HomeMy WebLinkAboutHEARTHFIRE PUD, 2ND FILING - FINAL - 31-95E - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT3.1.7 Time of Concentration
In order to use the Rainfall Intensity Duration Curve, the time of concentration must be
known. This can be determined either by the following equation or the "Overland Time r
Flow Curves" from the Urban Storm Drainage Criteria Manual, included in this report (Se
Figure 3-2).
Tc=1.87 (1.1 —CC,) D112
S11J
Where Tc =Time of Concentration, minutes
S = Slope of Basin, %
C = Rational Method Runoff Coefficient
D = Length of Basin, feet
Ct = Frequency Adjustment Factor
Time of concentration calculations should reflect channel and storm sewer velocities as well
as overland flow times.
3.1.8 Adjustment for Infrequent Storms
The preceding variables are based on the initial storm, that is, the two to ten year storms. For
storms with higher intensities an adjustment of the runoff coefficient is required because of
the lessening amount of infiltration, depression retention, and other losses that have a
proportionally smaller effect on storm runoff.
These frequency adjustment factors are found in Table 3-4.
Table 3-4
RATIONAL METHOD FREQUENCY ADJUSTMENT FACTORS
Storm Return Period
(years)
2to10
11 to 25
26 to 50
51 to 100
3.2 Analysis Methodology
Frequency Factor
Ct
1.00
1.10
1.20
1.25
Note: The product of C times C, shall not exceed 1.00
The methods presented in this section will be instituted for use in the determination and/or verification
of runoff at specific design points in the drainage system. These methods are (1), the Rational Method
and (2) the Colorado Urban Hydrograph Procedure (CUHP). Other computer methods, such as
SWMM, STORM, and HEC-1 are allowable if results are not radically different than these two. Where
applicable, drainage systems proposed for construction should provide the minimum protection as
determined by the methodology so mentioned above.
3.2.1
tWl Wll
Rational Method
For drainage basins of 200 acres or less, the runoff may be calculated by the Rational
Method, which is essentially the following equation:
Q = C,CIA
Where Q = Flow Quantity, cfs
A =Total Area of Basin, acres
Ct = Storm Frequency Adjustment Factor (See Section 3.1.8)
C = Runoff Coefficient (See Section 3.1.6)
1 = Rainfall Intensity, inches per hour (See Section 3.1.4)
Colorado Urban Hydrograph Procedure
For basins larger than 200 acres, the design storm runoff should be analyzed by deriving
synthetic unit hydrographs. It is recommended that the Colorado Urban Hydrogra^�,
Procedure be used for such ana!ysis. This procedure is detailed in the Urban Storm Drain
Criteria Manual, Volume 1, Section 4.
MAY 1984 . 3-5 DESIGN CRITERIA
R-M-P Medium Density Planned Residential District — designation for medium density
areas planned as a unit (PUD) to provide a variation in use and building placements
with a minimum lot area of 6,000 square feet.
R-L-M Low Density Multiple Family District — areas containing low density multiple family
units or any other use in the R-L District with a minimum lot area of 6,000 square feet
for one -family or two-family dwellings and•9,000 square feet for multiple -family
dwellings.
M-L Low Density Mobile Home District — designation for areas for mobile home parks
containing independent mobile homes not exceeding 6 units per acre.
M-M Medium Density Mobile Home District — designation for areas of mobile home
parks containing independent mobile homes not exceeding 12 units per acre.
B-G General Business District — district designation for downtown business areas,
including a variety of permitted uses, with minimum lot areas equal to 1 /2 of the total
floor area of the building.
B-P Planned Business District — designates areas planned as unit developments to
provide business services while protecting the surrounding residential areas with
minumum lot areas the same as R-M.
H-B Highway Business District — designates an area of automobile -orientated busi-
nesses with a minimum lot area equal to 112 of the total floor area of the building.
B-L Limited Business District — designates areas for neighborhood convenience
centers, including a variety of community uses with minimum lot areas equal to two
times the total floor area of the building.
C Commercial District —designates areas of commercial, service and storage areas.
I-L Limited Industrial District —designates areas of light industrial uses with a minimum
area of lot equal to two times the total floor area of the building not to be less than ,-
20,000 square feet.
I-P Industrial Park District —designates light industrial park areas containing controlled
industrial uses with minimum lot areas equal to two times the total floor area of the
building not to be less than 20,000 square feet.
I-G General Industrial District — designates areas of major industrial development.
T Transition District — designates areas which are in a transitional stage with regard
to ultimate development:
For current and more explicit definitions of land uses and zoning classifications, refer to the
Code of the City of Fort Collins, Chapters 99 and 118.
Table 3-3
RATIONAL METHOD RUNOFF COEFFICIENTS FOR COMPOSITE ANALYSIS
Character of Surface Runoff Coefficient
Streets, Parking Lots, Drives:
Asphalt................................................................................................ 0.95
Concrete............................................................................................. 0.95
Gravel................................................................................................. 0.50
Roofs.......................................................................................................... 0.95
Lawns, Sandy Soil:
Flat<2%............................................................................................. 0.15
Average2 to 7%.................................................................................. 0.
Steep>7%.......................................................................................... 0.20
Lawns, Heavy Soil:
Flat<2%............................................................................................. 0.20
Average2 to 7%.................................................................................. 0.25
Steep>7%.........:................................................................................ 0.35
MAY 1984 3-4 DESIGN CRITERIA
3.1.6 Runoff Coefficients
The runoff coefficients to be used with the Rational Method referred to in Section 3.2
"Analysis Methodology" can be determined based on either zoning classifications or the
types of surfaces on the drainage area. Table 3-2 lists the runoff coefficients for the various
types of zoning along with the zoning definitions. Table 3-3 lists coefficients for the different
kinds of surfaces. Since the Land Development Guidance System for Fort Collins allows land
development to occur which may vary the zoning requirements and produce runoff coeffi-
cients different from those specified in Table 3-2, the runoff coefficients should not be based
solely on the zoning classifications.
The Composite Runoff Coefficient shall be calculated using the following formula
C = (s C;A;)/A,
i=1
Where C = Composite Runoff Coefficient
C; = Runoff Coefficient for specific area A;
A; =Area of surface with runoff coefficient of C;
n = Number of different surfaces to be considered
A, =Total area over which C is applicable; the sum of all A;'s is equal to A,
Table 3-2
RATIONAL METHOD RUNOFF COEFFICIENTS FOR ZONING CLASSIFICATIONS
Description of Area or Zoning
Business: BP, BL........................................................................................
Business: BG, HB, C..................................................................................
Industrial: IL, IP..........................................................................................
Industrial: IG...............................................................................................
Residential: RE, RLP..................................................................................
Residential: RL, ML, RP.............................................................................
..Residential: RLM, RMP..............................................................................
Residential: RM, MM..................................................................................
Residential: RH..........................................................................................
Parks, Cemeteries......................................................................................
Playgrounds...............................................................................................
RailroadYard Areas...................................................................................
Unimproved Areas......................................................................................
Coefficient
0.85
0.95
0.85
0.95
0.45
0.50
0.60
0.65
0.70
0.25
0.35
0.40
0.20
Zoning Definitions
R-E Estate Residential District — a low density residential area primarily in outlying
areas with a minimum lot area of 9,000 square feet.
R-L Low Density Residential District — low density residential areas located throughout
the City with a minimum lot area of 6,000 square feet.
R-M Medium Density Residential District — both low and medium density residential
areas with a minimum lot area of 6,000 square feet for one -family or two-family
dwellings and 9,000 square feet for a multiple family dwelling.
R-H High Density Residential District —high density residential areas with a minimum lot
area of 6,000 square feet for one -family or two-family dwellings, 9,000 square feet
for a multiple family dwelling, and 12,000 square feet for other specified uses.
R-P Planned Residential District — designation of areas planned as a unit (PUD) to pro-
vide a variation in use and building placements with a minimum lot area of 6,000
square feet.
R-L-P Low Density Planned Residential District — areas planned as a unit (PUD) to permit
variations in use, density and building placements, with a minumum lot area of 6,000
square feet.
MAY 1984
3-3
DESIGN CRITERIA
No Text
DRAINAGE CRITERIA MANUAL
RUNOFF
6"
30
F- 2 0
z
w
U
cc
IL 10
z
w
a r;
O 5
rn
w
cc 3
O
U 2
w
F-
1
.5
�I
• I
r r
1, I '
r
I
nil
•,
a�►�■=�i�■►l�i
■■■■ICI
■'�■■■■��
a 1 2 3 5 10 20
VELOCITY IN FEET PER SECOND
FIGURE 3-2. ESTIMATE OF AVERAGE FLOW VELOCITY FOR
USE WITH THE RATIONAL FORMULA.
*MOST FREQUENTLY OCCURRING "UNDEVELOPED"
LAND SURFACES IN THE DENVER REGION.
REFERENCE: "Urban Hydrology For Small Watersheds" Technical
Release No. 55, USDA, SCS Jan. 1975.
5 -1-84
URBAN DRAINAGE & FLOOD CONTROL DISTRICT
APPENDIX III
Supporting exhibits, figures, tables, etc.
Figure 3-1; City of Ft.. Collins Rainfall Intensity Duration Curve
Figure 3-2; Estimate of Average Flow Velocity for Use with the Rational Formula
Table 3-3; Rational Method Runoff Coefficients for Composite Analysis
Table 3-4; Rational Method Frequency Adjustment Factors
Figure 4-2; Reduction Factor for Allowable Gutter Capacity
Fig 5-2 Nomograph for Capacity of Curb Opening Inlets in Sumps
Fig 5-3; Capacity of Grated Inlet in Sump
Table 4 Circular Pipe Flow Capacity for Mannings 'n' = 0.012
Table 5 Circular'Pipe Flow Capacity for Mamungs 'n' = 0.013
CONSTRUCTION SEQUENCE
PROJECT: _Hearthfire P.U.D., Second Filing
STANDARD FORM C
SEQUENCE FOR ONLY COMPLETED BY: MEO / Shear Engineering Corp.
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 197 98
Month S O N D J F M A M J J A
OVERLOT GRADING ***
WIND EROSION CONTROL
* Soil Roughening ***
Perimeter Barrier
Additional Barriers
Vegetative Methods
Soil Sealant
Other
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
VEGETATIVE:
Permanent Seed Planting
*** ***
Mulching/Sealant
Temporary Seed Planting
***
***
Sod Installation
*** ***
Nettings/Mats/Blankets
Other
STRUCTURES: INSTALLED BY: DEVELOPER MAINTAINED BY: DEVELOPER
VEGETATION/MULCHING CONTRACTOR: DEVELOPER
DATE PREPARED: 06/26/97 DATE SUBMITTED: 07/16/97
APPROVED BY THE CITY OF FORT COLLINS ON:
SHEAR'
ENGINEERING
CGRPGRATIGN
July 16, 1997
Project No: 1552-02-97
Re: EROSION CONTROL SECURITY DEPOSIT REQUIREMENTS:
Hearthfire P.U.D., Second Filing; Fort Collins, -Colorado
An erosion control security deposit is required in accordance with City of Fort Collins
policy (Chapter 7, Section C: SECURITY; page 7.23 of the City of Fort Collins
Development Manual). In no instance shall the amount of the security be less than
$1000.00.
a. The cost to install the proposed erosion control measures is approximately
$15,675.00 Refer to the cost estimate attached in Appendix I. 1.5 times the cost to
install the erosion control measures is $23,512.50.
b. Based on current data provided by the City of Fort Collins Stormwater Utility, and
based on an actual anticipated net affected area which will be disturbed by
construction activity (approximately 20 acres), we estimate that the cost to re -
vegetate the disturbed area will be $10,620.00 ($531 per acre x 20 acres). 1.5 times
the cost to re -vegetate the disturbed area is $15,930.00. The $531 per acre cost for
re -seeding sites greater than 5 acres was quoted to us by City of Fort Collins
Stormwater Utility personnel.
CONCLUSION:
The erosion control security deposit amount required for Hearthfire P.U.D., Second Filing
will be S 23,512.50.
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-031 1
July 16, 1997
Project No: 1552-02-97
Basil Hamdan
City of Fort Collins Stormwater Utility
P.O. Box 580
Ft. Collins, Colorado 80522
Re: Erosion Control Cost Estimate
Hearthfire P.U.D., Second Filing; Fort Collins, Colorado
Dear Basil,
Z///,,
SHEAR
ENGINEERING
CORPORATION
Attached is the erosion control security deposit estimate for Hearthfire P.U.D., Second Filing.
