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Hazardous Material Sampling Part 2

Soil Sampling

Soil samples may be collected using a variety of methods and equipment. The methods and equipment used are dependent on the depth of the desired sample, the type of soil, and whether the sample is required to be from disturbed or undisturbed soil. Once collected, soil samples should be kept at their in-ground temperature or lower. Refrigeration at 4°C with a minimal holding time is the best approach. Samples should also be protected from direct light. The two primary problems associated with soil sampling involve cross-contamination of samples and improper sample collection. Therefore, these areas should be addressed in the sampling plan. Cross-contamination problems can be eliminated or minimized through the use of dedicated (i.e., assigned only to that purpose) sampling equipment. If this is not possible, care should be taken to properly decontaminate equipment. Adhering to proper SOPs can reduce errors due to improper collection. online hazwoper training

Surface Soil Samples

Surface material for HAZWOPER work can be removed to the required depth using spades, shovels, and scoops. Next, a stainless steel scoop, plastic spoon, or trowel is used to remove and discard a thin layer of soil from the area that came into contact with the spade. Most soil types can then be sampled using a stainless steel scoop or plastic spoon. A flat, pointed mason trowel may be used to cut a block of soil when undisturbed profiles are required. One should avoid the use of equipment that is plated with chrome or other materials. online hazwoper training

Soil Sampling at Given Depths

Soil samples at certain depths can be taken with various sampling devices, such as a split spoon sampler, a trier, and an auger. The method and equipment used are dependent on the type of soil and the type of sample required.

If the soil is not hard and rocky, an auger may be used to bore a hole to a desired sampling depth. If satisfactory, a sample can be collected directly from the auger. If a core sample is needed, the auger tip is replaced with a thin-wall tube sampler. The device is then carefully lowered down the borehole and driven into the soil. Once it is withdrawn, the core sample can be collected. Several types of augers are available.

Bucket Augers
Bucket augers are better for direct sample recovery since they provide a large volume of sample in a short time.

Continuous Flight Augers
When continuous flight augers are used, the sample can be collected directly from the flights, which are usually at five foot intervals. The continuous flight augers for HAZWOPER work are satisfactory for use when a composite of the complete soil column is desired.

Post Hole Augers
Post hole augers have limited use for sample collection.

Shallow soil samples can be taken using a trier. The trier must be inserted at an angle to minimize sample spillage. The trier is rotated once or twice to cut a core of undisturbed soil. It is then slowly withdrawn with the slot facing upward.

Split Spoon Sampler
For undisturbed soil cores 18 to 24 inches in length, a split spoon sampler is used. It may be used on the soil surface but is generally used with a power-operated drill rig. The split spoon sampler can therefore be used in a wide variety of soil types and at greater depths than other types of equipment.

When a detailed examination of soil characteristics is required, it may be necessary to excavate a test pit or trench using a backhoe. However, because of the relatively high cost of the backhoe operation, this is the least cost effective sampling method.

Surface Water Sampling

When sampling surface water at shallow depths near the edge of the body of water, a stainless steel beaker or scoop may be submerged for collection. The contents can then be transferred to the sample container. By using this method, the outside of the container does not become contaminated and require decontamination. To collect a shallow sample that is more than 10 feet from the water's edge, a pond sampler or a small peristaltic pump with stiff-walled tubing may be used. Surface water may be sampled at greater depths with an extended bottle sampler or a weighted bottle. In both cases, the exterior of the bottle is exposed to contamination. At depths up to 18 to 24 feet, a peristaltic pump may be used. If the depth exceeds the lift capacity of the pump, a Kemmerer bottle is typically used.

Note: When working around ponds or lagoons, especially in PPE, drowning is a potential hazard. The PPE can restrict one's movement and vision, resulting in a trip or fall. Once in the water, the weight of the PPE and the restricted movement can be deadly. Also, be aware that a SCBA, which is part of level A or B protection, does NOT work underwater.

Groundwater Sampling at HAZWOPER Sites

Numerous wells, both on-site and off-site, are required for groundwater monitoring on hazardous waste sites. The installation and operation of these wells must be planned and supervised by personnel who have extensive knowledge and experience in hydrology and related subjects.

When installing and operating the well, the following considerations are necessary:
· Well installation plans must be carefully followed to ensure that the well will provide representative information. The plans will also help to avoid puncturing through a separating layer to an uncontaminated aquifer (i.e., a water-bearing rock formation).
· Decontaminate drilling and sampling equipment thoroughly after to avoid cross-contamination of the next well.
· Avoid overpumping, which can alter groundwater flow or affect
· Proper safety precautions must be taken by sampling personnel. Any material that comes out of a drill hole or well, either on-site or off-site, may be contaminated.

It is important to realize that the water standing in a well, and immediately surrounding a well, does not generally represent the groundwater to be sampled. Therefore, the well must be purged (i.e., removal of standing water) before sampling by pumping or bailing. The purged water should be containerized and stored until samples are analyzed. If the samples indicate that the purged water is contaminated, the site-specific project plan should specify the method of handling or disposal.

The volume of purged water to be removed should be specified in the sampling plan. An alternative to volume-based removal is to monitor the water level, temperature, conductivity, and pH as the well is purged. When these factors stabilize, the well is sufficiently purged. Wells may be purged using a variety of equipment including a gas pressure displacement system, a submersible pump, and a peristaltic pump. The most complete purging occurs if water is pumped from just below the water surface. Care must also be taken to purge the wells at the correct rate to avoid overpumping and excessive draw-down (i.e., lowering of the water level).

Gas Pressure Displacement System
In a gas pressure displacement system, the water is displaced up the discharge tube by the increased gas pressure above the water level. It is particularly useful when the well depth is beyond the lifting capacity of a peristaltic pump. However, the potential for increased gas diffusion into the water makes this system unsuitable for when sampling for volatile (i.e., vaporous) organic compounds or for most pH factors.

Submersible Pumps
Submersible pumps are portable and have relatively high pumping rates. However, they are heavy, awkward, expensive, and difficult to decontaminate in the field.

Peristaltic Pumps
Peristaltic pumps are limited in their lifting capacity; however, they have an advantage in that the same system can be used not only for purging but also for sample collection.

A peristaltic pump is useful when relatively large samples are needed. However, a pump system may strip volatile components as a result of the vacuum created by lifting. Therefore, volatile organic analysis samples should be collected using a bailer.

When collecting a sample with a peristaltic pump, the following guidelines should be observed:
· Install clean medical-grade silicon tubing in the pump head.
· Attach pump to required length of Teflon suction line; lower to mid-point of well screen or slightly below the existing water level.
· The first liter of liquid collected is considered a system purge.
· Fill sample bottles, letting the discharge flow gently down the side of the bottle with a minimum of turbulence (i.e., disturbance).
· Preserve the sample (if directed by EPA sampling guidelines), check the Teflon liner in the cap, and then secure the cap.
· Complete the label, the chain of custody form, and the log entry.
·Place the sample bottle in a carrying container at 4 degrees C.
· Allow the system to drain, disassemble, and return tubing for decontamination.

Bailers are useful when samples must be taken from depths beyond a pump's lifting capacity and when volatile component stripping is a concern. A bailer allows samples to be recovered with a minimum of aeration (i.e., mixing with air). This is accomplished by slowly lowering the bailer until it contacts the water and then by allowing the bailer to sink as it fills. The disadvantage of using bailers is that they are time-consuming because of their limited sample volume. In addition, transfer of the sample to the collection jar may cause aeration. Pouring the water slowly down the side of the sample bottle may reduce aeration, by avoiding turbulence.

Container Sampling

Drums are usually opened and sampled in place during site investigations. However, remedial and emergency operations may require a separate drum opening area. Procedures for opening drums are the same, regardless of where the drums are opened. To enhance the efficiency and safety of drum-opening personnel, the following procedures should be instituted.

