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PRELIMINARY DRAINAGE REPORT
MAXFIELD SUBDIVISION
2ND FILING
FORT COLLINS, COLORADO
SEPTEMBER 27, 2023
NORTHERNENGINEERING.COM
970.221.4158
FORT COLLINS
GREELEY
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FORT COLLINS | GREELEY COVER LETTER
September 27, 2023
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
RE: FINAL DRAINAGE REPORT FOR
MAXFIELD SUBDIVISION 2ND FILING
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage Report for your review. This report
accompanies the Preliminary submittal for the proposed Maxfield Subdivision 2nd Filing.
This report has been prepared in accordance with the Fort Collins Stormwater Criteria Manual (FCSCM) and
serves to document the stormwater impacts associated with the project. We understand that review by the City
of Fort Collins is to assure general compliance with standardized criteria contained in the FCSCM.
If you should have any questions as you review this report, please feel free to contact us.
Sincerely,
NORTHERN ENGINEERING SERVICES, INC.
AMANDA POINCELOT
Project Engineer
Compliance Statement
I hereby attest that this report for the preliminary drainage design for the Gateway Apartments 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 will not assume liability for drainage facilities
designed by others.
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FORT COLLINS | GREELEY TABLE OF CONTENTS
TABLE OF CONTENTS
GENERAL LOCATION AND DESCRIPTION .......................................................... 1
DRAIN BASINS AND SUB-BASINS ..................................................................... 3
DRAINAGE DESIGN CRITERIA .......................................................................... 4
DRAINAGE FACILITY DESIGN ........................................................................... 6
CONCLUSIONS .............................................................................................. 7
REFERENCES ................................................................................................ 8
TABLES AND FIGURES
FIGURE 1 – AERIAL PHOTOGRAPH ...................................................................................1
FIGURE 2 – FEMA FIRMETTE .............................................................................................3
FIGURE 3 – EXISTING CITY FLOODPLAINS .......................................................................3
TABLE 1 - DETENTION SUMMARY .....................................................................................7
APPENDICES
APPENDIX A – HYDROLOGIC COMPUTATIONS
APPENDIX B – HYDRAULIC CALCULATIONS
APPENDIX C –WATER QUALITY/LID COMPUTATIONS
APPENDIX D – EROSION CONTROL REPORT
APPENDIX E – USDA SOILS REPORT
MAP POCKET
DR1 – DRAINAGE EXHIBIT
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GENERAL LOCATION AND DESCRIPTION
A. LOCATION
Vicinity Map
The Maxfield Subdivision 2nd Filing project site is a tract of land located in the southeast quarter of
Section 15, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins,
County of Larimer, State of Colorado.
The project site (refer to Figure 1) is bordered to the north by an existing single-family residential
area; to the south by Prospect Road; to the east by Shields Street; and to the west by an existing
single-family residential area.
B. DESCRIPTION OF PROPERTY
The Maxfield Subdivision 2nd Filing is a ± 0.67-acre tract.
The site is currently zoned as Neighborhood Conservation, Buffer District (N-C-B) with one
existing residential structure on site.
The subject property is not located within a FEMA floodplain or within a City of Fort Collins
regulatory floodplain.
Figure 1 – Aerial Photograph
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FORT COLLINS | GREELEY 2 | 11
The existing groundcover consists of grass with tree cover, a residential structure, and an asphalt
driveway. The existing on-site runoff of the western two thirds of the property generally drains
from the east-to-southwest where it sheet flows to the adjacent properties to the south and west.
The existing on-site runoff of the eastern third of the property generally drains from the west-to-
east across moderately flat grades (e.g., <6.00%) onto Shields Street. From there, the drainage
continues to Prospect Road, and is received by the New Mercer Canal.
According to the United States Department of Agriculture (USDA) Natural Resources Conservation
Service (NRCS) Soil Survey, the site consists primarily of Altvan-Satana loams which fall into
Hydrologic Soil Group B.
The proposed development is an 8-unit complex. Consisting of a conversion of the existing
residential structure to a 2-unit complex and the addition of (3) 2-unit interconnected structures.
Other proposed improvements include a new drive aisle consisting of concrete and concrete
pavers, new sidewalks and new landscaping, a mailroom with bike storage, and a patio common
area.
The proposed land use is Multi-Family Residential. This is a permitted use in the existing
Neighborhood Conservation Buffer (NCB) zoning between CSU/Downtown and the residential
neighborhoods to the west.
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C. FLOODPLAIN
The subject property is not located within a FEMA floodplain or within a City regulatory
floodplain.
Figure 2 – FEMA FIRMette
Figure 3 – Existing City Floodplains
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DRAIN BASINS AND SUB-BASINS
A. MAJOR BASIN DESCRIPTION
1. The Maxfield Subdivision 2nd Filing project is located within the Canal Importation Basin. The
Canal Importation Basin encompasses almost five square miles (3,200 acres) of west-central Fort
Collins. Three irrigation canals pass through the basin flowing generally from north to south. The
runoff from the Maxfield Subdivision 2nd Filing, is received by the New Mercer Canal which
generally flows west to east.
B. SUB-BASIN DESCRIPTION
The project site is broken up into three sub-basins. The central basin and western basin are
connected via a subdrain that receives infiltration from the pavers located in the drive isle within
both basins. The eastern basin flows to the proposed detention pond adjacent to Shields Street.
The project site has one outfall location which is the existing flowline of Shields Street.
The project site does not receive notable runoff from contiguous off-site properties.
DRAINAGE DESIGN CRITERIA
A. STORMWATER MANAGEMENT STRATEGY
The overall stormwater management strategy employed with Maxfield Subdivision 2nd Filing utilizes
the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters. The
following is a description of how the proposed development has incorporated each step.
Step 1 – Employ Runoff Reduction Practices. Maxfield Subdivision 2nd Filing aims to reduce runoff
peaks, volumes and pollutant loads from frequently occurring storm events (i.e., water quality (i.e.,
80th percentile) and 2-year storm events) by implementing Low Impact Development (LID) strategies.
Wherever practical, runoff will be routed across landscaped areas or through Permeable Interlocking
Concrete Pavers (PICP). These LID practices reduce the overall amount of impervious area, while at
the same time Minimizing Directly Connected Impervious Areas (MDCIA). The combined LID/MDCIA
techniques will be implemented, where practical, throughout the development, thereby slowing
runoff and increasing opportunities for infiltration.
