SWM-SY 930201Section 1
Introduction
The purpose of this manual is to provide technical guidance to municipalities,
property owners, engineers, contractors and other construction industries in the
North Central Texas area for compliance with the requirements of the NPDES
General Permit for lf-tdttstrial Storm Water Discharges From Construction
Activities ets they relate to eortstruetion in Region 6. This manual focuses on the
effects of the NPDES requirements on construction activities in the North
Central Texas area along with methods to reduce the pollution potential of
construction sites in the area. The following establishes the framework and
provides the tools to produce an effective Storm Water Pollution Prevention Plan
(SWPPP) in accordance with EPA guidelines as well as locally established
guidelines in storm water pollution control.
The processes of soil erosion and deposition are natural, ongoing geological
mechanisms in which the surface of the earth is changed through the creation,
transportation (via wind and water) and settlement of soil particles. As a natural
process, erosion provides for stream formation and shaping. However, human
activities accelerate this erosion process producing more sediment than
waterways can bear. At this point, sediment ceases to be a natural constituent
and becomes a pollutant. Construction activities are a major source of this type
of pollution.
As land is developed and urbanization occurs, two mechanisms occur that
increase erosion and thereby increase sediment in waterways. First,
urbanization results in a significant increase in impervious area, preventing
precipitation from infiltrating into the soil. This produces significant increases in
the volume of runoff from a given area and increases flows, often resulting in
higher water velocities in streams and drainage channels. Higher runoff
velocities increase the potential for soils to be eroded. Secondly, development
activities almost always necessitate the removal of natural ground cover.
Vegetation acts to hold topsoil in place during precipitation events and its
removal leaves soil unprotected against wash off during storms. For these
reasons, erosion (and the associated deposit of sediment in waterways) is
increased drastically as land is developed, reducing storm drainage system and
watercourse capacity. This increase in erosion and sediment can cause flooding
and, as importantly, significant degradadetti degradation of the water quality
of streams, lakes and. rivers.
Besides contributing to soil erosion and sedimentation, construction activities
related to the process; of urbanization (land development, renovation,
demolition, etc.) can introduce hazardous chemicals into the environment
through contamination of storm water runoff. Pollutants from construction sites
can enter waterways through incorrect usage of chemicals, improper disposal or
NCTCOG Construction BMP Manual 1 -1 February 1993
Section 1
Introduction
storage of chemicals, and inadequate containment of chemical spills. Because
chemicals can bind to sediment particles, the combination of chemicals and
sediment in runoff can be particularly harsh on the quality of surface waters,
harming wildlife and vegetation, which affects the quality of life of the citizens
of the North Central Texas region.
Pollution, as it relates to storm water, consists of a wide variety of constituents
including suspended solids, bacteria, heavy metals, oxygen - demanding
substances, nutrients, and oil and grease. The sources of the majority of these
pollutants result from human activities such as agriculture, motorized vehicle
use, construction activities, and industrial activities. In addition, construction
site waste such as building materials, packaging, sandblasting grit and paints are
subject to transport off of the construction site through neglect, wind, or rain.
Storm water runoff is increasingly becoming the focus of surface water pollution
throughout the U.S. In a recent study prepared by the Association of State and
Interstate Water Pollution Control Administrators and the EPA, 38 states
reported urban runoff as a major cause of beneficial use impairment for surface
waters. In addition, 21 states reported construction site runoff as a major cause of
use impairment.' In another study by the EPA it was found that 87 percent of
the 246 major water basins in the country are affected by nonpoint source
pollution , which results from runoff from both urban and rural land uses.
As part of the Water Quality Act of 1987, storm water runoff from certain
industrial activities are now considered point source discharges to waters of the
United States and, unless authorized by a National Pollutant Discharge
Elimination System ( NPDES) permit, are unlawful. Construction activities which
disturb an area greater than 5 acres by grading, clearing, grubbing or other
construction activity are classified as an industrial activity, subject to the
requirement of an NPDES permit. In order to effectively manage the permit process,
the EPA has produced a general permit for construction activities which defines
specific conditions and requirements to be met as part of the permit. The General
Permit establishes the procedures required for proper coverage, the requirement of
an SWPPP and requirements for termination of permit coverage. A copy of the
permit is included in Section 5, NPDES Requirements.
As oi Oetober 1, 1992 In accordance with the Construction General Permit, all
applicable construction sites will be are required to submit a Notice of Intent (NOI)
to the EPA and, in many cases, the local jurisdiction. This inekt d.
Failure to
properly submit the required information may result in federal prosecution through
the Water Quality Act of 1987 along with possible actions by the city with regards to
IFederal Register Rules and Regulations, Volume 57, No. 64, Thursday
April 2, 1992, p. 11395.
2Council on Environmental Quality, "Environmental Quality - 1979: The
Tenth Annual Report of the Council on Environmental Quality," U.S.
Government Printing Ogee, Washington, D. C., 1980.
NCTCOG Construction BMP Manual 1 -2 February 1993
Section 1
Introduction
enforcement of local ordinances.
This manual provides guidance in meeting
the construction phase requirements of the NPDES
regulations. It is one of a three volume set available from the North Central Texas
Council of Governments which addresses storm water quality and techniques to
reduce pollution associated with storm water runoff.
Definitions
The following terms are used throughout the manual.
BMP Best Management Practices.. kBMPs) consist of means
schedules of activities, prohibitions of practices,
maintenance procedures, and other management practices
to prevent or reduce the politttion of discharge of
pollutants to waters of the United States. Otis BMPs also
includes treatment requirements, operating procedures,
and practices to control construction 1p ant site runoff,
spillage or leaks, sludge or waste disposal, or drainage
from raw material storage!
Design storm The rainfall intensity which is used for the adequate
design of erosion and sediment control systems. For most
projects, this will be the 2 -year, 24 -hour design storm. The
local jurisdiction has the option to require a higher
intensity for projects which that may be particularly
sensitive or impact sensitive areas.
As used throughout the manual, the 2 year, 24 hour design
storm refers to a storm intensity with a 2 year intensity
and a duration of 24 hours. Intensity is used to compute a
peak flow while duration allows for the computation of
volumes for sediment basins and similar structures. The 24
hour criteria should not be confused with the time of
concentration for computing flows based on the rational
method. Volumetric calculations use hydrograph data, not
the rational method.
Erosion The wearing away of the land surface by running water,
wind, ice, or other geological agents, including such
processes as gravitational creep. In this manual, erosion
3NPDES General Permits For Storm Water Discharges From Construction
Activities That Are Oaiiified Ai
• , „ in
Region 6, page 2-5836508.
NCTCOG Construction BMP Manual 1 -3 February 1993
Section 1
Introduction
due to stormwater runoff is the primary design issue.
Local The local governing body in which the construction takes
Jurisdication place. In this manual local jurisdiction is used
interchangeably with city.
MEP Maximum Extent Practicable. The NPDES goal of
pollutant reduction through the use of BMPs. For the
North Central Texas area, this goal is achieved through a
site rating of 0.70 or greater.
MS4 or MSSSS Municipal separate storm sewer system permitting
program established by EPA in the 1987 Amendments to
the CWA which requires cities with a :population of over
100,000 (and other related areas) to develop monitoring
and control systems to reduce the amount of pollution
discharged from the separate storm sewer system. As it
relates to construction activities, the M[S4 permit program
requires the local jurisdiction to monitor and control the
impacts of construction activities to water quality.
NOI Notice of Intent (NOI). Documentation of construction
activity which is submitted to the EPA. and possibly the
local jurisdiction prior to construction. It serves as a
notification to the EPA of construction. activity as well as a
commitment by the mvner eon rator that he /she
understands the requirements of the NPDES General
Permit for Storm Water Discharges From Construction
Activities and that measures will be taken to implement
and maintain an SWPPP at the site. Copies of the NOI may
be requested by the local jurisdiction.
NOT Notice of Termination (NOT). A completed form sent to
the EPA upon stabilization of the site that serves as notice
that the site is no longer subject to the requirements of the
NPDES General Permit for Storm Water Discharges From
Construction Activities. Copies of the MOT may be
requested by the local jurisdiction.
NPDES National Pollutant Discharge Elimination System. The
1972 amendments to the Federal Water Pollution Control
Act (also referred to as the Clean Water Act or CWA)
prohibited the discharge of any pollutant to navigable
waters from a point source unless the discharge is
authorized by an NPDES permit. The Water Quality Act of
1937 added section 402(p) to the CWA establishing phased
and tiered requirements for storm water discharge under
the NPDES program. Under these regulations, any
construction activity with a disturbance area of 5 acres or
NCTCOG Construction BMP Manual 1 -4 February 1993
Section 1
Introduction
greater will require adherence to an NPDES permit
limiting the release of pollution from the site. An NPDES
"General Permit" is available for the State of Texas to
permit the majority of construction projects in the North
Central Texas area. This general permit sets forth
requirements and criteria for controlling pollution at a
construction site. This manual serves to assist in meeting
the requirements set forth in the general permit.
Operator The owner or contractor (or both) of a site who has 'day-to
day operational eontroi'of construction operations at the
site. The operatot is the person(s) responsible for
maintenance of the SWPPP and impleirtentation of the
pollution reductiort mensures defined in the SWPPP. The
operator conartits to this responsibility through the
of JuV
j 11UJJ1Vll 1 R E)1 The L _ _7 _ of il_ •
_ w nT defines . i
entity as the operettor of the site. There can be more thart
one operator for the site (co pern-dttee situation). Any
party associated with a construction project that meets
e_ ither of the following two criteria:
1. The party has operational control over construction
plans and specifications, including the ability to
make modifications to those plans and specifications;
or
2. The party has day -to -day operational control of those
activities at a project which are necessary to ensure
compliance with a storm water pollution prevention
plan for the site or other permit conditions
There can be more than one operator for the site (co-
permittee situation).
Sediment The soil particles deposited through the process of
sedimentation as a product of erosion. These soil particles
settle out of runoff at variable rates based on the size of the
particle and soil type.
Sedimentation The process of soil being deposited through the settling of
soil particles collected in runoff through erosion.
Site Rating Also referred to as site factor, this is a number assigned to
the site based on the calculated amount of sediment
retained on a disturbed construction site by the use of best
management practices. Calculation of the site rating is
shown in the Design Methodology section (Section 3) of
the manual. For normal conditions, a goal of 0.70 is
satisfactory, but the local jurisdiction can modify this
requirement, if necessary, on a site specific basis.
