Presentation on theme: "1 Redox Tech, LLC Fundamentals of In-Situ Remediation Providing Innovative In Situ Soil and Groundwater Treatment."— Presentation transcript:
1 Redox Tech, LLC Fundamentals of In-Situ Remediation Providing Innovative In Situ Soil and Groundwater Treatment
2 Redox Tech, LLC Business founded in Headquarters in Cary, NC. Other offices in GA, SC, IL, MA, and CA. New England Office opened in In situ treatment with biological and chemical manipulation, both reduction and oxidation – over 800 projects completed. In situ Soil Blending.
In Situ Remediation is a TOOL!
Site Characterization for In Situ Treatment Designs Horizontal and Vertical Delineation; MNA Field Measurements (Ph, ORP, and DO); Alkalinity, Dissolved Iron, Sulfate, etc… Site Geology; Total Oxidant Demand (TOD); Utility Locations; and Nearby Receptors.
5 In Situ Remediation – The Design Delivery and Chemistry are Key Requires fundamental understanding of geochemistry and microbiology. Requires confidence in the consultants work. Requires delivery that mimics the target contaminant distribution. Without both proper data, delivery and formulation, remediation likely to fail. May require Pilot Study.
6 Total Oxidant Demand (TOD) Water-phase contaminant is not only material that will be oxidized Sorbed phase contaminant Free-phase contaminants Naturally-occurring organic material (NOM) Reduced soil and water minerals Can be estimated with site data
7 Total Oxidant Demand Total Oxidant Demand can vary between <0.1 to 155 g/Kg
8 Treatment Classes Chemical Oxidation Chemical Reduction Aerobic Bioremediation Anaerobic Bioremediation Metals Stabilization Thermal (steam)
9 Chemical Oxidants Permanganate – widely used for chlorinated alkenes, PCE, TCE, DCE, VC Peroxide (Fentons) – relatively inexpensive, but can be difficult to inject Persulfate – replacing many peroxide applications because of safety and gas generation Ozone – still occasionally used for gas stations
Base Activated Sodium Persulfate Competes with permanganate, Fentons chemistry, ozone and peroxide; Oxidizes a broader range of organic contaminants than permanganate ; Oxidizes more compounds than Fentons chemistry and does not have gas generation; Slower reaction time than other oxidants which can translate to less rebound; and Much safer to handle than other oxidants.
Sodium Persulfate Injection Enfield, CT Gasoline Release in the 1980s; Remediation activities included product recovery, SVE, pump and treat and soil excavation; Following 20+ years of remediation, groundwater concentration were still elevated under the roadway and nearby properties; and Redox Tech NE was invited to bid on a Fentons Reagent design and proposed activated sodium persulfate as an alternative.
Plume is approximately 17,000 Square Feet
Injection Design 17,000 square foot treatment area; Average TVOC approximately 18,000 ppb; 5 to 7 foot thickness; 44 injection points (2 rounds); 54,000 lbs of sodium persulfate; 450 gallons per point; 2 target depth intervals; and Completed in 11 days;
Groundwater Treatment Results Average TVOC approximately 4,000 ppb (78%); Elevated sulfate still present in groundwater (>1,000 mg/L); and 22 out of 36 target monitoring wells below groundwater standards (GW Protection and Residential).
