Sts. & Hy. Code, § 10352

All changes shall be made on notice and hearing as herein provided, except changes may be made:

(a) At the hearing on the report, which:

(1) Reduce the total amount of the assessment or make no change in the total amount of the assessment and no increase or decrease in the amount of money assessed on each parcel of property included in the assessment; or

(2) Eliminate a portion of the work or provide a substitution therein without increasing the cost of any assessment by reason thereof or substantially affecting the distribution of benefits from the work; or

(3) Eliminate a portion of the assessment district without increasing the amount of any assessment by reason thereof or substantially affecting the distribution of benefits from the work; or

(4) Exclude territory which will not be benefited by the improvement without increasing the amount of any assessment by reason thereof; and

(b) At any time after the improvements are ordered and during the pendency of the proceedings, which;

(1) Do not increase the total amount of the assessment; or

(2) Provide for the elimination or addition of work or substitutions therein, though they result in an increase in some assessments, provided that the owners of the property affected request in writing that the changes in the work and in the assessments be made; or

(3) Exclude territory which will not be benefited by the improvement without increasing the amount of any assessment by reason thereof.