The development started around August last year, which was also when the school's grounds began flooding.
Last Thursday a meeting was held between Marshall, the Tawhero School board chair, Ministry of Education members, engineers from the council and its chief executive David Langford to discuss the issue.
"They still believe the plans they had for the subdivision were fine, even a council engineer went out there and said it was just heavy rain while standing in mud nearly up to his knees," Marshall said.
After the meeting, Langford sent an email to Marshall stating there wasn't any obvious cause for water ponding, given the adjacent subdivision had been designed to direct stormwater away from the school grounds.
"That said, as per the commitment I gave you council will undertake due diligence checks to ensure everything with both the council's stormwater infrastructure and the adjacent subdivision is working properly," Langford said in the email, seen by the Whanganui Chronicle.
"This will include comparing ground contours from both before and after subdivision, using these contours to confirm stormwater flow path, CCTV inspections of the stormwater pipes and systems to check."
Langford said the work would be carried out by the council's staff and maintenance contractors, and they did not know how much it would cost but it would be covered by the council's existing budgets.
"The council wants to support the school in whatever way we can, but at this stage, it is more important to establish the facts and identify the actual cause of the ponding," he said.
"Once we have this, we can figure out the next steps to fix the issue and who is responsible for doing it."
Marshall said one of the strategic goals for the school was to create tamariki who were physically active as it contributed to all facets of their wellbeing.
"But we're down to about a third of the playground we're used to having."
She said the school grounds were kept open during weekends so kids could use them instead of walking the streets.
"We feel like we give back to the community and we would love support from the council for that to continue because this [swamp] is unacceptable," Marshall said.
Pukeko have set up shop on the playing fields. Photo / Bevan Conley
A council spokesperson said its infrastructure team had been in correspondence with the previous principal of Tawhero School and the ministry at various times and plans were previously agreed with the ministry "to support them with managing stormwater on the school's grounds".
The spokesperson said the council was not aware of any sewage overflows and its current understanding was of a stormwater issue only.
The email said if all things went to plan, the results from the ground checks would be prepared in a report and ready to share with Marshall around August 26.
"In an ideal world, I'd love council to say they will fix it, but it's something rather than nothing and hopefully the problem is rectified," Marshall said.
