Victorian Mallee Irrigation Region
Standards/Guidelines for
Installation and Management of
Testwells and Piezometers
17
Appendix 2
Enhancement of the Irrigation Development Guidelines in the Mallee - Standards for Testwells
Implementation of the Mallee Regional Irrigation Development Guidelines – 2010/11
Contract number: 10/893
Prepared for: Mallee Catchment Management Authority
Regional Sustainability
Prepared by: Scott McLean
Mallee Irrigation Development Coordinator
DPI, Farm Services Victoria, Mallee
Telephone 03 5051 4500
Email [email protected]
If you would like to receive this information/publication in an accessible format (such as large print or audio) please
call the Customer Service Centre on 136 186, TTY 1800 122 969, or email [email protected]
Published by the Department of Primary Industries Sustainable Landscapes, Mallee, June 2011
© The State of Victoria 2011.
This publication is copyright. No part may be reproduced by any process except in accordance with the
provisions of the Copyright Act 1968.
Authorised by the Department of Primary Industries
1 Spring Street, Melbourne 3000.
Disclaimer
This publication may be of assistance to you but the State of Victoria and its employees do not guarantee
that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and
therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any
information in this publication.
For more information about DPI go to www.dpi.vic.gov.au or phone the Customer Service Centre on 136 186.
Introduction and Purpose
Background
Mallee Land and Water Management Plan
Formation of Salinity Management Plans to Irrigation Development Guidelines
Unbundling and Minister’s Determinations, June 2007
Purpose of Standards/Guidelines for Groundwater Monitoring
Why monitor Groundwater
Groundwater monitoring and salt management in the Victorian Mallee
Meeting the Water-Use Objectives
The use of Soil Surveys and IDMP’s to Determine Monitoring Requirements
Soils
Parilla Sands Aquifer
Blanchetown Clay Aquitard
Irrigation Drainage Management Plans (IDMP)
Installation Requirements
Do you need a licence to install a testwell or piezometer?
Who can install a testwell or piezometer?
Licensing requirements for a testwell or piezometer greater than three metres deep
Key issues to consider when siting a testwell or piezometer
Monitoring
Why monitor using Testwells
Why monitor using Piezometers
Monitoring Plan
Field Record Sheets
Minimum standards for establishing a Testwell not exceeding three metres below
ground level (Testwell diagram attached as Appendix 2)
Minimum standards for establishing a Piezometers that is greater than three metres
and generally less than 10 metres below ground level (Piezometer diagram attached
as Appendix 3)
Monitoring Equipment Checklist
Glossary
References
Appendix
1.
2.
2.1
2.2
2.3
3.
4.
4.1
4.2
5.
5.1
5.2
5.3
5.4
6.
6.1
6.2
6.3
6.4
7.
7.1
7.2
7.3
7.4
8.
9.
10.
11.
12.
13.
Table of contents
1.0 Introduction and purpose
The Victorian Mallee has seen a significant increase in the area of land irrigated by private
diverters over recent years. Over 31,000 hectares of new irrigation development has
occurred by private diverters between 1999 and 2009, taking the total area irrigated in the
Mallee to a little over 70,000 hectares(Source: Sunrise 21, 2010).
This extensive land-use change from dryland farming practices to irrigated horticultural
developments focused on crops such as almonds, olives and vegetables. The pace of
new irrigation developments has now slowed but the approvals process continues to
be reviewed on a regular basis to meet the current environmental policies and minimise
impacts from irrigation, particularly salinity and nutrients inputs to the River Murray from
irrigation developments.
Impacts of irrigation water on the environment are predominately caused by the lateral
or vertical movement of groundwater. This water movement occurs as a result of excess
irrigation water moving past the crop root zone, potentially forming a perched water
table thus increasing the pressure on the regional groundwater table in the Parilla Sands
Aquifer. In some instances excess water may find its way directly to the regional ground
water aquifer, particularly in areas where there is an absence of shallow aquitards such as
Blanchetown Clay.
Monitoring of groundwater through the use of testwells and piezometers is a way of
observing if changes are occurring due to irrigation. Early detection of any detrimental
impacts from accessions to water tables is important as mitigation measures can often
be costly and may take time to implement; early intervention is required to avoid long
term impacts from occurring.
It is during the New Irrigation Development approval process that any requirement for the
installation of testwells or piezometers will be clearly identified. Soil surveyors, irrigation
system designer or approval authorities reviewing submitted plans or assessments, such
as Irrigation and Drainage Management Plan, will recommend installation in areas where
potential impacts on the environment are identified. The requirements for groundwater
monitoring (where required) will be included as a condition on the Water Use Licence for
the property.
