EP 1110-1-27
27 Jan 00
Chapter 5
Schedule of Maintenance Actions for Wells
5-1. Well and Plant Maintenance Schedule Overview
a. General. Chapter 9 provides a recommended maintenance program. This pamphlet provides
recommendations and decision trees for a variety of operational settings. It is emphasized that this is a
guide that should be adapted to local needs and should be revised as experience dictates.
b. Pre-selection of maintenance testing intervals and methods. There is considerable debate
concerning appropriate monitoring and inspection intervals for maintenance of pumping and injection
wells for HTRW sites. The purpose of such monitoring is to
Detect deterioration symptoms in time to permit the most cost-effective repair or replacement.
Define the condition sufficiently so that correct rehabilitation diagnosis and treatment are possible.
The ideal situation from an operational standpoint is to achieve these objectives with the minimum
possible intrusion, time, and material costs. Some biogeochemical environments and hydrologic condi-
tions result in a reduced likelihood of well clogging and corrosion than others. Among those conditions so
recognized are high-specific-capacity aquifer settings under nitrate-reducing conditions with modest total
organic carbon. Clogging potential is greater at both higher and lower redox potentials (e.g., sulfate-
reducing and iron-oxidizing). Field work on domestic water supply wells in a region with well clogging
and water quality concerns documented in Cullimore and Legault (1997) showed that, if there is a
background of data on well-deteriorating causes and effects, monitoring can be limited to one or a few
biological parameters. These parameters can be supported by the hydrologic measurements previously
identified in Chapter 2. However, defining deteriorating conditions is necessary during site development
for monitoring to be safely minimized and can only be reasonably accomplished using existing wells in
the area that have had time for biofouling to develop.
5-2. Minimum and Optimal Regular Schedule for First Year
This section and Sections 5-3 and 5-4 offer maintenance schedule recommendations based on the
principle of establishing a data baseline and then settling into less frequent (or more intense) preventive
maintenance (PM) activity if conditions warrant. Table 5-1 is a summary minimum recommendation for
first-year maintenance activity frequency for an HTRW well array. It is an appropriate monitoring level-
of-effort for a new (or newly started) facility if
There is sufficient background information on the biogeochemical and hydrologic
environment to make good estimates of the types and rates of deterioration to be expected.
The well construction and system equipment are well documented (as in a new system) and
not one taken over from another responsible party or O&M service provider).
a. Choosing level of effort. "Sufficient" information may include experience with other facilities
with similar geochemistry and contaminants and hydrogeology or detailed site characterization including
geochemical information from samples of existing (e.g., domestic water) wells from which conclusions
about biological mechanisms can be made. Table 5-2 lists the type of data that should be available to
permit a minimized first-year maintenance testing schedule (Table 5-1).
5-1
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