EP 1110-1-27
27 Jan 00
(4) Table 2-4 summarizes the purposes of specific physicochemical analyses recommended for
use in identifying the mechanisms at work in ground water within the influence of the sampled wells.
Analysis of geochemical mechanisms at work is crucial information in "triage" (Chapter 5) in which a
determination is made of the appropriate levels of maintenance monitoring should be made. As specific
redox-sensitive pairs important to a system are identified, these pairs can be monitored for change over
time.
Table 2-4. Summary of Physicochemical Methods Relevant to Well Maintenance
Constituent Analysis
Purpose of Analysis
Fe (total, Fe2+/Fe3+, Fe minerals and complexes)
Indications of clogging potential, presence of
biofouling, Eh shifts. Fe transformations are the
most common among redox-sensitive metals in
the environment.
4+
2+
Mn (total, Mn /Mn , minerals and complexes)
Indications of clogging potential, presence of
biofouling, Eh shifts. Less common but locally
important in some wellfields.
2-
2- 0
S (total, S /S /SO4 , S minerals and complexes)
Indications of corrosion and clogging potential,
presence of biofouling, Eh shifts.
Eh (redox potential)
Direct indication of probable metallic ion states,
microbial activity. Usually bulk Eh, which is a
composite of microenvironments.
PH
Indication of acidity/basicity and likelihood of
corrosion and/or mineral encrustation. Combined
with Eh to determine likely metallic mineral states
present.
Indication of TDS content and a component of
corrosivity assessment.
Major ions
Carbonate minerals, F, Ca, Mg, Na, Cl determine
the types of encrusting minerals that may be
present and are used in saturation indices. One
surrogate for many cations is total hardness.
Turbidity
Indication of suspended particles content, suitable
for assessment of relative changes indicating
changes in particle pumping or biofouling.
Sand/silt content (v/v, w/v)
Indication of success of
development/redevelopment, potential for
abrasion and clogging.
2+
3+
Note: Generally, the Fe /Fe ratio (easily measured using conventional field analysis instruments) is
the most useful. In some settings, Mn oxidation (resulting in more difficult-to-remove minerals) and
the sulfur system may be dominant.
c. Hazardous physical/chemical parameters. Personnel safety (Chapter 7) dictates that physical
(primarily radiological) and chemical conditions that will affect how maintenance can be performed
should be known. For the most part, data collected for the purpose of regulatory monitoring (and its
toxicological interpretation) should cover hazards of exposure to pumped fluids. Additional factors may
include:
2-14
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