Project_15_-_Harlan_St_-_Drainage_Memo.pdf

CITY OF WHEAT RIDGE

PROJECT 15 -

HARLAN ST,

32ND AVE TO 35TH AVE

SIDEWALK GAP PROGRAM

Prepared for:

City of Wheat Ridge Colorado

Wheat Ridge, Colorado

Prepared by:

Olsson

1525 Raleigh Street, Suite 400

Denver, CO 80204

August 2026

Olsson Project No. B25-03001

Project 15 – Harlan St, 32nd Ave to 35th Ave Sidewalk Gap Program

City of Wheat Ridge Project No. 025-029B August 2026

B25-03001 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 and Street Capacity

5.2 Storm Drain

5.3 Detention/Water Quality

6. Variances

References

Appendix A Hydrology

Appendix B Hydraulics

Appendix C Reference Information

B25-03001 2

1. INTRODUCTION

Project 15 consists of sidewalk improvements along the east and west side of Harlan Street between 32nd and 35th Avenue as part of the City of Wheat Ridge Sidewalk Gaps Program. The project will include curb and gutter, sidewalks, driveways, roadway patching, portions of full-depth pavement reconstruction, and new storm infrastructure. The proposed storm infrastructure will replace and/or supplement existing infrastructure within the project area and discharge to the existing storm sewer system. No modifications to storm drainage infrastructure downstream of the project limits are proposed.

1.1 Project Location and Purpose

Project 15 will improve pedestrian connectivity along the east and west sides of Harlan Street by connecting discontinuous segments of existing sidewalk and closing sidewalk gaps between

32nd Avenue and 35th Avenue, creating a continuous pedestrian route along the corridor. The project is located within a residential area of the City of Wheat Ridge, Colorado. A vicinity map is provided in Figure 1.

Figure 1 - Site Vicinity Map

B25-03001 3

1.2 Description of Property

1.2.1 Ground Cover and Topography

The project area is fully developed. Existing ground cover consists primarily of private landscaping, including grass, rock, gravel, mulch, shrubs, and trees. Small, isolated areas of exposed soil are also present.

Existing drainage within the project area is divided by a roadway high point located approximately 175 feet south of 33rd Avenue. Along the east side of Harlan Street, drainage south of the high point is conveyed by curb and gutter to an existing inlet near 32nd Avenue, while drainage north of the high point is conveyed to an existing inlet at 35th Avenue.

Along the west side of Harlan Street, runoff is conveyed by a combination of curb and gutter and roadside swales. Runoff south of the high point generally drains to an existing inlet near 32nd

Avenue, while runoff north of the high point flows north before outfalling west along 33rd Avenue or 35th Avenue. However, in several locations the roadside swale is discontinuous, causing runoff to sheet flow onto adjacent properties.

1.2.2 Soils Description

The project area includes soils in Hydrologic Soil Group Type B and C which are characterized as having low to moderate infiltration rates and moderate to high runoff potentials. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service

(NRCS), the soils in the project area are comprised of 12.3 acres of Urban land-Ciancio-

Englewood complex, 0.7 acres of Urban land-Elyria-Ascalon complex. The full soils report is included in Appendix C.

1.2.3 Major Drainageways

There are no major drainageways within the project area. Stormwater originating south of the drainage high point is within the Sloan Lake Reach J North Tributary watershed and is presumed to ultimately discharge into Sloan's Lake. Stormwater originating north of the high point is presumed to flow northward and ultimately discharge to Clear Creek.

2. HYDROLOGY

2.1 Drainage Basin Map

Drainage basins were delineated using survey information, supplemented with 2020 LiDAR data outside of the project area. The Rational Method was used to complete hydrological calculations using the MHFD rational spreadsheet. A drainage map of the proposed conditions is included in

Appendix A.

B25-03001 4

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 southern portion of the project site eventually flows to Gray Street Tributary and ultimately is conveyed to Ashland Drainageway and Sloan’s Lake Drainageway. The northern portion of the project site eventually flows to Clear

Creek.

2.3 On-Site Description

Ten basins were delineated under proposed conditions. Full rational calculations are included in

Appendix A

15.01 - This basin delineates flow along the west side of N Harlan Street between W 35th

Avenue and the northern limit of the project. Flow is conveyed north along the street and continues along the existing roadway, leaving the project area.

15.02 - This basin is the smallest and delineates flow along the north side of W 35th Avenue between N Harlan Street and the western limit of the project. Flow is conveyed west along the street and continues along the existing roadway, leaving the project area.

