properties resulted in a reduction in revenue of $383,000 and $726,000 for the three and six months ended June 30, 2021, and a reduction in revenue of $86,000 and $156,000 for the three and six months ended June 30, 2020, respectively .

Tenant reimbursements, which are included in revenues from rental properties and which consist of real estate taxes and other municipal charges paid by us and reimbursable by our tenants pursuant to the terms of triple-net lease agreements, were $4,280,000 and $8,036,000 for the three and six months ended June 30, 2021, respectively, and $4,638,000 and $7,964,000 for the three and six months ended June 30, 2020, respectively .

The components of the $74,895,000 investment in direct financing leases as of June 30, 2021, are lease payments receivable of $106,612,000 plus unguaranteed estimated residual value of $13,928,000 less unearned income of $44,727,000 and $918,000 allowance for credit losses. The components of the $77,238,000 investment in direct financing leases as of December 31, 2020, are lease payments receivable of $113,256,000 plus unguaranteed estimated residual value of $13,928,000 less unearned income of $49,028,000 and $918,000 allowance for credit losses. Of the $918,000 aggregate credit loss reserve related to these direct financing leases, $578,000 was recognized as a cumulative adjustment to retained earnings and as a reduction of the investment in direct financing leases balance on our consolidated balance sheets on January 1, 2020.

As Lessee

For leases in which we are the lessee, ASU 2016-02 requires leases with durations greater than twelve months to be recognized on our consolidated balance sheets. We elected the package of transition provisions available for expired or existing contracts, which allowed us to carryforward our historical assessments of (i) whether contracts are or contain leases, (ii) lease classification and (iii) initial direct costs.

As of January 1, 2019, we recognized operating lease right-of-use assets of $25,561,000 (net of deferred rent expense) and operating lease liabilities of $26,087,000, which were presented on our consolidated financial statements. The right-of-use assets and lease liabilities are carried at the present value of the remaining expected future lease payments. When available, we use the rate implicit in the lease to discount lease payments to present value; however, our current leases did not provide a readily determinable implicit rate. Therefore, we estimated our incremental borrowing rate to discount the lease payments based on information available and considered factors such as interest rates available to us on a fully collateralized basis and terms of the leases. ASU 2016-02 did not have a material impact on our consolidated balance sheets or on our consolidated statements of operations. The most significant impact was the recognition of right-of-use assets and lease liabilities for operating leases, while our accounting for finance leases remained substantially unchanged.

Major Tenants

As of June 30, 2021, we had four significant tenants by revenue:

Getty Petroleum Marketing Inc.

Getty Petroleum Marketing Inc. (“Marketing”) was our largest tenant from 1997 until 2012 under a unitary triple-net master lease that was terminated in April 2012 as a consequence of Marketing’s bankruptcy, at which time we either sold or re-leased these properties. As of June 30, 2021, 348 of the properties we own or lease were previously leased to Marketing, of which 315 properties are subject to long-term triple-net leases with petroleum distributors across 14 separate portfolios and 26 properties are leased as single unit triple-net leases. The portfolio leases covering properties previously leased to Marketing are unitary triple-net lease agreements generally with an initial term of 15 years and options for successive renewal terms of up to 20 years. Rent is scheduled to increase at varying intervals during both the initial and renewal terms of these leases. Several of the leases provide for additional rent based on the aggregate volume of fuel sold. In addition, the majority of the portfolio leases require the tenants to invest capital in our properties, substantially all of which is related to the replacement of USTs that are owned by our tenants. As of June 30, 2021, we have a remaining commitment to fund up to $6,712,000 in the aggregate with our tenants for our portion of such capital improvements. Our commitment provides us with the option to either reimburse our tenants or to offset rent when these capital expenditures are made. This deferred expense is recognized on a straight-line basis as a reduction of rental revenue in our consolidated statements of operations over the life of the various leases.

As part of the triple-net leases for properties previously leased to Marketing, we transferred title of the USTs to our tenants, and the obligation to pay for the retirement and decommissioning or removal of USTs at the end of their useful lives, or earlier if circumstances warranted, was fully or partially transferred to our new tenants. We remain contingently liable for this obligation in the event that our tenants do not satisfy their responsibilities. Accordingly, through June 30, 2021, we removed $13,813,000 of asset retirement obligations and $10,808,000 of net asset retirement costs related to USTs from our balance sheet. The cumulative change of $1,211,000 (net of accumulated amortization of $1,794,000) is recorded as deferred rental revenue and will be recognized on a straight-line basis as additional revenues from rental properties over the terms of the various leases.

purposes of allocating the costs to complete the RI/FS among its members, with the understanding that this interim allocation formula is not binding on the parties in terms of any potential liability for the costs to remediate the LPRSA. The CPG submitted to the EPA its draft RI/FS in 2015, which sets forth various alternatives for remediating the entire 17 miles of the LPRSA. In October 2018, the EPA issued a letter directing the CPG to prepare a streamlined feasibility study for just the upper 9-miles of the LPRSA based on an iterative approach using adaptive management strategies. On December 4, 2020, The CPG submitted a Final Draft Interim Remedy Feasibility Study (“IR/FS”) to the EPA which identifies various targeted dredge and cap alternatives for the upper 9-miles of the LPRSA. On December 11, 2020, EPA conditionally approved the CPG’s IR/FS for the upper 9-miles of the LPRSA, which recognizes that interim actions and adaptive management may be appropriate before deciding a final remedy.  It is anticipated that EPA will issue a proposed plan for an interim remedy for the upper 9-miles, which will be published for public comment.  Subject to EPA’s response to any comments and/or objections received, it is anticipated that EPA will issue a Record of Decision (“ROD”) for an interim remedy for the upper 9-mile portion of the LPRSA in 2021 (“Upper 9-mile IR ROD”).  

In addition to the RI/FS activities, other actions relating to the investigation and/or remediation of the LPRSA have proceeded as follows. First, in June 2012, certain members of the CPG entered into an Administrative Settlement Agreement and Order on Consent (“10.9 AOC”) with the EPA to perform certain remediation activities, including removal and capping of sediments at the river mile 10.9 area and certain testing. The EPA also issued a Unilateral Order to Occidental Chemical Corporation (“Occidental”), the former owner/operator of the Diamond Shamrock Corporation facility responsible for the discharge of 2,3,8,8-TCDD (“dioxin”) and other hazardous substances from the Lister facility.  The Order directed Occidental to participate and contribute to the cost of the river mile 10.9 work. Concurrent with the CPG’s work on the RI/FS, on April 11, 2014, the EPA issued a draft Focused Feasibility Study (“FFS”) with proposed remedial alternatives to remediate the lower 8-miles of the LPRSA. The FFS was subject to public comments and objections and, on March 4, 2016, the EPA issued a ROD for the lower 8-miles (“Lower 8-mile ROD”) selecting a remedy that involves bank-to-bank dredging and installing an engineered cap with an estimated cost of $1,380,000,000. On March 31, 2016, we and more than 100 other PRPs received from the EPA a “Notice of Potential Liability and Commencement of Negotiations for Remedial Design” (“Notice”), which informed the recipients that the EPA intends to seek an Administrative Order on Consent and Settlement Agreement with Occidental (who the EPA considers the primary contributor of dioxin and other pesticides  generated from the production of Agent Orange at its Diamond Shamrock Corporation facility and a discharger of other contaminants of concern (“COCs”) to the Superfund Site for remedial design of the remedy selected in the Lower 8-mile ROD, after which the EPA plans to begin negotiations with “major” PRPs for implementation and/or payment of the selected remedy. The Notice also stated that the EPA believes that some of the PRPs and other parties not yet identified will be eligible for a cash out settlement with the EPA. On September 30, 2016, Occidental entered into an agreement with the EPA to perform the remedial design for the Lower 8-mile ROD. In December 2019, Occidental submitted a report to the EPA on the progress of the remedial design work, which is still ongoing.

Occidental has asserted that it is entitled to indemnification by Maxus Energy Corporation (“Maxus”) and Tierra Solutions, Inc. (“Tierra”) for its liability in connection with the Site. Occidental has also asserted that Maxus and Tierra’s parent company, YPF, S.A. (“YPF”) and certain of its affiliates must indemnify Occidental. On June 16, 2016, Maxus and Tierra filed for reorganization under Chapter 11 of the U.S. Bankruptcy Code. In July 2017, an amended Chapter 11 plan of liquidation became effective and, in connection therewith, Maxus and Tierra entered into a mutual contribution release agreement with certain parties, including us, pertaining to certain past costs, but not future remedy costs.

