HomeMy WebLinkAboutELIZABETH SUBDIVISION - PDP - PDP160046 - SUBMITTAL DOCUMENTS - ROUND 1 - EROSION CONTROL LETTER/REPORTCOLORADO CIVIL GROUP, INC.
EROSION CONTROL REPORT
FOR
ELIZABETH SUBDIVISION
CITY OF FORT COLLINS
DECEMBER 2016
Colorado Civil Group, Inc.
December 21, 2016
Ms. Heather McDowell, PE
Water Utilities Engineering
City of Fort Collins
281 N College Avenue
Fort Collins, CO 80524
Re: Elizabeth Subdivision
Project No. 0036.0002.00
Dear Ms. McDowell,
We are pleased to submit this Erosion Control Report for the Elizabeth Subdivision. This report was prepared
based on current City of Fort Collins and Urban Drainage Flood Control District storm drainage criteria.
Please let me know if you have any questions or comments.
Sincerely,
COLORADO CIVIL GROUP, INC.
Jamie K. Galyon, PE
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Colorado Civil Group, Inc. i
Table of Contents
1 Introduction .............................................................................................................................................................. 1
1.1 Report Objectives (I.B.1 – I.B.4) ........................................................................................................................ 1
1.2 ECP Administrator (I.C.3.a) ............................................................................................................................... 1
2 Site Description (I.C.1) .............................................................................................................................................. 2
2.1 Site Location ..................................................................................................................................................... 2
2.2 Existing Site Description ................................................................................................................................... 3
2.2.1 Existing Physical Characteristics (I.C.1.c) ............................................................................................. 3
2.2.2 Existing Soil Properties (I.C.1.d) .......................................................................................................... 3
2.2.3 Existing Vegetation (I.C.1.e) ................................................................................................................ 3
2.2.4 Flood Insurance Rate Map (FIRM)....................................................................................................... 4
2.2.5 Existing Receiving Waters (I.C.1.h) ...................................................................................................... 4
2.3 Proposed Site Description ................................................................................................................................ 4
2.3.1 Proposed Construction Activity (I.C.1.a and I.C.1.b) ........................................................................... 4
2.3.2 Proposed Physical Characteristics (I.C.1.a) ......................................................................................... 5
2.3.3 Potential Non‐Stormwater Discharges (I.C.1.g) .................................................................................. 5
2.3.4 Proposed Controls ............................................................................................................................... 5
3 Identification of Pollutant Sources ........................................................................................................................... 5
3.1 Disturbed or Stored Soils (I.C.3.b.1) ................................................................................................................. 5
3.2 Vehicle Tracking of Sediments (I.C.3.b.2) ......................................................................................................... 6
3.3 Management of Contaminated Soils (I.C.3.b.3) ............................................................................................... 6
3.4 Loading and Unloading Operations (I.C.3.b.4) ................................................................................................. 6
3.5 Outdoor Storage Activities (I.C.3.b.5) ............................................................................................................... 6
3.6 Vehicle and Equipment Maintenance and Fueling (I.C.3.b.6) .......................................................................... 6
3.7 Significant Dust or Particulate Generating Processes (I.C.3.b.7) ...................................................................... 7
3.8 Routine Maintenance Activities (I.C.3.b.8) ....................................................................................................... 7
3.9 On‐Site Waste Management Practices (I.C.3.b.9) ............................................................................................ 7
3.10 Concrete Truck Washout (I.C.3.b.10) ............................................................................................................... 7
3.11 Non‐Industrial Waste Sources (I.C.3.b.12) ....................................................................................................... 7
3.12 Other Areas or Procedures where Potential Spills Can Occur (I.C.3.b.13) ....................................................... 7
4 Stormwater Management Controls (I.C.3.c) ............................................................................................................ 8
4.1 Four‐Step Process ............................................................................................................................................. 8
4.1.1 Step 1: Runoff Reduction .................................................................................................................... 8
4.1.2 Step 2: Treat and Slowly Release Runoff ............................................................................................ 8
4.1.3 Step 3: Stabilize Drainageways ........................................................................................................... 9
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4.1.4 Step 4: Implementation of Source Controls ........................................................................................ 9
4.2 Temporary BMPs .............................................................................................................................................. 9
4.2.1 Vehicle Tracking Control Pad with Wheel Washout (I.C.3.c.6) ........................................................... 9
4.2.2 Stabilized Staging Area(Structural ‐ I.C.3.c.1) ..................................................................................... 9
4.2.3 Silt Fence (Structural ‐ I.C.3.c.1) ........................................................................................................ 10
4.2.4 Wattle Dikes (Structural ‐ I.C.3.c.1) ................................................................................................... 10
4.2.5 Curb Inlet Protection (Structural ‐ I.C.3.c.1) ...................................................................................... 10
4.2.6 Surface Roughening and Slope Protection (Non‐Structural ‐ I.C.3.c.2) ............................................ 11
