EP 1110-1-27
27 Jan 00
f. Wellhead chemical treatment.
(1) A hydrant should be installed between the well pitless discharge and the well house flow
meter-valve assembly for discharge to waste during treatment. Several suitable self-draining hydrant
styles approved for potable water distribution are available on the market (ANSI/AWWA C503 and
CEGS 02510). During the well treatment process, a hose may be run from the blowoff hydrant to
containment and treatment.
(2) Chemical feed pumps can be used to meter chemical mixtures into wells (CEGS 11242). The
manufacturer should also be consulted about the chemical compatibility of diaphragm and housing of the
liquid end. Also, the suitability of hose installed for short term, periodic service feeding pH 2 solutions
should be double-checked.
Table 9-1. Design and Equipment for Wellheads to Facilitate Maintenance
Recommended Features
Feature Application
Room exists for personnel to operate and
Improves accuracy and reduces the potential for
manipulate equipment around the wellhead,
accidental injury or equipment damage or loss.
reasonably accessible, dry and stable wellhead
Minimizes personnel needs for routine tasks;
area, elimination of confined-space-entry
reduces time and equipment required for
conditions.
maintenance events.
Locks, caps, or security apparatus are corrosion-
Personnel do not waste time and risk injury or
and weather-resistant
equipment damage attempting to perform
maintenance. Instrumentation is not easily
damaged by heat, cold, or vandalism.
Water-level measurement access and flow
Personnel can perform these tasks efficiently and
readings are easily obtained
willingly.
Wellhead structures and fittings permit easy
Pumps can be removed quickly, saving money.
removal of pumps and downhole equipment.
Piping and valving is designed to limit pressure
Clogging is minimized, and maintenance flushing
drops, and permit convenient flow diversion and
and pigging can be accomplished. See paragraphs
pipe maintenance.
9-1f and 9-1g.
Water quality taps are accessible and protected
Samples can be readily obtained and taps
from weather and corrosion.
maintained.
(3) Systems have been developed to systematically redevelop with the pump in place, and
designed to provide treatment chemicals to the screen where past pump-in-place designs were not
effective. An example is a system in which a valved return flow pipe is installed to permit periodic or
demand flushing of the well water column. These should be considered as maintenance treatment options.
g. Distribution pipeline maintenance. Distribution lines from wells may also develop deposits of
iron oxides and biofilm. If oxidation and fouling in wells are kept to a minimum, lines are likely to remain
relatively clean. However, line clogging is a very common problem in systems pumping contaminated
ground water to treatment.
(1) If the system head shows signs of increasing, a program of pigging and flushing can be
instituted. Pigging is the process of running a soft plug with a rough, abrasive outside surface through the
lines to remove deposits. (The procedure is described in Deb et al. (1990)). Some system modification
9-3
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