HomeMy WebLinkAboutPOUDRE FIRE AUTHORITY STATION #14 - PDP - 14-02 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTi
' implemented during construction. Silt fence shall be installed along the southern and
_ eastern sides of proposed site. Also, vehicle -tracking pads shall be installed at the three
' entrances to the site to control the mud being tracked onto the existing pavement. During
overlot grading, disturbed areas are to be kept in a roughened condition and watered to
' reduce wind erosion.
5.3 Dust Abatement
During the performance of the work required by these plans, the contractor shall carry out
proper efficient measures wherever and as necessary to reduce dust nuisance, and to
prevent dust nuisance, which has originated from his operations from damaging crops,
orchards, cultivated fields and dwellings, or causing nuisance to persons. The Contractor
will be held liable for any damage resulting from dust originating from his operations
under these plans, on right-of-way or elsewhere.
5.4 Tracking Mud
Wherever construction vehicles access routes intersect paved public roads, provisions
' shall be made to minimize the transport of sediment (mud) by runoff or vehicles tracking
onto the paved surface. A stabilized construction entrance is required per the detail
' shown on the Detail Sheet with base material consisting of 6" coarse aggregate. The
contractor will be responsible for clearing tracked mud on a daily basis.
5.5 Maintenance
All temporary and permanent erosion and sediment control practices must be maintained
and repaired as needed to assure continued performance of their intended function. Silt
fences will require periodic replacement. Maintenance is the responsibility of the
contractor.
6. CONCLUSIONS
6.1 Compliance with Standards
All computations that have been completed within this report are in compliance with the
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channel and enters Carmichael (Basin 3) through a metal sidewalk culvert.
' Basin 3 contains the eastern portion of the site including the west half of Carmichael
along the site frontage. This basin accepts runoff from Basins 1 and 2 and conveys the
flow south to an inlet and storm system that conveys the runoff to the detention area
discussed above.
The overall 2 year c-value for Basins 1, 2 and 3 is 0.66 and the overall 100 year c-value is
0.83. This meets the criteria set forth in the previous study and no further analysis of the
downstream facilities was completed.
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4.3 Drainage Summary
The storm conveyance system is a surface and sub -surface system and has been designed
for minimal maintenance. The proposed storm sewer system (outlet structure and pans)
and the detention pond will be owned and maintained by the property owners. The
existing storm system shall be maintained by the City of Fort Collins or other responsible
parties.
1 4.4 Variance Requests
No variances are being requested at this time.
5. EROSION CONTROL
5.1 General Concept
This site lies within the Moderate Rainfall and Wind Erodibility Zone per the City of Fort
Collins Zone Maps. A potential exists for silt movement from the site to be transported
into the existing ponds located to the south of the site. All erosion control measures
necessary to minimize sediment transport have been shown on the Erosion Control Plan.
5.2 Specific Details
To limit the amount of silt leaving the site, several erosion control measures shall be
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t' report. Standard Form 8 (SF-8) provides time of concentration calculations for all sub -
basins. Standard Form 9 (SF-9) provides a summary of the design flows for all Sub -
basins and Design Points associated with this site.
3.4 Hydraulic Criteria
All hydraulic calculations within this report have been prepared in accordance with the
City of Fort Collins Drainage Criteria and are also included in Appendix B of this report.
1 4. DRAINAGE FACILITY DESIGN
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4.1 General Concept
The runoff from this site is split by the proposed building and will flow east on each side
of the building in the parking lots via pans, curb & gutter and concrete channels to
Carmichael Street. The flow will be conveyed to the detention pond (SB 91) that was
sized to accept undetained runoff from this site.
4.2 Specific Flow Routing
This site is a portion of Basin 71 in the overall Westchase P.U.D. Basin 71 contains 7.55
acres and is limited to a 2-year c-value of 0.70 and a 100-year c-value of 0.88. A portion
of Basin 71 is analyzed with this report and the c-value limitation was applied to the
portion analyzed. A summary of the drainage patterns within each basin is provided in
the following paragraphs. For more specific details see the calculations located in
Appendix B of this report.
