Section 30.903 - Cost Estimation for Closure(1) (Effective on and after July 1, 1988) The owner or operator shall, within the applicable time period prescribed in 310 CMR 30.901, prepare and submit to the Department a written estimate, in current dollars, of the cost of closing the facility pursuant to 310 CMR 30.580. This cost estimate shall equal the cost of closure at the point in the facility's operating life when the extent and manner of its operation would make closure the most expensive, as indicated by the closure plan. This cost estimate shall be certified by an independent Massachusetts registered professional engineer.(2) The preparation of a current closure cost estimate shall be subject to the following provisions: (a) To the extent that quantities of different hazardous wastes being stored or treated at the facility vary over the operating life of the facility, the owner or operator shall base the current closure cost estimate upon the cost of removing the maximum inventory of each hazardous waste that may occur during the operating life of the facility, regardless of whether a maximum inventory occurs simultaneously with any other maximum inventory or with the point in the facility's operating life when the extent and manner of its operations would make closure most expensive; and(b) The current closure cost estimate may show at a cost no lower than zero those hazardous wastes for which the owner or operator persuades the Department that there is not a cost of alternate disposal of such hazardous wastes, that such hazardous wastes have a current economic value, and that such economic value will continue over the remaining operating life of the facility.(3) Within 30 days after each anniversary of the date on which the first current closure cost estimate was prepared, the owner or operator shall prepare and submit to the Department an adjustment for inflation of the current closure cost estimate. The adjustment shall be made as specified in 310 CMR 30.903, using an inflation factor derived from the annual implicit Price Deflator for Gross Domestic Product as established by the U.S. Department of Commerce in its Survey of Current Business. The inflation factor shall be calculated by dividing the latest published annual Deflator by the Deflator for the previous year. (a) The first adjustment shall be made by multiplying the current closure cost estimate by the inflation factor. The result shall be the adjusted current closure cost estimate.(b) Subsequent adjustments shall be made by multiplying the latest adjusted closure cost by the inflation factor.(4) The owner or operator shall revise the current closure cost estimate whenever a change in the closure plan increases the cost of closure. The revised current closure cost estimate shall be adjusted for inflation as specified in 310 CMR 30.903(3). The Department may authorize or require the use of an adjusted inflation factor if the Department determines that the inflation factor calculated pursuant to 310 CMR 30.903(3) does not accurately reflect change in the cost of closing the facility.(5) During the operating life of the facility, the owner or operator shall keep in the facility's records all closure cost estimates prepared pursuant to 310 CMR 30.903.