HomeMy WebLinkAboutJEFFERSON COMMONS PUD - FINAL - 50-95A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE RELATED DOCUMENTPROJECT
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VICINITY MAP
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Figure 1. Vicinity map.
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Ayres Associates
INTRODUCTION
This report summarizes the storm drainage investigations performed for the proposed
Jefferson Commons in Fort Collins, Colorado. A hydrologic analysis of the proposed
development was completed to determine the magnitude and location of storm runoff,
allowable release rates into an existing drainageway, develop detention ponds, and
determine downstream effects of the proposed development. This study and drainage plan
was prepared to meet City of Fort Collins Storm Drainage Design Criteria for the
development.
The Jefferson Commons is located along the north side of West Elizabeth Street
approximately 1,000 feet west of Taft Hill Road as shown in Figure 1. It consists of
approximately 16.7 acres occupying the northeast quarter of Section 16, Township 7 North,
Range 69 West, of the 6th Principal Meridian and lies within the West Plum Street basin.
PREVIOUS STUDIES
Previous drainage studies of the area include (1) West Plum Street Basin Master Drainage
�J Plan (RCI 1990), and (2) Update of Hydrologic Analysis for West Plum Street Basin (Ayres
Associates 1995). These were reviewed to assist with the preparation of this report.
EXISTING DRAINAGE CONDITIONS
The Jefferson Commons site lies along the north side of West Elizabeth Street,
approximately 1,000 feet west of Taft Hill Road. Skyline Mobile Home Park lies to the north,
Sunray Place Apartments and West Elizabeth Plaza to the east, and Miller-Layland
subdivision to the west. A major drainageway runs eastward across the property from
Miller-Layland to the Sunray Place Apartments. The drainageway is constricted and
improved both up- and downstream, but remains unimproved on the site. The majority of
runoff flows to this drainageway. Along West Elizabeth Street, there are two small houses,
several sheds, and a horse corral. An irrigation/drainage ditch lies between these houses
and Elizabeth Street. The ditch is overgrown with vegetation, filled with debris, and appears
to be unused with the exception of storm drainage that it collects off of Elizabeth Street.
The ditch dead ends at the West Elizabeth Plaza boundary where curb and gutter begin.
Curb and gutter have not been installed along Elizabeth Street adjacent to the property.
Except for the two houses and a horse corral, the site is currently at historic conditions
covered with native grasses.
Existing runoff calculations were performed to determine the 2- and 100-year runoffs for the
site using the Storm Water Management Model (SWMM, UDFCD 1985). A schematic
showing the linkages of the subcatchments and conveyance elements for the existing
conditions is shown in Figure 2. The overall basin is shown in Figure 3. Both figures
contain information from the West Plum Street Master Drainage Plan SWMM model. The
hydrologic analysis used the Master Plan SWMM model with those subcatchments
representing the Jefferson Commons site altered to reflect existing conditions.
Ayres Associates
LIST OF TABLES
Table 1. Subcatchment Constants.......................................................................................8
Table 2. Basin Parameters...................................................................................................8
Table 3. Conveyance Elements and Peak Discharges.........................................................9
Table 4. SWMM Results Comparison................................................................................10
Table 5. Detention Pond #144 Outlet Rating Curve...........................................................11
Table 6. Detention Pond #172 Outlet Rating Curve...........................................................13
Table 7. Detention Pond #170 Outlet Rating Curve...........................................................13
Table 8. Offsite Hydraulic Impacts.....................................................................................15
Table 9. Security Requirements.........................................................................................18
Ayres Associates
TABLE OF CONTENTS
INTRODUCTION..................................................................................................................1
PREVIOUSSTUDIES ............................. .............................................................................. 1
EXISTING DRAINAGE CONDITIONS..................................................................................1
PROPOSED DRAINAGE CONDITIONS...............................................................................5
STORM DRAINAGE FACILITIES.......................................................................................10
Plum Creek Hydraulic Analysis........................................................................................12
Existing Conditions Hydraulics.....................................................................................12
Proposed Conditions Hydraulics..................................................................................14
OffsiteImpacts.............................................................................................................14
EROSIONCONTROL PLAN...............................................................................................15
Overview.........................................................................................................................15
WindErosion...................................................................................................................15
RainfallErosion...............................................................................................................15
APPENDIX........................................................................................................................... --
ILIST OF FIGURES
Figure1. Vicinity map..........................................................................................................2
Figure 2. Overall basin existing conditions SWMM schematic . ............................................. 3
Figure 3. West Plum Street basin........................................................................................4
Figure 4. Overall basin proposed conditions SWMM schematic...........................................6
Figure 5. Jefferson Commons site SWMM schematic .................................................. :....... 7
Figure 6. Construction schedule.........................................................................................16
Ayres Associates
/SIRES
ASSOCIATES
March 18, 1996
Mr. Basil Hamdan
City of Fort Collins
Stormwater Utility
235 Mathews Street
Fort Collins, Colorado 80524
Re: Jefferson Commons PUD
Dear Basil,
Enclosed please find our "Final Grading and Drainage Report For Jefferson Commons PUD"
This report was prepared in accordance with the City of Fort Collins Storm Drainage Criteria as
revised in May 1991.
We appreciate your time and consideration in reviewing this submittal. Please call if you have
any questions.
Sincerely,
Owen A�yree's_ & Associates, Inc.
Chris Carlson, E.I.T.
ivil En
gin r
Scott Que n, P.E.
Civil Engineer
CC/SQ/sp
Enclosure
Owen Ayres & Associates, Inc.
Engineers/Scientists/Surveyors
oc
3665 JFK Parkway, Building 2, Suite 300, P.O. Box 270460, Fort Collins, CO 80527 c:\data\wp51\jpilet.d
(970) 223-5556, Denver Metro (303) 572-1806, FAX (970) 223-5578 34-0276.00
Printed on recycled paper
FINAL GRADING AND DRAINAGE REPORT
FOR
JEFFERSON COMMONS PUD
Prepared for
JPI Texas Development
P.O. Box 619208
Dallas, Texas 75261-9208
AVMmS
ASSOCIATES
P.O. Box 270460
Fort Collins, Colorado 80527
(970) 223-5556, FAX (970) 223-5578 AVMS
ASSOCIATES