September 6, City of Thornton 9500 Civic Center Drive Thornton, CO (303) RE: Maverik Thornton, CO - Drainage Report

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2 September 6, 2016 City of Thornton 9500 Civic Center Drive Thornton, CO (303) RE: Maverik Thornton, CO - Drainage Report As per your request, we are submitting to you the drainage report and calculations of the drainage design for the Maverik located at 112 th Avenue and Colorado Blvd in Thornton, CO. The storm water generated onsite will sheet flow to newly installed inlet boxes. The inlet boxes are equipped with a sump and snout that will filter the storm water from hydrocarbons and other pollutants. After passing through the filtration process, the storm water will be directed to an above ground open detention basin that has been sized for the WQCV, EURV, and 100-year volume per USDCM and City of Thornton criteria. Once the storm water is in the detention system, it will be gravity fed towards a control box that is equipped with an orifice plate that has been sized to control the outflow at rates of 0.10 cfs for WQCV, 0.20 cfs for EURV, and 5.20 cfs for the 100-yr volume. The storm water hydraulic and hydrology calculations including the basin sizing and orifice plate are discussed in this report. If you have any questions, or we can be of further assistance, please let us know. Sincerely, Nate Reeve, P.E. Principal Engineer Reeve & Associates, Inc. nreeve@reeve-assoc.com Anna Newman, E.I.T. Project Engineer Reeve & Associates, Inc. anewman@reeve-assoc.com Solutions You Can Build On Civil Engineering / Land Planning / Structural Engineering / Landscape Architecture / Land Surveying 5160 South 1500 West Riverdale, Utah Tel: Fax: ogden@reeve-assoc.com Website:

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4 Stormwater Drainage Design Report 1.0 Introduction 1.1 Purpose The purpose of this drainage report is to reflect proposed changes to the current drainage patterns associated with the proposed Maverik located on 112 th Avenue and Colorado Boulevard in Thornton, CO. Proposed changes to the property include construction of a 5,518 sq. ft. Maverik convenience store with fuel pumps and associated utility service connections. The detention basin and associated facilities have been designed for a full build-out scenario. 1.2 General Property Description At the request of Thornton City, Reeve & Associates has prepared the following Storm Drainage Design Report for the proposed Maverik located on 112 th Avenue and Colorado Boulevard in Thornton, Colorado. The site is located in the northwest quarter of section 7, township 2 south, and range 67 west. Figure 1 in the Appendix contains a general location map that shows the proposed location and surrounding properties. A private storm sewer system will collect stormwater runoff from the proposed development. The storm sewer system will discharge into a private detention pond located on the south end of the property. An outlet pipe from the detention pond will outlet to the public right of way located along the east side of Colorado Boulevard. 1.3 Pre-developed Drainage Characteristics The existing site is currently undeveloped and consists mostly of dry weeds and sandy loam with the soil type being C/D. The existing runoff from this property is one basin(ex-1) and sheet flows to the south west and out the access of the adjacent property owner as outlined in this section and depicted on the predevelopment drainage plan located in the Appendix; with design point Z being the outfall of the basin. The property is bordered to the north by 112 th Avenue to the west by Colorado Boulevard, to the south by commercial developments (Conoco Gas Station), and to the east by a baseball field and church. The pre-developed stormwater runoff leaves the site without the use of engineered quality or detention facilities. 4

5 Stormwater Drainage Design Report 1.4 Post-developed Drainage Characteristics The proposed site will operate as a Maverik Convenience Store with vehicle fueling stations. The entire parcel sits on 3.04 acres. The site will contain 54,208 s.f. of hard surface area, 54,208 s.f. of landscaped area and 5,518 s.f. of building area. The proposed grading will divide the site into eleven drainage basins and seven design points as outlined in this section and depicted on the developed drainage plan located in the Appendix. Basin R-1 encompasses 0.12 acres of landscape between the onsite curb and gutter and the adjacent property owner to the east. Stormwater generated in this basin will sheet flow undetained to the east and then to the south and follow its historical pattern into Colorado Blvd. Basin R-2 encompasses 0.24 acres of landscape and a small area of sidewalk between the onsite curb and gutter and Colorado Boulevard right of way. Stormwater generated in this basin will sheet flow undetained into the curb and gutter within the right-of-way and into the southwest corner of the lot and into Colorado Blvd. Basin R-3 encompasses 0.14 acres of landscape to the south of the property and in between the adjacent property owner to the south. Stormwater generated in this basin will sheet flow undetained into the right-of-way and into the southwest corner of the lot and into Colorado Blvd. Basin R-4 encompasses 0.10 acres of asphalt paving on the southwest corner of the lot. Stormwater generated in this basin will sheet flow undetained into the curb and gutter within the right-of-way in Colorado Blvd. Basin B-1 encompasses 0.31 acres of parking and drive aisles of the proposed convenience store. Stormwater generated in this basin will sheet flow to a low point on the curb with an inlet box titled A. The water will be conveyed by a private storm sewer system to the private detention pond. Basin B-2 encompasses 0.15 acres of parking, drive aisles and building from the proposed convenience store. Stormwater generated in this basin will sheet flow to a low point on the curb with an inlet box titled A. The water will be conveyed by a private storm sewer system to the private detention pond. Basin B-3 encompasses 0.32 acres of parking, drive aisles and landscape of the proposed convenience store. Stormwater generated in this basin will sheet flow to a low point on curb with an inlet box titled B. The water will be conveyed by a private storm sewer system to the private detention pond. 5

