East_Park_GW_Underpass_&_Drainage_at_UPRR_9-16-2022.pdf

East Park Greenway Underpass

& Dra inage P lan a t the Un ion

Pac i f i c Ra i lroad

September 2022

East Park G reenway Underpass & Drainage Plan at the Union Paci f ic Ra i l road

Disc la imer Not ice

The preparat ion of this report has been f inances in part through grant(s) from the Federal High-way Administrat ion and Federal Transit Administrat ion, U.S. Department of Transportat ion, un-der the State P lanning and Research Program, Sect ion 505 [of Metropol itan P lanning Program, Sect ion 104(f) ] of T it le 23, U.S. Code. The contents of this report do not necessar i ly ref lect the off ic ia l v iews or pol icy of the U.S. Department of Transportat ion.

Partners

Cheyenne Metropol i tan

Planning Organizat ion

2101 O ’Nei l Avenue

Cheyenne, WY

City of Cheyenne

2101 O ’Neil Avenue

Cheyenne, WY

Summit Engineer ing

5907 Townsend P lace

Cheyenne, WY

GLM Design Group

P.O. Box 20505

Cheyenne, WY

Lithos Engineer ing

5205 S. Col lege Ave. Ste. B

Fort Col l ins , CO

Martin -Martin, Wyoming

4020 Laramie St .

Cheyenne, WY

360 Rai l Services

7800 E. Dorado P lace, Ste. 280

Englewood, CO 80111 i

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 1

Contents

Contents

Executive Summary

Purpose

Considerations

Explored Alternatives

Conclusion

Next Steps

East Park Greenway Underpass & Drainage Plan at the UPRR

Introduction

History

Purpose

Drainage Study of UPRR Dry Creek Crossing

Overview

Alternative 1

Alternative 2

Selected Alternative

Greater Cheyenne Greenway

Greenway Planning

Pedestrian Underpass of the UPRR Tracks

Kiwanis Park Greenway

Cheyenne Business Parkway Greenway

Next Steps

UPRR Approval

Utility Investigation

Projected Costs

Appendices

A GLM Design Group: Final Lower Dry Creek Study (HEC‐1 Sump 130) for Union Pacific RR Dry Creek Crossing with Appendices

B Lithos Engineering: Tunnel Feasibility Memorandum

C 360 Rail Services: Pedestrian Underpass Requirements / Feasibility

D Martin/Martin: Masonry Culvert Investigation and Assessment Report

E Summit Engineering: East Park Greenway 35% Design Plan and Profiles

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 2

Executive Summary

Purpose

The City of Cheyenne continues to expand eastward. As the City expands so should the recreational amenities. The City purchased the East Park land in 2020 with sixth-penny sales tax funds approved by Laramie County voters. In July of 2022 the park was renamed Kiwanis Park. The purpose of this study is two-fold:

• Identify a route for the Greater Cheyenne Greenway through Kiwanis Park and across the Union Pacific Railroad (UPRR) to join with the planned LEADS Trail along Campstool Road.

• Explore the potential for reducing the buildup of stormwater along the north side of the Union Pacific Railroad Embankment and improve flood mitigation for surrounding properties.

The Kiwanis Park land plays a significant role in the Lower Dry Creek Drainage Basin as it serves as a detention storage area. Runoff is detained until it is able to pass through the Union Pacific Railroad Embankment via a masonry arch structure constructed for this purpose in 1903. The figure below shows the extent of the FEMA floodplain and floodway in this area.

Figure 1: FEMA Floodway and Floodplain at Kiwanis Park

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 3

Considerations

Providing a route for the Greenway across the UPRR tracks requires either a pedestrian overpass or a pedestrian underpass. If the sole purpose of this project was to provide a Greenway crossing then both an overpass option and an underpass option would be equally considered. However, the purpose of this study is to also identify ways to reduce the floodway footprint and reduce the buildup of stormwater along the UPRR embankment. Impoundment of storm water against this embankment, which was neither designed nor constructed with such impoundment in mind, is a safety concern should the embankment fail during a significant storm event.

Additionally, this land holds a significant interest to history and railroad enthusiasts as the original transcontinental rail bed was constructed here in the 1870’s as part of the Pacific Railroad Acts of 1862.

Remnants of this original embankment are located inside Kiwanis Park.

Explored Alternatives

The alternatives explored were predicated on two main factors:

• Incorporating the existing remnants of the transcontinental rail bed into a berm to serve as the downstream side of the detention pond to keep stormwater impoundment off of the UPRR embankment.

• Utilizing the existing masonry arch structure, constructed in 1903, as a pedestrian underpass for the Greenway, thereby allowing public access to this historically significant structure. Utilizing this structure for pedestrians requires that new culverts be installed through the UPRR embankment for use as drainage conveyance. The UPRR requires that any culvert / structure that passes under their tracks be hydraulically isolated from inundation of storm water during a 100-year frequency storm event if it will be used as a pedestrian underpass.

The first alternative kept the footprint of the proposed berm smaller, both within the Kiwanis Park land and including only a small portion within private property to the east. The private property which would be impacted is located within the FEMA floodplain and acts as a retention pond currently. This alternative did not provide enough stormwater storage area upstream of the UPRR tracks. It would require significantly more storm water to pass through the embankment to keep the limits of the floodplain upstream of Kiwanis Park to existing conditions. Passing the additional stormwater through the embankment would require that this flow be

Figure 2: 1903 Structure constructed for Drainage Conveyance

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 4 mitigated by improvements made to the land and culverts downstream, including within the Laramie County Conservation District Managed LEADS property; under Campstool Road; through the Cheyenne Business Parkway, 8th Filing, Lot 2, Block 1; under Interstate 80; and potentially further downstream.