NCTCOG Construction BMP Manual 1 -5 February 1993
Section 2
Administrative Policies
contacted prior to the initiation of construction.
As defined in the federal regulations, an NPDES permit is required for:
"Construction activity including clearing, grading and exen tion activiti�s
exeept. orerations that result irt the disturbance of less than five aeres of t
disturbing at least five acres, or construction activity disturbing less than five
acres which is part of a larger common plan of development or sale with the
potential to disturb cumulatively five or more acres."
The plan shetil eonsist of prepetring permit requirements include the preparation
of a Storm Water Pollution Prevention Plan (SWPPP) for any construction
project in which 5 acres or more of a single site or common plan of development
are disturbed by clearing, grading, grubbing or other construction activities. The
SWPPP consists of an erosion and sediment control plan along with an
accompanying report that outlines the methods that will be employed to reduce
pollution at the site. The SWPPP shall be prepared in accordance with the design
guidelines presented in this manual by a Registered Professional Engineer,
licensed in the State of Texas.
A SWPPP will be required for sites less than 5 acres if the site is part of a larger
development whose total disturbed area is greater than 5 acres. An example of
sites in a common plan of development include residential lots in a subdivision
or a large commercial tract with several pad sites under construction at one time.
Figure 2 -1 shows the steps in determining if an SWPPP is required by the EPA.
Each operator will be responsible for their site(s) and will be :required to submit
appropriate information to the EPA. For cities in the North Texas area which are
subject to MS4 permitting, NOIs and NOTs are to be submitted to the
appropriate city department. At the discretion of the local jurisdiction, standard
SWPPPs can be approved without the signature and seal of a registered
professional engineer for site areas less than 1 acre with minimal (less than 1
acre) offsite drainage impacting the site. This will likely be required for
residential lots which are part of a larger common plan of development that are
developed separately by different operators or are non - contiguous across the
development. It is the responsibility of the designer to provide a system in which
all erosion and pollution controls effectively reduce sediment: transport and
potential chemical and septic spills, while not excessively disrupting
construction activities.
Best Management Practices (BMPs) should be incorporated into the SWPPP to
reduce runoff pollution to the maximum extent practicable (MEP). BMPs consist
of procedures, techniques and devices that effectively reduce pollution in runoff
while not severely impacting construction operations and project cost. This
manual describes several BMPs common to the North Central Texas area and
establishes a minimum criteria for cost effective onsite control of runoff
constituents.
The local jurisdiction may provide an administrative system to ensure the
NCTCOG Construction BMP Manual 2 -2 February 1993
Section 2
Administrative Policies
preparation of an SWPPP for each applicable construction project along with
methods of monitoring the SWPPP. While not responsible for the adequate
design of the SWPPP under the general permit, MS4 permitted local jurisdictions
may notify the owner, engineer or contractor of breeches of erosion and
sediment control devices due to inadequate design, poor maintenance of the
control devices, improper installation of control devices, or other problems that
undermine the effectiveness or intent of the SWPPP. As part of the MS4 permit
requirements, the local jurisdiction may address problems associated with
improper discharges of storm water into a municipal separate storm sewer
system (see Ordinance Authority later in this section).
MS4 permitted cities in the North Central Texas region along with other
communities require the submission of the NOI before the initiation of
construction for projects which meet the submission requirements above. This
includes all projects, including projects performed by franchise utilities which
disturb large areas of land. Additional agreements may be reached between local
jurisdictions and the franchise utilities to clarify and /or simplify this procedure.
Cities with a population of less than 100,000 are currently exempt from the
NPDES requirement for construction sites through the hitermodet! Surface
. provisions found in 40 CFR 122.26(e)(1)(ii)
and (g) of the NPDES regulations.
"Section 106 40 C]FR 122.26(e)(1)(ii ) and glof the Transportation Act NPDES
regulations provides that EPA shall not require any municipality with a
population of less than 100,000 to apply for or obtain a permit for any storm
water discharge associated with an industrial activity other than an airport,
power plant, or uncontrolled sanitary landfill owned or operated by such
municipality before October 2,1992..." August 7, 2001.
Projects in which the city is the owner or operator and the city meets the
requirements above are exempt. Private projects are subject to the requirement
wherever the project or owner is located.
Problem Definition
Pollution through storm runoff is intensified at construction sites due to the
removal of the natural groundcover of the site as well as the introduction of
hazardous chemicals and wastes to the area. Measures are required both during
construction and after the completion of construction to stabilize the site.
Stabilization of the site during construction activities consists of the installation
of temporary or permanent measures to prevent erosion or to intercept sediment
prior to it leaving the site. This can be accomplished through the use of
groundcover, mulching, paving, silt fences, and sediment basins along with
modifying construction methods to reduce the disturbed areas of construction.
NCTCOG Construction BMP Manual 2 -4 February 1993
Section 2
Administrative Policies
Goals
The primary goal of the construction activity related NPDES program is to
minimize sediment transport off of construction sites and eliminate the
introduction of hazardous chemicals, fuels, grease, lime, cement, and other
construction related wastes into storm sewer systems, drainage ways, streams,
rivers and other bodies of water. Sediment is the collection of ;soil particles
loosened from the existing ground through the erosion process and transported
via storm water or wind to other locations on or offsite. This manual delineates
the procedures associated with the development of a SWPPP and itemizes both
structural and non - structural methods to reduce and control potential pollution
associated with construction.
The NPDES General Permit for construction provides only for the release of
storm water from a construction site. Discharges of material other than storm
water except those noted below must be authorized by another NPDES permit.
Table 2 -1 lists non -storm water discharges from active construction sites that are
acceptable under the General Permit. Release of these discharges must be
accounted for in the SWPPP along with methods to address erosion prevention
and minimization of associated pollution.
• Discharges from fire fighting activities.
• Fire hydrant flushings.
• Water used to wash vehicles or control d -` where detergents are not
used.
• Water used to control dust.
• Potable water sources (including waterline flushings).
• Routine external building wash down that does not use detergents.
• Uncontaminated ground water
infiltratiortr or spring water.
• Foundation or footing drains where flows are not contaminated with
process materials such as solvents.
A Springs, ripetrian habitats, wetlands and ed ground-mater.
AL irrigation water.
A Exterior building wash down without detergents.
• Pavement wash waters where spills or leaks of toxic or hazardous
materials have not occurred (unless all spill material has been removed)
and where detergents are not used.
• Air conditioning condensate.
Table 2 -1- Allowable Non -Storm Water Discharges
This manual serves as a tool for the design engineer, contractor, and owner to
design and maintain an effective system to control the release of sediment and
hazardous chemicals from a construction site. A variety of best management
practices is presented representing common techniques that address the needs
NCTCOG Construction BMP Manual 2 -5 February 1993
Section 2
Administrative Policies
and conditions of the North Central Texas area. Other methods are available,
which, in some circumstances, may be more cost effective in reducing sediment.
Verification of method effectiveness will be required along with examples of
other installations in order to obtain approval for these new techniques.
Verification of efficiencies may be based on acceptable published data (other
BMP manuals, research and product data to a limited degree) or by certification
by a registered professional engineer. Typically this information will be
submitted to the local jurisdiction and approved on a site -by -site basis. If certain
new techniques prove useful and cost effective for a range of applications, this
manual may be revised to reflect the acceptance of the new technique. However,
acceptance of any technique on a site -by -site basis is at the discretion of the local
jurisdiction. A formal amendment process for incorporation of these new
techniques into this manual will be developed and implemented by the
NCTCOG at a later date.
Due to the variety of soil types, site conditions and drainage patterns in the
north central Texas area, the responsibility of selecting and implementing the
BMPs is the responsibility of the operator of the site as defined in the general
permit Notice of Intent. Design of the SWPPP must be prepared by a registered
professional engineer licensed in the State of Texas and familiar with drainage
design and construction practices with the exception of sites less than 1 acre in
size (which are part of a larger common plan of development). Standard plans
are provided in this manual (Section 6) that can be utilized for small tracts (1 acre
or less) with minimal offsite drainage impacts (less than 1 -acre offsite drainage)
without the seal of a professional engineer. The operator (as defined in the
Notice of Intent) will assume full responsibility for the adequacy of design and
implementation of the plan.
Ordinance Authority
The National Pollution Discharge Elimination System ( NPDES) is the federal
policy that governs the requirements associated with runoff pollution,
establishing the Notice of Intent (NOI), the Storm Water Pollution Prevention
Plan ( SWPPP) and the Notice of Termination for construction activities. The U.S.
Environmental Protection Agency has prepared and published 'Fimrl Reissuance
of NDPES General Permits for Storm Water Discharges From Construction Sites
Activities in Region 6; Notice' in the Federal Register, Vol. 57 63 No. i75128,
Wednesday Monday, Septembe9 uT ly 6, +9421998. This General Permit serves
as authorization for discharge of storm water from construction activities which
disturb 5 acres or more in a single development or common plan of development
in conformance with the Clean Water Act as amended in 1987. If desired, the
operator can forego the general permit and submit a specific site permit
(individual permit) application to the EPA for review and approval. A specific
site permit may address unique conditions of the site or constrl action activities
which are not adequately addressed as part of the general permit. This is
discouraged by the EPA.
NCTCOG Construction BMP Manual 2 -6 February 1993
Section 2
Administrative Policies
Each city with a population as defined by the last census of greater than 100,000
requires an NPDES permit for the city's storm sewer system. This permit is often
referred to as a Municipal Separate Storm Sewer System permit or MS4 permit.
Part of this permit requires the submission of a management plan to address
pollution reduction in the system. As stated in 40 CFR 122.26 (D) this
management plan includes:
A description of a program to implement and maintain structural and non-
structural best management practices to reduce pollutants in storm water
runoff from construction sites to the municipal storm sewer system, which
shall include:
(1) A description of procedures for site planning which incorporate
consideration of potential water quality impacts;
(2) A description of requirements for non - structural and structural best
management practices;
(3) A description of procedures for identifying priorities for inspecting
sites and enforcing control measures which consider the nature of
the construction activity, topography, and the characteristics of soils
and receiving water quality; and
(4) A description of appropriate educational and training measures for
construction site operators.
As noted above, additional requirements may be imposed by the MS4 permitted
areas to address pollution at the construction site. These requirements are in
addition to the federal requirements as outlined in the general permit.
