the probe(s) from contaminating the water in the well. In no case should field analyses be

performed directly on samples that will be submitted for laboratory analysis.

The QAPjP to be included in the permit application should list the specific parameters

that will be measured in the field. The QAPjP should specify the types of instruments (e.g.,

in line flow cells, downhole probes, meters) that will be used to make field measurements,

and describe the procedures that will be followed in operating the instruments and recording

the measurements. The QAPjP should describe all instrument calibration procedures,

including the frequency of calibration. The description of calibration procedures should

include: discussion of initial calibration, multi level calibration for determination of usable

range, periodic calibration checks, conditions that warrant re calibration of instruments,

acceptable control limits, and the maintenance of calibration records in the field log book. At

a minimum, all field instruments should be calibrated at the beginning of each use and in

accordance with the frequency suggested by the manufacturer. Field instruments should be

calibrated using at least two calibration standards spanning the range of results anticipated

during the sampling event. For example, if ground water pH is expected to be near pH 7, the

two standards used to calibrate the pH meter should be pH 4 or pH 5, and pH 9 or pH 10,

respectively.

7.5

Sample Containers and Preservation

The procedures employed for sample containerization and preservation are nearly as

important for ensuring the integrity of the samples as the collection device itself.

Investigators should refer to Chapter Two of SW 846 for guidance relating to sample

containers and sample preservation. Detailed procedures for sample containerization,

preservation, packaging, and handling should be provided in the QAPjP. Regardless of the

analytes of concern, exposure of the samples to the ambient air should be minimized.

7.5.1

Sample Containers

The Agency has identified several general performance standards that apply to the

selection and use of sample containers relative to ground water monitoring. These are as

follows:

The QAPjP should identify the types of sample containers that will be used to

collect ground water samples, as well as the procedures that the owner/operator

will use to ensure that sample containers are free of contaminants prior to use.

Chapters Three and Four of SW 846 discuss sample container selection and

cleaning for inorganic and organic parameters, respectively.

Clean sample containers should be sealed and stored in a clean environment to

prevent any accumulation of dust or other contaminants. The cleanliness of a

November 1992

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