Case Study: Practical Strategies to Demonstrate Remediation Success with PlumeStop and AquaZVI
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Are there any long-term studies with PlumeStop ? Will it break down and rerelease contaminants?
So activated carbon has been used for an awfully long time and what effects it and the isotherms over very, very well defined. So the things to watch out for with the application of PlumeStop is due to realize that activated car even has a finite capacity and having a co-applied or combined remedy that includes a degradation mechanism to keep the carbon clean and to keep those captions sites available. And from, you know, from reaching its capacity is incredibly important and monitoring to make sure you have the degradation pathway is also incredibly important.
Can you reapply degradation products without adding more PlumeStop if contaminants persist?
And for that Arkansas site, that is the basis of our design. So the PlumeStop of course, you know, cost more than just adding the biostimulants alone, which are relatively cheap. So the ONM plan for the Arkansas side is to no longer add any more pumps. Stop. We stop was added initially as part of the capital costs, the initial implementation. So every few years we expect that we’re gonna have to go out and add more a bio stimulant, maybe some micronutrients. So definitely you do not need to add more v wants. It’s already applied that activated carbons there and just need to keep it clean by stimulating the degradation mechanisms.
Does the bio degradation occur on the dissolved phase only and then is the sorbed phase not bioavailable?
Well, I guess that’s how small you have large, you wanna draw your black box. So my microbiologist friends tell me that you cannot get degradation on the swarm face, like something that’s in the solid phase. But there’s a lots of stuff that go on and very, very, very close distances, you know, in desert technically dissolved but associated with the sword face. So I’ve noted bio gac and degradation on activated carbon. You activated carbon is completed, is incredibly efficient and I think there’s a decent amount of studies that show that and more information on the enhancements of activated carbon on degradation, check out that webinar, that door a tiger gave that’s archived on the REGENESIS a website. I dropped my back box pretty large when it comes to that. I don’t get caught up in the semantics of does degradation actually occur on the subsurface or not? It occurs.
Would PlumeStop and AquaZVI work on a low-level 11DCE and vinyl chloride plume?
Sure, yeah. As long as there’s no inhibitors and that sort of thing, so you need to know you, you know, do your normal design homework and make sure you’re designing your amendment formulation perfectly. But do you have anything to add to that one Maureen?
Yeah, and I think it’s important to note is I mentioned we have software that allows us to incorporate isotherms of different chemicals, biodegradation rates and that again will allow us to come up with the right design mixture. I personally for the compounds that you’re mentioning. I certainly would consider ZVI bio and Aqui ZVI the application and I think it would be quite appropriate.
Dane: Hello and welcome everyone. My name is Dane Menke. I am the Digital Marketing Manager here at REGENESIS and Land Science. Before we get started, I have just a few administrative items to cover. Since we’re trying to keep this under an hour. Today’s presentation will be conducted with the audience audio settings on mute. This will minimize unwanted background noise from the large number of participants joining us today. If the webinar or audio quality degrades, please disconnect and repeat the original login steps to rejoin the webcast. If you have a question, we encourage you to ask it using the question feature located on the webinar panel. We’ll collect your questions and do our best to answer them at the end of the presentation. If we don’t address your question within the time permitting, we’ll make an effort to follow up with you after the webinar. We are recording this webinar and a link to the recording will be emailed to you once it is available. In order to continue to sponsor events that are of value and worthy of your time, we will be sending out a brief survey following the Webinar to get your feedback.
Today’s presentation will focus on Case Studies and Practical Strategies for Remediation Success with PlumeStop and AquaZVI. With that, I’d like to introduce our presenters for today. We are pleased to have with us Matt Burns, Technical Fellow and the US contaminated land national service line director at WSP. Matt has more than 25 years of professional chemistry and engineering experience. He’s based in Boston and is responsible for the financial and technical depth and breadth of the contaminated land site, investigation and remediation service line.
Matt also brings chemical and microbial process expertise to assist the local WSP teams with challenging investigation and remediation projects in the US and across the globe. His area of expertise includes practical application of microbial and chemistry based innovative remediation. We’re also pleased to have with us today Maureen Dooley, Director of Strategic Projects at REGENESIS. Maureen has more than 25 years of experience in the remediation industry. In her current role at REGENESIS, she provides the technical leadership for complex soil and groundwater remediation projects throughout North America as well as remediation design strategy and business development in the northeastern United States and eastern Canada. All right. That concludes our introduction. So now I’ll hand things over to Maureen to get us started.
Maureen: Well, thank you Dane. And welcome everyone, welcome from the WSP office in beautiful downtown Boston. I understand how busy people are, so really appreciate you choosing to participate in the webinar presentation today. I wanna give a special shout-out to the folks in the UK and Europe who are joining us as well as we know how late it is in your day. So the title of today’s presentation is Practical Strategies to Demonstrate Remediation Success with PlumeStop and AquaZVI. And has Dane had mentioned, we are really pleased to have Matt Burns with us today to make this presentation. I have had the pleasure of working with Matt for many years. And at once it comes to site remediation, I really appreciate, appreciate his abilities and he has a particularly an academic level of understanding, yet he applies this knowledge in a practical way that really can result in an effective application of technologies and ultimately achieve that goal of obtaining reduced costs to closure.
