This case arises from a dispute involving a 1968 contract between the contractor, C.J. Langenfelder & Son, Inc. (Langenfelder) and the District of Columbia. The basic issue concerns whether in 1968, the contract term “equitable adjustment” included payment of interest on sums owed by the District to Langenfelder for costs incurred by Langenfelder in 1969-70, but not paid to Langenfelder until June 19,1980. Because contract terms must be construed according to their customary and common usage at the time when the parties executed the contract, we disagree with the trial court’s holding that the term “equitable adjustment” in this 1968 contract was meant to include interest foregone on capital expended to perform changes under the contract. Accordingly, we reverse.
I
The District of Columbia contracted with Langenfelder in 1968 to construct a portion of U.S. Highway 1-95 near the Rayburn House Office Building at a cost of approximately 24.5 million dollars. The contract directed that Langenfelder dispose of waste material resulting from the highway construction project at Dyke Marsh, an area in Virginia that was being filled to a grade that would cause flooding and allow restoration of the former swampland. In February of 1969, less than a month after the work had begun, the District imposed restrictions on Langenfelder’s use of Dyke Marsh which forced the contractor to incur additional costs at Dyke Marsh and to utilize private dump areas in Virginia and Maryland.
The contract contained the standard “changes clause” present in United States contracts at that time, and provided for “equitable adjustments” to be made in the contract price whenever the contracting officer ordered changes in the contract specifications which increased or decreased the cost of performance.1 Specifically, the contract stated:
Article 3. Changes. — The contracting officer may at any time, by a written *1157order, and without notice to the sureties, make changes in the drawings and/or specifications of this contract and within the general scope thereof. If such changes cause an increase or decrease in the cost of performing the work under this contract, or in the time required for its performance, an equitable adjustment shall be made and the contract shall be modified in writing accordingly.
Contract at 3 (emphasis added).
The parties do not dispute the actual cost of the changes computed as part of the equitable adjustment; after extensive litigation in the 1970s,2 the Contract Appeals Board (Board) determined that the District owed Langenfelder $320,877.27 for the cost of performing the changes unilaterally imposed by the District under the contract. This amount, however, was not paid by the District to Langenfelder until June 19, 1980. The contractor asserts that it is owed interest3 on this amount, that the interest is actually a cost that should be computed as part of the equitable adjustment, and that this additional cost should have been paid to it on June 19, 1980 as well.4
The contractor first brought its interest claim before the Board in 1975. The Board determined that the District owed Langen-felder interest or the “cost of operating capital” incurred by Langenfelder between February 19, 1969 and May 19, 1970.5 The Board concluded, however, that Langen-*1158felder was “not entitled to payment on its claim for general interest” as part of the cost of the equitable adjustment for interest accrued beyond the time of Langenfelder’s actual performance under the contract.
On September 12, 1979, the contractor filed a complaint for breach of contract in Superior Court challenging the Board’s denial for reimbursement for interest incurred on financing after May 19, 1970. Both parties filed motions for summary judgment. The contractor argued that it was entitled to interest on the $320,887.27 measured at the prime interest rate, 7.75%, from September 28,1975, to June 19,1980. The parties had stipulated that if the court found the contractor was entitled to recover financing costs, the applicable computation period would be from September 28, 1975, the date the contracting officer first became aware of the claim for interest, to June 19, 1980, the date when the District paid Langenfelder the $320,887.27. Further, the parties stipulated that the prime rate of interest applied to that sum would amount to $144,990.12. The District, conceding only that it owed Langenfelder the $320,887.27, argued that if Langenfelder was entitled to such interest costs, the applicable rate was 6% as required under D.C.Code § 28-3302(a) (1988 Supp.).6
The Superior Court held that the Contract Appeals Board erred in denying Lan-genfelder interest for the period up to June 19, 1980, and entered summary judgment for Langenfelder. The court implied that such a result was mandated by “equity” as well as “the terms of the instant contract” pursuant to the equitable adjustment clause, whether the cost of performance was financed by borrowings from the contractor’s bank or whether the contractor utilized its own funds for that purpose. Specifically, the court stated, “[Langenfelder] is entitled to an equitable adjustment of its contract price in an amount that will compensate it for the cost of the interest it had to pay because of having had to borrow money to perform the additional work....” C.J. Langenfelder & Son, Inc., supra, Civ. No. 11747-79 at 2-3. Thus, the court found that plaintiff’s payment of interest “represents a cost to plaintiff.” Id. at 3 (citing Maryland Port Administration v. C.J. Langenfelder & Son, Inc., 50 Md.App. 525, 438 A.2d 1374 (Ct.Spec.App.1982)). The court also noted, however, that:
Even if plaintiff had utilized its own assets to perform additional work required of it by the defendant, the Court is of the opinion that plaintiff would have been entitled to an equitable adjustment of its contract price to compensate it for such use.
