HomeMy WebLinkAboutFile Documents.743 Cemetery Ln.0011.2018 (16).ARBK MOUNTAIN CROSS
�".1 ENGINEERING, INC.
Civil and Environmental Consulting and Design
May 02, 2018
Ms. Gretchen Greenwood
Gretchen Greenwood&Associates, Inc.
210 South Galena Street, Suite 30
Aspen, CO 81611
RE: Urban Runoff Management Plan—743 & 745 Cemetery Lane - Revised
Dear Ms. Greenwood:
The purpose of this correspondence is to evaluate the construction of a new duplex residence at
743 and 745 Cemetery Lane, from a storm water perspective and provide design recommendations
pertaining to urban runoff management for incorporation into the site design. This letter
incorporates review comments from the City of Aspen and replaces the previous letter dated
December 20, 2017. These recommendations were generated from the site plans that were
submitted to our office and a site visit performed on November 29 and December 13, 2017.
Attached are plan sheets that show the design recommendations and details. Also attached are the
drainage calculations that were generated.
The project is at elevation of approximately 7880 feet above sea level and is adjacent to the golf
course on Cemetery Lane. The project site currently contains an existing duplex building that will
be razed prior to construction of the proposed new duplex. Ultimately runoff from the site will
travel to Castle Creek and then to the Roaring Fork River after it travels through a series of roadside
conveyances and storm drain appurtenances.
Runoff from snowmelt is typically very large in volume but because it happens over a much longer
time period, the peak flows are usually less than a rainfall event. Also, the Urban Runoff
Management Plan states that they are not necessary at this time. Therefore storm water is defined
in this study to be surface water that is a direct result from a rainfall event.
No major irrigation structures cross the site. No other drainage studies specific to this site are
known to exist. The project is located greater than 100' from any mapped floodplain or mud flow
boundaries.
Storm water from the site is evaluated in accordance with the standards of applicable sections of
the City of Aspen, Urban Runoff Management Plan (Code). All flows are listed in units of cubic
feet per second(cfs)unless otherwise noted.
Methodology
The design of a drainage plan begins with a calculation of the flowrate of water that wi ���
produced from a rainfall event. Since the watershed basins are small (less than 90 acres), pe ,�
11/14/201E
8261/2 Grand Avenue, Glenwood Springs,CO 81601 ASPEN
P:970.945.5544 F: 970.945.5558 www.mountaincross-eng.com
BUILDING DEPARTME'
Cemetery Lane
May,2018
Page 2 of 6
Code, the Rational method was used for estimating the amount of runoff that will occur. This
method calculates runoff(Q) in cubic feet per second (cfs) from basin area (A) in acres, runoff
coefficient(C), and rainfall intensity (I) in inches per hour:
Q =C * I * A
When acres and inches per hour are used as the units, the conversion into cubic feet per second is
1.008 but is usually ignored and it has been here. The runoff coefficient is a dimensionless
coefficient.
Basin Area
Drainage basins have the characteristic that any precipitation falling within that area will
drain to the same point of discharge. The project basins were delineated from project
topography,project site plan, and building architecture.
Runoff Coefficient
A runoff coefficient is assigned to each basin that gives a relationship between the amount
of precipitation that becomes surface water and the amount of water that is lost to
infiltration, evaporation, or transpiration. The runoff coefficient is a function of drainage
basin soil types, surface area, and/or land-use. Because the land-use and the surface cover
often vary through the project, a composite coefficient is often assigned to each drainage
basin, based on the weight of the areas and their respective coefficients.
Rainfall Intensity
Rainfall intensity is determined from intensity duration frequency curves, or IDF curves.
IDF curves are graphs of, more or less parallel, frequency curves that yield rainfall
intensities based on storm durations.
Frequency: The return frequency of a rainfall storm is the statistical probability
that a given storm event will occur on average in a given period.For instance a 100-
year storm has the statistical probability of occurring once in a 100 year span or it
has a 1% chance of occurring in any given year. It is important to emphasize that
it is based on probability statistics and therefore does not reflect actual storm
frequency. Storms of a 100-year magnitude can occur in sequential years, even in
the same year. The return frequency of design is chosen and then referred to as the
design storm.