This document provides guidance to developers who have a requirement to install
monitoring bores and undertake groundwater monitoring. It provides minimum standards
for the installation and use of testwells and piezometers, data collection, storage and the
reporting on groundwater information relating to irrigation development in the Mallee.
2.0 Background
2.1 Mallee Land and Water Management PlanThe Victorian Mallee Irrigation Region Land and Water Management Pan (LWMP)
provides the framework and policy direction for the protection natural resource assets of
the Victorian Mallee from the potential impacts that may arise from irrigated agriculture.
The plan recognises that new irrigation developments can potentially result in salinity
impacts.
In accordance with the Ministerial Determinations on water use under the Water Act
1989, the LWMP seeks to manage these potential impacts through a system of salinity
impact zones and a set of irrigation development guidelines.
Salinity impact zoning encourages new developments to areas that have a low salinity
impact on the River Murray.
The Victorian Mallee Irrigation Development Guidelines is a companion document to the
LWMP and provides finer details on how new irrigation developments can proceed in a
way that meets the Water-Use Objectives of the Water Act 1989.
2.2 Formation of Salinity Management Plans to Irrigation Development GuidelinesThe Mallee community developed Salinity Management Plans such as the Sunraysia,
Nangiloc-Colignan and Nyah to the South Australian Border (N2SAB) in the early 1990’s.
These plans were designed to encourage sustainable irrigation practices that minimised
the impacts from irrigation on the environment.
New Irrigation Development (NID) Guidelines were later developed in 1994 from the
N2SAB Salinity Management Plan and formalised in 1999 across all of the salinity
management plans. The NID Guidelines enable standards, conditions and monitoring
requirements to be placed on new developments in a consistent and equitable manner.
In general, the Victorian Mallee NID Guidelines are triggered when irrigation development
is proposed on land which has never been licensed, there is a proposal to increase the
annual use limit above a specific level or an application involves an increase in an area
allowed to be irrigated in the existing licence.
Unbundling and Minister’s Determinations, June 2007
The Minister’s Determinations relating to unbundling of water entitlements were issued
in June 2007 and further strengthened the requirements under the NID Guidelines for
irrigators to meet their environmental responsibilities. The Determinations set down
policy and considerations that must be taken into account when issuing a Water-Use
Licence. In particular, the Water-Use Objectives and Standard Water-Use Conditions are
an important instrument in minimising the impacts of water use on the environment. The
five Water-Use Objectives being:
• Managing groundwater infiltration
• Managing disposal of drainage
• Minimising salinity
• Protecting biodiversity
• Minimising cumulative effects of water use
The Mallee Catchment Management Authority reviewed the Victorian Mallee NID
Guidelines in 2010/11 incorporating changes and improvements that had occurred over
the years. As part of the Guideline review, Landholder Information Packages are being
developed that clearly communicate processes, standards and conditions. As a part of
this review, these “Standards/Guidelines for Installation and Management of Testwells
and Piezometers (Groundwater Monitoring Bores)” have been developed.
3. Purpose of Standards/Guidelines for Groundwater Monitoring
This document must be read in conjunction with the Victorian Mallee NID Guidelines
which gives developers a clear understanding of the expectations and standards required
when installing groundwater monitoring bores as part of licensing conditions.
All new irrigation developments are expected to meet best management practices.
As a way of minimising impacts on the environment, the use of monitoring bores is
recommended to detect signs of changes in water tables associated with the use of
irrigation water and drainage past the root zone of plants. Monitoring bores can detect
rising groundwater, increases in groundwater salinity levels and groundwater flows that
may cause off-site impacts.
These Guidelines provide technical support and guidance to assist potential new irrigation
developers meet their responsibilities towards monitoring requirements that may include
the installation of testwells and/or piezometers, by defining minimum standards and
reporting obligations.
4. Why monitor Groundwater
4.1 Groundwater monitoring and salt management in the Victorian MalleeSalt has been a significant natural part of the Mallee’s landscape for hundreds of
thousands of years. Salt exists beneath the landscape and the mechanisms of salt
mobilisation are related to hydrogeological processes; groundwater movement through
aquifers, and retarding clay layers.
Human activity has the greatest potential to affect hydrogeological processes, typically
through river regulation, land clearing and irrigation. Salt management in the Mallee is
focused on managing groundwater movement and in the case of irrigation, managing
recharge and root zone drainage caused by inappropriate and/or excessive irrigation.
