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HomeMy WebLinkAboutBROWNS ON HOWES - PDP/FDP - FDP140019 - SUBMITTAL DOCUMENTS - ROUND 4 - DRAINAGE REPORTFINAL DRAINAGE REPORT Brownes on Howes Fort Collins, Colorado February 18, 2015 Prepared for: Maxiiimo Development Group 706 S. College Avenue, Suite 201 Fort Collins, CO 8024 Prepared by: 301 North Howes Street, Suite 100 Fort Collins, Colorado 80521 Phone: 970.221.4158 Fax: 970.221.4159 www.northernengineering.com Project Number: 1033-001 P This Drainage Report is consciously provided as a PDF. Please consider the environment before printing this document in its entirety. When a hard copy is absolutely necessary, we recommend double-sided printing. February 18, 2015 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Final Drainage Report for Brownes on Howes Dear Staff: Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report for your review. This report accompanies the 11.19.14 Preliminary/Final Development Review submittal for the proposed Brownes on Howes. Comments from the Preliminary Review Letter dated September 2, 2014 have been addressed. Written responses thereto can be found in the comprehensive response to comments letter on file with Current Planning. This report has been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM), and serves to document the stormwater impacts associated with the proposed Brownes on Howes project. We understand that review by the City is to assure general compliance with standardized criteria contained in the FCSCM. If you should have any questions as you review this report, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Nicholas W. Haws, PE Cody Snowdon Project Manager Project Engineer Brownes on Howes Preliminary Drainage Report TABLE OF CONTENTS I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1 A. Location ....................................................................................................................................... 1 B. Description of Property ................................................................................................................ 2 C. Floodplain .................................................................................................................................... 3 II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 5 A. Major Basin Description ............................................................................................................... 5 B. Sub-Basin Description .................................................................................................................. 5 III. DRAINAGE DESIGN CRITERIA ................................................................................... 5 A. Regulations .................................................................................................................................. 5 B. Four Step Process ........................................................................................................................ 5 C. Development Criteria Reference and Constraints ......................................................................... 6 D. Hydrological Criteria .................................................................................................................... 7 E. Hydraulic Criteria ......................................................................................................................... 7 F. Floodplain Regulations Compliance .............................................................................................. 7 G. Modifications of Criteria .............................................................................................................. 7 IV. DRAINAGE FACILITY DESIGN .................................................................................... 8 A. General Concept .......................................................................................................................... 8 B. Specific Details ............................................................................................................................. 9 V. CONCLUSIONS ........................................................................................................ 9 A. Compliance with Standards .......................................................................................................... 9 B. Drainage Concept ...................................................................................................................... 10 References ....................................................................................................................... 11 APPENDICES: APPENDIX A – Hydrologic Computations APPENDIX B – Hydraulic Computations B.1 – Storm Sewers B.2 – Inlets B.3 – Detention Facilities APPENDIX C – Water Quality Design Computations APPENDIX D – Erosion Control Report Brownes on Howes Preliminary Drainage Report LIST OF TABLES AND FIGURES: Figure 1 – Aerial Photograph ................................................................................................ 2 Figure 2– Proposed Site Plan ................................................................................................ 3 Figure 3 – Existing City Floodplains ....................................................................................... 4 MAP POCKET: C400 - Drainage Exhibit Brownes on Howes Preliminary Drainage Report 1 I. GENERAL LOCATION AND DESCRIPTION A. Location 1. Vicinity Map 2. Brownes on Howes project is located in the southwest quarter of Section 11, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. 3. The project site is located north of Maple Street on the west side of Howes Street. 4. Currently the existing lot does not have any stormwater or water quality facilities. The project primarily consists of a gravel parking area and one existing building. The remaining area consists of a convenient store and surrounding landscape areas. The project site is composed of 39% imperviousness. The existing site all drains from the southwest corner of the property to the northeast corner and into Howes Street. 