HomeMy WebLinkAboutTHE GROVE AT FORT COLLINS - PDP - MJA110001 - REPORTS - DRAINAGE REPORTOverall Drainage Report
Date: June 1, 2011
Project: Amended CSURF Centre for Advanced Technology Project No. 502-001
Overall Development Plan
Fort Collins, Colorado
Attn: Stormwater Staff
Fort Collins Utilities
700 Wood Street
Fort Collins, Colorado 80524
Dear Stormwater Staff:
This letter report accompanies the Major Amendment submittal for the CSURF Centre for Advanced
Technology Overall Development Plan (ODP). Specifically, it serves to document the overall
drainage impacts associated with the amended ODP.
The ODP area is comprised of various properties all owned and managed by the Colorado State
University Research Foundation (CSURF). The parcels comprise roughly 116.7 acres contained
within Section 23, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort
Collins, County of Larimer, State of Colorado. Prospect Road is located to the north, Shields Street
to the west, Burlington Northern Railroad to the east, and Drake Road to the south. It should be
noted that a FEMA regulatory floodplain3 roughly bisects the ODP area, flowing west to east.
Much of the roadway and drainage infrastructure currently in place was constructed with the Centre
for Advanced Technology Special Improvement District. The design of said facilities dates back to
master plans for the area developed in the late 1980’s. The corresponding drainage master plan for
the Center for Advanced Technology2 has governed much of the subsequent development within the
original ODP boundary.
The proposed amendment to the existing CSURF Centre for Advanced Technology ODP of record
does not change any land uses or otherwise influence major drainage patterns. The only changes of
any significance are related to future road connections. The current ODP shows Rolland Moore
Drive extending from its present terminus near Shields Street at CARE Housing towards the stub
street constructed with the Gardens on Spring Creek near Centre Avenue. The depicted alignment
roughly follows the northern boundary of ODP Parcel C. If constructed as currently shown, Rolland
Moore Drive would have severe adverse impacts to Army Corps of Engineers jurisdictional wetlands,
not to mention the ramifications related to the FEMA floodway and 100-year flood fringe.
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Therefore, the proposed ODP amendment will relocate Rolland Moore Drive further south in an
alignment that roughly parallels the Larimer County Canal No.2, and connects to Centre Avenue
across from the southern-most entrance into the Natural Resources Research Center. The ODP of
record also depicts the future connection of Northerland Drive from the extension of Rolland Moore
Drive into the Windtrail neighborhood. This street is proposed to be eliminated from the ODP
altogether. Not only will this prevent traffic from cutting through the Windtrail neighborhood, but it
removes an infeasible perpendicular roadway crossing of the FEMA floodway.
The entire ODP area is located within the Spring Creek Major Drainage Basin. This area is the
subject of numerous drainage studies and analyses. First and foremost is the Spring Creek Master
Drainage Plan5 itself. The master drainage plan assumed land uses and drainage patterns
consistent with the current CSURF Centre for Advanced Technology ODP. Since the proposed
amendment will not be altering any of these parameters, the Spring Creek Master Drainage Plan
remains valid.
More recently, the City of Fort Collins and CSURF conducted a joint study1 to investigate alternative
stormwater detention and conveyance solutions. ODP Parcels D, E, and F were of particular
interest in this analysis. Additionally, the study increased the percent impervious value of Parcel C
to account for more intense future development. The results of the study confirmed that Parcel C
can develop roughly 24 acres with an impervious value of 90% without any “on-site” detention.
Consistent with stormwater master planning best practices, detention is handled with a regional
approach.
The proposed ODP amendment also depicts two new local streets within Parcel C. These
alignments are consistent with The Grove at Fort Collins Project Development Plan (PDP) submitted
to the City on 12.08.10. Please refer to the project-specific drainage report4 submitted with the
PDP for a more thorough description and analysis of the stormwater solutions proposed with the
development of Parcel C.
While not technically a part of this proposed ODP amendment itself, it should be noted that there is
currently a plan in process to realign the Larimer County Canal No. 2 within the limits of the ODP.
Specifically, the proposal is to shift the stretch between Parcel B and Parcel C further south. The
Ditch Company is currently working to finalize an agreement with CSURF (the land owner) for said
realignment. The concept is to create a newly cut and compacted channel, approximately 50’ south
of the existing route. The purpose is to eliminate any potential seepage from the ditch and to gain
separation from the steep embankment and the numerous large trees that have overtaken the
current ditch corridor. This creates a better situation for the Ditch Company, the land owner, and
the natural habitat. The old channel section will be restored to a gentler landscape, essentially
creating a wildlife refuge and substantial buffer for future development of Parcels B and C.
The Amended CSURF Centre for Advanced Technology Overall Development Plan is consistent with
previous ODP’s and all applicable drainage studies and stormwater improvements in the area. The
changes proposed (i.e., re-aligning Rolland Moore Drive and eliminating Northerland Drive
connection) only help the future drainage condition. The newly proposed roadway alignment is not
located in the floodplain or floodway, and therefore, the current effective hydraulic model does not
need to be revised. All future development plans and construction activity within the floodplain or
floodway shall be in conformance with Chapter 10 – Flood Prevention and Protection of the City of
Fort Collins Municipal Code (COFCMC).
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In summary, this Overall Drainage Report letter adequately addresses any potential stormwater
changes associated with the proposed ODP amendment. Essentially, there are no changes at a
major drainage level. The ODP complies with the City of Fort Collins Spring Creek Master Drainage
Plan and Chapter 10 of the COFCMC. Other reports contain more in-depth studies and analyses of
the ODP area. The Amended CSURF Centre for Advanced Technology ODP does not affect the
previous drainage models, nor do the existing studies conflict with the proposed ODP amendment.
Please feel free to contact me if you have any questions.
Sincerely,
Nicholas W. Haws, PE , LEED AP
References
1. Alternative Analysis for the Design of the Mason Street Outfall, November 2010, Ayres
Associates.
2. Amended Master Plan for the Centre for Advanced Technology, February 1988, RBD, Inc.
Engineering Consultants.
3. Flood Insurance Rate Map (FIRM) Panel 0987F, Effective Date December 19, 2006, Federal
Emergency Management Agency (FEMA).
4. Preliminary Drainage and Erosion Control Report for The Grove at Fort Collins, April 6, 2011,
Northern Engineering.
5. Spring Creek Master Drainage Plan, May 5, 2003, Anderson Consulting Engineers, Inc.
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