Sampling and pre-treatment

Margareta Wahlström, VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, FINLAND.


Reliable mine waste characterization data are needed for choosing treatment and disposal options for waste and planning the closure of a waste facility. When available data on waste characteristics is insufficient for decisions and actions, sampling is required and a plan for sampling and testing needs to be developed. The base for a sampling activity is collection of existing background information (see also Overall guidance document CEN/TR 16376). A field visit will normally be part of developing a sampling plan with special focus on accessibility to the location (e.g. safety restrictions).
Many different aspects need to be taken into account when planning a sampling campaign. The key issue in sampling is the objective of the sampling (screening, comprehensive characterization or confirmation of a specific property). The sampling approach depends on the required reliability in sampling and also previous information about the variability in waste properties (waste heterogeneity) and previous information of potential critical properties linked to planned actions. The amount of samples to be taken depends on the heterogeneity of the waste to be sampled together with the objectives for the sampling (how reliable information is needed). Sample size depends both on the heterogeneity and requirements for testing. Sampling techniques depends beside the sample objective also on the waste property to be determined (e.g. for many geotechnical analyses special sampling equipment is necessary). During sampling and also pretreatment of samples (e.g. subsampling) it is important to have appropriate knowledge of sample requirements and the critical factors influencing the waste properties of interest in order to take measures to minimise changes in samples. Changes in sample properties may occur due to various environmental factors, e.g. oxidation, carbonation or due to sampling approach (e.g. loss of sample integrity in taking the sample).
In some cases sampling campaigns are conducted in two steps. The first sampling campaign is a screening of waste properties and the second sampling campaign more targeted to a specific area or property based on the results from the first sampling round.

Sampling standards

A specific sampling guideline for the characterization of waste from extractive industries has been developed (CEN/TR 16365). The guideline builds upon EN 14899, “Sampling of Waste Materials – Framework for the preparation and application of a Sampling Plan” and its supporting technical reports (see Table 1). The sampling guideline is focusing on the development of sampling plans but does also discuss some practical aspects such as sampling equipment, storage and transport. According to the sampling guideline a plan for characterization of extractive waste should normally cover the aspects listed in Table 2. Furthermore, ISO 10381-2 gives information on appropriate sampling techniques and equipment for different soil sampling situations and EN ISO 22475-1 on sampling methods particularly for geotechnical testing.

Taken into account the great variety of waste types, sampling situations and objectives, it is not possible to develop definitive instructions that cover all scenarios. Therefore the standards and guideline documents (see Table 1) discuss the basic considerations to be followed, and provides guidance on selection of sampling approaches that might be relevant to the three principle phases of a mine from exploration, operation to closure.
Table 1. Standards of relevance for mine waste sampling (Technical Committee CEN/TC 292)
Focus Standard number and name Applicability Comment
Characteristics of mine waste sampling CEN/TR 16365:2012: Characterization of waste – Sampling of waste from extractive industries The guidance is applicable for sampling during exploration phase, operation phase and closure. The report focuses mainly on sampling for geochemical rather than geotechnical requirements. Note! Sampling at closed sites, including abandoned historic mine-sites, may in some cases require specific approaches e.g. due to accessibility and limited background information. Complementary information to EN14899 and its supporting technical reports (CEN/TR 15310 package)
Sampling plan EN 14899: Characterization of waste – Sampling of waste materials – Framework for preparation of a sampling plan preparation General information The objective of the sampling plan is translated sampling steps into specific and concrete technical instructions.
Sampling principles CEN/TR 15310-1: Sampling of waste materials: Information on selection and application of criteria for sampling under various conditions General information Discussion on statistical principles in sampling and description of statistical tools for design of testing programmes
Sampling techniques CEN/TR 15310-2: Sampling of waste materials. Information on sampling techniques General information General description of sampling techniques for various wastes found in a variety of location
Sub-sampling CEN/TR 15310-3: Sampling of waste materials: Information on procedures for sub-sampling in the field General information Description of procedures for reducing size of the waste materials in field to aid practical transportation of a sample to the laboratory
Sample preparation and storage CEN/TR 15310-4: Sampling of waste materials: Information on procedures for sample package, storage, preservation, transport and delivery General information Description of procedures for packaging, preservation, short-term storage and transport
Sampling plans CEN/TR 15310-5: Sampling of waste materials. Guidance on the process of defining the sampling plan Note! Limited applicability of the practical examples. Examples are given in CEN/TR 16


Guidance in important steps in sampling including illustrative

examples on how to define technical goals


Geotechnical testing EN ISO 22475-1:2006, Geotechnical investigation and testing. Sampling methods and groundwater

measurements.  Part 1: Technical principles for execution (ISO 22475-1:2006)

Applicable for geotechnical investigations  
Soil sampling ISO 10381-2:2002, Soil quality. Sampling. Part 2: Guidance on sampling techniques General information  
Pre-treatment EN 15002: Characterization of waste – Preparation of test portions from the laboratory sample Applicable  
Pre-treatment ISO 11464: Soil quality – Pretreatment of samples for physico-chemical analysis Partly applicable, see comment Method is limited to particle size < 2 mm while > 2 mm material is not treated because for soil analysis only material < 2 mm is relevant. If this method should be applied to wastes the fraction > 2 mm has to be crushed and included in the sample.
Pre-treatment ISO 16720: Soil quality – Pretreatment of samples by freeze-drying for subsequent analysis See comment Method has limitations as water may not be fully removed, better applicable to very moist samples


Table 2: Key elements in a sampling plan(see further EN 14899 and CEN/TR 16365)

Aspect Explanation Aspect Explanation
Identification of stakeholders List with contact information of all stakeholders
Identify general objectives General objectives such as development of a cover structure for the closure of a waste facility, treatment technology for waste water management
Background information Information of the process type, waste types, known geology, mineralogy, previously performed characterization, site characteristics etc.
Specific objectives Detailed objectives such as prediction of drainage quality, ARD potential, mineralogy
Determine generic level Sampling for screening, detailed characterization, confirmation etc.
Identify constituents and analytical methods Elements/constituents of concern e.g. total metal content, pyrite content, and analytical methods to determine these constituents
Identify health and safety precautions Health and safety issues for the sampler and the storage and transport of the samples
Select sampling approach Judgmental, unbiased, etc.
Identify sampling techniques Sampling from drill core, auger, shovel etc.
Sub-sampling Splitting system of samples after collection for reduction of volume/mass
Sample preparation Drying, splitting for different analysis, storage requirements
Transport sample Transport system to the lab and transport documentation
Document sampling plan and produce instructions for the sampler Details on sampling procedure for the sampler
Produce a field sample record List of information to be included in the field sample record
Complete sample record and document changes List deviations to the sampling plan and reasons for the deviation



Technical Committee CEN/TC 292 2012. Characterization of waste – Overall guidance document for characterization of wastes from extractive industries. CEN/TR 16376:2012.