HomeMy WebLinkAboutTAPESTRY - PDP240001 - SUBMITTAL DOCUMENTS - ROUND 1 - Variance Request
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April 18, 2024
Sophie Buckingham
Engineering Development Review
City of Fort Collins
281 N. College Avenue
Fort Collins, CO 80524
Project # 473-010
Tapestry PDR210019 – Modified Minimum Flowline Grade Variance Request
Variance Description:
This is a request for variance to the standard minimum flowline grade contained in Chapter 7.4B of the Larimer County
Urban Area Street Standards (LCUASS Fort Collins).
Variance to this Standard will allow for closely matching existing conditions and alleviate the need for a much larger
disturbed area of disturbance.
Technical Design Criteria:
Public Streets to be designed to vertical alignment criteria in the Larimer County Urban Area Street Standards (Fort
Collins). This approved requirement is stated below:
Chapter 7.4 General Design Elements - Section B - Vertical Alignment
2. Minimum Flowline Grades. Minimum flowline grades for gutters shall be 0.50 percent, except the bulb of cul-de-sacs
where the minimum shall be 1.0 percent.
Identifying the issue:
The existing vertical curb and gutter along the northern project boundary of Tapestry was constructed at 0.4% per topo
collected by Northern Engineering of March 22, 2021 (NE Project number 368-005). The grade is flatter than the allowable
minimum slope as required by Larimer County Urban Area Street Standards (LCUASS) and extends from the west end of
the project to the east end at a constant slope. Part of Tapestry’s scope is to remove the existing curb & gutter to provide a
3’ landscape buffer and parallel parking along the Buckingham Street frontage. While it is considered high priority to
improve upon an existing condition where there might be a deficient area that is not currently meeting code, this
variance is essential to accommodate existing conditions and ensure optimal functionality and compatibility with
surrounding infrastructure.
Alternatives Considered:
1. Alternative 1: Hold upstream elevation and maintain minimum slope going from west to east along the site.
Since the site frontage being improved is nearly 500 feet long, holding a minimum grade of 0.5% for the entire frontage
would result in a spot approximately 0.4’ lower than the existing gutter on the east (downhill) end of the site. To daylight
this grade further east along Buckingham an amount in excess to 200 LF of curb and gutter, offsite landscaping, and
offsite sidewalks as well as a larger section of asphalt being removed and replaced moving from west to east.
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Maintaining a flowline grade of 0.5% would work against the existing topography and flow patterns and thereby trigger
extensive alterations to the landscape and increase potential disruptions to the surrounding environment. The additional
costs of this option would far exceed the benefits associated.
2. Alternative 2: Add a low point along the replaced section of Buckingham curb & gutter.
This alternative looked at holding the minimum grade of 0.5% and the existing tie in elevations on each side of the project
by creating a low point somewhere on the site frontage.
This alternative would change the pre-existing drainage patterns along the site’s frontage causing a need to route storm
sewers to the northwest corner to detain or pass newly created sump drainage flows. This would have a large impact on
the site’s program as it does not require storm infrastructure in this area without the creation on this condition. Localized
low points can be avoided while maintaining current drainage patterns while taking necessary precautions during
construction, therefore this alternative was considered not ideal and avoidable.
Justification for reduced flowline grades
This request is grounded in the acknowledgement of specific instances where 0.4% grade is not only sufficient but also
standard within our community. For example, City of Greeley Street standards currently list 0.4% flowline grades as
minimum for new street construction, which has proven effective in managing stormwater runoff and ensuring proper
drainage without compromising safety or functionality. However, it is noted that during construction, flatter flowline
grades will heighten the need for tighter construction tolerances and quality control. These tighter construction
tolerances are achievable with today’s construction techniques with the proper care and consideration.
Conclusion
We do not feel that this variance will increase risks to public health, safety, or welfare, nor will it reduce the design life of
any public roadway or cause the City of Fort Collins additional maintenance costs.
Furthermore, the proposed variance maintains a reasonable balance between compliance with regulatory standards and
practical considerations, ensuring that the development remains in harmony with the City’s objectives while still meeting
the necessary criteria for functionality and safety.
Please call if you have any questions.
Sincerely,
Cody Pape, P.E.
Project Engineer