New Life for Sunshine State Sites

Leveraging Innovative Design for Landfill Redevelopment

Landfill redevelopment is becoming increasingly prevalent in several Florida counties, as land suited for redevelopment is sparse throughout the state, particularly in South Florida.

Since its establishment in 1976, the Resource Conservation and Recovery Act (RCRA) has set the gold standard for properly handling certain wastes and designing, constructing, and maintaining a landfill. However, many landfills (i.e., “dump sites”) were built before RCRA became the law of the land—literally. As a result, they do not meet RCRA standards. This creates several challenges, as these dump sites are scattered across communities and, in some cases, have since been redeveloped into commercial/industrial warehouses, parking lots, and even housing.

Solving Redevelopment Challenges

Langan effectively addresses these landfill redevelopment challenges with a team of experts that navigates the issues associated with building atop Class I (municipal solid waste), Class III (yard waste), construction and demolition (C&D) debris landfills, and unregulated dump sites. Landfill redevelopment is very complex because one must consider the potential sources and exposure pathways; the end goal of each project is to render the exposure pathways incomplete or employ innovative, cost-effective designs to manage the associated risks.

For example, while providing environmental engineering services for a warehouse development located atop a permitted and closed C&D landfill, which operated from 1999 to 2004 and closed in 2017, Langan maneuvered through a maze of permitting requirements, local codes, and regulations. Once the redevelopment was initiated through a zoning variance, Langan was called upon to navigate complex statutes of the Florida Department of Environmental Protection (Chapter 62-701 for solid waste) and Miami-Dade County (Chapter 24-44 for contaminated sites) to address landfill considerations.

Implementing Practical Solutions

The team mitigated an array of issues with the landfill redevelopment, which included reducing the amount of soil disposal, avoiding expensive groundwater remediation, designing an innovative methane gas management system, and identifying suitable locations for stormwater management (Florida rule alert: stormwater cannot be discharged over a contaminated plume).

In response, Langan approached the soil remediation through a combination of soil and waste source removal and relocation to meet future design grades, limiting leachate generation through strategic material placement, which saved the client millions of dollars on disposal. Additionally, groundwater was managed through a combination of delineation in the deep aquifer and long-term monitoring (with a focus on the conceptual site model of nearby extraction systems), while methane was managed via a mitigation system with unique nuances for strategic placement and operations.

Through these innovative, risk-based approaches to complex landfill redevelopment challenges, the team delivered an effective project that successfully protects human health and the environment for hundreds of warehouse employees.

Manivannan (Mani) Nagaiah, PE, has over 18 years of experience navigating complex redevelopment and remediation projects. His project management approach focuses on delivering cost-effective, innovative designs for clients by providing multidisciplinary services for complex urban redevelopment projects. He has managed Langan’s overall work on multiple design projects.