A mutual agreement may include the location, the character of work to be done, the adjustment of the damages, the classification of the lands to be benefited by the agreement, the amount of special assessments to be levied, when the special assessments shall be levied, or so many of these or other provisions as may be agreed upon, and to such extent shall be as valid and binding as though performed in the mode and manner provided for in parts 1-12 of this chapter.