A groundwater monitoring program can detect changes in water levels and potential salt
movement in groundwater. Early detection is important for minimising impacts on both
production and the environment by implementing corrective actions and management
procedures.
4.2 Meeting the Water-Use ObjectivesWhen applying for a new or amending a Water-Use Licence, consideration must be given
prior to approval that the Water-Use Licence is consistent with and meets the Water-Use
Objectives that apply to water licences. Standard and/or Particular conditions, including
groundwater monitoring requirements, are placed on a licence, where appropriate, to
meet the Water-Use Objectives.
The Water-Use Objectives are:
a) Managing groundwater infiltration
To limit infiltration to groundwater systems arising from irrigation so as to minimise or
avoid waterlogging, land salinisation, water salinisation and groundwater pollution.
b) Managing disposal of drainage
To control the disposal of drainage from irrigation so as to minimise or avoid
waterlogging, salinisation or eutrophying waterways, wetlands, native vegetation, native
animal habitat and other persons’ property.
c) Minimising salinity
To ensure that, where limits on groundwater infiltration and controls on drainage
disposal are not sufficient to manage identified risks of that land or water salinisation,
licence-holders are responsible for the full costs of measures to reduce those risks, or,
alternatively, the full cost of any necessary offsetting works.
d) Protecting Biodiversity
To set corrective action thresholds and corrective action procedures where limits on
groundwater infiltration and controls on drainage disposal are not sufficient to manage
identified risks, associated with water use, to specific wetlands, native vegetation stands,
or native animal habitats.
e) Minimising cumulative effects of water use
To ensure that, where a series of individually acceptable expansions in water use within
a defined area reaches a preciously announced level, the combined impacts on other
people and the environment is dealt with by remedial actions such as a communal
drainage system, with water users in the area who have expand their use after the
announcement contributing to the capital cost in line with their expansion in use
compared with total use (and remaining costs shared by government and water users in
a way judged after due consideration to be equitable).
4.3 Meeting the Standard Water-Use ConditionsAll Water-Use Licensees must meet the set of standard or conditions attached to their
licence to ensure the irrigation operations comply with the Water-Use Objectives.
Long established irrigation is subject to a set of very basic conditions as detailed in
the Standard Water-Use Conditions (DSE, 2007). However, for any new irrigation
development or a major expansion of irrigation, relatively high performance levels are
required to achieve the best practice in irrigation.
To address the protection of biodiversity, one of the Water-Use Objectives, in situations
where the use of water for irrigation poses direct and ongoing risks to wetlands, native
vegetation, or the habitat of native animals, the standard conditions for new or varied
Water-Use Licences state that “water may be only used for irrigation while the licence
holder meets the relevant monitoring and correctional requirements” with regard to:
i. Installing and maintaining monitoring equipment;
ii. Following data reading, recording, reporting and auditing requirements;
iii. Carrying out corrective action procedures, within time, where a threshold is breached.
As part of the Irrigation Drainage Management Plan during the approval process for
a New Irrigation Development, risks to wetlands, native vegetation, or the habitat
of native animals are identified as well as the specific and relevant monitoring, and
correctional requirements. In the Mallee, Irrigation Drainage Plans are referred to as
Irrigation Drainage Management Plans (IDMP). These involve a detailed assessment
of the proposed irrigation property including a soil survey and irrigation design that
matches water use to crop type. Drainage contingencies are incorporated into the plan
to minimise any impacts should they be detected. One way of detecting excess drainage
past the root zone and rising water tables is through the installation of testwells and
piezometers.
5. The Use of Soil Surveys and IDMP’s to Determine Monitoring Requirements
5.1 SoilsThe Victorian Mallee has a semi-arid climate with rainfall ranging from 350mm in the
south to 250mm in the north. The surface land formations include dunes, jumbled dunes,
swales, hummocks and ridges with floodplains along the waterway systems. These
formations, with exception of the floodplains, were created by Aeolian (wind generated)
geologic processes and are often layered reflecting a series of past events. Figure 1
shows a schematic illustration of the hydrogeology units associated with irrigation areas
in the Victoria Mallee from the River Murray.
Beneath the surface lie a number of contrasting soil layers. Irrigation and drainage water
that moves past the rooting zone of plants has the potential to impact on either regional
or local groundwater processes. There are two important soil layers, the Parilla Sands
Aquifer and the Blanchetown Clay Aquitard that influences groundwater processes. An
understanding of these is fundamental to understanding Mallee regional groundwater
processes.
