This handout discusses sampling techniques and presents photographs of sampling activities.

Surface soil samples are normally collected with a stainless steel trowel and homogenized in a stainless steel bowl. Surface soil samples are collected in the first foot of soil. Samples for volatile organic compounds (VOC) analyses are collected from 6-12 inches in depth to help prevent loss to air. Deeper soil samples (subsurface soil samples) are collected by direct push methods.

Geoprobe/Direct Push Operations

The geoprobe rig is a method for obtaining subsurface soil samples with a minimum of disturbance to the surrounding land. The rig can be mounted in the back of a pickup truck (see photo) or on a small ATV/4-wheeler vehicle for access to remote locations. Soil samples are collected in a disposable acetate (a non-reactive plastic material) sleeve lining the inside of a 4-foot long, 3-inch diameter metal pipe. The cutting shoe is placed over the end of the liner and screwed into the pipe and acts like a drill bit.

The pipe is then placed in the geoprobe unit and advanced by hydraulic pressure. The pipe is directly pushed into the ground until resistance is encountered. At that point, the geoprobe operator can use the unit to vibrate the pipe further into the soil through a series of rapid blows, much like a jackhammer.

Once the pipe has been advanced 4-ft (the length of the pipe), a pulling cap is placed on the end of the pipe. The geoprobe unit then hydraulically pulls the pipe back out. The cutting shoe is removed and the acetate liner, now full of soil, is pulled out of the pipe. This soil sample represents a column or core taken from that location (see photo). The geoprobe operator labels each end of the core with the depth of the top and bottom so that its orientation is known.

Deeper samples can be collected from each boring in 4-ft increments by adding drill rods to the top of the pipe and advancing further down each hole. These continuous cores can also be useful in assessing changes in the geology, as at the Rubble Pile, (SWMU 58). The geoprobe cores were used at that site to identify the depth of manmade fill and the beginning of native soil.

Sediment samples are collected from drainage pathways, impoundments, stream and pond beds to help assess if constituents of concern are migrating by surface water flow or impacting ecological receptors. Sediment samples can be collected with trowels and stainless steel bowls, or for samples in deeper water an Eckman sampler can be used. An Eckman sampler consists on an open container attached to an extendable rod. Once the sediment is reached, a lever closes a lid on the bottom of the container and the sediment sample can be retrieved. For deeper sediment samples a vibracore rig can be employed.

Vibracore sediment sampling techniques were employed in three lagoons at SWMU 31- Coal Ash Settling Lagoons to obtain virtually undisturbed sediment samples at depth (see photo). Vibratory coring uses a vibrating head assembly, which is clamped, onto an aluminum pipe. The head assembly vibrates the pipe into the sediment column until the desired depth is obtained. Once the desired depth is reached, water is poured into the standing pipe to create a vacuum effect inside the tube to aid in the full recovery of a sample. An example is putting your finger over a straw full of water. The top of the pipe is then capped off and the pipe is extracted with an electric winch. The pipe is then positioned horizontally where two lengthwise cuts are made with a power shear to open the core for sampling (see photo).

Surface water samples are normally collected straight into the jars in which they will be submitted for laboratory analysis. Surface water samples are normally collected at the same locations as sediment samples (see photo).