If the executive director determines that the levels of financial responsibility required are not consistent with the degree and duration of risk associated with the facility or group of facilities, the executive director may adjust the levels of financial responsibility required for liability coverage as may be necessary to protect human health and the environment. An owner or operator must furnish to the executive director, within 30 days, any information which the executive director requests to determine whether cause exists for such adjustments of level of coverage. Any adjustment to the amount of financial assurance due to a change in the degree and duration of risk associated with the permitted facility will be treated as a permit modification.