What kinds of linear projects are required to obtain coverage
under the General Construction Storm Water Permit?
Projects disturbing one or more acres of land
by any type of construction activity must file a Notice
of Intent (NOI), to comply with the Construction Storm
Water Permit regardless of what proportion is in one
or more Regional Water Quality Control Board jurisdictions,
or how the project is phased.
How should "total area to be disturbed" on the NOI form
be calculated for linear construction activity?
All disturbances to the ground must be accounted
for and considered additive. The following formula
attempts to account for all disturbances from the
construction activity, not just the trenching activity
itself:
[Width of
disturbance (including trench width) + Immediate
access width]
* Length of Projector
pipe diameter
+ Areas where project-related activity (such
as equipment and material storage) occur
+ (Bore hole diameter + Immediate access width) * number of bore holes
= Total area to be disturbed
This formula illustrates how to account for all disturbances
to the ground resulting from the construction activity. Although dischargers are not required to use
this exact formula, they must include all disturbances
to the ground in their total calculation.
Since
linear construction activities can transverse or enter
into different Regional Boards jurisdictions, how
many NOIs must be filed?
Regardless of the project scheduling, a separate NOI and fee
must be filed for each Regional Board area involved
prior to the commencement of construction activities.
Can
a Notice of Termination (NOT) be filed once the project
or a portion of a project is completed?
Regardless of project scheduling, a separate Notice of Termination
for each Regional Board area should be filed subsequent
to the completion of construction activities, and
the stabilization of all disturbed areas.
What
are the fees for filing a NOI for the General Construction
Storm Water Permit for linear construction projects?
The current fee is based on total size of the
construction project in acres. See
Construction fees for a list of fees by acres.
Since
linear construction projects usually encompass a
very large area, how should we determine the site
address on the NOI form?
When filling out the NOI form, replace the site address
with the phrase "linear construction project".
How
do you define property owner for a linear project?
For purposes of linear projects, where the owner
of the actual cable, pipeline, etc., and infrastructure
associated with the installation and operation of
the cable or pipeline are different than the owner
of the properties across which the project will
be installed, you need not list the property owners
on the NOI.
Is
the General Construction Storm Water Permit the only
permit that linear construction projects must apply
for?
Be
aware that there may be other permits or requirements.
Examples include streambed alteration agreements with
the Department of Fish and Game, Water Quality Certification
pursuant to Section 401 of the Clean Water Act administered
by the State and Regional Boards, and/or Clean Water
Act Section 404 permits administered by the U.S. Army
Corps. of Engineers. Under some circumstances, you
may also be required to obtain an exemption from a
Basin Plan prohibition. This generally requires a
resolution from the appropriate Regional Board.
The
permit requires that "runoff from off-site areas
should be prevented from flowing through areas that
have been disturbed by construction unless appropriate
conveyance systems are in-place." Preventing runoff from off-site areas seems
beyond the scope of the permit.
Not anticipating run-on emanating from off-site
areas during rainstorms has proven disastrous for
some corridor construction projects in previous
winters. Transecting
a drainage or low spot during the rainy season without
proper diversions, conveyances, or protection of
disturbed ground constitutes unrealistic planning,
and could contribute to a discharge of sediment
or other wastes. SWPPP design strategies to protect water
quality in these circumstances are very much in
keeping with the intent of the permit.
The
permit requires construction projects to show all
calculations for anticipated storm water run-on. A storm water run-on assessment and calculation will be difficult
and costly, especially for linear construction projects,
without any significant benefit. How should linear construction projects comply
with this type of permit requirement?
Estimating runoff, run-on, and soil loss is an important
first step in the design of an effective program. A simple calculation of Qpeak using the Rational
Method, for example, to size a temporary culvert,
earthen diversion structure, or to size outlet protection
would be considered adequate. For linear projects, it may also be appropriate
to perform and present standard calculations, which
could be applied in similar field situations throughout
the project. In this case, only a few calculations would
need to be performed and applied in the field, based
on a common sense approach. The benefits include
permit compliance, project integrity, protection
of water quality, and the prevention of costly damage
from erosion and flooding. The appropriate Regional
Board should be contacted during SWPPP design to
determine specific concerns or requirements.
What
are the criteria for post-construction storm water
BMPs as they relate to linear construction projects?
Post-construction BMPs address water quality concerns
which occur after project completion due to the
activity or structure put in place. For construction activity which does not
result in a structure or major alteration of the
topography, the appropriate post-construction BMP
would be stabilization of the disturbed area. For construction resulting in the installation
of structures, impervious surfaces, or soil compaction,
the appropriate post-construction BMPs may include
detention, velocity dissipation, off-site channel
enlargement, check dams, or other applications which
reduce net loading of sediment or polluted runoff
to water bodies.
How
do we obtain the runoff coefficient for before and
after construction of a linear project, and how
do we calculate the percent of impervious area before
and after construction?
There are many published sources for the
values of the runoff coefficient, C. Useful and
comprehensive examples can be found in: Handbook
of Applied Hydrology; A Compendium of Water Resources
Technology by Ven Te Chow, Editor in Chief, 1964;
the Erosion and Sediment Control by Steven J. Goldman,
et al. 1996; and the ABAG Manual of Standards for
Erosion and Sediment Control, May 1995 (Table 2
page 4.4)Some judgment is required to select the appropriate C value within
the ranges presented in the published tables. In general, for pervious surfaces, large areas with permeable
soils, flat slopes, and dense vegetation should
have the lowest C values. Small areas with dense soils, impervious
surfaces, moderate to steep slopes, and sparse vegetation
should be assigned the highest C values (1986. Goldman,
Steven J. et al.
The calculation of percent of site imperviousness
as required on the NOI form involves a simple areal
estimation of how much the ground has been covered
by impervious surfaces (including rooftops) after
construction is complete. If no permanent structures, roadways, pads,
etc. have been installed, and if all disturbed ground
has been restored to the original pre-construction
vegetation density, then the before and after construction
values would be the same.
If you have other questions concerning how
to comply with the General Permit, you may contact
the State Water Resources Control Board, Storm Water
Section at (916) 341-5537 or send an email question
to: stormwater@waterboards.ca.gov.