So just to briefly highlight what will be covered today, Matt will discuss in some detail ways to monitor and to demonstrate biodegradation, how biodegradation is contributing to reductions observed when you seen PlumeStop liquid activated carbon. He also will present data from a very interesting case study. And then later in the presentation, we will discuss how unwisely ZVI may be incorporated into a PlumeStop liquid activated carbon application. So with that, Matt, I’ll turn it over to you.
Matt: Well, thank you, Maureen. That was a great introduction. I think some of my family might disagree with that, but thank you. Well, welcome to the webinar and thank you for taking the time out of your day to tune in. You know, as Maureen just discussed, we’re gonna talk about a new class of In Situ remediation amendments based on the PlumeStop technology. We’ll discuss some of the benefits of the technology and we’ll also discuss some of the challenges. Hopefully, we’ll leave you with solutions to these challenges so that it benefits our best realize and more and more contaminated groundwater sites get closed.
This flowchart shows the steps for managing any project from grocery shopping to a designing In Situ remediation cleanups. I know the cycle is a cycle is absolutely correct because I got it from Wikipedia. Let’s focus on the very beginning of the project initiation phase. From the design engineer’s perspective, that means that most of the time a good amount of the characterization data has already been collected and a general conceptual model has been developed. The contaminants are known and the need for treatment has been identified. The real action goals have usually been set, you know, treat to a standard or isolated pathway. So we can be then thinking about potential remediation options just about as soon as it’d be a design engineer gets the project.
So In Situ remediation of groundwater and all lots options or potential degradation pathways to stimulate. This screenshot alone shows many discrete pathways for chlorinated solvents in petroleum compounds. Their oxidative pathways, direct chemical oxidation, aerobic bio-oxidation, anaerobic bio-oxidation, comb, anabolic and reductive pathways, you know, direct chemical reduction, hydrogen analysis, elimination pathways. And this is just the first part of the page of a simple Google search, you know, uncontaminated degradation pathways.
So over the past few years, a lot of degradation pathways have been identified for design engineers to stimulate. Further, there are lots of combinations of these pathways that can use to make clean up even more efficient. Here’s a little bit more info about the combined remedies. Combining remedies often returned, referred to as a treatment trains. The concept has been around for awhile with pump and treat systems. For example, the first extract the water and run it through an air stripper, then you run it through activated carbon for polishing. So the idea behind combined remedies is that each technology has a set of optimum conditions where they perform most efficiently.
The plot here shows increasing contaminant concentration on the X-axis and increasing costs and dollars per mass and contaminant removed on the Y-axis. The black line shows that mass removal generally through horsepower technologies is most efficient at high contaminant concentrations. Bioremediation is more efficient at the lower contaminant concentrations. ESCO and hisker fill the space between mass removal when bioremediation. Combining a remedies allows for the highest treatment efficiency at the lowest possible cost.
I love combined remedies. Nearly all of my projects a now use combined remedies. My favorite combined remedies involved stimulating multiple In Situ degradation pathways using a single amendment formulation. Know Jim Cummings and his colleagues at EPA have championed the use of combined remedies. He actually calls this multicomponent amendment formulation to two force. You’d be surprised at how many different degradation pathways can be recombined synergistically. You know, three furs and four furs maybe even more. And the best part about these applications is that they lead to complete remediation and lower costs to closure.
I’ll be talking about a couple of amendment formulation combinations today. Plumestop plus bio and PlumeStop plus bio plus ZVI. Additional information on a multicomponent, multifunctional amendments, synergies can be found in a combined remedies is article thinking out the side of the boxcar which we published last year. So the end game is that in addition to selecting degradation mode, oxidation or reduction, there are many degradation pathways that can be used and probably hundreds of pathway combinations. In every amendment vendor, they’ll claim that they have the best their product, their stimulant is the best for your site. And if the contaminated matrix was homogeneous sand, well they might be right, their product might be magic dust. But the most challenging part of any IN SITU design is not whether a pathway or pathways can be stimulated. It’s whether or not that’s relatively easy to prove. By doing some advanced diagnostics combined with some IN SITU or xx studies.
I find the most challenging aspect of the design to be making contaminant amendment contact actually getting on the degradation pathway. So here’s the reality of most sites. The image to the right is a teleview log of fractured bedrock. It’s a 360-degree photo of the borehole. You can see some wide fractures here and you’ll be seeing this bedrock again a few minutes in the case study. This is a three-foot section of that teleview image. You can see the fractures here with apertures ranging from six inches to a quarter inch and even smaller. The bulk matrix, the sandstone, which has a fairly high porosity as bedrock goes and as compared to the porosity of fractures. You can see that is going to be quite a difference in how contaminated groundwater moves within the fractures versus within the competent rock matrix. The difference is gonna lead to back diffusion. There are some visuals that explained this in the next couple of slides. But basically back to fusion can occur with this little order as an order of magnitude difference in hydraulic conductivity between adjacent matrices.
So a sandy zone adjacent to a less transmissive zone is equivalent or nearly equivalent onto this bedrock example. So contaminating groundwater flows fast and fractures. This is active transport. But affect the ground also migrates into less transmissive zones here into the bulk sandstone by diffusion. This slide shows a remedial effort which cleaned up the more transmissive flows sounds, the remediation changes that diffusion gradient and contaminants diffuse from the bulk sandstone, and if the men who is no longer there, recontaminate the higher flows now causing a contaminant concentration rebound in the more transmissive zone. This back diffusion will occur for at least as long as the contaminate has been a present probably much longer.
