PURPOSE: Step 5: Post Decontamination Assessment is required to verify the effectiveness of the decontamination works, and independently assess all works have been completed in compliance with the New Zealand Standard NZS 8510:2017. This is necessary in order for clearance documentation to be issued by the decontamination company.
Sample Collection and Sample plan MUST be signed off by IANZ Accredited Sampler for clearance to be issued.
A sample plan/quote must be submitted to the client for acceptance before the commencement of the assessment
Properties will need to meet the requirements of Step 3: Detailed Site Assessment and Step 5: Post Decontamination Assessment criteria in order for property clearance to be issued.
Laboratory Composite Within a Single Area
If all potential maximum concentrations DO NOT exceed (1.5µg/100cm²), Property Clearance Documentation will be issued.
If “Potential Maximum” traces within a single area are above the limits of the Standard (1.5µg/100cm²) the following options apply:
Individual Analysis of some or all of the composite
Return to Step 4 (Further Decontamination)
WARNING: Employing a sampling company that is not IANZ Accredited for Post Decontamination Assessments, means the final clearance documentation DOES NOT MEET THE REQUIREMENTS OF NZS 8510:2017.
Failure to meet these requirements may result in a requirement to re-test and re-decontaminate, resulting in additional work and expense. If Property Clearance Documentation is not correctly obtained, the contamination may remain on the LIM.
You are at Step Five of the Methamphetamine Assessment Ladder
To review the Steps of the Methamphetamine Assessment Ladder - Click here
A sampling plan / quote is compiled by an IANZ Accredited Sampler, in order to compile a sampling plan sufficient for property clearance. Areas are assessed as per NZS 8510:2017 Section 3.3 and Section 5 criteria. Areas that meet these requirements are deemed as successfully decontaminated.
This assessment gathers relevant information such as room size, and materials. Once the sampling plan has been accepted by the client, samples are collected from necessary areas that have not met the requirements of the New Zealand Standard and then analysed and reported on.
Post Decontamination Assessment Acceptable Methodologies
NZS 8510:2017 allows two types of analysis for a post decontamination assessment. these are as follows:
Discreet swab individual analysis
Area Specific Composite Analysis
As with anything, there are advantages and disadvantages to both methodologies. Before making a decision on what type of analysis you require, it's important to understand the benefits of each in order to make an informed decision.
Discreet Swab Individual Analysis
Discreet samples are a single wipe collected from a single templated area and submitted to an IANZ accredited laboratory for analysis as a unique location.
Once analysed, the IANZ Accredited laboratory will report to the IANZ Accredited sampler, the amount of methamphetamine recovered from the templated surface. This represents the amount of methamphetamine for that 100cm2 templated area.
Individual results - giving full picture for the surface swabbed
Expensive - NZS 8510 requires 1 x sample to be collected per 10m2 of floor space, and all materials within an area must be considered. This means in some cases 5-6 samples per room is necessary depending on the materials. With this methodology, you are paying the laboratory for individual analysis of each of those 5-6 samples. Costs can increase significantly, depending on the amount of materials in each room, the size of the room, and the amount of areas requiring sampling in order for clearance to be issued.
Area Specific Laboratory Composite Analysis
Discreet samples are collected as per NZS 8510:2017 requirements. For property clearance each specific area requires 1 x sample per 10m2 of floor space, and each material within the area is required to be considered. The difference with this methodology is that each sample is submitted to the laboratory as an individual, however the laboratory is requested to perform a composite analysis of each area. The laboratory extract even amounts from each sample from within the area identified, and create a new sample called the "laboratory composite" for that area. Below is an image that illustrates how a laboratory composite analysis is put together for three areas. The laboratory can report an average of methamphetamine found within the laboratory composite, and the "potential maximum" (the total) of all methamphetamine recovered from the laboratory composite. The potential maximum assumes that all methamphetamine recovered is from 1 swab within the composite. NZS 8510:2017 requires all potential maximum concentrations within an individual to NOT exceed 1.5µg/100cm².
Cost Effective - You are effectively only paying for one analysis per area, therefore saving laboratory analysis fees.
10 for the price of 1 - The Laboratory can include unto 10 swabs within a composite.
The laboratory hold the samples for further individual analysis if required. If the potential maximum does exceed1.5µg/100cm2, the decision can be made to either;
Apply a further decontamination treatment to the area
Individually analyse samples within the laboratory composite, (this can be done all at once, or one at a time) this decision can be made in consultation with the decontamination contractor, depending on how close to 1.5µg/100cm² the POTENTIAL MAXIMUM is.
Potential Maximum result - If the potential maximum result exceeds 1.5µg/100cm2, it is inconclusive as to which material from the area the contamination is from. As the laboratory are adding each sample within to the composite, the more samples within the composite, the higher the risk of the calculation exceeding 1.5µg/100cm².
SEE BELOW: ILLUSTRATION ON HOW A LABORATORY IS MADE UP FOR THE BATHROOM, LIVING AREA, AND BEDROOM 1
Example Property Price Comparison
Below is a sample plan from an example property, the left hand table shows the areas requiring samples as per NZS8510 requirements. The right table shows the price comparison between the two types of analysis.
Is there any contamination left after cleaning?
Following the clean up, this test tells us if any meth contamination remains after the Step 4: Decontamination process is complete.
The test adheres to the NZS 8510:2017 Standards and provides a numerical value to indicate hazardous levels contained within your property.
Further Lab Based Samples are taken, ensuring the property is now free of methamphetamine contamination and levels are below the NZS 8510:2017 Standards.
This test is conducted in conjunction with the meth-testing and decontamination standard NZS 8510:2017. We use IANZ accredited labs to test the samples.
With this test you receive a comprehensive Post-Decontamination Assessment Report stating any remaining levels of toxic contamination in each room and recommendations on any further remediation (if any) that may be required for the property.
This report can then be passed on to the previously used or a new clean up/decontamination companies who will provide a quote and scope of work for the process.
Sampling and/or assessment costs vary based on the number of rooms needing to be tested, we are happy to discuss and quote on a case by case basis.
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