HomeMy WebLinkAboutTIMBER LARK SINGLE-FAMILY DEVELOPMENT - PDP210015 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT PRELIMINARY DRAINAGE REPORT
AADT LAND HOLDINGS, LLC
TIMBER LARK RESIDENTIAL
JULY 7, 2021
NORTHERNENGINEERING.COM
970.221.4158
FORT COLLINS
GREELEY
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FORT COLLINS | GREELEY COVER LETTER
July 7, 2021
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
RE: PRELIMINARY DRAINAGE REPORT FOR
TIMBER LARK RESIDENTIAL
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage Report for your review. This report
accompanies the combined Preliminary Plan submittal for the proposed Timber Lark Residential project.
This report has been prepared in accordance with the City of Fort Collins Stormwater Criteria Manual (FCSCM)
and serves to document the stormwater impacts associated with the proposed Timber Lark Residential project.
We understand that review by the City of Fort Collins is to assure general compliance with standardized criteria
contained in the manual. If you should have any questions as you review this report, please feel free to contact
us.
Sincerely,
NORTHERN ENGINEERING SERVICES, INC.
FREDERICK S. WEGERT, PE
Project Engineer
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FORT COLLINS | GREELEY TABLE OF CONTENTS
TABLE OF CONTENTS
I. I. GENERAL LOCATION AND DESCRIPTION .......................................................... 1
II. II. DRAINAGE BASINS AND SUB-BASINS ............................................................... 3
III. III. DRAINAGE DESIGN CRITERIA .......................................................................... 4
IV. IV. DRAINAGE FACILITY DESIGN ........................................................................... 7
V. V. CONCLUSIONS ............................................................................................ 11
VI. VI. REFERENCES .............................................................................................. 12
TABLES AND FIGURES
FIGURE 1: VICINITY MAP .........................................................................................................1
FIGURE 2: AERIAL PHOTOGRAPH ...........................................................................................2
FIGURE 3: REGULATORY FLOODPLAINS ................................................................................3
FIGURE 4: LOOKING SOUTHWEST ACROSS PROJECT SITE ..................................................4
TABLE 1: PARAGON ESTATES NORTH & WEST CHANNELS 100-YEAR FLOWRATE DEPTH . 11
APPENDICES
APPENDIX A – HYDROLOGIC COMPUTATIONS
APPENDIX B – HYDRAULIC COMPUTATIONS
APPENDIX C – DETENTION POND & WATER QUALITY COMPUTATIONS
APPENDIX D – EROSION CONTROL REPORT
APPENDIX E – USDA SOILS REPORT
APPENDIX F – EXCERPTS FROM LINDEN PARK DRAINGE REPORT
APPENDIX G – EXCERPTS FROM PARAGON ESTATES DRAINGE REPORT
MAP POCKET
DR1 – DRAINAGE EXHIBIT
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I. GENERAL LOCATION AND DESCRIPTION
A. LOCATION
Vicinity Map
The Timber Lark Residential project is located in the southeast quarter of Section 7, Township 6
North, Range 68 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 Linden Park Subdivision, to the east
by Timberline Road, to the south by agricultural land, and to the west by Great Western Railway.
The surrounding properties are single-family residential to the north, east, and west and
agriculture to the south. The site abuts against Fort Collins City Limits on the north and west
boundaries and along the Timberline Road right-of-way.
The nearest existing major streets to the project are South Timberline Road on the east side of
the project and Trilby Road towards the south.
A 30” storm sewer conveys stormwater from Linden Park south to Fossil Creek across the
property. Fossil Creek is located towards the southwest of the project south of Trilby Road and
west of the Great Western Railway.
B. DESCRIPTION OF PROPERTY
The Timber Lark Residential site comprises of ± 35.16 acres.
Project
Location
Figure 1: Vicinity Map
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The site is currently used as agriculture.
A subsurface exploration report was completed by Earth Environmental Consultants, Inc. on
June 2, 2020 (EEC Project No. 1202034). At the time this report was written, the site was
undeveloped with established vegetation. According to Earth Environmental Consultants, the
site consist of sandy lean clay soil with bedrock at a depth between 20 to 35 feet.
According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey website:
(http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx),
the site consists primarily of Fort Collins loam and Nunn loam (Hydrologic Soil Group C) and Kim
loam (Hydrologic Soil Group B). The calculations assume a Hydrologic Soil Group of C.
Hydrologic Soil Group C has a slow rate of water absorption and infiltration.
The proposed development will consist of single-family and multi-family residential. Other
proposed improvements include asphalt drive aisles, sidewalks, landscaping, and a
neighborhood park.
The site is currently zoned as Rural Residential (RR-2) in Larimer County. Subdivisions to the are
zoned Low-Density Mixed -Use District (LMN) to the north and east of the project and Low-Density
Residential District (R-L) to the west. The proposed uses for the project are consistent with Low-
Density Mixed Use District (LMN).
Figure 2: Aerial Photograph
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Two irrigation laterals, providing water to agricultural land south of the project, cross the site.
Both irrigation laterals will be relocated into pipes and continue to provide irrigation to the
southern neighboring properties.
A 30” storm sewer, from the Linden Park detention facilities, bisects the property in half. The 30”
storm sewer (Linden Park Outfall) was sized to provide an additional capacity of 40 cfs per the
Final Drainage Report for Linden Park P.D.P., and this project proposes to utilize the additional
capacity. The Linden Park Outfall discharges into a drainage ditch on the south side of Trilby
Road, and this drainage ditch conveys stormwater around the north and west side of Paragon
Estates ultimately discharging into Fossil Creek.
C. FLOODPLAIN
The subject property is not located in a FEMA or City of Fort Collins regulatory floodplain.
II. DRAINAGE BASINS AND SUB-BASINS
A. MAJOR BASIN DESCRIPTION
Timber Lark Residential is within the City of Fort Collins Fossil Creek major drainage basin.
Specifically, the project site is situated in the eastern third of this major drainage basin towards
Fossil Creek Wetlands Natural Area. The Fossil Creek drainage basin extends along the south end of
Fort Collins, from the foothills across Interstate 25 past County Road 5. It encompasses 32 square
miles in the city of Fort Collins and Larimer County. Historically, the basin consisted of agricultural
land, but the basin has experienced significant development in the recent past. The Fossil Creek
drainage basin generally drains from west to east. Runoff from the major drainage basin drains to
Fossil Creek Reservoir.
B. SUB-BASIN DESCRIPTION
The outfall for the project site is Fossil Creek via the existing 30” storm sewer and the Paragon
Estates Channel along the south side of Trilby Road.
Figure 3: Regulatory Floodplains
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The existing site can be defined with four (4) sub-basins.
Existing runoff follows the natural topography from the northwest to the southeast across gentle
grades (e.g., 1.00% to 3.00%) with a hill (e.g., 2.00% to 6.00%) in the northwest corner. The site
generally sheet flows from a high point elevation of ±4958 in the northwest corner to the
southeast corner of the site. An existing irrigation lateral flows diagonally north to south in the
eastern third of the site.
The site does not receive notable surface runoff from adjacent properties. However, there is a
30” storm sewer from Linden Park Subdivision that bisects the property. According to the Final
Drainage Report for Linden Park P.D.P, the storm sewer was sized to convey the historic 100-year
release from Linden Park plus an additional 40 cfs for additional development south of Linden
Park. The 30” storm sewer conveys stormwater south towards the Paragon Estates Channel on
the south side of Trilby Road, and the Paragon Estates Channel discharges into Fossil Creek.
III. DRAINAGE DESIGN CRITERIA
A. OPTIONAL REVISIONS
There are no optional provisions outside of the Fort Collins Stormwater Manual (FCSM) and the Mile
High Flood District (MHFD).
B. STORMWATER MANAGEMENT STRATEGY
The overall stormwater management strategy employed with Timber Lark Residential 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. The first consideration taken in trying to reduce the
stormwater impacts of this development is the site selection itself. By choosing an already
developed site with public storm sewer currently in place, the burden is significantly less than
developing a vacant parcel absent of any infrastructure.
Figure 4: Looking Southwest Across Project Site
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Timber Lark Residential 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 a bioretention pond. These LID practices reduce the overall
amount of impervious area, while at the same time Minimizing Directly Connected Imp ervious 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 in the rain gardens, underground chambers,
and extended detention pond.
Step 3 – Stabilize Drainageways. As stated in Section II.A, above, the site discharges into Fossil
Creek, however no changes to the channel are proposed with this project. While this step may not
seem applicable to Timber Lark Residential, the proposed project indirectly helps achieve stabilized
drainageways, nonetheless. Once again, site selection has a positive effect on stream stabilization.
By developing a with existing stormwater infrastructure, combined with LID and MDCIA strategies,
the likelihood of bed and bank erosion is reduced. Furthermore, this project will pay one-time
stormwater development fees, as well as ongoing monthly stormwater utility fees, both of which
help achieve Citywide drainageway stability.
Step 4 – Implement Site Specific and Other Source Control BMPs. This step typically applies to
industrial and commercial developments.
C. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS
The subject property is not part of any Overall Development Plan (ODP) drainage study or similar
“development/project” drainage master plan. However, stormwater from Timber Lark
Residential will discharge into conveyance structures established as part of the Linden Park and
Paragon Estates subdivisions.
The site plan is constrained to the north by the Linden Park Subdivision, to the west by the Great
Western Railway, and to the east by Timberline Road. An existing agricultural use borders the
project on the south.
D. 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 Timber Lark
Residential 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 3.2-1, 3.2-2, and 3.2-3 of the FCSCM.
The Rational Method will be used to estimate peak developed stormwater runoff from drainage
basins within the developed site for the 2-year, 10-year, and 100-year design storms. Peak runoff
discharges determined using this methodology have been used to check the street capacities,
inlets, swales, and storm drain lines. Detention was calculated utilizing EPA SWMM.
