A Simple Field Leach Test to Assess Potential Leaching of 

Soluble Constituents from Mine Wastes, Soils, and Other 

Geologic Materials

Introduction

Rainwater- or snowmelt-induced 

leaching of major elements, trace 

elements, and acid from mine wastes 

or naturally mineralized areas and the 

effects of the resulting runoff on 

adjacent streams (fig. 1) are common 

environmental concerns. Another 

concern is the direct or indirect uptake 

of potentially toxic metals from 

these leachates into the food chain 

(fig. 2).

Many other geogenic materials 

(for example, soils, mineralized rocks, 

dusts, volcanic ash, and forest-fire ash) 

may also react chemically with water 

to produce leachates with increased 

concentrations of major and trace 

elements and altered pH. Because of 

this potential, it is important to have a 

tool that will aid the environmental 

scientist in quantifying and understanding the leachability of geologically 

derived material and the chemical 

reactions that can occur when the 

material comes into contact with 

water. 

Traditionally, laboratory leach 

studies have been a useful way to 

assess the potential effects from the 

leaching of materials. However, the 

leach tests most commonly used are 

complicated and time consuming and 

require specialized equipment. In light 

of these factors, the U.S. Geological 

Survey (USGS) has developed a fast 

(5-minute), relatively simple and 

cost-effective leach test. The USGS 

Field Leach Test (FLT) can easily be 

performed in the laboratory or onsite 

to effectively simulate the chemical 

reactions that occur when geologic 

materials are leached by water. 

Figure 1. Leached constituents from mineralized areas may affect local streams and biota.

USGS Fact Sheet 2005-3100

2005

U.S. Department of the Interior

U.S. Geological Survey

*ÀÌi`ÊÊÀiVÞVi`Ê«>«iÀ

Figure 2. Mountain goats drink rainfall-induced leachate at a historical mine dump in 

Colorado.
Development of the 

USGS Field Leach Test

The USGS FLT is a modification 

of a leach test developed by Hageman 

and Briggs (2000). The method was 

originally developed to quickly assess 

and predict metals and acid release 

from historical metal mine dumps. 

The element concentration trends 

(geochemical signatures) of the leachates determined by this test were used 

to rank and prioritize the waste piles 

for cleanup. 

Since its inception, use of the USGS 

FLT has increased, and the test is now 

used to predict or characterize the potential for metals and acid release from a 

diverse variety of geologic materials.

As part of developing the FLT, 

extensive research and comparative studies 

were done using many other types of leach 

tests. After the initial tests, we focused 

our comparison on studies between the 

USGS FLT and the EPA Method 1312, 

Synthetic Precipitation Leaching Procedure (SPLP) (U.S. Environmental Protection Agency, 2002). This comparison 

was emphasized because the SPLP was 

one of the leach tests most commonly 

used for leaching studies of mine wastes. 

Complete results of this study are given 

in Hageman and Briggs (2000). 

Comparison of the two procedures 

showed that the 5-minute USGS FLT 

produced leachate geochemical signatures and element-concentration trends 

that are similar to those produced by the 

18-hour EPA (SPLP) test. As a result 

of these studies, the USGS adopted the 

USGS FLT as a screening procedure that 

can be used as a surrogate for the EPA 

(SPLP) procedure. 

Figure 3. Geoscientist 

using the USGS FLT 

to leach a soil sample 

onsite.

Figure 4. Geoscientist using the USGS 

FLT to sieve and mix a sample for leaching 

onsite. 

0

2

4

6

8

10

12

Miningaffected

wetland

sediment

Mine waste

dump

Mancos soil Iraq soil Mount. St.

Helens ash

Windblown

dust from

dry lakebed

Agricultural

soil

World Trade

Center dust

Forest-fire

burned soil

SAMPLE

pH (STANDARD UNITS)

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

SPECIFIC CONDUCTANCE (MICROSIEMENS PER 

CENTIMETER)

pH Specific conductance

Figure 5. Leachate pH and specific-conductance data for a variety of samples leached using the USGS FLT. 
Table 1. Leaching parameters of the USGS FLT and the modified EPA Method 1312 (SPLP).

