When the managing director or a designee determines in writing that it is impracticable to secure competition for required materials, equipment, or supplies, he or she may purchase the materials, equipment, or supplies without competition. The term "impracticable to secure competition" means:
(1) When material, equipment, or supplies can be obtained from only one person or firm (single source of supply); or
(2) When specially designed parts or components are being procured as replacement parts in support of equipment specially designed by the manufacturer.