Duration: The duration of a storm is chosen to coincide with the time of
concentration. Per the Code,the FAA Overland flow equation was used to estimate
the time of concentration. The parameters needed to determine the flow elements
include length, slope, and the Rational runoff coefficient. The theory states that if
the duration is equal to the time of concentration,the length of time will be adequate
for the entire basin to contribute flow.
RECEIVEI
Mountain Cross Engineering, Inc. 11/14/2 01 E
Civil and Environmental Consulting and Design
8261/2 Grand Avenue, Glenwood Springs,CO 81601 ASPEN
P:970.945.5544 F:970.945.5558 www.mountaincross-eng.com
BUILDING DEPARTMEI
Cemetery Lane
May,2018
Page 3 of 6
Analysis
Project basins were delineated based on a site visit to review existing conditions, aerial
photography, roof lines, site grading, roads, project topography, and proposed and existing
buildings. The site slopes from west to east with drainage trending towards Cemetery Lane.
Cemetery Lane has a vegetated swale that separates the pedestrian path from the roadway that
prevents run-on from the east. The neighboring property to the west is the golf course that contains
a pond and ditch; additionally topographic survey shows a small berm along the west property line
to prevent run-on trespass from the western property line. The southern property is an existing
residence that has berming along the southern property line for the western portion and then is
lower in elevation for the eastern portion. The northern property is another existing residence that
is lower in elevation with a swale along the northern property line that drains toward Cemetery
Lane. Presently, there is some runoff trespass onto the southern property and onto the northern
property. The contributory areas are small but the proposed design will correct this. Other than
the vegetated swale mentioned above, no adjacent storm conveyances exist.
The historic and existing drainage basins were assumed to be the same. The proposed basin is
slightly larger to capture the small areas that were trespassing to the north and south. Essentially,
one drainage basin was delineated; everything in this basin drains to the bio-retention pond on the
eastern property boundary. The proposed building will have hardscape and roof areas that will
drain to turf areas before being conveyed by grass swales to the proposed bio-retention structure.
Runoff coefficients were determined based on site soils and percentage imperviousness, per the
appropriate figures in the Code. The hydrologic soil group was determined from Figure 3.1 and
based on the project location is, "C". Based on the corresponding Figure 3.3 the applicable
coefficients were determined and are shown in the attached calculations. The parameters for
calculating the time of concentration were determined from the site, slope, length, and land uses.
The time of concentrations for the site basins that were used are between 9.1 and 14.1 minutes.
The calculations are attached. The rainfall intensities were determined by using the appropriate
storm curve, duration to match the time of concentration, and the IDF curve provided in the Code
for the City of Aspen.
The basin flow rates were calculated for the 5-year and 100-year storms based on the Rational
Method described in the Code for the historic (pre-project flows), existing, and the proposed
conditions. The calculations are attached.
Basin Area Coefficient Flow
Description (acres) (cfs)
Historic—5 yr 0.322 0.15 0.09
Existing - 5 yr 0.322 0.32 0.21
Proposed- 5 yr 0.326 0.40 0.29
RECEIVEI
Mountain Cross Engineering, Inc. 11/14/2 01 E
Civil and Environmental Consulting and Design
8261/2 Grand Avenue, Glenwood Springs,CO 81601 ASPEN
P:970.945.5544 F:970.945.5558 www.mountaincross-eng.com
BUILDING DEPARTMEI
Cemetery Lane
May,2018
Page 4 of 6
Basin Area Coefficient Flow
Description (acres) (cfs)
Historic - 100 yr 0.322 0.50 0.63
Existing - 100 yr 0.322 0.58 0.80
Proposed- 100 yr 0.326 0.60 0.92
Flows will be overland into swales. The swale sizes were determined using the Manning's
equation for open channel flow. Minimum slopes of 1.5%,project flows,and vegetated lining was
used for swale calculations. Minimum slopes of 1%,project flows, and corrugated metal was used
for pipe calculations. Calculations are attached.
