Drainage_Report.pdf

WADSWORTH

PATH 32ND TO 35TH

AVENUE

Prepared for:

City of Wheat Ridge

Wheat Ridge, Colorado

Prepared by:

Laura Kindt, PE

Olsson, Inc.

September 2025

Olsson Project No. 024-03656

ACQ M361-013 (25614) Wadsworth Path 32nd to 35th Avenue

Project No. 024-03656 September 2025

024-03656 1

TABLE OF CONTENTS

1. INTRODUCTION

1.1. Project Location and Purpose

1.2. Description of Property

1.2.1. Ground Cover and Topography

1.2.2. Soils Description

1.2.3. Major Drainageways

2. HYDROLOGY

2.1. Drainage Basin Map

2.2. Major Basin Description

2.3. On-Site Description

2.4. Precipitation Data

2.5. Design Flood Frequency

3. EXISTING STRUCTURES

4. DESIGN DISCUSSION

5. RECOMMENDED DESIGN

5.1. Inlets

5.2. Storm Drain

5.3. Detention/Water Quality

REFERENCES

024-03656 2

LIST OF FIGURES

Figure 1: Vicinity Map

Figure 2: MHFD Initial Storm Street Capacity Criteria

Figure 3: MHFD Major Storm Street Capacity Criteria

LIST OF TABLES

Table 1: Existing and Proposed Initial and Major Flows

APPENDICES

Appendix A Hydrology

Appendix B Hydraulics

Appendix C Reference Information

024-03656 3

1. INTRODUCTION

The Wadsworth Path 32nd to 35th Avenue project includes adding a sidewalk along the west side of Wadsworth Boulevard (Blvd) from 32nd to 35th Avenue, curb and gutters, roadway patching, relocating the existing Rocky Mountain Water Company (RMWC) 6-foot by 3-foot box culvert, bulkheading the existing Colorado Department of Transportation (CDOT) 6-foot by 3-foot box culvert and extending the culvert with 24” and 18” reinforced concrete pipes, and relocating existing drainage structures (inlets and storm pipes) along Wadsworth. This project is designed for the City of Wheat Ridge in conjunction with CDOT.

1.1. Project Location and Purpose

The Improve Wadsworth project located to the north, that is currently under construction by others, is adding a detached shared path on the west side of Wadsworth Blvd. from 35th Avenue to Clear Creek. This project is extending the path south from 35th Avenue to 32nd Avenue and will improve ADA facilities of the path at 35th Avenue. This project is 0.25 miles long and is located within the City of Wheat Ridge, Colorado. The project stationing begins at 103+16.88 and extends to 116+41.45. The existing roadway includes CDOT right-of-way along Wadsworth

Blvd. that is bound by residential and commercial properties. The project is located in Section

26 Township 3 Range 69. A vicinity map is located in Figure 1.

024-03656 4

Figure 1: Vicinity Map

1.2. Description of Property

1.2.1. Ground Cover and Topography

The improvements include adding a sidewalk to the west side of Wadsworth Blvd. for approximately 0.25 miles. The project area is fully developed and is comprised primarily of roadway, grass, and dirt as ground cover. There is a high point located near station

024-03656 5

107+00 along Wadsworth Blvd. Drainage north of 107+00 drains to the north to the storm system located within Wadsworth and ultimately outfalls to Clear Creek. Drainage south of 107+00 drains south towards 32nd Avenue. Drainage is collected and conveyed within an existing storm system located within 32nd Avenue. Drainage is conveyed east where it outfalls to an unnamed Creek located east of the intersection of 32nd Avenue and Independence Street. The unnamed creek ultimately outfalls to Clear Creek. Offsite drainage generally flows southwest to northeast towards Wadsworth Blvd.

The surrounding topography slopes range from zero percent up to approximately nine percent, with adjoining offsite properties being a combination of residential and commercial properties draining towards Wadsworth Blvd.

1.2.2. Soils Description

The project area and tributary offsite areas include Hydrologic Soil Group Type C soils, which are characterized by slow infiltration rates and high runoff potential. According to the United States Department of Agriculture (USDA) Natural Resources Conservation

Service (NRCS), the soils in the project area are primarily comprised of Nunn-Urban land complex with some portions of Englewood-Urban land complex. Refer to Appendix

A for the soil maps.

1.2.3. Major Drainageways

There are no major drainageways within the project. The entire project drains to Clear

Creek via street conveyance, storm inlets and pipe.

2. HYDROLOGY

2.1. Drainage Basin Map

Drainage basins were delineated using survey information and supplemented with 2020

LiDAR data outside of the project limits. The Rational Method was used to complete hydrology calculations using the MHFD Rational spreadsheet.

2.2. Major Basin Description

There are no major cross-drainage waterways that pass through the project area and no major offsite basin delineation was required for the project. The project site flows directly to

Clear Creek.

2.3. On-Site Description

Five basins were delineated for both existing and proposed conditions.

024-03656 6

E01/P01-This basin delineates flow contributing to the 20’ Type R inlet that will be installed as part of the Improve Wadsworth project.

E02/P02-This basin delineates flow contributing to the existing No.16 Combination inlet and proposed 10’ Type R inlet at station 113+50.

E03/P03- This basin delineates flow contributing to the existing RMWC 6’x3’ box culvert.

E04/PR04- This basin delineates flow contributing to the existing and proposed No.16

Combination inlet located in the curb return at the southwest corner of 32nd Avenue and

Wadsworth Blvd. intersection.

E05/P05- This basin delineates flow contributing to the existing 6’x3’ box culvert that flows east under Wadsworth Blvd.

