1. Major repairs, alterations, extensions and improvements of drainage works for a drainage improvement district may be made by the department on petition therefor and after procedure thereon similar to that specified in section 15-1931 for original construction. If additional surveys are required, they may be authorized as provided in sections 15-1911, 15-1913, 15-1915 and 15-1917, except that the cost of surveys and other expenses may be included in the cost of the improvement and assessed on the properties to be served thereby in accordance with the apportionment of cost of the repairs.

2. Except where the department shall otherwise determine, the cost of improvements and repairs to a ditch already built under the provisions of title 19 of this article, or of any former drainage laws, shall be apportioned in the same manner as the original cost was apportioned, but the department may make a new apportionment by following the procedure above specified.