15.03 - This basin delineates flow along the south side of W 35th Avenue between N Harlan

Street and the western limit of the project. Flow is conveyed west along the street and continues along the existing roadway, leaving the project area. Bypass flow from basin 15.05 combines with flow from basin 15.03.

15.04 - This basin delineates flow along the south side of W 35th Avenue between N Harlan

Street and the eastern limit of the project. Flow is conveyed east along the street and continues along the existing roadway, leaving the project area. Bypass flow from basin 15.08 combines with flow from basin 15.04.

15.05 - This basin delineates flow along the west side of N Harlan Street between W 33rd

Avenue and W 35th Avenue. Flow from this basin is conveyed north along the street to a Wheat

Ridge combination inlet located along N Harlan Street. Flow leaves the inlet via a storm pipe that connects to an existing storm system. Bypass flow from basin 15.05 will be conveyed to basin 15.03.

15.06 - This basin delineates flow along the north side of W 33rd Avenue between N Harlan

Street and the western limit of the project. Flow is conveyed west along the street and continues along the existing roadway, leaving the project area.

B25-03001 5

15.07 - This basin delineates flow along the south side of W 33rd Avenue between N Harlan

Street and the western limit of the project. Flow is conveyed west along the street and continues along the existing roadway, leaving the project area.

15.08 - This basin is the largest and delineates flow between the east side of N Harlan Street to the west side of Fenton Street between W 35th Avenue and halfway between W 32nd Avenue and W 33rd Avenue. Flow from this basin is conveyed north along the N Harlan Avenue to a triple Wheat Ridge combination inlet. Flow leaves the inlet via a storm pipe that connects to an existing storm system. Bypass flow from basin 15.08 will be conveyed to basin 15.04.

15.09 - This basin delineates flow along the west side of N Harlan Street between W 33rd

Avenue and W 32nd Avenue. Flow from this basin is conveyed south along the street to a Wheat

Ridge combination inlet located along N Harlan Street. Flow leaves the inlet via a storm pipe that connects to an existing storm system.

15.08 - This basin delineates flow along the east side of N Harlan Street between W 33rd

Avenue and W 32nd Avenue. Flow from this basin is conveyed south along the street to a Wheat

Ridge combination inlet located along N Harlan Street. Flow leaves the inlet via a storm pipe that connects to an existing storm system.

Table 1 - Peak Flow Summary

Basin 5-year Flows (cfs) 100-year Flows (cfs)

15.01 0.17 0.39

15.02 0.05 0.11

15.03 0.12 0.26

15.04 0.13 0.35

15.05 0.86 1.97

15.06 0.09 0.20

15.07 0.29 0.66

15.08 11.46 36.56

15.09 0.63 1.45

15.10 2.81 7.61

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 was determined in accordance with the MHFD guidance using the point precipitation frequency estimates from NOAA Atlas 14, Volume 8, Version 2 for Wheat

Ridge, Colorado at the project location. Precipitation data is included in Appendix A.

B25-03001 6

2.5 Design Flood Frequency

The Jefferson County criteria was referred to determine a minor and major flood frequency of 5-years and 100-years, respectively. MHFD Criteria and Jefferson County criteria were referenced to determine the allowable overtopping and street capacity for collector streets. The more stringent of the two criterion, MHFD criteria, was used. Figure 2 and Figure 3 show the MHFD street capacity criteria used for this project.

For this project, along Harlan Street the minor storm flow must leave at least one lane free of water and must not exceed 6-inches in depth as to not overtop the curb. The major storm flow may spread to the crown of the street and must not exceed 12-inches in depth. Along the side streets, the minor storm flow may spread to the crown of the street and must not exceed 6-inches in depth as to not overtop the curb. The major storm flow may spread to the crown of the street and must not exceed 12-inches in depth.

Figure 2 - MHFD Minor Storm Street Capacity Criteria

B25-03001 7

Figure 3 - MHFD Major Storm Street Capacity Criteria

3. EXISTING STRUCTURES

There is an existing inlet at the northwest corner of 32nd Avenue and Harlan Street, a slotted drain along the east side of Harlan Street just north of 32nd Avenue, and an existing inlet at the southeast corner of 35th Avenue and Harlan Street. The inlet and slotted drain near 32nd

Avenue are located south of the roadway high point, while the inlet at 35th Avenue is located north of the high point as discussed above.

4. DESIGN DISCUSSION

The proposed drainage does not change the existing drainage patterns and ties into the existing drainage infrastructure. Existing conditions were not evaluated, and it is assumed that the existing downstream infrastructure has capacity for the design flows.

