LNAPL Remediation Technologies

There are a variety of Light Non-Aqueous Phase Liquid (LNAPL) remediation approaches. This article provides brief summaries of some LNAPL remediation technologies with links for additional information. Results from performance evaluations are presented. Finally, the Interstate Technology and Regulatory Council (ITRC) framework for selecting LNAPL remediation technologies is presented.

Related Articles

• LNAPL Conceptual Site Models (coming soon)
• NAPL Mobility
• Vapor Intrusion - Separation Distances from Petroleum Sources
• Petroleum Hydrocarbons (PHCs)

Contributors: Shahla Farhat, Tom McHugh, Phil de Blanc

Key Resources:

• LNAPL Site Management: LCSM Evolution, Decision Process, and Remedial Technologies (LNAPL-3)

• Managing Risk at LNAPL Sites - Frequently Asked Questions, 2nd Edition

• Progress in Remediation of Groundwater at Petroleum Sites in California

Problem Definition

LNAPL releases can result in a range of adverse impacts, and an effective remediation approach needs to match the impact. The nature of the potential LNAPL concerns include:

• Risk to health and safety based on LNAPL composition. This includes the generation and migration of dissolved hydrocarbon plumes that can affect drinking water resources, and the generation of hydrocarbon vapors that can, in limited circumstances, create vapor intrusion risks. (See also: Vapor Intrusion - Separation Distances from Petroleum Sources)
• The migration of LNAPL itself (based on the LNAPL saturation) which expands the LNAPL source zone and, in some circumstances, can cause sheens on surface water at discharge points. (See also: NAPL Mobility)
• LNAPL-specific regulatory requirements (such as removal of LNAPL to the “maximum extent practicable”).
• Other physical or aesthetic impacts, such as odors or soil stability issues.

To address these concerns, general LNAPL remediation goals and technology-specific remediation objectives can be developed. General technology classes include:

• Mass Removal Technologies (e.g., hydraulic recovery of LNAPL)
• Mass Control Technologies (e.g., barrier wall)
• Phase Change Technologies (e.g., soil vapor extraction)
• Natural Source Zone Depletion (NSZD)

However, even with the wide range of remediation technologies that are available, LNAPL remediation can be challenging. Sale et al. (2018) described the problem this way: