1. Government of India & Government of The Netherlands
DHV CONSULTANTS &
DELFT HYDRAULICS with
HALCROW, TAHAL, CES,
ORG & JPS
VOLUME 4
GEO-HYDROLOGY
FIELD MANUAL - PART VIII
MONITORING WELLS
INSPECTION AND MAINTENANCE

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Table of Contents
GENERAL 1
1 NEED FOR OPERATION AND MAINTENANCE (O&M) PLAN 2
1.1 GENERAL 2
1.2 IMPLEMENTATION OF O & M PROGRAMME 3
1.3 NEED FOR PERIODICAL INSPECTION 3
2 INSPECTIONS DETAILS 4
2.1 APPROACHABILITY 4
2.2 INSPECTION OF LOGBOOKS 4
2.3 INSPECTION OF LOCAL SITE CONDITIONS 5
2.4 INSPECTION OF FENCING 6
2.5 INSPECTION OF PROTECTIVE COVER 6
2.6 VALIDATING GEOGRAPHICAL CO-ORDINATES 7
2.7 INSPECTION OF OBSERVATION WELLS 7
2.8 INSPECTION OF SURFACE CASING OF PIEZOMETERS WITHOUT DWLR 8
2.9 CALIBRATION OF MEASURING TAPES 8
2.10 EXAMINATION OF WATER LEVEL HYDROGRAPHS 9
2.11 IDENTIFICATION OF MAINTENANCE TASKS BASED ON THE INSPECTION 10
3 FOLLOW-UP OF FIELD INVESTIGATIONS 13
3.1 GENERAL 13
3.2 DOWN-HOLE GEOPHYSICAL LOGGING 14
3.3 PUMPING OF MONITORING STRUCTURES 15
3.4 CARRYING OUT AQUIFER PERFORMANCE TESTS 17
3.4.1 STEP-DRAW-DOWN TEST 17
3.4.2 CONSTANT DISCHARGE TEST 17
3.5 DEVELOPMENT OF PIEZOMETER 18
3.6 REMOVAL OF ROOTS 18
3.7 HYDROFRACTURING 19
3.8 DEEPENING OF PIEZOMETERS 20
4 MAINTENANCE OF DIGITAL WATER LEVEL RECORDERS 20
4.1 REQUIREMENTS FOR DWLR PERFORMANCE-MONITORING 21
4.2 EXECUTION OF PERFORMANCE MONITORING 22
4.2.1 ADMINISTRATION AND LOGGING 23
4.2.2 ORGANISATION AND PREPARATION 23
4.2.3 PERFORMANCE CHECKS 23
4.2.4 VERIFICATION 24
4.2.5 MAINTENANCE PROCEDURE 25

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GENERAL
The Field Manual on Geo-Hydrology comprises the procedures to be carried out to ensure proper
execution of design of the groundwater water level monitoring network, operation and maintenance of
observation well and piezometers. The operational procedures are tuned to the task descriptions
prepared for each Hydrological Information System (HIS) function. The task description for each HIS-
function is presented in Volume 1 of the Field Manual.
It is essential, that the procedures, described in the Manual, are closely followed to create uniformity
in the field operations, which is the first step to arrive at comparable hydrological data of high quality.
It is stressed that water level network must not be seen in isolation; in the HIS integration of networks
and of activities is a must.
• Volume 4 of the Field Manual deals with the steps to be taken for network design and
optimisation as well as for its operation and maintenance. It covers the following aspects.
• Part I deals with the steps to be taken for network design and optimisation. Furthermore, site
selection procedures are included, tuned to the suitability of a site for specific measurement
procedures.
• Part II details with piezometer construction procedure with details of the different elements and
the significance of different elements in the piezometer construction
• Part III comprises the preparatory activities and procedures for carrying out aquifer tests. The
procedures to be adopted for analysis of pumping test data is briefly discussed
• Part IV comprises the testing and installation of DWLR’s. Procedures to be followed for
procurements and installation are outlined in Volume 4 of the reference manual.
• Part V deals with the need for carrying out Reduced Level Surveys and the procedures in
carrying out the survey are outlined.
• Part VI deals with the standardised procedures to be adopted for manual collection of water level
data from open wells and piezometers.
• Part VII deals with the standardised procedures to be adopted for retrieval of data from DWLR
and integration with the software.
• Part VIII, deals with procedures to be adopted for regular inspection and maintenance of
piezometers and DWLR’s.
The procedures as listed out in this manual are in concurrence with the ISO standards as far as
available for the various techniques and applicable to the conditions in Peninsular India.

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1 NEED FOR OPERATION AND MAINTENANCE (O&M) PLAN
1.1 GENERAL
The integrated groundwater monitoring networks comprise the newly constructed piezometers and the
observation wells of both the state and central agencies. In order to ensure generation of reliable data
from the networks, the piezometers and the observation wells have to be systematically maintained.
Under-performing observation wells and piezometers would generate erroneous data, that could result
in wrong interpretations. This would in the long run result in formulating wrong policies and legislations.
Declining performance of piezometers and observation wells is natural with the passage of time. The
declining performance needs to be anticipated and preventive maintenance needs to be carried out.
The causative factors for declining performances will be largely guided by the local conditions and
these have to be well understood, so as to formulate suitable maintenance strategies.
Open dug wells are referred to as the most efficient groundwater structures and, hence, in a normal
situation, if the dug well is not being used for pumping, it should be the ideal structure for monitoring
the water levels. In the case of observation wells the reliability of the data would decrease
considerably when:
• the well is used for drinking water supply, irrigation or other purposes,
• the observation well goes into disuse and is used for dumping waste,
• declining water levels result in drying up of the well for part of, or throughout the year,
• there is siltation in the well,
• the well collapses,
• there are damages to the platform leading to seepage of surface water and domestic waste,
• the monitoring structure is submerged for part of, or throughout the year, and
• there is a number of production wells near the open well, overlapping the area of influence.
Piezometers are simple structures and require very little for a regular upkeep, also since there is no
pumping equipment installed. Periodically, cleaning and/or rehabilitation may be required, removing
unwanted materials to improve the flow of the surrounding aquifer to the piezometer. Poor
performance can be expected due to:
• clogging of the aquifer fractures or the borehole screen openings by deposition due to chemical
or physical processes,
• poor or under-development of the piezometer at the time of construction,
• general decline in regional water levels leading to seasonal or complete drying up of
piezometers,
• siltation leading to blocking significant portions of the water bearing zones/screens,
• collapse of the piezometer,
• incrustation of the screen,
• growth of roots from the sides of the bore-hole ,
• heavy influence of other production wells near the piezometers overlapping the area of influence,
• seepage of surface water due to failure of sanitary seals,
• vandalism,
• dropping of DWLR into the piezometer, and
• submergence of the piezometer for part of, or throughout the year.
The O&M procedures should identify the monitoring structures that encounter one or more of the
problems listed above. Data emerging from such suspect structures should be identified at the initial
stages itself and these structures should be repaired. In cases where the deterioration is beyond