4.3 Permanent BMPs ............................................................................................................................................ 11
4.3.1 Surface Roughening/Mulching and Re‐Seeding (Non‐Structural ‐ I.C.3.c.2) .................................... 11
4.3.2 Rain Gardens (Structural ‐ I.C.3.c.1) .................................................................................................. 12
5 BMPs for Material Handling and Spill Prevention (I.C.3.c.4) .................................................................................. 13
6 Final Stabilization and Ultimate Stormwater Management (I.C.4) ........................................................................ 13
7 Construction Site Inspection and Maintenance (I.C.5, I.D.6, I.D.7) ........................................................................ 14
Figures and Tables
Figure 1‐1: Vicinity Map ................................................................................................................................................ 2
Table 2‐1: Anticipated Construction Phases ................................................................................................................. 4
Table 4‐1: LID Treatment ............................................................................................................................................ 12
Appendices
Appendix A: General Permit Application ...................................................................................................................... A
Appendix B: Existing Soil Information .......................................................................................................................... B
Appendix C: Erosion Control Plan and Details .............................................................................................................. C
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1 Introduction
1.1 Report Objectives (I.B.1 – I.B.4)
The objective of this report is to create an Erosion Control Plan (ECP) to
“identify possible pollutant sources to stormwater and to set out Best Management
Practices (BMPs) that, when implemented, will reduce or eliminate any possible water
quality impacts.” (from Colorado’s Stormwater Program Fact Sheet)
More specifically, this report covers each facility in the General Permit Application for
Stormwater Discharges Associated with Construction Activity (Stormwater Construction
Permit). A copy of the Stormwater Construction Permit will be included in Appendix A
after issuance. This report identifies all potential pollutant sources which could adversely
affect the quality of the discharged stormwater and suggests measures that can be
implemented to reduce stormwater pollutants associated with construction activity. All
measures described within this report are in accordance with good engineering practices,
which include installation, implementation, and maintenance requirements, and must be
updated in accordance with Part I.D.5.c of the Stormwater Construction Permit, to ensure
compliance with the terms and conditions of the permit. Furthermore, any potential
pollutant that can reasonably be expected during construction activity through final
stabilization must be identified and any possible water quality impacts must be reduced
or eliminated by implementing the suggested measures found within this report.
1.2 ECP Administrator (I.C.3.a)
The ECP Administrator is responsible for developing, implementing, maintaining, and
revising the ECP. The ECP Administrator will be assigned by the General Contractor
and should be noted below when the construction contract is awarded:
Name: _____________________________
Title: _____________________________
Company: _____________________________
Address: _____________________________
_____________________________
Phone: _____________________________
Email: _____________________________
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2 Site Description (I.C.1)
2.1 Site Location
The Elizabeth Subdivision site is located in the Southeast Quarter of Section 13, Township
7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of
Larimer, Colorado. The site is bounded on the north by East Elizabeth Street and on
the west, south, and east by neighboring single-family residential lots. A vicinity map is
presented in Figure 1-1. The project area is generally located at Latitude 40° 34’27”
and Longitude -105° 3’47”.
Figure 1-1: Vicinity Map
S LEMAY AVE
PROJECT
AREA
MORGAN ST
S STOVER ST
E ELIZABETH ST
GARFIELD ST
LAUREL
ELEMENTARY
SCHOOL
E LAUREL ST
E PITKIN ST
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2.2 Existing Site Description
2.2.1 Existing Physical Characteristics (I.C.1.c)
The Elizabeth Subdivision project includes the replatting of two parcels (parcels
9713400012 and 9713400006). The northwest lot will be increased from 5,000
square feet to 7,840 square feet. A new single-family home will be built on the
southeast lot. The construction of the single-family home will include a driveway
from Elizabeth Street and off-street parking. The parking lot for the commercial
building will be modified to meet City of Fort Collins setback requirements and to
accommodate the driveway for the single-family home.
2.2.2 Existing Soil Properties (I.C.1.d)
Soil properties described in this section were determined from the Natural
Resources Conservation Service (NRCS) website using the Web Soil Survey to
compile and present the data. The soils found on-site can be classified as 53%
(94) Satanta loam with 0 to 1 percent slopes and 47% (95) Satanta loam, 1 to
3 percent slopes. The soil falls into the wind erodibility group of 5 and has a
wind erodibility index of 56. Wind erodibility groups range from 1 to 8 where
group 1 is the most susceptible to wind erosion and group 8 is the least
susceptible. The wind erodibility index is a numerical value, ranging from 0 to
310, indicating the susceptibility of soil to wind erosion, or the tons per acre per
year that can be expected to be lost to wind erosion. A wind erosion index of
56 indicates that the soil is mildly susceptible to being lost to wind erosion. The
existing site consists of a commercial building with paved parking lot and natural
or landscaped open space. As construction on site progresses, the erosion
potential due to wind in disturbed areas is considered moderate with moderate
potential for soil transportation. Several exhibits are provided in Appendix B that
show the soil properties presented in this section.
2.2.3 Existing Vegetation (I.C.1.e)
The northern portion of the site that is not developed is landscaped with grass,
shrubs, and trees. The southern portion of the site is mainly a non-irrigated grass
area with some trees along the outer boundary. The current imperviousness is
approximately 29%.
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2.2.4 Flood Insurance Rate Map (FIRM)
The project site is located within Zone‘X’ of Community-Panel Number
08069C1189F, revised December 19, 2006. Zone‘X’is defined as“Areas
determined to be outside the 0.2% annual chance floodplain.” A portion of the
referenced map can be found in Appendix B of this report.