5. The project is currently border to the south by a commercial building, west by a public alley, north by a single-family residence and east by Howes Street. Brownes on Howes Preliminary Drainage Report 2 B. Description of Property 1. Brownes on Howes is approximately 0.436 net acres. Figure 1 – Aerial Photograph 2. Brownes on Howes consists of two properties with one existing structure located in the northwest corner of the northern lot. The remainder of the lot consists of gravel parking area for both the residence to the north and the commercial building to the south. The alley located to the west of the property drains onto the property and this runoff and all runoff generated from the project site is routed to the northeast corner of the northern property and discharged directly into Howes Street. 3. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey, 100 percent of the site consists of Paoli fine sandy loam, which falls into Hydrologic Soil Groups B. 4. The proposed development will include the demolition of the existing structure and removal of the existing gravel parking area. The proposed site will include two large building, each being divided into three single family attached units with an access drive located to the north composed of both permeable pavers and concrete. The section of drive constructed of permeable pavers will act as the projects water quality and detention facility. SITE Brownes on Howes Preliminary Drainage Report 3 Figure 2– Proposed Site Plan 5. No irrigation facilities are known to be within the property limits. 6. The project site is within the Downtown (D) Zoning District. The proposed project is not requesting a change in the land use. C. Floodplain 1. The subject property is not located in a FEMA or City regulatory floodplain. 2. The FEMA Panel 0801010979H, shown below, illustrates the proximity of the project site to the nearest FEAM delineated regulatory floodplain. It is noted that the vertical datum utilized for site survey work is the City of Fort Collins Benchmark #1- 13 (Elevation = 4976.58, Fort Collins NVGD 29 – Unadjusted) Brownes on Howes Preliminary Drainage Report 4 Figure 3 – Existing FEMA Floodplains Figure 4 – Existing City Floodplains Brownes on Howes Preliminary Drainage Report 5 II. DRAINAGE BASINS AND SUB-BASINS A. Major Basin Description 1. Brownes on Howes is located within the Old Town Basin, which is located primarily in Old Town Fort Collins. B. Sub-Basin Description 1. The property historically drains from the southwest corner of the southern lot to the northeast corner of the northern lot. Stormwater is routed via overland flow across the existing parking area. The project has been subdivided into two basins; Basin H1 and Basin OS 1. Basin OS represents the area within the proposed project that will be released undetained. Stormwater is historically discharged directly into Howes street (0.37 cfs for the 2-year storm and 1.78 cfs for the 100-year event), which excludes the proposed area that will be discharged directly into Howes Street. A more detailed description of the projects proposed drainage patterns follows in Section IV.A.4., below. 2. No drainage is routed onto the property from the east, north or south. There is a public alley that runs along the western boundary and drains to a low point located north of the property. This alley currently does not include curb and gutter and all the runoff generated from the western half is routed through sheetflow to the properties to the east. The amount of runoff is minimal, but is reflected within the historic runoff calculations. A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of this report. III. DRAINAGE DESIGN CRITERIA A. Regulations There are no optional provisions outside of the FCSCM proposed with the Brownes on Howes Project B. Four Step Process The overall stormwater management strategy employed with the Brownes on Howes project utilizes the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters. The following is a description of how the proposed development has incorporated each step. Step 1 – Employ Runoff Reduction Practices Several techniques have been utilized with the proposed development to facilitate the reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the current use by implementing multiple Low Impact Development (LID) strategies including: Providing vegetated open areas along the south and east portion of the site to reduce the overall impervious area and to minimize directly connected impervious areas (MDCIA). Routing flows, to the extent feasible, through bio-swale to increase time of concentration, promote infiltration and provide initial water quality. Brownes on Howes Preliminary Drainage Report 6 Providing permeable paver areas with underground detention area to increase time of concentration promote infiltration and provide water quality. Routing runoff from the proposed roofs into individual planter beds to promote infiltration. Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release The efforts taken in Step 1 will facilitate the reduction of runoff; however, this development will still generate stormwater runoff that will require additional BMPs and water quality. Stormwater generated from the southern portion of the building will be routed through individual planter beds. Overflow from these planting beds and the proposed walk will drain into a bio-swale and into a proposed storm collection system. This storm collection system is proposed to discharge directly into the proposed storm system. Stormwater generated from the northern portion of the building will be routed through planter beds and into a proposed storm collection system. This storm collection system is proposed to discharge directly into the detention vault. The stormwater generated from the proposed parking area will be routed via overland flow to the permeable paver area. Step 3 – Stabilize Drainageways As stated in Section I.B.5, above, there are no major drainageways in or near the subject site. While this step may not seem applicable to Brownes on Howes, the proposed project indirectly helps achieve stabilized drainageways nonetheless. Once again, site selection has a positive effect on stream stabilization. By repurposing an already developed, under- utilized site with existing stormwater infrastructure, combined with LID, the likelihood of bed and bank erosion is greatly reduced. Furthermore, this project will pay one-time stormwater development fees, as well as ongoing monthly stormwater utility fees, both of which help achieve Citywide drainageway stability. Step 4 – Implement Site Specific and Other Source Control BMPs. This step typically applies to industrial and commercial developments and is not applicable for this project, but the a following site specific source control has been included: A localized trash enclosure at the rear of the building for the disposal of office waste. C. Development Criteria Reference and Constraints 1. There are no known drainage studies for the existing properties. 