HomeMy WebLinkAboutHOMESTEAD AT CLARENDON HILLS - FDP200032 - - DRAINAGE REPORT (3)
February 5, 2021
DRAINAGE LETTER AND LID REPORT
HOMESTEAD AT CLARENDON HILLS
Fort Collins, Colorado
Prepared for:
Kenneth R. Mitchell
Mosaic Real Estate LLC
1021 Nightingale Drive
Fort Collins, Colorado. 80525
Prepared by:
301 North Mason Street, Suite 100
Fort Collins, Colorado 80524
Phone: 970.221.4158
www.northernengineering.com
Project Number: 1013-008
Drainage Letter and LID Report – Homestead at Clarendon Hills
Date: February 5, 2021
Project: Homestead at Clarendon Hills Project No. 1013-008
Preliminary Development Plan (PDP)
Fort Collins, Colorado
Attn: City of Fort Collins Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
To whom it may concern:
This letter serves to address the stormwater impacts of the proposed project known as “Homestead at
Clarendon Hills”. The site is located in southwest Fort Collins bounded to the north by Front Range
Community College, to the east by existing Clarendon Hills Subdivision, to the south by Clarendon
Hills Drive and Langdale Drive, and to the west by South Shields Street. The project is part of the
Drainage Report for Clarendon Hills by Stuart and Associates written in 1986. The proposed
development consists of 8 low-density single-family lots and a detention area. The project site also
contains an existing irrigation ditch along the north property line.
The project was included in the drainage report for Clarendon Hills Subdivision. Therefore, this letter
intends to show conformance with the approved drainage design, including general drainage patterns
and imperviousness. This letter also documents how the project meets new Low Impact Development
requirements implemented City of Fort Collins since the approval of the original project.
Original Drainage Patterns
The original Clarendon Hill drainage design divided the subdivision into 3 basins. The current project
site is split by two of these basins - Drainage Basin A draining to the north, and Drainage Basin B
draining to the south. Drainage Basin B flows into Clarendon Hills Drive and Langdale Drive and
travels via gutter and pan flow south along Clarendon Hills Drive. The flow is then collected by inlets
at Clarendon Hills Drive and Hinsdale Drive and conveyed to a series of existing detention ponds.
Drainage Basin A generally flows to the northeast to an existing irrigation ditch on the property. A
small undisturbed area north of the irrigation ditch will flow into the Front Range Community College
drainage system. From there, it flows through existing drainage ways east to Mail Creek, and
eventually to Fossil Creek. An Existing Drainage Exhibit and excerpts from the original report are
provided in the appendices for reference.
Page | 3
Proposed Drainage Patterns
The Homestead at Clarendon Hills project was divided into seven proposed drainage basins that
essentially follow the established drainage patterns, as well as the drainage patterns approved with
the Drainage Report for Clarendon Hills.
Basin A encompasses the rear of the lots and open space between the rear lot lines and the existing
irrigation ditch. The only proposed improvements with Basin A are landscaping in the rear of the lots.
Flows from the basin will drain north into the irrigation ditch. Basin A is consistent with Basin A from
the Drainage Report for Clarendon Hills.
Basin B will roughly match the existing area draining south to the existing Clarendon Hills ponds.
Proposed improvements will include single-family homes, the front and side of the lots, driveways,
walks, and detention area. Basin B is further subdivided into Basins B1, B2, B3, and B4. Basins B1 and
B3 consists of the open space at the west and east ends that will discharge into the Clarendon Hills and
Langdon Drives curb and gutter. Basins B2 consists of Lots 1 through 8 building envelopes, driveways
and detention pond. The project was graded to allow the building envelopes to drain to south, and
small swales and curb and gutter in the shared driveway will convey drainage towards the detention
pond. Basin B4 consists of the landscaping along the front of the pond that is incapable of draining
into the detention pond. The release rate from the detention pond is reduced to accommodate the
undetained releases from Basins B1, B3, and B4. An exhibit calculating the release rate is included in
the appendices.
The percent impervious for the lots was developed by assuming a typical building footprint of 3,250
square feet. The building footprint was placed along the rear building envelope to maximize the
length of the driveway. This resulted in 49% imperviousness on a 7,982 sq. ft. lot. The area of the
driveway was adjusted on the other lots to maintain a 49% imperviousness on the other lots. Along
with the shared driveway, this resulted in a percent imperviousness of 51% in Basin B3. An exhibit is
included in the appendices.
Additionally, Basin OS1 and OS2 are on the east and the north sides of the site to quantify flows to the
Front Range Community College campus. Basin OS1 consists of the side and rear of Lot 8 and
adjacent open space. Basin OS2 is a small sliver of open space on the north side of the irrigation ditch
that drains directly to the Front Range Community College campus.
Development of Existing Runoff Coefficient
The drainage for Clarendon Hills Subdivision was originally analyzed in the Drainage Report:
Clarendon Hills: Fort Collins, Colorado prepared by Stuart and Associates in 1986 as part of the approval
process for Clarendon Hills 1st Filing. Homestead for Clarendon Hills is in the northwest corner of the
original drainage master plan for Clarendon Hills 1st Filing. In the approved original drainage report
for Clarendon Hills (1st Filing), the project site was planned as office and multi-family with a
developed runoff coefficient of C=0.50.
According to the approved drainage report for Clarendon Hills 4th Filing, prepared by Land
Development Services and dated April 9, 1991, a church site of 8.27 acres in the middle of the
Clarendon Hills 4th Filing was assumed to be an offsite undeveloped drainage basin with a developed
Page | 4
runoff coefficient of C=0.25. According to the approved drainage report for Clarendon Hills 6th Filing,
prepared by Land Development Services and dated January 8, 1992, the original developer of
Clarendon Hills swapped the northwest corner of Clarendon Hills (including Homestead for
Clarendon Hills) for the church site in Clarendon Hills 4th Filing. The old church site was then
developed as Clarendon Hills 6th Filing with runoff coefficients from 0.28 to 0.70.
Because of the subsequent drainage studies and land swaps, we assumed an existing runoff coefficient
of C=0.25 for Homestead at Clarendon Hills. A runoff coefficient of 0.25 is consistent with the
following design considerations:
• The Fort Collins Stormwater Criteria Manual for lawns with clayey soil and an average slope of
2% to 7% requires a runoff coefficient of C = 0.25. The existing slopes throughout the site is
between 2% to 7% with clayey soil.
• The drainage report for Clarendon Hills 4th Filing assumed a runoff coefficient C=0.25 for the
church site, and the church site was subsequently part of a land swap for the northwest corner
of the Clarendon Hills Subdivision.
Detention
Per the Clarendon Hills 1st Filing Drainage Report, “The ponds were designed using a mass diagram
that required 10.46 acre-feet to detain the 100-year developed storm and release at a 2-year historic
rate…”. Assuming a historic runoff coefficient of 0.25, detention from Basin B was provided as long as
the overall flow at Design Point B does not exceed 1.9 cfs. Because of the increased impervious area
within Basin B, detention is required within Basin B2 to reduce the post-developed flow rates at
Design Point B to equal or less than 1.9 cfs. Since Basins B1, B3, and B4 will be released into the
surrounding curb and gutter undetained, the detention pond in Basin B2 is designed to release the
100-year event at 1.5 cfs. A release rate of 1.5 cfs is required to maintain a 100-year flow rate of 1.9 cfs
at Design Point B. (See the included flowrate calculations included in the appendices.)
Detention Spillway
The detention pond is designed to overflow at the west driveway entrance on Clarendon Hills Drive.
In the even the outlet orifice is blocked, stormwater will first overflow through a weir into the west
rain garden. Then, it will overflow through a curb cut at the northwest end of the rain garden.
Finally, stormwater will overflow through the curb and gutter at a high point located at the back of
sidewalk at the west entrance. Hydraulic calculations are included in the appendices.
Inlets
By limiting the 100-year flowrate at Design Point B, the flowrate at the existing inlets will match or
decrease from the projected flowrates in the previously approved Clarendon Hills drainage reports.
This results in matching or decreasing runoff to the existing inlets that were designed and approved
with the earlier project, so no additional inlet calculations have been provided as a part of this report.
Water Quality/LID Conformance
According to Section 6.0 of the City of Fort Collins Stormwater Manual, “50% site treated with ‘standard’
water quality plus 50% site treated with LID (including pavers) equals 100% of site-treated (requirements met),
or 25% site treated with ‘standard’ water quality plus 75% treated with LID equals 100% of site treated
Page | 5
(requirements met)”, (page 14). This project proposes to treat 90.5% of the new impervious areas
through two rain gardens as LID treatment. However, due to grading constraints along the east side
of the project and requirements to provide a maintenance access for the ditch company, a gravel
pedestrian path (9.5% of new impervious area) will not be treated by either the rain gardens or the
detention pond. An exhibit showing the area of LID treatment is included in the appendices.
Although exact impervious area is unavailable at this preliminary stage, the building envelopes will
drain towards the rain gardens and the detention pond. The high point along each lot line is set at the
rear of the building envelopes to maximize as much of the lot draining towards the south. Space
limitations on the detention pond and rain gardens, natural buffer offsets from the ditch, and fire
accessibility requirements restrict the drainage towards the front. Even with the grading restrictions,
the proposed flowrate into the Mail Creek Basin is 2.2 cfs less than the existing flowrate.
Erosion and Sediment Control
During construction, the Contractor will follow the appropriate and applicable City of Fort Collins
standards for erosion and sediment control. Since more than 10,000 sf will be disturbed as a part of
this project, a comprehensive Stormwater Management Plan will be prepared for this project at final
design. Post construction water quality and erosion control will be achieved by a fully established and
stabilized site. All areas disturbed during construction will receive permanent hardscape, landscape,
or building structure.
Floodplains
There are no regulatory floodplains associated with the project.
Conclusions
The proposed grading concept matches the original drainage patterns. The site matches the designed
imperviousness draining to the existing Clarendon Hills curb and gutter. Onsite detention will be
provided for the increased imperviousness of the area draining to towards the existing Clarendon
Hills ponds, and onsite detention will be required to maintain historic flow rates within Clarendon
Hills. Stormwater quality has been provided and meets the city requirements for Low Impact
Development treatment. Therefore, it is my professional opinion that Homestead at Clarendon Hills
satisfies all applicable stormwater criteria and will effectively limit potential damage associated with
its stormwater runoff.
Please do not hesitate to contact me if you have questions or require additional information.
Sincerely,
Frederick S. Wegert, PE
Project Engineer
Page | 6
Compliance Statement
I hereby attest this report for the final drainage design for Homestead at Clarendon Hills was prepared
by me or under my direct supervision, in accordance with the provisions of the Fort Collins
Stormwater Criteria Manual. I understand that the City of Fort Collins does not and ill not assume
liability for drainage facilities designed by others.
2/5/2021
ATTACHMENT 1
HYDROLOGIC CALCULATIONS
TYPICAL LOT IMPERVIOUSNESS EXHIBIT
FEMA Firmette
FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5)
3.0 Rational Method
3.4 Intensity-Duration-Frequency Curves for Rational Method
Page 8
Table 3.4-1. IDF Table for Rational Method
Duration
(min)
Intensity
2-year
(in/hr)
Intensity
10-year
(in/hr)
Intensity
100-year
(in/hr)
Duration
(min)
Intensity
2-year
(in/hr)
Intensity
10-year
(in/hr)
Intensity
100-year
(in/hr)
5 2.85 4.87 9.95
39 1.09 1.86 3.8
6 2.67 4.56 9.31
40 1.07 1.83 3.74
7 2.52 4.31 8.80
41 1.05 1.80 3.68
8 2.40 4.10 8.38
42 1.04 1.77 3.62
9 2.30 3.93 8.03
43 1.02 1.74 3.56
10 2.21 3.78 7.72
44 1.01 1.72 3.51
11 2.13 3.63 7.42
45 0.99 1.69 3.46
12 2.05 3.50 7.16
46 0.98 1.67 3.41
13 1.98 3.39 6.92
47 0.96 1.64 3.36
14 1.92 3.29 6.71
48 0.95 1.62 3.31
15 1.87 3.19 6.52
49 0.94 1.6 3.27
16 1.81 3.08 6.30
50 0.92 1.58 3.23
17 1.75 2.99 6.10
51 0.91 1.56 3.18
18 1.70 2.90 5.92
52 0.9 1.54 3.14
19 1.65 2.82 5.75
53 0.89 1.52 3.10
20 1.61 2.74 5.60
54 0.88 1.50 3.07
21 1.56 2.67 5.46
55 0.87 1.48 3.03
22 1.53 2.61 5.32
56 0.86 1.47 2.99
23 1.49 2.55 5.20
57 0.85 1.45 2.96
24 1.46 2.49 5.09
58 0.84 1.43 2.92
25 1.43 2.44 4.98
59 0.83 1.42 2.89
26 1.4 2.39 4.87
60 0.82 1.4 2.86
27 1.37 2.34 4.78
65 0.78 1.32 2.71
28 1.34 2.29 4.69
70 0.73 1.25 2.59
29 1.32 2.25 4.60
75 0.70 1.19 2.48
30 1.30 2.21 4.52
80 0.66 1.14 2.38
31 1.27 2.16 4.42
85 0.64 1.09 2.29
32 1.24 2.12 4.33
90 0.61 1.05 2.21
33 1.22 2.08 4.24
95 0.58 1.01 2.13
34 1.19 2.04 4.16
100 0.56 0.97 2.06
35 1.17 2.00 4.08
105 0.54 0.94 2.00
36 1.15 1.96 4.01
110 0.52 0.91 1.94
37 1.16 1.93 3.93
115 0.51 0.88 1.88
38 1.11 1.89 3.87
120 0.49 0.86 1.84
FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5)
3.0 Rational Method
3.4 Intensity-Duration-Frequency Curves for Rational Method
Page 9
Figure 3.4-1. Rainfall IDF Curve – Fort Collins
Runoff
Coefficient1
Percent
Impervious1
0.95 100%
0.95 90%
0.50 40%
0.55 50%
0.20 2%
0.20 2%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt,
Concrete (acres)Rooftop (acres)Gravel (acres)Residential: Low
Density (acres)
Undeveloped:
Greenbelts,
Agriculture
(acres)
Lawns, Clayey
Soil, Flat Slope <
2% (acres)
Percent
Impervious
C2*Cf
Cf = 1.00
C5*Cf
Cf = 1.00
C10*Cf
Cf = 1.00
C100*Cf
Cf = 1.25
EX A 103,769 2.382 2%0.25 0.25 0.25 0.31
EX B 29,782 0.684 2%0.25 0.25 0.25 0.31
EX OS1 6,418 0.147 2%0.25 0.25 0.25 0.31
EX OS2 2,806 0.064 2%0.25 0.25 0.25 0.31
North 112,993 2.594 0.000 0.000 0.000 0.000 0.000 0.000 2%0.25 0.25 0.25 0.31
Lawns and Landscaping:
Combined Basins
2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins
Stormwater Manual (FCSM).
Lawns, Clayey Soil, Flat Slope < 2%
USDA SOIL TYPE: C
Undeveloped: Greenbelts, Agriculture Composite Runoff Coefficient2
1) Runoff coefficients per Tables 3.2-1 & 3.2 of the FCSM. Percent impervious per Tables 4.1-2 & 4.1-3 of the FCSM.
Per Clarendon Hills 4th Filing Drainage Report: C = 0.25, Percent Impervious = 2%
Per Clarendon Hills 4th Filing Drainage Report: C = 0.25, Percent Impervious = 2%
Per Clarendon Hills 4th Filing Drainage Report: C = 0.25, Percent Impervious = 2%
Per Clarendon Hills 4th Filing Drainage Report: C = 0.25, Percent Impervious = 2%
EXISTING RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Gravel
Residential: Low Density
Homestead at Clarendon
F. Wegert
December 18, 2020
Project:
Calculations By:
Date:
Character of Surface
Streets, Parking Lots, Roofs, Alleys, and Drives:
Page 1 of 3
Project:
Calculations By:
Date:
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Ti
2-Yr
(min)
Ti
10-Yr
(min)
Ti
100-Yr
(min)
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Comp.
Tc 2-Yr
(min)
Max.
Tc 2-Yr
(min)
Tc
2-Yr
(min)
Comp.
Tc 10-Yr
(min)
Max.
Tc 10-Yr
(min)
Tc
10-Yr
(min)
Comp.
Tc 100-Yr
(min)
Max.
Tc 100-Yr
(min)
Tc
100-Yr
(min)
ex a EX A 60 92.89 89.01 6.47%6.6 6.6 6.1 N/A N/A N/A 705 89.01 85.49 0.50%1.06 11.09 17.69 14.25 14.25 17.69 14.25 14.25 17.21 14.25 17.21
ex b EX B 30 93.00 91.75 4.17%5.4 5.4 5.0 340 91.75 84.93 2.01 2.83 2.00 N/A N/A N/A 7.41 12.06 7.41 7.41 12.06 7.41 7.01 12.06 7.01
ex os1 EX OS1 96 93.00 89.90 3.23%10.5 10.5 9.8 N/A N/A N/A 98 89.90 86.13 3.85%2.94 0.56 11.09 11.08 11.08 11.09 11.08 11.08 10.32 11.08 10.32
ex os2 EX OS2 45 92.23 88.81 7.60%5.4 5.4 5.0 N/A N/A N/A N/A N/A N/A 5.42 10.25 5.42 5.42 10.25 5.42 5.02 10.25 5.02
ex a North 65 93.83 88.55 8.12%6.4 6.4 5.9 N/A N/A N/A 665 88.55 85.49 0.46%1.02 10.89 17.27 14.06 14.06 17.27 14.06 14.06 16.80 14.06 16.80
Time of Concentration
Combined Basins
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Design
Point Basin
Overland Flow Channelized Flow Swale Flow
Velocity (Swale Flow), V = 15·S ½
EXISTING TIME OF CONCENTRATION COMPUTATIONS (MHFD)
Overland Flow, Time of Concentration:
Homestead at Clarendon
Gutter/Swale Flow, Time of Concentration:F. Wegert
Tt = L / 60V (Equation 6-4 per MHFD)December 18, 2020
Tc = Ti + Tt (Equation 6-2 per MHFD)
Intensity, i (per Table 3.4-1 of the Fort Collins Stormwater Manual)
Velocity (Gutter Flow), V = 20·S ½
(Equation 6-4 per MHFD)
(Equation 3.3-2 per Fort Collins
}
𝑆𝑖=1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑆ൗ13
Notes:
1)Add 4900 to all elevations.
2) Flow path (Tc) for Basin EX A includes the flowline for the Smith Lateral to Design Point ex a. Because the Smith
Lateral has a slope of 0.50% for a length of 705 feet, the computed Tc of 17.21 minutes was used for the Tc.
Page 2 of 3
Tc2 Tc10 Tc100 C2 C10 C100
I2
(in/hr)
I10
(in/hr)
I100
(in/hr)
Q2
(cfs)
Q10
(cfs)
Q100
(cfs)
ex a EX A 2.382 14.25 14.25 17.21 0.25 0.25 0.31 1.92 3.29 6.10 1.1 2.0 4.5
ex b EX B 0.684 7.41 7.41 7.01 0.25 0.25 0.31 2.52 4.31 8.80 0.4 0.7 1.9
ex os1 EX OS1 0.147 11.08 11.08 10.32 0.25 0.25 0.31 2.13 3.63 7.72 0.1 0.1 0.4
ex os2 EX OS2 0.064 5.42 5.42 5.02 0.25 0.25 0.31 2.85 4.87 9.95 0.0 0.1 0.2
ex a North 2.594 14.06 14.06 16.80 0.25 0.25 0.31 1.92 3.29 6.20 1.25 2.13 5.03
Combined Basins
Velocity (Swale Flow), V = 15·S ½
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Design
Point Basin Area
(acres)
Tc (Min)Runoff C Intensity Flow
Velocity (Gutter Flow), V = 20·S ½
EXISTING DIRECT RUNOFF COMPUTATIONS (MHFD)
Overland Flow, Time of Concentration:
Project:Homestead at Clarendon
Gutter/Swale Flow, Time of Concentration:Calculations By:F. Wegert
Tt = L / 60V (Equation 6-4 per MHFD)Date:December 18, 2020
Tc = Ti + Tt (Equation 6-2 per MHFD)
Intensity, I from Fig. 3.4.1 Fort Collins Stormwater Manual
(Equation 6-4 per MHFD)}
𝑆𝑖=1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑆ൗ13
(Equation 3.3-2 per Fort Collins
Stormwater Manual)
Page 3 of 3
Runoff
Coefficient1
Percent
Impervious1
0.95 100%
0.95 90%
0.50 40%
0.55 50%
0.20 2%
0.20 2%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt,
Concrete (acres)Rooftop (acres)Gravel (acres)Residential: Low
Density (acres)
Undeveloped:
Greenbelts,
Agriculture
(acres)
Lawns, Clayey
Soil, Flat Slope <
2% (acres)
Percent
Impervious
C2*Cf
Cf = 1.00
C5*Cf
Cf = 1.00
C10*Cf
Cf = 1.00
C100*Cf
Cf = 1.25
A 59,611 1.368 0.000 0.000 0.176 0.000 1.193 0.000 7%0.24 0.24 0.24 0.30
B1 1,772 0.041 0.000 0.000 0.012 0.000 0.000 0.029 13%0.29 0.29 0.29 0.36
B2 70,997 1.630 0.302 0.574 0.000 0.000 0.000 0.753 51%0.60 0.60 0.60 0.75
B3 552 0.013 0.000 0.000 0.000 0.000 0.000 0.013 2%0.20 0.20 0.20 0.25
B4 3,034 0.070 2%0.25 0.25 0.25 0.31
OS1 4,023 0.092 0.000 0.000 0.028 0.044 0.020 0.000 36%0.46 0.46 0.46 0.57
OS2 2,806 0.064 2%0.25 0.25 0.25 0.31
North 66,440 1.525 0.000 0.000 0.203 0.044 1.277 0.000 8%0.25 0.25 0.25 0.31
South 76,355 1.753 0.302 0.574 0.012 0.000 0.000 0.864 48%0.58 0.58 0.58 0.72
DEVELOPED RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Gravel
Residential: Low Density
Homestead at Clarendon
F. Wegert
December 18, 2020
Project:
Calculations By:
Date:
Character of Surface
Streets, Parking Lots, Roofs, Alleys, and Drives:
Lawns and Landscaping:
Combined Basins
2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins
Stormwater Manual (FCSM).
