HomeMy WebLinkAboutDrainage Reports - 11/02/1993FINAL STORM DRAINAGE REPORT 6/ S•U.
FOR
A BIG A STORAGE P.U.D.
SroRP EgT�RAFVI
WITH R SV W Cppv
A[
NOVEMBER 2. 1993
R
STEWART & ASSOCIATES, INC.
103 SOUTH MELDRUM STREET
FORT COLLINS, COLORADO 80521
303/482-9331
STEWART&kSSOCIATES
Consulting Engineers and Surveyors
November 2, 1993
Storm Water Utility
City of Fort Collins
P.O. Box 580
Fort Collins, Colorado 80522
Gentlemen:
The following is the storm drainage report for the proposed A Big A
Storage .P.U.D. It is located in Lot 3, Bank Center Square, First Filing.
It is in the Northeast 41 of Section 23, Township 7 North, Range 69 West of
the 6th P.M. The site contains 1.99 acres. It is bounded on the north by
the Sherwood Ditch; on the east.by the Kelly —Moore Paint Store; on the south
by existing commercial buildings, including Montgomery Ward & Co.; and on the
west by the Burlington Northern Railroad. The site is in the Spring Creek
Drainage Basin.
The site has been approved twice before for development. It was approved
in May 1978 for a warehouse and retail use and again in August 1982 for a
skating rink. The onsite stormwater detention pond that was approved in 1982
was constructed along with the 6—inch corrugated metal outfall pipe into the
Sherwood Ditch.
The A Big A Storage P.U.D. is a proposal for a two—phase self —storage
planned unit development. Phase I will have four buildings, including an
office. The site slopes from south to north at a moderate slope for
approximately 200 feet and then slopes steeply down to the Sherwood Ditch.
There are two offsite sub —basins south of the site which also flow northerly
through the P.U.D. The University Mall, including the Montgomery Ward & Co.
property, lies south of the two offsite basins, and that property drains
easterly to South College Avenue.
It is proposed to continue to drain the property northerly to two area
inlets which will discharge into the existing detention pond. We will also
use the existing 6—inch discharge pipe into the Sherwood Ditch. A restriction
plate will be placed on the 6—inch outlet pipe to restrict the outlet to 1.15
c.f.s.
The required detention volume, based on the mass diagrams for both the
S onsite 1.99 acres (Sub —Basins A, ( " " "B" "C" and "D") and a portion of the
offsite Sub —Basin "F", is 22,788 cubic feet. The pond will be expanded to
a volume of 22,861 cubic feet. The pond was approved by the City of Fort
Collins in May 1978 for the area that is proposed now, and the southwest
James H. Stewart
and Associates, Inc.
103 S. Meldrum Street
P.O. Box 429
Ft. Collins, CO 80522
303/482-9331
Fax 303/482-9382
A Big A Storage P.M.
Page 2
building was built at that time. The southeast building (Taylor Rental) was
constructed in the early 1960's. It was approved again in August 1982 when
there was a proposal for a skating rink on the land now proposed for A Big
A Storage P.U.D. The pond was built in 1982. Copies of the calculations from
1982, the grading plans from 1978 and 1982, and the agreement for the pond
are included as part of this report. The required pond capacity that was
approved in 1978 was 15,876 cubic feet; however, the enclosed mass diagram
for the onsite parcel would require 15,876 cubic feet to detain the difference
between the historic tw4year runoff and the 100—year developed runoff. The
mass diagram for the existing southwest offsite building would require 6,912
cubic feet to detain the difference between the two—year historic runoff and
the 50—year developed runoff. The combined allowable release rate is 1.15
c.f. s.
EROSION CONTROL:
The site is in a high. rainfall erodibility zone and a moderate wind
erodibility zone. The site has a good ground cover of grass and weeds. None
of the steep bank down to the Sherwood Ditch will be disturbed. A curb is
being constructed along the north side of the access drive which will preclude
runoff to sheet flow .down the steep bank. The present ground cover protects
the bank very well. _DD-ly Phase I will be disturbed during its construction.`
The Phase II area w>>> ho—+4_-+ _on_ v urino 1 s construction.
A silt fence will be placed along the top of the bank along the entire
northerly line. It will remain in place during the entire construction period.
Straw bales will be placed at the two area inlets as soon as the discharge
pipes are constructed. After the driveway is paved, the area inlets will be
protected by rock filters. If any area in Phase II or the pond area is
disturbed, it will be reseeded.
The stormwater calculations, grading and drainage plan and the erosion
control calculations are included as a part of this report.
To the best of my knowledge, this report.and the drainage plans conform
to the City of Fort Collins Storm Drainage criteria. If you have any questions
regarding this report, please call.
Sincerely,
�,o�p A. RUTh
Richard A. Rutherford, P. & L.S. .•��tisrf%P'•
President �` �<
Jrr 5028
enclosures
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STEWART&SSOCIATES 103 S. MEL933DRUM1, FORT COLLINS, CO 80521
PH. 482-FAX 482-9382
Consulting Engineers and Surveyors
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Consulting Engineers and Surveyors
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PH. 482-9331 FAX 482-9382
By: P, A P. Date: 9/7/,-7--1 Client: I A W A 7 IS P- r f) A) Sheet No. S- of
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STEWART& SSOCIATES 103 S. 938 RUM,FAX FORT gOLLINS, CO 80521
Consulting Engineers and Surveyors
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PH.482-92
Consulting Engineers and Surveyors
By: ±' !'. Date: 1 z _ 3 Client: . j Ai AT' P.sSheet No. 73.of
Project: A B I c: A P
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COUSTRUCTIOU SEQUEfICE
PROJECT:A
Bf6
Sro A P(Jb
STANDARD FUIlh1 C
SEQUENCE.
FOR 19
93
UNLY. COMPLETED BY: ,eA0
DATE: 9/7 /93
Indicate
Major modifications
by use
of a
bar line or symbols when erosion control measures will be installed.
to
approval by. the City
an approved schedule may require submitting
Engineer.
a new schedule for
YEAR
MONTH
-------------I------
OVERLOT GRADING
41II10 EROSION CONTROL
Soil Roughing
Perimeter Barrier
Additional Barriers
Vegetative Methods
Soil Sealant
Other
B Ulf_ DIN (.
RAINFALL EROSION CONTROL
STRUCTURAL:
Sediment Trap/Basin
Inlet Filters
Straw Barriers
Silt Fence Barriers
Sand Bags
Bare Soil Preparation
Contour Furrows
Terracing
Asphalt/Concrete Paving
Other
BUf1-v.N&
VEGETATIVE:
Pennanent Seed Planting
Mulching/Sealant
Temporary Seed Planting
Sod Installation
Nettings/Hats/Blan.kets
Other
-----------------------------
STRUCTURES: INSTALLED BY
VEGETATION/MULCHING CONTRACTOR
DATE SUBMITTED
HOI/SF-C:1989
J IFIA4IAIAIZrISIA
---------------------------------- --
MAINTAINED BY
APPROVED BY CITY OF FORT COLLINS ON
_S_.
I
I
I �
-------------------I
( RAINFALL PERFORMANCE STANDARD EVALUATION
---------------------------------------------------------------------
PROJECT: A. 13ry .A STOOL 6E Rv 1% STANDARD FORM A
COMPLETED BY: RAje- DATE_-�1/
---------------------------------------------------------------�
DEVELOPED
ERODIBILITY
SUBBASIN
ZONE
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EFFECTIVEIIESS CALCULATIONS
----------------------------------------------------------------------
PROJECT: A Bra A Sroe,a 6e R v.•o. STAIIUARU FORM U
COMPLETED BY: ae ae OAFE: I/Z1g3
Erosion Control.
C-Factor
P-Factor
Method -.
Value
Value Couiment
-------------------
BAet .foil
---------------------------------------
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PS.
SITU
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(o)
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CALCULATIOIIS
- e D
- - 3
- ---
- ---
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(0, /Z.x 0,4 u) x 100D
--------------------=-----------------------------------�
IIUI/SF-U:19U9
EFFECTIVEIIESS CALCULATIUIIS
---------------------------------- ------------------------------------!
PROJECT: A Liim A froYe-AaE' P.0,D. STAIIUARU FURI-I B
COMPLETED BY: p 4p UAIE: .Q/7/ 93
Erosion Control C-Factor P-Factor
Hethod Value Value Conmient
------------------- -----------------------------------
C, 0 ,U
--------------------------
MAJOR
PS.
Sllll
AREA
OAS III
(a)
DASIII
(Ac)
A,B,D,
80.3%
b„
J
0.3rl,9�.
E
CALCULATIUIIS
--------------------------------------------
$ A E G0'•33 Ac,
CS7AP,bVYE1) Sr - AL,.
UJ -r U> C = (pr 33 v A ) .4-C6. 0 x 0. 08)
0 3q -- -
• = br0 SB
WTv = 0,So
C— FF = �(_(0.938r.0.zo�r.
= CO• 9l2X 0•5S) FrO ySL x0•S2) -F(o•57/x0.331
/, 7 (,
83•(..% .
ok % 80,3/o
----------------------------------------------------------------------�
IIUI/SF-D:1989
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James H. Stewart and Associates., Inc.