ESTIMATE 1:
9 - Gravel Inlet Filter Q $75.00 each $ 675.00
10 - Haybale barriers ® 75.00 each $ 3,000.00
4000 lineal feet silt fence ® $3.00 per foot $ 12 000.00
TOTAL ESTIMATED COST: $ 15,675.00
x 1.50
S 239512.50
I_M11 M IT0Ifs►
re -vegetate the disturbed area of 20 acres at $ 531.00 per acre $ 10 620.00
TOTAL ESTIMATED COST: $ 10,620.00
x 1.5
$ 159930.00
In no instance shall the amount of the security be less than $1,000.00. Therefore, the total
required erosion control security deposit for Hearthfire P.U.D., Second Filing will be
$239512.50.
If you have any questions, please call at 226-5334.
Sincerely,
Mark Oberschmidt.
Shear Engineering Corporation
MEO / meo
cc: Richards Lake Development
Jean Pakech, Stormwater Utility
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-031 1
EFFECTIVENESS CALCULATIONS
PAGE
2 OF 2
STANDARD
FORM B
PROJECT: HEARTHFIRE P.U.D. SECOND
PROJ. NO.1552-01-96
BY: MARK OBERSCHMIDT
DATE
07/14/97
------------------------------------------------------------------------------------------
MAJOR PS SUB AREA
CALCULATIONS
BASIN % BASIN acre
AREA
C
P
------------------------------------------------------------------------------------------
ALL 84.60% 5 2.71
ROOF
1.12 ACRES
1.00
0.90
SOD
0.75 ACRES
0.01
1.00
EQUATIONS.
ASPHALT
0.84 ACRES
0.01
1.00
C = WEIGHTED AVG OF C X AREA
P= (WEIGHTED AVG OF P X AREA) X P
C=
0.4192
EFF - (1 - P X C) X 100
P =
0.3068
EFF
87.14%
------------------------------------------------------------------------------------------
6 9.02
ROOF
1.80 ACRES
1.00
0.90
SOD
7.22 ACRES
0.01
1.00
ASPHALT
0.00 ACRES
0.01
1.00
C =
0.2080
P =
0.3136
EFF
93.48%
------------------------------------------------------------------------------------------
7 10.47
ROOF
2.09 ACRES
1.00
0.90
SOD
8.38 ACRES
0.01
1.00
ASPHALT
0.00 ACRES
0.01
1.00
C =
0.2080
P =
0.3136
EFF
93.48%
------------------------------------------------------------------------------------------
8 5.31
ROOF
1.06 ACRES
1.00
0.90
SOD
4.25 ACRES
0.01
1.00
ASPHALT
0.00 ACRES
0.01
1.00
WETLAND
1.21 ACRES
0.00
0.00
C =
0.2080
P =
0.4900
EFF
89.81%
t+frtttf+ttrffttt+xtr+x+frffrff+ftffxx+f xffffff
tf tff+tt+rrtrrf tff tf tf tx+tt+rrrrrrrrffrfff+
SUB TOTAL AREA 27.51 ACRES
EFFECTIVENESS = 92.14%
TOTAL AREA = 39.31 ACRES
OVERALL EFFECTIVENESS = 89.63%
>
84.601,
CONCLUDE: EROSION CONTROL PLAN IS EFFECTIVE
EFFECTIVENESS CALCULATIONS
PAGE
1 OF
2
STANDARD
FORM B
PROJECT: HEARTHFIRE P.U.D.
SECOND
PROJ. NO.1552-01-96
BY: MARK OBERSCHMIDT
DATE
07/14/97
------------------------------------------------------------------------------------------
EROSION CONTROL
C-FACTOR
P-FACTOR
COMMENT
METHOD
VALUE
VALUE
------------------------------------------------------------------------------------------
ROUGHENED GROUND
1.00
0.9
ROOF AREAS
SILT FENCE
1.00
0.5
SUBBASINS
1-5
HAY BALES
1.00
0.8
SUBBASINS
1-5
!
ASPHALT
0.01
1.0
SUBBASINS
1-5
SOD
0.01
1.0
SUBBASINS
1-5
GRAVEL INLET FILTERS
1.00
0.8
SUBBASINS
1-5
------------------------------------------------------------------------------------------
MAJOR PS SUB
AREA
CALCULATIONS
BASIN % BASIN
acre
AREA
C
P
------------------------------------------------------------------------------------------
ALL 84.60% 1
0.78
ROOF
0.27 ACRES
1.00
0.90
SOD
0.18 ACRES
0.01
1.00
EQUATIONS
ASPHALT
0.34 ACRES
0.01
1.00
C - WEIGHTED AVG OF C X AREA
P- (WEIGHTED AVG
OF P X AREA) X P
C=
0.3528
EFF = (1 - P X C)
X 100
P =
0.3130
------------------------------------------------------------------------------------------
EFF
88.96%
2
0.90
ROOF
0.30 ACRES
1.00
0.90
SOD
0.20 ACRES
0.01
1.00
ASPHALT
0.40 ACRES
0.01
1.00
C =
0.3400
P =
0.3093
------------------------------------------------------------------------------------------
Epp
89.48%
3
2.00
ROOF
0.82 ACRES
1.00
0.90
SOD
0.55 ACRES
0.01
1.00
ASPHALT
0.63 ACRES
0.01
1.00
C =
0.4159
P =
0.3069
------------------------------------------------------------------------------------------
EFF
87.24%
4
8.12
ROOF
3.64 ACRES
1.00
0.90
SOD
2.42 ACRES
0.01
1.00
ASPHALT
0.85 ACRES
0.01
1.00
WETLAND
1.21 ACRES
0.00
0.00
C =
0.4523
P =
0.4031
EFP
81.77%
f xtrxxxttttffffffffff tf txtxttttf tfffftxxxf xtx+ttf
ttffxtttttftff xxxxtxxxfxxxxxf
txx+xxttfff+
SUBTOTAL AREA =
11.8 ACRES
EFFECTIVENESS =
83.76%
RAINFALL PERFORMANCE STANDARD EVALUATION
PROJECT:
HEARTHFIRE PUD SEC
STANDARD
FORM A
COMPLETED BY:
MARK OBERSCHMIDT
DATE:
07/14/97
xxxif++x+f ift+xxxxf
r+rrf rtrxxxxxxxx*♦+++xxxi+itxxxixrirrrrr*+x+x+xxx+rift+xxx+++rift+xrxx+
DEVELOPED
ERODIBILITY
Aeb
Lob
Sob
Lb
Sb PS
SUBBASIN
ZONE
(ac)
(ft)
(})
(feet)
(}) (})
x Hfir+++ri+tt++iHe+rrii+rtttt+xi++r++x+if
it+tirxrr+Hti+t*xxr ry xixi H tt+xxx+x Hirtxxrxxr
1
MODERATE
0.78
520.00
1.00
406
0.78
2
MODERATE
0.90
420.00
1.20
378
1.08
3
MODERATE
2.00
990.00
1.90
1980
3.80
4
MODERATE
8.12
1285.00
1.90
10434
15.43
5
MODERATE
2.71
955.00
0.90
2588
2.44
6
MODERATE
9.02
400
4.00
3608
36.08
7
MODERATE
10.47
1500
2.00
15705
20.94
8
MODERATE
5.31
200
4.00
1062
21.24
i xxxx**+t+rr+*xxx++++*+xixxxi+*ii+r+xxxx+r*++++x*rtxf rfirrr+rtxxxrirr+r+
14.51 2492.13 7.01
LINEAR INTERPOLATION
SLOPE
LENGTH
7.00
7.01
8.00
2000
84.6
84.60
84.6
2492.13
84.60
2500
84.6
84.60
84.7
CONCLUDE:PERFORMANCE STANDARD = 84.60%
EROSION CONTROL PLAN OVERALL EFFECTIVENESS MUST EXCEED THIS
APPENDIX H '
Erosion Control Calculations.
SHEAR ENGINEERING
CORPORATION
DEVELOPED
PAGE
14
FLOW TO CONCENTRATION POINT
E
FROM SUBBASIN
5
PROJECT: HEARTHFIRE.PUD
DATE
07/14/97
LOCATION:TOWN CENTER DRIVE
- NORTH SIDE
PROJ. N0.1552-01-96
FILE: STORM
BY
MEO
AREA (A)= 2.71 ACRES
i
RUNOFF COEF.y,(C)
2 YEAR
SO YEAR
100 YEAR
C 0.74
0.74
0.93
REFER TO SUBBASIN BREAKDOWN ON PAGE 2
TIME OF CONCENTRATION (TO
OVERLAND TRAVEL TIME (Ti)
LENGTH 30 FEET
SLOPE = 2.00
%
2 YEAR
10 YEAR
100 YEAR
C = 0.20
0.20
0.25
Ti (min)- 7.33
7.33
6.93
TRAVEL TIME (Tt)=L/(60*V)
FLOW TYPE
L (ft) - 50 S (%)
= 0.50 GUTTER
V (fps)
= 1.50
Tt(min)=
0.56
L (ft) = 105 S (%)
4.00 GUTTER
V (fps)
= 4.00
Tt(min)=
0.44
L (ft) - 770 S (%)
= 0.50 GUTTER
V (fps)
= 1.50
Tt(min)=
8.56
L (ft) =7 S (%)
_? ?
V (fps)
_?
Tt(min)=
0.00
L (ft) =7 S (%)
_? ?
V (fps)
_?
Tt(min)=
0.00 --
L (ft) _? S (%)
_? ?
V (fps)
_?
Tt(min)=
0.00
L (ft) =7 S (%)
_? ?
V (fps)
_?
Tt(min)=
0.00
NOTE: ALL VELOCITIES TAKEN FROM FIGURE 3-2
TOTAL TRAVEL TIME
(min) =
9.55
L = 955 L/180+10
15.31 <
16.47
CHOOSE LESSER
Tc =Ti+TOTAL TRAVEL TIME
2 YEAR
10 YEAR
100 YEAR
Tc (min)= 15.31
15.31
15.31
USE Tc - 15.5
15.5
15.5
INTENSITY (I) (iph)
2 YEAR
10 YEAR
100 YEAR
I = 2.11
3.70
5.98
NOTE: INTENSITIES TAKEN FROM FIGURE
3-1
RUNOFF (Q= CIA) (cfs)
2 YEAR
10 YEAR
100 YEAR
QINLET = 4.24
7.44
15.02
CONCLUDE:PIPE DIAM. =
2.00 FT. PIPE TYPE =
ADS
0.012
SLOPE =
0.0235 FT/FT
SLOPE _
0.005
FT/FT
CONVEYANCE FACTOR= 245.08 - REFER
TO TABLE
4 ADS MANUAL
CAPACITY =
37.57 CFS
'
PIPE OVERSIZED FOR OVERFLOW FROM POND 2
SHEAR ENGINEERING CORPORATION
DEVELOPED
FLOW TO CONCENTRATION POINT E2
FROM SUBBASIN 5B
PROJECT: HEARTHFIRE PUD DATE 07/14/97
LOCATION:TOWN CENTER DRIVE - SOUTH SIDE PROJ. NO.1552-01-96
FILE: STORM BY HBO
AREA (A)= 0.77 ACRES
PAGE
RUNOFF COEF. (C)
2 YEAR
10
YEAR
100
YEAR
C = 0.74
0.74
0.92
REFER TO SUBBASIN
BREAKDOWN ON
PAGE
2
TIME OF CONCENTRATION (Tc)
OVERLAND TRAVEL TIME (Ti)
LENGTH 50
FEET SLOPE
= 1.00
$
2 YEAR
10
YEAR
100
YEAR
C = 0.20
0.20
0.25
Ti (min)= 11.90
11.90
11.24
TRAVEL TIME (TO
=L/(60*V)
FLOW TYPE
L (ft) = 450
- S (6) =
0.50
GUTTER
V (fps)
= 1.50
Tt(min)=
L'(ft) =?
S (11) =?
?
V (fps)
=?
Tt(min)=
L (ft) =?
S (%) =?
?
V (fps)
=?
Tt(min)=
L (ft) =?
S (%) =?
?
V (fps)
=?
Tt(min)=
L (ft) =?
S ('a) =?
7
V (fps)
=?
Tt(min)=
L (ft) =?
S (%) =?
?
V (fps)
=?
Tt(min)=
L (ft) =?
S (4) =?
7
V (fps)
=?
Tt(min)=
NOTE: ALL VELOCITIES TAKEN
FROM, FIGURE 3-2.