Here’s another cleanup attempt, but this time with a longer lasting amendment, the longer lasting amendments are typically limited to colloidal particles, but as I mentioned earlier, colloidal particles are difficult to deliver and fractured rock without potentially clogging fractures and diverting flow. This dramatically limits the options available to the design engineer. The product innovators at REGENESIS and developed this technology that aids in the distribution of these colloidal particles. They use an antibiotic polymer just strictly stabilized small particles with an aqueous solutions so that they flow like water. And the delivery characteristics more comparable to amendments to dissolve and conventionally applied colloidal solid amendments.
This column test, it shows the difference in transport characteristics between the starkly stabilizing non stabilized particles. You see there’s quite a difference you can see from the labels on the size of the particles being tested were activated carbon-based PlumeStop, which is the first material REGENESIS has applied the stabilization technology to and that’s compared against powder activated carbon. I’ve used it on several sites and it functions differently than any other In Situ amendment have used. This is because PlumeStop alone does not destroyed contaminants. It absorbs them. Destruction is completed by a co-application of the combined remedy that stimulates degradation along one of those pathways shown in the earlier Google’s search slide. The PlumeStop concentrates to chemicals for efficient treatment along these pathways. And if you’d like more information on how the activated carbon enhances biodegradation, there’s a great webinar that door taggart microbial insights gauged archived on the REGENESIS website.
Let’s use a visual to explain the significance of this selection mechanism. All right, here’s a glass of water. And if we install it well, I should have put the sand in first. And then we’ll add a contaminant in our contaminant is conveniently colored red and treated with PlumeStop in biostimulants. We can wait a while for the PlumeStop to set a lot of solution or a cat on a parking agent can be added to cancel out the negative charge of the PlumeStop stabilization palmer to speed things up. You end up with an aqueous phase free or nearly free contaminants. This is because the contaminants petitioned to the soil face and is hopefully degrading. Why is it important that the contaminant is degrading on the v and the solid phase? After all falling the treatment, the activated carbon in the groundwater concentration is likely an order of magnitude lower. So treatment with the activated carbon causes dramatic concentration decreases, and oftentimes it’s pretty close if not complying with apical standards in the aqueous phase.
Well, it’s important to add the degradation mechanism too, because activated carbon has an unlimited capacity. Loom needs to be made on the activated carbon by destructive treatment to accommodate additional contaminant loading from, for example, back to fusion or even naturally organic materials. These materials can migrate onto the treatment zone, into the treatment zone and potentially bump off a contaminant.
Here’s an older but, you know, applicable guidance on activated carbon. On the second page, it notes that high levels of organic matter may result in rapid exhaustion of the carbon. It’s pretty easy to imagine a scenario where background levels of organic carbon, even those lower than the 10 milligrams per liter noted here when continuously loaded, could cause an issue potentially leading to disruption of the target contaminants in the future. So it is very important to have a good destructive mechanism included to make sure the remediation is complete and that there are no surprises a couple years down the road.
So monitoring to assess degradation along the stimulated pathways is very important too. Let’s go back to the project management cycle to show the importance of performance monitoring of any radiation project. Again, this flowchart shows steps for managing any project, grocery shopping to brain surgery, and even including remediation. After initiation, all projects go through a planning stage where real action objectives as set, in our case combined remedy of bioremediation, aided by sortation onto activated carbon. After the plan and design are implemented, testing can you begin to see if the radio action objectives had been met. If the test is passed, the project closes, but if it fails, then you basically need to go back to the planning and design phase and come up with an adjustment or start all over. This can become an endless iterative cycle. The way to break the cyclist and make sure that the degradation pathway or pathways for combined remedies that you’re trying to engineer are actually stimulated and the degradation pathway is complete. If a problem was identified early, then you’ll be able to fix it quicker and minimize your trips around the project management cycle and close the project quickly and permanently.
I think of these degradation pathway is the same as taking a trip and an unfamiliar area before GPS. After every turn, I used to look for visual clues, landscape features, signs that indicate that I was on the right road. Observing these cues, other tests use the trip to my destination. If I looked at the signs at key points frequently, the concept the consequences of making a wrong term would never be that bad. I could just turn around and get back on the right path. If I didn’t look for signs often enough, I could end up way off course and maybe not even reached my destination.
The degradation pathway or pathways in the case you can run remedies is the remediation roadmap. Specific, react and some products in a number of reactants and products in the equation, you know, very, but the contaminant being treated in the pathway being stimulated caused them to vary. But there’s always products and reactants.
Key reactants and products, anything needed to silicate reaction are great candidates to include performance monitoring plans. The performance monitoring plans did not need to mirror natural attenuation investigations. For MNA investigations, the degradation pathway is unknown and needs to be identified and the stoichiometry of the equation of that degradation pathway needs to be figured out in the presence of enough of reactants and proper conditions to derive complete degradation. All need to be determined for MNA to be applicable. For remediation sites, the design engineering selects the pathway to stimulate and prides proper conditions, careful considerations given to the amount of reactant the macronutrients. The macronutrients have electronic sectors and electron donors needed to drive the reactions.
So performance monitoring is a designed for certification at the working level. Are there any issues needed to be fixed level? So observing expected trends is evidence of activity along the targeted degradation pathway and the evidence that you’re realizing your design goals, but not all data is equal. Data that provide direct evidence of degradation is the strongest. In a decreasing voc of the king of that evidence line. After all VOCs are the reason remediation is needed in degradation, pathways were identified for stimulation. End products like Ethane and Ethene for chlorinate contaminants and isotopic data also provide great direct evidence of activity along stimulated degradation pathways.