Step 2 – Implement BMPs that Provide a Water Quality Capture Volume (WQCV) with Slow
Release. The efforts taken in Step 1 will help to minimize excess runoff from frequently occurring
storm events; however, urban development of this intensity will still have stormwater runoff leaving
the site. The primary water quality treatment will occur via Permeable Interlocking Concrete Pavers
(PICP) to a subdrain beneath the parking and drive isle from the northwest part of the site that flows
to the detention pond in the east. In addition to LID treatment, traditional water quality treatment
will be provided within the lower stages of the detention pond.
Step 3 – Stabilize Drainageways. The Maxfield Subdivision 2nd Filing project aims to protect the
existing New Mercer Canal by limiting any increases beyond historical flow rates within the ditch. By
utilizing a combination of LID, traditional water quality treatment, and a detention pond. As such, the
peak discharge from the Maxfield Subdivision 2nd Filing project will not be compounded with peak
flow in the ditch. Furthermore, this project will pay a one-time stormwater development fee, as well
as ongoing monthly utility fees, both of which help achieve citywide drainage stability.
Step 4 – Implement Site Specific and Other Source Control BMPs. This step typically applies to
industrial and commercial developments.
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B. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS
The subject property is part of the Canal Importation Basin Master Drainage Plan.
The site plan is constrained on the north, south, and west by residential properties, on the east
side by Shields Street.
C. HYDROLOGICAL CRITERIA
The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in Figure 3.4-1
of the FCSCM, serve as the source for all hydrologic computations associated with the Maxfield
Subdivision 2nd Filing development. Tabulated data contained in Table 3.4-1 has been utilized for
Rational Method runoff calculations.
The Rational Method has been employed to compute stormwater runoff utilizing coefficients
contained in Tables 4.1-2 and 4.1-3 of the FCSCM.
Two separate design storms have been utilized to address distinct drainage scenarios. The first
event analyzed is the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The
second event considered is the “Major Storm,” which has a 100-year recurrence interval.
D. HYDRAULIC CRITERIA
The drainage facilities proposed with the Maxfield Subdivision 2nd Filing development project are
designed in accordance with criteria outlined in the Mile High Flood District’s “Urban Storm
Drainage Criteria Manual” (UDFCD) and Fort Collins Stormwater Criteria Manual (FCSCM).
As stated in Section I.B.3, above, the subject property is not located within a FEMA floodplain or
within a City of Fort Collins regulatory floodplain.
E. CONFORMANCE WITH WATER QUALITY TREATMENT CRITERIA
City Code requires that 100% of runoff from a project site receive some sort of water quality
treatment. This project proposes to provide water quality treatment through the use of Permeable
Interlocked Concrete Pavers (PICP) and traditional water within the lower stages of the detention
pond. Through these methods 100% of the on-site area will be treated for water quality.
F. CONFORMANCE WITH LOW IMPACT DEVELOPMENT (LID)
The project site will conform with the requirement to treat a minimum of 50% of the proposed
impervious surfaces using LID treatment from PICP pavers. Please see Appendix C for LID design
information, table, and exhibit(s). As shown in the LID table provided in the appendix, 74.2% of the
proposed site impervious area will receive LID treatment from PICP pavers, which exceeds the
minimum required.
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G. SIZING OF LID SYSTEMS
Permeable Pavers Systems
The type of Permeable Pavement sections chosen for this project are Permeable Interlocked
Concrete Pavers.
The effective imperviousness of area tributary to permeable pavement, the tributary watershed
area and the area of the permeable pavement system were used to determine the required
storage volumes for each area of PICPs.
The minimum depth of reservoir, the slope of the subgrade, the porosity of the subgrade, the
slope of the subgrade interface, and the length between lateral flow barriers were used to
determine the volume provided based on the depth of base course.
DRAINAGE FACILITY DESIGN
A. GENERAL CONCEPT
The main objective of the Maxfield Subdivision 2nd Filing project drainage design is to maintain
existing drainage patterns, while not adversely impacting adjacent properties.
A list of tables and figures used within this report can be found in the Table of Contents at the
front of the document. The tables and figures are located within the sections to which the content
best applies.
Drainage for the project site has been analyzed using three (3) drainage sub-basins, designated as
sub-basins A1, A2, and A3. The drainage patterns anticipated for the basins are further described
below.
Sub-Basin A1
Sub-basin A1 is comprised of a section of the drive Isle, portions of the multi-family development,
vegetated area and the detention pond. Drainage is routed through the pond via grades and a
concrete pan.
Sub-Basin A2
Sub-basin A2 is comprised of portions of the multifamily development including the drive isle.
Drainage is routed to Paver 2 where it will be treated for LID prior to infiltration and release via
subdrain to the pond.
Sub-Basin A3
Sub-basin A3 is comprised of portions of the multifamily development including the parking and
drive isle, and vegetated area. Drainage is routed to Paver 1 where it will be treated for LID prior
to infiltration and release via subdrain to the pond.
A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of this report.
B. SPECIFIC DETAILS
Maxfield Subdivision 2nd Filing is bounded by residential lots to the north, south and west and
adjacent to Shields Street on the east. The site will be discharging to Shields Street. In order to
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reduce runoff peaks, volumes and pollutant loads from urbanizing areas, LID strategies and a
detention pond are proposed.
Maxfield Subdivision 2nd Filing proposed providing 100-year detention, and utilizing extended
detention for water quality.
Pervious Interlocked Concrete Pavers are proposed to treat on-site runoff and conform with LID
practices established in the UDFCD and Fort Collins Stormwater Criteria Manual.
Detention Pond Calculations
1. Detention Pond Calculations were done via FAA Modified method as described in Chapter 6,
Section 2.3 in the City of Fort Collins Stormwater Criteria Manual.
Pond
ID
Tributary
Area (ac)
Weighted
Percent
Imperviousness
(%)
Extended
Detention
WQCV (ac-
ft)
LID
WQCV
(ac-ft)
100-Yr
Detention
Vol. (ac-
ft)
Total Pond
Volume
(ac-ft)
100-Yr
Detention
WSEL (ft)
Final
Release
Rate
(cfs)
Pond 1 0.25 31 0.004 N/A 0.064 0.068 5037.40 0.60
Paver 1 0.20 70 N/A 0.009 N/A N/A N/A N/A
Paver 2 0.21 39 N/A 0.013 N/A N/A N/A N/A
Table 1 - Detention Summary
CONCLUSIONS
A. COMPLIANCE WITH STANDARDS
The detention design proposed with the Maxfield Subdivision 2nd Filing project does comply with
the City of Fort Collins’ Stormwater Criteria Manual.
The drainage design proposed with the Maxfield Subdivision 2nd Filing complies with the City of
Fort Collins Canal Importation Master Drainage Plan.
The drainage plan and stormwater management measures proposed with the Maxfield
Subdivision 2nd Filing project are compliant with all applicable State and Federal regulations
governing stormwater discharge.