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Two separate design storms have been utilized to address distinct drainage scenarios. The first
event analyzed is the “Minor” or “Initial” Storm with a 2-year recurrence interval. The second
event considered is the “Major Storm” with a 100-year recurrence interval.
E. HYDRAULIC CRITERIA
The hydraulic analyses of street capacities, inlets, storm drain lines, culverts, and swales will be
per the FCSM criteria and provided during Final Plan. The following computer programs and
methods will be utilized:
• The storm drain lines will be analyzed using the Hydraflow Express Extension for AutoCAD
Civil 3D.
• The inlets will be analyzed using the Urban Drainage Inlet and proprietary area inlet
spreadsheets.
• Swales and street capacities will be analyzed using the Urban Drainage Channels
spreadsheets.
• Sidewalk chases will be analyzed using the Hydraflow Express Extension for AutoCAD Civil
3D.
F. FLOODPLAIN REGULATIONS COMPLIANCE
As previously mentioned, this project is not subject to any floodplain regulations.
G. MODIFICATIONS OF CRITERIA
No formal modifications are requested at this time. However, due to the additional design
capacity of the existing 30” storm sewer, the project proposes to release at the 100-year
historic release rate, the capacity of the 30” storm sewer, or the capacity of the Paragon
Estates Channel, whichever is more conservative.
H. 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 with bioretention ponds (aka –
rain gardens) and extended detention within the detention pond. The rain gardens are considered a
LID treatment method. Due to the physical constraints associated with a project of this nature and
the prohibition of providing water quality facilities within the public right-of-way, there are some
small, narrow areas around the perimeter of the project that cannot be captured. The uncaptured
areas tend to be narrow strips of grading behind rear lot lines that tie the site back into established
offsite grades along property lines. Every effort is taken to direct as much of these narrow
landscaping strips into the proposed drainage infrastructure, but there will be some small segments
of uncaptured parcels.
While these small areas will not receive formal water quality treatment, most areas will still see
some treatment as runoff is directed across through the landscaped areas before reaching the
property line.
I. CONFORMANCE WITH LOW IMPACT DEVELOPMENT (LID)
The project site will conform with the requirement to treat a minimum of 75% of the project site
using a LID technique. LID treatment will be provided by a rain garden, a bioswale, and
underground chambers. Please see Appendix C for LID design information, table, and exhibit(s). As
shown in the LID table provided in the appendix, 75% of the proposed site impervious area will
receive LID treatment, which exceeds the minimum required.
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IV. DRAINAGE FACILITY DESIGN
A. GENERAL CONCEPT
The main objective of Timber Lark Residential drainage design is to maintain existing drainage
patterns, while not adversely impacting adjacent properties.
Off-site drainage from Linden Park passes through an existing 30” storm sewer bisecting the
property (Linden Park Outfall).
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 fourteen (14) drainage sub-basins. The
drainage patterns anticipated for the basins are further described below.
Basin A1
Basin A1 is approximately 2.32 acres and consists of the detention pond and surrounding
landscaping areas in the southeast corner of the site. The basin will generally maintain
historic drainage patterns. Runoff from this basin will sheet flow into the onsite detention
pond. The detention pond will provide both detention and water quality in the form of
extended (40-hour) detention for the entire project. The detention pond will discharge
into the Linden Park Outfall.
Basin A2a
Basin A2 is approximately 1.19 acres and consists of seven lots immediately west of the
detention pond, the south side of Street B, and the southeastern quarter of Street I. The
basin will generally maintain historic drainage patterns from west to east. Runoff from
this basin will sheet flow off the lots into the Street B curb and gutter. The curb and gutter
will convey the stormwater east towards a storm inlet in Street B and ultimately into the
detention pond in Basin A1. Detention and water quality for Basin A2 will be provided by
the detention pond.
Basin A2b & A3
Basins A2b and A3 consists of the lots along the south side of Street B and the south side
of Street B. Basin A2b is approximately 0.69 acres and Basin A3 is approximately 2.19
acres. The basin will generally maintain historic drainage patterns from west to east.
Runoff from this basin will sheet flow off the lots into the Street B curb and gutter. The
curb and gutter will convey the stormwater east towards a storm inlet in Street B . A storm
sewer will then convey stormwater to underground chambers in the south half of the park
for water quality treatment, and the 100-year storm will continue east to the detention
pond in Basin A1. Detention and water quality for Basin A3 will be provided by the
detention pond and underground chambers.
Basin A4
Basin A4 is approximately 2.77 acres and consists of the lots along Red Willow Drive and
Alley L, the west half of Street I, and the north half of Street B. The basin will generally
maintain historic drainage patterns from northwest to southeast. Runoff from this basin
will sheet flow off the lots into either Red Willow Drive, Street I or Alley L curb and gutter.
The curb and gutter and the alleys will convey the stormwater south towards a storm inlet
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in Street B and ultimately into the detention pond in Basin A1. Detention and water
quality for Basin A4 will be provided by the detention pond.
Basin A5
Basin A5 is approximately 4.58 acres and consists of the lots along Street G and Alley K, a
park, Street G, Alley K, and the north half of Street B. The basin will generally maintain
historic drainage patterns from northwest to southeast. Runoff from this basin will sheet
flow off the lots into either the Street G, Street B, or Alley K curb and gutter. The curb and
gutter will convey the stormwater south towards a storm inlet in Street B. A storm sewer
will then convey stormwater to underground chambers in the south half of the park for
water quality treatment, and the 100-year storm will continue east to the detention pond
in Basin A1. Detention and water quality for Basin A 5 will be provided by the detention
pond and underground chambers.
Basin A6
Basin A6 is approximately 6.33 acres and consists of the lots along Weeping Willow Drive
and Street E, Street E, Weeping Willow Drive south of Street A, and the north half of Street
B. The basin will generally maintain historic drainage patterns from northwest to
southeast. Runoff from this basin will sheet flow off the lots into the Street E or Weeping
Willow Drive curb and gutter. The curb and gutter will convey the stormwater south
towards a storm inlet in Street B. A storm sewer will then convey stormwater to
underground chambers in the south half of the park for water quality treatment, and the
100-year storm will continue east to the detention pond in Basin A1. Detention and water
quality for Basin A6 will be provided by the detention pond and underground chambers.
Basin A7
Basin A7 is approximately 3.59 acres and consists of the lots along Golden Willow Drive.
The basin will generally maintain historic drainage patterns from north to the south.
Runoff from this basin will sheet flow off the lots into the Golden Willow Drive curb and
gutter. The curb and gutter will convey the stormwater south towards a storm inlet in
Street B. A storm sewer will then convey stormwater to underground chambers in the
south half of the park for water quality treatment, and the 100-year storm will continue
east to the detention pond in Basin A1. Detention and water quality for Basin A7 will be
provided by the detention pond and underground chambers.
Basin A8
Basin A8 is approximately 0.46 acres and consists of the south half of Street A. The basin
will generally maintain historic drainage patterns from west to east. Runoff from this
basin will collect within the curb and gutter, and the curb and gutter will convey the
stormwater east towards a storm inlet in Street A. A storm sewer will then convey
stormwater to underground chambers in the south half of the park for water quality
treatment, and the 100-year storm will continue east to the detention pond in Basin A1.
Detention and water quality for Basin A8 will be provided by the detention pond and
underground chambers.
Basin A9
Basin A9 is approximately 3.84 acres and consists of the lots along the Street A and the
north half of Street A. The basin will generally maintain historic drainage patterns from
west to east. Runoff from this basin will sheet flow off the lots into the Street A curb and
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gutter. The curb and gutter will convey the stormwater towards a storm inlet in the
middle of Street A. A storm sewer will then convey stormwater to underground chambers
in the south half of the park for water quality treatment, and the 100-year storm will
continue east to the detention pond in Basin A1. Detention and water quality for Basin A9
will be provided by the detention pond and underground chambers.
Basin A10
Basin A10 is approximately 0.94 acres and consists of the lots along Alleys O and P. The
basin will generally maintain historic drainage patterns from north to south. Runoff from
this basin will sheet flow off the lots into Alleys O and P, and the alleys will convey water to
a storm inlet south of the basin. A storm sewer will then convey stormwater to Rain
Garden 1 and the detention pond in Basin A1. Detention and water quality for Basin A10
will be provided by the detention pond and the rain garden.
Basin A11
Basin A11 is approximately 0.45 acres and consists of the south half of Street C. The basin
will generally maintain historic drainage patterns from west to east. Runoff from this
basin will collect within the curb and gutter, and the curb and gutter will convey
stormwater east towards an inlet at the east end of Street C. A drainage channel will then
convey stormwater to detention pond in Basin A1. Detention and water quality for Basin
A11 will be provided by the detention pond.
Basin A12
Basin A12 is approximately 2.25 acres and consists of the lots along Alleys M and N, Street
G, Alley M, Alley N, the south half of Street A, the north half of Street C, and the northeast
quarter of Street I. The basin will generally maintain historic drainage patterns from
northwest to southeast. Runoff from this basin will sheet flow off the lots into either the
Street I curb and gutter or into Alleys M and N. The curb and gutter and the alleys will
convey the stormwater south towards a storm inlet in Street C. A drainage channel will
then convey stormwater to detention pond in Basin A1. Detention and water quality for
Basin A12 will be provided by the detention pond.
Basin A13
Basin A13 is approximately 1.28 acres and consists of open space south of Street A and
west of Timberline Drive. The basin will generally drain east to west via a bioswale (Rain
Garden 2) to the detention pond in Basin A1. Detention and water quality for Basin A13
will be provided by the detention pond and the bioswale.
Basin A14
Basin A14 is approximately 0.34 acres and consists of the south half of Street A. The basin
will generally maintain historic drainage patterns from west to east. Runoff from this
basin will collect within the curb and gutter, and the curb and gutter will convey
stormwater towards an inlet in Street A. A bioswale (Rain Garden 2) will then convey
stormwater to detention pond in Basin A1. Detention and water quality for Basin A14 will
be provided by the detention pond and the bioswale.
Basin A15
Basin A15 is approximately 1.95 acres and consists of the lots along the north half of Street
A and the north half of Street A. The basin will generally maintain historic drainage
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patterns from west to east. Runoff from this basin will collect within the curb and gutter,
and the curb and gutter will convey stormwater towards an inlet in Street A. A bioswale
(Rain Garden 2) will then convey stormwater to detention pond in Basin A1. Detention
and water quality for Basin A15 will be provided by the detention pond and the bioswale.
A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of this
report.
B. SPECIFIC DETAILS
The project proposed to release at the 100-year historic release rate, the capacity of the Linden
Park Outfall, or the capacity of the Paragon Estates North Channel, whichever is more
conservative. The detention pond in the southeast corner will provide 2.19 acre-feet of detention
and 0.19 acre-feet of water quality treatment for a total required volume of 2.38 acre-feet. The
pond is designed to provide 2.50 acre-feet.
• The historic 100-year release rate for Timber Lark Residential was calculated to 45.2 cfs.
However, due to limitations within the Paragon Estates Channel, further described below,
the release rate from the detention pond is 40 cfs.
• According to the Final Drainage Report for Linden Park P.D.P., the existing 30” storm sewer
(Linden Park Outfall) was designed to convey 26 cfs from Linden Park and an excess
capacity of 40 cfs for a total of 66 cfs.. An hydraulic analysis of this storm sewer yield a
total capacity of 45.2 cfs with the pipe surcharged to a depth of 7.37 feet at Manhole EX-4.
The total elevation from invert to rim is 11.14 feet. A storm sewer analysis of the Linden
Park Outfall is included in Appendix B. However, the Paragon Estates Channel, further
described below, limits the release rate to 40 cfs.
• According to the Final Drainage Report for Paragon Estates, the Paragon Estates North
Channel was designed to convey 64.88 cfs from Basin O1. Basin O1 (see Appendix G)
includes Linden Park, Timber Lark Residential, and agriculture land northwest of the
intersection of Trilby Road and Timberline Road (depicated as Basin OS1 in the drainage
exhibit). However, the Final Drainage Report for Linden Park P.D.P. assumes a total flow of
66 cfs for the Linden Park Outfall. Assuming 66 cfs from the Linden Park Outfall and 25.4
cfs from Basin OS1, we calculated a 100-year flowrate of 91.4 cfs draining into the Paragon
Estates North Channel. This is greater than the designed flowrate per the Final Drainage
Report for Paragon Estates.
Therefore, Northern Engineering surveyed the Paragon Estates North and West Channels
between Trilby Road and Fossil Creek. We then modeled both channels assuming 91.4 cfs
with Hydraflow Express Extension for AutoCAD Civil 3D. Table 1 below is the a summary of
the results at multiple cross-sections along both the Paragon Estates North and West
Channels. Assuming a release rate of from Timber Lark Residential detention pond results
in a freeboard of 3” to 11.4” within the Paragon Estates North and West Channels. The
Paragon Estates North Channel, Sections 4 and 5 in Table 1, will restrict the release rate
from Timber Lark Residential.
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Cross-
Section Description 100-Year
Flowrate (cfs)
Channel
Depth (ft)
Flow
Depth (ft)
Freeboard
(ft)
Section 1
170' downstream from Paragon Estates Channel B
confluence 169.0 3.46 2.97 0.49
Section 2
Immediately upstream of Paragon Estates Channel
B confluence 127.9 2.61 2.10 0.51
Section 3
80' downstream from 90-degree bend in Paragon
Estates North and West Channels. 127.9 2.76 1.81 0.95
Section 4
292' upstream from 90-degree bend in Paragon
Estates North and West Channels at a low point in
the south embankment. 91.4 1.59 1.23 0.36
Section 5
Immediately downstream of the Linden Park
Outfall. 91.4 1.38 1.11 0.27
Table 1: Paragon Estates North & West Channels 100-Year Flowrate Depth
Water quality and LID treatment will be provided by a rain garden, a bioswale, underground
chambers, and extendend detention within the detention pond.
Final design details, detailed hydraulic calculations, and construction documentation, will be
provided to the City of Fort Collins for review prior to Final Development Plan approval.
V. CONCLUSIONS
A. COMPLIANCE WITH STANDARDS
The proposed drainage design for the Timber Lark Residential complies with the City of Fort
Collins Stormwater Criteria Manual.
The drainage desing proposed with this project will effectively limit potential damage associated
with its stormwater runoff. Timber Lark Residential will detain per the 100-year historic runoff
from the site.
The drainage plan and stormwater measurements proposed with Timber Lark Residential are
compliant with all applicable State and Fedaral regulations.
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: TIMBER LARK RESIDENTIAL
FORT COLLINS | GREELEY 12 | 11
VI. 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. Final Drainage Report for Linden Park P.D.P., TST, Inc., Fort Collins, Colorado, May 30, 2000.
3. Final Drainage Report for Paragon Estates, TST, Inc., Fort Collins, Colorado, September 12, 1994.
4. 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.
5. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service,
United States Department of Agriculture.
6. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District,
Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008.
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: TIMBER LARK RESIDENTIAL
FORT COLLINS | GREELEY APPENDIX
APPENDIX A
HYDROLOGIC COMPUTATIONS
Runoff Coefficient1
Percent
Impervious1
0.95 100%
0.95 90%
0.85 90%
0.55 50%
0.20 2%
0.20 2%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt,
Concrete (acres)Rooftop (acres)Residential: High
Density (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
H-A1 75,250 1.728 0.000 0.000 0.000 0.000 1.728 0.000 2%0.20 0.20 0.20 0.25
H-A2 903,864 20.750 0.000 0.000 0.000 0.000 20.750 0.000 2%0.20 0.20 0.20 0.25
H-A3 474,765 10.899 0.000 0.000 0.000 0.000 10.899 0.000 2%0.20 0.20 0.20 0.25
H-A4 78,249 1.796 0.000 0.000 0.000 0.000 1.796 0.000 2%0.20 0.20 0.20 0.25
OS1 769,218 17.659 0.000 0.000 0.000 0.000 17.659 0.000 2%0.20 0.20 0.20 0.25
Total 1,532,128 35.173 0.000 0.000 0.000 0.000 35.173 0.000 2%0.20 0.20 0.20 0.25
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.
Offsite Basins
EXISTING RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Residential: High Density
Residential: Low Density
South Timberline Res.
F. Wegert
July 7, 2021
Project:
Calculations By:
Date:
Character of Surface
Streets, Parking Lots, Roofs, Alleys, and Drives:
Page 1 of 3
Project:
Date:
Where: V = Velocity (ft/sec)
n = Roughness Coefficient
R = Hydraulic Radius (feet)
S = Longitudinal Slope, feet/feet
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
(%)Surface Roughness
(n)
Flow
Area3
(sq.ft.)
WP
3
(ft)
Hydraulic
Radius (ft)
Velocity
(ft/s)
Tt
(min)
Max.
Tc
(min)
Comp.
Tc 2-Yr
(min)
Tc
2-Yr
(min)
Comp.
Tc 10-Yr
(min)
Tc
10-Yr
(min)
Comp.
Tc 100-Yr
(min)
Tc
100-Yr
(min)
h-a1 H-A1 298 53.25 44.61 2.90%20.4 20.4 19.2 527 44.61 38.26 1.20%Swale (8:1)0.035 8.00 16.12 0.50 2.93 3.00 14.58 23.37 14.58 23.37 14.58 22.24 14.58
h-a2 H-A2 162 56.31 46.64 5.97%11.8 11.8 11.2 2301 46.64 30.99 0.68%Swale (4:1)0.035 4.00 8.25 0.48 2.17 17.70 23.68 29.51 23.68 29.51 23.68 28.85 23.68
h-a3 H-A3 300 50.31 43.49 2.27%22.2 22.2 20.9 1250 43.49 34.20 0.74%Swale (8:1)0.035 8.00 16.12 0.50 2.30 9.06 18.61 31.23 18.61 31.23 18.61 29.99 18.61
h-a4 H-A4 300 43.32 38.25 1.69%24.5 24.5 23.1 211 38.25 36.48 0.84%Swale (8:1)0.035 8.00 16.12 0.50 2.44 1.44 12.84 25.91 12.84 25.91 12.84 24.55 12.84
os1 OS1 82 44.74 43.00 2.12%11.9 11.9 11.2 1569 43.00 23.00 1.27%Swale (8:1)0.035 8.00 16.12 0.50 3.01 8.68 19.17 20.54 19.17 20.54 19.17 19.88 19.17
total Total 162 56.31 46.64 5.97%11.8 11.8 11.2 2301 46.64 30.99 0.68%Swale (4:1)0.035 4.00 8.25 0.48 2.17 17.70 23.68 29.51 23.68 29.51 23.68 28.85 23.68
July 7, 2021
Combined Basins
Design
Point Basin
Overland Flow Channelized Flow Time of Concentration
Offsite Basins
EXISTING TIME OF CONCENTRATION COMPUTATIONS
Overland Flow, Time of Concentration:
Calculations By:
South Timberline Res.
