SW-II-FINAL
W-97-12
H.D.2.b3
ANALYSIS OF BEST MANAGEMENT PRACTICES
FOR SMALL CONSTRUCTION SITES
Work Performed for:
United States Environmental Protection Agency
Office of Wastewater Management
Washington, DC
Work Performed by:
United States Army Corps of Engineers
Chicago District
Chicago, EL
June 1998
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ANALYSIS OF BEST MANAGEMENT PRACTICES
FOR SMALL CONSTRUCTION SITES
Work Performed for:
United States Environmental Protection Agency
Office of Wastewater Management
Washington, DC
Work Performed by:
United States Army Corps of Engineers
Chicago District
Chicago, IL
June 1998
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INTRODUCTION 1
REVIEW OF AVAILABLE TECHNOLOGY 1
SOIL LOSS 1
GENERAL EROSION PROCESSES 1
Construction Impacts on Soil Loss 2
Evaluation of Impacts 2
RUSLE 3
RUSLE INPUT PARAMETERS 3
Rainfall Runoff Erosivity Factor, R 3
Soil Erodibility, K 5
Topographic Factor, LS 6
Cover Management Factor, C 7
Pre-Constniction Conditions 7
Construction Condition with No Best Management Practices 8
Construction Conditions with Best Management Practices 9
Support Practice Factor, P II
Development of Practice Factor in RUSLE 12
Sediment Delivery Ratio 12
MODELING OF EPA CONDITIONS 13
Pre-Construction 14
Construction 14
Construction Under Varying Individual Best Management Practices. 14
Seeding and Seeding Combined With Mulching 14
Straw Bales and Silt Fences 15
Sediment Traps, Earthen Dikes, Stone Check Dams and Stabilized Construction Entrances 15
Comparison of Individual Best Management Practices 16
Construction Under Combinations of Individual Best Management Practices 17
DISCUSSION OF RUSLE OUTPUT AND RESULTS 17
Pre-Construction and Construction Conditions 17
Construction with Best Management Practices 18
RUSLE CONCLUSIONS 19
AGNPS 20
AGNPS INPUT PARAMETERS 20
Watershed Data 20
Cell Data 21
Soil and Soil Cover Parameters. 21
Channel Data 22
AGNPS COMPUTATIONS 25
EPA COMBINATIONS TESTED IN AGNPS 25
DISCUSSION OF AGNPS OUTPUT AND RESULTS - 26
Individual Cell Erosion 27
Celt Deposition and Yield. 28
Watershed Deposition and Yield 30
AGNPS CONCLUSIONS 38
STUDY CONCLUSIONS AND RECOMMENDATIONS 38
REFERENCES 40
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LIST OF TABLES
TABLE TABLE
NUMBER TITLE
1 Rainfall Runoff Erosivity Values for 15 Climatic Zones of the United States
2 General Soil Characteristics for Three Soil Types
3 Topographic Factor, LS, Determination
4 Cover Management Factors for Pre-Constniction and Construction Conditions
5 Cover Management Factors for Best Management Practices
6 Comparison of C Values for Varying Construction Conditions
7 Effectiveness of Four Best Management Practices from EPA Documentation
S Matrix of Best Management Practice Combinations
9 Assumed AGNPS Channel Parameters
10 AGNPS Input Parameters for Pre-Constniction and Construction Conditions
11 Cells Where AGNPS Results are Reported
12 AGNPS Cell Erosion for Pre-Construction and Construction Conditions
13 AGNPS Upland Cell Deposition and Yield
14 Comparison of Sediment Yield at Watershed Outlet
15 Normalization of Increased Sediment Yield for Varying Construction Densities
16 AGNPS Reporting Cell and Construction Site Information
17 Increases in Sediment Yield at Watershed Outlet from Pre-Construction to Construction
Conditions
LIST OF FIGURES
FIGURE FIGURE
NUMBER TITLE
1 Fifteen Climatic Regions of the United States
2 Pre-Constmction Conditions RUSLE Soil Loss, Sandy Soils
3 Pre-Construction Conditions RUSLE Soil Loss. Clayey Soils
4 Pre-Construction Conditions RUSLE Soil Loss, Silty Soils
5 Construction Conditions RUSLE Soil Loss, Sandy Soils
6 Construction Conditions RUSLE Soil Loss, Clayey Soils
7 Construction Conditions RUSLE Soil Loss, Silty Soils
8 AGNPS Hypothetical Watershed
9 AGNPS 99 Acre Hypothetical Watershed
10 AGNPS 300 Acre Hypothetical Watershed
11 AGNPS 639 Acre Hypothetical Watershed
12 Sediment Yield Increase Due to 3 Acres of Construction on 99 Acre Watershed
13 Sediment Yield Increase Due to 15 Acres of Construction on 99 Acre Watershed
14 Sediment Yield Increase Due to 30 Acres of Construction on 99 Acre Watershed
15 Sediment Yield Increase Due to 3 Acres of Construction on 300 Acre Watershed
16 Sediment Yield Increase Due to 15 Acres of Construction on 300 Acre Watershed
17 Sediment Yield Increase Due to 30 Acres of Construction on 300 Acre Watershed
18 Sediment Yield Increase Due to 3 Acres of Construction on 639 Acre Watershed
19 Sediment Yield Increase Due to 15 Acres of Constmction on 639 Acre Watershed
20 Sediment Yield Increase Due to 30 Acres of Construction on 639 Acre Watershed
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LIST OF APPENDICES
APPENDIX APPENDIX
NUMBER TITLE
la RUSLE Results - Pre-Constniction Conditions
lb RUSLE Results - Construction Conditions with No Best Management Practices
lc RUSLE Results - Construction Conditions with Seeding and Seeding Combined With
Mulching
Id RUSLE Results - Construction Conditions with Straw Bales and Silt Fences
le RUSLE Results - Construction Conditions with Stone Check Dams and Sediment Traps
le RUSLE Results - Comparison of Pre-Construction, Construction and Construction with
Individual Best Management Practices
lg RUSLE Results - Construction Conditions with Combinations of Best Management
Practices Scenarios
2a AGNPS Results - Sediment Yield and Sediment Deposition
2b AGNPS Results - Comparison of Sediment Yield Increases
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INTRODUCTION
The Chicago District Corps of Engineers (Corps) was contracted by the Environmental
Protection Agency (EPA) to study the impacts of Best Management Practices on the
reduction of erosion generated from small construction sites. This work is part of the
EPA's ongoing development of the Phase II Stormwater regulations. Specifically, the
work completed by the Corps will be used to develop economic costs and benefits
associated with the proposed Phase II regulation.
In general, the scope of work specifies that erosion generated from small construction
sites (from one to five acres) will be determined under varying conditions; climatic, soil
type, soil cover type, land slope and under varying best management practices. In
addition, the EPA requested an analysis of transport of the eroded material from the site
and how the material travels through a hypothetical watershed subjected to varying
degrees of construction.
REVIEW OF AVAILABLE TECHNOLOGY
Upon receipt of the EPA request, the Corps began a search of available technology for use
in the analysis. Contacts with several agencies were made including: EPA, the Corp's
Waterways Experiment Station (WES), the Corp's Hydrologic Engineering Center
(HEC), Natural Resource Conservation Service (NRCS), and the Agricultural Research
Service (ARS). In addition, library and Internet searches were conducted to determine
available technology.
The EPA contacted the NRCS for assistance as well. A meeting between Mr. Glenn
Weesies, the NRCS liaison at Purdue University, and Corps representatives was held April
14 and 15, 1998. The meeting focused on the proposed study and how best to perform
the required analyses. NRCS contributed significantly in the development of the study
strategy as well as in the development of some key parameters. Based on the review of
literature as well as the contacts which were made, it was decided that the Revised
Universal Soil Loss Equation (RUSLE) would be used to quantify erosion of the
construction site and AGNPS, the agricultural non-point source model, would be utilized
as a comparative tool for studying the watershed transport analysis under varying
construction scenarios.
SOIL LOSS
GENERAL EROSION PROCESSES
Soil loss, or soil erosion, is the amount of soil moved by the action of wind and water.
The analysis undertaken for the EPA dealt with the erosive impacts of water. Erosion
includes the processes which displace soil particles from their position on the ground
surface. The amount of erosion is dependent on the soil type, the soil cover condition, the
slope length and steepness of the site under study, and the climatic region of interest. Soil
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which is lost to erosive processes may be transported by sheet flow in overland or interrill
areas or in small concentrated flows. These flows combine to form small channels and
streams whose size increases with increasing tributary area. Soil eroded from hillslopes
has the potential to deposit at the base of hills or to carry on to a receiving stream. The
downstream transport of soil which passes to a receiving stream is limited by the transport
capacity of the receiving streams.
Sediment yield is the amount of eroded soil that is delivered to a point in the watershed
that is remote from the origin of the detached soil particles. Sediment yield includes the
erosion from slopes and channels minus the sediment that is deposited after it is eroded
but before it reaches the point of interest. By knowing the soil loss and the sediment yield,
the sediment delivery ratio can be determined. This quantity gives an indication of the
amount of eroded material deposited within the watershed.
Construction Impacts on Soil Loss
The effects of construction lead to increases in soil loss due to the effects of site
preparation, surface stripping, grading operations, excavation activities and other
construction operations. These surface disturbances lead to increases in soil loss and the
potential for sediment deposition in receiving waters. Although short term erosion
impacts can be significant, implementation of Best Management Practices acts to minimize
the construction impacts both on-site and off-site.
Evaluation of Impacts
The processes described above were investigated as part of the EPA analysis. Soil loss for
180 pre-construction conditions was evaluated using the Revised Universal Soil Loss
Equation (RUSLE, version 5.0). RUSLE is an erosion model which predicts longtime
average annual soil loss resulting from raindrop splash and runoff from specified field
slopes under varying soil, cover and management conditions. Construction impacts were
then determined as well as impacts of implementing varying Best Management Practices.
Widespread use of RUSLE has substantiated its usefulness and validity as an erosion
model. Although primarily developed for agricultural uses, it is applicable to construction
sites. The RUSLE model with its wide range of applicability has proven to be a suitable
tool to capture the diversity of sediment yield across the continental United States.
Sediment yields and watershed depositional characteristics were evaluated using AGNPS
(version 5.0), an empirically based watershed runoff, erosion and pollution transport
model. These analyses are described below.
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RUSLE
The revised soil loss equation model (RUSLE), developed by ARS (a branch of the United
States Department of Agriculture (USDA)), is used to predict long term average annual
soil loss from field slopes. RUSLE evolved from the original Universal Soil Loss
Equation (USLE) as technology changed and the need to expand the use of the USLE
arose. The general equation remains the same but the parameters which enter the equation
are determined through a more detailed process. Because of this, the RUSLE model is
computerized with data developed through the use of built in databases. The following
states the RUSLE equation as well as a brief description of the required input parameters.
A=R*K*L*S*C*P
Where:
A:
computed average soil loss per unit of area,
R:
rainfall runoff erosivity factor.
K:
soil erodibility factor,
L:
slope length factor,
S:
slope steepness factor,
C.
cover-management factor,
P:
support practice factor.
Mr. Glenn Weesies, a conservation agronomist with the USDA-NRCS, was instrumental
in the development of the RUSLE computer model and was retained by EPA for the Best
Management Practice analysis. Mr. Weesies developed a RUSLE database specific to the
EPA analysis and forwarded the RUSLE model and the associated database to the
Chicago District Corps of Engineers. The parameters contained in the EPA database are
described below.
RUSLE INPUT PARAMETERS
Rainfall Runoff Erosivity Factor , R
The rainfall runoff erosivity factor quantifies the effect of raindrop impact and the amount
and rate of runoff likely to be associated with rain. As such, this factor is subject to the
various climatic regions across the United States. The R factor is the average annual total
of the storm EI values, a statistical interaction term which reflects how total energy and
peak intensity are combined in each particular storm and thus relates to how particle
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detachment is combined with transport capacity. Refer to Agriculture Handbook Number
703 for additional details regarding the R and EI factors.
Originally, the work specified by EPA included an analysis of varying return frequency
rainfall events and determining the impacts that these storms had on the erosion at the
construction sites under study. It was recognized that return frequency events vary across
the nation and no one storm would be applicable. Because of this it was decided that the
variability of climatic conditions across the United States would be investigated. In
addition, it was determined that the loss of soil in response to individual events was not a
critical component of the study but rather a determination of average annual soil loss was
a more useful, and more defensible, component. The RUSLE model is generally limited to
the development of average annual sediment loss.
The R factor in the RUSLE takes into account the average rainfall-runoff process, the
seasonal variability of the rainfall-runoff process as well as the intensity effects of
particular storms. The RUSLE program integrates the seasonal variations of these values
in the calculation of the K and C parameters thus recognizing the inter-relation of rainfall
intensity on soil erodibility, soil cover efficacy as well as practice management efficacy
during varying times of the year. The RUSLE program also uses the 10 year EI value in
the determination of P, the support practice factor. This allows the model to give varying
levels of credit to the support practice depending on the energy and intensity of rain that
the support practice would be subjected to during a 10 year frequency storm.
Mr. Weesies, of the USDA-NRCS, was instrumental in choosing appropriate climatic
regions for the present study. Fifteen areas were chosen to represent the varying climatic
conditions across the United States. These areas and their representative cities are
detailed in table 1 and shown in figure 1. Although it is recognized that the climate zones
indicated below do not fully represent conditions throughout the U.S., the zones were
necessarily limited in keeping with the goals and time constraints of the project. The cities
selected are intended to represent a range in the amount, intensity and seasonal
distribution of rainfall. The cities are representative of Land Resource Regions in
Agriculture Handbook 296.
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Table 1. Rainfall Runoff Erosivity Values for 15 Climatic Zones of the United States
Climatic Region
City
State
R
10 year EI
Hartford
Duluth
Las Vegas
Charleston
Bismarck
Helena
Atlanta
Denver
Boise
Nashville
Amarillo
Portland
Des Moines
San Antonio
Fresno
Connecticut
Minnesota
Nevada
South Carolina
North Dakota
Montana
Georgia
Colorado
Idaho
Tennessee
Texas
Oregon
Iowa
Texas
California
130
95
8
400
50
14
295
40
12
225
100
65
160
250
12
70
70
18
190
50
14
140
40
12
90
110
18
90
150
10
Soil Erodibility, K
The soil erodibility factor, K, is the rate of soil loss per rainfall erosion index unit as
measured on a unit plot. Soil erodibility is related to the integrated effects of rainfall,
runoff and infiltration on soil loss. The soil erodibility is also subject to seasonal effects of
storm energy and intensity
As specified in the EPA request, three different soil types were to be investigated in the
analysis of the construction site impacts. Originally, the EPA scope specified sand, silt and
clay as the three soil types. Although it is highly unlikely that a single soil type would be
present on a construction type, this was a necessary assumption due to the time limits of
the study. Discussions between the EPA and NRCS concluded that three K factors would
be used to represent soils of varying erodibility characteristics, and would include a soil
with low erodibility, one with moderate erodibility and one with high erodibility. Further
description of the three soil types was provide within a fax, dated 14 April 1998, from the
NRCS. The values stated were for undisturbed conditions. Additional values were
provided by NRCS to assess soil conditions during construction operations and were
transmitted by Mr. Weesies via an e-mail message. Different K values were assumed
during construction under the assumption that typical construction activities may involve
major excavation which removes one or more soil horizons and/or may involve heavy
earthmoving equipment which may compact the soil. Both impacts effect the soil
erodibility. K factors under a construction condition are appropriately modified based on
recommendations from USDA-ARS and NRCS and reflect a 25 percent increase over
undisturbed K values. Table 2 summarizes the assumed soils and their soil erodibility
values under pre-construction and construction conditions.
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Table 2. General Soil Characteristics for Three Soil Types
Soil Hydraulic
Soil Texture
K
Soil Erodibility Conductivity
Permeability
Classification
Factor
Pre-Construction Condition (Undisturbed)
1 Low High
Rapid
Sandy in surface and
0.10
subsurface layers.
2 Moderate Moderately
Moderately
Clay Loam
0.27
Low
Slow
3 High Low
Slow
Silt Loam
0.64
High Silt Fraction
Construction Condition (Disturbed)
1 Low High
Rapid
Sandy in surface and
0.12
subsurface layers.
2 Moderate Moderately
Moderately
Clay Loam
0.34
Low
Slow
3 High Low
Slow
Silt Loam
0.80
High Silt Fraction
Topographic Factor, LS
The topographic factor, LS, is determined based on a consideration of the length of the
slope in question and the steepness of the slope in question. The slope length is defined as
the horizontal distance from the origin of overland flow to the point where either the slope
gradient decreases enough that deposition begins or runoff becomes concentrated in a
defined channel. The slope length factor, L, is determined through a relation between the
slope length and a RUSLE unit plot length (72.6 feet). The slope steepness factor, S,
accounts for the influence of slope gradient on erosion and is determined through a
relation between the slope gradient and a RUSLE plot at a 9% gradient. The LS factor is
not the product of the slope length and slope gradient, but rather, it represents the ratio of
soil loss on a given slope length and steepness to soil loss from a slope that has a length of
72.6 feet and a steepness of 9%.
The topographic factor used in the RUSLE program considers several aspects of the field
under study. As indicated above, the analysis was limited to 1 acre, 3 acre and 5 acre sites
at varying slopes ranging from mild slopes to very steep slopes. It should be understood
that RUSLE predicts soil loss from a hill slope. Based on conversations with Mr.
Weesies, USDA-NRCS, it was recognized that given a particular hill slope, there is an
associated limiting slope length. RUSLE slope gradients and corresponding slope lengths
were taken from guidelines in an unpublished table titled, "Default Slope Length For Each
Increment of Slope Steepness For Use in All Areas of the U.S. Except the 'Palouse,'" by
D.T. Lightle and G.A. Weesies. Four slope gradients were chosen by NRCS to represent
expected slopes across the U.S. For each chosen slope the corresponding slope length is
detailed in table 3.
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Table 3. Topographic Factor, LS, Determination
Slope
Slope Steepness
Slope Length
LS
Description
(Percent)
(feet)
Topographic Factor
Flat
3
200
0.48
Rolling
7
140
1.06
Steep
12
100
1.79
Very Steep
18
50
1.98
Again, the RUSLE model only predicts the erosion processes that occur off the hill slope
over the slope lengths defined in table 3. Depending on the cell size, one or more of these
representative hill slopes can be present. Other processes will occur after the hill slope
erosion computation, including possible deposition at the base of the hill slope, additional
erosion to the edge of the construction site and transport of eroded material to a receiving
stream. The AGNPS model was used to account for processes which occur subsequent to
the RUSLE computations of hill slope erosion.
Cover Management Factor, C
The cover management factor, C, accounts for the effect of cropping and management
practices on erosion rates. The C factor reflects how varying management practices
impact the average annual soil loss and how soil loss potential is distributed over time
during construction activities - in the case of the EPA analysis. The development of the C
factor includes the consideration of the time variability of the cover management condition
over a year and the EI factor at that corresponding time. A yearly period is broken up into
24 periods of 15 day increments. For each 15 day increment, information to define the
following is required: the prior landuse, the canopy cover, the surface cover, the soil
moisture and the average EI value for that 15 day period.
Pre-Construction Conditions
Based on discussions with NRCS representatives, the chosen C factors would reflect two
conditions, pre-construction and during construction. The pre-construction condition
would be reflective of a field site which had previously been farmed and then taken out of
farming prior to a construction condition. Conversations with Mr. Roger Nanney, an
NRCS representative working with EPA (Region V), indicated that this should reflect a
majority of conditions experienced. The factors required for determination of a C value
were provided by Mr. Weesies. The assumptions for the pre-construction condition
included a prior landuse of a 3-year rotation of a high residue crop (corn with
conventional tillage), a surface cover of a low residue crop (soybeans with conventional
tillage) and a canopy cover of first-year hay/pasture condition. This is the assumed field
condition prior to a construction condition.
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Construction Condition with No Best Management Practices
Under the construction scenario, different assumptions were used to represent the
disturbance to the fallow soils due to varying construction operations. The NRCS
assumptions for the construction condition include: a full year of construction operation
occurs where the first six months are under a disturbed condition and the soil during the
last six months is bare and idle. Results under this condition can be modified as
construction conditions for these small sites are likely to last only half of a year, the agreed
upon average duration of construction based on conversations with EPA Headquarters.
A series of C factor databases were developed by Mr. Weesies to represent conditions
described above. As indicated previously, the determination of the C factor depends not
only on the temporal variation of the soil and cover conditions but also on the regional and
temporal EI values. The RUSLE model links the chosen cover condition (pre-
construction or construction) to the EI value appropriate to the region under study. The
soil conditions, cover conditions and EI values are determined over the 24 - 15 day
periods in the year to come up with a comprehensive average annual C value.
As recommended by NRCS, two of the 15 regional climatic zones, detailed in table 1,
were handled differently due to when the greatest storm intensities occurred during the
year. Both Fresno, California and Portland, Oregon were assumed to experience their
peak storm intensities during the winter. Because of this, the database describing their
cover management condition linked their most vulnerable cover management condition to
coincide with the period of greatest storm intensity, their winter season. The thirteen
other climatic locations had their greatest storm intensity occurring in the summer season.
This methodology ensured that a worst case scenario was developed for the pre-
construction condition. Resultant C factors are presented in table 4 for the various
conditions tested. A review of the values in table 4 shows that the C factor for pre-
construction conditions ranged from 0.03 to 0.36. For construction conditions the C
factors were fairly consistent ranging from 0.81 to 0.92 for all 15 climatic regions. This
equates to a minimum 140 percent increase from pre-construction conditions in San
Antonio, Texas and a maximum 2,210 percent increase for construction conditions in Las
Vegas, Nevada. Because there is a linear relationship between C and the resultant soil loss
predicted from RUSLE, the percent increase in C results in the same percent increase in
soil loss from the hill slope - assuming all other RUSLE factors are equal.
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Table 4. Cover Management Factors for Pre-Construction and Construction Conditions
w —
Pre-Construction
Construction
Climatic Region
Cover Management Factor
Cover Management
C
C
Hartford, Connecticut
0.283
0.878
Duluth, Minnesota
0.225
0.873
Las Vegas, Nevada
0.035
0.809
Charleston, South Carolina
0.359
0.917
Bismarck, North Dakota
0.206
0.844
Helena, Montana
0.160
0.827
Atlanta, Georgia
0.340
0.898
Denver, Colorado
0.214
0.841
Boise, Idaho
0.143
0.818
Nashville, Tennessee
0.340
0.891
Amarillo, Texas
0.298
0.859
Portland, Oregon
0.228
0.864
Des Moines, Iowa
0.309
0.885
San Antonio, Texas
0.361
0.877
Fresno, California
0.113
0.822
Construction Conditions with Best Management Practices
Two of the Best Management Practices specified for analysis by the EPA were the use of
seeding and mulching at construction sites. The RUSLE model was well suited for
modeling these conditions and determining the potential for reducing soil loss off of
construction sites resulting from implementing these measures. Again, Mr. Weesies
developed the necessary database to model two conditions: seeding, and seeding
combined with mulching. The determination of the C value is identical to that described
above but the temporal soil condition was modified to reflect a construction condition
which undergoes seeding or seeding and mulching. Where mulching was assumed to
indicate straw mulch applied at one ton per acre. The resultant C values for all four
conditions (pre-construction, construction, construction with seeding and construction
with seeding and mulching) are presented in table 5. Comparisons between the four
conditions are presented in table 6.
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Table 5. Cover Management Factors for Best Management Practices
Cover Management Factors, C
Pre- Best Management Practice
Climatic Region
Construction
Construction
Seeding and
Condition
Condition
Seeding
Mulching
Hartford, Connecticut
0.283
0.878
0.440
0.261
Duluth, Minnesota
0.225
0.873
0.666
0.362
Las Vegas, Nevada
0.035
0.809
0.458
0.139
Charleston, South Carolina
0.359
0.917
0.546
0.295
Bismarck, North Dakota
0.206
0.844
0.655
0.345
Helena, Montana
0.160
0.827
0.655
0.379
Atlanta, Georgia
0.340
0.898
0.578
0.385
Denver, Colorado
0.214
0.841
0.697
0.365
Boise, Idaho
0.143
0.818
0.567
0.442
Nashville, Tennessee
0.340
0.891
0.538
0.408
Amarillo, Texas
0.298
0.859
0.573
0.408
Portland, Oregon
0.228
0.864
0.263
0.219
Des Moines, Iowa
0.309
0.885
0.643
0.451
San Antonio, Texas
0.361
0.877
0.536
0.434
Fresno, California
0.113
0.822
0.251
0.202
Table 6. Comparison of C Values for Varying Construction Conditions
% Increase Over
% Decrease From
Climatic Region
Pre-Construction Condition
Construction Condition
Seeding+
Seeding+
Constr.
Seeding
Mulching
Seeding
Mulching
Hartford, CN
210
55
-8
50
70
Duluth, MN
288
196
61
24
59
Las Vegas, NV
2211
1209
297
43
83
Charleston, SC
155
52
-18
40
68
Bismarck, ND
310
218
67
22
59
Helena, MT
417
309
137
21
54
Atlanta, GA
164
70
13
36
57
Denver, CO
293
226
71
17
57
Boise, ED
472
297
209
31
46
Nashville, TN
162
58
20
40
54
Amarillo, TX
188
92
37
33
53
Portland, OR
279
15
-4
70
75
Des Moines, IA
186
108
46
27
49
San Antonio, TX
143
48
20
39
51
Fresno, CA
627
122
79
69
75
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Support Practice Factor, P
The support practice factor is the ratio of soil loss with a specific support practice to the
corresponding loss with upslope and downslope tillage. Support practices are those which
effect erosion by modifying the flow pattern, grade or direction of surface runoff and by
reducing the amount and rate of runoff. The support practices considered in the RUSLE
modeling for the EPA Best Management Practice analysis included: straw bales and silt
fences. No support practices were assumed for the pre-construction and construction
without Best Management Practices conditions.
In general, the P factor will be equivalent to 1.0 under the pre-construction condition.
Under a construction condition with no Best Management Practices in place it is assumed
that the P factor will remain equal to 1.0. The P factor will vary greatly under
construction operations depending on which best management practice is utilized and will
always be reduced to a value below 1.0 - thus indicating a reduction of soil loss off the hill
slope. In the RUSLE modeling, the Best Management Practices tested were placed at the
base of the RUSLE hill slope. Only the straw bale and silt fence BMP methods were
directly tested in the RUSLE model to determine their effects on the P factor
NRCS created the necessary database to include the straw bale and silt fence BMP
methods. Each BMP method represents a separate impact analysis, that is, a combination
was not evaluated in the RUSLE model. As mentioned earlier, the effectiveness of the
BMP is related to the physical measure itself as well as the intensity of the 10 year
•frequency rainfall EI value to which it may be subjected. The developed P factor takes
these two factors into account by comparing the general BMP effectiveness to the regional
climate in which it is placed. Although the straw bales and silt fence methods are not
explicitly defined in the RUSLE model, NRCS developed an approach to modeling them.
For both cases, the BMP was modeled by assuming an effective strip cropping buffer at
the base of the RUSLE hill slope. The length of the strip cropping buffer varied based on
the BMP under study as well as the slope characteristics of the construction site. Table 6
summarizes these assumptions.
Table 6. Effective Strip Cropping Buffer Widths for Best Management Practice Analysis
Minimum Strip Width for Best Management Practice
Slope
Slope Length
(Expressed as a Percent of the
RUSLE Hill Slope Length *)
(Expressed in Feet at the Bottom
of the RUSLE Hill Slope)
(%)
(feet)
Straw Bales
Silt Fences
Straw Bales
Silt Fences
3
200
8%
15%
16 feet
30 feet
7
140
5%
10%
7 feet
14 feet
12
100
5%
10%
5 feet
10 feet
18
50
3%
5%
1.5 feet
2.5 feet
*Values taken from correspondence (fax) between NRCS offices (September 18, 1997).
11
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Development of Practice Factor in RUSLE
The RUSLE model provides several pieces of information relative to the computation of
the final support practice factor P. As part of the computation, the RUSLE model allows
the user to define contouring, terracing, subsurface drainage as well as strip cropping
characteristics. The contouring and strip cropping practices were modified to reflect
conditions with construction and straw bales or silt fences in place. The contouring effects
would be related to the construction equipment on the site and the resultant tire tracks and
general earth moving. The strip cropping effect is related solely to the straw bale or silt
fence placed at the bottom of the hill slope.
The contouring was defined by specifying the slope of the hill, the hydrologic soil class,
information regarding the cover management and a small ridge height to reflect tire tracks
running perpendicular to the slope. With these values as input, the RUSLE model
generates a composite P factor associated with the contouring of the site.
Next, the user defines factors associated with the strip cropping to represent the straw
bales or silt fences. The P factor associated with the strip cropping is based on the slope
of the hill, the length of the hill and the minimum strip width (in the direction of the hill
slope) of the Best Management Practice (taken from table 6). The RUSLE model
generates a composite P factor associated with the strip cropping, or BMP placement for
this analysis, on the site.
The final support practice factor, P, is then generated by accounting for both the
contouring and strip cropping practices. The P factor for the contouring practice is
multiplied by the P factor for the strip cropping practice to develop a composite P factor.
The composite P factor, a value less than 1.0, represents the credit given to the support
practices in place - the straw bales and silt fences in the EPA analysis.
Sediment Delivery Ratio
In the computation of the strip cropping support practice factor, P, the RUSLE model
takes into account the physical location of the support practice on the hill slope. Support
practices located at the bottom of the slope, as in the BMP analysis, are given little credit
and thus receive a higher P factor resulting in greater soil loss. The degree of credit,
reflected in the P value, increases as the location of the deposition, due to the presence of
the support practice, moves up the slope. This is consistent with conservation planning
goals of minimizing the loss of soil from a hill slope and minimizing the relocation of that
soil if it is eroded. In summary, a single support practice located at the bottom of a hill
slope will have a higher P factor than a support practice, or practices, located along the
slope.
As defined above, the strip cropping P factor is computed with conservation planning
goals in mind. The goals of implementing Best Management Practices on construction
sites is different in that the ultimate goal is to prevent or minimize the transport of eroded
12
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soil off the construction site itself. That is, placement of Best Management Practices on a
construction site is not necessarily targeted toward retaining lost soil within a localized
zone from its point of displacement. The goal is to keep that lost soil, to the extent
possible, on the construction site so as to avoid offsite problems. This differs from the
agricultural goals of soil conservation, specifically, maintaining soils within their zone of
origin so as not to deplete the soil resource. Because of this difference, the RUSLE model
offers an adjustment to the strip cropping P factor to give more credit to the straw bales
and silt fences as they are meeting the ultimate goal of the construction site, minimizing
off-site transport of eroded soil. This adjustment is achieved through the use of the
RUSLE defined sediment delivery factor. The sediment delivery factor (which is always
less than ] .0) is multiplied by the other RUSLE variables (R, K, LS, C) to determine a
sediment passing the straw bale or silt fence at the base of the RUSLE hill slope. Based
on conversations with NRCS it was felt that the sediment delivery factor would be more
applicable to construction sites than using the RUSLE computed P factors. The resultant
value is not the soil loss off of the RUSLE hill slope, but rather the sediment delivered off
of the hill slope.
In summary, the Revised Universal Soil Loss Equation is used to predict soil loss, A, off
of a hill slope. Applying the sediment delivery factor for the strip cropping practice to the
equation results in a new product, the sediment delivered off of the RUSLE hill slope.
Where the sediment delivered is the amount of soil that leaves the field slope and is less
than the overall soil loss from the hill slope due to the presence of the straw bales or silt
fences.
MODELING OF EPA CONDITIONS
The scope of work for the present study specified that several conditions would be
analyzed in order to assess the benefits of implementing Best Management Practices on
small construction sites. The conditions which were analyzed included:
a) Pre-Construction
b) Construction
c) Construction Using Best Management Practices
Seeding
Seeding and Mulching
Straw Bales
Silt Fences
Sediment Traps
Stone Check Dam
As discussed previously, the RUSLE model was used to evaluate pre-construction and
construction conditions as well as the impacts of the first four best management practices
listed above (seeding, seeding and mulching, straw bales and silt fences). The sediment
traps, guidewalls/earthen dike and stone check dam Best Management Practices were
accounted for by applying efficiency factors provided by EPA based on their research.
13
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AJ1 soil loss quantities (and sediment delivery quantities, where appropriate) for the
conditions listed above are detailed in Appendix 1. The end product of the RUSLE is a
soil loss value, A, expressed in average annual tons of soil loss per acre. Because the sites
of EPA concern range from 1 to 5 acres, the values from the RUSLE model were loaded
into a spreadsheet to determine quantities of soil loss for the particular sizes of sites.
Again, the RUSLE analysis gives an indication of the soil loss from a hill slope, not the
amount that leaves the construction site itself.
Pre-Construction
RUSLE was used to determine the average annual hill slope soil loss, A, for pre-
construction conditions under the following combinations:
a) 3 Soil Types (low erodibility, moderate erodibility and high erodibility),
b) 4 Slope Types (flat, rolling, steep and very steep), and
c) 15 Climatic Regions
The total number of pre-construction combinations tested using RUSLE was 180 (3*4*15
= 180). The Revised Universal Soil Loss Equation was solved using the R values detailed
in table 1, the K values from table 2, the LS values from table 3 and the C values from
table 4. The P factor in the equation was assumed equal to 1.0 under the pre-construction
conditions. Soil loss results from the pre-construction conditions analysis are contained in
Appendix la. Average annual soil loss values in Appendix la are expressed in units of
tons per acre.
Construction
As with the analysis of pre-construction conditions, 180 combinations were analyzed for
the construction condition. The only variables which changed from the pre-construction
analysis were the soil erodibility factor, K, and the cover management factor, C. It was
assumed that the P factor remained equal to 1.0 under construction conditions with no
Best Management Practices in place. The construction K factors were determined by
multiplying the pre-construction K factor by 1.25. The construction condition C factor
was determined as described in the appropriate section above and is summarized in table
4. Soil loss results from the construction conditions analysis are contained in Appendix
lb. Average annual soil loss values in Appendix lb are expressed in units of tons per acre.
Construction Under Varying Individual Best Management Practices
Seeding and Seeding Combined With Mulching
The impacts of the seeding and seeding combined with mulching Best Management
Practices are directly related to the change in the cover management factor, C. Cover
management factors were developed for both seeding and seeding combined with
14
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mulching conditions for each of the 15 climatic regions. These values were presented in
table 5. The C factors resulting from these Best Management Practices were then
multiplied by the original R and LS values as well as the construction modified K value to
determine the soil loss under a construction condition with seeding or seeding and
mulching in place. Hill slope soil loss results are summarized in Appendix lc. Average
annual soil loss values in Appendix lc are expressed in units of tons per acre.
Straw Bales and Silt Fences
The impacts of the straw bales and silt fences Best Management Practices are directly
related to the change in the support practice factor, P. Sediment delivery factors were
determined by RUSLE for both the straw bales and silt fences conditions under the
varying soil, slope and climatic conditions. The resultant sediment delivery factors for
these two Best Management Practices were multiplied by the original R and LS values as
well as the construction modified K and C values to determine the sediment delivered off
of the RUSLE hill slope for the straw bales and silt fences conditions. The sediment
delivery results are presented in Appendix Id. Average annual sediment delivery values in
Appendix Id are expressed in units of tons per acre.
Sediment Traps, Earthen Dikes, Stone Check Dams and Stabilized Construction Entrances
These four Best Management Practices were also specified for analysis. A review of the
RUSLE model by USACE-Chicago District and Mr. Weesies of the NRCS determined
that the RUSLE model may not be appropriate for analyzing the sediment traps or earthen
dikes. RUSLE was originally thought to be able to handle these practices by modeling
them using the terrace option in RUSLE. A review of the preliminary results indicated
that these practices resulted in very low P factors and it was thought that they may have
been assigned too much credit for sediment trapping. Because it was unclear if the
agricultural definition of terracing was compatible with the sediment traps and earthen
dikes used in construction it was decided that these best management practices would be
analyzed outside of the framework of RUSLE. The analysis of stone check dams and
stabilized construction entrances was considered outside of the RUSLE model as well.
The effectiveness of these four Best Management Practices, shown in table 7, were
provided by EPA based on their review of National Association of Home Builders
(NAHB) documentation. The analysis of these practices was necessarily limited to
applying a factor (less than 1.0) to represent the sediment delivery factor of the Best
Management Practice. The following table, developed from information provided by
EPA, summarizes these adopted factors, where the EPA efficiency factor is an indication
of how effective the BMP is at removing sediment. For example, a stone check dam has
an efficiency factor of 0.7 indicating that it removes approximately 70 percent of the
sediment to which it is exposed. The sediment delivery factor is an indication of what
percentage of total sediment passes the BMP. For example, a stone check dam delivers or
yields 30 percent of the sediment to which it is exposed.
