5.5 Permanent Stabilization A vegetative cover shall be established within one and one-half years on disturbed areas and soil stockpiles not otherwise permanently stabilized. Vegetation shall not be considered established until a ground cover is achieved which is demonstrated to be mature enough to control soil erosion to the satisfaction of the City Inspector and to survive severe weather conditions. Drainage and Erosion Control Report Page 6 The Human Bean - North College Avenue November 24, 2004 I I 4. HYDRAULIC ANALYSIS IF 4.1 Pond Description II A proposed detention facility providing both, water quality and detention volume has been designed for this site. The proposed outlet structure is a water quality structure per USDFCD criteria_ It is designed to release at a 2-year historic rate, which is approximately 0.10 cfs. A 2-inch orifice plate on the outlet pipe regulates this release rate. The 100-year water surface elevation for the proposed pond is 4965.0'. A proposed spillway will convey flows in excess of the 100-year, into a 2-foot sidewalk chase and curb cut onto College Avenue. All water quality calculations can be found in Appendix C of this report. All pond design and outlet sizing calculations can be found in Appendix D of this report. II 5. EROSION CONTROL 5.1 Erosion and Sediment Control Measures Erosion and sedimentation will be controlled on -site by use of silt fences, straw bale barriers, gravel construction entrances, and seeding and mulch. The measures are designed to limit the overall sediment yield increase due to construction as required by the City of Fort Collins. During overlot and final grading the soil will be roughened and furrowed perpendicular to the prevailing winds. Straw bale dikes will be placed along proposed swales. Erosion control effectiveness, rainfall performance calculations and a construction schedule are provided in Appendix E. 5.2 Dust Abatement During the performance of the work required by these specifications or any operations appurtenant thereto, whether on right-of-way provided by the City or elsewhere, the contractor shall furnish all labor, equipment, materials, and means required. The Contractor shall carry out proper efficient measures wherever necessary to reduce dust nuisance. Efficient measures shall be taken to prevent dust nuisance that has originated from the contractor's operations from damaging crops, orchards, cultivated fields, and dwellings, or causing nuisance to persons. The Contractor will be held liable for any damage resulting from dust originating from his operations under these specifications on right-of-way or elsewhere. Drainage and Erosion Control Report Page 5 The Human Bean - North College Avenue November 24, 2004 3.4 Hydrologic Analysis of the Proposed Drainage Conditions The Rational Method was used to determine the 10-year and 100-year peak runoff values for each sub -basin. Runoff coefficients were assigned using Table 3-2 of the SDDCCS Manual. The Rational Method is given by: Q = CfC1A (1) where Q is the maximum rate of runoff in cfs, A is the total area of the basin in acres, Cf is the storm frequency adjustment factor, C is the runoff coefficient, and I is the rainfall intensity in inches per hour for a storm duration equal to the time of concentration. The frequency adjustment factor, Cf, is 1.0 for the initial 2-year storm and 1.25 for the major 100- year storm. The runoff coefficient is dependent on land use or surface characteristics. The rainfall intensity is selected from Rainfall Intensity Duration Curves for the City of Fort Collins (Figure 3.1 of SDDCCS). In order to utilize the Rainfall Intensity Duration Curves, the time of concentration is required. The following equation is used to determine the time of concentration to = ti + tt (2) where to is the time of concentration in minutes, ti is the initial or overland flow time in minutes, and tt is the conveyance travel time in minutes. The initial or overland flow time is calculated with the SDDCCS Manual equation: ti = [1.87(l.1 - CCf)Los]/(S)0.33 (3) where L is the length of overland flow in feet (limited to a maximum of 500 feet), S is the average slope of the basin in percent, and C and Cf are as defined previously. All hydrologic calculations associated with the sub -basins shown on the attached drainage plan are included in Appendix B of this report. Drainage and Erosion Control Report Page 4 The Human Bean - North College Avenue November 24, 2004 M chases, which discharge into the proposed detention facility at the southeast corner of the site. At this location a water quality structure with an orifice into a proposed 18-inch storm pipe that flows into a proposed manhole that connects to an existing 18" RCP storm pipe. The existing 18" storm pipe flows south and eventually discharges into the Josh Ames Ditch. 3.3 Proposed Drainage Plan A qualitative summary of the drainage patterns within each sub -basin and at each design point is provided in the following paragraphs. Certain sub -basins are combined for discussion purposes where practicable, and discussed relative to the design point to which the sub -basins drain. Discussions of the detailed design methodologies for the drainage facilities identified in this section are included in the following sections. Please refer to the drainage plan included with this report for basin locations. Runoff from Sub -basin 1 will be conveyed via overland flow, from northwest to southeast, to a 2-foot curb cut and sidewalk chase at Design Point 1. The proposed sidewalk chase releases flows south into the proposed detention facility. Runoff from Sub -basin 2 and OS-1 will be conveyed via overland and gutter flow to Design Point 2 where a 2-foot curb cut and sidewalk chase discharge flows into the proposed detention facility. Sub -basin 2 and OS-1 encompass the entire western portion of the proposed site. The proposed detention pond is the area referred to as Sub -basin 3. The runoff from this area is detained in the proposed pond. (Refer to Section 4.1 for a description of the pond.) Runoff from Sub -basin 4 is conveyed across the property directly to the south into an existing drainage swale that eventually discharges into the Josh Ames Ditch. Runoff from Sub -basin 5 will be conveyed via overland flow along the north property line to the west side of the property and ultimately south, into the existing swale, which discharges into the Josh Ames Ditch. Runoff from Sub -basin 6 will be conveyed via overland flow along the north property line to the east, onto College Avenue. Flows will ultimately be conveyed south, to the Josh Ames Ditch. Drainage and Erosion Control Report The Human Bean - North College Avenue Page 3 November 24, 2004 Site frontage is along State Highway 287 (College Avenue) and improvements to College Avenue will be constructed to bring the cross section up to the City of Fort Collins 4-lane Arterial Street Standard. 