The second, preferred, alternative will expand the berm into the adjacent two private properties to increase the Lower Dry Creek detention storage volume over that which was available in the first alternative. The City of Cheyenne is currently pursuing the purchase of these two properties.

Conclusion

The Hydraulics and Hydrology study done by GLM Group concludes that construction of a berm within both Kiwanis Park and the adjacent properties, installation of drainage culverts through the UPRR embankment, and construction of a second berm and additional culvert to address stormwater coming to the site from east of Whitney Road, will hydraulically isolate the masonry arch structure such that it can be used as a pedestrian underpass. This design meets the project goals of removing the buildup of storm water against the UPRR embankment that comes from the Lower Dry Creek Basin north of East Pershing Boulevard. Additionally, the footprint of the floodplain, east of Whitney Road may be reduced following construction of the proposed improvements and the filing of a Letter of Map Revision with

FEMA

A Greenway has been conceptually designed around East Park to connect to the existing Greenway around Saddle Ridge Subdivision at the northeast corner of the intersection of East Pershing Boulevard and Whitney Road, as well as to the proposed Greenway envisioned to enter Kiwanis Park in the southwest corner as part of the Sun Valley Connector Greenway project. The Greenway will utilize the masonry arch structure and continue through the Laramie County Conservation District Managed Cheyenne LEADS land to connect to the planned LEADS Trail along Campstool Road.

Next Steps

The implementation of this proposed design depends on the acceptance by the UPRR as it not only requires construction to take place within their right of way to construct the berm and to bore the proposed culverts through their embankment, but also to utilize the masonry arch structure as a pedestrian underpass. To move forward the City of Cheyenne must enter into a Preliminary Engineering (PE) Agreement with the UPRR. The PE Agreement will allow conceptual level plans, drainage report, geotechnical report, and culvert boring plans to be reviewed by UPRR or their subcontracted reviewers.

A retainer must accompany the PE Agreement. The cost of the retainer will be determined by the UPRR Manager of Public Projects based on the scope of work. This particular project had a suggested retainer of $25,000 in 2021. The UPRR will bill the City of Cheyenne for actual review costs, which could be in excess of the retainer. Following acceptance of the conceptual plans the City of Cheyenne can proceed with final design plans, again to be reviewed by the UPRR, and ultimately construction if the plans are approved.

We believe this conceptual plan is a win-win for both the City of Cheyenne and the Union Pacific Railroad. Impoundment of stormwater on the UPRR embankment has reaches depths of 19 feet on multiple occasions in the past. A breach of the embankment in a large flood event would be catastrophic for downstream properties and the travelling public including traffic on Interstate 80, as well as catastrophic for the UPRR who relies on these mainline tracks for all railroad commerce into and out of Cheyenne to the east.

E. PERSHING BLVD.

W H

IT

N

EY

R

D

PREFERRED ALTERNATIVE

LEGEND

PROPOSED GRAVEL PATH

UNION PACIFIC RIGHT-OF-W

AY

PROPOSED GREENWAY TRAIL

EXISTING SANITARY SEWER

PROPOSED CULVERT

EXISTING COMMUNICATION LINE

EXISTING PETROLEUM LINE

KIWANIS PARK

CHEYENNE

LEADS: LCCD

MANAGED LAND

PLAINS PIPELINE BLOCK VALVE

E. PERSHING/WHITNEY INTERSECTION

SHOWN PER Y2'S RECOMMENDATION IN

THE E. PERSHING BLVD. CORRIDOR STUDY.

300' SPILLWAY

3 4

KEY NOTES

1. KIWANIS PARK BERM. TOP ELEV. 5941,

(EXCEPT AT SPILLWAY)

2. EAST BASIN BERM. TOP ELEV. 5937.5 MIN.

3. SPILLWAY: 300' LONG, CREST ELEV.

5939.6'

4. SPILLWAY OVERFLOW OUTLET

STRUCTURE. RIM ELEV. 5939.6', 3 x 60"

DIA. OUTLET PIPES

5. WEST BASIN OUTLET, 1 x 36" DIA. PIPE

6. KIWANIS PARK OUTLET, 2 x 60" DIA. + 1 x

42" DIA. PIPES

7. EXISTING MASONRY ARCH STRUCTURE

TO BE USED AS PEDESTRIAN

UNDERPASS

8. EAST BASIN OUTLET, 2 x 60" DIA. PIPES

9. EAST BASIN DITCH OUTLET, 1 x 30" DIA.

PIPE WITH FLAP GATE

10. EAST BASIN DITCH, WILL REQUIRE

DRAINAGE EASEMENT

EAST BASIN

WEST BASIN

PARK BOUNDARY

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 6

East Park Greenway Underpass & Drainage Plan at the UPRR

Introduction

The City of Cheyenne continues to expand eastward. As the City expands so should recreational amenities, including City park facilities and the Greater Cheyenne Greenway. With that vision the City purchased the East Park land in 2020 with sixth-penny sales tax funds approved by Laramie County voters. In 2021, after some safety improvements were made, the park was opened to the public. The City of Cheyenne retained Russell + Mills to complete the East Cheyenne Community Park Master Plan in 2022. The Master Plan was done with consideration given to the drainage needs within East Park that were identified with this Drainage Plan. In July of 2022 the park was renamed Kiwanis Park when the Kiwanis Club pledged a financial contribution to the park as well as ongoing support and maintenance for the park.

In addition to being public open space, the Kiwanis Park land plays a significant role in the Lower Dry Creek Drainage Basin as it serves as a detention storage area. Runoff is detained until it is able to pass through the Union Pacific Railroad (UPRR) Embankment via a masonry arch structure constructed for this purpose in 1903. The City of Cheyenne has been proactive with its regulatory stance within the Dry Creek Basin by limiting stormwater discharge to the 20-year existing peak flow. However, even with this restriction in place, stormwater is impounded against the UPRR embankment during large storm events, with the impoundment measuring 19 feet deep on multiple occasions. When this embankment was constructed in the early 1900’s it is very likely that it was not constructed with such impoundments in mind. A breach of the embankment in a large flood event would be catastrophic for downstream properties and the travelling public including traffic on Interstate 80 where multiple culverts exist to convey Dry Creek flows under the Interstate. Additionally, this would be catastrophic for the UPRR who relies on these mainline tracks for all railroad commerce into and out of the east side of Cheyenne.

History

The history of the project area begins with the passage of the Pacific Railroads Acts of 1862 that promoted the construction of the “transcontinental railroad” across the United States. Portions of the original transcontinental railbed, originally constructed in the 1870’s still exist and are partially located within Kiwanis Park. Figure 3, on the following page, outlines the transcontinental railbed in aqua. The existing mainline tracks were constructed shortly after 1901 with the construction of the 6’ x 8’ masonry box arch culvert being completed in 1903. This arch culvert is depicted as a red line in Figure 3. As previously mentioned, its purpose is to convey storm water through the embankment. Previously a railroad trestle over Dry Creek was utilized by the transcontinental railroad.

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 7

Purpose

The purpose of this study is two-fold:

• Identify a route for the Greater Cheyenne Greenway through Kiwanis Park and across the Union Pacific Railroad (UPRR) to join with the planned Cheyenne LEADS Trail along Campstool Road.

o Connect the proposed Greenway through Kiwanis Park to the proposed Sun Valley Connector Greenway that will enter the park property in the southwest corner.

• Explore the potential for reducing the buildup of stormwater along the north side of the Union Pacific Railroad Embankment and improve flood mitigation for surrounding properties.

Drainage Study of UPRR Dry Creek Crossing

Overview

GLM Design Group completed the drainage study for the Union Pacific Railroad crossing of Lower Dry Creek. The complete report is included as Appendix A. A summary of this report is included herein: This plan evaluated two alternatives for improvements that will remove the impoundment of storm water

Figure 3: Vicinity Map

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 8 against the UPRR embankment by creating a bermed detention facility to detain the stormwater inside Kiwanis Park. A hydraulic analysis was done on both alternatives. In both alternatives the existing masonry arch structure was hydraulically isolated such that it could be used as a pedestrian underpass, and the north portion of Kiwanis Park was kept out of the floodplain to allow structures and park amenities to be planned in that portion of the park.

Both alternatives utilize the existing transcontinental railbed berm as the location of the new storm water detention berm. Utilizing this berm embraces the historic significance of this location. Train enthusiasts are drawn to Cheyenne because of the rich railroad history. Preserving this transcontinental railbed and incorporating it into a project that makes it publicly accessible is a great opportunity. The berm will include a gravel pathway accessible via the Greenway that will be incorporated into Kiwanis Park. From this vantage point, atop the transcontinental railbed berm, pathway users will be at the same elevation as the existing UPRR mainline tracks, but separated by a valley to the south.

Figure 4: View atop Existing Transcontinental Railbed

Alternative 1

The first alternative has a berm with a smaller footprint whereas the berm is located mainly within Kiwanis Park property and extending into the adjacent private property only within the limits of the existing low-lying ground that is almost always inundated with standing water. Figure 5 shows the extents of the berm as the magenta line; Greenway and trails are shown as orange lines; proposed culverts through the UPRR embankment are shown as red lines, the existing masonry arch structure is a dashed blue line, and a portion of the Kiwanis Park improvement area that will be outside of the floodplain is shown shaded green.

The location of the berm in this alternative restricted the amount of area available for storm water detention, and necessitated too much of an increase in flow through the culverts to Dry Creek on the south side of the UPRR embankment. This alternative causes too much water to enter the downstream system too quickly and would require extensive improvements to the downstream Dry Creek reach from the UPRR embankment to the Interstate 80 crossing and further downstream. With this alternative it isn’t feasible to simply raise the height of the berm to detain more storm water as that would cause a rise in the flood elevation on the property(ies) upstream of Kiwanis Park. For these reasons, Alternative 1 was not considered further.

Figure 5: Alternative 1

Alternative 2

The second alternative increased the footprint of the berm by extending it almost entirely into the adjacent private properties. Both of these properties, show in Figure 6, were owned by the Mary Winkler estate. The City of Cheyenne has obtained an appraisal and is actively negotiating the purchase of these properties.

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 10

Figure 6: Privately Owned Parcels

Figure 7 shows the extents of the berm in Alternative 2 as the magenta line; Greenway and trails are shown as blue lines; culverts through the UPRR embankment are shown as red lines, and a portion of the Kiwanis Park improvement area that will be outside of the floodplain is shown shaded green.

