In a contested case, a party or witness may apply to the agency for the appointment of a qualified interpreter to assist that party or witness, if the party or witness is deaf or, because of a hearing impediment, cannot readily understand or communicate the spoken English language. On application of the party or witness the agency shall appoint a qualified interpreter. In selecting a qualified interpreter for appointment, the agency may consult the directory of interpreters for manual communication or oral interpretation to assist deaf persons that is maintained by the courts of the State. An interpreter appointed under this section shall be allowed the compensation that the agency considers reasonable. Subject to paragraph (3) of this subsection, the compensation shall be paid by the agency. If the agency has the authority to tax for services and expenses as a part of the costs of a case, the agency may tax the amount paid to an interpreter as a part of these services and expenses in accordance with the federal Americans with Disabilities Act.