15
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As shown in table 7, the stabilized construction entrance and the earthen dike have
sediment delivery factors of 1.0 - indicating no relative impact on controlling erosion.
Based on conversations with EPA it was determined that the use of a stabilized
construction entrance is a valid Best Management Practices for minimizing the transport
of eroded material to adjacent streets used as haul routes and to the street's storm sewers.
But, the stabilized construction entrances did not play a large role in reducing down slope
erosion - the focus of the present analysis. Similarly, the intent of the earthen dike is to
direct flows to the sediment trap at the base of the hill slope. Because of this, the earthen
dike on its own was not given credit for reducing down slope erosion.
Table 7. Effectiveness of Four Best Management Practices from EPA Documentation
Best Management Practice
EPA
Sediment
Efficiency Factor
Delivery Factor*
** Stabilized Construction Entrance
n.a.
1.0
Stone Check Dams
0.7
0.3
** Earthen Dikes
n.a.
1.0
Sediment Traps
0.6
0.4
* Sediment Delivery Factor = (1 - EPA Efficiency Factor)
** Both stabilized construction entrances and earthen dikes were considered to have
minimal impact on computed sediment yield values based on conversations with EPA.
For this reason, their impacts were not included in the spreadsheet analysis and are not
presented in the Appendix le, If or lg results.
The sediment delivery factors defined in table 7 were applied directly to the soil loss
values computed for the construction conditions with no Best Management Practices in
place. The resultant sediment delivery values for the stone check dam and sediment trap
Best Management Practices are presented in Appendix le. Average annual sediment
delivery values in Appendix le are expressed in units of tons per acre.
Comparison of Individual Best Management Practices
The average annual soil loss and sediment delivery quantities for each of the Best
Management Practices described above are summarized in Appendix If. This appendix
allows for a quick comparison of individual Best Management Practices to pre-
construction conditions and construction conditions with no Best Management Practices.
As can be seen in the next section, the use of only one Best Management Practice is not
likely except on 1 acre construction sites on flat sloped (3%) sandy soil conditions. For all
other construction sites a combination of Best Management Practices is used to control
soil loss impacts due to construction. The values presented in Appendix If are intended to
be used as a simple means of comparing the relative impacts of the individual Best
Management Practices analyzed as part of this study.
16
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Construction Under Combinations of Individual Best Management Practices
In addition to analyzing the impacts of individual Best Management Practices the
combined impacts of varying Best Management Practices were analyzed. The EPA
forwarded several matrices of probable Best Management Practice combinations that
would be expected for varying size sites and for varying slope and soil conditions. The
final Best Management Practice matrix is presented in table 8.
Table 8. Matrix of Best Management Practice Combinations
Construction
Soil
Slope of Site
Site Size
Erodibility
3%
7%
12%
18%
1 acre
Low
a
a, b
a, c, e
c, e, f, g
1 acre
Moderate
a, b
a, c, e
a, c, e
c, e, f, g
1 acre
High
a, c, e
a, c, e
c, e, f, g
c, e, f, g
3 acres
Low
a, b
a, c, e
c, d, e, f, g
c, d, e, f, g
3 acres
Moderate
a, c, e
a, c, e
c, d, e, f, g
c, d, e, f, g
3 acres
High
a, c, e
c, d, e, f, g
c, d, e, f, g
c, d, e, f, g
5 acres
Low
a, c, d, e
c, d, e, f, g
c, d, e, f, g
c, d, e, f, g
5 acres
Moderate
a, c, d, e
c, d, e, f, g
c, d, e, f, g
c, d, e, f, g
5 acres
High
c, d, e, f, g
c, d, e, f, g
c, d, e, f, g
c, d, e, f, g
LEGEND:
(a) Silt Fence
(b) Mulch*
(c) Seed and Mulch
(d) Stabilized Construction Entrance**
(e) Stone Check Dam
(f) Earthen Dike Directing Runoff to Sediment Trap**
(g) Sediment Trap (1,800 cu-ft/acre * Site Size (acres))
* modeled as seed and mulch in RUSLE as per conversations with EPA
** not considered in spreadsheet analysis as per conversations with EPA
The results of the construction conditions using the combinations of Best Management
Practices shown in table 8 are presented in Appendix lg. Average annual sediment
delivery values in Appendix lg are expressed in units of tons.
DISCUSSION OF RUSLE OUTPUT AND RESULTS
Pre-Construction and Construction Conditions
The pre-construction and construction conditions RUSLE average annual soil loss results
were plotted for the 15 climatic zones, three soil types and four slope conditions which
were studied. These results are presented in figures 2 through 7 using the data which was
17
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presented in Appendices la and lb. These figures are useful in quickly assessing the
regional differences between soil loss under similar soil and slope conditions. It is clear
from these figures that even under equivalent slope and soil conditions, average annual soil
loss can vary considerably across the United States due to the rainfall and erosivity
parameters associated with that region.
In addition, figures 2 through 7 can be used to draw threshold limits of tolerable soil loss
values. For example, if new regulations state that an average annual soil loss of 2 tons per
acre is tolerable, these figures can be referenced to determine which climatic zones under
which soil and slope conditions would meet that criteria. Curves of this type could be
useful for justifying exemptions to the new regulations if the proposed construction were
within particular climatic zones and certain slope and soil conditions were met.
Construction with Best Management Practices
The information presented in Appendices la through le is based on an analysis of the
impacts of individual Best Management Practices in controlling soil erosion due to
construction. Appendix If allows for a quick comparison of the individual impacts of all
of the Best Management Practices tested to pre-construction and construction conditions
with no Best Management Practices in place. A quick review of the table shows the check
dam has the greatest impact on reducing soil loss off of the RUSLE hill slope. This is true
for all climatic regions studied.
Finally, results presented in Appendix lg combine the appropriate Best Management
Practices according to site size, soil type and slope type (as defined in table 8). The EPA
recommended Best Management Practice combinations are analyzed for 1 acre, 3 acre and
5 acre construction sites. The results presented in Appendix lg provide for some
interesting conclusions.
For all one acre flat (3% slope), sandy sites the recommended Best Management Practice
is a silt fence. For all climatic regions tested, the implementation of a silt fence alone was
not adequate enough to bring soil loss values to a level at or bgjQwJhs.pre-construction
vafuer That is,nimplementation of a silt fence alone was not enough to mitigate for the soil
loss impacts due to construction. This conclusion was also true for some climatic regions
under the flat (3%) clay condition and a limited number of the rolling (7%) sand condition.
For these conditions the silt fence was combined with the seeding and mulching Best
Management Practice from table 8. The remainder of the other Best Management
Practices andj;oil and slope conditions tested for the one acre construction sites showed
tfiatlhe computed quantity oTs^rmenTdelivered was always less than that under pre-
constructioriconditions.
For the three acre site analyses, seven of the fifteen climatic regions exhib i t edjncreases in
soil loss when comparing pre-construcii_on conditions to construction cond it tons with the
recommended Best Management Practice combination for the flat (2%) sand sites. Here
18
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the recommended Best Management Practice was the silt fence combined with seeding
and mulching (table 8).
The remaining Best Management Practices and soil and slope conditions tested, for both
the 3 acre and 5 acre sites, showed that the jmplementatjon of the recommendedBest
Management Practices resulted in bringing soil loss values to a condition equal or lower
than the Dfe-cdristruction condition.
RUSLE CONCLUSIONS
The RUSLE analysis provided insight into how construction practices can impact soil loss
from a site and how these impacts can vary regionally across the United States.
Disturbances to the soil can result in sediment loss increases ranging from 140% to
2,210% depending on the climatic region.
In addition, the RUSLE analysis provided insight into how individual Best Management
Practices and combinations of Best Management Practices acted to reduce the impacts of
construction on soil loss. The results presented in Appendix lg help to illustrate that the
Best Management Practice combinations presented in table 8 should only be looked at as
recommended combinations. For example, it was shown that the use of a silt fence alone
was not adequate in mitigating for construction impacts for the majority of the 1 acre and
3 acre construction sites with a sandy soil on a flat (3%) slope. In this case, if the goal is
to achieve no net increase in soil loss off a site, additional Best ManaqemeruPracticesmay
need to be implemented. Conversely, the remaining Best Management Practice
combinations recommended for the other site and soil conditions resulted in over
compensating for the construction impacts on soil loss. Again, the magnitude of this
impact varies depending upon the climatic region under study. Recommendations for
implementing combinations of Best Management Practices on small construction sites may
be overstated in table 8 and it may be appropriate to review these in light of the results for
small construction sites.
As part of the review of the results presented in Appendices la through lg, it needs to be
remembered that RUSLE only calculates the soil loss from sheet and rill erosion from a
hillslope, it does not predict sediment yield from a construction site. Sediment delivery
ratios, as used in the RUSLE analysis, provide information on the quantity of sediment
that bypasses the Best Management Practice placed at the base of the hill slope. Because
of this, the RUSLE results presented above should only be used to predict the potential for
soil loss and delivery off of a hill slope under varying construction conditions and Best
Management Practices. The determination and comparison of the off-site transport of this
material through a watershed under varying construction conditions is left for the AGNPS
analysis.
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AGNPS
AGNPS is an empirically based, single event watershed runoff, erosion and pollution
transport model developed by the USDA-ARS. Where RUSLE predicts soil erosion
quantities off a hillslope, AGNPS is useful in comparing the effects of implementing
various alternatives within a watershed and the resultant changes in soil loss, yield and
deposition.
The study watershed in AGNPS is divided into square, uniform cells which are defined in
the AGNPS program. For each cell the flow direction and "flow to" cell are defined.
These inputs allow AGNPS to develop the connectivity of the watershed cells. Within
each cell soil parameters, cover parameters, pollutant parameters and channel parameters
are defined. Cell by cell runoff and subsequent soil losses are generated based on input
rainfall characteristics as well as the individual cell parameters defined previously. Runoff
and soil loss from individual cells are routed to the connecting cells and through the
AGNPS watershed. Continuity equations define these relationships.
The use of AGNPS was explored to determine sediment movement through three
generalized watershed sizes under varying degrees of construction. The analyses using
AGNPS required the use of the model for both individual cell sediment yields as well as
estimates of sediment movement throughout the watershed. The results from the
individual cell calculations of the AGNPS model will be reported, but it is assumed that
the RUSLE results have more validity on an individual cell basis due to its more rigorous
approach in computing soil loss. The sole purpose of using the AGNPS model is to track
the sediment through the watershed and compare differences between watershed
scenarios.
Several watershed scenarios were tested in AGNPS to allow for comparisons between
pre-construction and construction conditions for three size watersheds with varying soil
and slope conditions. The construction conditions tested included an analysis of the
impacts of three different construction densities (3 acres, 15 acres and 30 acres) on three
different watershed sizes (99 acres, 300 acres and 639 acres).
AGNPS INPUT PARAMETERS
Watershed Data
The watershed data required by AGNPS consists of two types: general watershed size,
individual cell sizes, and information regarding precipitation. Three watershed sizes were
studied as part of the EPA Best Management Practice analysis: 99 acre, 300 acre and 639
acre. For each watershed size studied, the individual, square cells were 3 acres in size. In
keeping with the study time constraints, the AGNPS model was only applied at one
location, within the Des Moines climatic region!
20
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Information regarding precipitation inputs was adopted from a study performed by the
Chicago District Corps of Engineers for Lake George^located in Hobart. Indiana. The
AGNPS input for the Lake George study was developed as a joint effort between the
Corps office and the Soil Conservation Service (currently the Natural Resource
Conservation Service) office in Crown Point, Indiana. The precipitation inputs were
developed by the SCS based on their knowledge of the area and experience with the
AGNPS model. As the study was geared toward developing average annual loads, the
development of the precipitation input for AGNPS was based on running a series of
precipitation depths associated with varying frequency rainstorms. Resultant sediment
values at the watershed outlet were determined for each rainstorm. The sediment values
were plotted against the frequency of the associated storm events and the resultant curve
was integrated to determine an average annual sediment yield at the watershed outlet.
Once this was known, a trial and error process was followed to determine a single storm
event (precipitation depth) which would closely reproduce the average annual sediment
yield value at the watershed outlet. This precipitation depth, 4.75 inches (EI value of
143.19), was then used for subsequent average annual determinations. The above steps
were executed by the SCS as part of their work on the Lake George study. The single
precipitation value used for the Lake George study was used for the EPA analysis as well.
Although the precipitation assumptions for the present study were taken from the Lake
George study, the goal of the AGNPS modeling was to offer a comparison between
varying construction site impacts. Because of this, the quantitative results from an
individual AGNPS run have to be looked at cautiously due to the limitations of the input.
It should be obvious that the use of precipitation values from the Lake George (Hobart,
Indiana) study would not be directly applicable to the climatic conditions listed in table 1.
But the ultimate goal of the use of AGNPS needs to be remembered, that being, that
comparisons between outputs for the various conditions tested can be instrumental in
drawing qualitative conclusions regarding soil loss due to construction sites, transport of
soil off the construction site and the impacts of construction at varying locations
throughout a developing watershed.
Cell Data
The AGNPS model requires the user to define variables associated with the watershed
soil, soil cover, fertilizers, pesticides, point source loads, gullies, impoundments as well as
channel characteristics. Because the EPA analysis was only associated with sediment
loads off of construction sites, the variables associated with fertilizers, pesticides, point
source loads, gullies and impoundments were set to zero. The only inputs considered
were those relating to soil, soil cover and channel characteristics.
Soil and Soil Cover Parameters
Several inputs are required for each of the individual cells as part of the AGNPS model.
The primary soil and soil cover parameter factors required are:
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a) SCS Curve Number
b) Land Slope
c) Slope Length and Shape
d) Overland Manning's Roughness Coefficient, "n"
e) K Factor
f) C Factor
g) P Factor
h) Surface Condition Constant
The assumption for the EPA study was that the watershed had uniform parameters
throughout except under a construction condition. Where construction was simulated, the
cell or cells which were under construction had factors which varied from the undisturbed
conditions The input values associated with the land slope, slope length, K factor, C
factor and P factor were taken directly from the RUSLE analysis for pre-construction and
construction conditions in the Des Moines, Iowa climatic region. Input values for the SCS
curve numbers under pre-construction and construction conditions were based on land use
recommendations from the NRCS. The AGNPS input menu listed recommended surface
condition constants which were associated with the SCS curve number and land use
condition description. The overland Manning's roughness coefficient was assumed
constant (0.100) for all cells in all AGNPS simulations.
Channel Data
The definition of the AGNPS channel for the watersheds studied was necessarily limited
due to time constraints. It is recognized that a single channel gradient, side slope and
roughness value cannot be reasonably applied to any significant reach of channel let alone
for a channel running the length of an entire watershed. Despite this, certain assumptions
had to be made to satisfy the goals of the AGNPS analysis, to qualitatively evaluate the
impacts of varying construction scenarios on receiving waterways at varying locations
throughout a watershed of varying size. Channel slopes and Manning's roughness values
were chosen by the Corps. Channel length and side slopes were based on AGNPS default
values. It was understood, based on discussions with NRCS-ARS representatives, that the
default size of the AGNPS channel would change relative to the drainage area of the
channel. The channel geometry computations are internal to AGNPS. Assumptions for
channel parameters are presented in table 9. The parameters listed below remained
constant for every AGNPS cell which contained a channel and for each of the three
watersheds analyzed.
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Table 9. Assumed AGNPS Channel Parameters
Watershed
Watershed
Channel
Channel
Channel
Manning's
Description
Slope
Slope
Gradient
Side Slope
"n" Value
Flat
3%
5 feet/mile
0.09%
10%
0.04
Rolling
7%
15 feet/mile
0.28%
10%
0.04
Steep
12%
30 feet/mile
0.57%
10%
0.04
Very Steep
18%
50 feet/mile
0.95%
10%
0.04
In addition to the channel characteristics defined above, the AGNPS model allows the user
to specify whether the channel is erodible and allowed to contribute to the sediment yield.
Because the EPA analysis was concerned with the erosion from construction sites and the
fate of tH^ero^edlTTat^rTal, it was decidedlhat the channeLshould be specified as^a.stable
channel and therefore no^ allowed tg_degrade._ The removal of the channel erosion
component allows for a cleaner comparison of construction site impacts between the
modeled scenarios.
It is recognized that the channel conditions defined in table 9 are not applicable to channel
conditions throughout the United States. In fact, it is a gross assumption that the channel
characteristics defined in table 9 would be consistent throughout a watershed or even over
a significant length of channel. But, again, the ultimate goal of the use of AGNPS needs
to be remembered. The AGNPS model is being used as a comparative tool to draw
qualitative conclusions regarding soil loss due to construction sites, transport of soil off
the construction site and the impacts of construction at varying locations throughout a
developing watershed.
A summary of the AGNPS soil, soil cover and channel characteristics for pre-construction
and construction conditions is presented in table 10.
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Table 10. AGNPS Input Parameters for Pre-Construction and Construction Conditions
SCS
Land
Slope
Overland
K
C
P
Surface
Soil
Channel
Channel
Channel
Curve
Slope
Length
Manning's
Factor
Factor
Factor
Condition
Texture
Slope
Side Slope
Manning's
Number
"n"
Constant
#
"n"
PRE-CONSTRUCTION CONDITIONS
SAND
Flat
67
3%
200'
0.100
0.10
0.309
1.0
0.05
(1) Sand
0.09%
10%
0.04
Rolling
67
7%
140'
0.100
0.10
0.309
1 0
0.05
(1) Sand
0.28%
10%
0.04
Steep
67
12%
100'
0.100
0.10
0.309
1.0
0.05
(1) Sand
0.57%
10%
0.04
V. Steep
67
18%
50'
0.100
0.10
0.309
. 1.0
0.05
(1) Sand
0.95%
10%
0.04
CLAY
Flat
85
3%
200'
0.100
0.27
0.309
1.0
0.05
(3) Clay
0.09%
10%
0.04
Rolling
85
7%
140'
0.100
0 27
0 309
1.0
0.05
(3) Clay
0 28%
10%
0.04
Steep
85
12%
100'
0.100
0 27
0.309
1.0
0.05
(3) Clay
0.57%
10%
0.04
V.Steep
85
18%
50'
0.100
0.27
0.309
1 0
0 05
(3) Clay
0.95%
10%
0.04
SILT
Flat
89
3%
200'
0.100
0 60
0 309
1.0
0.05
(2) Silt
0.09%
10%
0.04
Rolling
89
7%
140'
0.100
0.60
0.309
1.0
0.05
(2) Silt
0 28%
10%
0.04
Steep
89
12%
100'
0.100
0.60
0.309
1.0
0.05
(2) Silt
0.57%
10%
0.04
V. Steep
89
18%
50'
0.100
0.60
0.309
1.0
0.05
(2) Silt
0.95%
10%
0.04
CONSTRUCTION CONDITIONS
SAND
Flat
77
3%
200'
0.100
0.12
0.885
1.0
0.22
(1) Sand
0.09%
10%
0.04
Rolling
77
7%
140'
0.100
0.12
0.885
1.0
0.22
(1) Sand
0.28%
10%
0.04
Steep
77
12%
100'
0.100
0.12
0.885
1.0
0.22
(1) Sand
0.57%
10%
0.04
V. Steep
77
18%
50'
0.100
0.12
0.885
1.0
0.22
(1) Sand
0.95%
10%
0 04
CLAY
Flat
91
3%
200'
0.100
0.34
0.885
1.0
0.22
(3) Clay
0.09%
10%
0.04
Rolling
91
7%
140'
0.100
0.34
0.885
1.0
0.22
(3) Clay
0.28%
10%
0.04
Steep
91
12%
100'
0.100
0.34
0.885
1.0
0.22
(3) Clay
0.57%
10%
0.04
V.Steep
91
18%
50'
0.100
0.34
0.885
1.0
0.22
(3) Clay
0.95%
10%
0.04
SILT
Flat
94
3%
200'
0 100
0.80
0.885
1 0
0.22
(2) Silt
0.09%
10%
0.04
Rolling
94
7%
140'
0.100
0.80
0.885
1.0
0.22
(2) Silt
0.28%
10%
0.04
Steep
94
12%
100'
0.100
0.80
0.885
1.0
0.22
(2) Silt
0.57%
10%
0.04
V. Steep
94
18%
50'
0.100
0.80
0.885
1.0
0.22
(2) Silt
0.95%
10%
0.04
24
-------
AGNPS COMPUTATIONS
The AGNPS model proceeds through three loops in determining final sediment yields and
distributions throughout the watershed. The first loop consists of the initial calculations
for the individual cells that make up the watershed. These initial calculations include:
upland erosion, overland runoff volume and time until overland runoff becomes
concentrated flow. The second loop calculates the sediment yields for primary cells, cells
which have no other cells draining into them. The final loop routes the sediment through
the rest of the watershed based on concentrated flow rates, channel transport capacity and
sediment flow rates. Additional calculations are made for pollutants and impoundments,
but these are not discussed here as they were not considered for the EPA Best
Management Practices analysis.
Upland erosion calculations in AGNPS use a modified version of the Universal Soil Loss
Equation which takes into account the shape (uniform, concave or convex) of the slope -
which was considered uniform in all the AGNPS simulations which were run. The soil
texture classification is then used to determine the fractional components of the eroded
material.
The runoff volume from each cell is determined using the USDA-Soil Conservation
Service (SCS) curve number method. This method relates the runoff to the precipitation
and the soil retention factor which is directly related to the SCS curve number. The time
at which concentrated flow occurs is related to the slope length, the slope of the land and
the surface condition constant.
Sediment routing through the individual cells is based on equations derived from the
steady state continuity equation which considers sediment discharge at the upstream end
of the cell, the lateral sediment inflow within the cell and the sediment deposition rate
within the cell. Deposition within the cell is based on the fall velocity of the individual
particles, the runoff flow rate within the cell, the sediment flow rate and the effective
sediment transport capacity which is determined using a modified version of the Bagnold
stream power equation.
Details on the above AGNPS computations can be found in the 1994 AGNPS user's
guide. In addition, the user's guide lists the equations used within AGNPS and presents
references for further clarification.
EPA COMBINATIONS TESTED IN AGNPS
Watershed sizes, soil types, slopes and construction sites were varied and combined in an
attempt to determine some general understanding of potential sediment impact and
redistribution throughout the watershed under varying watershed construction scenarios.
The AGNPS individual cell sizes were 3 acres for all conditions tested. Three watershed
sizes were tested: 99 acres (33 cells), 300 acres (100 cells) and 639 acres (213 cells).
Four slope conditions were tested and three soil types were tested. Four construction
25
-------
conditions were tested: pre-construction, one construction site per watershed (3 acres),
five construction sites (15 acres) per watershed and ten construction sites (30 acres) per
watershed. These combinations resulted in 144 AGNPS simulations (3*4*3*4 = 144).
The three watersheds tested were subwatersheds of each other, where the 99 acre
watershed is lumped into the 300 acre watershed and the 300 acre watershed is similarly
lumped into the full 639 acre watershed. Figure 2 shows the combined watershed and
figures 3 through 5 detail the three individual watersheds. These figures show the
watershed outline, the AGNPS cell numbers, the primary flow paths through the
watershed, the individual flow connections between cells as well as the cells where
AGNPS results are reported.
The impacts of varying numbers of construction sites (1,5 and 10) were tested for each of
the three watershed sizes. A single construction site occupied an entire 3 acre cell so the
1, 5 and 10 construction sites represent 3 acres, 15 acres and 30 acres of construction,
respectively. Figures 3 through 5 illustrate the placement of the assumed construction
sites for each of the three watersheds tested.
DISCUSSION OF AGNPS OUTPUT AND RESULTS
AGNPS output can be examined at the individual cell level or at various locations
throughout the simulated watershed. Sediment and runoff summary data were requested
at every cell in the watershed and were output to general ASCII files. A computer
program was written to extract pertinent data from the output files for import to
Microsoft Excel for further processing. The computer program allowed the user to input
cells where detailed data was requested. For each watershed size, five cells were chosen
for detailed output. The cells which were chosen for the three watershed sizes represented
a combination of the following: an upland cell with no cells flowing into it, a cell at the
start of a defined channel segment, cells at varying locations along the main channel, cells
at tributary confluences and a cell at the watershed exit. Table 11 presents the cells where
detailed output was requested and figures 3 through 5 show the cell locations.
Table 11. Cells Where AGNPS Results Are Reported
99 Acre Watershed 300 Acre Watershed 639 Acre Watershed
AGNPS
Drainage
AGNPS
Drainage
AGNPS
Drainage
Cell Number
Area (acres)
Cell Number
Area (acres)
Cell Number
Area (acres)
5*
3
31**
27
31**
27
9
12
61
75
92***
147
13**
27
85***
147
106***
282
17
48
92***
282
175***
534
27****
99
100****
300
213****
639
* Upland Cell
*** Cell at Tributary Confluence
** Cell at Start of Defined Channel Segment
**** Cell at Watershed Exit
26
-------
Individual Cell Erosion
The first comparison made was at the individual cell level. The change in cell erosion
going from a pre-construction to a construction condition is presented in table 12. These
values reflect the soil erosion offa single 3 acre AGNPS cell under a pre-construction and
a construction condition. The soil erosion is not the amount that leaves the 3 acre
construction site but rather the soil eroded from the site. As will be seen in subsequent
tables, a portion of the soil erosion is deposited within the 3 acres and thus not transported
off site. As discussed in the section titled "AGNPS Computations", the individual cell
erosion is computed within the first of the three AGNPS computational loops.
Table 12. AGNPS Cell Erosion for Pre-Construction and Construction Conditions
AGNPS Computed Cell Erosion Percent
(tons/acre) Increase
Slope
Pre-Construction
Construction
Difference
Due to
Soil Type
(%)
Condition
Condition
(tons/acre)
Construction
Sand
3
1.6
5.4
3.8
243
Clay
3
4.2
15
11
261
Silt
3
10
36
26
258
Sand
7
4.3
15
11
244
Clay
7
12
42
30
261
Silt
7
28
99
71
258
Sand
12
8.1
28
20
244
Clay
12
22
79
57
261
Silt
12
52
185
133
258
Sand
18
11
38
27
244
Clay
18
30
107
77
261
Silt
18
71
253
182
258
From table 12 it can be seen that there is a general 240 to 260 percent increase in cell
erosion (displacement) due to construction activities for the site conditions defined in table
10. This increase is due to the change in the K and C values when going from a pre-
construction to a construction condition. A comparison of the soil loss values presented
in table 12 can be made against the RUSLE pre-construction and construction results
presented in Appendix la and lb. The comparisons made were against those results for
the Des Moines, Iowa climatic region. When comparing the AGNPS against the RUSLE
results, the AGNPS results were:
27
-------
a) 35% lower for all soil conditions at the flat (3%) slope,
b) 17% lower for all soil conditions at the rolling (7%) slope,
c) 9% lower for all soil conditions at the steep (12%) slope, and
d) 13% higher for all soil conditions at the very steep (18%) slope.
The differences detailed above were equivalent for the pre-construction and the
construction conditions. It is assumed that the differences are due to the differences in the
precipitation inputs between the two models. The RUSLE computations are based on the
R value for Des Moines, Iowa. The AGNPS computations are based on a single
precipitation depth and energy-intensity value for a storm which closely generated an
average annual soil loss for a specific location, Hobart, Indiana. Considering the
computational differences between the two models, the difference in the precipitation
inputs and the uncertainties inherent in any sediment study, the differences listed above are
not considered unreasonable. Again, the reader should be aware that the primary focus of
the AGNPS analysis is with regard to differences within the AGNPS model run under
varying scenarios and not in a comparison between AGNPS and RUSLE. With that in
mind, the primary purpose of table 12 is to illustrate the percent increases in cell erosion
when going from a pre-construction to a construction condition.
Cell Deposition and Yield
As stated earlier, the amount of soil loss due to cell erosion does not reflect the amount of
soil which leaves the 3 acre construction site. The soil loss values presented in table 12
above represent the soil which is eroded from the hill slope. That soil is further
transported through the cell, a portion of which deposits within the cell and the remainder
is yielded by the cell or transported to the next downstream cell. Table 13 presents the
erosion from an upland cell, the amount of sediment deposited within the 3 acre upland
cell and the amount of sediment that leaves the 3 acre upland cell. These quantities are
presented for both pre-construction and construction conditions. As discussed in the
section titled "AGNPS Computations", the cell yield from upland cells is determined in
loop two of the three AGNPS computational loops.
28
-------
Table 13. AGNPS Upland Cell Deposition and Yield
Cell
Sediment
Percent
Sediment
Percent
Erosion
Deposited
Deposited
Yielded
Yielded From
(tons)
(tons)
w/in 3acre Cell
(tons)
3acre Cell
Pre-Construction Condition
Sand (3%)
4.7
4.1
88
0.6
12
Clay (3%)
12.69
6.4
50
6.3
50
Silt (3%)
30.07
17
57
13
43
Sand (7%)
13.00
11
87
1.7
13
Clay (7%)
35.10
16
46
19
54
Silt (7%)
83.21
45
54
39
46
Sand (12%)
24.22
21
86
3.3
14
Clay (12%)
65.4
29
44
36
56
Silt (12%)
155.03
80
52
75
48
Sand (18%)
33.11
28
86
4.7
14
Clay (18%)
89.41
38
43
51
57
Silt (18%)
211.93
107
50
105
50
Construction Condition
Sand (3%)
16.15
14
87
2.1
13
Clay (3%)
45.75
22
49
23
51
Silt (3%)
107.66
60
56
48
44
Sand (7%)
44.68
38
86
6.2
14
Clay (7%)
126.61
57
45
69
55
Silt (7%)
297.90
157
53
141
47
Sand (12%)
83.25
71
85
12
15
Clay (12%)
235.88
102
43
134
57
Silt (12%)
555.02
282
51
273
49
Sand (18%)
113.81
97
85
17
15
Clay (18%)
322.46
134
42
188
58
Silt (18%)
758.73
376
50
383
50
A review of table 13 shows that for each of the three soil groups, deposition percentages
remain fairly constant for the four slopes tested. That is, sand at a flat slope (3%) showed
similar cell deposition percentages as sand on a very steep slope (18%). In addition, table
13 shows that deposition percentages remained consistent between pre-construction and
construction conditions. It can also be seen that a sandy soil condition results in
deposition percentages of approximately 85%, that is only 15% of the eroded soil is
yielded from the 3 acre upland site. Silt and clay type soils have much lower deposition
percentages, 50% and 40%, respectively. As expected, much of the silt and clay particles
stay in suspension and are yielded from the upland cell. The results presented in this
section are valid for individual upland cells, that is, cells which are not subject to flow or
sediment loads from upstream cells. The deposition and yield percentages presented in
table 13 can be useful in transforming the RUSLE cell erosion values presented in
29
-------
Appendix 1 into expected cell depositions and cell yields. Cell depositions and cell yields
would then be valid for upland cells.
Watershed Deposition and Yield
The data presented in the above section dealt with the deposition and yield characteristics
of a 3 acre upland site, that is, a site with no tributary drainage except that which comes
off the 3 acres. In addition, no defined waterway was present on the 3 acre upland site.
The presentation of watershed deposition and yield becomes more difficult because
individual cells within the AGNPS watershed have other cells flowing into them,
sometimes one cell and sometimes up to three cells. Sediment yield from these sources
are in addition to the sediment loss from the cell itself. Transport of the combined
material is then limited to the transport capacity of the receiving channel. In addition, the
specification of the location of the construction sites throughout the three watersheds
makes for a difficult comparison among scenarios modeled. As stated in the section titled
"AGNPS Computations", the computation of sediment yield at every cell in the watershed
is determined in loop three of the AGNPS computations.
In an attempt to simplify the comparison, sediment yield changes at the watershed outlet
for the 99 acre, 300 acre and 639 acre watersheds were observed. This presentation
allows for a reasonable and quick comparison between soil types, watershed slopes,
watershed sizes and degrees of construction. It needs to be remembered that the values
presented in this table will vary depending on the placement of the construction sites.
Where, construction sites located in the uplands are less likely to contribute additional
sediment loading at the watershed outlet than construction sites located directly on
mainstem streams running the length of the watershed or construction sites located at or
near the watershed outlet. Table 14 presents the data representing conditions studied as
part of the EPA analysis as described in the section "EPA Combinations Tested in
AGNPS".
A review of table 14 shows that net increases in sediment yield due to construction
remains fairly constant between the 99 acre and 300 acre watershed scenarios when
looking at equivalent soil types, slopes and density of construction. This indicates that
construction on the smaller watersheds results in a |arger.percent_increase.in.sediment.
yield from the watershed. The net increase in sediment yield from the 639 acre watershed
undercSnstruction conditions is less than that from the 300 acre hypothetical watershed.
Table 15 presents the same data in a different format. The values in table 15 are
normalized sediment yield increases, that is, the increase in sediment yield (tons) per
acreage of construction disturbance. What this table would indicate is that certain
conclusions regarding construction impacts on watershed sediment yield can be drawn.
For example, construction on a 99 acre, rolling (7% slope), silty, watershed would result
in sediment yield increases of 10 to 12 tons per acre of disturbance due to construction.
This same conclusion can be drawn for the 300 acre watershed.
30
-------
Table 14. Comparison of Sediment Yield at Watershed Outlet
Soil and
Slope
Condition
Sediment Yield (tons)
at Outlet of a
99 Acre Hypothetical Watershed
Construction Density*
Sediment Yield (tons)
at Outlet of a
300 Acre Hypothetical Watershed
Construction Density*
Sediment Yield (tons)
at Outlet of a
639 Acre Hypothetical Watershed
Existing 1 Site 5 Sites 10 Sites Existing 1 Site 5 Sites 10 Sites Existing
Construction Density*
1 Site 5 Sites 10 Sites
Sand (3%)
9
10
11
14
25
25
27
29
44
j auics
45
i j acres
46
ju acres
48
Clay (3%)
87
92
113
144
233
238
259
291
416
420
442
462
Silt (3%)
162
171
209
266
421
430
466
527
709
714
754
786
Sand (7%)
23
24
29
37
61
62
67
75
108
109
114
118
Clay (7%)
275
292
362
466
731
747
816
924
1279
1290
1363
1427
Silt (7%)
539
571
702
902
1398
1427
1556
1768
2324
2342
2479
2588
Sand (12%)
45
48
58
75
118
121
131
148
205
206
217
227
Clay (12%)
568
604
752
971
1508
1542
1687
1916
2615
2638
2790
2922
Silt (12%)
1134
1203
1487
1916
2955
3019
3299
3750
4917
4955
5247
5486
Sand (18%)
66
70
86
111
173
176
192
217
295
298
314
328
Clay (18%)
840
895
1116
1444
2236
2287
2505
2846
3868
3901
4127
4326
Silt (18%)
1693
1800
2232
2880
4441
4540
4966
5646
7425
7482
7924
8291
* Construction Density is expressed in acres, where 15 acres indicates 5 AGNPS cells (3 acres each) are in a construction condition
-------
Table IS. Normalization of Increased Sediment Yield for Varying Construction Densities
Soil and
Slope
Condition
Normalized* Sediment Yield
Increase (tons/acre)
at Outlet of a
99 Acre Hypothetical Watershed
Construction Density*
Normalized* Sediment Yield
Increase (tons/acre)
at Outlet of a
300 Acre Hypothetical Watershed
Construction Density*
Normalized* Sediment Yield
Increase (tons/acre)
at Outlet of a
639 Acre Hypothetical Watershed
Construction Density*
Existing 1 Site 5 Sites 10 Sites Existing 1 Site 5 Sites 10 Sites Existing 1 Site 5 Sites 10 Sites
3 acres
15 acres
30 acres
3 acres
15 acres
30 acres
3 acres
15 acres
30 acres
Sand (3%)
-
0.3
0.1
0.2
-
0.0
0.1
0 1
0.3
0.1
0.1
Clay (3%)
-
1.7
1.7
1.9
-
1.7
1.7
1.9
1.3
1.7
1.5
Silt (3%)
-
3.0
3.1
3.5
-
3.0
3.0
3.5
1.7
3.0
2.6
Sand (7%)
-
0.3
0.4
0.5
-
0.3
0.4
0.5
0.3
0.4
0.3
Clay (7%)
-
5.7
5.8
6.4
-
5 3
5.7
6.4
3.7
5.6
4.9
Silt (7%)
-
10.7
10.9
12 1
-
9.7
10.5
12.3
6.0
10.3
8.8
Sand (12%)
-
1.0
0.9
1.0
-
1.0
0.9
1.0
0.3
0.8
0.7
Clay (12%)
-
12.0
12.3
13.4
-
11.3
11.9
13.6
7.7
11.7
102
Silt (12%)
-
23.0
23.5
26 1
-
21.3
22.9
26.5
12.7
22.0
19.0
Sand (18%)
-
1.3
1.3
1.5
-
1.0
1.3
1.5
1.0
1.3
1.1
Clay (18%)
-
18.3
18.4
20.1
-
17.0
17.9
20.3
11.0
17.3
15.3
Silt (18%)
-
35.7
35.9
39.6
-
33.0
35.0
40.2
19.0
33.3
28.9
*Where the normalized sediment yield increase for a 3 acre
For example, for the 99 acre watershed (sand (H> 7% slope)
construction condition is equivalent to:
((Construction Yield - Existing Yield)/(Acres of Construction))
under a 30 acre construction density the normalized yield would be: ((37-23)/30) = 0.5
32
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Another interesting conclusion from table 15 is that a sandy watershed of any size and any
slope has a very limited range of sediment yield increases ranging from less than 0.1 to 1.5
tons per acre of construction disturbance. However, it should be noted that the shape of
the watershed, the shape of the channel transporting this material and the resultant channel
velocities, may have impacted the sediment yield. Silty soils resulted in the largest range
of sediment yield increases when comparing the three watersheds under the four slopes,
where yield increases varied from 1.7 to 40 tons/acre of construction. The clay soils also
had a fairly large range in sediment yield increase (1.3 to 20 tons/acre of construction)
under the four slopes and three watershed sizes tested.
