This webinar focuses on pre-application Design Verification steps that directly improve existing design assumptions prior to field application, resulting in improved remedial performance outcomes. Craig Sandefur, VP of Remediation Applications Development at REGENESIS, and Rick Gillespie, SVP North America at REGENESIS, discuss the identification of aquifer characteristics that can be documented using traditional field methods and provide the most insight into the remedial design and application programs.

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What is the typical timing for design verification? How far in advance should it be done before the field application starts?

Typically or ideally, it would be at least six weeks out. That doesn’t always happen. Sometimes it’s part of the field application, but ideally for us, to be able to collect this information and make the necessary changes to evaluate the data and provide the report, we’d recommend at least four to six weeks.

To build on that, people often ask, how long does it take? What are the costs associated with it? It really depends on the site and the size or the scope of the remediation. In terms of cost, it varies. In the data that we presented, it was somewhere between 3% to maybe 8% of the total remedial project cost, and, on average, it was in the $6,000 to $8,000 range for the data to collect that. I’ll tell you, its money very well spent. If you’re one of those 10% of sites where we may change the whole remedial design, I guarantee you’re going to save money on that. But just in terms of improved remedial performance, we just haven’t seen a site we’ve collected where design verification didn’t help us in some way.

What volume of water is injected at each interval, and really what’s the total volume? And I’m assuming they mean that rule of thumb.

You know, it’s really reagent-specific and the clear water injection testing will be based off the reagent. So if it was something like PlumeStop, it would be different than it would be if it was something like RegenOx or PersolfOx, and they’re all high volume where they’re very critical as in the high-volume reagents. And, essentially, what we try to do from a design verification standpoint is to use volumes that represent, if we’re using direct push or even injection wells, represents the entire volume that we would theoretically apply. If it’s a nonreactive material, we probably go one to one. If it’s reactive materials, we’d probably go 1.3 to 1, gallon per gallon, just to make sure we have a little bit of a wiggle room there and make sure the aquifer can really accommodate that volume.

Is there any problems with getting regulatory approval to do a clear water injection test?

So we’re injecting tap water at these sites. Were not re-injecting groundwater so, to date, we have not had any issues in the states where we’ve performed this in terms of getting regulatory approval for that injection.

It’s a question related to direct push. How do you decide when you’re going to do bottom-up versus top-down?

It’s really based on hydraulic conductivity. And if, let’s just say, you have a sandy unit deep and you have more fine-grained units up above, let’s say, high silt still clay content, if you start at the bottom-down and you have a stick interval, let’s say even 10 feet, and this can happen even over a 4-foot or a 2-foot zone, if you have large hydraulic conductivity ranges, going from the more transmissive to the less transmissive, it almost ensures you’re going to put most of it in the higher transmissive zone because of the resistance that’s required to move fluids into the lower hydraulic conductivity zones. And as you know, fluids take the path of least resistance, so that would be a top-down indicator.

The reverse of that would be the same. I would do bottom-up if I tended to have more coarse-grained material higher in the section and finer-grained materials in the lower section. I’m a big fan of shorter intervals is better. It controls more. It gives you more control on where you’re putting reagents. So the longer these treatment intervals are, the less control you have over where you’re putting reagents, so that’s just a given.

Is it difficult to convince clients, and by client I mean the end user, the payer, to install more boring wells to characterize the hydro-geologic conditions? And I think their question is what’s your basis? How do you provide a technical rationale to the payers, say, “Look, these tests are worth it.”?

Well, I mean, I think they’re fundamentally based in the notion that you’re avoiding application of reagents…I mean, I think it goes to that where we talked about the characterizations done today are for different set of reasons than why you’re doing remedial investigations. You’re trying to find mass in the trans-mass transport units. And if you don’t identify those, you’re not really inclined to be focused on that as part of your other remedial steps, I mean, sorry, characterization steps, then you’re really trying to design into a system that you really don’t understand. And you’re going to save time in terms of covering a 20-foot section, because during the characterization you screen it across a wide interval because we didn’t quite understand what groundwater was doing and where the mass flux zones were.

And therefore, once you can do something like a design verification step, you’ve now rifle-shotted it in to maybe a four foot zone. So not only is this the time to apply reagent, it’s also putting it where you need it, not where you don’t. So you save time, you save money, because your applier isn’t out there a long time, and you’re saving cost of the product itself.

You indicated that something one should not proceed with the remediation of the volume was too much. What the heck does that mean? What is too much?” I think what they’re referring to is reagent volumes. Craig, you want to take a stab at that one?

Maybe I was amiss…that poor language selection. I would say, try to think of it as: can we fit the remedial reagent? Are we under hydraulic limitation? Can we fit the reagent volumes with the necessary quantities at the proper solution percentages into the target treatment zone? And if the volume is too much, then you’re going to be fracking or you’re going to be surfacing just from mounding. So you have to keep those things in mind in trying to fit the reagent quantity in terms of mass of material in volume. Does that make sense?