B. DRAINAGE CONCEPT
The drainage design proposed with this project will effectively limit potential damage associated
with its stormwater runoff.
The proposed Maxfield Subdivision 2nd Filing development will not impact the Master Drainage
Plan recommendations for the Canal Importation Basin.
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REFERENCES
1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities ,
November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services.
2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance
No. 159, 2018, and referenced in Section 26-500 of the City of Fort Collins Municipal Code.
3. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service,
United States Department of Agriculture.
4. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District,
Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008.
5. Canal Importation Basin Master Drainage Plan Hydraulic Evaluation and Mapping Update, City of
Fort Collins, Colorado, Anderson Consulting Engineers, Inc., Fort Collins, Colorado, July 22, 2014.
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: MAXFIELD SUBDIVISON 2nd FILING
FORT COLLINS | GREELEY APPENDIX
APPENDIX A
HYDROLOGIC COMPUTATIONS
Runoff Coefficient1
Percent
Impervious1 Project:
Location:
0.95 100%Calc. By:
0.95 90%Date:
0.15 2%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt, Concrete
(acres)Rooftop (acres)
Lawns, Sandy Soil,
Avg Slope 2-7%
(acres)
Percent
Impervious
C2*Cf
Cf = 1.00
C5*Cf
Cf = 1.00
C10*Cf
Cf = 1.00
C100*Cf
Cf = 1.25
HA1 10,496 0.24 0.08 0.03 0.14 0.00 43% 0.50 0.50 0.50 0.62
HA2 18,660 0.43 0.02 0.02 0.39 0.00 11% 0.23 0.23 0.23 0.28
Total 29,156 0.67 0.10 0.05 0.52 0.00 23% 0.32 0.32 0.32 0.41
HISTORIC RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Lawns, Sandy Soil, Avg Slope 2-7%
Streets, Parking Lots, Roofs, Alleys, and Drives:
Character of Surface:Maxfield Subdivision 2nd Filing
Fort Collins
J. Obanion
Sep. 27, 2023
2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins
Stormwater Manual (FCSM).USDA SOIL TYPE: B
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.
Notes:
1) A1 drains Southeast to Shields Street
2) A2 drainas Southwest to adjacent property line
Page 1 of 3
Where:
C2*Cf C100*Cf
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Ti
2-Yr
(min)
Ti
100-Yr
(min)
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)Surface n
Flow
Area3
(sq.ft.)
WP3 (ft)R (ft)V
(ft/s)
Tt
(min)
Max.
Tc
(min)
Comp.
Tc 2-Yr
(min)
Tc
2-Yr
(min)
Comp.
Tc 100-
Yr
(min)
Tc
100-Yr
(min)
HA1 ha1 0.50 0.62 37 38.77 37.95
2.21%5.26 4.17 121 37.95 35.55
1.99%Swale (8:1)0.035 8.00 16.12 0.50 3.77 0.53 10.88 5.80 5.80 4.71 5.00
HA2 ha2 0.23 0.28 55 38.69 37.46 2.23%9.28 8.68 126 37.46 36.25 0.96% Swale (8:1)0.035 8.00 16.12 0.50 2.61 0.80 11.01 10.09 10.09 9.49 9.49
total Total 0.36 0.45 37 38.77 37.95 2.21%6.44 5.65 121 37.95 35.55 1.99% Swale (8:1)0.035 8.00 16.12 0.50 3.77 0.53 10.88 6.98 6.98 6.18 6.18
Notes
S = Longitudinal Slope, feet/feet
R = Hydraulic Radius (feet)
n = Roughness Coefficient
V = Velocity (ft/sec) WP = Wetted Perimeter (ft)
HISTORIC TIME OF CONCENTRATION COMPUTATIONS
Location:
Maximum Tc:Overland Flow, Time of Concentration:
Channelized Flow, Velocity: Channelized Flow, Time of Concentration:
Maxfield Subdivision 2nd
Filing
Fort Collins
J. Obanion
Sep. 27, 2023
Project:
Calculations By:
Date:
Design
Point Basin ID
Overland Flow Channelized Flow Time of Concentration
(Equation 3.3-2 per Fort Collins Stormwater =1.87 1.1 − ∗
=1.49
∗
/ ∗ (Equation 5-4 per Fort Collins Stormwater
=
180 + 10
(Equation 3.3-5 per Fort Collins
Stormwater Manual)
=
∗ 60
(Equation 5-5 per Fort Collins
1) Add 4900 to all elevations.
2) Per Fort Collins Stormwater Manual, minimum Tc = 5
min.
3) Assume a water depth of 6" and a typical curb and
gutter per Larimer County Urban Street Standard Detail
701 for curb and gutter channelized flow. Assume a water
depth of 1', fixed side slopes, and a triangular swale
section for grass channelized flow. Assume a water depth
Page 2 of 3
Tc2 Tc10 Tc100 C2 C10 C100 I2 I10 I100 Q2 Q10 Q100
HA1 ha1 0.24 5.8 5.8 5.0 0.5 0.5 0.6 2.8 4.7 10.0 0.3 0.6 1.5
HA2 ha2 0.43 10.1 10.1 9.5 0.2 0.2 0.3 2.2 3.8 8.0 0.2 0.4 1.0
total Total 0.67 7.0 7.0 6.2 0.3 0.3 0.4 2.6 4.4 9.3 0.6 1.0 2.5
Runoff CTc (Min)
HISTORIC DIRECT RUNOFF COMPUTATIONS
Intensity (in/hr)Flow (cfs)
Maxfield Subdivision 2nd
Filing
J. Obanion
Sep. 27, 2023Date:
Fort Collins
Project:
Location:
Calc. By:
Design
Point Basin
Intensity, I, from Fig. 3.4.1 Fort Collins Stormwater Manual.
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Area
(acres)
Page 3 of 3
Runoff Coefficient1
Percent
Impervious1 Project:
Location:
0.95 100%Calc. By:
0.95 90%Date:
0.50 40%
0.15 2%
0.00 0%
0.00 0%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt, Concrete
(acres)Rooftop (acres) Pavers (acres)
Lawns, Sandy Soil,
Avg Slope 2-7%
(acres)
Percent
Impervious
C2*Cf
Cf = 1.00
C5*Cf
Cf = 1.00
C10*Cf
Cf = 1.00
C100*Cf
Cf = 1.25
DA1 11,023 0.25 0.05 0.03 0.00 0.18 0.00 31% 0.40 0.40 0.40 0.50
DA2 8,866 0.20 0.07 0.05 0.06 0.02 0.00 70% 0.74 0.74 0.74 0.92
DA3 9,267 0.21 0.05 0.02 0.04 0.11 0.00 39% 0.47 0.47 0.47 0.58
Total 29,156 0.67 0.17 0.10 0.09 0.31 0.00 45% 0.52 0.52 0.52 0.65
Lawns and Landscaping:
2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins
Stormwater Manual (FCSM).USDA SOIL TYPE: B
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.
