1. Whenever any sewer district shall have been organized as provided by sections 249.010 to 249.420, and it shall appear necessary, convenient or advisable to extend the boundaries of such district for the purpose of including therein a contiguous area which could be efficiently served by the sewer system of such district, or by reasonable modifications, extensions or improvements thereof, the boundaries of such district may be extended in the following manner; provided that such extension shall not include any territory within the boundaries of any other sewer district.

2. The trustees of such district may, and shall upon a petition therefor, signed by twenty-five or more persons residing within such district and owning property therein which is liable for assessment for the sewers constructed therein, file with the circuit court having jurisdiction of such district a petition setting forth the reason or necessity for extending the boundaries of such district; the boundary lines of the proposed extension and a request for the appointment of a sanitary engineer, with duties as herein provided, and a prayer for such further action as may be necessary to determine the question as to whether the boundaries of such district should be extended.

3. Upon the filing of such petition the said circuit court shall as soon as may be thereafter appoint a competent sanitary engineer, who shall possess the qualifications and shall subscribe the same oath as are now provided for the engineer appointed under the provisions of section 249.040.

4. Such engineer may alter or amend the boundaries of the proposed extension of the district as set forth in the petition so that such boundaries may embrace all of the area capable of being efficiently served or drained by the system of sewers in such district or by reasonable modifications, extensions or improvements thereof, or so as to exclude any part of the area within the proposed extended boundaries which is so situated as not to be benefitted by the sewer system of such district as changed or for the drainage of which the sewer system of such district is not or cannot be made efficiently and economically adequate. For this purpose the engineer shall have the power to make surveys and maps and do all things necessary to locate and describe such boundaries.

5. The engineer shall report whether or not he finds the proposed extension of such district will be for the preservation of the public health or public welfare or will be of public utility or benefit and in such report he shall state what changes, if any, will be required to be made in the sewer system within the boundaries of the district then existing and what extensions or additions will be necessary in the territory proposed to be annexed, and the probable cost thereof, in order to serve the territory within the proposed extended boundaries. The engineer shall file with his report a statement that he has consulted with the department of health and senior services in connection therewith, and he shall also file with his report any statement in writing which may have been made to him by said department of health and senior services covering the matters contained in such report.

6. The engineer shall within thirty days after his appointment, unless for good cause shown the court shall extend the time, report his findings in writing to the court with such maps, profiles, drawings or other data as are necessary to advise the court in the premises.