Lawns, Clayey Soil, Flat Slope < 2%
USDA SOIL TYPE: C
Undeveloped: Greenbelts, Agriculture Composite Runoff Coefficient2
1) Runoff coefficients per Tables 3.2-1 & 3.2 of the FCSM. Percent impervious per Tables 4.1-2 & 4.1-3 of the FCSM.
Lawns, Clayey Soil > 7%: C = 0.35, Percent Impervious = 2%
Lawns, Clayey Soil > 7%: C = 0.35, Percent Impervious = 2%
Page 1 of 3
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Ti
2-Yr
(min)
Ti
10-Yr
(min)
Ti
100-Yr
(min)
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Velocity
(ft/s)
Tt
(min)
Comp.
Tc 2-Yr
(min)
Max.
Tc 2-Yr
(min)
Tc
2-Yr
(min)
Comp.
Tc 10-Yr
(min)
Max.
Tc 10-Yr
(min)
Tc
10-Yr
(min)
Comp.
Tc 100-Yr
(min)
Max.
Tc 100-Yr
(min)
Tc
100-Yr
(min)
a A 60 92.89 89.01 6.47%6.7 6.7 6.2 N/A N/A N/A 705 89.01 85.49 0.50%1.06 11.09 17.78 14.25 14.25 17.78 14.25 14.25 17.32 14.25 17.32
b B1 40 93.97 92.33 4.10%6.0 6.0 5.5 326 92.33 84.93 2.27 3.01 1.80 N/A N/A N/A 7.80 12.03 7.80 7.80 12.03 7.80 7.27 12.03 7.27
b B2 120 94.10 91.77 1.94%8.2 8.2 5.7 375 91.77 84.93 1.82 2.70 2.31 N/A N/A N/A 10.47 12.75 10.47 10.47 12.75 10.47 7.99 12.75 7.99
b B3 40 92.18 91.54 1.60%9.1 9.1 8.6 366 91.54 84.93 1.81 2.69 2.27 N/A N/A N/A 11.37 12.26 11.37 11.37 12.26 11.37 10.86 12.26 10.86
b B4 20 91.89 90.41 7.40%3.6 3.6 3.4 167 90.41 84.93 3.28 3.62 0.77 N/A N/A N/A 4.42 11.04 5.00 4.42 11.04 5.00 4.15 11.04 5.00
os1 OS1 35 92.28 91.47 2.31%5.4 5.4 4.4 N/A N/A N/A 134 91.47 86.13 3.99%2.99 0.75 6.12 10.94 6.12 6.12 10.94 6.12 5.16 10.94 5.16
os2 OS2 25 92.23 90.55 6.72%4.2 4.2 3.9 N/A N/A N/A N/A N/A N/A 4.21 10.14 5.00 4.21 10.14 5.00 3.90 10.14 5.00
a North 60 92.89 89.01 6.47%6.6 6.6 6.1 N/A N/A N/A 705 89.01 85.49 0.50%1.06 11.09 17.69 14.25 14.25 17.69 14.25 14.25 17.21 14.25 17.21
b South 95 94.23 92.41 1.92%7.7 7.7 5.6 350 92.41 84.93 2.14 2.92 2.00 N/A N/A N/A 9.67 12.47 9.67 9.67 12.47 9.67 7.55 12.47 7.55
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Velocity (Swale Flow), V = 15·S ½
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS (MHFD)
Overland Flow, Time of Concentration:
Homestead at Clarendon
Gutter/Swale Flow, Time of Concentration:F. Wegert
Tt = L / 60V (Equation 6-4 per MHFD)December 18, 2020
Tc = Ti + Tt (Equation 6-2 per MHFD)
Velocity (Gutter Flow), V = 20·S ½
Project:
Calculations By:
Date:
Intensity, i (per Table 3.4-1 of the Fort Collins Stormwater Manual)
Time of Concentration
Combined Basins
Design
Point Basin
Overland Flow Channelized Flow Swale Flow
(Equation 6-4 per MHFD)
(Equation 3.3-2 per Fort Collins
}
𝑆𝑖=1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑆ൗ13
Notes:
1)Add 4900 to all elevations.
2) Flow path (Tc) for Basin A includes the flowline for the Smith Lateral to Design Point a. Because the Smith Lateral
has a slope of 0.50% for a length of 705 feet, the computed Tc of 17.32 minutes was used for the Tc.
Page 2 of 3
Tc2 Tc10 Tc100 C2 C10 C100
I2
(in/hr)
I10
(in/hr)
I100
(in/hr)
Q2
(cfs)
Q10
(cfs)
Q100
(cfs)
a A 1.368 14.25 14.25 17.32 0.24 0.24 0.30 1.92 3.29 6.10 0.6 1.1 2.5
b B1 0.041 7.80 7.80 7.27 0.29 0.29 0.36 2.46 4.21 8.80 0.0 0.0 0.1
b B2 1.630 10.47 10.47 7.99 0.60 0.60 0.75 2.21 3.78 8.59 2.2 3.7 10.6
b B3 0.013 11.37 11.37 10.86 0.20 0.20 0.25 2.13 3.63 7.57 0.0 0.0 0.0
b B4 0.070 5.00 5.00 5.00 0.25 0.25 0.31 2.85 4.87 9.95 0.0 0.1 0.2
os1 OS1 0.092 6.12 6.12 5.16 0.46 0.46 0.57 2.67 4.56 9.95 0.1 0.2 0.5
os2 OS2 0.064 5.00 5.00 5.00 0.25 0.25 0.31 2.85 4.87 9.95 0.0 0.1 0.2
a North 1.525 14.25 14.25 17.21 0.25 0.25 0.31 1.92 3.29 6.10 0.7 1.3 2.9
b South 1.753 9.67 9.67 7.55 0.58 0.58 0.72 2.26 3.86 8.59 2.3 3.9 10.9
Velocity (Gutter Flow), V = 20·S ½
DEVELOPED DIRECT RUNOFF COMPUTATIONS (MHFD)
Overland Flow, Time of Concentration:
Project:Homestead at Clarendon
Gutter/Swale Flow, Time of Concentration:Calculations By:F. Wegert
Tt = L / 60V (Equation 6-4 per MHFD)Date:December 18, 2020
Tc = Ti + Tt (Equation 6-2 per MHFD)
Intensity, I from Fig. 3.4.1 Fort Collins Stormwater Manual
Combined Basins
Velocity (Swale Flow), V = 15·S ½
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Design
Point Basin Area
(acres)
Tc (Min)Runoff C Intensity Flow
(Equation 6-4 per MHFD)}
𝑆𝑖=1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑆ൗ13
(Equation 3.3-2 per Fort Collins
Stormwater Manual)
Page 3 of 3
/ / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / /SINGLE - FAMILY RESIDENCE
DRIVEWAY
BUILDING ENVELOPE
LOT LINE
SHARE
D
D
R
I
V
E
W
A
Y
EASEMENT
EASEMENT
EASEMENT
E N G I N E E R N GI
EHTRON R N FIGURE 1
Typical Lot for Impervious Areas
12.18.2020 FORT COLLINS, CO
P:\1013-008\DWG\EXHIBITS\1013-008_DRAINAGE_TYPLOT.DWG
HOMESTEAD AT CLARENDON
LEGEND
ROOF
DRIVEWAY
PERVIOUS
LOT SIZE = 7,982 SQ. FT.
PERCENT IMPERVIOUS = 49%
3,250 SQ. FT.
701 SQ. FT.
4,031 SQ. FT.
USGS The National Map: Orthoimagery. Data refreshed October, 2017.
National Flood Hazard Layer FIRMette
0 500 1,000 1,500 2,000250Feet
Ü105°5'59.00"W 40°31'15.27"N 105°5'21.55"W 40°30'47.92"N
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
SPECIAL FLOODHAZARD AR EAS
Without Base Flood Elevation (BFE)Zone A, V, A99With BFE or Depth Zone AE, AO, AH, VE, AR
Regulator y Floodway
0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mile Zone X
Future Conditions 1% AnnualChance Flood Hazard Zone XArea with Reduced Flood Risk due toLevee. See Notes.Zone X
Area with Flood Risk due to Levee Zone D
NO SCREE N Area of Minimal Flood Hazard Zone X
Area of Undetermined Flood Hazard Zone D
Channel, Culver t, or Storm SewerLevee, Dike, or Floodwall
Cross Sections with 1% Annual Chance17.5 Water Surface ElevationCoastal Transect
Coastal Transect BaselineProfile BaselineHydrographic Feature
Base Flood Elevation Line (BFE)
Effective LOMRs
Limit of StudyJurisdiction Boundar y
Digital Data Available
No Digital Data Available
Unmapped
This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards
The flood hazard information is derived directly from theauthoritative NFHL web services provided by FEMA. This mapwas exported on 4/5/2019 at 2:25:52 PM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time.
This map image is void if the one or more of the following mapelements do not appear: basemap imagery, flood zone labels,legend, scale bar, map creation date, community identifiers,FIRM panel number, and FIRM effective date. Map images forunmapped and unmodernized areas cannot be used forregulatory purposes.
Legend
OTHER AREAS OFFLOOD HAZARD
OTHER AREAS
GENERALSTRUCTURES
OTHERFEATURES
MAP PANELS
8
1:6,000
B 20.2
The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative proper ty location.
