Winter presents some challenges for stormwater management. You may be familiar with snow and ice, but what about salt?
The 2021 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) that may be used for deicing or other purposes. Even if a stormwater permit does not specifically mention salt, such a pile (even if a salt substitute) is likely considered a “significant material” (or similar phrase) because of its potential to degrade or impair surface waters.
For instance, Section 184.108.40.206 of the 2021 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. Piles may be covered permanently or temporarily as needed (e.g., using tarps). It is good practice to place salt piles on an impervious surface. Appropriate measures (e.g., good housekeeping, containment) must be taken to minimize exposure of salt to stormwater while adding or removing it from piles. State permits may have the same or similar requirements for salt storage piles. Check your permit.
Your Stormwater Pollution Prevention Plan (SWPPP) must contain detailed information about your salt storage piles and related structures and procedures and include their locations on your SWPPP’s site map.
At the same time, better control of salt use may make permit compliance easier (e.g., less salt to store, add, or remove) as well as provide operational and cost-savings benefits. For instance, avoid applying too much salt, especially in low-traffic areas and straight, level areas; however, higher application rates may be needed 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 your salt storage piles.
If you have questions on stormwater, please contact David Wagger, ISRI’s Chief Scientist / Director of Environmental Management, at (202) 662-8533. ISRI also has stormwater resources available on-line here.