· If a supplied-air respiratory protection system is used, place a bank of air cylinders outside the work area and supply air to the operators via air lines and escape SCBAs. This enables workers to operate in relative comfort for extended periods of time.
· Protect personnel by keeping them at a safe distance from the drums being opened. If personnel must be located near the drums, place explosion-resistant plastic shields between them and the drums to protect them in case of detonation. Locate controls for drum opening equipment, monitoring equipment, and fire suppression equipment behind the explosion-resistant plastic shield.
· If possible, monitor continuously during drum opening. Place sensors of monitoring equipment, such as colorimetric tubes, dosimeters, radiation survey instruments, explosion meters, organic vapor analyzers, and oxygen meters, as close as possible to the source of contaminants (i.e., at the drum opening).

Remote-controlled Opening
Use the following remote-controlled devices for opening drums:
I. Pneumatically operated impact wrench to remove bungs.
II. Hydraulically or pneumatically operated drum piercers.
III. Backhoes equipped with bronze spikes for penetrating drum tops in large-scale operations.

a) Do not use picks, chisels and firearms to open drums
b) Hang or balance the drum opening equipment to minimize worker exertion.
c) If the drum shows signs of swelling or bulging, perform all steps slowly. Relieve excess pressure before opening and, if possible, from a remote location using such devices as a pneumatic impact wrench or hydraulic penetration device. If pressure must be relieved manually, place a barrier such as explosion-resistant plastic sheeting between the worker and bung to deflect any gas, liquid, or solids which may be expelled as the bung is loosened.
d) Open exotic metal drums and polyethylene or polyvinyl chloride-lined (PVC-lined) drums through the bung by removal or drilling. Exercise extreme caution when manipulating these containers.
e) Do not open or sample individual containers within laboratory packs.
f) Reseal open bungs and drill openings as soon as possible with new bungs or plugs to avoid explosions and/or vapor generation. If an open drum cannot be resealed, place the drum into an overpack. Plug any openings in pressurized drums with pressure-venting caps set to a 5-psi (pounds per square inch) release to allow venting of vapor pressure.
g) Decontaminate equipment after each use to avoid mixing incompatible wastes.
h) Drum and container sampling can be one of the most hazardous activities to worker safety and health because it often involves direct contact with unidentified wastes. When manually sampling from a drum, use the following safety techniques:
i) Keep sampling personnel at a safe distance while drums are being opened. Sample only after opening operations are complete.
j) Do not lean over other drums to reach the drum being sampled, unless absolutely necessary.
k) Cover drum tops with plastic sheeting or other suitable noncontaminated materials to avoid excessive contact with the drum tops.
l) Never stand on drums. This is extremely dangerous. Use mobile steps or another platform to achieve the height necessary to safely sample from the drums.
m) Obtain samples with either glass rods or vacuum pumps. Do not use contaminated items such as discarded rags to sample. The contaminants may contaminate the sample and may not be compatible with the waste in the drum. Glass rods should be removed prior to pumping to minimize damage to pumps.

Selection of Sampling Equipment

Selection of sampling equipment is dependent on the type of container and the material to be sampled. Sludge and sediment sampling is similar to soil sampling in that the material may in some cases be collected as though it were a solid. Therefore, scoops, triers, corers, or a grain thief may be used for collection. Again with containerized liquids, the selection of sampling equipment is dependent on the material and the container. A device that is commonly used is a drum thief. These glass tubes are inexpensive and can therefore be disposed of instead of decontaminated. One draw back is that if the liquid has a low viscosity it may be difficult to maintain the vacuum in the tube and the sample may dribble from the tube as it is withdrawn from the drum. Also, glass tubing should not be used with materials containing hydrofluoric acid or strong alkali solutions. PVC tubing may also be used in a manner similar to the drum thief; however, compatibility is a concern. Another common device is the coliwasa, which is often used for multi-phase samples. However, the main disadvantage of the coliwasa is decontamination.

Note: The methods discussed for surface water sampling may be an option, depending on the size and accessibility of the container.

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