This project does disturb more than one acre and therefore requires a stormwater management plan. This project is exempt from water quality treatment per Section 4.a.i.I. of the City’s MS4 permit. This project is exempt because bike and pedestrian trails are excluded.

B25-03001 8

5. RECOMMENDED DESIGN

5.1 Inlets and Street Capacity

The street inlets were analyzed to meet the spread criteria as discussed in Section 2.5.

Calculations were completed using the MHFD-Inlet, Version 6.00 spreadsheet and FlowMaster.

Full calculations are included in Appendix B.

An at-grade, Wheat Ridge combination inlet will be located at the northern point of basin 15.05.

The inlet will have capacity for the minor storm and 87% of the major storm. Bypass flow from this inlet will be conveyed to basin 15.03 and leave the site.

An at-grade, triple Wheat Ridge combination inlet will be located at the northern point of basin

15.08. The inlet will have capacity for 76% of the minor storm and 47% of the major storm.

Bypass flow from this inlet will be conveyed to basin 15.04 and leave the site. The southern portion of the street along basin 15.04 does not have capacity for the major storm event.

However, the flows will overtop the crown and be conveyed to the north side of the street. The north side of the street has more than enough capacity for the bypass flows to meet criteria.

Flow along the north side of the street would be directed towards an existing inlet located east of the project area along W 35th Avenue.

An at-grade, Wheat Ridge combination inlet will be located at the southern point of basin 15.09.

The inlet will have capacity for the minor storm and 96% of the major storm. Bypass flow from this inlet will be conveyed southwest and leave the site along 32nd Avenue.

An at-grade, Wheat Ridge combination inlet will be located at the southern point of basin 15.10.

The inlet will have capacity for 77% of the minor storm and 50% of the major storm. Bypass flow from this inlet will be conveyed southwest and leave the site along 32nd Avenue. An existing slotted drain inlet is located along N Harlan Street and captures existing flows from basin 15.10.

Under existing conditions, the slotted drain inlet has capacity for 100% of the minor storm and

93% of the major storm. This project will reduce the overall inlet capacity at basin 15.10 but the actual bypass flow is only 0.6 cfs and 3.8 cfs in the minor and major storms, respectively. To fully capture the flow under proposed conditions, either two, at-grade Wheat Ridge combination inlets would need to be installed with a connecting pipe or a quadruple Wheat Ridge combination inlet would need to be installed. Alternatively, 15 feet of slotted drain could be installed and tied into the proposed Wheat Ridge combination inlet to capture the bypass flows.

At this location, it would be uneconomical to install an inlet that captures 100% of the flow.

Wheat Ridge has expressed a preference to not include slotted drain in the design so that is not proposed. A capture efficiency is not listed in the criterion, but it is typical for an at-grade inlet to be required to capture 70% of the incoming minor storm flow. Since the criterion does not list a requirement for inlet capture efficiency, it was assumed that 70% capture efficiency would be

B25-03001 9 acceptable. Since the capture efficiency is greater than 70% and bypass flow is so insignificant, it was assumed to be acceptable. The proposed inlet meets criteria because a required inlet capture efficiency is not specified.

Within basins 15.05, 15.07, and 15.09, a maximum ponding depth of 2.5-inches was used for the minor storm to verify roadway capacity at reduced-height driveways. Under existing conditions, driveways within these basins slope towards the properties, therefore, to avoid increasing runoff onto the properties during the minor storm event, the driveways were designed to rise a maximum of 2.5 inches before sloping towards the properties. Within basin 15.05, a

FlowMaster calculation was completed to supplement the MHFD-Inlet spread calculations because the driveway rise at station 111+50 is only 2 inches. FlowMaster was used at this location because the geometry of the driveway is different that the geometry of a typical roadway with curb and gutter. Within basin 15.05 and upstream of station 110+10, the driveways have a maximum ponding depth of 2 inches. It was assumed that half of the total flow would be conveyed along these driveways because station 110+10 and upstream are within the upper half of basin 15.05. To verify roadway capacity at these driveways, a roadway capacity calculation was performed using half of the total basin flow with 2-inch maximum ponding depth.

Full calculations for the street capacity evaluation are included in Appendix B.

5.2 Storm Drain

It is assumed that the existing downstream storm drain has capacity for the flows captured by the proposed inlets. Analysis of the entire downstream storm system is not included in the scope of this project. To determine the proposed pipe size from the inlets at basins 15.05, 15.08, 15.09, and 15.10, calculations were performed using MHFD-Culvert spreadsheet and the downstream inlets were assumed to be empty meaning there is no tailwater depth. Full calculations for this evaluation are included in Appendix B.

To mitigate issues with ponding on the adjacent properties, chase drains are proposed at the two properties north of the northeast corner of N Harlan Street and W 34th Avenue and at the southeast corner of N Harlan Street and W 33rd Avenue. The intent of the chase drains is to mitigate nuisance flows coming from the properties; therefore, no additional calculations were performed for the chase drains.

5.3 Detention/Water Quality

This project is not required to provide detention. The increase in percent imperviousness compared to existing conditions is 1.7%, which will produce minimally increased runoff – maximums of 0.16 cfs and 0.20 cfs during the minor and major storms, respectively.

The project is exempt from water quality requirements.

B25-03001 10

6. VARIANCES

No variances from the criteria are requested with this project.

REFERENCES

Mile High Flood District. April 2025. MHFD-Culvert Workbook, Version 4.01.

Mile High Flood District. August 2025. MHFD-Inlet Workbook, Version 6.00.

Mile High Flood District. August 2025. MHFD-Rational Workbook, Version 3.00.

National Oceanic and Atmospheric Administration. 2026. NOAA Atlas 14, Volume 8, Version 2.

United States Department of Agriculture. 2026. Custom Soil Resource Report for

Golden Area, Colorado, Parts of Denver, Douglas, Jefferson, and Park Counties.

Urban Drainage and Flood Control District, Volume 1. March 2024. Urban Storm

Drainage Criteria Manual: Volume 1.

Urban Drainage and Flood Control District, Volume 2. January 2016. Urban Storm

Drainage Criteria Manual: Volume 2.

APPENDIX A

HYDROLOGY

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DATE:

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08.06.2026

1PROPOSED DRAINAGE MAP

EXHIBIT

A = BASIN DESCRIPTION

B = AREA (AC)

C = COMPOSITE RUNOFF COEFFICIENTS

(5-YR, 100-YR)

D = DESIGN POINT

FLOW PATH

CB

A

D

LEGEND

BASIN BOUNDARY

PROPOSED STORM

EXISTING MAJOR CONTOUR

(SURVEY)

EXISTING MINOR CONTOUR

(SURVEY)

EXISTING MAJOR CONTOUR

(LIDAR)

EXISTING MINOR CONTOUR

(LIDAR)

PROPOSED MAJOR CONTOURS

PROPOSED MINOR CONTOURS

CHANNELIZED FLOW

OVERLAND FLOW

XXXX

XXXX

XXXX

N HARLAN ST

150' 300'75'0'

SCALE IN FEET

0.810.06

15.01

0.870.810.02

15.02

0.87

0.810.03

15.06

0.87

0.810.10

15.07

0.87 0.810.04

15.03

0.87

0.610.06

15.04

0.77

0.4610.48

15.08

0.70

0.810.22

15.09

0.87

0.810.30

15.05

0.87

0.601.71

15.10

0.77

W

32TH

AVE

W

33TH

AVE

W

34TH

AVE

W

35TH

AVE

15.01

15.04

15.03

15.05

15.06 15.07

15.08

15.09

15.10

15.02

Designer:

Company:

Date:

Project:

Location:

Provide subcatchment names on the Rational Calcs worksheet to open up the table below.

Imperviousness

Source

Imperviousness

Category Calculated

Imperviousness

(Optional)

Override

Imperviousness

WQE

2-yr

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

WQE

2-yr

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

EX 15.01 2 0.06 C/D 82.5% 82.5% 0.68 0.71 0.74 0.78 0.80 0.82 0.85 0.68 0.71 0.74 0.78 0.80 0.82 0.85

0.05 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.01 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

EX 15.02 2 0.02 C/D 72.8% 72.8% 0.60 0.63 0.67 0.73 0.75 0.78 0.82 0.60 0.63 0.67 0.73 0.75 0.78 0.82

0.01 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.00 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

EX 15.03 2 0.04 C/D 76.3% 76.3% 0.62 0.66 0.69 0.75 0.77 0.80 0.83 0.62 0.66 0.69 0.75 0.77 0.80 0.83

0.03 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.01 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

EX 15.04 2 0.06 C/D 57.5% 57.5% 0.46 0.50 0.55 0.64 0.68 0.72 0.77 0.46 0.50 0.55 0.64 0.68 0.72 0.77

0.03 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.03 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

EX 15.05 2 0.30 C/D 80.0% 80.0% 0.66 0.69 0.72 0.77 0.79 0.81 0.84 0.66 0.69 0.72 0.77 0.79 0.81 0.84

0.24 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.06 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

EX 15.06 2 0.03 C/D 70.0% 70.0% 0.57 0.61 0.65 0.71 0.74 0.77 0.81 0.57 0.61 0.65 0.71 0.74 0.77 0.81

0.02 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.01 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

EX 15.07 2 0.10 C/D 93.4% 93.4% 0.77 0.80 0.82 0.84 0.85 0.87 0.88 0.77 0.80 0.82 0.84 0.85 0.87 0.88

0.10 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.00 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

EX 15.08 2 10.48 C/D 51.8% 51.8% 0.41 0.46 0.51 0.61 0.65 0.70 0.75 0.41 0.46 0.51 0.61 0.65 0.70 0.75

4.45 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

6.03 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

EX 15.09 2 0.22 C/D 78.0% 78.0% 0.64 0.67 0.70 0.76 0.78 0.80 0.83 0.64 0.67 0.70 0.76 0.78 0.80 0.83

0.17 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.05 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

EX 15.10 2 1.71 C/D 67.4% 67.4% 0.55 0.58 0.63 0.70 0.73 0.76 0.80 0.55 0.58 0.63 0.70 0.73 0.76 0.80

1.08 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.63 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

PR 15.01 1 0.06 C/D 95.0% 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.06 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

PR 15.02 1 0.02 C/D 95.0% 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.02 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

PR 15.03 1 0.04 C/D 95.0% 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.04 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

PR 15.04 2 0.06 C/D 70.0% 70.0% 0.57 0.61 0.65 0.71 0.74 0.77 0.81 0.57 0.61 0.65 0.71 0.74 0.77 0.81

0.04 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.02 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

PR 15.05 1 0.30 C/D 95.0% 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.30 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

PR 15.06 1 0.03 C/D 95.0% 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.03 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

PR 15.07 1 0.10 C/D 95.0% 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.10 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

PR 15.08 2 10.48 C/D 52.5% 52.5% 0.42 0.46 0.52 0.61 0.65 0.70 0.75 0.42 0.46 0.52 0.61 0.65 0.70 0.75

4.54 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

5.94 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

PR 15.09 1 0.22 C/D 95.0% 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.22 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

PR 15.10 2 1.71 C/D 69.1% 69.1% 0.56 0.60 0.64 0.71 0.73 0.77 0.81 0.56 0.60 0.64 0.71 0.73 0.77 0.81

1.12 C/D Surface Type Roadways and Paved Streets 95% 0.79 0.81 0.83 0.85 0.86 0.87 0.89

0.59 C/D Surface Type Disturbed Soil 20% 0.14 0.20 0.28 0.43 0.49 0.57 0.65

Determination of Runoff Coefficients for Rational Method MHFD-Rational, Version 3.00 (August 2025)

Sidewalk Gaps - Project 15 Cells of this color are for required user-input

Cells of this color are for optional override values

Subcatchment

Name

# of

Subareas

Area

(ac)

NRCS

Hydrologic

Soil Group

(Optional) Override Runoff Coefficient, C

Wheat Ridge

Runoff Coefficient, C

Madison Stewart

Olsson

8/5/2026

Percent Imperviousness

Project 15_MHFD-Rational v3.00.xlsm, Runoff Coeffs 8/5/2026, 21:16

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

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

Date: 1-hour rainfall depth, P1 (in) = 0.60 0.78 1.05 1.28 1.63 1.92 2.22 3.00

Project: a b c

Location: Rainfall Intensity Equation Coefficients = 28.50 10.00 0.786

Subcatchment

Name

Area

(ac)

NRCS

Hydrologic

Soil Group(s)

Imperviousness

WQE

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)

(Optional)

Override tc

(min)

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

EX 15.01 0.06 C/D 82.5% 0.68 0.71 0.74 0.78 0.80 0.82 0.85 28.47 5450.86 5449.30 0.055 2.16 82.65 5449.30 5445.93 0.041 20 4.04 0.34 2.50 12.31 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.08 0.11 0.15 0.19 0.26 0.31 0.37 0.52

EX 15.02 0.02 C/D 72.8% 0.60 0.63 0.67 0.73 0.75 0.78 0.82 18.18 5450.58 5449.68 0.049 2.14 21.98 5449.68 5449.61 0.003 20 1.13 0.32 2.47 13.95 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.02 0.03 0.04 0.05 0.07 0.08 0.10 0.14

EX 15.03 0.04 C/D 76.3% 0.62 0.66 0.69 0.75 0.77 0.80 0.83 17.66 5451.09 5450.39 0.040 2.14 24.19 5450.39 5450.19 0.008 20 1.82 0.22 2.36 13.26 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.05 0.07 0.09 0.12 0.16 0.20 0.24 0.34