[<, less than; ~, approximately]

Parameter Modified EPA 1312 (SPLP) USGS FLT

Test type batch batch

Leachate to solid ratio 20:1 20:1

Leachate composition 60/40 H2SO4/HNO3 deionized water

Leachate pH 4.2 (for mine wastes) ~ 5.7

Particle size used < 1 centimeter < 2 millimeters

Sample mass 100.0 grams 50.0 grams

Duration of agitation 18 hours 5 minutes

Agitation method end-over-end rotary hand shaken

Filtration positive pressure syringe

Filter type borosilicate glass fiber nitrocellulose

Filter pore size 0.70 micrometer 0.45 micrometer

A complete listing of the parameters of 

these two procedures is given in table 1.

Finally, the USGS FLT offers the 

advantage of convenience. It can easily 

be performed onsite (fig. 3) or in the 

laboratory with equipment and reagents 

that are readily available and can be 

taken to the field in the back of a vehicle 

(fig. 4). Onsite leaching requires only 

the return of the preserved filtrate to the 

laboratory for analyses. In contrast, the 

EPA (SPLP) procedure requires specific, 

costly equipment and must be performed 

in the laboratory. 

Some of the Studies That 

Have Used the USGS FLT

In addition to studies of metal mine 

wastes (see, for example, Hageman, 2004), 

the USGS FLT has been used extensively 

for a variety of other applications, including 

environmental studies of the World Trade 

Center area after the September 11, 2001, 

attack (Clark and others, 2001; Plumlee 

and others, 2005); studies of the effects of 

surface applications of biosolids on soil, 

crops, ground water, and streambed sediment (Yager and others, 2004); as well as 

leach studies of mine dump cores, naturally 

mineralized soils, forest-fire burned soils, 

dried chemical slurries (used to fight forest 

fires), various types of eolian dusts, volcanic ash, and dried stream and wetland 

sediments. Examples of some of the 

leachate geochemical data produced from 

these studies are given in figures 5 and 6.

Over time, these studies have 

shown the USGS FLT to be effective 

as a quick and inexpensive method to 

characterize chemical reactivity and 

identify the water-soluble fraction of 

very diverse geologic sample matrices. 

An important feature of the USGS FLT 

procedure is that it was designed to use 

the same extraction ratio (20 parts leachate 

to 1 part solid) as the EPA (SPLP) leach test. 

Use of the 20:1 ratio ensures that the soluble 

components of the sample can be taken into 

solution without exceeding saturation limits 

and allows results produced using the USGS 

FLT to be compared directly with other 

leaching studies that have used the EPA 

(SPLP). It also ensures that the FLT provides 

sufficient sample to obtain all desired 

measurements and elemental analyses. 

0.001

0.010

0.100

1.000

10.000

100.000

1,000.000

10,000.000

100,000.000

Aluminum Cadmium Copper Iron Lead Manganese Nickel Zinc

ELEMENT

CONCENTRATION (MICROGRAMS PER LITER)

Mining-affected wetland sediment Mine waste dump

Mancos soil Iraq soil 

Mount St. Helens ash Windblown dust from dry lakebed

Agricultural soil after biosolids application World Trade Center dust

Forest-fire burned soil

Figure 6. Selected leachate trace-element signatures (ICP–MS) for a variety of samples leached using the USGS FLT. 
Procedure for Using the 

USGS Field Leach Test

The first step in the USGS FLT is 

to collect a representative sample. After 

collection, the sample is air dried, if 

necessary, and dry sieved as desired (less 

than 2 millimeters for most samples). 

Some samples do not need to be sieved 

(for example, dusts).