Basin 1 contains the north portion of the site including the north half of the building, the
drive area on the north side of the building, the parking lot on the north side of the
building and a portion of the landscaped area. Runoff from this basin flows to the east in
pans to a concrete channel and enters Carmichael (Basin 3) through a metal sidewalk
culvert.
Basin 2 contains the south portion of the site including the south half of the building and
parking, drives and landscaping on the south side of the building. and a portion of the
drive areas. Runoff from this basin flows to the east in pans and curb to a concrete
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criteria established in the Final Drainage Report for Westchase P. U.D. Detention and
water quality are provided for this site in the ponds south and east of this site. The site
taccepts no runoff from the adjacent streets on the west, north and east and will discharge
to Carmichael Street along the eastern boundary of the site.
3. DRAINAGE DESIGN CRITERIA
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3.1 Regulations
This report was prepared to. meet or exceed the "City of Fort Collins Storm Drainage
Design Criteria Manual' specifications. Where applicable, the criteria established in the
"Urban Storm Drainage Criteria Manual" (UDFCD), 1984, developed by the Denver
Regional Council of Governments, has been used.
3.2 Development Criteria Reference and Constraints
The runoff from this site and the allowable release rate has been routed to conform to
existing drainage reports completed that have included this area.
The streets and associated drainage systems surrounding the site are existing. There is no
storm system adjacent to this site and therefore, the site will discharge directly to the
street. The runoff will flow south in Carmichael to an inlet and into a storm system that
will carry the flow to the detention area.
Detention is provided for this site in the detention ponds up to a 2-year c value of 0.70
and a 100-year c value of 0.88. The site meets this criteria and therefore will not provide
any onsite detention. Runoff from the site was calculated based on the rainfall criteria
adopted by the City of Fort Collins on March 26, 1999.. Water quality measures will also
be provided downstream in the form of extended detention.
3.3 Hydrologic Criteria
Runoff computations were prepared for the 2-year minor and 100-year major storm
frequency utilizing the rational method.
All hydrologic calculations associated with the basins are included in Appendix B of this
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1.
2.
GENERAL LOCATION AND DESCRIPTION
1.1 Location
This site is located in Block 11 of the Westchase P.U.D. in the Southwest Quarter of
Section 8, Township 6 North, Range 69 West of the Sixth Principal Meridian, in the City
of Fort Collins, County of Larimer, State of Colorado. See the location map in Appendix
A.
The project is located east of Timberline Road, north of Trilby Road and south of
Westchase Road. The site is bounded by residential development on the east and north
boundaries and by future church site on the south boundary.
1.2 Description of Property
The entire project consists of 0.88 acres of land. The land is currently undeveloped and
slopes to the southeast at approximately 1.5%. The runoff from the site currently enters
the adjacent street and is conveyed to a detention pond.
The project will consist of a single structure which will be a fire station with bay doors
and associated drives and parking area. The site will access from the existing Westchase
Road on the north and a proposed private access on the south that will connect from
Timberline Road to Carmichael Street.
DRAINAGE BASINS AND SUB -BASINS
2.1 Major Basin Description
The proposed development lies within the Fossil Creek Reservoir Drainage Basin. The
site is included in the area covered by the Final Drainage Report for Westchase
P. U.D..by David Evans and Associates dated December 14, 2000. Portions of this report
are included in Appendix E.
2.2 Sub -basin Description
This site is included in Basin 71 of the Westchase P.U.D. The site is restricted to the
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TABLE OF CONTENTS
TABLEOF CONTENTS.............................................................................................................................iii
1.
GENERAL LOCATION AND DESCRIPTION
1.1 Location...............................................................................................................................1
1.2 Description of Property........................................................................................................
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2.
DRAINAGE BASINS AND SUB -BASINS
2.1 Major Basin Description......................................................................................................
