This guideline was developed to raise awareness among council staff and landowners about the risks associated with former sheep-dip sites. Old [The terms "old", "former", "historical" and "disused" are used synonymously throughout the guidelines for pre-1980 sheep-dip sites.] sheep-dip sites are typically contaminated due to the historical use of persistent and toxic chemicals such as arsenic, dieldrin, DDT and lindane. Exposure to these chemicals is likely to be hazardous to human health and the environment. Some of the toxicological effects may include effects on the central nervous system, liver and kidney damage, dermal lesions, suppression of the immune system and cancer.
The guideline aims to help local authorities address their statutory responsibilities in ensuring that land is suitable for its specified use, and to avoid an unacceptable risk to people and the environment. At high risk are children playing in or around old sheep-dip sites and ingesting contaminated soil, and site occupants who grow their own food on the contaminated area. Many areas in New Zealand previously used for pastoral farming are being developed into more intensive cropping, horticultural, dairying and residential land uses. As a result, local authorities now come across this kind of "hotspot" contamination more frequently, and having guidance available is very helpful.
The guideline provides best practice for local authorities to identify and oversee the investigation, management and remediation of contaminated sheep-dip sites. In particular, they provide guidance on how to:
- identify and locate former sheep-dip sites
- assess the risks to human and animal health, and to the environment
- evaluate remediation and long-term management options.
The different steps in the process of assessing a former sheep-dip site (identifying, investigating and remediating) are outlined. Guidance is also given to determine the acceptable level of contamination for various land uses.
Practical advice is provided in the form of a checklist that can be given to landowners to help identify dip sites on their property. There is also a flow chart that local authorities can incorporate into their "business-as-usual" contaminated land identification and management processes (ie, assessing applications for subdivision and other resource consents). The guideline recommends site management and remediation options, and give practical tips for the investigation and remediation of a site.
Like other existing industry-based guidelines, this guideline targets a specific contamination type − in this case, that associated with old practices of sheep farming − and should be used in conjunction with the Ministry for the Environment's Contaminated Land Management Guidelines series.