Mechanistic data provides solid evidence of activity along the degradation pathway to these data focus on the facilitators of the reaction, the microbes, and the functional and the functions of interest. For example, for chlorinated Ethene d helical coilsgs is the magic microbe, is the only microbe reference in literature that completely degrades PCE and TCT to the innocuous end products, Ethene and Ethane. For DHC, there’s even a target abundance and it’s been identified as one times 10 to the 14th cells per milliliter. A target abundance correlates to rapid degradation rates. That targeted abundance is referenced in the 2015. The article in groundwater monitoring remediation the article also has great content on abiotic degradation by reactive iron minerals, and I urge everyone to pull that and review it.
Finally, there’s empirical data like macronutrients and they’re oxidized and reduced products. Macronutrients in the electronic chapters like dissolved oxygen, nitrates, self-aid to stimulate petroleum degradation or contaminants that he uses electronic Service lifetime donors. Electron donors are microbial food that are added to stimulate how hallow respiration of a comment bollock degradation pathways. These microbes needs the contaminates and need something to eat in the electron donors and what they eat. The macronutrients also stimulate ancillary geochemical changes that often have empirical relationships with the target degradation pathway. For example, ORP, Ph, conductivity alkalinity, these great data for assessing delivery efficiency,
So monitoring is important and traditional buyer mediation performance monitoring heavily relies on seeing direct evidence like VOC concentration, reductions, but we just discuss how activated carbon moves VOCs from the aqueous phase. What do we do to moderate and apply know what are we supposed to monitor and apply like? Yeah man, Kendall, statistical analysis on that. Well, not all of the products and reactants are sewer by activated carbon. Here’s the guidance on treating VOCs using activated carbon. Yeah, there’s a lot of EPA guidance on activated carbon, even though from the age is still relevant, if you wanna take a deeper dive into the object. But on page 75 at this guidance as a nice summary of a capacity to select VOCs on activated carbon the graph at the top of the page shows average storage and capacity using eight types of activated carbon.
For several other VOCs, you’re basically how much VOC massive swarmed when the aqueous phase is held in a fixed VO concentration. You can see the difference VOCs have different affinities for the activated carbon. Generally, so option capacities for less soluble compounds a greater than those for a more sizable compounds. The graph shows floral, benzenes and PEC on the right with the highest activated carbon capacities, TCE and benzene or in the middle, and the methylene chloride is the left not showing is vinyl chloride, which we plot even further to left. Ethane and Ethene basically have no affinity for activated carbon different. Electron donors could also be plotted here too. Some have higher affinity for activated carbon and some have very low affinities.
The REGENESIS technical people can help you determine whether or not the donors that you want to use have affinity for the activated carbon PlumeStop. Many the reactants and products don’t have much affinity to activated carbon chloride, ethane, ethene. There are many others. Microbial parameters also don’t, are not very sensitive to activated carbon as far as their relationship with abundances are concerned.
So last year I gave a talk about a engineered bioplus biogeochemical reductive dechlorination combined remedy. It was a pilot test at a site in Arkansas. We also conducted a PlumeStop pilot tests at the site that we’ll talk about today. Here’s a quick refresher on the side. It’s a former manufacturing site that began operation in the early 60s. Operations included chlorinated solvents, you contaminants included TCS and his daughters. Affected groundwater is present and fraction sandstone matrix. We’re back to fusion a major concern we expect long term back diffusion from this matrix. The sandstone fraction network is predominantly horizontal fracture pattern with some high angle fracture is present. And the veto zone source areas had been remediated and vapor mitigation systems have been installed.
This cross section shows the psych conceptual model with the former facility, the top of the hill. The pilot trust areas a few hundred feet downgrading in the facility. Oh, excuse me, I have a bit of have a cold. The plumes discharging to the local stream about a thousand feet away from the facility. And the vetoes known sources have been excavated. The pilot tests were conducted in these adjacent areas. Wells within each oval were included with the performance monitoring. This includes nearfield wells and farfield wells, hundreds of feet away from the injection point.
The purpose of the pilot tests were taking place long-lasting amendments to address back to fusion exactly as was shown earlier in the back diffusion slides. The overall concept would be to install injection wells along several transects, perpendicular groundwater flow and maintain a treatment conditions every few years with operation maintenance injections. For PlumeStop plus bio, this would involve injecting biostimulants only during the operation maintenance activities as the activated carbon is conserved.
Costwise, the capital costs of installing injection wells and the first application of the PlumeStop and buyer mediation amendments is roughly equivalent to the capital cost of a pump and treat system. But the o and m costs the PlumeStop plus bio, the periodic application of biostimulants is just a fraction of the cost of a pump and treat owner And over the lifetime of the remedy, this provides a huge cost savings as compared to pump and treat in a much, much lower total cost of closure.
Here’s the layout of the nearfield wells. The distances a labeled in the figure. IW2 was the injection well. It was a two inch PVC well screened across the sandstone unit. The amendments included PlumeStop activated carbon to the aqueous face in a concentrate them for the efficient treatment and by biodegradation along the sequential dehalogenation or hydrogen dialysis pathway.
HERC and HRC primer who the electron donors we used. We also applied micronutrients, nitrogen, and phosphorus. We added a sodium bicarbonate buffer to keep the Ph within the ideal range of dehalogenating microbes. And we actually added some biology into microbe with the helical cody’s augment. The injections went very smoothly. We applied about 5,000 gallons of fluids at less than a 10 PSI through IW2 and she the flow rate of about 10 gallons per minute. There were no delivery issues at all with the amendment that PlumeStop when and like water.