DEVELOPED RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Pavers
Lawns, Sandy Soil, Avg Slope 2-7%
Streets, Parking Lots, Roofs, Alleys, and Drives:
Character of Surface:Maxfield Subdivision 2nd Filing
Fort Collins
J. Obanion
Sep. 27, 2023
Notes:
1) A1 drains Southeast to Shields Street
2) A2 drainas Southwest to adjacent property line
Page 1 of 3
Where:
C2*Cf C100*Cf
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)
Ti
2-Yr
(min)
Ti
100-Yr
(min)
Length
(ft)
Elev
Up
Elev
Down
Slope
(%)Surface n
Flow
Area3
(sq.ft.)
WP3 (ft)R (ft)V
(ft/s)
Tt
(min)
Max.
Tc
(min)
Comp.
Tc 2-Yr
(min)
Tc
2-Yr
(min)
Comp.
Tc 100-
Yr
(min)
Tc
100-Yr
(min)
DA1 da1 0.40 0.50 35 38.77 38.00
2.20%5.98 5.14 152 38.00 36.00
1.32%Swale (6:1)0.035 6.00 12.17 0.49 3.05 0.83 11.04 6.81 6.81 5.97 5.97
DA2 da2 0.74 0.92 35 39.37 37.61
5.03%2.35 1.16 120 37.61 36.73
0.73%Swale (8:1)0.035 8.00 16.12 0.50 2.29 0.88 10.86 3.22 5.00 2.03 5.00
DA3 da3 0.47 0.58 35 37.86 37.50
1.03%6.95 5.68 54 37.50 37.21
0.54%Swale (8:1)0.035 8.00 16.12 0.50 1.96 0.46 10.49 7.41 7.41 6.14 6.14
total Total 0.52 0.65 35 37.86 37.50 1.03%6.34 4.91 120 37.61 36.73 0.73% Swale (8:1)0.035 8.00 16.12 0.50 2.29 0.88 10.86 7.21 7.21 5.78 5.78
Design
Point Basin ID
Overland Flow Channelized Flow Time of Concentration
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Location:
Maximum Tc:Overland Flow, Time of Concentration:
Channelized Flow, Velocity: Channelized Flow, Time of Concentration:
Maxfield Subdivision 2nd
Filing
Fort Collins
J. Obanion
Sep. 27, 2023
Project:
Calculations By:
Date:
Notes
S = Longitudinal Slope, feet/feet
R = Hydraulic Radius (feet)
n = Roughness Coefficient
V = Velocity (ft/sec) WP = Wetted Perimeter (ft)
(Equation 3.3-2 per Fort Collins Stormwater =1.87 1.1 − ∗
=1.49
∗
/ ∗ (Equation 5-4 per Fort Collins Stormwater
=
180 + 10
(Equation 3.3-5 per Fort Collins
Stormwater Manual)
=
∗ 60
(Equation 5-5 per Fort Collins
1) Add 4900 to all elevations.
2) Per Fort Collins Stormwater Manual, minimum Tc = 5
min.
3) Assume a water depth of 6" and a typical curb and
gutter per Larimer County Urban Street Standard Detail
701 for curb and gutter channelized flow. Assume a water
depth of 1', fixed side slopes, and a triangular swale
section for grass channelized flow. Assume a water depth
Page 2 of 3
Tc2 Tc10 Tc100 C2 C10 C100 I2 I10 I100 Q2 Q10 Q100
DA1 da1 0.25 6.8 6.8 6.0 0.4 0.4 0.5 2.6 4.4 9.6 0.3 0.4 1.2
DA2 da2 0.20 5.0 5.0 5.0 0.7 0.7 0.9 2.9 4.9 10.0 0.4 0.7 1.9
DA3 da3 0.21 7.4 7.4 6.1 0.5 0.5 0.6 2.5 4.3 9.3 0.2 0.4 1.2
total Total 0.67 7.2 7.2 5.8 0.5 0.5 0.7 2.5 4.3 9.6 0.9 1.5 4.2
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Area
(acres)
Runoff CTc (Min)
DEVELOPED DIRECT RUNOFF COMPUTATIONS
Intensity (in/hr)Flow (cfs)
Maxfield Subdivision 2nd
Filing
J. Obanion
Sep. 27, 2023Date:
Fort Collins
Project:
Location:
Calc. By:
Design
Point Basin
Intensity, I, from Fig. 3.4.1 Fort Collins Stormwater Manual.
Page 3 of 3
Pond No :
A1
100-yr
0.70
5.00 min 2770 ft3
0.67 acres 0.064 ac-ft
Max Release Rate =0.60 cfs
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 1400 1.00 0.60 180 1220
10 7.720 2172 1.00 0.60 360 1812
15 6.520 2752 1.00 0.60 540 2212
20 5.600 3152 1.00 0.60 720 2432
25 4.980 3503 1.00 0.60 900 2603
30 4.520 3816 1.00 0.60 1080 2736
35 4.080 4018 1.00 0.60 1260 2758
40 3.740 4210 1.00 0.60 1440 2770
45 3.460 4381 1.00 0.60 1620 2761
50 3.230 4545 1.00 0.60 1800 2745
55 3.030 4690 1.00 0.60 1980 2710
60 2.860 4829 1.00 0.60 2160 2669
65 2.720 4975 1.00 0.60 2340 2635
70 2.590 5102 1.00 0.60 2520 2582
75 2.480 5234 1.00 0.60 2700 2534
80 2.380 5358 1.00 0.60 2880 2478
85 2.290 5477 1.00 0.60 3060 2417
90 2.210 5597 1.00 0.60 3240 2357
95 2.130 5694 1.00 0.60 3420 2274
100 2.060 5797 1.00 0.60 3600 2197
105 2.000 5909 1.00 0.60 3780 2129
110 1.940 6005 1.00 0.60 3960 2045
115 1.890 6116 1.00 0.60 4140 1976
120 1.840 6213 1.00 0.60 4320 1893
*Note: Using the method described in FCSCM Chapter 6 Section 2.3
DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF
Input Variables Results
Required Detention Volume
Fort Collins, Colorado
2047-001
Maxfield Subdivison 2nd Filing
Project Number :
Project Name :
Pond 1
A =
Tc =
Project Location :
Design Point
C =
Design Storm
Page 1 of 1
2047-001_FAAModified
Pond Stage-Storage Curve
Pond: 1
Project: 2047-001 Maxfield Subdivision 2nd Filing
By: JFO
Date: 09/27/2023
Stage
(FT)
Contour Area
(SF)
Volume
(CU.FT.)
Volume
(AC-FT)
5,036.00 322.56 0.000 0.000
5,036.20 801.99 112.450 0.003
5,036.26 919.63 170 0.004 WQCV
5,036.40 1,214.10 314.060 0.007
5,036.60 1,566.11 592.080 0.014
5,036.80 1,933.90 938.780 0.022
5,037.00 2,858.03 1417.970 0.033
5,037.20 3,865.41 2090.310 0.048
5,037.39 5,126.52 2962.08 0.068 100-YR DETENTION
5,037.40 5,172.90 2994.140 0.069
5,037.60 2,269.80 3625.330 0.083
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: MAXFIELD SUBDIVISON 2nd FILING
FORT COLLINS | GREELEY APPENDIX
APPENDIX B
HYDRAULIC CALCULATIONS
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: MAXFIELD SUBDIVISON 2nd FILING
FORT COLLINS | GREELEY APPENDIX
APPENDIX C
WATER QUALITY/LID COMPUTATIONS
MBMBMB
FO
FO
OH
U
OH
U
OH
U
OH
U
OH
U
OHU OHU
FO
FO
X
X
X
X
G
G
G
G
E
E
E
E E E
0.25 ac.
A1
0.21 ac.
A3
0.20 ac.
A2
a3
a2
a1
SO
U
T
H
S
H
I
E
L
D
S
S
T
R
E
E
T
DETENTION POND 1
PROPOSED 6" PVC UNDERDRAIN @0.2%
PAVER 1
PAVER 2
UD UD UD UD
UD
DRAWN BY:
SCALE:
ISSUED:
MAXFIELD SUBDIVISION
2ND FILING
SHEET NO:
FORT COLLINS: 301 North Howes Street, Suite 100, 80521
GREELEY: 820 8th Street, 80631
E N G I N E E R N GI
EHTRON R N
970.221.4158
northernengineering.com
LID EXHIBIT
J. OBanion
1in=30ft
09/27/23
PROPOSED STORM SEWER
PROPOSED CURB & GUTTER
PROPERTY BOUNDARY
PROPOSED INLET
aDESIGN POINT
DRAINAGE BASIN LABEL
DRAINAGE BASIN BOUNDARY
A
LEGEND:
( IN FEET )
1 inch = ft.
Feet03030
30
PERMEABLE PAVER LIMITS
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
On-Site LID Treatment
Project Summary
Total Impervious Area 13,237 sf
Target Treatment Percentage 50%
Minimum Area to be Treated by LID measures 6,619 sf
Permeable Paver Area
Paver 1 Impervious Area 4,543 sf
Run-on area for Paver 1 2,998 sf
Total Pavers Treatment Area 1,545 sf
Impervious Run-on Ratio for Pavers 1 (2:1 Max) 2 :1
Paver 2 Impervious Area 7,892 sf
Run-on area for Paver 2 5,593 sf
Total Pavers Treatment Area 2,299 sf
Impervious Run-on Ratio for Pavers 2 (2:1 Max) 2 :1
Total Treatment Area 9,820 sf
Percent Total Project Area Treated 74.2%
AREA TREATED BY PAVER 1
AREA TREATED BY PAVER 2
*SEE RATIONAL CALCS FOR IMPERVIOUS AREA CALCULATIONS
Project Number:Project:
Project Location:
Calculations By:Date:
Sq. Ft. Acres
A1 11,023 0.25 31%n/a Traditional 142 3,417
A2 8,866 0.20 70%Pavers 1 Pavers 163 6,206
A3 9,267 0.21 39%Pavers 2 Pavers 109 3,614
Total 29,156 0.67 13,237
Sq. Ft. Acres
Pavers 1 8,866 0.20 70% 6,206
A2 Pavers 371
Pavers 2 9,267 0.21 39% 3,614
A3 Pavers 552
Total 18,133 0.42 9,820 923
Treatment via
Traditional
Sq. Ft.Acres
Pond 1 11,023 0.25 31% 3,417
A1 Extended Detention 170
Total 11,023 0.25 3,417
29,156 ft2
13,237 ft2
6,619 ft2
9,820 ft2
74.19%
3,417 ft2
25.81%
100.00%
Total Impervious Area Treated by Traditional WQ
Percent Impervious Treated by Traditional Water Quality
WQ Treatment Tributary Area Weighted %
Impervious
LID Site Summary - New Impervious Area
Treatment Type Volume per
MHFD-
Percent Impervious Treated by PICP
Subbasin IDImpervious
Area (ft2)
Percent Impervious Area Treated by Traditional WQ or LID
Total Impervious Area Treated by PICP
50% Required Minimum Area to be Treated by PICP
Total Area of Current Development
Total Impervious Area
LID Summary
AreaBasin ID WQ Treatment Type
Percent
Impervious LID ID
Maxfield Subdivision 2nd Filing
9/27/2023
2047-001
Fort Collins, Colorado
A. Boese
Total Impervious
Area (ft2)
Tributary Area Weighted %
Impervious
Required
Volume (ft3)
LID Summary per Basin
Subbasin ID Treatment TypeWQ Treatment
Volume per
UD-BMP or
FAA (ft3)
Impervious
Area (ft2)
Water Quality Treatment via LID
Project Title Date:
Project Number Calcs By:
City
Basins
1
WQCV = Watershed inches of Runoff (inches)31%
a = Runoff Volume Reduction (constant)
i = Total imperviousness Ratio (i = Iwq/100)0.155 in
0.25 ac
0.0033 ac-ft 142 cu. ft.
0.0039 ac-ft 170 cu. ft.
V = Water Quality Design Volume (ac-ft)
WQCV = Water Quality Capture Volume (inches)
A = Watershed Area (acres)
V =
V (120%) =
A =
Maxfield Subdivision 2nd Filing September 27, 2023
2047-001 A. Boese
Fort Collins
Pond 1
Drain Time
a =
i =
WQCV =
Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event
0.231
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 0.
1
0.
2
0.
3
0.
4
0.
5
0.
6
0.
7
0.
8
0.
9
1
WQ
C
V
(
w
a
t
e
r
s
h
e
d
i
n
c
h
e
s
)
Total Imperviousness Ratio (i = Iwq/100)
Water Quality Capture Volume
6 hr
12 hr
24 hr
40 hr
()iii78.019.10.91aWQCV 23 +-=
()iii78.019.10.91aWQCV 23 +-=
AV*
12
WQCV
=
40 hr
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Type of Permeable Pavement Section
A) What type of section of permeable pavement is used?
