We discuss the reasons so many organizations end up with bad stormwater samples, or failing stormwater test results.
We do stormwater work all over the United States, and one common element we run into are facilities getting bad stormwater samples. NPDES stormwater permits often require that stormwater discharges be sampled, and that the results be compared to benchmarks or limits in the permit. Yet far too regularly, facilities get poor results, which are often very difficult to diagnose the cause of the bad results.
Now here's a situation I truly wish I had a dollar for every time I hear about it. Someone who holds an NPDES stormwater discharge permit calls us, and they want to discuss the bad sample results they got. They've been doing their BMPs, keeping their site neat and clean, updating their SWPPP, yet they still are getting bad sample results. They all want to know why are our stormwater samples so bad? Why are our stormwater results failing?
Could it possibly be due to bad sampling? Bad technique? Dirty equipment? Untrained personnel? The answer is usually easier to figure out than you think!
Why is my stormwater sample failing?
Let's take a look:
1 - The person doing the stormwater sampling is untrained or not properly trained
Does the sampler have any idea what they are doing? Where to sample? When to sample? What is the right way, and what is the wrong way? I cannot stress enough that the number one problem is untrained staff. Get your employees stormwater training! And not by someone equally untrained or someone who kind of gets it. Hire an expert! Ante up, and get some real training.
2 - Your stormwater sampling location stinks.
This normally isn't your staff's fault, but the fault of whoever prepared or oversaw the implementation of your stormwater permit or SWPPP. You can't get a good sample at a lousy location, end of story. So help yourself! You have two choices: either fix up your outfall, or have your site re-evaluated. A professional could let you know if your outfall location is any good or not. Or, a professional could provide you some pointers to help clean up your outfall. Either way, you have options.
3 - Your stormwater samples are being taken in the wrong location.
I see this all the time! Ask your stormwater sampler where they are taking a sample. I will bet you, chances are, they'll mumble something like "wherever I can" or "from a puddle" or something equally incorrect. You are only supposed to sample at your designated, identified, and possibly augmented outfall location. If you're not sure where that is, get some help. Identify that outfall. Take a picture of it, put up a sign, conduct some simple training, do whatever you have to do to make sure your employees know the right location to sample at!
4 - You have no idea how your stormwater outfall looks.
I'm not talking about where it is, I'm referring to a regular inspection. Go outside, check your outfall, and take note of the condition of it. Is it dirty? Is there trash? If it's a dry day, is there water leaving the site (that's process water and you can't be doing that so you have a whole other set of problems we won't go into here)? Think of this inspection as a simple feedback loop. In other words, learn what you can do at your site to ensure that your discharge is clean.
5 - You're taking your stormwater sampling at the wrong time.
A lot of people we end up helping started off by having no idea when to sample. Isn't your job just to "take a water sample"? NO! Your permit (almost undoubtedly) has restrictions on when you must take your sample. Will it make a difference to the results? I don't know, but it might! Why chance it? Get it right. Check your permit and make sure you know when to take a sample.
6 - Your stormwater equipment is disgusting and dirty.
Why would you ever take a sample, that needs to show your water is clean, with dirty equipment? That's like pouring someone a glass of water in a dirty cup! I see this all the time! Is your equipment clean? Where was it stored? Did the last sample leave a residue on it? Was it rinsed off? I just had a client have an issue because the guy taking their sample was using… a dust pan from his office! Long story short, make sure your equipment is clean. This is a no-brainer folks.
7 - You're not handling your stormwater samples correctly.
Take your samples and do what needs to be done to get them analyzed ASAP. Don't leave them baking in the sun for a week. Don't leave your samples open to the elements. Stuff like that. Will it really make any difference? For some parameters, no. But for others, definitely! And maybe, just maybe, your incorrect handling is making the difference between good results and bad results.
8 - Your stormwater samples are being analyzed wrong.
Your permit definitely requires that your samples be analyzed by certain approved test procedures, and trust me, there's a right way and a wrong way to do it. And yes, it does make a difference. It might make a big difference!
Stormwater test results are an easy way to figure out your compliance level.
Getting a good sample isn't rocket science!
Here's the bottom line. Think about the reasons above. If you're not up to snuff on all of them, then chances are you're having problems with your samples.
Step one is to make sure you're doing everything above. If not, fix your stormwater sampling procedures now! If one of those was the problem, then you should start seeing better results immediately.
If you're following all the steps above, and your samples are still poor, then you should start looking elsewhere. Maybe you should ramp up your BMPs. Maybe the problem is above you, and you should consider hiring an expert. But like I said, start simple, and work your way up from there.