By letter dated March 30, 2017, the EPA advised the recipients of the Notice that it would be entering into cash out settlements with 20 PRPs to resolve their alleged liability for the remedial actions addressed in the Lower 8-mile ROD, who the EPA stated did not discharge any of the eight hazardous substances identified as a COC in the ROD. The letter also stated that other parties who did not discharge dioxins, furans or polychlorinated biphenyls (which are considered the COCs posing the greatest risk to the river) may also be eligible for cash out settlements, and that the EPA would begin a process for identifying other PRPs for negotiation of similar cash out settlements. We were not included in the initial group of 20 parties identified by the EPA for cash out settlements, but we believe we meet EPA’s criteria for a cash out settlement and should be considered for same in any future discussions. In January 2018, the EPA published a notice of its intent to enter into a final settlement agreement with 15 of the initial group of parties to resolve their respective alleged liability for the Lower 8-mile ROD work, each for a payment to the EPA in the amount of $280,600. In August 2017, the EPA appointed an independent third-party allocation expert to conduct allocation proceedings with most of the remaining recipients of the Notice, which is anticipated to lead to additional offers of cash out settlements to certain additional parties and/or a consent decree in which parties that are not offered a cash out settlement will agree to perform the Lower 8-mile ROD remedial action. The allocation proceedings, which we are participating in, are still ongoing.

On June 30, 2018, Occidental filed a complaint in the United States District Court for the District of New Jersey seeking cost recovery and contribution under the Comprehensive Environmental Response, Compensation, and Liability Act for its alleged expenses with respect to the investigation, design, and anticipated implementation of the remedy for the Lower 8-mile ROD work. The complaint lists over 120 defendants, including us, many of whom were also named in the EPA’s 2016 Notice. Factual discovery is ongoing, and we are defending the claims consistent with our defenses in the related proceedings.

Many uncertainties remain regarding the anticipated interim remedy selection for the Upper 9-mile IR ROD and how the EPA intends to implement either the Upper 9-mile IR ROD and/or the Lower 8-mile ROD work, including whether EPA will designate

certain PRPs as work parties and/or if EPA will identify PRPs for future cash-out settlement negotiations for the Upper 9-mile IR ROD, the Lower 8-mile ROD work or both.  Further, none of the above referenced AOCs and RODs relating to the LPRSA obligate us to fund or perform any remedial action contemplated for the LPRSA and do not resolve liability issues for remedial work or the restoration of or compensation for alleged natural resource damages to the LPRSA, which are not known at this time.  Therefore, we anticipate that performance of the EPA’s selected remedies for the LPRSA will be subject to future negotiation, potential enforcement proceedings and/or possible litigation.  

Based on currently known facts and circumstances, including, among other factors, anticipated allocations, our belief that there was not any use or discharge of dioxins, furans or polychlorinated biphenyls in connection with our former petroleum storage operations at our former Newark, New Jersey Terminal, and because there are numerous other parties who will likely bear the costs of remediation and/or damages, the Company does not believe that resolution of this matter as relates to the Company is reasonably likely to have a material impact on our results of operations. Nevertheless, our ultimate liability in the pending and possible future proceedings pertaining to the LPRSA remains uncertain and subject to numerous contingencies which cannot be predicted and the outcome of which are not yet known. Therefore, it is possible that our ultimate liability resulting from this matter and the impact on our results of operations could be material.

   MTBE Litigation – State of Pennsylvania

On July 7, 2014, our subsidiary, Getty Properties Corp., was served with a complaint filed by the Commonwealth of Pennsylvania (the “State”) in the Court of Common Pleas, Philadelphia County relating to alleged statewide MTBE contamination in Pennsylvania. The named plaintiffs are the State, by and through (then) Pennsylvania Attorney General Kathleen G. Kane (as Trustee of the waters of the State), the Pennsylvania Insurance Department (which governs and administers the Underground Storage Tank Indemnification Fund), the Pennsylvania Department of Environmental Protection (vested with the authority to protect the environment) and the Pennsylvania Underground Storage Tank Indemnification Fund. The complaint names us and more than 50 other petroleum refiners, manufacturers, distributors and retailers of MTBE or gasoline containing MTBE who are alleged to have distributed, stored and sold MTBE gasoline in Pennsylvania. The complaint seeks compensation for natural resource damages and for injuries sustained as a result of “defendants’ unfair and deceptive trade practices and acts in the marketing of MTBE and gasoline containing MTBE.” The plaintiffs also seek to recover costs paid or incurred by the State to detect, treat and remediate MTBE from public and private water wells and groundwater. The plaintiffs assert causes of action against all defendants based on multiple theories, including strict liability – defective design; strict liability – failure to warn; public nuisance; negligence; trespass; and violation of consumer protection law.

The case was filed in the Court of Common Pleas, Philadelphia County, but was removed by defendants to the United States District Court for the Eastern District of Pennsylvania and then transferred to the United States District Court for the Southern District of New York so that it may be managed as part of the ongoing MTBE MDL proceedings. In November 2015, plaintiffs filed a second amended complaint naming additional defendants and adding factual allegations intended to bolster their claims against the defendants. We have joined with other defendants in the filing of a motion to dismiss the claims against us. This motion is pending with the Court. We intend to defend vigorously the claims made against us. Our ultimate liability, if any, in this proceeding is uncertain and subject to numerous contingencies which cannot be predicted and the outcome of which are not yet known.

MTBE Litigation – State of Maryland

On December 17, 2017, the State of Maryland, by and through the Attorney General on behalf of the Maryland Department of Environment and the Maryland Department of Health (the “State of Maryland”), filed a complaint in the Circuit Court for Baltimore City related to alleged statewide MTBE contamination in Maryland. The complaint was served upon us on January 19, 2018. The complaint names us and more than 60 other defendants, including petroleum refiners, manufacturers, distributors and retailers of MTBE or gasoline containing MTBE. The complaint seeks compensation for natural resource damages and for injuries sustained as a result of the defendants’ unfair and deceptive trade practices in the marketing of MTBE and gasoline containing MTBE. The plaintiffs also seek to recover costs paid or incurred by the State of Maryland to detect, investigate, treat and remediate MTBE from public and private water wells and groundwater, punitive damages and the award of attorneys’ fees and litigation costs. The plaintiffs assert causes of action against all defendants based on multiple theories, including strict liability – defective design; strict liability – failure to warn; strict liability for abnormally dangerous activity; public nuisance; negligence; trespass; and violations of Titles 4, 7 and 9 of the Maryland Environmental Code.

On February 14, 2018, defendants removed the case to the United States District Court for the District of Maryland. It is unclear whether the matter will ultimately be removed to the MTBE MDL proceedings or remain in federal court in Maryland. We intend to defend vigorously the claims made against us. Our ultimate liability, if any, in this proceeding is uncertain and subject to numerous contingencies which cannot be predicted and the outcome of which are not yet known.

Uniondale, New York Litigation

In September 2004, the State of New York commenced an action against us, United Gas Corp., Costa Gas Station, Inc., Vincent Costa, Sharon Irni, The Ingraham Bedell Corporation, Richard Berger and Exxon Mobil in New York Supreme Court in Albany County seeking recovery for reimbursement of investigation and remediation costs claimed to have been incurred by the New York Environmental Protection and Spill Compensation Fund relating to contamination it alleges emanated from various gasoline station properties located in the same vicinity in Uniondale, New York, including a site formerly owned by us and at which a petroleum release and cleanup occurred. The complaint also seeks future costs for remediation, as well as interest and penalties. We served an answer to the complaint denying responsibility. In 2007, the State of New York commenced action against Shell, Motiva, and related parties, in the New York Supreme Court, Albany County seeking basically the same relief sought in the action involving us. We also filed a third-party complaint against Hess, Sprague Operating Resources LLC (successor to RAD Energy Corp.), Service Station Installation of NY, Inc., and certain individual defendants based on alleged contribution to the contamination that is the subject of the State’s claims arising from a petroleum discharge at a gasoline station up-gradient from the site formerly owned by us. In 2016, the various actions filed by the State of New York and our third-party actions were consolidated for discovery proceedings and trial. We have entered into a settlement agreement with the State of New York and the other parties to this lawsuit, which includes mutual releases. This settlement is in the process of being funded by the defendants, following which a stipulation of discontinuance will be filed and the lawsuit will be dismissed. Our settlement contribution is consistent with the amount we accrued for this lawsuit as of June 30, 2021. Although we believe that this case will be resolved as contemplated by the settlement agreement, until funding is fully made and the stipulation of discontinuance is filed, this case cannot be considered fully resolved.

The Restated Credit Agreement incurs interest and fees at various rates based on our total indebtedness to total asset value ratio at the end of each quarterly reporting period. The Revolving Facility permits borrowings at an interest rate equal to the sum of a base rate plus a margin of 0.50% to 1.30% or a LIBOR rate plus a margin of 1.50% to 2.30%. The annual commitment fee on the undrawn funds under the Revolving Facility is 0.15% to 0.25%. The Term Loan prior to its repayment pursuant to a subsequent amendment to the Restated Credit Agreement bore interest at a rate equal to the sum of a base rate plus a margin of 0.45% to 1.25% or a LIBOR rate plus a margin of 1.45% to 2.25%.

On September 19, 2018, we entered into an amendment (the “First Amendment”) of our Restated Credit Agreement. The First Amendment modifies the Restated Credit Agreement to, among other things: (i) reflect that we had previously entered into (a) an amended and restated note purchase and guarantee agreement with The Prudential Insurance Company of America (“Prudential”) and certain of its affiliates and (b) a note purchase and guarantee agreement with the Metropolitan Life Insurance Company (“MetLife”) and certain of its affiliates; and (ii) permit borrowings under each of the Revolving Facility and the Term Loan at three different interest rates, including a rate based on the LIBOR Daily Floating Rate (as defined in the First Amendment) plus the Applicable Rate (as defined in the First Amendment) for such facility.

On September 12, 2019, in connection with prepayment of the Term Loan, we entered into a consent and amendment (the “Second Amendment”) of our Restated Credit Agreement. The Second Amendment modifies the Restated Credit Agreement to, among other things, (a) increase our borrowing capacity under the Revolving Facility from $250,000,000 to $300,000,000 and (b) decrease lender commitments under the Term Loan to $0.

On December 14, 2020, we used a portion of the net proceeds from the Series I Notes, Series J Notes and Series K Notes (each as described below) to repay $75,000,000 of borrowings outstanding under our Restated Credit Agreement.

Senior Unsecured Notes

On December 4, 2020, we entered into a fifth amended and restated note purchase and guarantee agreement (the “Fifth Amended and Restated Prudential Agreement”) with Prudential and certain of its affiliates amending and restating our existing fourth amended and restated note purchase agreement. Pursuant to the Fifth Amended and Restated Prudential Agreement, we agreed that our (a) 6.0% Series A Guaranteed Senior Notes due February 25, 2021, in the original aggregate principal amount of $100,000,000 (the “Series A Notes”), (b) 5.35% Series B Guaranteed Senior Notes due June 2, 2023, in the original aggregate principal amount of $75,000,000 (the “Series B Notes”), (c) 4.75% Series C Guaranteed Senior Notes due February 25, 2025, in the aggregate principal amount of $50,000,000 (the “Series C Notes”) and (d) 5.47% Series D Guaranteed Senior Notes due June 21, 2028, in the aggregate principal amount of $50,000,000 (the “Series D Notes”) and (e) 3.52% Series F Guaranteed Senior Notes due September 12, 2029, in the aggregate principal amount of $50,000,000 (the “Series F Notes”) that were outstanding under the existing fourth restated prudential note purchase agreement would continue to remain outstanding under the Fifth Amended and Restated Prudential Agreement and we authorized and issued our 3.43% Series I Guaranteed Senior Notes due November 25, 2030, in the aggregate principal amount of $100,000,000 (the “Series I Notes” and, together with the Series A Notes, Series B Notes, Series C Notes, Series D Notes and Series F Notes, the “Notes”). On December 4, 2020, we completed the early redemption of our 6.0% Series A Notes due February 25, 2021, in the original aggregate principal amount of $100,000,000. As a result of the early redemption, we recognized a $1,233,000 loss on extinguishment of debt on our consolidated statement of operations for the year ended December 31, 2020. The Fifth Amended and Restated Prudential Agreement does not provide for scheduled reductions in the principal balance of the Series I Notes, or any of our previously issued Series B Notes, Series C Notes, Series D Notes, or Series F Notes prior to their respective maturities.

