The Commissioner, upon written application made by the owner or operator, shall issue an overweight permit for the operation of underground pipe cleaning, hydroexcavating, and water blasting equipment. Any vehicle operating under a permit issued pursuant to this section shall have a gross weight of no more than 64,000 pounds, a single axle weight of no more than 20,000 pounds, and a tandem axle weight of no more than 44,000 pounds. Such permit shall not designate the route to be traversed nor contain restrictions or conditions not applicable to other vehicles in their general use of the highways. The fee for such permit shall be as provided in § 46.2-1140.1. For purposes of this section, “underground pipe cleaning equipment” means a self-propelled motor vehicle manufactured for the specific purpose of vacuuming and cleaning underground sanitary and storm pipe. “Hydroexcavating equipment” means a self-propelled motor vehicle manufactured for the specific purpose of digging with water and vacuuming of debris. “Water blasting equipment” means a self-propelled motor vehicle manufactured for the specific purpose of waterblasting flat concrete surfaces and vacuuming spent water for reuse.