Environmental Engineering Reference
In-Depth Information
1. Wash each sample bottle or piece of glassware with a brush and
phosphate-free detergent.
2. Rinse three times with cold tap water.
3. Rinse three times with distilled or deionized water.
Method B: Acid Wash Procedures
Use this method when preparing all sample containers and glassware for
monitoring nitrates and phosphorus. Wear latex gloves.
1. Wash each sample bottle or piece of glassware with a brush and
phosphate-free detergent.
2. Rinse three times with cold tap water.
3. Rinse with 10% hydrochloric acid.
4. Rinse three times with deionized water.
Sample Types
Two basic types of samples are commonly used for water quality testing:
grab samples
and
composite samples
. The type of sample used depends on the
specific test, the reason why the sample is being collected, and the applicable
regulatory requirements. Grab samples are collected at one time and one
location. They are representative only of the conditions at the time of col-
lection. Grab samples must be used to determine pH, total residual chlorine
(TRC), dissolved oxygen, and fecal coliform concentrations. Grab samples
may also be used for any test that does not specifically prohibit their use.
Composite samples consist of a series of individual grab samples collected
over a specified period of time in proportion to flow. The individual grab
samples are mixed together in proportion to the flow rate at the time the
sample was collected to form the composite sample.
Note:
Before collecting samples for any test procedure, it is best to review
the sampling requirements of the test.
Collecting Samples from a Stream
In general, sample away from the stream bank in the main current. Never
sample stagnant water. The outside curve of the stream is often a good place
to sample, because the main current tends to hug this bank. In shallow
stretches, carefully wade into the center current to collect the sample. A boat
is required for deep sites. Try to maneuver the boat into the center of the
main current to collect the water sample. When collecting a water sample for
analysis in the field or at the lab, follow the steps below.
