Section 17. As used in this section and sections 18 to 21, inclusive, the following words shall, unless the context clearly requires otherwise, have the following meanings:

''Change order'', a written order not requiring the consent of the contractor, signed by the project manager and designated as an approved change order, directing the contractor to make changes in the work within the general scope of the contract, or, any written or oral order from the project manager which causes any change in the work, provided that the contractor gives the commonwealth written notice stating the date, circumstances, and source of the order and that the contractor regards the order as a change order.

''Contract modification'', any written alteration in plans or specifications, period of performance, price, quantity, or any other provision of the contract accomplished by mutual action of the parties to the contract.

The project manager may at any time, subject to the requirements set forth herein and in section 39I of chapter 30, order changes in the work within the general scope of the contract, including but not limited to changes: (a) in the plans and specifications (including drawings and designs); (b) in the method or manner of performance of the work; (c) in the commonwealth furnished facilities, equipment, materials, services or site; or (d) in the schedule for performance of the work. All such orders shall be written and designated to be change orders. All change orders or other contract modifications shall require the approval of the director when: (a) the cumulative cost of all previously approved increases in the contract price exceeds 5 per cent of the original contracted construction cost of the project, or such other percentage or dollar amount or criteria as designated by regulations of the commissioner; or (b) the preliminary estimate of the change in the contract price resulting from the change order or contract modification is $5,000 or more. The director may, after review of building projects for which the cumulative total of increases in the contract price has exceeded 5 per cent of the original contracted construction cost or such other percentage or dollar amount or criteria, direct the project manager as to those proposed changes, the preliminary estimated cost of which are under $5,000, that shall require the director's approval.

The commissioner shall promulgate regulations governing the procedures for obtaining preliminary estimates and giving notice to the contractor as to the necessity of obtaining the director's approval before any work pursuant to a change order or contract modification is commenced. Such procedures shall be designed so as to avoid delays in the progress of the project.

The project manager may delegate to the resident engineer, subject to approval by the director and notice to parties in interest, his authority to process and approve change orders when authorized to do so by regulations of the commissioner.

Section 20A of chapter 29 shall not apply to any change order request submitted and acted upon under sections 17 to 21, inclusive, of this chapter.