Figure 1. Schematic illustration of the irrigated area adjacent to the river displaying the important hydrogeological units; the saline Parilla Sands Aquifer and the impeding Blanchetown Clay Aquitard layer with a Perched Water Table above.
5.2 Parilla Sands AquiferThe Parilla Sands Aquifer was formed over two million years ago by the receding sea
depositing fine to medium grained sands as north-south trending stranded beach ridges
with intervening low areas or swales. These sediments form the uppermost aquifer
of the Murray Basin and have an average thickness of about 60 metres. The aquifer is
confined to semi-confined in areas where it is overlayed by a thicker layer of Blanchetown
Clay.
The salt concentration of the groundwater in the Parilla Sands aquifer ranges from 30,000
to 200,000 EC and groundwater can move freely through it and readily finds its own
level in the landscape. This regional watertable has a relatively flat gradient throughout
the region, irrespective of the local land surface relief. Any flow within the Parilla Sands
aquifer is ultimately towards a waterway, including the Murray River, where it may
deposit salts contained in the groundwater. Flow movement in the aquifer is generally in
a north to North-westerly direction.
The saline groundwater within this aquifer can have significant regional impacts.
Groundwater discharge and salinity occurs where the level of the land lies below or
within two metres of this regional watertable. Examples such as Lake Tyrrell and Pink
Lakes are scattered through the Mallee and as previously mentioned, the lower lying
Murray River borders all of the northern Mallee irrigation areas.
5.3 Blanchetown Clay AquitardBlanchetown Clay was laid down as deposits in an ancient freshwater lake called Lake
Bungunnia that covered much of the Mallee landscape. These deposits consist mainly of
red-brown and green mottled clays but can have some sandy to silty clay occurrences.
Blanchetown Clay can act as an impermeable to low permeability layer that commonly
lies within an undulating topography above the Parilla Sands Aquifer thus forming an
aquitard. Permeability of the Blanchetown Clay from above (leakage of rain and irrigation
water) is dependent on its thickness and clay content. Blanchetown Clay can vary from
50m in thickness , to only a few meters or not be present at all, but on average is 20m
thick.
The relatively low permeability and closeness to the surface of the Blanchetown Clay in
many areas, means that a perched water table can form above it if excessive irrigation
through drainage gets past the root zone. By definition most perched water tables are at
an elevation above the regional Parilla Sands Aquifer.
5.4 Irrigation Drainage Management Plans (IDMP)The IDMP for a property has detailed soil survey information that characterises soils to a
depth of 1.5m below ground level (BGL), generally on a 75m by 75m grid spacing across
the entire proposed irrigated area. The soil survey information is overlayed with a number
of other features that include contours, irrigation design, drainage contingency, native
vegetation, wetlands, habitat of native animals and buffers to form a detailed plan for the
proposed development.
Hydrogeological assessments can also be requested as part of a new irrigation
development and the IDMP. The report assesses potential groundwater movement
based on the property location and the known hydrogeological features of the region.
The soil survey and IDMP overlays inform where the shallower testwells less than 3m
BGL (Appendix 2) may be best located on a property to protect biodiversity values by
detecting the formation or rise in any perched water tables, allowing remedial actions to
be quickly implemented.
The hydrogeological report can determine where the deeper piezometers, between 3m
and approx 10m BGL (Appendix 3), may be best located to detect any potential water
movement, contaminants or excessive drainage impacts on the Parilla Sands Aquifer or
other groundwater formations. Due to the generally slow movement of groundwater
water, impacts greater than 10m BGL would require greater investigations and higher
standards for bore construction and monitoring to justify results.
6. Installation Requirements
6.1 Do you need a licence to install a testwell or piezometer?By definition in the Water Act 1989, “a bore is any bore, well or excavation used for the
purpose of groundwater observation or the collection of data concerning groundwater”.
This definition includes testwells and piezometers.
In general, constructing a groundwater bore greater than 3m BGL or if it intercepts
groundwater, a licence or registration is required. Approvals are administered by the
relevant Water Corporation and all water bores greater than the 3m BGL require pre
works approval in the form of a bore construction, alteration or decommissioning licence.
This includes investigation or new bores as well as replacement or alterations to an
existing bore. Bores less than 3m BGL do not need a license.
Licensing or registration of bores ensures that groundwater users and the environment
are considered and impacts minimised.
The irrigation areas within the Mallee are covered by three Water Corporations, two of
which manage licensing issues associated with groundwater bores. Prior to constructing
a testwell or piezometer monitoring bore, developers should consult with the relevant
water corporation who will advise on licensing requirements. The relevant water
corporations within the Mallee CMA Region include Lower Murray Water, Goulburn-
Murray Water and Grampians-Wimmera Mallee Water.
In addition to meeting the requirements of the Water Corporation, or when installing a
monitoring bore less than 3m BGL that does not require a licence, a person installing a
testwell or piezometer must consider any other requirements, such as contained in Acts
of Parliament or by other authorities. Section 6.4 covers a number of these requirements
as an example of items to be considered prior to starting construction of a monitoring
bore.
Prior to starting any construction works, contact the relevant Water Corporation for
administrative requirements and Licensing details.
Goulburn-Murray Water
40 Casey St
Tatura, 3616
(03) 5833 5500
Grampians-Wimmera Mallee Water
11 McLachlan St
Horsham, 3402
1300 659 961
Lower Murray Water
741-759 Fourteenth St
Mildura, 3500
(03) 5051 3400
6.2 Who can install a testwell or piezometer?Any ground water bore that is less than 3m BGL does not require a qualified and licensed
driller to complete the works. If the testwells depth does not exceed 3m BGL, a licence
is not required.
However, if the ground water bore or piezometer is greater than three metres in depth,
approval must be granted via a bore construction, alteration or decommissioning licence
by the relevant Water Corporation. A requirement of the licence is that works must be
completed by a licensed groundwater driller.
6.3 Licensing requirements for a testwell or piezometer greater than three metres deepDepending on the purpose for which a bore is being drilled, and the location, there may
be different obligations, responsibilities and licensing conditions in respect to work
requirements. Before starting work on a monitoring bore, consult with the relevant
Water Corporation.
Drilling must be completed in accordance with licence conditions and standards noted
within the following two documents:
1. Minimum Construction Requirements for Water Bores in Australia,
Edition 2, revised September, 2003 (This document is currently under
review) and
2. General Requirements for Groundwater Observation Bore Works, August
2008, published by the Department of Sustainability and Environment.
These two documents are guidelines only and it must be noted that special conditions
can be applied to a particular bore requiring the bore to meet higher standards.
6.4 Key issues to consider when siting a testwell or piezometerLicensing conditions outlined in the documents mentioned in Section 6.3 above and
discussion with the Water Corporation will deal with the legislation and guideline
requirements regarding groundwater bores. When assessing a licence application, the
Water Corporation must consider existing users of groundwater and the environment as
outlined in Section 40 of the Water Act 1989.
A number of issues need to be considered prior to constructing a monitoring bore to
minimise any detrimental impacts and maximise the quality of the data from a bore. This
includes:
1. The distance from:
• a National Park
• an area of biodiversity significance
• powerlines
• drainage pipes
• channels, lakes or water ways
2. Whether the site is within or close to:
• a Groundwater Management Area or Water Supply Protection Area
• towns / communities
• another bore
• an area where surface water interacts with groundwater
3. If the site is:
• environmentally significant
• potentially susceptible to any contamination
• prone to flooding
• easily accessible
4. Impacts on Cultural Heritage including Aboriginal and European
5. Dial-before-you-dig
7. Monitoring
7.1 Why monitor using TestwellsTestwells, less than 3m BGL, are a relatively cost effective to install and require minimal
approvals. Testwells can measure depth to water levels and water quality of a local/
perched watertable and can detect changes that potentially will have detrimental impacts.
Groundwater is often high in salts and rising water tables in areas without subsurface
drains can be disastrous. Groundwater within a few meters below the surface can bring
salts to the surface destroying irrigated crops, native vegetation and impacting on other
surface features. Testwells are often used by irrigators to minimise damage to production
and for environmental monitoring requirements, primarily because the changes in a
perched water table level can be detected rapidly with easy installation of testwells.
Testwell locations are determined using a number of assessment that include native
vegetation maps, soil surveys, IDMP’s and hydrogeological assessments conducted as
part of the approvals process for new irrigation development.
7.2 Why monitor using PiezometersPiezometers are used in the Mallee to monitor the regional water table in the Parilla
Sands Aquifer or perched water tables where Blanchetown Clay or an impeding layer
is greater than 3m BGL. Monitoring can determine if a site is subject to recharge,
discharge or has lateral flow.
A piezometer that is constructed into a confined aquifer should be designed so that
contamination of a water body is controlled through using a bentonite or grout seal to
reinstate an impeding layer which is punctured by drilling.
Piezometers are generally located in areas as a result of recommendations from a
hydrogeological assessment conducted as part of the approval process for new irrigation
development.