The footprint of the electron donor distribution and the expected geochemical changes in response to the amendment are shown here. The heat map shows two post-injection monitoring rounds, the green strong or chemical shifts yellow or for moderate and read for really no shift at all. All is compared to baseline. For example, the VFAs in the top row and measure electron donor is green. A strong signal in the groundwater samples collected from the closest monitoring wells and a bit weaker for the don gradient. Dissolved oxygen showed a good geochemical response. It’s now wells initially, but you can see some potential influence, a deal loading from upgrading an untreated areas. Overall, it was a strong Geo chemical shifts consistent with pathway we’re trying to stimulate in the closest wells. And there’s even some evidence of Geochemical shifts in amendment delivery in the more distant wells.
Okay. This slide shows groundwater VOC data and mole fraction information. The X axis on the plot show the dates of the baseline and performance monitoring sampling. The Y-axis is the total VOC and micromolar concentration. And the mole fraction is shown. The Pie chart that plots the total VOC concentration, you know, red’s TCE, yellow DCE, Greens for Vinyl chloride and Blue for Ethane and Ethene. So you can see that samples in the three closest wells IW2, W5, and MW6, the wells within 50 feet of the injection point shows significant groundwater concentration decreases with treatment. But apparent progress along sequential reductive dechlorination pathway seen in the pie charts is not totally clear because preferential option of TCE over, you know, over DCE by the reactive carbon could have caused that partitioning. However, the MW6 pie chart shows 30% conversion of chlorinated VOC to Ethane and Ethene.
The degradation pathway is definitively complete based on the OW6 samples, I’m sorry, MW6 samples. By contrast, the mole fractions didn’t change much in OW6 and OW7 samples, but it looks like there might’ve been some option in OW6 samples. See what was going on in the store fest, we constructed In Situ microcosms. In Situ, microcosms ISMs and deploy them before the amendment, a injection so that the ISMs will be treated in a manner similar to the fractured sandstone matrix.
Here are some photos of the ISMs. We crushed sandstone with a hammer and collected sand passed through a 35 massive, but it was retained by a five-match live. The crushed sandstone was then placed into one-inch diameter well screen and deployed within our monitoring wells. We deployed several ISMs in the each well so they can be disconnected discreetly. The goal of the ISM samplers was to quantify degradation on the PlumeStop on the sword face.
This slide shows the results of the phase data from the ISMs. The VOC data and mole fraction data plot of the same way they were on the previous slide. The plots for OW5 and NW6 data show increase VOC mass loading. This is to be expected with upgrading VOC, migrating into the treatment area. This was a relatively small pilot trust in a much larger area. So, even so, the mole fraction data from samples collected in these wells show reduction of TCE to DCE. This information cannot be readily inferred from the groundwater sampling data because of the differing affinities of these compounds for the activated carbon. The data from downgrading, the VOC or a significant total VOC concentration decrease and reduction of the TEC to DCE.
We also ran some advanced diagnostics. Here are the data from MW-6 located about 50 feet from the injection plan, a fairly represented well as far as being located far enough downgradient to minimize the effects of upgrading it, loading of DCE and VOCs, but not so far downgradient that delivery efficiency is questionable. The first two plots, other, the groundwater and ISM plots that we discuss. Together, these plots show partitioning from the aqueous phase and the baseline to the sword phase, fall on treatment. They also show TCE reduction in the soar fest, TCE to DCE and DCE Ethane and Ethene in the aqueous face.
The third plot is QPCR groundwater data. The abundance of d helical coils is greater than the 10 to the fourth cells per mil threshold that we mentioned earlier. You obligate respires of chlorinated VOCs. They would not be present at these elevated abundancies if they weren’t breathing. The final plot is CSIA data from the ISMs. I’m sure many of you are knowledgeable at CSIA, but I’ll make sure everyone’s on board and I’ll give a quick review that doesn’t involve some eyeballing equations. I delivered the CSIA explanation around a great information, a great image that I found online. I’m not sure the explanation will be better any better than traditional way CSIA has explained, but you know, at least I got, the image into the webinar. I’ll count that as a success.
So isotopes or form of the same element that contain an equal number of protons, but different than number of neutrons. So they differ in atomic mass. The plot shows the isotopes of all elements on the periodic table with the atomic number. You know the number of protons in the x-axis and the number of neutrons on the y access. The color scale shows stability of each isotope with black being the most stable nonradioactive. CSIA measures the abundance of stable isotopes of the elements that can as compounds that are contaminants of interest.
The figure to the right shows, isotopes of elements that comprise the most chemicals of interest to radiation professionals. We can see from the figure that carbon, for example, has to stabilize isotopes for the atomic mass of 12 and 13. Carbon 14 is radioactive and not involved in typical environmental CSI diagnostics as often use for carbon dating organic compounds, and it’s even used in the environmental field for rate determining assets. But these are topics for another webinar. The relevance is that chemical bonds have lighter isotopes of slightly more reactive than bonds involving heavier isotopes. So the compounds with the heavier isotopes tend to accumulate and residual matrix. This is referred to as fractionation and it’s definitive evidence of destructive processes versus nondestructive processes that don’t have similar extra topic effects.
