Section 81U. When a definitive plan of a subdivision is submitted to the planning board, as provided in section eighty-one O, a copy thereof shall also be filed with the board of health or board or officer having like powers and duties. Such health board or officer shall, within forty-five days after the plan is so filed, report to the planning board in writing, approval or disapproval of said plan, and, in the event of disapproval, shall make specific findings as to which, if any, areas shown on such plan cannot be used for building sites without injury to the public health, and include such specific findings and the reasons therefor in such report, and where possible, shall make recommendations for the adjustments thereof. Failure of such board or officer to report shall be deemed approval by such board or officer. Such health board or officer shall send a copy of such report, if any, to the person who submitted said plan. When the definitive plan shows that no public or community sewer is to be installed to serve any lot thereon, approval by a board of health or officer shall not be treated as, nor deemed to be approval of a permit for the construction and use on any lot of an individual sewage system; and approval of a definitive plan for a subdivision by a board of health or officer shall not be treated as, nor deemed to be, an application for a permit to construct or use an individual sewage system on any lot contained therein.

After the hearing required by section eighty-one T and after the report of said health board or officer or lapse of forty-five days without such report, the planning board shall approve, or, if such plan does not comply with the subdivision control law or the rules and regulations of the planning board or the recommendations of the health board or officer, shall modify and approve or shall disapprove such plan. In the event of disapproval, the planning board shall state in detail wherein the plan does not conform to the rules and regulations of the planning board or the recommendations of the health board or officer and shall revoke its disapproval and approve a plan which, as amended conforms to such rules and regulations or recommendations. The planning board shall file a certificate of its action with the city or town clerk, a copy of which shall be recorded by him in a book kept for the purpose, and shall send notice of such action by registered mail, postage prepaid, to the applicant at his address stated on the application.

If the report of the board of health or board or officer having like powers and duties shall so require, the approval by the planning board shall be on condition that no building or structure shall be built or placed upon the areas designated without consent by such board of health or officer. In the event approval by the board of health or board or officer having like powers and duties is by failure to make a report, the planning board shall note on the plan that health approval is by failure to report.

In the case of a nonresidential subdivision where a preliminary plan has been duly submitted and acted upon or where forty-five days has elapsed since submission of the said preliminary plan, and then a definitive plan is submitted, the failure of a planning board either to take final action or to file with the city or town clerk a certificate of such action regarding the definitive plan submitted by an applicant within ninety days after such submission, or such further time as may be agreed upon at the written request of the applicant, shall be deemed to be an approval thereof. Notice of such extension of time shall be filed forthwith by the planning board with the city or town clerk.

In the case of a subdivision showing lots in a residential zone, where a preliminary plan has been acted upon by the planning board or where at least forty-five days has elapsed since submission of the preliminary plan, an applicant may file a definitive plan. The failure of a planning board either to take final action or to file with the city or town clerk a certificate of such action on the definitive plan within ninety days after such submission, or such further time as may be agreed upon at the written request of the applicant, shall be deemed to be an approval thereof. Notice of such extension of time shall be filed forthwith by the planning board with the city or town clerk.

In the case of a subdivision showing lots in a residential zone, where no preliminary plan has been submitted and acted upon or where forty-five days has not elapsed since submission of such preliminary plan, and a definitive plan is submitted, the failure of a planning board either to take final action or to file with the city or town clerk a certificate of such action regarding the definitive plan submitted by an applicant within one hundred thirty-five days after such submission, or such further time as may be agreed upon at the written request of the applicant, shall be deemed to be an approval thereof. Notice of such extension of time shall be filed forthwith by the planning board with the city or town clerk.

Before endorsement of its approval of a plan, a planning board shall require that the construction of ways and the installation of municipal services be secured by one, or in part by one and in part by another, of the methods described in the following clauses (1), (2), (3) and (4) which method or combination of methods may be selected and from time to time varied by the applicant:

(1) By a proper bond, sufficient in the opinion of the planning board to secure performance of the construction of ways and the installation of municipal services required for lots in the subdivision shown on the plan, and the planning board may require that the applicant specify the time within which such construction shall be completed.

(2) By a deposit of money or negotiable securities, sufficient in the opinion of the planning board to secure performance of the construction of ways and the installation of municipal services required for lots in the subdivision shown on the plan, and the planning board may require that the applicant specify the time within which such construction shall be completed.