ATTACHMENT 2
HYDRAULIC CALCULATIONS
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Dec 17 2020
Lot 7 Culvert Driveway 100-Year
Invert Elev Dn (ft) = 5090.56
Pipe Length (ft) = 20.00
Slope (%) = 0.50
Invert Elev Up (ft) = 5090.66
Rise (in) = 12.0
Shape = Circular
Span (in) = 12.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Square edge w/headwall (C)
Coeff. K,M,c,Y,k = 0.0098, 2, 0.0398, 0.67, 0.5
Embankment
Top Elevation (ft) = 5092.80
Top Width (ft) = 16.00
Crest Width (ft) = 20.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 2.25
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 2.20
Qpipe (cfs) = 2.20
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 3.20
Veloc Up (ft/s) = 4.19
HGL Dn (ft) = 5091.38
HGL Up (ft) = 5091.29
Hw Elev (ft) = 5091.64
Hw/D (ft) = 0.98
Flow Regime = Inlet Control
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Dec 17 2020
Trench Drain - 100-Year
Rectangular
Bottom Width (ft) = 1.00
Total Depth (ft) = 1.81
Invert Elev (ft) = 100.00
Slope (%) = 1.50
N-Value = 0.012
Calculations
Compute by: Known Q
Known Q (cfs) = 5.12
Highlighted
Depth (ft) = 0.76
Q (cfs) = 5.120
Area (sqft) = 0.76
Velocity (ft/s) = 6.74
Wetted Perim (ft) = 2.52
Crit Depth, Yc (ft) = 0.94
Top Width (ft) = 1.00
EGL (ft) = 1.47
0 .25 .5 .75 1 1.25 1.5
Elev (ft)Depth (ft)Section
99.50 -0.50
100.00 0.00
100.50 0.50
101.00 1.00
101.50 1.50
102.00 2.00
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Dec 17 2020
Valley Pan at East Driveway - 100-Year
Triangular
Side Slopes (z:1) = 60.00, 60.00
Total Depth (ft) = 0.30
Invert Elev (ft) = 100.00
Slope (%) = 1.70
N-Value = 0.012
Calculations
Compute by: Known Q
Known Q (cfs) = 3.00
Highlighted
Depth (ft) = 0.14
Q (cfs) = 3.000
Area (sqft) = 1.18
Velocity (ft/s) = 2.55
Wetted Perim (ft) = 16.80
Crit Depth, Yc (ft) = 0.18
Top Width (ft) = 16.80
EGL (ft) = 0.24
0 5 10 15 20 25 30 35 40 45 50
Elev (ft)Depth (ft)Section
99.75 -0.25
100.00 0.00
100.25 0.25
100.50 0.50
100.75 0.75
101.00 1.00
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Thursday, Dec 17 2020
Sidewalk Culvert and Chase - 100-Year
Rectangular
Bottom Width (ft) = 2.00
Total Depth (ft) = 0.71
Invert Elev (ft) = 100.00
Slope (%) = 0.50
N-Value = 0.013
Calculations
Compute by: Known Q
Known Q (cfs) = 1.50
Highlighted
Depth (ft) = 0.27
Q (cfs) = 1.500
Area (sqft) = 0.54
Velocity (ft/s) = 2.78
Wetted Perim (ft) = 2.54
Crit Depth, Yc (ft) = 0.26
Top Width (ft) = 2.00
EGL (ft) = 0.39
0 .5 1 1.5 2 2.5 3
Elev (ft)Depth (ft)Section
99.75 -0.25
100.00 0.00
100.25 0.25
100.50 0.50
100.75 0.75
101.00 1.00
Reach (ft)
Area Inlet Performance Curve:
Rain Garden Overflow
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 3.1416*Dia.of grate
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate:Nyloplast 24" Dome
Diameter of Grate (ft):2
Open Area of Grate (ft2):1.88
Rim Elevation (ft):5089.60
Reduction Factor:50%
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 5089.60 0.00 0.00 0.00
0.10 5089.70 0.30 1.60 0.30
0.20 5089.80 0.84 2.27 0.84
0.30 5089.90 1.55 2.77 1.55
0.40 5090.00 2.38 3.20 2.38 10-Year
0.50 5090.10 3.33 3.58 3.33
0.60 5090.20 4.38 3.92 3.92
0.70 5090.30 5.52 4.24 4.24
0.80 5090.40 6.74 4.53 4.53
0.90 5090.50 8.05 4.81 4.81
1.00 5090.60 9.42 5.07 5.07 100-Year
10-Year Design Flow =1.80 cfs100-Year Design Flow = 5.12 cfs
5.10.3 HPQ=
5.0)2(67.0 gHAQ=
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00Discharge (cfs)Stage (ft)
Stage -Discharge Curves
Weir Flow
Orifice Flow
Area Inlet Performance Curve:
Detention Pond Overflow
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 2(L + W)
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate:FABRICATED
Length of Grate (ft):3.00
Width of Grate (ft):3.00
Open Area of Grate (ft2):7.65
Grate Elevation (ft):5089.60
Allowable Capacity:0.80
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 5089.60 0.00 0.00 0.00
0.10 5089.70 0.91 10.40 0.91
0.20 5089.80 2.58 14.71 2.58
0.30 5089.90 4.73 18.01 4.73
0.40 5090.00 7.29 20.80 7.29
0.52 5090.12 10.80 23.72 10.80 Q100
0.60 5090.20 13.39 25.48 13.39
0.70 5090.30 16.87 27.52 16.87
0.80 5090.40 20.61 29.42 20.61
0.90 5090.50 24.59 31.20 24.59
1.00 5090.60 28.80 32.89 28.80
100-Year Flow = 10.6 cfs
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00Discharge (cfs)Stage (ft)
Stage -Discharge Curves
Weir Flow
Orifice Flow
5.10.3 HPQ=
5.0)2(67.0 gHAQ=
ATTACHMENT 3
DETENTION POND CALCULATIONS
STATE DRAIN TIME CALCULATIONS
WATER QUALITY CALCULATIONS
LID CALCULATIONS AND EXHIBIT
Project Number:
Project Name:
Project Location:
Date:
Basin Notes
Historic Basin EX A 4.6 cfs
Historic Basin EX OS1 0.4 cfs
Historic Basin EX OS2 0.2 cfs
Total Q100 to the North 5.2 cfs
Proposed Basin A 2.5 cfs
Proposed Basin OS1 0.5 cfs
Proposed Basin OS2 0.2 cfs
Total Q100 to the North 3.2 cfs
Change in Q100 to the North 2.0 cfs Results in a decrease for the 100-year storm.
Basin Notes
Historic Basin EX B 1.9 cfs
Total Q100 to the South 1.9 cfs
Proposed Basin B1 0.1 cfs
Proposed Basin B3 0.0 cfs
Proposed Basin B4 0.2 cfs
Detention Pond Release Rate 1.5 cfs Pond release rate determined by subtracting Basin B1, B3, and
B4 from Basin EX B.
Total Q100 to the South 1.9 cfs
Change in Q100 to the South 0.0 cfs No change for the 100-year storm.
Q100
Historic vs. Developed Flowrates to the North
Historic vs. Developed Flowrates to the South
HISTORIC VS. DEVELOPED FLOWRATES
1013-008
Homestead at Clarendon
Fort Collins, Colorado
Q100
December 18, 2020
Pond No :
B2
100-yr
0.75
12.74 min Storage 7373 ft3
1.63 acres Water Quality 0 ft3
Max Release Rate =1.50 cfs 0.17 ac-ft
Time (min)
Ft Collins
100-yr
Intensity
(in/hr)
Inflow
Volume
(ft3)
Outflow
Adjustment
Factor
Qav
(cfs)
Outflow Volume
(ft3)
Storage
Volume
(ft3)
5 9.950 3649 1.00 1.50 450 3199
10 7.720 5663 1.00 1.50 900 4763
15 6.520 7174 1.00 1.50 1350 5824
20 5.600 8215 1.00 1.50 1800 6415
25 4.980 9132 1.00 1.50 2250 6882
30 4.520 9946 1.00 1.50 2700 7246
35 4.080 10474 1.00 1.50 3150 7324
40 3.740 10973 1.00 1.50 3600 7373
45 3.460 11421 1.00 1.50 4050 7371
50 3.230 11846 1.00 1.50 4500 7346
55 3.030 12224 1.00 1.50 4950 7274
60 2.860 12587 1.00 1.50 5400 7187
65 2.720 12968 1.00 1.50 5850 7118
70 2.590 13298 1.00 1.50 6300 6998
75 2.480 13643 1.00 1.50 6750 6893
80 2.380 13966 1.00 1.50 7200 6766
85 2.290 14278 1.00 1.50 7650 6628
90 2.210 14589 1.00 1.50 8100 6489
95 2.130 14842 1.00 1.50 8550 6292
100 2.060 15110 1.00 1.50 9000 6110
105 2.000 15404 1.00 1.50 9450 5954
110 1.940 15653 1.00 1.50 9900 5753
115 1.890 15943 1.00 1.50 10350 5593
120 1.840 16196 1.00 1.50 10800 5396
*Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2.
DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF
Input Variables Results
Required Detention Volume
Fort Collins, Colorado
1013-008
Homestead at Clarendon
Project Number :
Project Name :
Detention Pond
A =
Tc =
Project Location :
Design Point
C =
Design Storm
Page 1 of 1
1013-008_Pond_FAA_Fort Collins A Lots.xls
Project:
Date:
Outlet Elevation:5086.57 0.17 ac. ft.
Grate Elevation:5089.6 0.19 ac. ft.
Crest of Pond Elev.:5090.6 5089.41
Freeboard.:1.2 ft
Maximum
Elevation
Minimum
Elevation cu. ft.acre ft cu. ft.acre ft
5086.6 N/A 0.0 0 0.0 0.00 0.0 0.00
5087.0 5086.6 567.8 0.4 122.1 0.00 122.1 0.00
5087.5 5087.0 2,375.7 0.5 735.9 0.02 858.0 0.02
5088.0 5087.5 3,379.2 0.5 1,438.7 0.03 2,296.7 0.05
5088.5 5088.0 3,602.6 0.5 1,745.5 0.04 4,042.1 0.09
5089.0 5088.5 3,740.2 0.5 1,835.7 0.04 5,877.8 0.13
5089.5 5089.0 3,809.3 0.5 1,887.4 0.04 7,765.2 0.18
5090.0 5089.5 3,860.6 0.5 1,917.5 0.04 9,682.7 0.22
5090.6 5090.0 3,920.8 0.6 2,334.4 0.05 12,017.1 0.28
Volume at Grate:
Project Number:
Project Location:
Calculations By:
Pond No.:
Detention Pond Stage Storage Curve
Contour Contour
Surface Area
(ft2)
Depth
Incremental Volume Cummalitive Volume
Pond Stage Storage Curve
1013-008
Fort Collins, Colorado
F. Wegert
B2
Elev at Design Volume:
Homestead at Clarendon
12/18/2020
Pond Outlet and Volume Data
Design Volume:
12/17/2020 6:00 PM P:\1013-008\Drainage\Detention\
1013-008_Stage-Storage A Lots.xlsx\Pond
Stormwater Facility Name:
Facility Location & Jurisdiction:
User Input: Watershed Characteristics User Defined User Defined User Defined User Defined
Selected BMP Type =RG Stage [ft]Area [ft^2]Stage [ft]Discharge [cfs]
Watershed Area =1.63 acres 0.00 0 0.00 0.00
Watershed Length =500 ft 0.40 568 0.18 0.37
Watershed Length to Centroid =100 ft 0.90 2,376 0.43 0.58
Watershed Slope =0.018 ft/ft 1.40 3,379 0.68 0.73
Watershed Imperviousness =51.0%percent 1.90 3,603 0.93 0.85
Percentage Hydrologic Soil Group A =0.0%percent 2.40 3,740 1.18 0.96
Percentage Hydrologic Soil Group B =0.0%percent 2.90 3,809 1.43 1.05
Percentage Hydrologic Soil Groups C/D =100.0%percent 3.40 3,861 1.68 1.14
Target WQCV Drain Time =12.0 hours 4.00 3,921 1.93 1.22
2.18 1.30
User Input 2.43 1.37
2.68 1.44
2.84 1.48
2.93 1.51
3.18 1.57
3.43 1.63
3.68 1.69
4.00 1.76
After completing and printing this worksheet to a pdf, go to:
https://maperture.digitaldataservices.com/gvh/?viewer=cswdif
Create a new stormwater facility, and attach the PDF of this
worksheet to that record.