Here’s a slide for the visual learners, the LMI or flask represent samples collected from an MNM trade party, the arranged in order which they were collected with the left sample being collected before the party and the far right at the end of the party. And the first LMI you can see out of the package there are a lot more blue MNMS, you know, call them the lighter isotopes than the yellow MNMs call them the heavier isotopes.
Everyone knows that blue LMNs tastes much better than yellow MNMs, so they are preferentially consumed or eaten by guests increasing the ratio of yellow to blue or heavy to light isotopes. So if during the party we are given a sample, we can compare the initial out of the bag ratio of yellow to blue, MNMs, MNM ratio in the sample. If the ratio is greater in the sample, then we know the MNMs are being it. Same thing with isotopes. If the ratio of heavier to lighter isotopes increases from a previous sample or from a published literature value, then the initial isotopic signature of the manufacturing chemical, we know that degradation has occurred. So reporting gets a little confusing for CSIA. CSIA data expressed and relation to an international standard, dell and multiply by a thousand represented by the part per mil symbol.
For carbon, this and often results in a negative dell 13 see value as the initial international standard the PD is set at zero. It has a higher ratio of C13 to C12 and most things that we measure in the environmental field, so things we measure usually have a more negative dell 13 values. Now the practical part, here’s a plot of CSA data with time. The dell values increased from the first value measured. This fractionation is unequivocal proof of degradation.
Here’s a non-degrading data product added to the plot. The fractionation, that data product you see as related to the parent, the degradation bonds that involve C13 are still degrading, just slower, and they add up in the data product. Eventually, all the parents degraded. When this happens, the isotopic signature and the non-degrading daughter will match the initial isotopic signature of the parents. Here we see how complicated CSA can get with multiple degrading donna products, but the basics are TCE is fractionating. The isotopic signature, the non-migrating data product, the athene is approaching the initial isotopic signature, the TCE. And once the isotopic signature of the intermediate daughter is greater than the initial signature of the parent. That is definitive proof of degradation.
So let’s take a look at CSIA data collected from MW-6. The baseline pretreatment isotopic signatures of TCE and DCI or above the same minus 26 parts per mil. The round one, isotopic signature of TCE is fractionated and shows degradation with lighter signatures than the baseline about minus 24 parts per mil. The DCE shows a corresponding isotopic depletion. The C12 from TCE are dumped into the DCE, which increased the seat 13 to about minus 28 per mil. During the third round, the TCE continued to vaccinate to about minus 20 per mil, you know, continue to degrade and a DCE showed even a stronger fractionation or degradation to minus 12 per mil. This is definitive evidence that both the TCE and DCE or degrading. So based on the sorbet total VOC data, there is more DCE present round two, but the CSIA data shows definitively that, that DCE is degrading. This is consistent with the VOC data, where ethane dissolve VOC from the groundwater, where ethene and that thing we’re accumulating,
Hopefully, at this point, you’ll all see the need to incorporate contaminant degradation with activated carbon-based remedies. The table below is a summary of potential performance monitoring strategies for these combined remedies. Specific analytes will vary with the contaminant and degradation pathway and this being stimulated, but options are always derived from the reactants and products and the pathway. So here’s some modern strategy guidelines that should help focus the performance martin plants for your design. The top half of the table includes strategies for chlorinated solvents and the bottom half if for petroleum. The datatype gets a column of its own to emphasize the preference of direct and mechanistic data.
Empirical data is good, especially for delivery efficiency assessment, but I find a direct and mechanistic data more actionable and lead to quicker implementation of corrective measures and ultimately a more direct path to closure. The diagnostics in a matrix which are dictated by the affinity and activated carbon get their own columns. So let’s march through the table, beginning with the macronutrients, the electron donor for the treatment of the chlorinated solvents and the electronic petroleum.
Potential donor analytes include volatile fatty acid in dissolved organic carbon. Potential, acceptor her analytes includes all the oxygen out of trade sulfate. These parameters are great indicators to assess the stoichiometry and the design is progressing appropriately, appropriately or poor design. A check to see if they will be enough being depleted a to quickly to drive all the reactions. So it’s a check to make sure you put enough in the design phase.
Adding electronic donors and acceptors causes geochemical shifts. The list of potential geochemical shifts parameters can include ph, conductivity, alkalinity, we select on acceptors, oxidized donor like carbon dioxide, and even microbial groups such as, you know, totally eubacteria mythos antigens. There are many potential analytes and monitor geochemical shifts.
You wanna monitor the VOC is depends upon compounds on the compounds you want to monitor, generally expect most patrolling compounds and most chlorinate parent compounds to be present in soar fest. So ISMs will be needed to monitor these compounds if desired. VOCs is in the aqueous phase are generally a limited to less cybil sub, you know, less cybil chloro substitute VOCs like vinyl chloride. But when combined with CSIA vinyl chloride fractionation beyond that of the original PCE, TCE isotopic signature provides definitive evidence of degradation pathway from the aqueous phase long.
End products like ethane, ethane, propane, propane, or definitive as it gets as far as a solvent degradation. End product assessments petroleum’s a compounds is usually carbon dioxide. There are some isotopic techniques available to, can you even tie the carbon either generated or the origin of that carbon to petroleum products. CSIA is appropriate for whatever matrix to compound of interest is located, but care should be taken to make sure that the contaminant and fire degradation pathway result measurable fractionation, also called Richmond factor. Most do, but some don’t.