Table 1: Existing and Proposed Initial and Major Flows

Basin Existing 5-year Flows (cfs)/ Proposed 5-year Flows (cfs)

Existing 100-year Flows (cfs)/ Proposed 100-year Flows (cfs)

E01/P01 4.24/4.27 12.59/12.68

E02/P02 2.94/3.08 7.98/8.37

E03/P03 17.67/17.58 52.51/52.25

E04/PR04 17.62/17.62 47.85/47.85

E05/P05 0.18/0.18 0.68/0.68

Total 42.65/42.73 121.61/121.83

2.4. Precipitation Data

The project is located in the City of Wheat Ridge; therefore, the City of Wheat Ridge drainage design criteria was applied and supplemented with Mile High Flood District (MHFD)

Criteria as required. Precipitation data is developed in accordance with the MHFD guidance using the point precipitation frequency estimates from NOAA Atlas 14, Volume 8, Version 2 for Wheat Ridge, Colorado. Refer to Appendix A for precipitation data.

2.5. Design Flood Frequency

Design flood frequency was selected per the City of Wheat Ridge Site Drainage

Requirements. Refer to Figures 2 and 3 for the criteria from MHFD that are applicable to this project. Wadsworth Blvd. from 32nd Avenue to 35th Avenue is generally two lanes in each direction with separate continuous turn lanes in both directions.

Wadsworth Blvd. is posted at 40 miles per hour (mph) and is classified as a principal arterial.

The 5-year and 100-year events will be used for the initial/minor and major system designs, respectively. Wheat Ridge defers to MHFD on inlet design criteria. The initial/minor storm event spread is limited to no curb overtopping and flow spread must leave at least one lane

024-03656 7 free of water in each direction and should not flood more than two lanes in each direction.

For the major event residential dwellings and public, commercial, and industrial buildings should be no less than 12 inches above the 100-year flood at the ground line or lowest water entry of the building. The depth of water should not exceed the street crown to allow the operation of emergency vehicles. The depth of water over the gutter flow line should not exceed 12 inches.

Figure 2: MHFD Initial Storm Street Capacity Criteria

Figure 3: MHFD Major Storm Street Capacity Criteria

024-03656 8

3. EXISTING STRUCTURES

There is one major cross culvert CDOT structure number 121A015250BL, a 6-foot wide by 3-foot-high box culvert within the project limits located at approximately station 109+75. There is no proposed change to the area contributing to this box culvert, therefore a hydraulic analysis was not completed. At the request of the RMWC, the existing headwalls and wingwalls will be removed, a bulkhead will be installed at the end of the box culvert, and a 24” RCP will extend to a manhole to collect offsite drainage falling into the adjacent lot as well as diversion drainage from the RMWC ditch to the south. The culvert runs east under Wadsworth Blvd and outfalls to an open channel that continues to flow to the east.

The existing inlets located at stations 103+25 and 113+50 will be removed and replaced with new inlets due to the realignment and replacement of the existing curb and gutter. There are minor changes to the flows contributing to these inlets due to the increase in impervious surface. The inlet at 115+75 will remain in place and will not be impacted by this project. As part of the removal and replacement of the inlet at 113+50 a portion of the existing storm sewer will be removed and replaced.

In addition to the CDOT 6’x3’ concrete box that runs under Wadsworth Blvd there is an existing

RMWC 6’x3’ box that runs along the western portion of Wadsworth Blvd. The RMWC 6’x3’ concrete box culvert will be shifted west to accommodate the sidewalk improvements. The vertical alignment will match existing. There are minimal impacts to the flows contributing to the box, and no impacts to the hydraulics are anticipated. No hydraulic analysis is being completed as part of this project.

From station 107+00 to the north project limits, surface drainage is collected within the inlets located at 113+50 and 115+75 and conveyed via the existing storm pipe that drains towards the

Improve Wadsworth Project. The storm drain system drains into a water quality pond and ultimately into Clear Creek. From station 107+00 to the south project limits, surface drainage is collected in the inlets located at 32nd Avenue and Wadsworth Blvd. This storm system drains east in 32nd Avenue and ultimately outfalls into Clear Creek.

4. DESIGN DISCUSSION

The proposed drainage design is limited to removing and replacing existing inlets located at stations 103+25 and 113+50, removing and replacing the existing pipe at station 113+50, removing the existing headwall and wingwalls and bulkheading the existing CDOT 6’x3’ concrete box culvert and adding 24” RCP extension near station 109+75, and shifting the existing RMWC 6’x3’ concrete box culvert that runs parallel to Wadsworth Blvd. from station

109+25 to 104+41. There are minor changes to tributary areas and percent impervious that

024-03656 9 increase flows at design points 1 and 2. Design points 3, 4 and 5 all reduce flows, or the flows remain the same. Refer to the hydrology maps located in Appendix A for design point locations.

The Inlets P01 and P02 meet the City of Wheat Ridge and MHFD spread design criteria. Inlet

P04 does not meet the City of Wheat Ridge or MHFD spread design criteria due to the large contributing area upstream and no upstream inlets. In order to meet criteria a storm system with inlets and pipes would need to be placed in 32nd Avenue, which is outside the scope of this project.

This project disturbs more than one acre, which would therefore require water quality treatment per the City’s MS4 permit.

5. RECOMMENDED DESIGN

5.1. Inlets

Inlets were analyzed to meet spread requirements as outlined in Section 2.5. See Appendix B for these calculations using MHFD spreadsheet, UD-Inlet (v 5.03). The project is using a combination of Type R inlets and Wheat Ridge Curb inlets. Inlets P01 and P02 meet spread criteria. Spread criteria at inlet P04 cannot be met as there are no inlets on 32nd Ave. upstream of the intersection. An additional inlet can be added upstream of the intersection; however the conveyance is limited by the existing 12” storm pipe. A separate storm system improvement project is recommended in 32nd Avenue to improve conveyance.

