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"pir'RTY OF
FINAL DRAINAGE &
EROSION CONTROL REPORT
FOR
COOK COURT (Minor Subdivision)
FORT COLLINS, COLORADO
OCTOBER 12, 1993
PREPARED BY:
CAMPANA INCORPORATED
DAN EVANS AND GINO CAMPANA
1404 W. MOUNTIAN AVENUE
FORT COLLINS, COLORADO 80521
(303)490-1939
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TABLE OF CONTENTS
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Introduction
Site Description
Ffistoric Drainage
• Drainage Criteria
Drainage Under Developed Conditions
Erosion Control
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Conclusions and Recommendations
References
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1
1
1
3
3
3
4
6
Figure 1 Vicinity Map 2
Figure 2 Drainage Schematic sheet A
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FINAL DRAINAGE &
EROSION CONTROL REPORT
FOR
COOK COURT (Minor Subdivision)
FORT COLLINS, COLORADO
Introduction
This drainage report has been prepared along with final engineering drawings to provide
design information for the development of 2 single-family residences in proximity to Cook Drive
near the New Mercer Canal. This report was prepared in conformance with the City of Fort
Collins Storm Drainage, Design Criteria and Construction Standards (Reference 1).
Site Description
Cook Court is a 1.556 acre parcel of land located off of Cook Drive along the south side
of the New Mercer Canal(See Figure 1). More specifically the property is located in the
northwest comer of Section 12, Township 7 North, Range 69 West of the 6th Principal Meridian,
City of Fort Collins, County of Larimer, State of Colorado (Reference 3).
Historic Drainage
The historic land use of this site has been a vacant lot with a northeasterly slope of 3% .
All historic drainage from this site flows -into the New Mercer Canal. Runoff from surrounding
lots to the west flow around this site. The low flow runoff to the south is diverted to the south of
the site by an existing swale along the south side property line. The higher runoff flows to the
south, flow over the swale and onto this site This site is located in the Canal Importation
Drainage Basin
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Design Criteria
The Rational Formula as identified in The City of Fort Collins Storm Drainage Design
Criteria Manual is used to calculate the runoff from this site. The Rational Method is widely
accepted as a method for predicting runoff from basins of less than 200 acres. Manning's
Equation was used to identify the capacity of all channels and street gutters. All coefficients,
nomographs and design values used in this report were provided from The Fort Collins Storm
Drainage Design Criteria Manual. (Reference 1)
Drainage Under Developed Conditions
The development of 2 3/4-acre lots will not significantly increase the runoff in this area.
The majority of runoff from this site will follow the historic drainage pattern. The site is made up
of one basin with runoff characterized as overland flow travelling into the New Mercer Canal.
Off -site flows from the west flow around the site flow into the New Mercer Canal. The existing
swale along the south property line will be rehibilitated sufficient to. divert the historic 100-year
flow to the east into the New Mercer Canal (see Drainage Plan).
Erosion Control
Because only one home will be constructed, a majority of the site will be left undisturbed.
Therefor we will not submit a erosion control plan and would suggest a variance to the erosion
control deposit.
Wind Erosion
This site is located in an area designated as having moderate wind erosion potential. The
existing native grasses provide adequate ground cover for the site in its natural state. By field
inspection, there appears to be minimal evidence of wind erosion. The perimeter of this site is
surrounded by trees, houses and fences which provide above adequate,wind protection.
Water Erosion
This site is located in an area designated as having a moderate potential for erosion due to
stormwater runoff. Since the majority of this site will not be disturbed during construction no
seeding and mulch is needed. All disturbed areas will be covered by houses, driveways, or lawns.
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Conclusions and Recommendations
After reviewing the existing drainage information available in this area and surveying the
existing site conditions, we present the following recommendations.
There will be minimal overlot grading with existing drainage pattern
remaining unchanged. Therefore, no erosion protection is required.
2. No designated floodplains are located on this site.
3. The New Mercer Ditch Company has given the developer permission to discharge
stormwater runoff into the New Mercer Canal.
4. The historic runoff will not change enough to necessitate a detention facility.
1511
REFERENCES
1. Storm Drainage Design Criteria and Construction Standards, City of Fort Collins, May
1984.
2. Urban Storm Drainage Criteria Manual, Urban Drainage and Flood
Control District, March 1969.
3. Topography, Northeast Quarter Section 13, Township 6 North, Range 69 West, Arix,
April 23, 1981.
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APPENDIX
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*MOST FREQUENTLY OCCURRINGuUNDEVELOPED"
LAND SURFACES IN THE DENVER REGION.
REFERENCE: -Urban Hydrolog§ For Small Watersheds" Technical
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Release No. 55, USDA, SCS Jan. 1975.
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URBAN DRAINAGE d FLOOD CONTROL DISTRICT
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Resource Consultants & Engineers, Inc., 3665 JFK Pkwy, Bldg 2, Ste 300 / P.O. Box 270460, Fort Collins, CO 80527
(303) 223-5556, Denver Metro (303) 572-1806, Fax (303) 2235578
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(303) 223NW
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Hesource consultants & Engineers, Inc., 3665 JFK Pkwy, Bldg 2, Ste 300 / P.O. Box 270460, Fort Collins, CO 80527
(303) 223-5556, Denver Metro (303) 572-1806, Fax (303) 223-5578