HomeMy WebLinkAbout05.11.17 GAC Agenda 3 Arapahoe UP CEAPGAC May 11, 2017
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C I T Y O F B O U L D E R
INFORMATION ITEM FOR:
ENVIRONMENTAL ADVISORY BOARD – April 5, 2017
PLANNING BOARD – April 6, 2017
TRANSPORTATION ADVISORY BOARD – April 10, 2017
OPEN SPACE BOARD OF TRUSTEES – April 12, 2017
WATER RESOURCES ADVISORY BOARD – April 17, 2017
PARKS AND RECREATION ADVISORY BOARD – April 24, 2017
GREENWAYS ADVISORY COMMITTEE AGENDA ITEM
MEETING DATE: May 11, 2017
SUBJECT:
Community and Environmental Assessment Process (CEAP) for the Boulder Creek Arapahoe
Underpass Project (Arapahoe Underpass project) along the Boulder Creek Multi-Use Path at
Arapahoe Avenue near 13th Street
REQUESTING DEPARTMENT:
Bryant Gonsalves– Transportation Project Manager
Melanie Sloan-Transportation Planner
PURPOSE: A summary of the CEAP is being provided to board members as an information
item. It is requested you review the full CEAP and forward any comments or concerns
regarding the CEAP to your Greenways Advisory Committee representative. If you have
questions on this material, please contact Melanie Sloan at 303-441-4934 or
SloanM@bouldercolorado.gov. The full CEAP is available at:
https://bouldercolorado.gov/planning/boulder-creek-arapahoe-and-13th-underpass
GREENWAYS ADVISORY COMMITTEE ACTION REQUESTED:
A recommendation from the Greenways Advisory Committee to City Council concerning the
CEAP for the Arapahoe Underpass project is requested. Pending GAC approval, City
Council will receive the CEAP as a call up item in spring 2017.
Attached is the Executive Summary from the Boulder Creek Arapahoe Underpass project,
Boulder Creek Multi-Use Path at Arapahoe Avenue near 13th Street CEAP summarizing the
proposed recommendations.
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Boulder Creek Arapahoe Underpass Project
Boulder Creek Multi-Use Path at Arapahoe Avenue near 13th Street
EXECUTIVE SUMMARY
This report documents the Community and Environmental Assessment Process (CEAP) for the
Boulder Creek Arapahoe Underpass project (Arapahoe Underpass project). The Arapahoe
Underpass project will provide a safer, more accessible and less flood prone underpass along
the Boulder Creek Multi‐Use Path at Arapahoe Avenue near 13th Street. The voter‐approved
2014 Community, Culture, and Safety Tax (CCS) ballot initiative provides $2.5 million in project
funds and requires construction to be completed by year end 2018. Current cost estimates for
all proposed design options considered for this project are greater than $2.5 million. The
planning and design process began in early 2016 and continued through winter, 2017.
Construction is currently anticipated to begin in late 2017 or early 2018.
The purpose of the CEAP is to assess potential impacts of conceptual project options in order to
inform the selection of desired elements and the refinement of a preferred option. The CEAP
provides the opportunity to balance multiple community goals in the design of a capital project
by assessing a project against the policies outlined in the Boulder Valley Comprehensive Plan
and departmental master plans. This CEAP summarizes an evaluation of two underpass, two
north path connection and two south path connection options, with a focus on safety,
accessibility and mobility, environment and user experience, impacts to existing infrastructure,
and construction cost and duration.
For each of the underpass options considered in this CEAP the width of the underpass will be 24
feet; the Boulder Creek Path width will be widened to 15 feet; the approaches to the underpass
on the north and south will be straightened and the grades reduced to 5% or less; the
pedestrian and bicycle bridge over Boulder Creek south of the underpass will be replaced and
widened; the existing seating area southeast of the underpass will be removed; pedestrian
lighting will be installed on the north and south approaches to the underpass and within the
underpass; public art will be incorporated; mature trees and vegetation will be removed and no
additional property will need to be acquired.
The two underpass options differ with regards to the straightness of the approaches to the
underpass, safety and mobility impacts to existing movement patterns, the potential to restore
a section of Boulder Creek, their impact to the Civic Area Central Park and its green spaces, the
way high water closure days are reduced, the number of trees impacted, the adaptability of the
design to future vehicular bridge replacement, the potential to support future flood passage
improvements, maintenance needs, construction cost and the duration of construction.
Hydraulics analyses on each underpass option show no rise in the water surface of the 100‐year
flood. Impacts to wetland habitat will be mitigated per United States Army Corps of Engineers
404 Wetlands Permit stipulations and City of Boulder Stream, Wetlands and Water Body
Protection regulations (BRC 9‐3‐9).
Underpass Option 1 would modify the existing underpass. Underpass Option 2 would construct
a new underpass between the Arapahoe Avenue bridge and 13th Street. North Path Connection
1 would reconstruct the existing path connections on the north side of the underpass. North
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Path Connection 2 would move the path connection to the Arapahoe Ave and 13th St
intersection closer to the Boulder Creek Path and build a single, tall retaining wall with a
handrail between the two paths. To achieve the project goal of reducing the steepness of the
southern approach to the underpass, the convergence of the paths and the existing pedestrian
and bicycle bridge over Boulder Creek on the south side of the underpass would move
downstream. South Path Connection 1 would reconstruct the existing multi‐use paths and
connections on the south side of the underpass. South Path Connection 2 would replace the
existing pedestrian and bicycle bridge over Boulder Creek on the south side of the underpass
with a new bridge that would cross over Boulder Creek and the Boulder Creek Path and connect
the multi‐use path south of the creek to the on‐street crossing on Arapahoe Ave at 13th St.