As part of the MS4 permitting, the cities of Arlington, Dallas, Fort Worth,
Garland, Irving, Mesquite and Plano will be developing ordinance authority
which will address measures to insure storm water quality management in the
respective city. These measures will vary from city to city, but: the technical basis
of the BMPs provided in this manual will be applicable in addressing
construction related storm water management.
NCTCOG Construction BMP Manual 2 -7 February 1993
NM..
Each city with a population as defined by the last census of greater than 100,000
requires an NPDES permit for the city's storm sewer system. This permit is often
referred to as a Municipal Separate Storm Sewer System permit or MS4 permit.
Part of this permit requires the submission of a management plan to address
pollution reduction in the system. As stated in 40 CFR 122.26 (D) this
management plan includes:
A description of a program to implement and maintain structural and non-
structural best management practices to reduce pollutants in storm water
runoff from construction sites to the municipal storm sewer system, which
shall include:
(1) A description of procedures for site planning which incorporate
consideration of potential water quality impacts;
(2) A description of requirements for non - structural and structural best
management practices;
(3) A description of procedures for identifying priorities for inspecting
sites and enforcing control measures which consider the nature of
the construction activity, topography, and the characteristics of soils
and receiving water quality; and
(4) A description of appropriate educational and training measures for
construction site operators.
As noted above, additional requirements may be imposed by the MS4 permitted
areas to address pollution at the construction site. These requirements are in
addition to the federal requirements as outlined in the general permit.
As part of the MS4 permitting, the cities of Arlington, Dallas, Fort Worth,
Garland, Irving, Mesquite and Plano will be developing ordinance authority
which will address measures to insure storm water quality management in the
respective city. These measures will vary from city to city, but: the technical basis
of the BMPs provided in this manual will be applicable in addressing
construction related storm water management.
NCTCOG Construction BMP Manual 2 -7 February 1993
Section 3
Design Methodology
site. The primary methods of soil control consist of minimizing onsite
disturbance of the soil and groundcover and providing structural measures to
retain sediment onsite after erosion occurs. Figure 3 -1 shows typical relative
effectiveness between several erosion and sediment control techniques.
By far, the most effective method to reduce the sediment lost from a tract of land
is to prevent the occurrence of erosion. While structural barriers such as those
shown in this manual may provide 70 to 90% removal of sediment from runoff,
natural groundcover and mulching can provide up to 98% reduction in erosion
and site soil loss. Therefore, the primary goals of the erosion control plan for a
construction site is to protect the soil from erosion and minimize the area of
disturbance through the phasing of construction activities, mulching of
disturbed but inactive areas, and providing tarps, seeding or hydromulching of
stockpiles. These techniques are not only the most effective at reducing soil loss,
they are normally the most cost effective due to low initial cost and reduced
maintenance requirements.
Structural controls are the second line of defense, treating sediment -laden storm
water prior to it leaving the site. All construction activities will require areas in
which soil is disturbed. Storm water runoff that crosses areas of exposed soil will
require treatment by adequate structural controls in accordance with the
guidelines presented in this manual. Structural controls include diversion of
storm water around areas of construction, and filtration and sedimentation
(detention) of sediment -laden runoff that crosses disturbed areas. Guidelines for
the use of several typical methods of structural controls are presented as part of
this manual. Other methods will be considered by the local jurisdiction if the
effectiveness of the technique can be determined through testing or similar
successful applications. If the technique proves cost effective for the North
Central Texas region, amendments to this manual will be incorporated by
methods established at a future date.
Figure 3 -2 depicts the erosion and sediment control design methodology
graphically. The runoff across both disturbed and non - disturbed areas of a
drainage basin produce a quantity of erosion. This quantity is estimated through
the use of the Universal Soil Loss Equation as a mass per time period. If
necessary, structural controls are used to reduce the sediment transported offsite
to an acceptable level. For the North Central Texas area, a minimum site rating
of 0.70 is used as a guideline for the adequate design of erosion and sediment
control systems. The site rating is defined as the amount of sediment captured
on site divided by the calculated erosion for the disturbed construction site.
In addition to an acceptable site ratio of 0.70, the foliowing Table 3 -1 lists the
maximum rates of soil loss from a site during construction activities. These
values are recommended maximums based on site slope and are subject to
change by the local jurisdiction due to potential downstream impacts or
historical erosion problems for the site.
NCTCOG Construction BMP Manual 3 -2 February 1993
Section 3
Design Methodology
structural controls to intercept sediment prior to it being transported offsite.
The site is analyzed on a drainage basin basis by applying the USLE to both the
pre - construction conditions and the anticipated construction conditions (see
Figure 3 -2). The pre - construction conditions reflect the existing groundcover at
the site, the existing drainage paths of the site and the topography of the
drainage basin. A calculated quantity of erosion is determined for each drainage
basin to serve as the basis for the analysis.
The K factor relates to the potential erodibility of the soil..
Table 3 -2 provides approximate values of K for various soil types and can be
used in calculations if detailed data is not available. It is strongly suggested that
soil erodibility be determined as part of the geotechnical investigation of the site
in order to determine the most effective means to reduce site erosion.
Soil Type
K
Sand
0.03
Fine Sand
0.14
Loamy Sand
0.10
Sandy Loam
0.24
Loam
0.34
Silt Loam
0.42
Silt
0.52
Sandy Clay Loam
0.25
Clay Loam
0.25
Silty Clay Loam
0.32
Sandy Clay
0.13
Silty Clay
0.23
Clay
0.20
Table 3 -2 - Soil Erodibility Factors (K)
based on Environmental Engineering Handbook
The length -slope (LS) factor considers the topographic features of the drainage
basin. The LS factor is defined by the length and slope a drop of water will travel
through the drainage basin from the farthest reach to the point of analysis. Table
3 -4 lists values of LS for a wide variety of slope and drainage length.
NCTCOG Construction BMP Manual 3 -6 February 1993
Section 3
Design Methodology
The cropping factor (CS) considers the protection of natural ground cover in
preventing erosion of the soil. This is dependent on the type of vegetation (grass
or trees) and the density of the vegetation on the site. The following table
provides approximate values for C, for a variety of conditions.
Type and Height
of Raised
Vegetative Canopy
Canopy
Cover, %
Ground cover that contacts the surface, %
0
20
40
60
80
95 -100
No appreciable canopy
Canopy of tall weeds or
short brush ( <1' tall)
0
0.450
0.200
0.100
0.042
0.013
0.003
215
0.360
0.170
0.090
0.038
0.012
0.003
50
0.260
0.130
0.070
0.035
0.012
0.003
75
0.170
0.100
0.060
0.031
0.011
0.003
Appreciable brush or
bushes (5' fall height)
25
0.400
0.180
0.090
0.040
0.013
0.003
50
0.340
0.160
0.085
0.038
0.012
0.003
75
0.280
0.140
0.080
0.036
0.012
0.003
Trees w/o appreciable
low brush ( >10' fall
height)
25
0.420
0.190
0.100
0.041
0.013
0.003
50
0.390
0.180
0.090
0.040
0.013
0.003
75
0.360
0.170
0.090
0.039 1
0.012
0.003
Table 3 -3 - Cropping Factors
based on Environmental Engineering Handbook
The construction phase erosion calculations represents the anticipated soil
erosion for the site with areas disturbed due to construction. Disturbance of the
soil primarily affects i:he C, factor, increasing it as much as 2 to 100 times. For
each drainage basin, this C, value is weighted based on the percentage of
disturbed area in the basin:
Cstotat = L(Q.n *Aun) + (Q,*Adis)] / At... (Equation 3)
where:
Cstota, = Csfor drainage basin
Csun = C, for undisturbed areas
Ain = Area of undisturbed areas of drainage basin (acres)
Csdis = C, for disturbed areas
Adis = Area of disturbed areas of drainage basin (acres)
Atota, = Total Area of drainage basin (acres)
The sensitivity of the C, value reflects the importance of minimizing the area of
disturbance and providing protection to the disturbed soil before erosion occurs.
Approximate values of C, are presented in Table 3 -3 which represents a variety
of groundcover conditions. For construction areas stripped of natural
vegetation, a C, value! of 1.0 shall be used.
NCTCOG Construction BMP Manual 3 -8 February 1993
Legend For Calculation Worksheet
Column Description
1 DA # - Enter drainage area identification
2 Area (Ac) - Enter area of drainage basin in acres
3 Avg. K - Enter Weighted K value for the drainage basin from Table 3-2
4 LSd - Enter Value of LS for drainage basin based on the disturbed
length and slope of the basin and Table# :3 - 11
5 Cd - Enter value of Cropping Factor Cs for disturbed conditions from
Table 3-3 with cleared or disturbed areas having a value of 1.0
6 ZAsd - Calculate anticipated soil loss from drainage basin under
disturbed conditions from USLE - ZA = Area * 300 * K * LSu * Cu * 2000
7 Fe - Enter effectiveness rating of BMP used in drainage basin from BMP
sheets in section 4.
S ZAret - Compute soil retained in Structural Controls by ZAret = ZAsd
Fe
At the bottom of the form, columns 6 and 8 are totalled. The site rating is based on
column 8 divided by column 6.
NCTCOG Construction BMP Manual 3 -12 November 1993
Section 4 - ConsUuction BMPs
Sediment Basin
Applications
Perimeter Control
High flow outlet_ Emergen
'
Slope Protection
Desi n Ihi h water 1' min S31Iway
Sediment Trapping
max
Deli n capacity 1' max Earth 1 Max
Channel Protection
- Berm
Temporary Stabilization
Outfall
Permanent Stabilization
Waste Management
Cross Section Dewatering Outlet
(Perforated riser shown)
Housekeeping Practices
Targeted Constituents
DESCRIPTION
A sediment basin is a pond area with a controlled outlet in which sediment.
0 Sediment
laden runoff is directed to allow settling of suspended sediment from the
p Nutrients
runoff. It provides treatment for the runoff as well as detention and controlled
Toxic Materials
release of runoff, minimizing flood impacts downstream.
O Oil &Grease
PRIMARY USE
Sediment basins should be used for all sites with adequate open space to site
O Floatable Materials
the basin and the ability to direct a majority of the site drainage into the basin.
O Other Construction
For sites with disturbed areas of 10 acres and larger that are part of a common
Wastes
drainage area, sediment basins are required as either temporary or permanent
Implementation
controls unless specific site conditions limit their use.
Requirements
APPLICATIONS
• Capital Costs
Sediment basins serve as treatment devices which can be used on a variety of
project types. It is normally used in site development projects in which large
p Maintenance
areas of land are available for the basin, a stream or drainage way crosses the
O Training
site, or a specific water feature is planned for the site. Sediment basins are
highly effective at reducing sediment and other pollutants for design storm
• Suitability for
conditions. It also reduces maintenance requirements due to the central
Slopes >5%
location of the sediment and minimal structural requirements of the basin.
Legend
DESIGN CRITERIA
0 Significant Impact
❑ Maximum drainage area contributing to the basin should be 10 acres or
less. Larger sediment basins will require specific measures to address the
p Medium Impact
potential for overtopping of the basin and possible failure of the berm.
O Low Impact
❑ Minimum capacity of the basin shall provide storage for the calculated
? Unknown or
volume of runoff from a 2 -year, 24 -hour storm per disturbed acre of
drainage area. Where no such calculation has been performed, the
Questionable Impact
minimum capacity of the basin shall be 3600 cubic feet per disturbed acre
of contributing drainage area.
Fe = 0.90
❑ Deposited sediment shall be removed when the storage capacity of the
S-6
basin has been depleted by 20%.
❑ Minimum width of the embankment at the top shall be 8 feet.
❑ Minimum embankment slope shall be 3:1.
❑ Maximum embankment height shall be 6 feet as measured from the toe of
the slope on the downstream side.
❑ The basin outlet shall be designed to accommodate a 10 -year design storm
•
without causing damage to the containment structure.
❑ Minimum outlet capacity shall be 0.2 CFS per acre of contributing
drainage area.
North Central Texas
Council of Governments
NCTCOG Construction BMP Manual 4 -31 February 1993
Section 5
NPDES Requirements
Section 5
NPDES Requirements
As part of the Water Quality Act of 1987, storm water discharges associated with
industrial activity from a point source to waters of the United States is unlawful,
unless authorized by an National Pollutant Discharge Elimination System
(NPDES) permit. Construction activities which disturb an area greater than 5
acres by grading, clearing, grubbing or other construction activity is defined as
an industrial activity, subject to the requirement of an NPDES permit. In order to
effectively manage the permit process, the EPA has produced a general permit
for construction activities which defines specific conditions and requirements to
be met as part of the permit. The general permit establishes the procedures
required for proper coverage, the requirement for a Storm Water Pollution
Prevention Plan (SWPPP) and requirements for termination of permit coverage.
In addition to NPDES permits for construction activities, large and medium size
municipalities are required to obtain NPDES permits for their Municipal
Separate Storm Sewer System (MS4) to control storm water outflow into waters
of the United States. This permit will require local jurisdictions to take an active
role in monitoring and controlling pollution due to storm water runoff from a
variety of sources including construction activities. Therefore, in addition to
meeting the requirements for the general permit and subn-dttingthe requir�el
NO! and NOT, the site operator is obligated to contact the local jurisdiction to
determine local requirements that may be required in addition to general permit
coverage.
As noted above, all construction activities which disturb 5 acres or more land
area or are a part of a common development or plan of sale is subject to the
NPDES permit requirement. Failure to abide by the terms of the general permit
or failure to develop and implement a site specific NPDES permit is a violation
of federal law, which can subject the owner or operator to severe fines or
imprisonment.
Compliance with the requirements of the general permit consists of three four
major components; determination of eli ig bilAy, preparation and implementation
of a Storm Water Pollution Prevention Plan, submission of the Notice of Intent,
preparation and implementatiort of a Storm Water t: __ _ _ and
submission of the Notice of Termination. This section details the sequence of
events and requirements for each of these components.
Figure 5 -1 delineates the basic steps required when construction activities for a
single site or common development will disturb an area larger than 5 acres.
Note that the Storm Water Pollution Prevention Plan (SWPPP) is prepared in
NCTCOG Construction BMP Manual 5 -1 February 1993
Section 5
NPDES Requirements
NCTCOG Construction BMP Manual 5 -2 February 1993
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CONSTRUCTION BMP MANUAL
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NPDES SEQUENCING
env:w,menmrenginmrs ZWjscientistsan. ts
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Figure 5 -1
NCTCOG Construction BMP Manual 5 -2 February 1993
Section 5
N'PDES Requirements
conjunction with the construction documents for the site and before the
submission of the Notice of Intent (NOI) to the EPA. As part of the NOI, the
operator must certify that a SWPPP has been prepared for the site and that the
operator will conform to the requirements of the SWPPP.
guideline, At ffie time of writing of ffids Size is being
reviewed by the EPA. A recent court case stated thatthe 5 acre 1i thadno
jttstification frorn the standpoint of larger sites having a greetter impact oi
enviror=ertt than smaller sites. it is anticipated that the 5 e-lnrdt may 1
.__d____d to 1 acre or less in the n__r L__L___ At iLL time Lo_.__ -___ the EPA is not
reqttiring sites wl-dch disturb areas smaller than 5 etcres to sttbrrdt an NO!
prepare the SWPPP. When and if this hn-dt chartges, referencles. "LOAL-1-Me 555 --Cte
criteria in t�ds manual must be revised to reflect the new hn L
Eligibility Determination
Permittees are only authorized to discharge pollutants in storm water runoff
associated with construction activities provided that the construction activity
discharge does not damage listed endangered /threatened species or critical
habitats. Any facility identified by EPA as having an impact on endangered
species will now be required to certify that the storm water discharge will not
affect listed endangered species and their habitats. The permit provides a six -
step process to assist applicants in pursuing certification:
L Determine if the construction site is found within designated critical habitat
for listed species.
2. Determine if listed species are located in the county(ies) )here the
construction activity will occur.
3. Determine if any federally listed endangered or threatened species may be
present in the project area.
4. Determine if listed species or critical habitats are likely to be adversely
affected by the construction activity's storm water discharges or storm water
discharge - related activities.
5. Determine if measures can be implemented to avoid any adverse effects.
6. If a determination has been made that construction activity will affect
endangered species, then the applicant must receive clearance from Fish and
Wildlife Services and /or the National Marine Fisheries Service to a obtain
permit coverage.
After permit eligibility has been determined, preparation of the Storm Water
Pollution Prevention Plan may begin.
NCTCOG Construction BMP Manual 5 -3 February 1993
Section 5
NPDES Requirements
Preparation of the SWPPP Storm Water Pollution
Prevention Plan
The Storm Water Pollution Prevention Plan (SWPPP) is the document(s) that
defines the measures to be employed to prevent the release of pollution from the
construction site. The SWPPP consists of two doettments components, a
narrative description of the project and a plan view of the site with proposed
improvements and pollution reduction methods shown. The SWPPP identifies
the techniques that the operator will use to reduce site erosion and sediment loss
and manage construction - related wastes. It identifies the maintenance
procedures that the operator will perform to preserve the efficiency of the
techniques used. l tals
acknowledge the req irements of ?4PBES and to eomrMt to compliance -mith the
e specific SWPPP.
The SWPPP identifies the techniques that the operator will use to reduce site
erosion and sediment loss and manage construction - related wastes. It identifies
the maintenance procedures that the operator will perform to preserve the
efficiency of the techniques used. The SWPPP must clearly describe the control
measures, the timing and sequence of implementation, and which permittee
(contractor) is responsible for implementation of the control measures.
Unlike many construction documents, the SWPPP is very likely to change
during the course of construction due to variations in construction techniques
and /or site conditions. These modifications should be made by the original
preparer of the SWPPP or someone else experienced in the design of erosion and
sediment control systems in order to maintain the effectiveness of the original
SWPPP design. The EPA requires that the SWPPP documents be updated within
7 days of any change in the pollution prevention systems employed on the site.
The SWPPP is not submitted to the EPA as part of the NOI; instead it must be
available onsite or nearby for inspection by EPA personnel, and state and /or
local jurisdiction staff.
In preparing the SWPPP the following information must be presented:
Site Description
A. Description of Construction
B. Project Sequencing
C. Total and Disturbed Areas of Site
D. Estimate of Runoff Coefficient (C) Before and After
Construction
E. Site Map With Drainage and Layout Information
F. Location and Description of Any Discharge Associated
with Industrial Activity Other Than Construction
G. Flame of Receiving Waters
H. Copy of Permit Requirements
NCTCOG Construction BMP Manwd 5 -4 February 1993
Section 5
NPDES Requirements
I. If Applicable, Information on Listed Species or Critical
Habitat Affected by Activity
J. If Applicable, Information on Historic Places Affected by
Activity
2. Controls To Be Used Onsite
A.
Construction, Erosion and Sediment Controls
1.
Short and Long Term Goals
2.
Stabilization Practices
3.
Structural Practices
B.
Storm Water Management
1.
Flow Reduction
2.
Velocity Dissipation
C.
Other Controls
1.
Solid Material Discharge
2.
Offsite Sediment Tracking
D:
3.
Compliance with State and Local Requirements for
Waste Disposal
4.
Construction and Waste Materials Storage
5.
Pollutant Sources from Construction Support
Activities
6.
Protection Measures for Listed Species or Critical
Habitat
D.
Compliance
with State and Local Requirements for
Sediment and Erosion Control
3. Maintenance Requirements and inspection R cords of Wa
Management Procedures for Control Measures
4. Inspection Schedule Requirements
5. Planned Non -Storm Water Discharges
6 5 be Employed After
A detailed checklist for both the narrative and the plan are included in Section 6
of this manual to ensure that each of the above issues is addressed in the SWPPP.
A form is also presented for the narrative portion to simplify preparation of the
document.
Notice of Intent
The Notice of Intent (NOI) is the primary document used by the EPA to monitor
and enforce compliance with the NPDES permitting requirements. The NOI is to
be submitted after preparation of construction plans and SWPPP at least 48
hours prior to the beginning of construction activities at the site. Unless notified
NCTCOG Construction BMP Manual 5 -5 February 1993
Section 5
NPDES Requirements;
by the EPA during the 48 hour period after submission, the NOI is considered
acceptable and construction activities, including implementation of the SWPPP
can proceed under thi ts offlhe SW assumed • coverage
NPDES general •
The operatorLs) of the site is required to submit the NOI and is ultimately
•• • for •• • of pollution and sediment loss from
site. The orerator-carrbe the owner (or owner's representative), the gel
contractor for the project or srecific subcontractors for the rroject. The operator
Ims
WWI 8MWjr1LW�1WJM4
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•
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■ - - _ almets .:
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A copy of the form is :included in Appendix C of this manual. Additional copies
can be obtained from the EPA. .
