HomeMy WebLinkAboutDrainage Reports - 04/17/1995 (2)Final Approved
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DRAINAGEXEPORT -
FORM
R
LOTS .9. AND 1j1I
FORT COLLINS, COLORADO
PREPARED
FOR
DELEBOY CONSTRUCTION
APRII, 39 1995
STEWART &,,ASSOCIATE$, INC.
103 SOUTH MELDRUM:STREET
FORT COLLINS, COLORADO 80521
303/482-9331
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' STEWART&ASSOCWES
Consulting Engineers and Surveyors
April 3, 1995
' Mr. Basil Hamdan
Stormwater Utility
' City of Fort Collins
P.O. Box 580
Fort Collins, CO 80522
Dear Basil:
' The following is the storm drainage report for a proposed new building on Lots 9 and 10,
Block 11, City of Fort Collins, Colorado. The address is 346 East Mountain Avenue. The area
of the site is 7,218 square feet and it is a part of the Old Town Drainage Basin. The site is
' bounded on the South by East Mountain Avenue, on the West by an existing commercial building,
on the North by an existing gravel alley and on the East by a vacant lot.
The South 1/3 of the lot slopes Southeasterly to Mountain Avenue at an approximate
slope of 0.90%, and the North 2/3 of the lot slopes Northeasterly to the alley at an approximate
' slope of 1.4%. The ground cover is sparse weeds and gravel. The lot has been vacant at least
since 1967.
It is proposed to construct a 50 foot by 100 foot commercial building on the lot with the
North 44 feet by 50 feet as a hard surfaced parking lot. The roof will slope North at
approximately 1% to the North wall of the building. It is proposed to detain the difference
' between the two year historic storm and the 100 year developed storm in the rear parking area.
The required detention volume is 1,140 cubic feet. The detention pond will discharge 0.15 c.f. s.
through a 4 inch diameter P.V.C. pipe with a restriction plate through the curb to the inverted
' crowned paved alley. The runoff flows Easterly in the alley to the Southwest gutter of Jefferson
Street, then Southeasterly to an existing ten foot curb inlet at the comer of Mountain Avenue and
Jefferson Street.
tThe Mountain Avenue right-of-way between the proposed building and the existing curb
will continue to slope to the curb and gutter, and the runoff will flow into the street undetained.
' The runoff in the North gutter of Mountain Avenue flows Easterly to an existing inlet at the
landscape island at the comer of Mountain Avenue and Jefferson Street.
1
' 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
I
' April 3, 1995
Page 2
The property adjacent to the proposed building on the West is higher than this property.
The area South of the existing building will continue to flow to Mountain Avenue on the existing
concrete. The area North of the existing building is gravel and slopes to the alley. The North
area will continue to flow to the alley. The top of the curb to be constructed for the proposed
building will be at elevation 71.75, which will not block runoff from the offsite lot.
' The following two storm drainage variances are requested. The requirement of having
one foot of freeboard between the finish floor of the building and the high water line of the .
detention pond is very difficult to achieve. The finish floor cannot be raised and still be able to
' access the building from the existing sidewalk in the front of the building. A step cannot be used
due to handicap access requirements. The sidewalk cannot be lowered and still fit existing
conditions. The detention pond cannot be lowered and still discharge into the alley. The alley
' cannot be lowered anymore than shown. Four inches of freeboard is provided. With the very
small pond area there is very little risk of wave action. The entire width of the lot acts as a
spillway for the pond. This variance will not cause property damage to this property or adjoining
property.
' The second variance requested is to allow the entire site to discharge into the alley at the
two year historic rate of 0.15 c.f s.. The historic site has 0.05 c.f.s. discharging into Mountain
Avenue and 0.10 c.f.s. into the alley. The developed site drains North to the detention pond and
' then into the alley. The minor increase of flow of 0.05 c.f. s. discharging into the alley will not
adversely affect the capacity of the alley or the Jefferson Street gutter. The alley capacity is
actually increased due to the hard surfacing that will be constructed. Both routes of flow end up
' at the same storm drainage system at the comer of Mountain Avenue and Jefferson Street. There
is no request for a variance to the total allowable discharge.
' The two variance requests are justified because of the small size of the area being
developed and the small amount of stormwater discharge and small detention volume required.
This site is an infill project which should also justify the variance requested.
1
EROSION CONTROL:
The foundation will be constructed as the first task, which will eliminate any erosion
caused by runoff from 5,000 square feet of the 7,200 square foot lot. The parking area will also
be graded early on in the construction process. Straw bales will be placed at the Northeast comer
of the parking area where the runoff will discharge into the alley. A silt fence will be placed along
' the North 44 feet of the East property line.
r-,
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I
April 3, 1995
Page 3
The stormwater runoff calculations and the detention pond mass diagram are included as a
part of this report. The grading plan and the alley plan and profile are also enclosed.
If you have any questions regarding this report, please call.
Sincerely,
CT� G
Richard A. Rutherford, P. . & US.
President
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enclosures
STEWART&&SSOCIATE 103 S. MELDRUM, FORT COLLINS, CO 80521
S PH. 482 9331 FAX 482-9382
Consulting Engineers and Surveyors
By: j2 A PL Dater .,1¢,j 14, /99S Client: De L eaoy C_ omxr2 ye- rjo, Sheet No. - of_
' Project: _(_o-r_r 9 J 100 Rc.ock 110 0e o= EnA✓r Cot,c/Ali
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Consulting Engineers and Surveyors
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STEWART&SSOCIATES 103 S. MELDRUM, FORT COLLINS, CO 80521
PH. 482-9331 FAX 482-9382
Consulting Engineers and Surveyors
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January 18, 1995
STEWART&ASSOCIATES
Consulting Engineers and Surveyors
' Mr. Basil Hamdan
Stormwater Utility
City of Fort Collins
P.O. Box 580
Fort Collins, CO 80522
Dear Basil:
1
1
1
The following is the erosion control cost estimate for Lots 9 and 10,
Block 11, City of Fort Collins, Colorado.
1. Straw Bales $50.00
2. Silt Fence 44 L.F. @ $2.50/ft. $110.00
3. Re —seeding 7500 S.F. @ $0.0298 $223.50
The reseeding of the entire site is $223.50 and 150% of that cost is
$335.00, which is less than the $1,000.00 minimum collateral. Therefore, the
collateral is $1,000.00.
If you have any questions, regarding this cost estimate, please call.
Sincerley,
C-C2z;(0,t
Richard A. Rutherford,.. P.-E. & L.S.
President
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James H. Stewart
and Associates, Inc.
103 S. Meldrum Street
P.O. Box 429
Ft. Collins, CO 80522
303/482-9331
Fax 303/482-9382
( 9�
'
CONSTRUCTION SEQUENCE
PROJECT: Lois 9£!Q-
BLoak.l.l.
Clry nFFrCacta,vl
STANDARD FORA C
SEQUENCE. FOR 19
ONLY
COMPLETED BY: ,e•A C-
DATE: JA u./t:,199S '
•,
Indicate by use of a
bar line
or symbols when erosion control measures will be installed.
Major modifications to an approved
schedule may require submitting a
new schedule for
approval by the City
Engineer.
YEAR
�_-I-F I M-I A M-I-�-I ..1--I A I
S 1 o I
V I
D
------MONTH
OVERLOT GRADING
-
-I
----
----
----
----
----
WIND-----
WIND EROSION CONTROL
I
j
Soil Roughing
I
Perimeter Barrier
I
Additional Barriers
Vegetative Methods
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Soil Sealant
j
Other
j
IrpvNDA -rioN
1
1
RAINFALL EROSION CONTROL
STRUCTURAL:
Sediment Trap/Basin
Inlet Filters
Straw Barriers
Silt Fence Barriers
Sand Bags
Bare Soil Preparation.