TOTAL TRAVEL TIME
(min) _
L = 500
L/180+10
12.78
<
16.24
CHOOSE
LESSER
Tc =Ti+TOTAL TRAVEL TIME
2 YEAR
10
YEAR
100
YEAR
Tc (min)= '12.78
12.78
12.78
USE Tc = 13
13
13
INTENSITY (I) (iph)
2 YEAR 10 YEAR
I = 2.30 4.03
NOTE: INTENSITIES TAKEN FROM FIGURE
100 YEAR
6.49
3-1
RUNOFF (Q= CIA) (C£s)
2 YEAR 10 YEAR 100 YEAR
Q = 1.30 2.28 4.60
QTOTAL = 4.72 8.10 16.69 FROM FILING 1 CALCULATIONS
CONCLUDE:INSTALL 10 FOOT TYPE R INLET SUMP FOR 100 YEAR STORM
CAPACITY PER FOOT (cfe/ft)= 2.45 BASED ON FLOW DEPTH OF 1 FOOT
ABDUCTION FACTOR 90.004ACTUAL CAPACITY 22.05 CPS
PIPE DIAM. = 2.00 FT. PIPE TYPE = ADS MANNINGS 0.012
SLOPE = 0.0235 FT/FT SLOPE _ 0.005 FT/FT
CONVEYANCE FACTOR= 245.08 - REFER TO TABLE 4 ADS MANUAL
CAPACITY = 37.57 CPS
PIPS OVERSIZED FOR OVERFLOW FROM POND 2
INLET SIZED FROM FILING 1
13
5.00
0.00
0.00
0.00
0.00
0.00
0.00
5.00
SHEAR ENGINEERING CORPORATION
DEVELOPED
FLOW TO CONCENTRATION POINT E1
FROM SUBBASIN SA
PROJECT: HEARTHFIRE PUD DATE 07/14/97
LOCATION:TOWN CENTER DRIVE - NORTH SIDE PROD. NO.1552-01-96
FILE: STORM BY MEO
AREA (A)= 1.94 ACRES
RUNOFF CORP. (C)
2 YEAR 10 YEAR 100 YEAR
C = 0.75 0.75 0.93
REFER TO SUBBASIN BREAKDOWN ON PAGE 2
TIME OF CONCENTRATION (Tc)
OVERLAND TRAVEL TIME (Ti)
LENGTH = 30 FEET
2 YEAR
C = 0.20
Ti (min)= 7.33
SLOPE 2.00 %
10 YEAR 100 YEAR
0.20 0.25
7.33 6.93
TRAVEL TIME.(Tt)
=L/(60-V)
FLOW TYPE
L (£t) =
50 S M =
0.50 GUTTER
L (ft) =
105 S (%) =
4.00 GUTTER
L (ft) =
770 S (%) =
0.50 GUTTER
L (ft) _?
S (%) _?
?
L (ft) _?
S (%) _?
?
L (ft) _?
S (%) _?
?
NOTE: ALL
VELOCITIES TAKEN
FROM FIGURE 3-2
L =
955 L/180+10
15.31 <
Tc =Ti+TOTAL TRAVEL TIME
2 YEAR
10 YEAR
Tc (min)=
15.31
15.31
USE Tc =
15.5
15.5
INTENSITY (I) (iph)
2 YEAR 10 YEAR
I = 2.11 3.70
NOTE: INTENSITIES TAKEN FROM FIGURE
RUNOFF (Q= CIA) (cfs)
2 YEAR 10 YEAR
QINLET = 3.05 5.34
PAGE 12
V (fps) = 1.50
Tt(min)=
0.56-
V (fps) = 4.00
Tt(min)=
0.44
V (fps) = 1.50
Tt(min)=
8.56
V (fps) _?
Tt(min)=
0.00
V (fps) _?
Tt(min)=.
0.00
V (fps) _?
Tt(min)=
0.00
V (fps) _?
Tt(min)=
0.00
TOTAL TRAVEL TIME
(min) =
9.55
16.47 CHOOSE LESSER
100 YEAR
15.31
15.5
100 YEAR
5.98
3-1
100 YEAR
10.79
CONCLUDE:INSTALL 10 FOOT TYPE R INLET SUMP FOR 100 YEAR STORM
CAPACITY PER FOOT (cfs/ft)= 2.45 BASED ON FLOW DEPTH OF 1 FOOT
REDUCTION FACTOR = 90.00%ACTUAL CAPACITY 22.05 CFS
PIPE DIAM. = 2.00 FT. PIPE TYPE = RCP MANNINGS 0.013
SLOPE _ 0.0235 FT/FT SLOPE 0.005 FT/FT
CONVEYANCE FACTOR= 226.22 - REFER TO TABLE 5 ADS MANUAL
CAPACITY = 34.68 CFS
PIPE OVERSIZED FOR OVERFLOW FROM POND 2
INLET SIZED FROM FILING 1
SHEAR ENGINEERING CORPORATION
DEVELOPED
FLOW TO CONCENTRATION POINT D
FROM SUBBASIN 4
PROJECT: HEARTHFIRE PUD DATE 07/14/97
LOCATION:TOWN CENTER COURT PROJ. NO.1552-01-96
FILE: STORM BY MEO
AREA (A)= 8.12 ACRES
RUNOFF CORP. (C)
2 YEAR 10 YEAR 100 YEAR
C = 0.61 0.61 0.77
REFER TO SUBBASIN BREAKDOWN ON PAGE 2
TIME OF CONCENTRATION (TO
OVERLAND TRAVEL TIME (Ti)
LENGTH = 250 FEET SLOPE = 4.00 4
2 YEAR 10 YEAR 100 YEAR
C = 0.20 0.20 0.25
Ti (min)= 16.84 16.84 15.91
TRAVEL TIME (Tt)=L/(60*V) FLOW TYPE
L (ft) = 150 S (6) = 4.00 SWALR
L (ft) = 550 S (%) = 0.50 GUTTER
L (ft) = 235 S 00 = 2.50 GUTTER
L (ft) = 100 S 00 = 0.50 GUTTER
L (ft) _? S 00 _? ?
L (ft) _? S 00 _? ?
L (ft) _? S ($) _? ?
NOTE: ALL VELOCITIES TAKEN FROM FIGURE 3-2
L = 1285 L/180+10 17.14 <
Tc =Ti+TOTAL TRAVEL TIME
2 YEAR 10 YEAR
Tc (min). 17.14 17.14
USE Tc = 17 17
INTENSITY (I) (iph)
2 YEAR 10 YEAR
I = 2.02 3.55
NOTE: INTENSITIES TAKEN FROM FIGURE
PAGE 11
V (fps) = 3.00
Tt(min)=
0.83
V (fps) - 1.50
Tt(min)=
6.11
V (fps) = 3.10
Tt(min)=
1.26
V (fps) = 1.50
Tt(min)=
1.11
V (fps) _?
Tt(min)=
0.00
V (fps) _?
Tt(min)=
0.00
V (fps) _?
Tt(min)=
0.00
TOTAL TRAVEL TIME
(min) =
9.32
25.22 CHOOSE LESSER
100 YEAR
17.14
17
100 YEAR
5.72
3-1
RUNOFF
(Q= CIA) (cfs)
2 YEAR
10 YEAR
100 YEAR
Q
= 10.10
17.71
35.67
QDP-El
= 0.33
0.58
1.15
FLOW
INTERCEPTED AT DP
81
QDP-E2
= 0.50
0.87
6.45
FLOW
INTERCEPTED AT DP
E2
QDP-E3
= 9.47
16.62
31.82
FLOW
INTERCEPTED AT DP
E3
QPIPB
= 10.30
18.07
39.43
SIZE
PIPE
CONCLUDE:SIZE PIPE FROM
DP E1
TO POND FOR
100 YEAR FLOW
PIPE DIAM. =
2.50
FEET .
ADS
MANNINGS N =
0.012
CONVEYANCE FACTOR
=
444.35
SLOPE =
0.0089
FT/FT
CAPACITY
=
41.92 CPS
STREET CAPACITY FROM BACK OF WALK
TO BACK OF
WALK
= 27.50 CPS
FLOW DEPTH AT
FLOWLINE UP TO BACK
OF WALK =
0.57
FEET
SHEAR ENGINEERING CORPORATION
DEVELOPED
PAGE
10
FLOW TO CONCENTRATION POINT
D3
FROM SUBBASIN
4C
PROJECT: HEARTHFIRB PUD
DATE 07/14/97
LOCATION:WEST SIDS TOWN CENTER COURT
PROJ. NO.1552-01-96
FILE: STORM
BY MEO
AREA (A)- 6.88 ACRES
i
RUNOFF COBF. (C)
2 YEAR 10 YEAR
100 YEAR
C 0.68 0.68
0.85
REFER TO SUBBASIN BREAKDOWN ON PAGE
2
TIME OF CONCENTRATION (Tc)
OVERLAND TRAVEL TIME (TO
LENGTH 250 FEET SLOPE = 4.00
It
2 YEAR 10 YEAR
100 YEAR
C = 0.20 0.20
0.25
Ti (min)= 16.84 16.84
15.91
TRAVEL TIME (TO-L/(60*V) FLOW TYPE
.v
L (£S) = 150 S (%) = 4.00 SWALB
V (fps) = 3.00
Tt(min)-
0.83
L (ft) = 550 S (%) = 0.50 GUTTER
V (fps) = 1.50
Tt(min)=
6.11
L (ft) = 235 S (%) - 2.50 GUTTER
V (fps) = 3.10
Tt(min)=
1.26
L (ft) = 100 S (%) = 0.50 GUTTER
V (fps) = 1.50
Tt(min)=
1.11
L (ft) _? S (%) _? ?
V (fps) _?
Tt(min)=
0.00
L (ft) _? S (%) _? ?
V (fps) _?
Tt(min)=
0.00
L (ft) _? S (%) _? ?
V (fps) _?
Tt(min)-
0.00
NOTE: ALL VELOCITIES TAKEN FROM FIGURE
3-2
TOTAL TRAVEL TIME
(min)
9.32
L = 1285 L/180+10. 17.14 <
25.22
CHOOSE LESSER
Tc =Ti+TOTAL TRAVEL TIME
2 YEAR 10 YEAR
100 YEAR
Tc (min)= 17.14 17.14
17.14
USE Tc = 17 17
17
INTENSITY (I),(iph)
2 YEAR 10 YEAR
100 YEAR
I = 2.02 3.55
5.72
NOTE: INTENSITIES TAKEN FROM FIGURE
3-1
RUNOFF (Q= CIA) (cfs)
2 YEAR 10 YEAR
100 YEAR
Q = 9.47 16.62
33.47
DIRECT FLOW TO INLET
QUP = 0.00 0.00
3.75
FLOW FROM DP
D2
QTOTAL = 9.47 16.62
37.22
QINT = 9.47 16.62
31.82
INTERCEPTION
QPASS 0.00 0.00
5.40
-
CONCLUDB:DESIGN FOR 100 YEAR STORM FROM FIGURE
5-5
Q Sx T
Dw n
S
37.22 0.02 15 0.26
0.016
0.005
22 FOOT INLET REQUIRED FOR
100% INTERCEPTION
INSTALL 15 FOOT INLET
Qi/Q -
0.95
THEORETICAL INLET CAPACITY =
35.36
CFS
REDUCTION FACTOR = 90.00%ACTUAL CAPACITY =
31.82 CPS
SHEAR ENGINEERING CORPORATION
DEVELOPED
FLOW TO CONCENTRATION POINT D2
FROM SUBBASIN 4B
PROJECT: HEARTHFIRE PUD DATE 07/14/97
LOCATION:WEST SIDE TOWN CENTER COURT PROS. NO.1552-01-96
FILE: STORM BY MEO
AREA (A)= 1.04 ACRES
RUNOFF CORP. (C)
2 YEAR 10 YEAR 100 YEAR
C = 0.24 0.24 0.30
REFER TO SUBBASIN BREAKDOWN ON PAGE 2
TIME OF CONCENTRATION (TO
OVERLAND TRAVEL TIME (Ti)
LENGTH = 250 FEET SLOPE = 4.00 $
2 YEAR 10 YEAR 100 YEAR
C = 0.20 0.20 0.25
Ti (min)= 16.84 16.84 15.91
TRAVEL
TIME (It)
-L/(60+V)
FLOW TYPE
L (ft)
= 150
S ($) =
4.00
SWALE
L (ft)
= 550
S ($) =
0.50
GUTTER
L (£t)
= 235
S ($) =
2.50
GUTTER
L (ft)
= 100
S ($) =
0.50
GUTTER
L (ft)
_?
S ($) _?
?
L (ft)
_?
S ($) _?
?
L (ft)
_?
S ($) _?
?