6 Stormwater Drainage Design Report Basin B-4 encompasses 0.10 acres of parking, drive aisles, building and landscape of the proposed convenience store. Stormwater generated in this basin will sheet flow to a low point on curb with an inlet box titled C. The water will be conveyed by a private storm sewer system to the private detention pond. Basin B-5 encompasses 0.30 acres of parking and drive aisles. Stormwater generated in this basin will sheet flow to a low point on curb with an inlet box titled E. The water will be conveyed by a private storm sewer system to the private detention pond. Basin B-6 encompasses 0.67 acres of parking and drive aisles and landscape for the proposed convenience store. Stormwater generated in this basin will sheet flow to a low point on curb with an inlet box titled D. The water will be conveyed by a private storm sewer system to the private detention pond. Basin B-7 encompasses 0.53 acres of detention pond. This has been sized to detain the 100-year storm event per COT code with an outlet structure and orifice plates for the WQCV, EURV and 100-year storm event. It will be landscaped per COT code. Pipe P1 conveys the stormwater from Basin B-1 from the inlet box A. This pipe also carries the water from Basin B-2. Pipe P2 conveys the stormwater from Basin B-3 from the inlet box B. Pipe P3 conveys the stormwater from Basin B-4 from the inlet box C. This pipe also carries the water from Basin B-3, B-2 and B-1. Pipe P4 conveys the stormwater from B-6 from the inlet box D. This pipe also carries the water from Basin B-4, B-3, B-2 and B-1. Pipe P5 conveys the stormwater from B-5 from the inlet box E. This pipe also carries the water from Basin B-6, B-4, B-3, B-2 and B-1. Pipe P6 conveys the stormwater from B-7, the detention pond. Ultimately, all storm water runoff from this site is conveyed to the South Platte River. Once completed, 0.65 cfs and 1.17 cfs will exit the site untreated during the 5-yr and 100-yr storms respectively with the majority of it passing through landscape areas. The remaining storm water from hard surface areas will be directed to a private detention pond that is sized for the WQCV, EURV and 100- yr volumes. It will release 0.3 cfs and 5.20 cfs into the Colorado Blvd right-ofway during the 5-year and 100-year storm events respectively. 6

7 Stormwater Drainage Design Report 1.5 Water Quality Post-development stormwater runoff will be collected via curb and gutter and private combination curb inlets throughout the property. A private storm sewer system will convey storm water flows to the private detention pond facility located along the northeast property line. The detention pond will provide storage for the water quality capture volume of acre-feet or 3,659 c.f. with a water surface elevation of and the EURV storage has also been provided with a volume of acre-feet or 7,318 c.f. with an elevation of An outlet structure within the detention pond will provide water quality and staged release of stored stormwater that meets the City of Thornton Storm Drainage Design requirements. Because the 5-yr, and 100-yr design storm event developed flows are larger than the pre-developed site runoff totals, the detention pond outlet structure also reduces the release rates of the post-developed flows to the pre-developed rates. The pond will provide storage for the 5-yr design storm event and the water quality volume of acre-feet or 13,024 c.f. with a water surface elevation of The pond will also provide storage for the 100-yr, design storm event with a volume of acre-feet or 18,687 c.f. with a water surface elevation of During the 100-yr design storm event, the pond outlet structure will provide a release rate of 5.2 cfs which is less than the predeveloped outflow of 16.1 cfs provided the UD-Detention analysis of the detention pond volume. A private 15 RCP pipe will connect to the outlet structure and release into a sidewalk chase drain and into the curbline along the north side of Colorado Boulevard. See Hydraulic Calculations located in the Appendix for more details regarding detention pond design. 1.6 Hydrology Calculations The City of Thornton Storm Drainage Design, Grading, and Water Quality Technical Criteria within the City of Thornton Standards and Specifications was used to perform hydrology calculations. The Rational Method has been used to compute storm water runoff, as preferred for drainage areas less than 100-acres. Design storms with the 5-yr, and 100-yr, occurrence intervals were used. Weighted or composite C values for the site were calculated using the following formula. 7

8 Stormwater Drainage Design Report 5-year, and 100-yr, flows for the proposed site are summarized in the Appendix. Table 1 shows a comparison between pre-development discharges and postdevelopment discharges from the project site. Tablie 1: Peak Discharge Comparison Pre-Development Discharge (cfs) Post-Development Discharge (cfs) Discharge Difference (cfs) Q5 Colorado Blvd Q100 Colorado Blvd Pipe and inlet capacity calculations were performed at each design point as shown on the drainage plan. Storm sewer for this project was designed to convey the required 10-yr storm even with a surcharge hydraulic grade line not less than one foot below finished grade. Hydrologic and hydraulic calculations are located in the Appendix. All assumptions shall be field verified by the contractor prior to commencing construction, and discrepancies shall be reported to the engineer immediately for review. 1.7 Floodplain Statement According to the Federal Emergency Management Agency (FEMA), as depictured on Flood Insurance Rate Map (FIRM) 08001C0314H with an effective date of March 5, 2007, the site lies within areas determined to be outside the 500- year floodplain. 1.8 Erosion Control It is respectfully requested that an erosion control plan be submitted in conjunction with the final grading plan and not be required to be submitted with this drainage report. Erosion control will be implemented in 2 phases. Phase 1 is during construction and Phase 2 is post-construction. 8

9 Stormwater Drainage Design Report Phase 1 erosion control components include the following. Two 25 x 20 construction entrances with 8 compacted clean gravel will be placed at the construction accesses to reduce amounts of sediment tracked onto roadways. A concrete wash area will be placed on site to contain concrete waste. A silt fence will be placed at the perimeter of the site as a dust control measure. A temporary drainage ditch will be created prior to installation of infrastructure to provide a path for storm water and prevent runoff to adjacent property. Inlet protection bmps will be implemented at all inlets to prevent sediment from entering storm drain system. In addition to these components, streets will be swept within 1,000 feet of construction entrances daily if necessary. Phase 2 erosion control components include a snout and sump filter on strategically placed inlet box and extended detention basin. Snout and sump filter will be placed on inlet box that directly outlets to detention basin to filter hydrocarbons and other contaminants from entering the detention basin. Extended detention basin provides water quality volume as well as EURV. 1.9 Summary Developed runoff generated from the project site during the 100-yr. design storm event are anticipated to be less than or equal to the pre-developed runoff rates. Prior to being released off-site, runoff will be treated via a private detention pond and water quality facility, while a small percentage of the site s runoff will discharge (un-detained) to the adjacent right-of-way or adjacent properties. Downstream of the detention pond, a private 15 RCP pipe and sidewalk chase drain will convey treated runoff into the Colorado Boulevard right of way. A series of private combination inlets will collect runoff in multiple locations on site and convey the runoff to the proposed private detention pond east of the Maverik building. The storm sewer has been designed to handle developed flows in the required 10-yr. design storm event condition within minimal surcharge. Since the site s anticipated developed runoff rate is less than the allowed predevelopment runoff rate, development on this site as described in the enclosed drainage plan is not anticipated to adversely impact downstream stormwater infrastructure. Upon the completion of construction, if conditions or outfall locations differ from the assumptions stated within this drainage study, an amendment to this report must be completed. Maverik Inc. will be responsible for any maintenance on the drainage facilities. 9

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11 Stormwater Drainage Design Report Figure 1 Vicinity Map 12 th Avenue and Colorado Boulevard Project Site The project site is located at 112 th Avenue and Colorado Boulevard.in Thornton, CO. 11

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34 Storm Runoff Calculations Maverik, Inc 112th Avenue & Colorado Boulevard 9/6/2016 TJH Basin Designation EX-1 Composite 'C' Factors - Pre & Post-Development GRASS ROOFS PAVEMENT GRAVEL COMPOSITE C FACTOR Grass Roofs Paved Gravel Total 5-YR 10-YR 100-YR 5-YR 10-YR 100-YR 5-YR 10-YR 100-YR 5-YR 10-YR 100-YR 5-YR 10-YR 100-YR % IMPERVIOUS 0.00 R-1 R-2 R-3 R-4 B-1 B-2 B-3 B-4 B-5 B-6 B-7 * EX = existing * R = undetained * B = detained Basin Designation EX-1 Time of Concentration Slope C5 Acre Length (ft) Slope % Ti (min) Length (ft) Vel. (fps) Tt (min.) Total (ft/ft) R R R min. assumed R min. assumed B min. assumed B min. assumed B min. assumed B min. assumed B min. assumed B min. assumed B min. assumed * EX = existing * R = undetained * B = detained Design Point Z A B C E D * EX = existing * R = undetained * B = detained Design Storm: 5-Year Runoff Basin Area (ac) Coeff. (c) Tc C*A I (in./hr.) Q (cfs) Sum Area Max (Tc) EX R-1 R-2 R-3 R-4 B-1 B-2 B-3 B-4 B-5 B-6 B Sum C*A Total Q (cfs) Passby Q (cfs)

35 Design Storm: 10-Year Runoff Design Point Basin Area (ac) Coeff. (c) Tc C*A I (in./hr.) Q (cfs) Sum Area Max (Tc) Sum C*A Total Q (cfs) EX Z R R R R A B B B B C B E B D B B * EX = existing * R = undetained * B = detained Design Point Basin EX-1 Z R-1 R-2 R-3 R-4 A B-1 B-2 B B-3 C B-4 E B-5 D B-6 B-7 Design Storm: 100-Year Runoff Area (ac) Coeff. (c) Tc C*A I (in./hr.) Q (cfs) Sum Area Max (Tc) Sum C*A Total Q (cfs) Passby Q (cfs) Sum Area Max (Tc) Sum C*A Total Q (cfs) A B-1 + B B B C B D B E B FOR PIPE CAPACITY CALCULATIONS P1 P2 P3 P4 P5 Sum Area (Tc) Sum C*A I (in./hr) P6 See UD-Detention Spreadsheet Total Q (cfs) Z post See UD-Detention Spreadsheet 5.20