Id. at n. 3.
Finally, the court concluded as part of its holding on this issue that since the Board “utilized the prime rate charged by [Lan-genfelder’s] lender during the time of the actual performance of the additional work” during 1969 and 1970 to compute the amount of interest owed, it too would apply the prime rate to Langenfelder’s claim for interest up to June 19, 1980. Id. at 3.
II
Stated simply, the question before this court is whether an “equitable adjustment,” as that contract term was used in 1968, was meant to include payment of interest as a cost incurred under the contract. Langenfelder argues that the term “equitable adjustment” implies an equitable, make-whole remedy that includes not only the cost of financing the actual changes in 1969-70 which amounted to $320,887.27, but also payment of interest on that sum which was not paid to Langenfelder by the District until 1980. Langenfelder relies heavily on two cases, the first of which was also relied upon in the Superi- or Court: Maryland Port Administration, supra, 438 A.2d 1374, and General Railway Signal Co. v. Washington Metropolitan Area Transit Authority, 875 F.2d 320, (D.C.Cir.1989). The District asserts that *1159while these cases perhaps represent a correct statement of the law in the late 1970s and 1980s, they are inapposite to an interpretation of the 1968 contract at issue in this case. We agree with the latter and hold that the terms of the contract never encompassed payment for the claimed interest here at issue as part of an equitable adjustment.
We further reject the proposition that equity guides our resolution of this case.
As a preliminary matter, we note that the dispute between Langenfelder and the District arises under the contract and is not in the nature of a breach of contract. “When the contract makes provision for equitable adjustment of particular claims, such claims may be regarded as converted from breach of contract claims to claims for relief under the contract.” Utah Construction, supra, 384 U.S. at 404 n. 6, 86 S.Ct. at 1551 n. 6 (citations omitted); see also Crown Coat Front Co. v. United States, 386 U.S. 503, 511, 87 S.Ct. 1177, 1182, 18 L.Ed.2d 256 (1967); District of Columbia v. Savoy Construction Co., 515 A.2d 698, 701-02 (D.C.1986). In cases arising under the contract, the contract itself governs the method and scope of relief available. Crown Coat, supra, 386 U.S. at 511, 87 S.Ct. at 1182.
It is a fundamental principle that “[t]he first step in contract interpretation is determining what a reasonable person in the position of the parties would have thought the disputed language meant.” Intercounty Construction Corp. v. District of Columbia, 443 A.2d 29, 32 (D.C.1982) (citations omitted). A presumption exists that the parties are aware of the surrounding circumstances at the time the contract was made. See 1010 Potomac Assocs. v. Grocery Mfrs., 485 A.2d 199, 205 (D.C.1984); Intercounty Construction Corp., supra, 443 A.2d at 32; Restatement (Second) of Contracts § 202 (1981). Further, the parties are “bound by all usages which either party knows or has reason to know.” Intercounty Construction Corp., supra, 443 A.2d at 32.
