• During the initial site entry phase of site characterization, a team of personnel in appropriate protective gear enters the site to make observations and take samples.

The second stage of site characterization is initial site entry. The purpose of this stage is to:

• Verify the information gathered in the preliminary evaluation, and
• Gather additional information.

No matter how thorough the preliminary evaluation is, there are always potential unknowns during an initial site entry. For that reason, a minimum of a Level B ensemble for protective clothing and equipment is highly recommended. A Level A ensemble must be worn for certain activities or if immediately dangerous to life or health (IDLH) conditions are expected.

The level of protective equipment and clothing worn during an initial site entry must be decided based on the results of the preliminary site evaluation. It must provide enough protection to keep exposure below permissible exposure limits (PELs) or published exposure levels.

If a positive-pressure self-contained breathing apparatus (SCBA) is not part of the entry ensemble but respiratory protection is necessary, then site entry personnel must carry escape SCBAs with at least five minutes of air.

If the preliminary site evaluation does not produce enough information to identify the hazards that may be present, then the team must wear at least a Level B ensemble for the initial site entry.

An initial site entry team should consist of a minimum of four personnel, and the buddy system must always be used — at least two employees enter the site, and at least two more employees wear the same (or higher) ensemble level as the entry employees but remain outside the site, ready to provide support in case of an emergency.

If the preliminary evaluation is insufficient or indicates the potential for ionizing radiation or IDLH conditions, one of the tasks of initial entry employees is to monitor the air and make visual observations to confirm site conditions. In this situation, the Occupational Safety and Health Administration’s (OSHA) Hazardous Waste Operations and Emergency Response (HAZWOPER) Standard requires the use of direct-reading instruments, such as combustible gas meters and detector tubes, to check for:

• Hazardous levels of ionizing radiation,
• Any IDLH conditions, and
• Other conditions that may cause death or serious harm (such as combustible, explosive, or oxygen-deficient atmospheres or toxic substances).

The standard also calls for visual observations for actual or potential IDLH or other dangerous conditions like enclosed spaces that must be entered, bulging drums, or open patches with dead vegetation.

If deadly or serious hazards are indicated, initial entry employees should proceed with extreme caution. It may be necessary to regroup and take extra precautions before continuing.

The other main task of initial entry employees is to gather additional information, such as:

• The types of containers and storage systems;
• Any containers in damaged, corroded, leaking, or unsound condition;
• The quantities and physical states of materials (such as gases, liquids, or solids);
• Potential exposure indicators, such as dead fish, an oily sheen on water surfaces, dust in the air, and pools of liquid;
• Any safety hazards like unstable terrain and deteriorating structures;
• Land features and natural wind barriers;
• The presence of poisonous plants; and
• Any signs, labels, tags, or other identifying markings.

Finally, when gathering additional information, workers will:

Collect samples from the air, soil, pools of liquids, storage containers, ditches, streams, and groundwater; and

Use non-invasive methods like metal detection or radar to locate buried wastes.

After the initial site entry is completed, all the new information must be analyzed by a qualified person prior to starting operations onsite. This analysis will ensure employees are aware of:

• Specific hazardous substances onsite and their concentration levels,
• Any other health hazards that are present at the site, and
• Any other physical hazards that are present at the site.

Once the presence and concentrations of specific hazardous substances and health hazards have been established, the risks associated with these substances must be identified. Some risks that must be considered include:

• Exposures exceeding the PELs and published exposure levels,
• IDLH concentrations,
• Potential skin absorption and irritation sources,
• Potential eye irritation sources,
• Explosion sensitivity and flammability ranges, and
• Oxygen deficiency.

Before work begins onsite, the employer must make available to employees information concerning any identified risks and the properties of each hazardous substance present or anticipated at the site, if those substances are relevant to the duties workers are expected to perform. The employer may use the Hazard Communication (HazCom) Program for this purpose.