Contour Furrows
Terracing
Asphalt/Concrete Paving
Other
FovNDAT10AJ
VEGETATIVE:
Permanent Seed Planting
Mulching/Sealant
Temporary Seed Planting
Sod Installation
Nettinas/Mats/Blankets
Other
STRUCTURES: INSTALLED BY
VEGETATION/MULCHING CONTRACTOR
DATE SUBMITTED
HDI/SF-C:1989
MAINTAINED BY
APPROVED BY CITY OF FORT COLLINS ON
I
JANUA-R i 1991
n
8-20
DESIGN CRITEa!A
RAINFALL
PERFORMANCE STANDARD EVALUATION'
---------------------------------------------------------------------
PROJECT:
Lo'7s qr
/o, Rcoak l/,
Ciry oFFrCoccm,vSTANOARD
FORM A
COMPLETED
BY: R aye
-- ------
DATE: JA,,,ia,/#tj
-- ---------------------------------------
DEVELOPED
ERODIBILITY
Asb
Lsb
Ssb
Lb
Sb
PS
SUBBASIN
---------
ZONE
-----------
(ac)
-------
(ft)
-------
(%) .
-------
(feet)
-------
(%)
-------IlI
I (o)
Lo-reYz&a
/AOP6RATE
0,/$Ac.
/S.S
/,/(,0/O
1S5'
lfiO/,
I 74i-2 Vo
---------------------------------------------------------------------
II)1/BF=A=lA89
--EFFECTIVENESS CALCULATIONS
-----------------
PROJECT: rro7s 9 /O, g,&ock !/.. Ciry eF FrCo�c , STANDARD FORM B
COMPLETED BY: ,e A e " DATE: JAM /4_1947
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Erosion Control
C-Factor
P-Factor
Method
-----------------
Value
Value Comment
----------------------------------------
SAe,5 SOIL.
/.00
A00 O. 0 SSAc.
FOUMI>ATlo�V -
D•01
boo O • /I Ac.
G r Ave[. AtLFy
0.07
/, vv O • D I SAr
S7-,4�prNJ BALES
/•0p
0.80
✓' � t.T F r✓ .vC 6
/ . D't7
p � SlJ
---------------------------------------------
MAJORI
PS SUB AREA
------------------------
BASIN
(%)
BASIN
(Ac)
CALCULATIONS
--- -
Lb-
----.--
----
1-0
----.--
--------------------------------------------
/
J _r D
C x O.OSS, -f'(6.0IX Oa) 4(1.67YO.0,.
61),
0.3Z
W T D " P " = 0,S0X0.80 = D.¢0
�FF = C/ — (0.32.x D 00)1 A/Oa =A 2Z
D�
67.76.-z
E
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DI/SF-B:1989
oAR _ Ems! M
40
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EASEMENT DEDICATION
KNOW ALL MEN BY THESE PRESENTS: That the undersigned being the owners of Lots 9
and 10, Block 11, City of Fort Collins, County of Larimer, State of Colorado, do hereby dedicate
and convey to and for public use, forever, a drainage easement which is described as follows,
provided, however, that acceptance by the City of this dedication of the easement does not
unpose upon the City a duty to maintain the easement so dedicated.
A drainage easement on the North 35.00 feet of Lots 9 and 10, Block 11, City of Fort
Collins, County of Larimer, State of Colorado, containing 1,750 square feet more or less.
Witness our hands and seals this
State of Colorado )
)ss
County of Larimer)
day of
LM
The foregoing instrument was acknowledged before me this
A.D. 19 by
Witness my hand and official seal.
Notary Public
My notarial commission expires:
ATTORNEY'S CERTIFICATE
A.D. 1995.
day of
This is to certify that on the of , A.D. 19 , I examined the title
to the property hereon described and established that the owners and proprietors of record of said
property as construed in C.RS. 1973, 31-23-111, are as shown hereon as of said date.
Signature: Address:
Registration No.
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