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Site Closure Sought after using ORC® Biobarrier to Enhance Aerobic Biodegradation of MTBE and TPHg
CASE SUMMARY
Former Service Station – Bishop, CA
Extensive methyl tertiary-butyl ether (MTBE) and total petroleum hydrocarbons as gasoline (TPHg) contamination was discovered within the subsurface as a result of leaking underground storage tanks (USTs) at a former service station. Following the removal of the leaking USTs, a total of 1,192 cubic yards of gasoline- impacted soil in the source area was excavated and transported off-site for treatment. Monitoring following the excavation activities revealed residual source contamination found in the capillary fringe immediately downgradient near Wells MW-6 and MW-7. Concentrations in Well MW-6 exceeded 7 parts per million (ppm) MTBE and approximately 11 ppm TPHg. Efforts to further delineate the plume revealed petroleum contamination extending 1,700 feet downgradient from the source. Early efforts were made to treat the downgradient plume utilizing an air sparging/vapor extraction system placed 800 feet downgradient from the site of the original release. This approach proved to be effective as MTBE and TPHg were reduced to non-detect levels downgradient from where it was installed. However, the source area continued to reveal MTBE and TPHg concentrations above the cleanup goals enforced by the California Regional Water Quality Board. To treat the source area and bring the site to closure, an enhanced bioremediation barrier (biobarrier) was designed and implemented using Oxygen Release Compound (ORC®).
REMEDIATION APPROACH
To address the source area, a total of 950 pounds of ORC was mixed with water to form a slurry and injected via direct-push technology. The 3 row ORC biobarrier was applied immediately downgradient from the release area (Figure 1). Wells MW-6 and MW-7 were monitored to observe the effectiveness of ORC.
RESULTS
The post-ORC injection monitoring results show an effective reduction of MTBE and TPHg within one year. Well MW-6 indicates two MTBE concentration spikes likely caused by residual contamination from the soil entering into the groundwater (Graph 1). However, an MTBE reduction of 94% occurred between day 210 and 300 and concentrations reached non-detect shortly afterwards. TPHg concentrations declined by 70% within the first 30 days and continued on a downward trend, reaching non-detect levels approximately one year after the application.
In Well MW-7, reduction occurred immediately after injection with an MTBE decrease of 88% by day 120 (Graph 2). Concentrations reached non-detect less than a year after the ORC application. TPHg levels declined similarly to MTBE and reached non-detect in less than one year.
The effective treatment of MTBE and TPHg using ORC resulted in non-detect levels of both contaminants and has allowed the consultant to seek site closure status from the regulatory agency.
In Situ Aerobic Bioremediation vs. AS/SVE Cost Comparison at UST Site
REGENESIS® Demonstrates Effective Cost-Savings Using ORC®
Project Highlights
- An in situ aerobic bioremediation pilot test demonstrates a cost-effective treatment option vs. traditional Air Sparge and Soil Vapor Extraction (AS/SVE) system
- Within one month, benzene concentrations were reduced from baseline concentrations of 200 ug/L to non-detect (>5 ug/L)
- Approach using ORC® resulted in a $79K savings vs. traditional mechanical treatment option
Project Summary
The site of a former gas station with leaking underground storage tanks (LUSTs) was chosen for a pilot test to demonstrate the effectiveness of ORC® in treating the existing benzene (BTEX) and MTBE concentrations. In addition to the pilot test, a cost-comparison was also prepared to illustrate the potential for cost-savings associated with the use of a passive, innovative technology like ORC vs. a traditional AS/SVE remediation system.
For the pilot test a 20 ft. x 20 ft. area, with the highest concentrations of BTEX and MTBE, was treated with 180 lbs of ORC. BTEX concentrations within this area varied from 200 ug/L to 2100 ug/L from low and high groundwater elevation, respectively. ORC was injected into 10 points from 8-14 ft bgs to ensure ample coverage of the sand layer and some of the smear zone.
Technology Description
Oxygen Release Compound (ORC) is an engineered, oxygen release compound designed specifically for enhanced, in situ aerobic bioremediation of petroleum hydrocarbons in groundwater or saturated soils.