5.2. Storm Drain

A portion of storm pipe is proposed to be removed and replaced at IN-P02. Flows are not changing at this location, and no hydraulic analysis was performed. The RMWC 3’x6’ culvert that runs along Wadsworth Blvd. will be relocated west to accommodate the proposed improvements. The existing CDOT 6’x3’ box culvert headwalls and wingwalls will be removed, a bulkhead will be installed at the end of the box culvert, and a 24” RCP will extend to a manhole to collect offsite drainage falling into the adjacent lot as well as diversion drainage from the

RMWC ditch to the south. The RMWC 6’x3’ box culvert that runs parallel to Wadsworth Blvd will be relocated to accommodate the proposed sidewalk improvements. No hydraulic analysis was completed on either of the two 6’x3’ box culverts as the improvements will minimally impact flows contributing to the structures, and no change in hydraulic performance is anticipated.

5.3. Detention/Water Quality

This project is not required to provide detention and aligns with the design of the Improve

Wadsworth project to the north. The increase in impervious surface is less than 2% resulting in

024-03656 10 an increase in runoff of approximately 0.22 cfs, resulting in less than 0.01 ac-feet of required detention. Due to the minimal increase in runoff, there will be minimal impact to the downstream storm system and pond. The Improve Wadsworth drainage design, including storm sewer, pond and bypass flow design, can accommodate the minimal increases in impervious surface created by this project.

The project disturbs over one acre; therefore, water quality is required. The total treatment area required is 1.59 acres. The WQCV standard is recommended to satisfy the MS4 permit, with the recommended control measure a water quality pond. Since over 80% of this project drains to the Improve Wadsworth pond located to the north, the pond was reviewed to evaluate the feasibility of treating this project within the pond. The Improve Wadsworth Project was sized to capture and treat a total area of 21.3 acres. Of the total 21.3 acres, a total of 1.29 acres of this project area included within the water quality pond sizing. The Improve Wadsworth Project was required to provide treatment for approximately 1.6 acres of pavement; however, it was sized to accommodate approximately 13.1 acres. Based on the design of the Improve Wadsworth water quality pond, the pond can provide the required water quality treatment for this project with no modifications to the pond. Refer to Appendix C for reference information on the pond design.

Additionally, due to site constraints (existing grades and utilities), 20% of the project will not be able to be treated. The south portion of the project cannot be collected and conveyed to the water quality pond near Clear Creek. This meets the requirements of the general MS4 permit section 4 ii. A.1. Refer to Appendix C for the applicable MS4 post construction water quality requirements. Since both the north and south portions of this project ultimately drain to Clear

Creek, the project proposes treating additional area to the north within the Improve Wadsworth

Water pond to make up for the area untreated in the south. This approach was accepted by the

City of Wheat Ridge in March of 2025 when consideration for modifications to the north pond were requested. Refer to Appendix C for water quality approach documentation and correspondence.

024-03656 11

REFERENCES

Colorado Department of Transportation. 2019. Drainage Design Manual. Chapters 7, 9, 13 and

16. December 2024. 2019 Drainage Design Manual — Colorado Department of Transportation

HDR. November 2020. Hydraulic Design Report Wadsworth Blvd. Widening from 35th Avenue to

Interstate 70. Wheat Ridge Colorado.

Mile High Flood District. 2024. Urban Storm Drainage Criteria Manual, Volume 1 Management, Hydrology and Hydraulics. December 2024. Criteria Manual Volume 1 | Mile High Flood District

Mile High Flood District. 2024. Urban Storm Drainage Criteria Manual, Volume 3 Stormwater

Quality. December 2024. 01_USDCM-Volume-3.pdf

NOAA. 2024. Atlas 14, Volume 8, Version 2. December 2024. PF Map: Contiguous US

United States Department of Agriculture. 2024. Web Soil Survey. December 2024.

https://websoilsurvey.nrcs.usda.gov/app/

APPENDIX A

HYDROLOGY

U

1+

2+

3+

4+

5+

6+

7+

8+

9+

0+

1+

2+

3+

4+

5+

6+

7+

8+

9+

54955500

550555 05 5505

10 5470

548054855490

NUMBERS

STRUCTURE

NO REVISIONS:

REVISED:

VOID: SHEET SUBSET:

DETAILER:

DESIGNER:

SHEET NUMBER:SUBSET SHEETS:

INIT.COMMENTSDATE:

SHEET REVISIONS AS CONSTRUCTEDJuly 14, 2025PRINT DATE:

VERT. SCALE:

FILE NAME:

UNIT INFORMATION

W_HMAP01_02403656.DWG

HORIZ. SCALE:

PROJECT NO./CODE

Suite 400 Denver, CO 80204

1525 Raleigh St

PROJECT NO.:

CODE:

City of Wheat Ridge

OF

7500 W. 29th Ave.

Wheat Ridge, CO 80033 Phone: 303-205-7600

Region 1

CDOT

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NOT FOR

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BGK

25614

AQC M361-013

LEGEND

A = BASIN DESCRIPTION

B = AREA (AC)

C = 10-YR RUNOFF

COEFFICIENT (C10)

D = 100-YR RUNOFF

COEFFICIENT (C100)

E = DESIGN POINT

CB

A

D

E

EXISTING BASIN

EXISTING MAJOR

CONTOUR

EXISTING MINOR

CONTOUR

FLOW PATH

0.5718.37

E03

0.73

0.6515.61

E04

0.77

0.572.88

E01

0.73

0.651.38

E02

0.77

P04

E02

E01

E03

EXISTING HYDROLOGY MAP

W 32ND AVE

W 35TH AVE

W

AD

SW

O

R

TH

B

LV

D

ZE

PH

YR

C

T

YA

R

R O

W C

T

YA

R

R O

W S

T

W 34TH AVE

E05

0.430.16

E05

0.65

J. BEYNER

J. BEYNER

1 2HYDROLOGY N/A

SCALE IN FEET

20' 40'10'0'

