We are pleased to have with us as a special guest speaker Mr. Steven Sittler, P.G. Senior Project Manager, Patriot Engineering and Environmental. Joined by Barry Poling, Central Region Manager at REGENESIS, Mr Sittler reviews a portfolio of remediation sites that featured the co-application of slow-release electron donor and bioaugmentation technologies from REGENESIS. This is a continuation of a webinar that was broadcast in February of 2015, in which Mr. Sittler and Mr. Poling reviewed strategies for success in the remediation of chlorinated solvents in groundwater. After accumulating another year’s worth of performance data, the 2 have lessons learned, and additional insight about when it is best to use supplemental injections. Below is the recorded version of the full webinar, including a Q&A portion in which they address live questions from the audience.


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  • To learn more about the bioaugmentation technology used at the sites in this webinar, visit our Bio-Dechlor Inoculum® Plus page.


You suggested that DHC or BDI Plus be applied concurrently with the 3-D ME. What do you mean by concurrently?

By concurrently, I mean that we do the injections not in the same hole, but at the same time. We like to do the 3-D ME first, and get all that in the ground, and then come back immediately and put in the BDI Plus. Bacteria are very oxygen-sensitive, so it’s important to use deoxygenated water, or water that’s been sparged of its oxygen with nitrogen, before you do that injection. Typically, we don’t think we have to wait six months, or three months, or a month, or anything. We typically do all the 3-D ME first, come back and do all the BDI. If it’s a long injection, it might be two or three weeks between the time that you finish the 3-D ME injection and come back with the BDI. But by concurrently, I mean, “Do it in the same mobilization, the same injection phase, and don’t wait.” There’s no reason to wait. But we do do them separately.

Do you always recommend adding DHC, or do you evaluate it before recommending it, or applying it?

In my experience, there’s been very little DHC at most sites where we’ve done a pre-evaluation. Again, as I said, those analyses are expensive. They’re about $350 a pop. So if you do six or eight wells, you’re looking at several thousand dollars. And most of the time, you end up having little to no bacteria. So if there’s a compelling reason that you think there might be bacteria because of the presence of daughter products, or maybe the presence of a plume of hydrocarbons that is commingling with your chlorinated pluming causing a reductive environment, then it might be worthwhile. But I think for the most part, adding bacteria upfront is going to be your best bet, unless you have strong reasons that that’s not the case. Again, the cost to do it typically is not much compared to waiting and doing it later. You know from the data that we’ve shown you that adding the bacteria to begin with is going to be a positive step. So I look at it as a rather inexpensive add-on in the grand scheme of things that has a huge benefit.

Are the injection times temperature, weather, or seasonally-dependent?

In theory, no. In practice, yes. The ground doesn’t change much, the temperature of the ground doesn’t. So from the perspective of the materials going in the ground and the bacteria, it’s going to be 55 degrees in the ground. It’s not going to make too much difference. But it’s a huge pain to have to try to inject fluids in freezing temperatures. We here in Indiana have freezing temperatures several months a year. And that’s why I say, “In theory, no.” It doesn’t make a difference to the bacteria themselves. But it’s tough to keep the materials…the materials themselves don’t freeze as much as you have problems with water, your joints and your pipe connections, and all the things in your Geoprobe. So we have done a couple sites where we’ve built little shelters around the drums or the totes of 3-D ME and kept them warm. We were able to do that. But even at night time, you have things freeze up. If you’re going to do that, you probably better have some leeway built into your budget to deal with the issues of cold because it’s not so much the products, it’s just the mechanics of doing it. It’s just tough. And guys don’t like it to have to go out and do it, either.

And beyond that, and I know we’ve talked about this, rain events. I know rain has affected some of the geochemistry at some of your sites.

Yeah, you have to keep that into account when you’re timing your injection. If you’re in an area that gets a lot of seasonal rain, you might want to think about maybe not doing it in the spring, especially in a water table condition. We had one site where the water table was only about eight feet deep, and it was sand. And we injected, and we got some positive results, but not as good as we would have liked because they happened to have, in the 3 months after we injected, they had about 13 inches of rain, which is way more than normal. And we believe that that counteracted our attempt to create anaerobic conditions, and flushed a bunch of oxygenated water through the formation. So if the water’s deep, and it’s not a water table situation, if you’ve got a sand lens or stringer, then I think perhaps that might end up not being as much of a concern as it does in a water table, especially shallow water table. But yes, certainly something to think about.

So what is the scale or size of plumes that you’re treating?

Well, as we talked about, some of the square footage there, they’ve ranged from as small as 1,000 square foot to as large as 66,000 square feet. We’ve actually got a couple sites that we’re working on right now that have larger footprints than that, up to 150,000 square feet, maybe even 180,000 square feet. So it works in a large variety of situations. The bigger the plume, the more you have to rely on transport of the materials by injecting them in barriers or lines. That increases the time it takes to clean it up. Obviously, if you tried to do a grid across the plume that’s a quarter mile long, it’s going to be ridiculously expensive. So barriers work well. They just take time to operate. One of the sites I did barriers on took about a year for the material to move downgradient to a well that was maybe 70 or 80 feet away. That’s about what we expected, but we had to do that additional monitoring during that period, and the well basically looked like it wasn’t cleaning up. But as soon as the material got there, it did.

So what factors determine whether to use ISCO or ERD?