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repair, the monitoring structure should be abandoned and a suitable replacement should be planned.
The O&M strategy should be preventive in nature rather than curative. It has to be recognised that
deterioration of monitoring structures is natural with time, hence there is a need to invest in
maintenance. Only this can ensure generation of data of reliable quality. In case of piezometers, the
aim should to be maintain them in their original drilled/cased depth, ensuring a good hydraulic
connection with the groundwater reservoir being monitored. The O&M plan has to be formulated by all
the agencies with a clear definition of the procedures, standard maintenance practices, prescribed
technical options for different generic problems with clear recognition of responsibilities at the different
levels, the budgetary requirements, reporting and evaluation procedures.
1.2 IMPLEMENTATION OF O & M PROGRAMME
An ideal O&M policy should ensure that a series of procedures are in place for monitoring the health
of all the monitoring structures.
Maintenance of the observation wells would continue to be a tricky issue, as most of them are
privately owned. However, it has to be ensured that non-representative observation wells do not
continue to generate data. These need to be replaced by reliable open wells or dedicated
piezometers. Review of the performance of all the observation wells appears very relevant and all the
agencies are advised to carry out a detailed examination of all the observation wells and confirm that
the data emanating from them are reliable. The problems that result in the poor performance of
piezometers need to be understood, the solutions for reviving them identified and repairs carried out
so as to bring them back to optimally performing levels.
1.3 NEED FOR PERIODICAL INSPECTION
The health of the monitoring network (for water level and water quality monitoring) needs to be
periodically evaluated by competent authorities in the different districts/divisions/regions, so as to
reassure that the data generated are reliable and that the monitoring practices are in agreement with
the prescribed methodology.
The officers responsible for data collection have the singular responsibility of picking up the first
indicator that reflects a less than optimal performance of the structure. Keen observations followed by
systematic scrutiny of the data during every observation are the key to picking up declining
performances. The officers responsible for data collection have to allocate adequate time at all
observation sites for evaluating the structures and the data. It has to be always kept in mind that data
emerging from a poorly performing monitoring structure can lead to wrong interpretations. Any
structure whose performance is considered suspect by the field-data collector has to be reported to
the concerned officer recommending follow-up investigations.
As a procedure, detailed inspection has to be carried out annually or whenever earlier as requested
by the field officer responsible for data collection.
The inspection should be carried out by the In-charge accompanied by the officers responsible for
data collection. These inspections need to be carried out preferably two months prior to the onset of
the monsoon, so that remedial actions can be taken up before the monsoon. As part of the inspection
the supervisor should witness field measurements of water levels, water quality sampling and DWLR
data transfer. The civil structures have to be examined, the instruments inspected and the
neighbourhood of the monitoring structures observed. Brief chats with the people in the
neighbourhood should prove beneficial in understanding issues that are not seen or otherwise
visualised during the inspection. The inspection should identify and verify:
• that the monitoring structure is providing reliable data,
• the potential threats that could affect the generation of reliable data,
• the solutions for ensuring continuous generation of data,

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• the plans for ensuring the implementation of periodic maintenance procedures,
• the skills of the field officer in-charge of data collection,
• the usefulness of data collection formats and log books and cross-checks them in the field,
• the preparation of an estimate of the maintenance budget,
• the performance and the discipline of the observation staff and staff motivation,
• any observation procedure errors, and
• the calibration of the measuring tape.
The integration of the individual networks of the State and Central Agencies has to be ensured
through regular meetings between the agencies, for an exchange of notes after each inspection. A
joint inspection is also useful at times, but is not always a necessity.
2 INSPECTIONS DETAILS
The inspection should verify whether the construction of the piezometer has been matching the
specifications and whether all the relevant information regarding the piezometer construction and the
local conditions is recorded accurately. Further, it should look at the approachability of the monitoring
site, the time taken for reaching the site, the neighbourhood of the site, the status of the fence and of
the protection cover and then examine the monitoring structure itself. The inspection team should also
address issues related to facilities provided to the monitoring team, including timely availability of
transport, fuel allocation, the status of monitoring instruments, the availability of spares and other
relevant issues.
2.1 APPROACHABILITY
The water level monitoring network of Penninsular India has a large area coverage. The network
represents the different hydro-geological units and aquifer systems. It is likely that a limited number of
these monitoring structures are not easily approachable (or probably not at all) throughout the year. It
has to be ensured that the normal routes taken for reaching the monitoring structures are inspected
and bottlenecks, if any, clearly identified, and that alternative routes, if any, have also been identified
and inspected. During the inspection of the roads not only the mobility of jeeps but also of heavy
trucks, that would carry the water quality sampling pumps/compressor/pumping test units/drilling rig/
hydrofracturing units, has to be kept in mind. In terrain where approachability is difficult during certain
seasons, the feasibility of using local observers (with the required technical skills) to monitor the data
for preventing discontinuity in data generation has to be examined. The usefulness of installing
DWLRs for monitoring water levels in such piezometers also has to be examined.
A route map should be prepared for all observation sites giving the approach road from the nearest
town/highway or prominent feature. The map should give the distances, types of roads, major
bottlenecks and alternative routes, if any. The details of permanent identification marks and the
names of local contact persons with their address should also be part of the map. The maps with the
details of the location should be part of the Logbook.
2.2 INSPECTION OF LOGBOOKS
It is expected that for every monitoring site a log-book, also referred to as the well register, is
maintained giving location details in the form of a map and text. These details would include
geographical co-ordinates, height of Measuring Point (MP), structure design, construction details,
original depth, lithology, aquifer depth, discharge, and water quality details. Information on the
monitoring details including initiation date, monitoring frequency, details of DWLR and cable length
should be part of the logbook as well.

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The logbook should be carried to the site every time a water level monitoring or water quality sampling
is carried out. The inspection team should examine data collection formats, and log books and cross
check them in the field, essentially for assessing the performance of the field officer responsible for
data collection, and assessing the training requirements and the performance of the field instruments.
The purpose of the logbook is to keep a clear record of checks and details of maintenance undertaken
when the site is visited. This includes routine monitoring and inspection by supervising officers. The
logbook is an extremely important link in the data quality audit chain. The design of the logbook will
depend upon the type of the monitoring well, design, type of instruments installed and the frequency
of monitoring.
2.3 INSPECTION OF LOCAL SITE CONDITIONS
The observation wells forming part of the water level and water quality monitoring network are largely
private or community owned open dug wells. In the case of piezometers these are all located on the
premises of government institutions such as schools, colleges, local government offices, electric sub-
stations, health centres, inspection bungalows, police stations, village centres or other government
lands. It has been noticed that in many cases local agencies or interested volunteers have been of
assistance in protecting the piezometers from vandalism as well as helped maintain the surroundings
by cutting the grasses/weeds/branches etc. In some situations, the local institutions have not been of
much assistance in giving protection or maintenance. The reason for the indifference can be due to
lack of awareness on the utility of the water level monitoring structures and its relevance in their life.
This situation needs to be altered and awareness should be created regarding the benefits of reliable
data.
Figure 2.1:
Field inspection of piezometers
The annual inspection team have to sensitise the local people regarding the utility of the piezometers
and the need for proper maintenance. It would always be useful if the design of the structure and the
instruments used are explained along with sample sets of different data. This would generate interest
in the local authorities and communities to help, if not in maintenance, at least in preventing vandalism
(see Figure 2.1).
The neighbourhood of the piezometer, both inside and outside the fence, has to be examined. Water
logging conditions, sewage dumps, pumping wells, etc. have to be identified and their influence on the
data generated examined. The corruption of the data, if any, because of the influences in the
neighbourhood should be examined and remedial actions suggested. This would refer to, for instance,
the growth of weeds and grass inside the enclosure and the branches of trees outside hindering
movement and maintenance work. Provisions have to be made for cutting weeds and grass once
every quarter and to prune the branches every year.
The cost of cleaning the neighbourhood of the piezometer should be worked out and the person who
can execute the job locally should be identified.