Consulting Engineers
April 3, 1978
Mr. Earl Wilkinson
412 South Howes
Rott Collins. -Co 80521
Dear Earl:
The detention quantity for Lot 3, Bankcenter Square is calculated as
13,155 cubic feet, based on City requirements for a 50 year storm.
The present runoff of undeveloped 3 acres is 3.6 cubic feet per second.
for a 50 year storm and the developed runoff is 7.2 cubic feet per second.
The proposed 6" outlet pipe from the pond will carry a maximum of 1.6
cubic feet per second.
For comparison, I have calculated the total runoff from a 100 year storm,
which is 17,655 cubic feet. For this area, a 50 year storm is 2.25 inches
per hour and a 100 year storm is 2.8 inches per hour.
Please call if I can be of any further assistance.
Sincerely,
JAI4ES H. STL74ART AND ASSOCIATES, INC.
Phillip I. Robinson, P.E. & L.S.
Vice President
PIR/dw
OFFICE-214 NORTH HOWES • P.O. BOX 429 • FORT COLLINS, COLORADO 80522 • TELEPHONE AREA 30W482-9331
COMPUTATIONS
James H. Stewart & Assoc. Fort Collins, Colorado
By: P�lZ DateClient _Ear% ... Sheet NO. -ot�
Chkd By:..' Date.._ Project: Lot -3 13cin4cen4er�igvai-r JobNo1742..
.
Subject STORM �FZ.4I hlAGF
4 6 9 5 9 1 aet flat 29 FN 3 I B
COUNTY OF LP.RINER STATE OF COLORADO
CERTIFICATION
cc
O
n+ STATE or COLORADO )
�- COUNTY Or LARIMER• ) SS
ca CITY Or FORT COLLINS )
I, City Engineer of the City
co
of tort OcIlins, Mlor&b, do hereby certify that the attached is a true
and correct copy of a Mweramdmm of Agreement by and beb+een Earl Wilkinson,
Charles Howling, and James Jdvm n i San, Inc. regarding the use of a par -
I .
tic► of the psmporty outed by Jams Johnson i Sono Inc. u a detm*Am pcid.,,,
y.
ac the came remains on file and recoxd in the office of the City Engineer.
WITNESS my had, this day of ,,�, _.I qr L
City Engineer
City of Fort Collins. Cblmado
4
C7
i
ca
82181 P12 9
MSMOM MN Or AOAIIKY WT�
THIS Ia A LICSWs■ TO Oss ONLY
Mr. Larl Wilkinson and Mr. Chuck Bowling, who desire to
use a piece of ground owned by James Johnson 6 Son, Ino.,
which lima directly mouth of the Sherwood Irrigation Ditch,
agree to the rollowings
1. The ground will be used only for a required
detention pond.*
2. The detention pond will be constructed as an
earth berm*.
3. The area will be landscaped.
4. The landscape plan will be approved by Mr.
Melvin Johnson, President of Janes Johnson
and Son, Inc.
S. Wilkinson -Bowling or future owners of the
Wilkinson -Bowling property will maintain the
landscaping at their sole expense.
6. The credit for landscaping and the land area
involved will relate to the planned unit de-
velopment requirments of the Johnson property
only. A description of the area is attached.
In return for the above James Johnson i Son, Inc. or future
owners agree -to allow continuous use of the piece of ground
for a detention pond as long as required for the Wilkinson -
Bowling property by the city of sort Collins. If the re-
quirement by the City is terminated or the Wilkinson -Bowling
property is redeveloped and there is a way the drainage
requirement can be otherwise matisfied, this agreement shall
terminate.
Accepted and agreed to this f/ day of April, 1978.
az N c nson'-
�j
Chuck Bowling
JAMS JOHNSON ON,a
Ai7E3?s By
Jn Johns , President
Secretary
STEWART&kSSOCIATES
Consulting Engineers and Surveyors
October 18, 1993
Mr. Glen Schlueter
Storm Water Utility
City of Fort Collins
P.O. Box 580
Fort Collins, Colorado. 80522
Dear Glen:
The following is the cost estimate for A Big A Storage P.U.D. erosion
control facilities:
1. Silt Fence — 365 L.F. @
$2.00
$
730.00
2. Straw Bales at Pipes — 2
@ $75.00
$
150.00
3. Gravel Filters at Inlets
— 2 @ $100.00
$
200.00
4. Reseeding—..86,684 S.F. @ $0.0149/S.F. $1292.00
Based on the re 50% of the estimated cost of the reseeding,
the collateral will be 1938.00. I you have,any questions regarding this
cost estimate, please
Sincerely,
Richard A. Rutherford, P. . & L.S.
President
jrr
James H. Stewart
and Associates, Inc.
103 S. Meldrum Street
P.O. Box.429
Ft. Collins, CO 80522
303/482-9331
Fax 303/482-9382
5028
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