The 23 ha site falls within an HSE consultation zone because it is close to the Hickson and Welsh chemical plant, in Castleford, West Yorkshire.
Regeneration quango English Partnerships, joint developer with a Gleeson Homes/Miller Homes venture, is paying for the remediation work at the plant.
Once the work is complete, the consultation zone will be lifted.
Duncan Innes, English Partnerships' head of Millennium Communities, said the delay would give Gleeson Homes the opportunity to make changes to the way the scheme is designed. He said: "The developer is taking advantage of the extra time to review the house types used. The size of some houses and room layout are being looked at."
Innes added that other areas, such as car parks, are also under review. Innes played down fears that Gleeson's switch to traditional housebuilding would lead to a watering down of the scheme's architectural ambitions.
The developer is using the extra time to review house types
Duncan Innes, EP senior executive
He said: "We sat down specifically with Gleeson to work through its commitment to the scheme. Gleeson is committed to the Millennium Village."
EP has decided to develop other parts of the scheme early to ensure the housing delay has less impact.
It is working on landscaping aspects and improved access to facilities for disabled people.
A source close to the scheme said: "In acknowledgement that there is a delay in the whole programme, EP wanted to get started on particular parts of the project."