The project is within the Castle Creek drainage basin and the proposed flows are increased from
the historic condition so detention is required and proposed. Detention is provided by means of a
bio-retention pond to mitigate increased flows from the project area. Swales convey flows into
the bio-retention pond. Detention volumes were calculated using the modified FAA Procedure
described in the Code. The required depth is 15.6"with 3:1 minimum side slopes. The pond has
a north and south portion that is joined with a 12"pipe. Detention storage volumes for the 5-year
and 100-year storms begin at an elevation of 7879.80, above the water quality capture volume that
is discussed below. The 5-year volume calculated is 167 cubic feet and this is achieved at an
elevation of 7880.25. The 100-year volume calculated is 275 cubic feet and this is achieved at an
elevation of 7880.50. There is a slotted drain across the driveway at an elevation of 7880.67 that
would serve as an emergency overflow in case of storms larger than the 100-year storm. Total
pond volume is 436 cubic feet. The calculations are attached.
Release rates from the detention pond match the historic flow rates for the 5-year and 100-year
storms by means of orifices. The release for the 5-year storm is at elevation 7879.80 with an orifice
of a diameter of 2.25 inches. The release for the 100-year storm is at elevation 7880.25 with an
orifice of a diameter of 6.25 inches. The calculations are attached.
Water Quality
Temporary structures are intended to be used during construction activities. Permanent structures
are intended to be used continually after the construction activities have been completed.
Temporary erosion control measures that are to be employed during construction have been
designed to contain sediment on the site and to mitigate erosion from construction activities. Silt
fencing is placed around the downhill limits of disturbance. Rock socks are placed in the thalweg
of swales and at inlets.
Permanent erosion control measures are revegetation of disturbed areas, design of conveyances to
prevent erosion, and the bio-retention pond. Additionally, the Code requires a Water Quality
Capture Volume (WQCV)per the Figures 8.13 and 8.14. RECEIVE
Mountain Cross Engineering, Inc. 11/14/2 01 E
Civil and Environmental Consulting and Design
8261/2 Grand Avenue, Glenwood Springs,CO 81601 ASPEN
970.945.5544 F: 970.945.5558 www.mountaincross-eng.com
BUILDING DEPARTME'
Cemetery Lane
May,2018
Page 5 of 6
The WQCV was calculated based on the site acreage and percent impervious area. Based on Fig
8.13 in the Urban Runoff Management Plan the watershed inches is determined based on the
percentage of effective impervious area determined from the type of drainage system that is
tributary to the impervious areas. Level 1 adjustment was used to determine the "Effective
Impervious Area" from Fig 8.14. Based on the Effective Imperviousness of 48%,this yields 0.09
watershed-inches. Using the area 0.326 acres this yields 106.6 cubic feet of WQCV. The WQCV
Structure is provided in the bottom of the bio-retention pond. The flat surface area of the bottom
of the pond is 187 sq. ft. at an elevation of 7879.2. A depth of 0.6 feet is required to achieve the
volume to an elevation of 7879.80. Type C soils require an underdrain rather than allowing
infiltration. A 4" perforated PVC is proposed to drain through back to back reducers that would
restrict flows prior to discharging to daylight. Drain time is estimated to be 1.5 hours. Calculations
are attached.
The site will disturb less than one acre and therefore will not require a permit from CDPHE.
Maintenance
Maintenance will be required periodically for the drainage system. At a minimum the following
should be done bi-annually in the spring and fall: pipes, inlets, roof drains, downspouts, gutters,
and swales should be cleaned and cleared of mud and debris. The bio-retention pond should also
be cleared of mud and debris and also maintained with clean, straight grades. All heat tape should
be checked. Heat tape should be turned off in the spring and turned on in the fall. Temporarily,
the general notes require the maintenance and frequent inspection of the silt fence and the rock
socks for proper operation. A management plan is included in the Appendix.