EX 15.04 0.06 C/D 57.5% 0.46 0.50 0.55 0.64 0.68 0.72 0.77 24.99 0.040 3.41 25.72 5450.12 5449.97 0.006 20 1.53 0.28 3.69 16.55 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.06 0.07 0.11 0.14 0.21 0.26 0.32 0.47

EX 15.05 0.30 C/D 80.0% 0.66 0.69 0.72 0.77 0.79 0.81 0.84 21.91 5465.23 5464.67 0.026 2.56 577.52 5464.67 5451.19 0.023 20 3.06 3.15 5.71 15.52 5.71 1.96 2.53 3.43 4.19 5.33 6.28 7.26 9.81 0.39 0.50 0.71 0.90 1.23 1.48 1.77 2.47

EX 15.06 0.03 C/D 70.0% 0.57 0.61 0.65 0.71 0.74 0.77 0.81 26.73 5465.39 5464.54 0.032 3.15 33.92 5464.54 5463.54 0.029 20 3.43 0.16 3.32 14.28 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.03 0.04 0.06 0.08 0.12 0.14 0.17 0.25

EX 15.07 0.10 C/D 93.4% 0.77 0.80 0.82 0.84 0.85 0.87 0.88 20.92 5466.09 5465.35 0.035 1.65 195.09 5465.35 5463.62 0.009 20 1.88 1.73 3.38 11.68 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.16 0.21 0.29 0.36 0.48 0.57 0.67 0.92

EX 15.08 10.48 C/D 51.8% 0.41 0.46 0.51 0.61 0.65 0.70 0.75 78.67 0.040 6.51 1519.32 5482.00 5450.81 0.021 20 2.87 8.84 15.35 28.06 15.35 1.35 1.74 2.36 2.87 3.66 4.31 4.99 6.74 5.83 7.54 11.31 15.46 23.38 29.33 36.37 53.05

EX 15.09 0.22 C/D 78.0% 0.64 0.67 0.70 0.76 0.78 0.80 0.83 21.29 5466.09 5465.22 0.041 2.25 423.34 5465.22 5455.43 0.023 20 3.04 2.32 4.57 15.08 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.29 0.37 0.53 0.67 0.92 1.11 1.33 1.87

EX 15.10 1.71 C/D 67.4% 0.55 0.58 0.63 0.70 0.73 0.76 0.80 271.76 5474.00 5463.69 0.038 9.89 263.89 5463.69 5455.89 0.030 20 3.44 1.28 11.17 15.94 11.17 1.55 2.01 2.72 3.31 4.22 4.97 5.74 7.76 1.45 1.88 2.71 3.55 5.02 6.17 7.46 10.62

PR 15.01 0.06 C/D 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 28.47 5450.86 5449.30 0.055 1.60 82.65 5449.30 5445.93 0.041 20 4.04 0.34 1.94 10.16 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.10 0.12 0.17 0.22 0.28 0.34 0.39 0.54

PR 15.02 0.02 C/D 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 18.18 5450.58 5449.68 0.049 1.32 21.98 5449.68 5449.61 0.003 20 1.13 0.32 1.65 10.14 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.03 0.03 0.05 0.06 0.08 0.09 0.11 0.15

PR 15.03 0.04 C/D 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 17.66 5451.09 5450.39 0.040 1.40 24.19 5450.39 5450.19 0.008 20 1.82 0.22 1.62 10.05 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.06 0.08 0.12 0.14 0.19 0.22 0.26 0.36

PR 15.04 0.06 C/D 70.0% 0.57 0.61 0.65 0.71 0.74 0.77 0.81 24.99 0.040 2.82 25.72 5450.12 5449.97 0.006 20 1.53 0.28 3.11 14.40 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.07 0.09 0.13 0.17 0.24 0.29 0.35 0.49

PR 15.05 0.30 C/D 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 21.91 5465.23 5464.67 0.026 1.80 577.52 5464.67 5451.19 0.023 20 3.06 3.15 4.95 12.68 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.48 0.62 0.86 1.08 1.41 1.68 1.97 2.71

PR 15.06 0.03 C/D 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 26.73 5465.39 5464.54 0.032 1.85 33.92 5464.54 5463.54 0.029 20 3.43 0.16 2.02 10.00 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.05 0.06 0.09 0.11 0.14 0.17 0.20 0.27

PR 15.07 0.10 C/D 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 20.92 5466.09 5465.35 0.035 1.58 195.09 5465.35 5463.62 0.009 20 1.88 1.73 3.31 11.40 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.16 0.21 0.29 0.36 0.47 0.56 0.66 0.90

