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 IV
DWLR COMMISSIONING

2. Field Manual – Geo-hydrology (GW) Volume 4 – Part IV
Geo-hydrology March 2003 Page i
Table of Contents
GENERAL 1
1 DWLR COMMISSIONING 2
2 MONITORING STRUCTURE 2
3 REDUCED LEVELS 2
4 INSTALLATION STEPS 3
4.1 GENERAL 3
4.2 PRE-INSTALLATION REQUIREMENTS 3
4.2.1 ACCESSORIES FOR INSTALLING A DWLR 4
4.2.2 SPARES 4
4.2.3 DOCUMENTS 4
4.2.4 CHECKS PRIOR TO DEPARTURE 5
4.3 INSTALLATION 6
4.3.1 PREPARATION 6
4.3.2 SET-UP 7
4.3.3 POST-INSTALLATION 7

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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 DWLR COMMISSIONING
Before a DWLR can be effectively put into service, the following prerequisites have to be met:
• it has to be ensured that the piezometer can serve as a dedicated monitoring structure that is
tapping a single aquifer and the water level in the piezometer responds effectively to all the
changes in the system,
• the DWLR should have been successfully tested,
• the filed officers and engineers should have been adequately trained,
• a DWLR operations procedure should have been designed and implemented, and
• for spatial comparison of water level data originating from different piezometers, the reduced
level survey (msl) connecting the different piezometers to the same datum should have been
completed.
The DWLR commissioning includes installation of the instrument and putting it to work. Preferably, the
supplier participates during the first commissioning of new DWLRs. The purchasing agency should
strive to acquire the necessary knowledge and become an expert user organisation.
2 MONITORING STRUCTURE
Installation of a DWLR requires a well or piezometer of appropriate diameter, such that the lowering
and raising of the instrument is possible. Normally, and depending upon the chemical quality of
groundwater and its corrosive nature, piezometer casing pipe made of mild steel (MS) or PVC are
used. The diameters range from 70 mm to 150 mm. The smaller the piezometer diameter, the better
the response to changes in pressure head of the aquifer will be as, the storage effect will be
negligible. The piezometer casing-pipe protrudes to 0.5 m above ground level in order to avoid
ingress of soil, dirt or storm water. The top of well / piezometer casing forms the reference point and is
normally connected to mean sea level (MSL). The actual reference point, e.g. in the north-east corner
should be clearly and unambiguously marked by colour paint. The top casing pipe is completely
grouted with cement to provide firm grip to the casing pipe. In the case of installation of a DWLR in an
open dug wells a small diameter PVC casing of 6” should be placed in the well, suitably anchored and
the DWLR installed within the casing pipe. This will reduce the storage effects.
The main purpose behind the installation of DWLR’s should be to systematically monitor closely all
the changes in the over a long period so as to assess the maximum and minimum levels, the
fluctuations with time and the response to recharge / discharge conditions in the aquifer. Further, data
are required on aspects such as recording of tidal effects, pumping tests, data collection, etc.
Based on the details of depth to water level, seasonal fluctuation, long-term fluctuation, critical
drought period level of the water table, and a minimum submergence of the pressure sensor below
the water table, the cable length is to be established.
3 REDUCED LEVELS
The pressure sensor type of DWLR measures water level fluctuation relative to its internal reference.
Usually, the reference is the membrane of the pressure sensor. For most hydro-geological
applications the water level data have to be related to specific hydro-geological units. For a proper
comparison, all these data have to be related to the same reference level (datum), usually Mean Sea
Level (MSL).
On the piezometer well a reference point is identified as the Measuring Point (MP). In order to get a
reproducible result, the reference point should be used for all water level measurements, both by tape

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and by DWLR. The reference point should be clearly marked for unambiguous identification and it
should be acute-angled for accurate measurement.
By levelling, the piezometer reference point is connected to (MSL) benchmarks, e.g. GTS
benchmarks or other benchmarks of established accuracy. It should be verified that the levelled
reference point, which is connected to MSL, is the same as the reference point used for water level
measurement. For effective use, the piezometer/well reference point should be on top of the well head
and easily accessible as reference for manual observations by 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 MP should be accurately
measured from the ground level and the height of the MP recorded in the database.
4 INSTALLATION STEPS
4.1 GENERAL
The pressure sensor is lowered in the piezometer on its suspension / electrical cable to the desired
depth. The top end of the cable is hooked to a special clamp on the well head, firmly keeping the
sensor in position at the desired depth. A safety wire should be attached to avoid loss of the
instrument due to handling error or failure of the main suspension. On the well head a protective cover
of appropriate size should be made to enclose the well head and all DWLR parts. Within the case the
surplus cable may be stored. During data retrieval and other communications with the DWLR, the
communication connector is attached to the DRS. Therefore, the connector should be easily
accessible.
During the first month the recording interval should be 1 hour, later on the interval could be adjusted
according to the temporal water level fluctuations in the piezometers, e.g. to 3, 6 or 12 hours as per
the requirement.
The field officers responsible for water level data collection should be furnished with a detailed
operation protocol as well as clear-cut trouble shooting guidelines. All DWLR operators need rigorous
training to make them fully acquainted with the working principle of DWLRs.
All piezometer related activities, findings and observation should be entered in the piezometer history
log. The DWLR related activities, findings and observations should be entered in the DWLR history
log. For both history logs all relevant particulars should be included as applicable, e.g. location details,
name and identification code, RL of reference point, observer’s name, date and time, instrument serial
number and many others.
The manual gives details of the installation steps. The installation steps given here are generic and
are intended for guidance. For detailed installation procedures of specific instruments also the
manufacturer’s manual and instructions should be observed.
4.2 PRE-INSTALLATION REQUIREMENTS
Before any installation can take place the required materials, tools, spares and other items have to be
collected. Further the proper functioning and fitness for use should be verified.
It has to be ensured that the DWLR is well protected against the damage during transport and storage
in the field. In particular, shock absorbing material should enclose the DWLR housing. Further, it
should be made sure that that the water will not flood the instrument well head assembly especially
during monsoon.

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4.2.1 ACCESSORIES FOR INSTALLING A DWLR
The following accessories are required for installation of a DWLR:
• electrical / suspension cable (most DWLR's under HP have the suspension cable fixed to the
instrument housing. In that case a unit with proper cable length is to be selected),
• suspension grip,
• safety catch,
• safety wire,
• nose cone/pressure filter, if applicable,
• desiccator; the desiccator must be kept in moisture proof sealing, e.g. air-tight plastic bottles,
• breather bags as applicable,
• hydrophobic filter,
• communication cable to DRS, and
• communication interface/adapter box to DRS / PC (required for some brands).
4.2.2 SPARES
The spares should comprise the following;
• At least one set of the above mentioned accessories.
• Spare batteries for DWLR (if required); it is assumed that batteries already have be installed in
the DWLR.
• Spare batteries and/or battery charger for the DRS.
• A DRS
• High accuracy level tape. It is strongly recommended to use accurate electrical level tape of
international standard. To be used as reference for the DWLR, the tape should have at least four
times better accuracy than the DWLR. If for example the accuracy of the DWLR is 1 cm, then the
tape should have an accuracy of 2.5 mm or better. It is very unfortunate but the cheap electrical
tapes, like the ones based on parallel wire antenna cable that are available from some
manufacturers, will not be accurate. In the event of non-availability of accurate electrical tape ,
then a high quality steel tape should be selected.
• multi-meter with capability to measure voltage, current and resistance. Measuring wires and
spare batteries should be included. The display should have a resolution of 3 ½ digits or more.
4.2.3 DOCUMENTS
The following documents are essential during installation:
• DWLR guidelines,
• installation protocol,
• installation forms,
• instrument history log,
• station history log, none of the documents should be original, only copies should be exposed to
field conditions. The history logs do not have to cover a period of more than one year.
• transport box, The transport box must be padded with shock absorbing material to avoid the
fragile instruments being damaged during transport.
• copy of instrument log file pertaining to the specific DWLR, but also for the spare DWLR(s)
carried for field visit.