2.2.5 Existing Receiving Waters (I.C.1.h)
The project site is part of the Spring Creek Drainage Basin. The Spring Creek
Drainage Basin generally conveys runoff to the Poudre River. Runoff from the
commercial portion of the Elizabeth Subdivision project site is conveyed via sheet
flow to Elizabeth Street. The majority of existing runoff from the residential lot is
conveyed via sheet flow to the neighboring properties on the south and east sides
of the property.
2.3 Proposed Site Description
2.3.1 Proposed Construction Activity (I.C.1.a and I.C.1.b)
The proposed construction activity will begin with the installation of erosion control
devices in Elizabeth Street and along the project boundary. Silt fence will be
installed along the perimeters of the disturbed areas. After the erosion control
devices are installed, construction will begin, including utility installation, grading,
construction of the new buildings, demolition of a portion of the parking, and
asphalt laying for the new driveway. Disturbed areas that are not paved will be
landscaped. After these steps are complete the site will reach final stabilization.
Table 2-1 shows the anticipated construction activities within each phase of site
construction.
Table 2-1: Anticipated Construction Phases
Construction Activity Site Development Phase
Erosion Control Installation Phase I
Utility Installation and Grading Phase II
Building Construction Phase III
Concrete Curb & Gutter and Asphalt Pavement Phase IV
Final Stabilization Phase V
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2.3.2 Proposed Physical Characteristics (I.C.1.a)
The proposed physical characteristics of the site will be modified with the the
construction of the single family residence, demolition of a portion of the existing
parking lot, and paving of the residential driveway. The proposed drainage
patterns will generally follow the existing drainage patterns. There are no
proposed changes in soil type, hydrologic soil group, or drainage class. However,
the imperviousness of the site will be increased to 49% as a result of the
construction.
2.3.3 Potential Non‐Stormwater Discharges (I.C.1.g)
There are several potential non-stormwater discharges associated with construction
activities anticipated for the Elizabeth Subdivision project. The potential discharges
are from the use of a concrete washout, trench dewatering, watering for dust
control and compaction. The concrete waste will be contained within the concrete
washout area or transported off-site and disposed of. No change to regulated
floodplains/floodways are anticipated within the project area.
2.3.4 Proposed Controls
Controls are necessary once construction begins and must continue until the
project is complete, leaving no exposed soils. These controls are critical to
ensuring that downstream receiving waters are protected from contamination due
to soil erosion caused by wind and surface runoff, as well as any potential
chemical or biological contamination anticipated due to construction activities.
Controls used for site development are discussed in greater detail in Section 4.
3 Identification of Pollutant Sources
This section of the ECP report attempts to identify all pollutant sources expected with the
construction of the proposed site. Since it is not possible to know all of the construction
activities that will occur on-site during the creation of this report, it is critical that the Contractor
be aware of all construction activities and their potential to contaminate stormwater either
above or below ground, and if needed, install controls to prevent contamination. The following
sections describe pollutant sources in detail.
3.1 Disturbed or Stored Soils (I.C.3.b.1)
Approximately 47 percent of the site (0.36 acres) will be disturbed with the construction
activities. Once soils have been disturbed, they do not retain the same compaction as
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in their native state, therefore surface runoff can cause more soil erosion than was
historically observed. Stockpiles shall be placed in an area where the proposed BMPs
(i.e. wattles or silt fence) will prevent the migration of soils into the public streets and
stormwater system.
3.2 Vehicle Tracking of Sediments (I.C.3.b.2)
Vehicle tracking of sediments may occur throughout the construction process. The
implementation of street sweeping practices and keeping vehicles on paved surfaces is
critical in reducing pollutants during construction. Vehicle tracking control pads can also
reduce the tracking of sediments.
3.3 Management of Contaminated Soils (I.C.3.b.3)
In the event that soils are found to be contaminated on-site, the ECP Administrator
should be notified. Proper procedures should be followed based on the type and extent
of soil contamination.
3.4 Loading and Unloading Operations (I.C.3.b.4)
Loading and unloading operations will occur on the project site where BMPs will have
been installed. These operations should not introduce contaminants to the stormwater
system. No additional controls for these loading operations are anticipated.
3.5 Outdoor Storage Activities (I.C.3.b.5)
Construction materials may be stored on-site with the construction of the Elizabeth
Subdivision project. However, this storage should not produce any contaminants that
could be transported. Stored liquids (and materials) should be covered with an
impermeable tarp to prevent transportation during precipitation events.
3.6 Vehicle and Equipment Maintenance and Fueling (I.C.3.b.6)
Due to the planned construction activities, is anticipated that equipment maintenance and
fueling will occur on-site. These procedures must only be allowed to occur in one
designated area on-site to limit spillage of maintenance liquids/lubricants and fuel. An
impermeable tarp that prevents fuel and other liquids from infiltrating the soil must cover
the fueling area. Proper disposal of contaminated soil must occur after the construction
is complete or at frequent intervals, if necessary.
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3.7 Significant Dust or Particulate Generating Processes (I.C.3.b.7)
Dust or particulate generation is typical in the northern front range of Colorado, and can
happen anytime during the year. The use of water for dust control is the most common
practice for minimizing particulate generation. Another possible preventative technique
would be to minimize vehicular traffic on days with high winds.
3.8 Routine Maintenance Activities (I.C.3.b.8)
Other than typical vehicle repair and maintenance, there are no other anticipated
maintenance activities that require additional controls.
