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When necessary planning and preparation steps have been completed, you are ready to collect samples. Sample collection contains four major components you must keep in mind at all times. The first and most important is personal health and safety. Make sure that you and all the samplers you supervise have had the appropriate safety training and that you adhere to all the safety precautions listed in your sampling plan.
The second major component is collect a representative sample. The primary objective of any sampling plan is to collect a sample that represents the water quality at that particular time.
The third major component is quality control, described in STEP 11.
The fourth major component is record keeping (STEP 10, below). Complete and accurate records are essential.
Before you attempt to collect water quality samples, you must be aware of the applicable health and safety requirements. Because sample collection may occur at contaminated sites or in remote, rugged country far from immediate medical attention:
A. Recording Minimum Set of Data Elements
On October 29, 1992, the EPA approved the establishment of the minimum set of data elements (MSDE) for ground water quality. The purpose of the MSDE is to share and manage water-quality information effectively at the federal, state, county and local levels of government. The EPA and its contractors are required as policy to use the MSDE; other federal agencies, states, tribes, and localities are encouraged to adopt them where appropriate.
The MSDE consists of 21 data elements. Items 1 through 10 and 17 through 21 below also are applicable to surface water quality sampling. A complete description of these elements is provided in "Definitions for the Minimum Set of Data Elements for Ground Water Quality"; copies can be obtained by calling the Safe Drinking Water Hotline at 1-800-426-4791. Brief definitions of the elements are given below (from EPA Order 7500.1A, 10/29/92, pp. 3-6):
IDENTIFICATION
1. Data Sources: The name of the organization to which questions regarding the following data can be directed: 1) latitude and longitude coordinates, 2) altitude coordinate, 3) well log information, 4) sample collection and 5) laboratory sample analyses.
2. Latitude: A coordinate representation that indicates a location on the surface of the earth using the earth's equator as the latitudinal origin, reported in degrees, minutes, seconds, and fractions of a second in decimal format (if fractions of a second are available). A "+" (plus) symbol represents latitudes north of the equator. A "-" (minus) symbol represents latitudes south of the equator.
3. Longitude: A coordinate representation that indicates a location on the surface of the earth using the prime meridian (Greenwich, England) as the longitudinal origin, reported in degrees, minutes, seconds, and fractions of seconds (if fraction of a second are available). A "+" (plus) symbol represents longitudes "east" of the prime meridian.
4. Method Used to Determine Latitude and Longitude: The procedure used to determine the latitude and longitude coordinates, the standard used for three dimensional and horizontal positioning, and the date on which the coordinates were determined.
5. Description of Entity: A textual description of the entity (e.g., sampling station) to which the latitude and longitude coordinate refers.
6. Accuracy of Latitude and Longitude Measurement: The quantitative measurement of the amount of deviation from true value present in a measurement (estimate of error). It describes the correctness of a measurement.
7. Altitude: The vertical distance from the National Reference Datum for Altitude to the land surface or other measuring point in meters (or feet). If the measuring point is above the National Reference Datum for Altitude a "+" (plus) sign shall precede the reported altitude value. If the measuring point is below the National Reference Datum for Altitude a "-" (minus) sign shall precede the reported altitude value.
8. Method Used to Determine Altitude: The method used to determine the altitude value, the National Reference Datum on which the altitude measurement is based, and the date the measurement was taken.
9. State FIPS Code: A Federal Information Processing Standard (FIPS) alphabetic or numeric code to indicate the state (or its equivalent such as territory or province) in which the well is located.
10. County FIPS Code: A FIPS numeric code to indicate the location of the county (or county equivalent such as territory or province) in which the well is located.
WELL INFORMATION
11. Well Identifier: A unique well indicator assigned by the responsible organization.
12. Well Use: The principal current use of the well; if the well is not currently in use, the original or principal purpose for its construction.
13. Type of Log: The type of record-keeping log(s) available for a well.
14. Depth of Well at Completion: The depth of the completed well below the land surface or other measuring point, in meters (or feet).
15. Screened/Open Interval: The depth below the measuring point to the top and bottom of the open section in a well reported as an interval in meter (or feet). The open section may be a well screen, perforated casing or open hole.
16. Depth to Water: The vertical distance between the measuring point and the water surface level at a well, corrected to land surface, where the measuring point is not the land surface. Report this distance in meters (or feet), along with the date and time of measurement.
SAMPLE INFORMATION
17. Sample Identifier: A unique number for each water quality sample collected at a well which references the date, the depth at which each sample is taken reported in meters (or feet), and the time the sample is taken.
18. Constituent or Parameter Measured: Measurement of a physical, chemical or biological component is referred to as a constituent or parameter.
19. Concentration/Value: The analytical results value, the units of measure used, and the analytical methods applied.
20. Analytical Results Qualifier: Qualifying information that will assist in the interpretation of the concentration/value, such as whether the level is below the detectable limit or if the constituents (or parameters) of interest are present but cannot be quantified.
21. Quality Assurance Indicator: The quality assurance of the field protocol plan and laboratory quality assurance/quality control (QA/QC) procedures.
B. Keeping Field Notes
Modern sample collection in the field requires adequate documentation for quality assurance and control. Maintain a separate file in the office for each station. The sampling station file may contain detailed written notes describing how samples were taken, field measurements, previous laboratory analyses, permission forms, chain-of-custody records, maps, photographs and correspondence. Because of their importance as official and legal documents, make these as legible and complete as possible. The file's location, security and oversight should be described in Part VI. Field Methods and Procedures of your Sampling Plan (see STEP 3).
The recording process is speeded up if one person performs the sampling while the other takes field notes. Use a standard field form if it is available. ADEQ (QAPP, 1991, p. 74) recommends that the following items be recorded in indelible ink:
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