Department of Health Seal

TGM for the Implementation of the Hawai'i State Contingency Plan
Section 8.6
FIELD SCREENING EQUIPMENT TO SUPPORT HEALTH AND SAFETY PROGRAMS

8.6 FIELD SCREENING EQUIPMENT TO SUPPORT HEALTH AND SAFETY PROGRAMS

The HEER Office does not regulate Health and Safety plans required for work on contaminated or hazardous waste sites (see Section 3.6.3). However, the HEER Office does check to confirm that Health and Safety plans are included as part of the overall site Sampling and Analytical Plan or site Work Plans. Because field screening equipment is commonly used on contaminated sites to support protection of workers, summary information on field equipment that may typically be utilized is included in this section.

All personnel using field survey equipment for health and safety related monitoring should have training on its operation, limitations, and maintenance. Maintenance and internal or electronic calibration should be performed in accordance with manufacturer recommendations by individuals trained and familiar with the devices before and after their use in accordance with manufacturers’ instructions. Repairs, maintenance, and calibration of these devices should be recorded in an equipment maintenance logbook. The equipment maintenance logbook for each instrument should be kept in that instrument’s storage case. For rented monitoring equipment, routine repairs consisting of maintenance and calibration should be conducted by the rental company vendor prior to the equipment being available for rent. The rental company vendor should provide a copy of the equipment maintenance and calibration response certification within the equipment storage case. The results of the vendor’s routine calibration and maintenance should also be recorded in the field logbook. For photoionization detector (PID) rentals, field personnel should ensure that the instrument contains the proper electron volt (eV) lamp.

Air monitoring equipment should be calibrated by field personnel before work begins and after each period of use, in accordance with manufacturers’ instructions and standard industrial hygiene practices to ensure the accuracy of the air monitoring data. Field personnel should ensure that they have the correct calibration gases for the intended air monitoring equipment to be used. Only basic maintenance (such as changing/charging batteries) will typically be performed by on-site personnel. Any additional maintenance or repairs should be performed by a trained service technician.

No single instrument can provide sufficient information as each has its own strengths and weaknesses. Any health and safety monitoring strategy should employ a combination of devices, be documented in an accident prevention plan and site-specific health and safety plan that meets applicable state and federal regulations and has been reviewed and approved by a certified industrial hygienist. Weather conditions such as extreme heat or cold, humidity (water vapor), exposure to rain or other spilled liquids, and electromagnetic radiation can all affect the instrumental readings for the equipment. Real-time monitoring should take into account the applicable use, operating ranges and limitations for the instrument being used, equipment warm-up time, equipment response time, and equipment correction factor (equipment sensitivity). Pay attention to inconsistent or non-responsive readings and record them in the field logbook. Air monitoring instruments discussed in the following subsections are typically used during soil and groundwater investigations. Additional air monitoring, radiation monitoring or other specialized equipment may be required.

Figure 8-13 Combustible Gas Indicator

8.6.1 COMBUSTIBLE GAS INDICATOR (CGI)

This meter typically uses a platinum filament, which is heated by burning the combustible gas or vapor. The increase in heat is measured and reported as a percent of the lower explosive limit (%LEL). Generally if the gas is flammable, the Combustible Gas Indicator (CGI) reading is +50 percent when the meter is calibrated to hexane. The CGI has multiple sensitivities and thus can read a wide range of atmospheric levels on one meter. This meter operates only at normal oxygen levels and is also subject to electronic noise and is not very accurate at very low levels.

Advantages

  • Measures the presence of combustible gases/vapors
  • Range : 0 – 100 % of LEL (units are % of the LEL or ppm depending on the instrument brand used)

Limitations

  • Catalytic sensor poisoning
  • Relative response
  • Does not indicate mists or dusts
  • Must have normal oxygen content (generally at least 16 %) to provide valid readings

Figure 8-14 Oxygen Meter

8.6.2 OXYGEN METER

This instrument uses an electrochemical sensor to measure the partial pressure of oxygen levels in the air and converts that reading to oxygen concentration. A deficient oxygen atmosphere (<19.5 percent) can indicate displacement by another gas or consumption. An oxygen atmosphere with a surplus (>23.5 percent) can indicate another source of oxygen. Either situation is potentially life-threatening and hazardous. It is important to understand that the meter only considers the effect of oxygen itself and not the presence of other materials. Any deflection on the oxygen meter should be treated as an abnormal situation. Neutralizing and masking gases can affect the accuracy of this instrumentation.

Advantages

  • Measures oxygen levels in the air

Limitations

  • Neutralizing and masking gases

Figure 8-15 Flame Ionization Detector

8.6.3 FLAME IONIZATION DETECTOR (FID)

This meter has low detection levels for a broad number of organic compounds and has a self-adjusting span for known compounds. The FID ionizes compounds by burning them in a hydrogen flame. Operations on site may result in variable background levels of airborne compounds. Airborne compounds may be released from vehicles, blowing dust, material transfers, and so on. These sources can complicate monitoring of contaminant emissions during project tasks. Therefore, several upwind and pre-work measurements should be taken to assess contributions to airborne contamination by other potential sources. The instrument can also flame out at 10,000 ppm and above.

Advantages

  • Low detection levels for many organic compounds
  • Self-adjusting span for known organic compounds
  • Ionizes compounds by burning them in hydrogen flame
  • Can detect compounds with high ionization energy vapors (such as methane).

Limitations

  • Can flame out at 10,000 PPM
  • Multiple sensitivities
  • Does not differentiate between compounds detected

Figure 8-16 Photoionization Detector (MiniRAE)

8.6.4 PHOTOIONIZATION DETECTOR (PID)

This instrument detects atmospheric contaminants by ionizing them with UV radiation and producing a current that is proportional to the number of released ions. A PID with a 10.6 electron volt (eV) lamp should be sufficient for measuring VOCs and can be used for monitoring activities. A PID can determine compounds at very low concentrations with little electronic noise; the typical range is 0.5 to 2,000 ppm. The instrument is self-adjusting for known compounds but is blind to many common gases (methane, for example). Operations on site may result in variable background levels of airborne compounds. Airborne compounds may be released from vehicles, blowing dust, material transfers, and so on. These sources can complicate monitoring of contaminant emissions during project tasks. Therefore, several upwind and pre-work measurements should be taken to assess contributions to airborne contamination by other potential sources. This instrument is not accurate at high levels.

Advantages

  • Can detect many analytes and organic compounds at very low concentrations

Limitations

  • Not accurate when analytes and compounds are present in the air at high concentrations
  • Does not differentiate between compounds detected
  • Does not detect acid gases (HCl, HNO3)
  • Does not detect PCBs
  • Humidity reduces accuracy
  • Dusts / Mists reduce accuracy
  • Extreme heat and cold may affect instrument response
  • Does not detect methane and other vapors with high ionization energy
  • Multiple sensitivities (multiple electron volt [eV] lamps may be needed)