interest expense related to capital lease obligations was $ 1.7 million during both the years ended december 31 , 2013 and 2012 , and $ 1.5 million during the year ended december 31 , 2011 . purchase commitments in the table below , we set forth our enforceable and legally binding purchase obligations as of december 31 , 2013 . some of the amounts included in the table are based on management 2019s estimates and assumptions about these obligations , including their duration , the possibility of renewal , anticipated actions by third parties , and other factors . because these estimates and assumptions are necessarily subjective , our actual payments may vary from those reflected in the table . purchase orders made in the ordinary course of business are excluded from the table below . any amounts for which we are liable under purchase orders are reflected on the consolidated balance sheets as accounts payable and accrued liabilities . these obligations relate to various purchase agreements for items such as minimum amounts of fiber and energy purchases over periods ranging from one to 15 years . total purchase commitments are as follows ( dollars in thousands ) : .
what percentage of total purchase commitments are due after 2018?
the company purchased a total of $ 61.7 million , $ 27.7 million , and $ 28.5 million during the years ended december 31 , 2013 , 2012 , and 2011 , respectively , under these purchase agreements . the increase in purchase commitments in 2014 , compared with 2013 , relates to the acquisition of boise in fourth quarter 2013 . environmental liabilities the potential costs for various environmental matters are uncertain due to such factors as the unknown magnitude of possible cleanup costs , the complexity and evolving nature of governmental laws and regulations and their interpretations , and the timing , varying costs and effectiveness of alternative cleanup technologies . from 1994 through 2013 , remediation costs at the company 2019s mills and corrugated plants totaled approximately $ 3.2 million . at december 31 , 2013 , the company had $ 34.1 million of environmental-related reserves recorded on its consolidated balance sheet . of the $ 34.1 million , approximately $ 26.5 million related to environmental- related asset retirement obligations discussed in note 14 , asset retirement obligations , and $ 7.6 million related to our estimate of other environmental contingencies . the company recorded $ 7.8 million in 201caccrued liabilities 201d and $ 26.3 million in 201cother long-term liabilities 201d on the consolidated balance sheet . liabilities recorded for environmental contingencies are estimates of the probable costs based upon available information and assumptions . because of these uncertainties , pca 2019s estimates may change . as of the date of this filing , the company believes that it is not reasonably possible that future environmental expenditures for remediation costs and asset retirement obligations above the $ 34.1 million accrued as of december 31 , 2013 , will have a material impact on its financial condition , results of operations , or cash flows . guarantees and indemnifications we provide guarantees , indemnifications , and other assurances to third parties in the normal course of our business . these include tort indemnifications , environmental assurances , and representations and warranties in commercial agreements . at december 31 , 2013 , we are not aware of any material liabilities arising from any guarantee , indemnification , or financial assurance we have provided . if we determined such a liability was probable and subject to reasonable determination , we would accrue for it at that time. .