SURFER® and API’s Interactive Light Non-Aqueous Phase (LNAPL) Guide software applications were used to complete a stability analysis for a hydrocarbon plume in Wyoming. The analysis indicates that between calendar years 2002 and 2016, the mass and footprint of the dissolved plume were reduced by approximately 63 and 32 percent, respectively. Over a similar time period, the LNAPL mass was estimated to have been reduced by 99 percent.

SURFER was used to calculate the plume volume and average overall dissolved contaminant concentration. These data along with the aquifer porosity were then entered into an EXCEL spreadsheet to calculate the plume’s total dissolved hydrocarbon mass for calendar years 2002 and 2016.

A similar process was performed to evaluate the change in free product mass except that the thicknesses of LNAPL were gridded in SURFER rather than dissolved petroleum concentrations. API’s Interactive LNAPL Guide software application was then used to estimate the average fraction of free product within the saturated soil pores of each contour interval. These data along with the aquifer porosity were then entered into an EXCEL spreadsheet to estimate the mass of LNAPL present in calendar years 1999 and 2016.

Primary Author/Conference Presenter:
Boyd Breeding
Sr. Engineer / Hydrogeologist
AECOM
Salt Lake City, UT, USA

Co-Authors:
McLean Carpenter, AECOM, Salt Lake City, UT, USA
Lyndsey Anderson, AECOM, Salt Lake City, UT, USA
Lawrence Cannon, AECOM, Salt Lake City, UT, USA