Piezometers are generally greater than 3m BGL, require approval or licensing by a Water
Corporation and compared to a testwell, have a relatively higher cost due construction
requirements. Piezometers can measure water levels in perched water tables, detect
effects of water pressure on a aquifer, water movement both lateral and vertical, as well
as water quality. A line of three or more bores at a site, at the same depth, can measure
horizontal water movement, while bores installed at different depths at a site can
measure vertical water movement.
7.3 Monitoring PlanA monitoring plan is a vital document to manage the information collected on each
particular bore and includes the installation details and type of data to be gathered. The
plan also sets down the monitoring parameters to ensure quality data is captured and
stored in an acceptable manner.
The detail in a monitoring plan will depend on what is being monitored, at what frequency
and any other requirements set by the relevant Water Corporation. There are a number
of guidelines and documents on data collection and monitoring that aim to reduce errors
and increase quality of data to improve management decisions or remedial strategies. A
number of these references are listed in Section 7.3 in this document and should be read
if samples are going to be analysed or if contamination is being measured.
A monitoring plan should record the following items:
• Bore identification, GPS coordinates and date installed;
• Brief monitoring bore description and infrastructure details (Licence No,
depth of bore, screened depth, casing type, height of
casing above ground level);
• Drill log details that includes description of soil characteristics excavated
from bore hole;
• Schedule of who, when and how often to monitor (weekly, monthly,
quarterly, each irrigation, etc);
• What is being monitored – Water levels, salinity, nutrients, contaminants etc;
• Purging details of the bore if required for water quality readings (volume of
water removed and time before sampled);
• Where will the data be stored and by whom;
• Is the installation and monitoring a part of a condition of a Water-Use
Licence;
• Does the data need to be sent to a relevant Water Corporation;
• What are the thresholds that trigger remedial actions;
• What are the monitoring methods and instruments to be used (e.g. fox
whistle for levels, EC conductivity meter for salinity);
• How detailed and creditable does the data collection requirements need to
be (EPA for contamination related issues);
• Identify safety issues;
• Maintenance schedule/requirements.
7.4 Field Record SheetsAn example of a Field Record Sheet is appended (Appendix 1). The field record sheet
should be completed accurately by the nominated recorder at the time of sampling.
The recorder is responsible for the sheet being completed accurately and stored
appropriately.
A condition often placed on a Water-Use Licence for new irrigation development is
that monitoring bores are to be installed, monitored at regular intervals and the results
supplied to the relevant Water Corporation on an annual basis.
8. Minimum standards for establishing a Testwell not exceeding three metres below ground level (Testwell diagram attached as Appendix 2)
A testwell, not exceeding 3m BGL, for monitoring groundwater should be installed in
accordance with the following guiding principles:
• The Testwell should be drilled to the Blanchetown Clay, first impeding layer
or no greater than 3m BGL using a minimum of 110mm diameter auger;
• The Testwell bore casing should be constructed from 50mm Class 9, PVC
pipe/casing;
• The lower 500mm to 2000mm should be slotted with a hacksaw at 8mm
intervals depending on the depth of the water table and depth to first
impeding layer. This allows for water level fluctuation;
• Cover the slotted area with a porous synthetic filter sock (stocking material is
suitable) to exclude fine material from entering the bore casing;
• A 50mm PVC end cap with a centred 10mm drain hole is attached to lower
end of the casing;
• 500mm of PVC casing should extend above the natural ground level. This
standardises the top of the casing, 500mm above ground level, as the point
to be used for measuring depth to ground water from;
• A 50mm PVC cap is placed on the upper end of the bore casing;
• The bore casing is placed in the auger hole and back-filled with gravel or a
course sand filter pack to a maximum of 1000mm above the slotted area.
The remainder can also be filled with gravel, course sand or clean back-fill to
400mm BGL;
• Using clay extracted from the bore hole or bentonite, form a raised seal
around the bore casing at ground surface and to a depth of 400mm BGL in
the bore hole;
• Place a permanent marker post with bore identification number located
500mm from the testwell.
9. Minimum standards for establishing a Piezometers that is greater than three metres and generally less than 10 metres below ground level (Piezometer diagram attached as Appendix 3)
A piezometer that is greater than 3m BGL must be licensed with the relevant Water
Corporation. Licensed bores need to be constructed to minimum standards, specified
in Minimum Construction Requirements for Water Bores in Australia, edition 2, revised
September, 2003 (Agricultural and Resource Management Council of Australia and
New Zealand 1997 (ARMCANZ. 1997)) and to the satisfaction of the relevant Water
Corporation. Monitoring bores should also follow the General Requirements for
Groundwater Observation Bore Works, August 2008, published by the Department of
Sustainability and Environment.
