1. Gateway Wellfield project, Hermanus, South Africa: Implementation, system testing, aquifer monitoring and hydrogeodetic observation
Chris Hartnady,1 Andiswa Mlisa,1 Eric Calais,2
Richard Wonnacott,3 Helen Seyler1
1 Umvoto Africa (Pty) Ltd, Muizenberg, South Africa
2 EAS Dept, Purdue University, West Lafayette, Indiana, USA
3 CD:NGI, Mowbray, South Africa
AfricaArray 2011 workshop, University of the Witwatersrand
22 Nov 2011

2. Hermanus Groundwater Project: Implementation & System Testing
So the outline of the talk:
First I’ll give an introduction to the hermanus water source project and the gateway wellfield
Then I’ll mention something on the sustainable aquifer development related to monitoring
And then I’ll go thrghouh the monitoring system in more detail talking about the 3 tiers we use
Long term
Early warning
And emergency responses
And then I’ll give some examples of how this monitoring system has been put to the test
CCT
HNUS 2

3. Table Mountain Group palaeogeography
Deposition of TMG at mouth of Amazon-scale river system draining southern front of vast Famatinian-Taconic mountain belt in collision zone between Gondwana and Laurentia

4. TMG - Amazon delta analogue

5. Overstrand Water Supply
Until 1976 single schemes in each town:
Surface water use (dams) in Fisherhaven and Voelklip
Groundwater use (boreholes or small wellfields) in Hawston, Onrus, Hermanus
Since 1976 DeBos Dam as source for all towns in Greater Hermanus Area
Previously used schemes abandoned

6. Overstrand Groundwater Investigation
Phase A – Inception (2001/2002)
Phase B – Detailed Design & Implementation (2002 – 2006)
B1 – Wellfield Development at Gateway
B2 – Monitoring programme
B3 – Hydrogeological Reconnaissance
B4 – License Application
Phase C – Conjunctive Water Resource Planning (2006 onwards)

7. Hermanus Geology To introduce you to the heramnus area
Here is a geology map
the peninsual is the lightest grey blue
Cant see topography very well but along here is an escarpment
Beneath it is a coastal platform
The peninsula Unconfined / recahrge zone in the mountains here in the Fernkloof reserve
Peninsula buried in these 3 fault blocks under the overlying confining Cedarberg and Goudini formations
wellfield Confined Peninsula aquifer in coastal setting
Augmentation to municipal supply system
Long Term Pump Test phase 7

8. Hermanus Geo-profile
Looking at a cross section along from the unconfined area
The wellfield boreholes are dpwn at the coastal plateau
Recahrge ocurs up here and the conceptual mdoel is that it feeds the coastal plateau by travelling along the hermanus fault parallel to the page 8

9. Peninsula Aquifer: High confining pressure, high yielding fractures
Wellfield pumping rates: 10 – 30 l/s
License:
1.5 Mm3/a
Firstly to give those who arent familiar some idea of what we are deailng with in the Peninsual aquifer:
We have high confining pressure, artesian conditoins in many situations (some of the hermanus holes)
And fracture dominated flows (pump test data shows)
The wellfield has 3 abstraction holes which pump at between l/s
To give you a visual idea of the strength of these holes here’s a clip of drilling GWP02 and the blow yield 9

10. Gateway Wellfield New Production Borehole GWE06
Existing Production Borehole GWP01
New Production Borehole GWP02
Monitoring Wellpoints WP1 – WP4
Monitoring Boreholes GWE07, GWE08, GWE09 and GWE10

11. Gateway Challenges Management challenges in Hermanus
Avoid seawater intrusion
Avoid dewatering confined aquifer
Avoid unacceptable impact in ecologically sensitive recharge zone
Appropriate technology to address challenges??
As an introduction to the monitoring system and before you see (what we think) is a really sophisticated monitoring system you may wonder why go to all the trouble?
We have the following management challenges in hermanus 11