Low Impact Development
Principle 1: At the outset of the drainage design, WQCV was anticipated. The site grading was
designed to convey runoff to the WQCV in the bio-retention pond.
Principle 2: The design used the entire site attempting to minimize impervious areas. All flows
are in permeable conveyances and discharge to landscaping.
Principle 3: The impervious areas have been minimized as much as practical and still meet the
requirements of the Owner.
Principle 4: Similar to Principal 2, the impervious areas are minimized and flows are in natural
conveyances.
Principle 5: Detention is provided to mitigate peak flows.
Principle 6: The WQCV facility is paired with the detention creating a dual purpose of peak
mitigation and treating water to enhance the community in the bio-retention pond.
Principle 7: The site has a treatment train approach in that drainage is conveyed in natural swales
to the WQCV structure.
Principle 8: All features are at grade and easily maintained.
Principle 9: N/A. None of the facilities are located in areas accessible to the general public. RECEIVEI
Mountain Cross Engineering, Inc. 11/14/2 01 E
Civil and Environmental Consulting and Design
8261/2 Grand Avenue, Glenwood Springs,CO 81601 ASPEN
P:970.945.5544 F:970.945.5558 www.mountaincross-eng.com
BUILDING DEPARTMEI
Cemetery Lane
May,2018
Page 6 of 6
Results
The magnitude of the peak runoff flows from the proposed condition is increased for the 100-year
runoff when compared to the historic site. Bio-retention is provided that contains 436 cubic feet
of detention and 106.6 cubic feet of WQCV. Natural swales convey flows to the bio-retention
pond.
There is a certain amount of uncertainty in hydrologic calculations. However, when constructed
in accordance with this report and the drainage plan, it is our opinion that the design will safely
convey the runoff flows and volume of the 5-year design storm event and the bio-retention required
for this site and will not cause flooding damage to this or adjacent sites per the requirements of the
City of Aspen.
Thank you for the opportunity to provide this report. Feel free to call if you have any questions,
concerns, or comments.
Sincerel ,
Mount• n Cross E gin ring, Inc. •
r,
/LMi, r.
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"1 is Hale, PE `4 `//°
RECEI VEI
Mountain Cross Engineering, Inc. 11/14/201E
Civil and Environmental Consulting and Design
826 1/2 Grand Avenue,Glenwood Springs, CO 81601
P:970.945.5544 F:970.945.5558 www.mountaincross-eng.com ASPEN
BUILDING DEPARTME'
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JOB Gretchen Greenwood & Assc.'I ph 970.945.5544 fx 970.945.5558 www.mountaincross-eng.com
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ASPEN
BUILDING DEPARTME'
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RECEIVEI
11/14/201E
ASPEN
BUILDING DEPARTMEI
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RECEIVEI
11/14/201E
ASPEN
BUILDING DEPARTMEE
DRAINAGE CALCULATIONS for
M®uNT/IIN CROSS
743 8�745 cemetery Lane
r r
ENGINEERING, INS 12120/2017
� } Civil and Environmental consulting and oe g
626 1f2 Grand Avenue Glenwood Springs.CO 61691
yh61a,9453544txa7a.645,555aww.umountnfncrosscng - \ -
Drainage Area : Historic
PROPERTY GENERAL SURFACE DATA
Total Drainage Area: 14,026 sq. ft. 0.322 ac.