Figure 5 -2 shows an example of a completed the front of the standard Notice of
Intent form. Detailed instructions for completion of the NOI form can be found
on the back of the form as shown in Figure 5 -3. Completed NOIs should be
submitted to EPA at the designated address shown on the back of the form.
Block 1 identifies the perator of the facility complete with address and phone
number. The status block
11 locates the site by a / / available, by a variety v
other means. USGS aps of the area will normally provide latitude and
longitude inforrytatio r if a street address is not available.
I Block H! of the NC)l a idresses the type of activity and general storm water
NCTCOG Construction BMP Manual 5 -6 February 1993
Section 5
NPDES Requirements
:.
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NCTCOG Construction BMP Manual 5 -7 February 1993
Section 5
NPDES Requirements
PUPEFOA MIA . • .
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- _ :• :
i i Mom v tirm :
Notice of Termination
The Notice of Termination (NOT) provides notification to the EPA that the site
has been stabilized in accordance with the requirements of the general permit
and that construction on the site is completed. Upon submission of the NOT, the
operator loses the authority to discharge storm water under the conditions of the
general permit.
As stated in the general permit, the NOT for the site cannot must be submitted
until the site is stabili ted or there is a change in operators for the site within 30
days of one or more of the following conditions being met: 1) final stabilization
iEnvironmental Protection Agency, "Final NPDES General Permits for Storm
Water Discharges From Construction Sites; Notice, " Federal Register, Vol.
57, No. 175, Wednesday, September 9, 1992, p. 41222.
NCTCOG Construction BMP Manual 5 -8 February 1993
-
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PUPEFOA MIA . • .
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Notice of Termination
The Notice of Termination (NOT) provides notification to the EPA that the site
has been stabilized in accordance with the requirements of the general permit
and that construction on the site is completed. Upon submission of the NOT, the
operator loses the authority to discharge storm water under the conditions of the
general permit.
As stated in the general permit, the NOT for the site cannot must be submitted
until the site is stabili ted or there is a change in operators for the site within 30
days of one or more of the following conditions being met: 1) final stabilization
iEnvironmental Protection Agency, "Final NPDES General Permits for Storm
Water Discharges From Construction Sites; Notice, " Federal Register, Vol.
57, No. 175, Wednesday, September 9, 1992, p. 41222.
NCTCOG Construction BMP Manual 5 -8 February 1993
Section 5
NPDES Requirements
of the site is achieved; 2) another operator has taken control over all areas that
have not been finally stabilized; or 3) temporary stabilization has been
completed and the residence has been turned over to the homeowner (for
residential construction on W. ,
SIOFes, r'P rttP rind velocity, attenttat-rs for storm drain out is and concrete
lirringfor harmers. Final stabilization means that either: 1) all soil disturbing
activities have been completed and a uniform perennial vegetative cover with a
density of 70% of the native background vegetative cover has been established
for all areas outside of paved areas or building_ limits, or equivalent other
stabilization measures fril2rap, gabions, geotextiles, etc.) have been employed;
2) for individual lots in residential construction projects, final stabilization as
defined in 1) above is achieved, or temporary stabilization including perimeter
controls for an individual lot have been implemented, the home has been
transferred to the homeowner, and the homeowner has been instructed on the
benefits of final stabilization; or 3) for construction on land u; ;ed for agricultural
purposes, the disturbed land is returned to its preconstruction agricultural use.
The section on BMPs in this manual and the other mantials ryas series outlines
techniques and design criteria for both temporary and pen Went stabilization
measures.
An As stated above, an NOT is also must be submitted if the operator of the site
changes during the construction operations. In the case of a co- permittee, no
interruption of construction is required if the general contractor (a co- permittee
with the owner) leaves the site and files an NOT. The owner becomes
responsible for the site until the site is stabilized and an NOT is filed or until
another contractor files as a co- permittee (both owner and contractor become
responsible). An NOI must be in place for the site throughout the time the site is
in a disturbed condition either through the owner, the contractor or both. The
lie site.
A copy of the NOT form is included in Appendix C of this manual. Additional
copies can be obtained from the EPA. Figure 5 -4 shows an example of a
completed Notice of Termination form. Detailed instructions for completion of
the NOT form can be found on the back of the form as shown in Figure 5 -5.
Completed NOTs should be submitted to EPA at the designated address shown
on the back of the form.
items requested on the NOT are the sarne as the NEX or etre self explanatory-.
NCTCOG Construction BMP Manual 5 -9 February 1993
Section 5
NPDES Requirements
Genera' Hi hlic h� ted Permit Requirements
In addition to the filing requirements set forth in the general permit, other
requirements are included which may impact typical construction activities. A
copy of the Federal Register with the NPDES General Permit for Storm Water
Discharges From Construction Sites Activities is included at the end of this
section for reference. The following itemizes some of the specific requirement of
the permit and methods to address the requirement where applicable.
Inspection Requirements
Qualified personnel (provided by the permittee or cooperatively by multiple
permittees ) shall inspect disturbed areas of the construction site that have not
been finally stabilized, areas used for storage of materials that are exposed to
precipitation, structural control measures, and locations where vehicles enter or
exit the site, at least once every fourteen (14) calandar days and within 24 hours
of the end of a storm event of 0.5 inches or greater. Based on the results of the
inspection, the SWPPP shall be modified as necessary to include additional or
modified BMPs designed to correct problems identified. Revisions to the
SWPPP shall be completed within 7 calendar days following the inspection A
report summarizing the scope of the inspection, name(s) and qualifications of
personnel making the inspection, the date(s) of the inspection, and major
observations relatin& to the implementation of the SWPPP shall be made and
retained as part of the SWPPP for at least three years from the date that the site is
finally stabilized.
Stabilization Regu,irement For Inactive Areas
During construction, some areas which are disturbed may be inactive for
extended periods of time. The general permit addresses this issue by requiring
that areas which are inactive for periods longer than 14 days must be stabilized
through the use of seeding, mulching, sod, geotextiles or vegetative buffer strips
If it is anticipated that construction will resume within 21 days from when
activities ceased, stabilization is not required. Proper sequencing and phasing of
operations can minimize the need for temporary stabilization.
Sediment Basin Requirement
The general permit states that for common drainage areas which serve an area
with 10 or more disturbed acres at one time, a sediment basin shall be provided
where attainable until final stabilization of the site occurs.
is to be designed and -onstructed to the rttirtirmtrn standards provided in the
BNIP section of this rtnnal. As stated in the BMP, the required volume for the
sediment basin must provide storage for calculated volume of runoff from a 2-
year, 24 -hour storm for each disturbed acre of drainage area. Where this
calculation hasn't been performed, the required volume for the sediment basin is
NCTCOG Construction BMP Manual 5 -10 February 1993
Section 5
NPDES Requirements
3600 cubic feet of storage area per acre disturbed. This sedirnent basin is to be
designed and constructed to the minimum standards provided in the BMP
section of this manual.
This reqtfirement is certain to rut et burden on large, in the
region. By12hasing development and the amount of land disturbed at one time,
the size of the basin can be reduced or eliminated entirely. However, if
necessary, sSediment basins provide excellent temporary and permanent storm
water treatment and can serve as an amenity to the site. T+tt-prirnary drawback
is the amount of land required and the long term rnaintenetnee of the betsin-.-By
proper phasing of the construction and effective stabilizati of etreas _Ii_r
construction is completed in an area, the EPA requirement for sediment b -�I sins
retther to n-drdmize the s* ent and the need for the.'----
i
Where a sediment basin with the above storage reauirements is not attainable,
sSmaller sediment basins and /or sediment traps may be used. When the 3
. However, at a minimum, silt
fences or equivalent controls are required on all sideslopes and downslope
boundaries of the site.
Storm Water Management Measures
As part of the SWPPP, storm water management measures must be addressed to
permanently reduce pollutants in storm water runoff from the site. The
permittee is only responsible for installation and maintenance of the device(s)
during construction and prior to final stabilization of the site.
Specific techniques listed in the permit include storm water detention Lwet
12onds), and retention structures (sediment basins), and velocity dissipation.
Other techniques are discussed in the other manuals in this series.
Coverage of Support Activities
This permit also authorizes storm water discharges from support activities (e.g.,
concrete or asphalt batch plants, equipment staging_, yards, material storage
areas, excavated material disposal areas, borrow areas) provi Jed:
a) The support activity is directly related to a construction site that is
required to have NPDES permit coverage for discharges of storm water
associated with construction activity;
b) The support activity is not a commercial operation serving multiple
unrelated construction projects by different operators„ and does not
operate beyond the completion of the construction activity at the last
construction project it supports; and
c) Appropriate controls and measures are identified in a storm water pollution
prevention plan covering the discharges from the sup ort activity.
All discharges of storm water from ready -mix concrete batch plants covered as a
NCTCOG Construction BMP Manual 5 -11 February 1993
Section 5
NPDES Requirements
support activity must also comply with the following limitations:
a) pH — between 6.0 and 9.0 standard units;
W Oil and Grease -15 mg /l as a daily maximum; and
J Total Sus ended Solids —65 mg /1 as a daily maximum.
Spill Notification
The general permit allows for storm water discharge from construction sites
only. Discharges of other substances (other than those listed in Section 2) from
construction activities; or from operations on a site during construction are not
permitted. In the event of a spill of a hazardous substance, the operator is
required to notify the National Response Center (NRC) at (800) 424 -8802 to
properly report the spill. In addition, the operator shall submit a written
description of the release (including the type and the approximate amount of
material released), the date of the release, the circumstances of the release, and
the steps to be taken to prevent future spills to the EPA regional office in Dallas.
In addition, the SWPPP must be revised within 14 calendar days after the release
to reflect the release, stating the information above along with modifications to
minimize the possibility of future occurrences.
If fuels, oils or other substances are to be present on site, it is imperative that
closed containers be provided along with containment areas for large quantity
spills. Hazardous chemicals include fertilizers, paints, oils, grease, pesticides,
fuels, along with other construction chemicals. While much of this manual
focuses on the sediment and erosion control aspects of the SWPPP, the potential
for damaging pollution from chemicals is great. Provisions must be provided to
address potential pollution through the use of the BMPs presented along with
compliance of OSHA and other regulatory requirements.
