The Airports Company of South Africa (Acsa) still does not know what caused the hole in the main runway of the Cape Town International Airport.
Acsa spokesperson Deirdré Hendricks told journalists on Tuesday that the matter was still being investigated.
But Acsa would spend about R36m in the new financial year on maintenance for the main runway of 3.2km.
She said there had been widespread speculation in the past few days about the causes of the hole on runway 19.
She said the speculations that moles might have damaged the runway were definitely not true. Acsa still believed that environmental and stress factors were the logical answer.
A Capetonian pest controller and expert who does not want to be named for professional reasons, said moles might have caused the damage.
"Moles often make burrows under constructions such as roads and runways. This area is hot and dry, and is an ideal home for these animals.
"The burrows might have made the reinforced concrete surface subside slightly and then the asphalt could easily have been ripped off," he said.
Hendricks said Acsa wanted to emphasise that the main and secondary runways were closed from 11:35 to 17:00 on Sunday so that an airport team could repair the hole. A piece of asphalt had been ripped off the main runway.
"The pilot of a plane that took off at 11:20 reported the damage on runway 19. Engineers discovered a hole of 6m by 3m. Asphalt 3cm thick was ripped off the runway," Hendricks said.
Airport manager George Uriesi said Acsa apologised for any inconvenience.
"But the safety of airport users is very important. Acsa cannot take chances with people's lives," he said.
He added that the runways at Cape Town International Airport complied with international safety standards and boasted some of the safest runways in Africa.
"Incidents like this are not unique. International airports everywhere in the world also regularly interrupt their normal activities to solve problems," Uriesi said.
He said the airport here complied with all the requirements that the Civil Aviation Authority (CAA) expected of an airport.