The city of Gloucester appeals from orders denying its motions (predicated on objections) challenging subsidiary and general findings in a master’s report and adopting the report and from a judgment awarding the plaintiff, as receiver of R. & J. Salvucci Corporation (Sal- *455 vucci), $243,007.05 in damages (and $95,711.47 in interest) for several alleged breaches by the city of its road construction contract with Salvucci. 1 We reverse the judgment, holding that the report in its present form should not have been adopted but rather should have been recommitted for additional findings, summaries of the evidence, and production of certain exhibits.
The procedural background follows. Salvucci contracted to construct a road in and through the Cape Ann Industrial Park in Gloucester. Work commenced around July 1,1972, and was completed on October 31, 1973. In July, 1976, Salvucci’s receiver filed suit against the city. The amended complaint claimed that the contractor had incurred $528,753.76 in damages stemming from certain activities by the city in violation of the contract, among them a refusal to provide a disposal area for inorganic debris removed from the job, a failure seasonably to designate areas where suitable off-site borrow could be obtained, and a refusal to grant reasonable relief when the contractor encountered subsurface soil conditions at variance with those to be anticipated from the plans and test borings. The master, acting under a non-jury order of reference with evidence to be left unreported, found that the city had breached the contract: (1) by misrepresenting the subsurface soil conditions on the plans and thereafter refusing to allow Salvucci to deal with the actual conditions in a reasonable and economical fashion; (2) by seeking to impose a charge for use of the city dump in violation of a contract provision that promised a free disposal site for inorganic debris; (3) by ordering Salvucci to rebuild the road’s embankments after rocks buried in their sides at the engineers’ directions had caused concave slopes; and (4) by failing, as required by the agree *456 ment, to designate a suitable area for the excavation of usable gravel borrow and fill for the road’s subgrade. The master also found that a memorandum signed by Salvucci’s president just prior to the job’s completion, which stated that the contractor had no present or anticipated claims under the agreemént against the city, did not constitute a waiver or release of the contractor’s rights, and that, if the memorandum was held sufficient to waive or release Salvucci’s claims, it was signed under duress. Finally, the master found that, although Salvucci had failed to comply with the contract procedure for claiming payment for extras, the city was “aware that the corporation was incurring . . . extra costs and intended to make a claim in connection therewith.”
Following the filing of the report, the city, punctiliously adhering to the requirements of Mass.R.Civ.P. 53, as amended,
1. The central task confronting the court based on the report’s findings was one of contract interpretation.
Daley
*457
V.
J.F. White Contr. Co.,
In our view, the master’s findings, both subsidiary and general, are insufficient to permit a judge to address adequately the dispositive legal questions. The report does not (as it should) disclose on its face all the subsidiary findings which the master had in mind and upon which he based his general findings. Bi
lls
v.
Nunno, supra
at 282, and cases cited. The subsidiary findings on several of the vital issues are vague and non-specific and leave the general findings ultimately predicated thereon lacking in sufficient foundation. See
Lattuca
v.
Cusolito,
We conclude that the city has demonstrated probable error on the face of the report
(Minot
v.
Minot,
2. To speed disposition of the case, we briefly comment on the legal principles that are to be applied to the facts once the report is put in good order.
*460
On a public construction contract, if actions or requirements of the public agency necessitate changes in the work as it progresses, thereby causing the contractor to perform extra work or incur added expense, or if the contractor encounters materially different conditions from those predicted by the plans, specifications, preliminary borings and estimates, the contractor must follow the procedures spelled out in the contract and in the Blue Book, if incorporated in the contract, to adjust the price before unilaterally accruing expenses to be pursued later on breach of contract or quantum meruit theories. See
United States
v.
Utah Constr. & Mining Co.,
Moreover, if the contractor argues (as it does here) that the agency waived compliance with the contract’s provisions, it is incumbent on it to show not only that G. L. c. 30, § 391, is inapplicable, but also that there was clear, decisive, and unequivocal conduct on the part of an authorized representative of the agency indicating that it would not insist on adherence to the agreement.
10
Cashman
v.
Boston,
3. This case, as have many others before it, illustrates that the experience with references to masters has not been a happy one. Stripped of excess baggage, this case involves questions of contract interpretation and construction which
*463
have always been better left to a judge than a master. See
D. Federico Co.
v.