F. Wegert
Maximum Tc:
Channelized Flow, Velocity:Channelized Flow, Time of Concentration:
(Equation 3.3-2 per Fort Collins
Stormwater Manual)𝑅𝑖=1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑅ൗ13
𝑉=1.49
𝑛∗𝑅2/3 ∗𝑅(Equation 5-4 per Fort Collins Stormwater Manual)
𝑅𝑐=𝐿
180 +10 (Equation 3.3-5 per Fort Collins Stormwater Manual)
𝑅𝑡=𝐿
𝑉∗60
(Equation 5-5 per Fort Collins Stormwater Manual)
Notes:
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
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)
h-a1 H-A1 1.728 14.58 14.58 14.58 0.20 0.20 0.25 1.90 3.24 6.62 0.7 1.1 2.9
h-a2 H-A2 20.750 23.68 23.68 23.68 0.20 0.20 0.25 1.48 2.52 5.15 6.1 10.5 26.7
h-a3 H-A3 10.899 18.61 18.61 18.61 0.20 0.20 0.25 1.68 2.86 5.84 3.7 6.2 15.9
h-a4 H-A4 1.796 12.84 12.84 12.84 0.20 0.20 0.25 2.02 3.45 7.04 0.7 1.2 3.2
os1 OS1 17.659 19.17 19.17 19.17 0.20 0.20 0.25 1.65 2.82 5.75 5.8 10.0 25.4
total Total 35.173 23.68 23.68 23.68 0.20 0.20 0.25 1.48 2.52 5.15 10.4 17.7 45.2
Combined Basins
EXISTING DIRECT RUNOFF COMPUTATIONS
Intensity Flow
South Timberline Res.
F. Wegert
July 7, 2021
Project:
Calculations By:
Date:
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Offsite Basins
Design
Point Basin Area
(acres)
Runoff C
Intensity, I from Fig. 3.4.1 Fort Collins Stormwater Manual
Tc (Min)
Page 3 of 3
Runoff Coefficient1
Percent
Impervious1 Project:
Location:
0.95 100%Calc. By:
0.95 90%Date:
0.85 90%
0.55 50%
0.20 2%
0.20 2%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt, Concrete
(acres)Rooftop (acres)Residential: High
Density (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
A1 100,959 2.32 0.02 0.00 0.10 0.00 0.00 2.20 7%0.23 0.23 0.23 0.29
A2a 51,896 1.19 50%0.55 0.55 0.55 0.69
A2b 29,912 0.69 50%0.55 0.55 0.55 0.69
A3 95,602 2.19 50%0.55 0.55 0.55 0.69
A4 120,520 2.77 50%0.55 0.55 0.55 0.69
A5 199,678 4.58 50%0.55 0.55 0.55 0.69
A6 275,823 6.33 50%0.55 0.55 0.55 0.69
A7 156,374 3.59 50%0.55 0.55 0.55 0.69
A8 20,111 0.46 0.26 0.06 0.00 0.00 0.00 0.15 67%0.71 0.71 0.71 0.89
A9 167,208 3.84 50%0.55 0.55 0.55 0.69
A10 40,983 0.94 90%0.85 0.85 0.85 1.00
A11 19,556 0.45 0.28 0.01 0.00 0.00 0.00 0.16 64%0.68 0.68 0.68 0.84
A12 97,988 2.25 90%0.85 0.85 0.85 1.00
A13 55,631 1.28 0.00 0.00 0.31 0.00 0.00 0.97 23%0.36 0.36 0.36 0.45
A14 14,947 0.34 0.25 0.00 0.00 0.00 0.00 0.09 74%0.76 0.76 0.76 0.94
A15 84,828 1.95 0.50 0.00 0.00 1.36 0.00 0.09 61%0.64 0.64 0.64 0.79
Assumed Residential High Density, i = 90%, c = 0.65
Lawns and Landscaping:
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
Assumed Residential Low Density, i = 50%, c = 0.55
Assumed Residential Low Density, i = 50%, c = 0.55
Assumed Residential Low Density, i = 50%, c = 0.55
Assumed Residential Low Density, i = 50%, c = 0.55
Assumed Residential Low Density, i = 50%, c = 0.55
Assumed Residential Low Density, i = 50%, c = 0.55
Assumed Residential High Density, i = 90%, c = 0.85
DEVELOPED RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Residential: High Density
Residential: Low Density
Streets, Parking Lots, Roofs, Alleys, and Drives:
Character of Surface:
Assumed Residential Low Density, i = 50%, c = 0.56
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.
South Timberline Res.
Fort Collins
F. Wegert
July 7, 2021
Assumed Residential Low Density, i = 50%, c = 0.56
Runoff Coefficient1
Percent
Impervious1 Project:
Location:
0.95 100%Calc. By:
0.95 90%Date:
0.85 90%
0.55 50%
0.20 2%
0.20 2%
Basin ID Basin Area
(sq.ft.)
Basin Area
(acres)
Asphalt, Concrete
(acres)Rooftop (acres)Residential: High
Density (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
Lawns and Landscaping:
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
DEVELOPED RUNOFF COEFFICIENT CALCULATIONS
Asphalt, Concrete
Rooftop
Residential: High Density
Residential: Low Density
Streets, Parking Lots, Roofs, Alleys, and Drives:
Character of Surface:
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.
South Timberline Res.
Fort Collins
F. Wegert
July 7, 2021
OS1 769,218 17.66 0.00 0.00 0.00 0.00 17.66 0.00 2%0.20 0.20 0.20 0.25
UC 944,707 21.69 0.26 0.06 0.00 21.23 0.00 0.15 50%0.55 0.55 0.55 0.69
RG1 40,983 0.94 0.00 0.00 0.94 0.00 0.00 0.00 90%0.85 0.85 0.85 1.00
RG2 155,406 3.57 0.75 0.00 0.31 1.36 0.00 1.15 49%0.55 0.55 0.55 0.68
WQ1 390,918 8.97 0.29 0.01 2.35 3.96 0.00 2.36 50%0.55 0.55 0.55 0.69
Total 1,532,014 35.17 0.80 0.06 3.19 27.13 0.00 3.98 49%0.55 0.55 0.55 0.68
Offsite Basins5
Combined Basins1,2,3,4
Notes:
1)Basin UC consist of all basins draining towards the underground chambers (Basins A2b, A3, A5, A6, A7, A8, & A9).
2) Basin RG1 consist of all basins draining towards Rain Garden 1 (Basin A10).
3) Basin RG2 consist of all basins draining towards Rain Garden 2 (Basins A13, A14, & A15).
4) Basin WQ1 consist of all basins draining into detention pond that is not treated by a rain garden or underground
chambers (Basins A1, A2a, A4, A11, & A12).
5) Basin OS1 is provided to facilitate the capacity calculations for the Paragon Estates Channel along the south side of Trilby
Road.
Where:
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
(%)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 10-Yr
(min)
Tc
10-Yr
(min)
Comp.
Tc 100-
Yr
(min)
Tc
100-Yr
(min)
a1 A1 80 35.45 29.10 7.94%7.26 7.26 6.76 680 29.10 25.20 0.57%Valley Pan 0.02 6.00 10.25 0.59 5.26 2.15 14.22 9.41 9.41 9.41 9.41 8.92 8.92
a2a A2a 55 38.25 35.81 4.44%4.64 4.64 3.48 724 35.81 32.99 0.39%Gutter 0.02 3.61 19.18 0.19 2.04 5.92 14.33 10.57 10.57 10.57 10.57 9.41 9.41
a2b A2b 60 38.25 36.79 2.43%5.92 5.92 4.44 377 36.79 34.48 0.61%Gutter 0.02 3.61 19.18 0.19 2.55 2.46 12.43 8.38 8.38 8.38 8.38 6.90 6.90
a3 A3 45 42.39 42.20 0.42%9.20 9.20 6.90 570 42.20 35.64 1.15%Gutter 0.02 3.61 19.18 0.19 3.50 2.71 13.42 11.91 11.91 11.91 11.91 9.61 9.61
a4 A4 30 38.93 38.25 2.27%4.29 4.29 3.22 550 38.25 38.22 0.01%Gutter 0.02 3.61 19.18 0.19 0.24 38.03 13.22 42.32 13.22 42.32 13.22 41.25 13.22
a5 A5 35 46.44 46.09 1.00%6.08 6.08 4.56 960 46.09 34.33 1.23%Gutter 0.02 3.61 19.18 0.19 3.61 4.43 15.53 10.51 10.51 10.51 10.51 8.99 8.99
a6 A6 215 52.99 44.16 4.11%9.42 9.42 7.06 660 44.16 35.60 1.30%Gutter 0.02 3.61 19.18 0.19 3.72 2.96 14.86 12.38 12.38 12.38 12.38 10.02 10.02
a7 A7 110 51.99 50.02 1.79%8.88 8.88 6.66 725 50.02 37.23 1.76%Gutter 0.02 3.61 19.18 0.19 4.33 2.79 14.64 11.67 11.67 11.67 11.67 9.45 9.45
a8 A8 40 43.00 42.97 0.08%10.96 10.96 5.98 318 42.97 38.83 1.30%Gutter 0.02 3.61 19.18 0.19 3.72 1.42 11.99 12.38 11.99 12.38 11.99 7.41 7.41
a9 A9 120 49.89 47.12 2.31%8.53 8.53 6.39 700 47.12 38.86 1.18%Gutter 0.02 3.61 19.18 0.19 3.55 3.29 14.56 11.82 11.82 11.82 11.82 9.68 9.68
a10 A10 45 37.32 34.93 5.31%1.80 1.80 0.72 250 34.93 32.42 1.00%Gutter 0.02 3.61 19.18 0.19 3.27 1.27 11.64 3.07 5.00 3.07 5.00 1.99 5.00
a11 A11 30 36.94 36.39 1.83%3.55 3.55 2.14 425 36.39 33.41 0.70%Gutter 0.02 3.61 19.18 0.19 2.73 2.59 12.53 6.15 6.15 6.15 6.15 4.73 5.00
a12 A12 20 41.75 41.49 1.30%1.92 1.92 0.77 730 41.49 33.41 1.11%Gutter 0.02 3.61 19.18 0.19 3.43 3.54 14.17 5.46 5.46 5.46 5.46 4.31 5.00
a13 A13 80 37.93 33.75 5.23%7.17 7.17 6.31 505 33.75 31.23 0.50%Swale (4:1)0.04 4.00 8.25 0.48 1.86 4.53 13.25 11.70 11.70 11.70 11.70 10.84 10.84
a14 A14 25 41.73 41.13 2.40%2.41 2.41 1.09 500 41.13 37.00 0.83%Gutter 0.02 3.61 19.18 0.19 2.97 2.81 12.92 5.22 5.22 5.22 5.22 3.90 5.00
a15 A15 70 43.79 41.99 2.57%5.30 5.30 3.48 620 41.99 37.00 0.80%Gutter 0.02 3.61 19.18 0.19 2.93 3.53 13.83 8.83 8.83 8.83 8.83 7.01 7.01
os1 OS1 82 44.74 43.00 2.12%11.86 11.86 11.20 1,569 43.00 23.00 1.27%Swale (8:1)0.04 8.00 16.12 0.50 3.01 8.68 19.17 20.54 19.17 20.54 19.17 19.88 19.17
uc UC 110 51.99 50.02 1.79%8.83 8.83 6.59 1,565 50.02 34.68 0.98%Gutter 0.02 3.61 19.18 0.19 3.23 8.07 19.31 16.90 16.90 16.90 16.90 14.67 14.67
rg1 RG1 45 37.32 34.93 5.31%1.80 1.80 0.72 250 34.93 32.42 1.00%Gutter 0.02 3.61 19.18 0.19 3.27 1.27 11.64 3.07 5.00 3.07 5.00 1.99 5.00
rg2 RG2 70 43.79 41.99 2.57%6.31 6.31 4.75 1,270 41.99 34.78 0.57%Gutter 0.02 3.61 19.18 0.19 2.46 8.61 17.44 14.92 14.92 14.92 14.92 13.36 13.36
wq1 WQ1 20 41.75 41.49 1.30%4.21 4.21 3.16 1,590 41.49 32.86 0.54%Gutter 0.02 3.61 19.18 0.19 2.40 11.02 18.94 15.24 15.24 15.24 15.24 14.18 14.18
total Total 70 43.79 41.99 2.57%6.31 6.31 4.75 2,130 41.99 32.86 0.43%Valley Pan 0.02 6.00 10.25 0.59 4.55 7.80 22.22 14.11 14.11 14.11 14.11 12.55 12.55
Combined Basins
Design
Point Basin ID
Overland Flow Channelized Flow Time of Concentration
Offsite Basins
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Location:
Maximum Tc:Overland Flow, Time of Concentration:
Channelized Flow, Velocity:Channelized Flow, Time of Concentration:
South Timberline Res.
