FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

Mr. Michael T. Goldstein October 18 , 1985 Page 2 program that can simulate solute transport in groundwater (Prickett, T. A. , and others; A Random Walk Solute Transport Model for Selected Groundwater Quality Evaluations, " Bulletin 65 of the Illinois State Water Survey) . The effects of dispersion and chemical reactions ( retardation) are included. The code can simulate nonsteady or steady flow problems in hetrogeneous aquifers under confined and/or unconfined and leaky conditions . The program covers pumping and injection by wells and allows specification of chemical constituent concentrations in any segment of the model. Further features of the program include variable grid size, printout of input data, sequential plots of solute concentration distributions , concentrations of water recharged to the modeled area , quantities of chemical constituents removed by pumpage and the effects of dispersion and dilution or mixing of waters having different solute concentrations. The basis for the solute transport calculation in this code is that the distribution of concentrations can be represented by the distribution of a finite number of discrete particles. Each particle is assigned a mass which represents the weight of pure solute dissolved in an element of aquifer to produce a convenient unit concentration, i .e. , 100 ppb for each particle in an element. The particles are removed by groundwater flow and the changes in concentration are controlled by dispersion, retardation, dilution, and mixing . The groundwater flow vector is entered as the regional velocity and modified as the head distribution is changed. The dispersion is calculated as a random process tending to a normal distribution moderated by longitutinal and transverse dispersivity. The retardation is a coefficient that includes adsorption, organic fixation, and biodegradation. Basic Transport Coefficient The basic transport coefficients defined for the shallow aquifer in the vicinity of the Georgia-Pacific plant are as follows : Tiansmissivity = 150 ,000 (gpd/ft ) Storage coefficient = 0 .01 (dimensionless) Hydraulic conductivity = 3 ,750 (gpd/sq ft) Porosity = 0 . 30 (dimensionless) Longitudinal dispersivity = 27 ( ft) Transverse dispersivity = 6.5 ( ft) Retardation coefficient = 1.0 (dimensionless) Regional X flow = -0 . 53 ( ft/day) Regional Y flow = 1 . 57 ( ft/day) Particle mass = 0 . 7488 ( lbs) BROWN AND CALDWLLL .. 6.0 N 1619'1 OUIp If I I% n Dd'Ip•Of I if Al JA NI bu,I If AVI 14tI I I I kp V1I I IH I