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Surface Water Chemistry
Surface water is sampled to assess water quality parameters to
provide contaminant concentration data. This data can be used for
calculating contaminant mass loadings. Surface water can become
easily contaminated with acid and metals when it contacts tailings
and waste rock piles. Samples may be taken from various different
locations including streams, rivers, adit openings, wetlands, ponds,
lakes, and runoff from tailings and waste rock. Surface water samples
should be taken near the source to determine if contamination is
being produced. If contamination is being produced, samples should
be taken in different locations downstream of the source to determine
the impacts on downstream environments. Upstream samples may be
taken to determine background concentrations of different contaminants.
Contaminant concentrations are compared with acceptable concentrations
as specified in surface water protection legislation, mine permits
and licenses. These limits are scientifically-based and intended
to protect aquatic life in the receiving environment. In addition,
surface water regulations are in place to protect human health.
Surface water samples are usually taken manually by grab sampling.
The advantage of manually collected grab samples is that field analysis
can be done immediately, unlike programmable samplers where a delay
between collection, sampling and analysis can affect results. Samples
may be taken in a sampling container and then transferred to a sampling
bottle (polyethylene bottles are acceptable for most acidic drainage
water quality parameters) or they may be collected directly into
a sampling bottle. Samples should be taken from the middle of the
flow stream if possible, and at mid-depth. Care must be used to
collect a fresh sample and not stir up sediments and introduce contaminants
into the sample collection area. Samples have a limited life span
and analytical analyses need to be completed within allowable times
from sample collection. To help preserve samples, they should also
be placed in a cooler (ideally at 4�C) immediately after sampling.
Sample bottles should be labeled and should indicate the sample
location, the time of sampling, the name of the sampler, and the
required analyses. Information written on the sampling label should
also be recorded in a field book along with a description of the
sampling location.
Samples may be analyzed for electrical
conductance, dissolved
oxygen (DO), pH
and water temperature in the field. Analyses for pH, sulfate,
acidity,
alkalinity,
total dissolved
solids, total
suspended solids, elemental
metals, redox
potential (Eh) and sometimes other parameters are commonly conducted
by an analytical chemistry lab. Laboratory analyses for common water
quality parameters are fairly standard, however limits of detection
need to be specified to ensure that the data can be compared to
allowable limits or established water quality objectives. As an
example, if the measured concentration of copper is to be compared
to a water quality objective of 0.005 mg/L, the limits of detection
need to be 0.005 mg/L or lower (MEND,
2001).
Problem | Compliance
| Health & Safety | Sampling
| Analytical | Data
Quality
Site Assessment | Prediction
| Construction | GIS
| Monitoring & Assessment
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