HomeMy WebLinkAboutFIRE STATION #12, FALCON RIDGE PUD - PRELIMINARY / FINAL - 2-94H - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTIV. SUMMARY
The combined use of the facility parking lot and the street section built for Country Club Road,
as well as the facilities proposed by Falcon Hill P.U.D. subdivision, ensures a safe,
economical, and sensible means to direct storm runoff in both the minor and major storm
events.
In the event clogging may occur in the curb and gutter section, this would not pose a serious
problem as runoff would top the gutters and flow towards the detention pond, therefore, not
endangering the safety of the adjacent property.
If the recommended construction (as illustrated on Exhibit A and outlined in this report) are
implemented, we feel the site will adequately handle the runoff for the minor as well as the
major storm. The improvements proposed for the construction of Fire Station No. 12 work in
harmony with the improvements planned for Falcon Ridge P.U.D. subdivision.
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IV. SUMMARY
III. DRAINAGE DESIGN
A. Scope of Design
The site is proposed for the construction of a new fire station. Because we will be changing
the current use of the site from a grassy, vacant lot to a building and an asphalt parking lot, the
permeability of the site is reduced. The site is planned for areas of landscaping, breaking up
the `sea of asphalt" which will help reduce the impermeability of the site. Prior to
consideration as a site for the fire station, the area was platted for single-family homes. The
final drainage report by Stewart & Associates took into account the decrease in the
permeability brought on by the construction of streets and homes. Because the proposed use of
a fire station will further decrease the permeability of the site, we will review again the
composite runoff factor "C" as part of this study.
We have considered a composite "C" factor when calculating the developed major storm runoff
and have included this calculation in the Technical Appendix. The proposed parking lot and
asphalt drive will collect and transport runoff from the north side of the facility to Country
Club Road and will drain into the proposed north detention pond through the sidewalk culvert.
The runoff from the south side of the facility will drain onto Falcon Hill Road eventually
exiting the site through a series of storm inlets (inlets IN-1 and IN-2) and storm sewers
eventually emptying into the north detention pond or flow directly into the proposed north
detention pond. Falcon Hill Road, with storm inlets and storm sewers, is planned as part of
the improvements scheduled when Falcon Ridge P.U.D. subdivision is constructed. The fire
station facility will utilize the streets and storm sewer improvements to control runoff.
B. Gutter. Channel Sizing. and Location
We have calculated the major storm runoff from the site in the developed condition. This rate
of discharge was used to investigate the capacity of the proposed street sections to handle the
predetermined flow rate. Please reference the Technical Appendix of this report for a review
of these calculations.
III. DRAINAGE DESIGN
C. Hydraulic Analysis
Historic Conditions
The site historically flows in a westerly direction both north and south from Ford Lane.
Stewart & Associates, who prepared the overall grading plan for Falcon Ridge P.U.D.
subdivision, used the natural lay of the land as a final grading and drainage pattern. In the
preparation of the fire station grading plan, we also incorporated the natural lay of the land and
integrated our grading into the grading scheme for the entire subdivision. In the preparation of
this report, we have closely followed the report prepared by Stewart & Associates for Falcon
_ Ridge P.U.D. subdivision.
11. HYDROLOGY AND HYDRAULICS
A. Introduction
The hydrologic techniques and analytical tools utilized in the design flow hydrology for the
proposed improvements to the site are described in this chapter. The facilities constructed as a
result of this analysis will convey the runoff resulting from storm events with the design
frequencies of 2-year and 100-year recurrence intervals. Because there will be no detention,
the facilities constructed will be sized to carry the major storm to the proposed north detention
pond.
B. Design Objectives and Approach
The objective of the hydrologic analysis for the Fire Station No. 12 site concentrates on two
principal issues:
1. To investigate the impact of the proposed development upon the changes in the
magnitude of storm runoff.
2. Designing for the conveyance of storm runoff by means of appropriate
strategies as specified by the applicable drainage guidelines of the City of Fort
Collins and compliance with the stormwater drainage report prepared for
Falcon Ridge P.U.D. subdivision.
The Rational Method, in widespread use in the Colorado area, will be utilized for the
determination of the runoff magnitude from the site in the developed condition and to size the
appropriate means of conveying this runoff. The Rational Method was used in the preparation
of the Final Stormwater Drainage Report prepared for Falcon Ridge P.U.D. subdivision.
The limit of application of the Rational Method is approximately 160 acres. Because the site is
approximately 1.05 acres (more or less), the Rational Method will be used for this analysis.
Accomplishing the modeling objectives has been attained through a sequence of model
simulation runs for the contributing basins. (Please reference Exhibit A). The 100-year storm
output in the developed condition has been used for the design of curb and gutter sections as
well as the sizing of the sidewalk culvert. We have determined the minor storm runoff flows
to analyze the capacity of the site to handle nuisance flows in smaller storms.
II. HYDROLOGY AND HYDRAULICS
the site and the planned construction of the north detention pond, no on -site detention will be
proposed.
Runoff from the fire station building and parking lots will be directed to Country Club Road.
As detailed in the Final Stormwater Drainage Report for Falcon Ridge P.U.D. subdivision, a
24-foot wide sidewalk culvert will be constructed on the south side of Country Club Road at
the intersection of Highway 1. As part of this study, we will investigate the impact the
proposed construction of the fire station would have on the opening size of the inlet.
