Lance Robinson, P.E.

Expanding the Applicability of Air Sparging Using Horizontal Wells

Lance Robinson, P.E., President, EN Rx

A common design obstacle for air sparging is the presence of a dense or semi-confining layer immediately beneath a thin plume. Conventional guidance often discourages air sparging under these conditions because there is insufficient depth below the plume for the injected air to develop the characteristic parabolic distribution before rising through the treatment zone. However, this limitation may not apply to horizontal air sparge wells. Because air is introduced continuously along the length of the horizontal well, treatment does not depend on the development of an expanding ROI vertically, allowing effective treatment in hydrogeologic settings that are often considered unsuitable for conventional vertical sparging.    This presentation describes a Central Florida petroleum site where horizontal air sparge wells installed only approximately 7 feet into the water table achieved rapid BTEX reduction despite a lower clayey unit that precluded conventional sparge depths. The horizontal system also minimized disruption at a high-volume service station with a very small treatment footprint, requiring short bores 150 to 216 feet for horizontal well installation. The site achieved regulatory closure within approximately three years. This case study demonstrates that horizontal air sparging can expand the applicability of air sparging to sites where conventional design guidance would otherwise limit its use.

Lance I. Robinson, P.E., is the President of EN Rx and co-developed the Vertebrae™ Well Systems and the EN Rx Support Platform (SP) technologies during his 13-year tenure. Prior to EN Rx, Robinson worked for 10 years as a design and assessment engineer for various environmental consultants in the remediation industry. His experience spans projects in petroleum, pesticides, and solvent remediation, completing projects from inception through closure. Robinson graduated from the University of South Florida with a B.S. in Chemical Engineering.