HomeMy WebLinkAboutPROSPECT INDUSTRIAL PARK, LOT 15 - PDP - 28-98 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT�3)
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the high point to the Northwesterly comer of Lot 15
Lot 15 is Q2yr=20.1 c.f.s. and Q100yr-106.6 c.f.s.
c.f.s. at 7 inches over crown.
EROSION CONTROL:
. The rate of runoff at the Northwesterly comer of
The capacity of the street cross section is 102.5
The site is located in a moderate wind erodibility zone and in a high rainfall erodibility zone.
A silt fence will be required around the perimeter of the site prior to beginning any overlot grading.
Immediately after grading, the concrete building foundation will be installed and gravel roadbase shall be
placed in the driveways and parking areas. This roadbase shall be thick enough to handle construction
traffic without failure.
This is a fairly small site and it will be very busy during building construction so vegetative plantings
will not be done until the building and paving procedures are nearing completion.
Wind erosion control on the site will be provided by the silt fence, building foundation and gravel
roadbase.
All erosion control procedures shall comply with the City of Fort Collins Criteria.
The stormwater runoff calculations, the Grading, Drainage and Erosion Control Plan and the overall
Utility Plan of Prospect Industrial Park showing the stormwater flows in Midpoint Drive are enclosed as
part of this report.
This drainage report and the design of the drainage system for Lot 15 are in compliance with the
City of Fort Collins Storm Drainage Specifications and Criteria. If you have any questions regarding
this report, please call.
Sincerely, v'""
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Richard A. Rutherford, P. . & L.S. lfl- _ -le
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July 2, 1998
Mr. Basil Hamdan
Storm Water Utility
City of Fort Collins
P.O. Box 580
Fort Collins, CO 80522-0580
Dear Basil,
The following is the Final Drainage Report for Lot 15, Prospect Industrial Park, City of Fort
Collins, County of Larimer, State of Colorado. The site is in the Poudre River Basin and contains
1.3724 acres. The existing site slopes from Northwest to Southeast at an approximate slope of 0.7%.
The site has a very good ground cover of grass and weeds.
It is proposed to divide Lot 15 into two new lots which each will have an office/warehouse building.
The site will be phased with Lot 15-A being Phase I and Lot 15-B begin Phase H.
The site is within approximately 1100 feet of the Cache La Poudre River. Due to this close
proximity to the River, it is proposed to not have storm water detention on site. The runoff from the
basin enters the outfall system to the River at the existing inlets at the comer of Midpoint Drive and
Sharp Point Drive. The Westerly inlet is only 450 feet Southeasterly of the Southwest comer of Lot 15.
The two inlets drain in a 24 inch R.C.P. to an existing gravel pit which drains into the Cache La Poudre
River.
The stormwater will be carried in the on -site curb and gutter to the two driveways where it will
enter the Northeasterly gutter of Midpoint Drive at both driveways on the site. The Phase I Building is
Developed Basin-1 and the developed runoff rates for it are Q2yr=1.93 c.f.s. and Q100=6.70 c.f.s. The
second phase is Developed Basin-2 and the developed runoff rates for it are Q2yi=1.56 c.f.s. and Q100
yr = 4.68 c.f.s.
There is not any appreciable stormwater runoff entering this site from off site. Lots 10 & 11 which
are adjacent to the rear of Lot 15, drain Southeast onto Lots 13 & 14. Lot 16 has not been developed
at this time and some of its historic runoff will sheet flow onto D.B.-1 and D.B.-2. The grading on both
basins will accomodate the off -site flow through each basin to Midpoint Drive.
There was some concern at the conceptual review meeting regarding the capacity of Midpoint Drive
to carry the stormwater runoff that discharges into it. The flow in the Midpoint Drive South and
Southwesterly gutter form Timberline Road to the North line of Prospect Industrial Park is diverted to
the East in a pan across Midpoint Drive and then to an existing pond in the Prospect East Industrial
Park. The North and Northeast gutter of Midpoint Drive flows into the Specht Point Road, Prospect
Parkway and the above described pan. There is a high point in Midpoint Drive 110 feet South of the
bran at the North line of Prospect Industrial Park. The pan crosses at the Southeast comer of the
existing Larimer County Jail property. Therefore, 1200 feet of Midpoint Drive is carrying runoff from
FINAL DRAINAGE REPORT
FOR
LOT 15, PROSPECT INDUSTRIAL PARK
POUDRE RIVER BASIN
PREPARED FOR
DOHN CONSTRUCTION, INC.
PREPARED BY
STEWART & ASSOCIATES
103 SOUTH MELDRUM STREET
FORT COLLINS, CO 80521
TEL. 970-482-9331
FAX. 970-482-9382