Fort Collins
F. Wegert
July 7, 2021
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 Manual)𝑅𝑖=1.87 1.1 −𝐶∗𝐶𝑓𝐿
𝑅ൗ13
𝑉=1.49
𝑛∗𝑅2/3 ∗𝑅(Equation 5-4 per Fort Collins Stormwater Manual)
𝑅𝑐=𝐿
180 +10 (Equation 3.3-5 per Fort Collins
Stormwater Manual)
𝑅𝑡=𝐿
𝑉∗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 of 1', 4:1 side slopes, and a 2' wide valley pan for channelized
flow in a valley pan.
Intensity, I from Fig. 3.4.1 Fort Collins Stormwater Manual
Rational Equation: Q = CiA (Equation 6-1 per MHFD)
Tc2 Tc10 Tc100 C2 C10 C100 I2 I10 I100 Q2 Q10 Q100
a1 A1 2.32 9.4 9.4 8.9 0.2 0.2 0.3 2.3 3.9 8.2 1.3 2.1 5.6
a2a A2a 1.19 10.6 10.6 9.4 0.6 0.6 0.7 2.2 3.7 8.0 1.4 2.4 6.6
a2b A2b 0.69 8.4 8.4 6.9 0.6 0.6 0.7 2.4 4.1 9.1 0.9 1.5 4.3
a3 A3 2.19 11.9 11.9 9.6 0.6 0.6 0.7 2.1 3.6 7.9 2.5 4.3 11.9
a4 A4 2.77 13.2 13.2 13.2 0.6 0.6 0.7 2.0 3.4 6.9 3.0 5.2 13.2
a5 A5 4.58 10.5 10.5 9.0 0.6 0.6 0.7 2.2 3.7 8.2 5.5 9.3 25.9
a6 A6 6.33 12.4 12.4 10.0 0.6 0.6 0.7 2.1 3.5 7.7 7.1 12.2 33.6
a7 A7 3.59 11.7 11.7 9.4 0.6 0.6 0.7 2.1 3.6 8.0 4.1 7.0 19.8
a8 A8 0.46 12.0 12.0 7.4 0.7 0.7 0.9 2.1 3.6 8.8 0.7 1.2 3.6
a9 A9 3.84 11.8 11.8 9.7 0.6 0.6 0.7 2.1 3.6 7.9 4.4 7.5 20.8
a10 A10 0.94 5.0 5.0 5.0 0.9 0.9 1.0 2.9 4.9 10.0 2.3 3.9 9.4
a11 A11 0.45 6.1 6.1 5.0 0.7 0.7 0.8 2.7 4.6 10.0 0.8 1.4 3.8
a12 A12 2.25 5.5 5.5 5.0 0.9 0.9 1.0 2.9 4.9 10.0 5.4 9.3 22.4
a13 A13 1.28 11.7 11.7 10.8 0.4 0.4 0.4 2.1 3.6 7.6 1.0 1.6 4.3
a14 A14 0.34 5.2 5.2 5.0 0.8 0.8 0.9 2.9 4.9 10.0 0.7 1.3 3.2
a15 A15 1.95 8.8 8.8 7.0 0.6 0.6 0.8 2.4 4.0 8.8 2.9 5.0 13.6
os1 OS1 17.66 19.2 19.2 19.2 0.2 0.2 0.3 1.7 2.8 5.8 5.8 10.0 25.4
uc UC 21.69 16.9 16.9 14.7 0.6 0.6 0.7 1.8 3.0 6.6 21.4 36.4 99.2
rg1 RG1 0.94 5.0 5.0 5.0 0.9 0.9 1.0 2.9 4.9 10.0 2.3 3.9 9.4
rg2 RG2 3.57 14.9 14.9 13.4 0.5 0.5 0.7 1.9 3.2 6.9 3.7 6.3 16.9
wq1 WQ1 8.97 15.2 15.2 14.2 0.6 0.6 0.7 1.9 3.2 6.7 9.2 15.7 41.4
total Total 35.17 14.1 14.1 12.5 0.5 0.5 0.7 1.9 3.3 7.0 37.0 63.3 169.4
DEVELOPED DIRECT RUNOFF COMPUTATIONS
Intensity (in/hr)Flow (cfs)
South Timberline Res.
F. Wegert
July 7, 2021
Design
Point Basin Area
(acres)
Runoff CTc (Min)
Combined Basins
Offsite Basins
Date:
Fort Collins
Project:
Location:
Calc. By:
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: TIMBER LARK RESIDENTIAL
FORT COLLINS | GREELEY APPENDIX
APPENDIX B
HYDRAULIC COMPUTATIONS
Linden Park Outfall with a release rate of 40 cfs from Timber Lark Residential
Linden Park Outfall with a release rate of 40 cfs from Timber Lark Residential
Linden Park Outfall with a release rate of 40 cfs from Timber Lark Residential
Linden Park Outfall with a release rate of 45.2 cfs from Timber Lark Residential
Linden Park Outfall with a release rate of 45.2 cfs from Timber Lark Residential
Linden Park Outfall with a release rate of 45.2 cfs from Timber Lark Residential
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Tuesday, Jun 29 2021
Section 1 at 100-Year Flowrate
Triangular
Side Slopes (z:1) = 6.00, 7.45
Total Depth (ft) = 3.46
Invert Elev (ft) = 100.00
Slope (%) = 0.20
N-Value = 0.030
Calculations
Compute by: Known Q
Known Q (cfs) = 169.00
Highlighted
Depth (ft) = 2.97
Q (cfs) = 169.00
Area (sqft) = 59.32
Velocity (ft/s) = 2.85
Wetted Perim (ft) = 40.39
Crit Depth, Yc (ft) = 2.09
Top Width (ft) = 39.95
EGL (ft) = 3.10
0 5 10 15 20 25 30 35 40 45 50 55 60
Elev (ft)Depth (ft)Section
99.00 -1.00
100.00 0.00
101.00 1.00
102.00 2.00
103.00 3.00
104.00 4.00
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Tuesday, Jun 29 2021
Section 2 at 100-Year Flowrate
Triangular
Side Slopes (z:1) = 5.64, 5.91
Total Depth (ft) = 2.61
Invert Elev (ft) = 100.00
Slope (%) = 1.00
N-Value = 0.030
Calculations
Compute by: Known Q
Known Q (cfs) = 127.90
Highlighted
Depth (ft) = 2.10
Q (cfs) = 127.90
Area (sqft) = 25.47
Velocity (ft/s) = 5.02
Wetted Perim (ft) = 24.62
Crit Depth, Yc (ft) = 1.99
Top Width (ft) = 24.25
EGL (ft) = 2.49
0 5 10 15 20 25 30 35 40 45
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
102.50 2.50
103.00 3.00
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Tuesday, Jun 29 2021
Section 3 at 100-Year Flowrate
Triangular
Side Slopes (z:1) = 5.57, 5.34
Total Depth (ft) = 2.76
Invert Elev (ft) = 100.00
Slope (%) = 2.50
N-Value = 0.030
Calculations
Compute by: Known Q
Known Q (cfs) = 127.90
Highlighted
Depth (ft) = 1.81
Q (cfs) = 127.90
Area (sqft) = 17.87
Velocity (ft/s) = 7.16
Wetted Perim (ft) = 20.08
Crit Depth, Yc (ft) = 2.03
Top Width (ft) = 19.75
EGL (ft) = 2.61
0 5 10 15 20 25 30 35 40 45
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
102.50 2.50
103.00 3.00
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Tuesday, Jun 29 2021
Section 4 at 100-Year Flowrate
User-defined
Invert Elev (ft) = 100.00
Slope (%) = 1.20
N-Value = 0.030
Calculations
Compute by: Known Q
Known Q (cfs) = 91.40
(Sta, El, n)-(Sta, El, n)...