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2.4 INSPECTION OF FENCING
In some states, piezometers with DWLR have been enclosed with barbed wire fencing. The status of
the fence and the angle iron posts anchoring them need to be inspected. During the inspection, it has
to be ensured that the prevailing fencing is not only good currently, but will also not deteriorate before
the next inspection (see Figure 2.2).
Figure 2.2:
Inspection of fencing
The portion where the barbed wire is loose has to be identified. The maintenance requirements for
different tasks, including giving tension to barbed wire or replacement wherever required, and painting
or replacement of angle iron posts have to be identified. Barbed wire fencing would likely need to be
replaced more frequently in coastal areas/areas with polluted air as compared to other areas
Similarly, the angle iron posts, which are rusted, damaged and need replacement should be identified.
2.5 INSPECTION OF PROTECTIVE COVER
The piezometers equipped with a DWLR have a protective cover. In many states piezometers without
a DWLR do not have any protective cover. The design of the protective cover varies from agency to
agency. It is mounted on a brick masonry/concrete (some times pre-fabricated) platform anchored
through bolts and nuts (see Figure 2.3).
Figure 2.3:
Inspection of protection cover
During the inspection it has to be ensured, that the protective cover is in good condition, the top cover
is not rusted, and that the locked doors fully protect the instruments placed inside. It has also to be
ensured that rainwater does not stagnate on the top of the cover or seeps through the base of the
platform. The hinges should be in good condition. The Thermocol insulation inside the box should be
inspected and replacements suggested wherever required. The nuts and bolts that anchor the
protection box with the platform need to be oiled and greased regularly. The bolts will have to be
opened whenever maintenance works have to be carried out on the piezometer. Provision has to be
made for painting the protective cover and the board every two years in coastal areas/ areas with
heavy air pollution and in other areas every 3 years. The masonry platform also has to be inspected
for any development of cracks. The maintenance budget should include provisions for repair of the
platform every time the protective cover is removed.

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2.6 VALIDATING GEOGRAPHICAL CO-ORDINATES
The geographical co-ordinates corresponding to the location of the piezometer need to be validated
by the Data Centre Manager. The validations should be carried out with the help of the toposheet
(1:50,000 scale) brought to the site. Using the Brunton compass, locate the piezometer site accurately
on the toposheet.
The Lat.-Long. values should be read from the toposheet and the values verified. Validated
geographical co-ordinates should only be used for generating different types of maps and cross
sections.
Figure 2.4:
Verify the accuracy of the geographical
co-ordinates assigned for the piezometer
using Brunton compass and toposheet
An alternative method to determine the geographical coordinates is by using a GPS. The accuracy of
the GPS-system is consistently improving and already horizontal accuracy’s better than 100 meter are
possible.
2.7 INSPECTION OF OBSERVATION WELLS
The observation wells, which have been the main source of data on water levels and water quality for
the last three decades, need to be inspected. Declining water levels, drilling of bore-wells/ tube wells
as reliable drinking water source and the easy availability of power have resulted in discontinued
maintenance of the observation wells. In the absence of alternative sources, these observation wells
continued to be used as monitoring wells by the groundwater agencies.
Figure 2.5:
Spend time at observation well site,
ensure that data generated are useful,
reliable and representative
Inspection of the network should focus on the relevance of some of the observation wells (see Figure
2.5). The inspection should clearly indicate that the observation well continues to represent the
regional groundwater system that is being monitored and continues to generate reliable data. It has
also to be ascertained that the groundwater does not get contaminated with the surface run off,
sewage/ domestic waste and can continue to be used for water quality monitoring. The well platform
(in the case of domestic wells) and the stone/cement covering that prevents collapsible material from
falling into the well also have to be examined.
0.00 50.00 100.00 150.00 200.00 250.00 300.00
0.00
50.00
100.00
150.00
200.00
0.00 50.00 100.00 150.00 200.00 250.00 300.00
0.00
50.00
100.00
150.00
200.00

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2.8 INSPECTION OF SURFACE CASING OF PIEZOMETERS WITHOUT DWLR
The piezometers that have not been fitted with a DWLR in many cases do not have a protective box.
The top-casing pipe of the piezometer has in many cases a protective-casing pipe of galvanised iron
along with a cap. The protective cover is usually painted. It is exposed to the vagaries of the weather
and vandalism. The status of the protective cover has to be inspected, (see Figure 2.6).
Figure 2.6:
Inspect Piezometers without a DWLR.
Check protective casing, cap and masonry
platform, and identify maintenance
requirements
The necessity of painting and repairs if any has to be recorded. It has to be closely examined
whether the cap is able to cover the piezometer properly. The inspection team should recommend on
the required frequency of painting. In case the surface casing pipe is of PVC and is not protected with
a GI casing pipe, it has to be ensured that the PVC pipe does not provide scope for vandalism. The
necessity of proper fencing of the piezometer sites has to be examined. The status of the platform
also has to be examined.
2.9 CALIBRATION OF MEASURING TAPES
The first indicator of the health of the piezometer/observation well is the water level. Manual
measurement of the depth to water level should be carried out during the inspection. The manual
water level measurements should be recorded and compared with the DWLR water levels wherever
available or with the previous readings in the piezometers without a DWLR. The inspection team
should discuss with the officer in-charge of regular monitoring the type of method to be used for
manual water level measurement and calibration of the tape. Manual measurement, are considered
very simple and basic, and are usually taken for granted. The errors that creep in are ignored or
arbitrarily corrected. The different methods used for water level monitoring are discussed in the
following:
A popular method is the wetted tape (hold & cut) method. In this method a graduated steel tape is
used for measuring the depth to water levels. A weight is attached to the lower end of the tape. The
lower part of the tape is coated with chalk. The steel tape is lowered until part of chalked portion of the
tape is below water. The reading from the MP is noted. The tape is then pulled up and the wetted
chalk portion read. This reading is then subtracted from the measurement at the MP, which is the
actual water level depth. This is a very reliable method for water level measurement.
Figure 2.7:
Steel tape with weight