(Based on the land use and activities, proximity to adjacent
structures and soil characteristics.)
B) What type of wearing course?1
2. Required Storage Volume
A) Effective Imperviousness of Area Tributary to Permeable Pavement, Ia Ia =70.0 %
B) Tributary Area's Imperviousness Ratio (I = Ia / 100)i = 0.700
C) Tributary Watershed Area ATotal = 8,866 sq ft
(including area of permeable pavement system)
D) Area of Permeable Pavement System APPS =2,299 sq ft
(Minimum recommended permeable pavement area = 2299 sq ft)
E) Impervious Tributary Ratio RT =2.0
(Contributing Imperviuos Area / Permeable Pavement Ratio)
F) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 163 cu ft
(WQCV = (0.8 * (0.91 * i3 - 1.19 * i2 + 0.78 * i) / 12) * Area)
G) Is flood control volume being added?
H) Total Volume Needed VTotal =163 cu ft
3. Depth of Reservoir
A) Minimum Depth of Reservoir Dmin =10.0 inches
(Minimum recommended depth is 6 inches)
B) Is the slope of the reservoir/subgrade interface equal to 0%?
2
C) Porosity (Porous Gravel Pavement < 0.3, Others < 0.40) P = 0.30
D) Slope of the Base Course/Subgrade Interface S = 0.002 ft / ft
E) Length Between Lateral Flow Barriers (max = 235.7 ft.) L = 150.0 ft
F) Volume Provided Based on Depth of Base Course V = 414 cu ft
Flat or Stepped: V = P * ((Dmin - 1) / 12) * Area Volume assumes uniform slope & lateral flow barrier spacing
Sloped: V = P * ((Dmin - 6*S*L - 1) / 12) * Area Calculate the volume of each cell individually when this varies.
4. Lateral Flow Barriers
A) Type of Lateral Flow Barriers
B) Number of Permeable Pavement Cells Cells =
5. Perimeter Barrier
A) Is a perimeter barrier provided on all sides of the
pavement system?
(Recommeded for PICP, concrete grid pavement, or for any
no-infiltration section.)
Maxfield Subdivision 2nd Filing
Basin A2
Design Procedure Form: Permeable Pavement Systems (PPS)
A. Boese
Northern Engineering
September 26, 2023
UD-BMP (Version 3.07, March 2018)
Choose One
No Infiltration
Partial Infiltration Section
Full Infiltration Section
Choose One
YES
NO
Choose One
YES- Flat or Stepped Installation
NO- Sloped Installation
Choose One
Concrete Walls
PVC geomembrane installed normal to flow
N/A- Flat installation
Other (Describe):
Choose One
YES
NO
Choose One
PICP
Concrete Grid Pavement
Pervious Concrete
Porous Gravel
UD-BMP_v3.07-Pavers East, PPS 9/26/2023, 8:42 AM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
6. Filter Material and Underdrain System
A) Is the underdrain placed below a 6-inch thick layer of
CDOT Class C filter material?
B) Diameter of Slotted Pipe (slot dimensions per Table PPs-2)
C) Distance from the Lowest Elevation of the Storage Volume y = ft
(i.e. the bottom of the base course to the center of the orifice)
7. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is there a minimum 30 mil thick impermeable PVC geomembrane
liner on the bottom and sides of the basin, extending up to the top
of the base course?
B) CDOT Class B Separator Fabric
8. Outlet 1
(Assumes each cell has similar area, subgrade slope, and length
between lateral barriers (unless subgrade is flat). Calculate cells
individually where this varies.)
A) Depth of WQCV in the Reservoir DWQCV =inches
(Elevation of the Flood Control Outlet)
B) Diameter of Orifice for 12-hour Drain Time DOrifice =inches
(Use a minimum orifice diameter of 3/8-inches)
Notes:
Basin A2
Maxfield Subdivision 2nd Filing
Design Procedure Form: Permeable Pavement Systems (PPS)
A. Boese
Northern Engineering
September 26, 2023
Choose One
YES
NO
Choose One
4-inch
6-inch
Choose One
Choose One
YES
NO
Placed above the liner
Placed above and below the liner
N/A
UD-BMP_v3.07-Pavers East, PPS 9/26/2023, 8:42 AM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Type of Permeable Pavement Section
A) What type of section of permeable pavement is used?
(Based on the land use and activities, proximity to adjacent
structures and soil characteristics.)
B) What type of wearing course?1
2. Required Storage Volume
A) Effective Imperviousness of Area Tributary to Permeable Pavement, Ia Ia =39.0 %
B) Tributary Area's Imperviousness Ratio (I = Ia / 100)i = 0.390
C) Tributary Watershed Area ATotal = 9,267 sq ft
(including area of permeable pavement system)
D) Area of Permeable Pavement System APPS =1,545 sq ft
(Minimum recommended permeable pavement area = 1512 sq ft)
E) Impervious Tributary Ratio RT =1.9
(Contributing Imperviuos Area / Permeable Pavement Ratio)
F) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 109 cu ft
(WQCV = (0.8 * (0.91 * i3 - 1.19 * i2 + 0.78 * i) / 12) * Area)
G) Is flood control volume being added?
H) Total Volume Needed VTotal =109 cu ft
3. Depth of Reservoir
A) Minimum Depth of Reservoir Dmin =10.0 inches
(Minimum recommended depth is 6 inches)
B) Is the slope of the reservoir/subgrade interface equal to 0%?
2
C) Porosity (Porous Gravel Pavement < 0.3, Others < 0.40) P = 0.30
D) Slope of the Base Course/Subgrade Interface S = 0.002 ft / ft
E) Length Between Lateral Flow Barriers (max = 236.17 ft.) L = 150.0 ft
F) Volume Provided Based on Depth of Base Course V = 278 cu ft
Flat or Stepped: V = P * ((Dmin - 1) / 12) * Area Volume assumes uniform slope & lateral flow barrier spacing
Sloped: V = P * ((Dmin - 6*S*L - 1) / 12) * Area Calculate the volume of each cell individually when this varies.
4. Lateral Flow Barriers
A) Type of Lateral Flow Barriers
B) Number of Permeable Pavement Cells Cells =
5. Perimeter Barrier
A) Is a perimeter barrier provided on all sides of the
pavement system?
(Recommeded for PICP, concrete grid pavement, or for any
no-infiltration section.)
