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Is Your Stormwater Management Program Worth Its Salt?

Winter is here. While you likely have prepared your HVAC systems, vehicles, and equipment for winter, how about your stormwater management program?

Winter presents some challenges for stormwater management. You may be familiar with snow and ice, but what about salt?

The 2015 Federal Multi-Sector General Permit (MSGP) and many state stormwater permits have specific requirements for salt storage piles or piles containing salt (e.g., sand/salt mixtures) for deicing, or for other commercial or industrial purposes, including maintenance of paved surfaces. Even if a stormwater permit does not specifically mention salt, salt is likely considered a “significant material” (or similar phrase). A significant material is defined by its potential to degrade or impair the quality of a facility’s receiving water. In this case, bulk quantities of salt (including sand/salt or other salt mixtures) would qualify as a significant material. Either way, explicitly by “salt” or implicitly by “significant material,” your stormwater permit includes requirements for salt storage piles.

For instance, the 2015 MSGP requires enclosing or covering piles of deicing salt to minimize the discharge of salt via stormwater runoff. Berms may be used to enclose or surround piles. Pile cover may be permanent or achieved via use of tarps as necessary. It is good practice to place salt piles on an impervious surface. Appropriate measures (e.g., good housekeeping, containment) must be taken to minimize salt exposure to stormwater while adding it to or removing it from piles. State permits may have the same or similar requirements for salt storage piles. Check your permit. There is an exception to these requirements if stormwater runoff from the pile is not discharged or if you have another permit for stormwater discharges from salt storage piles. Some state stormwater permits also provide an exception if these discharges are routed to a proper collection and treatment system (not a stormwater sewer).

You need to document information about your salt storage piles and related structures and procedures in your Stormwater Pollution Prevention Plan (SWPPP), including their locations on the site map. This includes identification of salt piles by type and quantity; a description of structures that enclose or cover piles or prevent stormwater runoff from piles; any procedures for covering salt piles with tarps; and measures to minimize pile exposure during addition or removal of salt.

While you have permit requirements for salt storage and handling, you also have opportunities to control your use of salt. Better control of salt use may make complying with these permit requirements easier (e.g., less salt to store, add, or remove) and also provide operational and cost-savings benefits. The first opportunity is to avoid applying too much salt, especially in low-traffic areas and straight, level areas; however, you may need higher application rates for intersections, grades, and high-traffic areas. Monitor the weather for the timing and conditions of expected storms to reduce the need for applying salt. Check your salting equipment to ensure that it is distributing the correct quantity of salt (high or low) and closely monitor your salt usage.

Salt is important and necessary for operating safely in winter, but it is also relevant to stormwater management. It is worth reviewing your stormwater permit to ensure that your SWPPP and procedures are current for salt storage piles. ISRI has members-only stormwater resources that cover most aspects of stormwater management. Please consult those. If you have questions on stormwater, or anything environmental, please contact ISRI Chief Scientist/Director of Environmental Management David Wagger at (202) 662-8533.

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