( 0.00, 101.59)-(2.80, 100.74, 0.030)-(13.00, 100.00, 0.030)-(18.80, 100.00, 0.030)-(24.40, 101.59, 0.030)
Highlighted
Depth (ft) = 1.23
Q (cfs) = 91.40
Area (sqft) = 18.97
Velocity (ft/s) = 4.82
Wetted Perim (ft) = 22.22
Crit Depth, Yc (ft) = 1.18
Top Width (ft) = 21.95
EGL (ft) = 1.59
-5 0 5 10 15 20 25 30
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
Sta (ft)
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Tuesday, Jun 29 2021
Section 5 at 100-Year Flowrate
User-defined
Invert Elev (ft) = 100.00
Slope (%) = 3.10
N-Value = 0.030
Calculations
Compute by: Known Q
Known Q (cfs) = 91.40
(Sta, El, n)-(Sta, El, n)...
( 0.00, 101.38)-(3.40, 100.39, 0.030)-(8.00, 100.00, 0.030)-(12.20, 100.00, 0.030)-(19.00, 101.38, 0.030)
Highlighted
Depth (ft) = 1.11
Q (cfs) = 91.40
Area (sqft) = 12.80
Velocity (ft/s) = 7.14
Wetted Perim (ft) = 16.97
Crit Depth, Yc (ft) = 1.35
Top Width (ft) = 16.74
EGL (ft) = 1.90
-2 0 2 4 6 8 10 12 14 16 18 20 22
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
Sta (ft)
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: TIMBER LARK RESIDENTIAL
FORT COLLINS | GREELEY APPENDIX
APPENDIX C
DETENTION POND & WATER QUALITY
COMPUTATIONS
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.015)
--------------------------------------------------------------
*********************************************************
NOTE: The summary statistics displayed in this report are
based on results found at every computational time step,
not just on results from each reporting time step.
*********************************************************
****************
Analysis Options
****************
Flow Units ............... CFS
Process Models:
Rainfall/Runoff ........ YES
RDII ................... NO
Snowmelt ............... NO
Groundwater ............ NO
Flow Routing ........... YES
Ponding Allowed ........ NO
Water Quality .......... NO
Infiltration Method ...... HORTON
Flow Routing Method ...... KINWAVE
Starting Date ............ 03/15/2016 00:00:00
Ending Date .............. 03/20/2016 00:00:00
Antecedent Dry Days ...... 0.0
Report Time Step ......... 00:05:00
Wet Time Step ............ 00:05:00
Dry Time Step ............ 01:00:00
Routing Time Step ........ 15.00 sec
************************** Volume Depth
Runoff Quantity Continuity acre-feet inches
************************** --------- -------
Total Precipitation ...... 10.754 3.669
Evaporation Loss ......... 0.000 0.000
Infiltration Loss ........ 3.092 1.055
Surface Runoff ........... 7.552 2.577
Final Storage ............ 0.147 0.050
Continuity Error (%) ..... -0.354
************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow ....... 0.000 0.000
Wet Weather Inflow ....... 7.552 2.461
Groundwater Inflow ....... 0.000 0.000
RDII Inflow .............. 0.000 0.000
External Inflow .......... 0.000 0.000
External Outflow ......... 7.551 2.461
Flooding Loss ............ 0.000 0.000
Evaporation Loss ......... 0.000 0.000
Exfiltration Loss ........ 0.000 0.000
Initial Stored Volume .... 0.000 0.000
Final Stored Volume ...... 0.000 0.000
Continuity Error (%) ..... 0.012
********************************
Highest Flow Instability Indexes
********************************
All links are stable.
*************************
Routing Time Step Summary
*************************
Minimum Time Step : 15.00 sec
Average Time Step : 15.00 sec
Maximum Time Step : 15.00 sec
Percent in Steady State : 0.00
Average Iterations per Step : 1.00
Percent Not Converging : 0.00
***************************
Subcatchment Runoff Summary
***************************
--------------------------------------------------------------------------------------------------------------
Total Total Total Total Imperv Perv Total Total Peak Runoff
Precip Runon Evap Infil Runoff Runoff Runoff Runoff Runoff Coeff
Subcatchment in in in in in in in 10^6 gal CFS
--------------------------------------------------------------------------------------------------------------
UC 3.67 0.00 0.00 1.08 1.80 0.76 2.56 1.51 87.97 0.696
RG1 3.67 0.00 0.00 0.14 3.24 0.23 3.47 0.09 8.87 0.946
RG2 3.67 0.00 0.00 1.10 1.76 0.77 2.53 0.25 14.26 0.689
WQ1 3.67 0.00 0.00 1.08 1.76 0.79 2.55 0.62 37.23 0.696
******************
Node Depth Summary
******************
---------------------------------------------------------------------------------
Average Maximum Maximum Time of Max Reported
Depth Depth HGL Occurrence Max Depth
Node Type Feet Feet Feet days hr:min Feet
---------------------------------------------------------------------------------
OUT-1 OUTFALL 0.00 0.00 4922.40 0 00:00 0.00
POND-1 STORAGE 0.07 4.97 4930.26 0 01:11 4.97
*******************
Node Inflow Summary
*******************
-------------------------------------------------------------------------------------------------
Maximum Maximum Lateral Total Flow
Lateral Total Time of Max Inflow Inflow Balance
Inflow Inflow Occurrence Volume Volume Error
Node Type CFS CFS days hr:min 10^6 gal 10^6 gal Percent
-------------------------------------------------------------------------------------------------
OUT-1 OUTFALL 0.00 40.00 0 00:36 0 2.46 0.000
POND-1 STORAGE 148.33 148.33 0 00:40 2.46 2.46 0.012
*********************
Node Flooding Summary
*********************
No nodes were flooded.
**********************
Storage Volume Summary
**********************
--------------------------------------------------------------------------------------------------
Average Avg Evap Exfil Maximum Max Time of Max Maximum
Volume Pcnt Pcnt Pcnt Volume Pcnt Occurrence Outflow
Storage Unit 1000 ft3 Full Loss Loss 1000 ft3 Full days hr:min CFS
--------------------------------------------------------------------------------------------------
POND-1 1.141 1 0 0 95.422 45 0 01:10 40.00
***********************
Outfall Loading Summary
***********************
-----------------------------------------------------------
Flow Avg Max Total
Freq Flow Flow Volume
Outfall Node Pcnt CFS CFS 10^6 gal
-----------------------------------------------------------
OUT-1 20.68 3.68 40.00 2.460
-----------------------------------------------------------
System 20.68 3.68 40.00 2.460
********************
Link Flow Summary
********************
-----------------------------------------------------------------------------
Maximum Time of Max Maximum Max/ Max/
|Flow| Occurrence |Veloc| Full Full
Link Type CFS days hr:min ft/sec Flow Depth
-----------------------------------------------------------------------------
Pond_Outlet DUMMY 40.00 0 00:36
*************************
Conduit Surcharge Summary
*************************
No conduits were surcharged.
