ARCHIVED REPORTS_2011 REVISED FEASABILITY STUDY

Home Browse Search

MODFLOW/RT3D simulated groundwater extraction at the existing Industrial Avenue treatment system with wells EU-3 and EU-4 at a pumping rate of 30 gpm each. Extraction at the existing Stockton Avenue treatment system will be conducted at a rate of 60 gpm at well E-2 and at 300 gpm at well E-6. Groundwater extraction will be conducted at three additional extraction wells completed in the Intermediate Aquifer at pumping rates of 100 gpm each and at two additional extraction wells completed in the Lower Aquifer at 200 gpm and 100 gpm, respectively. For this model run, known vertical conduits, particularly municipal wells MW-4 and MW-6 are assumed to have been eliminated. In addition, several municipal and private wells (MW-3, MW-11, MW-7, MW-9, and irrigation wells at Ripon Christian and Ripon Public schools, and the Caltrans well) are assumed no longer extract groundwater as part of the institutional controls proposed for this Alternative. The scenario simulates predicted groundwater elevations and TCE concentrations via a transient model run which is run for 30 years into the future. The following table summarized the key boundary conditions and/or TCE source area conditions employed in the simulation of the Revised Feasibility Study Alternative 2: Table A2: Alternative 2 MODFLOW/RT3D Modeling Inputs Model Boundary Condition/Property Conditions in Alternative 2 Modeling Scenario Domestic/Agricultural Pumping Wells Pumping terminated for entire model run at wells MW-3, MW-11, MW-7, MW-9, and irrigation wells at Ripon Christian and Ripon Public schools (RC- 1, RC-2, RPS-1, and RPS-2), and Caltrans well. Average quarterly extraction rates from calendar year 2008 used for all other domestic and agricultural wells throughout transient model run. Remediation Wells Extraction wells EU-3 and EU-4 (Upper Aquifer IRAP wells) assumed to continue pumping at 30 gpm each throughout model run. Extraction wells E-2 and E-6 are assumed to continue at 60 gpm and 300 gpm, respectively, throughout transient model run. Source Area Remediation Source area mass removal simulated via groundwater extraction at wells E-2, E-6, EU-3 and EU-4 and five additional extraction wells. All TCE source area cells assumed to degrade at base model-established intrinsic biodegradation rate k= 0.000316 day-'). Other adjustments to base period Vertical transmissivity at municipal wells MW-4 conditions: and MW-6, and Neenah Paper Company wells TH-8, TH-10, S-1, S-2, S-3, S-4, S-5 adjusted to mitigate vertical migration at these locations. The primary areas of TCE impacts and changes over time in the Upper Aquifer under this modeling scenario are illustrated in figures A-14 through A-17, in the Intermediate Aquifer in figures A-18 through A-21; and in the Lower Aquifer in figures A-22 through A-25. Figure A-26 shows the 3D distribution of TCE concentrations greater than 5 lag/L beneath the Study Area after 30 years. 3