The following sections describe the equipment used in the field to measure specified parameters, procedures for equipment calibration, maintenance and decontamination.

Field measurements may be made using the following monitoring equipment:

3.1 - HNu Photoionization Detector and Organic Vapor Analyzer

Monitoring for total organic vapors and gases in the field will be conducted using the HNu PID or an OVA. The HNu measures up to 2,000 ppm organic vapors in the air while the OVA measures up to 10,000 ppm. Both will be used for various field screening techniques.

During surface soil sampling or drilling of soil and/or monitoring well borings, the PID will be used periodically to monitor the breathing zone, drill cuttings, borehole and undisturbed core samples. Headspace analyses of soil samples retrieved with a core sampler during drilling will also be tested with the HNu or OVA. All readings made with the HNu or OVA will be recorded either in the field logbook or directly on the field boring logs.

During well development, groundwater sampling, and surface soil sampling, the HNu or OVA will be used to monitor the breathing zone, and readings will be recorded in the field logbook. Furthermore, immediately after the monitoring well cap is removed, a reading will be taken inside the top of casing. The frequency of air monitoring for these activities is defined in the project HASP (Parsons ES, 1995). Prior to use of the HNu or OVA for air monitoring, personnel will be thoroughly familiar with site-specific action levels defined in the HASP.

The HNu PID or OVA will be calibrated according to the user's manual at least once a day, prior to use in the field. The standard calibration gas for the HNu is isobutylene, which may be obtained in canisters from an environmental sampling equipment supplier. Methane is used as the calibration gas for the OVA.

3.2 - Sensidyne One-Stroke Pump and Tubes

If the concentration of organic vapors in the breathing zone exceeds 1 ppm above background, benzene and vinyl chloride Sensidyne tubes will be used to determine whether these compounds are present. These two compounds have the lowest permissible exposure limit (PEL) of all suspected contaminants on site. Sensidyne tubes are compound specific and may be used to determine if the compound is present and to quantify the concentration. If needed, Sensidyne tubes will be used during drilling activities, monitoring well installations, subsurface soil sampling, groundwater sampling, and the geophysical surveys. The frequency of ambient air monitoring is detailed in the HASP.

The tube is physically broken open at one end, and ambient air is manually drawn through the system to obtain a direct reading. Sensidyne tubes do not require calibration.

Each Sensidyne tube contains a reagent system designed to undergo a chemical reaction with a particular substance. Since chemicals and chemical reagents are not stable indefinitely, each box of detector tubes is stamped with an expiration date. The tubes are suitable for use through the last day of the month of expiration. Tubes used beyond the expiration date cannot be relied upon to give accurate results.

To guarantee the validity of the tube expiration date, Sensidyne tubes should always be stored in the original package at room temperature. A note on the package indicates a maximum storage temperature of 25°C (77°F). Excessively low (less than 35°F) or high (greater than 77°F) temperatures during storage will be avoided, and the tubes will not be subjected to light for prolonged periods.

Detector tubes are tested according to National Institute for Occupational Safety and Health (NIOSH) method TCA/A-012, "Certification Requirements for Gas Detector Tube Units," for the Safety Equipment Institute certification program. Furthermore, each manufacturer's detector tubes are tested as a unit by an independent third party laboratory accredited by the American Industrial Hygiene Association (AIHA).

The Sensidyne one-stroke pump and tubes require no general maintenance.

3.3 - HMX 271 Combustible Gas Indicator

The HMX 271 combustible gas indicator will be used to measure the LEL in work areas. The LEL of a combustible gas or vapor is the lowest concentration by volume in air which will explode when there is an available ignition source. During field activities that can potentially generate sparks, such as drilling or welding, the breathing zone and the air in and around the borehole or well will be periodically monitored with the HMX 271 combustible gas indicator. Furthermore, during field activities around enclosed spaces the breathing zone will also be monitored for the presence of combustible gases and vapors.

The HMX 271 combustible gas indicator takes continuous and simultaneous measurement of combustible gases, oxygen levels, and hydrogen sulfide concentrations. The HMX 271 should be calibrated with pentane according to the user's manual prior to field work each day.

If the HMX 271 is used to measure hydrogen sulfide, it will first be calibrated with the appropriate calibration gas.

The HMX 271 combustible gas indicator will be maintained in the field by wiping the unit clean after every use, storing the unit in a safe protected case, and recharging the battery on a daily basis or as use dictates.

3.4 - Hydac Conductivity, Temperature, pH Meter

General water quality parameters will be periodically tested during well development and groundwater sampling using a Hydac conductivity, temperature, pH meter, or equivalent. The Hydac conductivity, temperature, pH meter will be calibrated according to the user's manual each day prior to use. The meter will be recalibrated periodically during days of extended use.

3.5 - Water Level Indicator

The depth to groundwater will be measured in each monitoring well with an electric water level indicator. Depth to water will be measured from the top of casing and recorded in the field logbook.

The fiberglass tape on the water level indicator may stretch over extended periods of use. Therefore, the accuracy of the water level indicator will be checked in the field against a calibrated steel measuring tape. Calibration of water level indicator(s) will be performed once prior to use.

The following procedures will be followed for proper maintenance of the water level indicator:

1. Keep probe clean and free of silt or mud. Rinse after every use. The probe on the water level indicator must be thoroughly rinsed with deionized water prior to taking each water level measurement. This procedure will prevent cross contamination at the site. If gross contamination is observed on the water level indicator probe, it will be washed with Alconox and water and a paper towel or scrub brush.

2. Before sending the unit to the field, make sure it is functioning properly. If not, replace batteries and try again. If water level indicator is still not functioning properly, send back to manufacturer for repair.

3.6 - Field Equipment Calibration

Before use, field monitoring instruments will be calibrated on a schedule according to the manufacturer's specifications. A copy of the operations manual will be kept with all field monitoring equipment. The operator must understand the limitations of each instrument and the possible sources of error. Furthermore, the operator must ensure that the equipment is in good working order and functioning properly. All calibration activities will be noted in a calibration logbook. Calibration methods and frequencies are listed in Table 3.1.

3.7 - Equipment Maintenance

Equipment to be used during field sampling will be examined to certify that it is in proper operating condition. This includes checking the manufacturer’s operating manual and the instructions for each instrument to ensure that all maintenance requirements are being observed. Field notes for previous sampling trips will be reviewed so that the notations on any prior equipment problem are not overlooked and all necessary repairs to equipment have been carried out.

Equipment, instruments, tools, gauges, and other items requiring preventive maintenance will be serviced in accordance with the manufacturer’s specified recommendations and written procedures developed by the operators.

Manufacturer’s procedures identify the schedule for servicing critical items in order to minimize the downtime of the measurement system. It will be the responsibility of the operator to adhere to the maintenance schedule and to arrange any necessary and prompt service as required. Service to the equipment, instruments, tools, gauges, etc., will be performed by qualified personnel. In the absence of any manufacturer’s recommended maintenance criteria, a maintenance procedure will be developed by the operator based upon experience and previous use of the equipment.

Logs will be established to record maintenance and service procedures and schedules. All maintenance records will be documented and traceable to the specific equipment, instruments, tools, and gauges.

3.8 - Instrument Decontamination

Instrument decontamination will be performed on equipment that comes in direct contact with soil or water samples. Refer to Section 1.5 of this plan for proper decontamination procedures or the manufacturer’s operating manual specified recommended procedures.

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