Analysis begun on: Tue Jun 29 08:24:04 2021
Analysis ended on: Tue Jun 29 08:24:04 2021
Total elapsed time: < 1 sec
UDUDUDUDUDUDUDUDUDLINDEN PARKP.D.P., 1ST REPLATLOT 19LOT 18LOT 17LOT 16LOT 15LOT 14LOT 13LOT 12LINDEN PARKP.D.P., 1ST REPLATLOT 11LOT 10LOT 9LOT 8LINDEN PARKP.D.P., 1ST REPLATLINDEN PARKP.D.P., 1ST REPLATLOT 7LOT 6LOT 5LINDEN PARKP.D.P., 1ST REPLATLOT 4LOT 3LOT 2LINDEN PARKP.D.P., 1STREPLATLOT 1FOHYD
HYD CECHYDLIDSDCABLEELEC
ELEC ELECBRKREVAULTF.O.FOELECBRKREDSDSELECBRKREEEHYDFESXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXFOFOFOFOXXXXWWWWX X X X X X X X XXXXXXXXXXXXXXXXXXXXXXXXXXOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUOHUSTSTSTSTSTSTSTSTSTSTDSSTOUTLETSTRUCTUREOUTLETSTRUCTUREOUTLETSTRUCTUREMANHOLE WITHFLOW CONTROLWEIR2.32 ac.A14.58 ac.A56.33 ac.A62.19 ac.A33.84 ac.A90.46 ac.A81.95 ac.A152.36 ac.A120.94 ac.A100.45 ac.A111.16 ac.A133.59 ac.A70.34 ac.A142.77A417.66 ac.OS1STORM TECHCHAMBERSRAIN GARDEN 1RAIN GARDEN 2DETENTION PONDSTREET ASTREET ASTREET ASTREET BSTREET BSTREET I
ALLEY M
ALLEY N
ALLEY O
ALLEY P
GOLDEN WILLOW DRIVE
STREET CSTREET EWEEPING WILLOW DRIVE
STREET G
ALLEY K
RED WILLOW DRIVE
ALLEY L
CORONA AVENUESTREET B1.19 ac.A2a0.69 ac.A2bNORTH( IN FEET )01 INCH = 80 FEET8080160240ENGINEERNGIEHTRONRNLID EXHIBIT2021-07-07FORT COLLINS, COSOUTH TIMBERLINE SUBP:\698-004\DRAINAGE\WATQUAL\LID\698-004_LID.DWGPROPOSED STORM SEWERPROPERTY BOUNDARYPROPOSED INLETADESIGN POINTDRAINAGE BASIN LABELDRAINAGE BASIN BOUNDARYALEGEND:AREA TREATED BY LID 1AREA TREATED BY LID 2AREA TREATED BY LID 3LID Summary per BasinBasin IDAreaPercentImperviousLID IDTreatmentTypeTotal ImperviousArea (sq. ft.)Sq. Ft.AcresA1100,9592.327%n/an/a7,067A2a51,8961.1950%n/an/a25,948A2b29,9120.6950%LID 1Stormtech14,956A395,6022.1950%LID 1Stormtech47,801A4120,5202.7750%n/an/a60,260A5199,6784.5850%LID 1Stormtech99,839A6275,8236.3350%LID 1Stormtech137,911A7156,3743.5950%LID 1Stormtech78,187A820,1110.4667%LID 1Stormtech13,546A9167,2083.8450%LID 1Stormtech83,604A1040,9830.9490%LID 2Rain Garden 136,885A1119,5560.4564%n/an/a12,510A1297,9882.2590%n/an/a88,189A1355,6311.2823%LID 3Rain Garden 212,795A1414,9470.3474%LID 3Rain Garden 211,134A1584,8281.9561%LID 3Rain Garden 251,745Total1,532,01435.17782,377LID Site SummaryTotal Site Area1,532,014sq. ft.Total Impervious Area782,377sq. ft.Total Impervious Area without LIDTreatment193,974sq. ft.50% Requried Minium Area to be Treated391,189sq. ft.75% Requried Minium Area to be Treated586,783cu. ft.Total Treated Area588,403sq. ft.Percent Impervious Treated by LID75%LID Summary per BasinLID IDAreaWeighted %ImperviousTreatmentTypeRequiredVolume (cu. ft.)Total ImperviousArea (sq. ft.)Sq. Ft.AcresLID 1944,70721.6950%Stormtech15,589475,844LID 240,9830.9490%Rain Garden 11,31536,885LID 3155,4063.5749%Rain Garden 22,53275,674Total1,141,09726.2019,436588,403
Project:
Calc. By:
Date:
0.94 <-- INPUT from impervious calcs
90%<-- INPUT from impervious calcs
0.90 <-- CALCULATED
12 hours <-- from FCSM Figure 5.4-1
0.80 <-- from FCSM Figure 5.4-1
0.32 <-- MHFD Vol. 3 Equation 3-1
0.03 <-- FCSCM Equation 7-2
1,315 <-- Calculated from above
**<-- INPUT from stage-storage table
**<-- CALCULATED from Equation EDB-3
dia (in) =**
number of columns=**
number of rows =**
number of holes =**
Area Per Row =**
Total Outlet Area (in2) =**<-- CALCULATED from total number of holes
WQCV (watershed inches) =
WATER QUALITY POND DESIGN CALCULATIONS
Rain Garden 1
South Timberline Residential
F. Wegert
July 7, 2021
Required Storage & Outlet Works
Basin Area (acres) =
Basin Percent Imperviousness =
Basin Imperviousness Ratio =
Drain Time =
Drain Time Coefficient =
**To be completed at final design
WQCV (ac-ft) =
WQ Depth (ft) =
Area Required Per Row, a (in2) =
Circular Perforation Sizing
WQCV (cu. ft.) =
NORTHERNENGINEERING.COM | 970.221.4158
FORT COLLINS | GREELEY
Project:
Calc. By:
Date:
3.57 <-- INPUT from impervious calcs
49%<-- INPUT from impervious calcs
0.49 <-- CALCULATED
12 hours <-- from FCSM Figure 5.4-1
0.80 <-- from FCSM Figure 5.4-1
0.16 <-- MHFD Vol. 3 Equation 3-1
0.06 <-- FCSCM Equation 7-2
2,532 <-- Calculated from above
**<-- INPUT from stage-storage table
**<-- CALCULATED from Equation EDB-3
dia (in) =**
number of columns=**
number of rows =**
number of holes =**
Area Per Row =**
Total Outlet Area (in2) =**<-- CALCULATED from total number of holes
**To be completed at final design
WQCV (ac-ft) =
WQ Depth (ft) =
Area Required Per Row, a (in2) =
Circular Perforation Sizing
WQCV (cu. ft.) =
WQCV (watershed inches) =
WATER QUALITY POND DESIGN CALCULATIONS
Rain Garden 2
South Timberline Residential
F. Wegert
July 7, 2021
Required Storage & Outlet Works
Basin Area (acres) =
Basin Percent Imperviousness =
Basin Imperviousness Ratio =
Drain Time =
Drain Time Coefficient =
NORTHERNENGINEERING.COM | 970.221.4158
FORT COLLINS | GREELEY
Project:
Calc. By:
Date:
21.69 <-- INPUT from impervious calcs
50%<-- INPUT from impervious calcs
0.50 <-- CALCULATED
12 hours <-- from FCSM Figure 5.4-1
0.80 <-- from FCSM Figure 5.4-1
0.17 <-- MHFD Vol. 3 Equation 3-1
0.36 <-- FCSCM Equation 7-2
15,589 <-- Calculated from above
**<-- INPUT from stage-storage table
**<-- CALCULATED from Equation EDB-3
dia (in) =**
number of columns=**
number of rows =**
number of holes =**
Area Per Row =**
Total Outlet Area (in2) =**<-- CALCULATED from total number of holes
**To be completed at final design
WQCV (ac-ft) =
WQ Depth (ft) =
Area Required Per Row, a (in2) =
Circular Perforation Sizing
WQCV (cu. ft.) =
WQCV (watershed inches) =
WATER QUALITY POND DESIGN CALCULATIONS
Underground Chambers
South Timberline Residential
F. Wegert
July 7, 2021
Required Storage & Outlet Works
Basin Area (acres) =
Basin Percent Imperviousness =
Basin Imperviousness Ratio =
Drain Time =
Drain Time Coefficient =
NORTHERNENGINEERING.COM | 970.221.4158
FORT COLLINS | GREELEY
Project:
Calc. By:
Date:
8.97 <-- INPUT from impervious calcs
49%<-- INPUT from impervious calcs
0.50 <-- CALCULATED
40 hours <-- from FCSM Figure 5.4-1
1.00 <-- from FCSM Figure 5.4-1
0.21 <-- MHFD Vol. 3 Equation 3-1
0.19 <-- FCSCM Equation 7-2
8,059 <-- Calculated from above
**<-- INPUT from stage-storage table
**<-- CALCULATED from Equation EDB-3
dia (in) =**
number of columns=**
number of rows =**
number of holes =**
Area Per Row =**
Total Outlet Area (in2) =**<-- CALCULATED from total number of holes
WQCV (watershed inches) =
WATER QUALITY POND DESIGN CALCULATIONS
Water Quality for Detention Pond
South Timberline Residential
F. Wegert
July 7, 2021
Required Storage & Outlet Works
Basin Area (acres) =
Basin Percent Imperviousness =
Basin Imperviousness Ratio =
Drain Time =
Drain Time Coefficient =
**To be completed at final design
WQCV (ac-ft) =
WQ Depth (ft) =
Area Required Per Row, a (in2) =
Circular Perforation Sizing
WQCV (cu. ft.) =
NORTHERNENGINEERING.COM | 970.221.4158
FORT COLLINS | GREELEY
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: TIMBER LARK RESIDENTIAL
FORT COLLINS | GREELEY APPENDIX
APPENDIX D
EROSION CONTROL REPORT
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: TIMBER LARK RESIDENTIAL
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 Erosion 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.
NNORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: TIMBER LARK RESIDENTIAL
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
South Timberline Residential
Natural
Resources
Conservation
Service
April 27, 2021
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
36—Fort Collins loam, 3 to 5 percent slopes..............................................13
37—Fort Collins loam, 5 to 9 percent slopes..............................................14
55—Kim loam, 5 to 9 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
K Factor, Whole Soil....................................................................................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
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
44827004482790448288044829704483060448315044832404482700448279044828804482970448306044831504483240495870 495960 496050 496140 496230 496320 496410 496500 496590 496680
495870 495960 496050 496140 496230 496320 496410 496500 496590 496680
40° 30' 0'' N 105° 2' 57'' W40° 30' 0'' N105° 2' 18'' W40° 29' 41'' N
105° 2' 57'' W40° 29' 41'' N
105° 2' 18'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,150 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 15, Jun 9, 2020
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Aug 11, 2018—Aug
12, 2018
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
36 Fort Collins loam, 3 to 5 percent
slopes
13.9 34.6%
37 Fort Collins loam, 5 to 9 percent
slopes
1.8 4.4%
55 Kim loam, 5 to 9 percent slopes 1.5 3.7%
74 Nunn clay loam, 1 to 3 percent
slopes
23.2 57.4%
Totals for Area of Interest 40.4 100.0%
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
Custom Soil Resource Report
11
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.