A closer look at table 15 also identifies an apparent anomaly for the 639 acre watershed
with a 15 acre construction density. The general trend, when looking at the 99 acre and
300 acre watersheds, is that the normalized sediment yield increase value increases from 3
acres of construction to 15 acres of construction and from 15 to 30 acres of construction.
This is not the case with the 639 acre watershed. Although there is an increase from the 3
to 15 acres of construction, there is a decrease when going from 15 acres to 30 acres. At
first this appears to be an anomaly but looking at the randomly chosen construction sites
(Figures 3 - 5), it can be seen that the 15 acres of construction scenario was based on two
of the five construction sites near the 639 acre watershed outlet. Although these same
two construction sites are present under the 30 acres of construction condition, their
contribution to the normalized sediment yield increase value is diminished due to the
presence of the other eight construction sites located higher up in the watershed. Despite
this, a look at table 14 confirms the expected trend of increasing sediment yield with
increasing construction density. Based on this, the apparent anomaly is really a result of
the random placement of the construction sites for the 639 acre watershed under the 15
acres and 30 acres of construction disturbance.
The conclusion from the observations above, then, is that the location of construction sites
plays a role in resultant watershed yield increases. The construction scenarios shown in
figures 3 through 5 should be referenced in conjunction with the results in tables 14 and
15. In addition, the configuration of the watershed and locations of waterways within the
watershed play a role in these results. Finally, the shape of the assumed channel effects
channel velocities and thereby effect the transport of materials downstream. In summary,
general conclusions regarding watershed yields need to keep these qualifiers in mind.
The results provided in table 14 can also be found in Appendix 2a where sediment yield
and percent deposition values are presented for each soil, slope, watershed size and
construction condition analyzed. Representatives at NRCS have indicated that the
AGNPS sediment yield results should primarily be looked at on a comparative basis
between scenarios tested. That is, the individual yield results should not be used directly.
More credence is given to percent changes in sediment yields when scenarios are "
compared, These comparisons are made at the end of the AGNPS results discussion and
are contained in Appendix 2b. The discussions above are not meant to present exact
numbers but are intended to convey general trends in sediment movement throughout a
watershed under varying construction scenarios.
33
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Another analysis of the overall watershed results is presented in graphical format. For
each of the three watershed sizes and four construction density conditions the sediment
yield increases due to construction were tracked at varying locations throughout the
watershed. The sediment yield increases due to construction were computed at each of
the five reporting cells listed in table 11. This computation was made for every soil and
slope combination and for each watershed size and construction condition. Figures 6
through 14 present these results.
As with all of the results from the AGNPS analysis, these figures have to be looked at with
an understanding of the specified locations of construction sites. The three figures
representing the impacts of one 3 acre cell under construction on 99 acre, 300 acre and
639 acres watersheds (Figures 6, 9 and 12) are the easiest to interpret. These figures
show the impact of a single 3 acre construction site on sediment yields at varying locations
throughout the watershed under 12 soil and slope combinations.
When looking at the results for the watersheds with 15 acres of construction (5 AGNPS
cells at 3 acres each) and 30 acres of construction, the locations of the construction sites
plays a role in the sediment yield increases throughout the watershed. Again, the
construction scenarios shown" inTigures 3 through 5 should be referenced when reviewing
the results presented in figures 6 through 14.
Table 16 details the AGNPS reporting cells (and their drainage areas) where the data in
figures 6 through 14 is plotted. In addition, table 16 shows the number of cells which
were modeled as construction sites which are tributary to the reporting cell in the AGNPS
watershed. An additional column also identifies the actual AGNPS cell number(s) which
has construction and can be cross-checked against figures 3 through 5.
34
-------
Table 16. AGNPS Reporting Cell and Construction Site Information
1 Construction Site (3 acres)
5 Construction Sites (15 acres)
10 Construction Sites (30 acres)
Drainage Area
Number of
AGNPS
Number of
AGNPS
Number of
AGNPS
AGNPS
to Reporting
Construction
Construction
Construction
Construction
Construction
Construction
Reporting
Cell Number
Cell
(acres)
Sites Tributary
to the AGNPS
Cell
Identification
Sites Tributary
to the AGNPS
Cell
Identification
Sites Tributary
to the AGNPS
Cell
Identification
Reporting Cell
Numbers
Reporting Cell
Numbers
Reporting Cell
Numbers
Watershed Size:
99 Acres
5
3
0
n.a.
1
5
1
5
9
12
1
9
2
5, 9
2
5, 9
13
27
1
9
2
5,9
4
3,5, 9, 13
17
48
1
9
4
5, 9, 12, 20
7
2,3,5,9,12,13,20
27
99
1
9
5
5,9, 12,20, 25
10
2,3,5,9,12,13,
20,25.29,30
Watershed Size:
300 Acres
31
27
0
n.a.
0
n.a.
0
n.a.
61
75
1
32
2
32, 60
2
32, 60
85
147
0
n.a.
2
41,42
5
35,38,41,42,49
92
282
1
32
5
32,41,42,60,73
8
32,35,38,41,42,
49,60,73
100
300
I
32
5
32,41,42,60,73
10
32,35,38,41,42,
49,60,73,93,94
Watershed Size:
639 Acres
31
27
0
n.a.
0
n.a.
0
n.a.
92
147
1 26
1
26
4
26, 67, 68, 93
106
282
1
26
3
26, 45, 62
8
26,45,48, 62,
67, 68, 75, 93
175
534
1
26
3
26, 45, 62
8
26, 45, 48, 62,
67, 68, 75, 93
213
639
1
26
5
26, 45, 62, 199,
200
10
26, 45, 48, 62,
67, 68, 75, 93,
199, 200
-------
Appendix 2b presents tables of percent sediment yield increases for the soil, slope,
watershed size and construction conditions tested in AGNPS. These results are presented
at each of the AGNPS reporting cells as shown in table 16. A summary of the results at
the watershed outlet cells, taken from Appendix 2b, are shown in table 17. The table
presents the percent change in sediment yield at the watershed outlet under varying soil,
slope and construction scenarios.
The most noticeable trend in table 17 is that the sediment yield increase percentages are
greater for the smaller watershed (99 acre) than for the larger watersheds (300 and 639
acres) under similar construction density scenarios. This difference is most pronounced :
when comparing the scenarios with 10 construction sites over the three watershed sizes.
Percent sediment yield increases range from 46% to 72% for the 99 acre watershed
depending on the soil type - where the majority of the increases were around 70%. For
the 639 acre watershed, the percent sediment yield increases have a much smaller range,
8% to 11% for all soils. This trend, as expected, indicates that smaller watersheds can be
greatly impacted by high density construction.
For each watershed size investigated (99 acres, 300 acres and 639 acres) the percent
increase in sediment yield due to construction throughout the watershed was very similar
when comparing the silt and clay conditions results - under all slope and construction
conditions. This was true under all watershed sizes and construction scenarios tested.
Looking at the 99, 300 and 639 acre sandy watersheds similar trends are apparent when
comparing the rolling (7%), steep (12%) and very steep (12%) slopes. But when
comparing the flat (3%) to the rolling (7%) slope it can be seen that the percent yield
increase goes up as the slope becomes steeper. These same results are true for the 1, 5
and 10 construction site conditions tested for the sandy watershed. This trend is most
likely related to the carrying capacity of the channel associated with the flat watershed.
As stated earlier, the most acceptable way to present and interpret the AGNPS results
should be based on percent changes in sediment yield - as shown in table 17 and presented
in Appendix 2b. The results presented in tables 12 through 15 and figures 6 through 14
were intended to give an indication of trends in sediment yield increases under varying
degrees of soil types, slopes and construction conditions. The values presented in those
tables and figures should not be looked at as absolute values. More reliance should be
given to the percent change values presented in table 17 and in Appendix 2b. But again,
the specific watershed, channel and construction configurations chosen for this analysis
need to be kept in mind.
36
-------
Table 17. Increase in Sediment Yield (percent) at Watershed Outlet From Pre-Construction to Construction Conditions
Sandv Soil
Clavev Soil
Silty Soil
U of Construction Sites
# of Construction Sites
# of Construction Sites
Watershed
Watershed
I 5 10
1 5 10
1 5 10
Description
Slope
(3 acres) (15 acres) (30 acres)
(3 acres) (15 acres) (30 acres)
(3 acres) (15 acres) (30 acres)
Watershed Size: 99 acres (AGNPS Outlet Cell = 27)
Flat
3 %
4
21
46
6
30
65
5
29
64
Rolling
7%
5
27
61
6
31
69
6
30
67
Steep
12%
6
29
66
6
32
71
6
31
69
Very Steep
18%
6
30
68
6
33
72
6
32
70
Watershed Size: 300 acres (AGNPS Outlet Cell = 100)
Flat 3 %
1 8
17
2
11
25
2
11
25
Rolling 7 %
2 10
23
2
11
26
2
11
26
Steep 12 %
2 11
25
2
12
27
2
12
27
Very Steep 18%
2 11
26
2
12
27
2
12
27
Watershed Size: 639 acres (AGNPS Outlet Cell = 213)
Flat 3 %
1 4
8
1
6
11
1
6
11
Rolling 7 %
1 6
10
1
6
11
1
7
11
Steep 12 %
1 6
11
1
7
12
1
7
12
Vers'Steep 18%
1 6
11
1
7
12
1
7
12
17
-------
AGNPS CONCLUSIONS
Again, the results presented above were for a hypothetical application of the AGNPS
model. The chosen precipitation, watershed, soil, and channel characteristics along with
the construction site layout impact the results presented above. Despite this, the results
can be used in a comparative fashion to examine trends when certain parameters are
modified. Therefore, it is recommended that the results presented as percent changes be
given more credence than those presented as absolute values (ex. tons per acre).
Based on the results of the AGNPS analysis it was shown that for upland cells within
sandy watersheds, the majority (85%) of the eroded soil deposits within the upland cell
and only a small portion of the eroded soil is yielded to a downstream cell. For upland
cells with silt and clay type soils it was found that approximately half of the eroded soil
stays on site and half is yielded to a downstream cell. These conclusions were true for all
watershed, slope and construction conditions which were tested.
The AGNPS analysis of construction conditions revealed the expected trend of increasing
sediment yield with increasing construction density. In addition, the analysis of the three
sizes of watersheds showed that construction on smaller watersheds results in a larger
percent increase in sediment yield from the watershed - up to a 70% sediment yield
increase for 30 acres of construction on a 99 acre watershed compared to only a 12%
sediment yield increase for 30 acres of construction on a 639 acre watershed.
The recurring conclusion from the AGNPS results was that the location of the
construction sites plays a role in resultant watershed yield increases. Upland construction
sites had far less impact than those placed near watershed outlets. And, as indicated
previously, the specific watershed, channel and construction configurations chosen for this
particular analysis need to be kept in mind.
As an additional note, based on correspondence from NRCS (April 14, 1998 fax), the
AGNPS model will generally underpredict the sediment yield from construction sites.
This is due to the fact that significant erosion from a given construction site occurs in
concentrated flows and in gullies. There is the capability to explicitly define this source
within AGNPS but this was not included in the AGNPS runs described above in order to
minimize the differences between AGNPS runs.
The increase in sediment yield from construction sites as described above is only a short
term problem, occurring only during the construction period. Despite this, the increases in
sediment yield can cause a variety of problems that are likely to persist beyond the
duration of the construction period. These impacts include, but are not limited to:
aggradation and impairment of natural drainage ways, increased maintenance of harbors
and navigable channels, sedimentation in storage reservoirs, excess turbidity in the water,
as well as impacts to recreation, wildlife and vegetation.
STUDY CONCLUSIONS AND RECOMMENDATIONS
38
-------
The impacts of construction, described above, are followed by the impacts of the newly
created development. A fax from NRCS (dated April 14, 1998) states that additional
problems are likely to occur after the construction is completed and the presence of the
development(s) causes increases in the flow hydrograph, due to changes in the runoff
patterns from the developed area(s). Potential long term impacts include: channel
downcutting and headcutting, side slope sloughing and other changes to the channel
morphology. These long term impacts to the channel can eventually effect local water
tables, riparian vegetation, fish and wildlife habitat and stream-side land use.
In summary, the impacts of construction on soil loss and sediment yields are not strictly
limited to disturbances during the period of construction. Increased sediment loads due to
construction effect receiving waterways and can result in long term impacts due to
accumulations of sediment. In addition, the post-construction condition of the site can
alter the hydrology and soil cover conditions and cause changes to the long term sediment
loads to the receiving waterways.
In light of the above, the implementation of Best Management Practices on small
construction sites can help alleviate the short term sedimentation impacts due to
construction. Where Best Management Practices are not practical or not effective in
controlling erosion due to construction, it may be appropriate to consider a form of
reimbursement to local watershed commissions for increased sediment loads which occur
during construction as well as for a means of mitigating the long term impacts of
development on area waterways.
39
-------
REFERENCES
U.S. Army Corps of Engineers, Hydrologic Engineering Center. Application of Methods
and Models for Prediction of Land Surface Erosion and Yield. Training Document
No. 36. March, 1995.
U.S. Army Corps of Engineers. Sedimentation Investigations of Rivers and Reservoirs.
Engineering Manual, EM 1110-2-4000. December, 1989.
U.S. Army Corps of Engineers. Construction Engineering Research Laboratories. A
Summary of Best Management Practices for Nonpoint Source Pollution. USACERL
Technical Report EP-93/06. August 1993.
U.S. Army Corps of Engineers, Chicago District. Trail Creek Sediment Trap Study.
Chicago, Illinois. April 1995.
U.S. Army Corps of Engineers, Chicago District. Lake George, Hobart, Indiana -
Planning/Engineering Report. May 1995.
U.S. Department of Agriculture, Agricultural Research Service. AGNPS, Agricultural Non-
Point-Source Pollution Model. Conservation Research Report 35. December 1987.
U.S. Department of Agriculture, Agricultural Research Service. Predicting Soil Erosion by
Water: A Guide to Conservation Planning With the Revised Universal Soil Loss
Equation (RUSLE). Agricultural Handbook Number 703. January 1997.
U.S. Department of Agriculture, Natural Resources Conservation Service. Agricultural Non-
Point Source Pollution Model, Version 4.03, AGNPS User's Guide. September, 1994.
U.S. Department of Agriculture, Soil Conservation Service. Land Resource Regions and Major
Land Resource Areas in the United States. Agriculture Handbook Number 296.
December, 1981.
U.S. Department of Agriculture, Natural Resources Conservation Service. Default Slope Length
For Each Increment of Slope Steepness For Use in All Areas of the U.S. Except the
'Palouse', by D.T. Lightle and G.A. Weesies - Unpublished Document. October 1996.
U.S. Environmental Protection Agency. 40 CFR Parts 122 and 123, National Pollutant
Discharge Elimination System-Proposed Regulations for Revision of the Water
Pollution Control Program Addressing Storm Water Discharges; Proposed Rule.
January, 1998.
American Society of Civil Engineers. Sedimentation Engineering. ASCE Manuals and
Reports on Engineering Practice-No. 54. 1977.
40
-------
RUSLE Results for
Pre-Construction Condition - Sandy Soils at Varying Slopes
0.00 0.20 0.40 0.60 0.80 1.00 1.20
RUSLE 'LS' Factor
1.40
1.60
1.80
—e—
- Charleston
- Atlanta
—A
- San Antonio
—e—
- Nashville
—X
- Des Moines
--Q--
- Hartford
—O--
- Amarillo
—A--
- Duluth
—©--
- Bismarck
- Denver
D
- Helena
- Boise
A
- Las Vegas
- . -O -
- Portland
- *
Fresno
2.00
Analysis of Best Management Practices
for Small Construction Sites
Pre-Construction Conditions RUSLE Soil Loss.
Sandv Soils
Chicago District. U.S. Army Corps of Engineers
June 1998 Figure 2
-------
RUSLE Results for
Pre-Construction Condition - Clayey Soils at Varying Slopes
80.0
75.0
70.0
65.0
60.0
55.0
gT 50.0
u
re
"55 45.0
c
o
Si 40.0
(A
M
.3 35.0
w 30.0
25.0
20.0
15.0
10.0
5.0
"i" f"A
1--s-
¦ini|iiniii"i,ii-T,f,rin"l""" J'
0.80 1.00 1.20
RUSLE 'LS' Factor
u r-f
—B—
- Charleston
—o-
- Atlanta
- San Antonio
—e—
- Nashville
—*—
- Des Moines
—Q--
- Hartford
—O--
- Amarillo
—A- -
- Duluth
--0--
- Bismarck
- Denver
Q.
-Helena
O
- Boise
- - A -
- Las Vegas
- - e>.
- Portland
- Fresno
2.00
V
Analysis of Best Management Practices
for Small Construction Sites
Pre-Construction Conditions RUSLE Soil Loss.
Clavev Soils
Cliicaeo District. U.S. Armv
June 1998
Engineers
Cure .3
-------
RUSLE Results for
Pre-Construction Condition - Silty Soils at Varying Slopes
-s,
—a— Charleston
—o— Atlanta
—a— San Antonio
—o— Nashville
—x— Des Moines
—~— Hartford
--o--- Amarillo
-—a— Duluth
—©— Bismarck
—Denver
- - q Helena
- - - - Boise
-a-- - Las Vegas
- o - Portland
x Fresno
0.00 0.20 0.40 0.60 0.80 1.00 1.20
RUSLE 'LS* Factor
1.40
1.60
1.80
2.00
Analysis of Best Management Practices
for Small Construction Sites
Prc-Constructton Conditions RUSLE Soil Loss.
Sillv Soils
Chicago District. U.S. Arniv Corps of Engineers
June I99X
Figure 4
-------
RUSLE Results for
Construction Condition - Sandy Soils at Varying Slopes
—B—
Charleston
O
Atlanta
—A—
San Antonio
—O
Nashville
—X—
Des Moines
—~—
Hartford
—0
Amarillo
—A—
Duluth
Bismarck
Denver
Helena
- - -
Boise
A
Las Vegas
- - O -
Portland
- X- •
Fresno
0.00 0.20 0.40 0.60 0.80 1.00 1.20
RUSLE *LS' Factor
1.40
1.60
1.80
2.00
Analysis of Best Management Practices
for Small Construction Sites
Construction Conditions RUSLE Soil Loss.
Snndv Soils
Chicago District. U.S. Army
-------
RUSLE Results for
Construction Condition - Clayey Soils at Varying Slopes
~
- Charleston
-Atlanta
A—
- San Antonio
—©—
- Nashville
—X—
- Des Moines
--B--
- Hartford
-0--
- Amarillo
—A--
- Duluth
—0—
- Bismarck
—3K--
- Denver
- o
Helena
. . o -
- Boise
A
- Las Vegas
- -o
Portland
- K
Fresno
0.00 0.20 0.40 0.60 0.80 1.00 1.20
RUSLE 'LS' Factor
1.40
1.60
1.80
2.00
Analvsis of Best Management Pmcticcs
for Small Construction Sites
Constniction Conditions RUSLE Soil Loss.
Clnvcv Soils
Chicago District. U S Armv Corps of Engineers
June | FiiMirc 6
-------
RUSLE Results for
Construction Condition - Silty Soils at Varying Slopes
S-
u
«
w
c
o
(A
(0
O
o
V)
—B—
- Charleston
-Atlanta
—A—
- San Antonio
- Nashville
—X—
- Des Moines
—Q--
- Hartford
--0--
- Amarillo
--A--
- Duluth
—©--
- Bismarck
—X—
- Denver
- - -O-
Helena
Boise
- - A-
Las Vegas
-- -O -
- Portland
Fresno
0.00 0.20 0.40 0.60 0.80 1.00 1.20
RUSLE 'LS' Factor
1.40
1.60
1.80
2.00
Analysis of Best Management Practices
for Small Construction Sites
Construction Conditions RUSLE Soil Loss.
Silt\ Soils
Chicago District. U S Arniy 0 ^f Eng
June 1998 rpurc 7
iineers
-------
\ 1 1
300 Acre Watershed
9
a Acr
e vva
xersn
eu
\
/
\
/
\
/
\
/
\
\
/
\
/
f\
/
\
/
k
639 Acre
Watershed
i I
Undisturbed Cell
3 acre cell
Water Cell
Direction of
Drainage
inalyc.c nf Rp«J Mananpmpnt
iin
IB:
1
•1 Practices For Small Construction Sites
AGNPS Hypothetical Watershed
2^21 Figure #8
41
-------
m
-------
15
29
43
57
2
16
30
44
58
~
Undisturbed 3 Acre
Cell
Water Cell
Construction Cell as part
of 1,5 or 10 construction
site scenario
Direction of
Drainage
Reporting Cell for
AGNPS Results
Analysis of Best Management Practices For
Small Construction Sites
AGNPS Hypothetical 300 acre Watershed
Figure #10
Hi
-------
-------
EPA BMP Analysis
Hypothetical 99 Acre Watershed with One 3 acre Construction Site
250
200
150
100
1 Site
Trib
AGNPS Eroscxl Charaes for a Sinale
3 acre Cell Under Constructs
Porooit Increase
Pa-cant* ofTotal
Peromt* ofTotal
Soil vid Slope
Incr in Cell Eroaon
Due to
Erosion Deposited
Eroaicn Yielded
Condition
Due to Construction
Construction
w/in 3aoreCell
From iaczt Cdl
(torn)
(V.)
<*)
(*)
Sand (3%)
3 81
243
88
12
Cliy (3%)
11.02
261
50
50
SiH (3%)
25 87
258
57
43
Sand (7%)
10.56
244
87
13
Clay (7%)
30 5
261
46
54
SiH (7%)
71 56
258
54
46
Sand (12%)
19 68
244
86
14
Clay (12%)
56.83
261
44
56
Sih (12%)
133.33
258
52
48
Sand (18%)
26 9
244
86
14
Clay (18%)
77.69
261
43
57
Sik(l8%)
182.27
258
50
50
Deposition and Yidd Percentagea are
valid for pr^construction and construction ccndibons
A
1 Site
Trib
i
1 Site
Trib
-Q— Very Steep Silt
-©--- Steep Silt
A Rolling Silt
o Flat Silt
-x— Very Steep Clay
-H— Steep Clay
x Rolling Clay
Flat Clay
-a— Very Steep Sand
-©--- Steep Sand
A Rolling Sand
o • Flat Sand
50
10
20
"fri-
....j.
: R-l- 1
Drainage Area (acres)
80
90
100
-------
600
500
400
300
200
100
EPA BMP Analysis
Hypothetical 99 Acre Watershed with Five 3 acre Construction Sites
40 50 60
Drainage Area (acres)
—s— Very Steep Silt
--0-— Steep Silt
A Rolling Silt
o Flat Silt
—x— Very Steep Clay
—-i— steep Clay
x Rolling Clay
Flat Clay
—a— Very Steep Sand
- Steep Sand
A Rolling Sand
... o- - Flat Sand
100
!B.
8?
& °
4
3 fi I J
s If
ii
-------
EPA BMP Analysis
Hypothetical 99 Acre Watershed with Ten 3 acre Construction Sites
1200
U~i
Drainage Area (acres)
100
—B—
- Very Steep Silt
—O--
- Steep Silt
A
Rolling Silt
¦ -Q-
Flat Silt
X—
- Very Steep Clay
- Steep Clay
X
Rolling Clay
Flat Clay
- Very Steep Sand
-d--
- Steep Sand
A
Rolling Sand
- -o -
Flat Sand
$
" o
^ o
II
Ps
I
-------
EPA BMP Analysis
Hypothetical 300 Acre Watershed with One 3 acre Construction Site
160
140
(/)
o 120
60
20
A\
Site*
Trib
AGNPS Eros en Cham a fie to
Erosion Deposited
Erosion Yielded
Condition
EX* to Construction
Construction
w/in 3acre Cell
From 3a
(%)
Sand (3%)
3.81
243
88
12
CUy (3%)
11.02
261
50
50
Sih (3%)
25.87
258
57
43
Sand (7%)
10 56
244
87
13
CUy (7%)
30 5
261
46
54
Sill (7%)
71 56
258
54
46
Sand (12%)
19.68
244
86
14
Clay (12%)
56.83
261
44
56
Sih (12%)
133.33
258
52
48
Sand (18%)
26.9
244
86
14
Clay (18%)
77.69
261
43
57
Sih (18%)
182.27
258
50
50
Deposition snd Yidd Peroertages re
valid for pro-construction snd construction conditions
1 Site
Trib
1 Site
Trib
0 Sites
Trib
V /
0 Sites
Trib
vJ
¦•T"
mm
-o—Very Steep Silt
-
-------
600
500
400
v>
e
o
c
o
o
a
V>
C
O
o
0)
% 300
a>
re
a>
o
c
2
a>
> 200
c
0)
E
0)
to
100
EPA BMP Analysis
Hypothetical 300 Acre Watershed with Five 3 acre Construction Sites
-e— Very Steep Silt
Steep Silt
A Rolling Silt
o Flat Silt
-K— Very Steep Clay
--I— Steep Clay
x Rolling Clay
Flat Clay
-q— Very Steep Sand
Steep Sand
A Rolling Sand
o Flat Sand
50
100 150
Drainage Area (acres)
200
250
300
o
a.
? 5
I £
n
i2
SB 11
> a S w
-i
3 3
*"
a ?
a
8
-------
EPA BMP Analysis
Hypothetical 300 Acre Watershed with Ten 3 acre Construction Sites
1400
S
50
100 150
Drainage Area (
200
250
300
-a— Very Steep Silt
-o— Steep Silt
a Rolling Silt
o - Flat Silt
-x— Very Steep Clay
-H— Steep Clay
x Rolling Clay
Flat Clay
-a— Very Steep Sand
-o—- Steep Sand
A - Rolling Sand
o - Flat Sand
o
3T
Q
^ &
3
p 1
a
1»
I
P
G
3. ?
3 |
t/3
§ |
W O
O P
o jC
3
<
n
u
1
o
II
2- a
1
O
•*>
rt
in o
i
5
-------
EPA BMP Analysis
Hypothetical 639 Acre Watershed with One 3 acre Construction Site
1 Site
Trib
1 Site
Trib
AGNPS Eros on Changes for a Sinflle 3 acre Cdl Under Construction
Percent Increase
Per Gent" of Total
Percent* of Total
Sal md Slope
!nar in Cell Eronon
Due to
Eroaion Deponted
Eroaion Yielded
Condition
Due to Construction
Construction
vf\n 3acreCcll
From 3atre Cell
(tons)
w
(*)
(*)
Sand (3%)
3 81
243
88
12
CUy (3%)
11.02
261
50
50
Silt (3%)
25 87
258
57
43
Sand (7%)
10.56
244
87
13
CUy (7%)
30 5
261
46
54
Silt (7%)
71.56
258
54
46
Sand (12%)
19.68
244
86
14
CUy (12%)
56.83
261
44
56
Sih (12%)
133 33
258
52
48
Sand (18%)
26 9
244
86
14
CUy (18%)
77.69
261
43
57
Silt (18%)
182.27
258
50
50
Deposinon and Yidd Ptrccntagee are vaJid for pre-constnj&ion and construction conAtions
1 1 Site
1 Trib
100
200
300 400
Drainage Area (acres)
500
600
~
- Very Steep Silt
—O--
- Steep Silt
A
Rolling Silt
Flat Silt
—X—
- Very Steep Clay
—4--
-Steep Clay
X
Rolling Clay
Flat Clay
- Very Steep Sand
—o--
- Steep Sand
- A
Rolling Sand
- o-
- Flat Sand
700
a _
1 K
§ =
* 3
Ui E
^ K
I*
€ o
K w
I*
2. 8
o
tl
C/> o
3 ~
-------
EPA BMP Analysis
Hypothetical 639 Acre Watershed with Ten 3 acre Construction Sites
1200
1000
800
(/>
c
o
e
o
u
2
+*
(A
C
o
o
4)
¦i 600
a>
m
10
a>
o
c
2
0)
>: 400
a>
E
a)
a
o 2
Sill
> a n >5
3. g
0 3
3 3
1Si —
1 ?