Maxfield Subdivision 2nd Filing
Basin A3
Design Procedure Form: Permeable Pavement Systems (PPS)
A. Boese
Northern Engineering
September 26, 2023
UD-BMP (Version 3.07, March 2018)
Choose One
No Infiltration
Partial Infiltration Section
Full Infiltration Section
Choose One
YES
NO
Choose One
YES- Flat or Stepped Installation
NO- Sloped Installation
Choose One
Concrete Walls
PVC geomembrane installed normal to flow
N/A- Flat installation
Other (Describe):
Choose One
YES
NO
Choose One
PICP
Concrete Grid Pavement
Pervious Concrete
Porous Gravel
UD-BMP_v3.07-Pavers West, PPS 9/26/2023, 8:45 AM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
6. Filter Material and Underdrain System
A) Is the underdrain placed below a 6-inch thick layer of
CDOT Class C filter material?
B) Diameter of Slotted Pipe (slot dimensions per Table PPs-2)
C) Distance from the Lowest Elevation of the Storage Volume y = ft
(i.e. the bottom of the base course to the center of the orifice)
7. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is there a minimum 30 mil thick impermeable PVC geomembrane
liner on the bottom and sides of the basin, extending up to the top
of the base course?
B) CDOT Class B Separator Fabric
8. Outlet 1
(Assumes each cell has similar area, subgrade slope, and length
between lateral barriers (unless subgrade is flat). Calculate cells
individually where this varies.)
A) Depth of WQCV in the Reservoir DWQCV =inches
(Elevation of the Flood Control Outlet)
B) Diameter of Orifice for 12-hour Drain Time DOrifice =inches
(Use a minimum orifice diameter of 3/8-inches)
Notes:
Maxfield Subdivision 2nd Filing
Design Procedure Form: Permeable Pavement Systems (PPS)
A. Boese
Northern Engineering
September 26, 2023
Basin A3
Choose One
YES
NO
Choose One
4-inch
6-inch
Choose One
Choose One
YES
NO
Placed above the liner
Placed above and below the liner
N/A
UD-BMP_v3.07-Pavers West, PPS 9/26/2023, 8:45 AM
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: MAXFIELD SUBDIVISON 2nd FILING
FORT COLLINS | GREELEY APPENDIX
APPENDIX D
EROSION CONTROL REPORT
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: MAXFIELD SUBDIVISON 2nd FILING
FORT COLLINS | GREELEY EROSION CONTROL REPORT
EROSION CONTROL REPORT
A comprehensive Erosion and Sediment Control Plan (along with associated details) has been included with the
final construction drawings. It should be noted; however, any such Erosion and Sediment Control Plan serves
only as a general guide to the Contractor. Staging and/or phasing of the BMPs depicted, and additional or
different BMPs from those included may be necessary during construction, or as required by the authorities
having jurisdiction.
It shall be the responsibility of the Contractor to ensure er osion control measures are properly maintained and
followed. The Erosion and Sediment Control Plan is intended to be a living document, constantly adapting to
site conditions and needs. The Contractor shall update the location of BMPs as they are installed, removed, or
modified in conjunction with construction activities. It is imperative to appropriately reflect the current site
conditions at all times.
The Erosion and Sediment Control Plan shall address both temporary measures to be implemented during
construction, as well as permanent erosion control protection. Best Management Practices from the Volume 3,
Chapter 7 – Construction BMPs will be utilized. Measures may include, but are not limited to, silt fencing and/or
wattles along the disturbed perimeter, gutter protection in the adjacent roadways, and inlet protection at
existing and proposed storm inlets. Vehicle tracking control pads, spill containment and clean-up procedures,
designated concrete washout areas, dumpsters, and job site restrooms shall also be provided by the Contractor.
Grading and Erosion Control Notes can be found on Sheet CS2 of the Utility Plans. The Final Utility Plans will also
contain a full-size Erosion Control Plan as well as a separate sheet dedicated to Eros ion Control Details. In
addition to this report and the referenced plan sheets, the Contractor shall be aware of, and adhere to, the
applicable requirements outlined in any existing Development Agreement(s) of record, as well as the
Development Agreement, to be recorded prior to issuance of the Development Construction Permit. Also, the
Site Contractor for this project may be required to secure a Stormwater Construction General Permit from the
Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater
Program, before commencing any earth disturbing activities. Prior to securing said permit, the Site Contractor
shall develop a comprehensive Storm Water Management Plan (SWMP) pursuant to CDPHE requirements and
guidelines. The SWMP will further describe and document the ongoing activities, inspections, and maintenance
of construction BMPs.
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: MAXFIELD SUBDIVISON 2nd FILING
FORT COLLINS | GREELEY APPENDIX
APPENDIX E
USDA 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
Maxfield Subdivision Lot 2 - 1509
Shields
Natural
Resources
Conservation
Service
July 7, 2023
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
Soil Information for All Uses...............................................................................15
Soil Properties and Qualities..............................................................................15
Soil Erosion Factors........................................................................................15
Wind Erodibility Index..................................................................................15
Wind Erodibility Group.................................................................................18
Soil Qualities and Features.............................................................................21
Hydrologic Soil Group.................................................................................21
References............................................................................................................26
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
Custom Soil Resource Report
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.
8
9
Custom Soil Resource Report
Soil Map
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Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 20 40 80 120
Feet
0 5 10 20 30
Meters
Map Scale: 1:507 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 17, Sep 7, 2022
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jul 2, 2021—Aug 25,
2021
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
10
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
4 Altvan-Satanta loams, 3 to 9
percent slopes
0.7 100.0%
Totals for Area of Interest 0.7 100.0%
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
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.
Custom Soil Resource Report
11
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.
Custom Soil Resource Report
12
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
H3 - 16 to 31 inches: loam
H4 - 31 to 60 inches: gravelly sand
Properties and qualities
Slope:6 to 9 percent
Depth to restrictive feature:More than 80 inches
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 content:10 percent
Available water supply, 0 to 60 inches: Low (about 5.5 inches)
Interpretive groups
Land capability classification (irrigated): 4e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: B
Ecological site: R067BY008CO - Loamy Slopes
Hydric soil rating: No
Custom Soil Resource Report
13
Description of Satanta
Setting
Landform:Structural benches, terraces
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
H3 - 14 to 60 inches: loam
Properties and qualities
Slope:3 to 6 percent
Depth to restrictive feature:More than 80 inches
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 content:10 percent
Available water supply, 0 to 60 inches: High (about 10.1 inches)
Interpretive groups
Land capability classification (irrigated): 2e
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: B
Ecological site: R067BY002CO - Loamy Plains
Hydric soil rating: No
Minor Components
Nunn
Percent of map unit:6 percent
Ecological site:R067BY002CO - Loamy Plains
Hydric soil rating: No
Larimer
Percent of map unit:4 percent
Ecological site:R067BY002CO - Loamy Plains
Hydric soil rating: No
Custom Soil Resource Report
14
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.