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
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Larimer County Area, Colorado
36—Fort Collins loam, 3 to 5 percent slopes
Map Unit Setting
National map unit symbol: 2yqpg
Elevation: 4,800 to 5,900 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: Prime farmland if irrigated
Map Unit Composition
Fort collins and similar soils:80 percent
Minor components:20 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Fort Collins
Setting
Landform:Alluvial fans, terraces
Landform position (three-dimensional):Tread
Down-slope shape:Linear, convex
Across-slope shape:Linear
Parent material:Pleistocene or older alluvium and/or eolian deposits
Typical profile
Ap - 0 to 5 inches: loam
Bt1 - 5 to 8 inches: clay loam
Bt2 - 8 to 18 inches: clay loam
Bk1 - 18 to 24 inches: loam
Bk2 - 24 to 80 inches: loam
Properties and qualities
Slope:3 to 5 percent
Depth to restrictive feature:More than 80 inches
Drainage class:Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high
(0.20 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:12 percent
Maximum salinity:Nonsaline to very slightly saline (0.1 to 2.0 mmhos/cm)
Available water capacity:High (about 9.1 inches)
Interpretive groups
Land capability classification (irrigated): 4e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: C
Ecological site: R067BY002CO - Loamy Plains
Hydric soil rating: No
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Minor Components
Table mountain
Percent of map unit:15 percent
Landform:Stream terraces, alluvial fans
Landform position (three-dimensional):Tread
Down-slope shape:Linear
Across-slope shape:Linear
Ecological site:R067BY036CO - Overflow
Hydric soil rating: No
Larim
Percent of map unit:5 percent
Landform:Alluvial fans
Down-slope shape:Linear
Across-slope shape:Linear
Ecological site:R067BY063CO - Gravel Breaks
Hydric soil rating: No
37—Fort Collins loam, 5 to 9 percent slopes
Map Unit Setting
National map unit symbol: 2yqpj
Elevation: 4,800 to 5,500 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
Fort collins and similar soils:80 percent
Minor components:20 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Fort Collins
Setting
Landform:Alluvial fans, terraces
Landform position (three-dimensional):Tread
Down-slope shape:Linear, convex
Across-slope shape:Linear
Parent material:Pleistocene or older alluvium and/or eolian deposits
Typical profile
Ap - 0 to 5 inches: loam
Bt1 - 5 to 8 inches: clay loam
Bt2 - 8 to 18 inches: clay loam
Bk1 - 18 to 24 inches: loam
Bk2 - 24 to 80 inches: loam
Custom Soil Resource Report
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Properties and qualities
Slope:5 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
(0.20 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:12 percent
Maximum salinity:Nonsaline to very slightly saline (0.1 to 2.0 mmhos/cm)
Available water capacity:High (about 9.1 inches)
Interpretive groups
Land capability classification (irrigated): 6e
Land capability classification (nonirrigated): 6e
Hydrologic Soil Group: C
Ecological site: R067BY002CO - Loamy Plains
Hydric soil rating: No
Minor Components
Larim
Percent of map unit:15 percent
Landform:Alluvial fans
Down-slope shape:Linear
Across-slope shape:Linear
Ecological site:R067BY063CO - Gravel Breaks
Hydric soil rating: No
Table mountain
Percent of map unit:5 percent
Landform:Stream terraces, alluvial fans
Landform position (three-dimensional):Riser
Down-slope shape:Linear
Across-slope shape:Linear
Ecological site:R067BY036CO - Overflow
Hydric soil rating: No
55—Kim loam, 5 to 9 percent slopes
Map Unit Setting
National map unit symbol: jpwz
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: Farmland of local importance
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Map Unit Composition
Kim and similar soils:85 percent
Minor components:15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Kim
Setting
Landform:Fans
Landform position (three-dimensional):Base slope, side 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:5 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:15 percent
Maximum salinity:Nonsaline to slightly saline (0.0 to 4.0 mmhos/cm)
Available water capacity:Very high (about 26.5 inches)
Interpretive groups
Land capability classification (irrigated): 4e
Land capability classification (nonirrigated): 6e
Hydrologic Soil Group: B
Ecological site: R067XY002CO - Loamy Plains
Hydric soil rating: No
Minor Components
Thedalund
Percent of map unit:10 percent
Hydric soil rating: No
Stoneham
Percent of map unit:5 percent
Hydric soil rating: No
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
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 content:7 percent
Maximum salinity:Nonsaline to very slightly saline (0.1 to 2.0 mmhos/cm)
Sodium adsorption ratio, maximum:0.5
Available water capacity:High (about 9.9 inches)
Interpretive groups
Land capability classification (irrigated): 2e
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: C
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Ecological site: R067BY042CO - Clayey Plains
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:R067BY042CO - Clayey Plains
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:R067BY002CO - Loamy Plains
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.
K Factor, Whole Soil
Erosion factor K indicates the susceptibility of a soil to sheet and rill erosion by
water. Factor K is one of six factors used in the Universal Soil Loss Equation
(USLE) and the Revised Universal Soil Loss Equation (RUSLE) to predict the
average annual rate of soil loss by sheet and rill erosion in tons per acre per year.
The estimates are based primarily on percentage of silt, sand, and organic matter
and on soil structure and saturated hydraulic conductivity (Ksat). Values of K range
from 0.02 to 0.69. Other factors being equal, the higher the value, the more
susceptible the soil is to sheet and rill erosion by water.
"Erosion factor Kw (whole soil)" indicates the erodibility of the whole soil. The
estimates are modified by the presence of rock fragments.
Factor K does not apply to organic horizons and is not reported for those layers.
19
20
Custom Soil Resource Report
Map—K Factor, Whole Soil
44827004482790448288044829704483060448315044832404482700448279044828804482970448306044831504483240495870 495960 496050 496140 496230 496320 496410 496500 496590 496680
495870 495960 496050 496140 496230 496320 496410 496500 496590 496680
40° 30' 0'' N 105° 2' 57'' W40° 30' 0'' N105° 2' 18'' W40° 29' 41'' N
105° 2' 57'' W40° 29' 41'' N
105° 2' 18'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,150 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
.02
.05
.10
.15
.17
.20
.24
.28
.32
.37
.43
.49
.55
.64
Not rated or not available
Soil Rating Lines
.02
.05
.10
.15
.17
.20
.24
.28
.32
.37
.43
.49
.55
.64
Not rated or not available
Soil Rating Points
.02
.05
.10
.15
.17
.20
.24
.28
.32
.37
.43
.49
.55
.64
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 15, Jun 9, 2020
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Aug 11, 2018—Aug
12, 2018
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—K Factor, Whole Soil
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
36 Fort Collins loam, 3 to 5
percent slopes
.43 13.9 34.6%
37 Fort Collins loam, 5 to 9
percent slopes
.37 1.8 4.4%
55 Kim loam, 5 to 9 percent
slopes
.28 1.5 3.7%
74 Nunn clay loam, 1 to 3
percent slopes
.28 23.2 57.4%
Totals for Area of Interest 40.4 100.0%
Rating Options—K Factor, Whole Soil
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Layer Options (Horizon Aggregation Method): Surface Layer (Not applicable)
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
44827004482790448288044829704483060448315044832404482700448279044828804482970448306044831504483240495870 495960 496050 496140 496230 496320 496410 496500 496590 496680
495870 495960 496050 496140 496230 496320 496410 496500 496590 496680
40° 30' 0'' N 105° 2' 57'' W40° 30' 0'' N105° 2' 18'' W40° 29' 41'' N
105° 2' 57'' W40° 29' 41'' N
105° 2' 18'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,150 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 15, Jun 9, 2020
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Aug 11, 2018—Aug
12, 2018
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
36 Fort Collins loam, 3 to 5
percent slopes
C 13.9 34.6%
37 Fort Collins loam, 5 to 9
percent slopes
C 1.8 4.4%
55 Kim loam, 5 to 9 percent
slopes
B 1.5 3.7%
74 Nunn clay loam, 1 to 3
percent slopes
C 23.2 57.4%
Totals for Area of Interest 40.4 100.0%
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
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: TIMBER LARK RESIDENTIAL
FORT COLLINS | GREELEY APPENDIX
APPENDIX F
EXCERPTS FROM LINDEN PARK DRAINGE REPORT
This unofficial copy was downloaded on Oct-09-2020 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 Oct-09-2020 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 Oct-09-2020 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 Oct-09-2020 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 Oct-09-2020 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
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: TIMBER LARK RESIDENTIAL
FORT COLLINS | GREELEY APPENDIX
APPENDIX G
EXCERPTS FROM PARAGON ESTATES DRAINGE REPORT
NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: TIMBER LARK RESIDENTIAL
FORT COLLINS | GREELEY APPENDIX
MAP POCKET
DR1 – DRAINAGE EXHIBIT
APPENDIX F
REFERENCE DOCUMENTS
FO
HY DHY DC EC
HY DLID
S
D
CABLE
ELEC
ELEC
ELEC
BRKRE
VAULT
F.O.
FO
ELEC
BRKRE
D
S
D
SELEC
BRKREEE HY DF ES
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXFOFOFOFOXXXWWWXXXXXXXXXXXXX X X X X X X X X X XXXXX
OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHUSTSTSTSTSTSTSTST
D
S STUD
IRR IRR
IRRIRRIRR IRR IRR IRR IRR
IRRIRRIRRIRRIRRIRRIRRUDUDUDUDUDUD2.32 ac.
A1
1.19 ac.
A2a
4.58 ac.
A5
6.33 ac.
A6
2.19 ac.
A3
3.84 ac.
A9
0.46 ac.
A8
1.95 ac.
A15
2.25 ac.
A12
0.94 ac.
A10
0.45 ac.
A11
1.28 ac.
A13
3.59 ac.
A7
0.34 ac.
A14
UNDERGROUND
CHAMBERS
DETENTION POND
REQUIRED STORAGE VOLUME = 2.19 AC-FT
WATER QUALITY VOLUME = 0.19 AC-FT
PROVIDED VOLUME = 2.50 AC-FT
OUTLET STRUCTURE
RELEASE RATE = 40 CFS
2.77
A4
STREET A STREET ASTREET A
STREET B STREET B STREET B STREET IALLEY MALLEY NALLEY OALLEY PGOLDEN WILLOW DRIVESTREET CSTREET EWEEPING WILLOW DRIVESTREET GALLEY KRED WILLOW DRIVEALLEY LCORONA AVENUE17.66 ac.
OS1 TIMBERLINE ROADTRILBY ROAD
CONNECTION TO EXISTING 30"
STORM SEWER AT MANHOLE EX-4
(LINDEN PARK STORM OUTFALL)
RAIN GARDEN 2
A2A
A6
A7
A4
A3
A8
A9
A10
A11
A12
A13
A14
A15
A1
###
RAIN GARDEN 1
A5
0.69 ac.
A2b
TIMBERLINE ROADTRILBY ROAD
PARAGON ESTATES NORTH CHANNEL
PARAGON ESTATES
LINDEN PARK
SheetTIMBER LARK RESIDENTIALThese 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 29
NORTH
( IN FEET )
0
1 INCH = 100 FEET
100 100 200 300
DR1 DRAINAGE PLAN29
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 FOR TIMBER LARK, DATED JULY 9,
2021 FOR ADDITIONAL INFORMATION.
A
LEGEND:
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
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