a
8
-------
APPENDIX 1A
RUSLE RESULTS
Pre-Construction Conditions
-------
Pre-Construction Condition
Pre-
Soil
Constructic
Des Moines, Iowa
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
160
0.10
0.49
0.309
1
2.4
Mod (Clay)
160
0.27
0.49
0.309
1
6.5
High (Silt)
160
0.64
0.49
0.309
1
15.3
7% slope, 140' length
Low (Sand)
160
0.10
1.06
0.309
1
5.2
Mod (Clay)
160
0.27
1.06
0.309
1
14.1
High (Silt)
160
0.64
1.06
0.309
1
33.5
12% slope, 100' length
Low (Sand)
160
0.10
1.79
0.309
1
8.8
Mod (Clay)
160
0.27
1.79
0.309
1
23.9
High (Silt)
160
0.64
1.79
0.309
1
56.6
18% slope, 50' length
Low (Sand)
160
0.10
1.98
0.309
1
9.8
Mod (Clay)
160
0.27
1.98
0.309
1
26.4
High (Silt)
160
0.64
1.98
0.309
1
62.6
Pre-
Soil
Construction
Helena, Montana
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200" length
Low (Sand)
14
0.10
0.49
0.160
1
0.1
Mod (Clay)
14
0.27
0.49
0.160
1
0.3
High (Silt)
14
0.64
0.49
0.160
1
0.7
7% slope, 140' length
Low (Sand)
14
0.10
1.06
0.160
1
0.2
Mod (Clay)
14
0.27
1.06
0.160
1
0.6
High (Silt)
14
0.64
1.06
0.160
1
1.5
12% slope, 100' length
Low (Sand)
14
0.10
1.79
0.160
1
0.4
Mod (Clay)
14
0.27
1.79
0.160
1
1.1
High (Silt)
14
0.64
1.79
0.160
1
2.6
18% slope, 50' length
Low (Sand)
14
0.10
1.98
0.160
1
0.4
Mod (Clay)
14
0.27
1.98
0.160
1
1.2
High (Silt)
14
0.64
1.98
0.160
1
2.8
Pre-
Soil
Construction
Duluth, Minnesota
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
95
0.10
0.49
0.225
1
1.0
Mod (Clay)
95
0.27
0.49
0.225
1
2.8
High (Silt)
95
0.64
0.49
0.225
1
6.6
7% slope, 140' length
Low (Sand)
95
0.10
1.06
0.225
1
2.3
Mod (Clay)
95
0.27
1.06
0.225
1
6.1
High (Silt)
95
0.64
1.06
0.225
1
14.5
12% slope, 100' length
Low (Sand)
95
0.10
1.79
0.225
1
3.8
Mod (Clay)
95
0.27
1.79
0.225
1
10.3
I High (Silt)
95
0.64
1.79
0.225
1
24.5
18% slope, 50" length | Low (Sand)
95
0.10
1.98
0.225
1
4.2
Mod (Clay)
95
0.27
1.98
0.225
1
11.4
High (Silt)
95
0.64
1.98
0.225
1
27.1
-------
Pre-Construction Condition
Pre-
Soil
Construction
Bismarck, North Dakota
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
50
0.10
0.49
0.206
1
0.5
Mod (Clay)
50
0.27
0.49
0.206
1
1.3
High (Silt)
50
0.64
0.49
0.206
1
3.2
7% slope, 140" length
Low (Sand)
50
0.10
1.06
0.206
1
1.1
Mod (Clay)
50
0.27
1.06
0.206
1
2.9
High (Silt)
50
0.64
1.06
0.206
1
7.0
12% slope, 100' length
Low (Sand)
50
0.10
1.79
0.206
1
1.8
Mod (Clay)
50
0.27
1.79
0.206
1
5.0
High (Silt)
50
0.64
1.79
0.206
1
11.8
18% slope, 50' length
Low (Sand)
50
0.10
1.98
0.206
1
2.0
Mod (Clay)
50
0.27
1.98
0.206
1
5.5
High (Silt)
50
0.64
1.98
0.206
1
13.0
Pre-
Soil
Construction
Denver, Colorado
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
40
0.10
0.49
0.214
1
0.4
Mod (Clay)
40
0.27
0.49
0.214
1
1.1
High (Silt)
40
0.64
0.49
0.214
1
2.7
7% slope, 140" length
Low (Sand)
40
0.10
1.06
0.214
1
0.9
Mod (Clay)
40
0.27
1.06
0.214
1
2.5
High (Silt)
40
0.64
1.06
0.214
1
5.8
12% slope, 100' length
Low (Sand)
40
0.10
1.79
0.214
1
1.5
Mod (Clay)
40
0.27
1.79
0.214
1
4.1
High (Silt)
40
0.64
1.79
0.214
1
9.8
18% slope, 50* length
Low (Sand)
40
0.10
1.98
0.214
1
1.7
Mod (Clay)
40
0.27
1.98
0.214
1
4.6
High (Silt)
40
0.64
1.98
0.214
1
10.9
Pre-
Soil
Construction
Boise, Idaho
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
12
0.10
0.49
0.143
1
0.1
Mod (Clay)
12
0.27
0.49
0.143
1
0.2
High (Silt)
12
0.64
0.49
0.143
1
0.5
7% slope, 140' length
Low (Sand)
12
0.10
1.06
0.143
1
0.2
Mod (Clay)
12
0.27
1.06
0.143
1
0.5
High (Silt)
12
0.64
1.06
0.143
1
1.2
12% slope, 100' length
Low (Sand)
12
0.10
1.79
0.143
1
0.3
Mod (Clay)
12
0.27
1.79
0.143
1
0.8
High (Silt)
12
0.64
1.79
0.143
1
2.0
18% slope, 50' length
Low (Sand)
12
0.10
1.98
0.143
1
0.3
Mod (Clay)
12
0.27
1.98
0.143
1
0.9
High (Silt)
12
0.64
1.98
0.143
1
2.2
-------
Pre-Constaiction Condition
P re-
Soil
Const ructid
Nashville, Tennessee
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
225
0.10
0.49
0.340
1
3.7
Mod (Clay)
225
0.27
0.49
0.340
1
10.0
High (Silt)
225
0.64
0.49
0.340
1
23.7
7% slope, 140' length
Low (Sand)
225
0.10
1.06
0.340
1
8.1
Mod (Clay)
225
0.27
1.06
0.340
1
21.9
High (Silt)
225
0.64
1.06
0.340
1
51.9
12% slope, 100" length
Low (Sand)
225
0.10
1.79
0.340
1
13.7
Mod (Clay)
225
0.27
1.79
0.340
1
37.0
High (Silt)
225
0.64
1.79
0.340
1
87.6
18% slope, 50' length
Low (Sand)
225
0.10
1.98
0.340
1
15.1
Mod (Clay)
225
0.27
1.98
0.340
1
40.9
High (Silt)
225
0.64
1.98
0.340
1
96.9
P re-
Soil
Const ruction
Hartford, Connecticut
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
130
0.10
0.49
0.283
1
1.8
Mod (Clay)
130
0.27
0.49
0.283
1
4.8
High (Silt)
130
0.64
0.49
0.283
1
11.4
7% slope, 140' length
Low (Sand)
130
0.10
1.06
0.283
1
3.9
Mod (Clay)
130
0.27
1.06
0.283
1
10.5
High (Silt)
130
0.64
1.06
0.283
1
24.9 -
12% slope, 100" length
Low (Sand)
130
0.10
1.79
0.283
1
6.6
Mod (Clay)
130
0.27
1.79
0.283
1
17:8
High (Silt)
130
0.64
1.79
0.283
1
42.1
18% slope, 50' length
Low (Sand)
130
0.10
1.98
0.283
1
7.3
Mod (Clay)
130
0.27
1.98
0.283
1
19.7
High (Silt)
130
0.64
1.98
0.283
1
46.6
Pre-
Soil
Const ruction
Atlanta, Georgia
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
295
0.10
0.49
0.340
1
4.9
Mod (Clay)
295
0.27
0.49
0.340
1
13.1
High (Silt)
295
0.64
0.49
0.340
1
31.2
7% slope, 140' length
Low (Sand)
295
0.10
1.06
0.340
1
10.6
Mod (Clay)
295
0.27
1.06
0.340
1
28.7
High (Silt)
295
0.64
1.06
0.340
1
68.1
12% slope, 100' length
Low (Sand)
295
0.10
1.79
0.340
1
18.0
Mod (Clay)
295
0.27
1.79
0.340
1
48.5
High (Silt)
295
0.64
1.79
0.340
1
115.0
18% slope, 50' length
Low (Sand)
295
0.10
1.98
0.340
1
19.9
Mod (Clay)
295
0.27
1.98
0.340
1
53.7
High (Silt)
295
0.64
1.98
0.340
1
127.2
-------
Pre-Construction Condition
Pre-
Soil
Construction
Las Vegas, Nevada
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
8
0.10
0.49
0.035
1
0.0
Mod (Clay)
8
0.27
0.49
0.035
1
0.0
High (Silt)
8
0.64
0.49
0.035
1
0.1
7% slope, 140' length
Low (Sand)
8
0.10
1.06
0.035
1
0.0
Mod (Clay)
8
0.27
1.06
0.035
1
0.1
High (Silt)
8
0.64
1.06
0.035
1
0.2
12% slope, 100'length
Low (Sand)
00
o
o
1.79
0.035
1
0.1
Mod (Clay)
8 0.27
1.79
0.035
1
0.1
High (Silt)
8 0.64
1.79
0.035
1
0.3
18% slope, 50' length
Low (Sand)
8 0.10
1.98
0.035
1
0.1
Mod (Clay)
8 0.27
1.98
0.035
1
0.2
High (Silt)
8 0.64
1.98
0.035
1
0.4
Pre-
Soil
Construction
Portland, Oregon
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
65
0.10
0.49
0.228
1
0.7
Mod (Clay)
65
0.27
0.49
0.228
1
1.9
High (Silt)
65
0.64
0.49
0.228
1
4.6
7% slope, 140' length
Low (Sand)
65 ! 0.10
1.06
0.228
1
1.6
Mod (Clay)
65 0.27
1.06
0.228
1
4.2
High (Silt)
65 i 0.64
1.06
0.228
1
10.1
12% slope, 100' length
Low (Sand)
65
0.10
1.79
0.228
1
2.7
Mod (Clay)
65
0.27
1.79
0.228
1
7.2
High (Silt)
65 ! 0.64
1.79
0.228
1
17.0
18% slope, 50' length
Low (Sand)
65 ! 0.10
1.98
0.228
1
2.9
Mod (Clay)
65
0.27
1.98
0.228
1
7.9
High (Silt)
65
0.64
1.98
0.228
1
18.8
Pre-
Soil
Construction
Fresno, California
Erodibility
R
K
LS
C
P
A (tons/ac)
3% slope, 200' length
Low (Sand)
12
0.10
0.49
0.113
1
0.1
Mod (Clay)
12
0.27
0.49
0.113
1
0.2
High (Silt)
12
0.64
0.49
0.113
1
0.4
7% slope, 140' length
Low (Sand)
12
0.10
1.06
0.113
1
0.1
Mod (Clay)
12
0.27
1.06
0.113
1
0.4
High (Silt)
12
0.64
1.06
0.113
1
0.9
12% slope, 100' length
Low (Sand)
12
0.10
1.79
0.113
1
0.2
Mod (Clay)
12
0.27
1.79
0.113
1
0.7
High (Silt)
12
0.64
1.79
0.113
1
1.6
18% slope, 50' length
Low (Sand)
12 I 0.10
1.98
0.113
1
0.3
Mod (Clay)
12 j 0.27
1.98
0.113
1
0.7
High (Silt)
12 i 0.64
1.98
0.113
1
1.7
(p J
-------
APPENDIX IB
RUSLE RESULTS
Construction Conditions with
No Best Management Practices
-------
RUSLE Construction Conditions
Construction
Soil
Construction K & C
no BMPs
Des Moines, Iowa
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
160
0.49
1
0.12
0.885
8.2
Mod (Clay)
160
0.49
1
0.34
0.885
23.3
High (Silt)
160
0.49
1
0.80
0.885
54.9
7% slope, 140' length
Low (Sand)
160
1.06
1
0.12
0.885
18.0
Mod (Clay)
160
1.06
1
0.34
0.885
51.0
High (Silt)
160
1.06
1
0.80
0.885
120.0
12% slope, 100" length
Low (Sand)
160
1.79
1
0.12
0.885
30.4
Mod (Clay)
160
1.79
1
0.34
0.885
86.1
High (Silt)
160
1.79
1
0.80
0.885
202.7
18% slope, 50' length
Low (Sand)
160
1.98
1
0.12
0.885
33.6
Mod (Clay)
160
1.98
1
0.34
0.885
95.3
High (Silt)
160
1.98
1
0.80
0.885
224.2
Construction
Soil
Construction K & C
no BMPs
Helena, Montana
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
14
0.49
1
0.12
0.827
0.7
Mod (Clay)
14
0.49
1
0.34
0.827
1.9
High (Silt)
14
0.49
1
0.80
0.827
4.5
7% slope, 140* length
Low (Sand)
14
1.06
1
0.12
0.827
1.5
Mod (Clay)
14
1.06
1
0.34
0.827
4.2
High (Silt)
14
1.06
1
0.80
0.827
9.8
12% slope, 100' length
Low (Sand)
14
1.79
1
0.12
0.827
2.5
Mod (Clay)
14
1.79
1
0.34
0.827
7.0
High (Silt)
14
1.79
1
0.80
0.827
16.6
18% slope, 50* length
Low (Sand)
14
1.98
1
0.12
0.827
2.8
Mod (Clay)
14
1.98
1
0.34
0.827
7.8
High (Silt)
14
1.98
1
0.80
0.827
18.3
Construction
Soil
Construction K & C
no BMPs
Duluth, Minnesota
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
95
0.49
1
0.12
0.873
4.8
Mod (Clay)
95
0.49
1
0.34
0.873
13.7
High (Silt)
95
0.49
1
0.80
0.873
32.2
7% slope, 140' length
Low (Sand)
95
1.06
1
0.12
0.873
10.5
Mod (Clay)
95
1.06
1
0.34
0.873
29.9
High (Silt)
95
1.06
1
0.80
0.873
70.3
12% slope, 100' length
Low (Sand)
95
1.79
1
0.12
0.873
17.8
Mod (Clay)
95
1.79
1
0.34
0.873
50.5
High (Silt)
95
1.79
1
0.80
0.873
118.7
18% slope, 50' length
Low (Sand)
95
1.98
1
0.12
0.873
19.7
Mod (Clay)
95
1.98
1
0.34
0.873
55.8
High (Silt)
95
1.98
1
0.80
0.873
131.4
-------
RUSLE Construction Conditions
Construction
Soil
Construction K & C
no BMPs
Bismarck, North Dakota
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
50
0.49
1
0.12
0.844
2.5
Mod (Clay)
50
0.49
1
0.34
0.844
7.0
High (Silt)
50
0.49
1
0.80
0.844
16.4
7% slope, 140' length
Low (Sand)
50
1.06
1
0.12
0.844
5.4
Mod (Clay)
50
1.06
1
0.34
0.844
15.2
High (Silt)
50
1.06
1
0.80
0.844
35.8
12% slope, 100' length
Low (Sand)
50
1.79
1
0.12
0.844
9.1
Mod (Clay)
50
1.79
1
0.34
0.844
25.7
High (Silt)
50
1.79
1
0.80
0.844
60.5
18% slope, 50' length
Low (Sand)
50
1.98
1
0.12
0.844
10.0
Mod (Clay)
50
1.98
1
0.34
0.844
28.4
High (Silt)
50
1.98
1
0.80
0.844
66.9
Construction
Soil
Construction K & C
no BMPs
Denver, Colorado
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
40
0.49
1
0.12
0.841
2.0
Mod (Clay)
40
0.49
1
0.34
0.841
5.5
High (Silt)
40
0.49
1
0.80
0.841
13.0
7% slope, 140' length
Low (Sand)
40
1.06
1
0.12
0.841
4.3 1
Mod (Clay)
40
1.06
1
0.34
0.841
12.1
High (Silt)
40
1.06
1
0.80
0.841
28.5
12% slope, 100' length
Low (Sand)
40
1.79
1
0.12
0.841
7.2
Mod (Clay)
40
1.79
1
0.34
0.841
20.5
High (Silt)
40
1.79
1
0.80
0.841
48.2
18% slope, 50' length
Low (Sand)
40
1.98
1
0.12
0.841
8.0
Mod (Clay)
40
1.98
1
0.34
0.841
22.6
High (Silt)
40
1.98
1
0.80
0.841
53.3
Construction
Soil
Construction K & C
no BMPs
Boise, Idaho
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
12
0.49
1
0.12
0.818
0.6
Mod (Clay)
12
0.49
1
0.34
0.818
1.6
High (Silt)
12
0.49
1
0.80
0.818
3.8
7% slope, 140' length
Low (Sand)
12
1.06
1
0.12
0.818
1.2
Mod (Clay)
12
1.06
1
0.34
0.818
3.5
High (Silt)
12
1.06
1
0.80
0.818
8.3
12% slope, 100Mength
Low (Sand)
12
1.79
1
0.12
0.818
2.1
Mod (Clay)
12
1.79
1
0.34
0.818
6.0
High (Silt)
12
1.79
1
0.80
0.818
14.1
18% slope, 50' length
Low (Sand)
12
1.98
1
0.12
0.818
2.3 J
Mod (Clay)
12
1.98
1
0.34
0.818
6.6
High (Silt)
12
1.98 ! 1
0.80
0.818
15.5
-------
RUSLE Construction Conditions
Construction
Soil
Construction K & C
no BMPs
Nashville, Tennessee
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
225
0.49
1
0.12
0.891
11.7
Mod (Clay)
225
0.49
1
0.34
0.891
33.1
High (Silt)
225
0.49
1
0.80
0.891
77.8
7% slope, 140' length
Low (Sand)
225
1.06
1
0.12
0.891
25.5
Mod (Clay)
225
1.06
1
0.34
0.891
72.2
High (Silt)
225
1.06
1
0.80
0.891
170.0
12% slope, 100' length
Low (Sand)
225
1.79
1
0.12
0.891
43.1
Mod (Clay)
225
1.79
1
0.34
0.891
122.0
High (Silt)
225
1.79
1
0.80
0.891
287.0
18% slope, 50' length
Low (Sand)
225
1.98
1
0.12
0.891
47.6
Mod (Clay)
225
1.98
1
0.34
0.891
134.9
High (Silt)
225
1.98
1
0.80
0.891
317.5
Construction
Soil
Construction K & C
no BMPs
Hartford, Connecticut
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
130
0.49
1
0.12
0.878
6.6
Mod (Clay)
130
0.49
1
0.34
0.878
18.8
High (Silt)
130
0.49
1
0.80
0.878
44.3
7% slope, 140' length
Low (Sand)
130
1.06
1
0.12
0.878
14.5
Mod (Clay)
130
1.06
1
0.34
0.878
41.2
High (Silt)
130
1.06
1
0.80
0.878
96.8
12% slope, 100' length
Low (Sand)
130
1.79
1
0.12
0.878
24.5
Mod (Clay)
130
1.79
1
0.34
0.878
69.5
High (Silt)
130
1.79
1
0.80
0.878
163.5
18% slope, 50' length
Low (Sand)
130
1.98
1
0.12
0.878
27.1
Mod (Clay)
130
1.98
1
0.34
0.878
76.9
High (Silt)
130
1.98
1
0.80
0.878
180.9
Construction
Soil
Construction K & C
no BMPs
Atlanta, Georgia
Erodibility
,R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
295
0.49
1
0.12
0.898
15.4
Mod (Clay)
295
0.49
1
0.34
0.898
43.7
High (Silt)
295
0.49
1
0.80
0.898
102.8
7% slope, 140' length
Low (Sand)
295
1.06
1
0.12
0.898
33.7
Mod (Clay)
295
1.06
1
0.34
0.898
95.5
High (Silt)
295
1.06
1
0.80
0.898
224.6
12% slope, 100' length
Low (Sand)
295
1.79
1
0.12
0.898
56.9
Mod (Clay)
295
1.79
1
0.34
0.898
161.2
High (Silt)
295
1.79
1
0.80
0.898
379.3
18% slope, 50' length
Low (Sand)
295
1.98
1
0.12
0.898
62.9
Mod (Clay)
295
1.98
1
0.34
0.898
178.3
High (Silt)
295
1.98 ! 1
0.80
0.898
419.5
-------
RUSLE Construction Conditions
Const ructicu
.
Soil
Construction K & C
no BMPs
Charleston, South Carolina
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200* length
Low (Sand)
400
0.49
1
0.12
0.917
21.3
Mod (Clay)
400
0.49
1
0.34
0.917
60.5
High (Silt)
400
0.49
1
0.80
0.917
142.3
7% slope, 140' length
Low (Sand)
400
1.06
1
0.12
0.917
46.6
Mod (Clay)
400
1.06
1
0.34
0.917
132.2
High (Silt)
400
1.06
1
0.80
0.917
311.0
12% slope, 100' length
Low (Sand)
400
1.79
1
0.12
0.917
78.8
Mod (Clay)
400
1.79
1
0.34
0.917
223.2
High (Silt)
400
1.79
1
0.80
0.917
525.1
18% slope, 50' length
Low (Sand)
400
1.98
1
0.12
0.917
87.1
Mod (Clay)
400
1.98
1
0.34
0.917
246.9
High (Silt)
400
1.98
1
0.80
0.917
580.9
Const ruction
Soil
Construction K & C
no BMPs
Amarillo, Texas
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
100
0.49
1
0.12
0.860
5.0
Mod (Clay)
100
0.49
1
0.34
0.860
14.2
High (Silt)
100
0.49
1
0.80
0.860
33.3
7% slope, 140" length
Low (Sand)
100
1.06
1
0.12
0.860
.10.9
Mod (Clay)
100
1.06
1
0.34
0.860
31.0
High (Silt)
100
1.06
1
0.80
0.860
72.9
12% slope, 100' length
Low (Sand)
100
1.79
1
0.12
0.860
18.5
Mod (Clay)
100
1.79
1
0.34
0.860
52.3
High (Silt)
100
1.79
1
0.80
0.860
123.1
18% slope, 50' length
Low (Sand)
100
1.98
1
0.12
0.860
20.4
Mod (Clay)
100
1.98
1
0.34
0.860
57.9
High (Silt)
100
1.98
1
0.80
0.860
136.1
Construction
Soil
Construction K & C
no BMPs
San Antonio, Texas
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
250
0.49
1
0.12
0.877
12.8
Mod (Clay)
250
0.49
1
0.34
0.877
36.2
High (Silt)
250
0.49
1
0.80
0.877
85.1
7% slope, 140" length
Low (Sand)
250
1.06
1
0.12
0.877
27.9
Mod (Clay)
250
1.06
1
0.34
0.877
79.0
High (Silt)
250
1.06
1
0.80
0.877
185.9
12% slope, 100' length
Low (Sand)
250
1.79
1
0.12
0.877
47.1
Mod (Clay)
250
1.79
1
0.34
0.877
133.5
High (Silt)
250
1.79
1
0.80
0.877
314.0
18% slope, 50' length
Low (Sand)
250
1.98
1
0.12
0.877
52.1
Mod (Clay)
250
1.98
1
0.34
0.877
147.6
High (Silt)
250
1.98
1
0.80
0.877
347.3
(0*
-------
RUSLE Construction Conditions
Construction
Soil
Construction K & C
no BMPs
Las Vegas, Nevada
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
8
0.49
1
0.12
0.809
0.4
Mod (Clay)
8
0.49
1
0.34
0.809
1.1
High (Silt)
8
0.49
1
0.80
0.809
2.5
7% slope, 140' length
Low (Sand)
8
1.06
1
0.12
0.809
0.8
Mod (Clay)
8
1.06
1
0.34
0.809
2.3
High (Silt)
8
1.06
1
0.80
0.809
5.5
12% slope, 100" length
Low (Sand)
8
1.79
1
0.12
0.809
1.4
Mod (Clay)
8
1.79
1
0.34
0.809
3.9
High (Silt)
8
1.79
1
0.80
0.809
9.3
18% slope, 50' length
Low (Sand)
8
1.98
1
0.12
0.809
1.5
Mod (Clay)
8
1.98
1
0.34
0.809
4.4
High (Silt)
8
1.98
1
0.80
0.809
10.3
Construction
Soil
Construction K & C
no BMPs
Portland, Oregon
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200* length
Low (Sand)
65
0.49
1
0.12
0.864
3.3
Mod (Clay)
65
0.49
1
0.34
0.864
9.3
High (Silt)
65
0.49
1
0.80
0.864
21.8
7% slope, 140' length
Low (Sand)
65
1.06
1
0.12
0.864
7.1
Mod (Clay)
65
1.06
1
0.34
0.864
20.2
High (Silt)
65
1.06
1
0.80
0.864
47.6
12% slope, 100' length
Low (Sand)
65
1.79
1
0.12
0.864
12.1
Mod (Clay)
65
1.79
1
0.34
0.864
34.2
High (Silt)
65
1.79
1
0.80
0.864
80.4
18% slope, 50" length
Low (Sand)
65
1.98
1
0.12
0.864
13.3
Mod (Clay)
65
1.98
1
0.34
0.864
37.8
High (Silt)
65
1.98
1
0.80
0.864
89.0
Construction
Soil
Construction K & C
no BMPs
Fresno, California
Erodibility
R
LS
P
K
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
12
0.49
0.12
0.822
0.6
Mod (Clay)
12
0.49
1
0.34
0.822 '
1.6
High (Silt)
12
0.49
1
0.80
0.822
3.8
7% slope, 140' length
Low (Sand)
12
1.06
1
0.12
0.822
1.3
Mod (Clay)
12
1.06
1
0.34
0.822
3.6
High (Silt)
12
1.06
1
0.80
0.822
8.4
12% slope, 100" length
Low (Sand)
12
1.79
1
0.12
0.822
2.1
Mod (Clay)
12
1.79
1
0.34
0.822
6.0
High (Silt)
12
1.79
1
0.80
0.822
14.1
18% slope, 50' length
Low (Sand)
12
1.98
1
0.12
0.822
2.3
Mod (Clay)
12
1.98
1
0.34
0.822
6.6
High (Silt) I 12
1.98
1
0.80
0.822
15.6
-------
APPENDIX 1C
RUSLE RESULTS
Construction Conditions with
Seeding and Seeding Combined With Mulching
-*} o
-------
RUSLE -Results - Construction Conditions with Seeding and with Seeding and Mulching Combined
|
Constructon
Constructon
Soil
Constructon
with Seeding
w/Seeding+Mulching
Des Moines, Iowa
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
160
0.49
0.12
0.643
6.0
0.451
4.2
Mod (Clay)
160
0.49
0.34
0.643
17.0
0.451
11.9
High (Silt)
160
0 49
0 80
0.643
39 9
0.451
28.0
7% slope, 140' length
Low (Sand)
160
1.06
0.12
0.643
13.1
0.451
9.2
Mod (Clay)
160
1 06
0.34
0.643
37.1
0.451
26.0
High (Silt)
160
1.06
0.80
0.643
87.3
0.451
61.2
12% slope, 100' length
Low (Sand)
160
1.79
0.12
0.643
22.1
0.451
15.5
Mod (Clay)
160
1.79
0.34
0.643
62.6
0.451
43.9
High (Silt)
160
1.79
0.80
0.643
147.3
0.451
103.4
18% slope, 50' length
Low (Sand)
160
1 98
0.12
0.643
24.4
0.451
17.1
Mod (Clay)
160
1.98
0 34
0.643
69.3
0.451
48.6
High (Silt)
160
1 98
0 80
0.643
163.0
0.451
114.3
Constructon
Construction
Soil
Constructon
with Seeding
w/Seeding+Mulching
Helena, Montana
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
14
0 49
0.12
0.655
0.5
0.379
0.3
Mod (Clay)
14
0.49
0.34
0.655
1.5
0.379
0.9
High (Silt)
14
0 49
0.80
0 655
3.6
0.379
2.1
7% slope, 140' length
Low (Sand)
14
1 06
0.12
0 655
1 2
0.379
0.7
Mod (Clay)
14
1 06
0.34
0.655
3.3
0 379
1.9
High (Silt)
14
1 06
0.80
0.655
78
0.379
45
12% slope, 100' length
Low (Sand)
14
1.79
0.12
0 655
20
0 379
1.1
Mod (Clay)
14
1 79
0 34
0.655
5.6
0.379
3.2
High (Silt)
14
1 79
0 80
0.655
13.1
0.379
7.6
18% slope, 50' length
Low (Sand)
14
1 98
0 12
0.655
2.2
0 379
1.3
Mod (Clay)
14
1.98
0.34
0.655
6.2
0.379
3.6
High (Silt)
14
1.98
0.80
0.655
14.5
0.379
8.4
Construction
Constructon
Soil
Constructon
with Seeding
w/Seeding+Mulching
Duluth, Minnesota
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
95
0.49
0.12
0.666
3.7
0.362
2.0
Mod (Clay)
95
0.49
0 34
0 666
10.4
0.362
5.7
High (Silt)
95
0.49
0 80
0 666
24.5
0.362
13.3
7% slope, 140' length
Low (Sand)
95
1.06
0 12
0.666
8.0
0.362
4.4
Mod (Clay)
95
1 06
0.34
0.666
22.8
0.362
12.4
High (Silt)
95
1.06
0.80
0.666
53.6
0.362
29.2
12% slope, 100' length
Low (Sand)
95
1.79
0.12
0.666
13.6
0.362
74
Mod (Clay)
95
1.79
0 34
0.666
38.5
0.362
20.9
High (Silt)
95
1.79
0 80
0 666
90.6
0.362
49.3
18% slope, 50' length
Low (Sand)
95
1 98
0.12
0.666
15.0
0.362
8.2
Mod (Clay)
95
1 98
0.34
0.666
42.6 •
0.362
23.2
High (Silt)
95
1 98
0 80
0 666
100.2
0.362 1 54.5
-u
-------
RUSLE~Results - Construction Conditions with Seeding and wrth Seeding and Mulching Combined
Construction
Construction
Soil
Construction
wrth Seeding
w/Seeding+Mulching
Bismarck, North Dakota
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
50
0 49
0.12
0.655
1.9
0.345
1.0
Mod (Clay)
50
0.49
0.34
0.655
5.4
0.345
2.8
High (Silt)
50
0.49
0.80
0.655
12.7
0.345
6.7
7% slope, 140' length
Low (Sand)
50
1.06
0.12
0.655
4.2
0.345
2.2
Mod (Clay)
50
1.06
0.34
0.655
11.8
0.345
6.2
High (Silt)
50
1.06
0.80
0.655
27.8
0.345
14.6
12% slope, 100" length
Low (Sand)
50
1.79
0.12
0.655
7.0
0.345
3.7
Mod (Clay)
50
1.79
0.34
0.655
19.9
0.345
10.5
High (Silt)
50
1.79
0.80
0.655
46.9
0.345
24.7
18% slope, 50' length
Low (Sand)
50
1.98
0.12
0.655
7.8
0.345
4.1
Mod (Clay)
50
1.98
0.34
0.655
22.1
0.345
11.6
High (Silt)
50
1.98
0.80
0.655
51.9
0.345
27.4
Construction
Construction
Soil
Construction
with Seeding
w/Seeding+Mulching
Denver, Colorado
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
40
0.49
0.12
0.697
1.6
0.365
0.8
Mod (Clay)
40
0.49
0.34
0.697
4.6
0.365
2.4
High (Silt)
40
0.49
0.80
0.697
10.8
0.365
5.7
7% slope, 140' length
Low (Sand)
40
1.06
0.12
0.697
3.5
0.365
1 _~]
Mod (Clay)
40
1 06
0.34
0.697
10.0
0.365
5.r
High (Silt)
40
1.06
0.80
0.697
23.6
0.365
12.4
12% slope, 100' length
Low (Sand)
40-
1.79
0.12
0.697
6.0
0.365
3.1
Mod (Clay)
40
1.79
0.34
0.697
17.0
0.365
8.9
High (Silt)
40
1.79
0.80
0.697
39.9
0.365
20.9
18% slope, 50" length
Low (Sand)
40
1.98
0.12
0.697
6.6
0.365
3.5
Mod (Clay)
40
1.98
0.34
0.697
18.8
0.365
9.8
High (Silt)
40
1.98
0.80
0.697
44.2
0.365
23.1
Construction
Construction
Soil
Construction
wrth Seeding
w/Seeding+Mulching
Boise, Idaho
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200" length
Low (Sand)
12
0.49
0.12
0.568
0.4
0.442
0.3
Mod (Clay)
12
0.49
0.34
0.568
1.1
0.442
0.9
High (Silt)
12
0.49
0 80
0.568
2.6
0.442
2.1
7% slope, 140' length
Low (Sand)
12
1.06
0.12
0.568
0.9
0.442
0.7
Mod (Clay)
12
1.06
0.34
0.568
2.5
0.442
1.9
High (Silt)
12
1 06
0.80
0.568
5.8
0.442
4.5
12% slope, 100" length
Low (Sand)
12
1.79
0.12
0.568
1.5
0.442
1.1
Mod (Clay)
12
1.79
0.34
0.568
4.1
0.442
3.2
High (Silt)
12
1.79
0.80
0.568
9.8
0.442
7.6
18% slope, 50" length
Low (Sand)
12
1.98
0.12
0.568
1.6
0.442
1.3
Mod (Clay)
12.
1 98
0.34
0.568
4.6
0.442
3.6
High (Silt)
12
1.98 .
0 80
0.568
10.8
0.442
8.4
-)*>
-------
RUSLE-Results - Constructor) Conditions with Seeding and with Seeding and Mulching Combined
|
Construction
Construction
Soil
Construction
with Seeding
w/Seeding+Mulching
Nashville, Tennessee
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
225
0.49
0.12
0.538
70
0.408
5.3
Mod (Clay)
225
0 49
0.34
0 538
20.0
0.408
15.1
High (Silt)
225
0.49
0.80
0.538
47 0
0.408
35.6
7% slope, 140' length
Low (Sand)
225
1.06
0.12
0.538
15.4
0.408
11.7
Mod (Clay)
225
1.06
0.34
0.538
43.6
0.408
33.1
High (Silt)
225
1.06
0.80
0.538
102.7
0.408
77.8
12% slope, 100' length
Low (Sand)
225
1.79
0.12
0.538
26.0
0.408
19.7
Mod (Clay)
225
1.79
0.34
0.538
73.7
0.408
55.9
High (Silt)
225
1.79
0.80
0.538
173.4
0.408
131.5
18% slope, 50' length
Low (Sand)
225
1.98
0.12
0.538
28.8
0.408
21.8
Mod (Clay)
225
1 98
0.34
0.538
81.5
0.408
61.8
High (Silt)
225
1.98
0.80
0 538
191.8
0.408
145.4
Construction
Construction
Soil
Construction
with Seeding
w/Seeding+Mulching
Hartford, Connecticut
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
130
0.49
0.12
0.440
3.3
0.262
2.0
Mod (Clay)
130
0.49
0 34
0 440
94
0.262
5.6
High (Silt)
130
0 49
0.80
0.440
22.2
0.262
13.2
7% slope, 140' length
Low (Sand)
130
1.06
0.12
0.440
7.3
0.262
4.3
Mod (Clay)
130
1 06
0.34
0.440
20.6
0.262
12.3
High (Silt)
130
1.06
0.80
0.440
48.5
0.262
28.8
12% slope, 100' length
Low (Sand)
130
1.79
0 12
0.440
123
0.262
7.3
Mod (Clay)
130
1.79
0.34
0.440
34 8
0.262
20.7
High (Silt)
130
1 79
0 80
0 440
81 9
0.262
48.7
18% slope, 50' length
Low (Sand)
130
1 98
0.12
0 440
13.6
0.262
8.1
Mod (Clay)
130
1 98
0.34
0.440
38.5
0.262
22.9
High (Silt)
130
1.98
0 80
0 440
90 5
0.262
53.8
Constructon
Construction
Soil
Constructon
with Seeding
w/Seeding+Mulching
Atlanta, Georgia
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
295
0.49
0.12
0 578
9.9
0.385
6.6
Mod (Clay)
295
0 49
0.34
0.578
28 1
0.385
18.7
High (Silt)
295
0 49
0.80
0.578
66.1
0.385
44.0
7% slope, 140' length
Low (Sand)
295
1 06
0.12
0.578
21 7
0.385
14.4
Mod (Clay)
295
1 06
0.34
0.578
61.4
0.385
40.9
High (Silt)
295
1 06
0.80
0 578
144 5
0.385
96.3
12% slope, 100' length
Low (Sand)
295
1 79
0.12
0 578
36.6
0.385
24.4
Mod (Clay)
295
1.79
0.34
0 578
103.7
0.385
69.1
High (Silt)
295
1.79
0 80
0.578
244.0
0.385
162.6
18% slope, 50' length
Low (Sand)
295
1 98
0.12
0 578
40.5
0.385
27.0
Mod (Clay)
295
1.98
0.34
0.578
114.7
0.385
76.4
High (Silt)
295
1 98
0.80
0.578 | 269 9
0 385
179.8
-1"*
-------
RUSLE Results - Constructor! Conditions with Seeding and with Seeding and Mulching Combined
I
|
|
Construction
Construction
Soil
Construction
with Seeding
w/Seeding+ Mulching
Charleston, South Carolina
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200" length
Low (Sand)
400
0.49
0.12
0.546
12.7
0.295
6.9
Mod (Clay)
400
0.49
0.34
0.546
36.0
0.295
19.4
High (Silt)
400
0.49
0.80
0.546
84.7
0.295
45.7
7% slope, 140" length
Low (Sand)
400
1.06
0.12
0.546
27.8
0.295
15.0
Mod (Clay)
400
1.06
0.34
0.546
78.7
0.295
42.5
High (Silt)
400
1.06
0.80
0.546
185.2
0.295
100.0
12% slope, 100' length
Low (Sand)
400
1.79
0.12
0.546
46.9
0.295
25.3
Mod (Clay)
400
1 79
0.34
0.546
132.9
0.295
71.7
High (Silt)
400
1.79
0.80
0.546
312.7
0.295
168.8
18% slope, 50' length
Low (Sand)
400
1.98
0.12
0.546
51.9
0.295
28.0
Mod (Clay)
400
1 98
0.34
0.546
147.0
0.295
79 4
High (Silt)
400
1 98
0.80
0.546
345.9
0.295
186.7
Constructon
Construction
Soil
Construction
with Seeding
w/Seeding+Mulching
Amarillo, Texas
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200" length
Low (Sand)
. 100
0.49
0.12
0.573
3.3
0.408
2.4
Mod (Clay)
100
0.49
0.34
0.573
9.5
0.408
6.7
High (Silt)
100
0.49
0.80
0.573
22.2
0.408
15.8
7% slope, 140" length
Low (Sand)
100
1 06
0 12
0.573
7.3
0.408
5,
Mod (Clay)
100
1.06
0.34
0.573
20.7
0.408
U
High (Silt)
100
1 06
0.80
0.573
48.6
0.408
34.8
12% slope, 100' length
Low (Sand)
100
1.79
0.12
0.573
12.3
0.408
8.8
Mod (Clay)
100
1 79
0.34
0.573
34.9
0.408
24.9
High (Silt)
100
1 79
0.80
0.573
82.1
0.408
58.5
18% slope, 50' length
Low (Sand)
100
1 98 I 0.12
0.573
136
0.408
9.7
Mod (Clay)
100
1.98
0 34
0.573
38.6
0.408
27.5
High (Silt)
100
1.98
0.80
0.573
90.8
0.408
64.7
Construction
Construction
Soil
Construction
with Seeding
w/Seeding+M ulching
San Antonio, Texas
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
250
0.49
0.12
0.536
7.8
0.434
6.3
Mod (Clay)
250
0.49
0.34
0.536
22.1
0.434
17.9
High (Silt)
250
0.49
0.80
0.536
52.0
0.434
42.1
7% slope, 140' length
Low (Sand)
250
1.06
0.12
0.536
17.1
0.434
13.8