36 Inlet Management Worksheet Protected INLET NAME Inlet A Inlet B Inlet C Inlet D Inlet E ed Site Type (Urban or Rural) URBAN URBAN URBAN URBAN URBAN Inlet Application (Street or Area) STREET STREET STREET STREET STREET Hydraulic Condition In Sump On Grade On Grade On Grade On Grade Inlet Type Denver No. 16 Combination Denver No. 16 Combination Denver No. 16 Combination Denver No. 16 Combination Denver No. 16 Combination USER-DEFINED INPUT User-Defined Design Flows Minor Q Known (cfs) Major Q Known (cfs) Bypass (Carry-Over) Flow from Upstream Receive Bypass Flow from: Minor Bypass Flow Received, Q b (cfs) Major Bypass Flow Received, Q b (cfs) No Bypass Flow Received No Bypass Flow Received No Bypass Flow Received Inlet B Inlet C Watershed Characteristics Subcatchment Area (acres) Percent Impervious NRCS Soil Type Watershed Profile Overland Slope (ft/ft) Overland Length (ft) Channel Slope (ft/ft) Channel Length (ft) Minor Storm Rainfall Input Design Storm Return Period, T r (years) One-Hour Precipitation, P 1 (inches) C 1 C 2 C 3 User-defined C User-defined 5-yr C 5 User-defined T c Major Storm Rainfall Input Design Storm Return Period, T r (years) One-Hour Precipitation, P 1 (inches) C 1 C 2 C 3 User-defined C User-defined 5-yr C 5 User-defined T c CALCULATED OUTPUT Minor Total Design Peak Flow, Q (cfs) Major Total Design Peak Flow, Q (cfs) Minor Flow Bypassed Downstream, Q b (cfs) Major Flow Bypassed Downstream, Q b (cfs) Minor Storm (Calculated) Analysis of Flow Time C C 5 Overland Flow Velocity, Vi Channel Flow Velocity, Vt Overland Flow Time, Ti Channel Travel Time, Tt Calculated Time of Concentration, T c T c (Equation 5-5 USDCM) Recommended T c T c selected by User Design Rainfall Intensity, I Calculated Local Peak Flow, Q p Major Storm (Calculated) Analysis of Flow Time C C 5 Overland Flow Velocity, Vi Channel Flow Velocity, Vt Overland Flow Time, Ti Channel Travel Time, Tt Calculated Time of Concentration, T c T c (Equation 5-5 USDCM) Recommended T c T c selected by User Design Rainfall Intensity, I Calculated Local Peak Flow, Q p N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

37 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) 112th Avenue & Colorado Boulevard Basin 1 Inlet at Design Point A Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb T BACK = 0.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb) S BACK = ft/ft Manning's Roughness Behind Curb (typically between and 0.020) n BACK = Height of Curb at Gutter Flow Line H CURB = 6.00 inches Distance from Curb Face to Street Crown T CROWN = 40.0 ft Gutter Width W = 1.50 ft Street Transverse Slope S X = ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or ft/ft) S W = ft/ft Street Longitudinal Slope - Enter 0 for sump condition S O = ft/ft Manning's Roughness for Street Section (typically between and 0.020) n STREET = Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm T MAX = ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm d MAX = inches Allow Flow Depth at Street Crown (leave blank for no) check = yes MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Q allow = SUMP SUMP cfs INLET IN A SUMP OR SAG LOCATION Lo (C) H-Curb W W P H-Vert Wo Lo (G) Design Information (Input) MINOR MAJOR Denver No. 16 Combination Type of Inlet Type = Denver No. 16 Combination Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') a local = inches Number of Unit Inlets (Grate or Curb Opening) No = 1 1 Water Depth at Flowline (outside of local depression) Ponding Depth = inches Grate Information MINOR MAJOR Override Depths Length of a Unit Grate L o (G) = feet Width of a Unit Grate W o = feet Area Opening Ratio for a Grate (typical values ) A ratio = Clogging Factor for a Single Grate (typical value ) C f (G) = Grate Weir Coefficient (typical value ) C w (G) = Grate Orifice Coefficient (typical value ) C o (G) = Curb Opening Information MINOR MAJOR Length of a Unit Curb Opening L o (C) = feet Height of Vertical Curb Opening in Inches H vert = inches Height of Curb Orifice Throat in Inches H throat = inches Angle of Throat (see USDCM Figure ST-5) Theta = degrees Side Width for Depression Pan (typically the gutter width of 2 feet) W p = feet Clogging Factor for a Single Curb Opening (typical value 0.10) C f (C) = Curb Opening Weir Coefficient (typical value ) C w (C) = Curb Opening Orifice Coefficient (typical value ) C o (C) = Low Head Performance Reduction (Calculated) MINOR MAJOR Depth for Grate Midwidth d Grate = ft Depth for Curb Opening Weir Equation d Curb = ft Combination Inlet Performance Reduction Factor for Long Inlets RF Combination = Curb Opening Performance Reduction Factor for Long Inlets RF Curb = Grated Inlet Performance Reduction Factor for Long Inlets RF Grate = MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition) Q a = cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK) Q PEAK REQUIRED = cfs Copy of UD-Inlet_v4.03.xlsm, Inlet A 9/7/2016, 10:45 AM

38 Project: Inlet ID: ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) 112th Avenue & Colorado Boulevard Inlet B Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb T BACK = 0.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb) S BACK = ft/ft Manning's Roughness Behind Curb (typically between and 0.020) n BACK = Height of Curb at Gutter Flow Line H CURB = 6.00 inches Distance from Curb Face to Street Crown T CROWN = 40.0 ft Gutter Width W = 1.50 ft Street Transverse Slope S X = ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or ft/ft) S W = ft/ft Street Longitudinal Slope - Enter 0 for sump condition S O = ft/ft Manning's Roughness for Street Section (typically between and 0.020) n STREET = Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm T MAX = ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm d MAX = inches Allow Flow Depth at Street Crown (leave blank for no) check = yes MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Spread Criterion Q allow = cfs 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' INLET ON A CONTINUOUS GRADE Design Information (Input) MINOR MAJOR Denver No. 16 Combination Type of Inlet Type = Denver No. 16 Combination Local Depression (additional to continuous gutter depression 'a') a LOCAL = inches Total Number of Units in the Inlet (Grate or Curb Opening) No = 1 1 Warning 1 Length of a Single Unit Inlet (Grate or Curb Opening) L o = ft Warning 1 Width of a Unit Grate (cannot be greater than W, Gutter Width) W o = ft Clogging Factor for a Single Unit Grate (typical min. value = 0.5) C f -G = Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1) C f -C = Street Hydraulics: OK - Q < Allowable Street Capacity' MINOR MAJOR Total Inlet Interception Capacity Q = cfs Total Inlet Carry-Over Flow (flow bypassing inlet) Q b = cfs Capture Percentage = Q a /Q o = C% = % Warning 1: Dimension entered is not a typical dimension for inlet type specified. Copy of UD-Inlet_v4.03.xlsm, Inlet B 9/7/2016, 10:45 AM

