The same operation that causes knowable erosive or other pollutant release prevention concerns within the discharge of stormwater (NPSDES Permit) from construction projects may require very different approaches based on time of year (spring, summer, fall, winter). Most SWPPPs do not differentiate between seasons of general industry practice or are silent during snow accumulated months. Even well known sediment control and erosion prevention BMPs require different approaches to select, install, inspect and maintain in sloppy wet (spring), or frozen soils (winter).Inaccurate and incomplete SWPPPs that fail to address seasons of work can be amended, and will be discussed. But it starts with accurate SWPPPs. Work that is known to occur in winter must have appropriate SWPPP non-structural and structural items. BMPs that normally require (for example) trenching, anchoring, or pinning may not be feasible, even though there may be no regulatory variance for avoiding downgradient perimeters or stabilizing exposed soil. Detection and response of potential discharges on frozen, snow covered soils is different than warm months. Note that when winter is ending, the accumulated water equivalent may equal a 5 month rain event discharging in 2 weeks. All-season SWPPP document development will be discussed. States that experience winter snow covers and below zero temperatures no longer have the luxury of suspending work. The cost to the public or developers of delayed roads, bridges and other projects is too great. NPDES project inspection frequency may change due to seasons and during periods of work suspension. However, if construction is occurring anywhere within the defined SWPPP project limits, inspections must still occur within a defined timeframe (Minnesota is once every 7 days). The discussion will include performing an example class inspection based on seasons and what SWPPP items to focus attention (e.g. snow and spill management for winter; spring floods).
Learning Objectives:
Understand how differing seasons affect SWPPP implementation and inspection
Incorporate seasonality into the project SWPPP
Recognize proper seasonal corrective actions for non-compliant BMPs