Retention of Records
As part of the general permit, the SWPPP along with supporting documentation
must be retained for a period of 3 years after the completion of the project. This
is to protect the operator(s) of the site from future claims concerning water
quality and measures implemented at the site. It is recommended that each of
the operator(s) maintain a copy of the SWPPP for the 3 year period to protect
against potential lawsuits.
DAMON
E)nce again tl-ds addr!sses the issue of phasing of construction activities. Proper
sequencing and phasng of operations will mirdri-tize ternporary .
NCTCOG Construction BMP Manual 5 -12 February 1993
Section 6
Plan Requirements
The Storm Water Pollution Prevention Plan (SWPPP) is the primary tool for
reducing erosion and sediment loss from a construction site. It consists of two
parts: a report on the existing conditions and control methods to be employed
(Narrative) and construction documents for the erosion and sediment control
devices for the site (Pollution Control Plan). The following outlines the require-
ments and methods of preparing an SWPPP.
How to prepare an SWPPP
Narrative
The report section of the SWPPP details the existing condition of the drainage
basin including:
— Existing foliage and groundcover
— Significant topographic features
— Soil type(s) at the site
— Drainage patterns
— Major drainage way into which site drains
— Description of creeks /drainage ways on site
— Receiving waters of site drainage
- -- Copy of permit requirements
- -- Information on impact to endangered species
- -- Information on impact to listed historic places
— Other information concerning existing erosion and drainage along with
potential problems and concerns.
In addition, the SWPPP describes the techniques to be used to control the release
of sediment and other pollutants from the site. This includes the following:
— Phasing of the project (including time schedule)
— Responsibilities of the contractor and each subcontractor
— Structural sediment control techniques employed
— Temporary and permanent stabilization and treatment techniques employed
— Dust reduction techniques to be used
— Hazardous chemicals to be used on the site and containment methods to be
used (see 40 CFR 116.4 for complete listing of hazardous chemicals)
— Trash disposal procedures
The following serves as a guide outline for the preparation of the SWPPP
NCTCOG Construction BMP Manual 6 -1 February 1993
Storm Water Pollution Prevention Plan
Project Title
Operator with Responsibility for SWPPP
Prepared by TDate
Revision
Date of Revision
Operator Signature Preparer Signature
I certify under penalty of law that this document and all attachments were prepared under my direction
or supervision in accordance with a system designed to assure that qualified personnel properly
gathered and evaluated the information submitted. Based on my inquiry of the person or persons who
manage the system, or those persons directly responsible for gathering the information, the
information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am
aware that there are significant penalties for submitting false information, including the possibility of
fine and imprisonment for knowing violations.
A. Attach NOI(s) for General Information
B. Description of Construction Activity
C. Sequence of Major Construction Activities
Estimated Estimated
Activity Start Completion
Revision Date Page 1 of
D. Total Area of Site Acres
E. Total Area of Site to be Disturbed
F. Existing (Pre- construction) Vegetation
Type of GrassNegetation
G. Estimated Runoff Coefficient (C):
Pre - construction
H. Soil Types
Soil Name
Post - construction
Acres
Approximate Site
Density ( %) Coverage ( %)
Erosion Unified Site
Factor (K) Classification Coverage ( %)
I. Existing Areas of Erosion
Describe any areas which show signs of existing erosion (areas with gullies or rills, sediment buildup
in creeks, soil loss around structures, etc.). Note location, approximate area and probable cause
(disturbed area, steep slope, etc.).
J. Name of Receiving Water(s)
Revision Date Page 2 of
K. Existing Storm Sewer System
Describe any onsite storm sewer systems including location of inlets and outfalls, pipe sizes, etc. and
protection measures (i.e., inlet protection, outlet stabilization, etc.).
L. Natural Drainageways
Describe any onsite drainageways including channels, creeks, watercourses, etc. Provide name,
location, floodplain /floodway considerations, and protection measures such as buffers.
M. Wetlands and Special Aquatic Sites
Describe the areal extent and characteristics of any wetlands or other special aquatic sites ?? that will
be disturbed or will receive discharges from disturbed areas of the project and protection measures.
N. Storm Water Discharges; from Support Activities
Provide the location and description of any discharges associated with industrial activity other than
construction covered by the Construction General Permit (i.e., dedicated asphalt or concrete plants).
Provide a description of controls and measures that will be implemented to minimize pollutant
discharges. Note that discharges of storm water from ready -mixed concrete plants must comply with
the following limitations: pH — between 6.0 and 9.0, Oil and Grease — 15 mg /I as a daily maximum,
Total Suspended Solids — 65 mg /I as a daily maximum (General Permit Part X.6.b.).
Revision Date Page 3 of
O. Endangered Species Information
Provide information on whether listed endangered or threatened species, or critical habitat, are found
in proximity to the construction activity. Describe any impacts caused by storm water discharges or
storm water discharge - related activities and the measures necessary to protect such species or
habitat.
P. Storage of Construction and Waste Materials
Provide a description of construction and waste materials expected to The stored on -site (with updates
as appropriate). Include a description of controls to reduce pollutants and spill prevention and
response procedures.
Revision Date Paae 4 of
Sequence of Control Measure Implementation /Construction Activity
Associated Estimated Date Actual Date
Control Measure Construction Activity Site Location Installation Removal Installation Removal
Include all erosion and sediment controls: interim and permanent stabilization practices (establishment of vegetation, vegetative buffer strips, preservation of
mature vegetation, protection of trees, etc.); structural practices (silt fence, straw bale dike, earth dikes, drainage swales, sediment traps, sediment basins, inlet
protection, etc.); litter control; hazardous material containment; post- construction storm water management practices (storm water retention /detention structures,
open vegetated swales and depressions, infiltration, etc.); and measures necessary to protect listed endangered or threatened species, or critical habitat.
Revision Date Page 1 of
Responsibility for Control Measure Installation, Maintenance, and Removal
Associated I - Responsible Contractor
Control Measure Construction Activity Site Location Installation I Maintenance I Removal
Include all erosion and sediment controls: interim and permanent stabilization practices (establishment of vegetation, vegetative buffer strips, preservation of
mature vegetation, protection of trees, etc.); structural practices (silt fence, straw bale dike, earth dikes, drainage swales, sediment traps, sediment basins, inlet
protection, etc.); litter control; hazardous material containment; post- construction storm water management practices (storm water retention /detention structures,
open vegetated swales and depressions, infiltration, etc.); and measures necessary to protect listed endangered or threatened species, or critical habitat.
Revision Date Page 2 of
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Section 7
City Participation
Submit Notice of Intent
The NPDES Notice of Intent (NOI) shall be sent to the EPA after all city reviews
are complete and prior to the contractor moving onto the site. The NOI (see
NPDES Requirements section for sample NOI) shall be submitted to the EPA
along with a copy to the local jurisdiction. Forty -eight hours after submission of
the NOI to the EPA, the contractor may move onto the site and begin
implementing the SWPPP.
Install Erosion Control Devices
Prior to the beginning of construction at the site, structural erosion controls
must be installed and inspected by the operator (local jurisdiction inspection
is optional). These controls shall be installed in accordance with the SWPPP.
City Inspection and Approval (Optional)
The local governing agency will inspect the erosion control devices after
installation to ensure proper installation with respect to the SWPPP. If necessary,
the SWPPP representative will be required to make modifications to the SWPPP
to resolve construction problems or other obvious deficiencies associated with
the controls. Upon acceptance of the controls, the contractor shall be granted a
notice to proceed with construction. If the controls appear to be ineffective due
to site conditions, installation or improper design, modifications to the
installation or design will be required prior to granting a notice to proceed.
Proceed with Construction
While construction is underway, the following activities will be ongoing:
Intercept Sediment Flow
The control systems shall operate as designed, intercepting sediment flow for the
design flow without structural or operational failures for the design storm.
Surrounding areas of the site shall be inspected regularly by the operator to
determine evidence of soil loss from the site. If significant amounts of sediment
are detected outside of the controlled disturbed area, repair or redesign of the
erosion and sediment control system will be required along with cleanup of the
soil material outside of the controls.
The operator shall inspect and ensure that the systems are in good working
order on a week4y basis every fourteen calendar days and after each significant
rainfall ( >0.5 inches). Documentation of the inspections shall be a part of the
SWPPP. The SWPPP documents shall remain onsite or at a nearby location at all
times for review by the public. Any adjustments to the plan shall be documented
as part of the SWPPP within 72 hours of the __ _ dike �_ __ days of the inspection.
Implementation of SWPPP changes to BMPs shall be completed before the next
anticipated rainfall event or as soon as practicable. Local government inspectors
NCTCOG Construction BMP Manual 7-4 February 1993
Section 7
City Participation
should review these records periodically during normal site inspections.
Modify Controls as: Required
As construction. progresses, modifications may be required to the erosion control
systems due to phasing or changes in the disturbed areas of the site. These
modifications must be included in the original, approved SWPPP for the site.
If it is determined that the existing system is inadequate or modifications are
required due to construction, a modified SWPPP will be required within 7-2
l-oars -days of the notice to the contractor. The modified SWPPP will be subject to
the same review and approval procedures as the original. SWPPP.
Maintain Erosion Control Systems
As construction proceeds, maintenance of the erosion control systems becomes
critical to the proper operation of the controls. Maintenance requirements for
each of the controls is included in the BMP fact sheets. All systems should be
inspected regularly by the operator for integrity in addition to inspection after
significant storm events. The operator shall be responsible for maintaining the
erosion control systems to function as described in the SWPPP.
Stockpiles of erodible materials such as topsoil must be stabilized through
vegetative or structural means or stored onsite such that runoff from the
stockpile is treated prior to leaving the site. For example, a stockpile of topsoil
can be located outside of the construction area as long as the downstream side of
the stockpile utilizes silt fence to intercept silt off of the stockpile.
If, during the course of the project, construction activities are halted for a period
of 14 days (and no activity is planned for a total of 21 days), the operator shall
implement permanent stabilization on the site, or notify the city of measures to
be taken to prevent site erosion. During the 14 day period, all measures of the
SWPPP shall be maintained by the operator. Violations of
the maintenance of the temporary controls of final stabilization of the inactive
site may result in violations of either federal law or local ordinances.
Waste Collection and Disposal
During construction, waste management BMPs shall be maintained to minimize
trash and other construction wastes from leaving the site. This includes covered
waste containers which are emptied on a regular basis, watertight containers for
hazardous chemicals and other techniques listed in the waste management BMP
fact sheets.
