Still to be explained was whether someone moved a 20kg manhole cover over the stormwater drain in which the toddler was believed to drowned, Mr Harvey said.
West Auckland residents also said they had complained the manhole cover would come loose in heavy rain, but council did nothing about it.
Mr Harvey will today go into his first council meeting since Aisling's body was found in the drain on Monday, a week after she disappeared from a house in Longburn Rd, Henderson.
Her body was about 1.5 metres underground, 36 metres downstream from an inspection access pipe with a heavy manhole cover.
It was believed she got into the drain the day she went missing.
Police arrived within a few minutes of a frantic call from her family and reportedly found the manhole cover ajar by about 80-100mm.
While it was not thought the gap was enough for a child to squeeze through, Mr Harvey said that was one question the council now had to answer.
"So what happened? That child had to go down that drain," he said.
"She is small but she is not that small and then someone has got to close it (the manhole cover) to that degree after she is in the drain." The drain was blocked by tree roots and that was thought to cause back pressure, which forced off the manhole cover.
The council yesterday said it was considering how to respond to complaints from neighbours, and how to deal with the blockage, when Aisling died.
Police dug up the drain and found Aisling's body after sending cameras down the pipe, which found no sign of her.
Her body was found only when diggers and concrete cutters were used to break in to where the drain was blocked by roots.
The latest complaint received about the drain was on September 11, council spokesman Wally Thomas said.