NOTE:
ALL VELOCITIES TAKEN
FROM
FIGURE 3-2
L =
1285
L/180+10
17.14
<
Tc =Ti+TOTAL TRAVEL TIME
2 YEAR
10
YEAR
100 YEAR
Tc (min)=
17.14
17.14
17.14
USE Tc
= 17
17
17
PAGE
V (fpe) = 3.00 Tt(min)=
V (fps) = 1.50 Tt(min)=
V (fps) = 3.10 Tt(min)=
V (fps) = 1.50 Tt(min)=
V (fps) _? Tt(min)=
V (fps) _? Tt(min)=
V (fps) _? Tt(min)=
TOTAL TRAVEL TIME (min) _
25.22 CHOOSE LESSER
INTENSITY (I) (iph)
2 YEAR SO YEAR 100 YEAR
I = 2.02 3.55 5.72
NOTE: INTENSITIES TAKEN FROM FIGURE 3-1
RUNOFF (Q= CIA) (cfe)
2 YEAR 10 YEAR 100 YEAR
QINLET = 0.50 0.87 1.76
QUP = 0.00 0.00 5.40 FLOW FROM DP E3
QTOTAL 0.50 0.87 7.15 TOTAL FLOW TO INLET
QINT = 0.50 0.87 6.45 INTERCEPTION
QPASS = 0.00 0.00- 0.70
CONCLUDE:DESIGN FOR 100 YEAR STORM FROM FIGURE 5-5
Q Sx T S Dw n
7.15 0.02 15 0.005 0.26 0.016
22 FOOT INLET REQUIRED FOR 100% INTERCEPTION
INSTALL 20 FOOT INLET Qi/Q = 0.95
THEORETICAL INLET CAPACITY = 6.79 CPS
REDUCTION FACTOR = 95.00$ACTUAL CAPACITY = 6.45 CPS
9
0.83
6.11
1.26
1.11
0.00
0.00
0.00
9.32
SHEAR ENGINEERING CORPORATION
DEVELOPED
FLOW TO CONCENTRATION POINT D1
FROM SUBBASIN 4A
PROJECT: HEARTHFIRE PUD DATE 07/14/97
LOCATION:EAST SIDE TOWN CENTER COURT PROJ. NO.1552-01-96
FILE: STORM BY MEO
AREA (A)= 0.20 ACRES
RUNOFF CORP. (C)
2 YEAR 10 YEAR 100 YEAR
C 0.81 0.81 1.00
REFER TO SUBBASIN BREAKDOWN ON PAGE 2
TIME OF CONCENTRATION (Tc)
OVERLAND TRAVEL TIME (Ti)
LENGTH 250 FEET SLOPE 4.00 t
2 YEAR 10 YEAR 100 YEAR
C = 0.20 0.20 0.25
Ti (min)= 16.84 16.84 15.91
TRAVEL TIME
(Tt)
=L/(60*V)
PLOW TYPE
L (ft)
150
S (t) =
4.00
SWALE
L (ft) =
550
S ($) =
0.50
GUTTER
L (ft) =
235
S (%) =
2.50
GUTTER
L (ft) =
100
S (t) =
0.50
GUTTER
L (ft) _?
S (t) _?
?
L (ft) _?
S (t) _?
?
L (ft) _?
S (t) _?
?
NOTE: ALL
VELOCITIES TAKEN
FROM
FIGURE 3-2
L =
1285
L/180+10
17.14
<
Tc =Ti+TOTAL
TRAVEL TIME
2
YEAR
10
YEAR
100 YEAR
Tc (min)=
17.14
17.14
17.14
USE Tc =
17
17
17
PAGE
V (fps) 3.00 Tt(min)=
V (fps) 1.50 Tt(min)=
V (fps) = 3.10 Tt(min)=
V (fps) = 1.50 Tt(min)=
V (fps) _? .Tt(min)=
V (fps) _? Tt(min)=
V (fps) _? Tt(min)=
TOTAL TRAVEL TIME (min) _
25.22 CHOOSE LESSER
INTENSITY (I) (iph)
2 YEAR 10 YEAR 100 YEAR
I 2.02 3.55 5.72
NOTE: INTENSITIES TAKEN FROM FIGURE 3-1
RUNOFF (Q= CIA) (cfs)
2 YEAR
10 YEAR
100 YEAR
Q
0.33
0.58
1.15
QINT
0.33
0.58
1.04 INTERCEPTED FLOW
QPASS
= 0.00
0.00
0.12
CONCLUDE:DESIGN
FOR
100 YEAR STORM FROM FIGURE 5-5
Q Sx
T
S Dw n
1.15 0.02
7.5
0.005 0.11 0.016
10 FOOT.INLRT REQUIRED
FOR 100% INTERCEPTION
INSTALL 20
FOOT INLET
Qi/Q = 1
INLET CAPACITY =
1.15 REDUCTION FACTOR = 90.00t
ACTUAL CAPACITY =
1.04 CPS
PIPE MATL
n
SLOPE C CAPACITY
2.5 ADS
0.012
0.0089 444.35 41.92
PIPS AND INLET ARE
OVERSIZED
FOR UPSTREAM FLOWS
8
0.83
6.11
1.26
1.11
0.00
0.00
0.00
9.32
SHEAR ENGINERING
DEVELOPED
FLOW TO CONCENTRATION POINT
FROM SUBBASIN 3
PROJECT: HEARTHFIRE PUD SECOND FILING
LOCATION:TOWN CENTER COURT
FILE: STORM
AREA (A)= 2.00 ACRES
RUNOFF COEF. (C)
2 YEAR 10 YEAR 100 YEAR
C = 0.74 0.74 0.93
REFER TO SUBBASIN BREAKDOWN ON PAGE 2
TIME OF CONCENTRATION (TO
OVERLAND TRAVEL TIME (TO
LENGTH = 40 FEET SLOPE 1.00 6
2 YEAR 10 YEAR 100 YEAR
C = 0.20 0.20 0.25
Ti (min)= 10.64 10.64 10.05
TRAVEL TIME
(TO
=L/(60*V)
FLOW TYPE
L (ft) =
520
S M =
0.50
GUTTER
L (ft) =
230
S (4) -
4.00
GUTTER
L (ft)
100
S (M) =
2.00
GUTTER
L (ft) =
100
S (i) =
5.00
GUTTER
L (£t) _?
S (!) _?
?
L (ft) _?
S (4) _?
?
L (ft) _?
S (6) _?
?
NOTE: ALL
VELOCITIES TAKEN
FROM
FIGURE 3-2
L =
990
L/180+10
15.50
<
Tc -Ti+TOTAL
TRAVEL TIME
2
YEAR
SO
YEAR
100 YEAR
Tc (min)=
15.50
15.50
15.50
USE Tc -
15.5
15.5
15.5
DATE 07/14/97
PROD. NO.1552-02-97
BY MEO
PAGE
V (fps) = 1.50 Tt(min)=
V (fps) = 4.00 Tt(min)=
V (fps) - 2.83 Tt(min)=
V (fps) 4.45 Tt(min)=
V (fps) _? Tt(min)=
V (fps) _? Tt(min)=
V (fp0) _? Tt(min)=
TOTAL TRAVEL TIME (min) _
17.75 CHOOSE LESSER
INTENSITY (I) (iph)
2 YEAR 10 YEAR 100 YEAR
I = 2.11 3.70 5.98
NOTE: INTENSITIES TAKEN FROM FIGURE 3-1
RUNOFF (Q= CIA) (cfo)
2 YEAR 10 YEAR 100 YEAR
QTOTAL 3.14 5.50 11.10
QDPD1 = 0.67 1.18 1.83 FLOW INTERCEPTED AT DP
QDPD2 2.46 4.32 4.97 FLOW INTERCEPTED AT DP
QINT 3.14 5.50 6.80 TOTAL INTERCEPT
QPASS = 0.00 0.00 4.30
CONCLUDS:SIZE PIPE FROM DP D1 FOR 100 YEAR STORM =
PIPE DIAM. = 1.50 FEET ADS
MANNINGS N = 0.012 CONVEYANCE FACTOR = 113.8
SLOPS = 0.010 FT/FT CAPACITY = 11.38 CPS
STREET CAPACITY FROM BACK OF WALK TO BACK OF WALK = 86.99 CPS
FLOW DEPTH AT FLOWLINE UP TO BACK OF WALK = 0.57 FEET
DI
D2
6.80 CFS
7
5.78
0.96
0.59
0.37
0.00
0.00
0.00
7.70
SHEAR ENGINEERING CORPORATION
DEVELOPED
PLOW TO CONCENTRATION POINT C2
FROM SUBBASIN 3B
PROJECT: HEARTHFIRE PUD SECOND PILING DATE 07/14/97
LOCATION:WEST SIDE TOWN CENTER COURT PROJ. NO.1552-02-97
FILE: STORM BY MBO
AREA.(A)= 1.616 ACRES
RUNOFF COBF. (C)
2 YEAR 10 YEAR 100 YEAR
C = 0.72 0.72 0.90
REFER TO SUBBASIN BREAKDOWN ON PAGE 2
TIME OF CONCENTRATION (Tc)
OVERLAND TRAVEL TIME (Ti)
LENGTH = 40 FEET SLOPE = 1.00 i
2 YEAR 10 YEAR 100 YEAR
C = 0.20 0.20 0.25
Ti (min)= 10.64 10.64 10.05
TRAVEL TIME (Tt)=L/(60*V) FLOW TYPE
L (ft) = 520 S (%) = 0.50 GUTTER
L (ft) = 230 S (%) = 4.00 GUTTER
L (ft) _ 100 S (14) = 2.00 GUTTER
L (ft) = 100 S M = 5.00 GUTTER
L (ft) _? S (14) _? 7
L (ft) _? S (1k) _? ?
L (ft) _? S (t) _? ?
NOTE: ALL VELOCITIES TAKEN FROM PIGURE 3-2
L = 990 L/180+10 15.50 <
Tc =Ti+TOTAL TRAVEL TIME
2 YEAR 10 YEAR
Tc (min)= 15.50 15.50
USE Tc = 15.5 15.5
INTENSITY (I) (iph)
2 YEAR 10 YEAR
I 2.11 3.70
NOTE: INTENSITIES TAKEN FROM FIGURE
RUNOFF (Q= CIA) (Cfs)
2 YEAR
QINLET 2.46
QINT 2.46
QPASS = 0.00
CONCLUDE:DRSIGN FOR
Q Sx
8.72 0.02
PAGE
V (fps) = 1.50 Tt(min)=
V (fps) = 4.00 Tt(min)=
V (fps) = 2.83 Tt(min)=
V (fps) = 4.45 Tt(min)=
V (fps) _? Tt(min)=
V (fps) _? Tt(min)=
V (fps) _? Tt(min)=
TOTAL TRAVEL TIME (min) _
17.75 CHOOSE LESSER
100 YEAR
15.50
15.5
100 YEAR
5.96
3-1
10 YEAR 100 YEAR
4.32 8.72
4.32 4.97 INTERCEPTED FLOW
0.00 3.75 BYPASS FLOW TO DP E3
100 YEAR STORM FROM FIGURE 5-5
T S Dw n
13.5 0.05 0.23
6
5.78
0.96
0.69
0.37
0.00
0:00
0.00
7.70
SHEAR ENGINEERING CORPORATION
DEVELOPED
FLOW TO CONCENTRATION POINT C1
FROM SUBBASIN 3A
PROJECT: HEARTHFIRE PUD SECOND FILING DATE 07/14/97
LOCATION:EAST SIDE TOWN CENTER COURT PROJ. NO.1552-02-97
FILE: STORM BY MHO
AREA (A)= 0.38 ACRES
RUNOFF COEF. (C)
2 YEAR 10 YEAR 100 YEAR
C = 0.84 0.84 1.00
REFER TO SUBBASIN BREAKDOWN ON PAGE 2
TIME OF CONCENTRATION (TO
OVERLAND TRAVEL TIME (Ti)
LENGTH = 40 FEET SLOPE = 1.00 4
2 YEAR 10 YEAR 100 YEAR
C = 0.20 0.20 0.25
Ti (min)= 10.64 10.64 10.05
TRAVEL TIME (TO=L/(60+V) FLOW TYPE
L (ft) = 520 S (4) - 0.50 GUTTER
L (ft) = 230 S = 4.00 GUTTER
L (ft) = 100 S (%) = 2.00 GUTTER
L (ft) = 100 S ($) = 5.00 GUTTER
L (ft) _? S _? ?
L (ft) _? S (4) _? ?
L (ft) _? S (t) _? ?
