Overcoming Slope Failures at a Closed Landfill Site

Project Background

A closed landfill operator faced significant safety concerns due to multiple shallow slope failures along an exterior slope near a main access roadway. EARTHRES was engaged to perform a detailed investigation and develop an economical remediation plan. The comprehensive approach taken resulted in a six-step progressive remediation recommendation process, ensuring long-term slope stability and safety while managing costs effectively.

The Challenge

The primary challenge faced by the client was ensuring slope stability in the absence of comprehensive historical data. Given the age and closed status of the landfill, records of waste placement, leachate collection and detection system details, liner system details, capping system details, and phased development plans were limited.

Additionally, the shallow slope failures near a main access roadway heightened the need for a thorough investigation and an effective remediation plan.

Key challenges included:

• Limited historical data on the landfill’s construction and operational history.
• Multiple shallow slope failures, posing safety risks and operational challenges.
• The need for an economical solution that could adapt to the evolving conditions of the slope.

The Solution

EARTHRES was tasked with developing a comprehensive and cost-effective solution to address the slope failures. The approach included a thorough review of existing conditions and the development of a progressively tiered remediation plan.

Steps Taken by EARTHRES:

1. Historical Data Review of Landfill Site

• Conducted an in-depth review of available historical data to understand the site’s conditions.
• Analyzed stormwater conditions, toe drain conditions, s lope settlement over time, slope maintenance condition, stormwater channel maintenance, and changes in vegetative condition of the slope.

2. Slope Stability Modeling

• Created an iterative sensitivity model of material strength properties and forces to determine a slope failure condition.
• Identified major contributors to slope failure and assigned performance/indicator criteria to each potential contributor.
• Performed sensitivity analyses on each identified major contributor to understand their impact on slope stability.

3. Development of Landfill Slope Failure Remediation Plan

• Designed a six-step progressive remediation recommendation process to implement remedial efforts in response to observed slope responses.
• Provided an engineer’s opinion of probable costs for each of the six remediation steps, ensuring an economical approach.

The Results

The solution resulted in significant safety improvements and operational efficiencies for the client. Key outcomes included:

• Improved Safety: The progressive remediation plan ensured that slope stability was continuously monitored and addressed, reducing the risk of further slope failures and enhancing personnel safety.
• Cost-Effective Landfill Solutions: The six-step remediation process allowed the client to implement remedial efforts as needed, optimizing costs and resources over time.
• Enhanced Understanding of Slope Conditions: The sensitivity analyses and iterative modeling provided a detailed understanding of the factors contributing to slope failures, enabling more effective long-term management.

The collaboration resulted in a robust and economical solution to address the slope failures at the closed landfill site. Our team’s expertise and methodical approach ensured that the remediation efforts were effective, safe, and cost-efficient.