To determine the surrounding circumstances and common usage of a particular contract provision, courts must look to administrative and judicial interpretations of the contract provision at the time when the contract was executed. The meaning of a provision is fixed if there has been “uniform, continuous, and long-standing judicial and administrative construction” of its terms. Utah Construction, supra, 384 U.S. at 404-05, 86 S.Ct. at 1551-52. See generally 17 C.J.S. Contracts § 22 (1963 & 1988 Supp.) (“a contract will be construed according to the law of the state, as interpreted by its courts, at the time the contract was made, and not in accordance with subsequent decisions to the contrary.”) Thus, in Utah Construction, the Supreme Court refused the government’s request to alter a long-standing judicial and administrative construction of the disputes clause:
But even if, as an original matter, the language of the disputes clause might have been susceptible of the interpretation urged by the Government, the restrictive meaning of the words “arising under this contract” had long since been established when these parties used them in 1953. The question before us is what the parties intended, not whether the construction on which they relied was erroneous.
384 U.S. at 407, 86 S.Ct. at 1553 (emphasis added).
In 1968, the District and Langenfelder executed their contract against a background of judicial and administrative interpretations which held that a contractor could not recover interest for delays in the resolution of contract disputes with the government. One author, in discussing the historical evolution of these decisions, characterized the rule as an “ancient doctrine.” Walters, The Matter of Interest in Federal Government Contracting, 14 Pub. Cont. L.J. 96, 97 (Oct. 1983). Despite acknowledgments that equity might mandate a different outcome, the courts prior to 1968 steadfastly adhered to the rule that, in the absence of a statute or contractual provision to the contrary, interest was not recoverable on money owed by a sovereign. See United States v. New York Rayon Importing Co., 329 U.S. 654, 659-60, 67 S.Ct. 601, *1160603-04, 91 L.Ed. 577 (1947); United States v. North American Transp. & Trading Co., 253 U.S. 330, 336, 40 S.Ct. 518, 521, 64 L.Ed. 935 (1920); Tillson v. United States, 100 U.S. 43, 46, 25 L.Ed. 543 (1879); Acme Process Equip. Co. v. United States, 171 Ct.Cl. 324, 347 F.2d 509, 537 (1965), rev’d on other grounds, 385 U.S. 138, 87 S.Ct. 350, 17 L.Ed.2d 249 (1966); Komatsu Mfg. v. United States, 132 Ct.Cl. 314, 131 F.Supp. 949, 950 (1955); Ramsey v. United States, 121 Ct.Cl. 426, 101 F.Supp. 353, 356 (1951).
The District concedes, as it must, that the federal decisions are not directly controlling since they are based at least in part on the common law and statutory prohibition of the allowance of interest against the United States. See 28 U.S.C. § 2516(a) (1982). Compare Maryland Port Administration, supra, 438 A.2d at 1383. The courts in this jurisdiction and the Contract Appeals Board, however, have consistently applied federal contract provisions to District contracts. See, e.g., Savoy Construction Co., supra, 515 A.2d at 701 n. 3; District of Columbia v. Heman Ward, Inc., 261 A.2d 836, 837-38 & nn. 1, 2 (D.C.1970). Further, the Contract Appeals Board, whose cases supply authoritative construction of the equitable adjustment provisions of the District's contracts,7 has routinely followed the rule disallowing interest as part of an equitable adjustment. For example, in Community Residential Centers, Inc., CAB No. 478, Aug. 24, 1979, aff'd sub nom. Community Residential Centers, Inc. v. District of Columbia, No. 138-80 (Sup.Ct. July 1, 1981), aff'd by Memorandum Opinion and Judgment, No. 81-1055 (D.C. July 14,1982), the Board stated:
Contract Appeals Boards have consistently held that absent a specific contractual provision providing for interest payments, the Boards have no jurisdiction to allow such a claim. “It is well established that Boards of Contract Appeals may only grant that relief which is provided by the terms of the contract.” Appeal of L.A. Mann and Sons Construction, Inc., GSBCA No. 4542, 76-2 BCA II 12,087 (1976). Furthermore, the Board is not authorized to allow interest in the absence of such a provision because such action would constitute an improper reformation of the contract. “Since such clause was not included in the Appellant’s contract, there is, therefore, no basis for the Board to act and grant or consider interest since the Board does not have authority to reform the contract.” Appeal of E. Lionel Pavlo, GSBCA No. 39391-R, 74-2 BCA II 10,765 (1974). See also Appeal of T.M. Industries, ASBCA No. 20676, 76-1 BCA II 11,833 (1976); Appeal of Fruehauf Corporation, PSBCA No. 197, 76-1 BCA 1111,771 (1976), “... the fact remains that such interest consistently has been held unallowable, absent a statute or contract clause, before Boards of Contract Appeals, to the point where the legal writers consider the cases legion.”
