Implementation of In Situ Activated Carbon
Remedies at Contaminated Sediment Sites



INTRODUCTION

REMEDIAL LOCATIONS AND
COMMON CONSIDERATIONS

Active caps have been applied in a variety of environments. A list of projects with available application and monitoring information may be found here (click here to view table). Several of these projects are presented in the Case Studies section.

Many of the considerations for applying AC as a remedy are the same as those that must be considered for sediment capping or enhanced monitored natural recovery (Eek and Reible 2015 (insert) EPA 2005, ITRC 2014). Design, construction and contracting considerations will be detailed in subsequent pages, but three key points must be emphasized from the start:

1.

No amended cap to date has demonstrated sequestration of the bioavailable contaminant fraction to below a numeric Remedial Action Level (RAL). While all have shown significant reductions in the bioavailable fraction (75 - 90% over base line), no project has been implemented that has been engineered to a chemical-based RAL.
 
 

Contaminated sediments
in rivers and lakes

  • Sub-aqueous groundwater discharge
  • erosion by river flow, ice scour and
    ship traffic
 

Contaminated sediments in harbors

  • Sub-aqueous groundwater discharge
  • erosion by river flow and ship traffic
 

Contaminated soil and ground
water nearshore

  • Groundwater, NAPL flow
 

Contaminated sediments in estuaries
including fjords and other deep
estuaries, offshore areas)

  • Amendment placement, ocen current
    or wave erosion, bioturbation
 

Contaminated sediments in rivers

  • Sub-aqueous groundwater discharge
  • erosion by river flow, ice scour and
    ship traffic

Courtesy of Dr. Espen Eek (Norwegian Geotechnical Institute) and Professor Danny Reible (Texas Tech University)

2.

Most projects to date have been demonstration projects, not full scale remedies as part of a Record of Decision (ROD). While larger (e.g. 1 acre) sites are being evaluated, most have been demonstration projects.

3.

The long term efficacy of an AC remedy has yet to be established. While some applications have been in place for at least a decade, many of those do not have recent monitoring data to confirm the material is still in place and the continuing sequestration of contaminants.