Implementation of In Situ Activated Carbon
Remedies at Contaminated Sediment Sites



INTRODUCTION

Welcome to the Implementation of In Situ Activated Carbon Remedies at Contaminated Sediment Sites
web site. This web site is intended to provide an overview of the key technical considerations for
Department of Defense (DoD) Remedial Project Managers (RPMs) for using activated carbon as an in-water
remedial alternative for managing sediment sites. While this site has been built with an emphasis on the
DoD RPMs, input from EPA RPMs, state-lead RPMs, university and research organizations, as well as
industry leaders in AC application has been used to construct this site.

In this first section we will first provide background information on how activated carbon works to
sequester contaminants, an introduction to sites where activated carbon (AC) has been applied as a
sediment remedy, the types of remedies (in situ amendment addition, composite caps), and some key
definitions to understand moving forward into the technical chapters of this web site.

In subsequent sections we will discuss

  • Science of Carbon Sequestration. A brief primer on how the AC can capture and hold the contaminants
  • Design. Choosing amongst the various types of commercially available AC relative to the physical conditions at your site, how to determine the amount to place, and cost considerations
  • Construction. A discussion of the construction methods that are available to place the AC, relative to physical site conditions and availability of equipment and resources
  • Monitoring and Maintenance. Tools available to monitor the placement relative to the design and performance criteria, and examples of maintenance needs that have been implemented at other sites
  • Case studies with detailed documentation and/or links to the design, construction and monitoring documents or videos from that site
  • References and Resources. Links to other helpful remediation and monitoring documents within the DoD, EPA, the Interstate Technology & Regulatory Council (ITRC) and other helpful sources

Site

Contaminant

Year Constructed

Project summary

Target AC

Delivery Methods

Project Web Link

AC Projects Completed in North America

USN Hunters Point San Francisco Bay, CA

PCBs & PAHs

2015

1 acre pilot study that includes ca 0.5 acres of SediMite and 0.5 acres of AquaGate+PAC.

4 - 6 %

Telebelt ®

USN Hunters Point Case Study

USN Sierra 1B Pier Pearl Harbor, HI

PCBs & mercury

2015

11,000 ft 2 under-pier pilot study with ~ 4,400 ft 2 of SediMite and 4,400 ft 2 of AquaGate+PAC.

2.5%

Gravity fed hopper with pneumatic conveyance to an under-pier operator who directed the output over specific 10' x 10' cells.

USN Sierra 1 B Case Study

Mirror Lake Restoration Dover DE

PCBs

2014

Full-scale 4.9 acre remediation of lake and downstream with SediMite.

5%

Telebelt® in deeper areas of lake; induction air horn, vortex spreaders, and by hand in nearshore

Mirror Lake Case Study

Puget Sound Naval Shipyard Bremerton, WA

PCBs & mercury

2012

0.5 acre pilot study to evaluate the efficacy of AC application under an active Navy pier. Product was AquaGate+PAC.

4%

Telebelt ® over-water and under pier sections of the project.

PSNS Case Study

Berry’s Creek, NJ

Mercury & PCBs

2012

Small test plots (30 x 30 ft) with AC placed on the surface of a phragmites marsh using three approaches: 1) granular carbon only, 2) granular carbon with a 2 inch coarse sand cap, and 3) fine granular carbon in the form of SediMite™. Activated carbon dose was 5 percent by dry weight of sediment in the top 10 cm.

SediMite™ application rate was 5 kg/m2

AC 5%

SediMite™ 5 kg/m 2

GAC as a slurry using a hydroseeder. Coarse sand was delivered to plot using a telebelt and manually layered over the treatment area. SediMite™ was applied using a Vortex TR Aquatic spreader.

EPA, 2013

Lower Duwamish Slip 4 Seattle, WA

PCBs

2011

Dredged areas on the banks and riverbed at the head of the slip included a filter layer of well graded sandy gravel, amended with sand-size granulated activated carbon.

0.5%

Sandy gravel with GAC mixed upland and placed using a dredge bucket.

Slip 4 Lower Duwamish Case Study

Onondaga Lake Pilot Study Onondaga County, NY

Chlorinated benzenes & PAHs

2011

1 acre capping pilot to demonstrate the implementability of mixing/slurrying GAC and sand on-shore and placing the material over a pre-defined depth and area. The project informed full scale construction planning and implementation.

0.25 - 1.0 lb/ft 2

Sand/GAC slurry mix system mixed with water and pumped through a pipeline and booster pumps to a hydraylic spreader barge. Slurry placed in a series of parallel lands.

Onondaga Lake Pilot Case Study

Canal Creek, MD

PCBs & mercury

2010

Twenty-four test plots, each 8 meters by 8 meters to evaluate the performance of three AC applications in a wetland: two pelletized AC products (AquaBlok and SediMite, and a PAC slurry . Pilot project under ESTCP ER-200825 and ER-200835.

3%

Depending upon the test product, a Vortex spreader, hydroseeder, bark blower, or by hand. Many of the test plots were accessible on-foot, in the submerged wetlands the spreaders were used on a boat.

Canal Creek Case Study

Naval Air Station, Cottonwood Bay, Dallas TX

PCBs, PAHs, chromium, lead

2009

Small-scale pilot project that tested reactive mats featuring a 0.28 lb/ft2 activated carbon, 0.23 lb/ft2 apatite, 0.28 lb/ft2 organoclay amendment mixture and an AOS 80 geotextile.

0.28 lb/ft 2

Prototype reactive mats rolled up and deployed from a john-boat by divers. Divers secured the mats in the shallow bay with anchors, anchor screws, and blocks. Some of the treatments were further covered with sand.

SERDP ER-1493

NAVFAC TR-2366-ENV Technical Repor t

Bailey Creek, Fort Eustice, VA

PCBs

2009

Pilot-scale studies of SediMite in 225 m 2 plots within a marsh and in the main channel.

5%

Vortex spreaders from boat

Bailey Creek Case Study

St. Louis River Superfund Site Duluth, MN

NAPL/PAHs

2006

11 acres of cap that included a reactive core mat withAC to absorb advected PAH-porewater during consolidation. The cross section of the cap was 0.5 ft (15 cm) sand/activated carbon mat/2.5 ft (75 cm) sand.

0.4 lb/ft 2

Reactive mats attached to outer sheet-pile wall and unrolled toward shore from a moveable barge. Overlapping RCMs stapled and allowed to sink, followed by sand placement

ITRC 2014

Olta and Hornday, 2007

Grasse River, Massena, NY

PCBs

2006

0.5 acre pilot project with AC mixed into PCB-contaminated sediment.

3.2 - 5%

Two application methods tested: "roto-tiller" and tine sled. The tiller is an enclosed device that first applied (via spraying) activated carbon onto the sediment surface, followed by mixing of the material into near-surface sediments using the roto-tiller (was used with and without mixing). The tine sled device included direct injection of activated carbon into near-surface sediments.

Grass River Pilot Project Web Site

Hunters Point 2005 Pilot Project San Francisco Bay, CA

PCBs & PAHs

2005

Pilot project under SERDP-1207 and ESTCP ER-200510.

5.1%

Two types of GAC applications were tested. In the first, the AC was spread onto the surface of the sediments via a backpack spreader located on an Aquamog and then a rotovator arm mixed the GAC into the sediments. WIth the second applicationGAC was sprayed onto the rotovator and mixed.

SERDP-1207

ESTCP ER-200150

Hunters Point 2005 Case Study

Anacostia River, Washington, DC

PCBs, PAHs, chromium, lead

2004

1100 m 2 area was capped with a coke-filled RCM and covered with 15 cm of sand.

24 kg/m 2

Twelve 3.1 m x 31 m coke-filled RCMs were placed with a 0.3 m

overlap using a crane with a clamshell.A diver followed the unrolling mat to insure proper placement. A sand layer (~15 cm) was then placed above the RCM by particle broadcasting to

McDonough et al, 2006

ITRC 2014

AC Projects Completed in Europe

Grenlandsfjords, Norway

Dioxins/furans

2009

Pilot project to demonstrate efficacy of a hydraulic application of AC/clay mixture at depth. Plot size was 40,000 m 2 at a depth of 100 m. Comparative plots also included crushed limestone, and clay-only cpas.

2 kg/m 2

Dredged clean marine clay was mixed with a coal-derived powdered AC (d80 < 45 μm) in 10:1 dw ratio. To increase the density of the clay + AC slurries the salinity was increased by adding NaCl, and was pre-mixed for at least one hour in the hopper dredger tank to a water content of 56−70% prior to placement. A hopper dredge was used in reverse mode: the intake pipe was as a tremie with the material released approximately 5 m above the seafloor. To facilitate settling the powdered AC was mixed with a 10% w/w 

Grenlandsfjords Case Study

Trondheim Harbor, Norway

PAHs

2008

Pilot project evaluating three treatments: AC, AC+clay, and AC covered with sand for erosion protection. Test plots were 225 m 2

5 kg/m 2

NaCl in a 100-L cement blender to saturate the AC pore system with water that was slightly heavier than surrounding water. For the AC-only and AC+sand fields, this slurry was pumped out with a flexible manually operated 5 cm hose For the AC+clay field, AC and bentonite were mixed 1:1:6 with 10%-NaCl and pumped out as described above.

Trondeheim Harbor Case Study

NGI 2011