NASM sampling for odour assessment
Sampling of the NASM for the odour assessment test is very important. The characteristics of the NASM may vary from the top to the bottom of the storage container or lagoon. Odour characteristics may also change depending on how long the NASM is stored. It is important to obtain a sample that is representative of the NASM that will be applied to land.
The sampling method used will depend on the odour assessment test used and must be included in the information package submitted to the Director.
7.1. Sampling liquid NASM
Liquid materials (<18 % solids) can pose special challenges in collecting representative samples. Most of the liquid materials considered for application to land are suspensions rather than true liquids, and tend to settle into layers of varying densities and nutrient content. Materials need to be sampled so that the sample represents the entire volume of the material. In most situations, the material will need to be agitated prior to application to produce a relatively uniform mixture. It is easiest to obtain a representative sample of the material in the tank or lagoon after it has been thoroughly agitated. A variety of sampling strategies for various storage configurations can be found in the Sampling and Analysis Protocol, dated July 25, 2012 and incorporated by reference into O. Reg. 267/03.
7.2. Sampling solid NASM
Representative samples of the solid NASM must be collected at varying depths within the pile or storage facility. Samples must be collected at a minimum of six different locations per composite sample. At each location, the surface material is removed to a minimum depth of 15 cm, exposing a minimum area of 25 cm2. A sample of approximately 400 ml should be removed at each location, and the six samples mixed in a clean plastic pail to produce a composite with a total volume that will be sufficient to permit the testing described in section 8.0 of this guide (i.e. the depth of NASM in the flux chamber must match the depth of NASM applied to the land surface). Mixing is done manually with the same sampling shovel, in such a way as to slice the larger chunks and mix thoroughly. The composite (mixed grab) samples in the pail are then poured into a clean plastic high density polyethylene (HDPE with recycling symbol '2') container with an airtight lid. About 3 cm of air space should be allowed in the container for expansion caused by the release of gas from the material. The lid must be sealed securely to prevent gas leakage in or out.