Mass balance Clause Samples

Mass balance. A mass balance for mine water and total inorganic nitrogen was developed for the purpose of evaluating SMC’s current water management practices, and to aide in the determination of means to minimize or eliminate nitrogen discharges to groundwater and ultimately the East Boulder River. Mass balances show the total inputs and outputs of water and nitrogen from the mine and can be used as part of an examination of various means to optimize and prioritize performance of the water management system at the East Boulder Mine. Together with experience and logic, the mass balance can be useful as a tool to the engineer and operator in determining how to best operate a system to achieve a goal – in this case to minimize or eliminate discharges of nitrogen. Five scenarios have been developed for the purpose of first assessing SMC’s current operation of water management facilities; and second for the purpose of assessing prioritization and optimization of water management facilities under current and foreseeable future conditions. Scenarios depicted in the mass balance worksheets (Cases 1 – 5) were altered to affect minimization or elimination of water and nitrogen discharges as described in the following sections. This is intended to determine how to best operate or modify the design of the water management facilities at the East Boulder Mine under various conditions to achieve the goals of the GNA. The following sections describe those conditions and the results from the mass balance scenarios. 2.2.1 Case 1 – Original design conditions from 1992 EIS Using information provided by SMC, the flowsheet (Figure 1) described above was used to calculate a mass balance for mine water and total nitrogen at the East Boulder Mine as shown in Table 1. This scenario represents the original design conditions discussed in the 1992 EIS for the East Boulder Mine, which are based on conditions observed at the Stillwater Mine. Adit water is discharged to the surge pond (1), then the clarifier, at an average rate of 737 gallons per minute (gpm) and a concentration of 12.9 milligrams per liter (mg/L) total inorganic nitrogen resulting in an average load of 114.3 pounds per day (lb/d). The mine adit water flows into a surge pond and then into the clarifier (1). Volumes of the surge pond and clarifier are assumed to be steady state (i.e. mass in equals mass out). Clarified mine water then flows to the biological treatment plant to reduce the amount of nitrate nitrogen through an anoxic bio...