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Storm Water Program
Linear Construction - Frequently Asked Questions
- 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.
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.
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.
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.
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".
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.
the General Construction Storm Water Permit the only
permit that linear construction projects must apply
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.
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.
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.
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.
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: email@example.com.