I. INTRODUCTION
The City of Fort Collins is proposing the construction of a new fire station facility on the north
side of the City. The location selected is part of a recently -platted subdivision known as
Falcon Ridge P.U.D.. Falcon Ridge P.U.D. is located south of Country Club Road, west of
Ford Lane, east of Highway 1, and north of Spaulding Lane. The parcel of land which the
City would like to acquire comprises Lots 15, 16, and 17 as currently platted in the Falcon
Ridge P.U.D. subdivision. As access to the facility would be provided from Country Club
Road, not Falcon Hill Road as platted, the bulb portion of the cul-de-sac at the north end of
the proposed Falcon Hill Road would be realigned to the west to provide a buildable site for
the fire station building. Lots 18 and 19 of Falcon Ridge P.U.D. subdivision would be
expanded to the west to compensate for the loss of buildable area due to the realignment of the
cul-de-sac.
This report will study the impact on the proposed drainage features as shown on the revised
construction drawings prepared by our firm for Falcon Ridge P.U.D. subdivision and the
existing drainage features surrounding the site as a result of the construction of Fire Station
No. 12. This report follows closely the Final Drainage Report prepared for Falcon Ridge
P.U.D. subdivision by Stewart & Associates.
A. Scope of Work
The areas of emphasis, included as part of this investigation, are:
1. A hydrologic analysis
2. A hydraulic analysis
3. Review of detention considerations by Stewart & Associates
B. Executive Summary
This report was prepared for Fire Station No. 12 in Fort Collins, Colorado to evaluate
proposed drainage improvements required as a result of the construction of a fire station
complex. Stewart & Associates have prepared an overall drainage report for Falcon Ridge
P.U.D. subdivision, which we will reference in the preparation of this report. The north half
of the site is located within the boundaries of the Dry Creek Drainage Basin, and the south half
of the site is located within the boundaries of the Greenbriar/Bvergreen drainage basin. Our
investigation and report will comply with the guidelines established for improvements within
these master drainage basins as set forth by the City of Fort Collins, Stormwater Facilities
Department.
Proposed improvements to the site include the construction of an asphalt parking lot, asphalt
drives to access the building and parking lot, a fire station, and related landscaping and
sidewalks. The drives and parking lot will be used to collect and convey runoff to the proposed
north detention pond as described in the stormwater drainage report prepared for Falcon Ridge
P.U.D. subdivision. The proposed north detention pond will be constructed west of the fire
station complex, south of Country Club Road, and east of Highway 1. Due to the proximity of
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I. INTRODUCTION
TABLE OF CONTENTS
I. INTRODUCTION
A. Scope of Work
B. Executive Summary
II. HYDROLOGY AND HYDRAULICS
A. Introduction
B. Design Objectives and Approach
C. Hydraulic Analysis
III. DRAINAGE DESIGN
A. Scope of Design
B. Gutter, Channel Sizing, and Location
IV. SUMMARY
V. TECHNICAL APPENDIX
Design Calculations
Erosion Control Calculations
FINAL DRAINAGE REPORT
for
FIRE STATION NO. 12
CITY OF FORT COLLINS
STORMWATER FACILITIES DEPARTMENT
PREPARED BY
THE ENGINEERING CO.
a 2310 EAST PROSPECT
FORT COLLINS, CO 80525
RICK R. PICKARD, P. E.
August 1996
.y
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August 26, 1996
FILE: 96-056A
City of Fort Collins
Stormwater Utility
235 Mathews Street
Fort Collins, CO 80524
ATTENTION: Mr. Glen Schleuter
RE: Fire Station No. 12, City of Fort Collins
A part of Falcon Ridge P.U.D.
Dear Glen:
Enclosed is the Final Drainage Report for Fire Station No. 12 prepared for the City of Fort Collins.
This facility is proposed for construction on a parcel of land currently platted in the Falcon Ridge
P.U.D. subdivision. Falcon Ridge P.U.D. subdivision will be re -platted to allow for the sale and
reuse of the property for fire station use. Access to the building and parking lot would be from
Country Club Road.
This report was prepared to answer the hydrologic and hydraulic concerns regarding the changes
proposed by the construction of a fire station. As platted, Falcon Ridge P.U.D. was to have been
exclusively single-family lots. The construction of a fire station complex will alter the intended use of
the site by the construction of parking lots, drives, and a larger building pad which will generate
additional impervious areas.
This report was prepared in harmony with the Final Drainage Report prepared by Stewart &
Associates for Falcon Ridge P.U.D. subdivision. This report is in compliance with the City of Fort
Collins Stormwater Design Criteria (current at the time of the preparation of this report). By your
review and approval of this report, we can assure the project was completed within the standards and
specifications of the City's Stormwater Drainage Criteria.
Should you have any further questions or require further discussion, please feel free to contact our
office.
Sincerely yo s,
Rick R. Pickard, P. E.
Associate
The Engineering Co.
Enclosures
The Engineering Co.
2310 East Prospect
Ft. Collins, CO 80525
Phone: (970) 484-7477
FAX: (970) 484-7488
FINAL DRAINAGEREPORT
Fm
FIRE STATION NO. 12
A PART OF FALCON RIDGE P.U,D.
CITY OF FORT COLLINS
SIORMWATER FACILITIES DEPARTMENT
August 1996