2. There are no known drainage studies for any adjacent properties that will have any effect on the Brownes on Howes project. 3. The subject property is essentially an "in-fill" development project as the property is surrounded by currently developed properties. As such, several constraints have been identified during the course of this analysis that will impact the proposed drainage system including: Existing elevations along the east and west property lines adjacent to the public alley and Howes Street will be maintained. Existing elevations along the north and the south property lines will also be maintained. Brownes on Howes Preliminary Drainage Report 7 Existing elevations and vegetation on the east side of the subject property will be preserved. As previously mentioned, overall drainage patterns of the existing site will be maintained. D. Hydrological Criteria 1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations associated with the Regency Lakeview development. Tabulated data contained in Table RA-7 has been utilized for Rational Method runoff calculations. 2. The Rational Method has been employed to compute stormwater runoff utilizing coefficients contained in Tables RO-11 and RO-12 of the FCSCM. 3. The Rational Formula-based Modified Federal Aviation Administration (FAA) procedure has been utilized for detention storage calculations. 4. Three separate design storms have been utilized to address distinct drainage scenarios. A fourth design storm has also been computed for comparison purposes. The first design storm considered is the 80th percentile rain event, which has been employed to design the project’s water quality features. The second event analyzed is the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The third event considered is the “Major Storm,” which has a 100-year recurrence interval. The fourth storm computed, for comparison purposes only, is the 10-year event. 5. No other assumptions or calculation methods have been used with this development that are not referenced by current City of Fort Collins criteria. E. Hydraulic Criteria 1. As previously noted, the subject property historically drains into Howes Street. The majority of the site drains stormwater via overland flow. 2. All drainage facilities proposed with the Brownes on Howes project are designed in accordance with criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District’s (UDFCD) Urban Storm Drainage Criteria Manual. 3. As stated in Section I.C.1, above, the subject property is not located within a FEMA regulatory floodplain. 4. The Brownes on Howes project does not propose to modify any natural drainageways. F. Floodplain Regulations Compliance 1. As previously mentioned, all structures are located outside of any FEMA 100-year floodplain, and thus are not subject to any floodplain regulations. G. Modifications of Criteria 1. The proposed Brown on Howes development is not requesting any modification at this time. The proposed Brown on Howes is proposing underground detention with this project. This detailed study shall act as a written request for approval of our system per Section 4.16. Brownes on Howes Preliminary Drainage Report 8 IV. DRAINAGE FACILITY DESIGN A. General Concept 1. The main objectives of the Brownes on Howes drainage design are to maintain existing drainage patterns and ensure no adverse impacts to any adjacent properties. 2. The existing site does have off-site flows from the public alley to the west. The existing routing of this runoff of will remain and pass through the proposed project. 3. A list of tables and figures used within this report can be found in the Table of Contents at the front of the document. The tables and figures are located within the sections to which the content best applies. 4. The Brownes on Howes project is composed of two major drainage basin, designated as Basins A and Basin OS. The project further subdivided Basin A in to two (2) sub- basins, designated as Basins A1, and A2. The drainage patterns anticipated for Basin A, Basin OS and associated sub-basins are further described below. Basin A Basin A consists of all of the improvements being proposed on-site, as well as all of the improvements being proposed within the public alley. Basin A1 encompasses the northern portion of the proposed buildings and the entire drive aisle. Runoff from the roofs will be discharged via downspouts into designed planter beds with proposed inlets. The runoff from these planter beds will discharge directly into the underground detention vault. The runoff generated from the proposed alley improvements will be routed via curb and gutter into the site. All other runoff from this basin will be routed over the permeable pavers and intercepted by a combination inlet. This inlet is designed with an orifice plate to restrict flow to the existing 2-event. The stormwater intercepted by the combination inlet will back up into the proposed underground detention vault. Basin A2 encompasses the southern portion of the proposed buildings and the green belt to the south and east. Runoff from the roofs will be discharged via downspouts into designed planter beds. Any overflow from these planter beds and the runoff generated from the proposed concrete areas will discharge into a trench drain running along the proposed walk and be routed to the proposed storm sewer. Any runoff that is not capture by the trench drain will be routed into a proposed inlet located at the southeastern corner of the property. The stormwater intercepted by the proposed trench drain or inlet will be discharge directly into the paver section for water quality and ultimately into the underground detention vault. Basin OS Basin OS consists of the landscape lawn to the east of the proposed buildings. Due to the severity of the grades, the