Tony Moran

A Pilot Study was developed for an industrial landfill located in Brazil using In situ solidification/stabilization (ISS). The objective of the Pilot Study was to treat and stabilize the source zone contamination in the subsurface soils with Sodium Persulfate, Portland cement and other reagents via in situ soil mixing with a single large diameter auger. The main contaminants of concern were BTEX and naphthalene, specifically Benzene occurring at concentrations of 7 to 7000 mg/kg. A bench scale… Show more

A Pilot Study was developed for an industrial landfill located in Brazil using In situ solidification/stabilization (ISS). The objective of the Pilot Study was to treat and stabilize the source zone contamination in the subsurface soils with Sodium Persulfate, Portland cement and other reagents via in situ soil mixing with a single large diameter auger. The main contaminants of concern were BTEX and naphthalene, specifically Benzene occurring at concentrations of 7 to 7000 mg/kg. A bench scale laboratory study was developed to test and optimize varying mixtures of reagents with the site soils to develop an ISS combination approach that was field implementable, in order to achieve gross contaminant and leachability reduction, strength and permeability. This paper presents an overview of soil mixing as it relates to environmental remediation as a “new” local technology and highlights the application of up to 30 different mix combinations to address the high level Benzene concentrations. A Pilot Study was performed focusing on the improvement of the oxidation reagent performance by varying reaction time, number of treatment strokes at a location and use of lime or Portland cement to activate the Sodium Persulfate. Show less

In Situ Solidification and Stabilization (ISS) is a proven environmental remediation
technology that has been implemented to address soil, sediment, and groundwater remediation projects throughout the United States and internationally. This remediation technology could serve as an alternative coal combustion residual (CCR) closure and corrective action strategy; however, there has not been extensive bench-scale testing to determine the appropriate mixes (i.e., cement, other reagents, and… Show more

In Situ Solidification and Stabilization (ISS) is a proven environmental remediation
technology that has been implemented to address soil, sediment, and groundwater remediation projects throughout the United States and internationally. This remediation technology could serve as an alternative coal combustion residual (CCR) closure and corrective action strategy; however, there has not been extensive bench-scale testing to determine the appropriate mixes (i.e., cement, other reagents, and doses) required to adequately ISS impounded CCR.

This paper uses samples collected from CCR ponds to perform a bench-scale study to
evaluate potential ISS mix designs. CCR samples were visually characterized and
tested for geotechnical characteristics (i.e., grain-size, plasticity, pH, moisture content and
organic content). Various dry reagent compositions and grout mixtures were developed and analyzed for workability. Mix designs were developed with the CCR being solidified using varying ratios of grout and reagent to CCR.

Mixed specimens were tested for early unconfined compressive strength (UCS) at 1, 3, 5, and 7 days with a pocket penetrometer. Using results of the early UCS testing, select specimens were selected for UCS testing at various rates of cure and for hydraulic conductivity. Test results were used to develop correlations between CCR index properties, reagent dosages and resulting UCS and hydraulic conductivity.
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In-Situ Solidification and Stabilization (ISS) is a proven environmental remediation
technology that has been implemented to address soil, sediment and groundwater
remediation projects throughout the US and internationally. This remediation
technology should serve as an alternative coal combustion residual (CCR) closure and
corrective action strategy.

Using results from a recent bench scale study conducted by Geo-Solutions, Inc., the
authors have performed feasibility… Show more

In-Situ Solidification and Stabilization (ISS) is a proven environmental remediation
technology that has been implemented to address soil, sediment and groundwater
remediation projects throughout the US and internationally. This remediation
technology should serve as an alternative coal combustion residual (CCR) closure and
corrective action strategy.

Using results from a recent bench scale study conducted by Geo-Solutions, Inc., the
authors have performed feasibility study level analyses to determine the
implementability, regulatory acceptance, sustainability, and estimated costs to apply ISS
as a CCR impoundment closure technology. Using the bench scale mix design results
substantially reduces the uncertainty in developing engineering cost estimates for ISS of
CCR impoundments. The analysis also includes consideration of potential future uses
of the former impoundment following application of the ISS treatment methods.

Specific closure applications evaluated include full depth/complete ISS of a CCR
storage area, shallow ISS as an alternate to or in conjunction with multi-layer capping,
and ISS for containment purposes (mixed cut-off wall versus other vertical barrier
technologies).
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In late 2016, contaminated soil at a former gas station site in Calgary, Alberta, was removed using a cement-bentonite (CB) slurry for excavation support, eliminating the need for dewatering, traditional shoring, and for personnel to operate within an excavation. The CB slurry, consisting of water, ground granulated Blast Furnace Slag Cement (BFSC), Portland Cement (PC), and bentonite, acted as hydraulic excavation support and later hardened to form a consistent, low-strength… Show more

In late 2016, contaminated soil at a former gas station site in Calgary, Alberta, was removed using a cement-bentonite (CB) slurry for excavation support, eliminating the need for dewatering, traditional shoring, and for personnel to operate within an excavation. The CB slurry, consisting of water, ground granulated Blast Furnace Slag Cement (BFSC), Portland Cement (PC), and bentonite, acted as hydraulic excavation support and later hardened to form a consistent, low-strength, low-hydraulic-conductivity backfill suitable for future site re-development. One to six bucket width panels were overlapped to create slurry-supported excavation cells (“piano keys”). In all, 10,232 m3 of contaminated soils were excavated from up to 12 m below the work platform. Cured CB slurry met or exceeded project requirements of 276 kPa unconfined compressive strength (UCS) and less than 1x10-7 cm/s hydraulic conductivity, typically within 28 days of cure, and continued to improve up to as long as 84 days of cure. Compared with conventional excavation support and dewatering methods, the approach demonstrated significant cost, safety, and schedule benefits. Show less

Much of the information presented in this paper should be considered common knowledge by
those who regularly encounter soil-cement mixtures. This paper was developed to provide the
reader a comprehensive understanding of what soil-cement mixtures are and what physical
properties to expect. The target audience is civil or geotechnical engineers that are not commonly
engaged in work involving shallow or deep soil mixing or other applications in which soil is mixed… Show more

Much of the information presented in this paper should be considered common knowledge by
those who regularly encounter soil-cement mixtures. This paper was developed to provide the
reader a comprehensive understanding of what soil-cement mixtures are and what physical
properties to expect. The target audience is civil or geotechnical engineers that are not commonly
engaged in work involving shallow or deep soil mixing or other applications in which soil is mixed
with cementitious reagents in situ. However, even readers with knowledge of these topics may
benefit from the information included in the tables and figures and commentary presented
throughout.

The term soil-cement is self-explanatory, but will herein also be used to describe any mixture of
soil and reagents containing some cementitious component installed in situ. Other common terms
used to describe mixtures like this are soil-grout and soilcrete. Applications in which soil or
sediment is mixed with cementitious reagents ex situ are not addressed here. Show less