National Lab, Oak Ridge National Lab, Rice 

 University, SUNY-Stony Brook, Texas A&M, 

 and the University of South Carolina. A map of 

 the site most extensively studied (WAG 6) is 

 given in Figure A. Researchers at ORNL have 

 adapted an existing finite element code to run on 

 an Intel scalable parallel distributed-memory 

 system. By using a preconditioned conjugate 

 gradient solver, users were able to distribute por- 

 tions of the model grid to different processors 

 and greatly reduce solution time. Using a 

 40,000 node grid (Figure B), they are obtaining 

 anisotropy factors and boundary conditions that 

 can be used to model smaller areas and test the 

 effects of remediation schemes on models of the 

 waste areas. One such remediation scheme is to 

 cover areas with a water-impermeable mem- 

 brane (cap) to eliminate surface recharge (Figure 

 C). A calculation of the water table following a 

 capping is given in Figure D. Such results point 

 to the specific piezometric wells for which 

 experimental indications of capping effects 

 should be sought. 



Pacific Northwest Laboratory is also exploring 

 the use of scalable massively parallel quantum 

 chemistry algorithms to improve methods for 

 redesigning enzymes to better degrade pollu- 

 tants, for extracting contaminants from soils, and 

 for burning halohydrocarbons. 



Researchers at the EPA's Robert S. Kerr 

 Environmental Research Laboratory and collab- 

 orators at various universities have focused 

 efforts on developing process understanding 

 using complementary numerical models and lab- 

 oratory studies. Implementation of numerical 

 models has followed approaches originally 

 developed in the petroleum industry and 



advanced multiprocessor techniques. A large 

 scale physical model is currently being used to 

 evaluate the numerical model. Release of an 

 organic liquid is planned for the physical model, 

 followed by testing of remedial technologies. A 

 remediation approach involving surfactant flood, 

 followed by vapor extraction above the water 

 table, is being designed by bench scale laborato- 

 ry studies and adaptation of a sophisticated 

 numerical model developed by the University of 

 Texas at Austin. Other remediation models are 

 also under development. Joint field and model- 

 ing studies in cooperation with the USDA are 

 underway to assess the impact of agricultural 

 chemicals on water resources in the midwest. 



Groundwater models will not eliminate the need 

 for adequate field data but will continue to assist 

 scientists in understanding these complex sys- 

 tems, thus contributing to reducing the risks to 

 public water supplies. 



SPONSORING AGENCIES AND 

 ORGANIZATIONS 



DOE 



EPA 



PERFORMING ORGANIZATIONS 



EPA's Robert S. Kerr Environmental Research 



Laboratory 

 Pacific Northwest Laboratory 

 Partnership in CompiUationai Science (PICS) 

 Consortia 



- Brookhaven National Lab 



- Oak Ridge National Lab 



- Rice University 



- SUNY-Stony Brook 



- Texas A&M 



- University of South Carolina 

 University of Texas at Austin 



136 