RUNOFF COEFFICIENT
imperviousness= 0%
HSG = C from Fig 3.3
C100 = 0.50
C10 = 0.25
C5 = 0.15
C2 = 0.04
100% 0.322
TOTAL BASIN ACERAGE 0.322
TIME OF CONCENTRATION
Overland Flow Time Length Slope C5 Tc
Upstream Elevation 7885.00 150 0.033 0.15 14.12
Dnstream Elevation 7880.00
Channel Flow Time none Length Slope K Tt
Upstream Elevation 7880.00 0.0 10.000 20.000 0.00
Dnstream Elevation 7880.00
Total 14.12 min
RUNOFF
Historic
Intensity Flowrate
(in/hr) (cfs)
2-yr Storm 1.3 0.02
5-yr Storm 1.8 0.09
10-yr Storm 2.4 0.19
100-yr Storm 3.9 0.63
NOTES:
- Soils are hydrologic soil group C from Figure 3.1
REV EIVEI
11/:4/201E
ASPEN
BUILDING DEPARTMEC
DRAINAGE CALCLlLATIOrJS for
I'A MO€1N'I'AIr9 CROSS ,
743&745 Cemetery Lane
ENGINEER NG, INC 12I2012017
Civil and Environmental Consulting end Dc Ig
826 1)2 Grand Avenue Glenwood Springs,CO 81681 *
--- Ph BrB.Bt5.6144I.B14.BC6.4658 wmv.mounlPincrasecng
Drainage Area : Existing
Surface description: Turf, duplex, and gravel driveway on an improved lot
PROPERTY GENERAL SURFACE DATA
Total Drainage Area: 14,026 sq. ft. 0.322 ac.
RUNOFF COEFFICIENT sq.ft.or
Land Use est. % acres imperviousness= 36%
Building Roof 4010 0.092 HSG = C from Fig 3.3
Ponds 0 0.000 C100 = 0.58
Hardscape and Paving 1040 0.024 C10 = 0.4
Landscaped turf and planters 8,976 0.206 C5 = 0.32
Pine and Aspen 0% 0.000 C2 = 0.25
Sage and Grasses 0% 0.000
TOTAL BASIN ACERAGE 0.322
TIME OF CONCENTRATION
Overland Flow Time Length Slope C5 Tc
Upstream Elevation 7885.00 150 0.033 0.32 11.59
Dnstream Elevation 7880.00
Channel Flow Time none Length Slope K Tt
Upstream Elevation 7880.00 0.0 10.000 20.000 0.00
Dnstream Elevation 7880.00
Total 11.59 min
RUNOFF
Proposed
Intensity Flowrate
(in/hr) (cfs)
2-yr Storm 1.4 0.113
5-yr Storm 2.0 0.206
10-yr Storm 2.6 0.335
100-yr Storm 4.3 0.803
NOTES:
- Soils are hydrologic soil group C from Figure 3.1
REi1,7EIVEI
11/24/201E
ASPEN
BUILDING DEPARTMEC
DRAifAGE CALCULATIONS for
MOIINTAI N CROSS 743 745 cemetery Lane
ENGINEERING, INC. t14130�2D18
Civil and Environmental Consulting and Design
• 02612 Grand Avenue clenwPotl Springs.co 81601 .% :: - -::
-----" Ph9TAB15.35M fx 9TO.Bi5.5559 wnv.montafcroazc} " - - -,
Drainage Area : Proposed
Surface description: Duplex, motor court, landscaping, and Improved lot
PROPERTY GENERAL SURFACE DATA
Total Drainage Area: 14,216 sq.ft. 0.326 ac.