I’ll take a stab on that one, too. In our remedial designs, we make assumptions and we might assume that we can get three to five gallons per minute via direct-push well. If we go out and do this around verification on our clear water injection tests of, “Hey, you’re going to have a hard time getting one gallon per minute.” And that means we would look for, “Hey, is direct-push the right approach here? Maybe we need to do permanent wells.” So when you talk about reagent volumes and what’s too much, it’s really related to how much volume do we need to get into the subsurface and how long is it going to reasonably take to get it in the ground?

Can you discuss how designed verification differs from a pilot test? I’m a huge proponent of pilot tests. I use those as then feasibility tests, really, as they’re something.

I just would say design verification is not reagent injection. We’re not going out there and measuring results. These are simple tests collected to help us define the vertical treatment interval to identify areas with high mass flux zones and to ensure that the contaminant concentrations that we’re basing our reagent amounts on, that they’re in line. So it is different than a pilot test, both in terms of duration and the fact that we’re not collecting additional contaminant data in most cases.

What is the approximate costs of design verification studies based on the graph you presented? Over 70% of the time you did not change the remediation designs.

We may have not presented that clearly. In fact, about 62% of the time, we, in fact, do change the remedial designs. Those changes can be changes in injection intervals, reagent volumes. Most the time it doesn’t result in a change in cost. Keep in mind up in the data we presented, and that was on 28 sites, 10%, 11% of the time, we canceled the injection and said, “Hey, we need to take a step back or we need to make recommendations for alternate approaches or alternate technologies.”

Total cost, usually around 3% to 10%. That’s a very broad rule of thumb. We’re only talking about one the two days typically in the field with a geoprobe unit. You guys know how much geoprobes cost per day. It’s often in the $6,000 to $8,000 range would be a typical cost for a design verification.

Are you emphasizing putting more substrate where the contaminant mass is located or where the contaminant mass flux is occurring? In your experience, are they typically the same or different?

Well, I’ll answer the second question first. They are different. And I am emphasizing, depending on the strategy and the very specific site objectives and goals, I always think that if you want to shrink a plume rapidly and quickly, you must contact the mass flux zones, that zone that carries 90% of the mass and probably 10% of the aquifer. If you identify that and you are able to address that with an efficient application, a plume will shrink rapidly. As far as putting it where mass is, and this is a whole different kettle of fish, in terms of the source area, I would advocate absolutely putting it right where the mass is.

Now, if you get in really heterogeneous environments where you have a back to fusion, etc, that’s a different philosophy and an approach that I would have to talk with them about. But, essentially, I’m interested in mass flux in the body of the plume and I’m interested in putting it right on the contamination, in the more source or proximal to the source area.

Video Transcript

Dane: Today’s presentation will focus on pre-application design verification steps that directly improve existing design assumptions prior to field application, resulting in improved remedial performance outcomes. With that, I’d like to introduce our first speaker for today. We are pleased to have with us Mr. Rick Gillespie . Mr. Gillespie serves as Senior Vice President of North America for REGENESIS, directing a team of technical sales consultants and engineers across North America, providing industry leading support to REGENESIS customers. He has over 20 years of experience in the environmental remediation industry.

All right that concludes our introduction. So now I will hand things over to Rick to get started.

Rick: Well, thanks Dane, appreciate it. On behalf of my co-presenter Craig Sandefur and our co-contributors Chris Lee and Steve Barnes, our team here at REGENESIS, some of the folks at Alion Science and Technology, I’d like to welcome you to today’s webinar. We obviously know how valuable your time is and our goal today is really to provide the ‘behind the scenes’ look into our remedial design process, and ultimately provide insights into the side issues that determine remedial success for all of us.

For those of you who may be unfamiliar with REGENESIS, our company was founded in 1994. We specialize in soil and groundwater remediation, as well vapor intrusion mitigation, with a broad range of technologies. Many people know us for Oxygen Release Compound or ORC Advanced, that simulate aerobic bioremediation of petroleum hydrocarbons. Many of you have worked with us on enhanced reductive dechlorination with either HRC or Hydrogen Release Compound, or 3D microemulsion for anaerobic bioemediation. We have a tremendous amount of experience with in situ chemical oxidation, both for soil and ground water, using our all-in-one catalyzed persulfate, known as PersulfOx, as well as RegenOx, two powerful oxiDanets that work on a broad range of contaminants.

In the last year or two, you’ve probably heard a lot about our new technology class using liquid activated carbon, PlumeStop. PlumeStop is a platform technology that absorbs contaminants to reduce its concentration to very low levels in days to weeks. We call it a platform technology because it really creates a table where contaminants can rapidly absorb and microbes can flourish to lead to permanent destruction of those contaminants in situ.