Stabilized to a probing is a technique that I haven’t mentioned yet. The technique involves labeling contaminants that is an electron donor and tracing the label to or components of a tenure microbes into dissolved and I get a carbon, the carbon dioxide. So this technique is generally appropriate for petroleum compounds, but not generally appropriate for chlorinated solvents. And because petroleum compounds are typically absorbed, stabilized, still probing studies usually done In Situ, microcosms. For more information on stabilized, still probing, you can visit the microbiome insights website, microbe.com.
Finally, microbial diagnostics. Microbio diagnostics provide great information on the facilitator, the buyer mediation pathway. On the chlorinator side, abundance abundances, specific microbes like DHC, you’re obligated and complete respires of clarinet cop pos provides very strong evidence that degradation along the hydrogen pathway. For petroleum, I like to look at reverse transcript ice. For enzymes needed for the pathway, I’m trying to stimulate. the RNA analysis, provides information not only on the genetic capacity or capability that micro, but indicates that the microbes actually making the enzyme.
So there are several options to demonstrate biotech degradation when using activity. Carbon plus bio combined remedies. And many of these options involve for a pre deploying for matrix In Situ microcosms. I liked direct measurements of VOC is using this technique. Yep. My favorite method of demonstrating degradation. It’s simple, inexpensive and easy to couple with advanced diagnostics and there’s one more benefit. It’s a great design tool.
This plot shows some of the full-scale design, radius and influence rationale you used for this Arkansas project. There are two things going on in this plot. The percentage VOC sore following the PlumeStop treatment and the potential romantic service increase during injections plotted with distance. Sore percentage on the left in blue had increase in orange and the ride. The present VOC score was calculated by comparing total VOC chlorinated VOC data from the aqueous phase to the data from the ISM from the sore phase. The ISM data was of course corrected for moisture. The plot shows that a distance of 80 feet, you know, 80% of the VOC is absorbed. So not only the ISM data provide, you know, be very useful for demonstrating degradation and also provides a method of designing a conservative well spacing.
So far, the focus has talked on PlumeStop plus bio. So let’s add iron to the mix. REGENESIS has applied there a particle steric stabilization chemistry to solve, and ZVI and WSP was among the first to use it. I was quick to adopt the technology because synergies between the pathways. Here’s some iron bio synergies. The first competitive inhibition between iron reduction and coordinative VOC reduction competing electron acceptors has been disproven. At least we’re from sub fleet concentrations that kept reasonable.
Iron improves conditions for DHC by removing concentration known inhibitors like sulfide TCA. I reduces also produce vitamin b 12 unnecessarily come with all and for hallow respiration. The alica cody’s can’t produce this component on its own. You know there are more iron bio synergies and case studies and listed in the groundwater monitoring mediation article I mentioned earlier.
Back to my PlumeStop plus bioplus ZVI combined remedy experience, the site is not only in Canada is in northern Canada. We found that battled freezing temperatures to perform the treatment last October. And unfortunately it has only recently thought out and performance data, which includes aquifer matrix ISMs aren’t in yet . What I can tell you is that the application is in a barrel configuration. You have 30 meters total injections were made in two rows with rye point injections made every three meters. We’ve got great distribution of the silty san in the silty sand matrix and the amendment was president within all monitoring wells within the barrier.
The injections were made at very low pressure play a maximum of 10 PIS. So there’s obviously, I kept obviously more to come with this, you know, from this date data from the site, but well the delivery went incredibly well and I know the chemistry works. So I’m very optimistic that the next data that we get will be favorable. So with that, I wanna turn it over to Maureen to go over a little bit more detail in the synergies of using PlumeStop with ZVI.
Maureen: Great. Thank you, Matt. Hey, so everyone out there send us your questions. I’m going to be wrapping this up pretty quickly. So email some questions. We’re going to have some time. I just wanna take it back to the big picture for a minute here. You know, when we’re looking at remediation strategies and what are some of the considerations like reactivity and persistence, you’ll, how does ZVI fit into this? You know, we have PlumeStop and bio remediation, you know, what can ZVI do to help us. Well, you know, it can really help in aspects of the reactivity and our ability to have a more rapid degradation and a number of different Components. But one thing you just stepping back on ZVI, it’s not that new. It’s been around for a long time. I even go back from my own experience probably 20 some years ago playing around with ZVI and DDT, but there are things that are new now and in what was different than it has been, I think predominantly the ability to deliver it when you’re considering in situ applications.
And so, now that we have a colloidal ZVI that can be injected under low pressure, it opens up a lot of really new opportunities. So, you know, again, why would I want to think about ZVII? You know, I think number one, you know, I’m just gonna skip to this next slide. If you could hit a biotic reduction reaction that may help bypass the VC. So, so we know about that. So that’s something that we’re familiar with and I think it can be really beneficial in our PlumeStop applications in that, you know, the VC doesn’t have thesame sort of isotherm that’s something like PCE has. So it can help if you’re trying to manage degradation products.
I think the other point is, is Matt brought out that there’s a lot of synergies and there’s a greater deal of understanding or new understanding that’s coming about the in essence iron makes bio better and bio makes iron better. So the combination of the two creates a situation where you’re gonna have faster reactions, better mass reduction, and again, that quicker costs to closure. I mean that’s really what we’re all going for here. and another point, so hey, so what do we have as far as REGENESIS? We have the aqua ZVI and the micro ZVI. What’s different? We may at mentioned sulfation, why that’s important. This is the ability to treat the iron with reduced iron that’s going to help with reactions. And what that means is when iron will react with water, now there’s some benefits to that. It’s gonna create hydrogen and that helps with your biological processes. But if you wanna have some additional persistence, the cell foundation is going to help with that. It also allows for more selective it, so you’re gonna be more selective to treat in the TCE versus just reacting with the water. For more information on that, go to our webinar, go to our page and REGENESIS, look for john, Dr. John Frim’s [SP] webinar. He’ll get into some detail on that.
