What does Non-Exposure mean under an NPDES stormwater permit?

Depending on the state your located in, and if your operation is located entirely within an enclosed facility, you may or may not need a stormwater permit. Confusing, right? It's called non-exposure, and we discuss factors which may impact the need for your operation to get a stormwater permit.

Lately we've been doing some interesting stormwater work, which spurred me to write this. We've been working with organizations that have an operation that's either mostly, or completely indoors. I'm talking about facilities with things like machinery, stockpiles, raw materials, and finished goods that are kept almost entirely inside a building. The owners of these facilities raise a great question:

"If we don't have anything outside, exposed to stormwater, do we still need and NPDES stormwater permit?"

Clients are asking about stormwater non-exposure, and it's a great question. Know this answer and you can save yourself time, money, aggravation, and liability. Get it wrong and you'll have the stormwater regulation book thrown at you. However, the concept of non-exposure as relating to stormwater permits can be tricky.

Let's look back at what an NPDES permit is. NPDES stormwater permits were designed to reduce the amount of pollution in stormwater runoff. The goal is to cut down on chemicals, oils, sediments, trash, and other things getting into our nation's waterways. These NPDES permits were crafted specifically for industrial facilities, seeing as they usually were contributing the most amount of pollution.

So what this means is if you have things outside that could contribute to polluting stormwater, then you need an NPDES permit that regulates pollutant discharge; otherwise known as an NPDES stormwater permit. Makes sense, right?

What if you don’t have any materials at your site that could contribute pollutants to stormwater runoff? Do you still need a permit?

The answer is yes and no.

Really look at your facility. Can you say that your operation has nothing outside? No machinery, no spills or leaks from equipment, no raw materials?

In some cases the answer is no. There is absolutely nothing stored outdoors. I’ve seen this many times at industrial facilities which are completely, totally enclosed indoors, like in an old factory or warehouse. Everything is indoors, including raw materials, manufacturing processes, and finished materials. There is literally nothing stored outdoors exposed to rainfall that could contribute pollutants to stormwater.

So what to do then? Many states and the Federal government have addressed this situation by offering a regulatory option for this type of facility – a “non-exposure certification”. This isn’t a permit, but a means of officially declaring that there is nothing that could contribute to pollution through stormwater at your facility. In many states you register via an NPDES non-exposure certification, and there’s no permit needed. It's literally as simple as that!

But expect to be inspected, to confirm your non-exposure condition. If you’re right, you’re one of the lucky ones. If you’re wrong, you’ll need to get NPDES stormwater permit coverage. This isn’t cheating the system, but does provide a mechanism for those that the permitting program doesn’t really address.

Interested? First, take a real look at your facility. What is outdoors, or exposed to rainfall? If nothing, you’re halfway there. The next step is to check with your NPDES delegated state permitting agency to confirm if they have a non-exposure certification available (most, but not all do). If they do, you can use this to avoid a permit that might otherwise not seem to make too much sense for you.

And, since you really have no chance to contribute pollutants to stormwater, not only do you win, but our nation’s waterways win as well. If you're in need of help with understanding or getting the most out of your permit, click here to contact us or give us a call at 609-693-8301 to discuss your stormwater needs today.