A new tool to determine the volume of subsurface light non-aqueous phase liquid (LNAPL) has been created. The tool is an extension of the commonly-used LNAPL distribution and recovery (LDRM) tool developed for the American Petroleum Institute (API).

The LDRM calculates LNAPL specific volume (Do) and transmissivity (Tn) at a single location for up to three soil layers. A limitation of the software is the need develop a separate input file to calculate Do and Tn at each location where LNAPL apparent thickness has been measured.

A spreadsheet has been developed that overcomes some of the limitations of the LDRM. The spreadsheet calculates Do and Tn at an arbitrary number of locations for up to ten different soil layers of differing lithology. Any number of soil types and properties may be specified by the user. The simultaneous determinations of Do and Tn at many locations saves a tremendous amount of time when many locations must be analyzed. The spreadsheet also automatically interpolates Do data to estimate the total volume of LNAPL in the subsurface using a publicly-available Kriging routine. The automatic interpolation avoids the need to export Do data to a GIS or contouring package to calculate subsurface LNAPL volumes.

Primary Author/Conference Presenter:
Dr. Phillip de Blanc
Senior Associate
GSI Environmental Inc.
Houston, Texas, USA

Shahla K. Farhat, Ph.D., GSI Environmental Inc., Houston, TX