Community Residential Centers, at 23-24; see also George Hyman Construction Co., 30 D.C.Reg. 4565, 4585 (1983); Clayton Mfg., 31 D.C.Reg. 1606, 1618-19 (1984). The rule was so engrained in the law of this jurisdiction that the D.C. Circuit noted that as of 1974, “not a single court or board of contract appeals had allowed recovery of interest foregone on equity capital as a ‘cost of performance.’” George Hyman Construction Co. v. Washington Metropolitan Area Transit Authority, 259 U.S. App.D.C. 449, 456, 816 F.2d 753, 760 (1987). This rule of construction was consistently applied by the Court of Claims and the Contract Appeals Board in the 1970s, when despite changes in the statutory law governing the payment of interest, most notably in the Contracts Disputes Act, see infra note 10, these tribunals refused to give retroactive effect to changes in the law. See, e.g., Brookfield Construction Co. v. United States, 228 Ct.Cl. 551, 661 F.2d 159, 163 (1981); Lawrence D. Krause, AGBCA No. 76-118-4, 82-2 BCA *1161¶16,129 (1982) (holding that although federal procurement regulations were amended on July 28, 1972, to require inclusion of standard clause for payment of interest, “such regulations did not apply retroactively to [the] contract which was awarded on May 2,1972.”); J.R Erickson, AGBCA, No. 333, 76-1 BOA ¶ 11,716 (1976).
Langenfelder ignores the vast body of law which firmly establishes that interest was not allowable as an element of compensation under the equitable adjustment provisions of the contract. The contractor’s emphasis on Kenny Construction Co. v. District of Columbia, 105 U.S.App.D.C. 8, 262 F.2d 926 (1959), to support its claim that interest was recoverable on District contracts despite federal precedent to the contrary, is misplaced. In Kenny Construction, the contractor’ and the District had entered into a contract which provided that monthly partial payments were to be made to the contractor as the work progressed with a 10% retainage until the work was completed by the contractor and accepted by the District. Id. 262 F.2d at 927. The District withheld payment at the end of the project alleging that the work had not been fully performed. Id. The D.C. Circuit held that the contractor could recover interest on that portion of the sum of money retained which exceeded the agreed upon 10% retainage. Id. at 930. The action in Kenny Construction was based on a breach of contract and was not an action arising under the contract, as is true in the present case, and therefore cannot be invoked in Langenfelder’s behalf.
An exception to the no-interest rule was established by the Court of Claims in 1968. In Bell v. United States, 186 Ct.Cl. 189, 404 F.2d 975 (1968), the court held that where a contractor could show that it paid interest on borrowings necessitated to perform changes pursuant to the changes clause of a contract, the contractor could recover the cost of such interest as part of the equitable adjustment under the contract. The court reasoned that this sort of interest payment was a cost of performance resulting from a government ordered change. The Court of Claims has consistently maintained this distinction between reimbursement of costs which could be traced directly to a loan obtained to perform changes ordered by the contracting officer and opportunity costs lost as a result of delays in payment. The former costs were deemed compensable, but the latter costs were not true performance costs lost as a result of delays in payment and thus were not compensable.8 See Dra-vo Corp. v. United States, 219 Ct.Cl. 416, 594 F.2d 842, 849 (1979) (finding that “ ‘clear necessity for borrowings occasioned by the change’ must be proven by the contractor”); Framlau Corp. v. United States, 215 Ct.Cl. 185, 568 F.2d 687, 694 (1977) (affirming Board’s decision to disallow interest where contractor failed to show what portion of claim was due to finance contract changes); Singer Co. v. United States, 215 Ct.Cl. 281, 568 F.2d 695, 718-20 (1977) (denying interest allowance where necessity for borrowing was not proven).
