HomeMy WebLinkAboutDrainage Reports - 09/01/2006I, 'i
TST, INC. CONSULTING ENGINEERS
PROPERTY OF COY of Ft. Coll' A fans
FORT �� ����pproved BY July 27, 2006
Mr. Basil Harridan
City of Fort Collins Storm Water Division
P.O. Box 580
Fort Collins, CO 80522
Re: Maple Hill
Project No. 0953.0003.00
Dear Mr. Harridan:
We are pleased to submit to you, this addendum to the Final Drainage Report for Maple
Hill. This report was prepared based on Urban Storm Drainage Criteria and City of Fort
Collins criteria.
In the Final Drainage Report for Maple Hill, it was stated that ST-7 would receive offsite
flows from the Lind Property PDP. However, due to a re -design of the Lind Property
drainage system, ST-7 will no longer need to receive this flow. Because this phase of the
Maple Hill project has not yet been constructed, ST — 7 will be resized for the reduced
flow requirement.
Flow from County Road 52 that was assumed to enter ST-7 from basin OF1-3 will now be
entering the Lind Property storm drainage system. These changes are per the Lind
Property PDP and Maple Hill PDP County Road 52 Improvements sheets CS304 11 of
41, the Lind Property Filing 1 CS 453 61 of 82 and CS 454 62 of 82 revised 3/25/05.
Additionally, per the final grading plan for the Maple Hill Subdivision, the area of OF1 — 2
increased while the areas of B3 and D1 were reduced. For the purposes of this
addendum, the impact of decrease in runoff from B3 and D1 was as not considered
because it is conservative. However, ST — 7 has been sized to convey the full runoff from
OF1 —2.
As shown in the attached calculations, the area directly draining to ST-7 will result in a
flow of 5.84 cfs at the flared end section (previously 62.2 cfs), and 6.25 cfs after the area
inlet (previously 66.6). Due to this flow reduction, the pipes were able to be resized to 18"
pipes as shown in the attached LID Sewer analysis. Basin OF1 — 4 drains to a grated
manhole area inlet. A 50% capacity reduction factor has been used to size this inlet
which will require a minimum open area of 0.85 ft2 to convey the 100 — year flow without
encroaching on any residential lots or public right of way. The 100 — year flow used to
size this area inlet was 1.98 cfs, the peak runoff from basin OF1 — 4. Updates have been
made to the storm and utility construction plans.
We look forward to your review and will gladly answer any question�,y9Y9 i %°PPaale.
Sincerely,
TST, INC. CONSULTING ENGINEERS
6 UCT 32935
7 Wig. ti
;mer
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748 Whalers Way, Bldg, D
Fort Collins, CO 80525
(fie--�
D. awson
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4� Ar,i, ;'PE
970.226.0557
metro 303.595 * 9103
SDJ/DBUm f
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fax 970.226.0204
info@tstinc.com
Enclosures
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www.tstmc.com
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ST-7
WSEL = 5000 ft
NeoUDS Results Summary
Project Title: Gillespie Farm
Project Description: ST-7
Output Created On: 7/28/2006 at 10:16:58 AM
Using NeoUDSewer Version 1.5.
Rainfall Intensity Formula Used.
Return Period of Flood is 0 Years.
Sub Basin Information
rF-- Time of Concentration F
Manhol Basin ,Overland Gutter Basin Rain I Peak Flow
e Area * C (Minutes), (Minutes) (Minutes) In our)
(CFS)
ID#
F-67-1 1.06 5.0 0.0 0.0 6.26 6.2
1.00, 5.0 0.0 0.0 6.26
I L 1.00 5.0 0.0 0.0 6.26I 6•2
F 3 0.33 5.0 0.0 0.017.44 5.8 ,
The shortest design rainfall duration is 5 minutes.
For rural areas, the catchment time of concentration is always => 10 minutes.
For urban areas, the catchment time of concentration is always => 5 minutes.
At the first design point, the time constant is <= (10+Total Length/180) in minutes.
When the weighted runoff coefficient => 0.2, then the basin is considered to be urbanized.
When the Overland Tc plus the Gutter Tc does not equal the catchment Tc, the above criteria
supersedes the calculated values.