15
16
Custom Soil Resource Report
Map—Wind Erodibility Index
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Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 20 40 80 120
Feet
0 5 10 20 30
Meters
Map Scale: 1:507 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 17, Sep 7, 2022
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jul 2, 2021—Aug 25,
2021
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
17
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 0.7 100.0%
Totals for Area of Interest 0.7 100.0%
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
Wind Erodibility Group
A wind erodibility group (WEG) consists of soils that have similar properties
affecting their susceptibility to wind erosion in cultivated areas. The soils assigned
to group 1 are the most susceptible to wind erosion, and those assigned to group 8
are the least susceptible.
Custom Soil Resource Report
18
19
Custom Soil Resource Report
Map—Wind Erodibility Group
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40° 34' 6'' N
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4
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Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 20 40 80 120
Feet
0 5 10 20 30
Meters
Map Scale: 1:507 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
1
2
3
4
4L
5
6
7
8
Not rated or not available
Soil Rating Lines
1
2
3
4
4L
5
6
7
8
Not rated or not available
Soil Rating Points
1
2
3
4
4L
5
6
7
8
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 17, Sep 7, 2022
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jul 2, 2021—Aug 25,
2021
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
20
Table—Wind Erodibility Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
4 Altvan-Satanta loams, 3
to 9 percent slopes
5 0.7 100.0%
Totals for Area of Interest 0.7 100.0%
Rating Options—Wind Erodibility Group
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Lower
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.
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
Custom Soil Resource Report
21
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
22
23
Custom Soil Resource Report
Map—Hydrologic Soil Group
44
9
0
7
8
0
44
9
0
7
9
0
44
9
0
8
0
0
44
9
0
8
1
0
44
9
0
8
2
0
44
9
0
8
3
0
44
9
0
8
4
0
44
9
0
8
5
0
44
9
0
7
8
0
44
9
0
7
9
0
44
9
0
8
0
0
44
9
0
8
1
0
44
9
0
8
2
0
44
9
0
8
3
0
44
9
0
8
4
0
44
9
0
8
5
0
491760 491770 491780 491790 491800 491810 491820 491830 491840 491850 491860 491870
491760 491770 491780 491790 491800 491810 491820 491830 491840 491850 491860
40° 34' 6'' N
10
5
°
5
'
5
0
'
'
W
40° 34' 6'' N
10
5
°
5
'
4
5
'
'
W
40° 34' 3'' N
10
5
°
5
'
5
0
'
'
W
40° 34' 3'' N
10
5
°
5
'
4
5
'
'
W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 20 40 80 120
Feet
0 5 10 20 30
Meters
Map Scale: 1:507 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 17, Sep 7, 2022
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jul 2, 2021—Aug 25,
2021
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
24
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 0.7 100.0%
Totals for Area of Interest 0.7 100.0%
Rating Options—Hydrologic Soil Group
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Custom Soil Resource Report
25
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
26
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
27
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: MAXFIELD SUBDIVISON 2nd FILING
FORT COLLINS | GREELEY APPENDIX
MAP PACKET
DR1 – HISTORIC DRAINAGE EXHIBIT
DR2 – DEVELOPED DRAINAGE EXHIBIT
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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.
Feet02020
20
40 60
EXISTING CONTOUR
PROPERTY BOUNDARY
A
DESIGN POINT
FLOW ARROW
DRAINAGE BASIN LABEL
DRAINAGE BASIN BOUNDARY
NOTES:
1.REFER TO THE PRELIMINARY DRAINAGE REPORT, DATED SEPTEMBER 27, 2023 FOR
ADDITIONAL INFORMATION.
A
LEGEND:
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
HISTORIC DRAINAGE SUMMARY
Design
Point Basin ID
Total
Area
(acres)
C2 C100 2-Yr Tc
(min)
100-Yr Tc
(min)
Q2
(cfs)
Q100
(cfs)
HA1 ha1 0.241 0.50 0.62 5.80 5.80 0.33 1.49
HA2 ha2 0.428 0.23 0.28 10.09 10.09 0.21 0.98
total Total 0.669 0.32 0.41 6.98 6.98 0.56 2.53
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PROPOSED 6" PVC UNDERDRAIN @0.2%
PAVER 1
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PAVER 2
PROPOSED PERMEABLE
INTERLOCKING PAVERS
PROPOSED SIDEWALK CHASE
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CONCRETE PAN
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LIMITS OF
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PROPOSED UNDERDRAIN OUTFALL
WITH UPTURNED ELBOW
PROPOSED 2' U-CHANNEL
100-YR WSEL100-YR WSEL
Sheet
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12
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.
Feet02020
20
40 60
PROPOSED CONTOUR
PROPOSED STORM SEWER
PROPOSED SWALE
EXISTING CONTOUR
PROPOSED CURB & GUTTER
PROPERTY BOUNDARY
PROPOSED INLET
A
DESIGN POINT
FLOW ARROW
DRAINAGE BASIN LABEL
DRAINAGE BASIN BOUNDARY
PROPOSED SWALE SECTION
11
NOTES:
1.REFER TO THE PRELIMINARY DRAINAGE REPORT, DATED SEPTEMBER 27, 2023 FOR
ADDITIONAL INFORMATION.
A
LEGEND:
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
DEVELOPED DRAINAGE SUMMARY
Design
Point Basin ID
Total
Area
(acres)
C2 C100 2-Yr Tc
(min)
100-Yr Tc
(min)
Q2
(cfs)
Q100
(cfs)
DA1 da1 0.253 0.40 0.50 6.81 6.81 0.26 1.21
DA2 da2 0.204 0.74 0.92 5.00 5.00 0.43 1.86
DA3 da3 0.213 0.47 0.58 7.41 7.41 0.25 1.15
total Total 0.669 0.52 0.65 7.21 7.21 0.88 4.21
DETENTION POND SUMMARY
Pond ID Tributary Area
(ac)
Weighted
Percent
Imperviousness
(%)
Extended
Detention
WQCV (ac-ft)
LID WQCV
(ac-ft)
100-Yr
Detention
Vol. (ac-ft)
Total Pond
Volume (ac-ft)
100-Yr
Detention
WSEL (ft)
Final
Release
Rate (cfs)
Pond 1 0.25 31 0.004 N/A 0.064 0.068 5037.40 0.60
Paver 1 0.20 70 N/A 0.009 N/A N/A N/A N/A
Paver 2 0.21 39 N/A 0.013 N/A N/A N/A N/A