21. Commitments and Contingencies

Leases

The Company is obligated under certain operating leases and rental agreements for railroad cars, office space, and other equipment. Certain lease agreements contain escalation clauses and are accounted for on a straight-line basis over the lease term. Future minimum annual commitments under such operating leases at December 31, 2017 are as follows:

Twelve months ending December 31,
2018	$	14,891
2019		11,254
2020		7,569
2021		5,827
2022		2,614
Thereafter		15,582

Expense related to operating leases and rental agreements was $10,239, $7,065 and $4,098 for the years ended December 31, 2017, 2016 and 2015, respectively. Lease expense related to railcars are included in cost of goods sold in the consolidated statement of operations.

Litigation

The Company is periodically involved in litigation and claims incidental to its operation. Other than the below, management believes that any pending litigation will not have a material impact the Company’s financial position.

In August 2016, an affiliate of one of the Company’s customers, in conjunction with bankruptcy proceedings, demanded a refund of the remaining balance of prepayments it claimed to have made pursuant to the agreement with the Company’s customer. In November 2016, this was settled favorably for the Company; accordingly, the full amount of the prepayment was recognized as revenue. As part of this settlement, the Company was granted an unsecured bankruptcy claim of approximately $12 million; in December 2016, a third party purchased the Company’s unsecured claim for approximately $6.6 million which was recognized in other income in the fourth quarter.

Capital Requirements

As of December 31, 2017, the Company has commitments related to its Oakdale facility as well as future expansion projects of approximately $35,100.

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 agreement continues for two years after the closing of one or more of the identified real properties. The third party’s compensation consists of $10 per month through the end of the agreement, reimbursement of expenses, and $1 per each acre purchased as a closing fee. In 2017, 2016 and 2015, the Company paid the third party $19, $0 and $841, respectively, in consulting fees, expense reimbursements and closing costs.

These closing costs have been capitalized in property and equipment in the accompanying consolidated balance sheets as they relate to the acquisition of land.

In addition to the aforementioned fees, the consulting agreement provides for tonnage fees based upon mining operations. The payment of $0.50 per sold ton of certain grades of sand that were mined and sold from the properties acquired under the consulting agreement begins with the second year of operations of the plant and continues indefinitely. The minimum annual tonnage fee is $200 per contract year, which runs from August 1 to July 31. During the years ended December 31, 2017, 2016 and 2015, the Company incurred $530, $258 and $252, respectively, related to tonnage fees.

Bonds

The Company entered into performance bonds with Jackson County, Wisconsin and Monroe County, Wisconsin for $4,400 and $900, respectively. The Company provided these performance bonds 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 December 31, 2017 and 2016, $487 and $971, respectively, of cash is being held as collateral related to the bond and is presented as restricted cash on the consolidated balance sheet.