A row has erupted between the quarry operators and conservationists about whether extending the quarry will damage local wildlife habitats.
Hanson Aggregates North are seeking permission from Flintshire County Council to extend Fagl Lane Quarry, on the outskirts of Caergwrle, near Mold.
Hanson now wants to create a 9.8 hectare extension - and to dredge its existing site to a greater depth.
If approval is granted, it will mean a further 3.9m tonnes of material can be removed from the site, giving it a projected lifespan running up to 2012-2017.
Flintshire planning committee has been recommended to approve the application, subject to conditions.
Hanson extracts sand and gravel from the site, using a dredger to remove minerals from a wet area, which is due to be restored as a pond.
The company argues its plans to restore the land with shallow lakes, wetlands, grassland and an area of woodland would have a significant wildlife conservation interest.
Wildlife habitat
But the extension area is the subject of a row over foraging habitat for species such as the greater crested newt, badgers and nesting site for hedgerow birds and possibly the flight path of bats.
But without firm evidence that the area should be a protected habitat, planning officials have recommended a condition that periodic checks are made for protected species, to allow for action to protect habitats.
Hanson claims its own restoration plans would enhance the area as a Site of Important Nature Conservation.
The council also wants to put in place conditions to control noise and dust levels on nearby residents.
In addition, the authority is looking at how the creation of a large area of water at the same level of River Alyn could provide enhanced flood relief, to accommodate surges in water levels.