Cost Comparison Analysis
A cost comparison analysis was prepared by the consultant for the Indiana Department of Environmental Management (IDEM) to show a comprehensive cost savings using ORC versus the AS/SVE system for full-scale treatment of benzene and MTBE. This cost comparison is illustrated in Table 2 and includes the initial full-scale ORC application costs as well as a second application at 50% of the initial application cost. This second application is shown as an “insurance policy” in the event that more ORC is needed to complete the remediation. The AS/SVE costs are reflective of the design, installation, and operation of such a system for two years. Based on the analysis, the use of ORC represents ~59% of the cost of the AS/SVE option or a potential savings of $79,451. If a second insurance application is avoided, then the savings are $79,451 (initial saving) plus $39,1529 (cost for re-application) equaling $118,603.
Results
Within one month, benzene concentrations in the low groundwater elevation were reduced from baseline concentrations of 200 ug/L to non-detect (<5 ug/L). Dissolved oxygen content also increased dramatically from <0.5 ppm (baseline) to >20 ppm post application. A successful full-scale application was designed using 4,000 pounds of ORC, which will save the client >$79K versus a traditional AS/SVE system.
PCP Bioremediation at Eastern Virginia DoD Wood Dip Tank Site
Site Summary
This site is the location of a former Department of Defense dip tank with associated storage racks that has been used to treat wood with a mixture of pentochlorophenol (PCP), diesel fuel and kerosene. The dip tank was dismantled in 1982 and the area was paved with asphalt and converted to a storage area. Subsequent soil and groundwater sampling indicated that PCP was present in both media, with soil concentrations greater than USEPA Region III Risk-Based Contaminant Levels and groundwater concentrations greater than USEPA Maximum Contaminant Levels (MCLs). In 1999, a soil excavation took place at the site removing all the soil above the water table with a PCP concentration greater than 16 mg/kg and the removal of one to three feet of soil below the water table. In 2000, a treatability study was conducted to evaluate the in-situ aerobic bioremediation) of PCP in the groundwater using Oxygen Release Compound (ORC®).
Remediation Approach
- Remediation Objective: Determine the efficacy of using ORC for the reduction of PCP concentrations in groundwater.
- Application Type: Grid (direct-push injection)
- Product: ORC
- Quantity Applied: 1,400 lbs
- Application Rate:
- Upper Aquifer: 6.3 lb/ft
- Lower Aquifer: 3.0 lb/ft
- Product Cost: $14,000
Site Characteristics
General
- Name: DOD Wood Dip Tank Site
- Location: Eastern, VA
- Industry: Wood Treatment
- Contaminants of Concern:
Hydrogeology
- Treatment Area: 5,000 ft2
- Soil Type: Fine to medium sands
- Groundwater Velocity: 0.3 ft/day
- Groundwater Flow Direction: Southwest
- Depth to Groundwater: 5.3 ft
Results
Conclusion
The treatability study performed at the site validated the prediction that ORC-facilitated bioremediation could successfully degrade existing PCP concentrations. After 250 days of observation, sampling of the source well, MW-27S, indicated the successful degradation of PCP by 95.9%. Other wells further from the source also responded well to ORC treatment. Data for each well begins at different time periods following the treatment date because some wells were added after treatment occurred, specifically MW-26S and MW27S. Due to the likely remediation that took place before concentrations were monitored, it is hypothesized that initial concentrations and overall contaminant reduction in MW-26S and MW-27S were higher than existing data indicates. Therefore, it is assumed that the ORC treatment could have performed even better than data indicates.
In Situ Chemical Oxidation of Chlorinated Solvents Using Persulfox™ At An Industrial Site
Overview:
Chlorinated compounds were discovered in shallow groundwater at a former industrial site in Attleboro, Massachusetts. With total VOC concentrations as high as 85,000 ug/L in groundwater, a rapid and aggressive remediation approach was required. In Situ chemical oxidation (ISCO) using PersulfOxTM – catalyzed persulfate was selected to treat a portion of the impacted area which was approximately 35’ long x 35’ wide x 15’ deep and primarily comprised of sand. Three prescribed injections of ISCO using PersulfOx were performed over a 7- month period.
