Project Risk Level Determination Guidance

Caltrans Stand-Alone Risk Level Determination Guidance

Caltrans has stand-alone guidance for assessing risk required by the new Construction General Permit (CGP) (State Water Board Order 2009-0009-DWQ) that went into effect on July 1, 2010. The CGP is a risk-based permit that establishes three levels of environmental risk possible for a construction site. 

The Risk Level (RL) is calculated in two parts:  (1) Project Sediment Risk, and (2) Receiving Water Risk. Caltrans Project Engineers and Consultants should use this guidance to determine if a project has a Risk Level 1, 2 or 3. The CGP Risk Level (RL) determination quantifies sediment and receiving water characteristics and uses these results to determine the project’s overall RL. Highly erodible soils, in higher rainfall areas, on steep slopes increase the ‘sediment risk’.

Monitoring and reporting requirements increase as the RL goes from 1 to 3.

Topography Tool

The Topograhpy Tool will assist Caltrans staff in developing a weighted average, by area, for slopes as required for the Construction General Permit's Risk Level Determination, Individual Method. For any given cross section, there will be one or more existing hillside slopes within the disturbed soil area limits of the planned work. For each of these existing slopes, the designer will provide the horizontal slope length (feet) and vertical rise (feet). For each slope, called segments, this Excel Worksheet will use these inputs to calculate slope steepness in percent and return a RUSLE 'LS Value' using the "LS values for Construction Slopes" table from page 7 of Appendix 1 of the Construction General Permit. For each cross section, a weighted average for LS is returned based upon slope length dominance (e.g., the longer slopes will dominate the average). Finally, a composite LS for the entire alignment is returned as a simple average of all cross sections.

Risk Level Determination Webinar

A two-hour webinar was presented on December 7, 2010 focused on Caltrans’ guidance for determining project risk level.  The presentation covered both GIS and Individual Methods as they apply to Caltrans projects.  A question and answer session followed the presentation.


FAQs have been compiled into a single document.  This includes questions on determining risk level received while developing the guidance and during the webinar’s question and answer session.