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• copy of station history log file,
• tools, and
• keys as required to open wells, compounds and buildings.
Any spare batteries should be kept in protective plastic bags or boxes. It should be impossible for the
batteries to be short-circuited by other batteries or metal/conducting objects. At all times, the batteries
should be kept dry and clean.
4.2.4 CHECKS PRIOR TO DEPARTURE
Prior to departure to the field the checks should be executed on the primary items and the spares
including:
• the steel tape. The tape is to be checked for accuracy against a known standard, e.g. a
calibrated steel tape, which is kept in office for reference purposes.
• functioning of the DRS. The separate cursor stick should be available, if applicable. In particular
the DRS models based palmtop PC technology may require a stick type cursor.
• setting of the DRS clock. Since DRS time is used to set the DWLR clocks, it is essential that the
DRS clock is accurately synchronised with national time. Spoken time announcements are not
accurate enough, the radio / TV beeps like transmitted by BBC World Service are! If available,
GPS time may be used instead, it is extremely accurate. After setting, the performance of the
clock should be verified.
• functioning of the DRS battery charger. The DRS devices consume a lot of energy, in particular
when in communication mode. Therefore a properly functioning battery charger should be
carried. In particular the battery contacts should be clean and in good shape.
• functioning of the DWLR. The checks should included the DRS’s and the communication cables.
In particular the communications cables and the connectors are vulnerable. If any defect or
imminent defect is detected, the cable should be replaced and / or repaired.
• Proper marking of the DWLR cable. The marking should at least include the cable length and
measuring range, it would be most efficient if also the serial number of the attached DWLR were
marked. However, some DWLR models have detachable cables that can be shifter for one
DWLR to another. The marking should be on a label placed close to the communication
connector. The readability should be very good and writing none erasable.
• remaining battery capacity of DWLR and voltage / capacity of any spare batteries for DWLR,
DRS, level tape and multi-meter where applicable. For most the battery types, the remaining
capacity can be estimated from the battery voltage. However, some of the Lithium batteries have
such a flat discharge curve that the voltage is not a proper indicator. With such batteries, the
voltage does only drop when the battery is about to become depleted. Battery capacity may be
tested by applying a specific load (resistor) to the battery and measuring the load current and / or
the voltage. The best method should be obtained from the vendor (instrument or battery). Care
should be taken that used DWLR batteries are not mixed with new ones. Write the date of
installation on batteries using a waterproof fibre tip pen
• saturation state of the desiccator. Regenerate the desiccator if not at full capacity in a drying
stove or similar device..
• details on piezometer well and DWLR on log sheet, e.g. well code, latest retrieval date, well RL
value, required instrument installation depth, DWLR Serial Number (S / N), pressure sensor S / N
and similar
• set the DRS clock to precise national time broadcast, i.e. the radio beeps.

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4.3 INSTALLATION
Installation on site is executed in three major steps, viz.: preparations, set-up and post-installation
checks. Since the DWLR is left unattended for many weeks or even months, it is of great importance
that all steps are executed meticulously and duly reported. At the time of departure, the operational
state of the DWLR should be checked. It would be unfortunate if the DWLR were left in a halted state
or some other unwanted mode.
4.3.1 PREPARATION
The preparation for installation of the DWLR involves the following activities.
• Take a manual level and date / time observation.
• Verify the DWLR particulars like serial number, measuring range and cable length. The length of
the suspension cable should be marked on a label. For easy access the label should be attached
close to the communication connector.
• Prepare the sensor for installation by attaching pressure filter / nose cone. Some DWLRs need a
nose cone to increase its weight to fully stretch the suspension cable. While handling the DWLR,
its should be avoided that the pressure sensors bangs on the water surface as the pressure
shock will damage the sensor. As a protection, some models have a pressure filter, most DWLRs
have a nose cone as a protection. The pressure is admitted to the sensor via a series of holes
around the DWLR’s body.
• Prepare the suspension cable for installation to the required depth relative to top of casing. Mark
the required cable length on the cable measuring the cable length starting from the sensor. The
cable should be carefully uncoiled by unrolling (i.e. rotating) instead of uncoiling. This to avoid
coils and kinks in the cable. Coils / kinks in the cable would result in initial zero drift because off
uncoiling / stretching of the cable over time.Protect the communication connector and the air-vent
/ hydrophobic filter against dust and moisture. Also the access for water pressure should be kept
free of dirt; the opening(s) should not be clogged.
• Attach the suspension grip / clamp for the required suspension depth to the cable. The
suspension grip should be positioned at the spot that marks the required cable length.
• Prepare the safety wire.A safety wire should be attached to the DWLR so as to avoid the DWLR
dropping to the bottom of the piezometer in case of an accident. At the other end the safety wires
is to be attached to a firm and stable point and properly secured.
• Check air vent and hydrophobic filter. The air vent should be open; the hydrophobic filter should
be checked for choking by dirt; if needed the filter should be replaced.
• Install fresh desiccator. Check the desiccator and if (partly) saturated it should be replaced by a
fresh package. In case the desiccator package is damaged it should also be replaced and all
loose desiccator material carefully removed.
• Carefully suspend the sensor to the required depth. Only after attachment of the safety wire the
DWLR may be brought into the well. The suspension depth is relative to the top-of-casing. Avoid
shaving of the cable and banging of the sensor. Allow sensor to adjust to the water temperature
and the cable can fully stretch.
• Fix the cable grip to a strong, stable and rigid point. The suspension grip should be attached to a
strong and stable point near the top of the casing. That point should not bend or shift in any way
under the weight of the DWLR with suspension cable or during handling of the equipment.
• check air vent and hydrophobic filter
• The air vent and hydrophobic filter should be kept as high above the ground level as possible to
avoid ingress of water during inundation of the area.

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4.3.2 SET-UP
The set-up involves:
• Start-up the DRS and allocate the required software.
• Connect the DRS to the DWLR.
• Open communications between DRS and DWLR. The proper communication between DWLR
and DRS is initialised, any flaw e.g. due to bad connection or failing DWLR will become evident.
• Retrieve any recorded data from the DWLR. Apply the standard data retrieval protocol and store
a copy of the retrieved data in a safe place on the DRS. At first time installation it is to be
expected that no data reside in the DWLR. It would be safer to store a copy on a removable
device or another DRS. However, in most cases this is difficult under field conditions. Make a
note of the retrieval and annotate the particulars of the retrieval, including data/time, filename
and directory. Only after successful retrieval of data the DWLR set-up may be changed. In some
DWLR models the recorded data is lost in case the instrument set-up is changed. This is an
unwanted property.
• Start the DWLR set-up application on the DRS
• Enable recording of temperature (if supported)
• Check DWLR date and time, and adjust if required
• Check DWLR memory setting: it should be set to endless loop / ring type if applicable
• Set the recording start time so that the readings are taken at integer intervals in such a way that
at midnight a reading is taken. Example: if the recording interval is 30 minutes then recordings
have to be made at 00h00, 00h30, 01h00, 01h30 etc.
• Set the recording interval in such a way that the full 24h is covered by an integer number of
record intervals.
• Time is to be presented in hh:mm:ss 24 hours format and not in AM / PM format.
• Water levels have to be presented in metres with millimetre resolution, non SI units such as
inches, feet etc. are not used under the Hydrology Project.
• Water level is to be presented as distance to water level (from Top-of-Casing). This makes water
level records directly comparable with manual observations. Use an accurate level tape for this.
• Connect the DWLR to ToC observing the manufacturer's instructions.
• Check the proper reading of the DWLR.
• Verify the proper set-up of the DWLR.
• Shut down communications.
• Disconnect the DRS from the DWLR.
4.3.3 POST-INSTALLATION
Post-installation activities involves:
• Allow the DWLR to take as least one programmed record.
• Connect the DRS to the DWLR again.
• Take a manual observation of water level by using the accurate level tape. This manual
observation should be executed several times, preferably by different observers. Any
discrepancies should be verified; it is to be expected that the readings do not differ by more than
1 cm.
• Annotate the date and time of the observations. The time of observation is important because
water level may fluctuate e.g. due to nearby pumping or tidal effect.
• Obtain an instantaneous water level reading from the DWLR. This should be done immediately
after the manual observation was obtained. The instantaneous reading should be really
instantaneous and not of some time ago.

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• Compare manual observations with the DWLR reading.
• Retrieve the collected data from the DWLR.
• Check the retrieved data for consistency. The station particulars should be correct. Verify the
data and time labels of the recorded water level data. The water level values, expressed in
metres relative to top-of-casing, should be the same as the manual observations; i.e. the
difference should stay well within the instrument accuracy limits. The water temperature, if
recorded, should have a reasonable value.
• Shut communication down and disconnect. Check that the DWLR is left in the proper recording
mode before disconnecting and make a note of this.
• Place the protection cap on the DWLR communication connector.
• Check proper fixing of DWLR suspension and safety wire.
• Carefully coil the free end of the electrical / suspension cable taking care not to introduce kinks.
The air-inlet and communication connector should be kept as high as possible above the ground.
In particular when there is a risk of flooding.
• Close the well head and attach locks as applicable.
• Close and lock the well housing.
All actions and observations should be noted in the related log sheet. Time dependant observations
should be given a time tag. Water level readings by level tape and DWLR should be taken quickly
after each other to avoid difference due to change of water level between both observations.
Notes:
• Procedure for procurement of DWLR are given in Volume 4 Reference Manual.
• Operation of the DWLR is outlined in part VII of this Field Manual.
• Maintenance of the DWLR is outlined in Part VIII of the Field Manual.