Designer:

Company: 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr

Date: 1-hour rainfall depth, P1 (in) = 0.78 1.04 1.28 1.63 1.92 2.22 2.99 Project: a b c

Location: Rainfall Intensity Equation Coefficients = 28.50 10.00 0.786

2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr Overland

Flow Length Li (ft)

U/S Elevation

(ft) (Optional)

D/S Elevation

(ft) (Optional)

Overland Flow Slope

Si (ft/ft)

Overland Flow Time ti (min)

Channelized Flow Length

Lt (ft)

U/S Elevation

(ft) (Optional)

D/S Elevation

(ft) (Optional)

Channelized Flow Slope

St (ft/ft)

NRCS

Conveyance

Factor K

Channelized Flow

Velocity Vt (ft/sec)

Channelized Flow Time tt (min)

Computed tc (min)

Regional tc (min)

Selected tc (min) 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr

0.47 0.52 0.57 0.66 0.69 0.73 0.78 8.83 10.08 10.08 2.09 2.80 3.45 4.40 5.18 5.99 8.06 2.83 4.24 5.70 8.30 10.29 12.59 18.06

0.56 0.61 0.65 0.71 0.74 0.77 0.81 3.61 4.98 5.00 2.63 3.53 4.34 5.53 6.51 7.53 10.14 2.02 2.94 3.86 5.41 6.62 7.98 11.28

0.47 0.52 0.57 0.66 0.69 0.73 0.78 8.89 24.44 24.44 1.37 1.84 2.26 2.88 3.39 3.92 5.28 11.82 17.67 23.78 34.62 42.92 52.51 75.33

0.56 0.61 0.65 0.71 0.74 0.77 0.81 13.31 23.78 23.78 1.39 1.86 2.29 2.92 3.44 3.98 5.36 12.12 17.62 23.15 32.43 39.69 47.85 67.64

0.30 0.36 0.43 0.54 0.59 0.65 0.71 5.87 7.73 7.73 2.30 3.09 3.81 4.85 5.71 6.60 8.89 0.11 0.18 0.26 0.42 0.53 0.68 1.00

5532.73 5528.00 0.016 1804.00 5528.00 5490.80 0.021

33.00 5494.66 5493.70 0.029 422.00E02 1.38

20.48

25.24

E05 0.16 C 40.0 57.60 5490.89 5487.88 0.052 190.30 5487.88 5482.39 0.029 10 1.70 1.87

33.67

E04 15.61 C 70.0 300.00

Cells of this color are for calculated results based on overrides

Joshua Beyner Olsson 12/13/2024 Wadsworth Path 32nd to 35th lakewood Colorado

Version 2.00 released May 2017

20 2.87 10.47

15.56

E03 18.37 C 60.0 300.00 5519.50 5494.00 0.085 1146.70 5494.00 5489.67 0.004 20 1.23

5493.70

15.55

5466.00 0.066 20 5.12 1.37C 70.0

0.087300.00 5492.05 5466.00

Rainfall Intensity, I (in/hr)

3.17 1.25 17.24200.0255460.005466.00238.66

Peak Flow, Q (cfs)

Calculation of Peak Runoff using Rational Method

Overland (Initial) Flow Time Channelized (Travel) Flow Time Time of ConcentrationRunoff Coefficient, C

Subcatchment Name

Area (ac)

NRCS

Hydrologic Soil Group

Percent Imperviousnes s

E01 2.88 C 60.0

Select UDFCD location for NOAA Atlas 14 Rainfall Depths from the pulldown list OR enter your own depths obtained from the NOAA website (click this link)

Cells of this color are for required user-input Cells of this color are for optional override values

I 𝑖𝑛/ℎ𝑟 = a ∗ Pଵ b + tୡ ୡ t୧ =

0.395 1.1 − Cହ L୧

S୧ .ଷଷ t୲ = L୲

60K S୲

L୲

60V୲

Computed tୡ = t୧ + t୲

Regional tୡ = 26 − 17i + L୲

60 14i + 9 S୲

Selected tୡ = max t୫୧୬୧୫୳୫ , min Computed tୡ , Regional tୡ t୫୧୬୧୫୳୫= 5 (urban) t୫୧୬୧୫୳୫= 10 (non-urban)

Q 𝑐𝑓𝑠 = CIA

MH

MH

MH

MH

1+

2+

3+

4+

5+

6+

7+

8+

9+

0+

1+

2+

3+

4+

5+

6+

7+

8+

9+

54955500

550555 05 5505

10 5470

548054855490

NUMBERS

STRUCTURE

NO REVISIONS:

REVISED:

VOID: SHEET SUBSET:

DETAILER:

DESIGNER:

SHEET NUMBER:SUBSET SHEETS:

INIT.COMMENTSDATE:

SHEET REVISIONS AS CONSTRUCTEDJuly 14, 2025PRINT DATE:

VERT. SCALE:

FILE NAME:

UNIT INFORMATION

W_HMAP01_02403656.DWG

HORIZ. SCALE:

PROJECT NO./CODE

Suite 400 Denver, CO 80204

1525 Raleigh St

PROJECT NO.:

CODE:

City of Wheat Ridge

OF

7500 W. 29th Ave.

Wheat Ridge, CO 80033 Phone: 303-205-7600

Region 1

CDOT

F:

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4\

1-

0\

4-

6\

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Au to

C

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\F in al P la ns

\S he et s\

W

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\W _H

M

AP

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6.

dw g

D

AT

E:

J ul

4, :1

4p m

SE

R

: j be yn er

NOT FOR

CONSTRUCTION

BGK

25614

AQC M361-013

LEGEND

A = BASIN DESCRIPTION

B = AREA (AC)

C = 10-YR RUNOFF

COEFFICIENT (C10)