Well, in my opinion, in my experience, that is typically…there are two things. One is concentration. We have effectively used ERD on some really high concentrations, up to 70,000 parts per billion of the parent product. But if you can do chemical oxidation and knock those down, it will make it easier for your ERD injection to follow on. You may not need as many supplemental injections, or as big of a supplemental injection. ISCO is a contact-based approach, so the materials actually have to physically contact all the contaminants. That has to be taken into account, and that’s a permeability issue. Whereas the bacteria will tend to move around a little bit as the water moves. Some will adhere to soil, but some will flow, and so you don’t have to worry about them actually contacting. I don’t want to say they’ll seek out because they’re not like little hunters going around hunting for the chlorinateds, but they’re looking for food. And as the food comes to them, and as they migrate, they’ll use it. So a combination of concentration and ability to get the material into the ground and allow it to move around.

And this is an extension of that last question, and you partially answered it already. At what high-end concentrations have you seen ERD effective? And is it effective on free product or DNAPL?

The DNAPL question’s easy. The answer is no. It doesn’t directly affect DNAPL. DNAPL will act as a continued source. If there’s DNAPL present, even if it’s just globules or droplets that don’t show up in the well, that can often be an explanation as to why a well isn’t cleaning up as quickly as you’d like. So it’s not effective on free product, but it is effective on very high concentrations. I have used it on concentrations as high as 70,000 parts per billion. In fact, the higher the concentration, the more rapid you’ll see degradation. So you can see success quicker in the higher concentrations, because it’s a lot easier to knock something from 10,000 to 500 than it is from 50 to 5. It’s like losing weight. It’s a lot easier to lose that first 20 than the last 20. So the same thing works with these. It’s much easier to knock down the high concentrations. I haven’t seen a concentration that I would think was too high. But if I saw anything up over 100, I would strongly suspect there was some DNAPL there, even if it wasn’t showing up in wells, and to be wary of that, and maybe try to address that some other way before I came through with ERD.

Going back to your cost comparison at the end, did that ERD cost include BDI and 3-D ME?

That cost range included the products, both 3-D ME and BDI, because we use them at all of our sites. It also included the drilling portion of it, the Geoprobe, and the injection pumps, and the materials. And it included the labor time for the crew that was out there doing the injection, as well as project management. So I rolled everything together. That was our project budget, soup to nuts. Materials, injection, management, oversight. There wasn’t anything left out other than obviously the assessment cost to determine what the problem was, was not part of it, nor was any post-injection monitoring. Typically our monitoring periods are, in Indiana, eight quarters. That’s a standard, although we’ve gotten away with less than that. Four quarters following some supplemental injections because it was obvious that it was degrading. It was just a matter of demonstrating that the add-on finished it off. Typically, when you have to do longer injections is if you get any spikes in your data, and you have to go back and deal with those things down the road.

If your pHs are low, generally around 5.5 at multiple locations at the site, would you still try this, ERD?

That’s pretty low. I would probably be reluctant to do that, unless I could buffer the pH ahead of time somehow. The worst thing with low pH is the degradation of daughter products. We’ve seen some decent degradation at 6.0 or a little below 6.0 of PCE to TCE. But when you get to cis- and vinyl chloride, they are very sensitive to pH. So when you’re talking 5.5, that’s pretty low. I would want to try to do something to buffer that before I would think of ERD as a good solution. And I don’t see that very often. But in cases where we have, we’ve had issues with that.

Do you have any experience with injection in horizontal wells?

None of the sites in this particular portfolio used horizontal wells. However, I know that Regenesis has done horizontal injections at a number of sites, and it certainly would work. I didn’t use them on any of these sites because I didn’t need to. But that would be a good application, under a building, or under a street where you couldn’t get at it angles, that would work well.

Video Transcription

Dane: Today’s presentation will focus on a multi-site performance review of projects using slow-release electron donor and bioaugmentation co-application strategy. This is a continuation of a webinar given last year, in which we reviewed strategies for remediation of chlorinated solvents in groundwater. Over the past year, we’ve been able to gather more comprehensive performance data from these sites, which has given us insight into when it is optimal to perform supplemental injections. So we’re excited to share this information with you today.

With that, I’d like to introduce our presenter for today. We are pleased to have with us Mr. Steven Sittler, Senior Project Manager at Patriot Engineering & Environmental. Mr Sittler has more than 30 years of technical experience in applied hydrogeology, with specialized experience in remedial strategy development and implementation. He has managed and performed hundreds of site investigations, audits, and assessments at industrial facilities, service stations, petroleum and chemical refineries, and landfills in more than 20 states, and has expertise in all aspects of remedial strategy development, and remedial system design, installation, and operation.

We also have with us today Mr. Barry Poling, Central Regional Manager here at Regenesis. He has 15 years of experience in the environmental industry, including extensive experience in Phase I and Phase II site assessment, remediation and industrial compliance. He provides senior leadership in areas of site remediation, design, strategy, and business development. All right, that concludes our introductions. So now I’ll hand things over to Steve to get us started.

Steve: Thanks very much, Dane. Hopefully everybody can hear me okay. If you have any issues with that, just please send a notification to Dane, and we’ll try to get that taken care of. But welcome, everyone. Again, as Dane said, this is kind of a follow-up to a presentation that we did last year on the same basic approach, but there is some really valuable information that you will see here at the end of the webinar that we’ve collected and developed by analyzing that data. And showing that not only does ERD work, and that we’ve done it successfully, but how long it ought to take and when you might want to look at supplemental injections.