39 Project: Inlet ID: ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) 112th Avenue & Colorado Boulevard Inlet C Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb T BACK = 0.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb) S BACK = ft/ft Manning's Roughness Behind Curb (typically between and 0.020) n BACK = Height of Curb at Gutter Flow Line H CURB = 6.00 inches Distance from Curb Face to Street Crown T CROWN = 10.0 ft Gutter Width W = 1.50 ft Street Transverse Slope S X = ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or ft/ft) S W = ft/ft Street Longitudinal Slope - Enter 0 for sump condition S O = ft/ft Manning's Roughness for Street Section (typically between and 0.020) n STREET = Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm T MAX = ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm d MAX = inches Allow Flow Depth at Street Crown (leave blank for no) check = yes MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Spread Criterion Q allow = cfs 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' INLET ON A CONTINUOUS GRADE Design Information (Input) MINOR MAJOR Denver No. 16 Combination Type of Inlet Type = Denver No. 16 Combination Local Depression (additional to continuous gutter depression 'a') a LOCAL = inches Total Number of Units in the Inlet (Grate or Curb Opening) No = 1 1 Warning 1 Length of a Single Unit Inlet (Grate or Curb Opening) L o = ft Warning 1 Width of a Unit Grate (cannot be greater than W, Gutter Width) W o = ft Clogging Factor for a Single Unit Grate (typical min. value = 0.5) C f -G = Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1) C f -C = Street Hydraulics: OK - Q < Allowable Street Capacity' MINOR MAJOR Total Inlet Interception Capacity Q = cfs Total Inlet Carry-Over Flow (flow bypassing inlet) Q b = cfs Capture Percentage = Q a /Q o = C% = % Warning 1: Dimension entered is not a typical dimension for inlet type specified. Copy of UD-Inlet_v4.03.xlsm, Inlet C 9/7/2016, 10:46 AM

40 Project: Inlet ID: ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) 112th Avenue & Colorado Boulevard Inlet D Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb T BACK = 0.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb) S BACK = ft/ft Manning's Roughness Behind Curb (typically between and 0.020) n BACK = Height of Curb at Gutter Flow Line H CURB = 6.00 inches Distance from Curb Face to Street Crown T CROWN = 40.0 ft Gutter Width W = 1.50 ft Street Transverse Slope S X = ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or ft/ft) S W = ft/ft Street Longitudinal Slope - Enter 0 for sump condition S O = ft/ft Manning's Roughness for Street Section (typically between and 0.020) n STREET = Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm T MAX = ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm d MAX = inches Allow Flow Depth at Street Crown (leave blank for no) check = yes MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Q allow = cfs 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' INLET ON A CONTINUOUS GRADE Design Information (Input) MINOR MAJOR Denver No. 16 Combination Type of Inlet Type = Denver No. 16 Combination Local Depression (additional to continuous gutter depression 'a') a LOCAL = inches Total Number of Units in the Inlet (Grate or Curb Opening) No = 1 1 Warning 1 Length of a Single Unit Inlet (Grate or Curb Opening) L o = ft Warning 1 Width of a Unit Grate (cannot be greater than W, Gutter Width) W o = ft Clogging Factor for a Single Unit Grate (typical min. value = 0.5) C f -G = Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1) C f -C = Street Hydraulics: OK - Q < Allowable Street Capacity' MINOR MAJOR Total Inlet Interception Capacity Q = cfs Total Inlet Carry-Over Flow (flow bypassing inlet) Q b = cfs Capture Percentage = Q a /Q o = C% = % Warning 1: Dimension entered is not a typical dimension for inlet type specified. Copy of UD-Inlet_v4.03.xlsm, Inlet D 9/7/2016, 10:46 AM

41 Project: Inlet ID: ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) 112th Avenue & Colorado Boulevard Inlet E Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb T BACK = 0.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb) S BACK = ft/ft Manning's Roughness Behind Curb (typically between and 0.020) n BACK = Height of Curb at Gutter Flow Line H CURB = 6.00 inches Distance from Curb Face to Street Crown T CROWN = 20.0 ft Gutter Width W = 1.50 ft Street Transverse Slope S X = ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or ft/ft) S W = ft/ft Street Longitudinal Slope - Enter 0 for sump condition S O = ft/ft Manning's Roughness for Street Section (typically between and 0.020) n STREET = Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm T MAX = ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm d MAX = inches Allow Flow Depth at Street Crown (leave blank for no) check = yes MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Spread Criterion Q allow = cfs 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' INLET ON A CONTINUOUS GRADE Design Information (Input) MINOR MAJOR Denver No. 16 Combination Type of Inlet Type = Denver No. 16 Combination Local Depression (additional to continuous gutter depression 'a') a LOCAL = inches Total Number of Units in the Inlet (Grate or Curb Opening) No = 1 1 Warning 1 Length of a Single Unit Inlet (Grate or Curb Opening) L o = ft Warning 1 Width of a Unit Grate (cannot be greater than W, Gutter Width) W o = ft Clogging Factor for a Single Unit Grate (typical min. value = 0.5) C f -G = Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1) C f -C = Street Hydraulics: OK - Q < Allowable Street Capacity' MINOR MAJOR Total Inlet Interception Capacity Q = cfs Total Inlet Carry-Over Flow (flow bypassing inlet) Q b = cfs Capture Percentage = Q a /Q o = C% = % Warning 1: Dimension entered is not a typical dimension for inlet type specified. Copy of UD-Inlet_v4.03.xlsm, Inlet E 9/7/2016, 10:46 AM

42 DETENTION BASIN STAGE-STORAGE TABLE BUILDER Project: 112th Ave & Colorado Blvd Basin ID: Detention Basin Depth Increment = 0.2 ft Optional Optional Example Zone Configuration (Retention Pond) Stage - Storage Stage Override Length Width Area Override Area Volume Volume Description (ft) Stage (ft) (ft) (ft) (ft^2) Area (ft^2) (acre) (ft^3) (ac-ft) Required Volume Calculation Micropool Selected BMP Type = EDB ISV Watershed Area = 3.37 acres Watershed Length = 556 ft Watershed Slope = ft/ft Watershed Imperviousness = 75.00% percent Percentage Hydrologic Soil Group A = 0.0% percent , Percentage Hydrologic Soil Group B = 15.0% percent , Percentage Hydrologic Soil Groups C/D = 85.0% percent , , Desired WQCV Drain Time = 40.0 hours , , Location for 1-hr Rainfall Depths = Thornton - Thornton City Office , , Water Quality Capture Volume (WQCV) = acre-feet Optional User Input Zone 1 (WQCV) , , Excess Urban Runoff Volume (EURV) = acre-feet 1-hr Precipitation , , yr Runoff Volume (P1 = 0.95 in.) = acre-feet inches , , yr Runoff Volume (P1 = 1.35 in.) = acre-feet inches , , yr Runoff Volume (P1 = 1.61 in.) = acre-feet inches Zone 2 (EURV) , , yr Runoff Volume (P1 = 2.03 in.) = acre-feet inches Floor , , yr Runoff Volume (P1 = 2.32 in.) = acre-feet inches , , yr Runoff Volume (P1 = 2.66 in.) = acre-feet inches , , yr Runoff Volume (P1 = 3.33 in.) = acre-feet inches Zone 3 (100-year) , , Approximate 2-yr Detention Volume = acre-feet , , Approximate 5-yr Detention Volume = acre-feet , , Approximate 10-yr Detention Volume = acre-feet , , Approximate 25-yr Detention Volume = acre-feet , , Approximate 50-yr Detention Volume = acre-feet , , Approximate 100-yr Detention Volume = acre-feet , , , , Stage-Storage Calculation , , Zone 1 Volume (WQCV) = acre-feet , , Zone 2 Volume (EURV - Zone 1) = acre-feet , , Zone 3 Volume (100-year - Zones 1 & 2) = acre-feet , , Total Detention Basin Volume = acre-feet , , Initial Surcharge Volume (ISV) = 11 ft^ , , Initial Surcharge Depth (ISD) = 0.33 ft , , Total Available Detention Depth (H total) = 3.04 ft , , Depth of Trickle Channel (H TC) = 0.50 ft , , Slope of Trickle Channel (S TC) = ft/ft , , Slopes of Main Basin Sides (S main) = 4 H:V , , Basin Length-to-Width Ratio (R L/W) = , , , , Initial Surcharge Area (A ISV) = 33 ft^ , , Surcharge Volume Length (L ISV) = 5.8 ft , , Surcharge Volume Width (W ISV) = 5.8 ft , , Depth of Basin Floor (H FLOOR) = 1.86 ft , , Length of Basin Floor (L FLOOR) = ft , , Width of Basin Floor (W FLOOR) = 57.3 ft , , Area of Basin Floor (A FLOOR) = 18,481 ft^ , , Volume of Basin Floor (V FLOOR) = 11,937 ft^ , , Depth of Main Basin (H MAIN) = 0.35 ft , , Length of Main Basin (L MAIN) = ft , , Width of Main Basin (W MAIN) = 60.2 ft , , Area of Main Basin (A MAIN) = 19,566 ft^ , , Volume of Main Basin (V MAIN) = 6,743 ft^ , , Calculated Total Basin Volume (V total) = acre-feet , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , UD-Detention_v3.02.xlsm, Basin 7/26/2016, 1:26 PM

43 Area (acres) Volume (ac-ft) Length, Width (ft.) Area (sq.ft.) DETENTION BASIN STAGE-STORAGE TABLE BUILDER User Defined Stage-Area Boolean for Message 0 Equal Stage-Area Inputs Watershed L:W 1 CountA Calc_S_TC 1.86 H_FLOOR L_FLOOR_OTHER 0.33 ISV 0.33 ISV Floor 2.04 Zone 1 (WQCV) 2.04 Zone 1 (WQCV) 2.62 Zone 2 (EURV) 2.62 Zone 2 (EURV) 2.69 Floor 3.05 Zone 3 (100-yea 3.05 Zone 3 (100-year) Stage (ft) Length (ft) Width (ft) Area (sq.ft.) Stage (ft.) Area (acres) Volume (ac-ft) UD-Detention_v3.02.xlsm, Basin 7/26/2016, 1:26 PM