To leach, 50.0 grams of prepared 

sample is weighed into a 1-liter (L) plastic 

bottle. Approximately 1.0 L deionized 

water is added slowly so that no dust is 

lost. (Depending upon the amount of 

solid material available, other leachate 

volumes can be used as long as the 20:1 

water-to-solid ratio is maintained.) The 

bottle is capped and vigorously hand 

shaken for 5 minutes. The contents are 

then allowed to settle for approximately 

10 minutes. After settling, subsamples 

of the leachate are measured for pH, 

specific conductance, and other 

parameters. A portion of leachate is 

filtered using a 60-cc (cubic centimeter) 

syringe and a 0.45-micrometer pore-size 

nitrocellulose filter. If filtration is 

difficult, a 0.70-micrometer glass fiber 

prefilter can be used in conjunction with 

the 0.45-micrometer filter in a serial 

manner. Subsamples of the filtrate are 

collected and preserved for analysis. 

Conclusion

The USGS FLT has proven to be 

a valuable tool for a diverse group of 

investigators including Federal, State, and 

other governmental agencies, environmental 

professionals, and academia. 

The FLT has been used both 

onsite and in the laboratory and has 

proven effective for the characterization 

of diverse geologic and environmental 

materials for a variety of geochemical, 

environmental, and toxicological 

investigations. 

Leachate geochemical signatures 

produced using this test have proven 

to be a critical and integral part of 

these diverse investigations.

References Cited

Clark, Roger N., Green, Robert O., 

Swayze, Gregg A., Meeker, Greg, 

Sutley, Steve, and others, 2001, Environmental studies of the World Trade 

Center area after the September 11, 

2001 attack: U.S. Geological Survey 

Open-File Report 01–0429. 

Hageman, Philip L., 2004, Use of 

short-term (5-minute) and long-term 

(18-hour) leaching tests to characterize, fingerprint, and rank mine waste 

material from historical mines in the 

Deer Creek, Snake River, and Clear 

Creek watersheds in and around the 

Montezuma Mining District, Colorado: 

U.S. Geological Survey Scientific 

Investigations Report 2004 –5104, 41 p.

Hageman, Philip L., and Briggs, Paul H., 

2000, A simple field leach for rapid 

screening and qualitative characterization 

of mine waste material on abandoned 

mine lands, in ICARD 2000, Proceedings 

from the Fifth International Conference 

on Acid Rock Drainage, Denver, Colorado, 

May 21–24, 2000: Society for Mining, 

Metallurgy, and Exploration Inc., 

p. 1463–1475.

Plumlee, G.S., Hageman, P.L., 

Lamothe, P.J., Ziegler, T.L., Meeker, 

G.P., Brownfield, I., Adams, M., 

Swayze, G.A., Hoefen, T., Taggart, 

J.E., Clark, R.N., Wilson, S., and 

Sutley, S., 2005, Inorganic chemical 

composition and chemical reactivity 

of settled dust generated by the World 

Trade Center building collapse, in

Urban aerosols and their impacts—

Lessons learned from the World Trade 

Center tragedy: American Chemical 

Society Special Publication, 

p. 238–276.

U.S. Environmental Protection Agency, 

2002, Test methods for evaluating 

solid wastes, physical and 

chemical methods: http://www.epa.

gov/epaoswer/hazwaste/test/sw846.

htm, accessed 07/25/2005.

Yager, Tracy J.B., Smith, David B., 

and Crock, James G., 2004, 

Effects of surface applications of 

biosolids on soil, crops, ground 

water, and streambed sediment near 

Deer Trail, Colorado, 1999–2003: 

U.S. Geological Survey Scientific 

Investigations Report 2004–5289, 

98 p.

For additional information on any aspect 

of this method, please contact:

Philip L. Hageman

U.S. Geological Survey

Bldg. 20 MS 964 DFC 

Denver, Colorado USA

80225-0046

Telephone: (303) 236-2494

Fax: (303) 23­­­6­­­­­­-3200

Email: phageman@usgs.gov