So anyway, and so micro ZVI, that’s our ZVI that again, it’s colloidal, that’s gonna be in a glycerol, that’s, that’s a product that we’re gonna use and we’re gonna mix with other ERD reagents so you can use with PlumeStop, you can use with an ERD reagent. And you know, again, the big point here is these materials can be suspended versus other ZVI materials and can be distributed like PlumeStop and I’m just gonna move on here is like PlumeStop and it’s going to allow you to get that distribution and that’s what’s a little different.
So with that I wanted to try to see what kind of questions we have here and see if we can help answer your question, but really thank you very much for your time. You know, there’s more information coming on sites that we have PlumeStop and ZVI and watch our website. I have several projects that went in just in, you know, the Q-four last year, data are coming in. We’re seeing rapid reductions on a big fan of including the ZVI, you know, with the PlumeStop and the bio amendments because we’re getting more rapid reductions in the cost with that. We can often adjust the reagent mixtures and it may not be that much of an increase in costs because we have software and our ability to design these by looking at isotopes and degradation rates and try to come up with the most efficient way to deal with your site and meet those objectives. So, Dane, I don’t know if you have any questions here that look good?
Dane: Yes. Thanks, Maureen. Oh, we do have some questions we have a little bit of time to get to some of them. So just that’s gonna conclude the formal section of our presentation. And before we get into the questions, just a couple of reminders. First, you’re going to receive a follow-up email with a brief survey. We really appreciate your feedback. So please do take a moment to let us know how we did. Also right after the webinar, you’ll receive a link to the recording as soon as it is available.
Okay. So we do have a lot of questions. If we don’t get to your question before time runs out, we will make an effort to follow up with you after the webinar. Okay. So let’s see here. Getting, a couple of questions about PlumeStop. Are there any long-term studies with PlumeStop ? Will it break down and rerelease contaminants?
Matt: Hey, Dane this is Matt Burns. So activated carbon has been used for an awfully long time and what effects it and the isotherms over very, very well defined. So the things to watch out for with the application of PlumeStop is due to realize that activated car even has a finite capacity and having a co-applied or combined remedy that includes a degradation mechanism to keep the carbon clean and to keep those captions sites available. And from, you know, from reaching its capacity is incredibly important and monitoring to make sure you have the degradation pathway is also incredibly important.
Dane: Okay. All right. Um, let’s see here. Next question is, can you reapply degradation products without adding more PlumeStop if contaminants persist?
Matt: Yes. And for that Arkansas site, that is the basis of our design. So the PlumeStop of course, you know, cost more than just adding the biostimulants alone, which are relatively cheap. So the ONM plan for the Arkansas side is to no longer add any more pumps. Stop. We stop was added initially as part of the capital costs, the initial implementation. So every few years we expect that we’re gonna have to go out and add more a bio stimulant, maybe some micronutrients. So definitely you do not need to add more v wants. It’s already applied that activated carbons there and just need to keep it clean by stimulating the degradation mechanisms.
Dane: Okay. Next question is a two part question. Does the bio degradation occur on the dissolved phase only and then is the sorbed phase not bioavailable?
Matt: Well, I guess that’s how small you have large, you wanna draw your black box. So my microbiologist friends tell me that you cannot get degradation on the swarm face, like something that’s in the solid phase. But there’s a lots of stuff that go on and very, very, very close distances, you know, in desert technically dissolved but associated with the sword face. So I’ve noted bio gac and degradation on activated carbon. You activated carbon is completed, is incredibly efficient and I think there’s a decent amount of studies that show that and more information on the enhancements of activated carbon on degradation, check out that webinar, that door a tiger gave that’s archived on the REGENESIS a website. I dropped my back box pretty large when it comes to that. I don’t get caught up in the semantics of does degradation actually occur on the subsurface or not? It occurs.
Dane: Okay. Excellent. Alright, so maybe time for one more question. Would PlumeStop and AquaZVI work on a low-level 11DCE and vinyl chloride plume?
Matt: Sure, yeah. As long as there’s no inhibitors and that sort of thing, so you need to know you, you know, do your normal design homework and make sure you’re designing your amendment formulation perfectly. But do you have anything to add to that one Maureen?
Maureen: Yeah, and I think it’s important to note is I mentioned we have software that allows us to incorporate isotherms of different chemicals, biodegradation rates and that again will allow us to come up with the right design mixture. I personally for the compounds that you’re mentioning. I certainly would consider ZVI bio and Aqui ZVI the application and I think it would be quite appropriate.
Dane: Okay, great. So we are out of time. Thank you so much matt and Maureen. That’s gonna be the end of our chat questions, so if we did not get to your question, someone will make an effort to follow up with you. If you would like more information about engineering solutions from WSP, please visit wsp.com. if you need immediate assistance with a remediation solution from REGENESIS, please visit regenesis.com to find your local technical representative and they will be happy to speak with you. Thanks again very much to Matt Burns and Maureen Julie, and thanks to everyone who could join us. Have a great day.