NOTE: ALL VELOCITIES TAKEN FROM FIGURE 3-2
L = 990 L/180+10 15.50 <
Tc =Ti+TOTAL TRAVEL TIME
2 YEAR 10 YEAR
Tc (min)= 15.50 15.50
USE Tc = 15.5 15.5
INTENSITY (I) (iph)
2 YEAR 10 YEAR
I = 2.11 3.70
NOTE: INTENSITIES TAKEN FROM FIGURE
PAGE
V (fps) = 1.50 Tt(min)=
V (fps) = 4.00 Tt(min)=
V (fps) = 2.83 Tt(min)=
V (fps) = 4.45 Tt(min)=
V (fps) _? Tt(min)=
V (fps) _? Tt(min)=
V (fps) _? Tt(min)=
TOTAL TRAVEL TIME (min) _
17.75 CHOOSE LESSER
100 YEAR
15.50
15.5
100 YEAR
5.98
3-1
RUNOFF (Q= CIA) (cfa)
2 YEAR 10 YEAR 100 YEAR
QINLRT = 0.67 1.18 2.27
QINT = 0.67 1.18 1.83 INTERCEPTED FLOW
QPASS 0.00 0.00 0.44 BYPASS FLOW TO DP B
CONCLUDE:DESIGN FOR 100 YEAR STORM FROM FIGURE 5-5
Q Sx T S Dw n
2.27 0.02 7.5 0.05 0.11 0.016
30 FOOT INLET REQUIRED FOR 100% INTERCEPTION
INSTALL 20 FOOT INLET Qi/Q = 0.85
INLET CAPACITY = 1.93 REDUCTION FACTOR = 95.00%ACTUAL CAPACITY =
PIPE MAIL n SLOPE C CAPACITY
1.5 ADS 0.012 0.0100 113.8 11.38 FEET
5
5.78
0.96
0.59
0.37
0.00
0.00
0.00
7.70
1.83
SHEAR ENGINEERING CORPORATION
PAGE 4 A
CHANNEL CAPACITY -AT EAST END OF BUNTWING
PROJECT NAME: HEARTHFIRE PUD 2ND FILING DATE: 07/14/97
PROJECT NO. : 1552-02-97 BY : MEO
SWALB DESCRIPTION:BUNTWING COURT FILE: STORM
CAPACITY OF TRIANGULAR OR TRAPEZOIDAL CHANNEL
CHANNEL CONFIGURATION: TRAPEZOIDAL Q100 (cfe) = 0.57
CHANNEL LINING: GRASS 1.33*Q100 (cfe) 0.76
Da Db Dc Sc n W I
(ft) (ft) (ft) (t) (ft) (ft)
---- ---- ---- ----- ---- ----
2.00 2.00 0.50 2.00 0.0320 2.00 6.20
0.25 FT/FT = LEFT BANK SLOPE 4.00 :11(H:V)
0.25 FT/FT = RIGHT BANK SLOPE 4.00 :1 (H:V)
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(s.f.) (ft) (s.f.) (ft) (A/P) (cfe) (ft/eec)
------------------------------------------------- -------
0.50' 6.00 2.00 6.12 0.47 0.14 6.23 3.11
0.30 4.40 0.96 4.47 0.36 0.14 2.26 2.35
0.10 2.80 0.24 2.82 0.19 0.14 0.30 1.27
0.00 2.00 0.00 2.00 0.00 0.14 0.00 0.00
0.00 2.00 0.00 2.00 0.00 0.14 0.00 0.00
0.00 2.00 0.00 2.00 0.00 0.14 0.00 0.00
0.17 3.36 0.46 3.40 0.26 0.14 0.76 1.72
r rrx+rxrrxtr+rrrrrrrr+xx+rr+rrrrrr rrrrrrrx+r+rr+rr+rx+x+r++rx++++++rr++r
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(s.f.) (ft) (s.f.) (ft) (A/P) (cfe) (ft/sec)
FLOW DEPTH FOR THE DESIGN FLOW IS APPROXIMATELY 0.17 FEET
FREEBOARD IN CHANNEL - 0.33 FEET
CONCLUDE:CHANNEL WILL BE ADEQUATE
SHEAR ENGINEERING CORPORATION
DEVELOPED
FLOW TO CONCENTRATION POINT B
FROM SUBBASIN 2
PROJECT: HEARTHPIRE PUD SECOND FILING DATE 07/14/97
LOCATION:BUNTWING COURT PROJ. NO.1552-02-97
FILE: STORM BY HBO
AREA (A)= 0.90 ACRES
RUNOFF CORP. (C)
2 YEAR 10 YEAR 100 YEAR
C = 0.78 0.78 0.98
REFER TO SUBBASIN BREAKDOWN ON PAGE 2
TIME OF CONCENTRATION (TO
OVERLAND TRAVEL TIME (TO
LENGTH = 40 FEET SLOPE = 1.00 ft
2 YEAR 10 YEAR 100 YEAR
C = 0.20 0.20 0.25
Ti (min). 10.64 10.64 10.05
TRAVEL TIME
(Tt)
=L/(60*V)
FLOW TYPE
L (ft) =
50
S (t) =
5.00
GUTTER
L (ft) =
30
S 00 =
2.50
GUTTER
L (ft) =
140
S 00 =
1.00
GUTTER
L (ft) =
160
S ($) =
0.50
GUTTER
L (ft) _?
S (6) _?
?
L (ft) _?
S (%) _?
?
L (ft) _?
S M _?
?
NOTE: ALL
VELOCITIES TAKEN
FROM FIGURE 3-2
.L -
420
L/180+10
12.33
<
Tc -Ti+TOTAL
TRAVEL TIME
2
YEAR
10
YEAR
100
YEAR
Tc (min)=
12.33
12.33
12.33
USE Tc =
12.5
12.5
12.5
PAGE
V (fps) = 4.45 Tt(min)=
V (fps) = 3.10 Tt(min)=
V (fps) = 2.00 Tt(min)=
V (fps) = 1.50 Tt(min)=
V (fps) _? Tt(min)=
V (fps) _? Tt(min)=
V (fps) _? Tt(min)=
TOTAL TRAVEL TIME (min) _
13 .35 CHOOSE LESSER
INTENSITY (I) (iph)
2 YEAR 10 YEAR 100 YEAR
I 2.34 4.10 6.60
NOTE: INTENSITIES TAKEN FROM FIGURE 3-1
4
0.19
0.16
1.17
1.78
0.00
0.00
0.00
3.29
RUNOFF (Q= CIA) (cfs)
2 YEAR 10 YEAR 100 YEAR
Q = 1.65 2.90 5.83
QUP = 0.00 0.00 0.44 FLOW FROM DP D1
QTOTAL = 1.65 2.90 6.27
QOVER = 0.00 0.00 0.57 OVERFLOW SWALE
CONCLUDE:DESIGN FOR 10 YEAR STORM
INSTALL 5 FOOT TYPE R INLET IN SUMP CONDITION
CAPACITY PER FOOT (cfs/ft)= 1.34 BASED ON FLOW DEPTH OF 0.57 FOOT
ABDUCTION FACTOR = 85.00}ACIUAL CAPACITY = 5.70 CPS
PIPE DIAM. = 1.50 FT. PIPE TYPE = ADS
SLOPS = 0.010 PT/FT MANNINGS n = 0.012
CONVEYANCE FACTOR= 113.8 - REFER TO TABLE 4 ADS MANUAL -
CAPACITY = 11.38 CPS SEE PAGE 4 A FOR OVERFLOW CHANNEL
SHEAR ENGINEERING CORPORATION
PAGE 3 A
CHANNEL CAPACITY -AT SOUTH END OF PONDVIEW
PROJECT NAME: HEARTHFIRE PUD 2ND FILING DATE: 01/00/00
PROJECT NO. : 1552-02-97 BY : MEO
SWALE DESCRIPTION: PONDVIEW COURT FILE: STORM
CAPACITY OF TRIANGULAR OR TRAPEZOIDAL CHANNEL
CHANNEL CONFIGURATION: TRAPEZOIDAL Q100 (cfe) = 0.12
CHANNEL LINING: GRASS 1.33rQ100 (cfe) = 0.16
Da Db Dc Sc n W I
(ft) (ft) (ft) (11) (ft) (ft)
---- ---- ---- ---- ----- ---- ----
2.00 2.00 0.50 2.00 0.0320 2.00 0.10
0.25 FT/FT = LEFT BANK SLOPE 4.00 :1 (H:V)
0.25 FT/FT = RIGHT BANK SLOPE 4.00 :1 (H:V)
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(e.f.) (ft) (s.f.) (ft) (A/P) (cfe) (ft/sec)
-------------- ----------------------------------- -------
0.50 6.00 2.00 6.12 0.47 0.14 6.23 3.11
0.40 5.20 1.44 5.30 0.42 0.14 3.97 2.76
0.30 4.40 0.96 4.47 0.36 0.14 2.26 2.35
0.20 3.60 0.56 3.65 0.29 0.14 1.05 1.88
0.10 2.80 0.24 2.82 0.19 0.14 0.30 1.27
0.00 2.00 0.00 2.00 0.00 0.14 0.00 0.00
0.07 2.56 0.16 2.58 0.16 0.14 0.16 1.03
xtx+++++++++++rr+r+rt+ttrtrtrtrrtrrr+rrtxrtrrrtrtertxrtr+rxr+++++++++r+rrr+r++rr
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(e.f.) (ft) (a.f.) (ft) (A/P) (cfe) (ft/sec)
FLOW DEPTH FOR THE DESIGN FLOW IS APPROXIMATELY 0.07 FEET
FREEBOARD IN CHANNEL = 0.43 FEET
CONCLUDE: CHANNEL WILL BE ADEQUATE
SHEAR ENGINEERING CORPORATION
PAGE 2
SUBBASIN BREAKDOWN
PROJECT: HEARTHFIRE PUD 2ND FILING DATE: 07/14/97
PROJECT NO 1552-02-97 BY MHO
FILE: STORM OPEN SPACE TRACTS
TRACT AREA AREA
PLAITED AREA SF ACRES
HEARTHFIRE 39.31 ACRES A 66265 1.52
i
OPEN SPACE* 8.28 ACRES B 120913 2.78
C 22193 0.51
ASSUME SINGLE FAMILY LOTS ON THE SITE ARE D 112866 2.59
60.00%IMPERVIOUS - ROOF AND DRIVES B 38523 0.88
40.00%PERVIOUS - LAWN 360760 8.28
1 SQ INCH 65 SCALE: 1 INCH 100 IM-
PERVIOUS PERVIOUS
PLANI OPEN ROADS ROOF/ LAWN C2 C100
SUB- METER SF ACRES SPACE DRIVES
BASIN READING 0.20 0.95 0.95 0.20
ACRES ACRES ACRES ACRES
t+r+rrr+xxrrxr++rrr+rrrxrrrrrrrrrrrrr+r++rrxrxrrrrar+rrt+rx+rrxxr+r+rxrxrxrrrrrttr r+rr+rrr
1 222 34154 0.78 0.00 0.34 0.27 0.18 0.78 0.98
2 255.5 39308 0.90 0.00 0.40 0.30 0.20 0.78 0.98
3 565 86923 2.00 0.00 0.63 0.82 0.55 0.74 0.93
4 2299 353692 8.12 1.21 0.85 3.64 2.42 0.61 0.77
5 766 117846 2.71 0.00 0.84 1.12 0.75 0.74 0.93
6 2554 392923 9.02 3.30 0.00 3.77 1.95 0.51 0.64
7 2964 456000 10.47 3.78 0.03 4.38 2.28 0.52 0.64
e 1503 231231 5.31 0.00 0.00 1.06 4.25 0.35 0.44
rr+rrrxrxxxrrr+rrrrrr+rrrtr++r++r+rrxxrxxrx++x++r+rr+rrrrrr++rrrrr+rxr++xxrxr+rrr+rrr+rr+r
SUBTOTAL 1712077 39.30 8.29 3.09 15.35 12.57 0.55 0.69
IM-
PERVIOUS PERVIOUS
PLANI OPEN ROADS ROOF/ LAWN C2 C100
MINOR METER SF ACRES SPACE DRIVES
BASIN READING 0.20 0.95 0.95 0.20
ACRES ACRES ACRES ACRES
r+rxxxxr++r+++r++rr+rxxxx+r++r++rr++xr+xrxrrx+rr+rr+r+++rxrr+rr+rrr+rrr+xxrxr+ree+xrr+xx+x
3A 107.5 16538 0.38 0.00 0.24 0.08 0.06 0.84 1.00
3B 457.50 70385 1.62 0.00 0.39 0.74 0.49 0.72 0.90
4A 57 8769 0.20 0.00 0.11 0.05 0.04 0.81 1.00
4B 294 45231 1.04 0.99 0.05 0.00 0.00 0.24 0.30
4C 1949 299846 6.88 0.00 0.69 3.72 2.48 0.68 0.85
SA 548 84308 1.94 0.00 0.62 0.79 0.53 0.75 0.93
SE 218 33538 0.77 0.00 0.22 0.33 0.22 0.74 0.92
FLOW SUMMARY
FOR STORM SEWER DESIGN IN
PAGE
1
HEARTHFIRE PUD SECOND FILING
DATE
07/14/97
DESIGN
CONTRIBUTING
AREA C2
C10
C100
Tc
Tc I2
I10
I100
Q2
Q10
Q100
DESIGN
PAGE
POINT
SUB
2,10
100
BASIN(S)
ac.
min.