- PersulfOx is a persulfate based ISCO reagent that promotes rapid and sustained in situ oxidation of a wide-range of organic contaminants.
- This patented technology utilizes a unique catalytic surface on which oxidants and contaminants react in a process known as “surface mediated oxidation.”
- PersulfOx also contains built-in activation which eliminates complex and potentially hazardous chemical addition required to achieve traditional persulfate activation.
- From a health and safety aspect, the use of PersulfOx alone is safer than traditional activation methods such as heat, chelated metals, hydrogen peroxide or base.
- If warranted, PersulfOx can also be activated through traditional means to achieve site remediation goals.
Figure 1. Injection wells and monitoring wells
A 10% solution of PersulfOx in water was mixed and injected into a 10-foot treatment thickness using 3 injection wells within the vicinity of monitoring wells MW-16D, MW-16S and MW-8 (Fig.1).
Results:
After each PersulfOx application, an anticipated increase and subsequent decrease in VOCs (resulting from subsurface disturbance and contaminant desorption) was observed. After the 3 prescribed applications of PersulfOx, 2 of the treatment zone wells, MW-16D and MW-8, measured significant VOC removal, 81% and 99% respectively. Treatment zone well MW-16S (the most highly impacted—starting at 85,000 ug/L) showed a significant increase in VOCs after the first 2 injections (indicative of the liberation of soil bound mass). After the third application of PersulfOx, VOC concentrations in MW-16S were clearly decreasing (see figures below).
Petroleum Hydrocarbon and Chlorinated Solvent Treatment Using PersulfOx™ at a Former Service Station
Overview
Petroleum hydrocarbons and chlorinated compounds were discovered in groundwater at a former gasoline service station/auto-repair facility. This redevelopment site, located in Bronx County, New York, previously housed an underground storage tank (UST) used for gasoline storage. Following the discovery of groundwater contamination in excess of NYSDEC groundwater protection standards, the UST and soils were removed to bedrock at a depth of 11 feet. Further monitoring revealed toluene and benzene contamination as well as tetrachloroethene (PCE) and trichloroethene (TCE) impacts from parts cleaning associated with the on-site auto-repair shop. Remedial action was required to restore site groundwater and make way for redevelopment and construction of a new building. In Situ chemical oxidation (ISCO) using PersulfOxTM was chosen as the remediation approach.
- PersulfOx is a persulfate based ISCO reagent that promotes rapid and sustained in situ oxidation of a wide-range of organic contaminants.
- This patented technology utilizes a unique catalytic surface on which oxidants and contaminants react in a process known as “surface mediated oxidation.”
- PersulfOx also contains built-in activation which eliminates complex and potentially hazardous chemical addition required to achieve traditional persulfate activation.
- From a health and safety aspect, the use of PersulfOx alone is safer than traditional activation methods such as heat, chelated metals, hydrogen peroxide or base.
- If warranted, PersulfOx can also be activated through traditional means to achieve site remediation goals.
The ISCO treatment system consisted of a series of pipes extending below the basement level of the existing slab for the specific purpose of delivering PersulfOx directly onto the bedrock surface. The pipes terminated into dispersion pits scraped into the bedrock allowing PersulfOx to pool and enter the fractures (Figure 1). The ISCO delivery system design allowed for multiple reagent applications as often as required to complete the remediation process.
Current trends in the available monitoring well data indicate significant reductions in total VOCs (Figure 2).
CASE STUDY: SOIL BOUND BTEX TREATMENT AND ACTIVE REMEDIATION SYSTEM INTEGRATION
Purpose:
The purpose of this pilot study was to demonstrate the feasibility of using PetroCleanzeTM to desorb petroleum contaminants from the soil into the dissolved phase where they can then be treated by physical extraction or an active remediation system.
