S.D. Codified Laws § 49-7A-8
An operator shall, upon receipt of the notice, advise the excavator of the location of underground facilities in the proposed excavation area by marking the location of the facilities with stakes, flags, paint, or other clearly identifiable marking within eighteen inches horizontally from the exterior sides of the underground facilities. The board shall promulgate rules, pursuant to chapter 1-26, to establish the response time for operators to mark the underground facilities. The response time shall be no later than forty-eight hours after the receipt of the notice, excluding Saturdays, Sundays, and legal holidays of the state or the excavation start time provided by the excavator, whichever is later. The response time may be less than forty-eight hours for emergency or subsequent inquiries to the original locate request and may be longer than forty-eight hours for nonexcavation requests. Excavators shall maintain a minimum horizontal clearance of eighteen inches between a marked underground facility and the cutting edge of any mechanical equipment. If excavation is required within eighteen inches, horizontally, the excavator shall expose the facility with hand tools or noninvasive methods approved pursuant to rule and shall protect and support the facility prior to further excavation with mechanical equipment.
SDCL 49-7A-8