Commitments and Contingencies Future Minimum Commitments The Company is obligated under certain operating leases, minimum royalty payments for our leased properties in West Texas, and rental agreements for railcars, office space, and other equipment. Future minimum annual commitments under such operating leases at September 30, 2018 are as follows: Twelve Month Period Ending September 30, 2019 $ 17,382 2020 11,818 2021 9,937 2022 6,447 2023 4,430 Thereafter 36,075 Total $ 86,089 Expense related to operating leases and rental agreements was $3,965 and $2,677 for three months ended September 30, 2018 and 2017 , respectively. Expense related to operating leases and rental agreements was $10,658 and $6,744 for the nine months ended September 30, 2018 and 2017 , respectively. Lease expense related to railcars is included in cost of goods sold in the condensed consolidated income statements. Litigation The Company is periodically involved in litigation and claims incidental to its operation. Management believes that any pending litigation will not have a material impact to the Companys financial position. Required Capital As of September 30, 2018 , the Company has commitments related to its Oakdale facility, wellsite storage solutions systems and other expansion projects of approximately $23,000 . Consulting Agreements On August 1, 2010, the Company entered into a consulting agreement related to the purchase of land with a third party. The third party acted as an agent for the Company to obtain options to purchase certain identified real property in Wisconsin, as well as obtain permits and approvals necessary to open, construct and operate a sand mining and processing facility on such real property. The third partys compensation, which continues indefinitely, consists of reimbursement of certain expenses and $1,000 per each acre purchased as a closing fee. For the three months ended September 30, 2018 and 2017 , the Company incurred no closing costs and expense reimbursements. For the nine months ended September 30, 2018 and 2017 , the Company incurred $60 and $19 of closing costs and expense reimbursements, respectively. The closing costs have been capitalized in property and equipment in the accompanying consolidated balance sheets when they relate to the acquisition of land. In addition to the aforementioned fees, the third-party agreement provides for tonnage fees based upon mining operations. The payment of $0.50 per sold ton of certain grades of sand that have been mined and sold from the properties acquired under the consulting agreement continues indefinitely. The minimum annual tonnage fee is $200 per contract year, which runs from August 1 to July 31. During the three months ended September 30, 2018 and 2017 , the Company incurred $225 and $133 related to tonnage fees, respectively. During the nine months ended September 30, 2018 and 2017 , the Company incurred $593 and $362 related to tonnage fees, respectively. These costs are presented as operating expenses in the condensed consolidated income statement. Bonds The Company entered into a performance bond with Jackson County, Wisconsin and Monroe County, Wisconsin for $4,400 and $900 , respectively. The Company provided a performance bond to assure performance under the reclamation plan filed with each respective county. The Company entered into permit bonds amounting to $1,350 with certain towns and counties in which it operates to use designated town and county roadways. The Company provided these permit bonds to assure maintenance and restoration of the roadways. The Company has an outstanding $1,943 bond to assure performance under its agreement with a pipeline common carrier. As of September 30, 2018 and December 31, 2017 , $0 and $487 , respectively, of cash is being held as collateral related to the bond and is presented as restricted cash on the consolidated balance sheets. As of April 13, 2018, the Company no longer had any restrictions on cash.