Mod (Clay)
250
1 06
0.34
0.536
48.3
0.434
39.1
High (Silt)
250
1.06
0.80
0.536
113.7
0.434
91.9
12% slope, 100' length
Low (Sand)
250
1.79
0.12
0.536
28.8
0.434
23.3
Mod (Clay)
250
1.79
0.34
0.536
81.6
0.434
66.0
High (Silt)
250
1.79
0.80
0.536
192.0
0.434
155.2
18% slope, 50" length
Low (Sand)
250
1.98
0.12
0.536
31.9
0.434
25.8
Mod (Clay)
250
1 98
0.34
0.536
90.3
0.434
73.0
High (Silt)
250
1 98 I 0.80
0.536
212.4
0.434
171J
•i i
-------
RUSLE'Resutts - Constructor! Conditions with Seeding and with Seeding and Mulching Combined
|
Construction
Construction
Soil
Construction
with Seeding
w/Seeding+Mulching
Las Vegas, Nevada
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
8
0 49
0.12
0 458
0.2
0.139
0.1
Mod (Clay)
8
0.49
0.34
0.458
0.6
0.139
0.2
High (Silt)
8
0 49
0 80
0 458
1 4
0.139
0.4
7% slope, 140" length
Low (Sand)
8
1.06
0.12
0.458
0.5
0.139
0.1
Mod (Clay)
8
1.06
0.34
0.458
1.3
0.139
0.4
High (Silt)
8
1 06
0.80
0.458
3.1
0.139
0.9
12% slope, 100' length
Low (Sand)
8
1.79
0.12
0.458
0.8
0.139
0.2
Mod (Clay)
8
1.79
0 34
0.458
2.2
0.139
0.7
High (Silt)
8
1.79
0.80
0.458
5.2
0.139
1.6
18% slope, 50" length
Low (Sand)
8
1.98
0.12
0.458
0.9
0.139
0.3
Mod (Clay)
8
1 98
0.34
0 458
2.5
0.139
0.7
High (Silt)
8
1 98
0 80
0 458
5.8
0.139
1.8
Construction
Construction
Soil
Construction
with Seeding
w/Seeding+Mulching
Portland, Oregon
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
65
0 49
0.12
0.263
1.0
0.219
0.8
Mod (Clay)
65
0 49
0.34
0.263
2.8
0.219
2.3
High (Silt)
65
0.49
0.80
0.263
66
0.219
5.5
7% slope, 140" length
Low (Sand)
65
1.06
0.12
0 263
2.2
0.219
1.8
Mod (Clay)
65
1.06
0 34
0.263
6.2
0.219
5.1
High (Silt)
65
1 06
0.80
0.263
14.5
0.219
12.1
12% slope, 100' length
Low(Sand)
65
1 79
0.12
0.263
3.7
0.219
3.1
Mod (Clay)
65
1.79
0 34
0.263
10.4
0.219
8.7
High (Silt)
65
1 79
0.80
0.263
24.5
0.219
20.4
18% slope, 50' length
Low (Sand)
65
1.98
0 12
0.263
4 1
0.219
3.4
Mod (Clay)
65
1 98
0 34
0.263
11.5
0.219
96
High (Silt)
65
1 98
0 80
0.263
27 1
0.219
22.6
Construction
Construction
Soil
Construction
with Seeding
w/Seeding+Mulching
Fresno, California
Erodibility
R
LS
K
C
A (tons/ac)
C
A (tons/ac)
3% slope, 200' length
Low (Sand)
12
0.49
0.12
0.251
0.2
0.202
0.1
Mod (Clay)
12
0 49
0.34
0.251
0.5
0.202
0.4
High (Silt)
12
0 49
0 80
0.251
1.2
0.202
0.9
7% slope, 140' length
Low (Sand)
12
1 06
0.12
0 251
0.4
0.202
0.3
Mod (Clay)
12
1 06
0.34
0.251
1 1
0.202
0.9
High (Silt)
12
1 06
0.80
0.251
2.6
0.202
2.1
12% slope, 100' length
Low (Sand)
12
1 79
0 12
0 251
06
0.202 I 0.5
Mod (Clay)
12
1 79
0 34
0.251
1 8
0.202
1.5
High (Silt)
12
1.79
0.80
0.251
4.3
0.202
3.5
18% slope, 50' length
Low (Sand)
12
1 98
0.12
0.251
0.7
0.202
0.6
Mod (Clay)
12
1 98
0 34
0.251
2.0
0.202 | 1.6
High (Silt) | 12 | 1.98
0 80
0 251
4.8
0.202 i 3.8
-------
APPENDIX ID
RUSLE RESULTS
Construction Conditions with
Straw Bales and Silt Fences
-------
RUSLE Construction Conditions with Straw Bales and Sitt Fences
Construction
Construction
with Straw Bales
with Silt Fence
Soil
Construction K & C
RUSLE SDR Method
RUSLE SDR Method
Des Moines, Iowa
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
160
0.49
0.12
0.885
0.65
54
0.60
4.9
Mod (Clay)
160
049
0.34
0.885
0.72
16.7
063
14.7
High (Silt)
160
0.49
0.80
0.885
0.73
40.0
0.64
35.0
7% slope, 140" length
Low (Sand)
160
1.06
0.12
0.885
0.59
10.6
0.45
8.1
Mod (Clay)
160
1.06
0.34
0 885
0.69
35.2
0.53
27.1
High (Silt)
160
1.06
0.80
0.885
0.71
85.0
0.55
66.1
12% slope, 10C length
Low (Sand)
160
1.79
0.12
0.885
0.53
16.2
0.37
11.2
Mod (Clay)
160
1.79
0.34
0.885
0.65
55.6
0.46
40.0
High (Silt)
160
1 79
080
0.885
0.67
1348
0.49
98.3
18% slope, 50' length
Low (Sand)
160
1.98
0 12
0.885
0.56
18.9
0.44
14.9
Mod (Clay)
160
1 98
034
0.885
0.68
643
0.57
54.0
High (Silt)
160
1 98
080
0 885
0.70
155.8
0.59
132.3
'Used SDR value
'Used SOR value
Soil
Construction K & C
SDR Method
SDR Method
Helena, Montana
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
14
0.49
0.12
0.827
0.58
0.4
0.58
0.4
Mod (Clay)
14
0.49
0.34
0.827
0.59
1.1
0.59
1.1
High (Silt)
14
0 49
0.80
0.827
0.60
2.7
0.60
2.7
7% slope, 140' length
Low (Sand)
14
1.06
0.12
0.827
0.38
0.6
0.38
0.6
Mod (Clay)
14
1.06
0.34
0.827
0.41
1 7
0.40
1.7
High (Silt)
14
1.06
0.80
0 827
0.43
4.2
0.41
4.0
12% slope, 100* length
Low (Sand)
14
1 79
0 12
0.827
0.29
0.7
0.29
0.7
Mod (Clay)
14
1 79
0.34
0 827
033
2.3
0.31
2.2
High (Sitt)
14
1.79
060
0 827
0.35
5.8
0.32
5.3
18% slope, 50" length
Low (Sand)
14
1 98
0.12
0.827
0.24
0.7
0.24
0.6
Mod (Clay)
14
1 98
0.34
0.827
0.29
2.3
0.27
2.1
High (Silt)
14
1 98
0.80
0 827
0.32
59
0.28
5.2
'Used SDR value
'Used SDR value
Soil
Construction K£C
SDR Method
SDR Method
Duluth, Minnesota
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
95
0.49
0.12
0 873
0.62
3.0
0.59
2.8
Mod (Clay)
95
0.49
0.34
0 873
0.69
9.4
0.61
8.4
High (Sitt)
95
0.49
0.80
0.873
0.70
22.5
0.62
20.0
7% slope, 140" length
Low (Sand)
95
1 06
0.12
0 873
0.53
5.6
0.42
4.4
Mod (Clay)
95
1.06
0.34
0.873
0.65
19.3
0.49
14.8
High (Silt)
95
1 06
0.80
0.873
0.67
469
0.51
36.1
12% slope, 100" length
Low (Sand)
95
1 79
0.12
0.873
0.46
8.2
0.33
5.9
Mod (Clay)
95
1 79
0.34
0.873
0.59
30.0
0.42
21.2
High (Silt)
95
1 79
080
0 873
0.62
73 5
0.44
52.5
18% slope, 50' length
Low (Sand) | 95
1.98
0.12
0.873
0.48
9.5
0.38
7.4
Mod (Clay)
95
1 98
034
0 873
0 62
34.8
0.51
28.5
High (Silt)
95
1.98
0.80
0 873
0 65
85.2
0.54
70.7
I'Used SDR value
'Used SDR value
-------
RUSLE Construction Condition# with Straw Bales and Silt Fences
Construction
Construction
with Straw Bales
with Silt Fence
Soil
Construction K & C
SDR Method
SDR Method
Bismarck, North Dakota
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
50
0.49
0.12
0.844
0.59
1.5
0.58
1.4
Mod (Clay)
50
0.49
0.34
0.844
0.65
4.5
0.60
4.2
High (Silt)
50
0.49
0.80
0.844
0.66
10.9
0.61
9.9
7% slope, 140" length
Low (Sand)
50
106
0.12
0.844
0.46
2.4
0.39
2.1
Mod (Clay)
50
1.06
0.34
0.844
0.58
8.9
0.45
6.9
High (Silt)
50
1.06
0.80
0.844
0.61
21.8
0.47
16.8
12% slope, 100" length
Low (Sand)
50
1.79
0.12
0.844
0.38
3.4
0.31
2.8
Mod (Clay)
50
1.79
0.34
0.844
0.52
13.4
0.37
9.5
High (Silt)
50
1.79
0.80
0.844
0.55
33.4
0.39
23.8
18% slope, 501 length
Low (Sand)
50
1.98
0.12
0.844
0.38
3.8
0.30
3.0
Mod (Clay)
50
1 98
034
0844
0.55
15.6
0.44
12.4
High (Silt)
50
1.98
0.80
0.844
0.58
38.9
0.47
31.3
'Used SDR value
*Used SDR value
Soil
Construction K & C
SDR Method
SDR Method
Denver, Colorado
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
40
0.49
0.12
0 841
0.59
1.1
0.58
1.1
Mod (Clay)
40
0.49
0.34
0 841
0.63
3.5
0.60
3.3
High (Silt)
40
0.49
0.80
0.841
0.64
84
0.60
7.8
7% slope, 140" length
Low (Sand)
40
1.06
0.12
0.841
0.42
1.8
0.39
1.7
Mod (Clay)
40
1.06
0.34
0.841
0.54
6.6
0.43
5.2
High (Silt)
40
1.06
080
0.841
0.57
16 3
0.45
12.7"
12% slope, 100" length
Low (Sand)
40
1.79
0.12
0.841
0.34
2.4
0.30
2.2
Mod (Clay)
40
1.79
0.34
0.841
0.48
9.7
0.35
7.1
High (Silt)
40
1.79
0.80
0.841
0.51
24.5
0.37
17.7
18% slope, 50" length
Low (Sand)
40
1.98
0.12
0.841
0.32
2.5
0.27
2.1
Mod (Clay)
40
1.98
0.34
0.841
0.50
11.2
0.39
8.8
High (Silt)
40
1.98
0.80
0.841
0.53
28.4
0.42
22.5
'Used SDR value
'Used SDR value
Soil
Construction K & C
SDR Method
SDR Method
Boise, Idaho
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
12
0.49
0.12
0.818
0.58
0.3
0.58
0.3
Mod (Clay)
12
049
0.34
0.818
0.59
1.0
0.59
1.0
High (Silt)
12
0.49
080
0.818
0.60
2.3
0.60
2.3
7% slope, 14CT length
Low (Sand)
12
1.06
0.12
0.818
0.38
0.5
0.38
0.5
Mod (Clay)
12
1.06
0.34
0.818
0.41
1.4
0.40
1.4
High (Silt)
12
1 06
0.80
0.818
0.42
3.5
0.41
3.4
12% slope, 100" length
Low (Sand)
12
1.79
0.12
0.818
0.29
0.6
0.29
0.6
Mod (Clay)
12
1.79
0.34
0.818
0.32
1 9
0.31
1.9
High (Silt)
12
1.79
0.80
0.818
034
4.7
0.32
4.5
18% slope, 50 length
Low (Sand)
12
1.98
0.12
0.818
0.24
0.6
0.24
0.6
Mod (Clay)
12
1.98
0.34
0.818
0.28
1 8
0.26
1.7
High (Silt)
12
1 98
0.80
0 818
0.31
4.7
0.28
4.3
•Used SDR value
'Used SDR value
n$
-------
RUSLE Construction Conditions with Straw Bales and Silt Fences
Construction
Construction
with Straw Bales
with Silt Fence
Soil
Construction K & C
SDR Method
SDR Method
Nashville, Tennessee
Erodibility
R
LS
K
C
SDR*
Sed Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200' length
Low (Sand)
225
0.49
0.12
0.891
0.65
7.6
0.60
6.9
Mod (Clay)
225
0.49
0.34
0.891
0.72
23.6
0.63
20.8
High (Silt)
225
0.49
0.80
0.891
0.73
56.6
0.64
49.6
7% slope, 140" length
Low (Sand)
225
1.06
0.12
0.891
0.59
15.1
0.45
11.5
Mod (Clay)
225
1.06
0.34
0.891
0.69
49.8
0.53
38.4
High (Silt)
225
1.06
0.80
0.891
0.71
120.3
0.55
93.7
12% slope, 100" length
Low (Sand)
225
1.79
0.12
0.891
0.53
22.9
0.37
15.9
Mod (Clay)
225
1 79
0.34
0.891
0.65
78.7
0.46
56.6
High (Silt)
225
1 79
0.80
0.891
0.67
1909
0.49
139.2
18% slope, 50" length
Low (Sand)
225
1.98
0.12
0 891
0.56
26.7
0.44
21.1
Mod (Clay)
225
1.98
034
0 891
0.68
91.1
0.57
76.5
High (Silt)
225
1.98
080
0.891
0.70
220.7
0 59
187.3
"Used SDR value
'Used SDR value
Soil
Construction K & C
SDR Method
SDR Method
Hartford, Connecticut
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
130
0.49
0.12
0.878
0.62
4.1
0.59
3.9
Mod (Clay)
130
0 49
034
0 878
069
12.9
0.61
11.5
High (Silt)
130
0.49
080
0.878
0.70
31.0
0.62
27.5
7% slope, 140" length
Low (Sand)
130
1.06
0.12
0.878
0.53
7.7
0.42
6.1
Mod (Clay)
130
1.06
034
0.878
0.65
26.6
0 49
20.3
High (Silt)
130
1 06
0.80
0.878
0.67
64.6
0.51
49.7
12% slope, 10CT length
Low (Sand)
130
1.79
0.12
0 878
0.46
11.4
033
8.2
Mod (Clay)
130
1.79
0.34
0 878
0.59
41.3
0.42
29.2
High (Silt)
130
1.79
0.80
0.878
0.62
101.2
0.44
72.3
18% slope, 50" length
Low (Sand)
130
1.98
0.12
0.878
048
13.1
038
10.2
Mod (Clay)
130
1.98
0.34
0 878
0 62
480
0 51
39.3
High (Silt)
130
1.98
0.80
0 878
0.65
117.4
0.54
97.3
'Used SDR value
'Used SDR value
Soil
Construction K 4 C
SDR Method
SDR Method
Atlanta, Georgia
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 2001 length
Low (Sand)
295
0 49
0.12
0.898
0.71
11.0
0.62
9.6
Mod (Clay)
295
0.49
0.34
0.898
0.77
33.5
0.67
29.2
High (Silt)
295
0.49
0.80
0.898
0.78
79.8
0.68
69.6
7% slope, 140" length
Low (Sand)
295
1.06
0.12
0 898
0.69
23.2
0.53
17.8
Mod (Clay)
295
1.06
0.34
0.898
0.76
72.4
0.61
57.8
High (Silt)
295
1.06
080
0.898
0.77
172.9
0.62
139.5
12% slope, 100" length
Low (Sand)
295
1 79
0.12
0.898
0.65
36.7
0.46
26.1
Mod (Clay)
295
1 79
0.34
0.898
0.72
116.7
055
88.5
High (Silt)
295
1.79
080
0 898
0.74
279 5
0.57
214.7
18% slope, SO1 length
Low (Sand)
295
1 98
0.12
0.898
0.68
42.6
0.57
35.6
Mod (Clay)
295
1 98
034
0.898
0.75
134.1
0.66
117.3
High (Silt)
295
1 98
080
0.898
0.76
320.5
0.67
282.3
•Used SDR value
'Used SDR value
-------
RUSLE Construction Conditions with Straw Bales and Silt Fences
Construction
Construction
with Straw Bales
with Silt Fence
Soil
Construction K & C
SDR Method
SDR Method
Charleston, South Carolina
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
400
0.49
0.12
0.917
0.76
16.2
0.66
14.0
Mod (Clay)
400
0.49
0.34
0.917
0.80
48.4
0.70
42.3
High (SiK)
400
0.49
0.80
0.917
0.81
115.0
0.71
100.9
7% slope, 140" length
Low (Sand)
400
1.06
0.12
0.917
0.75
34.9
0.59
27.5
Mod (Clay)
400
1.06
0.34
0.917
0.80
105.6
0.66
87.0
High (Silt)
400
1.06
0.80
0.917
0.81
251.3
0.67
208.4
12% slope, 100" length
Low (Sand)
400
1.79
0.12
0.917
0.71
56.0
0.53
41.7
Mod (Clay)
400
1.79
0.34
0.917
0.77
171.9
0.61
135.7
High (Silt)
400
1.79
0.80
0.917
0.78
409.6
0.62
326.6
18% slope, 50* length
Low (Sand)
400
1.98
0.12
0.917
0.74
64.6
0.64
56.0
Mod (Clay)
400
1.98
0.34
0.917
0.80
196.3
0.71
175.8
High (Silt)
400
1.98
0.80
0.917
0.80
467 0
0.72
420.6
'Used SDR value
'Used SDR value
Soil
Construction K & C
SDR Method
SDR Method
Amarillo, Texas
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
100
0.49
0.12
0.860
0.68
3.4
0.61
3.0
Mod (Clay)
100
0 49
034
0.860
0.74
10.5
0.65
9.1
High (Silt)
100
0.49
080
0.860
0.75
25.0
0.66
21.8
7% slope, 140" length
Low (Sand)
100
1.06
0.12
0.860
0.64
7.0
0.48
5.3
Mod (Clay)
100
1.06
0.34
0.860
0.72
22.4
0.57
17.5
High (Silt)
100
1.06
080
0.860
0.74
53.7
0.58
42.5
12% slope, 100" length
Low (Sand)
100
1.79
0.12
0.860
0.59
10.8
0.41
7.5 '
Mod (Clay)
100
1.79
0.34
0.860
0.68
35.7
0.50
26.3
High (Silt)
100
1.79
0.80
0.860
0.70
86.0
0.52
64.2
18% slope, 50" length
Low (Sand)
100
1.98
0.12
0.860
0.62
12.6
0.50
10.2
Mod (Clay)
100
1.98
034
0.860
0.71
41.2
0.61
35.3
High (Silt)
100
1.98
080
0.860
0 73
99 1
0.63
85.6
'Used SDR value
'Used SDR value
Soil
Construction K & C
SDR Method
SDR Method
San Antonio, Texas
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
250
0.49
0.12
0.877
0.72
9.2
0.63
8.0
Mod (Clay)
250
0.49
0.34
0.877
0.78
28 0
0.68
24.4
High (Silt)
250
0.49
0.80
0.877
0.78
66.7
0.68
58.2
7% slope, 140" length
Low (Sand)
250
1.06
0.12
0.877
0.70
19.6
0.54
15.1
Mod (Clay)
250
1.06
0.34
0.877
0.77
60.7
0.62
48.8
High (Silt)
250
1.06
080
0.877
0.78
144.9
0.63
117.5
12% slope, 10CT length
Low (Sand)
250
1.79
0.12
0.877
0.66
31.1
0.47
22.3
Mod (Clay)
250
1.79
0.34
0.877
0.74
98.1
0.56
75.1
High (Silt)
250
1.79
080
0.877
0.75
234.6
0.58
181.8
18% slope, 50* length
Low (Sand)
250
1.98
0.12
0.877
0.69
36 1
0.58
30.4
Mod (Clay)
250
1.98
0.34
0.877
0.76
112.5
0.67
99.1
High (Silt)
250
1.98
0.80
0.877
0.77
268.8
0.69
237.9
"Used SDR value
'Used SDR value
-------
RUSLE Construction Conditions with Straw Bales and Silt Fences
Construction
Construction
with Straw Bales
with Silt Fence
Soil
Construction K & C
SDR Method
SDR Method
Las Vegas, Nevada
Erodibility
R
LS
K
C
SDR'
Sed Del (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
8
0.49
0.12
0 809
0.58
0.2
0.58
0.2
Mod (Clay)
8
0.49
0.34
0.809
0.59
0.6
0.59
0.6
High (Silt)
8
0.49
0.80
0.809
0.60
1.5
0.60
1.5
7% slope, 140" length
Low (Sand)
8
1.06
0.12
0809
0.38
0.3
0.38
0.3
Mod (Clay)
8
1.06
0.34
0.809
0.43
1.0
0.40
0.9
High (Silt)
8
1.06
0.80
0.809
0.45
2.5
0.41
2.3
12% slope, 1001 length
Low (Sand)
8
1.79
0.12
0.809
0.29
04
0.29
0.4
Mod (Clay)
8
1.79
0.34
0.809
0.34
1.4
0.32
1.2
High (Silt)
8
1.79
0.80
0 809
0.37
3.5
0.32
3.0
18% slope, 50" length
Low (Sand)
8
1.98
0.12
0.809
0.24
0.4
0.24
0.4
Mod (Clay)
8
1 98
0.34
0.809
0.32
1.4
0.28
1.2
High (Silt)
8
1 98
0.80
0.809
0.36
3.7
0.30
3.1
'Used SDR value
'Used SDR value
Soil
Construction K & C
SDR Method
SDR Method
Portland, Oregon
Erodibility
R
LS
K
C
SDR*
Sed. Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200 length
Low (Sand)
65
0.49
0 12
0.864
0.58
1.9
0.58
1.9
Mod (Clay)
65
0 49
0.34
0.864
0.59
5.5
0.59
5.5
High (Silt)
65
0.49
0.80
0.864
0.60
13.1
0.60
13.0
7% slope, 1401 length
Low (Sand)
65
1.06
0.12
0.864
0.38
2.7
0.38
2.7
Mod (Clay)
65
1.06
034
0.864
0.43
8.6
0.40
8.2
High (Silt)
65
1.06
0.80
0864
0 45
21.6
0.41
19.6
12% slope, 10CT length
Low (Sand)
65
1 79
0 12
0.864
0.29
3.5
0.29
3.5
Mod (Clay)
65
1.79
0 34
0.864
0.34
11 7
0.32
10.8
High (Silt)
65
1.79
0.80
0.864
0.37
30.0
0.32
26.1
18% slope, 501 length
Low (Sand)
65
1.98
0.12
0.864
0.24
3.2
0.24
3.2
Mod (Clay)
65
1.98
0.34
0.864
0.32
122
0.28
10.5
High (Silt)
65
1.98 •
080
0 864
0.36
32.4
0.30
26.8
'Used SDR value
'Used SDR value
Soil
Construction K & C
SDR Method
SDR Method
Fresno, California
Erodibility
R
LS
K
C
SDR*
Sed Del. (tons/ac)
SDR*
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
12
0.49
0.12
0.822
0.58
0.3
0.58
0.3
Mod (Clay)
12
0 49
0.34
0.822
0.59
1.0
0.59
1.0
High (Silt)
12
0 49
0.80
0.822
0.60
2.3
0.60
2.3
7% slope, 1401 length
Low (Sand)
12
1 06
0.12
0.822
0.38
0.5
0.38
0.5
Mod (Clay)
12
1.06
0.34
0.822
0.40
1 4
0.40
1.4
High (Silt)
12
1.06
080
0 822
0.41
3.5
0.41
3.4
12% slope, 100" length
Low (Sand)
12
1.79
0.12
0.822
0.29
06
0.29
0.6
Mod (Clay)
12
1.79
0.34
0.822
0.31
1.9
0.31
1.9
High (Silt)
12
1 79
0.80
0.822
0.33
46
0.32
4.5
18% slope, 50" length
Low (Sand)
12
1 98
0 12
0.822
0.24
0.6
0.24
0.6
Mod (Clay)
12
1.98
034
0.822
0.27
1.8
0.26
1.7
High (Silt)
12
1 98
080
0.822
0.29
45
0.27
4.2
'Used SDR value
'Used SDR value
* I
-------
APPENDIX IE
RUSLE RESULTS
Construction Conditions with
Stone Check Dams and Sediment Traps
-------
Construction
Construction
with Check Oam
with Sediment Trap
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Des Moines, Iowa
Erodibility
R
LS
K
C
Eff*
Sed. Del. (tons/ac)
Eff*
Sed. Del. (tons/ac)
3% slope, 2Off length
Low (Sand)
160
0.49
0.12
0.885
0.7
2.5
0.6
3.3
Mod (Clay)
160
0.49
0.34
0.885
0.7
7.0
0.6
9.3
High (Silt)
160
0.49
0.80
0.885
0.7
16.5
0.6
22.0
7% slope, 140" length
Low (Sand)
160
1.06
0.12
0.885
0.7
5.4
0.6
7.2
Mod (Clay)
160
1.06
0.34
0.885
0.7
15.3
0.6
20.4
High (Silt)
160
1.06
0.80
0.885
0.7
36.0
0.6
48.0
12% slope. 100" length
Low (Sand)
160
1.79
0.12
0.885
0.7
9.1
0.6
12.2
Mod (Clay)
160
1.79
0.34
0.885
0.7
25.8
0.6
34.5
High (Silt)
160
1.79
080
0 885
0.7
60.8
0.6
81.1
18% slope, 50 length
Low (Sand)
160
1.98
0.12
0885
0.7
10.1
0.6
13.5
Mod (Clay)
160
1.98
0.34
0.885
0.7
28 6
0.6
38.1
High (Silt)
160
1.98
0.80
0 885
0.7
67.3
0.6
89.7
"Used EPA Eff. value
'Used EPA Eff. value
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Helena, Montana
Erodibility
R
LS
K
C
Eff
Sed. Del. (tons/ac)
EfT
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
14
0.49
0.12
0.827
0.7
0.2
0.6
0.3
Mod (Clay)
14
0.49
0.34
0.827
0.7
0.6
0.6
0.8
High (Silt)
14
0.49
080
0.827
0.7
1.3
0.6
1.8
7% slope, 140" length
Low (Sand)
14
1.06
0.12
0.827
0.7
0.4
0.6
0.6 ,
Mod (Clay)
14
1.06
0.34
0.827
0.7
1.3
0.6
1.7
High (Silt)
14
1.06
0.80
0.827
0.7
2.9
0.6
3.S
12% slope, 100" length
Low (Sand)
14
1.79
0.12
0.827
0.7
0.7
0.6
1.0
Mod (Clay)
14
1.79
0.34
0.827
07
2.1
0.6
2.8
High (Silt)
14
1 79
080
0.827
07
5.0
0.6
6.6
18% slope. 50' length
Low (Sand)
14
1.98
0.12
0 827
0.7
0.8
0.6
1.1
Mod (Clay)
14
1.98
0.34
0.827
0.7
2.3
0.6
3.1
High (Silt)
14
1.98
0.80
0.827
0.7
5.5
0.6
7.3
"Used EPA Eff. value
"Used EPA Eff. value
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Duluth, Minnesota
Erodibility
R
LS
K
C
Eff"
Sed. Del. (tons/ac)
Eff"
Sed. Del. (tons/ac)
3% slope. 20a length
Low (Sand)
95
0.49
0.12
0.873
0.7
1.4
0.6
1.9
Mod (Clay)
95
0.49
0.34
0 873
07
4.1
0.6
5.5
High (Silt)
95
0.49
0.80
0 873
0.7
9.7
0.6
12.9
7% slope, 140" length
Low (Sand)
95
106
0.12
0.873
07
3.2
0.6
4.2
Mod (Clay)
95
1.06
0.34
0.873
0.7
9.0
0.6
12.0
High (Silt)
95
1.06
0.80
0.873
0.7
21.1
0.6
28.1
12% slope, 1001 length
Low (Sand)
95
1.79
0.12
0.873
0.7
5.3
0.6
7.1
Mod (Clay)
95
1.79
0.34
0.873
0.7
15.1
0.6
20.2
High (Silt)
95
1.79
0.80
0.873
0.7
35 6
0.6
47.5
18% slope, 50* length
Low (Sand)
95
1.98
0.12
0.873
0.7
5.9
0.6
7.9
Mod (Clay)
95
1.98
0.34
0.873
0.7
16.7
0.6
22.3
High (Silt)
95
1.98
080
0.873
I 0.7
39.4
0.6
52.5
I "Used EPA Eff. value
'Used EPA Eff. value
3?
-------
Construction
Construction
with Check Dam
with Sediment Trap
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Bismarck. North Dakota
Erodibility
R
LS
K
C
Er
Sed. Del. (tons/ac)
Er
Sed. Del. (tons/ac)
3% slope, 200' length
Low (Sand)
50
0.49
0.12
0.844
0.7
0.7
0.6
1.0
Mod (Clay)
50
0.49
0.34
0.644
0.7
2.1
0.6
2.8
High (Silt)
50
0.49
0.80
0.844
0.7
4 9
0.6
6.6
7% slope, 14C length
Low (Sand)
50
1.06
0.12
0844
0.7
1.6
0.6
2.1
Mod (Clay)
50
1 06
0.34
0844
0.7
4.6
0.6
6.1
High (Silt)
50
1.06
0.80
0.844
0.7
10.7
0.6
14.3
12% slope, 100" length
Low (Sand)
50
1.79
0.12
0844
0.7
2.7
0.6
3.6
Mod (Clay)
50
1 79
0.34
0.844
0.7
7.7
0.6
10.3
High (Silt)
50
1 79
0.80
0.844
0.7
18.1
0.6
24.2
18% slope, 50" length
Low (Sand)
50
1 98
0.12
0.844
0.7
3.0
0.6
4.0
Mod (Clay)
50
1 98
0.34
0.844
07
8 5
0.6
11.4
High (Silt)
50 I 1 98
0.80
0.844
0.7
20.1
0.6
26.7
"Used EPA Eff. value
"Used EPA Eff. value
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Denver, Colorado
Erodibility
R
LS
K
C
Er
Sed. Del. (tons/ac)
Er
Sed. Del. (tons/ac)
3% slope. 2Off length
Low (Sand)
40
0.49
0.12
0.841
0.7
0.6
0.6
0.8
Mod (Clay)
40
0 49
0.34
0.841
0.7
1 7
0.6
2.2
High (Silt)
40
0 49
0.80
0.841
07
39
0.6
5.2
7% slope. 140" length
Low (Sand)
40
1.06
0.12
0 841
07
1.3
0.6
1.7
Mod (Clay)
40 | 1.06
0.34
0.841
0.7
3.6
0.6
4.8
High (Silt)
40 I 1.06
080
0.841
07
86
0.6
11.4
12% slope. 10ff length
Low (Sand)
40 | 1.79 | 0.12
0.841
0.7
2.2
0.6
2.9
Mod (Clay)
40 1 79
0.34
0.841
0.7
6 1
0.6
8.2
High (Silt)
40 | 1 79
080
0.841
0.7
14 4
0.6
19.3
18% slope, 501 lenqth
Low (Sand)
40 1 98
0.12
0.841
0.7 | 2 4
0.6
3.2
Mod (Clay)
40
1 98
0.34
0 841
0.7 6 8
0.6
9.1
High (Silt)
40
1 98
0.80
0.841
07 I 160
0.6
21.3
'
"Used EPA Eff value
"Used EPA Eff value
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Boise, Idaho
Erodibility
R
LS
K
C
EfP
Sed. Del (tons/ac)
Er
Sed. Del. (tons/ac)
3% slope, 200* length
Low (Sand)
12
0.49
0.12
0.818
0.7
02
0.6
0.2
Mod (Clay)
12
0.49
0.34
0.818
0.7
0.5
0.6
0.6
High (Silt)
12
0 49
0.80
0.818
0.7
1.1
0.6
1.5
7% slope, 140* length
Low (Sand)
12
1.06
0.12
0818
0.7
0.4
0.6
0.5
Mod (Clay)
12
1 06
0.34
0.818
0.7
1 1
0.6
1.4
High (Silt)
12
1 06
0.80
0.818
0.7
2.5
0.6
3.3
12% slope. 100" length
Low (Sand)
12
1.79
0.12
0.818
0.7
06
0.6
0.8
Mod (Clay)
12
1.79
0.34
0 818
0.7
1 8
06
2.4
High (Silt)
12
1 79
080
0 818
0.7
4 2
0.6
5.6
18% slope. 50* length
Low (Sand)
12
1 98
0.12
0 818
0.7
0 7
0.6
0.9
Mod (Clay) I 12 | 1 98 I 0 34
0.818
07 | 20
0.6
2.6
High (Silt) | 12 ' 198 I 0 80
0.818
O
-g
0.6
6.2
I i ;
'"Used EPA Eff value
"Used EPA Eff. value
-------
Construction
I Construction
with Check Dam
with Sediment Trap
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Nashville. Tennessee
Erodibility
R
LS
K
C
EIT
Sed. Del. (tons/ac)
Er
Sed. Del. (tons/ac)
3% slope. 200* length
Low (Sand)
225
0.49
0.12
0.891
0.7
3.5
0.6
4.7
Mod (Clay)
225
0.49
0.34
0.891
0.7
9.9
0.6
13.2
High (Silt)
225
0.49
0.80
0.891
0.7
23.3
0.6
31.1
7% slope, 14ff length
Low (Sand)
225
1.06
0.12
0.891
0.7
7.6
0.6
10.2
Mod (Clay)
225
1.06
0.34
0.891
0.7
21.7
0.6
28.9
High (Silt)
225
1.06
0.80
0.891
0.7
51.0
0.6
68.0
12% slope. 10CT length
Low (Sand)
225
1.79
0.12
0.891
0.7
12.9
0.6
17.2
Mod (Clay)
225
1.79
0.34
0.891
0.7
36.6
0.6
48.6
High (Silt)
225
1.79
0.80
0.891
0.7
86.1
0.6
114.8
18% slope. SO1 length
Low (Sand)
225
1.98
012 | 0.891
0.7
14.3
0.6
19.1
Mod (Clay)
225
1.98
0.34 I 0.891
0.7 i 40.5
0.6
54.0
High (Silt)
225
1 98
0 80 l 0 891
0.7 | 95.3
0.6
127.0
'Used EPA EfT. value
'Used EPA Eff. value
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Hartford. Connecticut
Erodibility
R
LS
K
C
Er
Sed. Del. (tons/ac)
Er
Sed. Del. (tons/ac)
3% slope, 20C length
Low (Sand)
130
0.49
0.12
0.878
0.7
2.0
0.6
2.7
Mod (Clay)
130
0.49
0.34
0.878
0.7
5.6
0.6
7.5
High (Silt)
130
0.49
0.80
0.878
0.7
13.3
0.6
17.7
7% slope, 14CT length
Low (Sand)
130
1 06
0.12
0.878
0.7
4.4
0.6
5.8
Mod (Clay)
130
1.06 I 0.34
0.878
0.7
12.3
0.6
16.5
High (Silt)
130
1.06
0.80 1 0.878
0.7
29.1
0.6
38.7
12% slope, 100* length
Low (Sand)
130
1.79
0.12 I 0.878
0.7
74
0.6
9.8
Mod (Clay)
130
1 79
0.34 I 0.878
0.7
20.8
0.6
27.8
High (Silt) i 130
1.79
0.80 I 0.878
0.7
49 1
0.6
65.4
18% slope. 50" length
Low (Sand)
130
1.98
0.12 i 0.878
0.7
8.1
0.6
10.9
Mod (Clay)
130
1.98
0.34 | 0 878
0.7
23.1
0.6
30.7
High (Silt)
130
1.98
0 80 I 0 878
0.7
54.3
0.6
72.4
I
'Used EPA Eff. value
'Used EPA Eff. value
! I
'
i i
SoU
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Atlanta. Georgia
Erodibility
R
LS
K
C
Er
Sed. Del. (tons/ac)
Er
Sed. Del. (tons/ac)
3% slope, 2Off length
Low (Sand)
295
0.49
0.12
0.898
0.7
4.6
0.6
6.2
Mod (Clay)
295
0.49
0.34
0.898
0.7
13.1
0.6
17.5
High (Silt)
295
0.49
0.80
0.898
0.7
30.8
0.6
41.1
7% slope, 140* length
Low (Sand)
295
1.06
0.12
0.898
0.7
10.1
0.6
13.5
Mod (Clay)
295
1.06
0.34
0.898
0.7
28.6
0.6
38.2
High (Silt)
295
1.06
0.80
0.898
0.7
67.4
0.6
89.8
12% slope, 100" length
.ow (Sand)
295
1.79
0.12
0.898
0.7
17.1
0.6
22.8
Mod (Clay)
295
1.79
0.34
0.898
0.7
48.4
0.6
64.5
High (Silt)
295
1.79
0.80 I 0.898
0.7
113.8 |
0.6
151.7
18% slope. 50" length
.ow (Sand)
295
1 98
0.12 I 0.898 I
0.7
18.9
I 0.6
25.2
Mod (Clay) | 295
1 98
034
0.898 I
0.7
53.5
0.6
71.3
High (Silt) 295
1 98
080
0 898 I
0.7
125.9
0.6
167.8
! ! I i I
'Used EPA Eff. value "Used EPA EfT. value
_ if'
-------
Construction
Construction
with Check Dam
with Sediment Trap
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Charleston. South Carolina
Erodibility
R
LS
K 1 C
EfT
Sed Del. ^tons/ac)
EfT
Sed. Del. (tons/ac)
1
3% slope. 200* length
Low (Sand)
400
0.49
0.12
0 917
0.7
64
0.6
8.5
Mod (Clay)
400
0.49
0.34
0.917
0.7
18.1
0.6
24.2
High (Silt)
400
0.49
0.80
0.917
0.7
42.7
0.6
56.9
7% slope. 140* length
Low (Sand)
400
1.06
0.12
0 917
0.7
14.0
0.6
18.7
Mod (Clay)
400
1 06
0.34
0 917
0.7
39.6
0.6
52.9
High (Silt)
400
1.06
0.80
0.917
0.7
93.3
0.6
124.4
12% slope. 100" length
Low (Sand)
400
1.79
0.12
0.917
0.7
23 6
0.6
31.5
Mod (Clay)
400
1.79
0.34
0 917
0.7
67.0
0.6
89.3
High (Silt)
400
1 79
0.80
0 917
07
157.5
0.6
210.1
18% slope, 501 length
Low (Sand)
400
1 98
0.12
0.917
0.7
26.1
0.8
34.9
Mod (Clay)
400
1.98
0.34
0 917
07
74 1
0.6
98.8
Hiqh (Silt)
400 i 1 98
080
0917
0.7
174 3
0.6
232.4
I I
"Used EPA Eff. value
•Used EPA Eff. value
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Amanllo. Texas
Erodibility
R
LS
K
C
EfT
Sed. Del. (tons/ac)
I EfT
Sed. Del. (tons/ac)
3% slope, 200' length
Low (Sand)
100
0.49
0 12
0 860
0.7
1.5
0.6
2.0
Mod (Clay)
100
0 49
0.34
0.860
0.7
4.3
0.6
5.7
High (Silt)
100
0 49
0.80
0 860
0.7
10.0
0.6
13.3
7% slope, 140" length
Low (Sand)
100
1 06
0.12 I 0.860
0.7
3.3
0.6
4.4
Mod (Clay)
100 I 1 06
034
0 860
0.7
9 3
0.6
12.4
High (Silt) I 100 ! 1.06
0.80
0 860
0.7
21.9
0.6
29.2
12% slope. 100" length
Low (Sand) | 100 179
0.12
0.860
0.7
5.5
0.6
7.4
Mod (Clay) | 100 ; 179
0.34 i 0 860
0.7 , 15 7
0.6
20.9
High (Silt)
100 ! 1.79
0.80 ! 0 860
07 ! 369
0.6
49.2
18% slope, 50" length
Low (Sand)
100 I 1.98
0.12 | 0 860
0.7
6.1
0.6
8.2
Mod (Clay) | 100 I 1 98
0.34 I 0 860
07
174
0.6
23.1
High (Silt) 100
1 98
I 0 80 I 0.860
| 0.7
40.8
0.6
54.5
I
I'Used EPA EfT value
"Used EPA Eff. value
|
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
San Antonio. Texas
Erodibility
R
LS
K
C
EfT* I Sed Del. (tons/ac)
EfT
Sed. Del. (tons/ac)
3% slope. 200* length
Low (Sand)
250
0.49
0.12
0.877
0.7
3.8
0.6
5.1
Mod (Clay)
250
0.49
034
0 877
0.7
10.8
0.6
145
High (Silt)
250
0.49
0.80
0.877
0.7
25.5
0.6
34.0
7% slope. 140" length
Low (Sand)
250
1.06
0.12
0 877
0.7
8.4
0.6
11.2
Mod (Clay)
250
1.06
0.34
0.877
0.7
23.7
0.6
31.6
High (Silt)
250
1 06
0.80
0 877
0.7
55.8
0.6
74.4
12% slope. 100* length
Low (Sand)
250
1.79
0 12
0.877
0.7
14 1
0.6
18.8
Mod (Clay)
250
1.79
034
0.877
0.7
40.0
0.6
53.4
I High (Silt)
250
1 79
0 80 ! 0.877 I
07
942
0.6
125.6
18% slope, SO" length | Low (Sand)
250
198 | 0 12 I 0 877 I i 0.7 I 15.6
0.6
20.8
I Mod (Clay)
250
1 98 | 0 34 ' 0 877 ! i 0.7
44.3
0.6
59.0
I High (Silt)
250
1.98 I 0 80 I 0 877 i 0 7
104.2
0.6
138.9
I !
1 "Used EPA Eff value ! i'Used EPA Eff. value
-------
Construction
Construction
with Check Dam
with Sediment Trap
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Las Vegas. Nevada
Erodibility
R
LS
K
C
e r
Sed. Del. (tons/ac)
Er
Sed. Del. (tons/ac)
3% slope, 200* length
Low (Sand)
8
0.49
0.12
0.809
0.7
0.1
0.6
0.2
Mod (Clay)
8
0.49
0.34
0.809
0.7
0.3
0.6
0.4
Hioh (Silt)
8
0.49
0.80
0.809
0.7
0.8
0.6
1.0
7% slope, 14(T length
Low (Sand)
8
1.06
0.12
0.809
0.7
0.2
0.6
0.3
Mod (Clay)
8
1.06
0.34
0.809
0.7
0.7
o.e
0.9
High (Silt)
8
1.06
0.80
0.809
0.7
1.6
0.6
2.2
12% slope, 10(7 length
Low (Sand)
8
1.79
0.12
0.809
0.7
0.4
0.6
0.6
Mod (Clay)
8
1.79
0.34
0.809
0.7
1.2
0.6
1.6
High (Silt)
8
1.79
0.80
0.809
0.7
2.8
0.6
3.7
18% slope, 50" length
Low (Sand)
8
1.98
0.12
0 809
0.7
0.5
0.6
0.6
Mod (Clay)
8
1.98
0.34
0.809
0.7
1.3
0.6
1.7
High (Silt)
8
1 98
0.80
0.809
0.7
3.1
0.6
4.1
'Used EPA Elt. value
"Used EPA Eff. value
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Portland, Oregon
Erodibility
R
LS
K
C
EIT
Sed. Del. (tons/ac)
Er
Sed. Del. (tons/ac)
3% slope, 200" length
Low (Sand)
65
0.49
0.12
0.864
0.7
1.0
0.6
1.3
Mod (Clay)
65
0.49
0.34
0.864
0.7
2.8
0.6
3.7
High (Silt)
65
0.49
0.80
0.864
0.7
6.5
0.6
8.7
7% slope, 140* length
Low (Sand)
65
1.06
0.12
0.864
0.7
2.1
0.6
2.9
Mod (Clay)
65
1 06
0.34
0.864
0.7
6.1
0.6
8.1
High (Silt)
65
1.06
0.80
0.864
0.7
14.3
0.6
19.1
12% slope. 10CT length
Low (Sand)
65
1.79
012
0.864
0.7
3.6
0.6
4.8
Mod (Clay) i 65
1.79
0.34
0.864
0.7
10.3
0.6
13.7
High (Silt) ! 65
1.79
080
0.864
0.7
24.1
0.6
32.2
18% slope, 50* length
Low (Sand)
65
1 98
0.12
0.864
0.7
4.0
0.6
5.3
Mod (Clay)
65
1.98
0.34
0.864
0.7
11.3
0.6
15.1
High (Silt)
65
1.98
0.80
0864
0.7
26.7
0.6
35.6
"Used EPA Eff. value
"Used EPA Eff. value
I
Soil
Construction K & C
Using EPA Efficiency
Using EPA Efficiency
Fresno, California
Erodibility
R
LS
K
C
Er
Sed. Del. (tons/ac)
Er
Sed. Del. (tons/ac)
3% slope, 200* length
Low (Sand)
12
0.49
0.12
0.822
0.7
0.2
0.6
0.2
Mod (Clay)
12
0.49
0 34
0.822
0.7
0.5
0.6
0.7
High (Sift)
12
0.49
0.80
0.822
0.7
1.1
0.6
1.5
7% slope. 14CT length
Low (Sand)
12
1.06
0.12
0.822
0.7
0.4
0.6
0.5
Mod (Clay)
12
1 06
0.34
0.822
0.7
1.1
0.6
1.4
High (Silt)
12
1.06
0.80
0.822
0.7
2.5
0.6
3.3
12% slope, KXT length
Low (Sand)
12
1.79
0.12
0.822
0.7
0.6
0.6
0.8
Mod (Clay)
12
1.79
0.34
0.822
0.7
1.8
0.6
2.4
High (Silt)
12
1 79
0.80
0 822
0.7
4.2
0.6
5.6
18% slope, 50* length
Low (Sand)
12
1.98
0.12
0.822
0.7
0.7
0.6
0.9
Mod (Clay)
12
1.98
0.34
0.822
0.7
2.0
0.6
2.7
High (Silt) |
12
1 98
0.80
0.822
0.7 I 4.7
0.6
6.2
! ¦ i
"Used EPA Eff value
"Used EPA Eff. value
*7
-------
APPENDIX IF
RUSLE RESULTS
Comparison of Pre-Construction, Construction and Construction with
Individual Best Management Practices
si
-------
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed.Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed. Del.
Sed. Del.
Sed Del.
Sed Del.
Des Moines, Iowa
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
2
8
6
4
5
5
2
3
Mod (Cla^
6
23
17
12
17
15
7
9
High (Silt)
15
55
40
28
40
35
16
22
7% slope, 140' length
Low (Sand)
5
18
13
9
11
8
5
7
Mod (Clay)
14
51
37
26
35
27
15
20
High (Silt)
34
120
87
61
85
66
36
48
12% slope, 100' length
Low (Sand)
9
30
22
16
16
11
9
12
Mod (Clay)
24
86
63
44
56
40
26
34
High (Silt)
57
203
147
103
135
98
61
81
18% slope, 50' length
Low (Sand)
Mod (Clay)
10
26
34
95
24
69'
17
19
15
10
13
49
64
54
29
38
High (Silt)
63
224
163
114
156
132
67
90
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed.Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed. Del
Sed. Del.
Sed Del.
Sed Del.
Helena, Montana
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
0
1
1
0
0
0
0
0
Mod (Clay)
0
2
2
1
1
1
1
1
High (Silt)
1
4
4
2
3
3
1
2
7% slope, 140' length
Low (Sand)
0
1
1
1
1
1
0
1
Mod (Clay)
1
4
3
2
2
2
1
2
High (Silt)
2
10
8
4
4
4
3
4
12% slope, 100' length
Low (Sand)
0
2
2
1
1
1
1
1
Mod (Clay)
1
7
6
3
2
2
2
3
High (Silt)
3
17
13
8
6
5
5
7
18% slope, 50' length
Low (Sand)
0
3
2
1
1
1
1
1
Mod (Clay)
1
8
6
4
2
2
2
3
High (Silt)
3
18
15
8
6
5
6
7
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed. Del.
Sed. Del.
Sed Del.
Sed Del
Duluth, Minnesota
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
Low (Sand)
{
3% slope, 200' length
5
4
2
3
3
1
2
Mod (Clay)
3
14
10
6
9
8
4
5
High (Silt)
7
32
25
13
23
20
10
13
7% slope. 140' length
Low (Sand)
2
11
8
4
6
4
3
4
Mod (Clay)
6
30
23
12
19
15
9
12
High (Silt)
15
70
54
29
47
36
21
28
12% slope, 100' length
Low (Sand)
4
18
14
7
8
6
5
7
Mod (Clay)
10
50
38
21
30
21
15
20
High (Silt)
24
119
91
49
74
52
36
47
J 8% slope, 50' length
Low (Sand)
4
20
8
10
7
6
8
Mod (Clay)
11
56
23
35
29
17
22
High (Silt)
27
131
54
85
71
39
53
-------
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed.Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed Del
Sed Del.
Sed Del
Sed Del
Bismarck, North Dakota
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
0
2
7
2
1
1
1
1
1
Mod (Clay)
1
5
3
5
4
2
3
High (Silt)
3
16
13
7
11
10
5
7
7% slope, 140'length
Low (Sand)
1
5
4
2
2
2
2
2
Mod^Clay)
3
15
12
6
9
7
5
6
High (Silt)
7
36
28
15
22
17
11
14
12% slope, 100' length
Low (Sand)
2
9
7
4
3
3
3
4
Mod (Clay)
5
26
20
11
13
10
8
10
High (Silt)
12
60
47
25
33
24
18
24
18% slope, 50' length
Low (Sand)
2
10
8
4
4
3
3
4
Mod (Clay)
5
28
22
12
16
12
9
11
High (Silt)
13
67
52
27
39
31
20
27
Re-
Construction
Construction with Single Best Management Practice Implemented
construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed.Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed. Del
Sed. Del.
Sed Del.
Sed Del
Denver, Colorado
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
0
2
2
1
1
1
1
1
Mod (Clay)
1
6
13
5
2
3
3
2
2
High (Silt)
3
11
6
8
8
4
5
7% slope, 140' length
Low (Sand)
1
4
4
2
2
2
1
2
Mod (Clay)
2
12
10
5
7
5
4
5
High (Silt)
6
29
24
12
16
13
9
11
12% slope, 100' length
Low (Sand)
2
7
6
3
2
2
2
3
Mod (Clay)
4
20
17
9
10
7
6
8
High (Silt)
10
48
40
21
25
18
14
19
18% slope, 50' length
Low (Sand)
2
8
7
3
3
2
2
3
Mod (Clay)
5
23
19
10
11
9
7
9
High (Silt)
11
53
44
23
28
23
16
21
Re-
Construction
Construction with Single Best Management Practice Implemented
construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed. Del
Sed Del.
Sed Del
Sed Del.
Boise, Idaho
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
0
1
0
0
0
0
0
0
Mod (Clay)
0
2
1
1
1
1
0
1
High (Silt)
1
4
3
2
2
2
1
2
7% slope, 140' length
Low (Sand)
0
1
1
1
0
0
0
0
Mod (Clay)
0
4
2
2
1
1
1
1
High (Silt)
1
8
6
4
4
3
2
3
12% slope, 100' length
Low (Sand)
0
2
1
1
1
1
1
1
Mod (Clay)
1
6
4
3
2
2
2
2
High (Silt)
2
14
10
8
5
5
4
6
18% slope, 50' length
Low (Sand)
0
2
2
1
1
1
1
1
Mod (Clay)
1
7
5
4
2
2
2
3
Hiah fSiltl
2
1fi
11
A
A
e;
c
-------
Pre-
Construction
Construction wilh Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Sitt Fence
Check Dam
Sed Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed Del.
Sed. Del.
Sed Del
Sed. Del
Nashville, Tennessee
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
4
12
7
5
8
7
3
5
Mod (Clay)
10
33
20
15
24
21
10
13
High (Silt)
24
78
47
36
57-
50
23
31
7% slope, 140' length
Low (Sand)
8
25
15
12
15
11
8
10
Mod (Clay)
22
72
44
33
50
38
22
29
High (Silt)
52
170
103
78
120
94
51
68
12% slope, 100'length
Low (Sand)
14
43
26
20
23
16
13
17
Mod^Clay)
37
122
74
56
79
57
37
49
High (Silt)
88
287
173
131
191
139
86
115
18% slope, 50' length
Low (Sand)
15
48
29
22
27
21
14
19
Mod (Clay)
41
135
82
62
91
77
40
54
High (Silt)
97
318
192
145
221
187
95
127
Re-
Construction
Construction with Single Best Management Practice Implemented
construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed.Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed Del.
Sed Del.
Sed Del.
Sed. Del.
Hartford, Connecticut
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
2
7
19
3
2
4
4
2
3
Mod (Clay)
5
9
6
13
12
6
8
High (Sitt)
11
44
22
13
31
28
13
18
7% slope, 140' length
Low (Sand)
4
15
7
4
8
6
4
6
Mod (Clay)
11
41
21
12
27
20
12
16
High (Silt)
25
97
48
29
65
50
29
39
12% slope, 100' length
Low (Sand)
7
25
12
7
11
8
7
10
Mod (Clay)
18
69
35
21
41
29
21
28
High (Sitt)
42
164
82
49
101
72
49
65
18% slope, 50' length
Low (Sand)
7
27
14
8
13
10
8
11
Mod (Clay)
20
77
38
23
48
39
23
31
High (Silt)
47
181
91
54
117
97
54
72
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed. Del
Sed. Del.
Sed. Del.
Sed. Del.
Atlanta, Georgia
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
5
15
10
7
11
10
5
6
Mod (Clay)
13
44
28
19
33
29
13
17
High (Silt)
31
103
66
44
80
70
31
41
7% slope, 140' length
Low (Sand)
11
34
22
14
23
18
10
13
Mod (Clay)
29
95
61
41
72
58
29
38
High (Silt)
68
225
144
96
173
139
67
90
12% slope, 100" length
Low (Sand)
18
57
37
24
37
26
17
23
Mod (Clay)
49
161
104
69
117
88
48
64
High (Silt)
115
379
*" L4
163
280
215
114
152
,8% slope, 50' length
Low (Sand)
20
63
27
43
36
19
25
Mod (Clay)
54
178
76
* n r\
134
117
53
71
-------
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed Del
Sed Del.
Sed. Del
Sed Del
Charleston, South Carolina
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
7
21
13
7
16
14
6
9
Mod (Clay)
19
60
36
19
48
42
18
24
High (Silt)
45
142
85
46
115
101
43
57
7% slope, 140' length
Low (Sand)
15
47
28
15
35
27
14
19
Mod (Clay)
41
132
79
42
106
87
40
53
High (Silt)
97
311
185
100
251
208
93
124
12% slope, 100' length
Low (Sand)
26
79
47
25
56
42
24
32
Mod (Clay)
69
223
133
72
172
136
67
89
High (Sin)
165
525
313
169
410
327
158
210
18% slope, 50' length
Low (Sand)
28
87
52
28
65
56
26
35
Mod (Clay)
77
247
147
79
196
176
74
99
High (Silt)
182
581
346
187
467
421
174
232
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Sitt Fence
Check Dam
Sed Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed Del.
Sed Del.
Sed. Del
Sed Del
Amarillo, Texas
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
1
5
3
2
3
3
2
2
Mod (Clay)
4
14
9
7
10
9
4
6
High (Silt)
9
33
22
16
25
22
10
13
7% slope, 140' length
Low (Sand)
3
11
7
5
7
5
3
4
Mod (Clay)
9
31
21
15
22
18
9
12
High (Silt)
20
73
49
35
54
42
22
29
12% slope, 100' length
Low (Sand)
5
18
12
9
11
8
6
7
Mod (Clay)
14
52
35
25
36
26
16
21
High (Silt)
34
123
82
58
86
64
37
49
18% slope, 50' length
Low (Sand)
6
20
14
10
13
10
6
8
Mod (Clay)
16
58
39
27
41
35
17
23
High (Silt)
38
136
91
65
99
86
41
54
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed.Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed Del.
Sed Del
Sed Del
Sed. Del
San Antonio, Texas
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope. 200' length
Low (Sand)
4
13
8
6
9
8
4
5
Mod (Clay)
12
36
22
18
28
24
11
14
High (Silt)
28
85
52
42
67
58
26
34
7% slope, 140' length
Low (Sand)
10
28
17
14
20
15
8
11
Mod (Clay)
26
79
48
39
61
49
24
32
High (Silt)
61
186
114
92
145
118
56
74
12% slope, 100' length
Low (Sand)
16
47
29
23
31
22
14
19
Mod (Clay)
44
133
82
66
98
75
40
53
High (Silt)
103
314
192
155
235
182
94
126
18% slope, 50' length
Low (Sand)
18
52
32
26
36
30
16
21
Mod (Clay)
48
148
90
73
112
99
44
59
High (Silt)
114
347
212
172
269
238
104
139
-------
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed Del.
Sed Del.
Sed Del
Sed Del
Las Vegas, Nevada
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
0
0
0
0
0
0
0
0
Mod (Clay)
0
1
1
0
1
1
0
0
High (Silt)
0
3
1
0
2
1
1
1
7% slope, 140' length
Low (Sand)
0
1
0
0
0
0
0
0
Mod (Clay)
0
2
1
0
1
1
1
1
High (Silt)
0
5
3
1
2
2
2
2
12% slope, 100' length
Low (Sand)
0
1
1
0
0
0
0
1
Mod (Clay)
0
4
2
1
1
1
1
2
High (Silt)
0
9
5
2
3
3
3
4
18% slope, 50' length
Low (Sand)
0
2
1
0
0
0
0
1
Mod (Clay)
0
4
2
1
1
1
1
2
High (Silt)
0
10
6
2
4
3
3
4
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed Del.
Sed. Del.
Sed. Del.
Sed. Del.
Portland, Oregon
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
1
3
1
1
2
2
1
1
Mod (Clay)
2
9
3
2
5
5
3
4
High (Silt)
5
22
7
6
13
13
7
9
7% slope, 140' length
Low (Sand)
2
7
2
2
3
3
2
3
Mod (Clay)
4
20
6
5
9
8
6
8
High (Silt)
10
48
14
12
22
20
14
19
12% slope, 100' length
Low (Sand)
3
12
4
3
4
3
4
5
Mod (Clay)
7
34
10
9
12
11
10
14
High (Silt)
17
80
24
20
30
26
24
32
18% slope, 50' length
Low (Sand)
3
13
4
3
3
3
4
5
Mod (Clay)
8
38
12
10
12
11
11
15
High (Silt)
19
89
27
23
32
27
27
36
Pre-
Construction
Construction with Single Best Management Practice Implemented
Construction
no BMPs
Seeding
Seed+Mulch
Straw Bale
Silt Fence
Check Dam
Sed.Trap
Soil
Soil Loss
Soil Loss
Soil Loss
Soil Loss
Sed Del.
Sed Del.
Sed. Del.
Sed Del
Fresno, California
Erodibility
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
(tons/ac)
3% slope, 200' length
Low (Sand)
0
1
0
0
0
0
0
0
Mod (Clay)
0
2
0
0
1
1
0
1
High (Silt)
0
4
1
1
2
2
1
2
7% slope, 140' length
Low (Sand)
0
1
0
0
0
0
0
1
Mod (Clay)
0
4
1
1
1
1
1
1
High (Silt)
1
8
3
2
3
3
3
3
12% slope, 100' length
Low (Sand)
0
2
1
1
1
1
1
1
Mod (Clay)
1
6
2
1
2
2
2
2
High (Silt)
2
14
4
3
5
5
4
6
^8% slope, 50' length
Low (Sand)
0
2
1
1
1
1
1
Mod (Clay)
1
7
2
2
2
2
3
f
Hinh fRiH\
?
A
4
A
«;
c
-------
APPENDIX 1G
RUSLE RESULTS
Construction Conditions with
Combinations of Best Management Practices Scenarios
-------
Combination BMPs According to SAIC
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Des Moines, Iowa
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence
2.4
8.2
4.9
Mod (Clay)
Silt Fence+Seed&Mulch
6.5
23.3
7.5
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
15.3
54.9
5.4
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch
5.2
18.0
4.1
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
14.1
51.0
4.2
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
33.5
120.0
10.1
12% slope, 100' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
8.8
30.4
1.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
23.9
86.1
6.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
56.6
202.7
12.4
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
98
33.6
2.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
26.4
95.3
5.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
62.6
224.2
13.7
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Helena, Montana
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200" length
Low (Sand)
Silt Fence
0.1
0.7
0.4
Mod (Clay)
Silt Fence+Seed&Mulch
0.3
1.9
0.5
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
0.7
4.5
0.4
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch
0.2
1.5
0-3,
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.6
4.2
0.2
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
1 5
9.8
0.6
12% slope, 100' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
0.4
2.5
0.1
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
1.1
7.0
0.3
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
2.6
16.6
0.9
18% slope, 50" length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.4
2.8
0.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
1.2
7.8
0.4
High (Silt) ;Seed&Mulch+Check Dam+Sed.Trap
2.8
18.3
1.0
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Duluth, Minnesota
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence
1.0
4.8
2.8
Mod (Clay)
Silt Fence+Seed&Mulch
2.8
13.7
3.5
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
6.6
32.2
2.5
7% slope, 140* length
Low (Sand)
Silt Fence+Seed&Mulch
2.3
10.5
1.8
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
6.1
29.9
1.8
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
145
70.3
4.5
12% slope, 100' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
3.8
17.8
0.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
10.3
50.5
2.6
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
24.5
118.7
5.9
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
4.2
19.7
1.0
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap I
114 I
55.8
2.8
High (Sift)
Seed&Mulch+Check Dam+Sed.Trap I 27.1
131.4
6.5
qf
-------
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Bismarck, North Dakota
Erodibilrty
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence
0.5
2.5
1.4
Mod (Clay)
Silt Fence+Seed&Mulch
1.3
7.0
1.7
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
3.2
16.4
1.2
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch
1.1
5.4
09
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
2.9
15.2
0.8
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
7.0
35.8
2.1
12% slope, 100' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
1.8
9.1
0.3
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
5.0
25.7
1.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
11.8
60.5
3.0
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
2.0
10.0
0.5
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
5.5
28.4
1.4
High (Silt)
Seed&Mulch+Check Dam+Sed Trap
13.0
66.9
3.3
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Denver, Colorado
Erodibilrty
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence
0.4
2.0
1.1
Mod (Clay)
Silt Fence+Seed&Mulch
1.1
5.5
1.4
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
2.7
13.0
1.0
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch
0.9
4.3
0.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
2.5
12.1
0.7
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
58
28.5
1.7
12% slope, 100' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
1.5
72
0.3
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
4 1
20.5
0.9
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
9.8
48.2
2.5
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
1 7
8.0
0.4
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
46
22.6
1.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
10.9
53.3
2.8
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Boise, Idaho
Erodibilrty
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Sift Fence
0.1
0.6
0.3
Mod (Clay)
Silt Fence+Seed&Mulch
0.2
1.6
0.5
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
05
3.8
0.4
7% slope. 140' length
Low (Sand)
Silt Fence+Seed&Mulch
0.2
1 2
0.3
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
05
3.5
0.2
High (Silt) [Silt Fence+Seed&Mulch+Check Dam
12
8.3
0.6
12% slope, 100' length
Low (Sand) I Silt Fence+Seed&Mulch+Check Dam
03
2.1
0.1
Mod (Clay) Silt Fence+Seed&Mulch+Check Dam
08
6.0
0.3
High (Silt) Seed&Mulch+Check Dam+Sed.Trap
2.0
14.1
0.9
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
03
2.3
0.2
Mod (Clay) j
Seed&Mulch+Check Dam+Sed.Trap
09
6.6
0.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
2.2
15.5
1 0
1p
-------
1 Acre Site
Construction
Combination
Sort
1 Acre Site
Baseline
No BMP
BMP
Nashville, Tennessee
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Sitt Fence
3.7
11.7
6.9
Mod (Clay)
Silt Fence+Seed&Mulch
10.0
33.1
9.5
High (Silt)
Sitt Fence+Seed&Mulch+Check Dam
23.7
77.8
6.8
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch
8.1
25.5
5.3
Mod (Clay)
Sitt Fence+Seed&Mulch+Check Dam
21.9
72.2
5.3
High (Sift)
Sitt Fence+Seed&Mulch+Check Dam
51.9
170.0
12.9
12% slope, 100'length
Low (Sand)
Sitt Fence+Seed&Mulch+Check Dam
13.7
43.1
2.2
Mod (Clay)
Sitt Fence+Seed&Mulch+Check Dam
37.0
122.0
7.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
87.6
287.0
15.8
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
15.1
47.6
2.6
Mod (Clay)
Seed&Mulch+Check Dam+Sed Trap
40.9
134.9
7.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
96 9
317.5
17.4
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Hartford, Connecticut
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence
1.8
6.6
3.9
Mod (Clay)
Sitt Fence+Seed&Mulch
4.8
18.8
3.4
High (Silt)
Sitt Fence+Seed&Mulch+Check Dam
11.4
44.3
2.5
7% slope, 140' length
Low (Sand)
Sitt Fence+Seed&Mulch
3.9
14.5
1.8
Mod (Clay)
Sitt Fence+Seed&Mulch+Check Dam
10.5
41.2
1.8
High (Silt)
Sitt Fence+Seed&Mulch+Check Dam
24.9
96.8
4.4
12% slope, 100' length
Low (Sand)
Sitt Fence+Seed&Mulch+Check Dam
6.6
24.5
0.7
Mod (Clay)
Sitt Fence+Seed&Mulch+Check Dam
17.8
69.5
2.6
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
42.1
163.5
5.8
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
7.3
27.1
1.0
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
19.7
76.9
2.7
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
46.6
180.9
6.5
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Atlanta, Georgia
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence
4.9
15.4
9.6
Mod (Clay)
Silt Fence+Seed&Mulch
13.1
43.7
12.5
High (Silt)
Sitt Fence+Seed&Mulch+Check Dam
31.2
102.8
8.9
7% slope, 140' length
Low (Sand)
Sitt Fence+Seed&Mulch
10.6
33.7
7.6
Mod (Clay)
Sitt Fence+Seed&Mulch+Check Dam
28.7
95.5
7.4
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
68.1
224.6
17.9
12% slope, 100'length :
Jow (Sand)
Silt Fence+Seed&Mulch+Check Dam
18.0 i 56.9
3.4
| Mod (Clay)
Sitt Fence+Seed&Mulch+Check Dam
48.5 j 161.2
11.4
| High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
115.0
379.3
19.5
18% slope, 50'length ILow(Sand)
Seed&Mulch+Check Dam+Sed.Trap
19.9
62.9
3.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
53.7
178.3
9.2
High (Silt) ; Seed&Mulch+Check Dam+Sed.Trap
127.2
419.5
21.6
Hi
-------
1 Acre Site I
Construction | Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Charleston, South Carolina
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence
7.0
21.3
14.0
Mod (Clay)
Sift Fence+Seed&Mulch
18.8
60.5
13.6
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
44 6
142.3
9.7
7% slope, 140' length
Low (Sand)
Sitt Fence+Seed&Mulch
15.2
46.6
8.8
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
41 1
132.2
8.4
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
97.4
311.0
20.1
12% slope, 100' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
25.7
78.8
4.0
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
69.4
223.2
13.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
164.5
525.1
20.3
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
28.4
87.1
3.4
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
76.8
246.9
9.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
182.0
580.9
22.4
1 Acre Site
Construction
Combinaton
Soil
1 Acre Site
Baseline
No BMP
BMP
Amanllo, Texas
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Sift Fence
1.4
5.0
3.0
Mod (Clay)
Silt Fence+Seed&Mulch
3.9
14.2
4.3
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
9.2
33.3
3.1
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch
3.2
10.9
2.5
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
8.5
31.0
2.5
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
20.2
72.9
6.1
12% slope, 100' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
5.3
18.5
1.1
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
144
52.3
3.7
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
34.1
123.1
70
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
5.9
20.4
1.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
15.9
57.9
3.3
High (Silt) ISeed&Mulch+Check Dam+Sed.Trap
37.7
136.1
7.8
1 Acre Site
Construction
Combinaton
Soil
1 Acre Site
Baseline
No BMP
BMP
San Antonio, Texas
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence
4 4
12.8
8.0
Mod (Clay)
Sitt Fence+Seed&Mulch
11.8
36.2
12.1
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
28.0
85.1
86
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch
9.6
27.9
7.5
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
25 8
79.0
7.2
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
61.2
185.9
17.4
12% slope, 100" length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
16.2
471 ! 3.3
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
43.6
133.5 I 11.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
103.4
314.0
18.6
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
17.9
52.1
3.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap I 48.3
147.6
8.8
I High (Silt) i Seed&Mulch+Check Dam+Sed.Trap I 114 4
347.3
20.6
-------
I
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Las Vegas, Nevada
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Sift Fence
0.0
0.4
0.2
Mod (Clay)
Silt Fence+Seed&Mulch
0.0
1.1
0.1
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
0.1
2.5
0.1
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch
0.0
0.8
0.1
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.1
2.3
0.0
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
0.2
5.5
0.1
12% slope, 100' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
0.1
1.4
0.0
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.1
3.9
0.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
0.3
9.3
0.2
18% slope, 50" length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.1
1.5
0.0
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
0.2
4.4
0.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
0.4
10.3
0.2
|
|
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Portland, Oregon
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons) i
3% slope, 200' length
Low (Sand)
Silt Fence
0.7
3.3
1.9
Mod (Clay)
Silt Fence+Seed&Mulch
1.9
9.3
1.4
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
4.6
21.8
1.0
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch
1.6
7.1
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
4.2
20.2
O.I
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
10.1
47.6
1.5
12% slope, 100' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
2.7
12.1
0.3
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
7.2
34.2
0.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
17.0
80.4
2.4
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
2.9
13.3
0.4
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
7.9
37.8
1.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap 1 18.8
89.0
2.7
1 Acre Site
Construction
Combination
Soil
1 Acre Site
Baseline
No BMP
BMP
Fresno, Calrfornia
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence
0.1
0.6
0.3
Mod (Clay)
Silt Fence+Seed&Mulch
0.2
1.6
0.2
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
0.4
3.8
0.2
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch
0.1
1.3
0.1
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.4
3.6
0.1
High (Silt)
Silt Fence+Seed&Mulch+Check Dam I 0 9
8.4
0.3
12% slope, 100" length
_ow(Sand) | Silt Fence+Seed&Mulch+Check Dam i 0.2
2.1 | 0.0
Mod (Clay) ! Silt Fence+Seed&Mulch+Check Dam ! 0.7
6.0 I 0.1
High (Silt) iSeed&Mulch+Check Dam+Sed.Trap i 1.6
14.1 ! 0.4
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap | 0.3
2.3
0.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap i 0.7
6.6
0.2
High (Silt) 'Seed&Mulch+Check Dam+Sed.Trap 17
15.6
0.4
-------
RUSLE LD.WK4
["Loading Reduction (% Reduction)
i
i
Size (acres) ISoil Erodibility
CO
o
¦a
e (%)
3 | med
3
7
12
18
>
<
(Q
Des Moines, IA ;
90.4%
91.8%
93.9% | 93.2%
92.3%
Helena, MT
91.2%
94.4%
94.3% | 94.4%
93.6%
Duluth, MN
92.4%
93.9%
95.0%
95.0%
94.1%
Bismarck, ND
92.8%
94.5%
95.1%
95.1%
94.4%
Denver, CO
92.2%
94.5%
94.8%
94.8%
94.1%
Boise, ID
89.8%
93.4%
93.3%
93.4%
92.5%
Nashville, TN
91.3%
92.7%
94.5%
94.5%
93.3%
Hartford, CT
94.5%
95.6%
96.5%
96.4%
95.8%
Atlanta, GA
91.4%
92.2%
94.9%
94.9%
93.3%
Charleston, SC
93.3%
93.6%
96.1%
96.1%
94.8%
Amarillo, TX
90.8%
91.9%
94.3%
94.3%
92.8%
San Antonio, TX
90.0%
90.8%
94.1%
94.1%
92.2%
Las Vegas, NV
96.9%
98.6%
98.3%
97.7%
97.9%
Portland, OR
95.3%
96.9%
97.0%
96.9%
96.5%
Fresno, CA
95.9%
97.2%
97.2%
97.0%
96.8%
MEAN
94.3%
STD DEV
0.016848
VARIANCE
0.000284
(xncUi
(^^ch CL^- ¦' :S-'~;
07/27/98, 12:40 PM
I i
O'J " Ti:-V
jJ.] ±rt,ufir u ttHP" ^ -
(W
-------
Construction Loadings Calculation Methodology
EPA worked with the U.S. Army Corps of Engineers (ACOE) to develop a model that would
estimate sediment loads from construction sites with and without Phase II controls, such as
BMPs. The ACOE used the Revised Universal Soil Loss Equation (RUSLE) to generate
sediment delivery estimates for 15 climatic regions with each of the following variations: 3 site
sizes (1, 3, and 5 acres), 3 soil erodibility levels (low, medium, and high), 4 slopes (3, 7, 12, and
18 %), and the BMPs combinations as presented in Exhibit 4-7. Sediment delivery represents the
quantity of sediment that bypasses the BMPs placed at the base of the hill slope.
To simplify the analysis of the loadings estimates generated by the RUSLE analysis, a 3 acre site
with medium erodibility and slopes ranging from 3 to 18% was selected as the model scenario.
The following assumptions were made:
Average site size is 3 acres. This value is based on information obtained on construction
starts from the U.S. Department of Commerce, Bureau of the Census (cite, 199#). This is
also the site size used in the cost analysis.
Soil erodibility is medium. Medium erodibility was selected as a reasonable average for
the three soil erodibility types (low, medium, high). This was also the soil type selected
in the costing of BMPs.
To determine the average sediment load per acre disturbed, all values were added across each
slope category (3, 7, 12, or 18%) and divided by 4. This provided an average sediment load per
climatic region for a 3 acre site with moderately erodible soil. Then, the average loads were
divided by 15 (the number of climatic regions) to obtain a national average sediment load per
site. Dividing the site load average by 3 (the number of acres per site) provides an average
sediment load per acre of 2.8 tons.
Limitations of the ACOE's analysis include:
The sediment loss calculation is actually for a hillslope, from sheet and rill erosion, and that it
does not predict sediment yield from a construction site.
-------
Exhibit 4-9. Sediment Delivery (tons) for Average 3 Acre Construction Site
Size (acres)
Soil Erodibility
Slope (%)
Average
Load (tons)
3
med
3
7
12
18
Des Moines, IA
6.7
12.5
15.8
17.5
13.1
Helena, MT
0.5
0.7
1.2
1.3
0.9
Duluth, MN
3.1
5.5
7.5
8.3
6.1
Bismarck, ND
1.5
2.5
3.8
4.2
3.0
Denver, CO
1.3
2.0
3.2
3.5
2.5
Boise, ID
0.5
0.7
1.2
1.3
0.9
Nashville, TN
8.6
15.8
20.1
22.2
16.7
Hartford, CT
3.1
5.4
7.4
8.2
6.0
Atlanta, GA
11.3
22.3
24.9
27.5
21.5
Charleston, SC
12.2
25.2
25.8
28.6
23.0
Amarillo, TX
3.9
7.5
8.9
9.9
7.6
San Antonio, TX
10.9
21.7
23.8
26.3
20.7
Las Vegas, NV
0.1
0.1
0.2
0.3
0.2
Portland, OR
1.3
1.9
3.1
3.5
2.5
Fresno, CA
0.2
0.3
0.5
0.6
0.4
Average Loadings per Site (tons)
Average Loadings per Acre (tons)
8.3
2.8
U.S. Army Corps of Engineers, Analysis of Best Management Practices for Small Construction Sites, for U.S.
Environmental Protection Agency, Washington, D.C. June 1998.
/ OX
-------
Combination BMPs According to SAIC
I
3 Acre Site
I
Construction
Combination
Soil
3 Acre Site I Baseline
No BMP
BMP
Des Moines, Iowa
Erodibilrty
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
7.2
24.7
7.5
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
19.4
70.0
6.7
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
46.0
164.8
16.1
7% slope, 140'length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
15.7
54.0
3.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
42.4
153.0
12.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
100.5
360.1
22.0
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
26.5
91.2
5.6
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
71.6
258.4
15.8
High (Sitt) '
Seed&Mulch+Check Dam+Sed.Trap
169.8
608.1
37.2
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
29.3
100.9
6.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
79.2
285.9
17.5
High (Silt)
Seed&Mulch+Check Dam+Sed Trap
187.8
672.7
41.2
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Helena, Montana
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
0.3
2.0
0.5
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.9
5.7
0.5
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
2.1
13.5
1.1
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam j 0.7
4.4
0.2 '
Mod (Clay)
Sift Fence+Seed&Mulch+Check Dam i 1.9
12.5
0.7
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap > 4.6
29.5
1.6
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap 1.2
7 5
0.4
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap ! 3.2
21.1
1.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap 7.7
49.7
2.7
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap ! 13
8.3
0.5
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap > 3.6
23 4
1.3
High (Sift)
Seed&Mulch+Check Dam+Sed.Trap 8.5
55.0
3.0
I
I
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Duluth, Minnesota
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
3.1
14.5
3.5
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
8.4
41.0
3.1
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
19.9
96.5
7.5
7% slope, 140" length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
6.8
31.6
1.6
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
18.4
89.7
5.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap i 43.5
211.0
10.5
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
11.5
53.4
2.7
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
31.0 l 151.4
7.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
73 5 i 356.2
17.7
18% slope, 50" length
_ow (Sand)
Seed&Muich+Check Dam+Sed.Trap !
12.7
59.1
2.9
IMod(Clay) |Seed&Mulch+Check Dam+Sed.Trap I
34.3
167.5
8.3
I High (Sift) iSeed&Mulch+Check Dam+Sed Trap
81.3
394.1
19.6.
|0*5
-------
3 Acre Site
Construction
Combination ,
Soil
3 Acre Site
Baseline
No BMP
BMP ;
Bismarck, North Dakota
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons);
!
