Morisset Showground Trust ground maintenance manager Robert Royal said the trust was appalled by the vandalism.

The attack has forced them to erect fencing earlier than planned.

"We're losing income we've already spent; we spent six months developing the ground cover for the field," Mr Royal said.

However, the trust is determined not to let the hoons slow the progress of the oval and have recently finished $150,000 worth of earthworks.

Mr Royal said the next step is erecting the lighting poles, which have been delivered to the ground and cost the trust about $26,000.

He expects the work to erect the poles to begin soon and to take two to three weeks. The next step will be to run power underground to the field, followed by installing the lights, which the trust aims to complete by the end of the year.

"We are eating the elephant one bite at a time," Mr Royal said.

"There is over half a million dollars worth [of work planned], so we are chewing away at it as the funds became available.

"There is still a lot to do between now and finishing."

Mr Royal said a contractor has recently been appointed to carry out the $113,000 upgrade to the amenities, which will take about 14 weeks.

The trust also plans to construct dog-show rings, new change rooms and a new canteen.

Mr Royal has recently stepped down as trust secretary due to work commitments. Lake Macquarie City councillor Rosmairi Dawson has stepped in to fill the position.