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2.2 Sub -Basin Description.........................................................................................................1
3.
DRAINAGE DESIGN CRITERIA
3.1 Regulations..........................................................................................................................2
3.2 Development Criteria Reference and Constraints................................................................2
3.3 Hydrologic Criteria..............................................................................................................2
3.4 Hydraulic Criteria................................................................................................................3
4.
DRAINAGE FACILITY DESIGN
4.1 General Concept..................................................................................................................3
4.2 Specific Flow Routing....................................................................................
....................3
4.3 Drainage Summary ..............................................................................................................4
4.4 Variance Requests...............................................................................................................4
' 5.
EROSION CONTROL
5.1 General Concept..................................................................................................................4
5.2 Specific Details.....................................................................................................................4
5.3 Dust Abatement...................................................................................................................5
5.4 Tracking Mud......................................................................................................................5
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5.5 Maintenance........................................................................................................................
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6.
CONCLUSIONS
6.1 Compliance with Standards................................................................................................5
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6.2 Drainage Concept................................................................................................................
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6.3 Water Quality and Erosion Control Concept.......................................................................6
' 7.
REFERENCES.................................................................................................................................6
' APPENDICES
A Vicinity Map
B Hydrologic Computations
C Erosion Control Calculations
D Figures and Tables
E Excerpts from Previous Reports
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11 North Star
rl*am., design, inc.
U
March 12, 2002
Basil Hamdan
City of Fort Collins Stormwater
700 Wood Street
Fort Collins, CO 80522-0580
RE: Final Drainage Report for Westchase P.U.D. Block 11, Lot 1
Poudre Fire Authority Station #14
Dear Basil,
I am pleased to submit for your review and approval, this Final Drainage & Erosion Control
Report for Westchase P.U.D. Block 11, Lot 1, Poudre Fire Authority Station #14. I certify that
this report for the drainage design of Poudre Fire Authority Station #14 was prepared in
accordance with the criteria in the City of Fort Collins Storm Drainage Manual.
I appreciate your time and consideration in reviewing this submittal.. Please call if you have any
questions.
aPatricia, E.
North Star Design, Inc.
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700 Automation Drive, Unit I Windsor, Colorado 80550
970-686-6939 Phone 9 970-686-1188 Fax
FINAL DRAINAGE AND
EROSION CONTROL REPORT
WESTCHASE P.U.D. BLOCK II, LOT 1
POUDRE FIRE AUTHORITY STATION #14
Prepared for:
Poudre Fire Authority
102 Remington Street
Fort Collins, CO 80526
Prepared by:
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, Colorado 80550
Ph# (970) 686-6939
Fax# (970) 686-1188
March 12, 2002
Job Number 114-22
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VICINITY MAP
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APPENDIX A
VICINITY MAP
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City of Fort Collins Storm Drainage Design Criteria Manual.
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6.2 Drainage Concept
' The proposed drainage concepts presented in this report and on the construction plans
adequately provide for the transmission of developed on -site runoff to the storm system in
Carmichael and to the detention area downstream. The impact of the development of this
_ site on downstream facilities has been accounted for in the previous drainage report for
' the overall Westchase P.U.D. Imperviousness of the site was restricted to meet the
criteria set forth in the Final Drainage Report for Westchase P. U.D.
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If, at the time of construction, groundwater is encountered, a Colorado Department of
Health Construction Dewatering Permit would be required.
6.3 Erosion Control Concept
Since the site is less than 5.0 acres, a NPDES permit is not required. During
' construction, erosion control shall be maintained to minimize erosion on this site and
transport of silt downstream.
7. REFERENCES
1. City of Fort Collins, "Storm Drainage Criteria Manual", (SDCM), dated March, 1986.
2. The Final Drainage Report for Westchase P. U.D..by David Evans and Associates
dated December 14, 2000.
3. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated March, 1969, and Volume 3 dated September,
1992.
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