min iph
iph
iph
cfe
cfs
cfs
r rrrrr+rr+r++r+r+r+rrrrrrrrrtrxrxxxtxrxxxrrxxxrrrrr+r+rx+xtx+r+rrxxr+rr
rrrr++++++rrrrrrrrrrrrrrrrrrrrr
DEVELOPED
FLOWS
FOR STORM SEWER IN
SUB -BASIN
1
TO POND 2
A
1
0.78 0.78
0.78
0.98
13.00
13.00 2.30
4.03
6.49
1.41
2.46
4.96
I/P
3
DEVELOPED
FLOWS
FOR STORM SEWER IN
SUB -BASIN
2
B
2
0.90 0.78
0.78
0.98
12.50
12.50 2.34
4.10
6.60
1.65
2.90
5.83
I/P
4
DEVELOPED FLOWS
FOR STORM SEWER IN
SUB -BASIN
4
TO POND 2
CI
3A
0.38 0.84
0.84
1.00
15.50
15.50 2.11
3.70
5.98
0.67
1.18
2.27
I/P
5
C2
3B
1.62 0.72
0.72
0.90
15.50
15.50 2.11
3.70
5.98
2.46
4.32
8.72
I/P
6
C
3
2.00 0.74
0.74
0.93
15.50
15.50 2.11
3.70
5.98
3.14
5.50
11.10
PIPE
7
DEVELOPED
FLOWS
FOR STORM SEWER IN
SUB -BASIN
5
TO POND 2
D1
4A
0.20 0.81
0.81
1.00
17.00
17.00 2.02
3.55
5.72
0.33
0.58
1.15
I/P
8
D2
4B
1.04 0.24
0.24
0.30
17.00
17.00 2.02
3.55
5.72
0.50
0.87
1.76
I/P
9
D3
4C
6.88 0.68
0.68
0.85
17.00
17.00 2.02
3.55
5.72
9.47
16.62
33.47
I/P
10
D
4
8.12 0.61
0.61
0.77
17.00
17.00 2.02
3.55
5.72
10.10
17.71
35.67
PIPE'
11
DEVELOPED FLOWS
FOR STORM SEWER IN
SUB -BASIN
6
TO RICHARDS
LAKE
E1
5A
1.94 0.75
0.75
0.93
15.50
15.50 2.11
3.70
5.98
3.05
5.34
3.05
I/P
12
82
5B
0.77 0.74
0.74
0.92
13.00
13.00 2.30
4.03
6.49
1.30
2.28
4.60
I
13
E
5
2.71 0.74
0.74
0.93.
15.50
15.50 2.11
3.70
5.98
4.24
7.44
15.02
PIPE
14
DESIGN
DESIGN
STORM
PIPE DESIGNINLET
OG
CAPA-
PIPE RCP/
SLOPE
CAPA-
POINT
INLET Q
SIZE
CITY
DIAM ADS
CITY
year
BOTH cfe
ft
SUMP
cfe
ft
ft/ft
cfe
rrr+r+rrrr+rtrtrtrrt+trrrrrr++rt++++++rrr+++++r+r++r+++++r+rrrrr+++++rr+++++++rrrrrx+rrrrrttx+.
..
PROFILE
A
PONDVIEW COURT
A
10
BOTH 4.96
5
SUMP
4.85
1.50 ADS
0.060
27.88
PROFILE
B
BUNTWING COURT
B
10
BOTH 6.27
5
SUMP
5.70
1.50 ADS
0.010
11.38
PROFILE
C
TOWN CENTER
DRIVE
@ TRACTS E & C
Cl
100
INLET 2.27
20
OG
1.83
C2
100
BOTH 8.72
20
OG
4.97
1.50 RCP
0.010
10.50
C
100
PIPE 6.80
1.50 ADS
0.010
11.38
PROFILE
D
TOWN CENTER
DRIVE
i4 TRACT A &
C
D1
100
INLET 1.15
20
OG
1.04
D2
100
INLET 7.15
20
OG
6.45
D2
100
PIPE 38.27
2.50 RCP
0.009
38.70
D3
100
BOTH 37.22
15
OG
31.82
2.50 RCP
0.009
38.70
D
100
PIPE 39.43
2.50 ADS
0.009
41.92
PROFILE
E
TOWN CENTER
DRIVE
- FILING 1
E1
100
INLET 10.79
10
SUMP
22.05
2.00 RCP
0.024
34.68
E2
100
INLET 16.69
10
SUMP
22.05
2.00 ADS
0.024
37.57
Storm Sewer Design Flows
APPENDIX I
Drainage Calculations
Page 11
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
VII. VARIANCE FROM CITY STANDARDS
A. Variance from City of Fort Collins requirements
1. There will be no requests for variances from City of Fort Collins Stormwater Utility
Standards.
VIH. CONCLUSIONS
A. Compliance With Standards
1. The grading and drainage design for Hearthfire P.U.D., Second Filing is in
compliance with the City of Fort Collins storm drainage design criteria.
2. The erosion control measures shown on the erosion control plan comply with the City
of Fort Collins standards and generally accepted erosion control practices.
B. Drainage Concept
1. The proposed drainage design for Hearthfire P.U.D., Second Filing is effective for the
control of storm runoff with a considerable reduction in potential downstream effects."
IX REFERENCES
1. City of Fort Collins "Storm Drainage Design Criteria and Construction Standards';
May, 1984, revised May, 1997
2. City of Fort Collins "Erosion Control Reference Manual"; January, 1991
3. Preliminary Drainage and Erosion Control Report for Hearthfire at Richards Lake;
Prepared by Merrick & Company; Project No. 15011782; Dated July 10,1996
4. Urban Runoff Mitigation for Hearthfire PUD, TR Boss Environmental and Biological
Consulting; Dated November 1996
5. Wetland Mitigation Report for Hearthfire P.U.D.; TR Boss Environmental and
Biological Consulting; Dated November 1996
Page 10
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
V. WATER QUALITY
B. Specific Details
2. The water quality diffuser will intercept the initial flush and divert to the gravel drains
on either side of the drain basin. When the capacity of the gravel drain is reached the
remaining stormwater will flow through the drain basin to pond 2 where the wetlands
will filter much of the remaining nutrients in the stormwater.
VI. EROSION CONTROL:
A. General Concept
1. Erosion control measures are specified on the Drainage and Erosion Control Plan.
a. Maintenance of erosion control devices. will remain. the responsibility of the
contractor and the owner until the project is complete.
B. Specific Details
1. The following temporary measures are specified on the Drainage and Erosion Control
plan:
a. Area inlet filters composed of haybales around all area inlets .
b. Silt fence along the downstream property lines.
c. Gravel inlet filters at all storm sewer inlets.
d. Haybale dikes within all swales.
2. The following permanent measures are specified on the Drainage and Erosion Control
plan:
a. Buried riprap aprons at all storm sewer outfalls
b. Riprap to have a Dso of 12"
c. Minimum length of riprap apron is 40 feet
d. Minimum width of the riprap apron will be 5.0 feet for 18" pipe and 6.0 feet for
24" pipe.
Page 9
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
IV DRAINAGE FACILITY DESIGN
B. Specific Details -Swales
1. Overflow swales are provided at the end of the Pondview and Buntwing Courts. The
swale is designed to convey the overflow generated by the 100-year storm at the
inlets. The design flow is 1.33 x the Q100.
The following table summarizes the design of the overflow swales.
DP Q100
Depth
Bottom
SS
Mannings
Swale Section
Width
(H:V)
n
Capacity
cfs
ft.
ft.
ft:ft
cfs
A 0.12
0.5
2
4:1
0.032
6.23 A -A
B 0.57
0.5
2.0
4:1
0.032
6.23 B-B
V. WATER QUALITY
A. General Concept
1. Water quality measures are specified in the Water Quality and Wetland Mitigation
Report prepared by Ted Boss, PH.D. A copy of this report is on file in the office of
Stormwater Utility
a. Maintenance of water quality will be the responsibility of the contractor and the
owner until the project is complete. The Homeowners Association will be
responsible upon completion of the construction.
B. Specific Details
1. A water quality diffuser will be installed at all storm sewer outfalls into the pond 2.
The diffuser will consist of the following;
a. An 18" or 24" ADS Drain Basin will be installed just before the Flared End
Section (FES) of the outfall. A different detail is provided with larger pipes.
b. Forty (40) lineal feet of 6" perforated ADS pipe will be extended out of either side
of the drain basin. The invert of the 6" pipe will be one (1.0') foot lower than the
invert of the storm sewer.
c. The 6" pipe will be surrounded by 6" of 3/4" clean gravel with Mirafi Filter
Fabric or equivalent on the top and the two (2) sides of the 6" pipe.
d. The FES will be attached to the downstream end of the drain basin.
e. 40 lineal feet of buried riprap with a D,o of 12" will be installed at each outfall.
f.. Riprap aprons will be 5.0 feet for 18" pipe and 6.0 feet for larger pipes.
Page 7
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
IV DRAINAGE FACILITY DESIGN
B. Specific Details - Storm Sewer
3. Storm sewer B located on Town Center Drive north of Buntwing Court will consist
of the following;
a. 1 - 20' Type R inlet in continuous grade condition on the west side of Town
Center Drive.
b. 31.33 LF of 18 " RCP pipe.
c. 1 - 20' Type R inlet in continuous grade condition on the east side of Town Center
Drive.
d. 300 LF of 18 " HDPE pipe ( ADS N-12 or approved equal) with FES.
e. An 18 "ADS N-12 Drain Basin for Water Quality
4. Storm sewer C located at the low point on Buntwing Court will consist of the
following;
a. 5' Type R inlet in sump condition
b. 140 LF of 18 " HDPE pipe ( ADS N-12 or approved equal) with FES.
c. An 18 "ADS N-12 Drain Basin for Water Quality
d. Overflow Swale
5. Storm sewer D located on Town Center Drive south of Buntwing Court will consist
of the following;
a. 1 - 15' Type R inlet in continuous grade condition on the west side of Town
Center Drive.
b. 65 LF of 30 " RCP pipe.
c. 2 - 20' Type R inlets in continuous grade condition on the east and west side of
Town Center Drive.
d. 31.33 LF of 30 " RCP pipe.
e. 500 LF of 30 " HDPE pipe ( ADS N-12 or approved equal) with FES.
Page 6
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
IV DRAINAGE FACILITY DESIGN
A. General Concept
1. The majority of the site (sub -basins 1-4) will be contributing stormwater to the
wetland / pond areas (Pond 2) via a combination of
a. overland flow
b. gutter flow
c. storm sewer flow
The grading of the site attempts to divert as much of the runoff into the wetland areas
as possible.
2. Sub -basins 5-7 will contribute stormwater directly to Richard Lake or Douglas Road
via the same methods of conveyance mentioned previously. Sub-basin:8 contributes
stormwater to pond 1.
3. Water quality is addressed in the design of the outfalls of the storm sewer into
Richards Lake. Refer to the Wetlands Mitigation Report prepared by TR. Boss .
Associates. Water Quality details coincide with the recommendations of the report.
4. Emergency overflow structures were designed with Filing 1 to pass any stormwater
that exceeds the storage capacity of the wetland/ pond areas safely to Richards Lake.
5. Any swales that have slopes less than 2.0 percent will have 3' valley pans installed at
the flow line of the swale.
B. Specific Details - Storm Sewer
1. Storm sewer A located at the low point on Pondview Court will consist of the
following;
a. 5' Type R inlet in sump condition
b. 140 LF of 18 " HDPE pipe ( ADS N-12 or approved equal) with FES. .
c. 1 - shallow manhole
d. An 18 "ADS N-12 Drain Basin for Water Quality
e. Overflow Swale
Page 5
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
III DRAINAGE DESIGN CRITERIA
A. Regulations
1. This final report and the Master Grading, Drainage and Erosion Control Plans for
Hearthfire P.U.D., Second Filing were prepared in accordance with the requirements
of the current City of Fort Collins Storm Drainage Design Criteria and Erosion
Control Criteria.
B. Development Criteria Reference and Constraints
1. County Road 13 will be widened with this project and the proposed grading along the
west property line will have to match the proposed design of the road.
2. The existing wetland areas retain much of the stormwater that flows to them.
Emergency overflow structures were necessary to convey the stormwater which
exceeds the capacity of the wetlands out of the wetland areas to Richards Lake. These
were designed with Hearthfire P.U.D., First Filing.
3. The design intent is to divert as much of the runoff as possible to Ponds 1 and 2 for
the purpose of water quality.
C. Hydrologic Criteria
1. Runoff calculations at various design points are based on the 'Rational" method. The
2, 10, and 100-year storms have been analyzed.
2. No detention is proposed with this subdivision because the existing wetland areas will
act as temporary retention ponds.
3. Emergency overflow structures were designed to convey flows that exceed the
capacity of the retention areas with Filing 1.
D. Hydraulic Criteria
1. Storm sewer inlet design is based on the inlet curves provided in the City of Fort
Collins Drainage Criteria Manual. All the storm sewer is designed for at least the 10-
year storm. This exceeds the City Requirement of the 2-year design storm.
