Locals in Mirfield who fought against a housing estate being built on an ancient floodplain are facing a new battle after an investigation of the site revealed contaminants in the earth.

Now people living near the fields on Granny Lane have sought assurance that soil containing toxins such as arsenic, asbestos and the carcinogenic benzo(a)pyrene won’t be used in gardens and an area of public open space included within the 67-house estate being built by Miller Homes.

A report by Wetherby-based environmental engineers Lithos says a three-phase investigation between December 2017 and April 2022 was carried out that tested ground and topsoil for a range of potential contaminants.

Of the 31 samples taken, 12 “yielded elevated concentrations of arsenic”. The chemical benzo(a)pyrene, which can cause cancer, was also found on the 5.4-acre site in a former paddock.

The report recommends that soil containing arsenic “is suitable for re-use” but that topsoil in the paddock “should be stripped and stockpiled separately from topsoil across the remainder of the site. Topsoil from the paddock should be used in areas of public open space only.”

This has caused concern amongst local people who have written to Kirklees Council seeking clarity. The authority approved building on the land last year.

Locals have asked for a meeting with Miller Homes and the council, and to receive an explanation “in layman’s terms” that might assuage their fears.

A spokeswoman for the Granny Lane Area Action Group (GLAAG), which opposed the housing scheme, said: “We find it very concerning that this investigation has identified that part of the site has significant levels of hazardous substances, resulting in the requirement for specialist handling, storage, removal and disposal of contaminated material.

“During the first consultation period [in] 2019, several local residents gave anecdotal evidence in the comments section that asbestos was buried within the site, so it comes as no surprise that this has now been discovered during demolition works.

“It is equally concerning that the report states that although some of the contaminated soil is unsuitable for gardens it can be used on the Public Open Space (POS),  which seems counter-intuitive to a layperson as this contains the children’s play area.

Another concern is that part of the public open space and play area is within Flood Zone 3. Therefore the soil can easily be washed into the surrounding watercourses as well as entering the drainage system and eventually the combined public sewer.”

Responding to criticism that building on the land was recommended for approval, a planning officer said: “While I do understand and appreciate the concerns surrounding asbestos, fundamentally it can be managed and address [sic] through the development process, typically through remediation of a site. Therefore it would not be a reasonable reason for refusal, or reason to delay a decision.”

Clr Martyn Bolt (Con, Mirfield) said: “Any developer can remediate the site if they throw enough money at it. Soil can be taken to a registered site for toxic materials. But to use that earth on a public open space is totally farcical.”