On June 21, 2018, we entered into a note purchase and guarantee agreement (the “MetLife Note Purchase Agreement”) with MetLife and certain of its affiliates. Pursuant to the MetLife Note Purchase Agreement, we authorized and issued our 5.47% Series E Guaranteed Senior Notes due June 21, 2028, in the aggregate principal amount of $50,000,000 (the “Series E Notes”). The MetLife Note Purchase Agreement does not provide for scheduled reductions in the principal balance of the Series E Notes prior to their maturity.

On December 4, 2020, we entered into a first amendment to note purchase and guarantee agreement (the “First Amended and Restated AIG Agreement”) with American General Life Insurance Company amending and restating our existing note purchase and guarantee agreement. Pursuant to the First Amended and Restated AIG Agreement, we agreed that our  3.52% Series G Guaranteed Senior Notes due September 12, 2029, in the aggregate principal amount of $50,000,000 (the “Series G Notes”) that were outstanding under the existing note purchase and guarantee agreement would continue to remain outstanding under the First Amended and Restated AIG Agreement and we authorized and issued our $50,000,000 of 3.43% Series J Guaranteed Senior Notes due November 25, 2030 (the “Series J Notes”) to AIG. The First Amended and Restated AIG Agreement does not provide for scheduled reductions in the principal balance of the Series J Notes or any of our previously issued Series G Notes prior to their respective maturities.

On December 4, 2020, we entered into a first amended and restated note purchase and guarantee agreement (the “First Amended and Restated MassMutual Agreement”) amending and restating our existing note purchase and guarantee agreement. Pursuant to the First Amended and Restated MassMutual Agreement, we agreed that our  3.52% Series H Guaranteed Senior Notes due September 12, 2029, in the aggregate principal amount of $25,000,000 (the “Series H Notes”) that were outstanding under the existing note purchase and guarantee agreement would continue to remain outstanding under the First Amended and Restated MassMutual Agreement and we authorized and issued our $25,000,000 of 3.43% Series K Guaranteed Senior Notes due November 25, 2030 (the “Series K Notes”) to MassMutual. The First Amended and Restated MassMutual Agreement does not provide for scheduled reductions in the principal balance of the Series K or any of our previously issued Series H Notes prior to their respective maturities.

We used the net proceeds from the issuance of the Series I Notes, Series J Notes and Series K Notes to prepay in full our Series A Notes due February 25, 2021, and repay $75,000,000 of borrowings outstanding under our Restated Credit Agreement.

The Notes, the Series E Notes, the Series G Notes, the Series H Notes, the Series I Notes, the Series J Notes and, the Series K Notes, respectively issued thereunder, are collectively referred to as the “senior unsecured notes.”

Covenants

The Restated Credit Agreement and our senior unsecured notes contain customary financial covenants such as leverage, coverage ratios and minimum tangible net worth, as well as limitations on restricted payments, which may limit our ability to incur additional debt or pay dividends. The Restated Credit Agreement and our senior unsecured notes also contain customary events of default, including cross defaults to each other, change of control and failure to maintain REIT status (provided that the senior unsecured notes require a mandatory offer to prepay the notes upon a change in control in lieu of a change of control event of default). Any event of default, if not cured or waived in a timely manner, would increase by 200 basis points (2.00%) the interest rate we pay under the Restated Credit Agreement and our senior unsecured notes, and could result in the acceleration of our indebtedness under the Restated Credit Agreement and our senior unsecured notes. We may be prohibited from drawing funds under the Revolving Facility if there is any event or condition that constitutes an event of default under the Restated Credit Agreement or that, with the giving of any notice, the passage of time, or both, would be an event of default under the Restated Credit Agreement.

As of June 30, 2021, we are in compliance with all of the material terms of the Restated Credit Agreement and our senior unsecured notes, including the various financial covenants described herein.

