Plans have been put forward to redevelop a Flintshire secondary school site at an estimated cost of £31m.

Flintshire Council wants to create a combined primary and secondary school campus at Argoed High School in Mynydd Isa, near Mold.

Existing buildings would be demolished under the proposals to make way for Ysgol Mynydd Isa primary school to relocate to the Argoed site.

Collectively known as the Mynydd Isa Campus, both schools would be located under the same roof with some shared facilities, although they would be run separately.

New details have been revealed as part of a formal planning application submitted by the local authority, which has been published on its website this week.

It follows a bid by heritage campaigners to have the Argoed school buildings listed being rejected by the Welsh Government's historic environment service.

A planning statement entered in support of the proposals said the development was required because of the deteriorating state of the current buildings and lack of space for teaching.

It said: “Argoed High School is in a poor condition and no longer fit to support the needs of the new Welsh curriculum.

“There is a clear need to provide high quality energy efficient educational facilities that would support the delivery of the new Welsh curriculum.

“The site also contains two double mobile and two single mobile classrooms providing accommodation for up to 90 pupil places.

“However, these mobile classrooms have been on site circa 18 years and have reached the end of their useful life.

“Ysgol Mynydd Isa Primary School is split over two sites and within old buildings that place limitations on the provision of quality education for young people as well as posing duplication and management difficulties.”

According to the proposals, the new primary school would be built to accommodate 600 children, along with a nursery and specialist speech and language facility.

Meanwhile, the high school would house a further 700 pupils, also providing for youngsters with speech and language needs and Asperger's syndrome.

An attempt by the Twentieth Century Society to save the existing Argoed school buildings from demolition was recently rebuffed by Cadw.

Campaigners had claimed the school, which was built in three phases between 1977 and 1981, was worthy of retention as an example of Brutalist architecture.

However, despite the society's objections, Cadw officials said the buildings  were "not particularly noteworthy".

In a statement released last week, the group’s caseworker Coco Whittaker said: “We are very disappointed by this decision as we believe this is a fantastic example of a late 20th-century comprehensive school in Wales, designed in a bold but also contextual Brutalist style.

“The other major Brutalist school in Wales, Bettws in Newport, was demolished in 2008.”

Planners acting on the council's behalf said the new combined school for pupils aged three to 16 would result in the creation of "high quality facilities" to meet the local demand for school places.

The proposals will be considered at a later date and if approved, would be funded through the Welsh Government's Mutual Investment Model, which sees private firms contracted to build and maintain public assets.