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Measurement of water levels using electrical dip tapes is another practised method. The dip tape is
battery operated and touching the water the indicator gives a beep sound/glowing light or both. Run
down batteries, poor contacts and cuts in the tape may give erroneous values. It has to be ensured
that the graduations marked on the tape are correct. It is recommended to purchase electrical tapes
from companies with proven accuracy and reliability. The graduations need to be validated using
more than one tape.
Manual measurement of water levels has to be taken up only by using a reliable tape. In the
piezometers fixed with a DWLR this has to be carried out once every month before down- loading the
data. Cross verification of the measurement of water levels more than once and adopting more than
one method should be made a standard practise, every time water level measurements are carried
out.
Figure 2.8:
Electrical dip tape
2.10 EXAMINATION OF WATER LEVEL HYDROGRAPHS
The field officers responsible for water level monitoring should be concerned about more than just
measuring water levels. They should be aware of the details of the aquifer system being monitored
and the formations penetrated.
The inspection team should reassure itself of the optimum performance of the piezometers in the
course of the inspection. Examination of the water level hydrographs of the concerned piezometer
along with the well section and design at the site itself should be part of the inspection. The response
of the water levels to recharge and discharge effects in the form of annual and seasonal cycles has to
be verified and, wherever required, compared with neighbouring wells which tap the same aquifer.
Figure 2.7 shows a typical DWLR hydrograph with rainfall and the lithological section less than
desired responses to different situations have to be taken up as cases for detailed field investigations.
Figure 2.7: Examine the response of water levels to recharge and draft. Have a good
understanding of the aquifer being monitored and the piezometer design. Identify
piezometers showing less than optimum response for further investigations.

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In such situations, it is likely, that the water level in the piezometer is not fluctuating simultaneously
with the piezometric head of the tapped layer, due to lack of response or time lag. The piezometer
could then be failing to provide the true information of the aquifer being monitored. Water level data
emerging from such piezometers cannot be considered as reliable. Such piezometers should be
subjected to detailed investigations for identifying the nature of the problem in the piezometer.
2.11 IDENTIFICATION OF MAINTENANCE TASKS BASED ON THE
INSPECTION
Based on the findings from the inspection, the team should be able to recognise the physical status of
the piezometer, as well as what is happening down the hole in the piezometer. When it becomes
difficult to recognise the sub-surface behaviour based on the available evidence, additional tests may
have to be conducted to find out whether the piezometer is operating efficiently or maintenance has
be carried out. The inspection team should be able to build a mental picture on the situation down-
hole by:
• measuring the depth of the piezometer,
• measuring the water levels,
• recording the obstructions met with while measuring the depth of the piezometer,
• examining mirror observations reflecting light down the piezometer, and
• examining water level hydrographs.
The field inspection team, basing itself on these checks, should be able to infer whether the
monitoring structure can generate accurate data. The results of the check should be used to pick up
indicators of deterioration likely to set in. Then the inspection team should be able to give expert
advice on the different standard maintenance and preventive maintenance tasks to be carried out. In
the case of non-representative monitoring structures, decisions have to be taken on the remedial
actions or alternative options recommended. The inspection team has the professional responsibility
of ensuring continued efficiency of the different structures that are part of the network.
The inspection team should report the observations in the prescribed inspection report. A sample
format of the inspection report is given in Table 2.1, which may be customised according to
requirement. The inspection report on individual observation wells and piezometers should be sent to
the concerned Data Processing Centre In-charge for information and necessary follow-up action.
The inspection findings should form the guidelines for additional field tests to be carried out and
maintenance activities initiated. Maintenance work should be carried out at the appropriate, to ensure
systematic generation of authentic groundwater data.

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Annual Operation and Maintenance Inspection Report
Date:………………………………………………………………… District: ……….…………………………………………….………
Agency: ……………………………………………………………………………………………………...…………………….…………….
Mandal/Block: …………………………………………….……… Village: ………………………………………………………….…..
Longitude: ………………………………………………………… Latitude: ………………………………………………….………..
R.L.: ……………………………………………………….……….. M.P.: …………………………………………………………………
Well No.: ………………………………………………..…………. Well Type: ………………………………………………………….
Total Depth: ………………………………………………………. Aquifer tapped: ……………………………………………………
DWLR Details, Make…………………………………….……… S. No.: ……………………………………………………………….
Capacity Range: ………………………………….………………………………………………………………………….…………….…..
Installation details: …………………………………………………………………………………………………………………………….
Inspection team members: ………………………………………………………………………………………………………………….
Parameter Query Response
Recommended
Action
Approachable throughout the year/
seasonal
Areas of poor approachability
Periods of poor approachability
Alternative routes, if any
Period for which data generation will be
effected??
Scope for identifying a local observer
Approachability
Solution for ensuring continuous data
generation
Status of the neighbourhood of the
piezometer
Does anything in the neighbourhood
affect data generation
Details of influencing conditions
Distance of the influencing zone from
the piezometer site
Will the data generated be influenced
seasonally or throughout the year
Has the influencing zone come up after
the establishment of the piezometer
Is there a possibility of data corruption
Neighbourhood of
observation site
Does the data need any correction
Status of the
Name Board
Does the name board need any repair.
Does any detail mentioned on the board
need correction or addition
Is the well currently used
Status of
Observation Well
Is the water reported to be potable

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Parameter Query Response
Recommended
Action
Is the well reported to go dry
Is there any physical damage to the well
Does the monitoring well represent a
regional aquifer system
Does the well platform protect it from
entry of surface seepage
Is the fencing completely protecting the
piezometer from vandalism
Does the fencing need any main-
tenance
What length of fencing needs tightening
What length of fencing needs
replacement
Does the angle post need any
maintenance
When was the angle post painted last
time
Status of the
Barbed Wire
fencing around
the piezometer
How many angle posts need
replacement
Is there grass and weeds around the
piezometerStatus of the area
besides the
piezometer
Are there any branches of trees
covering the piezometer which need to
be removed
Is the protective cover anchored with
the cement plat-form
Does the protective cover show any
rusting
Does the protective cover need painting
Are the doors of the protective cover
completely protecting the instruments
inside
Does the protective cover need repairs
or replacement
Status of the
protective cover
of the piezometer
Do the locks need replacement
Has the masonry platform developed
major cracks
Does the masonry platform allow
seepage of surface water
Status of the
masonry platform
around the
piezometer
Does the masonry platform need
repairs or replacement
Is the casing pipe protected and is the
cover attachedStatus of casing
pipe exposed to
outside Does the casing pipe require painting
or other maintenance
Frequency of manual water level
measurementsWater Level
measurements Frequency of DWLR measurement

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Parameter Query Response
Recommended
Action
Does the water level hydrograph clearly
bring out annual/seasonal/
diurnal cycles
Is there a reason to believe that the
water level hydrograph is not
responding optimally
Does the depth of the piezometer show
any reduction
Depth of the
piezometer Does the diameter of the piezo-meter
show any reduction
Observations of the team:
Recommended follow up work if any
Table 2.1: Example of Annual Operation and Maintenance Inspection Report
3 FOLLOW-UP OF FIELD INVESTIGATIONS
3.1 GENERAL
The field investigation report should clearly mention the number of observation wells that need
replacement or repair. The number of piezometers that need additional investigations have to be
identified. The report should also suggest the type of follow-up studies to be taken up (see Figure
3.1).
Field Observation Inference Follow up Technical Task Remarks
Geophysical bore-hole logging
Diameter
Caving zone
Corroded
casing/screen
Depth of the piezo-meter
shows reduction
Siltation due to caving from
weaker zones or break in the
casing/screens
Flushing - Development Restore the original
depth
Cleaning through pumpingClogging of fractures/screens
Development
Remove clogging
Siltation Flushing - Development Restore the original
depth
Steep decline in water levels Piezometer deepening or replacement
Water columns beyond
measuring range of DWLR
Replace DWLR or change the
transducer depth
Optimal measuring
range
Non-responsive water
levels
Reduced Hydraulic
connection with the aquifer
Hydro-fracture Improved hydraulic
connection
Growth of other obstructions For growth of roots in the bore-wells,
design appropriate tools to clean the
piezometer walls of the roots
Difficulty in lowering the
measuring tape
Other obstructions Flushing
Restore the original
piezometer design
Table 3.1: Summary of field investigation report (an example)

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In the annual budget of the HIS an imported competent is operation and maintenance cast of the
observation network. In table 3.2 a list of items is presented to be considered for budgeting.
Operation and Maintenance Estimates
Well No. …………………………… Village…………………………………
Item No. Item Qty. Rate
(in Rs.)
Unit Amount
(in Rs.)
1 Cutting of branches Job/year
2 Repair approach (wherever required) Job/year
3
Clearance of grass, weeds and branches (every six
months)
Job/year
4 Giving tension to barbed wire fencing Job/year
5 Replacing barbed wire fencing Job/year
6 Replacing broken angle posts Lump Sum (LS) Job/year
7 Providing ‘U’ nails and barbed wire etc. (LS) 6 Kgs.
8 Painting the protective cover (every 2 years) Job/year
9 Replacing the protective cover (wherever required) Job
10 Repairing the masonry platform (wherever required) Job
11 Replacement of pad-locks (every year) Unit
12 Painting the outer casing pipe (wherever required) Job/year
13 Strengthening the casing pipe (wherever required) Unit
14 Sounding the piezometer (every year) Job/year
15 Geophysical down hole logging (wherever required) Job
16 Development through pumping (every three years) Job
17 Pumping tests (every 5 years) Job
18
Cleaning of piezometer using cutting tool (wherever
required)
Job
19
Cleaning the piezometer using compressor (every 5
years)
Job
20 Hydro-fracturing (wherever required) Job
21 Deepening the piezometer (wherever required) Unit
Total Estimate towards Operation & Maintenance
Table 3.2: Table for preparation of Operation and Maintenance Estimates (an example)
3.2 DOWN-HOLE GEOPHYSICAL LOGGING
Down-hole geophysical logging should be carried out on piezometers that are suspected of siltation,
deviations, incrustations and bacterial growth that need confirmation. Logging could also be used to
examine the well design and check for breakage in the casing pipes or screens. The borehole logging
tools can be chosen from the (see Table 3.3 and Figure 3.1).
Systematic planning for
O&M will call for
preparing the O&M
budget with adequate
allocation of funds for
the different
components. Listing of
the different activities
under O&M and repairing
an estimate is a pre-
requisite

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Figure 3.1: Bore-hole logging tools
Type of Logging Information Obtained
Calliper Diameter of the borehole, permeable zones and type of clay, casing features, casing leaks, screen
position and build up, if any
Spontaneous potential Lithology, permeable zone, formation water quality
Resistivity Lithology, permeable zone, layer resistivity, thickness, formation water quality
Natural gamma Lithology, clay zone, water production zone, layer thickness
Temperature Permeable zone, casing leaks, fluid flow and water level
Conductivity Casing leaks, permeable zones, formation water quality and water level
Table 3.3: Summary of logging types and information obtained
Interpret the logging results carefully for detecting changes in the piezometer diameter, zones that
probably show caving, build up in the piezometer due to siltation, position of the screens, break in
casing or screen joints or leakage in casing joints.
The results of the logging should be the basis for deciding the follow-up activities for revitalising poorly
performing piezometers.
3.3 PUMPING OF MONITORING STRUCTURES
The simplest method of sustaining the performance of observation wells/piezometers is through
pumping. In this method, the monitoring structure should be pumped at a discharge rate in excess of
the potential discharge. During pumping the effort should be to over-pump the monitoring structure.
Pumping would remove the storage water/ replace stagnant water as well as help in limited removal of
fines in the case of piezometers.
In privately owned dug wells used for domestic purpose, it might not always be possible to carry out
the pumping. However, this should not be a problem with the agricultural wells used for monitoring.

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In the case of piezometers pumping may not always help in cleaning of the piezometer. This has to be
followed up by other steps such as using compressors, drilling rig, jetting and in limited cases even
hydrofracturing. Piezometers throwing up a big amount of fine materials during pumping run the risk of
getting spoiled because of sand locking in the pump (see Figure 3.2)
Figure 3.2:
Typical sub-surface section with submersible
pump
Cleaning of piezometers through pumping using submersible pumps needs to be carried out as a
regular maintenance procedure. The frequency of pumping will vary from piezometer to piezometer
depending upon its performance. Regular checking of the specific capacity will indicate the need for
cleaning through pumping. Declining of the specific capacity should be considered as an indication for
carrying out the pumping. Every piezometer has to be pumped once every three years as part of
development. In many cases the piezometers will come up for pumping as part of water quality
sampling. However, this should not be considered as a cleaning technique as the water quality-
sampling pump is of low discharge. Cleaning through pumping should be considered as an
independent process.
The procedure to be adopted is to pump the piezometer using a suitable submersible pump. The
pump capacity, discharge and depth of lowering should be guided by the yields obtained during
drilling/development of the piezometer. Preferably, the pump should be placed above the screen in
the case of unconsolidated rocks or against the deepest water-yielding zone in the case of
consolidated rocks. The procedure should involve pumping of the piezometer in multiple spells. Water
levels and discharge have to be monitored during the tests. Initially, the piezometer should be
pumped till the water level drops close to the suction limits. The initial water is likely to be muddy with
some fines. After the pumping is stopped the piezometer should be allowed to recover. In many
situations it is likely that the pumping discharge and water level will start rising compared to initial
levels due to the process of development. This should be followed by another spell of pumping and