Summary of Manhole Hydraulics
Design
Manhol
Contributing
Rainfall
Rainfall
peak
Water
e
*
Area C
Duration
Intensity
[Ground
Elevation
Elevation
Comments
ID #
(Minutes)
(Inch/Hour)
(CFS)
(Feet)
(Feet)
r 0
F-6
0.0
0.00
6.2
-5666.661
5000.00
I 1
2.33
5.0
F 2.68
6.2
5018.52
5000.14
r 2
r 1.33
5.0
F 4.69
F 6.2
5014.11
F 5008.76
F
3
0.33
FF
5.0.
17.44
F
5.8
F
5009.73
5 F
5010.69,
Surface Water
Present
Summary of Sewer Hydraulics
Note: The given depth to flow ratio is 1.
Manhole ID Number F Calculated
Sewer rewerDiameter Rise
ID # Upstream Downstream ha a Inches (FT)
p ( ) ( )
Suggested Existing
Diameter Rise Diameter Rise Width
( ) ( )
(Inches) (FT) (Inches) (FT) (FT)
-F 1 Round 13.7 18' 18 N/A:
12 ,F -2�-FRoundF 14.8 F 18F 18. N/A
23 ,FF2
Round
15.9,
18
18, N/A
Round and arch sewers are measured in inches.
Box sewers are measured in feet.
Calculated diameter was determined by sewer hydraulic capacity.
Suggested diameter was rounded up to the nearest commercially available size
All hydraulics where calculated using the existing parameters.
If sewer was sized mathematically, the suggested diameter was used for hydraulic calculations.
Design
g
Full '
Normal
Normal
Critical
Critical
Full
Sewer
ID(CFS)
Flow
[(Flow
Depth
Velocity
Depth
Velocity
Velocity
Froude
Number
Comment
CFS)
(Feet)
(FPS)
(Feet)
(FPS)
(FPS)
_ . 1 _ 6.2 12.9 6.74 7.2 0.96 5.2 3.5 1 "F
12 , . 6.2 10.5; 0.83, 6.2 0.96 5.2 3.5 L33
23
5.8 8.2 0.94 5.0
0.93
5.1
33
6.99 F
A Froude number = 0 indicated that a pressured flow occurs.
Summary of Sewer Design Information
Invert Elevation Buried Depth
Slope �(Feet)
stream, Downstream Upstream Downstream
Sewer ID % (Feet) (Feet) (Feet) Comment
1.50 4997.40 4996.00 19.62 2.50 1
12 1.00 50F80 5003.35 4.81 13.67
23 660 F 5009.72 5007.77 -1.49 4.84 Sewer Too Shallow'
Summary of Hydraulic Grade Line
F-1 Invert Elevation Water Elevation T--7I
Sewer Length
g
Surcharged Length
g g
�Fpstream
Upstream
p
Downstream
�Fcondition,
Sewer ID#
(Feet)
(
(Feet)
(Feet)
IDownstreamI
(Feet)
(Feet)
(Feet)
1 I 93.6.1 93.61 4997.40.1 4996.001 5000.141 5000.001 Pressured
12 444.651 0 5007.80, 5003.35 5008.76 5000.14. Jump
23 324.9;� 0, 5009.72 5007.77 5010.69 5008.76 Subcritical
y
Summary of Energy Grade Line
Upstream Manhole
Juncture Losses Downstream Manhole
Energy Sewer
Bend Lateral ' Energy
Sewer Manhole
Elevation Friction
1D # ID #
Bend K Lateral K Manhole
Loss Loss Elevation
Coefficient Coefficient 11D #
(Feet) (Feet)
(Feet) (Feet) (Feet)
I ' 1 1— 5000.33 0.33 0.20 0.00 1.00 0.00 1 0 5000.00
12 F 2 5009.18 8.85 0.03 0.01 1.00 0.00 � 5000.33
23
5011.08
1.87
0.03,
0.01
1.00
0.02
5009.18
Bend loss = Bend K * Flowing full vhead in sewer.
Lateral loss = Outflow full vhead - Junction Loss K * Inflow full vhead.
A friction loss of 0 means it was negligible or possible error due to jump.
Friction loss includes sewer invert drop at manhole.
Notice: Vhead denotes the velocity head of the full flow condition.
A minimum junction loss of 0.05 Feet would be introduced unless Lateral K is 0.
Friction loss was estimated by backwater curve computations.