A finding that Langenfelder was paying interest between 1975 and 1980 on loans undertaken to finance the changes at Dyke Marsh in 1969 and 1970 was never made by the Contract Appeals Board, nor does such evidence exist in the record. Indeed, Lan-genfelder does not argue that it was in fact paying interest on such loans between 1975 to 1980. Rather, the thrust of Langenfelder’s argument seems to be that it was entitled to interest because it was deprived of the use of its money while the contract disputes mechanism ran its course.9 Thus, *1162the exception developed in Bell and its progeny does not apply.
The trial court in reviewing Contract Appeals Board decisions acts merely as a reviewing court and must sustain the findings of the Board if they are based on substantial evidence in the administrative record:
Even when the contractual scheme has run its course and the contractor is free to file his suit in court, he is not entitled to demand a de novo determination of his claim for an equitable adjustment. The evidence in support of his case must have been presented administratively and the record there made will be the record before the reviewing court. United States v. Carlo Bianchi and Co., 373 U.S. 709 [83 S.Ct. 1409, 10 L.Ed.2d 652 (1963)]; United States v. Utah Construction Co., 384 U.S. 394 [86 S.Ct. 1545, 16 L.Ed.2d 642 (1966) ]. The court performs principally a reviewing function. Only if it is alleged and proved that the administrative determination was arbitrary, capricious or not supported by substantial evidence may the court refuse to honor it.
Crown Coat, supra, 386 U.S. at 512-13, 87 S.Ct. at 1182-83. The trial court' in this case, however, went beyond the evidence presented to the Board and made the finding that Langenfelder made interest payments on its loans. Specifically, the court stated:
In order to perform the additional work necessitated by defendant’s actions, plaintiff was required to borrow money ... plaintiff is entitled to an equitable adjustment of its contract price in an amount that will compensate it for the cost of the interest it had to pay because of having had to borrow money to perform the additional work required of plaintiff by defendant pursuant to the provisions of the contract.
C.J. Langenfelder & Son, Inc., supra, Civ. No. 11747-79, at 1-2. This finding is simply not supported by evidence in the record. The trial court’s assumption on summary judgment that Langenfelder was paying interest between 1975 and 1980 was inappropriate.
Langenfelder also emphasizes the inequity of the rule, an argument that appeared to sway the trial court as it found for Langenfelder not only under the terms of the contract, but also in equity, the court opining that “[ejquity, as in ‘equitable’ adjustment, requires as much_” Id. at 3. To support its conclusions the trial court relied on Maryland Port Administration, supra, where the Maryland Court of Special Appeals, looking to federal case law, determined that interest was a cost of performance that could be recovered as part of an equitable adjustment. 438 A.2d at 1383-84.
Maryland Port Administration, however, is different in critical aspects from the present case. The contract at issue in that case was executed in 1978. By that time, the law regarding the recovery of interest for delays in payment by the government had begun to change. As noted by the court, the Defense Department changed its procurement procedures in 1976 to allow for predecision interest without regard to borrowing on the part of the contractor. Id. at 1383 (citing 32 C.F.R. § 7-104.82 (1979)). Then in 1978, Congress passed the Contracts Disputes Act of 1978, 41 U.S.C. § 601 et seq. (1982),10 which removed the former federal bar against claims for interest against the government. The Maryland court acknowledged that the *1163concept of “equitable adjustment” was new to Maryland and characterized the concept as one “intended to ‘keep a contractor whole.’” Maryland Port Administrar tion, supra, 438 A.2d at 1382-83 (citing Bruce Construction Corp. v. United States, 163 Ct.Cl. 97, 324 F.2d 516, 518 (1963)). What the Maryland court did, in essence, was to apply mid-1970 federal contract law to interpret a clause in a mid-1970 contract. This is entirely consistent with what we have done herein — applying 1968 contract law to a 1968 contract interpretation.