Hazardous Chemical Management
If the project requires the use of hazardous chemicals such as fertilizers, paints,
or grease and oil, techniques listed in the Hazardous Waste BMP fact sheet
NCTCOG Construction BMP Manual 7 -5 February 1993
Section 7
City Participation
should be used and maintained during construction to minimize the potential
for spills or contamination of runoff or groundwater.
Operator Inspection
During construction, the operator is required to inspect the BMP systems
employed on the site and provide maintenance as necessary-on a weeldy basis
every fourteen calendar days_ . Written inspection reports become a part of the
SWPPP. The inspections are used to determine if the system is properly installed,
maintained and effective in the reduction of pollution. A sample form is
provided in Appendix C to simplify inspection reporting.
Permanently Stabilize Site
Upon completion of the project, the site shall be permanently stabilized in
accordance with the SWPPP and landscaping plans prior to removal of
temporary sediment control devices. In cases of unsuitable weather for
establishment of vegetation, erosion control matting, mulching, etc., can be used
to reduce erosion. In this context, stabilization shall be defined as a rrmtimurn 70
percent uniform density of vegetatiorr uniform perennial vet ;etative cover with a
density of 70% of the native background vegetative cover or other suitable
means of permanent stabilization such as gabions, pavement: or other armor type
covering.
Permanent Stabilization Inspection (Optional)
Upon completion of construction and the installation of permanent erosion
control methods, a final erosion control inspection may be performed as part of
acceptance of the project by the city or issuance of a certificate of occupancy for
the facility. In the event that the permanent erosion control is inadequate due to
improper design or installation, the permanent erosion control measures must be
corrected or redesigned to function properly.
Remove Temporary Stabilization
Upon acceptance of the permanent erosion control methods, the temporary
erosion control devices shall be removed by the contractor. If installation of the
permanent devices requires the removal of the temporary devices, approval of
the permanent controls shall be secured for each subbasin within one week of
removal of temporary controls. At no time shall an area be left unprotected by
either temporary or permanent controls for more than 2 weeks.
Submit Notice of Termination
A Notice of Termination (NOT) shall be submitted to the address belavd -on the
back of the NOT form upon completion of the final stabilization of the site.
NCTCOG Construction BMP Manual 7 -6 February 1993
Section 7
City Participation
..
WON 0
In the case of projects located in MS4 permitted cities, a copy of the NOT should
be sent to the local jurisdicition.
Completion of Project
Upon submission of the NOT, the operator states that the site is properly
stabilized and that the operator is no longer responsible for maintenance of the
permanent BMPs installed on the site.
Items in the flow chart which are marked as optional are issues addressed by the
local jurisdiction. The local jurisdiction should be contacted early to confirm
whether these steps Will be implemented as part of the project.
Enforcement of SWPPP
As stated above, the NPDES is a program administered and enforced by the
EPA. It is anticipated that local jurisdictions will take a role in enforcement as
the program matures through ordinances and inspection programs implemented
under the local MS4 permit requirements. At a minimum, file copies of site NOIs
and NOTs should be submitted to the local jurisdiction prior to construction to
notify of compliance with the NPDES requirements. The SWPPP is required to
be on site or at a nearby location and available to EPA and local jurisdiction
inspectors throughout construction.
The local jurisdiction has the option to report violations to the EPA or address
the issue on the local level.
NCTCOG Construction BMP Manual 7 -7 February 1993
STRAW BALE DIKE
GENERAL NOTES:
1. EACH BALE SHALL BE EMBEDDED IN THE SOIL A MINIMUM OF
FOUR INCHES.
2. BALES SHALL BE SECURELY ANCHORED IN PLACE BY 2" X 2"
WOOD STAKES DRIVEN THROUGH THE BALES. THE FIRST
STAKE IN EACH BALE SHALL BE ANGLED TOWARD THE
PREVIOUSLY LAID BALE TO FORCE THE BALES TOGETHER.
fVEERY "rwo WEEKS* OR AFTER Pic"
3. INSPECTION SHALL BE MADWE- E AND REPAIR OR �12
E ,�,-?- -I RA't
REPLACEMENT SHALL BE MADE PROMPTLY AS NEEDED BY THE
CONTRACTOR.
4. WHEN SILT REACHES A DEPTH OF 6 INCHES, IT SHALL BE
REMOVED AND DISPOSED OF IN AN APPROVED MANNER.
5. AFTER THE DEVELOPMENT OF THE SITE IS COMPLETELY
STABILIZED, THE BALES SHALL BE REMOVED AND DISPOSED
OF AT AN APPROVED SPOIL DISPOSAL SITE.
STRAW BALE DIKE Mart Caned Ttv Card N Dewnnmb S'ANOARD SPECIFICATION REFERENCE
02270A
6 „ DEC. -TE ST-DAW ORRAWW. NO,
C 92 2010 B
NCTCOG Construction BMP Manual 9.6 February 1993
SILT FENCE
GENERAL NOTES
1. STEEL POSTS WHICH SUPPORT THE SILT FENCE SHALL BE
INSTALLED ON A SLIGHT ANGLE TOWARD THE ANTICIPATED
RUNOFF SOURCE. POST MUST BE EMBEDDED A MINIMUM OF
ONE FOOT.
2. THE TOE OF THE SILT FENCE SHALL BE TRENCHED IN WITH A
SPADE OR MECHANICAL TRENCHER, SO THAT THE
DOWNSLOPE FACE OF THE TRENCH IS FLAT AND
PERPENDICULAR TO THE LINE OF FLOW. WHERE FENCE
CANNOT BE 'TRENCHED IN (e.g. PAVEMENT), WEIGHT FABRIC
FLAP WITH ROCK ON UPHILL SIDE TO PREVENT FLOW FROM
SEEPING UNDER FENCE.
3. THE TRENCH MUST BE A MINIMUM OF 6 INCHES DEEP AND 6
INCHES WIDE: TO ALLOW FOR THE SILT FENCE FABRIC TO BE
LAID IN THE GROUND AND BACKFILLED WITH COMPACTED
MATERIAL.
4. SILT FENCE SHOULD BE SECURELY FASTENED TO EACH
STEEL SUPPORT POST OR TO WOVEN WIRE, WHICH IS IN TURN
ATTACHED TO THE STEEL FENCE POST. THERE SHALL BE A 3
FOOT OVERLAP, SECURELY FASTENED WHERE ENDS OF
FABRIC MEET. EVERY -'Wo WEEKS
5. INSPECTION SHALL BE MADEy± AND AFTER EACH
RAINFALL. REPAIR OR REPLACEMENT SHALL BE MADE
PROMPTLY AS NEEDED.
6. SILT FENCE SHALL BE REMOVED WHEN THE SITE IS
COMPLETELY STABILIZED SO AS NOT TO BLOCK OR IMPEDE
STORM FLOW OR DRAINAGE.
7. ACCUMULATED SILT SHALL BE REMOVED WHEN IT REACHES A
DEPTH OF HALF THE HEIGHT OF THE FENCE. THE SILT SHALL
BE DISPOSED OF AT AN APPROVED SITE AND IN SUCH A
MANNER AS TO NOT CONTRIBUTE TO ADDITIONAL SILTATION.
SILT FENCE
",,, L_*, To , � d G ,_ STANDARD 9110 ATNIN RERENCE
EF
.A t.� � 022708
DATE �/� STANDSTANDARD D�RA N G NO.
EEC. 92 2020 B
NCTCOG Construction BMP Manual 9 -10 February 1993
DIVERSION DIKE
GENERAL NOTES
ALL DIKES SHALL BE PLACED IN 8" LIFTS OR LESS AND
COMPACTED TO 95% STANDARD PROCTOR DENSITY.
2. ALL DIVERSION DIKES SHALL HAVE POSITIVE DRAINAGE TO A
CONTROLLED OUTLET.
3. DIVERTED RUNOFF FROM A PROTECTED OR STABILIZED AREA
SHALL HAVE ITS OUTLET FLOW DIRECTED TO AN
UNDISTURBED STABILIZED AREA OR INTO A, LEVEL SPREADER
OR GRADE STABILIZATION STRUCTURE.
4. DIVERTED RUNOFF FROM A DISTURBED OR EXPOSED AREA
SHALL BE CONVEYED TO SEDIMENT TRAP SUCH AS A ROCK
BERM, TEMPORARY SEDIMENT TRAP OR SE= DIMENT BASIN OR
TO AN AREA PROTECTED BY ANY OF THESE MEASURES.
5. STABILIZATION IS REQUIRED WHEN VELOCITIES EXCEED 6 FEET
PER SECOND OR WHEN GRADES EXCEED 2.0 %. STABILIZATION
SHALL BE CRUSHED STONE PLACED IN A LAYER OF AT LEAST 3
INCHES THICKNESS OR HIGH VELOCITY EROSION CONTROL
MATTING. VEGETATION MAY BE USED FOR VELOCITIES LESS
THAN 6 FEET PER SECOND.
6. INSPECTION SHALL BE CONDUCTEDvftlls- OR AFTER EACH
RAINFALL EVENT.
40* C*44 T� Cood of
Co�errrnelV ST.M11 WED11CA1104 IETER0ICE
DM RSM DIKE =TOD
" DDArE STANDDAIARDDDRAWM NO.
■IGC. 92 L� �� B
NCTCOG Construction BMP Manual 9.18 February 1993
TRIANGULAR SEDIMENT FILTER DIKE
GENERAL NOTES:
1. DIKES SHALL BE PLACED IN A ROW WITH ENDS TIGHTLY
ABUTTING THE ADJACENT DIKE,
2. THE FABRIC COVER AND SKIRT SHALL BE A CONTINUOUS
EXTENSION OF THE FABRIC ON THE UPSTREAM FACE, AND
FABRIC SHALL BE OVERLAPPED A MINIMUM OF 12 ".
3. THE SKIRT SHALL BE WEIGHTED WITH A CONTINUOUS LAYER
OF TYPE 'A' RIP RAP, OR TOED -IN 6" WITH MECHANICALLY
COMPACTED MATERIAL. OTHERWISE, THE ENTIRE STRUCTURE
SHALL BE TRENCHED TO A DEPTH OF 4 INCHES.
