(a) Immediately after their qualification, the commissioners shall form plans for the improvement. To that end they may employ such engineers, attorneys, and other assistants as they find necessary and shall file a copy thereof with the county clerk.

(b)

(1) They shall thereupon appoint an assessor to assess the benefits which will accrue to the real property within the district from the making of the improvement.

(2) The assessor shall take an oath that he will well and truly assess all benefits that will accrue to the landowners of the district by the making of the proposed improvement.

(3) He shall thereupon proceed to assess the lands within the district and shall inscribe in a book each tract of land. He shall place in one (1) column his valuation of each tract or parcel of land before the improvement is made, which column may be marked "Assessed Value of Land before Improvements Are Made," and in another column he shall place what he thinks will be the value of each tract or parcel of land after the improvement is made, which column may be marked "Assessed Value of Land after Improvements Are Made." If the "Assessed Value of Land after Improvements Are Made" is greater than the "Assessed Value of Land before the Improvements Are Made," as assessed by the assessor for the district, then the difference between the two (2) shall be the assessed benefits that will accrue to each tract by reason of the improvement, but if the "Assessed Value of Land after Improvements Are Made" is less than the "Assessed Value of Land before Improvements Are Made," as assessed by the assessor for the district, then the difference between the two (2) shall be the assessed damages that will accrue to the particular parcel or tract of land by reason of the improvement. The assessor shall enter such assessment of benefits or damages opposite the description of each piece of property in appropriate columns, one (1) of which may be marked "Assessed Benefits," and the other may be marked "Assessed Damages," and in another column the assessor shall show the estimate of the probable cost to the landowner, which may be marked "Estimated Cost."

(4) His assessment shall embrace all the lands and improvements on real estate that will be benefited by the making of the improvement.

(5) The assessor shall place opposite each tract the name of the supposed owner, as shown by the last county assessment, but a mistake in the name shall not vitiate the assessment, and the assessor shall correct errors which occur in the county assessment list.

(6) The assessor shall also assess all damages that will accrue to any landowner by reason of the proposed improvement, including all injury to lands taken or damaged.

(7) Where he returns no such damages to any tract of land, it shall be deemed a finding by him that no damages will be sustained.

(8) When the board shall make the levy of taxes, it shall be the duty of the assessor to extend the amount levied and set that amount opposite each benefit assessed in a column marked "Annual Collection."

(9) The assessor shall hold his office at the pleasure of the board, which can fill any vacancy in the position of assessor.