Further, for the reasons we have explicated above, we find inappropriate the analysis set forth by the D.C. Circuit and relied upon by Langenfelder in General Railway Signal Co. v. Washington Metropolitan Area Transit Authority, where the court, construing a changes clause in a 1971 contract with almost identical language to the one at issue in the present case, stated:
The “Changes” clause of that contract, as we have seen, authorizes “equitable adjustments” in cases like this. This term imports into the contract a doctrine mandating a make-whole remedy that will restore a contractor to the contractor’s pre-change circumstances. Courts have long recognized that restoration of a party to the status quo ante typically requires compensation for prejudgment interest, since it is an actual element of the costs incurred by virtue of the other parties, conduct. See Maryland Port Administration v. C.J. Langenfelder & Son, Inc. [50 Md.App. 525], 438 A.2d 1374 (Ct.Spec.App.1982); see also Bebchick v. Washington Metropolitan Area Transit Commission [207 U.S.App.D.C. 161], 645 F.2d 1086, 1093 (D.C.Cir.1981).
875 F.2d 320 at 327 (D.C.Cir.1989). We reject the perhaps linguistically-enticing, yet facile analysis relied upon in General Railway and the cases cited therein that “equitable adjustment” and “equity” are interchangeable concepts authorizing this court with roving discretion to reform the contracts of informed and sophisticated parties. See Maryland Port Administration, supra, 438 A.2d at 1383; Bebchick v. Washington Metropolitan Area Transit Commission, 207 U.S. App.D.C. 161, 168, 645 F.2d 1086, 1093 (1981) (allowing interest in “equitable proceeding” for restitution).
This is not an equitable action; it is an action arising under the contract. Equitable considerations have no bearing upon the validity of the Board’s determination. While the Maryland court in Maryland Port Administration, supra, 438 A.2d at 1382, wrote on a clean slate, “the concept of equitable adjustment [being] relatively new to Maryland,” this court does not. When Langenfelder and the District executed their contract the Contract Disputes Act was nothing more than an idea awaiting legislative birth. In the meantime, courts and administrative tribunals consistently construed interest claims against the contractor. Try as it might, Langenfelder cannot claim the benefit of an albeit enlightened 1978 legislative change and the resulting judicial interpretations for construction of its 1968 contract.
Reversed.
. The contract language was typical for District and federal government contracts in the 1960s. As the Supreme Court stated in United States v. Utah Construction & Mining Co.:
The typical construction contract between the Government and a private contractor provides for an equitable adjustment of the contract price or an appropriate extension of time, or both, if the government orders permitted changes in the work or if the contractor encounters changed conditions differing materially from those ordinarily anticipated.
384 U.S. 394, 396, 86 S.Ct. 1545, 1547, 16 L.Ed.2d 642 (1966).
The contract language at issue in this case is almost identical to the language used in contracts with the United States government. See, e.g., id. at 397 n. 1, 86 S.Ct. at 1547 n. 1 (construing contract with language: “The contracting officer may at any time, by a written order, and without notice to the sureties, make changes in ... this contract and within the general scope thereof. If such changes cause an increase or decrease in the amount due under this contract, or in the time required for its performance, an equitable adjustment shall be made and the contract shall be modified in writing accordingly.”); Bell v. United States, 186 Ct.Cl. 189, 404 F.2d 975, 976 (1968) (same).
. Langenfelder first filed its claim for an equitable adjustment in 1969, alleging that the District’s decision to restrict the use of Dyke Marsh had increased the cost of performance under the contract. This claim was filed with the District of Columbia contracting officer pursuant to Article 15 of the contract, which also provided for appeal from the decision of the contracting officer to the Contract Appeals Board. See Contract at 8 ("all disputes concerning questions arising under this contract shall be decided by the contracting officer subject to written appeal by the contractor within thirty (30) days to the Contract Appeals Board_").
The contracting officer denied the claim in 1970 and the Contract Appeals Board affirmed the decision in 1972. Langenfelder then brought suit in the United States District Court for breach of contract and asserted that the Board had improperly denied its claim. The District Court, in 1974, reversed the Board and held that the District had been responsible for some of the restrictions at Dyke Marsh and remanded the case to the Board to determine what damages, if any, Langenfelder had incurred. C.J. Langenfelder & Son, Inc. v. District of Columbia, Civ. No. 2109-72 (D.D.C.Sept. 10, 1974).