drainage will be routed directly off-site into Howes Street. This area is very minimal and the impervious area will be reduced by replacing the existing gravel parking with landscaping. This portion of the project has been excluded from the historic basin to establish a more accurate historic release rate of the project. The runoff from this basin will be decreased from historic runoff rates. A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of this report. Brownes on Howes Preliminary Drainage Report 9 B. Specific Details 1. The main drainage problem associated with this project site is the deficiency of water quality present within the existing site. Currently the entire site drains overland and discharges directly into the Howes Street without water quality. The proposed site will mitigate this issue by instituting the following water quality devices: All of the runoff generated from the proposed building will be routed through a landscape area. All improvements generated from the site will be routed through a permeable paver system or bio-swale. 2. The release rate for the undeveloped land (pre-development) was established by calculating the 2-year peak runoff rate for the entire project area excluding a portion of the proposed project that contains the front landscape area designated as Basin OS1. The total establishes the overall maximum allowable release rate, 0.37 cfs, from the project site. This release rate was utilized in the FAA procedure detention storage computations (Refer to Appendix B for these calculations). 3. The FAA method was used to size the on-site pond for quantity detention. Calculations for this area, based on the characteristics of basin A and adjusted release rate, indicated a detention volume of 4587 cu. Ft. This does not include the any Quality Capture Volume (WQCV), but this it be stored within the proposed permeable paver system. During the water quality events the water quality capture volume will release into and through the permeable paver section over 12-hours. This section is considered an infiltration section because the in-situ soils in this area are Paoli fine sandy loam. 4. The storage volume available within StormTech Vault Structure is 4784 cu. ft., which does not include the No. 2 open-graded aggregate surrounding the system. This also does not include any of the volume within the permeable paver section. 5. The emergency spillway will be located at the northeastern corner of the street entrance from Howes Street. In the event that emergency overflows occur, the drainage will flow to the northeast into Howes Street. V. CONCLUSIONS A. Compliance with Standards 1. The drainage design proposed with the Brownes on Howes project complies with the City of Fort Collins’ Stormwater Criteria Manual. The proposed Brown on Howes is proposing underground detention with this project. This detailed study shall act as a written request for approval of the proposed system per Section 4.16. 2. The drainage design proposed with the Brownes on Howes project complies with the City of Fort Collins’ Master Drainage Plan for the Old Town Basin. 3. There are no regulatory floodplains associated with the Brownes on Howes development. 4. The drainage plan and stormwater management measures proposed with the Brownes on Howes development are compliant with all applicable State and Federal regulations governing stormwater discharge. Brownes on Howes Preliminary Drainage Report 10 B. Drainage Concept 1. The drainage design proposed with this project will effectively limit potential damage associated with its stormwater runoff. Brownes on Howes will detain for the pervious area converted to impervious areas to release at the 2-year existing rate during the 100-year storm. 2. The proposed Brownes on Howes development will not impact the Master Drainage Plan recommendations for the Old Town major drainage basin Brownes on Howes Preliminary Drainage Report 11 References 1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities, November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services. 2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code. 3. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007. 4. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture. 5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008. APPENDIX A HYDROLOGIC COMPUTATIONS CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: Browns on Howes Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: C. Snowdon Asphalt ……....……………...……….....…...……………….………………………………….. 0.95 100% Date: Concrete …….......……………….….……….………………..….………………………………… 0.95 90% Gravel ……….…………………….….…………………………..……………………………….. 0.50 40% Roofs …….…….………………..……………….…………………………………………….. 0.95 90% Pavers…………………………...………………..…………………………………………….. 0.40 22% Lawns and Landscaping Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0% Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf = 1.00 100-year Cf = 1.25 Basin ID Basin Area (s.f.) Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of Lawns and Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient Composite % Imperv. H1 19663 0.45 0.02 0.00 0.02 0.35 0.06 0.49 0.49 0.62 40% OS1 2745 0.06 0.00 0.01 0.00 0.03 0.02 0.47 0.47 0.58 36% HISTORIC COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS Notes November 19, 2014 10-year Cf = 1.00 **Soil Classification of site is Sandy Loam** Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I. Page 1 of 10 D:\Projects\1033-001\Drainage\Hydrology\1033-001_Rational-Calcs.xlsx\Hist-C-Values Overland Flow, Time of Concentration: Project: Browns on Howes Calculations By: Date: Gutter/Swale Flow, Time of Concentration: Tt = L / 60V Tc = Ti + Tt (Equation RO-2) Velocity (Gutter Flow), V = 20·S½ Velocity (Swale Flow), V = 15·S½ NOTE: C-value for overland flows over grassy surfaces; C = 0.25 Is Length >500' ? C*Cf (2-yr Cf=1.00) C*Cf (10-yr Cf=1.00) C*Cf (100-yr Cf=1.25) Length, L (ft) Slope, S (%) Ti 2-yr (min) Ti 10-yr (min) Ti 100-yr (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Tt (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Tt (min) 2-yr Tc Rational Method Equation: Project: Browns on Howes Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: h1 H1 0.45 19 19 16 0.49 0.49 0.62 1.65 2.82 6.41 0.37 0.63 1.78 os1 OS1 0.06 6 6 5 0.47 0.47 0.58 2.76 4.72 9.95 0.08 0.14 0.37 HISTORIC RUNOFF COMPUTATIONS Intensity, i2 (in/hr) Intensity, i10 (in/hr) Intensity, i100 (in/hr) Notes C. Snowdon November 19, 2014 Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 Design Point Basin(s) Area, A (acres) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) Flow, Q2 (cfs) Flow, Q10 (cfs) Flow, Q100 (cfs) C2 C 10 C100 Q = C f ( C )( i )( A ) Page 3 of 10 D:\Projects\1033-001\Drainage\Hydrology\1033-001_Rational-Calcs.xlsx\Hist-Direct-Runoff CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: Browns on Howes Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: Asphalt ……....