3.9 On‐Site Waste Management Practices (I.C.3.b.9)
Nearly all construction sites must implement some sort of waste management practice
and the Elizabeth Subdivision project is no exception. Portable toilets and construction
debris must be located in areas where, if spillage occurred, it would not enter the public
streets or stormwater system.
3.10 Concrete Truck Washout (I.C.3.b.10)
Concrete construction is planned for this project, so a designated area for a concrete
truck washout is needed. Part I.D.3.c of the Stormwater Construction Permit must be
followed in order to allow the conditional discharge of concrete washout material to the
designated area. Other equipment washing may occur throughout the construction
process as well, so this equipment should be washed in the same area as the concrete
truck washout. The concrete washout area shall be constructed per the Urban Drainage
Flood Control District (UDFCD) standard details.
3.11 Non‐Industrial Waste Sources (I.C.3.b.12)
One location should be setup for disposing of liquid and solid wastes generated during
the construction process. Containers should be kept closed at all times to prevent waste
from blowing off-site during days with high winds. Construction debris can be stored
until removed from the site and disposed of properly.
3.12 Other Areas or Procedures where Potential Spills Can Occur (I.C.3.b.13)
There are no other areas or procedures to our knowledge where potential spills can
occur with the construction of the Elizabeth Subdivision project.
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4 Stormwater Management Controls (I.C.3.c)
Stormwater management controls are commonly referred to as Best Management Practices, or
BMPs. The typical duration of use for individual BMP's can vary depending on the type of
BMP, the function of the BMP, the type of construction, and the duration of construction
activities. All projects require both temporary and permanent BMPs to be installed during and
following construction activities. The following sections will identify both temporary and
permanent BMPs that are to be used with proposed project. The implementation phase is
provided for each BMP in addition to the inspection interval. Anticipated BMPs to be used
with the Elizabeth Subdivision project have been identified on the Erosion Control Plan, which
is provided in Appendix C. During the design phase, it can be difficult to identify all necessary
preventative measures needed to prevent receiving water contamination; therefore, the
Contractor must monitor the ongoing construction and install any BMP, whether listed in the
report or not, necessary to prevent contamination. The ECP Administrator should modify the
Erosion Control Plan as necessary to document BMP installation and maintenance during the
life of the project.
4.1 Four‐Step Process
The selection of BMPs is part of the “Four-Step Process for Stormwater Quality
Management” as outlined by UDFCD and adopted by the City of Fort Collins. The
following sections explain that four-step process.
4.1.1 Step 1: Runoff Reduction
The first step in stormwater quality management is to reduce runoff peaks,
volumes, and pollutant loads from urbanizing areas by implementing Low Impact
Development (LID) strategies. LID practices include reducing unnecessary
impervious areas and routing runoff from impervious surfaces over permeable
areas to slow runoff and promote infiltration.
4.1.2 Step 2: Treat and Slowly Release Runoff
After reducing the runoff from a site, the second step in stormwater quality
management is to capture and slowly release a Water Quality Capture Volume
(WQCV). WQCV facilities may include bioretention, extended detention basins,
sand filters, constructed wetland ponds, and retention ponds.
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4.1.3 Step 3: Stabilize Drainageways
Although steps 1 and 2 help to minimize the effects of runoff on downstream
drainageways, natural drainageways are often subject to bed and bank erosion
due to increases in the frequency, rate, duration, and volume of runoff. Step 3
includes measures to prevent drainageway erosion.
There are no drainageways on the Elizabeth Subdivision site. By implementing
steps 1 and 2, the project site does its part to reduce drainageway erosion
downstream.
4.1.4 Step 4: Implementation of Source Controls
The final step in stormwater quality management is source control. Site specific
needs such as material storage or other site operations require consideration of
targeted source control Best Management Practices (BMPs). These BMPs are
shown on the Erosion Control Plan and explained in the following sections.
4.2 Temporary BMPs
The following description of temporary BMPs is organized to provide some indication as
to the order in which the BMPs are to be installed. This order is based on typical
construction activity sequencing. Temporary BMP details can be found in Appendix C of
this report.
4.2.1 Vehicle Tracking Control Pad with Wheel Washout (I.C.3.c.6)
Vehicle tracking control pads should be the first BMP installed in the construction
process, when necessary. Tracking control pads can also be supplemented with
a wheel washout, which is a designated area within the tracking control pad to
spray off large material prior to leaving the site. Vehicle tracking control pads
will be installed where indicated on the Erosion Control Plan and should be
installed per the details provided in Appendix C.
Implementation Phase (I.C.3.c.3) - Phase I
Inspection Interval (I.D.6 and I.D.7) - Semi-Monthly
4.2.2 Stabilized Staging Area(Structural ‐ I.C.3.c.1)
A stabilized staging area should be established to ensure there is a large enough
area to fully contain parking, storage, and unloading and loading operations.
These areas can be comprised of a minimum of 3 inch granular material and
constructed as shown on the detail. The Contractor can utilize a portion of the
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commercial building parking lot, which can function as Stabilized Staging Areas
since it is paved.