In 1975, Langenfelder filed a new claim with the contracting officer seeking interest on whatever sums the Contract Appeals Board ultimately found to be due Langenfelder. The Contract Appeals Board denied Langenfelder’s claim for interest and the Superior Court reversed the Board's decision. The resolution of this issue constitutes the focus of this opinion.
. Various terms have been used by the parties and the Board to describe exactly what is at issue. Langenfelder asserts that use of the word "interest" constitutes an “over-simplification’’ of "the concept at issue.” It prefers the phrase “the equitable adjustment cost of financing" in order to emphasize "that what is involved here is a cost to the contractor of performing additional work directed by the government, not originally contemplated in the contractor’s bid on the project.” Reply Brief at 4-5. The Board referred to Langenfelder’s claim as one for "general interest,” and the District simply refers to "interest.” The Superior Court refers to "the cost of the interest [Langenfelder] had to pay because of having had to borrow money to perform the additional work_’’ C.J. Langenfelder & Son, Inc. v. District of Columbia, Civ. No. 11747-79 at 3 (D.C.Super.Ct. June 16, 1987).
While acknowledging the nuances implied by the various characterizations of the issue, we prefer to use the term- "interest” to describe the cost incurred by Langenfelder for expending $320,877.27 to perform changes in 1969-70 pursuant to the changes clause in the contract, but not remitted to Langenfelder until June 19, 1980.
. Langenfelder also argues in its cross-appeal that it is owed prejudgment interest between June 19, 1980 and June 16, 1987, the latter date representing the day when the Superior Court entered its judgment in favor of the first interest claim. Because we reject Langenfelder’s first interest claim, we do not reach the prejudgment interest issue.
. February 19, 1969 represented the day on which excavation of the highway project requiring the use of Dyke Marsh began. Use of Dyke Marsh continued until May 19,1970, when Lan-genfelder decided against further use of Dyke Marsh for its disposal operations. The Board determined that for this period of time Langen-felder was entitled to reimbursement for various costs for delay, the disposal site investigation, the additional costs at the disposal sites, special insurance, taxes and the cost of operating capital.
. D.C.Code § 28-3302(a) (1988 Supp.) states: The rate of interest in the District upon the loan or forbearance of money, goods, or things in action in the absence of expressed contract, is 6 percent per annum.
. See generally Le Jimmy, Inc. v. District of Columbia Alcoholic Beverage Control Bd., 433 A.2d 1090, 1092 (D.C.1981) (not within province of court to substitute its own judgment for that of agency).
. Bell was decided on December 13, 1968. Supra, 404 F.2d at 975. The contract in this case was executed on December 16, 1968.
. In its Reply Brief, Langenfelder also advances two other arguments as to why it should not have to show that it made interest payments between Í975 and 1980. First, Langenfelder asserts that the fact that the parties stipulated the time period when the interest award, if any, would be computed, excuses it from the burden of showing actual interest payments over the time period in question. This argument is without merit. Second, Langenfelder argues that the issue of borrowing was not raised below. This argument too is without merit since Lan-genfelder should not be able to benefit from its failure to present evidence of interest payments. Had such evidence been presented, the Board *1162would have been required to apply the law as it had developed as of the date of the contract regarding the payment of interest on borrowings to finance contract modification.
. The Contract Disputes Act of 1978 provides for interest payments to contractors:
Interest on amounts found due contractors on claims shall be paid to the contractor from the date the contracting officer receives the claim pursuant to Section 605(a) of this title from the contractor until payment thereof. The interest provided for in this section shall be paid at the rate established by the Secretary of the Treasury pursuant to Public Law 92-41 (85 Stat. 97) for the Renegotiation Board.
41 U.S.C. § 611 (1982). See generally Walters, supra, 14 Pub.Cont.L.J. at 111-19 (discussing interest under the Contracts Disputes Act).