Sampling In the Vadose Zone

Zebra utilizes several types of samplers to meet the needs of any project.

Soil

The primary methods utilized by Zebra Environmental Corp. for soil sample acquisition are done by utilizing the Macro-Core Soil Sampler, LB sampler, and the Dual Tube Method. These sampling devices work best in medium- to fine-grained cohesive materials such as silty clay soils or sediments. The Core Samplers can also be used successfully in sampling medium-to coarse-grained sandy materials with some fine to medium gravels when core catchers are used.

Goundwater

The primary methods for groundwater sample acquisition are done by utilizing the SP-16 sampler or the Groundwater Profiler. The samples can be obtained in a number of ways. The most common method utilizes polyethylene or Teflon-tubing and a Tubing Bottom Check Valve. The check valve is attached to one end of the tubing and inserted down the casing until it is immersed in groundwater. Water is pumped through the tubing and to the ground surface by oscillating the tubing up and down. Collect the sample by withdrawing and draining the tubing.

Soil Gas

Direct sampling from the PRT using a gas chromatograph-compatible syringe used in conjunction with a mobile laboratory and gas chromatograph for immediate analysis of the collected samples.

Inline sampling using glass sampling bulbs or Tedlar bags. The sampling device is placed inline, between the PRT adapter and the vacuum/volume system. As the sampling system is purged, soil gas is trapped in the bulb or bag. These samples may be stored for limited periods of time and either analyzed on site or at an off-site laboratory.

Summa canisters, (pre-evacuated steel devices that are connected to the surface end to the PRT tubing), also provide another sampling option for soil gas. A valve on the canister is opened and the vacuum inside the canister pulls in soil gases from the sample interval. This system is expensive and is usually reserved for sending samples to an off-site laboratory for specialized analyses or quality control purposes.