The location of this berm increased the amount of storm water detention available and decreased the flow out of the culverts through the UPRR embankment to a manageable level. Some downstream improvements will still be required to mitigate the additional storm water flow coming through the UPRR embankment. For this reason, Alternative 2 was pursued with this plan.

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 11

Figure 7: Alternative 2

Selected Alternative

Alternative 2 was selected because it provides a large amount of stormwater detention, it does not increase the base flood water surface elevation on upstream properties, it allows for the masonry arch structure to be hydraulically isolated for use as a pedestrian underpass, and it narrows the extents of the floodplain on adjacent properties east of Whitney Road.

The berm to be constructed will create a detention facility. This berm is an earthfill dam to be constructed using fill material that is generated from excavated on-site material as well as import structural fill. Construction of the berm will need to be monitored to ensure that it is constructed in shallow lifts of 12 inches or less, moisture conditioned, and compacted to the specifications established by a geotechnical engineer.

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 12

Two 60” diameter culverts and one 42” diameter culvert are required to be bored through the UPRR embankment to convey stormwater from Kiwanis Park to Dry Creek on the south side of the UPRR embankment. Boring large diameter pipe through a railroad embankment requires approval by the railroad, a thorough engineering evaluation of the site, and strict adherence to American Railway Engineering and Maintenance-of-Way Association (AREMA) guidelines. Lithos Engineering completed a Tunnel Feasibility Memorandum for this site. The memorandum is included as Appendix B.

The height of the proposed culverts was limited to 60”. The UPRR requires continuous track monitoring during any culvert boring operation. The monitoring is done to ensure that the tracks do not settle more than ¼”. In this location there are two mainline UPRR tracks, which provide the only access to the UPRR yard from the east. Any settlement of the track or other failure during the culvert boring process would be extremely costly. The potential for settlement is reduced by increasing the distance between the top of the boring pipe and the bottom of the tracks. A suggested rule of thumb is to allow for four x the diameter of the pipe between the bottom of the track ballast and the crown of the pipe. For this reason, we have limited the pipe culverts used to a 60” diameter.

Existing conditions have stormwater directed to the masonry arch structure from not only Dry Creek, but also land to the east and west of Kiwanis Park. With the construction of a berm within Kiwanis Park stormwater from the east and west will flow toward the UPRR embankment without being detained by the proposed berm.

On the west side of the Kiwanis Park berm a detention pond will be formed between the existing UPRR embankment and the proposed berm. Storm water coming from this west basin will need to be conveyed through the UPRR embankment. A 30” diameter culvert is proposed for this purpose.

On the east side of Kiwanis Park a secondary, smaller, berm is included in the design to keep stormwater runoff from flowing onto the Greenway path from the north, east of Whitney Road. Because the masonry arch structure will need to be hydraulically isolated to be used as a pedestrian facility, it cannot be used to convey this runoff through the UPRR embankment during a 100-year frequency event. This second berm will create a smaller detention pond on the east side of the masonry arch structure. Two – 60” diameter borings are required to convey storm water from the east basin through the UPRR embankment.

As described in the drainage study completed by GLM Design Group, and included as Appendix A, a spillway is also required. The spillway design must accommodate conveyance of stormwater should the culvert outlets fail or if a storm with a frequency greater than 100-year should occur.

Greater Cheyenne Greenway

Greenway Planning

The Greater Cheyenne Greenway is a recreational amenity constructed by the City of Cheyenne and developers as a 10 foot wide concrete path. The purpose is to provide a pedestrian and bicycle corridor, separated from traffic whenever feasible, to connect neighborhoods and schools around the entirety of the Greater Cheyenne area. The Cheyenne On-Street Bicycle Plan and Greenway Plan Update, June 2012, shows a Greenway connection at Whitney Road, East Pershing Boulevard and the Sun Valley

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 13

Connector to Kiwanis Park, as well as a Greenway connection across the UPRR between Kiwanis Park and Campstool Road.

Pedestrian Underpass of the UPRR Tracks

The City of Cheyenne will need to enter into a Professional Engineering (PE) Agreement with the UPRR to evaluate the project and to have approval to utilize the existing masonry arch structure as a pedestrian underpass. The UPRR and BNSF Railway have developed a Guildelines for Railroad Grade Separation Projects which provides requirements for both overpass and underpass structures for both vehicular and pedestrian use. These guidelines can be found online at https://www.bnsf.com/bnsf-resources/pdf/in-the-community/uprr-bnsf-joint-guidelines-railroad-grade-separation-projects.pdf

The UPRR requires several items to be incorporated into the design of a pedestrian underpass structure, including lighting, fencing to keep trail users off of the tracks, and signage.

360 Rail Services has summarized these requirements in the included document Pedestrian Underpass Requirements/Feasibility, Appendix C.

Martin/Martin completed an investigation of the masonry arch structure during this planning process to evaluate the nearly 120-year-old structure for use as a pedestrian underpass. Their investigation, Cheyenne East Park Greenway Masonry Culvert Investigation and Assessment Report, is included in Appendix D. This investigation noted a few things that will require additional investigation including potential settlement of the southeast wingwall and a crack along the west wall face that should be monitored. They reported that the general condition of the tunnel “appears to be in good to fair condition.” Patching of the masonry joints and water-proofing as needed are recommended maintenance items. The recommended clearing of overgrown vegetation at the north and south portals will occur with the construction of the Greenway. Not mentioned in their investigation, but something which needs to be done to ensure ADA accessibility through this underpass is a leveling of the floor to be in compliance with ADA slope, gap, and tripping hazard requirements.

