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FINAL DRAINAGE REPORT
FOR
THE MARKET PLACE
LOCATED AT
SOUTH COLLEGE AVENUE AND
TROUTMAN PARKWAY
FORT COLLINS, COLORADO
REVISED 1/2/90
TO BE DEVELOPED BY:
ROSENBAUM/DEAN
COLORADO SPRINGS, COLORADO
PREPARED BY: PARSONS & ASSOCIATES
432 Link Lane Plaza
Fort Collins, CO 80524
(303) 221-2400
PROJECT NO. 89.07 ROS
PARSONS &
ASSOCIATES
77
CONSULTING ENGINEERS 1
j anuary 2, 1990
Mr. Glen Schlueter
Storm Water Utility
City of Fort Collins
P.O. Box 580
Fort Collins, Colorado 80522
RE: The Market Place P.U.D.
Dear Glen:
A Checker Auto Parts store is being proposed for Pad A (Lot
3) of the Market. Place P.U.D.
As shown on the revised grading and drainage plan, the
building area has increased by 780 square feet from the original
building footprint shown on our previous submittal of 10/19/89.
Because a run-off coefficient of 1.0 was used for Basin A-i, this
change will have no effect on the drainage calculations.
The site play: for the Checker Auto Parts store as prepared
by the architects, Yergensen, Obering, & Wittaker, P.C., conforms
to the Drainage Plan of this submittal. Included in Yergensen,
Obering, & Wittaker's site plan is provision for all roof
drainage to flow into Basin A-1.
if you have any questions, or need additional information,
please call our office at your earliest convenience.
Sincerely yours,.
Donald M. arsons, P.E.
Colorado License #13131
DMP/cd
• 432 Link Lane Plaza Ft. Collins, Colorado 80524 3 1- 4
TABLE OF CONTENTS
COVER LETTER
INTRODUCTION
SITE DESCRIPTION
HISTORIC DRAINAGE
MASTER DRAINAGE
DRAINAGE UNDER DEVELOPED CONDITIONS
CONCLUSIONS AND RECOMMENDATIONS
VICINITY MAP
CALCULATIONS
ENCLOSURE:
GRADING AND DRAINAGE PLAN
,70 PARSONS
In ASSOCIATES
CONSULTING ENGINEERS
October 19, 1989
Mr. Glen Schlueter
Storm Water Utilities
City of Fort Collins
P. 0. Box 580
Fort Collins, CO 80522
RE: The Market Place P.U.D.
Dear Glen:
Due to the changes requested by the owner, we have revised the final drainage
report for the Market Place that was approved by your office on 8/10/89.
The anchor tenant's desire to expand into a portion of the adjacent building
to the south has allowed a relocation of the loading dock, an area used for storm
water detention on the original plan (Basin B-1). As the grading and drainage
plan indicates, the dock has been replaced by a grass lined detention pond in a
newly formed landscaped area between the building and JFK Parkway.
The new pond exceeds the storage volume of that originally provided, and no
adjustment was made to the conservative coefficient of runoff used for this basin
in the approved report. Therefore, we believe this revision is a benefit to the
storm drainage system for the project.
Grades have been adjusted in the new vendor parking area and access drive south
of the loading dock to improve driveability and delivery functions (Basin A-5).
However, detention volumes have remained unchanged.
Downspout piping has been -added to accommodate the additional space occupied
by the anchor tenant and downspout piping as originally approved has been relocated
to connect to the interior roof drain system.
You will note that minor modifications have been made to the calculations on
page 13 and 14. However, release rates from the two affected basins remain as
previously approved.
Sincerely yo/s ,
14- z
Donald M. Persons, P.E.
DMP/nc
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FINAL DRAINAGE REPORT
FOR THE MARKET PLACE
FORT COLLINS, COLORADO
INTRODUCTION
This drainage investigation has been performed for the
purpose of providing design information for the development of a
proposed commercial shopping center to be located at the Northeast
corner of the intersection of South College Avenue and Troutman
Parkway, Fort Collins, Colorado. The City of Fort Collins "Storm
Drainage Design Criteria and Construction Standards" was used as a
basis for guidelines and criteria throughout this investigation.
SITE DESCRIPTION
The study area is situated in the Southwest Quarter of
Section 36, Township 7 North, Range 69 West of the 6th Principal
Meridian, City of Fort Collins, Larimer County, Colorado. The
site is bounded by: South College Avenue on the West; the
Fountainhead P.U.D. on the North; the JFK Parkway on the East; and
Troutman Parkway on the South. A small parcel of land located at
the Northwest corner of JFK Parkway and Troutman Parkway, known as
Superblock Holding, is excluded from this development. This phase
of development' contains approximately 8 acres. The area is
presently undeveloped and used for three residential acreages with
the major portion of the property being vacant. The topography of
the site slopes from Northwest to Southeast at grades varying from
0.5% to 2%. The site is predominantly covered with grasses and
native vegetation.
