Local authorities receive information of variable quantity and quality with new resource consent applications. This section of the guideline is aimed mainly at territorial authorities that evaluate information provided by applicants in the resource consent process with respect to identifying and assessing former sheep-dip sites. Regional councils may offer expertise and advice in the identification stage and often get involved at the investigation or remediation stage. Some overall guidance on information management is given in the last subsection.
Appendix 2 provides an example of a district plan containing policies and methods to avoid or minimise human health risks associated with contaminated land, specifically from former sheep-dip sites.
3.1 Resource consent applications
Most territorial authorities routinely check subdivision and other land-use applications for potential land contamination. Building consents can also be checked against potential land contamination. The checking process for disused sheep-dip sites is intended to be one of a number of assessments carried out on a resource consent application when it is received by a council. Even if the district plan does not have specific rules governing contaminated land, the checking routine should form standard practice in reviewing resource consent applications where potential contamination from historical land use exists.
Aside from old sheep dips and footbaths, there could also be other contaminant types present on the property, such as fuel from fuel storage, rubbish dumps, and asbestos (which was often used in buildings and sometimes on farm tracks). It is possible to exacerbate the exposure to contamination when building activities take place, and risks may also arise when changing from existing pastoral land use (eg, a sheep farm) to horticulture or cropping. While local authorities are not usually notified of changes to the cropping regime on rural land, they could give advice of this potential risk in leaflets about rural land. Changes in the status of rural land should also include assessment for potential land contamination.
The flow chart in Figure 5 sets out a systematic process for checking the adequacy of the information provided on potential former sheep-dip sites. The flow chart is designed as a series of prompts, to ensure that a processing officer can establish that all steps have been taken to determine whether a property is likely to have disused sheep dips, and that all probable sheep-dip locations have been identified and properly investigated.
The assumption is that the user is familiar with contaminated sites, and so the flow chart acts more as a prompt to ensure items are not overlooked than a "how to" guide for contaminated site investigations. Training should be given where this is not the case. The primary objective of the flow chart is to ensure that the right questions are asked and sufficient information is presented to allow the council officer to make a proper assessment.
Figure 5 pictorially summarises the information in the relevant sections in the guideline. It is intended for use in conjunction with this guideline, which should be read and understood prior to using the flow chart. Appropriate references are given to the guideline for clarification or prompting for the particular steps in the process. The accompanying notes provide some information on the use of the flow chart, including checklists and a table summarising the sheep-dip chemicals used in New Zealand.
The application is submitted to Council, information is checked if complete and if contamination issues were considered.
If contamination issues were not considered, request assessment of possible contamination (return)
If contamination issues were considered, was the site formerly a sheep farm?
|Sheep Dip identification|| |
If the site was not a sheep farm or it is uncertain, is the site history complete? (see Section 5.7)
If the site was not a sheep farm, request further information regarding past site use (return)
If the site was a sheep farm, is any indications of sheep dips?
If there are no indications of sheep dips, there are no further concerns regarding sheep dips
If there are indications of sheep dips, request identification of all possible sheep dip locations (see Section 4 and checklist Appendix 1) (return)
If the site was formerly a sheep farm, were sheep dips considered? (see Note 2)
If sheep dips were not considered, request identification of all possible sheep dip locations (see Section 4 and checklist Appendix 1) (return)
If sheep dips were considered, are all probable or actual dip locations identified? (see Note 3, and Section 3.4)
If all probably or actual dip locations were not considered or it is uncertain, request identification of all possible sheep dip locations (see Section 4 and checklist Appendix 1) (return)
If all probable or actual dip locations were considered, were any sheep dips identified?
If no sheep dips were identified, there are no further concerns regarding sheep dips.
If sheep dips were identified, see soil and water sampling information below.
|Soil and water sampling|| |
Appropriate chemicals identified and analysed? (see Note 4 and Section 2.3)
Results assessed against appropriate guideline values? (see Section 5.6 and Appendix 6)
Was adequate investigation sampling carried out?
If adequate investigation sampling was not carried out or it is uncertain, request additional investigations to characterise site (return)
If adequate investigation sampling was carried out, is there an adequate investigation report? (see Section 5.7)
If there is no adequate investigation report, request clarification of incomplete report sections (return)
If it is uncertain about the investigation report, seek independent review (see Note 6). Any issues raised by review?
If there were no issues raised by the review, proceed with application assigning controls as necessary
If there were issues raised, address issues raised and reassess application
If there is an adequate investigation report, has adequate management and/or remediation been proposed? (see Section 6)
If adequate management and/or remediation has been proposed proceed with application assigning controls as necessary.
If adequate management and/or remediation has not been proposed or it is uncertain, seek independent review (see note 6) Any issues raised by review?
If there are no issues raised by the review, proceed with application assigning controls as necessary
If issues were raised by the review, address issues raised and reassess application
1. Place a tick in the boxes as each section is completed.
2. It can be assumed that most sheep farms will have had one or more dip sites. Only very small farms would not have had their own dips. Those sites that have been subdivided off larger properties need to provide sufficient evidence that the subdivided property would not have had the dip located on it. A steep site is unlikely to bear a dip site and would usually be exempt from further investigation unless there is evidence that chemicals were poured down the hillside. Note the practice of directly spraying the flock with chemicals while held in the stock yards, which means that chemicals in soil from this source may not be at a recognised dip site.