RUNOFF COEFFICIENT sq. ft. or
Land Use est. % acres imperviousness= 48%
Building Roof 5040 0.116 HSG= C from Fig 3.3
Permeable pavers 2890 0.066 C100= 0.60
Hardscape 1750 0.040 C10 = 0.46
Landscaped turf and planters 4,536 0.104 C5= 0.40
Pine and Aspen 0% 0.000 C2 = 0.33
Sage and Grasses 0% 0.000
TOTAL BASIN ACERAGE 0.326
TIME OF CONCENTRATION
Overland Flow Time Length Slope C5 Tc
Upstream Elevation 7884.00 37 0.016 0.40 6.55
Dnstream Elevation 7883.40
Channel Flow Time none Length Slope K Tt
Upstream Elevation 7883.40 170.00 0.020 7.000 2.86
Dnstream Elevation 7880.00
Total 9.42 min
RUNOFF
Proposed
Intensity Flowrate
(in/hr) (cfs)
2-yr Storm 1.5 0.162
5-yr Storm 2.2 0.287
10-yr Storm 2.8 0.420
100-yr Storm 4.7 0.920
NOTES:
- Soils are hydrologic soil group C from Figure 3.1
- Conveyance Coeficient for Lawn (7.0) per Table 3.3
RE
11/ L4/201E
ASPEN
BUILDING DEPARTMEI
Rainfall IDF for Aspen, Colorado
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10 15 20 25 30 35 40 45 50 55 60
Duration in Minutes
-- .—2-yr —0—5-yr —4—10-yr i—25-yr —4-•50-yr - --100-yr
RECEIVEI
11/14/201E
ASPEN
BUILDING DEPARTMEI
WQC Volume, Area P
10I 4,' Level 1: Over turf to capture
E ram• ,tr` Tot Imp = 48 %
kF•' t"i.A.
c. from Fig. 8.14 yields
u• r Eff Imp = 45
r v r..ae.>r '�
w
it r�r>t` from Fig. 8.13 yields
s: f.
WQCV= 0.09 watershed-in
f — Area = 0.326 acres
6 Redd Volume = 106.6 cubic feet
'0 %..j
0 ,: :O Rl 4: 00 W .. W Y9 .:
Ini i It gr ere i•nr v wss(p-i Lrn1}
Figure 8.10 Imperviousness Adjustments far Laval/and 2 I.n CIA(UDFC D 1999)
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0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Effective Imperviousness of Tributary Area to BMP(percent)
Figure a.13 Aspen Wa.r Quality Capture Volume
RECEIVE
11/14/201E
ASPEN
BUILDING DEPARTME
- ,, DETENTION CALCULATIONS for
, MOUNTAIN CROSS
t ENGINEERING, INC. 743 & 745 Cemetery Lane
g',1and Environmmlal Consulting and Design
5261/i Gra�sd Avenue GlenwwdSprings.co SiSo1
w,e>ams .a,o�ss''s,.,',,,.'.,,..,,,''''',�' .'un 04/30/2018
Area= 0.326 acres
Tc= 9.42 minutes
Release rate= 0.63 cfs
C100 = 0.60
100-yr Detention
Duration I Release Volume inflow Volume Volume Difference
(min.) (in./hr.) (113) (ft3) (ft3)
5 5.80 272 344 72
10 4.70 366 557 191
15 3.90 460 693 233
20 3.50 554 829 275
25 3.10 648 918 270
30 2.70 742 960 217
35 2.50 837 1037 200
40 2.40 931 1137 206
45 2.20 1025 1173 148
50 2.10 1119 1244 125
55 1.90 1213 1238 25
60 1.70 1308 1208 -99
Maximum Volume Difference= Required Detention = 275 Cubic Feet
Release rate = 0.09 cfs
C5 = 0.400
5-yr Detention
Duration I Release Volume Inflow Volume Volume Difference
(min.) (in./hr.) (ft3) (ft3) (ft3)
5 3.00 38 118 81
10 2.20 51 174 123
15 1.80 64 213 150
20 1.50 77 237 160
25 1.30 90 257 167
30 1.10 103 261 158
35 1.00 116 276 161
__ 40 0.91 129 287 159
45 0.82 142 291 150
50 0.80 155 316 161
55 0.70 I68 304 136
60 0.60 I8I 284 103 REIVEI
Maximum Volume Difference = 167 Cubic Feet
11/14/201E
ASPEN
BUILDING DEPARTMEE
North Portion
Elevation Area Average Ends Depth (diff) Volume
80.50 507
80.25 433 470 0.3 117.5
80.00 368 400.5 0.25 100.1
79.80 314 341 0.20 68.2
79.20 187 250.5 0.60 150.3
436.1 Cubic Feet
WQCV = 106.6 cu.ft. Flat area of 187 sq.ft. at elev. 79.20. Flat area volume is a depth of 0.6'
5-yr detention volume begins at elevation 79.8 = 168.3 Cubic Feet
100-yr detention volume begins at elevation 79.8 = 285.8 Cubic Feet
Total pond volume = 436.13 Cubic Feet
Orifice Calculations = 5
Q = 0.089 cfs < 0.09 cfs
C = 0.600
A = 0.028 sq. ft. 2.25 diameter (in.)
