Surface Soil Sampling

Surface soil can be easily sampled to determine chemical variation across a scarred area. Care must be taken to collect representative samples and record the samples so that lab results can be used.

Soil Borings

Drilling into the soil to explore the subsurface and to obtain earth samples.

Soil Gas Surveys

Soil-gas surveys can be used to:

• identify contaminants and relative concentrations
  
• identify sources; indicate extent of contamination
  
• monitor the progress of cleanups
  
• guide placement of subsequent confirmatory samples (soil borings, monitoring wells)
  
• monitor at fixed vapor wells (long-term monitoring)
  
• detect leaks through use of tracer compounds

Selected Compounds Detectable in Soil Gases

• Aromatic hydrocarbons: Benzenes, toluene, xylenes, naphthalene
• Aliphatic hydrocarbons: C1-C10 (e.g., methane, butane, pentane, iso-octane cyclohexane)
• Mixtures: Gasoline, JP-4
• Chlorinated hydrocarbons: Chloromethanes (e.g., chloroform, carbon tetrachloride); chloroethanes;
• Chloroethenes (e.g., vinyl chloride, di-, tri-, and perchloroethene)
• Other: CO2, CS2, H2S, NOx, radon, mercury compounds

Subsurface Soil Sampling and Analysis

When collecting subsoil samples be careful not to contaminate them with scrapings from other soil layers. Because the chemical properties of soils vary dramatically with depth, even minor contamination of subsoil samples can make the interpretation of chemical results very difficult.

Determination of Extent of Contamination

Soil contamination is the occurrence of pollutants in soil above a certain level causing a deterioration or loss of one or more soil functions. Also, Soil Contamination can be considered as the presence of man-made chemicals or other alteration in the natural soil environment. This type of contamination typically arises from the rupture of underground storage tanks, application of pesticides, percolation of contaminated surface water to subsurface strata, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals. The occurrence of this phenomenon is correlated with the degree of industrialization and intensity of chemical usage.

Sources:
Soil Gas Measurement
Agriculture, Food & Forestry
Land Management & Natural Hazards Unit