Implementation Phase (I.C.3.c.3) - Phase I
Inspection Interval (I.D.6 and I.D.7) - Semi-Monthly
4.2.3 Silt Fence (Structural ‐ I.C.3.c.1)
Silt Fence should be one of the first BMPs installed prior to construction and
must be installed before any soil disturbance occurs. Silt Fence should be
installed per the construction plan details and must continually be monitored for
effectiveness. Silt Fence does not need to be installed around the entire
construction site; it only needs to be installed where surface runoff might transport
sediment or other materials off-site. Silt Fence will be installed where indicated
on the Erosion Control Plan. Additional silt fence should installed if determined
necessary by the ECP Administrator.
Implementation Phase (I.C.3.c.3) – Phase I
Inspection Interval (I.D.6 and I.D.7) – Semi-Monthly and within 24 hours following
precipitation or snow melt
4.2.4 Wattle Dikes (Structural ‐ I.C.3.c.1)
Waddle Dikes will be used along Elizabeth Street during the construction process
to mitigate the transportation of sediment. Proper installation is the most important
aspect of waddle dikes. These protection measures function poorly if not installed
correctly, so the construction details provided with the plans must be followed.
Waddle Dikes will be installed where indicated on the Erosion Control Plan.
Implementation Phase (I.C.3.c.3) – Phase I
Inspection Interval (I.D.6 and I.D.7) – Semi-Monthly and within 24 hours following
precipitation or snow melt
4.2.5 Curb Inlet Protection (Structural ‐ I.C.3.c.1)
Existing curb inlets collect generated surface runoff and protection from sediment
transportation must be provided at each inlet. There are many different types of
curb inlet protection, but this report recommends gravel filters, which filter out
sediment and allow runoff to pass into the storm sewer system. The curb inlet
protection installation details can be found in Appendix C. The curb inlet
protection locations are identified on the Site Preparation & Erosion Control
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Plan. Although no curb inlet exists or will be installed on-site, the curb inlet
protection is used for protection at the sidewalk chase.
Implementation Phase (I.C.3.c.3) - Phase I
Inspection Interval (I.D.6 and I.D.7) - Semi-Monthly and within 24 hours following
precipitation or snow melt
4.2.6 Surface Roughening and Slope Protection (Non‐Structural ‐ I.C.3.c.2)
As grading alters the historic landscape, techniques must be utilized to reduce
the possibility of soil erosion. Surface roughening and slope protection techniques
help minimize soil erosion during construction and prior to mulching and re-
vegetation. The most commonly used technique is to drive over a sloped area
with a “tracked” vehicle so impressions run perpendicular to the slope (and
surface runoff). The roughened surface creates a series of small check dams
helping to slow surface runoff velocities and increase the flow length, both of
which help to minimize sediment transportation. Other possible techniques of
slope protection include installing silt fence at the top of a sloped area to prevent
large amounts of surface runoff from sheet flowing to the slope, grading in a
swale to catch sheet flow draining to the slope and re-directing the runoff to a
desired location, and installing straw wattle barriers perpendicular to runoff flow
paths. Due to the mild slopes present on sight, no slope protection is
anticipated for this project.
Implementation Phase (I.C.3.c.3) – N/A
Inspection Interval (I.D.6 and I.D.7) – N/A
4.3 Permanent BMPs
4.3.1 Surface Roughening/Mulching and Re‐Seeding (Non‐Structural ‐ I.C.3.c.2)
Once a construction site is reaching completion, areas of bare ground that have
not already been protected with surface roughening techniques, landscaping,
mulching, or re-seeding must receive this permanent treatment. This permanent
BMP is critical to preventing soil erosion during precipitation events and achieving
final stabilization. Surface roughening is expected once the final grades are
established.
Implementation Phase (I.C.3.c.3) - Phase V
Inspection Interval (I.D.6 and I.D.7) - Semi-Monthly and within 24 hours following
precipitation or snow melt
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4.3.2 Rain Gardens (Structural ‐ I.C.3.c.1)
A rain garden utilizes bioretention to reduce the transportation of pollutants to
downstream receiving waters through sedimentation, filtering, adsorption,
evapotranspiration, and biological uptake of constituents. The UDFCD provides
guidelines and tools for the design of rain gardens, which have been used for
the Elizabeth Subdivision project.
The City of Fort Collins LID ordinance requires that for 75% of all newly added
or modified impervious areas be treated by LID techniques. Based on
conversations with the City of Fort Collins Engineering Department, no LID systems
are required for the single family residence lot because the ongoing maintenance
and inspections by erosion control inspectors can be difficult on a private lot. For
that reason, only the new or modified impervious area on the commercial lot has
been considered for the requirement of 75% treatment by LID, although a portion
of the residential lot is also treated by the rain garden. A small portion of the
new or modified impervious area on the commercial lot flows directly to Elizabeth
Street and is therefore not treated by the rain garden. Table 4-1 shows how the
LID requirements have been met for this project.
