N.C. Gen. Stat. § 130A-291.2
When a permanent domestic wastewater collection and treatment system is not available at a construction site or a temporary special event, a temporary wastewater holding tank of adequate capacity to prevent overflow may be used under a mobile or modular office to accommodate domestic wastewater from a commode and sink. The wastewater shall be removed often enough to prevent the temporary domestic wastewater holding tank from overflowing. The owner or lessee of a temporary construction trailer shall contract with a registered septage management firm or registered portable toilet sanitation firm for the removal of domestic waste. The wastewater shall be removed from the temporary domestic wastewater holding tank by a septage management firm holding a current permit to operate a septage firm.
N.C. Gen. Stat. § 130A-291.2