HISTORIC DRAINAGE
Prior to the construction of the streets bounding the site on
the east and south, the Larimer No. 2 Canal formed the easterly
boundary of these lands. The No. 2 Canal was reconstructed and
relocated as a part of the Heart Special Improvement District.
Prior to this construction the area drained into .the No. 2 Canal.
The Heart Special Improvement District installed storm drainage
pipes onto the properties at the intersection of Troutman Parkway
and JFK Parkway. The construction was performed in accordance
with an agreement between the City of Fort Collins and the Larimer
County Canal No. 2 Irrigation Company whereby the Ditch Company
allowed the City to discharge stormwater into the No. 2 Canal.
MASTER DRAINAGE .
The site has been considered in several previous drainage
studies in this area. The "McClelland's Mail Creek" Basin is the
City's designated master plan basin in which this site is located.
The site has not been studied to any detail within this Basin
Master Plan. An investigation for the area to the Northreporand East
was prepared by Cornell Consulting Company.
This"Master Storm Drainage Report For The Landings P.U.D.the
2. It was
recommended in this report that the area above the No. 2 Canal be
allowed to develop and detain stormwater on -site and to release
run-off at the 2-year historic rate into the No. 2 canal. •A
subsequent report prepared by Engineering Professionals, Inc. for
the Heart Special Improvement District recommends that in
conjunction with the reconstruction and relocation of the No. 2
Canal, as a part of the S.I.D., that the rate of discharge into
the canal be limited to 0.87 cfs/acre. The storm drainage pipes
that were, installed to serve the properties were sized on that
basis. This site is a portion of Basin A (6.12 acres of 9.96) and
a portion of Basin B (1.85 acres of 6.14) as defined by the Heart
S.I.D. Flows from those portions of Basin A & B north of this
site have been calculated using 0.87 cfs per acre and passed
through the Market Place drainage system. (2.83 cfs for Basin A,
3.51 cfs for Basin B)
Additionally, 7.6 cfs from the Fountainhead P.U.D. will be
allowed through this site and discharged to the No. 2 canal.
DRAINAGE UNDER DEVELOPED CONDITIONS
This site is proposed to be a retail shopping center with
perimeter pads for food service and other high traffic uses. The
majority of the site will be directed westerly to Basin A and
ultimately to the Troutman crossing, (7.405 ac.) and the remainder
of the site will be directed to the JFK Parkway Crossing. Flows
from Troutman Parkway and JFK Parkway will be released directly to
Canal No. 2, but detention has been provided on -site for those
adjacent portions of Troutman & JFK. The release rate used was
0.87 cfs per acre per the Heart S.I.D., and detention provided on -
site based on the difference between 100-year storm and 0.87
cfs/acre release rate. 60,000 cubic feet of detention is required
for this site.
No detention has been provided for flows from College Avenue.
However, these flows will overflow through the Market Place site
and ultimately drain to the Troutman crossing.*
Also, flows from
the 0.83 acres (Superblock Holding) were not considered, although
pipe stub -outs have been provided and capacity in the existing
system has been provided per the Heart S.I.D., allowing future
development of the site.
All easements for off -site, drainage structures as shown on
these plans are handled by separate document and not by the plat
of Market Place P.U.D.
CONCLUSIONS AND RECOMMENDATIONS
1.) The site is to be developed to retain the general drainage
pattern existing prior to development.
2.) All final design.and construction shall conform with the City
of Fort Collins "Storm Drainage Design; Criteria and
Construction Standards".
3.) On -site detention is to be provided with controlled release
rates that meet established criteria per Heart Special
Improvement District Final Drainage Report.
4.) The site is not located within an established floodway or
floodplain.
5.) The existing condition of the property to the north is such
that natural ponding is already in existence. Overflow of
that natural ponding occurs approximately at elevation 5031
per aerial topography of the site. Future development of
that property will require filling this low area to elevation
5031. The development of Market Place does not substantially
alter any drainage characteristics of the adjacent northerly
property and does provide drainage facilities to accommodate
future development of that property.
Prepared under the direct supervision of:
Donald M. Parsons, P. E. # 13131
*So some detention of flows from College Avenue will occur in all
situations except the 100-year storm, and even in the 100-year
event, the time of concentrations for College Avenue will be
increased.