44 Detention Basin Outlet Structure Design Project: 88th & Pecos Maverik Fueling Station Basin ID: Full Build-Out Detention Basin Stage (ft) Zone Volume (ac-ft) Outlet Type Zone 1 (WQCV) Orifice Plate Zone 2 (EURV) Orifice Plate Zone 3 (100-year) Weir&Pipe (Restrict) Example Zone Configuration (Retention Pond) Total 24 User Input: Orifice at Underdrain Outlet (typically used to drain WQCV in a Filtration BMP) Calculated Parameters for Underdrain Underdrain Orifice Invert Depth = N/A ft (distance below the filtration media surface) Underdrain Orifice Area = N/A ft 2 Underdrain Orifice Diameter = N/A inches Underdrain Orifice Centroid = N/A feet User Input: Orifice Plate with one or more orifices or Elliptical Slot Weir (typically used to drain WQCV and/or EURV in a sedimentation BMP) Calculated Parameters for Plate Invert of Lowest Orifice = 0.00 ft (relative to bottom of basin at Stage = 0 ft) WQ Orifice Area per Row = N/A ft 2 Depth at top of Zone using Orifice Plate = 2.62 ft (relative to bottom of basin at Stage = 0 ft) Elliptical Half-Width = N/A feet Orifice Plate: Orifice Vertical Spacing = N/A inches Elliptical Slot Centroid = N/A feet Orifice Plate: Orifice Area per Row = N/A inches Elliptical Slot Area = N/A ft 2 User Input: Stage and Total Area of Each Orifice Row (numbered from lowest to highest) Row 1 (required) Row 2 (optional) Row 3 (optional) Row 4 (optional) Row 5 (optional) Row 6 (optional) Row 7 (optional) Row 8 (optional) Stage of Orifice Centroid (ft) Orifice Area (sq. inches) Stage of Orifice Centroid (ft) Orifice Area (sq. inches) Row 9 (optional) Row 10 (optional) Row 11 (optional) Row 12 (optional) Row 13 (optional) Row 14 (optional) Row 15 (optional) Row 16 (optional) User Input: Vertical Orifice (Circular or Rectangular) Calculated Parameters for Vertical Orifice Not Selected Not Selected Not Selected Not Selected Invert of Vertical Orifice = N/A N/A ft (relative to bottom of basin at Stage = 0 ft) Vertical Orifice Area = N/A N/A ft 2 Depth at top of Zone using Vertical Orifice = N/A N/A ft (relative to bottom of basin at Stage = 0 ft) Vertical Orifice Centroid = N/A N/A feet Vertical Orifice Diameter = N/A N/A inches User Input: Overflow Weir (Dropbox) and Grate (Flat or Sloped) Calculated Parameters for Overflow Weir Zone 3 Weir Not Selected Zone 3 Weir Not Selected Overflow Weir Front Edge Height, Ho = 2.62 N/A ft (relative to bottom of basin at Stage = 0 ft) Height of Grate Upper Edge, H t = 3.05 N/A feet Overflow Weir Front Edge Length = 6.00 N/A feet Over Flow Weir Slope Length = 6.02 N/A feet Overflow Weir Slope = N/A H:V (enter zero for flat grate) Grate Open Area / 100-yr Orifice Area = N/A should be > 4 Horiz. Length of Weir Sides = 6.00 N/A feet Overflow Grate Open Area w/o Debris = N/A ft 2 Overflow Grate Open Area % = 70% N/A %, grate open area / total area Overflow Grate Open Area with Debris = N/A ft 2 Debris Clogging % = 50% N/A % User Input: Outlet Pipe w/ Flow Restriction Plate (Circular Orifice, Restrictor Plate, or Rectangular Orifice) Calculated Parameters for Outlet Pipe w/ Flow Restriction Plate Zone 3 Restrictor Not Selected Zone 3 Restrictor Not Selected Depth to Invert of Outlet Pipe = 0.00 N/A ft (distance below bottom of basin at Stage = 0 ft) Outlet Orifice Area = 0.63 N/A ft 2 Outlet Pipe Diameter = N/A inches Outlet Orifice Centroid = 0.41 N/A feet Restrictor Plate Height Above Pipe Invert = 9.00 inches Half-Central Angle of Restrictor Plate on Pipe = 2.09 N/A radians User Input: Emergency Spillway (Rectangular or Trapezoidal) Calculated Parameters for Spillway Spillway Invert Stage= 3.10 ft (relative to bottom of basin at Stage = 0 ft) Spillway Design Flow Depth= 0.66 feet Spillway Crest Length = 8.00 feet Stage at Top of Freeboard = 4.76 feet Spillway End Slopes = 4.00 H:V Basin Area at Top of Freeboard = 0.58 acres Freeboard above Max Water Surface = 1.00 feet Routed Hydrograph Results Design Storm Return Period = WQCV EURV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year 500 Year One-Hour Rainfall Depth (in) = Calculated Runoff Volume (acre-ft) = OPTIONAL Override Runoff Volume (acre-ft) = Inflow Hydrograph Volume (acre-ft) = Predevelopment Unit Peak Flow, q (cfs/acre) = Predevelopment Peak Q (cfs) = Peak Inflow Q (cfs) = Peak Outflow Q (cfs) = Ratio Peak Outflow to Predevelopment Q = N/A N/A N/A Structure Controlling Flow = Plate Plate Plate Overflow Grate 1 Overflow Grate 1 Overflow Grate 1 Overflow Grate 1 Outlet Plate 1 Spillway Max Velocity through Grate 1 (fps) = N/A N/A N/A Max Velocity through Grate 2 (fps) = N/A N/A N/A N/A N/A N/A N/A N/A N/A Time to Drain 97% of Inflow Volume (hours) = Time to Drain 99% of Inflow Volume (hours) = Maximum Ponding Depth (ft) = Area at Maximum Ponding Depth (acres) = Maximum Volume Stored (acre-ft) =

45 AREA [ft^2], VOLUME [ft^3] OUTFLOW [cfs] PONDING DEPTH [ft] FLOW [cfs] Detention Basin Outlet Structure Design YR COUNTA IN for Basin Tab = 1 Ao Dia WQ Plate Type Vert Orifice 1 Vert Orifice 2 500YR Count_Underdrain OUT = eter = 3/8 inch) YR IN Count_WQPlate = ter = 7/16 inch) 100YR OUT Count_VertOrifice1 = eter = 1/2 inch) Outlet Plate 1 Outlet Plate 2 Drain Time Message Boolean 50YR IN Count_VertOrifice2 = ter = 9/16 inch) 4 1 5yr, <72hr 0 50YR OUT 25YR IN Count_Weir1 = eter = 5/8 inch) >5yr, <120hr 0 25YR OUT Count_Weir2 = er = 11/16 inch) Max Depth Row 10YR Count_OutletPipe1 IN = eter = 3/4 inch) WQCV 200 Watershed Constraint Check 10YR Count_OutletPipe2 OUT = er = 13/16 inch) 2 Year 244 Slope YR IN COUNTA_2 (Standard FSD Setup)= eter = 7/8 inch) EURV 259 Shape YR OUT MaxPondDepth_Error? FALSE 0.67 er = 15/16 inch) 5 Year 269 2YR IN Hidden Parameters & Calculations 0.76 meter = 1 inch) 10 Year 279 Spillway Depth 2YR OUT /16 inches) 25 Year EURV IN WQ Plate Flow at 100yr depth = = 1-1/8 inches) 50 Year 298 EURV OUT CLOG #1= 35% /16 inches) 100 Year Z1_Boolean WQCV IN C dw #1 = = 1-1/4 inches) 500 Year Z2_Boolean WQCV OUT C do #1 = /16 inches) Zone3_Pulldown Message 1 Z3_Boolean Overflow Weir #1 Angle = = 1-3/8 inches) 1 Opening Message CLOG #2= #VALUE! /16 inches) Draintime Running C dw #2 = #VALUE! 1.73 = 1-1/2 inches) Outlet Boolean Outlet Rank Total (1 to 4) C do #2 = #VALUE! /16 inches) Vertical Orifice Overflow Weir #2 Angle = #VALUE! 2.03 = 1-5/8 inches) Vertical Orifice Boolean Underdrain Q at 100yr depth = /16 inches) Overflow Weir Max Depth 0.1 VertOrifice1 Q at 100yr depth = = 1-3/4 inches) Overflow 1 Weir yr Depth 10 VertOrifice2 Q at 100yr depth = /16 inches) TIME [hr] Outlet Pipe Freeboard EURV_draintime_user = 2.72 = 1-7/8 inches) Outlet Pipe Spillway 3.5 Count_User_Hydrographs /16 inches) 0 Spillway Length 500YR CountA_3 (EURV & 100yr) = eter = 2 inches) Button Visibility Boolean 100YR CountA_4 (100yr Only) = gular openings) 1 Button_Trigger 50YR YR 10YR 5YR 2YR EURV WQCV 0 Underdrain 1 WQCV Plate 0 EURV-WQCV Plate 0 EURV-WQCV VertOrifice 1 Outlet 90% Qpeak 0 Outlet Undetained DRAIN TIME [hr] User Area [ft^2] 6, Interpolated Area [ft^2] Volume [ft^3] 5, Outflow [cfs] 4, , , , PONDING DEPTH [ft]

46 Detention Basin Outlet Structure Design Outflow Hydrograph Workbook Filename: Storm Inflow Hydrographs The user can override the calculated inflow hydrographs from this workbook with inflow hydrographs developed in a separate program. SOURCE WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK Time Interval TIME WQCV [cfs] EURV [cfs] 2 Year [cfs] 5 Year [cfs] 10 Year [cfs] 25 Year [cfs] 50 Year [cfs] 100 Year [cfs] 500 Year [cfs] 4.77 min 0:00: :04: Hydrograph 0:09: Constant 0:14: :19: :23: :28: :33: :38: :42: :47: :52: :57: :02: :06: :11: :16: :21: :25: :30: :35: :40: :44: :49: :54: :59: :04: :08: :13: :18: :23: :27: :32: :37: :42: :46: :51: :56: :01: :06: :10: :15: :20: :25: :29: :34: :39: :44: :49: :53: :58: :03: :08: :12: :17: :22: :27: :31: :36: :41: :46: :51: :55: :00: :05: :10: :14: :19: :24: :29: :33: :38: :43:

47 1 2 6/2/2015 7:10:47 AM A B C D 0" 1" 2" SEAL DATE STATUS DATE REVISION PROJECT NUMBER????? FILE DRAWN BY R. Hansen CHECKED BY J.Nate Reeve, P.E. SCALE As indicated PRE-DEVELOPED DRAINAGE PLAN THORNTON MAVERIK 112TH AVENUE & COLORADO BOULEVARD THORNTON, COLORADO PERMIT SET

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