PR 15.08 10.48 C/D 52.5% 0.42 0.46 0.52 0.61 0.65 0.70 0.75 78.67 0.040 6.46 1519.32 5482.00 5450.81 0.021 20 2.87 8.84 15.29 27.89 15.29 1.35 1.74 2.36 2.88 3.67 4.32 4.99 6.75 5.92 7.65 11.46 15.62 23.55 29.52 36.56 53.28

PR 15.09 0.22 C/D 95.0% 0.79 0.81 0.83 0.85 0.86 0.87 0.89 21.29 5466.09 5465.22 0.041 1.52 423.34 5465.22 5455.43 0.023 20 3.04 2.32 3.84 11.93 5.00 2.04 2.63 3.56 4.34 5.53 6.51 7.53 10.18 0.35 0.46 0.63 0.79 1.04 1.24 1.45 1.99

PR 15.10 1.71 C/D 69.1% 0.56 0.60 0.64 0.71 0.73 0.77 0.81 271.76 5474.00 5463.69 0.038 9.62 263.89 5463.69 5455.89 0.030 20 3.44 1.28 10.90 15.62 10.90 1.57 2.03 2.74 3.35 4.26 5.02 5.80 7.84 1.51 1.95 2.81 3.66 5.14 6.30 7.61 10.80

Calculation of Peak Runoff using Rational Method Madison Stewart

Olsson

Runoff Coefficient, C

MHFD-Rational, Version 3.00 (August 2025)

8/5/2026

Sidewalk Gaps - Project 15

Wheat Ridge

Provide input for area, soil type, and imperviousness on the Runoff Coeffs worksheet.

Cells of this color are for required user-input

Cells of this color are for optional override values

Calculation of Peak Runoff using Rational MethodCalculation of Peak Runoff using Rational Method

Rainfall Intensity, I (in/hr) Peak Flow, Q (cfs)Overland (Initial) Flow Time Channelized (Travel) Flow Time Time of Concentration

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APPENDIX B

HYDRAULICS

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

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.01

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 6.0 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 = 13.0 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.030 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 = 0.041 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.013

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 8.0 13.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 12.0 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 Spread Criterion Qallow = 8.1 25.9 cfs

Minor storm max. allowable capacity GOOD - greater than the design peak flow of 0.17 cfs on sheet 'Inlet Management'

Major storm max. allowable capacity GOOD - greater than the design peak flow of 0.39 cfs on sheet 'Inlet Management'

MHFD-Inlet, Version 6.00 (August 2025)

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.02

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 6.0 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 = 13.0 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.050 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 = 0.003 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.013

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 13.0 13.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 12.0 inches

Allow Flow Depth at Street Crown (check box for yes, leave blank for no)

MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm

MAJOR STORM Allowable Capacity is based on Spread Criterion Qallow = 5.5 17.5 cfs

Minor storm max. allowable capacity GOOD - greater than the design peak flow of 0.05 cfs on sheet 'Inlet Management'

Major storm max. allowable capacity GOOD - greater than the design peak flow of 0.11 cfs on sheet 'Inlet Management'

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.03

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 6.0 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 = 13.0 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.005 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 = 0.008 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.013

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 13.0 13.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 12.0 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 Spread Criterion Qallow = 1.1 1.1 cfs

Minor storm max. allowable capacity GOOD - greater than the design peak flow of 0.12 cfs on sheet 'Inlet Management'

Major storm max. allowable capacity GOOD - greater than the design peak flow of 0.52 cfs on sheet 'Inlet Management'

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.04 North

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 6.0 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 = 17.5 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.045 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 = 0.013

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 13.0 17.5 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 12.0 inches

Allow Flow Depth at Street Crown (check box for yes, leave blank for no)

MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm

MAJOR STORM Allowable Capacity is based on Spread Criterion Qallow = 6.7 39.3 cfs

Minor storm max. allowable capacity GOOD - greater than the design peak flow of 2.87 cfs on sheet 'Inlet Management'

Major storm max. allowable capacity GOOD - greater than the design peak flow of 19.78 cfs on sheet 'Inlet Management'

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.04 South

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 6.0 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 = 13.0 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 = 0.006 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.013

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 13.0 13.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 12.0 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 Spread Criterion Qallow = 5.4 5.4 cfs

Minor storm max. allowable capacity GOOD - greater than the design peak flow of 2.87 cfs on sheet 'Inlet Management'

WARNING: MAJOR STORM max. allowable capacity is less than the design peak flow of 19.78 cfs on sheet 'Inlet Management'