H = 0.450 ft
Orifice Calculations = 100
Q = 0.111 cfs
C = 0.600
A = 0.028 sq. ft.
H = 0.700 ft 2.25 diameter(in.)
Plus
Q = 0.513 cfs
C = 0.600
A= 0.213 sq. ft.
H = 0.250 ft 6.25 diameter (in.)
Total flows = 0.111+.513< .63 cfs
RECEIVEI
11/14/201E
ASPEN
BUILDING DEPARTMEI
Channel Report
Hydraflow Express Extension for Autodesk®AutoCAD®Civil 3D®by Autodesk, Inc. Wednesday,May 2 2018
Swale
Triangular Highlighted
Side Slopes (z:1) = 4.00, 4.00 Depth (ft) = 0.36
Total Depth (ft) = 0.50 Q (cfs) = 0.920
Area (sqft) = 0.52
Invert Elev (ft) = 1.00 Velocity (ft/s) = 1.77
Slope (%) = 1.50 Wetted Perim (ft) = 2.97
N-Value = 0.030 Crit Depth, Yc (ft) = 0.32
Top Width (ft) = 2.88
Calculations EGL (ft) = 0.41
Compute by: Known Q
Known Q (cfs) = 0.92
Elev (ft) Section Depth (ft)
2.00 1.00
1.75 0.75
1.50 - 0.50
1.25 0.25
1.00 0.00
RED EIVEI
0.75 -0.25
0 .5 1 1.5 2 2.5 3 3.5 4 4.5 151/1 4/2 0 1 E
ASPEN
Reach (ft) BUILDING DEPARTMEI
Channel Report
Hydraflow Express Extension for Autodesk®AutoCAD®Civil 3D®by Autodesk, Inc. Wednesday,May 2 2018
12 in. Pipe
Circular Highlighted
Diameter (ft) = 1.00 Depth (ft) = 0.47
Q (cfs) = 0.920
Area (sqft) = 0.36
Invert Elev (ft) = 1.00 Velocity (ft/s) = 2.52
Slope (%) = 1.00 Wetted Perim (ft) = 1.51
N-Value = 0.022 Crit Depth, Yc (ft) = 0.41
Top Width (ft) = 1.00
Calculations EGL (ft) = 0.57
Compute by: Known Q
Known Q (cfs) = 0.92
Elev (ft) Section Depth (ft)
3.00 2.00
2.50 1.50
2.00 1.00
1.50 0 0.50
1.00 0.00
RECEIVEI
0.50 -0.50
0 1 2 3 11/14/201E
ASPEN
Reach (ft) BUILDING DEPARTMEI
Channel Report
Hydraflow Express Extension for Autodesk®AutoCAD®Civil 3D®by Autodesk, Inc. Monday,Apr 30 2018
8 inch PVC Pipe
Circular Highlighted
Diameter (ft) = 0.67 Depth (ft) = 0.44
Q (cfs) = 0.920
Area (sqft) = 0.25
Invert Elev (ft) = 1.00 Velocity (ft/s) = 3.75
Slope (%) = 1.00 Wetted Perim (ft) = 1.27
N-Value = 0.013 Crit Depth, Yc (ft) = 0.46
Top Width (ft) = 0.64
Calculations EGL (ft) = 0.66
Compute by: Known Q
Known Q (cfs) = 0.92
Elev (ft) Section
2.00
1.75
1.50
1.25
1.00
RECEIVEI
0.75
0 1 11/14/201E
ASPEN
Reach (ft)BUILDING DEPARTMEI