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soils covering the range of the parameter of interest should be included in the

experimental testing.

Table 1. Guidance for selection of soil samples a

pH range (in 0.01 M CaCl 2 )

Organic carbon content (%)

Clay content (%)

Soil type

Soil texture

1 2 3 4 5 6 7

4.5-5.5

1.0-2.0 3.5-5.0 1.5-3.0 3.0-4.0

65-80 20-40 15-25 15-30

Clay

>7.5

Clay loam Silt loam

5.5-7.0 4.0-5.5 <4.0-6.0

Loam

< 0.5-1.5 < 0.5-1.0

< 10-15

Loamy sand

>7.0 <4.5

40-65

Clay loam/clay Sand/loamy sand

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> 10

< 10

a From OECD Guideline 106 (9).

Site-specific soil testing may be required for a site survey, assessment of 260 decontamination or remediation effectiveness, or the validation of a method for 261 assessment of decontamination and remediation efforts. In cases such as these, a target 262 testing grid should be laid out over the test area and a soil sample from each grid area 263 should be collected (see Section 8.4). For decontamination and remediation assessments, 264 soil samples should be collected before, during and after the controlled experimental 265 release of agent or experimental decontamination treatment. Even on a small test grid, 266 soil types and characteristics can vary. A soil survey or online tools like the web soil 267 survey (Table 2) should be consulted to determine differing soil types and their expected 268 locations. Documentation of soil characterization tests as well as experimental results 269 from the site should be archived in a database for future reference.

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