12. Gateway steady-state model
Position of modelled Hermanus Fault NE
Alice Dodman, 2008

13. Limits pushed ?
Pushing limits of equipment & technical capabilities allows successful management in a potentially unmanageable environment (saline intrusion, environmental concern & opposition)
Monitoring system allows aquifer limits to be pushed
A 7-year human push…resulted in 20-year license awarded, an accepted aquifer management strategy, and handing over wellfield to municipality
Has required a significant human push… to enure htat the best scientific standards wrer mainteained witthin budget constraints, that community participation and undersrtanding kept pace with the license oprocess and I’m happy to say we have RoD and our reserve.
Delays were
2 years for construction of dosing plant, comissioning of dosing took 1 year – 3 years out of our hands
Issuing of reserve / RoD took 2 years.
final leg is final license awarding, an accepted aquifer management strategy, and handing over wellfield to municipality 13

14. Aquifer Monitoring Framework
So the outline of the talk:
First I’ll give an introduction to the hermanus water source project and the gateway wellfield
Then I’ll mention something on the sustainable aquifer development related to monitoring
And then I’ll go thrghouh the monitoring system in more detail talking about the 3 tiers we use
Long term
Early warning
And emergency responses
And then I’ll give some examples of how this monitoring system has been put to the test 14

15. Framework for Sustainable Use
Sustainable Management of Gateway Wellfield & Peninsula Aquifer
SCIENCE:
Water resource
SOCIETY:
The people involved
Available aquifer yield
Environmental impact
I&APs
DWA & CMA & DEA&DP
WSA & WSP
WUA
Operational data:
Pump test observation
Water levels / flows
Before going on with the hermanus case study I wanted to mention how monitoring fits into the project as a whole and how it supports sustainable use
The flow chart here which shows how monitoring feeds into the whole project and is key to many aspects of it
NOT definitive by any means – may be more factors influencing each of the aspects i show... Take it as illustrating the point i want to make
Science and society are key elements to the project.
The key scientific question is the water resource or aquifer yield AVAILABLE – and how does using this yield IMPACT on the ENVIRONMENT in terms of WATER LEVELS and ECOLOGICAL IMPACTS
To estimate the YIELD we can use OPERATIONAL DATA from pump testing, for example we have pumped one of the holes long enough to recognise the typical behaviour under certain pumping conditions tested and also through THEORETICAL MEANS BY MODELLING.
To determine impacts we of course need MONITORING.
And monitoring data of course SUPPORTS any yield determination
Going back to the top,
we cannot do science without society because sustainability (even the very existence before sustaining) of any project depends on public acceptance
People involved in the project are
DWA / WUA / WSP / WUA as represented by OMC
These all meet and interact at the OMC as a forum
DWA and dEADP as the legislator awards the license
In doing so takes the comments of various I&APS into account through the OMC
In doing so impact on the functioning / rules / operations of the WSP and WSA
DWA also has the responsibility to ensure that the WSP and WSA stick to their conditions. It is also the WSA / WSP responsibility to SHOW they are sticking to the conditions (if they want anything to move).
In order to do this monitoring results are key
And in fact monitoring of course is a key license condition
Shows monitoring is key to IWRM
It is the aspect which provides the feedback loops holding the whole together
Onrus Monitoring Committee
Theoretical means:
Modelling
Botanical
MONITORING 15

16. Monitoring Programme Based on Hydrocensus (2003)
Spatial and time distribution of
Rainfall
Stream flow
Water level (Surface and Groundwater)
Water quality
Ecological condition
Water use and abstraction

17. Monitoring overview * x Monitored point Water level EC Flow rate pH
Chemical analysis
Isotopes
3 x production *
6 x Peninsula monitoring
N/A
3 x Skurweberg monitoring x
6 x shallow WP
1 x other major GW user
GW dependent ecosystems
Each of these are monitored at different frequencies appropriate to the aim of the measurement
Those in red are connected to telemetry
Those with a star are also connected to alarms and also to automatic shut off loop 17

18. Three–tiered system Long term monitoring Early warning system
Emergency response
The system of telemetry connections, frequency of measurements, and alarm settings all support a 3 –tiered monitoring system
some monitoring has the aim of long term background monitoring
some acts as an early warning system
some acts as an emergency responder
This has similarities to the conventional far- field / near-field monitoring and you might expect that long term monitoring is simply far field and that an early warning system is near boreholes – but it is not quite that simple
because a far borehole could respond fast to a change if it is connected by fractures
AND because several tiers of data are required for monitoring 1 aspect (1 position) for example abstraction borehole water levels as per next example: 18