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.05

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 7.0 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 = 13.0 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.030 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 = 0.023 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.013

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 8.0 13.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 2.5 12.0 inches

Allow Flow Depth at Street Crown (check box for yes, leave blank for no)

MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm

MAJOR STORM Allowable Capacity is based on Spread Criterion Qallow = 1.2 19.4 cfs

Minor storm max. allowable capacity GOOD - greater 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 1.97 cfs on sheet 'Inlet Management'

INLET ON A CONTINUOUS GRADE

Design Information (Input) MINOR MAJOR

Type of Inlet Type = Wheat Ridge Combination

Local Depression (additional to continuous gutter depression 'a') aLOCAL = 2.0 2.0 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 = 2.75 2.75 ft

Width of a Unit Grate (cannot be greater than W, Gutter Width) Wo = 1.37 1.37 ft

Clogging Factor for a Single Unit Grate (typical min. value = 0.5) Cf (G) = 0.50 0.50

Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1) Cf (C) = 0.10 0.10

Street Hydraulics: OK - Q < Allowable Street Capacity' MINOR MAJOR

Total Inlet Interception Capacity Qa = 0.9 1.7 cfs

Total Inlet Carry-Over Flow (flow bypassing inlet) Qb = 0.0 0.3 cfs

Capture Percentage = Qa/Qo C% = 100 87 %

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.05 Roadway Half Flow

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 7.0 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 = 13.0 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.030 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 = 0.023 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.013

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 8.0 13.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 2.0 12.0 inches

Allow Flow Depth at Street Crown (check box for yes, leave blank for no)

MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm

MAJOR STORM Allowable Capacity is based on Spread Criterion Qallow = 0.7 19.4 cfs

Minor storm max. allowable capacity GOOD - greater than the design peak flow of 0.43 cfs on sheet 'Inlet Management'

Major storm max. allowable capacity GOOD - greater than the design peak flow of 0.99 cfs on sheet 'Inlet Management'

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.06

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 6.0 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 = 13.0 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.035 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 = 0.029 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.013

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 13.0 13.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 12.0 inches

Allow Flow Depth at Street Crown (check box for yes, leave blank for no)

MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm

MAJOR STORM Allowable Capacity is based on Spread Criterion Qallow = 15.6 27.7 cfs

Minor storm max. allowable capacity GOOD - greater than the design peak flow of 0.09 cfs on sheet 'Inlet Management'

Major storm max. allowable capacity GOOD - greater than the design peak flow of 0.20 cfs on sheet 'Inlet Management'

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.07

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 6.0 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 = 13.0 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.050 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 = 0.009 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.013

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 8.0 13.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 2.5 12.0 inches

Allow Flow Depth at Street Crown (check box for yes, leave blank for no)

MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm

MAJOR STORM Allowable Capacity is based on Spread Criterion Qallow = 0.8 30.3 cfs

Minor storm max. allowable capacity GOOD - greater than the design peak flow of 0.29 cfs on sheet 'Inlet Management'

Major storm max. allowable capacity GOOD - greater than the design peak flow of 0.66 cfs on sheet 'Inlet Management'

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.08

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 6.0 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 = 13.0 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.050 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 = 0.021 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.013

Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 8.0 13.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 12.0 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 Spread Criterion Qallow = 11.8 46.3 cfs

Minor storm max. allowable capacity GOOD - greater than the design peak flow of 11.46 cfs on sheet 'Inlet Management'

Major storm max. allowable capacity GOOD - greater than the design peak flow of 36.56 cfs on sheet 'Inlet Management'

Local Depression (additional to continuous gutter depression 'a') aLOCAL = 2.0 2.0 inches

Total Number of Units in the Inlet (Grate or Curb Opening) No = 3 3

Length of a Single Unit Inlet (Grate or Curb Opening) Lo = 2.75 2.75 ft

Width of a Unit Grate (cannot be greater than W, Gutter Width) Wo = 1.37 1.37 ft

Clogging Factor for a Single Unit Grate (typical min. value = 0.5) Cf (G) = 0.50 0.50

Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1) Cf (C) = 0.10 0.10

Street Hydraulics: OK - Q < Allowable Street Capacity' MINOR MAJOR

Total Inlet Interception Capacity Qa = 8.7 17.1 cfs

Total Inlet Carry-Over Flow (flow bypassing inlet) Qb = 2.7 19.4 cfs

Capture Percentage = Qa/Qo C% = 76 47 %

Project: Sidewalk Gaps - Project 15

Inlet ID: 15.09

Gutter Geometry:

Maximum Allowable Width for Spread Behind Curb TBACK = 9.0 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…