……………...……….....…...……………….………………………………….0.. 95 100% Date: Concrete …….......……………….….……….………………..….………………………………… 0.95 90% Gravel ……….…………………….….…………………………..……………………………….0.. 50 40% Roofs …….…….………………..……………….…………………………………………….. 0.95 90% Pavers…………………………...………………..…………………………………………….. 0.40 22% Lawns and Landscaping Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0% Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf = 1.00 100-year Cf = 1.25 Basin ID Basin Area (s.f.) Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Lawns and Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient Composite % Imperv. A1 14745 0.338 0.027 0.098 0.145 0.000 0.041 0.028 0.82 0.82 1.00 73% A2 4918 0.113 0.000 0.034 0.061 0.000 0.000 0.018 0.82 0.82 1.00 76% OS1 2745 0.063 0.000 0.018 0.000 0.000 0.000 0.045 0.38 0.38 0.47 25% TOTAL 22408 0.514 0.027 0.018 0.207 0.000 0.041 0.263 0.57 0.57 0.72 45% DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I. 10-year Cf = 1.00 Overland Flow, Time of Concentration: Project: Browns on Howes Calculations By: Date: Gutter/Swale Flow, Time of Concentration: Tt = L / 60V Tc = T i + Tt (Equation RO-2) Velocity (Gutter Flow), V = 20·S ½ Velocity (Swale Flow), V = 15·S ½ NOTE: C-value for overland flows over grassy surfaces; C = 0.25 Is Length >500' ? C*Cf (2-yr Cf=1.00) C*Cf (10-yr Cf=1.00) C*Cf (100-yr Cf=1.25) Length, L (ft) Slope, S (%) Ti 2-yr (min) Ti 10-yr (min) Ti 100-yr (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Tt (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Rational Method Equation: Project: Browns on Howes Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: a1 A1 0.34 5 5 5 0.82 0.82 1.00 2.85 4.87 9.95 0.79 1.35 3.37 a2 A2 0.11 5 5 5 0.82 0.82 1.00 2.85 4.87 9.95 0.27 0.45 1.12 os1 OS1 0.06 5 5 5 0.38 0.38 0.47 2.85 4.87 9.95 0.07 0.12 0.29 DEVELOPED RUNOFF COMPUTATIONS C100 Notes Design Point Flow, Q100 (cfs) Flow, Q2 (cfs) 10-yr Tc (min) 2-yr Tc (min) C2 Flow, Q10 (cfs) Intensity, i100 (in/hr) Basin(s) C. Snowdon November 19, 2014 Intensity, i10 (in/hr) Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 C10 Area, A (acres) Intensity, i2 (in/hr) 100-yr Tc (min) Q = C f ( C )( i )( A ) Page 6 of 10 D:\Projects\1033-001\Drainage\Hydrology\1033-001_Rational-Calcs.xlsx\Direct-Runoff CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: Browns on Howes Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: Asphalt ……....……………...……….....…...……………….………………………………….. 0.95 100% Date: Concrete …….......……………….….……….………………..….………………………………… 0.95 90% Gravel ……….…………………….….…………………………..……………………………….. 0.50 40% Roofs …….…….………………..……………….…………………………………………….. 0.95 90% Pavers…………………………...………………..…………………………………………….. 0.40 22% Lawns and Landscaping Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0% Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf = 1.00 100-year Cf = 1.25 Design Point Basin IDs Basin Area (s.f.) Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Lawns and Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient Composite % Imperv. a1 A1-A2 19663 0.45 0.03 0.13 0.21 0.00 0.04 0.091 0.83 0.83 1.00 73% COMBINED DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS November 19, 2014 **Soil Classification of site is Sandy Loam** 10-year Cf = 1.00 Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I. C. Snowdon Overland Flow, Time of Concentration: Project: Browns on Howes Calculations By: Date: Gutter/Swale Flow, Time of Concentration: Tt = L / 60V Tc = T i + Tt (Equation RO-2) Velocity (Gutter Flow), V = 20·S ½ Velocity (Swale Flow), V = 15·S ½ NOTE: C-value for overland flows over grassy surfaces; C = 0.25 Is Length >500' ? C*Cf (2-yr Cf=1.00) C*Cf (10-yr Cf=1.00) C*Cf (100-yr Cf=1.25) Length, L (ft) Slope, S (%) Ti 2-yr (min) Ti 10-yr (min) Ti 100-yr (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Tt (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Rational Method Equation: Project: Browns on Howes Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: a1 A1-A2 0.45 5 5 5 0.83 0.83 1.00 2.85 4.87 9.95 1.1 1.8 4.5 C100 Intensity, i2 (in/hr) Intensity, i10 (in/hr) Intensity, i100 (in/hr) COMBINED DEVELOPED RUNOFF COMPUTATIONS C. Snowdon November 19, 2014 Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 Design Point Basin(s) Area, A (acres) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) Flow, Q2 (cfs) Flow, Q10 (cfs) Flow, Q100 (cfs) C2 C10 Q = C f ( C )( i )( A ) Page 9 of 10 D:\Projects\1033-001\Drainage\Hydrology\1033-001_Rational-Calcs.xlsx\Comb-Direct-Runoff DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C100 2-yr Tc (min) 100-yr Tc (min) Q2 (cfs) Q100 (cfs) a1 A1 0.34 0.82 1.00 5.0 5.0 0.79 3.37 a2 A2 0.11 0.82 1.00 5.0 5.0 0.27 1.12 os1 OS1 0.06 0.38 0.47 5.0 5.0 0.07 0.29 DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C100 2-yr Tc (min) 100-yr Tc (min) Q2 (cfs) Q100 (cfs) h1 H1 0.45 0.49 0.62 19.5 15.5 0.37 1.78 os1 OS1 0.06 0.47 0.58 5.7 5.0 0.08 0.37 Page 10 of 10 D:\Projects\1033-001\Drainage\Hydrology\1033-001_Rational-Calcs.xlsx\SUMMARY-TABLE APPENDIX B HYDRAULIC COMPUTATIONS B.1 – Storm Sewers (Future Use) B.2 – Inlets (Future Use) B.3 – Detention Facilities APPENDIX B.1 STORM SEWERS (RESERVED FOR FUTURE USE) APPENDIX B.2 INLETS (RESERVED FOR FUTURE USE) Worksheet Protected Project: Inlet ID: Design Flow: ONLY if already determined through other methods: Minor Storm Major Storm (local peak flow for 1/2 of street, plus flow bypassing upstream subcatchments): *Q = 1.0 4.5 cfs * If you entered a value here, skip the rest of this sheet and proceed to sheet Q-Allow) Geographic Information: (Enter data in the blue cells): Subcatchment Area = Acres Percent Imperviousness = % NRCS Soil Type = A, B, C, or D Slope (ft/ft) Length (ft) Overland Flow = Gutter Flow = Rainfall Information: Intensity I (inch/hr) = C1 * P 1 / ( C2 + Tc ) ^ C 3 Minor Storm Major Storm Design Storm Return Period, Tr = years Return Period One-Hour Precipitation, P1 = inches C1 = C2 = C3 = User-Defined Storm Runoff Coefficient (leave this blank to accept a calculated value), C = User-Defined 5-yr. Runoff Coefficient (leave this blank to accept a calculated value), C5 = Bypass (Carry-Over) Flow from upstream Subcatchments, Qb = cfs Total Design Peak Flow, Q = 1.0 4.5 cfs Site Type: <--- FILL IN THIS SECTION OR… FILL IN THE SECTIONS BELOW. <--- DESIGN PEAK FLOW FOR ONE-HALF OF STREET BY THE RATIONAL METHOD Design Flow = Gutter Flow + Carry-over Flow Brownes on Howes Design Point A1 Site is Urban Site is Non-Urban Show Details Inlet DP A1.xls, Q-Peak 1/21/2015, 3:26 PM Project = Inlet ID = Design Information (Input) MINOR MAJOR Type of Inlet Inlet Type = Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal = 2.00 2.00 inches Number of Unit Inlets (Grate or Curb Opening) No = 1 1 Flow Depth outside of Local Depression at Inlet Flow Depth = 6.0 12.0 inches Grate Information MINOR MAJOR Length of a Unit Grate Lo (G) = 3.00 3.00 feet Width of a Unit Grate Wo = 1.73 1.73 feet Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = 0.43 0.43 Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = 0.50 0.50 Grate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = 3.30 3.30 Grate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = 0.60 0.60 Curb Opening Information MINOR MAJOR Length of a Unit Curb Opening Lo (C) = 3.00 3.00 feet Height of Vertical Curb Opening in Inches Hvert = 6.50 6.50 inches Height of Curb Orifice Throat in Inches Hthroat = 5.25 5.25 inches Angle of Throat (see USDCM Figure ST-5) Theta = 0.00 0.00 degrees Side Width for Depression Pan (typically the gutter width of 2 feet) Wp = 2.00 2.00 feet Clogging Factor for a Single Curb Opening (typical value 0.10) Cf (C) = 0.10 0.10 Curb Opening Weir Coefficient (typical value 2.3-3.6) Cw (C) = 3.70 3.70 Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.66 0.66 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition) Qa = 3.2 9.0 cfs Inlet Capacity IS GOOD for Minor and Major Storms (>Q PEAK) Q PEAK REQUIRED = 1.0 4.5 cfs INLET IN A SUMP OR SAG LOCATION Brownes on Howes Design Point A1 CDOT/Denver 13 Combination H-VertCurb H- W Lo (C) Lo (G) WP Wo Inlet DP A1.xls, Inlet In Sump 1/21/2015, 3:26 PM 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 10" Dome Grate Inlet Capacity Chart APPENDIX B.3 DETENTION FACILITIES Pond No : a1 100-yr 1.00 5.00 min 4587 ft3 0.45 acres 0.11 ac-ft Max Release Rate = 0.37 cfs Time (min) Ft Collins 100-yr Intensity (in/hr) Inflow Volume (ft3) Outflow Adjustment Factor Qav (cfs) Outflow Volume (ft3) Storage Volume (ft3) 5 9.950 1346 1.00 0.37 111 1235 10 7.720 2089 0.75 0.28 167 1923 15 6.520 2646 0.67 0.25 222 2424 20 5.600 3031 0.63 0.23 278 2753 25 4.980 3369 0.60 0.22 333 3036 30 4.520 3669 0.58 0.22 389 3281 35 4.080 3864 0.57 0.21 444 3420 40 3.740 4048 0.56 0.21 500 3549 45 3.460 4213 0.56 0.21 555 3658 50 3.230 4370 0.55 0.20 611 3760 55 3.030 4510 0.55 0.20 666 3844 60 2.860 4643 0.54 0.20 722 3922 65 2.720 4784 0.54 0.20 777 4007 70 2.590 4906 0.54 0.20 833 4073 75 2.480 5033 0.53 0.20 888 4145 80 2.380 5152 0.53 0.20 944 4209 85 2.290 5267 0.53 0.20 999 4268 90 2.210 5382 0.53 0.20 1055 4328 95 2.130 5476 0.53 0.19 1110 4366 100 2.060 5574 0.53 0.19 1166 4409 105 2.000 5683 0.52 0.19 1221 4462 110 1.940 5775 0.52 0.19 1277 4498 115 1.890 5881 0.52 0.19 1332 4549 120 1.840 5975 0.52 0.19 1388 4587 *Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2. DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF Input Variables Results Required Detention Volume Fort Collins, Colorado 1033-001 Browns on Howes Project Number : Project Name : Underground Detention A = Project Information: Project Name: Browns on Howes Location: Fort Collins, CO Date: 8/6/2014 Engineer: C. Snowdon StormTech RPM: MC-4500 Site Calculator System Requirements System Sizing Units Imperial Number of Chambers Required 31 each Required Storage Volume 4523 CF Number of End Caps Required 2 each Stone Porosity (Industry Standard = 40%) 30 % Bed Size (including perimeter stone) 1,363 square feet Stone Above Chambers (12 inch min.) 12 inches Stone Required (including perimeter stone) 306 tons Stone Foundation Depth (9 inch min.) 9 inches Volume of Excavation 391 cubic yards Average Cover over Chambers (24 inch min.) 24 inches Non-woven Filter Fabric Required (20% Safety Factor) 619 square yards Bed size controlled by WIDTH or LENGTH? LENGTH Length of Isolator Row 131.9 feet Limiting WIDTH or LENGTH dimension 170 feet Woven Isolator Row Fabric (20% Safety Factor) 362 square yards Storage Volume per Chamber 148.5 CF Storage Volume per End Cap 90.4 CF Installed Storage Volume 4,784 cubic feet 24 Maximum Length = 170 feet inches 1 row of 31 chambers 12 inches Maximum Length = 131.9 feet Maximum Width = 10.3 feet 9 inches Controlled by Length 60" (1524 mm) 24" (610 mm) MIN. 7.0' (2.13 m) MAX. 100" (2540 mm) Project Title Date: Project Number Calcs By: Client Pond Outlet Q = 0.41 cfs C = 0.65 Q = Release Rate (cfs) Eh = 4980.07 ft C = Discharge Coefficients (unitless) Ei = 4975.07 ft Aa = Area Allowed of Opening (ft2) Ec = 4975.18 ft Circular g = Gravity (32.2 ft/s2) Ec = 4975.18 ft Rectangular Eh = High Water Surface Elevation (ft) Ei = Elevation of Outlet Invert (ft) 0.035151395 ft2 Ec = Elevation of Outlet Centroid (ft) 5.061801 in2 Orifice Size (in.) 2 - 1/2 in. Area (in2) 5.06 sq-in Q 0.41 cfs Orifice Height (in.) 2 - 1/2 in. Orifice Width (in.) 2 in. Area (in2) 5.06 sq-in Q 0.41 cfs Aa = Circular Orifice 10-Year Orifice Rectangular Orifice 10-Year Orifice Brownes on Howes 11.19.14 1033-001 Cody Snowdon Maxiiimo Combination Inlet APPENDIX C WATER QUALITY DESIGN COMPUTATIONS Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Type of Permeable Pavement Section A) What type of section of permeable pavement is used? (Based on the land use and activities, proximity to adjacent structures and soil characteristics.) B) What type of wearing course? 