4. DIKES AND SKIRT SHALL BE SECURELY ANCHORED IN PLACE
USING 6 INCH WIRE STAPLES ON 2 -FOOT CENTERS ON BOTH
EDGES AND SKIRTS.
5. FILTER MATERIAL SHALL BE LAPPED OVER ENDS 6" TO COVER
DIKE TO DIKE JOINTS. JOINTS SHALL BE FASTENED WITH
GALVANIZED SHOAT RINGS.
6. THE DIKE STRUCTURE SHALL BE 6 GA. 6" X 6" WIRE MESH, 18"
ON A SIDE.
f-vf-KY -rwo wf��KS <<
7. INSPECTION SHALL BE MADEV*i -E- tfti` OR AFTER EACH �Z
RAINFALL EVENT AND REPAIR OR REPLACEMENT SHALL BE
MADE PROMPTLY AS NEEDED BY THE CONTRACTOR.
8. ACCUMULATED SILT SHALL BE REMOVED WHEN IT REACHES
APPROXIMATELY ONE -HALF THE HEIGHT OF THE DIKE, AND
DISPOSED OF IN A MANNER WHICH WILL NOT CAUSE
ADDITIONAL SILTATION.
9. AFTER THE DEVELOPMENT OF THE SITE IS COMPLETELY
STABILIZED, THE DIKES AND ANY REMAINING SILT SHALL BE
REMOVED. `TILT SHALL BE DISPOSED OF AS INDICATED IN NO.
8 ABOVE.
WIN Cm" Tara Caw[ wl CowmRw to S:MO�RD SKCIFXArON q TERENCE
� ��
02270E _
FLTEIR DKE
Ov D�,f rmowO DRAUWG wD.
DEC. 92 2050 B
NCTCOG Construction BMP Manual 9 -22 February 1993
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pup juauulpas aq4 uleia -p 'space pa4oajo.tdun uzoq .ta4um uappl- wauzlpas
ROCK BERM
GENERAL NOTES:
1. USE ONLY OPEN GRADED ROCK 4 -8 INCHES IN DIAMETER FOR
STREAM FLOW CONDITION. USE OPEN GRADED ROCK 3 -5
INCHES IN DIAMETER FOR OTHER CONDITIONS.
2. THE ROCK BERM SHALL BE SECURED WITH A WOVEN WIRE
SHEATHING HAVING A MAXIMUM OPENING OF 1 INCH AND A
MINIMUM WARE SIZE OF 20 GAUGE AND SHALL BE BURIED IN A
TRENCH APPROXIMATELY 3 TO 4 INCHES DEEP.
f_v6_r'%t Two wFF-KS
3. THE ROCK 13ERM SHALL BE INSPECTEDW EK-L-Y OR AFTER
EACWAIN EVENT AND SHALL BE REPLACED WHEN THE
STRUCTURE CEASED TO FUNCTION AS INTENDED DUE TO SILT
ACCUMULATION AMONG THE ROCKS, WASHOUT,
CONSTRUCTION TRAFFIC DAMAGE, ETC.
4. WHEN SILT REACHES A DEPTH EQUAL TO ONE -THIRD OF THE
HEIGHT OF THE BERM OR ONE FOOT, WHICHEVER IS LESS, THE
SILT SHALL BE REMOVED AND DISPOSED OF PROPERLY.
5. WHEN THE SITE IS COMPLETELY STABILIZED, THE BERM AND
ACCUMULATED SILT SHALL BE REMOVED AND DISPOSED OF IN
AN APPROVED MANNER.
6. ROCK BERM SHOULD BE USED AS CHECK DAMS FOR
CONCENTRATED FLOW AND ARE NOT INTENDED FOR USE IN
PERIMETER PROTECTION.
ROCK; BERM
North Cq+W To Ca "I of Goomnwb
STANDARD 91EdF1CAMN REFERENCE
02270F
DATE STANDARD DRANo.
[Mc. 92 20601
NCTCOG Construction BMP Manual 9 -26 February 1993
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-uoilleliis Iuuoilippu of aingiiluoa lou IIiM letll iauuuuz u ut alts pano.iddu
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suogaadstn Iuuoilippd -uoilaadsui .Sui inp papaau su paauldai io padttlsal
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SAND BAG BERM
GENERAL NOTES:
1. WHEN A SANDBAG IS FILLED WITH MATERIAL, THE OPEN END
OF THE SANDBAG SHOULD BE STAPLED OR TIED WITH NYLON
OR POLY CORD.
2. SANDBAGS SHOULD BE STACKED IN AT LEAST THREE ROWS
ABUTTING EACH OTHER, AND IN STAGGERED ARRANGEMENT.
3. THE BASE OF THE BERM SHOULD HAVE AT LEAST 3
SANDBAGS. THESE CAN BE REDUCED TO 2 AND 1 BAG IN THE
SECOND AND, THIRD ROWS RESPECTIVELY.
4. FOR EACH ADDITIONAL 6" OF HEIGHT, AN ADDITIONAL SANDBAG
MUST BE ADDED TO EACH ROW WIDTH. TWa was ANA
5. THE SANDBAG BERM SHALL BE INSPECTED AFTER EACH'RAIN
EVENT AND SHALL BE RESHAPED OR REPLACED AS NEEDED
DURING INSPECTION. REPAIRS SHALL BE MADE FOR WASHOUT,
CONSTRUCTION TRAFFIC DAMAGE, ETC.
6. WHEN SILT REACHES A DEPTH EQUAL TO 6 INCHES (THE
HEIGHT OF ONE SANDBAG), THE SILT SHALL BE REMOVED AND
DISPOSED OF IN A APPROVED SITE AND IN SUCH A MANNER AS
TO NOT CREATE A SILTATION PROBLEM.
7. WHEN THE SITE IS COMPLETELY STABILIZED, THE BERM AND
ACCUMULATED SEDIMENT SHALL BE REMOVED AND
DISPOSED OF IN AN APPROVED MANNER.
SAND BAG BERM
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NCTCOG Construction BMP Manual 9 -34 February 1993
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3.1 EROSION CONTROL MATTING
A. Prior to the installation of any erosion control matting, all rocks, dirt clods,
stumps, roots, trash and any other obstructions which would prevent the
mat from lying in direct contact with the soil shall be removed. Anchor
trenching shall be located along the entire perimeter of the installation
area. These trenches shall be 6 inches deep and 6 inches wide and the
matting shall be laid into the trench then backfilled with compacted soil or
gravel. Matting shall be fastened to the ground using 10 gauge wire staples
6 inches in length and 1 inch in width with a coverage rate of one staple
per 4 square feet minimum. Installations shall be in accordance with
manufacturers recommended guidelines with the exception of the
minimum criteria stated herein. Cvc�v�
B. Maintenance: Matted areas must be inspectedy� basis, and after
each WSW t rainfall event to locate bare spots caused by weather or
other events. :Missing or loosened matting must be promptly replaced or
re- anchored.
PART 4 - MEASUREMENT AND BASIS OF PAYMENT
4.1 MEASUREMENT
A. Measurement of erosion control matting will be made by the square yard
of material installed, in place and ready for use as an erosion control
surface treatment.
4.2 BASIS OF PAYMENT
A. Erosion control matting, measured as herein specified, will be paid for at
the unit price bid per square yard, which payment shall include furnishing
all materials, labor, and equipment necessary to provide a complete and
finished installation as specified.
END OF SECTION
NCTCOG Construction BMP Manual 9 -58 February 1993
D. Bark chips are popular for ornamental applications as they do not require
anchoring, do not decompose very rapidly and serve as an excellent
insulation material. When using bark chips, it is not necessary to treat for
nitrogen deficiency or to fertilize.
E. Other types of organic mulches are available but usually are very seasonal
and may have a limited availability.
2.2 MATTING AND GEOTEXTILES
A. Many geotextile materials are very beneficial when used in conjunction
with other mulching agents. See Specification 02270.N - EROSION
CONTROL MATTING for more information.
3.1 ORGANIC MULCH
A. Prior to the placement of any mulch, the area to be protected must be
graded completely in accordance with plans. Fertilization and soil
treatment should then be done prior to placement of mulch with the
exceptions of when seed is to be applied by means of hydro -seed or when
seed is distributed following straw mulch spreading during winter
months. Organic mulches may be distributed by hand or my mechanical
means, but to be effective a complete covering is required. Straw and hay
mulches should be distributed at the rate of 75 to, 90 pounds per 1000 feet of
treated area. To be fully effective, straw mulch must be anchored by
means of application of a fiber mulch binder, the application of a synthetic
liquid mulch binder or by using a tractor -drawn crimper to punch mulch
into the soil.
3.2 MAINTENANCE `/y eery �{ wa wc4G S
A. Maintenance: All mulchi g materials should be inspected y�- it weel4y
mss; and after each rainfall event to locate areas of erosion.
Where erosion has occurred, additional mulch must be applied or an
alternative method should be considered. Missing or loosened matting
must be promptly replaced or re- anchored.
' 13 i
4.1 MEASUREMENT
A. Measurement of organic mulches will be made by the square yard of
treated area, in place and ready for use as an erosion control surface
treatment.
NCTCOG Construction BMP Manual 9 -62 February 1993
at
Appendix A
Design Procedure for Temporary
Sediment Basins
The following design procedure provides a step -by -step method for the design
of a temporary sediment basin with a dam of less than 6 feet. The data sheet
found in the back of this Appendix should be used in the erosion and sediment
control plan to outline design values calculated.
I. Basin Volume
A. Determine the required basin volume. The basin capacity of the
basin must be either the calculated volume of runoff from a 2 -year,
24 -hour storm per disturbed acre or at4east 134 cubic yards per
acre of total contributing drainage area, half of which should be in
the form of a permanent pool or wet storage, and the remaining
half as a. "drawdown" area or dry storage. For soils with very low
permeability in which calculated drawdowns are greater than 48
hours, the wet storage should be eliminated and dry storage equal
to 134 e ither of the aforementioned
volumes should be provided.
For a natural basin, the wet storage volume may be
approximated as follows:
V,= 0.4xA,xD,
where,
V, = the wet storage volume in cubic feet
A, = the surface area of the flooded area at the
invert of the dewatering outlet, in square
feet
D, = the maximum depth in feet, measured from
the low point in the basin to the invert of
the dewatering outlet
2. For a natural basin, the dry storage volume may be
approximated as follows:
VZ = (fl + A2 ) x DZ
NCTCOG Construction BMP Manual A -1 February 1993