Piezometers, greater than 3m BGL and less than 10m BGL, for monitoring groundwater
should be installed in accordance with the two documents listed above and incorporate
the following guiding principles:
• A licensed driller must be used;
• The nominal diameter of the bore hole should be at least 60mm more than
the casing diameter;
• The drilling technique must be appropriate for the task (auger, rotary mud
drilling, rotary air drilling);
• Drilling methods must not contaminate the bore hole;
• Drilling methods should not restrict water movement through compaction or
smearing of the outer bore hole wall and alter water flow;
• 50mm to 80mm of a minimum class 12 PVC casing to be used;
• A length of slotted screen with suitable aperture size. The length will
depend on the purpose of the bore and which groundwater profile is being
targeted. A sump beneath the screened section may be required if siltation
is considered a problem;
• Generally, there will be approximately 100 slots to a meter; slots should be a
minimum of 40mm long with an aperture size ranging from 0.2mm to 1 mm;
• Cover the slotted area with a porous synthetic filter sock (stocking material
is suitable) to exclude fine material entering bore casing;
• A PVC end cap with a centred 10mm diameter drain hole is attached to the
lower end of the casing;
• 500mm of PVC casing should extend above the natural ground level. This
standardises the top of the casing, 500mm above ground level, as the point
to be used for measuring depth to ground water from;
• Lengths of casing and end caps should be joined with suitable glue that will
not cause contamination of the groundwater and impact on the monitoring
results;
• A small amount of gravel or graded sand is placed at the bottom of the bore
hole for drainage;
• Place the bore casing in the centre of the hole and backfill above the
screened section with gravel or a graded sand filter pack. The casing may
need stabilising centralisers to keep the bore central to the bore hole;
• Fill at least 1000mm above the filter pack with packed bentonite or a
grout seal and to a depth of 400mm BGL. This seal will prevent water
movement from the surface or between aquitard. The monitoring bore must
be constructed to eliminate cross-contamination of aquifers when drilling
through the impeding Blanchetown clay layer;
• Place a steel standpipe with lockable cap over the bore casing to reduce the
possibility of damage and surface contaminants entering the bore;
• Lay a concrete block extending 400mm BGL and sloped above the ground
level, around the standpipe;
• The bore should be purged immediately after construction and after the
bentonite or grout seals have cured. Water samples should be free of
turbidity, sand or silt;
• The bore should be left untouched for several days before the first
monitoring starts. Bore chemistry needs to stabilise and produce at least
three consecutive water quality readings with similar results;
• Maintain a drill log;
• In certain circumstances an accurate survey of the level of the ground and
the upper end of the PVC casing may be required for level in AHD.
10. Monitoring Equipment Checklist
The type and amount of monitoring equipment will depend on the monitoring plan.
The analyses of each sample or measurement will require a level of scrutiny for it to be
creditable. A basic list would include to following items:
• Map and GPS points for bore locations;
• GPS;
• Field Record Sheet;
• Field Record Sheet from previous sampling (check for anomalies);
• Pencil, pen, calculator;
• Key for bore;
• Water level detector;
• Tape measure;
• Field meters ie salinity EC meter;
• Purging device;
• Sampling device;
• Sample containers (must be clean, dry and sealed, material of the container
will be dependent of the analytes being tested; the volume of each sample
will need to be discussed with the laboratory doing the analysis. Note that
some analytes require pre treatment in the field at the time they are taken);
• Labels for samples;
• Decontamination equipment (clean or wash meters and sampling devices);
• If testing for analytes other than EC, then a chilled Esky must be used to
store samples between the sampling point and the laboratory.
Australian Height Datum.
A geological formation, group of formations, or part of a
formation capable of transmitting and yielding significant
quantities of water; aquifer types are confided, unconfined, and
artesian.
A saturated, but relatively poorly permeable, bed, formation or
group of formations that does not transmit or yield water freely.
A clay-type material, usually highly colloidal and, which swells
and shrinks with changes in water content.
Below Ground Level
A hole drilled into the ground and completed for the abstraction
of water or for water observation reasons
Mitigating measure protecting existing remnant native
vegetation to ensure water use and management practices do
not impact on that native vegetation and biodiversity values.
