The county commission shall employ a county engineer, who shall be a thoroughly qualified and competent civil engineer, possessing all of the qualities as specified for county engineers under the general laws of the state. The engineer shall devote his or her time and attention to the maintenance and construction of the Fayette County public roads, highways, bridges, and county shop, and shall, during his or her employment, reside in Fayette County, Alabama. The county engineer shall serve at the pleasure of the county commission. The county engineer shall perform engineering and surveying services as required and prepare and maintain all necessary maps and records. The county commission shall fix the amount of the salary of the engineer.