Groundwater Treatment Results Continued
Redox Techs Oxygen BioChem (OBC) A slow-release oxygen generating formula designed to provide short-term chemical oxidation (1-2 months) and long term anaerobic oxidation via sulfate reduction (1-2 years) Patented combination of sodium persulfate and food grade calcium peroxide Can be added to excavations or injected into groundwater One of the preferred products in New Hampshire Predecessor to Klozur CR
Oxygen BioChem vs. Competitors Oxygen BioChem (OBC) Competitors Greater oxygen – as much as 46 wt % Typically 10 to 20 wt % Both chemox and biorem.Mostly bioremediation Greater solubility –40 wt % for the persulfate portion Typically less than 5% soluble Better value - $3.25 per pound Typically $4 to $10 per pound
18 Enhanced Anaerobic Bioremediation Aquifers are sometimes limited by carbon (or food) source for bacteria In some instances, the proper bacteria (e.g. dehalogenators) are not present Overstimulation can result in domination by methanogens Examples: Redox Techs ABC, FMCs EHC and Regenesis HRC Data should support the use these products
19 Anaerobic BioChem (ABC) Sodium Lactate Ethyl Lactate – green solvent Fatty Acids – all dissolved Dipotassium Phosphate for micronutrients and pH buffering Can bioaugment with RTB-1 (DHC)
20 ABC ® Advantages Long lasting (2+ years) but water soluble so large volume of chase water not required Lower injection pressures Does not require hydrolysis of oils to release fatty acids No emulsion breaking potential No soap formation from bringing pH up to high Demonstrated buffering
21 Anaerobic BioChem (ABC + ) Mixture of ABC ® plus zero valent iron (ZVI) Combination of chemical reduction (ZVI) and anaerobic bioremediation Less likely to form VC Licensed with Adventus & Waterloo to add ZVI to carbon amendment Injected over 1,500,000 pounds ABC+
22 ZVI REACTION β-elimination pathway minimizes daughter products very low concentration of chlorinated intermediates intermediates degrade Surface reaction at ZVI
23 Combined Bio and Chemical Reduction
ABC+ Injection Wrentham, MA 5,000 square foot area and a 15 foot thickness Dense material with gravel, which required pre-clearing top 5 feet with auger 5,400 lbs of ABC+ 18 injection points with 5 depth intervals November 2009: PCE = 1,300 ppb and TCE = 93,000 ppb May 2010: PCE = ND < 50 ppb and TCE = ND < 50 ppb Dissolved gases detected and cis-1,2-DCE (3,300 ppb) and VC (910 ppb) spiked in May Cis-1,2-DEC and VC reduced in November 2010 to 670 ppb and 430 ppb.
25 Technical Advantages of Sulfate Exists naturally in most groundwater High solubility in comparison to other electron acceptors Easily applied as an aqueous solution Proper application of sulfate enhanced biodegradation will result in no adverse health effects Results are surprisingly rapid
Sulfate Reduction Case Study Site Background Former gasoline service station with two confirmed releases in 1992 and 2001 Historical remedial efforts with limited success included groundwater pump and treat and monitored natural attenuation Geology consists of fine to medium sand with groundwater present about 10 feet bgs Pilot study was not intended to be a full scale site remediation
27 Jackson, Michigan October 3, 2007 Baseline Conditions Sulfate is depleted in core Sulfate background is > 50 ppm Max. BTEX is >10,000 ppb Sulfate BTEX Sulfate Depleted In core of plume BTEX Plume GW Flow
28 Jackson, Michigan November 13, weeks after first application Sulfate is increased in core of plume – RED is >250 ppm Concurrently BTEX >10,000 ppb is decreasing Sulfate BTEX Sulfate Increases Sulfate Depleted BTEX beginning to shrink
29 Jackson, Michigan January 16, months after initial application Sulfate still elevated in core of plume BTEX >5,000 ppb is shrinking Sulfate BTEX Sulfate Increasing BTEX Shrinking
30 Jackson, Michigan April 12, months after first application Sulfate concentrations have returned to baseline conditions BTEX plume is stable with reduced peak concentrations Sulfate BTEX Sulfate Consumed BTEX Rebounding
31 Jackson, Michigan Case Study Benefits Accelerated cleanup Information gained significantly strengthens advocacy position with regulatory agencies Monitoring frequency showed no lag time for acclimation of native sulfate reducing bacteria Minimal site disruption In-situ approach with no ongoing O&M activities Cost effective <$2,000 worth of materials Safe Demonstrated absence of hydrogen sulfide gas generation or any other adverse affects Green – Natural Process
Metals Treatment 1. Lead treatment with phosphate buffer. 2. Arsenic/lead treatment with phosphate, calcium buffer and hydrogen peroxide. 3. Hexavalent chromium treatment with ferrous chloride and hydrated lime. 4. Bench Scale Study
Steam & Recovery Site in Lawrence, MA; Estimated 500 gallons of No. 6 Oil; Injected heated water into subsurface to create steam; Project was completed in 8 days; Approximately 700 gallons of product was recovered in 6 weeks; and No measurable product;
34 Delivery Capabilities Proprietary injection tools that are integrated with Geoprobe. Permanent injection points (PVC riser and screen). Injection of gasses, liquids and solids in largely varying geological environments - pressures from 10 to 2000 psi (Hydraulic Fracturing). Excavations/Trenches. In Situ Soil Blending for shallow soil (<25 bgs.).