Background:
A biosparge system was used at the site until groundwater concentrations dropped below cleanup target levels (approximately 2 years), then it was shut down. Rebound occurred during post-active remediation monitoring and groundwater concentrations increased above natural attenuation default concentrations. The observed increase in dissolved contaminant concentrations, combined with high organic vapor analyzer readings in saturated soil samples, and elevated fraction of organic carbon and total organic carbon concentrations in the soil, suggested petroleum contamination was likely absorbed to organics in saturated soils and was slowly desorbing into the groundwater. An approach was needed to liberate bound hydrocarbons for additional treatment using the biosparge system.
Pre-Injection Baseline Analytical:
On January 12, 2012, baseline groundwater samples from monitoring wells SW-6R, -17R, and 18 (Figure 1) were collected for BTEX (benzene, toluene, ethylbenzene, xylene) and TRPH (total recoverable petroleum hydrocarbons) analysis (Figure 3, 4). On January 13, 2012, two soil borings (SB-1 and SB-2) were completed and baseline soil samples were collected from 12-14 feet below land surface for BTEX analysis (Figure 2). Figure 2 shows the average soil BTEX concentration for SB-1 and SB-2 before and after PetroCleanze injection.
PetroCleanze Injection:
On February 2-3, 2012, a total of 2,220 gallons of 5% solution of PetroCleanze was injected into four injection points surrounding SW-18. Each point received a total of 550 gallons of solution, including 220 lbs of RegenOx Part A, 240 lbs of PetroCleanze, and 500 gallons of water. The biosparge system was reactivated for the duration of the treatment event.
Post-Injection Analytical:
On March 12, 2012 and July 10th, 2012, groundwater samples from groundwater monitor wells SW-6R, -17R, and -18 were collected for BTEX and TRPH analysis (Figure 3, 4). Also on March 13th and July 23rd, 2012, two soil borings (SB-1 and SB-2) were completed and soil samples were again collected for BTEX analysis (Figure 2).
Results:
Performance parameters were evaluated for SW-6R, -17R, and -18 and a marked increase in ORP values was observed in each of the three wells following the PetroCleanze injection indicating chemical oxidation activity. Additionally, the pH in wells SW-17R and -18 increased significantly, providing evidence that alkaline conditions resulted from the application of PetroCleanze. As anticipated, increases in TRPH and BTEX concentrations in the sampled wells were observed following PetroCleanze injection as compared to baseline (Figure 3, 4). SW-17R was slightly unique in that BTEX concentrations went down. When looking at the average soil BTEX concentration of the two soil samples (Figure 2) in January, March, and July 2012 (7,015, 3,977, and 657 μg/kg, respectively) there was a 43% reduction between January and March and a 91% reduction between January and July 2012 after continued biosparging treatment.
Conclusion and Recommendations:
The PetroCleanze application was successful and the material easily applied. Performance exceeded expectations as only one injection was needed to strip 91% of the BTEX contamination from the soil into the dissolved phase. The reactivated biosparge system was able to treat the increased dissolved phase contaminants in the treatment area.
The current groundwater concentrations at the site are very low in key monitoring wells; therefore, the project does not require additional treatment at this time. However, should a change in contaminant concentration be observed at the site once active remediation has been ceased then additional treatment will be considered.
Combined Remediation Approach – Dual Phase Vacuum Extraction with In Situ Chemical Oxidation
Introduction
When redevelopment of an old service station was proposed, site investigations revealed a significant petroleum hydrocarbon impact within the soil and groundwater. The subsurface contamination threatened to derail the redevelopment program and a rapid remediation strategy was needed to reduce concentrations to acceptable levels. Geo2 Remediation was contacted to remediate the site in order to allow safe development for luxury residential properties while ensuring no impact to local protected controlled waters.
Figure 1. Successful Site Remediation Leads to Luxury Residence Redevelopment
Project Background
Geo2 Remediation carried out the treatment of a former service station following historic leakage from underground storage tanks (USTs). The tanks had been removed prior to the beginning of the site investigation. Free product was discovered at the surface of the saturated zone and elevated concentrations of total petroleum hydrocarbons (TPH) were observed within the groundwater. Concentrations of TPH as high as 290 mg/L were discovered within the source area.
