Vadose Zone Processes and Environmental Remediation

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Scope:

his Research Area addresses the processes of flow, transport, and chemical reactions that occur in the unsaturated zone (i.e., vadose zone) in soils and fractured rock. The unsaturated zone is of particular significance to hydrology because it separates the surface, where hazardous materials are frequently stored or spilled, and the saturated (groundwater) zone, on which we rely for fresh water. Despite the fact that significant resources have been spent in efforts to clean up existing contamination from within the unsaturated zone, a better understanding of unsaturated zone processes is needed to improve environmental remediation and predict flow and transport of contaminants in the vadose zone.

In this Research Area, we seek to encourage and advance studies of vadose zone processes by experimental investigations both in the laboratory and in the field, as well as by numerical modeling. Because fundamental constraints on processes come from observations, we also focus on developing new ways of monitoring physical, chemical, and microbiological processes in unsaturated soils and fractured rock.

The overall objectives of work in this Research Area are to (1) improve the fundamental understanding of unsaturated flow, transport, and transformation processes in heterogeneous soils and fractured rock, and (2) facilitate the development of effective new remediation technologies.

ESD Activities:

A large effort within ESD is focused on unsaturated zone flow and transport processes for the Yucca Mountain Project. Within this project, researchers are carrying out field and modeling studies of infiltration, seepage into drifts, geochemical and geomechanical effects of heating, ventilation in drifts, and flow and transport of radionuclides. Other work is focused on environmetal remediation. At the Hanford site, the ESD researchers, in collaboration with PNNL and a private company Regenesis, LLS, are studying the biologically mediated transformation of chromium in unsaturated-saturated sediments. In addition, we have carried out a series of infiltration and tracer tests in fractured basalt at INEEL and used these data for simulations of infiltration in fractured rock. Within the environmental remediation field, we pursue a variety of technologies to assist in the remediation efforts at Hanford, INEEL, Savannah River, Oak Ridge, international sites, and our own LBNL Site Restoration project. Although we generally focus on hydrology, our work in this area is often carried out jointly with researchers in the Geophysics, Ecology, and Geochemistry Departments.

We are currently investigating new areas in unsaturated zone and environmental remediation research, among which are:

Sensors and monitoring systems:

Mapping DNAPL transport and contamination in sedimentary and fractured rock aquifers using high-resolution borehole seismic imaging

Geophysical subsurface imaging techniques for characterizing subsurface heterogeneity, which affects solute and microbial transport properties in sediments and fractured rock:

  Remediation Technologies: 

Related Conferences/Symposiums/Workshops:

Contact:

Boris Faybishenko
ph: 510.486.4852
email: bafaybishenko@lbl.gov