GEOWEB® Slope Protection System

Project Name: 68th Street Dump Superfund Site Landfill Capping Project

Project Location: Baltimore, MD

Site Background and Historical Context

The 68th Street Dump Superfund Site, located in Rosedale, Baltimore County, Maryland, covers a substantial 239-acre area and comprises multiple landfills. These landfills were operational from the 1950s to the 1970s, accepting a wide range of industrial and commercial wastes. Over the decades, hazardous substances accumulated, posing significant environmental and health risks. In response, the site was designated a Superfund site, necessitating a comprehensive remediation strategy to prevent further contamination and ensure public safety.

Environmental Remediation Challenges

The primary challenge at the 68th Street Dump Superfund Site was to develop and implement an effective capping solution that would:

• Isolate the hazardous materials to prevent the spread of contamination.
• Ensure compliance with stringent Environmental Protection Agency (EPA) guidelines requiring 12 inches of cover over the contaminated areas.
• Manage the complex topography of the site, which included slopes with varying vertical heights up to 60 feet.
• Provide a durable, long-term solution that could withstand environmental conditions and reduce the need for ongoing maintenance.

Comprehensive Remediation Solution

The remediation project was spearheaded by a large international engineering firm, with Colonial Construction Materials supplying the necessary materials and Entact Environmental Remediation & Geotechnical Construction handling the installation. Presto Geosystems’ engineering team conducted a thorough project evaluation to devise an optimal capping solution. The evaluation included an analysis of the site-specific conditions, leading to tailored recommendations for the different slope heights.

The solution involved capping 51,000 square feet of the landfill (all slopes steeper than 3:1) using the GEOWEB® Soil Stabilization System GW30V12 (12-inch depth geocells) with a topsoil infill to support vegetation. This innovative approach ensured a robust and stable cap, effectively containing the hazardous materials and meeting the EPA’s requirement of a 12-inch cover.

Representatives from Presto Geosystems and Colonial Construction Materials provided on-site technical and installation support to ensure the success of the project.

Design Specifications and Installation Process

Presto Geosystems provided tailored recommendations based on the varying vertical heights to ensure efficiency and effectiveness in the installation process. The design and installation process incorporated four different anchorage recommendations depending on slope height to ensure efficiency and effectiveness:

Pre-Assembly and Connection:

• The GEOWEB sections were pre-assembled at the crest of the slope with tendons and ATRA Tendon Clips (load transfer device), which were then anchored at the crest of the slope.
• Sections were connected using the patented ATRA® Keys. These keys are inserted through adjoining GEOWEB cell walls, turned, and locked to provide the most secure connection.

Tendon and Load Transfer Device Assembly:

• ATRA® Tendon Clips were used to secure the tendons running through the GEOWEB cells. These clips locked with the GEOWEB cell walls, while a looped tie-off ensured the tendons remained securely attached.
• This setup was crucial in preventing the slope system from shifting, providing an effective erosion control solution.

Anchoring and Installing the GEOWEB:

• The anchored GEOWEB sections were deployed down the slope, ensuring that each section was securely anchored and properly aligned.

Final Infill and Vegetation Support:

• The topsoil infill was added to the GEOWEB cells, ensuring a 12-inch cover as required by EPA guidelines. The topsoil filled cells were then hydroseeded to encourage quick vegetation growth.
• Topsoil supports vegetation growth, contributing to the long-term stability and environmental integration of the capping solution.

Benefits of the GEOWEB System

The successful implementation of the GEOWEB Soil Stabilization System at the 68th Street Dump Superfund Site provided several benefits:

• Enhanced Slope Stability: The GEOWEB system’s three-dimensional structure effectively stabilized the surface of the steep slopes of the landfill, preventing erosion and maintaining the integrity of the cap.
• Ease of Installation: The use of tendon-pre-assembled sections and ATRA accessories streamlined the installation process, reducing labor costs and time on site.
• Secure Connections: The ATRA Tendon Clips and ATRA Keys ensured secure and robust connections between the tendons and the GEOWEB cells and between the panels, preventing any displacement of the system under environmental stresses.
• Vegetation Support: The topsoil-filled GEOWEB geocells provided a stable growing medium for vegetation, promoting rapid establishment and long-term sustainability of the vegetative cover.
• Environmental Integration: By supporting vegetation growth, the GEOWEB system helped blend the capped landfill into the surrounding environment, enhancing the aesthetic and ecological value of the site.
• Long-Term Performance: The durability and stability of the GEOWEB system reduced the need for ongoing maintenance, offering a cost-effective long-term solution for the containment of hazardous materials.

The 68th Street Dump Superfund Site landfill capping project successfully addressed a critical environmental challenge. The installation of the GEOWEB Soil Stabilization System provided a durable and effective solution for containing hazardous materials. This project helps prevent future contamination, supports vegetation growth, and reduces the need for ongoing maintenance. The area is now on its way to becoming the largest green space in the greater Baltimore area, offering long-term benefits to the community and the environment.