We are looking for clarification on the selection of the extraction fluid for EPA Method 1312, SPLP. Written in the method is as follows:
Section 5.4.1 (Extraction fluid #1) The fluid is used to determine the leachability of soil from a site that is east of the Mississippi River, and the leachability of wastes and wastewaters.
Section 5.4.2 (Extraction fluid #2) The fluid is used to determine the leachability of soil from a site that is west of the Mississippi River. (Similar statements are made in section 7.1.4.)
1) Does the source (generation) location or disposal location determine whether or not the soil is east or west of the Mississippi River?
2) It appears that whether or not the sample is a waste (or wastewater) takes precedence over whether or not the waste (or wastewater) comes from east or west of the Mississippi River. Is this correct? (As an example, if the sample is a waste and comes from west of the Mississippi River, use fluid #1?) This seems to be confirmed in Section 2.2 “If the sample is a waste or wastewater, the extraction fluid employed is a pH 4.2 solution.”
3) What would the specific definition of a “waste” or “wastewater” be as used in the 1312 method (where this would take precedence over sample site for the selection of the extraction fluid)?
The purpose of SPLP is to determine the mobility of both organic and inorganic analytes from liquids, soils, and wastes, caused from the actions of precipitation. There is a very simplified assumption that precipitation east of the Mississippi is more acidic due to industrial activity and less buffering capacity of the soils there, versus west of the Mississippi. Therefore, the concern is leaching and mobilization of contaminants above the regulatory limits at the location of disposal where the contaminants would be released into the environment. Generally, the soil origin and potential disposal site would be exactly the same place or on the same side of the river, although there may be cases where this is not so (i.e., in states bordering the river).
On the second item, the fluid selection only applies if the sample is a soil. If it is a waste or solids from wastewater, the pH 4.2 fluid is used by default. No fluid is used if the sample has less than 0.5% solids, in which case the filtered liquid is considered the extract. (See section 2.1)
On the third item, there are many definitions as to what is a waste or wastewater. Rather than define those for the method, it is much simpler to just determine if the sample is a soil or not. If it is a soil, make the fluid selection. If it is not a soil, consider it a waste or wastewater and use the pH 4.2 fluid, except if the sample is <0.5% solids when no fluid is used.