2011 Issue

24 was divided into north and south areas. In the southern area, two extraction wells, R1 and R2, began pumping approximately 500 gallons per minute to granular activated carbon treatment systems. Effluent fromthe treatment system is used for secondary irrigation in Spanish Fork. Three extraction wells R3, Orton No. 23 a private irrigationwell and theMapletonNo. 1, a public water supply well in the northern portion, began pumping approxi- mately 2100 gallons per minute to the treatment system. Both Mapleton No. 1 and Orton No. 23 wells are treated by separate granular activated carbon treatment systems. Effluent is used for secondary irrigation in Mapleton. Effluent from treatment systems are returned to surface streams during thenon-irrigation season. Effluent quality from treatment systems showed results below the limit of detection for explosive constituents. Nitrate concentration in effluent is well below the current drinking water standard of ten milligrams per liter. At the plant site, contaminated soils were removed for an off- site disposal or burned when removal was deemed infeasible. Structures at the sitewere demolished, disassembledor burned. The mitigation at the site is near completion and awaiting final closure status. Since the early nineties, Ensign Bickford has built necessary infrastructure of pump and treatment systems at a cost of six million dollars, and operated treatment systems to this date. The company has continued to fund operational costs through 2022. The dollar amount required for financial assurance is reviewed yearly, and adjusted based on earlier performance data and costs. Figure 4 shows the summary of financial commitment for the pump and treatment systems. Financial responsibility may be assured through a letter of credit, which typically costs one to eight percent of the total amount subject to financial standing of the beneficiary, or other mutually agreeable escrow arrange- ments. The fundamental formulas for determiningpresent worth [P] of financial responsibility or assurance required is a summation of series of equal annual paymentsA 0 depositedat thebeginning of the period to cover an outlay required at the endof the period, over a period n years with an inflation rate, a percent per year and interest rate, i per cent per year as shown in Formula 1. Any escalation or reduction of payments over different timeframes for the entire duration of remediation requires the formula to be modified. Let us consider, for example, a remediation strategy for three periods with three different series of uniformpayments. Then the modified formula is as shown in Formula 2. For example, the financial responsibility for a project, with an operating life of 20 years, annual cost of $660,000 (A x ) for the first three years (t x ), $570,000 (A y ) for the next seven years (t y ), and $500,000 (A z ) for the remainder of ten years (t z ), and four and three percent per year discount and inflation rate, amounts to $9.5 million. This amount may be placed in reserve or assured through a letter of credit. This is illustrated in Figure 4. Currently, all monitoring wells are reporting downward trends in RDXandnitrate concentrations. Concentrations of RDXoriginally Figure 2. RDX and Nitrate Plumes Figure 3. Extraction Wells and Treatment Systems