Assessment and management of groundwater
Groundwater professionals are frequently asked to predict groundwater
behaviour. They may need to assess how much groundwater is present, by
using flow modelling, or to predict the concentration of solutes contained
within flowing groundwater, by using contaminant transport modelling.
For the groundwater professionals at C. M. Jewell & Associates Pty
Ltd (CMJA), groundwater modelling is a logical extension of hydrogeological
and site contamination assessment.
Many of CMJA's investigations involve modelling - in a variety of formats,
at various levels of resolution, and for a variety of objectives. Some
models can be as simple as a one-dimensional analytical equation embedded
in a spreadsheet program. Others can be highly complex, such as a multi-layered,
time-variant numerical model intended to simulate subtle changes in
groundwater movement within a complicated geological setting over a
time scale of several decades.
At CMJA we have the experience and insight to make the critical choices
in designing the model approach most appropriate to the application.
We use the latest analytical and numerical groundwater model codes
and suites of integrated modelling software. The three main codes used
are Visual MODFLOW, SEEP/W and SEEP 3D, described below.
Using the modular three-dimensional finite-difference flow model
MODFLOW, together with the contaminant transport packages known
as MODPATH and MT3D, we can extend modelling into complex contaminant
transport simulations. The public domain model MODFLOW, universally
recognised among scientists, is one of the most commonly used
groundwater flow models. It utilises CAD and graphic-user-interface
front-end software to accelerate and refine the modelling process.
Much faster and more sophisticated than models of the past, it
allows us to produce robust and accurate models in a matter of
A two-dimensional, variably saturated, finite element code, which
is particularly useful for sectional modelling of seepage through
embankments and other geotechnical problems, but may also be used
for 2-dimensional plan-form modelling with complex lateral boundaries.
An innovative, fully 3-dimensional (not layered) modelling code
used to solve complex local (engineering scale) groundwater flow
Other numerical groundwater modelling codes are used where appropriate,
for individual projects. They include INTERSAT/INTERTRANS, FEMSEEP,
TWODAN and PRINCE.
Combined finite difference, groundwater flow/contaminant transport
Finite-element flow and transport.
An analytical element code, TWODAN utilises sophisticated pre-
and post-processing to underpin its highly flexible approach.
Using TWODAN, effective two-dimensional groundwater flow models
may be produced in a matter of hours.
A suite of analytical and semi-analytical compiled codes developed
by Princeton University.
Modern groundwater modelling software bears little resemblance
to the cumbersome programs of the past. There has been a significant
shift towards digital manipulation of environmental information,
allowing computer-aided mapping and storage of virtually all baseline
A 2-dimensional finite-element transport model that is used in conjunction
|MT3D / RT3D
3-dimensional mass transport and reactive transport modelling codes
that are used in conjunction with MODFLOW.
A one-dimensional code that is used to evaluate vertical migration
of contamination through the vadose zone.
A complex geochemical speciation and one-dimensional transport code
used for reactive transport and static evolution problems.
|BIOSCEEN / BIOCLOR
Analytical codes used to assess natural attenuation or bioremediation
of petroleum hydrocarbons and chlorinated solvents in groundwater.
A finite difference flow, transport and biodegradation modelling
To complement these models, we use the software packages described
A three-dimensional sub-surface visualisation and imaging package
used to depict surfaces such as geological formation boundaries
or the envelopes of a contaminant plume. Geometric data can be
shared with the integrated Visual MODFLOW package for modelling
and visualisation of model results.
A geographic information system for the storage and manipulation
of large data sets.
A computer-aided mapping and surface generation package that allows
interpolation and contouring of distributed data and a variety
of geo-statistical analyses.
CMJA has the necessary know-how and experience for the effective application
of all these tools.
The following CMJA projects have involved significant numerical modelling.
Eastern Distributor Motorway, Sydney, NSW
The motorway link from Woolloomooloo to Sydney Airport involved
a tunnel through sandstone and a 'parkway' excavated below the
water table in the Botany Sands aquifer. On behalf of the main
contractor, Leighton, CMJA carried out a range of model studies,
using analytical and numerical finite-element and finite-difference
techniques. These were then used to assess regional and local
impacts of construction dewatering and the permanent structure,
and to optimise dewatering system design and the implementation
of a re-injection system.
Woodend wastewater treatment facility, Central Victoria
When drawing up plans for another storage lagoon at this facility,
Piper Associates asked us to assist with the design of the lagoon
liner and under-drainage system. We were also asked to estimate
leakage loss from the four existing storage lagoons, and to assess
the impacts of the existing and proposed storage lagoons on local
A groundwater flow model, developed using Visual MODFLOW, was
judged to be the only realistic and economically feasible means
by which to simulate the spatially complex hydrogeological conditions
at the site. Using this model, we could develop an understanding
of the hydrogeological set-up, the role of different physical
processes, and their influence on the groundwater system. This
model was then used to simulate groundwater levels and lagoon
leakages under various storage lagoon volumes. It also addressed
the effects of variable under-drain spacings, and their ability
to prevent leakage from reaching the water table.