35 Why Injection Isnt for Amateurs
36 Pump and Treat Gone Bad
37 Hydraulic Fracturing Injection of water, solution or slurry at pressure that exceeds the lithostatic pressure and cohesive strength of the formation. Results in short-term enhancement of soil permeability. Increases radius-of-influence and injection rate.
Hydraulic Fracturing Concept
Pressure – Time History Fracture Maintenance
40 ABC+ Injection Equipment
41 In Situ Soil Blending Efficient and uniform delivery of remediation amendments Production rates comparable to dig, haul and backfill No long term liability associated with disposal Costs that can be 2 to 10 times less expensive than dig and haul, depending upon the extent of contamination No RCRA TSD permits are required Can treat a wide range of compounds, such as chlorinated solvents, pesticides, PAHs, etc
42 In Situ Soil Blending – The Beginning
43 In Situ Soil Blending - Improved
44 Improvements in Blender Weight reduced by ~50% which reduces transportation costs by factor of two ($5-6 per mile now) Horsepower approximately doubled Independent acting dual motors in custom designed mixing head Torque load sensing on both sides of head so rotation speed automatically adjusts – prevents deadheading Base is common excavator so parts readily available
45 In Situ Soil Blending Cambridge, MA Dichloroethane (DCA) Contamination
46 Post In Situ Soil Blending
47 Amendment Distribution via Electrical Conductivity Distribution Dr. Joseph Rossabi Completely Integrated with Geoprobe Apply AC (current) Measure DC (voltage) Know current and voltage, calculate resistance and convert to conductivity (inverse relation) Measurements every 0.05 ft (vertical) Lateral sensitivity < 0.5 ft
51 USEPA Site Rhode Island
52 Treatment Area
53 Blending Activity – Day 1 Top Photo – A view of the excavation prior to blending activity Bottom Photo – A view of the application of the first 1K pounds of KMnO 4
54 Blending Activity – Day 1 (Continued) Top Photo – A view of the initial mixing with an excavator. Bottom Photo – A view of the soil blending thoroughly mixing the KMnO 4 with the contaminated soil.
55 Day 1 – Area Completed 2,000 pounds of KMnO 4 blended with ~ 300 cy of contaminated soil (Area shaded in purple). KMnO 4 not observed in down gradient monitoring wells.
56 Day 5 – Area Completed 7,000 pounds of KMnO 4 blended with ~ 1,500 cy of contaminated soil (Area shaded in purple). Approximately 8,500 gallons of water was used to blend the KMnO 4 with the soil. KMnO 4 observed in 3 down gradient monitoring wells ( ).
57 Day 7 – Soil Blending Completed 10,000 pounds of KMnO 4 blended with ~ 2,100 cy of contaminated soil (Area shaded in purple). Approximately 10,500 gallons of water was used to blend the KMnO 4 with the soil. KMnO 4 observed in 4 down gradient monitoring wells ( ).
58 Day 12 – Post Blending Monitoring KMnO 4 observed in 7 monitoring wells ( ).
In Situ Remediation Issues Underestimated contaminant mass; Unknown underground structures; Poorly marked utilities; Daylighting; Back Pressure; Surface grade; Aboveground obstructions; and Poorly identified geology
60 The End In Situ Remediation is 1 of many tools; Injection is not the only application technique; Know your site; Work with your In Situ contractor; Understand the function of the chemical; and For more information: