Mass. Gen. Laws ch. 83, § 21

If land abuts upon more than one way, assessments for sewers based wholly or in part upon frontage shall be assessed upon the frontage upon one such way and upon so much of the frontage upon such other way as is not exempted by the board whose duty it is to make the assessment; and such board may exempt from assessment so much of the frontage upon such other way as they consider just and equitable.