Routed Hydrograph Results
Design Storm Return Period =WQCV 2 Year 5 Year 10 Year 50 Year 100 Year
One-Hour Rainfall Depth =N/A 0.82 1.14 1.40 2.27 2.86 in
CUHP Runoff Volume =0.023 0.048 0.078 0.109 0.228 0.312 acre-ft
Inflow Hydrograph Volume =N/A 0.048 0.078 0.109 0.228 0.312 acre-ft
Time to Drain 97% of Inflow Volume =0.4 1.0 1.3 1.8 2.8 3.3 hours
Time to Drain 99% of Inflow Volume =0.4 1.1 1.4 1.8 2.8 3.4 hours
Maximum Ponding Depth =0.96 0.53 0.83 1.07 2.12 2.88 ft
Maximum Ponded Area =0.06 0.02 0.05 0.06 0.08 0.09 acres
Maximum Volume Stored =0.023 0.005 0.016 0.029 0.111 0.176 acre-ft
Once CUHP has been run and the Stage-Area-Discharge
information has been provided, click 'Process Data' to
interpolate the Stage-Area-Volume-Discharge data and
generate summary results in the table below. Once this is
complete, click 'Print to PDF'.
Stormwater Detention and Infiltration Design Data Sheet
Homestead at Clarendon
Fort Collins, Colorado
SDI-Design Data v2.00, Released January 2020
Location for 1-hr Rainfall Depths (use dropdown):
After providing required inputs above including 1-hour
rainfall depths, click 'Run CUHP' to generate runoff
hydrographs using the embedded Colorado Urban
Hydrograph Procedure.
SDI_Design_Data_v2.00.xlsm, Design Data 12/18/2020, 8:52 AM
Booleans for Message Booleans for CUHP
Watershed L:W 1 CUHP Inputs Complete
Watershed Lc:L 1 CUHP Results Calculated
Watershed Slope FALSE Time Interval
RunOnce 1
CountA 1
Draintime Coeff 0.8
User Precip 1
Equal SA Inputs 1
Equal SD Inputs 1
Stormwater Detention and Infiltration Design Data Sheet
0
1
2
3
4
5
6
0.1 1 10FLOW [cfs]TIME [hr]
100YR IN
100YR OUT
50YR IN
50YR OUT
10YR IN
10YR OUT
5YR IN
5YR OUT
2YR IN
2YR OUT
WQCV IN
WQCV OUT
0
0.5
1
1.5
2
2.5
3
3.5
0.1 1 10 100PONDING DEPTH [ft]DRAIN TIME [hr]
100YR
50YR
10YR
5YR
2YR
WQCV
SDI_Design_Data_v2.00.xlsm, Design Data 12/18/2020, 8:52 AM
Project Number :
Project Name :
Project Location :
Pond No :Calc. By:F. Wegert
Orifice Dia (in):5 9/16
Orifice Area (sf):0.1688
Orifice invert (ft):5086.57
Orifice Coefficient:0.65
Elevation Stage (ft)Velocity (ft/s)Flow Rate (cfs)Comments
5086.57 0.00 0.00 0.00
5086.75 0.18 2.21 0.37
5087.00 0.43 3.42 0.58
5087.25 0.68 4.30 0.73
5087.50 0.93 5.03 0.85
5087.75 1.18 5.66 0.96
5088.00 1.43 6.23 1.05
5088.25 1.68 6.76 1.14
5088.50 1.93 7.24 1.22
5088.75 2.18 7.70 1.30
5089.00 2.43 8.13 1.37
5089.25 2.68 8.54 1.44
5089.41 2.84 8.79 1.48 <-100 Year Elev.
5089.50 2.93 8.92 1.51
5089.75 3.18 9.30 1.57
5090.00 3.43 9.66 1.63
5090.25 3.68 10.00 1.69
5090.50 3.93 10.34 1.74
5090.75 4.18 10.66 1.80
5091.00 4.43 10.97 1.85
5091.25 4.68 11.28 1.90
5091.50 4.93 11.58 1.95
5091.75 5.18 11.87 2.00
ORIFICE RATING CURVE
Orifice Rating Curve
1013-008
Homestead at Clarendon
Fort Collins, Colorado
Pond B2
Orifice Design Data
Project Number :
Project Name :
Project Location :
Pond No :Calc. By:
Q=3.3LH 1.5
Length (L)=10.00 FT
Crest Elevation =5089.70 FT
Depth Above Crest
(ft)
Elevation
(ft)
Flow
(cfs)
0.00 5089.70 0.00
0.10 5089.80 1.04
0.20 5089.90 2.95
0.30 5090.00 5.42
0.40 5090.10 8.35
0.47 5090.17 10.63 Q100
0.50 5090.20 11.67
0.60 5090.30 15.34
0.70 5090.40 19.33
0.80 5090.50 23.61
0.90 5090.60 28.18 Crest of Pond
Q100 = 10.6 CFS
Input Parameters:
Depth vs. Flow:
B2
SHARP-CRESTED WEIR
This equation can be used to derive the stage-discharge relationship for a sharp crested weir where the depth of flow
is small compared to the length of weir. Reference 1) Hydrologic Analysis and Design, Richard H McCuen, Prentice
Hall, 1989. Pg.549.
* where Q is flow rate in CFS
* where L is the crest length of the weir (FT)
* where H is the height of flow over the crest (FT)
Governing Equations:
1013.008
Homestead at Clarendon
Fort Collins, Colorado
F. Wegert
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Friday, Dec 18 2020
Pond Spillway at West Driveway
User-defined
Invert Elev (ft) = 5089.65
Slope (%) = 0.50
N-Value = 0.012
Calculations
Compute by: Known Q
Known Q (cfs) = 10.60
(Sta, El, n)-(Sta, El, n)...
( 0.00, 5090.60)-(4.00, 5090.15, 0.012)-(4.10, 5089.65, 0.012)-(5.00, 5089.73, 0.012)-(114.03, 5090.02, 0.012)
Highlighted
Depth (ft) = 0.26
Q (cfs) = 10.60
Area (sqft) = 6.27
Velocity (ft/s) = 1.69
Wetted Perim (ft) = 68.72
Crit Depth, Yc (ft) = 0.26
Top Width (ft) = 68.50
EGL (ft) = 0.30
-10 0 10 20 30 40 50 60 70 80 90 100 110 120 130
Elev (ft)Depth (ft)Section
5089.00 -0.65
5089.50 -0.15
5090.00 0.35
5090.50 0.85
5091.00 1.35
Sta (ft)
UD
UDUDUDUDT T/ / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / /RAIN GARDENL
A
N
G
D
A
L
E
D
R
I
V
ECLARENDON HILLS DRIVEPROPOSED POND100-YEAR WSE = 5089.411' CURB CUT2' WIDE CONCRETE CHASEPROPOSED DRIVEWAYVERTICAL CURBAND GUTTEROUTLET PIPEOUTLET STRUCTURE2' WIDE METALSIDEWALK CULVERTHEADWALLPROPOSEDTRENCH DRAINPROVIDE 10' WIDEWEIR AT ELEV. 5089.7RAIN GARDENFIGURE 1Spillway InundationFORT COLLINS, COHOMESTEAD AT CLARENDONENGINEERNGIEHTRONRN12.18.2020P:\1013-008\DWG\EXHIBITS\1013-008_OVERFLOW INUNDATION.DWGAREA OF INUNDATIONFROM SPILLWAY
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1.Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =51.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i =0.510
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV =0.17 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area)Area =34,627 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =482 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =cu ft
(Only if a different WQCV Design Volume is desired)
2.Basin Geometry
A) WQCV Depth (12-inch maximum)DWQCV =12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical)Z =0.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin =353 sq ft
D) Actual Flat Surface Area AActual =495 sq ft
E) Area at Design Depth (Top Surface Area)ATop =571 sq ft
F) Rain Garden Total Volume VT=533 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3.Growing Media
4.Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y =ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =cu ft
iii) Orifice Diameter, 3/8" Minimum DO = in
Design Procedure Form: Rain Garden (RG)
Frederick S. Wegert
Northern Engineering
December 17, 2020
Homestead at Clarendon - East Rain Garden
Fort Collins, Colorado
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
1013-008_UD-BMP_v3.07 Rain Garden East.xlsm, RG 12/17/2020, 5:17 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5.Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6.Inlet / Outlet Control
A) Inlet Control
7.Vegetation
8.Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Frederick S. Wegert
Northern Engineering
December 17, 2020
Homestead at Clarendon - East Rain Garden
Fort Collins, Colorado
Choose One
Choose One
Choose One
Sheet Flow-No Energy Dissipation Required
Concentrated Flow-Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
1013-008_UD-BMP_v3.07 Rain Garden East.xlsm, RG 12/17/2020, 5:17 PM
Project:
Date:
Bottom Elevation:5088.6 578 ft3
Overflow Elevation:5089.7 603 ft3
Crest of Pond Elev.:5090.5 5089.7
Freeboard.:0.8 ft 1 ft
Maximum
Elevation
Minimum
Elevation cu. ft.acre ft cu. ft.acre ft
5088.6 N/A 495.2 0 0.0 0.00 0.0 0.00
5089.0 5088.6 542.6 0.4 207.6 0.00 207.6 0.00
5089.5 5089.0 570.8 0.5 278.4 0.01 485.9 0.01
5090.0 5089.5 598.2 0.5 292.3 0.01 778.2 0.02
5090.5 5090.0 625.7 0.5 306.0 0.01 1,084.1 0.02
Water Depth:
Volume at Overflow:
Project Number:
Project Location:
Calculations By:
Pond No.:
Rain Garden Stage Storage Curve
Contour Contour
Surface Area
(ft2)
Depth
Incremental Volume Cummalitive Volume
Pond Stage Storage Curve
1013-008
Fort Collins, Colorado
F. Wegert
East Rain Garden
Elev at Design Volume:
Homestead at Clarendon
12/18/2020
Pond Outlet and Volume Data
Design Volume1:
Notes:
1) The MHFD spreadsheet UD-BMP is a password protected black box that prevents the user from
multiplying the water quality volume by 120% per Fort Collins Stormwater Manual. Therefore, the Design
Volume on this spreadsheet is 482 cu. ft. * 1.2. The 482 cu. ft. is the water quality volume from the UD -
BMP.
12/17/2020 5:30 PM P:\1013-008\Drainage\LID\
1013-008_Stage-Storage East.xlsx\Pond
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1.Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia =51.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100)i =0.510
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV =0.17 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area)Area =31,852 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =444 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER =cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =cu ft
(Only if a different WQCV Design Volume is desired)
2.Basin Geometry
A) WQCV Depth (12-inch maximum)DWQCV =12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical)Z =0.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin =325 sq ft
D) Actual Flat Surface Area AActual =430 sq ft
E) Area at Design Depth (Top Surface Area)ATop =570 sq ft
F) Rain Garden Total Volume VT=500 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3.Growing Media
4.Underdrain System
A) Are underdrains provided?1
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y =ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 =cu ft
iii) Orifice Diameter, 3/8" Minimum DO = in
Design Procedure Form: Rain Garden (RG)
Frederick S. Wegert
Northern Engineering
December 17, 2020
Homestead at Clarendon - West Rain Garden
Fort Collins, Colorado
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
1013-008_UD-BMP_v3.07 Rain Garden West.xlsm, RG 12/17/2020, 5:32 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5.Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6.Inlet / Outlet Control
A) Inlet Control
7.Vegetation
8.Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Frederick S. Wegert
Northern Engineering
December 17, 2020
Homestead at Clarendon - West Rain Garden
Fort Collins, Colorado
Choose One
Choose One
Choose One
Sheet Flow-No Energy Dissipation Required
Concentrated Flow-Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
1013-008_UD-BMP_v3.07 Rain Garden West.xlsm, RG 12/17/2020, 5:32 PM
Project:
Date:
Bottom Elevation:5088.6 533 ft3
Overflow Elevation:5089.7 572 ft3
Crest of Pond Elev.:5090.0 5089.6
Freeboard.:0.4 ft 1 ft
Maximum
Elevation
Minimum
Elevation cu. ft.acre ft cu. ft.acre ft
5088.6 N/A 430.0 0 0.0 0.00 0.0 0.00
5089.0 5088.6 493.3 0.4 184.7 0.00 184.7 0.00
5089.5 5089.0 570.0 0.5 265.8 0.01 450.5 0.01
5090.0 5089.5 647.2 0.5 304.3 0.01 754.8 0.02
Design Volume1:
Volume at Overflow:
Project Number:
Project Location:
Calculations By:
Pond No.:
Water Depth:
West Rain Garden Stage Storage Curve
Contour Contour
Surface Area
(ft2)
Depth
Incremental Volume Cummalitive Volume
Pond Stage Storage Curve
1013-008
Fort Collins, Colorado
F. Wegert
West Rain Garden
Elev at Design Volume:
Homestead at Clarendon
12/18/2020
Pond Outlet and Volume Data
Notes:
1) The MHFD spreadsheet UD-BMP is a password protected black box that prevents the user from
multiplying the water quality volume by 120% per Fort Collins Stormwater Manual. Therefore, the Design
Volume on this spreadsheet is 444 cu. ft. * 1.2. The 444 cu. ft. is the water quality volume from the UD -
BMP.
