BUILDING homes and businesses in the Copley Valley will improve flooding problems, say the scheme's potential developers.
The firm, Genr8, accepts the 62.5million scheme – between Copley and Holmes Road in Sowerby Bridge – would be built on high-risk floodlands.
But they say new flood defences costing up to 6.25million would benefit Copley village and areas up and downstream of the River Calder.
A spokesman for Gener8 said: "The place is a former industrial site and the ground is clogged and so it gets saturated.
"You get rid of all that industrial mess, replace it with proper soil and proper foundations, get the river able to drain properly, put proper housing and proper businesses in there and you solve the problem."
Genr8 was commissioned by Calderdale Council to carry out technical surveys at the site. Sterne Bridge would be replaced and a new surface-water drainage system built.
The firm's report says the development could also reduce river levels by up to 9mm.
Diane Wade, of Copley Village Environmental Group, said the group want more information.
She said: "They've proposed all sorts of mitigation but they need to prove it."
A 2,000-page traffic assessment has also been released which the campaign group are contrasting with another report from 2005.
Mrs Wade said original traffic assessments in 2005 showed the infrastructure could not meet the extra demand from traffic.
"On the south bank you're going to put an industrial site like Lowfields in Elland. In order for Sterne Bridge to be big enough for those lorries, a dual carriageway is going to have to be built across there," she said.
The group also say the scheme would destroy local wildlife by taking away hectares of green land.
Genr8 says a quarter of the site will be set aside as a nature reserve. "This is very much a priority, not an afterthought," said the firm.
But Mrs Wade said: "They're pretending they're giving us a brilliant nature reserve but they're taking away 50 per cent of the one we already have."
The development is expected to raise more than 1.6 million for Calderdale Council in council tax match-funding from the Government, as part of its new housing incentive scheme.
While critics say it will destroy their local area, the developers say it will improve the area.
The company said treatment to remove asbestos, arsenic, lead and benzene will take place across the site and up to 600mm below.
The developers are showcasing the proposals over the next week, starting at Copley Primary School on Thursday from 4pm to 8pm.
A further two exhibitions will take place at St Paul's Methodist Church in Tower Hill, Sowerby Bridge, from 11am to 3pm on Saturday and 3pm to 8pm on Monday.