Implementation Phase (I.C.3.c.3) - Phase II
Inspection Interval (I.D.6 and I.D.7) - Semi-Monthly and within 24 hours following
precipitation or snow melt
Table 4-1: LID Treatment
75% ON‐SITE TREATMENT BY LID FOR COMMERCIAL LOT
PROJECT AREA
TOTAL COMMERCIAL AREA (INCLUDING ROW) 10,162 SF
NEW COMMERCIAL IMPERVIOUS AREA 1,923 SF
REQUIRED MINIMUM AREA TO BE TREATED BY LID (75% OF NEW
COMMERCIAL IMPERVIOUS AREA) 1,442 SF
NEW IMPERVIOUS AREA TREATED BY RAIN GARDEN 1,752 SF
PERCENT OF NEW IMPERVIOUS AREA TREATED BY LID 91 %
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5 BMPs for Material Handling and Spill Prevention (I.C.3.c.4)
Section 3 of this report identifies possible pollutant sources that can be expected with the
construction of the Elizabeth Subdivision project. Material handling and spill prevention
information must be distributed to all contractors and subcontractors working at the construction
site. This information, along with response and notification procedures, must be in place prior
to construction and must be administered by the site superintendent.
Contractors should be instructed to notify the site superintendent and ECP Administrator
immediately if any spill occurs. The ECP Administrator will determine the nature of the spill
and, if necessary, contact the Colorado Department of Public Health and Environment (24-hour
spill reporting line – 877-518-5608), downstream water users, and any other agency or
jurisdiction deemed necessary.
For hazardous material or liquid storage, concrete truck washouts, and fueling and maintenance
locations, proper instructions for clean-up procedures should be posted and spill kit locations
should be identified. Information on absorbents should also be made available at all liquid
storage locations and fueling locations, and proper disposal locations for used absorbents
should be provided.
6 Final Stabilization and Ultimate Stormwater Management (I.C.4)
Final stabilization is the last step in the construction process and begins after major construction
activities have ended. The site superintendent should inspect the site one final time to ensure
that all temporary and permanent BMPs will function correctly in a precipitation event. If any
unpaved areas exist, all exposed or bare soil that has not previously been treated must be
identified and the appropriate procedure implemented to achieve final stabilization. This can
include re-seeding of the area with an approved seed mix, soil preparation, soil amendments,
where necessary, and soil stabilization methods such as crimped straw, hydro-mulch, or rolled
erosion control products. All areas that are re-seeded with drought tolerant grasses should
use a temporary irrigation system to promote the quick growth until the grasses have been
established. Final stabilization is achieved once all ground disturbing activities have been
completed and uniform vegetative cover has been established with an individual plant density
of at least 70% of pre-disturbance levels. Ultimate stormwater management is achieved
through the use of temporary BMPs until final site stabilization is achieved and the continued
maintenance and operation of the permanent BMPs installed on-site.
Elizabeth Subdivision
Erosion Control Report December 2016
Colorado Civil Group, Inc. 14
7 Construction Site Inspection and Maintenance (I.C.5, I.D.6, I.D.7)
Standard construction site inspection and maintenance schedules were identified in Section 4
for each of the anticipated temporary and permanent BMPs to be installed on-site. Part I.D.6.a
of the Stormwater Construction Permit requires that a thorough inspection of the stormwater
management system be performed and documented at least every 14 days and within 24
hours following any precipitation or snowmelt event that causes surface erosion. More frequent
inspections may be necessary and should be performed at the request of the ECP
Administrator. This report can be modified to provide any additional pollution controls or meet
increased inspection needs if deemed necessary. Standard site inspection procedures that
must be followed by the site superintendent are as follows:
The perimeter of the construction site must be inspected to ensure that no unintended
stormwater discharge is occurring.
All perimeter temporary and permanent BMPs must be inspected to ensure they are
functioning correctly and are in a condition that can reasonably be expected to function
appropriately in a future precipitation event.
Any disturbed areas should be inspected to determine if pollution is entering the
stormwater system and if any further controls should be implemented to better protect
the stormwater system.
All areas where construction site material is stored should be inspected for compliance
with this report. Areas should be checked for any spills that may have occurred
without being reported and should also be evaluated to determine if additional control
measures should be installed to prevent contamination. If necessary, these areas
should be checked to ensure that they are covered or protected from precipitation or
wind events.
All interior temporary and permanent BMPs should be inspected for performance and
should be replaced if found to be deficient.
The site superintendent should monitor the construction activities occurring on-site and
install approved controls as necessary even if those controls are not mentioned in this
report.
Elizabeth Subdivision
Erosion Control Report December 2016
Colorado Civil Group, Inc. 15
A log of each inspection should be kept on-site at all times and should be made
available upon request to any governing agency or jurisdiction, the Environmental
Protection Agency, or the Colorado Department of Public Health and Environment.
A log book may be kept for use in tracking other items related to the ECP such as those
listed below. Additional information such as dated photographs, field notebooks, drawings and
maps, and the items below, etc. can also be included where appropriate.
BMP operation and maintenance
Stormwater contamination
Contacts with suppliers
Notes on the need for and performance of preventive maintenance and other repairs
Implementation of specific items in the ECP
Training events (given or attended)
Events involving materials handling and storage
Contacts with regulatory agencies and personnel
Notes of employee activities, contact, notifications, etc.
This information can also be found in Part I.D.6 of the Construction Permit and should be
referenced often to ensure adequate inspection practices are followed.