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
1.5
7.4
1.8 j
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
4.0
20.9
1.5
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
9.6
49.1
3.7
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
3.3
16.1
0.8
Mod (Clay)
Sitt Fence+Seed&Mulch+Check Dam
8.8
45.6
2.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
20.9
107.4
5.3
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
5.5
27.2
1.3
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
14.9
77.1
3.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
35.3
181.4
8.9
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
6.1
30.1
1.5
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
16.5
85.3
4.2
High (Silt)
Seed&Mulch+Check Dam+Sed Trap
39 1
200 6
9.8
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Denver, Colorado
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
1.2
5.9
1.5
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
3.4
16.6
1.3
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
8.0
39.1
3.1
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
2.7
12.8
0.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
74
36.4
2.0
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
175
85.6
4.5
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
46
21.7
1.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
12.4
61.4
3.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
29.5
144.5
7.5
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
5.1
24.0
1.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
13.8
67.9
3.5
I High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
32.6
1598
8.3
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Boise, Idaho
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
0.3
1.7
0.5
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.7
4.9
0.5
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
1 6
11.4
1.1
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
0.5
3.7
0.2
I Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
1.5
10.6
0.7
I High (Sift)
Seed&Mulch+Check Dam+Sed.Trap
3.5
25.0
1.6
12% slope, 100' length j Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.9
6.3
0.4
I Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
2.5 ' 17.9
1.2
I High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
5.9
42.2
2.7
18% slope, 50' length j Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
1.0
7 0
0.5
I Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
2.8 i 19.8
1.3
IHiqh(Silt) i
Seed&Mulch+Check Dam+Sed.Trap
6.5 I 46.6
3.0
(Otf
-------
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Nashville, Tennessee
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
11.1
35.0
9.5
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
30.1
99.2
8.6
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
71.2
233.3
20.5
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
24.3
76.5
4.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
65.7
216.7
15.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
155.7
510.0
28.0
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
41.1
129.2
7.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
110.9 ,
366.0
20.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
262.9
861.1
47.3
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
45.4
142.9
7.9
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
122.7
404.8
22.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
290.8
952.6
52.3
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Hartford, Connecticut
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
5.3
19.9
3.5
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
14.4
56.5
3.1
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
34.2
132.9
7.4
7% slope, 140" length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
11.7
43.6
i.flf !
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
31.6
123.5
5.
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
74.8
290.5
10.4" I
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
19.7
73.6
2.6 !
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
53.3
208.5
7.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
126.4
490.6
17.5
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
21.8
81.4
2.9
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
59.0
230.6
8.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
139.8
542.6
19.4
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Atlanta, Georgia
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
14.6
46.2
12.4
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
39.4
131.0
11.3
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
93.5
308.3
26.8
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
31.9
101.1
6.8
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
86.2
286.4
22.3
! High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
204 3
673.8
34.7
12% slope, 100' length Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
53.9
170.7
8.8
I Mod (Clay) | Seed&Mulch+Check Dam+Sed.Trap
145 6
483.6
24.9
i High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
345.0
1137.8
58.5
18% slope, 50' length Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
59.6
188.8
9.7
[Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
161.0
534.9
27.5
iHigh (Silt) !Seed&Mulch+Check Dam+Sed Trap
381 6
1258.6
64.Z,
-------
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Charleston, South Carolina
Erodibilrty
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200" length
Low (Sand)
Silt Fence+Seed&Mulch
20.9
64.0
13.5
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
56.4
181.4
12.2
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
133.7
426.9
29.2
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
45.7
139.9
7.9
Mod (Clay)
Sift Fence+Seed&Mulch+Check Dam
123.3
396.5
25.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
292.3
932.9
36.0
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
77.1
236.3
9.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
208.2
669.6
25.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
493.5
1575.4
60.8
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
85.3
261.4
10.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
230.3
740.6
28.6
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
545.9
1742.7
67.2
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Amanllo, Texas
Erodibilrty
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
4.3
15.0
4.3
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
11.7
42.5
3.9
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
27.7
100.0
9.3
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
95
32.8
2.3
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
25.6
92.9
7.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
60.6
218.7
12.5
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
16.0
55.4
3.2
| Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
43.1
156.9
8.9
High (Sift)
Seed&Mulch+Check Dam+Sed.Trap
102.3
369.2
21.1
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
177
61.3
3.5
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
47 7
173.6
9.9
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
113 1
408.4
23.3
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
San Antonio, Texas
Erodibilrty
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
13.1
38.3
11.9
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
35.5
108.5
10.9
High (Silt)
Silt Fence+Seed&Mulch+Check Dam
84.1
255.2
25.9
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
28.7
83.7
6.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
77.5
237.1
21.7
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
183 7
557.8
33.1
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
48.5
141.3
8.4
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
130.9 I 400.4
23.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
310.3
942.0
55.9
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
53.6
156.3
9.3
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
144.8
442.8
26.3
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
343.2
1042.0
61.8
I
-------
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Las Vegas, Nevada
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
0.0
1.1
0.1
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.1
3.2
0.1
High (Silt)
Sitt Fence+Seed&Mulch+Check Dam
0.3
7.5
0.2
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
0.1
2.5
0.0
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.2
7.0
0.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
0.6
16.5
0.3
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.2
4.2
0.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
0.4
11.8
0.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
1.0
27.8
0.6
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.2
4.6
0.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
0.5
13.1
0.3
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
1.1
30.8
0.6
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Portland, Oregon
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch
2.2
9.8
1.4
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
5.8
27.8
1.3
High (Sitt) Silt Fence+Seed&Mulch+Check Dam
13.8
65.4
3.0
7% slope, 140' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
4.7
21.4
0.6
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
12.7
60.7
1.9
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
30.2
142.9
4.3 '
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
8.0
36.2
1.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed Trap
21.5
102.6
3.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
51.0
241.3
7.3
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
8.8
40.0
1.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
23.8
113.5
3.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
56.4
267.0
8.1
3 Acre Site
Construction
Combination
Soil
3 Acre Site
Baseline
No BMP
BMP
Fresno, California
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Sitt Fence+Seed&Mulch
0.2
1.7
0.2
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.5
4.9
0.2
High (Silt)
Sitt Fence+Seed&Mulch+Check Dam
1.3
11 5
0.5
7% slope, 140' length
low (Sand)
Silt Fence+Seed&Mulch+Check Dam
0.4
3.8
0.1
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
1.2
10.7
0.3
High (Silt)
Seed&Mulch+Check Dam+Sed Trap
2.8
25.1
0.7
12% slope, 100'length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.7
64
0.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
2.0
18.0
0.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
4.7
42.4
1 3
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.8
7.0
0.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
2.2
19.9
0.6
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
5.2
46.9
1.4
IDt
-------
Combination BMPs According to SAIC
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Des Moines, Iowa
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
12.0
41.2
3.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
32.3
116.7
11.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
76.7
274.6
16.8
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
26.2
90.0
5.5
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
70.7
255.1
15.6
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
167.5
600.2
36.7
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
44.2
152.0
9.3
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
119.4
430.7
26.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
282.9
1013.5
62.0
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
48.9
168.2
10.3
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
132.0
476.5
29.2
High (Silt)
Seed&Mulch+Check Dam+Sed Trap
312.9
1121.1
68.6
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Helena, Montana
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
0.5
3.4
0.3
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
1.5
9.5
0.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
3.5
22.5
1.2
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
1.2
7.4
0.4
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
3.2
20.9
1.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
7.6
49.1
2.7
12% slope, 100'length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
2.0
12.4
0.7
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
5.4
35.2
1.9
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
12 8
82.9
4.6
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed Trap
2.2
13.8
0.8
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
6.0
39.0
2.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
14.2
91.7
5.0
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Duluth, Minnesota
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
5.2
24.1
1.8
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
14.0
68.4
5.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
33.2
160.9
8.0
7% slope, 140" length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
11.3
52.7
2.6
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
30.6
149.4
7.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
72.5
351.6
17.5
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
19.1
89.1
4.4
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
51 7
252.3
12.6
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
122.4
593.7
29.6
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
21.2
98.5
4.9
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
57.1
279.1
13.9
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
135.4
656.8
32.7
|D$
-------
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Bismarck, North Dakota
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
2.5
12.3
0.9
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
6.7
34.8
2.6
High (Sitt)
Seed&Mulch+Check Dam+Sed.Trap
16.0
81.9
4.0
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
5.4
26.8
1.3
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
14.7
76.1
3.7
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
34.9
179.0
8.8
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
9.2
45.3
2.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
24.8
128.5
6.3
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
58.9
302.3
14.8
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
10.2
50.2
2.5
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
27.5
142.1
7.0
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
65.1
334.3
16.4
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Denver, Colorado
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
2.1
9.8
0.7
Mod (Clay)
Sift Fence+Seed&Mulch+Check Dam
5.6
27.7
2.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
13.3
65.2
3.4
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
4.5
21.4
1.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
12.3
60.6
3.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
29.1
142.6
7.4
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
7.7
36.1
1.9
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
20.7
102.3
5.3
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
49.1
240.8
12.5
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
8.5
40.0
2.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
22 9
113.2
5.9
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
54 3
266.4
13.9
5 Acre Site
Construction
Combination
SoU
5 Acre Site
Baseline
No BMP
BMP
Boise, Idaho
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
0.4
2.9
0.3
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
1.1
8.1
0.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
2.7
19.0
1.2
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.9
6.2
0.4
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
2.5
17.7
1.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
5.8
41.6
2.7
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
1 5
10.5
0.7
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
4.2
29.9
1.9
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
9.9
70.3
4.6
18% slope, 50' length
-ow (Sand)
Seed&Mulch+Check Dam+Sed.Trap
1 7
11.7
0.8
Vlod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
46
33.0
2.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
10.9
77.7
5.0
1*1
-------
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Nashville, Tennessee
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
18.6
58.3
48
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
50.1
165.3
14.3
High (Sift)
Seed&Mulch+Check Dam+Sed.Trap
1187
388.9
21.4
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
40.5
127.5
7.0
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
109.5
361.2
19.9
High (Sift)
Seed&Mulch+Check Dam+Sed.Trap
259.5
849.9
46.7
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
68.5
215.3
11.8
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
184 9
610.0
33.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
438 2
1435.2
78.9
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
75.7
238.1
13.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
204.5
674.7
37.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
484.7
1587.6
87.2
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Hartford, Connecticut
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
8.9
33.2
1.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
24.1
94.2
5.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
57.1
221.5
7.9
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed Trap
195
72.6
2.6
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
52.6
205.8
7.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
124.7
484.2
17.3
12% slope, 100'length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
32.9
122.6
4.4
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
88.8
347.5
12.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
210.6
817.6
29.2
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
36.4
135.7
4.8
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
98.3
384.4
13.7
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
232.9
904.4
32.3
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Atlanta, Georgia
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
24.3
77.1
6.2
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
65.7
218.4
18.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
155.8
513.8
26.4
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed Trap
53.2
168.4
8.7
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
143.7
477.3
24.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
340.5
1123.0
57.8
12% slope, 100'length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
89.8
284.4
14.6
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
242.6
805.9
41.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
575.0
1896.3
97.5
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
99.4
314.6
16.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
268.3
891.5
45.9
High (Silt)
Seed&Mulch+Check Dam+Sed Trap
636.1
2097.6
107.9
1(0
-------
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Charleston, South Carolina
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200" length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
34.8
106.7
6.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
94.0
302.4
20.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
222.9
711.4
27.4
7% slope, 140" length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
76.1
233.2
9.0
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
205.5
660.8
25.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
487.1
1554.9
60.0
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
128.5
393.9
15.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
347.0
1115.9
43.0
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
822.5
2625.7
101.3
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
142.2
435.7
16.8
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
383.8
1234.4
47.6
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
909.8
2904.4
112.0
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Amanita, Texas
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
7.2
25.0
2.2
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
19.5
70.9
6.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
46.2
166.7
9.5
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
15.8
54.7
3.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
42.6
154.9
8.8
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
100.9
364.4
20.8
12% slope, 100" length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
26.6
92.3
5.3
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
71.9
261.5
14.9
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
170.5
615.4
35.1
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
29.5
102.1
5.8
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
79.5
289.3
16.5
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
188.6
680.7
38.8
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
San Antonio, Texas
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
21.9
63.8
6.0
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
59.1
180.8
18.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
140.1
425.4
25.2
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
47.8
139.5
8.3
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
129.2
395.1
23.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
306.2
929.7
55.2
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
80.8
235.5
14.0
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
218.1
667.3
39.6
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
517.1
1570.0
93.1
18% slope, 50' length
-ow (Sand)
Seed&Mulch+Check Dam+Sed.Trap
89.4
260.5
15.5
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
241.3
738.1
43.8
High (Silt)
Seed&Mulch+Check Dam+Sed Trap
572.0
1736.7
103.0
u\
-------
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Las Vegas, Nevada
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
0.1
1.9
0.1
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.2
5.3
0.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
0.4
12.6
0.3
7% slope, 140'length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.1
4.1
0.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
0.4
11.7
0.2
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
1.0
27.4
0.6
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.3
7.0
0.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
0.7
19.7
0.4
High (Silt)
Seed&Mulch+Check Dam+Sed Trap
1.6
46.3
1.0
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
0.3
7.7
0.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
0 8
21 8
0.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
1 8
51.3
1.1
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Portland, Oregon
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
3.6
16.3
0.7
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
97
46.3
2.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
23.0
109.0
3.3
7% slope, 140' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
7.9
35.7
1.1
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
21.2
101.2
3.1
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
50 4
238.2
7.2
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
13 3
60.3
1.8
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
35.9
171.0
5.2
High (Sift)
Seed&Mulch+Check Dam+Sed.Trap
85 0
402.2
12.2
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed Trap
147
66.7
2.0
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
39 7
189.1
5.8
High (Silt)
Seed&Mulch+Check Dam+Sed Trap
94.1
444.9
13.5
5 Acre Site
Construction
Combination
Soil
5 Acre Site
Baseline
No BMP
BMP
Fresno, California
Erodibility
Recommended BMPs
Soil Loss (tons)
Soil Loss (tons)
Sed. Del. (tons)
3% slope, 200' length
Low (Sand)
Silt Fence+Seed&Mulch+Check Dam
03
2.9
0.1
Mod (Clay)
Silt Fence+Seed&Mulch+Check Dam
0.9
8.1
0.4
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
2.1
19.1
0.6
7% slope, 140'length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
07
6.3
0.2
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
1.9
17.8
0.5
High (Silt)
Seed&Mulch+Check Dam+Sed Trap
46
41.8
1.2
12% slope, 100' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
1.2
10.6
0.3
Mod (Clay)
Seed&Mulch+Check Dam+Sed.Trap
3.3
30.0
0.9
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
7.8
70.6
2.1
18% slope, 50' length
Low (Sand)
Seed&Mulch+Check Dam+Sed.Trap
1.3
11.7
0.3
Mod (Clay)
Seed&Mulch+Check Dam+Sed Trap
36
33.2
1.0
High (Silt)
Seed&Mulch+Check Dam+Sed.Trap
86
78 1
2.3
-------
APPENDIX 2A
AGNPS RESULTS
Sediment Yield and Sediment Deposition
-------
AGNPS Results for the Impact An
alysis of P
e-Construc
ton to Vary
ng Construction Conditions | |
1 1 1
I I
On* -3 ac
re Constru
ction Site
Five • 3 acre Construction Sites
Ten -3 acre Construction Sites
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Drainage
Peak Rate
Cell
Entenng
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Cell
Area
of Runoff
ErotK>n
Cell
Within
Yield
Deposrfion
Erosion
Cell
Within
Yield
Oe position
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Number
(acres)
(cfs)
(t/a)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
FILE
99SAFLPR TAB
99 acre Watershed, Sandy Soil, Flat (3% Slope)
99 acre Watershed, Sandy Soil. Flat (3% Slope)
99 acre Watershed, Sandy Soil. Flat (3% Slope)
99 acre Watershed, Sandy Soil, Flat (3% Slope)
5
3
1887
1 57
0
5
1
66
1 57
0
5
1
88
538
0
16
2
87
S 38
0
18
2
87
9
12
35 27
1 57
2
5
1
79
538
2
16
2
66
538
3
16
3
83
538
3
16
3
83
13
27
54 84
1 57
3
5
3
60
1 57
4
5
4
57
1 57
5
5
4
55
538
6
16
6
72
17
48
76 23
1 57
5
5
S
49
1 57
6
5
5
48
1 57
8
5
7
44
1 57
10
5
9
42
27
99
11505
1 57
10
5
9
36
1 57
10
5
10
35
1 57
12
5
11
32
1 57
15
5
14
30
FILE
90SAROPR TAB
99 acre Watershed. Sandy Soil. Roiling (7% Slope)
99 acre Watershed. Sandy Soil, Rolling (7% Slope)
99 acre Watershed. Sandy Soil, Rolling (7% Slope)
99 acre Watershed, Sandy Soil, Rolling (7% Slope)
5
3
19 31
4 33
0
13
2
67
4 33
0
13
2
87
14 89
0
45
6
86
14 89
0
45
6
86
9
12
40 35
4 33
5
13
4
77
1489
5
45
7
85
14 89
10
45
10
81
14 89
10
45
10
81
13
27
62 85
4 33
9
13
8
64
433
12
13
10
80
4 33
15
13
12
57
14 89
17
45
17
72
17
48
87 57
4 33
14
13
12
54
433
16
13
14
52
4 33
23
13
19
47
4 33
31
13
25
43
27
99
132 61
4 33
26
13
23
40
4 33
27
13
24
39
4 33
33
13
29
36
4 33
42
13
37
33
FILE'
99SASTPR TAB
69 acre Watershed. Sandy Soil, Steep (12% Slope)
99 acre Watershed, Sandy Soil. Steep (12% Slope)
99 acre Watershed. Sandy Soil, Steep (12% Slope)
99 acre Watershed, Sandy Soil, Steep (12% Slope)
5
3
21 04
8 07
0
24
3
86
8 07
0
24
3
86
27 75
0
83
12
85
27 75
0
83
12
85
9
12
43 96
8 07
10
24
6
76
27 75
10
83
15
84
27 75
19
83
21
80
27 75
19
83
21
80
13
27
88 36
8 07
18
24
15
63
8 07
24
24
20
59
8 07
30
24
24
56
27 75
35
83
35
70
17
48
95 69
8 07
27
24
24
53
8 07
32
24
27
51
8 07
46
24
39
45
8 07
62
24
51
41
27
99
14S 24
8 07
50
24
45
40
8 07
53
24
48
39
8 07
66
24
58
35
8 07
85
24
75
32
FILE
99SAVSPR TAB
99 acre Watershed. Sandy Soil, Very Steep
18% Slope)
99 acre Watershed, Sandy Soil, Very Steep
18% Slope)
99 acre Watershed, Sandy Soil, Very Steep
18% Slope)
99 acre Watershed, Sandy Soil, Very Steep
18% Slope)
5
3
22 44
11 04
0
33
5
88
11 04
0
33
5
86
37 94
0
114
17
85
37 94
0
114
17
85
9
12
46 89
11 04
14
33
12
74
37 94
14
114
22
63
37 94
27
114
30
79
37 94
27
114
30
79
13
27
73 00
11 04
26
33
23
62
11 04
35
33
29
57
11 04
44
33
35
54
37 94
52
114
52
69
17
48
102 29
, 11 04
39
33
35
52
11 04
46
33
40
49
11 04
68
33
57
43
11 04
91
33
75
39
27
99
155 52
11 04
73
33
68
38
11 04
78
33
70
37
11 04
97
33
86
34
11 04
126
33
111
30
-------
AGNPS Results for the Impact Analysis of Pre-Construction to Varying Construction Conditions | |
I l I
I l
One - 3 acre Construction Site
Five • 3 acre Construction Sites
Ten - 3 acre Construe
"tlon Sites
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Drainage
Peak Rate
Cell
Entering
Generated
Sediment
Sediment
Oil
Entenng
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Cell
Area
of Runoff
Erosion
Cell
Within
Yield
Deposition
Ero*ion
Cell
Within
Yield
Oeposrtwn
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Number
(acres)
(cfs)
m
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(Ions)
(tons)
(%)
m
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
FILE
99CLFLPR TAB
99 acre Watershed. Clay©/ Soil, Flat (3% Slope)
99 acre Watershed. Clayey Soil, Flat (3% Slope)
99 acre Watershed, Clayey Soil, Flat (3% Slope)
99 acre Watershed. Clayey Soil, Flat (3% Slope)
5
3
29 22
4 23
cr
13
e
50
4 23
0
13
6
50
1525
0
46
23
49
15 25
0
46
23
49
9
12
01 85
4 23
19
13
16
49
15 25
19
46
29
55
15 25
36
46
40
52
15 25
36
46
40
52
13
27
96 56
4 23
34
13
29
37
4 23
47
13
38
37
4 23
57
13
45
36
15 25
67
4Q
66
41
17
48
135 45
4 23
52
13
46
29
4 23
60
13
53
28
4 23
89
13
74
27
4 23
118
13
96
27
27
99
205 86
4 23
97
13
87
20
4 23
103
13
92
20
423
126
13
113
19
4 23
163
13
144
18
file
99CLROPR TAB
99 acre Watershed, Clayey Soil, Rolling (7% Slope)
99 acre Watershed. Clayey Soil. Rolling (7% Slope)
99 acre Watershed, Clayey Soil, Rolling (7% Slope)
99 acre Watershed. Clayey Soil, Rolling (7% Slope)
5
3
33 43
11 70
0
35
19
46
11 70
0
35
19
48
42 20
0
127
69
45
42 20
0
127
69
45
9
12
70 77
11 70
56
35
51
44
42 20
56
127
92
50
42 20
107
127
125
47
42 20
107
127
125
47
13
27
11072
11 70
106
35
93
34
11 70
147
35
121
33
11 70
180
35
145
32
42 20
213
127
214
37
17
48
155 61
11 70
163
35
146
27
11 70
192
35
168
26
11 70
283
35
239
25
11 70
376
35
312
24
27
99
237 28
11 70
305
35
275
19
11 70
325
35
292
19
11 70
404
35
362
18
11 70
527
35
468
17
FILE
99CLSTPR TAB
99 acre Watershed Clayey Soil, Steep (12% Slope)
99 acre Watershed. Clayey Soil. Steep (12% Slope)
99 acre Watershed. Clayey Soil. Steep (12% Slope)
99 acre Watershed. Clayey Soil, Steep (12% Slope)
5
3
36 42
21 80
0
65
36
44
21 80
0
65
36
44
76 63
0
236
134
43
78 63
0
236
134
43
9
12
77 10
21 80
109
65
103
41
78 63
109
236
184
47
78 63
207
236
251
43
78 63
207
236
251
43
13
27
120 81
21 50
213
65
190
32
21 60
294
65
249
31
21 80
361
65
300
30
78 63
427
236
436
34
17
48
170 03
21 80
333
65
301
25
21 60
392
65
348
24
21 80
577
65
496
23
21 80
766
65
648
22
27
99
259 67
21 60
625
65
568
18
21 80
666
65
604
17
21 80
834
65
752
16
21 80
1069
65
971
16
FILE
99CLVSPR TAB
99 acre Watershed Clayey Soil, Very Steep (18% Slope)
99 acre Watershed. Clayey Soil, Very Steep (18% Slope)
99 acre Watershed. Clayey Soil, Very Steep (18% Slope)
99 acre Watershed, Clayey Soil, Very Steep (16% Slop
>
5
3
38 85
29 00
0
89
51
43
29 80
0
89
51
43
107 49
0
322
188
42
107 49
0
322
188
42
9
12
82 24
29 80
154
09
149
39
107 49
154
322
264
45
107 49
291
322
361
41
107 49
291
322
361
41
13
27
129 01
26 80
307
89
280
29
29 80
422
69
367
26
29 80
519
89
442
27
107 49
616
322
642
32
17
48
181 76
29 60
487
89
445
23
29 80
574
89
515
22
29 80
843
89
734
21
29 60
1117
69
959
21
27
99
278 29
29 80
918
89
840
17
29 80
979
89
895
16
29 80
1230
89
1116
15
29 80
1008
89
1444
15
-------
AGNPS Results for the Impact Analysis of Pre-Construction to Varying Construction Conditions I I
I i l
I I
One • 3 acre Construction Site
Five - 3 acre Construction Sites
Ten - 3 acre Construction Sites
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Drainage
Peak Rate
Cell
Entering
Generated
Sediment
Sediment
Cell
Entering
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Cell
Entering
Generated
Sediment
Sediment
Cell
Area
of Runoff
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Erosion
Ceil
Within
Yield
Deposrtion
Erosion
Cell
Within
Yield
Deposition
Number
(acres)
fcfs)
(t/a)
(tons)
(tons)
(tons)
(*)
(t/a)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%>
m
(tons)
(tons)
(tons)
(%)
FILE
99SLFLPR TAB
99 acre Watershed. Silty Soil, Fiat (3% Slope)
99 acre Watershed, Silty Soil, Flat (3% Slope)
99 acre Watershed, Silty Soil, Flat (3% Slope)
99 acre Watershed, Silty Soil, Flat (3% Slope)
5
3
32 28
10 02
0
30
13
57
10 02
0
30
13
57
35 89
0
108
48
56
35 69
0
108
48
56
e
12
68 49
10 02
39
30
33
53
35 89
39
108
59
60
35 89
74
108
80
56
35 89
74
108
80
56
13
27
107 00
10 02
68
30
56
43
10 02
95
30
73
41
10 02
115
30
87
40
35 89
136
108
130
47
17
46
150 33
10 02
101
30
87
34
10 02
118
30
100
33
10 02
175
30
141
31
1002
231
30
182
30
27
90
228 77
10 02
186
30
162
25
10 02
196
30
171
24
10 02
240
30
209
23
10 02
311
30
266
22
FILE
69SLROPR TAB
99 acre Watershed, Silty Soil. Rolling (7% Slope)
99 acre Watershed. Silty Soil, Rolling (7% Slope)
99 acre Watershed. Silty Soil, Rolling (7% Slope)
99 acre Watershed, Silty Soil. Rolling (7% Slope)
5
3
36 93
27 74
0
63
39
54
27 74
0
83
39
54
99 30
0
298
141
53
99 30
0
298
141
53
9
12
78 38
27 74
118
83
104
48
99 30
116
298
187
55
99 30
219
298
254
51
99 30
219
298
254
51
13
27
122 78
27 74
217
83
186
38
27 74
300
83
244
38
27 74
366
83
291
35
99 30
432
298
428
41
17
48
172 71
27 74
330
83
289
30
27 74
387
83
333
29
27 74
569
63
473
28
27 74
754
83
615
27
27
99
263 68
27 74
606
83
539
22
27 74
645
83
571
22
27 74
798
83
702
20
27 74
1039
83
902
20
FILE
99SLSTPR TAB
99 acre Watershed, Silty Soil. Steep (12% Slope)
99 acre Watershed, Silty Soil. Sleep (12% Slope)
99 acre Watershed, Silty Soil, Steep (12% Slope)
99 acre Watershed, Silty Soil, Steep (12% Slope)
5
3
40 24
51 68
0
155
75
52
S1 68
0
155
75
52
185 01
0
555
273
51
18501
0
555
273
51
9
12
85 37
51 68
225
155
211
44
185 01
225
555
376
52
185 01
423
555
511
48
185 01
423
555
511
48
13
27
133 96
51 68
437
155
387
35
51 68
602
155
506
33
51 68
737
155
607
32
185 01
871
555
885
38
17
48
188 72
51 68
679
15S
607
27
51 68
798
155
701
26
51 68
1170
155
994
25
51 68
1549
155
1295
24
27
99
288.79
51 68
1261
155
1134
20
51 68
1341
155
1203
20
51 68
1669
155
1467
19
51 66
2176
155
1916
18
FILE
99SLVSPR TAB
99 acre Watershed. Silty Soil. Very Steep (18% Slope)
99 acre Watershed, Sitty Soil, Very Steep (18% Slope)
99 acre Watershed. Silty Soil, Very Steep (18% Slope)
99 acre Watershed, Silty Soil, Very Steep (18% Slope)
5
3
42 92
70 64
0
212
105
50
70 64
0
212
105
50
252 91
0
759
363
50
252 91
0
759
383
50
9
13
12
27
91 06
70 64
316
212
306
42
252 91
316
759
541
50
252 91
594
759
737
46
252 91
594
759
737
46
143 05
70 64
631
212
572
32
70 84
866
212
748
31
70 64
1062
212
898
30
252 91
1257
759
1301
35
17
48
201 74
70 64
997
212
903
25
70 64
1172
212
1045
25
70 64
1714
212
1482
23
70 64
2266
212
1930
22
27
99
309 25
70 64
1863
212
1693
18
70 64
1985
212
1800
18
70 64
2481
212
2232
17
7064
3236
212
2680
16
i
-------
AGNPS Results for the Impact Analysis of Pre-Construction to Varying Construction Conditions | |
I I I
I I
One - 3 acre Construction Stte
Five - 3 acre Construction Sites
Ten - 3 acre Construction Sites
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Drainage
Peak Rate
Cell
Entering
Generated
Sediment
Sediment
Cell
Entering
Generated
Sediment
Sediment
Celt
Entenng
Generated
Sediment
Sediment
Ceil
Entering
Generated
Sediment
Sediment
Cell
Area
of Runoff
Erosion
Ceil
Wrthm
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Number
(acres)
(cts)
mi
(tons)
(tons)
(tons)
(*)
(t/a)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
(V»)
(tons)
(tons)
(tons)
(%)
FILE
300SAFPR TAB
300 acre Watershed, Sandy Soil. Flat (3% Slope)
300 acre Watershed, Sandy Soil. Flat (3% Slope)
300 acre Watershed. Sandy Soil, Fiat (3% Slope)
300 acre Watershed, Sandy Soil, Flat (3% Slope)
31
27
54 64
1 57
3
5
3
60
1 57
3
5
3
60
1 57
3
5
3
60
1 57
3
5
3
60
61
75
99 55
1 57
7
5
7
41
1 57
8
5
8
40
1 57
9
5
9
39
1 57
9
5
9
39
85
147
153 02
1 57
14
5
14
29
1 57
14
5
14
29
1 57
15
5
14
28
1 57
17
5
16
27
92
282
254 42
1 57
26
5
24
21
1 57
26
5
24
21
1 57
28
5
26
20
1 57
31
5
29
20
100
300
246 28
1 57
25
5
25
17
1 57
26
5
25
17
1 57
27
5
27
17
1 57
30
5
29
16
FILE
300SARPR TAB
300 acre Watershed, Sandy Soil, Rolling (7% Slope)
300 acre Watershed, Sandy Soil, Rolling (7% Slope)
300 acre Watershed. Sandy Soil, Rolling (7% Slope)
300 acre Watershed, Sandy Soil, Rolling (7% Slope)
31
27
62 65
4 33
9
13
8
64
4 33
9
13
8
64
4 33
9
13
8
64
4 33
9
13
8
64
61
75
114 56
4 33
19
13
18
45
4 33
22
13
19
44
4 33
25
13
22
43
4 33
25
13
22
43
85
147
176 57
4 33
36
13
33
32
4 33
36
13
33
32
4 33
38
13
35
30
433
43
13
40
29
02
282
293 98
4 33
64
13
60
22
4 33
65
13
61
22
4 33
71
13
66
21
4 33
82
13
76
20
100
300
285 05
4 33
63
13
61
20
4 33
64
13
62
19
4 33
70
13
67
19
4 33
78
13
75
18
FILE
300SASPR TAB
300 acre Watershed, Sandy Soil. Steep (12% Slope)
300 acre Watershed Sandy Soil. Steep (12% Slope)
300 acre Watershed, Sandy Soil, Steep (12% Slope)
300 acre Watershed, Sandy Soil, Steep (12% Slope)
31
27
68 36
8 07
18
24
15
63
8 07
18
24
15
63
8 07
18
24
15
63
8 07
18
24
15
63
61
75
125 33
8 07
38
24
34
45
8 07
43
24
38
43
8 07
50
24
43
42
8 07
50
24
43
42
85
147
193 54
8 07
69
24
85
31
8 07
69
24
65
31
8 07
74
24
69
30
8 07
88
24
79
28
92
282
322 52
8 07
123
24
116
21
8 07
126
24
119
21
8 07
139
24
131
20
8 07
162
24
151
19
too
300
31308
8 07
123
24
118
19
8 07
125
24
121
19
8 07
136
24
131
18
8 07
155
24
148
17
FILE
300SAVPR TAB
300 acre Watershed. Sandy Soil, Very Steep (18% Slope)
300 acre Watershed, Sandy Soil. Very Steep (18% Slope)
300 acre Watershed. Sandy Soil. Very Steep (18% Slope)
300 acre Watershed. Sandy Soil. Very Steep
(18% Slop
«)
31
27
73 00
11 04
26
33
23
62
11 04
26
33
23
62
11 04
26
33
23
62
11 04
26
33
23
62
61
75
134 10
11 04
56
33
50
43
11 04
63
33
56
42
11 04
73
33
64
40
11 04
73
33
64
40
85
147
207 37
11 04
101
33
94
30
11 04
101
33
94
30
11 04
108
33
101
28
11 04
128
33
117
27
92
282
345 79
11 04
180
33
170
20
11 04
185
33
174
20
11 04
204
33
192
19
11 04
238
33
222
18
100
300
335 94
11 04
179
33
173
19
11 04
183
33
176
18
11 04
200
33
192
18
11 04
227
33
217
17
-------
AGNPS Results for the Impact Analysis of Pre-Construction to Varying Construction Conditions
l
i I l
I
One - 3 ac
re Construction Site
Five - 3 acre Construction Sites
Ten • 3 ac
¦e Construction Sites
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Drainage
Peak Rate
Cell
Entering
Generated
Sediment
Sediment
Cell
Entering
Generated
Sediment
Sediment
Cell
Entenno
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Cell
Area
of Runoff
Erosion
Cell
Within
Yield
Deposrtion
Erosion
Cell
Within
Yield
Oe position
Erosion
Cell
Within
Yield
Deposrtion
Erosion
Cell
Within
Yield
Deposition
Number
(acres)
(c*)
m
(tons)
(tons)
(tons)
(%)
m
(tons)
(tons)
(tons)
(%)
m
(tons)
(tons)
(tons)
(%)
m
(tons)
(tons)
(tons)
(%)
FILE
300CLFPR TAB
300 acre Watershed, Clayey Soil
Flat (3% Slope)
300 acre Watershed. Clayey Soil
Flat (3% Slope)
300 acre Watershed, Clayey Soil
Flat (3% Slope)
300 acre Watershed. Clayey Soil
Flat (3% Slope)
31
27
06 56
4 23
34
13
29
37
4 23
34
13
29
37
4 23
34
13
29
37
423
34
13
29
37
61
75
177 05
4 23
73
13
00
23
4 23
83
13
74
23
4 23
97
13
84
23
423
97
13
84
23
85
147
274 85
4 23
133
13
125
14
4 23
133
13
125
14
423
143
13
135
14
423
165
13
154
13
92
282
459 92
4 23
240
13
228
10
4 23
246
13
233
10
4 23
270
13
256
9
423
314
13
295
10
100
300
445 40
4 23
241
13
233
8
4 23
240
13
230
8
4 23
268
13
259
8
423
303
13
291
6
FILE
300CLRPR TAB
300 acre Watershed, Clayey Soil
Rolling (7% Slope)
300 acre Watershed, Clayey Sod
Rolling (7% Slope)
300 acre Watershed, Clayey Soil
Rolling (7% Slope)
300 acte Watershed. Clayey Soil
Rolling (7% Sloped
31
27
11072
11 70
106
35
93
34
11 70
100
35
93
34
11 70
106
35
93
34
11 70
106
35
93
34
01
75
204 44
11 70
231
35
210
21
11 70
263
35
235
21
11 70
307
35
269
21
11 70
307
35
269
21
85
147
317 15
11 70
419
35
395
13
11 70
419
35
395
13
11 70
452
35
426
13
11 70
525
35
491
12
92
282
531 41
11 70
756
35
720
9
11 70
774
35
738
9
11 70
857
35
815
9
11 70
998
35
942
9
100
300
515 59
11 70
757
35
731
e
11 70
774
35
747
8
11 70
846
35
816
7
11 70
964
35
924
7
FILE
300CLSPR TAB
300 acre Watershed, Clayey Soil
Steep (12% Slope)
300 acre Watershed. Clayey Soil
Steep (12% Slope)
300 acre Watershed, Clayey Soil
Steep (12% Slope)
300 acre Watershed, Clayey Soil
Steep (12% Slope)
31
27
120 81
21 80
213
65
190
32
21 80
213
65
190
32
21 80
213
65
190
32
21 80
213
65
190
32
61
75
223 00
21 80
474
65
433
20
21 80
539
65
486
20
21 80
625
65
554
20
21 80
625
65
554
20
85
147
347 63
21 80
861
65
815
12
21 80
861
65
815
12
21 80
931
65
880
12
2180
1084
65
1018
11
92
282
583 01
21.80
1557
65
1488
6
21 80
1597
65
1526
8
21 80
1772
85
1688
8
21 80
2060
65
1953
8
—
100
300
566 29
21 80
1561
65
1508
7
21 80
1590
65
1542
7
21 80
1750
65
1687
7
2180
1995
65
1916
7
FILE
300CLVPR TAB
300 acre Watershed, Clayey Soi
Very Steep (18% Slope)
300 acre Watershed, Clayey Sot
Very Stee
p (18% Slope)
300 acre Watershed, Clayey Soi
Very Stee
p (18% Slo
300 acre Watershed. Clayey Soil
Very Stee
p (18% Slope)
31
27
129 01
29 80
307
89
280
29
29 80
307
69
280
29
29 80
307
89
280
29
29 80
307
89
280
29
61
75
239 31
29 80
696
89
641
18
29 80
791
69
719
18
29 80
914
89
819
18
29 80
914
69
819
18
8S
147
372 47
29 80
1270
69
1207
29 80
1270
69
1207
11
29 80
1375
89
1305
11
29 80
1602
89
1511
11
92
282
625 08
29 80
2303
89
2207
8
29 80
2363
89
2264
8
29 80
2623
89
2508
8
29 80
3046
89
2898
8
100
300
607 651 29 80
2311
89
2236
7
29 80
2364
69
2287
7
29 80
2595
89
2505
7
29 80
2959
89
2846
7
-------
AGNPS Results for the Impact Analysts of Pre-Construction to Varying Construction Conditions j |
I
I
i i
One - 3 acre Construction Site
Five - 3 acre Constru
ction Sites
Ten - 3 acre Construction Sites
—
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Drainage
Peak Rate
Cell
Entering
Generated
Sediment
Sediment
Cell
Entering
Generated
Sediment
Sediment
Cell
Enfenng
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Cf II
Area
of Runoff
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Number
(acres)
(cfs)
m
(tons)
(tons)
(Ions)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
—
FILE
300SIFPR TAB
300 acre Watershed, Silty Soil, Flat (3% Slope)
300 acre Watershed. Silty Soil, Flat (3% Slope)
300 acre Watershed, Silty Sotl, Flat (3% Slope)
300 acre Watershed. Sifty Soil. Flat (3% Slope)
31
27
107 06
10 02
88
30
56
43
10 02
88
30
56
43
10 02
68
30
56
43
1002
68
30
56
43
01
75
197 32
10 02
141
30
124
27
10 02
160
30
138
27
10 02
109
30
159
27
10 02
189
30
159
27
65
147
305 65
1002
250
30
231
17
10 02
250
30
231
17
10 02
267
30
247
17
10 02
309
30
284
18
92
202
51205
10 02
444
30
417
12
10 02
454
30
427
12
10 02
501
30
469
12
10 02
585
30
544
12
100
300
496,01
10 02
441
30
421
10
10 02
449
30
430
10
10 02
489
30
466
10
10 02
556
30
527
10
FILE
300SLRPR TAB
300 acre Watershed. Sifty Sod, Rolling (7% Slope)
300 acre Watershed, SiltySoil. Rolling (7% Slope)
300 acre Watershed, Silty Soil. Rolling (7% Slope)
300 acre Watershed. Sifty Soil. Rolling (7% Slope)
31
27
122 76
27 74
217
03
186
36
27 74
217
83
186
38
27 74
217
83
166
38
27 74
217
83
186
38
61
75
227 00
27 74
462
83
412
24
27 74
525
83
462
24
27 74
615
83
530
24
27 74
615
83
530
24
85
147
352 69
27 74
823
83
768
15
27 74
823
03
768
15
27 74
884
83
824
15
27 74
1028
83
951
14
92
202
591 65
27 74
1471
03
1391
11
27 74
1507
83
1424
10
27 74
1668
83
1572
10
27 74
1947
83
1824
10
100
300
574 09
27 74
1460
83
1396
S
27 74
1491
83
1427
9
27 74
1628
63
1556
9
27 74
1659
63
1766
9
FILE
300SLSPR TAB
300 acre Watershed. Sifty Soil, Steep (12% Slope)
300 acre Watershed. Silty Soil. Steep (12% Slope)
300 acre Watershed, Silty Soil. Steep (12% Slope)
300 acre Watershed. Silty Soil, Steep (12% Slope)
31
27
133 96
51 68
437
155
387
35
51 68
437
155
387
35
51 68
437
155
3871
35
51 68
437
155
387
35
61
75
248 43
51 68
959
155
665
22
51 68
1090
155
972
22
51 68
1266
155
1111
22
51 68
1266
155
1111
22
85
147
386 50
51 68
1722
155
1619
14
51 68
1722
155
1819
14
51 68
1855
155
1741
13
51 68
2161
155
2014
13
62
282
640 09
51 68
3093
155
2940
8
51 66
3171
155
3013
9
51 66
3515
155
3331
9
51 60
4092
155
3858
9
100
300
630 54
51 68
3076
155
2955
9
51 68
3144
155
3019
8
51 68
3442
155
3299
8
51 68
3929
155
3750
8
FILE
300SLVPR TAB
300 acre Watershed. Sitty Soil. Very Steep (18% Slope)
300 acre Watershed, Silty Soil, Very Steep (18% Slope)
300 acre Watershed. Silty Soil, Very Sleep (18% Slope)
300 acre Watershed. Silty Soil. Very Steep (18% Slope)
31
27
143 05
70 64
631
212
572
32
70 64
631
212
572
32
70 64
631
212
572
32
70 64
631
212
572
32
61
75
265 82
70 64
1417
212
1293
21
70 64
1009
212
1451
20
70 64
1859
212
1654
20
70 64
1859
212
1654
20
65
147
414 21
70 64
2563
212
2423
13
70 64
2563
212
2423
13
70 64
2767
212
2611
12
70 84
3224
212
3022
12
92
282
695 92
70 64
4623
212
4412
9
70 64
4742
212
4523
9
70 64
5259
212
5005
9
70 64
6108
212
5787
8
100
300
676 59
70 64
4610
212
4441
8
70 64
4715
212
4540
8
70 64
5168
212
4967
8
70 64
5896
212
5646
8
-------
AGNPS Results for the Impact Analysis of Pre-Construc
tion to Varying Construction Conditions | j
i i
i l
One • 3 acre Construction Site
Five - 3 acre Construction Sites
Ten . 3 acre Construction Sttes
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Drainage
Peak Rate
Cell
Entering
Generated
Sediment
Sediment
Cell
Entering
Generated
Sediment
Sediment
Cell
Entering
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Coll
Area
of Runoff
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Number
(acres)
(cfs)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
FILE
639SAFPR TAB
639 acre Watershed, Sandy Soil. Flat (3% Slope)
639 acre Watershed. Sandy Soil, Flat (3% Slope)
639 acre Watershed, Sandy Soil, Flat (3% Slope)
639 acre Watershed, Sandy Soil, Flat (3% Slope)
31
27
54 64
1.57
3
5
3
60
1 57
3
5
3
60
1 57
3
5
3
60
1 57
3
5
3
60
02
147
153.02
1 57
14
5
14
29
1 57
15
5
14
29
1 57
15
5
14
29
1 57
17
5
16
27
106
282
254 42
1 57
26
5
24
21
1 57
26
5
24
21
1 57
27
5
25
21
1 57
30
5
28
20
175
534
359 60
1 57
44
5
42
14
1 57
44
5
42
14
1 57
45
5
43
14
1 57
47
5
44
14
213
639
343 69
1 57
45
5
44
10
1 57
45
5
45
10
1 57
47
5
46
10
1 57
46
5
48
10
FILE
639SARPR TAB
639 acre Watershed, Sandy Soil. Rolling (7% Slope)
639 acre Watershed, Sandy Soil, Rolling (7% Slope)
639 acre Watershed, Sandy Soil, Rolling (7% Slope)
639 acre Watershed, Sandy Soil, Rolling (7% Slope)
31
27
62 65
4 33
9
13
8
64
433
9
13
8
64
4 33
9
13
6
64
4 33
9
13
8
64
92
147
176 57
4 33
36
13
33
32
433
37
13
34
31
4 33
37
13
34
31
4 33
44
13
40
29
106
282
293 98
4 33
64
13
60
22
4 33
65
13
61
22
4 33
68
13
64
21
4 33
78
13
72
20
175
534
417 64
4 33
108
13
103
15
433
109
13
104
14
433
111
13
107
14
4 33
117
13
112
14
213
639
400 85
4 33
110
13
108
12
433
111
13
109
12
433
116
13
114
12
4 33
121
13
118
11
PILE
639SASPR TAB
639 acre Watershed. Sandy Soil, Steep (12% Slop#)
639 acre Watershed. Sandy Sod, Steep (12% Slope)
639 acre Watershed, Sandy Soil. Steep (12% Slope)
639 acre Watershed. Sandy Soil. Steep (12% Slope)
31
27
66 36
8 07
18
24
15
63
8 07
18
24
15
63
8 07
18
24
15
63
8 07
18
24
15
63
92
147
193 54
8 07
69
24
65
31
8 07
72
24
67
30
8 07
72
24
87
30
8 07
86
24
79
28
106
282
322 52
6 07
123
24
116
21
8 07
126
24
119
21
8 07
133
24
125
20
8 07
153
24
143
19
175
534
459 58
8 07
209
24
200
14
8 07
211
24
202
14
8 07
215
24
207
14
8 07
228
24
219
13
213
639
442 41
8 07
209
24
205
12
8 07
211
24
206
12
8 07
222
24
217
12
6 07
232
24
227
12
FILE
639SAVPR TAB
639 acre Watershed, Sandy Soil. Very Steep (18% Slope)
639 acre Watershed. Sandy Soil. Very Steep (18% Slope)
639 acre Watershed, Sandy Soil, Very Steep (18% Slope)
639 acre Watershed, Sandy Soil. Very Steep (18% Slope)
31
27
73 00
11 04
26
33
23
62
11 04
26
33
23
62
11 04
26
33
23
62
11 04
26
33
23
62
92
147
207 37
11 04
101
33
94
30
11 04
105
33
98
29
11 04
105
33
98
29
11 04
126
33
116
27
100
282
345 79
11 04
180
33
170
20
11 04
184
33
174
20
11 04
195
33
184
19
11 04
225
33
211
18
175
534
493 80
11 04
304
33
293
13
11 04
307
33
295
13
11 04
314
33
302
13
11 04
333
33
321
13
—
213
639
476 32
11 04
302
33
295
12
11 04
305
33
298
12
11 04
322
33
314
12
11 04
336
33
328
11
-------
AGNPS Results for the Impact A
latysis of Pre-Construction to Varying Construction Conditions I I
I I I
I I
One • 3 acre Construction Site
Five - 3 acre Construction Sites
Ten - 3 acre Construction Sites
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Drainage
Peak Rate
Cell
Entenng
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Cell
Entering
Generated
Sediment
Sediment
Cell
Entenng
Generated
Sediment
Sediment
Cfllf
Area
of Runoff
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Wifhtn
Yield
Deposjfron
Erosion
Cell
Within
Yield
Depositor!