D = 100-YR RUNOFF

COEFFICIENT (C100)

E = DESIGN POINT

CB

A

D

E

PROPOSED BASIN

EXISTING MAJOR

CONTOUR

EXISTING MINOR

CONTOUR

FLOW PATH

0.5718.28

P03

0.73

0.6515.61

P04

0.77

0.572.90

P01

0.73

0.651.44

P02

0.77

P04

P02

P03

PROPOSED HYDROLOGY MAP

W 32ND AVE

W 35TH AVE

W

AD

SW

O

R

TH

B

LV

D

ZE

PH

YR

C

T

YA

R

R O

W C

T

YA

R

R O

W S

T

W 34TH AVE

P01

P05

0.430.16

P05

0.65

J. BEYNER

J. BEYNER

2 2HYDROLOGY N/A

SCALE IN FEET

20' 40'10'0'

Designer:

Company: 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr

Date: 1-hour rainfall depth, P1 (in) = 0.78 1.04 1.28 1.63 1.92 2.22 2.99

Project: a b c

Location: Rainfall Intensity Equation Coefficients = 28.50 10.00 0.786

2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr

Overland

Flow Length

Li (ft)

U/S Elevation

(ft)

(Optional)

D/S Elevation

(ft)

(Optional)

Overland

Flow Slope

Si (ft/ft)

Overland

Flow Time ti (min)

Channelized

Flow Length

Lt (ft)

U/S Elevation

(ft)

(Optional)

D/S Elevation

(ft)

(Optional)

Channelized

Flow Slope

St (ft/ft)

NRCS

Conveyance

Factor K

Channelized

Flow

Velocity

Vt (ft/sec)

Channelized

Flow Time tt (min)

Computed tc (min)

Regional tc (min)

Selected tc (min) 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr

0.47 0.52 0.57 0.66 0.69 0.73 0.78 8.83 10.09 10.09 2.09 2.80 3.45 4.40 5.18 5.99 8.06 2.85 4.27 5.74 8.36 10.37 12.68 18.20

0.56 0.61 0.65 0.71 0.74 0.77 0.81 3.60 4.98 5.00 2.63 3.53 4.34 5.53 6.51 7.53 10.14 2.12 3.08 4.05 5.67 6.94 8.37 11.83

0.47 0.52 0.57 0.66 0.69 0.73 0.78 8.89 24.44 24.44 1.37 1.84 2.26 2.88 3.39 3.92 5.28 11.76 17.58 23.67 34.45 42.71 52.25 74.97

0.56 0.61 0.65 0.71 0.74 0.77 0.81 13.31 23.78 23.78 1.39 1.86 2.29 2.92 3.44 3.98 5.36 12.12 17.62 23.15 32.43 39.69 47.85 67.64

0.30 0.36 0.43 0.54 0.59 0.65 0.71 5.87 7.73 7.73 2.30 3.09 3.81 4.85 5.71 6.60 8.89 0.11 0.18 0.26 0.42 0.53 0.68 1.00

0.83 0.85 0.87 0.88 0.89 0.89 0.90 1.82 4.27 5.00 2.63 3.53 4.34 5.53 6.51 7.53 10.14 1.54 2.11 2.64 3.41 4.06 4.72 6.43

0.83 0.85 0.87 0.88 0.89 0.89 0.90 3.83 5.09 5.09 2.62 3.51 4.32 5.50 6.48 7.49 10.09 0.77 1.05 1.32 1.70 2.02 2.35 3.20

C 70.0

0.087300.00 5492.06 5466.00

Rainfall Intensity, I (in/hr)

3.17 1.26 17.25200.0255460.005466.00239.30

Peak Flow, Q (cfs)

Calculation of Peak Runoff using Rational Method

Overland (Initial) Flow Time Channelized (Travel) Flow Time Time of ConcentrationRunoff Coefficient, C

Subcatchment

Name

Area

(ac)

NRCS

Hydrologic

Soil Group

Percent

Imperviousnes s

P01 2.90 C 60.0

Select UDFCD location for NOAA Atlas 14 Rainfall Depths from the pulldown list OR enter your own depths obtained from the NOAA website (click this link)

Cells of this color are for required user-input

Cells of this color are for optional override values

Cells of this color are for calculated results based on overrides

Joshua Beyner

Olsson

5/7/2025

Wadsworth Path 32nd to 35th lakewood Colorado

Version 2.00 released May 2017

20 2.87 10.47

15.57

P03 18.28 C 60.0 300.00 5519.50 5494.00 0.085 1146.70 5494.00 5489.67 0.004 20 1.23

5493.70

15.55

5466.00 0.065 20 5.12 1.3833.10 5494.67 5493.70 0.029 423.40P02 1.44

20.48

25.24

P05 (no change) 0.16 C 40.0 57.60 5490.89 5487.88 0.052 190.30 5487.88 5482.39 0.029 10 1.70 1.87

33.67

P04 (no change) 15.61 C 70.0 300.00 5532.73 5528.00 0.016 1804.00 5528.00 5490.80 0.021

WQ P02 0.70 C 100.0 33.10 5494.67 5493.70 0.029 662.70 5493.70 5460.00 0.051 20 4.51 2.45

10.10

11.13

WQ P01 0.35 C 100.0 300.00 5492.06 5466.00 0.087 239.30 5466.00 5460.00 0.025 20 3.17 1.26

I ��/ℎ� = a ∗ P� b + t� t� =

0.395 1.1 − C� L�

S� t� = L�

60K S�

L�

60V�

Computed t� = t� + t�

Regional t� = 26 − 17i + L�

60 14i + 9 S�

Selected t� = max t3�4�353 , min Computed t� , Regional t� t3�4�353= 5 (urban) t3�4�353= 10 (non-urban)

Q 89: = CIA

Supplementary Design Information for UD-Rational Workbook Urban Storm Drainage Criteria Manual (USDCM) Volume 1, Chapter 6 - Runoff (March 2017)

Version 2.00 released May 2017

Hydrologic Soil Group—Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

11/13/2024

490500 490800 491100 491400 491700 492000 492300 492600 492900 493200

490500 490800 491100 491400 491700 492000 492300 492600 492900 493200

39° 46' 22'' N

5°

' 4 4'

' W 39° 46' 22'' N

5°

' 4

1' ' W

39° 45' 21'' N

5°

' 4

4' ' W

39° 45' 21'' N

5°

' 4

1' ' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 500 1000 2000 3000

Feet 0 150 300 600 900

Meters Map Scale: 1:13,400 if printed on A landscape (11" x 8.5") sheet.

Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI) Area of Interest (AOI)

Soils Soil Rating Polygons

A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating Lines A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating Points A

A/D

B

B/D

C

C/D

D

Not rated or not available

Water Features Streams and Canals

Transportation Rails

Interstate Highways

US Routes

Major Roads

Local Roads

Background Aerial Photography

The soil surveys that comprise your AOI were mapped at 1:24,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for map measurements.

Source of Map: Natural Resources Conservation Service Web Soil Survey URL:

Coordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties Survey Area Data: Version 19, Aug 29, 2024

Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.

Date(s) aerial images were photographed: Jul 1, 2020—Jul 2, The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.

Hydrologic Soil Group—Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

11/13/2024

Hydrologic Soil Group

Map unit symbol Map unit name Rating Acres in AOI Percent of AOI

32 Denver-Kutch-Urban land complex, 5 to 9 percent slopes

C 8.1 2.3%

44 Englewood-Urban land complex, 0 to 2 percent slopes

C 6.5 1.8%

80 Leyden-Primen- Standley cobbly clay loams, 15 to 50 percent slopes

D 0.6 0.2%

105 Nunn-Urban land complex, 0 to 2 percent slopes

C 161.8 44.9%

106 Nunn-Urban land complex, 2 to 5 percent slopes

C 104.0 28.8%

107 Nunn-Urban land complex, 5 to 9 percent slopes

C 71.0 19.7%

178 Water 8.7 2.4%

Totals for Area of Interest 360.8 100.0%

Hydrologic Soil Group—Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

Description

Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms.

The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture.

These soils have a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission.

If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes.

Rating Options

Aggregation Method: Dominant Condition

Component Percent Cutoff: None Specified

Tie-break Rule: Higher

Hydrologic Soil Group—Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

Hydrologic Soil Group—Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

11/13/2024

492400 492500 492600 492700 492800 492900 493000 493100

492400 492500 492600 492700 492800 492900 493000 493100

39° 46' 12'' N

5°

' 2 0'

' W 39° 46' 12'' N

5°

' 4

8' ' W

39° 45' 40'' N

5°

' 2

0' ' W

39° 45' 40'' N

5°

' 4

8' ' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 200 400 800 1200

Feet 0 50 100 200 300

Meters Map Scale: 1:4,830 if printed on A portrait (8.5" x 11") sheet.

Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI) Area of Interest (AOI)

Soils Soil Rating Polygons

A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating Lines A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating Points A

A/D

B

B/D

C

C/D

D

Not rated or not available

Water Features Streams and Canals

Transportation Rails

Interstate Highways

US Routes

Major Roads

Local Roads

Background Aerial Photography

The soil surveys that comprise your AOI were mapped at 1:24,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for map measurements.

Source of Map: Natural Resources Conservation Service Web Soil Survey URL:

Coordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties Survey Area Data: Version 19, Aug 29, 2024

Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.

Date(s) aerial images were photographed: Jul 1, 2020—Jul 2, The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.

Hydrologic Soil Group—Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

Hydrologic Soil Group

Map unit symbol Map unit name Rating Acres in AOI Percent of AOI

44 Englewood-Urban land complex, 0 to 2 percent slopes

C 7.5 5.9%

105 Nunn-Urban land complex, 0 to 2 percent slopes

C 36.7 28.8%

106 Nunn-Urban land complex, 2 to 5 percent slopes

C 56.5 44.4%

107 Nunn-Urban land complex, 5 to 9 percent slopes

C 26.6 20.9%

Totals for Area of Interest 127.2 100.0%

Hydrologic Soil Group—Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

Description

Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms.

The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture.

These soils have a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission.

If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes.

Rating Options

Aggregation Method: Dominant Condition

Component Percent Cutoff: None Specified

Tie-break Rule: Higher

Hydrologic Soil Group—Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

APPENDIX B

HYDRAULICS

MHFD-Inlet, Version 5.03 (August 2023)

Worksheet Protected

INLET NAME P04 P02 P01

Site Type (Urban or Rural) URBAN URBAN URBAN Inlet Application (Street or Area) STREET STREET STREET Hydraulic Condition In Sump On Grade On Grade Inlet Type Denver No. 16 Combination CDOT Type R Curb Opening CDOT Type R Curb Opening

USER-DEFINED INPUT

User-Defined Design Flows Minor QKnown (cfs) 23.2 4.1 5.7 Major QKnown (cfs) 47.9 8.4 12.7

Bypass (Carry-Over) Flow from Upstream Inlets must be organized from upstream (left) to downstream (right) in order for bypass flows to be linked.