Figure 8: Masonry Arch Structure South Portal Looking North https://www.bnsf.com/bnsf-resources/pdf/in-the-community/uprr-bnsf-joint-guidelines-railroad-grade-separation-projects.pdf https://www.bnsf.com/bnsf-resources/pdf/in-the-community/uprr-bnsf-joint-guidelines-railroad-grade-separation-projects.pdf https://www.bnsf.com/bnsf-resources/pdf/in-the-community/uprr-bnsf-joint-guidelines-railroad-grade-separation-projects.pdf https://www.bnsf.com/bnsf-resources/pdf/in-the-community/uprr-bnsf-joint-guidelines-railroad-grade-separation-projects.pdf

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 14

Kiwanis Park Greenway

There is an existing Greenway located around the Saddle Ridge development at the northeast corner of the intersection of East Pershing Boulevard and Whitney Road. A Greenway is recommended with this plan to connect with that existing Greenway. The proposed Greenway will continue south from East Pershing Boulevard into Kiwanis Park where it will split at the north edge of the proposed berm. The west leg will go around the north and west sides of the existing constructed wetland and end at the western property line. From that point the Greenway is planned to continue west as the Sun Valley Connector to the existing Greenway on the east side College Drive at the Sun Valley Open Space. The east leg of the Kiwanis Park Greenway will follow the downstream side of the proposed berm around the proposed detention basin to connect to the masonry arch structure. A gravel trail is planned on top of the proposed berm around the proposed detention basin. Conceptual level plan and profiles for the concrete Kiwanis Park Greenway are included as Appendix E.

The Greenway around the perimeter of the proposed berm is unique in that it will have a berm on both sides, as previously discussed, in order to hydraulically isolate the masonry arch structure from both the flow from Dry Creek as well as the storm water runoff that does not get into the proposed detention pond at Kiwanis Park but comes toward the masonry arch structure from east of Whitney Road. This section of Greenway needs to be designed to drain to one side where a small ditch is also constructed to carry stormwater that falls directly onto the Greenway or the adjacent berm slopes. This runoff will flow through the masonry arch structure.

Consideration needs to be given to the maintenance needs of a Greenway between two berms. As shown on the plan and profile sheets a wider area has been designed where the Greenway circles around the perimeter of the berm and heads back southwest toward the masonry arch structure. This area can be used to store snow that is plowed off of the Greenway.

Currently a passenger truck is used to plow snow on the Greenway. The masonry arch structure is only 6’ wide and will not accommodate vehicles. Therefore, an area has been designed near the opening of the arch structure that will accommodate a Y-turn made by a passenger truck for the purpose of backing up and driving back up the Greenway toward Whitney Road.

Signage will be required along this portion of the Greenway to warn users of poor sight distance around the curves as well as to encourage them to dismount their bicycles and walk through the masonry arch structure due to the reduced width.

Cheyenne Business Parkway Greenway

The Greenway going through the masonry arch tunnel will emerge from the underpass into the Laramie County Conservation District managed lands within the LEADS Cheyenne Business Parkway. This nearly 65-acre parcel through which Dry Creek flows has been dedicated as open space. Cheyenne LEADS is planning a 10’ wide concrete trail to be constructed on the north side of Campstool Road between Whitney Road and the east side of the Lowes Distribution Center. The Greenway will continue south from the masonry arch structure along the eastern side of the parcel where it will connect to the proposed LEADS trail along Campstool Road.

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 15

Next Steps

UPRR Approval

The implementation of this proposed design depends on the acceptance by the Union Pacific Railroad, as it not only requires construction to take place within their right of way to construct the berm and to bore the proposed culverts through their embankment, but also to utilize the masonry arch structure as a pedestrian underpass. To move forward the City of Cheyenne must enter into a Preliminary Engineering (PE) Agreement with the UPRR. The PE Agreement will allow conceptual level plans, drainage report, geotechnical report, and culvert boring plans to be reviewed by UPRR or their subcontracted reviewers. A monetary retainer must accompany the PE Agreement. The UPRR will bill the City of Cheyenne for actual review costs, which could be in excess of the retainer amount. Following acceptance of the conceptual plans the City of Cheyenne can proceed with final design plans, again to be reviewed by the UPRR, and ultimately construction if the plans are approved.

We believe this conceptual plan is a win-win for both the City of Cheyenne and the Union Pacific Railroad. Impoundment of stormwater on the UPRR embankment has reaches depths of 19 feet on multiple occasions in the past. A breach of the embankment in a large flood event would be catastrophic for downstream properties and the travelling public including traffic on Interstate 80, as well as catastrophic for the UPRR who relies on these mainline tracks for all railroad commerce into and out of Cheyenne to the east. The potential risk of a breach of the embankment needs to be stressed to the Union Pacific Railroad to emphasize the mutual benefit of this proposal.

Utility Investigation

There are many utilities located within the proposed project area. The scope of this study did not include utility locates. There is a potential for utilities to exist within the project area that are not shown on the conceptual design plans because they were not identified within the scope of this study.