2. Storm sewer design is based on Mannings Equation with Mannings coefficients as
suggested in the City of Fort Collins Drainage Criteria Manual.
Page 4
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
II DRAINAGE BASINS AND SUB -BASINS
D. Developed Conditions
1 The developed site increases the contributing area to ponds 1 & 2 for the purpose of
water quality. The table below summarizes the sub -basins within the limits of the
Second Filing, their total area and the immediate destination of the flow from them.
Area
Sub -basin
acres
Flow Destination
Notes
1
0.78
Pond 2
Storm Sewer
2
0.90
Pond 2
Storm Sewer
3
2.00
Pond 2
Storm Sewer
4
8.12
Pond 2 /Richards Lake
Storm Sewer
5
2.71
Richards Lake
Storm Sewer
6
9.02
Richards Lake
7
10.47
Richards Lake
8
5.31
Pond 1
The total area of the sub -basins is 39.31 acres.
2. The table below summarizes the peak flows from the developed sub -basins which
contribute to the storm sewer infrastructure.
Sub -basin
Q2
Q100
Notes
cfs
cfs
1
1.41
4.96
Storm sewer Profile A
2
1.68
5.83
Storm Sewer Profile B
3
3.14
11.10
Storm Sewer Profile C
4
10.10
35.67
Storm Sewer Profile D
5
4.24
15.02
Overland Flow
Page 2
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
II DRAINAGE BASINS AND SUB -BASINS
A. Major Basin Description
1. The site is located in the Dry Creek Basin as delineated on the City of Fort Collins
Stormwater Basin Map.
2. This portion of the Dry Creek Basin is partially developed with large single family
lots and medium sized ranches.
B. Sub -Basin Description
1. The site topography is best described as rolling. There are several ridges on the site
which create several sub -basins. The site generally slopes from the northeast to the
southwest at an average rate of 0.04 ft/ft (4.0%).
2. The basin is defined by Douglas Road to the north, County Road 13 to the west and
Richards Lake to the south. The eastern property line of the entire site is the eastern
boundary of the basin.
3. There are two (2) existing wetlands / ponding areas east of the site which intercept
much of the runoff from the site and retain it. Grading proposed in these areas with
Hearthfire P.U.D., Fast Filing created permanent water features. They are designated
Pond 1 and Pond 2 on the Drainage and Erosion Control Plan.
a. Pond 1 is crossed by the proposed access road (Hearthfire Way) to the First Filing
from Douglas Road which was designed with Hearthfire P.U.D., First Filing.
b. Pond 2 is the wetland area that is within the limits of Hearthfire P.U.D., First
Filing.
The stormwater that is intercepted by the wetlands either percolates into the soil or
evaporates. An exception to this occurs when storm events exceed the storage
capacity of the low areas. The stormwater eventually overflows into Richards Lake
when this occurs.
4. Richards Lake is the ultimate destination of all runoff from the site including any
water that exceeds the storage capacity of the wetland / pond areas.
Page 1
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
I. GENERAL LOCATION AND DESCRIPTION
A. Property Location
1. Hearthfire P.U.D., Second Filing is located in the West one-half (1/2) of Section 30,
Township 8 North, Range 68 West of the 6th P.M., Latimer County, Colorado.
2. More specifically, it is located on the south side of Douglas Road (County Road 54),
approximately 1.5 miles east of the intersection of Douglas Road and State Highway
1.
3. The site is bounded on the west by County Road 13, on the north by Douglas Road
and Cherrywood Acres, on the east by Hearthfire P.U.D., First Filing and on the south
by Richards Lake.
4. Richards Lake is located immediately south of Hearthfire P.U.D., Second Filing.
Storm runoff from the site has historically entered Richards Lake and will continue
with the development of Hearthfire P.U.D., Second Filing.
a. Richard Lake is owned and operated by The Water Supply and Storage
Company.
b. The Water Supply and Storage Company has indicated that they will accept
undetained flows from Hearthfire P.U.D., Second Filing in a manner similar to
historic acceptance.
i. A statement has been provided with the Hearthfire P.U.D, Second Filing
Utility Plans and Final Plat indicating the reservoir company's acceptance of
undetained flows to Richards Lake.
ii. The Water Supply and Storage Company has provided a letter indicating their
intent to accept undetained flows to Richards Lake. A signed copy of this
letter is attached to this report and is located in Appendix IV.
B. Description of the Property
1. Hearthfire P.U.D., Second Filing is a proposed residential subdivision in the City of
Fort Collins, Colorado. The overall subdivision consists of approximately 146 single
family homes. There are a total of 57 lots proposed with this filing.
2. Hearthfire P.U.D., Second Filing has a platted area of approximately 39.31 acres.
3. The site is currently vacant and is covered with native vegetation.
4. There are some existing oil wells on the site.
July 16, 1997
Project No: 1552-02-97
Basil Hamdan
City of Ft. Collins Storm Water Utility
P.O. Box 580
Ft. Collins, Colorado 80524
Re: Hearthfire P.U.D., Second Filing; Ft. Collins, Colorado
Dear Basil,
Enclosed please find the Final Drainage and Erosion Report and Plans for Hearthfire P.U.D.,
Second Filing. The hydrology data and the hydraulic analysis presented in this report complies
with the requirements of the City of Fort Collins Storm Drainage Criteria Manual; dated March,
1984, revised May, 1997 and the Erosion Control Reference Manual.
If you have any questions or comments, please call me at 226-5334.
Sincerely,
Brian W. Shear
Shear Engineering Corporation
BW S / meo
cc: Richards Lake Development Company
a
A
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226.5334 FAX (970) 282-0311
FINAL DRAINAGE AND EROSION CONTROL REPORT
for
HEARTHFIRE P.U.D., SECOND FILING
Ft. Collins, Colorado
Prepared for:
RICHARDS LAKE DEVELOPMENT COMPANY
5319 Paradise Lane
Fort Collins, Colorado 80526
r, e r r" "nn-TAL
dale. `�I'�4Q-------
Prepared By:
SHEAR ENGINEERING CORPORATION
Project No: 1552-02-97
Date: July, 1997
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226.5334 FAX (970) 282-0311
SHEAR ENGINEERING CORPORATION
DEVELOPED
FLOW TO CONCENTRATION POINT A
FROM SUBBASIN 1
PROJECT: HEARTHFIRE PUD SECOND FILING DATE 07/14/97
LOCATION:POND VIEW COURT PROD. NO.1552-02-97
FILE: STORM BY HBO
AREA (A)= 0.78 ACRES
PAGE
i
RUNOFF COBF. (C)
2 YEAR 10
YEAR
100
YEAR
C 0.78
0.78
0.98
REFER TO SUBBASIN BREAKDOWN ON
PAGE
2
TIME OF CONCENTRATION (Tc)
OVERLAND TRAVEL TIME (Ti)
LENGTH = 40 FEET SLOPE
= 1.00
i
2 YEAR 10
YEAR
100
YEAR
C = 0.20
0.20
0.25
Ti (min)= 10.64
10.64
10.05
TRAVEL TIME (It) =L/(60*V)
FLOW TYPE
L (ft) = 480 S (%) =
1.00
GUTTER
V (fps)
= 2.00
Tt(min)=
L (ft) _? S M _?
?
V (fps)
_?
Tt(min)=
L (ft) _? S (6) _?
?
V (fps)
_?
Tt(min)=
L (ft) _? S (e) _?
?
V (fps)
_?
Tt(min)=
L (ft) _? S (6) _?
?
V (fps)
_?
Tt(min)=
L (ft) _? S (t) _?
?
V (fps)
_?
Tt(min)=
L (ft) _? S (6) _?
?
V (fps)
_?
Tt(min)=
NOTE: ALL VELOCITIES TAKEN
FROM
FIGURE 3-2
TOTAL TRAVEL TIME
(min) _
L = 520 L/180+10
12.89
c
14.05
CHOOSE
LESSER
Tc -Ti+TOTAL TRAVEL TIME
2 YEAR 10
YEAR
100
YEAR
Tc (min)= 12.89
12.89
12.89
USE Tc = 13
13
13
INTENSITY (I) (iph)
2 YEAR 10
YEAR
100
YEAR
I = 2.30
4.03
6.49
NOTE: INTENSITIES TAKEN FROM FIGURE
3-1
RUNOFF (Q= CIA) (cfe)
2 YEAR 10 YEAR 100 YEAR
QTOTAL - 1.41 2.46 4.96
QINLBT = 1.41 2.46 4.85
QOVRR = 0.00 0.00 0.12 OVERFLOW SWALE
CONCLUDE:DESIGN FOR 10 YEAR STORM
INSTALL 5 FOOT TYPE R INLET IN SUMP CONDITION
CAPACITY PER FOOT (cfe/ft)= 1.14 BASED ON FLOW DEPTH OF
REDUCTION FACTOR = 85.006ACTUAL CAPACITY = 4.85 CPS
PIPE DIAM. = 1.50 FT. PIPE TYPE = ADS
0.5 FOOT
3
4.00
0.00
0.00
0.00
0.00
0.00
0.00
4.00
SLOPE = 0.0600 FT/FT MANNINGS n = 0.012
CONVEYANCE FACTOR= 113.8 - REFER TO TABLE 4 ADS MANUAL
CAPACITY = 27.88 CPS SEE PAGE 3 A FOR OVERFLOW CHANNEL
Page 8
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
IV DRAINAGE FACILITY DESIGN
B. Specific Details - Storm Sewer
6. Storm sewer E located on Town Center Drive east of Ingle Court will consist of the
following;
a. 2 - 10' Type R inlet in sump condition designed with Filing 1
b. The overflow storm sewer from Pond 2 to Richards Lake designed with Filing 1.
7. The following table summarizes the design of the storm sewers. Flow depth only
applies to inlets in sump condition.
Profile
Design
Design
Inlet
Flow
Inlet
Point
Storm
Q
Size
Depth
Capacity
yr.
cfs
ft.
ft.
cfs
A
A
10
2.46
5
0.57
5.70
B
B
10
2.95
5
0.57
5.70
C
Cl
100
2.27
20
NA
1.83
C
C2
100
8.72
20
NA
4.97
D
D1
100
1.15
20
NA
1.04
D
D2
100
7.15
20
NA
6.45
D
D3
100
38.27
15
NA
31.82
E
E1
100
10.79
10
1.0
22.05
E
E2
100
16.69
10
1.0
22.05
Profile
From
To
Pipe
Pipe
Pipe
Mannings
Pipe
DP
DP
Diameter
Slope
Type
n
Cap.
ft..
ft./ft.
cfs
A
A
Pond
1.5
0.06
ADS N-12
0.012
27.88
B
B
Pond
1.5
0.01
ADS N-12
0.012
11.38
C
C2
Cl
1.5
0.01
RCP
0.013
10.50
C
C1
Pond
1.5
0.01
ADS N-12
0.012
11.38
D
D3
D2
2.5
0.0089
RCP
0.013
38.70
D
D2
D1
2.5
0.0089
RCP
0.013
38.70
D
D1
Pond
2.5
0.0089
ADS N-12
0.010
41.92
E
E2
E1
2.0
0.024
RCP
0.013
34.68
E
E1
Lake
2.0
0.024
ADS
0.012
37.57
Page 3
Final Drainage and Erosion Control Report
Hearthfire P.U.D., Second Filing
II DRAINAGE BASINS AND SUB -BASINS
C. Historic Conditions
The overall site which includes filing 1 and 2 can be divided into 6 historic sub -basins
designated A-F. These basins are undeveloped with a few active oil wells located on
them as well as some wetland areas. We are utilizing the "C" factor for sandy soils
with an average slope because of the wetlands present for most of the basin. We have
assumed a "C" factor of 0.45 for Sub -basin F which consists of large estate lots in
Cherrywood Acres. The table below summarizes the sub -basins, their total area and
the immediate destination of the flow from them.
Area
Sub -basin acres Flow Destination
A
50.53
Pond 1
B
57.59
Pond 2 a:
C
40.50
Richards Lake
D
10.64
Richards Lake via Richards Lake PUD
E
13.75
Serramonte Highlands
F
12.16
Douglas Road and east
The total area of the sub -basins is 185.17 acres. Sub -basins A-E contribute
stormwater to Richards Lake. There is also an additional 91.8 acres on the north side
of Douglas Road which contributes runoff to pond 1.
2. The table below summarizes the peak flows from the historic sub -basins.
Q2 Q100
Sub -basin cfs cfs Notes
A
30.5
59.8
Retained in Pond 1
B
9.5
35.1
Retained in Pond 2
C
7.7
28.6
Richards Lake
D
1.9
7.4
Richards Lake
E
3.4
12.4
Serramonte Highlands
F
8.3
30.5
Douglas Road
a
APPENDIX V
Grading and Drainage and Erosion Control Plan (3 Sheets)
THE WATER SUPPLY AND STORAGE COMPANY
231-9 EAST MULBERRY PHONE (303) 482-3433
P.O. BOX 1584
FORT COLLINS, COLORADO 80522
July 8, 1997
To whom it may concern
Re: Hearthfire P.U.D., Second Filing; Ft. Collins, Colorado
This note Is provided in order to indicate the intent of The Water Supply and Storage Company to agree to
accept developed undetained stormwater runoff from the Hearthfire P.U.D. project to Richards Lake in a
pattern similar to historic flows which entered Richards Lake.