South Path Connection 2 would require the Boulder Creek Path to remain at creek level further
downstream to provide clearance under this new bridge.
The Arapahoe Avenue Reconstruction Project (15th Street to Broadway) will be concurrent to
the Arapahoe Underpass construction. This project will complete the Arapahoe Avenue,
Folsom to 15th Street bond funded roadway pavement reconstruction work begun in 2013. This
project will reconstruct the deteriorated asphalt pavement with concrete pavement; improve
drainage of the roadway; reconstruct sidewalks, driveways, and curb ramps to meet Americans
with Disability Act requirements; redesign the on‐street crossing at Arapahoe Avenue and 13th
Street to improve safety; incorporate minor urban design and landscaping improvements and
replace water and irrigation utilities along the stretch of Arapahoe Avenue from 15th Street to
Broadway. The reconstruction of 15th Street to Broadway has a budget of $2.5 million, paid for
by City of Boulder Transportation and Utilities funds.
A city storm sewer box culvert crosses Arapahoe Avenue and outlets to Boulder Creek. The
existing box culvert is leaking and the outlet to Boulder Creek needs to be moved further
downstream to accommodate project improvements. Because of these, the project will replace
the box culvert during construction.
The Smith‐Goss ditch pipe, installed in the 1930’s, runs underneath Civic Area Central Park and
along the south side of Arapahoe Avenue. The pipe is in deteriorated condition and needs to
be replaced. The Arapahoe Underpass and Arapahoe Avenue Reconstruction projects will
complete this final section of ditch pipe replacement.
To address the safety issues associated with the existing underpass and path connections,
changes to the topography of the project area will require the removal of mature trees and
vegetation. Re‐grading of the project area is required to improve the safety issues of narrow
path width, poor sightlines and steep grades. The required excavation to widen, straighten and
lower the path, replace the box culvert under 13th Street and to replace the ditch pipe will
require the removal of trees and vegetation within the construction area. The underpass
designs were revised several times to minimize the removal of trees identified for preservation.
Opportunities to preserve additional trees will be sought during final design.
The on‐street crossing at Arapahoe Ave and 13th St has a history of collisions and a high volume
of pedestrian and bicycle crossing activity. Because of these, the project included the Arapahoe
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Avenue Reconstruction Project redesign of the on‐street crossing within the CEAP discussions.
However, the on‐street crossing options are not evaluated through the CEAP.
On‐Street Crossing 1 would re‐construct the existing on‐street crossing and pedestrian refuge
median. On‐Street Crossing 2 would re‐construct the existing pedestrian refuge median to
include a z‐crossing, where the crossing is offset on either side of the median to turn those
crossing Arapahoe Avenue to face oncoming traffic. Both On‐Street Crossing 1 and 2 would
increase the sidewalk detachment from the road on the north side of Arapahoe Avenue from
the current four‐feet to eight‐feet, providing better bicycle turning movements and greater
visibility between those crossing Arapahoe Avenue and vehicle drivers travelling along it.
On‐Street Crossing 3 and On‐Street Crossing 4 would re‐construct the intersection of Arapahoe
Ave and 13th St as a raised intersection crossing. On‐Street Crossing 4 would reduce Arapahoe
Avenue from three to two lanes through the removal of the center turn lane and incorporation
of a curb extension from the south side multi‐use path. Both On‐Street Crossing 3 and 4 would
remove the existing pedestrian refuge median, allow for diagonal crossing through the
intersection and require an attached sidewalk on the north side of Arapahoe Avenue.
The preferred project options are Underpass Option 1, North Path Connection 2, South Path
Connection 1 and On‐Street Crossing 1. These combined options achieve the goals of the
project which include improving sightlines by widening the path, reducing the steepness of the
approaches to meet Americans with Disabilities Act requirements, straightening curves in the
path and reducing the number of high water closure days. These options also are more likely to
encourage use of the underpass instead of the on‐street crossing and are more equally
supportive of all travel patterns within the project area. These options preserve more green
space within Civic Area Central Park than the other options and provide for an eight‐foot
detached sidewalk on the north side of Arapahoe Avenue. Additionally, this option minimally
impacts the future replacement of the existing vehicular bridge when that bridge reaches the
end of its useful life.
These options impact an estimated 50 trees measuring six‐inches in diameter or larger, of
which 15 are mature measuring 20‐inches in diameter or larger. Opportunities to preserve
additional trees will be sought during final design. The compact size of the underpass project
area constrains the ability to replant an equal number of trees as will be removed. Additional
planting opportunities outside of this area will be sought (e.g., within Civic Area Central Park,
adjacent to Boulder High, south of Boulder Creek, etc.).
Feedback received from the public on each of the options:
Mixed for the underpass options with more people not seeing a difference in the
function of either underpass and so preferring Underpass Option 1 for its ability to meet
the project goals at a lower cost with less disruption to the travelling public during
construction
Ambivalent towards the North Path Connections though the Parks and Recreation
Advisory Board and Parks and Recreation staff preferred North Path Connection 2
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Mixed for the South Path Connections, with more people preferring South Path
Connection 1 for its simpler path connections which more equally benefit all users and
routes and introduced fewer users into the on‐street crossing by encouraging use of the
underpass. This option was also preferred because it had less impact to trees and
vegetation, was less expensive and required less time to construct. Some members of
the cycling community had a strong preference for South Path Connection 2
Mixed for the On‐Street Crossing options with more people preferring On‐Street Crossing 1
than any other On‐Street Crossing option. Staff prefers On‐Street Crossing Option 1 because it
provides a safer crossing for all users while supporting existing north‐south bicycling movement