Foam Delivery of Amendments for Vadose Zone Remediation – Propagation Performance in Unsaturated Sediments
Foam delivery of remedial amendments is potentially useful for vadose zone remediation because aqueous amendments are delivered while maintaining a low water content. The transport behavior of foam in the vadose zone is not well studied. Bench top scale column tests were conducted to investigate the foam transport, foaming gas and liquid propagation, pressure build up and distribution, influence of foam quality and sediment permeability on foam injection pressure, and liquid up-taking and distribution in sediments during foam flow in unsaturated sediments. Results indicated that under the unsaturated conditions, foaming gas front traveled much faster than the foam front where bubbles rupture was significant. A liquid front was formed ahead of the foam flow front. The accumulated liquid in this front was mainly composed of the water injected with foam. The foam injection pressure was mostly attributed to the resistance to foam flow from the sediment, but not to the movement of the water ahead of the foam front. Foam had a high effective viscosity compare to water. A near linear pressure distribution within the foam-occupied column section was observed. At fixed injection rate, higher foam quality resulted lower injection pressure. Higher permeability sediments did not necessarily have a lower foam injection pressure, as other factors such as the foam injection rate, foam bubble diameter, and sediment pore size also influenced the pressure. In the foam flushed region, the liquid uptake and the water content distribution in sediment was barely affected by the initial water content and the foam injection rate. The implications of these findings in field remediation application were discussed.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 988123
- Report Number(s):
- PNNL-SA-70394; EY4049110; TRN: US201018%%132
- Journal Information:
- Vadose Zone Journal, 9(3):757-767, Vol. 9, Issue 3; ISSN 1539-1663
- Country of Publication:
- United States
- Language:
- English
Similar Records
Enhanced Remedial Amendment Delivery to Subsurface Using Shear Thinning Fluid and Aqueous Foam
Foam Transport in Porous Media - A Review