The St George Illawarra Dragons lodged a development application for the $50 million centre at Innovation Campus with Wollongong City Council in December last year.

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At the time the Mercury reported that flood mitigation works would be needed to ensure the playing fields didn't end up underwater.

Part of that involved the installation of drainage and a slight slope of the fields to allow water to run off.

Owners of a property that backs onto the site of the centre, Roy Kampen and Brendon Wright, have lodged a 54-page objection to the proposed development.

In that objection, they cite council's development control plan for the site which states one guideline is to "maintain the existing surface topography through the northern floodway area of the site, which currently behaves as an informal floodway between Cabbage Tree Creek and the Towradgi Arm in major storm events".

They claim that the currently largely vacant site acts "like a large sponge" by soaking up some of the water.

The pair were concerned about the potential increased risk of flooding of their property, which they claimed would be a byproduct of the playing fields being raised to a higher level than their home.

A Dragons spokesman said the proposal worked to ensure "the development does not result in adverse off-site flooding impacts".

"A flooding assessment has been submitted to council as part of the DA demonstrating that all council requirements have been met," the spokesman said.

The residents also raised concerns about noise levels due to the increased use of the site.

They state noise from Dalton Park - which is further away than the proposed centre - is clearly audible when sport is being played.

The spokesman said an "operations management plan" would be in place, which would outline measures "that will aim to mitigate noise issues".