RECENT USES OF IN SITU STABILIZATION, IN SITU CHEMICAL OXIDATION, - - PowerPoint PPT Presentation

“RECENT USES OF IN SITU STABILIZATION, IN SITU CHEMICAL OXIDATION, AND IN SITU CHEMICAL REDUCTION USING SOIL MIXING”

Presented by: Ken Andromalos & Daniel Ruffing

RE3 – Remediation, Renewal, Results

Soil Mixing – Development Timeline

First Used in US: Geotechnical and Earth Retention Applications Developed in Japan and Europe Re-introduced into US market: Jackson Lake Dam First used for Solidification / Stabilization of wastes Expanded use on environmental sites for stabilization & treatment 1960 1970 1980 1990 2000 2010

 Any technique used to mechanically mix soils with or without

additives

 More commonly, the term refers to processes by which reagents

are injected and mixed with the soil

 Processes vary:

 In Situ vs. Ex Situ  Dry vs. Wet Reagent Addition  Single Auger vs. Multi Auger  Auger vs. Bucket vs. Rotary Drum

 Purpose : the efficient creation of a soil-reagent composite with

improved properties relative to the in situ soils.

Soil Mixing

 Widely accepted means for cost effective site remediation  Other related acronyms:  Shallow Soil Mixing (SSM)  Deep Soil Mixing (DSM)  Stabilization & Solidification (S/S)  In Situ Stabilization (ISS)  In Situ Solidification (ISS)  In Situ Chemical Oxidation (ISCO)  In Situ Chemical Reduction (ISCR)

Soil Mixing – Background Conclusions

Soil Mixing – Equipment for Environmental Applications

Auger Mixing Excavator Mixing Excavator Mounted Rigs Or Crane Mounted Rigs Buckets Or Arm Attachments

Auger Mixing

• Auger mixing most

commonly used soil mixing method for environmental projects

• Generally the most

cost effective auger mixing for environmental applications is large diameter single auger mixing (pictured here)

Auger Mixing – general aspects

 Columns installed in an overlapping pattern that ensures 100%

coverage of the target area

 Wet mixing is more common for environmental applications, but

• ccasionally project or site conditions neccesitate the use of dry

mixing methods or the use of air as a drilling fluid

Solidification vs. Treatment

 Solidification / Stabilization (ISS) –

 Contaminants are not purposefully chemically changed to less

harmful forms, but are locked in low permeability matrices that reduce the contaminants’ impact on the surrounding soils and groundwater.

 Treatment (IST) –

 Reagents are used to actively promote a chemical change in the

impacted material

 Contaminants are purposefully chemically changed to less harmful

constituents via reduction or oxidation

Sources: ITRC (2011)[6]; Gardner, F.G., et. al., (1998)[8]; Irene M.C., (1996)[9]; USEPA (2009)[10]; U.S Department of Defense (2000)[11]; U.K Environmental Agency (2004)[12]; Raj, D.S.S; Rekha, C.A.P, Bindhu, V.H; Anjaneyulu, Y., (2005)[13]; Conner, (1990) [14].

Reagents

Solidification vs. Treatment – conclusions

 ISS generally cheaper than IST

 Lower reagent cost  Less material handling safety concerns

 Similar schedules  Both viewed as acceptable remediation approaches, but IST often

viewed as a more robust solution

 Promotes active degradation of contaminants

 Require similar equipment and labor, but IST projects are harder

to implement

 Project staging more difficult  Material handling more difficult

Case Studies - Introduction

 Case Study 1 – East Rutherford, NJ

 In situ chemical oxidation and stabilization of solvent impacted soils

 Case Study 2 – Robbinsville, NJ

 In situ chemical oxidation of xylene & pesticide impacted soils

 Case Study 3 – Waukegan, IL

 In situ chemical reduction of solvent impacted soils

 Case Study 4 – Norwich, NY

 In situ chemical oxidation of acetone impacted soils

 Case Study 5 – Columbus, IN

 In situ stabilization / solidification of wood treating impacted soils

Case Study 1 – East Rutherford, NJ

 Original site use:

 Glassware manufacturing facility

 Contaminant of Concern

 TCE and related byproducts

 Performance Schedule

 Bench Scale Study: Fall 2009  Site Prep Work: Spring 2010  Soil Mixing: Spring – Summer 2010

 Treated Volume Dimensions

 6,800 CYs – treated twice (13,600 CYs total)  Up to 20’ BGS

 Reagents

 Potassium Permanganate @ 17.5 lbs / CY  Portland Cement @ 202 lbs / CY (applied 3 days post oxidation)

Case Study 1 – East Rutherford, NJ (2)

Work performed in a “bowl” to control spoils A number of obstructions were removed, including deep foundations Potassium permanganate is bright purple at very low concentrations – material handling was a big part of the project.

Case Study 1 – East Rutherford, NJ (3)

 242 nine foot diameter columns installed  Quality Control

 Post construction groundwater monitoring showed 99% reduction

in TCE concentration

 Wet grab samples were collected from recently mixed columns  Average UCS = ~270 psi @ 28 days  Average Permeability = 4.1 x 10-7 cm/s @ 28 days

Case Study 2 – Robbinsville, NJ

 Original site use:

 Chemical manufacturing facility

 Contaminant of Concern

 Xylene and pesticides

 Performance Schedule

 Soil Mixing: Summer 2011

 Treated Volume Dimensions

 2,500 CYs  Up to 15’ BGS

 Reagents

 Hydrated lime @ 72 lbs / CY (pH adjustment)  Sodium Persulfate @ 28 lbs / CY (oxidant)

Case Study 2 – Robbinsville, NJ (2)

Work performed in a “bowl” to control spoils Project staging important because

• f post treatment soil properties

The oxidation reaction was evident at the surface as the material bubbled and changed colors

Case Study 2 – Robbinsville, NJ (3)

 91 nine foot diameter columns installed  Quality Control

 Process controls were utilized to ensure the proper amounts of

reagents were added to and mixed with the soils

Case Study 3 – Waukegan, IL

 Original site use:

 Outboard marine engine manufacturing

 Contaminant of Concern

 TCE and related byproducts (vinyl chloride)

 Performance Schedule

 Soil Mixing: Fall – Winter 2011

 Treated Volume Dimensions

 7,800 CYs  Up to 25’ BGS

 Reagents

 Zero Valent Iron (ZVI) @ 54 lbs / CY  Bentonite Clay @ 27 lbs / CY

Case Study 3 – Waukegan, IL (2)

Potassium permanganate is bright purple at very low concentrations – material handling was a big part of the project. The sands and gravels presented very difficult drilling conditions The ZVI soil mixing work was the first part of a much larger remediation effort at this Superfund site. The soil mixing was used to target the source zone. Iron storage very important – prevent rust!

Case Study 3 – Waukegan, IL (3)

 224 nine foot diameter columns

installed

 Quality Control

 Samples of mixed material were

subjected to magnetic seperation tests to ensure the iron was well distirbuted.

 Post construction sampling for

TCE concentration to be conducted later.

Case Study 4 – Norwich, NY

 Original site use:

 Chemical manufacturing

 Contaminant of Concern

 Acetone

 Performance Schedule

 Soil Mixing: Winter – Spring 2012

 Treated Volume Dimensions

 19,500 CYs  Up to 30’ BGS

 Reagents – Post hot air mixing

 Ammonium Sulfate @ 0.5 lbs / CY  Potassium Chloride @ 0.25 lbs / CY  Phosphoric Acid @ 18 lbs / CY

 Calcium Peroxide @ 21.5 lbs / CY

Case Study 4 – Norwich, NY (2)

Work performed in a “bowl” to control spoils Two drill rigs used throughout the project. The first rig was used for hot air mixing and the second rig was used to add and mix in the chemical reagents Project staging was very important given the liquid consistency of the soils post treatment.

Case Study 4 – Norwich, NY (3)

 324 nine foot diameter

columns installed

 Quality Control

 Process controls were

utilized to ensure the proper amounts of reagents were added to and mixed with the soils

 Post construction sampling

to be conducted

Case Study 5 – Columbus, IN

 Original site use:

 Wood treating

 Contaminant of Concern

 Creosote

 Performance Schedule

 Soil Mixing: Spring 2012

 Treated Volume Dimensions

 4,600 CYs  Up to 17’ BGS

 Reagents

 Portland Cement @ 480 lbs / CY  Powered Activated Carbon (PAC) @ 120 lbs / CY

Case Study 5 – Columbus, IN (2)

Work performed in a “bowl” to control spoils Two drill rigs used throughout the project. The first rig was used for hot air mixing and thesecond rig was used to add and mix in the chemical reagents Carbon combined with creosote gave the material it’s dark color Automated batch plant for proportioning grout components Powdered carbon delivered in supersacks

Case Study 5 – Columbus, IN (3)

 247 nine foot diameter columns installed  Quality Control

 Wet grab samples were collected immediately after mixing

Conclusions

 Soil Mixing

 Widely used to treat & stabilize a number of wastes

 Stabilization vs. Treatment

 Stabilization less expensive, but contaminants remain relatively

chemically unchanged

 Numerous reagents for both stabilization and treatment

 Case Studies

 Recent case studies highlight the use of soil mixing for the treatment

and stabilization of subsurface contamination

 Material handling and storage very important  Careful planning and staging required