---
kind: "section"
citation: "40 C.F.R. § 761.350"
title: "40"
number: "761.350"
heading: "Subsampling from composite samples."
url: "https://uscodex.org/cfr/40/761.350"
---

# §761.350. Subsampling from composite samples.

- (a) **Preparing the composite.** Composite the samples (eight from a flattened pile; eight or more from a conical pile; eight from waste that is continuously generated) and select a 19-liter subsample for shipment to the chemical extraction and analysis laboratory for further subsampling. There are two options for the preparation of the composite:
  - (1) **Option one.** Place all of the contents of all 19-liter samples that you collected into a 209 liter (55 gallon) drum or similar sized, cylinder-shaped container. Completely close the container, and roll it 10 or more complete revolutions to mix the contents.
  - (2) **Option two.** Add the 19-liter samples one at a time to a 209 liter (55 gallon) drum. Between the addition of each 19-liter sample, stir the composite using a broom handle or similar long, narrow, sturdy rod that reaches the bottom of the container. Stir the mixture for a minimum of 10 complete revolutions of the stirring instrument around the container at a distance approximately half way between the outside and center of the container.
- (b) **Selecting a 19-liter subsample from the composite.** Once the composite is mixed, pour the mixture of waste out on a plastic sheet and either divide it into 19-liter size piles or make one large pile.
  - (1) From 19-liter sized piles, use a random number generator or random number table to select one of the piles.
  - (2) **From one large pile, flatten the pile to a depth of 30 cm and divide it into 4 quarters of equal size.** Use a random number generator or random number table to select one quarter of the pile. Further divide the selected quarter pile into 19-liter portions and use a random number generator or random number table to select one 19-liter portion. A square having a 25 cm side or a circle having a diameter of approximately 28.5 cm when projected downwards 30 cm equals approximately 19 liters.
- (c) **Transferring the sample to the analytical laboratory.** Place the selected 19-liter subsample in a container, approved for shipment of the sample, to the chemical extraction and analysis laboratory, for the next step in sample selection in accordance with [§ 761.353](/cfr/40/761.353.md).

## Notes

### Source

Source: 63 FR 35469, June 29, 1998, unless otherwise noted.

### Authority

Authority: 15 U.S.C. 2605, 2607, 2611, 2614, and 2616 and 42 U.S.C. 6939g.

### Source

Source: 43 FR 7156, Feb. 17, 1978, unless otherwise noted.