Section 42. The commission may grant to towns locations for common sewers and drains in and across reservations or boulevards under its care and control. Whenever a drain or sewer is laid in locations so granted, the board of town officers respectively authorized to levy and collect assessments for the laying of drains and sewers in such town shall have the same power to levy and collect assessments for drains and sewers laid in said reservations or boulevards as is given to them by law in the case of drains and sewers laid in the public ways of such town; provided, that no such assessment shall be levied upon any lands belonging to the commonwealth.