12/17/2020 5:40 PM P:\1013-008\Drainage\LID\
1013-008_Stage-Storage West.xlsx\Pond
Project:Homestead at Clarendon Calc. By:
Location:Fort Collins, Colorado Date:
39,434 sf
50%
19,717 sf
100%
39,434 sf
35,681 sf
90.5%
578 cf
603 cf
533 cf
572 cf
1111 cf
1175 cf
35,681 sf
90.5%
7,373 cf
7,373 cf
0.17 ac.-ft.
8,149 cf
0.19 ac.-ft.
LID & Water Quality Summary
F. Wegert
12/18/20
Project Summary
LID Summary
Total New Impervious Area
Target LID Treatment Percentage
Minimum Area to be Treated by LID measures
Target Water Quality Treatment Percentage
Detention
Detention Treatment Area
Minimum Area to be Treated by Water Quality measures
Rain Gardens
Rain Garden Treatment Area
East Rain Garden Volume (Required)
East Rain Garden Volume (Design)
West Rain Garden Volume (Required)
Percent Total Project Area Treated
West Rain Garden Volume (Design)
Total Rain Garden Volume (Required)
Total Rain Garden Volume (Design)
Water Quality Summary
Percent Total Project Area Treated
Storage Volume (Required)
Total Detention Volume (Required)
Total Detention Volume (Design)
Project:Calc. By:
Location:Date:
Surface
Area (SF)% Imperv.Imperv.
Area (SF)
Surface
Area (SF)% Imperv.Imperv.
Area (SF)
Rooftop 0 100%0 Rooftop 25,025 90%22,523
Concrete 0 100%0 Concrete 0 100%0
Asphalt 0 100%0 Asphalt 13,158 100%13,158
Gravel 0 40%0 Gravel 9,384 40%3,754
Landscaping 142,798 0%0 Landscaping 95,231 0%0
Total 142,798 0 Total 142,798 39,434
39,434
Surface
Area (SF)% Imperv.Imperv.
Area (SF)
Surface
Area (SF)% Imperv.Imperv.
Area (SF)
Rooftop 25,025 90%22,523 Rooftop 25,025 90%22,523
Concrete 0 100%0 Concrete 0 100%0
Asphalt 13,158 100%13,158 Asphalt 13,158 100%13,158
Gravel 0 40%0 Gravel 0 40%0
Landscaping 0 0%0 Landscaping 0 0%0
35,681 35,681
Additional Impervious Area (SF)
Existing Developed
Onsite Impervious Area
Onsite Impervious Areas
Homestead at Clarendon
Fort Collins, Colorado
F. Wegert
12/18/20
Extended Detention Rain Gardens
Total Total
Developed Imperv. Area with LID TreatmentDeveloped Imperv. Area with WQ Treatment
VAULTELECELECEEVAULTELECCONTROLIRR
CONTROLIRR
CONTROLIRR
CONTROLIRR
CONTROLIRR
CONTROLIRR
CONTROLIRR
CONTROLIRR
X X
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// / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / /CLARENDON HILLS DRIVELANGDALE DR
IVEDETENTION PONDWEST RAIN GARDENREQUIRED VOLUME: 533 CU. FT.MINIMUM FLAT AREA: 325 SFPROVIDED VOLUME: 572 CU. FT.PROVIDED FLAT AREA: 430 SFTREATMENT AREA: 31,852 SFEAST RAIN GARDENREQUIRED VOLUME: 578 CU. FT.MINIMUM FLAT AREA: 353 SFPROVIDED VOLUME: 601 CU. FT.PROVIDED FLAT AREA: 603 SFTREATMENT AREA: 34,627 SFHOMESTEAD AT CLARENDON HILLSSHEET NO:P:\1013-008\DWG\DRNG\1013-008_LID.DWG301 N. Howes Street, Suite 100Fort Collins, Colorado 80521ENGINEERNGIEHTRONRNPHONE: 970.221.4158www.northernengineering.comDRAWING REFERENCE:LID TREATMENT EXHIBITF. Wegert1 in = 60 ftDecember 18, 2020LID-1DRAWN BY:SCALE:ISSUED:( IN FEET )01 INCH = 60 FEET6060LEGENDRAIN GARDEN TREATMENT AREAUNTREATED AREANOTES:1.UNTREATED AREA CONSISTS OF LANDSCAPING ANDLAWNS.2.RAIN GARDEN TREATMENT AREA CONSISTS OFAPPROXIMATELY SOUTH 3/4 OF LOTS (1 - 8), ROOFS,DRIVEWAYS, AND SHARED DRIVEWAY FOR LOTS 2 - 7.Homestead at Clarendon LID SummaryProject SummaryTotal New Impervious Area39,434sfTarget Treatment Percentage50%Minimum Area to be Treated by LID measures19,717sfRain GardensTotal Rain Garden Treatment Area35,681sfTotal Treatment Area35,681sfPercent Total Project Area Treated90.5%
ATTACHMENT 4
PREVIOUS REPORT EXCERPTS
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
Excerpts from Clarendon Hills
1st Filing Drainage Report
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
Excerpts from Clarendon Hills
4th Filing Drainage Report
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
Excerpts from Clarendon Hills
6th Filing Drainage Report
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on Nov-02-2018 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
ATTACHMENT 5
USDA NRCS SOILS REPORT
United States
Department of
Agriculture
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Larimer County
Area, Colorado
Homestead at Clarendon Hills
Natural
Resources
Conservation
Service
April 5, 2019
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface....................................................................................................................2
How Soil Surveys Are Made..................................................................................5
Soil Map..................................................................................................................8
Soil Map................................................................................................................9
Legend................................................................................................................10
Map Unit Legend................................................................................................11
Map Unit Descriptions.........................................................................................11
Larimer County Area, Colorado......................................................................13
4—Altvan-Satanta loams, 3 to 9 percent slopes.........................................13
56—Kim-Thedalund loams, 3 to 15 percent slopes....................................15
74—Nunn clay loam, 1 to 3 percent slopes.................................................17
Soil Information for All Uses...............................................................................19
Soil Properties and Qualities..............................................................................19
Soil Erosion Factors........................................................................................19
Wind Erodibility Index..................................................................................19
Soil Qualities and Features.............................................................................22
Hydrologic Soil Group.................................................................................22
References............................................................................................................27
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil-vegetation-landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil-landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
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6
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
Custom Soil Resource Report
7
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
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9
Custom Soil Resource Report
Soil Map
448531044853304485350448537044853904485410448543044854504485470448531044853304485350448537044853904485410448543044854504485470491850 491870 491890 491910 491930 491950 491970 491990 492010 492030 492050 492070 492090 492110
491850 491870 491890 491910 491930 491950 491970 491990 492010 492030 492050 492070 492090 492110
40° 31' 11'' N 105° 5' 46'' W40° 31' 11'' N105° 5' 34'' W40° 31' 6'' N
105° 5' 46'' W40° 31' 6'' N
105° 5' 34'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 15 30 60 90
Meters
Map Scale: 1:1,260 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 13, Sep 10, 2018
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Sep 20, 2015—Oct
21, 2017
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
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Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
4 Altvan-Satanta loams, 3 to 9
percent slopes
0.4 10.5%
56 Kim-Thedalund loams, 3 to 15
percent slopes
3.4 89.2%
74 Nunn clay loam, 1 to 3 percent
slopes
0.0 0.2%
Totals for Area of Interest 3.8 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
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11
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
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Larimer County Area, Colorado
4—Altvan-Satanta loams, 3 to 9 percent slopes
Map Unit Setting
National map unit symbol: jpwf
Elevation: 5,200 to 6,200 feet
Mean annual precipitation: 13 to 15 inches
Mean annual air temperature: 48 to 50 degrees F
Frost-free period: 135 to 150 days
Farmland classification: Farmland of statewide importance
Map Unit Composition
Altvan and similar soils: 55 percent
Satanta and similar soils: 35 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Altvan
Setting
Landform: Fans, benches, terraces
Landform position (three-dimensional): Base slope, side slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 9 inches: loam
H2 - 9 to 16 inches: clay loam, loam, sandy clay loam
H2 - 9 to 16 inches: loam, fine sandy loam, silt loam
H2 - 9 to 16 inches: gravelly sand, gravelly coarse sand, coarse sand
H3 - 16 to 31 inches:
H3 - 16 to 31 inches:
H3 - 16 to 31 inches:
H4 - 31 to 60 inches:
H4 - 31 to 60 inches:
H4 - 31 to 60 inches:
Properties and qualities
Slope: 6 to 9 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 10 percent
Available water storage in profile: Very high (about 13.7 inches)
Interpretive groups
Land capability classification (irrigated): 4e
Land capability classification (nonirrigated): 4e
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Hydrologic Soil Group: B
Hydric soil rating: No
Description of Satanta
Setting
Landform: Terraces, structural benches
Landform position (three-dimensional): Side slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium and/or eolian deposits
Typical profile
H1 - 0 to 9 inches: loam
H2 - 9 to 14 inches: loam, clay loam, sandy clay loam
H2 - 9 to 14 inches: loam, clay loam, fine sandy loam
H2 - 9 to 14 inches:
H3 - 14 to 60 inches:
H3 - 14 to 60 inches:
H3 - 14 to 60 inches:
Properties and qualities
Slope: 3 to 6 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 10 percent
Available water storage in profile: Very high (about 27.4 inches)
Interpretive groups
Land capability classification (irrigated): 2e
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: B
Hydric soil rating: No
Minor Components
Nunn
Percent of map unit: 6 percent
Hydric soil rating: No
Larimer
Percent of map unit: 4 percent
Hydric soil rating: No
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56—Kim-Thedalund loams, 3 to 15 percent slopes
Map Unit Setting
National map unit symbol: jpx0
Elevation: 4,800 to 5,600 feet
Mean annual precipitation: 13 to 15 inches
Mean annual air temperature: 48 to 50 degrees F
Frost-free period: 135 to 150 days
Farmland classification: Not prime farmland
Map Unit Composition
Kim and similar soils: 45 percent
Thedalund and similar soils: 35 percent
Minor components: 20 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Kim
Setting
Landform: Valley sides, fans
Landform position (three-dimensional): Side slope, base slope
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 7 inches: loam
H2 - 7 to 60 inches: loam, clay loam, sandy clay loam
H2 - 7 to 60 inches:
H2 - 7 to 60 inches:
Properties and qualities
Slope: 3 to 7 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile: Nonsaline to slightly saline (0.0 to 4.0 mmhos/cm)
Available water storage in profile: Very high (about 26.5 inches)
Interpretive groups
Land capability classification (irrigated): 3e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: B
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Ecological site: Loamy Plains (R067XY002CO)
Hydric soil rating: No
Description of Thedalund
Setting
Landform position (three-dimensional): Side slope
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Material weathered from sandstone and shale
Typical profile
H1 - 0 to 4 inches: loam
H2 - 4 to 33 inches: clay loam, loam, sandy clay loam
H2 - 4 to 33 inches: weathered bedrock
H2 - 4 to 33 inches:
H3 - 33 to 37 inches:
Properties and qualities
Slope: 7 to 15 percent
Depth to restrictive feature: 20 to 40 inches to paralithic bedrock
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to high
(0.06 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile: Nonsaline to moderately saline (0.0 to 8.0
mmhos/cm)
Available water storage in profile: Very high (about 15.5 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 6e
Hydrologic Soil Group: C
Ecological site: Loamy Plains (R067XY002CO)
Hydric soil rating: No
Minor Components
Renohill
Percent of map unit: 10 percent
Hydric soil rating: No
Midway
Percent of map unit: 9 percent
Hydric soil rating: No
Aquic haplustolls
Percent of map unit: 1 percent
Landform: Swales
Hydric soil rating: Yes
Custom Soil Resource Report
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74—Nunn clay loam, 1 to 3 percent slopes
Map Unit Setting
National map unit symbol: 2tlpl
Elevation: 3,900 to 5,840 feet
Mean annual precipitation: 13 to 17 inches
Mean annual air temperature: 50 to 54 degrees F
Frost-free period: 135 to 160 days
Farmland classification: Prime farmland if irrigated
Map Unit Composition
Nunn and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Nunn
Setting
Landform: Terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Pleistocene aged alluvium and/or eolian deposits
Typical profile
Ap - 0 to 9 inches: clay loam
Bt - 9 to 13 inches: clay loam
Btk - 13 to 25 inches: clay loam
Bk1 - 25 to 38 inches: clay loam
Bk2 - 38 to 80 inches: clay loam
Properties and qualities
Slope: 1 to 3 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to
moderately high (0.06 to 0.20 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 7 percent
Salinity, maximum in profile: Nonsaline to very slightly saline (0.1 to 2.0
mmhos/cm)
Sodium adsorption ratio, maximum in profile: 0.5
Available water storage in profile: High (about 9.9 inches)
Interpretive groups
Land capability classification (irrigated): 2e
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Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: C
Ecological site: Clayey Plains (R067BY042CO)
Hydric soil rating: No
Minor Components
Heldt
Percent of map unit: 10 percent
Landform: Terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Linear
Ecological site: Clayey Plains (R067BY042CO)
Hydric soil rating: No
Satanta
Percent of map unit: 5 percent
Landform: Terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Linear
Ecological site: Loamy Plains (R067BY002CO)
Hydric soil rating: No
Custom Soil Resource Report
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Soil Information for All Uses
Soil Properties and Qualities
The Soil Properties and Qualities section includes various soil properties and
qualities displayed as thematic maps with a summary table for the soil map units in
the selected area of interest. A single value or rating for each map unit is generated
by aggregating the interpretive ratings of individual map unit components. This
aggregation process is defined for each property or quality.
Soil Erosion Factors
Soil Erosion Factors are soil properties and interpretations used in evaluating the
soil for potential erosion. Example soil erosion factors can include K factor for the
whole soil or on a rock free basis, T factor, wind erodibility group and wind erodibility
index.
Wind Erodibility Index
The wind erodibility index is a numerical value indicating the susceptibility of soil to
wind erosion, or the tons per acre per year that can be expected to be lost to wind
erosion. There is a close correlation between wind erosion and the texture of the
surface layer, the size and durability of surface clods, rock fragments, organic
matter, and a calcareous reaction. Soil moisture and frozen soil layers also
influence wind erosion.
19
20
Custom Soil Resource Report
Map—Wind Erodibility Index
448531044853304485350448537044853904485410448543044854504485470448531044853304485350448537044853904485410448543044854504485470491850 491870 491890 491910 491930 491950 491970 491990 492010 492030 492050 492070 492090 492110
491850 491870 491890 491910 491930 491950 491970 491990 492010 492030 492050 492070 492090 492110
40° 31' 11'' N 105° 5' 46'' W40° 31' 11'' N105° 5' 34'' W40° 31' 6'' N
105° 5' 46'' W40° 31' 6'' N
105° 5' 34'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 15 30 60 90
Meters
Map Scale: 1:1,260 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Soil Rating Lines
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Soil Rating Points
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 13, Sep 10, 2018
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Sep 20, 2015—Oct
21, 2017
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
21
Table—Wind Erodibility Index
Map unit symbol Map unit name Rating (tons per acre
per year)
Acres in AOI Percent of AOI
4 Altvan-Satanta loams, 3
to 9 percent slopes
56 0.4 10.5%
56 Kim-Thedalund loams, 3
to 15 percent slopes
86 3.4 89.2%
74 Nunn clay loam, 1 to 3
percent slopes
48 0.0 0.2%
Totals for Area of Interest 3.8 100.0%
Rating Options—Wind Erodibility Index
Units of Measure: tons per acre per year
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Soil Qualities and Features
Soil qualities are behavior and performance attributes that are not directly
measured, but are inferred from observations of dynamic conditions and from soil
properties. Example soil qualities include natural drainage, and frost action. Soil
features are attributes that are not directly part of the soil. Example soil features
include slope and depth to restrictive layer. These features can greatly impact the
use and management of the soil.
Hydrologic Soil Group
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive precipitation
from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly
wet. These consist mainly of deep, well drained to excessively drained sands or
gravelly sands. These soils have a high rate of water transmission.
Custom Soil Resource Report
22
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well drained
soils that have moderately fine texture to moderately coarse texture. These soils
have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of water
transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay layer at
or near the surface, and soils that are shallow over nearly impervious material.
These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in their
natural condition are in group D are assigned to dual classes.
Custom Soil Resource Report
23
24
Custom Soil Resource Report
Map—Hydrologic Soil Group
448531044853304485350448537044853904485410448543044854504485470448531044853304485350448537044853904485410448543044854504485470491850 491870 491890 491910 491930 491950 491970 491990 492010 492030 492050 492070 492090 492110
491850 491870 491890 491910 491930 491950 491970 491990 492010 492030 492050 492070 492090 492110
40° 31' 11'' N 105° 5' 46'' W40° 31' 11'' N105° 5' 34'' W40° 31' 6'' N
105° 5' 46'' W40° 31' 6'' N
105° 5' 34'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 15 30 60 90
Meters
Map Scale: 1:1,260 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 13, Sep 10, 2018
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Sep 20, 2015—Oct
21, 2017
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
25
Table—Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
4 Altvan-Satanta loams, 3
to 9 percent slopes
B 0.4 10.5%
56 Kim-Thedalund loams, 3
to 15 percent slopes
B 3.4 89.2%
74 Nunn clay loam, 1 to 3
percent slopes
C 0.0 0.2%
Totals for Area of Interest 3.8 100.0%
Rating Options—Hydrologic Soil Group
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Custom Soil Resource Report
26
References
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife
Service FWS/OBS-79/31.
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric
soils in the United States.
National Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.
U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/national/soils/?cid=nrcs142p2_054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for
making and interpreting soil surveys. 2nd edition. Natural Resources Conservation
Service, U.S. Department of Agriculture Handbook 436. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577
Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580
Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section.
United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1.
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
home/?cid=nrcs142p2_053374
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/
detail/national/landuse/rangepasture/?cid=stelprdb1043084
27
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/soils/scientists/?cid=nrcs142p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?
cid=nrcs142p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. http://
www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf
Custom Soil Resource Report
28
ATTACHMENT 6
DRAINAGE EXHIBITS
VAULT
ELEC
ELECE
E
VAULT
ELEC
CONTROL
IRR
CONTROL
IRR CONTROL
IRRCONTROL
IRR
CONTROL
IRR CONTROL
IRR CONTROL
IRR CONTROL
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D
AL
E
D
RI
V
E
FRONT RANGE
COMMUNITY COLLEGE
CLARENDON HILLS
FIRST FILING
EX B
0.68 ac
EX A
2.38 ac
EX OS1
0.15 ac
EX OS2
0.06 ac
EX B
EX A
EX OS2
EX OS1
SMITH
L
A
T
E
R
A
L
EXISTIN
G
P
R
I
V
A
T
E
L
Y
O
W
N
E
D
IRRIGA
T
I
O
N
D
I
T
C
H
(
S
E
E
N
O
T
E
2
)
DR1 HISTORIC DRAINAGE EXHIBIT19
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE, OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
before you dig.Call
R
NORTH
( IN FEET )
1 inch = ft.
Feet03030
30
60 90
SheetHOMESTEAD AT CLARENDON HILLSThese drawings areinstruments of serviceprovided by NorthernEngineering Services, Inc.and are not to be used forany type of constructionunless signed and sealed bya Professional Engineer inthe employ of NorthernEngineering Services, Inc.NOT FOR CONSTRUCTIONREVIEW SETENGINEERNGIEHTRONRNFORT COLLINS: 301 North Howes Street, Suite 100, 80521GREELEY: 820 8th Street, 80631970.221.4158northernengineering.comof 20
LEGEND:
ADESIGN POINT
FLOW ARROW
DRAINAGE BASIN LABEL
EXISTING DRAINAGE BASIN BOUNDARY
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
C
PROPOSED CONTOUR
EXISTING CONTOUR
PROPERTY BOUNDARY
PROPOSED STORM DRAIN / IRRIGATION
EXISTING CURB AND GUTTER
PROPOSED SWALE
PROPOSED LOT LINE
EASEMENT
EXISTING DRAINAGE SUMMARY
Design
Point Basin ID
Total
Area
(acres)
C2 C100 2-Yr Tc
(min)
100-Yr Tc
(min)
Q2
(cfs)
Q100
(cfs)
ex a EX A 2.382 0.25 0.31 14.06 14.06 1.14 5.00
b EX B 0.684 0.25 0.31 12.06 12.06 0.35 1.53
b EX OS1 0.147 0.25 0.31 11.08 11.08 0.08 0.34
b EX OS2 0.064 0.25 0.31 5.42 5.42 0.05 0.20
NOTES:
1.REFER TO THE FINAL DRAINAGE LETTER FOR HOMESTEAD AT CLARENDON HILLS FOR ADDITIONAL
INFORMATION.
2.THE SMITH LATERAL IS OWNED BY NUMEROUS INDIVIDUAL OWNERS AS WELL AS THE CITY OF FORT
COLLINS (THROUGH THE PARKS DEPARTMENT) WHO USE THE DITCH TO CONVEY IRRIGATION
WATER. APPROVAL FROM THE IRRIGATION DITCH OWNERS IS REQUIRED PRIOR TO ANY WORK ON
THE DITCH OR IN ITS EASEMENT, AS WELL AS BEFORE ANY STORMWATER CAN BE DISCHARGED, OR
PLANNED TO BE DISCHARGED INTO THE DITCH. PLEASE CONTACT JILL WUERTZ (970-416-2062), 413 S.
BRYAN AVE, FORT COLLINS, CO 80521 REGARDING THE PARKS' DEPARTMENT'S INTEREST.
BENCHMARK
PROJECT DATUM: NAVD88
CITY OF FORT COLLINS BENCHMARK 5-02
1/2 MILE SOUTH OF HARMONY ROAD, APPROXIMATELY 200 FEET NORTH OF WOODED CREEK COURT, ON
THE WEST SIDE OF SHIELDS STREET, ON THE NORTHWEST CORNER OF A STORM INLET.
ELEV. = 5089.11
CITY OF FORT COLLINS BENCHMARK 8-13
SOUTHEAST CORNER OF HARMONY RD. AND SHIELDS ON THE NORTHEAST CORNER OF A CONCRETE
TRAFFIC SIGNAL BASE.
ELEV. = 5086.71
PLEASE NOTE: THIS PLAN SET IS USING NAVD88 FOR A VERTICAL DATUM. SURROUNDING DEVELOPMENTS
HAVE USED NGVD29 UNADJUSTED (PRIOR CITY OF FORT COLLINS DATUM) FOR THEIR VERTICAL DATUMS.
IF NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) IS REQUIRED FOR ANY PURPOSE,
THE FOLLOWING EQUATION SHOULD BE USED:
NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) = NAVD88 - 3.20'
BASIS OF BEARINGS
THE BASIS OF BEARINGS IS THE WEST LINE OF SECTION 2-6-69 AS BEARING NORTH 00° 17' 10" EAST
(ASSUMED BEARING).
CONTROL
IRR CONTROL
IRR CONTROL
IRR CONTROL
IRR
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D
AL
E
D
RI
V
E ACCESS EASEMENTLOT 6
LOT 7
LOT 8
B3
0.01 ac
OS1
0.09 ac
A
OS1
E
E
E
EEEEPROPOSED RAIN
GARDEN WITH FOREBAY
PROPOSED OUTLET STRUCTURE
CONSTRUCTED AS PART OF WALL
PROPOSED SIDEWALK CULVERT
PROPOSED
TRENCH DRAIN
PROPOSED
DRIVEWAY CULVERT
UNDERDRAIN
VAULT
ELEC
ELECE
E
VAULT
ELEC
CONTROL
IRR
CONTROL
IRR CONTROL
IRRCONTROL
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// / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / /CLARENDON HILLS DRIVE
FRONT RANGE
COMMUNITY COLLEGE
CLARENDON HILLS
FIRST FILING
LOT 1
LOT 2
LOT 3
LOT 5
LOT 4
TRACT A
A
1.37 ac
/ / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / /B1
0.04 ac
B2
1.63 ac
B4
0.01 ac
OS2
0.06 ac
PROPO
S
E
D
D
R
I
V
E
W
A
Y
PROPOSED POND
WSE - 5089.41
B
TRACT B
DITCH ACCESS EASEMENT
(WIDTH VARIES - SEE NOTE 2)
SMITH
L
A
T
E
R
A
L
EXISTIN
G
P
R
I
V
A
T
E
L
Y
O
W
N
E
D
IRRIGA
T
I
O
N
D
I
T
C
H
(
S
E
E
N
O
T
E
2
)
UD
UD
EEE
E
E
E
E
E EEEEEEEPROPOSED RAIN GARDEN WITH FOREBAY
PROPOSED RETAINING WALL
(RE: LANDSCAPE ARCHITECT)
PROPOSED VERTICAL
CURB & GUTTER
PROPOSED OUTLET STRUCTURE
CONSTRUCTED AS PART OF WALL
PROPOSED SIDEWALK CULVERT
WITH CONCRETE CHASE
PROPOSED OUTLET PIPE
PROPOSED VALLEY PAN
POND OVERFLOW /
SPILLWAY ELEV. = 5089.80
UNDERDRAIN
PROVIDE WEIR IN RETAINING WALL AT ELEV.
5089.7 TO ALLOW EMERGENCY FLOWS FROM
POND TO SPILL INTO RAIN GARDEN.
ELEV. AT CURB CUT = 5089.59 TO ALLOW
EMERGENCY SPILLS TO FLOW INTO CURB
DR2 PROPOSED DRAINAGE EXHIBIT20
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE, OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
before you dig.Call
R
NORTH
( IN FEET )
1 inch = ft.
Feet03030
30
60 90
SheetHOMESTEAD AT CLARENDON HILLSThese drawings areinstruments of serviceprovided by NorthernEngineering Services, Inc.and are not to be used forany type of constructionunless signed and sealed bya Professional Engineer inthe employ of NorthernEngineering Services, Inc.NOT FOR CONSTRUCTIONREVIEW SETENGINEERNGIEHTRONRNFORT COLLINS: 301 North Howes Street, Suite 100, 80521GREELEY: 820 8th Street, 80631970.221.4158northernengineering.comof 20
LEGEND:
ADESIGN POINT
FLOW ARROW
DRAINAGE BASIN LABEL
NOTES:
1.REFER TO THE FINAL DRAINAGE LETTER FOR HOMESTEAD AT CLARENDON HILLS FOR ADDITIONAL
INFORMATION.
2.THE SMITH LATERAL IS OWNED BY NUMEROUS INDIVIDUAL OWNERS AS WELL AS THE CITY OF FORT
COLLINS (THROUGH THE PARKS DEPARTMENT) WHO USE THE DITCH TO CONVEY IRRIGATION
WATER. APPROVAL FROM THE IRRIGATION DITCH OWNERS IS REQUIRED PRIOR TO ANY WORK ON
THE DITCH OR IN ITS EASEMENT, AS WELL AS BEFORE ANY STORMWATER CAN BE DISCHARGED, OR
PLANNED TO BE DISCHARGED INTO THE DITCH. PLEASE CONTACT JILL WUERTZ (970-416-2062), 413 S.
BRYAN AVE, FORT COLLINS, CO 80521 REGARDING THE PARKS' DEPARTMENT'S INTEREST.
BENCHMARK
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
C
PROJECT DATUM: NAVD88
CITY OF FORT COLLINS BENCHMARK 5-02
1/2 MILE SOUTH OF HARMONY ROAD, APPROXIMATELY 200 FEET NORTH OF WOODED CREEK COURT, ON
THE WEST SIDE OF SHIELDS STREET, ON THE NORTHWEST CORNER OF A STORM INLET.
ELEV. = 5089.11
CITY OF FORT COLLINS BENCHMARK 8-13
SOUTHEAST CORNER OF HARMONY RD. AND SHIELDS ON THE NORTHEAST CORNER OF A CONCRETE
TRAFFIC SIGNAL BASE.
ELEV. = 5086.71
PLEASE NOTE: THIS PLAN SET IS USING NAVD88 FOR A VERTICAL DATUM. SURROUNDING DEVELOPMENTS
HAVE USED NGVD29 UNADJUSTED (PRIOR CITY OF FORT COLLINS DATUM) FOR THEIR VERTICAL DATUMS.
IF NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) IS REQUIRED FOR ANY PURPOSE,
THE FOLLOWING EQUATION SHOULD BE USED:
NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) = NAVD88 - 3.20'
BASIS OF BEARINGS
THE BASIS OF BEARINGS IS THE WEST LINE OF SECTION 2-6-69 AS BEARING NORTH 00° 17' 10" EAST
(ASSUMED BEARING).
PROPOSED CONTOUR
EXISTING CONTOUR
PROPERTY BOUNDARY
PROPOSED STORM DRAIN / IRRIGATION
EXISTING CURB AND GUTTER
PROPOSED SWALE
PROPOSED LOT LINE
EASEMENT
DEVELOPED DRAINAGE SUMMARY
Design
Point Basin ID
Total
Area
(acres)
C2 C100 2-Yr Tc
(min)
100-Yr Tc
(min)
Q2
(cfs)
Q100
(cfs)
a A 1.368 0.24 0.30 14.25 14.25 0.63 2.74
b B1 0.041 0.29 0.36 12.03 12.03 0.02 0.10
b B2 1.630 0.60 0.75 12.74 12.74 1.98 8.65
b B3 0.013 0.20 0.25 12.26 12.26 0.01 0.02
b B4 0.070 0.25 0.31 11.04 11.04 0.04 0.16
os1 OS1 0.092 0.46 0.57 10.89 10.89 0.09 0.40
os2 OS2 0.064 0.25 0.31 5.00 5.00 0.05 0.20
Detention Pond and Rain Garden Summary
Description Required
Volume
(cu. ft.)
Design
Volume
(cu. ft.)
Release Rate
(cfs)
Crest of Pond
Elev.
Water
Surface Elev.
Freeboard
(ft)
Detention Pond 9,475 9,807 1.2 5090.6 5089.75 0.85
East Rain Garden 297 297 n/a 5090.6 5089.9 0.7
West Rain Garden 297 297 n/a 5090.6 5089.7 0.9
EXISTING DRAINAGE SUMMARY
Design
Point Basin ID
Total
Area
(acres)
C2 C100 2-Yr Tc
(min)
100-Yr Tc
(min)
Q2
(cfs)
Q100
(cfs)
ex a EX A 2.382 0.25 0.31 14.06 14.06 1.14 5.00
b EX B 0.684 0.25 0.31 12.06 12.06 0.35 1.53
b EX OS1 0.147 0.25 0.31 11.08 11.08 0.08 0.34
b EX OS2 0.064 0.25 0.31 5.42 5.42 0.05 0.20
PROPOSED DRAINAGE BASIN BOUNDARY
50' WETLANDS BUFFER
LID & WATER QUALITY SUMMARY
Project Summary
Total New Impervious Area 39,434 sf
Target LID Treatment Percentage 50%
Minimum Area to be Treated by LID measures 19,717 sf
Target Water Quality Treatment Percentage 100%
Minimum Area to be Treated by Water Quality measures 39,434 sf
LID Summary
Rain Gardens
Rain Garden Treatment Area 35,681 sf
Percent Total Project Area Treated 90.5%
East Rain Garden Volume (Required)297 cf
East Rain Garden Volume (Design)273 cf
West Rain Garden Volume (Required)297 cf
West Rain Garden Volume (Design)321 cf
Total Rain Garden Volume (Required)594 cf
Total Rain Garden Volume (Design)594 cf
Water Quality Summary
Detention
Detention Treatment Area 35,681 sf
Percent Total Project Area Treated 90.5%
Water Quality Volume (Required)1,187 cf
Storage Volume (Required)8,288 cf
Total Detention Volume (Required)9,475 cf
0.22 ac.-ft.
Total Detention Volume (Design)9,807 cf
0.23 ac.-ft.
POND INUNDATION AREA
EMERGENCY OVERFLOW PATH