A 53-home boost to a housing development will get the go ahead, if the Environment Agency drops its objection.
Linden Homes Midlands and Providence Court Investment are hoping to increase the number of houses to 139 on the seven-hectare Sawmills Site in Brackley.
But the agency has concerns because past investigations have identified both soil and groundwater contamination in the area.
It says is has not seen enough evidence that water will not be polluted and that the site can deal with flood risks.
South Northants Council (SNC) say the objection is because some application documents were not available online so has asked the agency to reconsider.
If the objection is dropped before July 11 and planning obligations are met, a mix of 53 detached, semi-detached and short terrace homes will be given the go-ahead.
Construction work would then start before the end of the year and would be finished for 2018.
The triangular-shaped Sawmills site has been subject to contamination partly because of where it gets its name from – it used to be a sawmill.
Tanalising - which gives softwood long-term protection - took place over a long period of time and chemicals are said to have contaminated the soil.
Contamination was also caused by the infilling of a former railway cutting to the western edge of the site.
But SNC and Northants County Council have no objections with plans for the site which is bordered by a number of current applications.
To the north of the site is land subject to a current and separate application of 180 homes, known as the Foxhills development.
To the north-west of the site, is the Radstone Fields Sustainable Urban Extension for 1,000 homes and to the south-east - on the opposite side of Northampton Road - is the site for a proposed Sainsbury’s supermarket.
Speaking in January, when the Foxhill application for 180 homes was made, Brackley town mayor Chris Cartmell said the council was ‘more than satisfied’ with the proposal.
He said: “All of these developments can only be good for the town. If Sainsbury’s does go ahead, we will have a new supermarket at that end of town.
“That will complement all of the new houses which will eventually be built and it is all good in terms of competition for the other supermarkets and petrol stations.”