A day in the life of a tip rat
4th February 2003
Our role in the field is to collect soil samples at the abandoned waste refuse site, in order to understand the contaminants present at the site, allowing for appropriate disposal once the site is excavated. Our day of sampling involves walking through the snow to the site about 1 km from station. The site is in a valley down by a bay providing a scenic location out of sight of station. We occasionally get visits from small groups of Adelie penguins who come out on the sea ice about 500 m away. They are generally curious and waddle over to us to see what we are doing before returning back to the water.
When we go out sampling, our equipment includes a shovel; plastic snap lock bags; barcode labels; a field note book; protective suit and masks; a digital camera; sample markers; a GPS and tape measure; and other comforts against the weather such as extra clothing, sunscreen, spare gloves, chocolate, and drinks.
When we arrive on site, we wear protective 'barrier suits' to ensure that we do not come into contact with any contaminants at the site. These suits cover the whole body except for the face. Over our nose and mouth we wear a mask that filters out contaminants and protects against other nasties that may be there, such as asbestos fibres.
The sampling is conducted in a grid across parts of the site that are exposed through the snow. There is additional fine scale sampling in areas of greater contamination. Sampling involves taking a shovel and collecting between 2 – 4 kg of soil, sorting through the soil to remove pieces of rubbish and metal, and placing the soil in an A3 plastic snap-lock bag. We then stick a barcode label on the bag, and take a digital photograph of the sample site. We also take a GPS location reading to determine the exact location of the sample, and place a marker there so that we can find the site again if needed. We then start recording information.
Part of the quality control of our sampling includes the collection of 'chain-of-custody' information. This is the process that details the transfer of samples from collection in the field, to arrival and analysis in the laboratory, storage in between times, and then final disposal. Several transfers may take place in this chain, so information recorded includes:
- a sample identification number
- name of person collecting the sample
- name of custodian of the sample
- the number of the field notebook that information is recorded into
- time and date samples are taken
- time and date samples are received by the lab
- the sample collection location
- the height of the sample relative to datum
- the sample type
- the depth the sample is taken
- the container type the sample is stored in
- the sample weight
- preservation procedures
- hazardous waste codes
- any other comments such as handling procedures, or expectations of heavy contamination.
This chain-of-custody information is entered into a spreadsheet on return from the field. All information about a sample can be accessed through each sample's unique identification number. This number is allocated by printing a series of barcodes onto labels, and placing a label on the sample container, at the time the sample is taken, providing a sample tracking system. Whenever the sample moves location, e.g. from a lab to a storage freezer, we simply scan the barcode to register the move in our spreadsheet.
After the sample is taken in the field it is sent to the onsite lab. This is a converted shipping container with all the required equipment. The sample is dried in an oven, and weighed. It is then sieved to discard any rock or pieces of rubbish that are still present, and crushed ready for x-ray analysis. A chemical analysis of the sample provides data on the soil parameters; and total concentrations and leachable concentrations of contaminants, including metals/metaloids and organics. This data is stored on the spreadsheet and is also accessible through the sample identification number and tracking system.
Next year, we plan to have hand held computers to enable the information to be directly input when in the field. The cold weather here reduces battery life, and tends to cause difficulties with using computers in the field, but we hope to solve these problems. We will also be working on site with a Geographical Information System (GIS), to visualise the contaminant map and manage further work at the site. Using the tracking system will allow us to interrogate data for each sample, and link it to contaminant layers or plumes on the GIS.