LNAPL

Light Non-Aqueous Phase Liquids (LNAPL) spills present a significant challenge to remediate. They can result in extensive contamination from small spillages and their mobilisation can be more extensive than that of DNAPL.

LNAPL is a liquid that is sparingly soluble and less dense than water. It forms a pool on top of the water table along its natural contours thus extending the plume area over time.

Effective remediation of LNAPL contaminated sites can be undertaken with a variety of technologies dependant upon the required remediation criteria.

Often more than one technology can produce the best results. Generally the initial remediation will require the recovery of the free product from either abstraction wells or excavations. This is known as source removal and may require some soil sources to be treated at the same time.

Once the main source is removed the dissolved phase in the groundwater, and any remaining product adhering to the soils, can be treated. This can be achieved utilising a number of technologies including pump and treat, multiphase abstraction, bioremediation, chemical oxidation, air sparging or vacuum extraction dependant on the contaminant being recovered.

Careful management including efficient and targeted monitoring of the remediation works by laboratory analysis are crucial to the understanding of how the works are progressing.

The most common forms of LNAPL are hydrocarbons.