Extensive grading will be required to construct not only the berm, but to shape the land inside the detention area. The proposed grading maximizes the available storm water detention storage while preserving the north portion of Kiwanis Park for park development of structures outside of the floodplain. Impacts to existing, known utilities include:

• BOPU Sanitary Sewer Main: The intent of the proposed grading is to not remove any cover on the 30” BOPU Sanitary Sewer line. All of the existing sanitary sewer manholes within Kiwanis Park are located within the existing floodplain or floodway. These manholes will continue to be within the floodplain and should be evaluated to limit infiltration during a storm event where water is being detained in this location. Additionally, approximately 18’ of fill will be placed over the 30” sanitary sewer line where the proposed berm is to be constructed over this existing main. Survey completed for the design should include invert elevations at the manholes on both the north and south side of the UPRR embankment to ensure adequate separation between the sanitary sewer main and the proposed borings through the UPRR embankment.

• Oil pipelines: two existing oil pipelines, classified as Hazardous Liquid Pipelines by the National Pipeline Mapping System, are located on the east side of the property and are depicted as the red lines in Figure 9. Fill will be placed on top of these pipelines with the construction of the berm. The location of the existing borings of these pipelines through the UPRR embankment will need to be determined to ensure adequate separation between these existing borings and

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 16 the proposed drainage culvert borings. One of these lines has existing utility markers for a petroleum pipeline owned by Plains Pipeline, L.P., the other line has existing utility markers for a crude oil pipeline owned by Suncor Energy USA Pipeline. Plains Pipeline, L.P. also has a fenced area at the south end of Whitney Road, inside an easement within Kiwanis Park containing a large valve and above ground piping. The sign on the fence says “UPRR Block Valve.” The proposed berm and other grading improvements have been made to avoid this fenced area.

Figure 9: Hazardous Liquid Pipelines per the National Pipeline Mapping System

• Communication Lines: A portion of this property was surveyed in approximately 2010 when the constructed wetland was added to the property. The survey from that project indicates the presence of a buried communication line along the east side of the constructed wetland. There is a recorded 16’ wide USWest Communications easement in this location as well as continuing north on the west side of Whitney Road to East Pershing Boulevard. Per Darrin Klawon, a Network Implementation Engineer at Lumen, this is a fiber optic line in conduit. A utility investigation and potentially potholing is recommended on this line anywhere grading will be done in its vicinity. This line is potentially located where removal of some cover is anticipated.

Additionally, fill material will be placed over this potential line with the construction of the proposed berm. During final design, construction of additional conduit for future expansion by Lumen may be desired.

• Overhead Electric Lines: There in an existing overhead electric line and utility poles located within the UPRR right of way, south of Kiwanis Park property. These utility poles will be impacted by the grading proposed in this location to ensure stormwater runoff is not trapped between the proposed berm and the existing UPRR berm. Coordination with the UPRR during the PE Agreement review process to ensure these facilities remain operational for the UPRR.

• In addition to these existing utilities, the Cheyenne Board of Public Utilities (BOPU) has expressed an interest in potentially adding an additional boring through the UPRR embankment for use as a re-use water line. Coordination with the BOPU should occur during the final design process to include this boring with the UPRR Preliminary Engineering Agreement submittal.

Likewise, if any improvements are desired by the BOPU on their existing 30” sanitary sewer line within the UPRR right of way, that should be included.

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 17

Projected Costs

See notes on following page.

East Park Greenway Underpass & Drainage Plan at the Union Pacific Railroad 18

Estimate of Probable Construction Costs Notes:

(1) This quantity includes the entirety of Kiwanis Park (See Note 2) and the disturbed area outside of the park boundary, at 0.4’ of existing topsoil.

(2) 247,100 CY± of material will be moved to complete this project. 100,000 CY± of material is required to create the proposed berms. (A 5% fill factor has been used in the earthwork calculations.) It is assumed that 1/3 of the excess material can be placed on‐site in the north portion of Kiwanis Parks that is to remain out of the floodplain. That equates to placing approximately 1’ of fill within that 27 acre area. It is assumed that the remaining material will be removed from the site.

(3) For the purpose of this estimate it has been assumed that the UPRR will require that the entire south property line of Kiwanis Park/North UPRR ROW line will be fences with 8’ tall chain link fence.

Estimate is based on 2022 dollars.

Estimated quantities begin south of the reconstructed Pershing/Whitney Intersection.

Estimated quantities end at the south end of the masonry arch structure and do not include any improvements south of the UPRR embankment.

East Park Greenway Underpass & Drainage Plan at the Union Paci f ic Rai l road

Appendices

A GLM Design Group : Final Lower Dry Creek Study (HEC ‐1 Sump 130) for Un ion Paci f i c RR Dry

Creek Cross ing with Appendices

B L i thos Engineer ing : Tunnel Feas ib i l i ty Memorandum

C 306 Rai l Serv ices : Pedestr ian Underpass Requirements / Feas ib i l i ty

D Mart in/Mart in : Masonry Culvert Invest igat ion and Assessment Report

E Summit Engineer ing : East Park Greenway 35% Design P lan and Prof i les

Final Lower Dry Creek Study (HEC-1 Sump 130) for Union Pacific RR Dry Creek Crossing

Summit Engineering 5907 Townsend Place Cheyenne, Wyoming 82009

September 12, 2022

P.O. Box 20505 | Cheyenne, WY 82003 | 307.214.7065 | gene@glmdesigngroup.com i Lower Dry Creek Union Pacific Crossing

September 12, 2022

Ms. Darci Hendon, PE Project Manager Summit Engineering 5907 Townsend Place Cheyenne, WY 82009

RE: Final Drainage Study of UPRR Dry Creek Crossing

Dear Darci:

GLM Design Group, LLC is pleased to submit the final drainage study for the Union Pacific railroad crossing of Lower Dry Creek. The preliminary study included an evaluation of alternative culverts under the UPRR embankment to replace the existing 6’ x 8’ masonry box arch culvert, constructed in 1903. The final study includes recommended sizes and locations required to hydraulically isolate the historic masonry culvert while protecting the UPRR embankment from impounded flood water.

The intent of this report is to provide a conceptual plan for making use of the historic masonry culvert as a part of the Greater Greenway System while taking into account UPRR design constraints and potential downstream impacts/mitigation.

If you should have any questions or comments as you review this report, please feel free to contact me at your convenience.

Sincerely, Gene L. MacDonald, PE Managing Principal GLM Design Group, LLC ii Lower Dry Creek Union Pacific Crossing

TABLE OF CONTENTS

PAGE

I. General Location and Description

A. Location B. Description of Property C. Description of Overall Project Development

II. Drainage Basins and Sub-Basins A. Major Basin Description B. Pre-Project Drainage Patterns

III. Drainage Design Criteria A. UPRR Guidelines B. Development of Design Models C. Hydrological Criteria

IV. Drainage Facility Design A. Preliminary Drainage Plan Overview………………………………………………………………………………………..14 B. Culvert Summaries C. Detention System Design D. Spillway Design E. Impacts on Downstream Facilities

V. Sediment/Erosion Control VI. Conclusions

A. Compliance with Standards B. Preferred Drainage Plan

VII. References

List of Figures Figure 1. Vicinity Map Figure 2. Existing Inundation Extents Figure 3. Proposed Berm

APPENDICES

HEC-1 Model Input Data and Output Summaries Pond Rating Curves HY-8 Culvert Analysis Reports HEC-RAS Output

1 Lower Dry Creek Union Pacific Crossing

I. General Location and Description

A. Location

The history of the project area begins with the passage of the Pacific Railroad Acts of 1862 that promoted the construction of a “transcontinental railroad” across the United States through the issuance of government bonds and grants of land to railroad companies. Transfer of land in the project area was finally patented in 1901 with the transfer of property to the Union Pacific Railroad.

Figure 1. Vicinity Map

2 Lower Dry Creek Union Pacific Crossing

The original transcontinental rail bed can be seen in aqua in Figure 1. The existing mainline tracks were constructed shortly after 1901 with the construction of the 6’ x 8’ masonry box arch culvert being completed in 1903. The original transcontinental rail bed was constructed through the project area in the 1870’s and remnants of that original embankment remain today as can be identified in Figure 1. As pointed out in both our proposal and, again, in our interview, the remaining transcontinental rail bed in our project area is a key element to our proposed design approach.

B. Description of Property

Currently the project area serves as a detention storage area for stormwater runoff in Lower Dry Creek and has been modeled as such since at least the 1970’s. Significant ponding up against the UPRR embankment has been noted by the USGS and others for storm events having occurred in the 1920’s and 1950’s. The project area is modeled as a sump in the 1988 Dry Creek Master Drainage Plan HEC-1 hydrologic model. The history of ownership of the project area immediately upstream of the UPRR Right-of-Way is a colorful one. Fred Peterson bought the property from the UPRR in 1912 and then lost it in the Great Depression. L.A. Foster acquired the property in 1939 and held it as agricultural property until 1999, when it was acquired by Dale Keizer. Mr. Keizer sold the property to the City of Cheyenne in early 2020 for the Future East Park.

Over the years since the existing UPRR main line tracks were constructed at the turn of the last century, the old transcontinental rail trestle over the historic Dry Creek channel was removed. Two oil pipelines and two fibre communication lines have been placed on the property. The Board of Public Utilities has also placed large sanitary sewer pipelines across the property. In 2010, an EPA 319 Project Grant was awarded to the County for a joint public-private constructed wetland project on Mr. Keizer’s property just upstream of the original transcontinental rail bed remnants. This 5-acre feature including a 2.5-acre forebay and 2.5-acre wetland chase is now the focal point of the City’s new East Park.

The following is a summary of the existing conditions:

Ground Cover - The site currently consists of native grasses in fair to good conditions. The property has historically been used for agricultural purposes including grazing of cattle. There are a few dirt roads on the property consisting of compacted earth and limited gravel. In 2021 a gravel trail was constructed around the forebay and wetland chase, connecting to a parking lot in the northwest corner of the park.

Grades – In general, the property drains to the south along moderate to shallow to moderate grades. As a part of the constructed wetland project, the northern third of the property was filled to a depth of approximately 8- to 10-feet with material excavated for the constructed wetland, effectively taking this portion of the property out of the regulatory floodplain.

Soil Type – A geotechnical study was completed in support of the constructed wetland project. The upper soils layers, based on field observations, are largely Clayey Sands. The depth to groundwater in the vicinity of the constructed wetland is approximately 8- to 12-feet. The material removed for the wetland and placed on the northern third of the property was compacted in shallow lifts and met all the required compaction test results.

Utilities – The site includes two oil pipelines and two fibre communication lines running north to south along the eastern part of the property. There are two BOPU pipelines that traverse the property east to west. There are dirt roads that have been cut in for access on the property.

