Any state which enacts the Central Midwest Interstate Low-Level Radioactive Waste Compact and has as its resident a generator shall be liable for the cost of post-closure care in excess of funds available from the Low-Level Radioactive Waste Facility Closure, Post-Closure Care and Compensation Fund or from any liability insurance or other means of establishing financial responsibility in an amount sufficient to provide for any necessary corrective actions or liabilities arising during the period of post-closure care. The extent of such liability shall not be in excess of the prorated share of the volume of waste placed in the facility by the generators of each state which has enacted the Central Midwest Interstate Low-Level Radioactive Waste Compact. However, this Section shall not apply to a party state with a total volume of waste recorded on low-level radioactive waste manifests for any year that is less than 10 percent of the total volume recorded on such manifests for the region during the same year.