Elizabeth Subdivision
Erosion Control Report December 2016
A
Appendix A: General Permit Application
Elizabeth Subdivision
Erosion Control Report December 2016
B
Appendix B: Existing Soil Information
Drainage Class—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 1 of 3
4491390 4491400 4491410 4491420 4491430 4491440 4491450 4491460 4491470 4491480 4491490 4491500
4491390 4491400 4491410 4491420 4491430 4491440 4491450 4491460 4491470 4491480 4491490 4491500
494640 494650 494660 494670 494680 494690 494700 494710 494720
494640 494650 494660 494670 494680 494690 494700 494710 494720
40° 34' 27'' N
105° 3' 48'' W
40° 34' 27'' N
105° 3' 44'' W
40° 34' 23'' N
105° 3' 48'' W
40° 34' 23'' N
105° 3' 44'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 25 50 100 150
Feet
0 5 10 20 30
Meters
Map Scale: 1:613 if printed on A portrait (8.5" x 11") sheet.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
Excessively drained
Somewhat excessively
drained
Well drained
Moderately well drained
Somewhat poorly drained
Poorly drained
Very poorly drained
Subaqueous
Not rated or not available
Soil Rating Lines
Excessively drained
Somewhat excessively
drained
Well drained
Moderately well drained
Somewhat poorly drained
Poorly drained
Very poorly drained
Subaqueous
Not rated or not available
Soil Rating Points
Excessively drained
Somewhat excessively
drained
Well drained
Moderately well drained
Somewhat poorly drained
Poorly drained
Very poorly drained
Subaqueous
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: http://websoilsurvey.nrcs.usda.gov
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
Drainage Class
Drainage Class— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
94 Satanta loam, 0 to 1
percent slopes
Well drained 0.4 53.0%
95 Satanta loam, 1 to 3
percent slopes
Well drained 0.4 47.0%
Totals for Area of Interest 0.8 100.0%
Description
"Drainage class (natural)" refers to the frequency and duration of wet periods under
conditions similar to those under which the soil formed. Alterations of the water
regime by human activities, either through drainage or irrigation, are not a
consideration unless they have significantly changed the morphology of the soil.
Seven classes of natural soil drainage are recognized-excessively drained,
somewhat excessively drained, well drained, moderately well drained, somewhat
poorly drained, poorly drained, and very poorly drained. These classes are defined
in the "Soil Survey Manual."
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Drainage Class—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 3 of 3
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 1 of 4
4491390 4491400 4491410 4491420 4491430 4491440 4491450 4491460 4491470 4491480 4491490 4491500
4491390 4491400 4491410 4491420 4491430 4491440 4491450 4491460 4491470 4491480 4491490 4491500
494640 494650 494660 494670 494680 494690 494700 494710 494720
494640 494650 494660 494670 494680 494690 494700 494710 494720
40° 34' 27'' N
105° 3' 48'' W
40° 34' 27'' N
105° 3' 44'' W
40° 34' 23'' N
105° 3' 48'' W
40° 34' 23'' N
105° 3' 44'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 25 50 100 150
Feet
0 5 10 20 30
Meters
Map Scale: 1:613 if printed on A portrait (8.5" x 11") sheet.
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: http://websoilsurvey.nrcs.usda.gov
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
Hydrologic Soil Group
Hydrologic Soil Group— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
94 Satanta loam, 0 to 1
percent slopes
B 0.4 53.0%
95 Satanta loam, 1 to 3
percent slopes
B 0.4 47.0%
Totals for Area of Interest 0.8 100.0%
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive precipitation
from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly
wet. These consist mainly of deep, well drained to excessively drained sands or
gravelly sands. These soils have a high rate of water transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well drained
soils that have moderately fine texture to moderately coarse texture. These soils
have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
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.
Rating Options
Aggregation Method: Dominant Condition
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 3 of 4
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 4 of 4
Wind Erodibility Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 1 of 3
4491390 4491400 4491410 4491420 4491430 4491440 4491450 4491460 4491470 4491480 4491490 4491500
4491390 4491400 4491410 4491420 4491430 4491440 4491450 4491460 4491470 4491480 4491490 4491500
494640 494650 494660 494670 494680 494690 494700 494710 494720
494640 494650 494660 494670 494680 494690 494700 494710 494720
40° 34' 27'' N
105° 3' 48'' W
40° 34' 27'' N
105° 3' 44'' W
40° 34' 23'' N
105° 3' 48'' W
40° 34' 23'' N
105° 3' 44'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 25 50 100 150
Feet
0 5 10 20 30
Meters
Map Scale: 1:613 if printed on A portrait (8.5" x 11") sheet.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
1
2
3
4
4L
5
6
7
8
Not rated or not available
Soil Rating Lines
1
2
3
4
4L
5
6
7
8
Not rated or not available
Soil Rating Points
1
2
3
4
4L
5
6
7
8
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at 1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil line
placement. The maps do not show the small areas of contrasting
soils that could have been shown at a more detailed scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov
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
Wind Erodibility Group
Wind Erodibility Group— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
94 Satanta loam, 0 to 1
percent slopes
5 0.4 53.0%
95 Satanta loam, 1 to 3
percent slopes
5 0.4 47.0%
Totals for Area of Interest 0.8 100.0%
Description
A wind erodibility group (WEG) consists of soils that have similar properties
affecting their susceptibility to wind erosion in cultivated areas. The soils assigned
to group 1 are the most susceptible to wind erosion, and those assigned to group
8 are the least susceptible.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Lower
Wind Erodibility Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 3 of 3
Wind Erodibility Index—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 1 of 3
4491390 4491400 4491410 4491420 4491430 4491440 4491450 4491460 4491470 4491480 4491490 4491500
4491390 4491400 4491410 4491420 4491430 4491440 4491450 4491460 4491470 4491480 4491490 4491500
494640 494650 494660 494670 494680 494690 494700 494710 494720
494640 494650 494660 494670 494680 494690 494700 494710 494720
40° 34' 27'' N
105° 3' 48'' W
40° 34' 27'' N
105° 3' 44'' W
40° 34' 23'' N
105° 3' 48'' W
40° 34' 23'' N
105° 3' 44'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 25 50 100 150
Feet
0 5 10 20 30
Meters
Map Scale: 1:613 if printed on A portrait (8.5" x 11") sheet.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Soil Rating Lines
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Soil Rating Points
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at 1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil line
placement. The maps do not show the small areas of contrasting
soils that could have been shown at a more detailed scale.
