Section 7. Emergency Purchase of Materials and Services
   When, in the opinion of the Mayor, the City Manager and if appropriate, a department head, any emergency exists, the nature of which makes it impracticable to following ordinary purchase procedures as set out in this Charter, emergency purchases of materials and services may be made by the City Manager upon the written certificate of the Mayor, the City Manager and such department head, filed promptly with the City Secretary. Non-budgeted purchases made under the provisions of this section shall not exceed twenty-five thousand dollars ($25,000.00) for any one emergency. The form of notice shall read:
      We, the undersigned, Mayor, City Manager, and department head, hereby certify that an emergency has occurred making it impracticable to follow ordinary purchase procedures as set out in the City Charter of the City of Pleasanton, Texas, and it is urgent the city purchase materials and/or services of the value of not more than twenty-five thousand dollars ($25,000.00) the nature of same being generally as follows:
   (General Description .......)
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Mayor
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City Manager
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Department Head
   When such an emergency occurs and the cost of the materials and services are known to be, or are estimated by the City Manager, to exceed twenty-five thousand dollars ($25,000.00), the Mayor shall forthwith call a special meeting of the City Council to be held at the earliest date and time for the purpose of taking appropriate action under such emergency.