The National Pollutant Discharge Elimination System (NPDES) is a Federal program intended to control water pollution by regulating point sources that discharge pollutants into waters of the United States. Point sources are discrete conveyances such as pipes or man-made ditches.
The San Francisco Bay Regional Water Quality Control Board oversees the program in the Bay Area. It does so by regulating discharge through a variety of permits. These include the Municipal Regional Permit and the statewide Construction General Permit.
Municipal Regional Stormwater Permit
The Bay Area's Municipal Regional Stormwater Permit regulates the design and maintenance of projects that create or replace impervious area.
Section C.3.i of the permit requires all development projects, which create and/or replace between 2,500 and 10,000 sq ft of impervious surface, and detached single family home projects (that are not part of a larger development plan) which create and/or replace 2.500 sq ft or more of impervious surface, to install one or more of the following site measures:
- Direct roof runoff into cisterns or rain barrels for reuse.
- Direct roof runoff onto vegetated areas.
- Direct runoff from sidewalks, walkways, and/or patios onto vegetated areas.
- Direct runoff from driveways, or uncovered parking lots onto vegetated areas.
- Construct sidewalks, walkways, and/or patios with permeable surfaces.
- Construct bike lanes, driveways, and/or uncover parking lots with permeable surfaces.
Section C.3b requires projects that create and/or replace 10,000-square-feet or more of impervious surface area (with limited exceptions) to incorporate the following stormwater controls:
- site design measures
- source control measures, and
- stormwater treatment measures.
C.3 also requires projects that create and/or replace one acre or more of impervious surface area and increase impervious area over the pre-project condition need to incorporate hydromodification management measures, if the project is located in an area susceptible to hydromodification.
Construction General Permit
With few exceptions, California's Construction General Permit prohibits construction that will result in a land disturbance of one acre or more, without first having an approved site-specific Storm Water Pollution Prevention Plan (SWPPP).
The level of effort and cost associated with developing and implementing a custom SWPPP is dependent upon the scope of the project and its General Permit category.
A construction project is categorized by the General Permit as either a traditional project or a linear underground/overhead (utility) project (LUP).
Both categories are further subdivided by three. The subcategories for traditional projects are identified as risk level. For LUPs, they are identified by type. Risk Level 1/Type 1 projects have the least amount of requirements, where as Risk Level 3/Type 3 projects have the most.
Alaco can assist clients with the risk assessment of site's potential to generate sediment and the threat posed to receiving waters and to plan for the control of all pollutants and their sources. However, Alaco does not currently offer oversight services (inspections, water testing, reporting).
Water Pollution Control Plans (WPCC) Preparation
When a project is not subject to the General Permit, some entities or project owners may still require at least a minimal plan to guard against water pollution. Such is the case with Caltrans, which requires a Water Pollution Control Plan (WPCP) for projects under one acre.
Alaco can assist government agencies, businesses, and private property owners with their need to comply with NPDES requirements by developing and overseeing the implementation of appropriate Stormwater Pollution Prevention Plans (SWPPPs) and Best Management Practices (BMPs).
For additional information regarding Bay Area NPDES matters, visit the websites of these local programs: