Contaminated Land
Investigations + Testing

A contamination investigation usually occurs in one of two forms: a Preliminary Site Investigation (PSI) with desktop assessments and a site walkover to determine the likelihood of contamination being present on the site, or a more comprehensive Detailed Site Investigation (DSI) with soil sampling and laboratory testing to determine the what, where and how much contamination exists on the site.

We generally recommend getting a DSI if historic aerial photography of the site shows potentially contaminating activities occuring on the site (or if identified by council or planning consultants), rather than paying for both and taking the time to prepare both reports. Our team will check aerial photography during the quoting process to let you know if you'll need a PSI to assess the likelihood of contamination depending on your site.

Both stages must be prepared or certified by a Suitably Qualified and Experienced Practitioner (SQEP) under the National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health (NESCS). Our team is suitably qualified and ready to help you meet your requirements.

While these are two common types of investigationsneeded to support proposed development, we also provide a range of assessmentsthat can be tailored to suit your needs. These include due diligence assessmentfor sellers and prospective buyers, simple soil testingassessments for disposal classification, and site investigation reports.

You'll likely need an investigation if your site has, or may have had, a Hazardous Activities and Industries List (HAIL) activity on it, and you're planning subdivision, earthworks, removing or replacing a fuel storage system, or a change of land use.

HAIL activities include things like bulk fuel storage, timber treatment, vehicle maintenance and dismantling operations, and orchards with a history of pesticide use, or the presence of fill material of unknown origin among others listed by the Ministry for the Environment. If any of these have happened on your site, an investigation is likely required under the National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health (NESCS).

Not sure if your site's history counts? Get in touch and we'll check it for you.

As early as possible, ideally before you've committed to a purchase price or a construction timeline.

A PSI or DSI carried out early gives you real information to factor into due diligence, budgeting, and negotiation on a sale. If you're already committed to a project, the next best time is before lodging a resource consent application or starting earthworks. If a consent is lodged without an investigation, the council may flag this and send a Section 92 RFI requesting that a PSI/DSI is completed, potentially causing significant delays in the resource consent process.

Investigating early means any findings can be designed around and added to the programme ahead of time, rather than turning up as a surprise once machinery is already on-site.

A PSI reviews a site's history through various sources, such as council records, historical aerial photography and title searches, to determine whether a HAIL activity has occurred and how likely contamination is. It also involves a site walkover from our team to perform small on-site checks for any potential contaminants.

A DSI goes further. We collect soil (and sometimes groundwater) samples and test them at a nationally accredited laboratory. Results are compared against the relevant soil contaminant standards for human health and the environment, and used to build a conceptual site model in line with Contaminated Land Management Guideline No. 5, giving a reliable picture of what's in the ground.

In terms of results, a PSI tells you the history of the site, whether current and former site uses could have caused contamination is likely, and the potential risk to site users and the environment, as well as any general considerations for future land development. A DSI does this, but will also tell you the extent, level and type of contamination present, and will evaluate the potential impacts on site users and the environment. We will also assess what likely types of resource consent will be required to support the proposed works.

Importantly, if a HAIL activity is (or is more than likely) present onsite, in most instances a DSI will be required under the National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health (NESCS), prior to commencing earthworks or development.

We generally recommend getting a DSI if historic aerial photography of the site shows potentially contaminating activities occuring on the site, rather than paying for both and taking the time to prepare both reports. Our team will check aerial photography during the quoting process to let you know if you'll need a PSI to assess the likelihood of contamination depending on your site.

It depends on your site's history, size, land use, and what the PSI finds.

A straightforward PSI on a small site with clear records costs less than a DSI on a larger or more complex site needing extensive sampling and lab analysis. Because of this variation, your best bet is to send us some background on your project and we'll give you a clear quote before any work starts.

We'll let you know if we think you need a PSI for your project, but generally it's more cost effective to go straight into a Detailed Site Investigation (DSI) based on the information we can find during the quoting process, to save you the hassle of paying for two reports.

We can usually begin the investigation within a week, with testing and reviews taking longer depending on the size and complexity of the site. All up, this process can take a few weeks to a month or two, so it's best to get one of our experts in as early as you can.

If you have particular requirements for timelines, we can work with you to figure out a solution.