EAGLE RIVER FLATS (OPERABLE UNIT C)
Fort Richardson, Alaska

A field pilot study was conducted by the United States Department of Agriculture (USDA) to evaluate the effectiveness of an AquaBlok (TM) cap over a tidally-influenced marsh. Waterfowl were roosting on the wetland's sediments that had been impacted with white phosphorus.

The study established a treated (or capped) area and a controlled (or uncapped) area; each approximately 1-acre in size. The waterfowl mortality rates were monitored for the next twelve months. A secondary aspect of the field study involved observing the degree and extent of vegetative growth across the capped area.

Results
The results of the pilot study demonstrated that AquaBlok (TM) successfully covered the impacted sediments and thereby, reduced the mortality rates of the waterfowl. The results also confirmed that AquaBlok (TM) can support wetland vegetation growth.

AquaBlok (TM) was incorporated into the 1998 Record of Decision for this Superfund Site, as one of two proven remedies for addressing the impacted sediments at this location.

Before After

OTTAWA RIVER
Toledo, Ohio

 This demonstrative project involved the installation and field-scale testing of different AquaBlok (TM) sediment-cap designs.

The primary project goals were to:

• Assess the relative, long-term effectiveness of an 2.5-acre AquaBlok (TM) based sediment cap by physically stabilizing and isolating impacted sediments, including PCBs and other organic and inorganic compounds.
• Demonstrate different techniques for cap construction (including a conveyor, a crane with clamshell, and a helicopter) to evaluate their relative effectiveness; and
• Develop general costs for the project.

An additional project goal was to assess long-term benthic colonization of encapsulated areas. Hull & Associates, Inc. provided AquaBlok Ltd. with the technical and project assistance and also acted as the City of Toledo’s primary engineering and environmental consultant. The Ohio EPA assisted with the benthic colonization assessment.

Results
Good spatial coverage of capping materials across targeting areas was achieved, as well as adequate and relatively consistent, hydrated cap thicknesses. Together, these observations demonstrate the viability of the different techniques to accomplish cap construction.

Monthly monitoring of near-bank, encapsulated areas (through seasonal freeze-thaw and periodic high-flow conditions) indicated AquaBlok (TM) stabilized and isolated impacted sediments in these areas. Significant sediment deposition over the cap was also observed along near-bank areas.

UTILITY COMPANY
St. Louis, Missouri

The objective of this project for Remedial Construction Services, L.P. (RECON) was to stabilize a 700-foot stretch of a creek bank that ran along the backside of the client's property.

Initially, the project included the removal of existing trees and vegetation to allow access to the creek. RECON then excavated the existing fill materials, removed undesirable fill materials, and regraded and compacted the new materials to the required lines and grades. Approximately 1,500 feet of maintenace road was installed, including a french drain system in the lower portion of the access road.

Final grading of the upper slope included placement of vegetation with erosion control matting, popular trees, and grass seed. The lower slopes received a layer of geotextile, followed by a layer of Geoweb, which was filled with silty clay and AquaBlok (TM) material. The Geoweb was covered by a layer of Stratapec along with a layer of crushed limestone and riprap.

In order to the anchor trench in the creek bottom to be installed correctly, the creek was temporarily diverted using submersible pumps powered by a mobile generator unit.

Re-vegetating the remaining disturbed areas and installing approximately 900 feet of six-foot tall chain-link fencing completed the project.