Division of Spill Prevention and Response

Breadcrumbs

Tactic AM-4: Testing Soil and Water for Contaminants

Government agencies may require periodic laboratory analysis of soil and water during treatment and rehabilitation of a spill site (Fig. 129). This tactic describes procedures for sampling and analysis to measure contaminants in tundra soil, surface water, and in supra-permafrost water (i.e., subsurface water within the active layer of thawed soil). Sampling and analysis plans must be approved by the Alaska Department of Environmental Conservation (ADEC). Select laboratory analyses by referring to regulations used by ADEC (18 AAC 75.341, 345 and 18 AAC 70.020) to establish chemical-specific screening criteria and cleanup levels for soil and groundwater. Workers must comply with Occupational Safety and Health Administration regulations, which require special training for sampling hazardous substances.

Selection of Sample Sites

To allow testing for a correlation between analytical results and field indicators, collect analytical samples at the same locations where field indicators are monitored (Tactic AM-2) whenever possible. If samples for analytical analysis are collected at new locations, field indicator data should also be collected at these locations. Avoid collecting analytical samples from a location that has been disturbed by monitoring for field indicators.

The number of locations selected for sampling, and the frequency of sampling must be approved by agencies. An intensive treatment and monitoring program may require ongoing sampling (weekly to monthly), while a less intense program may require annual monitoring. Sampling is normally performed when the soil is thawed.

Preventing Cross-Contamination

Avoid cross-contamination of samples by using proper sample-handling techniques and decontamination practices. Work in pairs with one person labeling jars and writing field notes without handling contaminated material, while the other person collects samples and handles sampling equipment. Decontaminate sampling equipment before each sampling event to ensure collection of representative samples and to prevent cross-contamination. Use a laboratory-grade detergent and preferably hot potable water to clean sample equipment. Rinse with tap water followed by multiple rinses with de-ionized water.

Soil Sampling Procedures

A typical cross-section of tundra soil has two distinct layers differentiated by color and texture (Tactic P-2). The upper horizon consists of dark organic soils, usually with dense plant roots and is often smooth in texture. The lower, mineral horizon is usually sandy or silty in texture, and the color is often lighter, or gleyed (grey and/or blue).

Collect samples separately for the upper (organic) soil horizon and the lower (mineral) horizon. Stainless steel spoons, disposable sample scoops, shovels, and hand augers may be used to collect surface/near-surface samples.

Surface soil samples must be collected from freshly uncovered soil to minimize the loss of any volatile compounds, and transferred directly from the freshly uncovered soil to the laboratory-supplied sample container. If a sample is to be collected in a test pit that has been open for longer than one hour, a minimum of 3 inches of surface soil should be removed immediately before collection.

Surface Water Sampling Procedures

Collect samples of surface water by gently immersing a clean sample bottle in the body of water. Avoid disturbing sediments in the immediate vicinity of the collection point before sample collection.

Field measurements of water quality parameters may be recorded after sample collection, including:

  • Temperature
  • pH
  • Specific conductance (SC), which is calculated from electrical conductivity (EC)
  • Dissolved oxygen
  • Oxidation reduction (Redox) potential

Calibrate the instruments in the field before use.

Testing Surface Water for Salt Content during Flooding or Flushing

When treating a spill of a saline substance by flooding or flushing, use a hand-held field probe to monitor the EC of the water before and after it is applied to the tundra, to provide immediate confirmation that salts are being removed. EC values should decrease with successive flooding treatments as salts become diluted. However, when salts have penetrated into the soil, EC may increase temporarily when these salts are flushed out of the soil. If the soil is frozen, this increase may not occur until the soil thaws sufficiently to allow the salts to become mobile. Calibrate the conductivity meter before collecting data. Many conductivity probes automatically convert EC values to SC (EC standardized to 25oC) to allow comparison of measurements made at different temperatures. If necessary, manually convert EC readings to SC values. A variety of units are used for recording conductivity in water; the standard international unit is the Siemen (S). Conductivity meters usually display results in microSiemens/cm (µS/cm), or in milliSiemens (mS/cm). Another unit, the “mhos” is often used in the United States. Fortunately, 1 mhos = 1 S, and 1 µmhos/cm = 1µS/cm (see Tactic AM-5).

Procedures for Sampling Water from the Active Layer of Soil

Collecting samples of water below the tundra surface (i.e., in the active layer of thawed soil or supra-permafrost groundwater) requires the installation of monitoring wells (Fig. 129). Before each sampling event, a minimum of three to five well volumes of water should be purged from the well. This will remove any stagnant water in the well casing and ensure that the sample originates from the soil surrounding the well. Use a disposable bailer or a peristaltic pump to purge wells. Collect purged water in drums and dispose of it according to applicable regulatory guidelines.

Monitoring_groundwater_adjusted.jpg

Figure 129. Monitoring water in the active layer

Use a sterile, disposable bailer to collect water samples from wells. Immediately place water into sample containers and preserve as specified by the analytical laboratory.

Laboratory Analysis Plan

The type of substance spilled and the sample media dictate the analyses to be used. Laboratories will provide sample containers and specify required sample quantities. Table 12 provides examples of sampling and analysis parameters.

Spilled

Substances

Analysis

Matrix

EPA/ADEC

Method

Containers

(will vary with lab )

Preservation, Holding Time

Crude Oil,

Diesel,

Gasoline

Gasoline

Range

Organics

(GRO)

Water

AK 101

40-ml VOA, TLS lid

HCI to pH<2, Cool to 4oC, extract and analyze in 14 days

Soil

AK 101

4-oz Amber glass, teflon-lined septa (TLS) lid

Methanol, <25oC, extract and analyze in 28 days

Diesel Range

Organics

(DRO)

Water

AK 102

2-1L Glass Amber

pH<2 (HCI), 4o+2oC, 7 days to extract, analyze <40 days

Soil

AK 102

4-oz Amber glass, TLS lid

4o+2oC, 14 days to extract, analyze <40 days

Residual

Range

Organics

(RRO)

Water

No water method

--

Soil

AK 103

4-oz Amber glass, TLS lid

4o+2oC, 14 days to extract, analyze <40 days

Total

Polynuclear

Aromatic

Hydrocarbons (PAH)

Water

610, 625, 8021 B, 8260 C

40 ml VOA, TLS lid

pH<2 (HCI), 4o+2oC/14 days

Soil

8270, 8100,
or 8310

4-oz Amber glass, TLS lid

4o+2oC/14 days or per method requirements

Benzene,

Toluene,

Ethylbenzene,

and Xylenes (BTEX)

Water

8260M
(SIM)/602, 624

40-ml VOA, TLS lid

HCI pH<2, cool to 4oC, extract and analyze in 14 days

Soil

8260M/

8021 B/

6240/

AK 101

4-oz Amber glass, TLS lid

4o+2oC, extract and anlyze in 14 days or per method requirements

Glycol

Water

8015 M, 8015 B

40-ml VOA

4o+2oC/7 days or per method requirements

Soil

8015 M, 8015 B

4-oz jar

4o+2oC/7 days or per method requirements

Therminol

Water

8015 M, 8015 B

40-ml VOA

4o+2oC/7 days or per method requirements

Soil

8015 M, 8015 B

4-oz jar

4o+2oC/7 days or per method requirements

Methanol

Water

8015 M, 8015 B

40-ml VOA

4o+2oC/7 days or per method requirements

Soil

8015 M, 8015 B

4-oz jar

4o+2oC/7 days or per method requirements

Salinity

Water

SM-22520B

250-ml plastic

4o+2oC/14 days or per method requirements

Soil

SM-22520B

4-oz jar

4o+2oC/14 days or per method requirements

Table 12. Examples of sampling and analysis parameters


Updated: 12/20/2010