U.S. Geological Survey, Branch Of Acquisition and Federal Assistance, Box 25046, Denver Federal Center, Denver, CO 80225-0046

R -- PROFESSIONAL SERVICES FOR CALCULATION PROGRAM ENHANCEMENTS POC Diana Romero, (303) 236-5900 ext. 344 E-MAIL: Click here to contact the Contracting officer via, dlromero@usgs.gov. The U.S. Geological Survey, Yucca Mountain Project, Boulder, Co., 80225, has a requirement for an application of and enhancements to the new version of the computer program MODFLOW, referred to here as MODFLOW-2000. A preliminary Death Valley regional flow system (DVRFS) model has been published, and will require refined version of the model. The application involves Advective Travel Observation (ADV) Package of MODFLOW-2000 used to apply nonlinear regression methods to the calibartion of ground water flow models. Enhancement shall include, track particles backward from the selected areas of springs at the base of the Spring Mountain (including As Meadows) to determine where the simulated spring flow originates. Use the sensitivity capabilities of the Advective Transport Observation(ADV) Package to determine what parameters are important to the paths and rates simulated. Perform these simulations using the trhee layer model and report results in a letter report. Begin similar simulations using the fifteen layer model. Program the additive parameters capabiltity in the Hydrogeologic Unitl Flow (HUF) Pacages, complete the report documentation and publish it. Complete the quality assurance procedure for the HUF Package, report on progress regularly and submit progress reports. As part of this work the existing version of MODFLOW-2000 will be used to evaluate the simulated flow of water to springs discharging at Ash Meadows and springs discharging at the base of the Spring Mountains. The current version of MODFLOW-2000 Hydrogeologic Unit Flow (HUF) Package does not fully support the four capabilities essential to the DVRFS model: gradual spatial veriation of fracture characteristics or grain size; tracking of particles with the Advective Travel Observation (ADV) Package through individual hydrogeologic units defined in the HUF Package; horizontial anisotropy directions that are not rigidly fixed based in the finite difference gride orientation; and a numerically stable way of allowing finite difference cells to become dry and to then become saturated again. Based on the information at this tim, and in accordance with 41 U.S.C. 253 (1), implemented by FAR 6.302-1, the Government considered the services specified as a sole source from Calibra Cunsulting, LLC, 1776 Lincoln Street, Suite 500, Denver, CO 80203-1018, and proposes to negotiate a contract with that firm on that basis. However, should additional sources be identified, they will be considered. Firms who feel that they can furnish the required services or its functional equivalent (based upon the criteria specified herein) are invited to submit in writing an affirmative response to this annoucement. An affirmative response would include literature, brochures, and such other materials which correspond to the required servies stated herein. This information will be evaluated and used to determine if competitive opportunities exist. Since no solicitation document exist, request for such documents without accompanying information will be considered non-responsive to this request without further consideration. This notice may represent to the Government's only official notice of this procurement. See Notes 22. Posted 08/12/00 (W-SN485299). (0225)

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