3. Permanent dips are often associated with woolsheds and yards. A convenient water supply (eg, bore) could also be an indicator. The common discovery methods are:
- existing structures or parts thereof
- anecdotal information
- historical aerial photographs
- suspicious ground depressions
- analytical confirmation, such as water and soil sampling.
Note that as many methods as feasible should be employed, so that all current and former locations are identified. For instance, a dip structure may be found, but one of the other discovery methods may identify another former location.
4. Laboratory analysis is only required for the persistent chemicals most likely to be present. This will depend on the operating period of the dip and the concentration of chemicals that may inhibit bacterial breakdown. Therefore, the period(s) of use should be determined to justify the selection of analytes according to the table below.
Table 3: Typical period of use of sheep-dip chemicals of concern in New Zealand
Used at this site?
Typical period of use
Yes / No
Yes / No
| ||Yes / No|| |
| ||Yes / No|| |
| ||Yes / No|| |
| ||Yes / No|| |
| ||Yes / No|| |
| ||Yes / No|| |
| ||Yes / No|| |
Yes / No
Insect growth regulators
Yes / No
5. Sampling methodology should be adequate to characterise soils surrounding a dip site, and, if appropriate, groundwater and surface water within the vicinity of the dip(s), which may be pathways for run-off/flow from the dip and drip areas. Sample site locations should be recorded on a site plan. Identifiable sampling locations may include:
- soil beneath a dip bath and within the bath
- soil in the splash zone and scooping mound around a dip
- soil in any disposal/run-off areas where sludge/spent dipping fluid may have been disposed of and drained
- soil from yards where freshly dipped sheep were collected before further transport
- soil in the storage areas for chemicals, and beneath the woolshed
- water from one or more areas of the identified dip area
- water from one or more groundwater wells within approximately 200 m of the dip
- water and sediment from one or more areas of a seepage zone, a stream or foreshore.
6. The ground investigation should be appropriate for the site. The collection, storage and transport of samples should follow the recommendations in the Ministry for the Environment's Contaminated Land Management Guidelines No. 5 (2004a).
In the event that a report appears to be generally satisfactory but has some uncertainties of sufficient concern, independent advice should be sought from the regional council or a contaminated site consultant.
There will probably be times where an applicant has not provided sufficient information to satisfy council criteria. In such cases, it is assumed a council would request more information from the applicant or refer to council records. Local authorities may want to present the checklist contained in Appendix 1 to landowners with a suspected dip site on their property to help them prepare a resource consent application for a potential subdivision, or a change in land use.
Discharge consents may also be required by regional councils during redevelopment and for remediation measures (compare section 6.2).
Note that the consent process is only one way to manage risks from old sheep-dip sites, which relies on councils establishing if any disused sheep dips are present. The risks are then managed through a resource consent or building consent application. Another way would be for local authorities, in consultation with landowner groups, to identify critical geographic areas for attention; for example, where significant land-use changes are occurring, such as on urban fringes. Where a property does not trigger a resource consent process, it is the current landowner's responsibility to make sure the site does not pose any risk to people or the environment and to manage or remediate the site with expert assistance, if appropriate.
3.2 Information management
Territorial authorities and unitary authorities have duties under the Local Government Official Information and Meetings Act (section 44A) to provide information on the likely presence of hazardous contaminants on land in Land Information Memoranda (LIMs), and also to include information on the presence of hazardous contaminants on land in Project Information Memoranda (PIMs) under the Building Act 2004.
For subdivision, building or land-use consent applications it is important that the territorial authority has up-to-date information about the site history and any contamination. When territorial authorities assess proposed changes in land use, they must have regard to the effects of the land-use change on the environment (including people), and may seek advice from regional councils. Territorial authorities also monitor, report and often keep (or have access to) records relating to hazardous substances or contaminants within their district or city area. This may entail compiling a register of known sheep-dip sites and other contaminated sites within their area as this information becomes available, although it may be better to take a proactive approach (see box below).
The investigation of land for the purposes of identifying and monitoring contamination is a function of regional councils. This allows regional councils to investigate land where contamination is suspected, even if there is no actual discharge occurring, to see if the land meets the definition of contaminated land in the RMA (see Appendix 3). Most regional councils maintain databases of sites where hazardous substances have been stored or used, or where historical land uses could have caused contamination of the soil. Information about the sites, including whether contamination has been confirmed or not, is recorded on the database. Some city or district councils maintain their own databases, or the regional council may have agreements with them about access to the information on the database. It is recommended that records of sheep-dip sites be maintained on one master database to avoid inconsistencies between regional and territorial authorities.
Landowners have no duty to report on the contamination status of their land, or on the remediation measures they may have undertaken, if there are no off-site effects. However, if they are asked by a potential purchaser about any contamination issues on their land they have a duty to disclose any knowledge they have, and the purchaser may have the right to withdraw from the purchase agreement if the former owner failed to disclose that information.
Councils may choose to employ an active programme of locating the old sheep-dip sites in each district before knowledge of their whereabouts is progressively lost. This approach would effectively address both the acute toxicity risk to children on farms or lifestyle blocks and the need to identify old dip sites by the time a property is subdivided. It is much harder to address contamination issues after the subdivision has taken place. The identification and site investigation may be carried out as a joint initiative between the regional council and the territorial authority.
Detailed protocols for classifying contaminated sites and managing information can be found in Contaminated Land Management Guidelines No. 4: Classification and Information Management Protocols (Ministry for the Environment 2006). Council staff are advised to refer to these for further guidance.