Aki Artimo and Sami Saraperä Turku Region Water Ltd Finland akiartimoturkufi ThreeDimensional M apping Workshop Oct 8 th 2011 Minneapolis MN Artificially infiltrated ID: 317269
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THE USE OF 3D GEOLOGICAL INFORMATION IN A LARGE MANAGED AQUIFER RECHARGE PROJECT
Aki Artimo and Sami Saraperä
Turku Region Water Ltd., Finlandaki.artimo@turku.fi
Three-Dimensional
M
apping
Workshop,
Oct
. 8
th
2011, Minneapolis, MNSlide2
Artificially
infiltrated
groundwater
will
be
produced
for 300,000
inhabitants
living in the Turku area at the end of this year.The infiltration water is obtained from the River Kokemäenjoki, 90 km north of Turku. Artificial infiltration takes place in the Virttaankangas Quaternary esker aquifer, 60 km north of Turku.The length of feeder pipelines (DN=1200 mm) is about 100 km.The cost of the project is 176,000,000 euros.
INTRODUCTIONSlide3Slide4
Precise
control of the infiltrated
water (i.e. flow paths and residence time in the
aquifer
) is
important
in the
operation
of the
managed
aquifer
recharge (MAR) plant.The aquifer is not used merely to store the infiltrated river water, but also to enhance the quality of the water. The natural purification of the infiltrated water during the flow within the saturated zone of the aquifer is a crucial process for those artificial recharge plants operating in the Nordic countries. After its completion, the Virttaankangas managed aquifer recharge project will significantly increase the number of consumers using artificially recharged groundwater in Finland.BACKGROUNDSlide5
The main factors
affecting the
quality change of the artificially infiltrated groundwater are the
composition
of the
soil
material
,
hydraulic
conductivity
distribution within the esker aquifer and residence time of the infiltrated water.Even though the water quality change occurs beyond the MAR plant’s facilities, the operation can be controlled with the help of:- Measurements of hydraulic head changes- Water quality monitoring data- 3D hydrogeological model- Groundwater flow
model
-
Tracers
(
natural
isotopes
,
organic
carbon and artificial tracers)
BACKGROUNDSlide6
The 3D geological
information
database has been available during the construction of the MAR
plant
.
Automated
updating
of the 3D
hydrogeological
and
groundwater
flow models has enabled the immediate use of the newest research information in the construction of the plant.In addition to basic sedimentological and hydrogeological information, the Virttaankangas 3D hydrogeological model has seen the introduction of geochemical, isotopic, and geophysical data into the 3D modeling workflow. Furthermore, the 3D hydrogeological model works as a structural basis for the 60-layer groundwater flow
model
.
TOOLS FOR THE PROJECT EXECUTIONSlide7
Database
development
Geological modelsHydrostratigraphical modelsGW flow modelsQuantitative
understanding
Simplified
basin
analysis
approach
.
Modified
from Sharpe et al. 2002TOOLS FOR THE PROJECT EXECUTIONSlide8
3D
Geological
information system(including time related data)
3D
Groundwater
Flow
M
odel
Quantitative
understanding
(Aquifer management)
Hydrogeochemical
data
Isotope
data
Drill
hole
data
Geophysical
data
Tracer
tests
Infiltrations
and
pumpings
GW
level
measurements
Sedimentological
interpretations
TOOLS FOR THE PROJECT EXECUTION
Integrated
approach
with
constantly
evolving
and
updating
3D
models
provides
versatile
tools
for
managed
aquifer
recharge
.Slide9
THE USE OF 3D GEOLOGICAL INFORMATION
Geological
information and 3D models have been used to solve
, for
example
,
legislative
,
constructional
, and
land-use
related
issues during the execution of the MAR project.Modeling tools were used to design the optimal layout and configuration of the infiltration pond and production well areas of the MAR plant.For example, locations of five previously planned infiltration areas were rejected due to discovery of morphologically undetectable kettle hole system underlying the infiltration areas restricting
the
flow
of
infiltrated
water
.
Exact
locations
of the
production wells were decided
after
a
thorough
examination
of
available
sedimentological
and
hydrogeological
data,
which
resulted
in
extremely
high
yields
of the
new
production
wells
. As
compared
with the pre-3D
plans
for
pumping
well
locations
, the
amount
of
wells
needed
for
full
scale
production
was
almost
reduced
in
half
.Slide10Slide11Slide12Slide13Slide14Slide15
Avg
.
pumping rate per well 6,700 m3/dPreviously built wells 5,000 m3/d
New
wells
8,500 m
3
/d
(Maximum
yields of the new wells are
higher than the used pumping rates.)Coarsest part of the eskerSlide16
THE USE OF 3D GEOLOGICAL INFORMATION
Geological
information system with the modeling tools provided the means
to design and
control
the
infiltrations
and
pumpings
related
to the
one-year
testing phase required in the environmental permits.According to those permits, the full scale production is only allowed to start after the results of the testing phase provide enough information of the controlled execution of full scale infiltration and pumping.During the one year testing phase the observed flow
paths
and
residence
times
of the
infiltrated
water
coincided extremely well with the groundwater flow
simulations
conducted
prior
to the
testing
phase
.
This
was
not
the case
when
the
earlier
pre-3D
plans
for
infiltration
and
pumping
were
simulated
with the
same
flow
model
.
Those
plans
would
have
resulted
in a
failure
in the
operation
of the MAR
plant
.Slide17
THE USE OF 3D GEOLOGICAL INFORMATION
The groundwater
flow model is the only tool that
can
be
used
to
decide
the
exact
infiltration and pumping rates for all the 19 infiltration ponds and 12 production wells so that the residence time of the infiltrated water in the aquifer is sufficient throughout the flow field. The groundwater flow simulations for full scale production will be conducted later this month.Modeling tools, tracer tests
and the
testing
phase
have
shown
that
the
influence of the artificial infiltration can only
be
observed
in the
coarsest
part
of the
esker
(
g
laciofluvial
coarse
unit
).Slide18
The ”
glaciofluvial
coarse” unit from the 3D hydrogeological
model
(
left
)
and the
corresponding
gw
flow model cells depicting the detailed variation of hydraulic conductivity within that unit (right).Slide19Slide20Slide21Slide22Slide23Slide24
Flow
of infiltrated water
(5 days)Slide25
Flow
of infiltrated water
(10 days)Slide26
Flow
of infiltrated water
(5 weeks)Slide27
Flow
of infiltrated water
(10 weeks)Slide28
Flow
of infiltrated water
(15 weeks)Slide29
Flow
of infiltrated water
(26 weeks)Slide30
All
the investments in research
have
been
less
than
5 M€ (
less
than 3% of the total budget).The cost of one production well is about 100,000 €. Average pumping rate of the MAR plant’s production well is 6,700 m3/d, whereas the avg. yield of other water producers’ wells within the same esker area is 500 m3/d.The required one-year testing phase was successfully completed before the entire construction work of the project was completed.The cost of each day of delay in water production after the construction is completed is about
20,000 €
due
to the loan
interests
.
The
required
production
rates
of the artificially infiltrated groundwater in this 176 M€ project would not have
been
achieved
without
the 3D
geological
information
system
and
models
.
CONCLUSIONS