Receive Bypass Flow from: No Bypass Flow Received No Bypass Flow Received P02 Minor Bypass Flow Received, Qb (cfs) 0.0 0.0 0.0 Major Bypass Flow Received, Qb (cfs) 0.0 0.0 1.6

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, Tr (years) One-Hour Precipitation, P1 (inches)

Major Storm Rainfall Input Design Storm Return Period, Tr (years) One-Hour Precipitation, P1 (inches)

CALCULATED OUTPUT

Minor Total Design Peak Flow, Q (cfs) 23.2 4.1 5.8 Major Total Design Peak Flow, Q (cfs) 47.9 8.4 14.3 Minor Flow Bypassed Downstream, Qb (cfs) N/A 0.0 0.0 Major Flow Bypassed Downstream, Qb (cfs) N/A 1.6 0.4

INLET MANAGEMENT

MHFD-Inlet, Version 5.03 (August 2023)

Worksheet Protected

INLET NAME

Site Type (Urban or Rural) Inlet Application (Street or Area) Hydraulic Condition Inlet Type

USER-DEFINED INPUT

User-Defined Design Flows Minor QKnown (cfs) Major QKnown (cfs)

Bypass (Carry-Over) Flow from Upstream Receive Bypass Flow from:

Minor Bypass Flow Received, Qb (cfs) Major Bypass Flow Received, Qb (cfs)

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, Tr (years) One-Hour Precipitation, P1 (inches)

Major Storm Rainfall Input Design Storm Return Period, Tr (years) One-Hour Precipitation, P1 (inches)

CALCULATED OUTPUT

Minor Total Design Peak Flow, Q (cfs) Major Total Design Peak Flow, Q (cfs) Minor Flow Bypassed Downstream, Qb (cfs) Major Flow Bypassed Downstream, Qb (cfs)

INLET MANAGEMENT

HDR_IN-A3 User-Defined

URBAN

STREET

On Grade CDOT Type R Curb Opening

0.9 2.0

P01 0.0 0.4

0.9 2.4 0.0 0.0

Project:

Inlet ID:

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 16.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb) SBACK = 0.015 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020) nBACK = 0.012

Height of Curb at Gutter Flow Line HCURB = 6.00 inches Distance from Curb Face to Street Crown TCROWN = 30.0 ft Gutter Width W = 2.00 ft Street Transverse Slope SX = 0.031 ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft) SW = 0.083 ft/ft Street Longitudinal Slope - Enter 0 for sump condition SO = 0.000 ft/ft Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.016

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 6.0 30.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 6.0 inches Check boxes are not applicable in SUMP conditions

MINOR STORM Allowable Capacity is not applicable to Sump Condition Minor Storm Major Storm MAJOR STORM Allowable Capacity is not applicable to Sump Condition Qallow = SUMP SUMP cfs

MHFD-Inlet, Version 5.03 (August 2023)

ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)

P04

02403656_PR_MHFD-Inlet_v5.03, P04 12/16/2024, 12:49 PM

Design Information (Input) MINOR MAJOR Type of Inlet Type = Local Depression (additional to continuous gutter depression 'a' from above) alocal = 2.00 2.00 inches Number of Unit Inlets (Grate or Curb Opening) No = 1 1 Water Depth at Flowline (outside of local depression) Ponding Depth = 3.5 8.0 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 Open Area Ratio for a Grate (typical values 0.15-0.90) Aratio = 0.31 0.31 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) = 3.60 3.60 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 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 2.3-3.7) Cw (C) = 3.70 3.70 Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.66 0.66

Low Head Performance Reduction (Calculated) MINOR MAJOR Depth for Grate Midwidth dGrate = 0.31 0.69 ft Depth for Curb Opening Weir Equation dCurb = 0.12 0.50 ft Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.54 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = N/A N/A Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.54 1.00

MINOR MAJOR

Total Inlet Interception Capacity (assumes clogged condition) Qa = 1.1 7.6 cfs WARNING: Inlet Capacity < Q Peak for Minor and Major Storms Q PEAK REQUIRED = 23.2 47.9 cfs

INLET IN A SUMP OR SAG LOCATION

MHFD-Inlet, Version 5.03 (August 2023)

Denver No. 16 Combination

H-Vert H-Curb

W

Lo (C)

Lo (G)

Wo

WP

Denver No. 16 Combination

Override Depths

02403656_PR_MHFD-Inlet_v5.03, P04 12/16/2024, 12:49 PM

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 16.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb) SBACK = 0.015 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020) nBACK = 0.013

Height of Curb at Gutter Flow Line HCURB = 6.00 inches Distance from Curb Face to Street Crown TCROWN = 30.0 ft Gutter Width W = 2.00 ft Street Transverse Slope SX = 0.031 ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft) SW = 0.083 ft/ft Street Longitudinal Slope - Enter 0 for sump condition SO = 0.045 ft/ft Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.016

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 6.0 30.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 6.0 inches Allow Flow Depth at Street Crown (check box for yes, leave blank for no)

MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow = 3.8 26.0 cfs

MHFD-Inlet, Version 5.03 (August 2023)

ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)

P02

WARNING: MINOR STORM max. allowable capacity is less than the design peak flow of 4.05 cfs on sheet 'Inlet Management' Major storm max. allowable capacity GOOD - greater than the design peak flow of 8.37 cfs on sheet 'Inlet Management'

02403656_PR_MHFD-Inlet_v5.03, P02 12/16/2024, 12:49 PM

Local Depression (additional to continuous gutter depression 'a') aLOCAL = 3.0 3.0 inches Total Number of Units in the Inlet (Grate or Curb Opening) No = 1 1 Length of a Single Unit Inlet (Grate or Curb Opening) Lo = 10.00 10.00 ft Width of a Unit Grate (cannot be greater than W, Gutter Width) Wo = N/A N/A ft Clogging Factor for a Single Unit Grate (typical min. value = 0.5) Cf (G) = N/A N/A Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1) Cf (C) = 0.10 0.10 Street Hydraulics: WARNING: Q > ALLOWABLE Q FOR MINOR & MAJOR STORM MINOR MAJOR Total Inlet Interception Capacity Q = 4.0 6.7 cfs Total Inlet Carry-Over Flow (flow bypassing inlet) Qb = 0.0 1.6 cfs Capture Percentage = Qa/Qo C% = 99 80 %