Debt Maturities

relevant factors including our tenants’ histories of paying for such obligations, our assessment of their financial capability, and their intent to pay for such obligations. However, there can be no assurance that our assessments are correct or that our tenants who have paid their obligations in the past will continue to do so. We may ultimately be responsible to pay for environmental liabilities as the property owner if our tenant fails to pay them.

The estimated future costs for known environmental remediation requirements are accrued when it is probable that a liability has been incurred and a reasonable estimate of fair value can be made. The accrued liability is the aggregate of our estimate of the fair value of cost for each component of the liability, net of estimated recoveries from state UST remediation funds considering estimated recovery rates developed from prior experience with the funds.

For substantially all of our triple-net leases, our tenants are contractually responsible for compliance with environmental laws and regulations, removal of USTs at the end of their lease term (the cost of which in certain cases is partially borne by us) and remediation of any environmental contamination that arises during the term of their tenancy. Under the terms of our leases covering properties previously leased to Marketing (substantially all of which commenced in 2012), we have agreed to be responsible for environmental contamination at the premises that was known at the time the lease commenced, and for environmental contamination which existed prior to commencement of the lease and is discovered (other than as a result of a voluntary site investigation) during the first 10 years of the lease term (or a shorter period for a minority of such leases). After expiration of such 10-year (or, in certain cases, shorter) period, responsibility for all newly discovered contamination, even if it relates to periods prior to commencement of the lease, is contractually allocated to our tenant. Our tenants at properties previously leased to Marketing are in all cases responsible for the cost of any remediation of contamination that results from their use and occupancy of our properties. Under substantially all of our other triple-net leases, responsibility for remediation of all environmental contamination discovered during the term of the lease (including known and unknown contamination that existed prior to commencement of the lease) is the responsibility of our tenant.

We anticipate that a majority of the USTs at properties previously leased to Marketing will be replaced over the next several years because these USTs are either at or near the end of their useful lives. For long-term, triple-net leases covering sites previously leased to Marketing, our tenants are responsible for the cost of removal and replacement of USTs and for remediation of contamination found during such UST removal and replacement, unless such contamination was found during the first 10 years of the lease term and also existed prior to commencement of the lease. In those cases, we are responsible for costs associated with the remediation of such preexisting contamination. We have also agreed to be responsible for environmental contamination that existed prior to the sale of certain properties assuming the contamination is discovered (other than as a result of a voluntary site investigation) during the first five years after the sale of the properties.

In the course of certain UST removals and replacements at properties previously leased to Marketing where we retained continuing responsibility for preexisting environmental obligations, previously unknown environmental contamination was and continues to be discovered. As a result, we have developed an estimate of fair value for the prospective future environmental liability resulting from preexisting unknown environmental contamination and have accrued for these estimated costs. These estimates are based primarily upon quantifiable trends which we believe allow us to make reasonable estimates of fair value for the future costs of environmental remediation resulting from the removal and replacement of USTs. Our accrual of the additional liability represents our estimate of the fair value of cost for each component of the liability, net of estimated recoveries from state UST remediation funds considering estimated recovery rates developed from prior experience with the funds. In arriving at our accrual, we analyzed the ages of USTs at properties where we would be responsible for preexisting contamination found within 10 years after commencement of a lease (for properties subject to long-term triple-net leases) or five years from a sale (for divested properties), and projected a cost to closure for preexisting unknown environmental contamination.

We measure our environmental remediation liabilities at fair value based on expected future net cash flows, adjusted for inflation (using a range of 2.0% to 2.75%), and then discount them to present value (using a range of 4.0% to 7.0%). We adjust our environmental remediation liabilities quarterly to reflect changes in projected expenditures, changes in present value due to the passage of time and reductions in estimated liabilities as a result of actual expenditures incurred during each quarter. As of June 30, 2021, we had accrued a total of $47,932,000 for our prospective environmental remediation obligations. This accrual consisted of (a) $11,920,000, which was our estimate of reasonably estimable environmental remediation liability, including obligations to remove USTs for which we are responsible, net of estimated recoveries and (b) $36,012,000 for future environmental liabilities related to preexisting unknown contamination. As of December 31, 2020, we had accrued a total of $48,084,000 for our prospective environmental remediation obligations. This accrual consisted of (a) $11,718,000, which was our estimate of reasonably estimable environmental remediation liability, including obligations to remove USTs for which we are responsible, net of estimated recoveries and (b) $36,366,000 for future environmental liabilities related to preexisting unknown contamination.