New Bedford Redev. Authy.,.supra
at 143, and cases cited;
Stock & Grove, Inc.
v.
United States,
*464 Paragraph one of the judgment is reversed. The orders adopting the master’s report, overruling the city’s objections, and denying its several motions are reversed. The action is to stand for further proceedings in the Superior Court consistent with this opinion.
So ordered.
Notes
The city does not attack that part of the judgment dismissing its counterclaim seeking damages for Salvucci’s late completion of the contract. The city’s appeal from the denial of its motion for attorney’s fees and costs pursuant to G. L. c. 231, § 6F, inserted by St. 1976, c. 233, § 1, has not been briefed or argued, and is considered waived. Mass.R.A.P. 16(a)(4), as amended,
The city’s twelfth objection, while conceding that the attempted charges for disposal of inorganic materials violated the contract, indicates that any problem with this aspect of the contract may have been a misunderstanding which, when called to the city’s attention, was immediately corrected.
The city contends that the plans and specifications will show that the test borings warned the contractor that he would encounter “boney” subsoil conditions (as ultimately found) in the roadbed.
The report does not tell us whether the contract price was paid, or what extras were in fact adjusted under the contract. It finds that the city “intended” to charge for dumping privileges without amplification. It states with regard to the designation of an off-site excavation area that an agent of the Gloucester Industrial Development Commission imposed “onerous burdens” on Salvucci without specification as to what these burdens were. It does not explain the extra work Salvucci was required to do in the industrial park as a condition of obtaining off-site borrow or whether this work was included in the computation of damages.
According to the city’s objection 11, the paragraph of the contract referred to in the report with regard to the selection of off-site borrow areas omits by use of an ellipsis that part of the contract which indicated the parties’ agreement to use an area within lots 5-30 in the Cape Ann Industrial Park as shown on a designated site plan. Thus it may be, as the city contends, that the general area had been preselected, and that the improvement of certain lots within.the park had been agreed to as part of the use of the site for- excavation. There is also a question whether there was any serious delay on the city’s part in designating a specific site within the general area for excavation.
We do not accept the city’s argument that the exhibits are automatically before the reviewing court by reason of the language in Mass.R.Civ.
*459
P. 53(e)(1), as amended,
This statute provides that wilful and substantial deviations from the project’s plans and specifications cannot be made unless authorized in writing by the awarding authority or the engineer who is in charge of the work, and only when certain certifications approving the deviations have been made by the awarding authority, including, where applicable, a certification that “an equitable adjustment has been agreed upon between the contracting agency and the contractor and the amount in dollars of said adjustment.”
This statute provides that contracts of the type in issue here (see G. L. c. 30, § 39M, as amended by St. 1967, c. 535, §§ 4 & 5) must contain equitable adjustment provisions to cover site conditions which differ substantially or materially from conditions indicated in the plans or contract documents. Although this statute was enacted after the execution of Salvucci’s contract, the contract’s adjustment provisions appear to accomplish the same purpose.
The adjustment remedies benefit both the contractor and the public agency. The agency customarily relies on the changed conditions and extra work clauses to remove unknown risks from competitive bidding and to obtain favorable bid prices stripped of such risk factors. Such a policy benefits the agency by keeping costs down and benefits bidders by assuring them that they can be compensated by formulae for overcoming sub-surface conditions and for extra work not anticipated in their bid estimates, or suggested by available data or by site inspection. The purposes of these safety valve provisions are discussed in
Kaiser Indus. Corp.
v.
United States,
The present finding of the master that “the defendant was aware” that Salvucci was doing extra work and intended to bring a claim to recover for that work is inadequate without supporting subsidiary findings to warrant a conclusion of waiver by an authorized representative of the city.
Constant tinkering with Rule 49 of the Superior Court, as amended (1976), and its predecessors to create a basis for review of a report and decades of cases interpreting and applying the rule’s standards in an effort to formulate an efficient and understandable framework for the study of reports have only led to additional mystification on the part of lawyers who in good faith are attempting to attack a master’s subsidiary and general findings.
It is questionable now whether even trade secret cases, which have always been considered suitable grist for the master’s mill, are appropriate for referral in view of the length of time they take before the master and the complications that ensue. See
Jet Spray Cooler, Inc.
v.
Crampton,
