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Title: Colloid transport and retention in fractured deposits. 1997 annual progress report

'The goal of this project is to identify the chemical and physical factors that control the transport of groundwater colloids in fractured porous media and develop a generalized capability to predict colloid attachment and detachment based on hydraulic factors (head, flow rate), physical structure (fracture aperture), and chemical properties (surface properties of colloids and fracture surfaces). Understanding the processes that control colloid behavior will increase the confidence with which colloid-facilitated contaminant transport can be predicted and assessed at various contaminated US Department of Energy (DOE) sites. An added benefit is the expectation that this work will yield novel techniques to either immobilize colloid-bound contaminants in situ or mobilize colloids for enhancing remedial techniques such as pump-and-treat and bioremediation. Research Statement A series of field-scale and laboratory-scale experiments, using both natural undisturbed samples and simple one-dimension ``artificial fractures,'''' are in progress to investigate the influence of physical and chemical factors on the transport of colloids in fractured materials. The experimental results will be assessed using a computer model (COLFRAC) developed to simulate colloid transport in fractured materials. The overall goal is to assess the relative influence of chemical and physical factors expected to influence colloid transport in fractured materials and investigatemore » strategies for predictive simulation at the field scale. The experimental methods each operate at different physical/geological scales and can be used with different degrees of experimental control. This allows testing of hypotheses in a relatively simple setting in the laboratory where individual chemical or colloidal characteristics can be varied and then the results compared with field-scale experiments where the influence of realistic geologic heterogeneity can be incorporated. The work is organized into interacting tasks dealing with theoretical descriptions of colloid transport in fractures, transport studies at three spatial scales (simple one-dimensional fractures, laboratory columns of intact geological material, and field-scale colloid tracer studies), and computer modeling of colloid transport processes. A continuing iteration among all tasks and experimental scales is envisioned throughout the project. Predictions based on laboratory experiments in simplified artificial fracture systems will be tested in column and field studies, and, likewise, hypothesized interpretations of the results of the column or field studies will be tested and verified in additional laboratory studies. Experimental efforts at all scales will begin with simple binary comparisons (e.g., large vs small colloids with similar surface chemistry), and proceed with increasing complexity (e.g., varying surface properties of colloids or fractures) as understanding is developed. It is only through this parallel iteration at different scales that predictions based on laboratory understanding can be tested in column and in field studies so that additional research-can be conducted to resolve observations that were not consistent with the earlier descriptions of controlling processes.'« less
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Oak Ridge National Lab., TN (US)
  2. Los Alamos National Lab., NM (US)
  3. Ohio State Univ., Columbus, OH (US)
  4. Tennessee Technological Univ., Cookeville, TN (US)
  5. Univ. of Tennessee, Knoxville, TN (US)
Publication Date:
OSTI Identifier:
Report Number(s):
ON: DE00013536
Resource Type:
Technical Report
Research Org:
Oak Ridge National Lab., TN (US)
Sponsoring Org:
USDOE Office of Environmental Management (EM), Office of Science and Risk Policy
Country of Publication:
United States
58; 40; 54; 05; Progress Report; Fluid Flow; Colloids; Mechanics; Chemical Reactions; Environmental Transport; Remedial Action; High-Level Radioactive Wastes; PROGRESS REPORT; FLUID FLOW; COLLOIDS; MECHANICS; CHEMICAL REACTIONS; ENVIRONMENTAL TRANSPORT; REMEDIAL ACTION; HIGH-LEVEL RADIOACTIVE WASTES