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recovery. The process of pumping and recovery should be continued until the pumped water is clear
with no fines, and till the water level rise is stabilised.
3.4 CARRYING OUT AQUIFER PERFORMANCE TESTS
After cleaning and development through pumping it would be advisable to carry out systematic aquifer
performance test for estimating the aquifer parameters. The change in the characteristics of the
groundwater reservoir and the aquifer parameters over time, need to be understood. This would be
beneficial in improving the computation of groundwater resources (see Field Manual Part III for a
description of Aquifer Testing). The testing can be carried out using a mobile pumping test unit as
shown in Figure 3.3.
Figure 3.3:
Mobile pumping test unit
Step-draw-down test and constant discharge tests can be carried out on the piezometer. These are
discussed below:
3.4.1 STEP-DRAW-DOWN TEST
The step-draw-down test should be performed on piezometers constructed in the un-consolidated
formations, primarily to understand the efficiency of the piezometer. An efficient piezometer with
minimum well loss would reflect a good hydraulic connection between the aquifer and the piezometer,
thereby indicating that the piezometer is reflecting the regional aquifer system very well.
In the step-draw-down test the piezometer should be pumped in increasing levels (steps) of pumping
discharge. For each step water levels have to be monitored systematically until the water level
reaches a steady (or near-steady) state. Every step has to be sustained for a period of 60 -100
minutes or until the drawdown in the well ceases to increase any further. The analysis of the
discharge in comparison to the draw-down data will permit estimation of aquifer and well loss. This is
the base on which a good hydraulic connection of the piezometer with the regional aquifer can be
inferred.
3.4.2 CONSTANT DISCHARGE TEST
A pumping test with a constant discharge needs to be carried out for estimating the aquifer
parameters of the tapped aquifer. The test involves pumping the piezometer at a constant discharge
rate. The water level changes need to be monitored systematically in the piezometer as well as in any
well in the neighbourhood tapping the same aquifer. An analysis of time-distance-draw-down data
provides estimates of the aquifer parameters.

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The pumping tests are not an essential method in the process of development. However, they help in
understanding the aquifer system being monitored as well as in recording any changes in aquifer
characteristics over time.
3.5 DEVELOPMENT OF PIEZOMETER
Declining performance of the piezometers will be the result of accumulation of fines in the fractures,
mineral scale, slime bacteria, silt or sand build-up, changes in the aquifer or the geological area
around the piezometer. With the right equipment and techniques, these can easily be removed from
the piezometer. Other problems, such as large physical obstructions, extensive damage to the well
screen, or changes in the aquifer due to natural events may not be so easily resolved.
Piezometer development should be undertaken for removing unwanted materials and improving the
flow of the surrounding aquifer to the piezometer. Development should physically remove silt, clay,
fine sand, scale, and befouling and correct any deficiencies during construction. This can be
accomplished through jetting, surging and/or airlifting. Development will clear unwanted materials
from the piezometer and its surroundings, and serve to integrate the piezometer into its environment.
No matter how carefully a piezometer has been designed and constructed, over a period of time
development is essential to ensure its efficiency and water quality.
Development to be carried out on piezometers drilled in consolidated and unconsolidated formations
must be different. In the latter case, development of the piezometer would require movement of a
drilling rig to the piezometer site. This needs some preparatory work including site preparation,
removal of fence, clearing of bushes and branches of trees, removal of DWLR and protective works.
The drilling rig has to be positioned carefully to prevent damage to casing and well assembly. Details
of the piezometer including type and combination of casing used, the total depth of casing and depth of
water bearing zones should be made available to the development unit.
In tube well designs jetting is the most effective way to clean the well screen and rehabilitate the
surrounding aquifer. Jetting involves shooting jets of water through the screen and into the formation
while simultaneously pumping the dislodged materials out of the well. The water column should be
agitated effectively after the jetting through spells of airlifting. Chemical solutions can also be used for
clearing the drilling mud clays, bentonite mud, encrustations, bacterial growth etc. Fresh water mixed
with sodium tripolyphosphate should be circulated through the screen. The well should be allowed to
set until the polyphosphate can effectively work on the mud cake/ clay masses and desegregate
them. Simply poured into a piezometer, the chemicals will not be effective; they need to be followed
by physical cleaning. Chemicals that are hazardous and also change the quality of the water should
never be used. Before using chemicals, a water quality analysis has to be carried out and any major
changes in water quality subsequent to chemical treatment should be clearly recorded. Such
piezometers should not be used for drawing major inferences on groundwater quality characteristics.
3.6 REMOVAL OF ROOTS
Special cutting tools have to be made for cleaning the piezometers where growth of roots is seen.
While designing the cutting tool, piezometer details such as its diameter, the lithology of the formation
and the nature of the water bearing formation have to be kept in mind. The drilling rig should be
properly positioned keeping in mind the deviations in the piezometer. The cutting tool has to be
lowered below the surface casing after which the walls are cleaned with a rotary movement. The
cleaning should be stopped 1 metre from the sounded depth. The cutting tool should be pulled out
and replaced by the button bit, and cleaned to the bottom. Airlifts should also be carried out with a
compressor. Occasionally, the cutting and air-lifting should be stopped and the piezometer allowed to
recuperate before repeating the process. Airlifting has to be carried out for longer periods against the
water bearing zones.

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3.7 HYDROFRACTURING
Hydrofracturing should be considered as a technical option only for reviving piezometers that show
clogging of fractures or those piezometers that show limited hydraulic connection with the aquifer that
is being monitored. Hydrofracturing can be carried out in consolidated rocks especially in those
piezometers where complete development cannot be achieved. Based on the logging data the aquifer
should be isolated using packers and hydrofracturing should be carried out (Figure 3.4). Geophysical
down-hole logging is a pre-requisite before hydro-fracturing, for isolating the aquifer being monitored.
In hydro-fracturing pressurised water is injected to clear the fines from the fractures (Figure 3.5). Care
has to be taken to see that new fissures are not created in the process of hydrofracturing. The
process involves injection of water into the fracture zone and the fines are washed out. Specialised
infrastructure is required for carrying out hydrofracturing and is available with the agencies involved
with groundwater development for rural water supply. Care has to be taken to see that the water
injected matches with the quality of water in the piezometer.
Figure 3.4: Schematic representation of hydrofracturing procedure
Figure 3.5:
Inflated packer and hydrofracturing procedures

