We accrue for the estimated closure costs as determined pursuant to Resource Conservation and Recovery Act ("RCRA") guidelines for all fixed-based regulated facilities, even though we do not intend to or have present plans to close any of our existing facilities. The permits and/or licenses define the waste, which may be received at the facility in question, and the treatment or process used to handle and/or store the waste. In addition, the permits and/or licenses specify, in detail, the process and steps that a hazardous waste or mixed waste facility must follow should the facility be closed or cease operating as a hazardous waste or mixed waste facility. Closure procedures and cost calculations in connection with closure of a facility are based on guidelines developed by the federal and/or state regulatory authorities under RCRA and the other appropriate statutes or regulations promulgated pursuant to the statutes. The closure procedures are very specific to the waste accepted and processes used at each facility. We recognize the closure cost as a liability on the balance sheet. Since all our facilities are acquired facilities, the closure cost for each facility was recognized pursuant to a business combination and recorded as part of the purchase price allocation of fair value to identifiable assets acquired and liabilities assumed. The closure calculation is increased annually for inflation based on RCRA guidelines, and for any approved changes or expansions to the facility, which may result in either an increase or decrease in the approved closure amount.

The adjustment to the obligation in 2011 was due to a change in the the estimated closure for our PFNWR facility. The decrease in closure accrual in 2012 included approximately $773,000 of costs incurred in connection with the closure of a processing unit at our PFNWR facility.