In Situ Physical Remediation
Geo2 Remediation installed a dual phase vacuum extraction (DPVE) system, designed to rapidly remove phase separated product identified on the surface of the groundwater. The DPVE system began treatment in September 2007. Thicknesses of free product up to 50mm, identified around the former tank farm, were removed within 1 month of commencing treatment. Within the groundwater, TPH concentrations were reduced to between 300 mg/L and 150 mg/L over a 5-month monitoring period. In order to increase the efficiency of the DPVE system, Geo2 augmented the physical treatment system with RegenOx to provide a rapid reduction in soil and groundwater concentrations and allow redevelopment to proceed on schedule.
Combined In Situ Physical Remediation and Chemical Oxidation
Geo2 Remediation applied RegenOxTM, a safe and easy to apply proprietary in situ chemical oxidation (ISCO) designed to provide rapid concentration reduction of contaminants without a violent exothermic reaction or other handling difficulties common to ISCO reagents. RegenOx was injected into the subsurface around the dissolved phase impact following DPVE system shutdown using a direct-push injection rig. Two applications were completed within one week of each other using a modest dose of 326 kg RegenOx to achieve sorbed-phase desorption and partial chemical oxidation of the residual hydrocabons. The DPVE system was then restarted to remove the resulting desorbed contamination and partially oxidised hydrocarbon species from the groundwater – this enabled the Reagent requirements to be kept to a minimum (i.e. partial contaminant oxidation rather than full contaminant oxidation) whilst capitalising on the use of the DPVE system already in place. The total cost of the RegenOx application – including all fieldwork – was approximately £ 5,000, the cost of one month’s DPVE operation at the site.
RegenOx® Basics
RegenOx® is a proprietary two-part chemical oxidation product developed and sold by Regenesis for in situ groundwater treatment. It combines the use of a controlled-release percarbonate-based oxygen compound with a proprietary multi-part catalyst to generate surface-mediated free-radical generation and contaminant oxidation (e.g. perhydroxyl radical, hydroxyl radical and superoxide radical), with reactive power comparable to that of Fenton’s reagent but with greatly facilitated handling and subsurface delivery / longevity (up to 30 days). This provides an effective contaminant oxidation reaction without violent exothermic reaction, and can therefore be handled using a wide range of standard field equipment (e.g. direct push injection rigs) or applied directly to excavations. Furthermore, it is alkaline and can therefore be used in calcareous formations in addition to sands and gravels etc.
RegenOx-enhanced Contaminant Desorption
RegenOx has been designed as a bespoke remediation product to provide advantages in usage and application over commodity chemical products used for ISCO (e.g. permanganates, persulphates, peroxides). One of the design features it includes is reduced losses onto the aquifer matrix, commonly known as the matrix Natural Oxidant Demand (NOD). This is achieved by RegenOx through a powerful desorption / surfactant effect of the combined product (principally the catalyst) that draws the contaminant off the soil surface and into solution / onto the catalytic surface where localised free-radical generation occurs leading to focused contaminant destruction. This restricts the oxidant losses onto tightly bound and heavier soil organics such as humics, roots, and other natural or immobile fractions. At the same time, RegenOx is purely inorganic therefore adding no organic surfactant to the system that may prevent a competitive oxygen sink to on-going contaminant biodegradation.
The present project makes use of this product feature to combine in situ chemical oxidation with enhanced physical mass recovery. RegenOx-desorbed contaminant mass and partially oxidised (more soluble) organic species are recovered via groundwater abstraction using the DPVE system, whilst further contamination is destroyed in situ by oxidation.
Results
Upon completing the RegenOx applications, desorption from the highly impacted soils produced a temporary increase in groundwater hydrocarbon concentrations to a maximum of 4,800 mg/L. One week after the second application was completed, the DPVE system was re-started, rapidly reducing the TPH concentrations in the groundwater to an average of 20 mg/L. The improved efficacy of the DPVE system can be seen in Graph 1 where the linear trendline of MW-2 before and after the RegenOx applications shows a conservative 80% reduction in contaminant concentrations within two months – effectively increasing the DPVE efficiency by more than 500% at this stage in its operation. Once the DPVE system was switched off, further monitoring showed that there was no rebound in groundwater hydrocarbon concentrations due to the augmentation process successfully reducing the sorbed TPH concentrations of the soils.