Erosion
Cell
Within
Yield
Oeoos/tJon
Number
(acres)
(cfs)
(fa)
(tons)
(tons)
(tons)
(%)
(W®>
(tons)
(tons)
(tons)
(%)
m
(tons)
(tons)
(tons)
(%)
(tons)
(tons)
(tons)
(%>
FILE
639CLFPR TAB
639 acre Watershed, Clayey Soil
Flat (3% Slope)
639 acre Watershed. Clayey Soil
Flat (3% Slope)
639 acre Watershed. Clayey Soil
Flat (3% Slope)
639 acre Watershed, Clayey Soil
Flat (3% Slope)
31
27
96 56
4 23
34
13
29
37
4 23
34
13
29
37
4 23
34
13
29
37
4 23
34
13
29
37
92
147
274 85
4 23
133
13
125
14
4 23
138
13
130
14
4 23
138
13
130
14
4 23
165
13
153
14
106
282
459 62
4 23
240
13
228
10
4 23
245
13
233
10
4 23
259
13
246
10
423
298
13
280
10
175
534
654 52
4 23
413
13
399
6
4 23
417
13
403
6
4 23
427
13
413
6
4 23
453
13
437
6
213
639
626 34
4 23
424
13
416
5
4 23
428
13
420
5
4 23
451
13
442
5
4 23
471
13
462
4
FILE
639CIRPR TAB
639 acre Watershed, Clayey Soil
Rollino (7% Slope)
639 acre Watershed, Clayey Soil
Rolling (7% Slope)
639 acre Watershed, Clayey Soil
Rolling (7% Slope)
636 acre Watershed. Clayey Soil
Rolling (7% Slope)
31
27
110 72
11 70
106
35
93
34
11 70
106
35
93
34
11 70
106
35
93
34
11 70
106
35
93
34
62
147
317 15
11 70
419
35
395
13
11 70
436
35
411
13
11 70
436
35
411
13
11 70
525
35
488
13
106
282
531 41
11 70
756
35
720
9
11 70
772
35
735
9
11 70
619
35
779
9
11 70
948
35
897
9
175
534
759 74
11 70
1291
35
1249
6
11 70
1304
35
1262
6
11 70
1336
35
1293
6
11 70
1421
35
1375
6
213
639
730 49
11 70
1306
35
1279
5
11 70
1318
35
1290
5
11 70
1394
35
1363
5
11 70
1459
35
1427
5
FILE
639CLSPR TAB
639 acre Watershed. Clayey Soil
Steep (12% Slope)
639 acre Watershed, Clayey Soil
Steep (12% Slope)
639 acre Watershed, Clayey Soil
Steep (12% Slope)
639 acre Watershed. Clayey Soil
Steep (12% Slope)
31
27
120 81
21 80
213
65
190
32
21 80
213
65
190
32
21 80
213
05
190
32
21 80
213
65
190
32
02
147
347 03
21 80
861
65
815
12
21 80
897
65
849
12
21 80
897
65
849
12
21 80
1081
65
1011
12
106
282
583 01
21 80
1557
65
1488
8
21 80
1591
65
1520
8
21 80
1691
65
1013
8
21 80
1961
65
1861
8
175
534
836 02
21 80
2656
65
2575
5
21 80
2683
65
2601
5
21 80
2752
05
2667
S
21 60
2934
65
2841
5
213
639
806 23
21 80
2674
65
2615
5
21 80
2697
65
2638
5
21 80
2856
65
2790
5
21 80
2992
65
2922
4
FILE
639CLVPR TAB
639 acre Watershed. Clayey Soil
Very Stee
3 (18% Slope)
639 acre Watershed. Clayey Soil
Very Stee
p (18% Slope)
639 acre Watershed, Clayey Soil
Very Stee
p (18% Slope)
639 acre Watershed. Clayey Soil
Very Stee
3 (18% Slope)
31
27
129 01
29 80
307
69
260
29
29 80
307
89
280
29
29 80
307
89
280
29
29 80
307
69
280
29
62
147
372 47
29 80
1270
89
1207
11
29 80
1325
89
1258
11
29 80
1325
69
1258
11
29 80
1593
69
1498
11
106
282
625 00
29 80
2303
69
2207
6
29 80
2353
89
2256
8
29 80
2502
89
2394
8
29 80
2902
89
2764
8
175
534
898 27
29 80
3932
69
3817
5
29 80
3972
89
3856
5
29 80
4076
89
3956
5
29 80
4351
69
4220
5
213
639
860 03
29 80
3955
89
3668
4
29 80
3989
89
3901
4
29 80
4226
89
4127
4
29 80
4430
89
4326
4
-------
AGNPS Results for (he Impact Analysis of Pre-Constnjction to Vary
ing Construction Condition
I I
i i i
I I
One - 3 ac
re Construction Site
Five - 3 acre Construction Site*
Ten - 3 acre Construction Site*
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Sediment
Drainage
Peak Rate
Cell
Entenng
Generated
Sediment
Sediment
Cell
Enlenng
Generated
Sediment
Sediment
Cell
Entenna
Generated
Sediment
Sediment
Cell
Entering
Generated
Sediment
Sediment
Coll
Area
of Runoff
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Erosion
Cell
Within
Yield
Deposition
Number
(acres)
(cf*>
(t/a)
(tons)
(tons)
(tons)
(%>
ft/a)
(tons)
(tons)
(tons)
(%)
(t/a)
(tons)
(tons) I (tons)
(%)
(t/a)
(tons)
(tons)
(tons)
(%)
I
—
FILE
639SIFPR TAB
639 acre Watershed, Silty Soil. Flat (3% Slope)
639 acre Watershed, Silty Soil, Flat (3% Sloe
e)
639 acre Watershed, Silty Soil, Flat (3% Slof
»)
639 acre Watershed, Silty Soil. Flat (3% Slo
3e)
31
27
107 06
10 02
68
30
56
43
10 02
68
30
56
43
10 02
68
30
56
43
10 02
68
30
56
43
92
147
306 as
10 02
250
30
231
17
10 02
259
30
240
17
10 02
259
30
240
17
10 02
312
30
285
17
106
282
512 05
10 02
444
30
417
12
10 02
453
30
425
12
10 02
480
30
450
12
1002
555
30
517
12
175
534
729 54
10 02
745
30
714
8
10 02
752
30
720
8
10 02
769
30
737
8
10 02
814
30
780
8
213
639
698 35
10 02
728
30
709
7
10 02
734
30
714
7
10 02
778
30
754
6
10 02
809
30
788
8
FILE
639SLRPR TAB
639 acre Watershed. Sitty Soil. Rolling (7% Slope)
639 acre Watershed, Silty Sod, Rolling (7% Slope)
639 acre Watershed, Silty Soil, Rolling (7% Slope)
639 acre Watershed. Silty Sort. Rolling (7% Slope)
31
27
122 76
27 74
217
63
186
38
27 74
217
83
186
38
27 74
217
83
186
38
27 74
217
83
186
38
62
147
352 69
27 74
823
83
788
15
27 74
855
83
798
15
27 74
855
83
798
15
27 74
1034
83
952
15
106
282
591 65
27 74
1471
83
1391
11
27 74
1501
83
1419
10
27 74
1595
83
1505
10
27 74
1853
83
1738
10
175
534
846 82
27 74
2463
83
2369
7
27 74
2486
83
2390
7
27 74
2546
83
2448
7
27 74
2707
83
2601
7
213
639
814 48
27 74
2392
83
2324
6
27.74
2410
83
2342
6
27 74
2555
83
2479
e
27 74
2668
83
2588
6
FILE
639SLSPR TAB
639 acre Watershed. Silty Soil. Steep (12% Slope)
639 acre Watershed. Silty Soil, Steep (12% Slope)
639 acre Watershed. Sitty Soil, Steep (12% Sfope)
639 acre Watershed. Silty Soil, Steep (12% Slope)
31
27
133 96
51 68
437
155
387
35
51 68
437
155
387
35
51 68
437
155
387
35
51 68
437
1551
387
35
92
147
386 58
51 68
1722
155
1619
14
51 68
1792
155
1683
14
51 68
1792
155
1683
14
51 68
2162
155
2009
13
106
282
649 09
51 68
3093
155
2940
9
51 68
3157
155
• 3000
9
51 68
3358
155
3184
9
51 68
3900
155
3681
9
175
534
931 84
51 68
5194
155
5011
6
51 68
5242
155
5057
6
51 68
5375
155
5184
6
51 68
5726
155
5519
6
213
639
B98 93
51 68
5058
155
4917
6
51 68
5097
155
4955
6
51 68
5405
155
5248
6
51 88
5651
155
5486
6
FILE
639SLVPR TAB
639 acre Watershed. Sitty Soil. Very Steep (16% Slope)
839 acre Watershed. Silty Soil, Very Sleep (18% Slope)
639 acre Watershed. Sitty Soil, Very Steep (18% Slope)
639 acre Watershed. Silty Soil. Very Steep (18% Slope)
31
27
143 05
70 64
631
212
572
32
70 64
631
212
572
32
70 64
631
212
572
32
70 64
631
212
572
32
92
147
414 21
70 64
2563
212
2423
13
70 64
2670
212
2522
12
70 64
2670
212
2522
12
70 64
3214
212
3006
12
106
282
695 92
70 64
4623
212
4412
9
70 64
4721
212
4505
9
70 64
5021
212
4782
9
70 64
5828
212
5527
8
175
534
1001 23
70 64
7794
212
7538
6
70 64
7869
212
7610
6
70 64
8072
212
7805
6
70 64
8612
212
8321
6
—
213
639
967 84
70 64
7630
212
7425
5
70 64
7689
212
7482
5
70 64
8154
212
7924
5
70 64
8533
212
8291
5
-------
APPENDIX 2B
AGNPSRESULTS
Comparison of Sediment Yield Increases
-------
AGNPS Results for the Impact Analysis of Pre-Construction to Varying Construction Conditions
Comparison of Pre-Construction
Comparison of Pre-Construction
Yields to Construction Yields for
Yields to Construction Yields for
Drainage
Varying K
umber of Constr.Sites
Varying Number of Constr.Sites
Cell
Area
1 Site
5 Sites
10 Sites
1 Site
5 Sites
10 Sites
Number
(acres)
(tons)
(tons)
(tons)
(%Diff)
(%Diff)
(%Diff)
99 acre Watershed, Sandy Soil, Flat (3% Slope)
5
3
0
1.51
1.51
0.0
260.3
260.3
9
12
1.05
1.89
1.89
76.6
138.0
138.0
13
27
0.64
1.22
2.95
21.0
40.0
96.7
17
48
0.49
2.13
3.84
9.9
43.1
77.7
27
99
0.39
2
4.35
4.2
21.4
46.5
99 acre Watershed, Sandy Soil, Rolling (7% Slope;
5
3
0
4.53
4.53
0.0
264.9
264.9
9
12
3.34
6.06
6.06
80.9
146.7
146.7
13
27
2.13
4.02
9.59
27.3
51.5
122.9
17
48
1.61
6.98
12.62
13.1
56.9
102.9
27
99
1.21
6.32
14.04
5.2
27.3
60.7
99 acre Watershed, Sandy Soil, Steep (12% Slope
5
3
0
8.83
8.83
0.0
265.2
265.2
9
12
6.72
12.32
12.32
80.2
147.0
147.0
13
27
4.5
8.47
19.89
29.3
55.2
129.6
17
48
3.43
14.75
26.63
14.3
61.6
111.1
27
99
2.54
13.29
29.7
5.6
29.5
66.0
99 acre Watershed, Sandy Soil, Very Steep (18% Slope)
5
3
0
12.43
12.43
0.0
263.3
263.3
9
12
9.69
17.89
17.89
79.0
145.8
145.8
13
27
6.73
12.69
29.4
29.9
56.4
130.7
17
48
5.21
22.17
40
14.8
63.1
113.9
27
99
3.85
20.1
44.95
5.8
30.5
68.3
-------
AGNPS Results for the Imf
)act Analysis of Pre-Construction to Varying Construction Conditions
Comparison of Pre-Construction
Comparison of Pre-Construction
Yields to Construction Yields for
Yields to Construction Yields for
Drainage
Varying N
umber of Constr.Sites
Varying Number of Constr.Sites
Cell
Area
1 Site
5 Sites
10 Sites
1 Site
5 Sites
10 Sites
Number
(acres)
(tons)
(tons)
(tons)
(%Diff)
(%Diff)
(%Diff)
99 acre Watershed, C
ayey Soil, Flat (3% Slope)
5
3
0
17.08
17.08
0.0
269.8
269.8
9
12
13.2
23.54
23.54
81.9
146.1
146.1
13
27
8.59
15.85
37.19
29.5
54.5
127.8
17
48
6.6
28.02
49.8
14.4
61.0
108.5
27
99
5.07
26.14
57.01
5.8
30.0
65.4
99 acre Watershed, Clayey Soil, Rolling (7% Slope).
5
3
0
50.62
50.62
0.0
269.3
269.3
9
12
40.84
73.98
73.98
80.2
145.2
145.2
13
27
28.52
52.81
121.03
30.8
57.0
130.7
17
48
22.39
93.42
166.09
15.4
64.1
113.9
27
99
16.93
86.84
190.57
6.1
31.5
69.2
99 acre Watershed, C
ayey Soil, Steep (12% Slope)
5
3
0
97.85
97.85
0.0
268.4
268.4
9
12
80.94
148.07
148.07
78.7
144.0
144.0
13
27
59.05
109.83
247.88
31.0
57.7
130.2
17
48
47.32
195.33
347.07
15.7
64.9
115.3
27
99
35.99
183.55
402.38
6.3
32.3
70.8
99 acre Watershed, Clayey Soil, Very Steep (18% Slope)
5
3
0
137.12
137.12
0.0
267.7
267.7
9
12
115.39
212.64
212.64
77.5
142.9
142.9
13
27
86.81
162.13
361.87
31.0
58.0
129.4
17
48
70.74
289.96
514.84
15.9
65.2
115.8
27
99
54.39
276.06
603.45
6.5
32.8
71.8
-------
AGNPS Results for the Impact Analysis of Pre-Construction to Varying Construction Conditions
Comparison of Pre-Construction
Comparison of Pre-Construction
Yields to Construction Yields for
Yields to Construction Yields for
Drainage
Varying N
umber of Constr.Sites
Varying Number of Constr.Sites
Cell
Area
1 Site
5 Sites
10 Sites
1 Site
5 Sites
10 Sites
Number
(acres)
(tons)
(tons)
(tons)
(%Diff)
(%Diff)
(%Diff)
99 acre Watershed, S
Ity Soil, Flat (3% Slope)
5
3
0
34.55
34.55
0.0
265.8
265.8
9
12
26.75
47.25
47.25
82.1
145.0
145.0
13
27
16.98
30.86
73.27
30.1
54.7
129.8
17
48
12.58
53.48
95.01
14.4
61.4
109.1
27
99
9
46.61
103.95
5.5
28.7
64.0
99 acre Watershed, Silty Soil, Rolling i
7% Slope)
5
3
0
102.49
102.49
0.0
264.9
264.9
9
12
82.93
149.3
149.3
79.5
143.1
143.1
13
27
57.23
104.91
241.81
30.7
56.3
129.8
17
48
44.04
183.31
325.59
15.2
63.4
112.5
27
99
31.81
163.07
363.12
5.9
30.2
67.4
99 acre Watershed, S
ty Soil, Steep (12% Slope)
5
3
0
198.2
198.2
0.0
264.2
264.2
9
12
164.5
299.49
299.49
77.8
141.6
141.6
13
27
119.2
219.97
498.05
30.8
56.8
128.6
17
48
94.28
387.76
688.21
15.5
63.9
113.5
27
99
69.43
353.19
782.16
6.1
31.2
69.0
99 acre Watershed, Silty Soil, Very Steep (18% Slope)
5
3
0
277.78
277.78
0.0
263.6
263.6
9
12
234.59
430.56
430.56
76.6
140.5
140.5
13
27
175.78
326.14
729.28
30.7
57.0
127.5
17
48
141.93
579.35
1027.4
15.7
64.2
113.8
27
99
106.5
538.75
1186.38
6.3
31.8
70.1
-------
AGNPS Results for the Im
jact Analysis of Pre-Construction to Varying Construction Conditions
Comparison of Pre-Construction
Comparison of Pre-Construction
Yields to Construction Yields for
Yields to Construction Yields for
Drainage
Varying N
umber of Constr.Sites
Varying N
umber of Constr.Sites
Cell
Area
1 Site
5 Sites
10 Sites
1 Site
5 Sites
10 Sites
Number
(acres)
(tons)
(tons)
(tons)
(%Diff)
(%Diff)
(%Diff)
300 acre Watershed, Sandy Soil, Flat (3% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
0.54
1.31
1.31
7.5
18.2
18.2
85
147
0
0.73
2.15
0.0
5.4
15.9
92
282
0.39
2.08
5.02
1.6
8.7
20.9
100
300
0.35
1.87
4.28
1.4
7.6
17.3
300 acre Watershed, Sand
y Soil, Rolling (7% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
1.81
4.37
4.37
10.3
24.8
24.8
85
147
0
2.24
6.93
0.0
6.7
20.9
92
282
1.22
6.72
16.42
2.0
11.3
27.5
100
300
1.11
5.96
13.93
1.8
9.7
22.7
300 acre Watershed, Sand
y Soil, Steep (12% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
3.85
9.18
9.18
11.2
26.8
26.8
85
147
0
4.68
14.68
0.0
7.3
22.8
92
282
2.59
14.25
34.6
2.2
12.2
29.7
100
300
2.33
12.56
29.46
2.0
10.6
24.9
300 acre Watershed, Sand
y Soil, Very Steep (18% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
6
14
14
11.6
27.4
27.4
85
147
0
7
22
0.0
7.5
23.6
92
282
4
22
52
2.3
12.7
30.5
100
300
4
19
45
2.0
11.0
25.8
-------
AGNPS Results for the Im
>act Analysis of Pre-Construction to Varying Construction Conditions
Comparison of Pre-Construction
Comparison of Pre-Construction
Yields to Construction Yields for
Yields to Construction Yields for
Drainage
Varying Number of Constr.Sites
Varying Number of Constr.Sites
Cell
Area
1 Site
5 Sites
10 Sites
1 Site
5 Sites
10 Sites
Number
(acres)
(tons)
(tons)
(tons)
(%Diff)
(%Diff)
(%Diff)
300 acre Watershed, Clayey Soil, Flat
2% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
7.42
17.76
17.76
11.2
26.7
26.7
85
147
0
9.37
28.59
0.0
7.5
22.8
92
282
5.2
28.26
66.93
2.3
12.4
29.3
100
300
4.77
25.38
57.81
2.0
10.9
24.8
300 acre Watershed, Clayey Soil, Rolling (7% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
25.11
58.75
58.75
12.0
28.0
28.0
85
147
0
30.72
95.73
0.0
7.8
24.2
92
282
17.5
94.61
222.07
2.4
13.1
30.8
100
300
15.85
84.41
193.08
2.2
11.5
26.4
300 acre Watershed, Clayey Soil, Steep (12% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
52.75
121.39
121.39
12.2
28.0
28.0
85
147
0
64.91
202.33
0.0
8.0
24.8
92
282
37.34
200.07
464.39
2.5
13.4
31.2
100
300
33.71
178.78
407.31
2.2
11.9
27.0
300 acre Watershed, Clayey Soil, Very Steep (18% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
78.43
178.2
178.2
12.2
27.8
27.8
85
147
0
97.95
303.6
0.0
8.1
25.1
92
282
56.51
300.39
690.36
2.6
13.6
31.3
100
300
51.06
269.42
610.43
2.3
12.0
27.3
-------
AGNPS Results for the Impact Analysis of Pre-Construction to Varying Construction Conditions
Comparison of Pre-Construction
Comparison of Pre-Construction
Yields to Construction Yields for
Yields to Construction Yields for
Drainage
Varying N
umber of Constr.Sites
Varying Number of Constr.Sites
Cell
Area
1 Site
5 Sites
10 Sites
1 Site
5 Sites
10 Sites
Number
(acres)
(tons)
(tons)
(tons)
(%Diff)
(%Diff)
(%Diff)
300 acre Watershed, Silty Soil, Flat (3% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
14
35
35
11.7
28.4
28.4
85
147
0
16
52
0.0
6.9
22.6
92
282
9
52
126
2.2
12.4
30.3
100
300
8
45
106
2.0
10.7
25.2
300 acre Watershed, Silty Soil, Rolling (7% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
50
118
118
12.2
28.7
28.7
85
147
0
56
183
0.0
7.3
23.8
92
282
33
181
433
2.4
13.0
31.1
100
300
29
158
370
2.1
11.3
26.4
300 acre Watershed, Silty Soil, Steep
12% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
106
246
246
12.3
28.4
28.4
85
147
0
122
395
0.0
7.5
24.4
92
282
73
391
918
2.5
13.3
31.2
100
300
64
344
795
2.2
11.6
26.9
300 acre Watershed, Silty Soil, Very Steep (18% Slope)
31
27
0
0
0
0.0
0.0
0.0
61
75
159
362
362
12.3
28.0
28.0
85
147
0
188
599
0.0
7.8
24.7
92
282
111
593
1375
2.5
13.4
31.2
100
300
99
526
1205
2.2
11.8
27.1
-------
AGNPS Results for the Im
jact Analysis of Pre-Construction to Varying Construction Conditions
Comparison of Pre-Construction
Comparison of Pre-Construction
Yields to Construction Yields for
Yields to Construction Yields for
Drainage
Varying N
umber of Constr.Sites
Varying Number of Constr.Sites
Cell
Area
1 Site
5 Sites
10 Sites
1 Site
5 Sites
10 Sites
Number
(acres)
(tons)
(tons)
(tons)
(%Diff)
(%Diff)
(%Diff)
639 acre Watershed, Sand
y Soil, Flat i
3% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
0
0
2
2.7
2.7
15.3
106
282
0
1
4
1.5
5.3
15.9
175
534
0
1
3
0.7
2.4
6.7
213
639
0
2
3
0.6
4.2
7.6
639 acre Watershed, Sand
y Soil, Rolling (7% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
1
1
7
3.4
3.4
20.7
106
282
1
4
13
1.8
7.0
21.2
175
534
1
3
9
0.9
3.0
8.5
213
639
1
6
11
0.8
5.6
9.8
639 acre Watershed, Sand
y Soil, Steep (12% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
2
2
15
3.7
3.7
22.5
106
282
2
9
27
1.9
7.6
23.1
175
534
2
6
18
0.9
3.2
9.2
213
639
2
13
22
0.8
6.1
10.7
639 acre Watershed, Sandy Soil, Very Steep (18% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
4
4
22
3.8
3.8
23.2
106
282
3
13
41
2.0
7.8
23.9
175
534
3
10
28
0.9
3.3
9.6
. 213
639
2
19
33
0.8
6.4
11.0
-------
AGNPS Results for the Im
)act Analysis of Pre-Construction to Varying Construction Conditions
Comparison of Pre-Construction
Comparison of Pre-Construction
Yields to Construction Yields for
Yields to Construction Yields for
Drainage
Varying Number of Constr.Sites
Varying Number of Constr.Sites
Cell
Area
1 Site
5 Sites
10 Sites
1 Site
5 Sites
10 Sites
Number
(acres)
(tons)
(tons)
(tons)
(%Diff)
(%Diff)
(%Diff)
639 acre Watershed, Clayey Soil, Flat (3% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
5
5
28
3.8
3.8
22.4
106
282
5
18
52
2.0
7.7
23.0
175
534
4
13
38
1.0
3.4
9.5
213
639
4
26
46
0.9
6.2
11.0
639 acre Watershed, Clayey Soil, Rolling (7% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
16
16
94
4.0
4.0
23.7
106
282
15
59
177
2.1
8.2
24.5
175
534
13
44
126
1.0
3.5
10.1
213
639
11
84
148
0.9
6.5
11.5
639 acre Watershed. Clayey Soil, Steep (12% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
34
34
196
4.1
4.1
24.0
106
282
32
124
373
2.1
8.4
25.0
175
534
26
92
267
1.0
3.6
10.4
213
639
23
175
307
0.9
6.7
11.7
639 acre Watershed, Clayey Soil, Very Steep (18% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
51
51
291
4.2
4.2
24.1
106
282
48
187
557
2.2
8.5
25.2
175
534
39
139
403
1.0
3.7
10.6
213
639
33
260
459
0.9
6.7
11.9
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AGNPS Results for the Impact Analysis of Pre-Construction to Vary
ng Construction Conditions
Comparison of Pre-Construction
Comparison of Pre-Construction
Yields to Construction Yields for
Yields to Construction Yields for
Drainage
Varying N
umber of Constr.Sites
Varying Number of Constr.Sites
Cell
Area
1 Site
5 Sites
10 Sites
1 Site
5 Sites
10 Sites
Number
(acres)
(tons)
(tons)
(tons)
(%Diff)
(%Diff)
(%Diff)
639 acre Watershed, Silty Soil, Flat (3% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
8
8
54
3.6
3.6
23.2
106
282
8
32
99
1.9
7.8
23.8
175
534
6
23
66
0.9
3.2
9.2
213
639
5
45
77
0.8
6.3
10.9
639 acre Watershed, Silty Soil, Rolling (7% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
29
29
184
3.8
3.8
24.0
106
282
28
113
347
2.0
8.2
24.9
175
534
22
79
232
0.9
3.3
9.8
213
639
18
154
264
0.8
6.6
11.4
639 acre Watershed, Silty Soil, Steep
12% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
64
64
390
4.0
4.0
24.1
106
282
60
244
741
2.1
8.3
25.2
175
534
47
173
508
0.9
3.5
10.1
213
639
38
330
568
0.8
6.7
11.6
639 acre Watershed, Silty Soil, Very Steep (18% Slope)
31
27
0
0
0
0.0
0.0
0.0
92
147
99
99
583
4.1
4.1
24.1
106
282
93
370
1115
2.1
8.4
25.3
175
534
72
267
783
1.0
3.5
10.4
213
639
57
500
867
0.8
6.7
11.7
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