The critical height for DNAPL entry into a partially water saturated, dead-end fracture is derived and compared to laboratory observations. Experiments conducted in an analog, parallel-plate fracture demonstrate that DNAPL accumulates above the water until the height of the DNAPL overcomes the sum of the capillary forces at the DNAPL-air interface and at the DNAPL-water interface. These experiments also show that DNAPL preferentially enters the water at locations where DNAPL has previously entered, and the entry heights for these subsequent entries are lower than the heights measured for the initial invasion. The wetting contact angle at the DNAPL-water interface becomes larger at the locations where the DNAPL has already entered the water because of residual DNAPL on the fracture walls, which results in lowering the critical entry height at those locations. The experiments also demonstrate that a DNAPL lens can remain nearly immobile above the water for a period of time before eventually redistributing itself and entering the water.

Both the measurement of temperature and the simulation of heat and water transport have benefited from significant recent advances in data acquisition and computer resources. This has afforded the opportunity for routine use of heat as a tracer in a variety of hydrological regimes. Heat is particularly well suited for investigations of stream/groundwater exchanges. Dynamic temperature patterns between the stream and underlying sediments are typical, due to large stream surface area to volume ratios relative to other surfacewater bodies. Heat is a naturally occurring tracer, free from (real or perceived) issues of contamination associated with use of chemical tracers in stream environments. The use of heat as a tracer relies on the measurement of temperature gradients, and temperature is an extremely robust parameter to monitor. Temperature data is immediately available as opposed to chemical tracers, which often require significant laboratory analysis. In this work, we report on the progress in the use of heat as a tracer to determine the hydraulic conductance of the streambed along the middle reaches of the Russian River, located west of Santa Rosa, CA. The general hydrological setting is described and the unique matter in which the water resources are managed in an environment of increasing population, a rapid shift to agricultural crops requiring more irrigation, and a series of fishery related mandates.

The Gardner and van Genuchten models of relative permeability are widely used in analytical and numerical solutions to flow problems. However, the applicab ility of the Gardner model to real problems is usually limited, because empirical relative permeability data to calibrate the model are not routinely available. In contrast, van Genuchten parameters can be estimated using more routinely available matric potential and saturation data. However, the van Genuchten model is not amenable to analytical solutions. In this paper, we introduce generalized conversion formulae that reconcile these two models. In general, we find that the Gardner parameter alpha G is related to the van Genuchten parameters alpha vG and n by alpha G=alpha vG ~; 1:3 n. This conversion rule will allow direct recasting of Gardner-based analytical solutions in the van Genuchten parameter space. The validity of the proposed formulae was tested by comparing the predicted relative permeability of various porous media with measured values.

This report details the work done between June 13 and September 30, 2006 by Lawrence Berkeley National Laboratory (LBNL) scientists to assist Fermi National Accelerator Laboratory (Fermilab) staff in understanding tritium transport at the Neutrino at the Main Injector (NuMI) facility. As a byproduct of beamline operation, the facility produces (among other components) tritium in engineered materials and the surrounding rock formation. Once the tritium is generated, it may be contained at the source location, migrate to other regions within the facility, or be released to the environment.