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The steps involved in hydrofracturing are:
• Study the lithological log of the piezometer,
• Identify the aquifer position. Carry out geophysical down-hole logging and decide on the aquifer
where water is to be injected,
• Lower a dummy tool to check the verticality and diameter of the piezometer to ensure that the
piezometer has not collapsed,
• Carry out a discharge test using a submersible pump for finding the pre-fracture yield test,
• Fill the piezometer with potable water so as to remove the air from the piezometer and isolate the
fracture zone using the packer. The packer should be inflated with the hydraulic pump,
• Inject water into the fracture using a high-pressure water pump. The injected water will start
working into the fracture. Continue the propagation for 5-10 minutes. Repeat the injection for
shorter spells, and
• Carry out post fracturing yield tests. Repeat the logging for comparing the pre- and post-
fracturing changes in the formation.
3.8 DEEPENING OF PIEZOMETERS
Deepening of the piezometers in consolidated formations can be taken up in select cases where the
piezometers show partial penetration, seasonal drying up or large declining water levels. The
deepening should be undertaken after ensuring that the tapped aquifer is extending deeper.
Geophysical resistivity surveys should be carried out prior to deepening. Before deepening, the
deviation of the piezometers has to be examined. Piezometers with large deviations should not be
considered for deepening. The diameter of the bit used should be considerably less than the smallest
diameter of the piezometer. Deepening of piezometers will be risky if the targeted aquifer is not clearly
demarcated. During deepening, there is a potential danger for the piezometer to collapse.
4 MAINTENANCE OF DIGITAL WATER LEVEL RECORDERS
Although the DWLRs were selected for proven reliability, they cannot be left without attention. The
data return, i.e. the amount of collected data, and the data quality can be adversely affected by many
causes resulting in damage and/or accuracy deterioration. Damage may be caused by vandals,
rodents, collapse of the well, flooding, lightning strikes, insects, corrosion, fungi, moisture ingress,
battery leakage, operator error and unfortunately many more causes. The accuracy may deteriorate
due to any of the above mentioned damage causes but also due to drift of sensor and electronics,
slippage of the suspension, change in water density, blockage of the air vent system, corrosion,
sedimentation or salt deposition on the pressure sensor.
Unavoidably, problems will arise during large-scale deployment of DWLRs. To avoid severe loss of
data and / or deterioration of the data quality, proper measures have to be taken. Implementation of a
performance-monitoring scheme is one of such measures. The performance-monitoring scheme aims
to limit the duration of data loss, if any, and to collect reference data for validation purposes. The
sooner an instrument defect is detected, the less data might be lost. Therefore, the performance-
monitoring interval should be as short as practical.
The quality of the validated data depends on the accuracy and reliability of the DWLR and also of the
accuracy and amount of the reference data. Hence, also for validation purposes the performance-
monitoring interval should be short. Moreover, the effect of errors caused by drift, e.g. of the clock, of
the pressure sensor or of the suspension can be limited by timely verification and adjustment, if
required.
The performance-monitoring interval could be set in such a way that the drift errors are effectively
limited to acceptable margins and the chances of large data loss are minimised. Hence, a stable and
reliable instrument may be visited less frequently than a drifting instrument and / or risky piezometer
well. Initially, the performance-monitoring interval may be as short as possible to gain experience with

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the individual instruments and piezometer wells and to build adequate performance statistics. An
assessment of the statistical data may result in an adjustment of the performance-monitoring interval.
4.1 REQUIREMENTS FOR DWLR PERFORMANCE-MONITORING
The following general requirements have to be met:
• The piezometer well is properly functional
For the water level reference measurement a level (dipper) tape is used. In order to get a
reproducible result, the well should have a reference point that is used for all water level
reference measurements. The reference point should be clearly marked for unambiguous
identification and it should be acute-angled for accurate measurement. All measurements, both
by tape and by DWLR should be referenced to that point.
The well interior should be easily accessible for the level tape, there should be no obstructions
that may hamper the movement/use of the tape. The level tape can deliver the required accuracy
only if it is vertical, without bends along obstructions.
• The proper reference tools are available
The time reference is derived from the clock of the DRS, the latter is synchronised with the
national time reference or with GPS time. For verification of level measurements, accurate level
tape is needed. The level tapes should have an accuracy that effectively exceeds the DWLR
accuracy, at least by a factor of 2. Comparison of various level tapes is quite instructive.
Differences of 5 mm/m are common. The level tape may also be verified against an electronic
distance meter, e.g. one that is integrated in a precision 'total station'.
• The operator is properly trained
Operators who execute the performance monitoring should be aware of the objectives for the
performance monitoring. Moreover, the operator should be fully conversant with the DWLR and
DRS.
• A performance-monitoring protocol is available
The performance monitoring at each station should be executed in compliance with a formal
protocol, this to collect all the required data in a standardised format which allows comparison of
previous checklists pertaining to that station.
• A station logbook is available
The logbook of a station is the collection of all checklists pertaining to that station plus all other
documents related to the performance of that station, i.e. it contains all the historical information
pertaining to the station. From the historical data the operator may learn what aspects require
special attention, e.g. zero drift (cable grip check), moisture ingress (desiccator replacement),
communication problems (spare cable required).
It is recommended to prepare and implement an operation and maintenance plan catering for:
• reference measurements,
• system performance monitoring,
• data retrieval,
• preventive maintenance, and
• fault handling.

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Some activities can be executed by field staff, others require thoroughly trained staff equipped with
DRS.
4.2 EXECUTION OF PERFORMANCE MONITORING
Performance monitoring should be part of standard procedures. Initially, after-set-up and
commissioning of the instrument, performance is monitored rather frequently, later, after assessment
of the collected data the monitoring interval may be optimised for best result at minimum effort and
costs.
Especially in the first year of deployment, when the DWLR properties are not fully known yet, the
performance should be monitored by manually taking accurate (better than 0.01 m) reference
observations. Every important aspect of instrument performance should be monitored on a routine
basis. The performance monitoring should be continued during the full operational lifetime of each
DWLR. The performance-monitoring interval may be adjusted according to the findings. That is, if the
DWLRs prove to function reliably, then the frequency of monitoring may be decreased to optimise
cost versus data quality and data return.
Data retrieval should be done at an appropriate interval, possibly in combination with preventive
maintenance.
Preventive maintenance merely concentrates on keeping the instrument clean, changing desiccant
timely and replacing batteries. Some maintenance aspects, like replacing of batteries in sealed
enclosures, may only be executed by specialists. In particular in piezometer wells, featuring high salt
concentrations, regular checks for corrosion and deposition of salts are required.
Service visits are made to the piezometer well to check the proper performance of the DWLR, to
collect reference data, to apply servicing to the instrument and to retrieve recorded data.
The data return and the quality of a water level collection network strongly depend on operational
procedures. Frequent service visits by properly trained and dedicated service engineers are essential.
The services visits pursue following goals:
• Data recovery
Off-loaded data are to be copied immediately to an independent medium which is kept in the
station office. The primary data are transported to the custodian office and loaded into the data
storage and processing system and subsequently backed-up.
• Supervision of procedures and station operation
All stations have one or more gauge readers. These aides have to be properly instructed, trained
and guided. Careful annotation procedures as well as proper time keeping, including timely gauge
reading, must be frequently reviewed. The purpose of staff gauge installation at DWLR stations,
and reading of the same, is to maintain a double check against data loss due to any mishap.
• Acquire quality assurance data
In particular, manual readings should be taken during each service visit to the station,
simultaneously with DWLR reading. This is one of the keys for data quality assurance and
validation.
• Formulate recommendations and directives for local operator
In case of found irregularities in the systems functioning as well as applied procedures appropriate
steps are to be taken.
During service visits, the stations are checked for proper functioning, and procedures and factors that
might jeopardise data yield and quality are appraised and modified. Normal operation and maintenance
works during a service visit include:

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• administration and logging,
• organisation and preparation,
• performance check,
• ventification, and
• maintenance procedures.
The activities are elaborated in the following sub-section.
4.2.1 ADMINISTRATION AND LOGGING
This involves the following activities:
• For each station a comprehensive history file should be maintained,
• For each DWLR a comprehensive history file should be maintained, and
• All findings and activities related to the field stations, instruments used, observations made, and
data collected should be logged into history file.
After each service visit, a Service Report is made, giving the details of the technical status of the station,
its functioning, and any particulars of interest regarding data collection, data quality, continuity, etc. is
necessary.
4.2.2 ORGANISATION AND PREPARATION
The preparation of a performance check/site visit should be the same as described in Part IV of the
Field Manual. The only exception is that only spare DWLRs have to be carried and not a new one for
each piezometer that is visited.
4.2.3 PERFORMANCE CHECKS
Annotate all checks and their results in the station visit sheet, much like with the other activities and
observations. Any remedial action should take place after instrument verification. Do not pull the
instrument out of the water because this may affect its reading and / or hamper trouble shooting. The
following checks have to be carried out:
• Check the local conditions.
The local conditions are assessed, in particular for changes which may affect the functioning of
the equipment and the accuracy of the collected data,
• Check the piezometer housing for damage, tampering.
As the piezometer housing protects the DWLR and the well against external hazards, immediate
action should be taken in case the housing is found to be damaged.
• Check the well for damage, tampering.
• Check the main and safety suspensions of the DWLR.
• Check if the marking of the reference point on the well head is still in good condition.
• Check for possible slip on the main suspension.
• Check the safety wire and its fixing.
• Check the suspension cable for damage, kinks etc.
• Check the communication connector for damage, dirt, moisture.

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• Check the air-vent for damage, dirt, moisture, replace hydrophobic filter if required.
• Check the desiccator for remaining capacity/saturation, replace if saturated or the remaining
capacity is not sufficient to cover the time to the next service visit.
• Check the state of maintenance of the DWLR station.
Such simple tasks as occasional painting of the housing, internal cleaning of enclosures, execution
of simple repairs are easily overlooked. However, a well-maintained station will be less prone to
unexpected failures, leakage, animal bite etc. Also for the local staff it must be more enjoyable to
work in conveniently arranged environment than at a disorganised station.
• Annotate all observations/checks and any other observation that possibly may be of interest for
DWLR operation, data validation and/or trouble shooting.
4.2.4 VERIFICATION
Verification includes the following steps:
• Retrieve the new data records from the DWLR.
• Take a manual water level observation with high accuracy level tape. For reproducibility reasons,
preferably always the same level tape is used.
• Annotate reading, time, observer name, and level tape identification (which tape was used).
• Do an instantaneous DWLR level reading, annotate DWLR reading, date and time on the log
sheet. The interval between instrument reading and manual observation should be kept short.
• All readings and observations should be in meters. The resolution of readings and observation
should be 1 mm.
• The instrument reading should be relative to ToC. If the instrument gives level as head, i.e. water
level above the sensor, then the ToC value is obtained by subtracting the head from the
installation depth (relative to the well head). The ToC value should be positive and increase with
falling water level, it is equivalent to a manual observation.
• Verify both manual observation and instrument reading for consistency.
• Check the DWLR clock against the DRS clock: make log sheet entries of DWLR and DRS time.
• Synchronise the DWLR with the DRS clock: make log sheet entries of DWLR and DRS time.
Errors in the setting of the DWLR’s system clock result in erroneous time labels in collected data.
The higher the water level rate of change the more important the clock’s setting and associated
time keeping is.
• Do a DWLR battery voltage reading, make an entry in the log sheet, and assess the remaining
capacity
Nearly exhausted batteries have to be replaced by new ones. Remaining battery capacity must
be more than adequate to keep the DWLR fully operational up to next service visit, this including
a practical safety margin.
• Do not erase the DWLR data. First the retrieved data have to be stored and reliably backed up in
office. It is recommended to keep all the data on the DWLR. This is most easy if the logger
memory is organised in a ring structure. The ring structure implies that when the memory
becomes completely filled, the oldest data gets overwritten by the new data.
Under normal conditions, the retrieve function should automatically retrieve the new data only.
The already retrieved data does not have to be retrieved again, unless data were lost or
corrupted during transport / transfer to data storage in office. In that case, there should be an
option to retrieve data starting at a user-defined date: that is the date of the latest correctly
transferred data, or retrieve all the recorded data.
• Verify the internal consistency of the time series, e.g. by displaying a time series graph. This
graph should display sufficient detail to make these verifications. For that the level and time
scales should be adjustable and zooming-in on particular data events should be supported by the
software.

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• If any flaws in the data or the functioning of the DWLR are detected then these have to be
documented and reported immediately. Prior to departing, the DWLR operator may have to
execute some trouble shooting tests and trials on site. Refer to the DWLR manual for details.
The instrument should not be opened at that occasion. Returned in office, the flaw has to be
reported and immediate actions have to be organised to remedy the DWLR problem.
After finishing the performance checks, the post-installation procedure should be followed to bring the
station to a normal working state in a coordinated way.
4.2.5 MAINTENANCE PROCEDURE
Proper first line maintenance should be executed, including:
• Cleaning of cable, connector and sensor.
The cable, communication connector and the sensor should be kept clean. The exterior of the
communication connector should be cleaned during each data retrieval visit.
The cleaning of the sensor and suspension cable should be executed whenever the DWLR is
removed from the well, e.g. when water quality samples have to be collected and for trouble
shooting purposes.
• Replacement of hydrophobic filter and / or breather bag.
This is executed during normal data retrieval visits whenever applicable.
• Replacement of desiccator.
This is executed during normal data retrieval visits whenever applicable.
• Painting.
Painting of housing should be scheduled in a general maintenance plan. However, in case
excessive corrosion is reported the painting should be executed at the earliest occasion.
• Oiling of locks.
This is executed during normal data retrieval visits whenever applicable.
• Repair of damage.
In case damage is reported immediate action should be taken.
• Watch and Ward Staff.
The payment of any watch and ward staff if arranged should be executed in compliance with the
contract. Delays should be avoided.

28. Field Manual – Geo-hydrology (GW) Volume 4 – Part VIII
Geo-hydrology March 2003 Page 26
Checklist for Maintenance of DWLRs
Problem Handing
- reporting
- assessment
- action
- follow up
- monitoring
- testing
Role of Vendor
- knowledge
- replacement of defective units
- repair
- cable extension
- training
- trouble shooting
- AMC
Spares
- spare units
- spare suspension accessory
- spare batteries for DWLR and DRS
- spare communication cables
- required numbers
- where to store
- post AMC
Monitoring
- Investment costs
- AMC costs
- Operational costs
- Costs of data handling
- Number of piezometer wells
- Number of instruments procured
- Number of instruments installed
- Instrument months
- Number of defective and repaired instruments
- Time between occurrence of defect and re-installation of instrument
- Number of defective and replaced (beyond repair) instruments
- Time between occurrence of defect and installation of replacement
instrument
- Number of instruments connected to MSL
- Maintenance interval
- Re-calibration interval
- Battery replacement interval
- Desiccator replacement interval
- Hydrophobic filter replacement interval
- Manual observation interval, difference between manual/instrument
observation
- Months of data retrieved (functional data collection period per instrument)
- Months of valid data, per instrument
- Months of invalid data, per instrument
- Annual graph of retrieved data (levels/temperature), per instrument
Table 4.1: Checklist for maintenance of DWLRs