Unless otherwise provided for by sections 68-601 to 68-631, each political subdivision of the state is hereby authorized to submit for approval by the state agency a plan for extending the benefits of Title II of the Social Security Act, in conformity with applicable provisions of such act, to employees of such political subdivision and is hereby further authorized to submit for approval by the state agency any modification or amendment to any then existing plan if such modification or amendment is necessary or desirable to secure the benefits and exemptions allowable to such political subdivisions thereof or to any employee of the political subdivision in conformity with Title II of the act. Each such plan and any amendment thereof shall be approved by the state agency if it finds that such plan or such plan as amended is in conformity with such requirements as are provided in regulations of the state agency, except that no such plan shall be approved unless: (1) It is in conformity with the requirements of the act and with the agreement entered into under sections 68-603 and 68-604; (2) it provides that all services which constitute employment and are performed in the employ of the political subdivision by employees thereof will be covered by the plan; (3) it specifies the source or sources from which the funds necessary to make the payments required by subsection (1) of section 68-610 and by section 68-611 are expected to be derived and contains reasonable assurance that such sources will be adequate for such purpose; (4) it provides for such methods of administration of the plan by the political subdivision as are found by the state agency to be necessary for the proper and efficient administration of the plan; (5) it provides that the political subdivision will make such reports in such form and containing such information as the state agency may from time to time require and will comply with such provisions as the state agency or the Secretary of Health and Human Services may from time to time find necessary to assure the correctness and verification of such reports; and (6) it authorizes the state agency to terminate the plan in its entirety, in the discretion of the state agency, if it finds that there has been a failure to comply substantially with any provision contained in such plan, such termination to take effect at the expiration of such notice and on such conditions as may be provided by regulations of the state agency and may be consistent with the provisions of the act.