April 2014

Authors: John A. Collins4, Gary Loveland3, Howard Evans3, John Rice2, Katherine Vater2and Shayne A. Wiesemann 1 1 DTE Energy 2 TRC Environmental 3 Terra Contracting Services, LLC 4 AquaBlok, Ltd.

Installation of an Impervious Cap for Control of Residual NAPL Migration:

Construction Issues and Solutions

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Presentation Outline

I.  Overview of Material Technology Utilized

II.  The Problem – Ebullition – Shoreline Seeps

III. Case Study – DTE Energy Ann Arbor Site

IV. Summary/Q & A

powder coating

AquaBlok “composite particle”

+

aggregate core

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Key Technical Advantages:

¤  Efficient delivery of high-value materials at low concentrations ¤  No field mixing or blending ¤  Low cost handling & installation ¤  Unique geotechnical attributes: self-compacting; shear strength ¤  Highly versatile: custom- formulate for project-specific need

Allows a particle to be uniformly coated with fine-grained (i.e. powdered) materials For efficient/effective placement in both freshwater and saltwater environments

Variables:

¤  Coating composition: - AquaGate™ for treatment; - AquaBlok® for isolation/sealing ¤  Coating to aggregate ration ¤  Permeability: 1 x 10-2 to 5 x 10-9 cm/s (dependent on composition) ¤  Particle size: -1/4” to -3/4”

Coating

Core

Overview of Technology

Low-Permeability for Sub-Aqueous Capping & Lining

Applied through standing water or in the dry

MGP Sites

PAH / PCBs

Landfill Cap

Refinery/PAH Sites

Metals/DDT

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Demonstrating Compliance in a Dynamic Environment

Split-core from Section A (2.5 yrs after placement)

New sediment Deposits

AquaBlok Clean Cap Layer

Discrete boundary

Contaminated Sediment

Permeable Materials for In-Situ Treatment & Remediation Applications

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

0 20 40 60 80 100

Residence Time ( hrs )

Con

cent

ratio

n ( µ

g/L

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AsCr

+Sorbster® +ORGANOCLAY AquaGate+PAC

not to scale

Organoclay Treatment Layer

Water Column

Clean Backfill

Residual Contamination

Armoring Layer

Example: Use of Permeable AquaGate+ORGANOCLAY Layer to Protect from Sheen Must Vary Thickness to Provide for Adequate Residence Time for Adsorption AND Capacity Must Have Adsorption Capacity to Protect from Higher Concentration Areas of an Isolated Seep Zone Granular Organoclay will Swell and Reduce Permeability as Oleophilic Clay Adsorbs NAPL – Can Cause “Blinding-Off” of Unused Adsorptive Capacity

Treatment of Groundwater Through A Permeable Treatment Layer

Conceptual Model - Gas Carries Coal Tar from Sediment to Water Surface (modified from McLinn & Stolzenburg, 2009)

The Problem: Ebullition – Shoreline Seeps

Conceptual Design - NAPL Trapping Cap A sediment capping system made of geological materials (clay, sand, gravel, boulders ) that can be used to capture NAPL permanently and predictably as it migrates from sediments

* NAPL Trapping Cap was designed by TRC

Patent Nos: US 8,419,314 and US 8,651,768

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Site Location: U.S. EPA Region 5 MGP Impacted River – Ann Arbor, MI

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Overview of Site

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Overall Project Details

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Cap Cross-Section / Layers

Initial Survey and Removal Area

Significant Effort was placed on protection of the river – a soil berm and boom system was employed

Removal of Impacted Sediments

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AquaBlok - Bulk Transport and Loading

Placement of Gas Transmission Layer – Formation of the Base of the Cap

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AquaBlok Low Permeability Layer

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Cover Layers & Armor

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View of Cap Layers – As Placed

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Cap Completion and Restoration

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View of Site

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•  All Natural Clay Material Provides Low Hydraulic Conductivity for Effective Contaminant Isolation (Addresses Food Chain Uptake Issues)

•  Serves as a Delivery System for a Wide Range of Treatment Materials

•  Easy to Handle and Install

•  Provides Ability to Perform Low Cost Post-Cap Monitoring

•  Implementable in Connection with Either MNA or Dredge/Cap Strategy

•  Highly Cost-Effective Alternative and Less Invasive than Dredging

Engineered Thin Capping Materials Provide Remediation Alternative for Sub Aqueous Treatment

and Sequestration of Contaminants at MGP Sites

Summary – Q&A