Media
Contact: Michael Mueller, (+01) 860.841.9138
U.S. EPA Releases SITE Evaluation Report – Demonstration
of the AquaBlok® Sediment Capping Technology
Report indicates AquaBlok Provides Material
Properties Superior to Traditional Sand Capping Approach
in Physical Stability and Reduced Permeability or Seepage
Through the Capping Material
 TOLEDO, OHIO, December 20, 2007 – AquaBlok, Ltd.,
a manufacturer of innovative clay-based composite materials,
is pleased to announce the long awaited release of the Final
report authored by the U.S. EPA’s National Risk Management
Research Laboratory, Office of Research and Development. The
full report can be accessed on the web at: http://www.epa.gov/ORD/SITE/reports.html
A program of the U.S. Environmental Protection Agency (EPA),
referred to as the Superfund Innovative Technology Evaluation
(SITE) Program, evaluated the effectiveness of AquaBlok® as
an innovative contaminated sediment capping technology in
the Anacostia River in Washington, DC. Contaminants
in the sediment of the Anacostia River include polycyclic
aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs),
heavy metals, and other chemicals to levels that generally
exceed regulatory standards. Performance of an AquaBlok® cap
was monitored over an approximately three year period using
a range of invasive and non-invasive methods.
A comparison of AquaBlok® to a traditional sand cap
was made relative to the following three basic objectives:
- Assess the physical stability of AquaBlok® relative
to a traditional sand cap,
- Determine the ability of AquaBlok® to prevent hydraulic
seepage compared to traditional sand cap material,
- Evaluate the impact of AquaBlok® on benthic habitat
and ecology relative to traditional sand cap material and
conditions in the native river system.
The conclusion of the evaluation, from the abstract of the
report is as follows:
“The overall results of the AquaBlok® SITE demonstration
indicate that the AquaBlok® material is highly stable,
and likely more stable than traditional sand capping material
even under very high bottom shear stresses. The AquaBlok® material
is also characteristically more impermeable, and the weight
of evidence gathered suggests it is potentially more effective
at controlling contaminant flux, than traditional sand capping
material. AquaBlok® also appears to be characterized
by impacts to benthos and benthic habitat generally similar
to traditional sand capping material.”
A range of unique and important measurement methods were
employed during the evaluation to support the conclusions
of the report. Two such measurements related to stability
of the capping material against flow or sheer stresses and
seepage through the cap.
To evaluate the stability of the material a novel “SedFlume” approach,
specifically designed for testing of core samples of sediments,
was performed by an independent source. The conclusions
of these tests from the report are as follows:
“in the actual AquaBlok® material, erosion rates
were exceedingly low and required very high shear energy
to produce erosion. The shear stresses required to erode
the AquaBlok® material were between 3.2 and 10 N/m2,
a range that is indicative of very high surface water energy
at the sediment/water interface. In addition, this range
is at least an order of magnitude higher than was required
to erode the native sediment interval and significantly
higher than energy required to erode the sand capping material.”
Since AquaBlok is considered a low-permeability capping
alternative to traditional sand caps, both hydraulic conductivity
(K) measurements and seepage information collected from the
field were considered to be key measurements for the evaluation.
While the hydraulic conductivity is a standard measure,
the seepage data was collected from the river with specialized
ground-water seepage meters adapted to provide continuous
measurement of aqueous flux through the sediment cap at high
resolution over an extended period of time.
The conclusions of the report in regard to hydraulic conductivity
is as follows:
“hydraulic conductivity of the AquaBlok® material
during both events (i.e., 10-7 to 10-8 cm/s) was very similar
to the range of values determined for the native sediment
and consistent with the documented range for this capping
material. Hydraulic conductivities in the range determined
for AquaBlok® (and native sediment in the demonstration
area) are indicative of a highly impermeable material. Alternatively,
the calculated hydraulic conductivity for the sand capping
material from the sand cell (i.e., 10-3 to 10-4 cm/s), while
it did demonstrate some decrease between the 18-month and
30-month post-capping events, was several orders of magnitude
greater than AquaBlok®”
The conclusions of the report in regard to seepage are as
follows:
“for each sampling event, the mean, minimum, and maximum
calculated discharge rates over the representative 24-hour
tidal period were generally lowest for the seepage meters
deployed in the AquaBlok® cell. Calculated discharge
rates in the sand cell were generally higher than in the
AquaBlok® cell and the control cell, suggesting the
most significant vertical movement of fluid from sediment
to surface water in this cell.”
Recovery of benthic habitat and ecology in the capped area
is also of primary interest in the evaluation and application
of sediment remediation management options. The report
provides significant detail at the 30 month interval on recovery
and the comparison of the AquaBlok Cell to the Sand Cap:
“Overall, benthic habitats and faunal communities
in the AquaBlok® and sand cells were more similar to
each other than to those in the control cell, but retained
differences that clearly separated them from each other. In
particular, the AquaBlok stations had relatively equal
or greater abundances of individuals in the major taxonomic
groups found to occur in the sand cell.”
The report also provides a detailed framework for estimating
and evaluating the economics of AquaBlok as a Sediment remediation
management approach. It is believed that this report
will be invaluable to regulators and engineering firms that
are charged with implementation of the EPA Sediment Management
Guidelines, released in December of 2005.
About AquaBlok, Ltd.
AquaBlok, Ltd. is a manufacturer of composite (clay-based)
materials utilizing its patented coating and amendment approach. The
company has a long history in the environmental industry
and a range of products utilized in sediment remediation
technologies. AquaBlok also can deliver a wide range
of treatment materials to the sediment, including organoclay,
activated carbon, zero valent iron, sulfur and other proprietary
materials such as EHC-M™ (an Adventus Group product). Adventus
Group (www.AdventusGroup.com) is AquaBlok's exclusive seller
of these AquaBlok+ treatment products. AquaBlok also
utilizes its delivery system in a range of other products
including, pond and industrial impoundment sealing, as seep
collars on piping, to construct cut-off walls in porous soil
conditions, flood control applications (i.e. levee and dam
protection), and to deliver organoclay-based materials. In
addition, AquaBlok is a licensee of Halliburton's Bariod
Division for the Baraclear® algae treatment product.
About Adventus Group
The Adventus Group provides a growing portfolio of leading
environmental remediation technologies, including patented
offerings from Adventus Americas Inc., and EnviroMetal Technologies
Inc. Our business model supports site owners, environmental
engineers, regulators, and diverse consulting professionals
by providing unbiased design, and selection of the most cost-effective
remediation strategies.
Adventus exclusively offers DARAMEND®, EHC® and related
ZVI technologies for In Situ Chemical Reduction (ISCR) along
with TERRAMEND®, AQUABLOK+™, EHC-O™, O-Sox™,
and mGCW-R™ systems to address myriad soil, sediment
and groundwater impacts. Our world-class technical team is
a clearly recognized industry leader. Since its inception
in 2003, Adventus has successfully deployed field installations
at hundreds of sites across North America, Europe, Asia,
and Australia.
The Adventus family of companies is always seeking strategic
partnerships with complementary remediation biotechnologies,
and qualified international licensees in numerous countries. For
more information contact Michael Mueller at or
visit us online at www.AdventusGroup.com or www.eti.ca.
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