HomeMy WebLinkAboutCHEROKEE FLYING HEIGHTS - PDP - 17-00 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFinal Drainage and Erosion Control Report for Cherokee Flying Heights
B. DRAINAGE CONCEPT
1. The proposed drainage design for Cherokee Flying Heights is effective for
the control of storm runoff with a considerable reduction in potential
downstream effects.
2. The proposed drainage design for Cherokee Flying Heights will have no
effect on City of Fort Collins Master Drainage Plan recommendations.
VIII. REFERENCES:
City of Fort Collins "Storm Drainage Design Criteria and Construction
Standards"; May 1984
City of Fort Collins "Erosion Control Reference Manual"; January 1991
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Final Drainage and Erosion Control Report for Cherokee Flying Heights
C. SPECIFIC DETAILS— EROSION CONTROL
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1. The following measures are specified on the Drainage and Erosion Control
I plan:
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a. A gravel inlet filter at curb opening at the low point in the street.
j b. Haybales in the swales.
i c. Silt fence on the downstream property lines, specifically the east
property line.
2. A water quality device will be installed at the outfall from the water quality
pond. Maintenance of the device will be the responsibility of the owner.
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D. EROSION CONTROL SECURITY DEPOSIT
1. An erosion control security deposit is required in accordance with City of
Fort Collins policy. In no instance shall the amount of the security be less
than $1000.00.
2. See the Erosion Control Security Deposit Requirements document located
in Appendix III.
3. The erosion control security deposit is reimbursable.
VII. CONCLUSIONS:
A. COMPLIANCE WITH STANDARDS
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1. All drainage analysis has been performed according to the requirements of
the City of Fort Collins Storm Drainage Criteria Manual.
2. Proposed drainage improvements generally conform to the
recommendations of the City of Fort Collins Master Drainage Plan.
3. Proposed erosion control measures conform to the recommendations of the
City of Fort Collins standards.
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VI. EROSION CONTROL AND WATER QUALITY:
A. GENERAL CONCEPT
1. Erosion control measures are specified on the Grading, Drainage and
Erosion Control plan.
2. Maintenance of erosion control devices will remain the responsibility of the
contractor and the owner until the project is complete.
3. A water quality pond will be constructed in the southeast corner of the site.
B. SPECIFIC DETAILS- WATER QUALITY
The required volume for the water quality pond is 2051 cubic feet. This is
based on a resultant impervious in sub -basin 1 of 64.94 percent.
2. The volume provided in the water quality pond is 5633 cubic feet up to the
top of the pond.
3. The top of the water quality pond is at an elevation of 72.0 feet. The invert
of the pond is at an elevation of 69.94 feet.
4. A water quality outlet device is specified on the plan set.
5. An overflow spillway is provided in the eastern portion of the berm to pass
any flows that exceed the capacity of the water quality outlet structure.
a. The overflow weir is set an elevation of 71.10 feet. The weir length is
10.0 feet. The weir is located on the north side of the water quality
device.
b. The maximum WSEL using the peak flow into the pond (11.51 cfs) is
71.68 feet. We have specified the lowest opening elevation on the unit
adjacent to the pond to be 1.5 feet above this or 73.18 feet.
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Final Drainage and Erosion Control Report for Cherokee Flying Heights
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4. Additional Right of Way is dedicated along the frontage of Cherokee
Flying Heights with this replat.
C. HYDROLOGICAL CRITERIA
1. The Rainfall -Intensity -Duration curves for the City of Fort Collins were
used (Figure 3-1, attached for reference), in conjunction with the "Rational
Method" for determining peak flows at various concentration points. The
revised figure 3.1 that was recently adopted by the City with Ordinance
No. 42 was utilized. A look up table with values taken from figures 3-la
j and b was used in the runoff calculations. A copy of these tables is included
in Appendix III.
2. The two (2) and one hundred (100) year storms were analyzed in
accordance with Table 3-1 of the City of Fort Collins Storm Drainage
Design Criteria Manual for residential sites.
D. HYDRAULIC CRITERIA
! 1. Storm sewer and drainage channel capacities are based on the Manning's
Equation. The Manning's coefficient is in accordance with the City of Fort
Collins Storm Drainage Criteria Manual.
2. Theoretical street capacities were determined using Haestads Flowmaster
software. The appropriate reduction factor was then applied to determine
the allowable capacity.
V. DRAINAGE FACILITY DESIGN:
A. GENERAL CONCEPT
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1. The historic flow patterns will be maintained with the development of this
site.
i2. Water quality will be provided in the southeast corner of the site by
constructing a water quality pond.
3. Stormwater will be conveyed through the site via a combination of
overland flow, swales and gutters.
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Final Drainage and Erosion Control Report for Cherokee Flying Heights
III. DRAINAGE BASINS AND SUB -BASINS:
A. MAJOR BASIN DESCRIPTION
1. The site is located within the West Vine Drainage Basin as defined on the
City of Fort Collins Master Stormwater Basin Map. The City is currently in
the process of updating the master plan for this basin.
2. The Basin fee rate for this basin is $7,004 per gross acre according to the
development fee section of the City of Fort Collins Development Manual.
B. SUB -BASIN DESCRIPTION
1. The site slopes from west to east. There is approximately 6 feet of fall from
the west property line to Taft Hill Road.
2. Historically, stormwater runoff from the site flows overland to the east into
Taft Hill Road and then north in Taft Hill Road.
3. Development of the site has divided the site into 2 sub -basins (1 and 2).
Sub -basin 1 contributes to the proposed water quality pond. Sub -basin 2
consists of Lot 1 and a portion of the entry road.
IV. DRAINAGE DESIGN CRITERIA:
A. REGULATIONS
1. Design Criteria from the City of Fort Collins Storm Drainage Design
Criteria Manual and options for storm drainage improvements discussed by
the City of Fort Collins were considered.
2. Erosion Control Criteria from the City of Fort Collins Criteria Manual was
used.
B. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS
1. The site is completely developed on all sides, creating grading constraints
for the entire perimeter of the project.
2. Water quality provisions are required for this subdivision.
3. No detention is required for this project.
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Final Drainage and Erosion Control Report for Cherokee Flying Heights
I. INTRODUCTION:
1. The site is an infill development within the City limits.
2. Development of the site will consist of replatting the existing 2 lots into a
pair of lots with different geometry. One of the proposed lots is for the
existing single-family residence on the site. The other lot is for the
proposed condominiums that will be constructed with this replat.
II. GENERAL LOCATION AND DESCRIPTION:
A. LOCATION
1. The Cherokee Flying Heights is located in the southeast quarter of section
9 Township 9 North Range 69, West, Fort Collins, Colorado.
2. More specifically, it is located approximately 1375 feet (1/4 mile) north of
the intersection of Mulberry Street and Taft Hill Road on the west side of
Taft Hill Road.
3. The site is bounded on the south, west and north by other residential
subdivisions, including the rest of M & G Subdivision and Tenth Green
.Second Filing. North Taft Hill Road adjoins the site on the east.
B. DESCRIPTION OF PROPERTY
1. Development of the site will consist of the construction of 5 condominium
buildings with varying numbers of condominiums in each building. Each
building will be located on an individual lot. There will be a total of 31
condominiums built with this project.
2. The site has a net area of approximately 1.88 acres.
3. There is an existing residence on the property. The location where the
existing residence is will be the exception to this replat. The condominium
units will be constructed on Lot 1-5 within the limits of the replat. The area
outside the limits of the 5 lots will be dedicated as a Public Access, Utility
and Drainage Easement. There are also some existing foundations on the
site that will be removed as part of the development.
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Final Drainage and Erosion Control Report for Cherokee Flying Heights
TABLE OF CONTENTS
I. INTRODUCTION: ....................................................................................................................... 3
H.
GENERAL LOCATION AND DESCRIPTION: ........................................................................ 3
A.
LOCATION..................................................................................................................................3
B.
DESCRIPTION OF PROPERTY........................................................................................................3
III.
DRAINAGE BASINS AND SUB -BASINS: ............................................................................
4
A.
MAJOR BASIN DESCRIPTION........................................................................................................4
B.
SUB -BASIN DESCRIPTION............................................................................................................4
IV.
DRAINAGE DESIGN CRITERIA: ........................................................................................
4
A.
REGULATIONS............................................................................................................................4
B.
DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS............................................................4
C.
HYDROLOGICAL CRITERIA..........................................................................................................5
D.
HYDRAULIC CRITERIA.................................................................................................................5
V.
DRAINAGE FACILITY DESIGN: .............................................................................................
5
A.
GENERAL CONCEPT....................................................................................................................5
VL
EROSION CONTROL AND WATER QUALITY: ...............................................................
6
A.
GENERAL CONCEPT....................................................................................................................6
B.
SPECIFIC DETAILS - WATER QUALITY.........................................................................................6
C.
SPECIFIC DETAILS - EROSION CONTROL ......................................................................................7
D.
EROSION CONTROL SECURITY DEPOSIT.......................................................................................7
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VII.
CONCLUSIONS: .....................................................................................................................
7
A.
COMPLIANCE WITH STANDARDS..................................................................................................7
B.
DRAINAGE CONCEPT...................................................................................................................8
VIII.
REFERENCES: .......................................................................................................................
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APPENDIX I — Drainage Calculations
APPENDIX II — Erosion Control
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APPENDIX III — Charts and Figures
APPENDIX IV — Stuffer Envelope
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Final Drainage and Erosion Control Report
For
KEROKEE FLYING HEIGHTS
it of Lots 1 and 2, except the north 51 feet of the east 125 feet of said lot 2,
M. and G. Subdivision
Fort Collins, Colorado
Prepared for:
Mike Jensen
1212 South College Avenue
Ft. Collins, Colorado 80524
Prepared by:
Shear Engineering Corporation
Project No: 1760-01-00
Date: May 2000
AQV' c r„uP,,. cnitp 79 Fr Cnllins. CO 80525
PRINT DATE
MAY 9 2000
SHEAR ENGINEERING CORP
(970) 226-5334 FAX (970) 282-0311