Pits and quarries are, by nature, self-consuming. Once a quarry's stone, sand and gravel have been fully extracted it's no longer necessary to keep it open. Sites can stay open for 35 years or more but many are depleted within 5 years. It all depends on how abundant the resource is and the rate at which the aggregate is extracted.
Unlike most other industrial uses, the sand and gravel operation is a temporary use that is not only making an important contribution to the economy but is simultaneously in the process of developing lands (and waters) for other uses. These uses can be anything from parks with fish and wildlife habitat to new residential subdivisions.
Progressive and final rehabilitation is the law.
All licences granted since the Aggregate Resources Act (1990) requireprogressive and final rehabilitation plans be in place. That means that at the end of each phase of extraction, the worked-on area must be rehabilitated. This results in only a small fraction of a pit being disturbed at any one time.
Aggregate is a unique industrythat allows land to be re-developed into a new use after extraction. Many former above-water sites return to agricultural land, natural land use or recreational areas.
A common myth is that once a below-water site has been extracted, all that remains is a stagnant pit of water. The reality is that pits and quarries are being rehabilitated as new wetlands and water features that encourage and enhance biodiversity.