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Material Storage and Handling

How you store and handle materials on your site can significantly impact your stormwater compliance. The key to proper material storage and handling is to prevent interactions between materials and your stormwater as much as possible. Dust from bag houses, fluids from maintenance areas, and exposed raw materials can all contribute pollutants to your stormwater and lead to costly cleanups and benchmark exceedances. This article will provide tips to improve your materials storage and handling practices.

Store inside or under cover

When storing materials on your site, you will want to store as many things inside as possible. Storing inside prevents the possibility of stormwater coming into contact with that material and causing pollution issues. Indoor storage can come at a premium, so the next best option is to cover your materials if stored outside. Not all coverings are created the same. A simple plastic tarp can be effective in some scenarios but is much more prone to rips, tears, and insufficient anchoring. Strong winds or heavy rainfall can easily render a tarp ineffective so they should be limited to temporary applications. Dedicated roof structures or proprietary plastic containers tend to be much more reliable outdoor storage systems. Many of the proprietary storage containers, such as those for drum or tote storage, have built-in secondary containers that capture spilled material, as well as locking mechanisms that help prevent vandalism or theft.

Secondary Containment

Secondary containment is a vital tool for material storage and handling. For some materials such as oil or petroleum, it is more than just a good idea, it is a permit requirement. There are several forms of secondary containment available ranging from simple pans to high-tech double-walled tanks with built-in leak detection.  Whatever type you use, you should ensure that they are appropriately sized are unable to be inundated with stormwater.

Determining the size of your secondary container: The ISGP states that your containment should be “be capable of containing 10% of the total enclosed tank volume or 110% of the volume contained in the largest tank, whichever is greater..”  here are a couple of examples of what this means.

Secondary containment volume calculations

Example 1: Containing a single 275-gallon IBC tote

10% of total enclosed tank volume: 0.1×275 gal.= 27.5 gal.

110% of the largest tank: 1.1×275 gal= 302.5 gallons

Whichever is greater: 302.5 gallon > 27.5 gallon, so the containment should hold at least 302.5 gallons.

Example 2: Containing 4 55-gallon drums:

10% of total enclosed tank volume: Total volume 4×55 gal. = 220 gal. 10% of total volume= 0.1×220= 22 gallon

110% of the largest tank: largest tank= 55 gal. 1.1×55 gal. = 60.5 gal.

Whichever is greater: 60.5 gal > 22 gal., so the containment should hold at least 60.5 gal.

Example 3: Containing 2 55-gallon drums:

10% of total enclosed tank volume: Total volume 2×55 gal. =110 gal. 10% of total volume= 0.1×110= 11 gallon

110% of the largest tank: largest tank= 55 gal. 1.1×55 gal. = 60.5 gal.

Whichever is greater: 60.5 gal > 11 gal., so the containment should hold at least 60.5 gal.

Dikes, Berms, and Curbs

Dikes, Berms and Curbs are also effective ways of minimizing the impacts of spilled materials. When properly installed on impervious surfaces, these effectively act as a secondary container, limiting the spread of spilled material. If Dikes or Berms are used for spill containment, the same secondary containment volume calculations need to be made as well coverings or other methods that prevent the inundation of stormwater.

Berms and Curbs are also a good solution to prevent stormwater from running on into a material storage area. This reduces the potential stormwater interaction and greatly reduces the volume of water that can be impacted.

Spill Kits

Spill kits should be located near all fueling areas and oil storage areas. You will want to fill your spill kit with the right adsorbent type for the materials and conditions found at your site. If you store and utilize lots of petroleum products, you should include oil-specific adsorbents. Water-soluble material storage may call for you to include more all-purpose adsorbents. These spill kits must be well stocked and easy to find for a quick response to a spill in your material storage area.

Read our dedicated spill kit article to learn more.

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