1.4 Design Criteria This report was prepared to meet or exceed the submittal requirements established in the City of Fort Collins' "Storm Drainage Design Criteria and Construction Standards" (SDDCCS), dated May 1984 and revised in January 1997. Where applicable, the criteria established in the "Urban Storm Drainage Criteria Manual" (UDFCD) dated 1984; developed by the Denver Regional Council of Governments have been utilized. The rainfall criteria used was the April 1999 amended criteria. 1.5 Master Drainage Basin The Human Bean — North College Avenue is located within the Dry Creek Master Drainage Basin. 2. HISTORIC (EXISTING) DRAINAGE The historic (existing) flows draining to or through the site consist primarily of on -site flows with some off -site flows from the adjoining property to the north and the west half of College Avenue. The overall drainage pattern for the entire site is via overland flow in a southwesterly direction at slopes that range from 0.5 to 2 percent. 3. LOCAL DEVELOPED DRAINAGE DESIGN 3.1 Method The Rational Method was used to determine the 10-year and 100-year flows for the sub - basins indicated in this drainage report. Drainage facilities were designed to convey the 100- year peak flows. The hydrologic calculations are found in Appendix B of this report. 3.2 General Flow Routing The proposed drainage pattern adheres to existing site topography and conveys flows from north to south. The proposed drainage pattern conveys flows towards two (2) sidewalk Drainage and Erosion Control Report Page 2 The Human Bean - North College Avenue November 24, 2004 1. INTRODUCTION 1.1 Project Description The Human Bean is located on North College Avenue in the southeast quarter of Section 2, Township 7 North, Range 69 West, of the 6th Principal Meridian in the City of Fort Collins, Larimer County, Colorado. The nearest intersection to the north would be Alpine Street and to the south is Vine Drive. A location map is provided in Appendix A. 1.2 Existing Site Characteristics The existing site is currently being used as a temporary storing site for U-Haul trailers and trucks. The soils in the area are reported in the Soil Survey of Larimer County Area, Colorado as being predominately Nunn Clay Loams (soil numbers 73). These soils belong to the hydrologic group C and are known to have slight to moderate erosive characteristics and slow to moderate runoff characteristics. The site historically drains at approximately one percent from northeast to southwest into the Josh Ames Ditch. The site is located within Zone AE of the Poudre River Floodplain per the FEMA Flood Insurance Rate Map for the City of Fort Collins, Larimer County, Colorado, Community Panel Number 080102 0004 C, revised March 18, 1996. Base Flood Elevations, (B.F.E.), have been determined and for this site the B.F.E. is estimated at an elevation 4965.50. The site is also located within the City 100-year floodplain, which may include ponding areas and sheet flow areas with average depths of 1-3 feet. There is a 1% annual chance that these areas will be flooded. 1.3 Proposed Site Characteristics This report defines the proposed drainage and erosion control plan for The Human Bean — North College Avenue. The plan includes consideration of all on -site and tributary off -site runoff and the design of all drainage facilities required with this development. As stated above, the existing site is located in the FEMA and City of Fort Collins floodplain. Our client is proposing to floodproof the proposed structure per City of Fort Collins Floodproofing Regulations. Drainage and Erosion Control Report ragc i The Human Bean - North College Avenue November 24, 2004 I I I 1 I I I I I I 7 L I I I TABLE OF CONTENTS PAGE 1. INTRODUCTION..................................................................................................................I 1.1 Project Description..........................................................................................................1 1.2 Existing Site Characteristics...........................................................................................1 1.3 Proposed Site Characteristics..........................................................................................1 1.4 Design Criteria................................................................................................................2 1.5 Master Drainage Basin....................................................................................................2 2. HISTORIC (EXISTING) DRAINAGE................................................................................2 3. LOCAL DEVELOPED DRAINAGE DESIGN...................................................................2 3.1 Method............................................................................................................................2 3.2 General Flow Routing.....................................................................................................2 3.3 Proposed Drainage Plan ..................................................................................................3 3.4 Hydrologic Analysis of the Proposed Drainage Conditions............................................4 4. HYDRAULIC ANALYSIS....................................................................................................5 4.1 Pond Description.............................................................................................................5 5. EROSION CONTROL...........................................................................................................5 5.1 Erosion and Sediment Control Measures........................................................................5 5.2 Dust Abatement...............................................................................................................5 5.3 Tracking Mud on City Streets.........................................................................................6 5.4 Maintenance....................................................................................................................6 5.5 Permanent Stabilization..................................................................................................6 6. REFERENCES.......................................................................................................................7 Appendix A: Maps and Figures Appendix B: Hydrologic Calculations Appendix C: Water Quality Calculations Appendix D: Detention Pond & Outlet Sizing Calculations Appendix E: Erosion Control Calculations I No Text No Text