2. Required Storage Volume A) Effective Imperviousness of Area Tributary to Permeable Pavement, Ia I a = 100.0 % B) Tributary Area's Imperviousness Ratio (I = Ia / 100) i = 1.000 C) Tributary Watershed Area ATotal = 4,658 sq ft (including area of permeable pavement system) D) Area of Permeable Pavement System APPS = 1,954 sq ft (Minimum recommended permeable pavement area = 1553 sq ft) E) Impervious Tributary Ratio RT = 1.4 (Contributing Imperviuos Area / Permeable Pavement Ratio) F) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 155 cu ft (WQCV = (0.8 * (0.91 * i 3 - 1.19 * i 2 + 0.78 * i) / 12) * Area) G) Is flood control volume being added? H) Total Volume Needed VTotal = cu ft 3. Depth of Reservoir A) Minimum Depth of Reservoir Dmin = 12.0 inches (Minimum recommended depth is 6 inches) B) Is the slope of the reservoir/subgrade interface equal to 0%? C) Porosity (Porous Gravel Pavement < 0.3, Others < 0.40) P = 0.40 D) Slope of the Base Course/Subgrade Interface S = ft / ft E) Length Between Lateral Flow Barriers L = ft F) Volume Provided Based on Depth of Base Course V = 716 cu ft Flat or Stepped: V = P * ((Dmin-1)/12) * Area Sloped: V = P * [(Dmin - (D min - 6*SL-1)) / 12] * Area 4. Lateral Flow Barriers A) Type of Lateral Flow Barriers B) Number of Permeable Pavement Cells Cells = 1 5. Perimeter Barrier A) Is a perimeter barrier provided on all sides of the pavement system? (Recommeded for PICP, concrete grid pavement, or for any no-infiltration section.) Browns on Howes Design Procedure Form: Permeable Pavement Systems (PPS) Cody Snowdon Northern Engineering January 21, 2015 Choose One No Infiltration Sheet 2 of 2 Designer: Company: Date: Project: Location: 6. Filter Material and Underdrain System A) Is the underdrain placed below a 6-inch thick layer of CDOT Class C filter material? B) Diameter of Slotted Pipe (slot dimensions per Table PPs-2) Detention Vault no Underdrain C) Distance from the Lowest Elevation of the Storage Volume y = 0.3 ft (i.e. the bottom of the base course to the center of the orifice) 7. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is there a minimum 30 mil thick impermeable PVC geomembrane liner on the bottom and sides of the basin, extending up to the top of the base course? B) CDOT Class B Separator Fabric 8. Outlet (Assumes each cell has similar area, subgrade slope, and length between lateral barriers (unless subgrade is flat). Calculate cells individually where this varies.) A) Depth of WQCV in the Reservoir DWQCV = 2.38 inches (Elevation of the Flood Control Outlet) B) Diameter of Orifice for 12-hour Drain Time DOrifice = 0.44 inches (Use a minimum orifice diameter of 3/8-inches) Notes: Browns on Howes Design Procedure Form: Permeable Pavement Systems (PPS) Cody Snowdon Northern Engineering January 21, 2015 Choose One YES NO Choose One 4-inch 6-inch Choose One Choose One YES NO Placed above the liner Placed above and below the liner N/A 1033-001 UD-BMP_v3.02.xls, PPS 1/21/2015, 3:29 PM APPENDIX D EROSION CONTROL REPORT Brownes on Howes Preliminary Erosion Control Report A comprehensive Erosion and Sediment Control Plan (along with associated details) will be included with the final construction drawings. It should be noted, however, that any such Erosion and Sediment Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of the BMPs depicted, and additional or different BMPs from those included may be necessary during construction, or as required by the authorities having jurisdiction. It shall be the responsibility of the Contractor to ensure erosion control measures are properly maintained and followed. The Erosion and Sediment Control Plan is intended to be a living document, constantly adapting to site conditions and needs. The Contractor shall update the location of BMPs as they are installed, removed or modified in conjunction with construction activities. It is imperative to appropriately reflect the current site conditions at all times. The Erosion and Sediment Control Plan shall address both temporary measures to be implemented during construction, as well as permanent erosion control protection. Best Management Practices from the Volume 3, Chapter 7 – Construction BMPs will be utilized. Measures may include, but are not limited to, silt fencing along the disturbed perimeter, gutter protection in the adjacent roadways and inlet protection at proposed storm inlets. Vehicle tracking control pads, spill containment and clean-up procedures, designated concrete washout areas, dumpsters, and job site restrooms shall also be provided by the Contractor. Grading and Erosion Control Notes can be found on Sheet CS2 of the Utility Plans. The Utility Plans at final design will also contain a full-size Erosion Control Plan as well as a separate sheet dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the Contractor shall be aware of, and adhere to, the applicable requirements outlined in any existing Development Agreement(s) of record, as well as the Development Agreement, to be recorded prior to issuance of the Development Construction Permit. Also, the Site Contractor for this project will be required to secure a Stormwater Construction General Permit from the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater Program, before commencing any earth disturbing activities. Prior to securing said permit, the Site Contractor shall develop a comprehensive StormWater Management Plan (SWMP) pursuant to CDPHE requirements and guidelines. The SWMP will further describe and document the ongoing activities, inspections, and maintenance of construction BMPs. Brownes on Howes Preliminary Erosion Control Report MAP POCKET DR1 – OVERALL DRAINAGE EXHIBIT C S C S C S VAULT CABLE X X X X X X X X X X OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE OHE ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD DN DN DN DN DN DN DN DN DN HOWES STREET (60' PUBLIC ROW) 6' EXISTING UTILITY EASEMENT 4' PUBLIC SIDEWALK PUBLIC ALLEY (20' PUBLIC ROW) PROPERTY LINE PROPERTY LINE ROW LINE ROW LINE EXISTING DRIVEWAY 5' PUBLIC SIDEWALK acres A1 0.82 0.34 1.00 acres A2 0.82 0.11 1.00 a1 a2 10" DOME GRATE W/ 10" DRAIN BASIN MONITORING WELL COMBINATION INLET w/ ORIFICE VAULT CABLE X X X X X X X X X X X X X X X X X X X X X X X G G G G G G G G ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST a1 acres H1 0.49 0.45 0.62 acres OS1 0.47 0.06 0.58 EXISTING WOODEN BUILDING HOWES STREET (60' PUBLIC ROW) EXISTING 6' UTILITY EASEMENT PUBLIC ALLEY (20' PUBLIC ROW) PROPERTY LINE