19. 3–tiered system Monthly to ad hoc Every second Every 30 minutes
Monitoring point
Water level EC
Flow rate pH
Chemical analysis
Isotopes
3 x production
Monthly to ad hoc
Every second
Every 30 minutes
the monitoring frequency themselves, and how we use the system, supports the 3 tiered system:
Chemistry is done 3 times a year
Along with isotopes ( carbon for water age, oxygen and deuterium for recharge)
Background interpretation of whether anything is changing – the long term monitoring
The water level, EC, flow rate, pH are LOGGED every 30 mins
Transmitted to the internet via telemetry every hour
Protocol for this to be checked every day to changes in water levels / wellfield situation
Supports an early warning system
The water level and EC SENSOR actually measure EVERY second: continually
IF the water level or EC are out of a predefined range an sms alert is sent immediately:
The sms’s are set up to send alerts at 3 levels of intensity / concern
Thus supporting the early warning system and emergency response.
SUMMARISE by saying which is the
Long term monitoring
Early warning system
emergency response system
Transmits to internet every hour
Out of acceptable range?
Immediate sms alarms
Checked daily 19

20. Real-time monitoring
Enables Overstrand to show to DWA, DEA&DP, and I&AP’s concerned with potential environmental impact, that Peninsula aquifer targeted at Gateway can - and is being - managed sustainably
Has therefore become key aspect of licence conditions
Is essential for sustainable aquifer management in such sensitive environment 20

21. Water-Level Monitoring (2003-2011)

22. GWE06 – WL & EC record ( )

23. Hydrogeodetic Observation

24. Precedent case study: Mesquite, Nevada

25. Mesquite setting

26. South African TrigNet system
Network of permanent continuously operating GPS (cGPS) base stations
Distributed throughout South Africa at approximately 200 – 300 km spacing
All stations record 1-second epoch data on both GPS frequencies (L1 and L2) through geodetic-standard choke ring antennas
21 stations stream data continuously to TrigNet control centre in Chief Directorate: Surveys and Mapping
Available within 30 minutes after each hour for 24 hours a day

27. TrigNet station distribution
HNUS

28. Gateway wellfield and HMO
Hermanus Magnetic Observatory

29. Gateway and HMO cGPS

30. Acquisition of Instruments
Ashtec
eBox
Trimble Zephyr antenna

31. Construction and Establishment
Pillar to be rigid and well anchored to borehole plinth

32. Construction and Establishment
Monument and antenna installation at wellheads (Oct-Nov 2008) for measurement of surface subsidence during groundwater abstraction

33. 1st project workshop field inspection (Jan 2009)

34. Data Handling Telemetry system
Cell phone communication
Private Network (machine to machine)
remote downloading of data
remote access to site
Data handling challenges and possible solutions
Data record at 1sec interval - 77MB per station per day
Compression function not working
Transfer of data site-Umvoto-AIMS
Collaboration with Centre for High Computing for data transfer?
Collaboration with CSIR-SAC for data mirroring / backup and transfer?
Data reduction process from 1sec-30sec

35. HY Test Pumping
HGW1 & HGW2
HGW3

36. Gateway and HMO cGPS

37. end pumping
HGW1-HGW2 Results
No observed signal

38. HGW3 to HNUS Result
Complex end-pumping signal, in N component only?
end pumping ?
Unexplained blips in E component ? ? ?

39. HGW3 to HNUS Results
Initial (~10 mm) response in opposite direction to expected uplift, possibly related to poro-elastic deformational response in overlying aquitard (Noordbergum-Rhade effects)
Recovery uplift (~20 mm) linked to ~15 m rise in Peninsula aquifer water-level?
end pumping
Restoration to zero?

40. Acknowledgements
The Overstrand Municipality, in particular town engineer, Mr Stephen Muller, for generous co-operation
The Department of Land Affairs & Rural Development (Chief Directorate: National Geospatial Information) for technical support and assistance related to TrigNet and additional GPS hardware
The WRC and Dr Shafiek Adams for funding support
The Department of Science and Technology for additional funding support
Prof. Hans-Peter Plag and IGCP565 for support to attend Johannesburg workshop