Please rely on the bar scale on each map sheet for map
Wind Erodibility Index
Wind Erodibility Index— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating (tons per acre
per year)
Acres in AOI Percent of AOI
94 Satanta loam, 0 to 1
percent slopes
56 0.4 53.0%
95 Satanta loam, 1 to 3
percent slopes
56 0.4 47.0%
Totals for Area of Interest 0.8 100.0%
Description
The wind erodibility index is a numerical value indicating the susceptibility of soil to
wind erosion, or the tons per acre per year that can be expected to be lost to wind
erosion. There is a close correlation between wind erosion and the texture of the
surface layer, the size and durability of surface clods, rock fragments, organic
matter, and a calcareous reaction. Soil moisture and frozen soil layers also
influence wind erosion.
Rating Options
Units of Measure: tons per acre per year
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Wind Erodibility Index—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 3 of 3
Elizabeth Subdivision
Erosion Control Report December 2016
C
Appendix C: Erosion Control Plan and Details
SF
SF SF SF SF SF SF SF SF SF SF SF SF SF SF SF SF
SF SF SF SF
SF
SF SF SF SF
SF
SF SF SF SF SF SF
SF SF SF SF SF
DATE REVISION DESCRIPTION
REVISIONS
FILENAME:
0036.0002.00_GRADING
0036.0002.00
1" = 20'
DECEMBER 2016
OF
DESIGNED:
CHECKED:
JOB NO.:
SCALE:
DATE:
SHEET NO.:
1" = 20'
0 20 40
scale feet
CALL THE UTILITY NOTIFICATION CENTER OF COLORADO
3 DAYS BEFORE YOU DIG
811 OR 1-800-922-1987
www.UNCC.org
CEM
CEM/JKG
5110 GRANITE STREET, UNIT D
LOVELAND, COLORADO 80538
(970) 278-0029
CCGCOLORADO
CIVIL
GROUP, INC.
ENGINEERING CONSULTANTS
0" 1" BAR IS ONE INCH ON ORIGINAL DRAWING
LAMAR VALLEY CRAFTSMAN
DATE DESCRIPTION
REVISIONS
0036.0002.00 GENERAL SHEETS
DECEMBER 2016
OF
DATE:
CCGCOLORADO
CIVIL
GROUP, INC.
ENGINEERING CONSULTANTS
SHEET:
N/A
SCALE:
0036.0002.00
JOB NO:
CEM
CHECKED:
CEM/JKG
DESIGNED:
FILE NAME:
0" 1" BAR IS ONE INCH ON ORIGINAL DRAWING
5110 GRANITE STREET, UNIT D
LOVELAND, COLORADO 80538
(970) 278-0029
DATE DESCRIPTION
REVISIONS
0036.0002.00 GENERAL SHEETS
DECEMBER 2016
OF
DATE:
CCGCOLORADO
CIVIL
GROUP, INC.
ENGINEERING CONSULTANTS
SHEET:
N/A
SCALE:
0036.0002.00
JOB NO:
CEM
CHECKED:
CEM/JKG
DESIGNED:
FILE NAME:
0" 1" BAR IS ONE INCH ON ORIGINAL DRAWING
5110 GRANITE STREET, UNIT D
LOVELAND, COLORADO 80538
(970) 278-0029
COLORADO CIVIL GROUP, INC. 1413 W. 29th Street Loveland, Colorado 80538 970-278-0029
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov
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 10, Sep 22, 2015
Soil map units are labeled (as space allows) for map scales 1:50,000
or larger.
Date(s) aerial images were photographed: Apr 22, 2011—Apr 28,
2011
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.
Wind Erodibility Index—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 2 of 3
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 10, Sep 22, 2015
Soil map units are labeled (as space allows) for map scales 1:50,000
or larger.
Date(s) aerial images were photographed: Apr 22, 2011—Apr 28,
2011
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.
Wind Erodibility Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 2 of 3
Survey Area Data: Version 10, Sep 22, 2015
Soil map units are labeled (as space allows) for map scales 1:50,000
or larger.
Date(s) aerial images were photographed: Apr 22, 2011—Apr 28,
2011
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.
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 2 of 4
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 10, Sep 22, 2015
Soil map units are labeled (as space allows) for map scales 1:50,000
or larger.
Date(s) aerial images were photographed: Apr 22, 2011—Apr 28,
2011
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.
Drainage Class—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
2/25/2016
Page 2 of 3