3 Lower Dry Creek Union Pacific Crossing

Storm Drainage Facilities – Lower Dry Creek has run through this property since before the railroad was constructed and the Town of Cheyenne was incorporated. The original transcontinental rail bed bridged over the historic channel bed with a trestle bridge in the 1870’s. The construction of the existing UPRR embankment at the turn of the last century, included the construction of the existing 6’ x 8’ box arch culvert approximately 500-feet to the east of the historic thalweg of the channel. Lower Dry Creek has been conveyed through the box arch culvert since 1903, its historic channel being abandoned. Moreover, in the early 1990’s, the County completed a channel realignment of Lower Dry Creek between U.S. 30 and the UPRR embankment. Remnants of the historic channel thalweg remain in the northern third of the property and on portions of the adjacent Hess property. Local drainage is still directed to these remnants from north of Pershing Blvd.

C. Description of Overall Project Development

Russell + Mills recently prepared the East Cheyenne Community Park Master Plan. This master plan includes park amenities such as ball fields, tennis courts, pickleball courts, an indoor court building, swimming pool, open turn area, a skate park and trails.

II. Drainage Basins and Sub-Basins

A. Major Basin Description

The project area is located in the Lower Dry Creek Drainage Basin. Dry Creek is a tributary of Crow Creek and has a drainage area of 14.6 square miles, much of that upstream of the UPRR crossing. Between U.S.

30 and the UPRR crossing the average slope of this reach is 0.5 percent. The historic small, meandering low-flow channel was realigned and straightened by the County in the early 1990’s. Between U.S. 30 and the East Park property, the low flow channel of Dry Creek is a man-made channel – the historic meandering channel being eliminated and/or abandoned. The historic floodplain has been narrowed somewhat by development. At the UPRR, floodwaters become ponded to a depth of nearly 19-feet for the regulatory flood event. The total storage volume estimated for Sump 130 by the 1988 study was 1,986 ac-ft with a 100-year storage volume of 868 ac-ft under existing outlet conditions. Sub-basins 110, 120 and 130 in the HEC-1 model have a more immediate impact on peak discharge to Sump 130 for the more frequent storm events. For less frequent events (higher discharges), the entire Dry Creek basin begins to contribute to ponding in Sump 130.

The rating curve used to analyze the existing UPRR 6’ x 8’ box arch culvert for the 1988 Dry Creek Master Drainage Plan produced slightly inaccurate results when compared with the rating curve produced by the Federal Highway Administration’s HY-8 Culvert Analysis Program. HY-8 analysis indicates a maximum depth of 16.48 feet with a corresponding discharge of 770 cfs for the 100-year event. Based on the existing storage for the regulatory event from the HEC-1 model along with the more accurate outlet rating curve from the HY-8 analysis, the SWMM, Version 5.0.15 analysis produces a corresponding storage of 730 ac-ft. For the purposes of this report, we are basing our conclusions on the more accurate HY-8, UD-Culvert, and SWMM analyses while incorporating the existing storage from the 1988 HEC-1 analysis as a comparison point for proposed alternative culvert designs. For the final drainage report, we will adjust the HEC-1 analysis to more accurately reflect current conditions in the lower basin as well as separate out by-pass flow from Saddle Ridge that will not enter the re-configured storage facility.

Downstream of the UPRR crossing and Sump 130, the creek flows through the Cheyenne LEADS owned property, managed by the Laramie County Conservation District (LCCD), and the location of their new headquarters building, located between the UPRR and the Campstool Road crossing. There is a broad floodplain through this area with two ponded areas. There will be opportunity to coordinate and partner

4 Lower Dry Creek Union Pacific Crossing with the LCCD on expanding the existing storage areas for mitigation purposes. The proposed expansion also serves the LCCD’s mission statement for the area as well. Between Campstool Road and the I-80 crossing, the channel becomes entrenched with a noticeable headcut that threatens the downstream end of the Campstool Road culverts. The LCCD has been attempting to restore this reach incorporating ‘soft’ engineering techniques. This reach will be evaluated as will the LCCD’s headquarters property immediately upstream in the final drainage report. Near the confluence with Crow Creek, downstream of the I-80 crossing, the peak discharge for the regulatory event inundates and overtops the Campstool Road crossing (Campstool Road turns south and crosses Dry Creek a second time just upstream of the confluence with Crow Creek and near the Hereford Ranch).

B. Pre-Project Drainage Patterns

The Dry Creek Flood Control Project intercepts flow occurring in the upper Dry Creek Basin through sub-basin 70 in the HEC-1 model as well as flow from portions of the Cheyenne Regional Airport beginning with the 5-year storm event. There are four storage areas in the Dry Creek Flood Control Project which effectively attenuate peak discharges in the upper basin. This attenuation is dampened out by the time peak flows reach the U.S. 30 crossing. Peak flow downstream of the U.S. 30 crossing combined with flow from sub-catchments 120 and 130 contribute to significant ponding at the UPRR embankment for the regulatory event. Sub-basin 110 has a contributing drainage area of 0.35 sq. mi. including flow from Dakota Crossings. Sub-basin 130 has a drainage area of 2.0 sq. mi. and includes flow from Saddle Ridge and Sun Valley. Stormwater flow from newer developments east of Ridge Road such as Whitney Ranch will exacerbate the existing ponding in Sump 130 at the UPRR crossing. The existing 6’ x 8’ box arch culvert reaches full flow conditions beginning with a 10-year event in the basin. At this point, stormwater ‘stacks’ up against the UPRR embankment due to inadequate capacity at the outlet. The original transcontinental trestle bridge would have likely had significantly higher capacity than does the 6’ x 8’ box arch culvert. The UPRR could not have envisioned the ensuing development of Cheyenne since 1903 in the Dry Creek basin.

Runoff from sub-basins and an estimate of existing…