(3) By a covenant, executed and duly recorded by the owner of record, running with the land, whereby such ways and services shall be provided to serve any lot before such lot may be built upon or conveyed, other than by mortgage deed; provided, that a mortgagee who acquires title to the mortgaged premises by foreclosure or otherwise and any succeeding owner of such premises or part thereof may sell any such lot, subject to that portion of the covenant which provides that no lot shall be built upon until such ways and services have been provided to serve such lot; and provided, further, that nothing herein shall be deemed to prohibit a conveyance by a single deed, subject to such covenant, of either the entire parcel of land shown on the subdivision plan or of all lots not previously released by the planning board. A deed of any part of the subdivision in violation hereof shall be voidable by the grantee prior to the release of the covenant but not later than three years from the date of such deed.

(4) By delivery to the planning board of an agreement executed after the recording of a first mortgage covering the premises shown on the plan or a portion thereof given as security for advances to be made to the applicant by the lender, which agreement shall be executed by the applicant and the lender and shall provide for the retention by the lender of funds sufficient in the opinion of the planning board and otherwise due the applicant, to secure the construction of ways and the installation of municipal services. Said agreement shall also provide for a schedule of disbursements which may be made to the applicant upon completion of various stages of the work, and shall further provide that in the event the work is not completed within the time set forth by the applicant, any funds remaining undisbursed shall be available for completion.

Any covenant given under the preceding paragraph and any condition required by the health board or officer shall be either inscribed on the plan or contained in a separate document, referred to on the plan.

The penal sum of any such bond held under clause (1) or any deposit held under clause (2) or any amount of funds retained pursuant to an agreement under clause (4) shall bear a direct and reasonable relationship to the expected cost including the effects of inflation, necessary to complete the subject work. Such amount or amounts shall from time to time be reduced so that the amount bonded, deposited or retained continues to reflect the actual expected cost of work remaining to be completed.

Upon the completion of the construction of ways and the installation of municipal services in accordance with the rules and regulations of the planning board, security for the performance of which was given by bond, deposit or covenant, or upon the performance of any covenant with respect to any lot, the applicant shall send by registered mail to the city or town clerk and the planning board a written statement that the said construction or installation in connection with which such bond, deposit or covenant has been given has been completed in accordance with said rules and regulations, such statement to contain the address of the applicant. If the planning board determines that said construction or installation has been completed, it shall release the interest of the town in such bond and return the bond or the deposit to the person who furnished the same, or release the covenant by appropriate instrument, duly acknowledged, which may be recorded. If the board determines that said construction or installation has not been completed, it shall specify in a notice sent by registered mail to the applicant and to the clerk of the city or town the details wherein said construction or installation fails to comply with its rules and regulations and upon failure so to do within forty-five days after the receipt by said clerk of said statement all obligations under the bond shall cease and terminate by operation of law, any deposit shall be returned and any such covenant shall become void. In the event that said forty-five day period expires without such specification, or without the release and return of the bond or return of the deposit or release of the covenant as aforesaid, the said clerk shall issue a certificate to such effect, duly acknowledged, which may be recorded.

Any such bond may be enforced and any such deposit may be applied by the planning board for the benefit of such city or town, as provided in section eighty-one Y, upon failure of the performance for which any such bond or deposit was given to the extent of the reasonable cost to such city or town of completing such construction and installation.

In any town which accepts the provisions of this paragraph, the proceeds of any such bond or deposit shall be made available to the town for expenditure to meet the cost and expenses of the municipality in completing the work as specified in the approved plan. If such proceeds do not exceed one hundred thousand dollars, the expenditure may be made without specific appropriation under section fifty-three of chapter forty-four; provided, however, that such expenditure is approved by the board of selectmen. The provisions of this paragraph shall not apply to cities or to towns having town councils.

Before approval of a plan by a planning board, said board shall also in proper cases require the plan to show a park or parks suitably located for playground or recreation purposes or for providing light and air and not unreasonable in area in relation to the area of the land being subdivided and the prospective uses of such land, and if so determined said board shall by appropriate endorsement on the plan require that no building may be erected on such park or parks for a period of not more than three years without its approval.