CMJA also designed a two-dimensional cross-sectional finite-element
model using the software SEEP/W, utilising parameters from the
MODFLOW model. It confirmed the results obtained in the three-dimensional
MODFLOW model, and also allowed seepage analysis of lagoon leakage
and quantification of consequent water level mounding between
the underlying drains.
Parkes water supply, NSW
The town of Parkes and the North Parkes Mine are supplied with
groundwater by a borefield located in the Lachlan alluvial aquifer.
This borefield was under stress, and experiencing a drawdown that
greatly exceeded the predictions of the consultants who installed
the boreholes. CMJA was engaged to review all data and prepare
a numerical model of the borefield, to assess long-term sustained
yield, and to help design a new pumping regime. A three-layer,
transient groundwater flow model was developed, using Visual MODFLOW.
Climate, irrigation abstraction, the town water supply abstraction,
and the river water level fluctuation stresses were imposed in
time-variant data sets in order to simulate the development of
the decline in piezometric head as a result of over-abstraction
at the Parkes Borefield.
Various model scenarios were developed, making it possible to
assess the effect of a number of strategies intended to ameliorate
the drawdown on the rest of the aquifer, and to achieve a more
sustainable abstraction regime for Parkes Borefield.
Thredbo Landslide Inquiry, Snowy Mountains, south-eastern
The NSW Police coronial inquiry into the Thredbo landslide disaster
commissioned CMJA to investigate and provide expert testimony
on the influence of groundwater seepage on factors contributing
to the landslide. The geotechnical SEEP/W modelling code was used
in verifying infiltration trials, in calculating seepage response
to recharge, and in sensitivity analysis of seepage in landslide
preconditions or triggers.
|Off-stream water storage and irrigation,
For this project, CMJA investigated groundwater conditions and potential
impacts of leakage from the large (20-GL) storage areas and from
irrigation bypass flows. A numerical groundwater flow model - INTERSAT
- was used as part of an extensive study that also included remote
sensing, geophysical surveys and a drilling program. CMJA subsequently
re-analysed the site for an alternative storage configuration, using
|Beef cattle feedlot development, Forbes,
Numerical groundwater-flow modelling (INTERSAT) was used to design
a contaminant plume capture system in order to contain existing
and potential groundwater contamination at this large export feedlot.
|Leachate collection system, Homebush Bay,
Analytical and numerical (FEMSEEP) modelling of the inflow to a
leachate collection drain, to be constructed as part of the remediation
of the former landfill sites at Homebush Bay, was carried out as
part of detailed design and construction planning.
|Environmental flows, Lower Darling River,
The NSW Department of Water Resources asked CMJA to assess interrelationships
between groundwater and surface water, and environmental flow requirements
in the Darling River downstream of Menindee. FEMSEEP was used to
model inflow along sections perpendicular to the river.
|Damman aquifer model
This project, carried out by Groundwater Development Consultants
International Ltd, involved creating an integrated finite-difference
numerical model of the multi-layered Damman aquifer complex in eastern
Saudi Arabia and Bahrain. Chris Jewell was responsible for program
development, model calibration and operation, and presentation of
|Oaklands Mine feasibility study, Oaklands,
Water management aspects of a large open-cut coal mine development
were studied. Work involved re-injecting large volumes of mine water
into the Murray Basin aquifers, and included drilling and well testing,
detailed field hydrochemical surveys, and modelling. Chris Jewell
was responsible for formulation of model geometry and boundary conditions,
and assessment of material properties.
|Contaminant transport modelling, Blue Mountains,
This project, relating to a former gasworks site in the upper Blue
Mountains, involved modelling transport, natural attenuation, impacts
on human and environmental receptors, and the feasibility of alternative
remediation and containment options.
|Open-cut Coal Mine, Hunter Valley, NSW
Finite-element modelling was used to assess the flow regime through
a leaking saline water storage dam, and compare remedial alternatives.
|Sandstone Quarry, Central Coast
SEEP 3D was used to assess the effect of expansion of a sandstone
quarry on groundwater levels in the surrounding area, and on local
How CMJA can help you
We have the expert capability to deal with the complex issues and factors
that are integral to groundwater flow modelling and contaminant transport
Whether you want us to design an efficient dewatering system or sustainable
borefield, to assess transport times and the fate of contaminants in
the groundwater system, or to make reliable predictions of groundwater
impacts, our professional team can meet your needs.
We also offer a full-service consultancy in this field, from water
sampling to expert testimony.