RegenOx Treats #2 Fuel Oil Plume Beneath Residential Home
CASE SUMMARY
Home Heating Oil, New Jersey
A 550-gallon leaking underground storage tank (UST) containing #2 fuel oil was removed from a single family residence in New Jersey (Figure 1). In addition, the surrounding soil was excavated and sampling was performed to determine the extent of the petroleum hydrocarbon plume within soil and groundwater. The plume was delineated at approximately 1,800 ft2 with
concentrations of total petroleum hydrocarbons as high as 40,000 parts per million (ppm) in soil and approximately 40,000 parts per billion (ppb) in groundwater. An estimated 20% of the plume was determined to be located beneath the home itself, eliminating the option for extensive soil excavation. Other remedial strategies such as pump & treat, monitored natural attenuation, and enhanced fluid recovery were ruled out as they did not provide a timely, cost-effective solution.
Figure 1. Residential Site
- Soil Type: Fine to Medium Sands
- Treatment Thickness: 5 to 12 feet bgs
- Free Product: 1” to 3” observed
- Contaminants of Concern:
- TPH – Total Petroleum Hydrocarbons
- TVOC – Total Volatile Organic Carbon
- TSVOC – Total Semi-Volatile Organic Carbon
| Contaminant | Concentration |
| TPH – soil | 40,000 ppm |
| TVOC – gw | 7,900 ppb |
| TSVOC – gw | 40,000 ppb |
REMEDIATION TECHNOLOGY
In Situ chemical oxidation (ISCO) using RegenOxTM was chosen as the most appropriate technology to treat the soil and groundwater plume. In addition, an application of a slow-release oxygen compound, ORC Advanced®, was applied following RegenOx to stimulate aerobic biodegradation of any residual contaminants. RegenOx was applied based on the following:
- Least disruptive to the homeowner
- Successful track record
- Feasible site conditions – sandy soils and a shallow water table paired well with direct-push injection
- Low natural organic carbon in saturated zone
- Safe to use and easy to apply
Ten permanent injection points were installed around the source area, at the edge of the plume and beneath the house in the crawl space as seen in Figure 2. During the installation, free phase product was observed in monitoring wells at approximately 1 to 3 inches. The NJDEP’s Permit-by- Rule prohibited the injection of any remediation technology should free product be present. Once the removal was complete, RegenOx could be applied as designed.
CONTAMINANT PLUME TREATMENT
Free Product Removal
The free product was removed using a mild surfactant and a high powered vacuum extraction truck within the source area. This process also effectively distributed the surfactant across the impacted zone for further desorption of contaminants from the soil matrix. Three free product recovery events were performed which effectively removed all free product from the wells and surrounding areas. TVOC concentrations in groundwater dropped only slightly as a result of the free product removal. However, concentrations of TSVOCs more than doubled in groundwater as a result of desorption from soil.
ISCO Injection for TPH Reduction
The application design included two RegenOx injection events and a third combined RegenOx and ORC Advanced injection for on-going biostimulation to treat residual contaminants. Using temporary and permanent injection points, a total of 6,210 pounds of RegenOx was applied from 5 to 11 feet bgs. The third injection included 650 pounds of ORC Advanced.
Conclusion
No free product, sheen or film was observed after the injections were completed (Figure 5). Levels of dissolved oxygen 30 days following the final application were measured at approximately 10-20 ppm indicating the presence of ORC Advanced in the subsurface.
Within 6 months, significant reductions in petroleum hydrocarbons were observed. TVOCs declined from 7,900 to <50 ppb and TSVOCs were reduced from 40,000 to <150 ppb. Further Action status from the NJDEP. The site is currently seeking No Further Action status from the NJDEP.
