Groundwater Contamination


Here's the thing

Here’s the thing with groundwater contamination for residential sites in the state of New Jersey. If the contractor you hire to perform your soil remediation project does the proper job and removes all the soil contamination, your groundwater investigation will most likely be clean. What that means is the source of any groundwater contamination must be removed in order to get clean groundwater, the source being the oil contamination in the soil. We need to first remove the tank, then we need to remove the contaminated soil that’s soaked with the oil. Then we put a well, which is basically a piece of PVC pipe that we drilled down to water level, and we pump out the water and we put it into a jar and send it to a state certified lab.

That water is going to come back clean nine out of 10 times, as long as the source is all gone. If you leave any of the source in there, if you leave soil contamination behind, because technically it’s under the cleanup standards so you don’t technically have to remove that soil, the problem is it’s still going to contaminate the groundwater to a level where the ground water will then not be acceptable. It will not pass the acceptable limits, which means we then have to either treat the groundwater or we have to return and take more of that source out, which is contaminated soil

So it’s very important that when you have groundwater impact or bedrock impact, when you’re excavating contaminated soil, that you get every last drop of contaminated soil out that you can. Now, sometimes that’s not physically possible, so you have to leave it behind. Then you have to deal with the groundwater in another way. You’ll have to treat it. But that’s a very extreme case in the state of New Jersey for residential sites. 99% of the jobs that we do in residential, when we investigate groundwater, the groundwater is clean, 99% of the time.

1% of the time, the groundwater is not clean. What happens in that situation is initially we need one clean sample result to show the NJDEP that yes, we investigated the groundwater. That one sample comes back clean, you’re finished. We write a report, you get your no further action letter. If that sample comes back over the cleanup standards for groundwater, the state will then require two clean consecutive rounds of groundwater samples. They must be taken 30 days apart.

How do we get the groundwater clean? There’s a few options you have. One is we can wait it out to have it naturally clean itself up. That’s the cheapest way, if you could afford to wait. We’re talking a few months to sometimes a few years. Or two, we can perform what’s called an EFR, Enhanced Fluid Recovery. What that means is we’re going to come out and basically remove all the vapors from the well, and also remove the water from the well. We’re essentially sucking the water out of the ground and bringing it to a facility where we’re going to dispose of it properly. This will help clean up the groundwater. After this EFR event is performed, we’re going to grab another ground water sample. If that’s clean, we’re going to perform a second EFR with a second ground water sample. And that should be enough to close out your case number.

If the groundwater continues to fail, we will then need to entertain either treating the groundwater with different chemicals that will clean up the hydrocarbons, or we need to entertain re-excavating more of the source out.

For more information on the next steps with contaminated groundwater, please don’t hesitate to call us