Our ur.derstanding is that water quality will be addressed. We also understand that an approval block will
be provided on the final utility plans for Hearthfire P.U.D., Second Filing Ndnich will be as follows:
Water Supply and Storage
UTILITY PLAN APPROVAL
The undersigned on behalf of THE WATER SUPPLY AND
STORAGE COMPANY, the owner of Richards Lake, does
hereby agree to accept all runoff from Hearthfire P.U.D. in a
pattern similar to historic flows which entered this irrigation
reservoir.
President Date
We also understand that the final plat •will be provided with the folio%vino:
IRRIGATION COMPANY APPROVAL
The undersigned on behalf of THE WATER SUPPLY AND
STORAGE COMPANY, the owner of Richards Lake, does
hereby agree to accept all runoff from Hearthfire P.U.D, in a
pattern similar to historic flows which entered this irrigation
reservoir.
President
Date
ifyoe hate any question or comments, please call us at (970) 482-3433.
Sincerely,
Torn 1 ogre, esrdent
The Water Supply and Storage Company
cc: Richards Lake Development Company
APPENDIX IV
Water Supply and Storage Letter accepting stormwater from
Hearthfire Second Filing
TABLE 5
CIRCULAR PIPE FLAW CAPACITY
Full Flow (cubic feet per second)
Mannings "n"= 0.013
Dia. *Cony. % Slope (feet per 100 feet)
(in.) Factor 0.02 0.05 0.10 0.20 0.35 0.50 0.75 1.00 1.25 1.50 1.75 2.0 2.5 5.0 10.0 20.(
(c.f.s.)
3 0.884 0.012 0.020 0.028 0.040 0.052 0.062 0.077 0.088 0.099 0.11 0.12 0.12 0.14 0.20 0.28 0.4(
4 1.903 0.027 0.043 0.060 0.085 0.113 0.135 0.165 0.190 0.213 0.23 0.25 0.27 0.30 0.43 0.60 0.8E
5 3.451 0.049 0.077 0.109 0.154 0.204 0.244 0.299 0.345 0.386 0.42 0.46 0.49 0.55 0.77 1.09 1.54
6 5.611 0.079 0.125 0.177 0.251 0.332 0.397 0.486 0.561 0.627 0.69 0.74 0.79 0.89 1.25 1.77 2.51
8 12.084 0.171 0.270 0.382 0.540 0.715 0.854 1.047 1.208 1.351 1.48 1.60 1.71 1.91 2.70 3.82 5.4(
10 21.91 0.31 0.49 0.69 0.98 1.30 1.55 1.90 2.19 2.45 2.68 2.90 3.10 3.46 4.90 6.93 9.8(
12 35.63 0.50 0.80 1.13 1.59 2.11 2.52 3.09 3.56 3.98 4.36 4.71 5.04 5.63 7.97 11.27 15.9;
15 64.60 0.91 1.44 2.04 2.89 3.82 4.57 5.59 6.46 7.22 7.91 8.55 9.14 10.21 14.44 20.43 28.8E
18 105.04 1.49 2.35 3.32 4.70 6.21 7.43 9.10 10.50 11.74 12.87 13.90 14.86 16.61 23.49 33.22 46.9E
21 158.45 2.24 3.54 5.01 •7.09 9.37 11.20 13.72 15.85 17.72 19.41 20.96 22.41 25.05 35.43 50.11 70.8E
24 226.22 3.20 5.06 7.15 10.12 13.38 16.00 19.59 22.62 25.29 27.71 29.93 31.99 35.77 50.59 71.54 101.17
27 309.70 4.38 6.93 9.79 13.85 18.32 21.90 26.82 30.97 34.63 37.93 40.97 43.80 48.97 69.3 97.9 138.5
30 410.17 5.80 9.17 12.97 18.34 24.27 29.00 35.52 41.02 45.86 50.24 54.26 58.01 64.85 91.7 129.7 183.4
36 666.98 9.43 14.91 21.09 29.83 39.46 47.16 57.76 66.70 74.57 81.69 88.23 94.33 105.46 149.1 210.9 298.3
42 1006.1 14.23 22.50 31.82 44.99 59.5 71.1 87.1 100.6 112.5 123.2 133.1 142.3 159.1 225.0 318.2 449.E
48 1436.4 20.31 32.12 45.42 64.24 85.0 101.6 124.4 143.6 160.6 175.9 190.0 203.1 227.1 321.2 454.2 642.4
* Conveyance Factor = (1.486 x R2/3 x A) / n
TABLE 4
CIRCULAR PIPE FLOW CAPACITY
Full Flow (cubic feet per second)
Mannings "n"= 0.012
Dia. *Conv. % Slope (feet per 100 feet)
(in.) Factor 0.02 0.05 0.10 0.20 0.35 0.50 0.75 1.00 1.25 1.50 1.75 2.0 2.5 5.0 10.0 21
(c.f.s.)
3 0.957 0.014 0.021 0.030 0.043 0.057 0.068 0.083 0.096 0.107 0.12 0.13 0.14 0.15 0.21 0.30 0
4 2.062 0.029 0.046 0.065 0.092 0.122 0.146 0.179 0.206 0.231 0.25 0.27 0.29 0.33 0.46 0.65 0
5 3.738 0.053 0.084 0.118 0.167 0.221 0.264 0.324 0.374 0.418 0.46 0.49 0.53 0.59 0.84 1.18 1
6 6.079 0.086 0.136 0.192 0.272 0.360 0.430 0.526 0.608 0.680 0.74 0.80 0.86 0.96 1.36 1.92 2
8 13.091 0.185 0.293 0.414 0.585 0.774 0.926 1.134 1.309 1.464 1.60 1.73 1.85 2.07 2.93 4.14 5
10 23.74 0.34 0.53 0.75 1.06 1.40 1.68 2.06 2.37 2.65 2.91 3.14 3.36 3.75 5.31 7.51 10
12 38.60 0.55 0.86 1.22 1.73 2.28 2.73 3.34 3.86 4.32 4.73 5.11 5.46 6.10 8.63 12.21 17
15 69.98 0.99 1.56 2.21 3.13 4.14 4.95 6.06 7.00 7.82 8.57 9.26 9.90 11.06 15.65 22.13 31
18 113.80 1.61 2.54 3.60 5.09 6.73 8.05 9.86 11.38 12.72 13.94 15.05 16.09 17.99 25.45 35.99 50
21 171.65 2.43 3.84 5.43 7.68 10.16 12.14 14.87 17.17 19.19 21.02 22.71 24.28 27.14 38.38 54.28 76
24 245.08 3.47 5.48 7.75 10.96 14.50 17.33 21.22 24.51 27.40 30.02 32.42 34.66 38.75 54.80 77.50 109
27 335.51 4.74 7.50 10.61 15.00 19.85 23.72 29.06 33.55 37.51 41.09 44.38 47.45 53.05 75.0 106.1 15'
30 4440
35 6.28 9.94 14.05 19.87 26.29 31.42 38.48 44.44 49.68 54.42 58.78 62.84 70.26 99.4 140.5 19
.57 10.22 16.16 22.35 32.31 42.75 51.09 62.58 72.26 80.79 88.50 95.59 102.19 114.25 161.6 228.5 32
36 722
42 1089.9 15.41 24.37 34.47 48.74 64.5 77.1 94.4 109.0 121.9 133.5 144.2 154.1 172.3 243.7 344.7 48
48 1556.1 22.01 34.80 49.21 69.59 92.1 110.0 134.8 155.6 174.0 190.6 205.9 220.1 246.0 348.0 492.1 69
* Conveyance Factor = (1.486 x R2/3 x A) / n
a
A
0.7
U- 0.6
F-
IAJ
Z 0.5
w
> 0.4
0
2
F
CL 0.3
w
o.
z 0.2
0
z
0
m
EXAMPLE
•
FLOW INTO INLET PER SO. FT. OF OPEN AREA (CFS/FT
Figure 5-3
CAPACITY OF GRATED INLET IN SUMP
(From: Wright -McLaughlin Engineers, 1969)
Z.
MAY 1984
5-11
DESIGN CRITERIA
No Text
1.0
.9
.8
7
RM
».1
f-
w
w
0 .25
F-
c�
w
.2
15
12
10
II
8
10
6
9
0
0 4
�U-
i
'
8
x 3
w
z
-
a
of
7 ,
��2'
v
P°t1�
Ex°mp`e�'
i
z
m
6 _ . Exaple, Part a_
J I'8-
z
z
w
5.5
a
a_
0
U
w
.6
1L
0
5
z
Z
z .4
w
=
-
4.5 z
0o .3
c�
w
U.
=
4 =
_ .2
z
co
z
0
�^
3.5 w
w
Q.
w
I
0
w
wo .08
w
3 0E-
o .06
=
c�
0
w
z
-
w
=
ac .04
or
2.5
w
°
w
~
.03
r
a
3
F,
a .02
p
2
a
F-
U
a..
w
.01
L
w
0
0
_
yo a
-
1.5
5
4
3
2
1.5
1.0
8
.7
.6
119
1.1
.3
.25
2
15
IN
Figure 5-2
NOMOGRPAH FOR CAPACITY OF CURB OPENING INLETS IN SUMPS, DEPRESSION DEPTH 2"
Adapted from Bureau of Public Roads Nomograph
MAY 1984 5-10 DESIGN CRITERIA
'S.4
'S.3.5 Grates for Pipes
Where a clear and present danger exists such as a siphon, a drop in elevation adjacent to a
sidewalk or road, a long pipe with one or more manholes, or at pipes which are near play-
grounds, parks; and residential areas, a grate may be required. For most culverts through
embankments and crossing streets, grates will not be required.
When called for on the plans, grates shall meet the following requirements:
a. Grating shall be constructed of steel bars with a minimum diameter of 5/8". Reinforcing
bars shall not be used.
b. Welded connections shall be 1/4" minimum.
c. Spacing between bars shall normally be 6" unless site conditions are prohibitive.
d. All exposed steel shall be galvanized in accordance with AASHTO M 111.
e. Welded joints shall be galvanized with a rust preventive paint.
I. Grates shall be secured to the headwall or end section by removable devices such as
bolts or hinges to allow maintenance access, prevent vandalism, and prohibit entrance by
children.
Inlets
Storm inlets shall be installed where sump (low -spot) conditions exist or street runoff -carrying
capacities are exceeded.
The curb inlets shown in the Standard Details, pages D-7, 8, 12 & 13, shall be used in all City Streets.
If larger inlets are required, the Colorado Department of Highways Type R Curb Inlet, Standard M-604-
12, shall be used. For drainageways other than streets (for example, parking lots, medians, sump
basins) an Area Inlet similar to the detail on page D-9 shall be used.
The outlet pipe of the storm inlet shall be sized on the basis of the theoretical capacity of the inlet, with
a minimum diameter of 15 inches, or 12 inches if elliptical or arch pipe is used.
All curb openings shall be installed with the opening at least 2 inches below the flow line elevation. The
minimum transition length shall be 3'6" as shown on the standard details previously listed.
Because of debris plugging, pavement overlaying, parked vehicles, and other factors which decrease
inlet capacity, the reduction factors listed in Table 5-4 shall be utilized.
Table 5-4
INLET CAPACITY REDUCTION FACTORS
Percentage of
Drainage Condition Inlet Type Theoretical Capacity
Sump or Continuous Grade ........................................... CDOH Type R-Curb
Opening
5' 80%
10, 85%
15' 90%
Street— Sump.............................................................. 4' Curb Opening 80%
Street — Continuous Grade .......................................... 4' Curb Opening 80%
Parking Lots, Medians ................................................... Area Inlet 80%
The theoretical capacity of inlets in a low point or sump shall be determined from Figures 5-2 and 5-3.
The theoretical capacity of curb openings on a continuous grade shall be determined from Figures 5-4,
5-5 and 5-6.
The standard curb -opening is illustrated by Figure 5-4 and is defined as having a gutter depression
apron W feet wide at the inlet opening which extends W feet upstream and downstream from the open-
ing, has a depression depth (a) equal to W/12 feet at the curb face, and a curb opening height (h) of at
least 0.5 feet. The graph as presented by Figure 5.5 is based on a depression apron width (W) equal to
2 feet and depression width (a) equal to 2 inches. The pavement cross-section is straight to the curb
MAY 1984 5-8 DESIGN CRITERIA