HomeMy WebLinkAboutDrainage Reports - 02/01/1987 (2)FINAL DRAINAGE REPORT
Redevelopment of 2025 South College Avenue
(Total Petroleum, Inc.)
Donohue & Associates, Inc.
4710 South College Avenue
Fort Collins, Colorado 80525
February 1987
M
Introduction
This report describes the drainage characteristics for the Total
Petroleum site (2025 S. College Avenue). The existing site (see
Exhibit 1 - Grading Plan) is only half developed. The west half
drains north into Spring Court, to Johnson Drive, and ultimately
to Spring Creek. The east half drains to College Avenue and then
to Spring Creek. This flow pattern will remain the same under
the proposed development, however, on -site detention within the
rear parking lot will be used to control storm water release to
the 2-year, historic rate.
Design Flows and Subbasins
Flows were calculated using the Rational Formula for the 100-year
and 2-year storm events. These are shown on the attached exhibit
along with flow arrows and grading contours. The contribution of
flow from the east side of the site to College Avenue is 1.37 cfs
during the 100-year event and 0.4 cfs during the 2-year event.
The flow off the back (west) side of the site is 2.6 cfs for the
100-year event and 0.86 cfs for the 2-year event (see exhibit).
The two other subareas on the site are grassed areas comprising
0.12 acres located at the extreme west part of the site.
Storm Water Detention
Storm water will be held in th
west by a retaining wall.
approximately 1800 cubic feet.
constructed to control flow west
flow control device consists of
and a drop structure.
Erosion Control
e
rear parking lot, bounded on the
The retained water amounts to
A release structure will be
to Spring Court to 0.5 cfs. The
a manhole lid with drilled holes,
The erosion control plan for the construction phase of the off -
site and site improvements includes the use of filter fence and
filter berms to confine mud generated by construction activities
to the construction area. Use of filter berms at the end of
construction on Spring Court and at the site entrance to College
Avenue will retain sediment carried by drainage flows. Filter
fences will be used where grades will cause drainage from the
construction area to leave the area. The site parking area will
be paved and the landscaped areas sodded shortly after grading is
completed. Offsite areas disturbed will be plowed and seeded.
Erosion control measures will be removed after completion of site
coverage.
The potential for erosion once the site is completed is minimized
by the use of sod, gravel mulch and paving to cover the entire
site. The drainage channel includes a concrete trickle channel
for channel protection. All drainage flows are confined to paved
areas or the paved trickle channel.
Impacts
The proposed improvement will not significantly impact downstream
facilities during either major or minor storm events because
storm water releases will not significantly exceed historical
releases.
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JDRAINIGEGRA`T$ 2p�
R-4030 Series . Heavy Duty; Grates
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R-4040 Series � Light Duty Grates
Designed to fit in bell end of standard sewer pipe.
Bell and spigot vitrified clay and concrete pipe are made under many
specifications and dimensions vary. Check the grate sizes in the table
to be sure they will fit the pipe you are using.
If specified, special lug arrangement is available on R-4040 series
which modifies grate to fit corrugated metal pipe in sizes indicated.
Weight in Pounds
Dimensions in inches
Heavy Duty
Light Duty
R-4030
R-4040
Pipe
Grote
Grate
Site
Dia.
Thickness'
6t
4
4
53A
1 '/,
13t
9
6
8
2
252
11
8
lash
21/.
25t
I
10
12%
21/7
38t
32
12
14%
21h
70t
55
15
181/4
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115t--o
75
18
22
2%
200t"(&
100
21
25'h
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210t--
140
24
29
31/.
290--
155
27
32s/.
31/2
300**0
1800
30
36
3%
525--
3000
36
42
4
-For light duty series this figure includes legs. "Slotted openings.
tSlight Crown. *Square openings. ®Not recommended for bicycle traffic
,.. For safety standards see pages 94 to 99. .
R-40Series -� Manhole
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Lids to:Fit'Over.Pipe" Bell.;
Medium Duty
J Bell and spigot vitrified clay and concrete pipe is
it made under many specifications and dimensions
ra vary. Check the lid size in the table to be sure
they will fit the pipe you are using.
a Specify:
h 1. Catalog number.
t!. 2. Lettered as shown or without lettering.
Rr4030 Type Grate"
R-4030 Type Grate$
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Showing grote
placed in bell of
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standard vitrified
sewer pipe.
Specify: R-4040 Type Grate with legs
l: Catalog number.
2. Pipe size.
,3. Lugs on R-4040 for corrugated pipe if required.
For
Dimensions
Catalog
Pipe
in inches
kA
Wt.
B
C
I D
No.
Size
lbs.
R-4044-A
4
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6
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20
R-4044-D
10
14%.
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12sy4
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R4044-E
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50
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340
R-4044-M
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R-4055.Senes.,;.;7Cov_.eri'to- .
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Pipe
Dimensions
in inches
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No.
Size
A
B
lbs.
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R-4055-12
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30
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R-4055-15 .
R-403S-16
15
18
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22
214
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45
50
A
hen ordering, advise pipe size. Remember, bell
and spigot vitrified clay and concrete pipe is
R-40S5-21:
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25'h
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110
= v" .
made under many specifications and dimensions
R-I0SS-24
24
29
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140
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vary. Check the cover size in the table to be sure
R-4035-27
27
32s/.
3'h
170
: ;. .
they will fit the pipe you are using.
R-4035-30
30
36
R-4055-36
36
42
233
M&I/Donohue
CLIENT
DATE
PROJECT BY
Fort Collins, Colorado PROJECT NO. - PAGE NO,
CONTROL TECHNIQUE F
FILTER FENCE
DEFINITION
A low fence made of filter cloth and fencing material.
PURPOSE
To filter runoff water prior to discharge.
APPLICABILITY
Any construction site.or other site of disturbance where the danger of
discharge of sediment -laden water exists. This is a temporary measure
and should be removed when no longer needed.
PLANNING CRITERIA
A filter fence can be substituted for a filter berm at approximately
equal cost, but the filter fence is easier to maintain and remove.
Care must be taken to insure that all runoff water must pass through,
not over, under or around, the filter cloth. This only applies to
sites which will not be subjected to significant hydrostatic pressure
or to vehicular traffic.
METHODS AND MATERIALS
• The filter fence shall be designed to filter the design storm
without overtopping, collapsing, becoming sedimented in, or.
being skirted by runoff flows.
• The fence shall be constructed with fence posts and "hog -wire"
(4"x4" or 6"x6" wire mesh) or "chicken -wire" of i14 or heavier
gauge wire. The fence shall be constructed as shown in Figure F-1.
a A trench shall be excavated at the uphill base of the fence to
a depth of at least 6 inches.
• Filter cloth (Mirafi 140 or equivalent) shall be draped over the
wire fencing material and lowered into the trench.
a The trench shall be backfilled to grade and compacted.
MAINTENANCE
Inspect periodically and after each storm for damage and repair or re-
place damaged sections. Remove sediment accumulations when the capacity
of the filter is impaired.
A
1. Drive wooden or metal posts.
33 Attach wire mesh.
S. Attach filter fabric.
J
2. Dip toe trench.
4. Cut length of filter fabric.
6. 8ackf111 trench.
CONTROL TECHNIQUE E
FILTER BERM
DEFINITION
A filter berm is a temporary ridge of gravel or crushed rock.
PURPOSE
To retain sediment on -site by retarding and filtering runoff while
allowing water to be discharged from the site.
APPLICABILITY
Filter berms may be used as outlets for sediment barriers around con-
struction sites, where graded areas meet paved roadways, in uncompleted
drainage facilities, or any other location requiring detention and
filtration of runoff water.
PLANNING CRITERIA
Filter berms are used to filter runoff water for discharge from the
site. Continuous filter berms may be used around construction sites
or individual berms may be located at discharge points in impermeable
bartiers such as shown in CT C&H.
If continuous filter berms are used, discharge through shall
be to a stable area such that no erosion occurs.
° Detailed design is not required. Figures E-1 and E-2 provide
general design criteria. Minimum requirements for use on graded
rights -of -way are as .follows:
• Height - 1.5 feet to 3 feet.
• Top Width - 1 to 1.5 feet.
• Side Slopes - 2:1 or flatter
• Material -.Coarse (3/4" to 1-1/2"), well -graded gravel or
crushed rock. Fines less than 5 percent.
• Filter Cloth - As specified in CT F.
MAINTENANCE
Remove all trapped sediment and clean out or replace clogged filter
material after -each storm. Repair as damaged by traffic.
COST
The unit cost for filter berms is $6.00 - $7.00 per lineal foot.
1
} 2:1
Graded Roadway J
3:1 I I
Flow Direction max I 3.1
mox
FILTER BERM ON GRADED ROADWAY
PLAN
no scale
3:1
Slope
mox.
Flow Direction
3:1
Graded Roadway
Slope
Max.
exist. cut slope
FILTER
BERM IN ROADWAY CUT
PLAN
no scale
Paved Street %
I
t ;!
0
a
0
Paved Street ,
FILTER I$RMS ZN;
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FIGURE E-2