A tube used as temporary or permanent lining of a bore in order
to prevent the solid aquifer material from entering the bore hole
or to ensure groundwater only enters the bore hole at specific
depths through screens
A completely saturated aquifer in which the upper and lower
boundaries are relatively impermeable layers. Groundwater
in a confided aquifer is under pressure and will rise above the
aquifer if the top of the impermeable layer is breached
Guidelines to assist excavators to make informed decisions
before they begin to dig and reduce the risk of injury, damage
or disruption.
Water flow from an aquifer (e.g. from a natural spring or bore)
Ground Water Area
Granular material introduced into the annulus between the bore
hole and a casing to prevent or control the movement of finer
particles from the aquifer into the bore
Subsurface water contained within a saturated zone
A fluid mixture of Portland cement and water of a consistency
that can be forced through a pipe and placed as required.
11. Glossary
AHD
Aquifer
Aquitard
Bentonite
BGL
Bore
Buffer
Casing
Confined Aquifer
Dial-before-you-dig
Discharge
GWA
Gravel Pack (filter pack)
Groundwater
Grout
Hydrogeological
IDMP
Monitoring Plan
Perched water
Permeability
Piezometer
Potentiometric surface
PVC
Purging Bore
Recharge
Salinity
Screen
Screen Intervals
Semi-confined aquifer
Standing water level
Testwell
Turbidity
Unconfined aquifer
Dealing with the distribution and movement of groundwater
in the soil and rocks taking into consideration the geological
aspects of surface water
Irrigation Drainage Management Plan
A system developed to achieve the monitoring objectives
Unconfined groundwater separated from the underlying body
of groundwater by an unsaturated zone and supported by an
aquitard
The capacity of a porous medium for transmitting water
A pipe in which the elevation of the water level or
potentiometric surface can be determined. The pipe is sealed
along its length and open to water at the bottom
The level to which water in a confined aquifer would rise
if unaffected by friction with the surrounding rocks and
sediments
Polyvinyl chloride
To remove stagnant water
Water infiltrating to replenish an aquifer, it can be either natural,
through movement of precipitation into an aquifer, or artificial
through pumping of water
The amount of salt dissolved in water
A special form of a bore liner used to stabilise the aquifer
or gravel pack while allowing the flow of water through the
bore into the casing and permitting the development of the
screened formation by an appropriate process
The area of an aquifer in which the screen has been positioned
and hence from which groundwater may be drawn from
An aquifer confined by a layer of moderate permeability)
aquitard) that allows vertical leakage of water into or out of the
aquifer
The level of groundwater standing in a bore uninfluenced by
pumping in that bore
Measure the level and quality of a local watertable at depths
generally less than three meters
Turbidity is caused by the presence of fine suspended matter
such as clay, silt or colloidal material
An aquifer whose upper boundary is made of permeable
material that transmits water readily
Water table
WSPA
The upper surface of groundwater within the unconfined
aquifer
Water Supply Protection Area
12. References Department of the Environment and Heritage, 2005 Groundwater Monitoring, Module 6,
Waterwatch Australia National Technical Manual, ISBN 0 6425 4856 0
Department of Sustainability and Environment, 2004, When is a Bore a Water Bore,
Groundwater Notes, ISSN 1440-2092
Department of Sustainability and Environment 2008, General Requirements for
Groundwater Observation Bore Works
Department of Primary Industries, Guide to Installing Testwells, 2008, Agricultural Notes,
ISSN 1329-8062
Department of Water, Government of Western Australia, February 2006, Groundwater
monitoring bores, Water Quality Protection Note
EPA 2000a, Groundwater Sampling Guidelines, EPA Information Bullet, Publication 699,
State Government of Victoria
EPA 2000b, Hydrogeological assessment (Groundwater Quality), EPA Publication 668,
Environment Protection Authority, Victoria, ISBN 0 7306 7658 7
EPA 2000c, Groundwater Sampling Guidelines, EPA Publication 669, Environmental
Protection Authority, Victoria, ISBN 0 7306 7563 7
Government of Western Australia, 2008, Guidelines for Groundwater Monitoring,
Department of Agriculture and Food, ISSN 1039-7205
Murray-Darling Basin Commission 1997, Murray-Darling Basin Groundwater Quality
Sampling Guidelines, Technical Report No 3, MDBC Groundwater Working Group,
Commonwealth of Australia
National Minimum Bore Specifications Committee 2003, Minimum Construction
Requirements for Water Bores in Australia, Edition 2, ISBN 1920920099 (this document is
currently under review)
South Australian Murray-Darling Basin Natural Resource Management Board, Floating
Flag Test Wells, Fact Sheet Land and Water 6, Government of South Australia (no date)
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