PROPERTY LINE ROW LINE ROW LINE EXISTING DRIVEWAY EXISTING ONE-STORY WOOD BUILDING EXISTING GRAVEL PARKING AREA EXISTING GRAVEL PARKING AREA ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST No. Revisions: By: Date: REVIEWED BY: N. Haws DESIGNED BY: DRAWN BY: SCALE: DATE: 02.18.15 PROJECT: 1033-001 Sheet Of 18 Sheets BROWNES ON HOWES DRAWING FILENAME: D:rojects\1033-001\Dwg\Drng\1033-001_HIST-DRNG.dwg LAYOUT NAME: C8.01 DATE: Feb 18, 2015 - 2:21pm CAD OPERATOR: cody LIST OF XREFS: [1033-001_xTopo] [1033-001_xAdj] [1033-001_xExst] [NES-xborder] These drawings are instruments of service provided by Northern Engineering Services, Inc. and are not to be used for any type of construction unless signed and sealed by a Professional Engineer in the employ of Northern Engineering Services, Inc. NOT FOR CONSTRUCTION REVIEW SET 301 North Howes Street, Suite 010 Fort Collins, Colorado 80521 E N G I N E E R I N G N O R T H E RN PHONE: 970.221.4158 FAX: 970.221.4159 www.northernengineering.com 02.18.15 C8.01 HISTORIC DRAINAGE EXHIBIT C. Snowdon C. Snowdon 1" = 10' FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION LEGEND: NOTES: CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. Call before you dig. R City Engineer Date Date Date Date Date Stormwater Utility Parks & Recreation Traffic Engineer Date APPROVED: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: Water & Wastewater Utility City of Fort Collins, Colorado UTILITY PLAN APPROVAL Environmental Planner NORTH EXISTING CONTOUR 5013 EXISTING VERTICAL PROPOSED OVERLAND FLOW DIRECTION CURB & GUTTER EXISTING STORM SEWER LINE PROPERTY BOUNDARY EXISTING INLET GRATE acres H1 0.56 1.79 0.86 h1 BASIN ACREAGE DESIGN POINT BASIN DELINEATION MAJOR RUNOFF COEFFICIENT PROPOSED BASIN LINES ST ( IN FEET ) 1 inch = ft. 10 0 10 Feet 10 20 30 MINOR RUNOFF COEFFICIENT PLATE ON EASTERN FACE OF BOX OVER OUTLET PIPE 6" PERFORATED UNDERDRAIN LANDSCAPE ISLAND W/ 8" DOME GRATE LANDSCAPE ISLAND W/ 8" DOME GRATE LANDSCAPE ISLAND W/ 8" DOME GRATE LANDSCAPE ISLAND W/ 8" DOME GRATE UNDERGROUND STORAGE STRUCTURE LOT 1 LOT 2 LOT 3 LOT 4 LOT 5 LOT 6 PERMEABLE PAVERS & UNDERGROUND STORAGE acres OS1 0.38 0.06 0.47 MONITORING WELL No. Revisions: By: Date: REVIEWED BY: N. Haws DESIGNED BY: DRAWN BY: SCALE: DATE: 02.18.15 PROJECT: 1033-001 Sheet Of 18 Sheets BROWNES ON HOWES DRAWING FILENAME: D:rojects\1033-001\Dwg\Drng\1033-001_DRNG.dwg LAYOUT NAME: C8.00 DATE: Feb 18, 2015 - 2:21pm CAD OPERATOR: cody LIST OF XREFS: [1033-001_xTopo] [1033-001_xExst] [1033-001_xPgrad] [1033-001_xPutil] [1033-001_xSite] [NES-xborder] These drawings are instruments of service provided by Northern Engineering Services, Inc. and are not to be used for any type of construction unless signed and sealed by a Professional Engineer in the employ of Northern Engineering Services, Inc. NOT FOR CONSTRUCTION REVIEW SET 301 North Howes Street, Suite 010 Fort Collins, Colorado 80521 E N G I N E E R I N G N O R T H E RN PHONE: 970.221.4158 FAX: 970.221.4159 www.northernengineering.com 02.18.15 C8.00 DRAINAGE EXHIBIT C. Snowdon C. Snowdon 1" = 10' FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION LEGEND: NOTES: CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. Call before you dig. R City Engineer Date Date Date Date Date Stormwater Utility Parks & Recreation Traffic Engineer Date APPROVED: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: Water & Wastewater Utility City of Fort Collins, Colorado UTILITY PLAN APPROVAL Environmental Planner NORTH 5013 PROPOSED CONTOUR 93 PROPOSED SWALE EXISTING CONTOUR PROPOSED VERTICAL PROPOSED OVERLAND FLOW DIRECTION CURB & GUTTER EXISTING STORM SEWER LINE PROPERTY BOUNDARY EXISTING INLET GRATE PROPOSED UNDERDRAIN UD PROPOSED STORM DRAIN PROPOSED RIBBON CURB PROPOSED PERMEABLE PAVERS acres B 0.56 1.79 0.86 a BASIN ACREAGE DESIGN POINT BASIN DELINEATION MAJOR RUNOFF COEFFICIENT PROPOSED BASIN LINES ( IN FEET ) 1 inch = ft. 10 0 10 Feet 10 20 30 MINOR RUNOFF COEFFICIENT Partial Infiltration Section Full Infiltration Section Choose One YES NO Choose One YES- Flat or Stepped Installation NO- Sloped Installation Choose One Concrete Walls PVC geomembrane installed normal to flow N/A- Flat installation Other (Describe): Choose One YES NO Choose One PICP Concrete Grid Pavement Pervious Concrete Porous Gravel 1033-001 UD-BMP_v3.02.xls, PPS 1/21/2015, 3:29 PM Tc = Project Location : Design Point C = Design Storm Page 1 of 1 1033-001_DetentionVolume_FAAModified Method.xls Tt (min) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) a1 A1-A2 No 0.82 0.82 1.00 7.00 0.02 1.11 1.11 0.39 273.00 0.01 1.85 2.46 0.00 N/A N/A N/A 5 5 5 COMBINED DEVELOPED TIME OF CONCENTRATION COMPUTATIONS C. Snowdon November 19, 2014 Design Point Basin IDs Overland Flow Pipe Flow Swale Flow Time of Concentration (Equation RO-4) ( ) 3 1 1 . 87 1 . 1 * S Ti C Cf L - = Page 8 of 10 D:\Projects\1033-001\Drainage\Hydrology\1033-001_Rational-Calcs.xlsx\Comb-Tc-10-yr_&_100-yr Page 7 of 10 D:\Projects\1033-001\Drainage\Hydrology\1033-001_Rational-Calcs.xlsx\Comb-C-Values Tt (min) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) a1 A1 No 0.82 0.82 1.00 7 2.00% 1.1 1.1 0.4 273 0.86% 1.85 2.5 N/A N/A N/A 5 5 5 a2 A2 No 0.82 0.82 1.00 11 4.45% 1.0 1.0 0.4 N/A N/A N/A 146 0.52% 1.08 2.2 5 5 5 os1 OS1 No 0.38 0.38 0.47 45 11.16% 4.1 4.1 3.5 N/A N/A N/A N/A N/A N/A 5 5 5 DEVELOPED TIME OF CONCENTRATION COMPUTATIONS Gutter Flow Swale Flow Design Point Basin Overland Flow C. Snowdon November 19, 2014 Time of Concentration (Equation RO-4) ( ) 3 1 1 . 87 1 . 1 * S Ti C Cf L - = Page 5 of 10 D:\Projects\1033-001\Drainage\Hydrology\1033-001_Rational-Calcs.xlsx\Tc-10-yr_&_100-yr November 19, 2014 **Soil Classification of site is Sandy Loam** C. Snowdon Page 4 of 10 D:\Projects\1033-001\Drainage\Hydrology\1033-001_Rational-Calcs.xlsx\C-Values (min) 10-yr Tc (min) 100-yr Tc (min) h1 H1 No 0.49 0.49 0.62 210 0.60% 19.5 19.5 15.5 N/A N/A N/A N/A N/A N/A 19 19 16 os1 OS1 No 0.47 0.47 0.58 47 2.85% 5.7 5.7 4.7 N/A N/A N/A N/A N/A N/A 6 6 5 HISTORIC TIME OF CONCENTRATION COMPUTATIONS C. Snowdon November 19, 2014 Design Point Basin Overland Flow Gutter Flow Swale Flow Time of Concentration (Equation RO-4) ( ) 3 1 1 . 87 1 . 1 * S Ti C Cf L - = Page 2 of 10 D:\Projects\1033-001\Drainage\Hydrology\1033-001_Rational-Calcs.xlsx\Hist-Tc-10-yr_&_100-yr