The head of a purchasing agency may make or authorize others to make an emergency procurement when there exists a threat to public health, welfare or safety or circumstances outside the control of the agency create an urgency of need which does not permit the delay involved in using more formal competitive methods. Whenever practical, in the case of a procurement of a supply, at least two quotes shall be solicited. A written determination of the basis for the emergency and for the selection of the particular contractor shall be included in the procurement file. No written contract may be required. The supplier of the supply, service or construction may be paid based on the emergency approval and approved invoice.