The application of risk analysis and the implementation of risk-management principles provide those responsible for design and construction of projects a method to make better informed decisions about what practices most appropriately fit into their storm water pollution prevention plans (SWPPP). Risk analysis can provide the information necessary to supplement and support the decision-making process. Risk-analysis and risk-management principles are frequently applied to processes such as: timing of construction; budgeting and estimating; quality assurance/quality control; comparing alternate techniques; selection of appropriate practices; and critical resource protection measurements. Risk analysis can be applied to most projects from small to very large. However, the benefits of risk analysis are more apparent on complex projects and those projects that are near critical resources.
Included in the project are type and location of critical resources, soils, weather, amount of grading, slopes, ditch gradients, and scheduling and staging. Information about area conditions and past projects is used in the risk analysis to design and/or select necessary protection for proposed projects and adjacent resources. For example, information from the state of Washington indicated that when there were erosion- and sediment-control problems on its projects, there was damage on site approximately 90% of the time, there were water quality issues 60% of the time and there was offsite damage approximately 40% of the time. Application of risk-analysis principles would indicate that protection for these projects needs to be comprehensive. In addition, conservative design practices that have less risk of failure can be determined and provided for proper protection of all the resources.
Risk analysis can be used to determine the type of protection practices that one might select for proper site protection. For example, in Minnesota, a properly installed silt fence can provide site protection for an approximate two-year, 24-hour storm event. Using risk analysis, the probability of one or more failures during any project duration of one construction season is 50%. In this same case, the probability of one or more failures over a two-year construction project is 75%, whereas the probability of a practice that provides a 10-year design storm protection to be successful is 90% over a one-year period and 80% over a two-year period.
Risk analysis, combined with proper budget analysis and best management practice (BMP) investment strategies, provides the owner, designer, project manager and contractor the ultimate tools to make sound decisions. For example, one would not want to invest in high-priced practices that have a high risk of failure. Risk analysis, combined with business decision strategies, will ensure that one is getting the most for his or her money. The combination of risk and investment strategies also provides the designer more detailed information on the budget requirements necessary to protect the site. Budgeting can be based on site requirements and the investments needed to reduce the risk of potential damage to critical resources.
When utilizing risk analyses and business investment principles in decision-making processes for designing and implementing SWPPPs for projects, the goal is ultimately coming up with the most correct decision, not the quickest.