INLET ON A CONTINUOUS GRADE

MHFD-Inlet, Version 5.03 (August 2023)

CDOT Type R Curb Opening CDOT Type R Curb Opening

02403656_PR_MHFD-Inlet_v5.03, P02 12/16/2024, 12:49 PM

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 16.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb) SBACK = 0.015 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020) nBACK = 0.013

Height of Curb at Gutter Flow Line HCURB = 6.00 inches Distance from Curb Face to Street Crown TCROWN = 30.0 ft Gutter Width W = 2.00 ft Street Transverse Slope SX = 0.033 ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft) SW = 0.083 ft/ft Street Longitudinal Slope - Enter 0 for sump condition SO = 0.010 ft/ft Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.016

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 6.0 30.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 6.0 inches Allow Flow Depth at Street Crown (check box for yes, leave blank for no)

MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow = 2.0 27.1 cfs

MHFD-Inlet, Version 5.03 (August 2023)

ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)

P01

WARNING: MINOR STORM max. allowable capacity is less than the design peak flow of 5.77 cfs on sheet 'Inlet Management' Major storm max. allowable capacity GOOD - greater than the design peak flow of 14.32 cfs on sheet 'Inlet Management'

02403656_PR_MHFD-Inlet_v5.03, P01 12/16/2024, 12:49 PM

Local Depression (additional to continuous gutter depression 'a') aLOCAL = 3.0 3.0 inches Total Number of Units in the Inlet (Grate or Curb Opening) No = 1 1 Length of a Single Unit Inlet (Grate or Curb Opening) Lo = 20.00 20.00 ft Width of a Unit Grate (cannot be greater than W, Gutter Width) Wo = N/A N/A ft Clogging Factor for a Single Unit Grate (typical min. value = 0.5) Cf (G) = N/A N/A Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1) Cf (C) = 0.10 0.10 Street Hydraulics: WARNING: Q > ALLOWABLE Q FOR MINOR & MAJOR STORM MINOR MAJOR Total Inlet Interception Capacity Q = 5.8 13.9 cfs Total Inlet Carry-Over Flow (flow bypassing inlet) Qb = 0.0 0.4 cfs Capture Percentage = Qa/Qo C% = 100 97 %

INLET ON A CONTINUOUS GRADE

MHFD-Inlet, Version 5.03 (August 2023)

CDOT Type R Curb Opening

02403656_PR_MHFD-Inlet_v5.03, P01 12/16/2024, 12:49 PM

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 9.5 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb) SBACK = 0.015 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020) nBACK = 0.013

Height of Curb at Gutter Flow Line HCURB = 6.00 inches Distance from Curb Face to Street Crown TCROWN = 30.0 ft Gutter Width W = 2.00 ft Street Transverse Slope SX = 0.020 ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft) SW = 0.083 ft/ft Street Longitudinal Slope - Enter 0 for sump condition SO = 0.004 ft/ft Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.016

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 6.0 30.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 6.0 inches Allow Flow Depth at Street Crown (check box for yes, leave blank for no)

MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow = 0.7 23.8 cfs

MHFD-Inlet, Version 5.03 (August 2023)

ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)

HDR_IN-A3

WARNING: MINOR STORM max. allowable capacity is less than the design peak flow of 0.86 cfs on sheet 'Inlet Management' Major storm max. allowable capacity GOOD - greater than the design peak flow of 2.35 cfs on sheet 'Inlet Management'

02403656_PR_MHFD-Inlet_v5.03, HDR_IN-A3 12/16/2024, 12:49 PM

Local Depression (additional to continuous gutter depression 'a') aLOCAL = 3.0 3.0 inches Total Number of Units in the Inlet (Grate or Curb Opening) No = 2 2 Length of a Single Unit Inlet (Grate or Curb Opening) Lo = 5 5.00 ft Width of a Unit Grate (cannot be greater than W, Gutter Width) Wo = N/A N/A ft Clogging Factor for a Single Unit Grate (typical min. value = 0.5) Cf (G) = N/A N/A Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1) Cf (C) = 0.10 0.10 Street Hydraulics: WARNING: Q > ALLOWABLE Q FOR MINOR & MAJOR STORM MINOR MAJOR Total Inlet Interception Capacity Q = 0.9 2.4 cfs Total Inlet Carry-Over Flow (flow bypassing inlet) Qb = 0.0 0.0 cfs Capture Percentage = Qa/Qo C% = 100 100 %

INLET ON A CONTINUOUS GRADE

MHFD-Inlet, Version 5.03 (August 2023)

CDOT Type R Curb Opening

02403656_PR_MHFD-Inlet_v5.03, HDR_IN-A3 12/16/2024, 12:49 PM

APPENDIX C

REFERENCE INFORMATION

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601 P Street / Suite 200 / Lincoln, NE 68508

O 402.474.6311 / olsson.com

To: City of Wheat Ridge From: Olsson, Laura Kindt, PE, CFM Date: March 4, 2025 Subject: Water Quality and Detention Design Approach for Wadsworth Path Project

The Wadsworth Path 32nd to 35th Avenue project is seeking guidance on the water quality and detention design approach. The project is located along Wadsworth from 32nd Avenue to 35th

Avenue (Figure 1). The project includes adding sidewalk along the west side of Wadsworth

Boulevard from 32nd to 35th Avenue, curb and gutters, roadway patching, relocating the existing

Rocky Mountain Water Company (RMWC) 6-foot by 3-foot box culvert, and relocating existing drainage structures. There is a high point along Wadsworth Boulevard located approximately at station 107+00. Drainage north of 107+00 drains to the north to the existing storm system located within Wadsworth and ultimately outfalls to Clear Creek via a water quality pond being constructed with the Improve Wadsworth project.