Environmental liabilities are accreted for the change in present value due to the passage of time and, accordingly, $863,000 and $922,000 of net accretion expense was recorded for the six months ended June 30, 2021 and 2020, respectively, which is included in environmental expenses. In addition, during the six months ended June 30, 2021 and 2020, we recorded credits to environmental expenses aggregating $1,039,000 and $1,228,000, respectively, where decreases in estimated remediation costs exceeded the depreciated carrying value of previously capitalized asset retirement costs. Environmental expenses also include project management

fees, legal fees and environmental litigation accruals. For the six months ended June 30, 2021 and 2020, changes in environmental estimates aggregating, $92,000 and $73,000, respectively, were related to properties that were previously disposed of by us.

During the six months ended June 30, 2021 and 2020, we increased the carrying values of certain of our properties by $1,211,000 and $1,441,000, respectively, due to changes in estimated environmental remediation costs. The recognition and subsequent changes in estimates in environmental liabilities and the increase or decrease in carrying values of the properties are non-cash transactions which do not appear on our consolidated statements of cash flows.

Capitalized asset retirement costs are being depreciated over the estimated remaining life of the UST, a 10-year period if the increase in carrying value is related to environmental remediation obligations or such shorter period if circumstances warrant, such as the remaining lease term for properties we lease from others. Depreciation and amortization expense related to capitalized asset retirement costs in our consolidated statements of operations for the six months ended June 30, 2021 and 2020, was $1,971,000 and $1,995,000, respectively. Capitalized asset retirement costs were $39,370,000 (consisting of $23,584,000 of known environmental liabilities and $15,786,000 of reserves for future environmental liabilities) as of June 30, 2021, and $39,610,000 (consisting of $23,573,000 of known environmental liabilities and $16,037,000 of reserves for future environmental liabilities) as of December 31, 2020. We recorded impairment charges aggregating $1,500,000 and $1,446,000 for the six months ended June 30, 2021 and 2020, respectively, for capitalized asset retirement costs.

Environmental exposures are difficult to assess and estimate for numerous reasons, including the amount of data available upon initial assessment of contamination, alternative treatment methods that may be applied, location of the property which subjects it to differing local laws and regulations and their interpretations, changes in costs associated with environmental remediation services and equipment, the availability of state UST remediation funds and the possibility of existing legal claims giving rise to allocation of responsibilities to others, as well as the time it takes to remediate contamination and receive regulatory approval. In developing our liability for estimated environmental remediation obligations on a property by property basis, we consider, among other things, laws and regulations, assessments of contamination and surrounding geology, quality of information available, currently available technologies for treatment, alternative methods of remediation and prior experience. Environmental accruals are based on estimates derived upon facts known to us at this time, which are subject to significant change as circumstances change, and as environmental contingencies become more clearly defined and reasonably estimable.

Any changes to our estimates or our assumptions that form the basis of our estimates may result in our providing an accrual, or adjustments to the amounts recorded, for environmental remediation liabilities.

In July 2012, we purchased a 10-year pollution legal liability insurance policy covering substantially all of our properties at that time for preexisting unknown environmental liabilities and new environmental events. The policy has a $50,000,000 aggregate limit and is subject to various self-insured retentions and other conditions and limitations. Our intention in purchasing this policy was to obtain protection predominantly for significant events. In addition to the environmental insurance policy purchased by the Company, we also took assignment of certain environmental insurance policies, and rights to reimbursement for claims made thereunder, from Marketing, by order of the U.S. Bankruptcy Court during Marketing’s bankruptcy proceedings. Under these assigned polices, we have received and expect to continue to receive reimbursement of certain remediation expenses for covered claims.

In light of the uncertainties associated with environmental expenditure contingencies, we are unable to estimate ranges in excess of the amount accrued with any certainty; however, we believe that it is possible that the fair value of future actual net expenditures could be substantially higher than amounts currently recorded by us. Adjustments to accrued liabilities for environmental remediation obligations will be reflected in our consolidated financial statements as they become probable and a reasonable estimate of fair value can be made.