Combined Technologies Replace Pump and Treat System
Manufacturing Facility Remediated Using Bioremediation, Bioaugmentation and ISCR
Project Highlights
- Combined technologies of bioremediation and ISCR were used to treat the PCE
- The remediation design replaced a costly legacy pump and treat system
- More than $200,000 per year saved by shuting down pump and treat system
- RRS’ injection strategy allows for the coapplication of BDI Plus, 3D-Microemulsion and CRS during the same mobilization event
Project Summary
Historic activities at an active manufacturing facility contaminated a sand aquifer with chlorinated solvents (primarily perchloroethene, PCE). Previous remediation activities included an extensive pump and treat system as well as other in situ activities. The cost of operating the pump and treat system was such that the client looked for a more cost-eff ective remediation approach. Regenesis Remediation Services (RRS) combined bioremediation/in situ chemical reduction (ISCR) approach proved to be cost-effective as a replacement technology for the pump and treat system, saving the client more than $200,000 per year. This remediation solution was installed both inside and outside of the manufacturing facility during winter in sub-zero temperatures.
Remediation Approach
Four treatment rows of a total 48 injection points were used to apply the product with a treatment area of 5-30 feet below ground surface.
The following in situ remediation technologies were used:
- 19,300 pounds of 3-D Microemulsion FE®
- 48 liters of Bio-Dechlor INOCULUM Plus®
- 2,400 pounds of Chemical Reducing Solution (CRS®)
Technology Description
3-D Microemulsion FE is an engineered electron donor material that off ers a novel 3-stage electron donor release profi le, pH neutral chemistry and is delivered on-site as a factory-emulsifi ed product. When injected into the subsurface, this stimulates bioremediation of the pollutant by the process of biologically enhanced reductive dechlorination. Bio-Dechlor INOCULUM Plus is an enriched natural microbial consortium containing a high density of Dehalococcoides sp. (DHC). This microbial consortium, when added to the subsurface augments the naturally occurring population of microbes that carry out the desired reductive dechlorination process. CRS (Chemical Reducing Solution) is a soluble iron substrate designed to easily distribute to an aquifer and stimulate that serves to stimulate the abiotic in situ chemical reduction (ISCR) of halogenated hydrocarbon contaminants.
Turn-Key PCE Plume Remediation on at Michigan Superfund Site
Former Manufacturing Facility Treated with 437,000 Pounds of PersulfOx® in 18 Days
Project Highlights
- PersulfOx was selected over other persulfate activation methods because of its inherent health and safety benefits and easy-of-use.
- An aggressive application schedule was implemented to satisfy stakeholders – 37,800 lbs (15,500 gallons) of PersulfOx were injected in a single day.
- On-site diagnostics conducted by RRS confirmed PersulfOx distribution throughout the targeted treatment area.
- The project was completed ahead of schedule and on budget.
- The site was left with minimal impact to the PGA Championship Golf Course.
Project Summary
A former manufacturing facility in Western Michigan was redeveloped into an active golf course. The USEPA took over responsibility for cleanup of the chlorinated solvents that remained. Regenesis Remediation Services (RRS) was contracted by a leading consulting fi rm to implement a remediation design to address the chlorinated VOC plume with concentrations as high as 3,000 ppb. PersulfOx was selected over other persulfate activation methods such as hydrogen peroxide or alkaline activate on because the built-in catalyst minimized hazardous materials handling allowing for a safer and easier application. This was especially important because of the treatment areas close proximity to a sensitive receptor (river). Despite persistent freezing temperatures, RRS was able to finish this project ahead of the projected schedule. The RRS team faced a unique challenge on this site as it is a PGA Championship Golf Course which required extreme caution while injecting on the course. Strategic injection point placement, equipment staging, and surface protection via mats were just a few of the techniques implemented by the team
Remediation Approach
The 18-day injection event included 437,000 pounds of PersulfOx which was applied through 129 injection points in a grid pattern 5-30 feet below ground surface. The team used two direct-push injection machines to apply PersulfOx into eight points injection simultaneously.
Technology Description
PersulfOx is a sodium persulfate-based chemical oxidation technology which destroys both hydrocarbon and chlorinated solvent-type contaminants in the subsurface. PersulfOx contains a built-in catalyst which activates the persulfate componentand generates contaminant-destroying free radicals without the need for the addition of a separate activator.
