MUNICIPAL FOCUS: NELSON MANDELA BAY
Groundwater has the muscle to push back ‘Day Zero’ – but are we protecting it?
Groundwater is being used in the fight against the worst drought in Nelson Mandela Bay’s recorded history. To stop the taps from running dry, businesses, citizens and NGOs are drilling boreholes in Gqebera. But amongst the panic and desperation, is enough care being taken to protect this precious resource?
By Kirsten Kelly, Editor: Water and Sanitation Africa, SENIOR JOURNALIST: IMIESA, 3S MEDIA
Link to the magazine article. https://issuu.com/glen.t/docs/
Covering 1 959 km2, Nelson Mandela Bay (NMB) is major seaport and automotive manufacturing centre. With below-average rainfall being experienced in catchment areas, dam levels have continued to decline rapidly. The combined storage levels have not been above 25% since February 2020. As dam levels continue to decline, it is groundwater that is augmenting water supply in the region.
“Depending on its quality, groundwater is generally more affordable than water re-use or desalination. It is a ‘sleeping giant’ and has huge potential in improving the region’s water security. Groundwater flows a lot slower than surface water and can provide water when the surface water sources are stressed. Then, when rainfall levels improve, and the rivers start flowing again, the groundwater can be recharged, while the surface water sources again become the primary water source. Groundwater can buffer the impacts of drought,” says Neville Paxton, chairman: Eastern Cape Branch, Ground Water Division (GWD).
NMB has a complex, favourable geology for good quality groundwater with relatively high yield. It mostly comprises of sedimentary rocks that have undergone tectonic stress, resulting in the mountainous landscapes and large faults that are subsequently overlain with aeolian and alluvial material. There have been highly successful groundwater development projects in and around the city for the Municipality, industrial and private sectors. When the big water users become completely, or partially dependent on groundwater that volume is freed up for other end users.
Nelson Mandela Bay Municipality (NMBM)
The Nelson Mandela Bay Municipality (NMBM) conducted groundwater investigations during the 2010/2011 Eastern Cape drought, and it was found that some properties owned by NMBM had a high groundwater potential. Subsequently, over 200 boreholes were drilled to locate suitable sites.
These potential sites were identified:
NMBM then developed a plan where it is anticipated that a sustainable yield of around 35 Mℓ/day can be abstracted through groundwater sources. The plan entails:
- Coegakop Wellfield and water treatment works
The drilling of five production boreholes is finished and the water treatment works should reach completion in the next few months. It is estimated that an additional 12.5 Mℓ/day should be available at the end of the project.
- St Georges Park Wellfield
High potential groundwater sites were identified at St Georges Park, which also falls along the Moregrove Fault. To date nine boreholes have been drilled – four of which were identified for production purposes. The four production boreholes have been drilled with an estimated yield of 2.1 to 3.6 Mℓ/day. Water from the boreholes will be filtered, disinfected and blended into the existing water supply system. The contract is currently under construction with an estimated completion date in August.
- Moregrove Fault Wellfield
Moregrove Fault Wellfields are completed, they comprise:
- Fort Nottingham Boreholes – three production boreholes have been drilled with an estimated yield of 1 Mℓ/day
- Glendenning Boreholes – three production boreholes have been drilled with an estimated yield of 2.2 Mℓ/day
- Fairview Boreholes – four production boreholes have been drilled with an estimated yield of 0.96 Mℓ/day.
- Bushy Park Wellfield
To date, 18 boreholes have been drilled, of which 10 are marked for production. Groundwater from these boreholes will be disinfected and blended into the Churchill pipeline situated near the wellfield and will supplement the water supply to the western side of NMB, which will reduce the severe pressure of the water demand required from the sources through the western water supply system. It is estimated that an additional 10.5 to 13.7 Mℓ/day should be available on completion of this scheme. The contract is currently under construction with an estimated completion date in August 2022.
- Churchill Wellfield (Future)
73 boreholes were drilled on municipal property around Churchill dam. 19 of these boreholes were identified for production purposes. Groundwater from these boreholes will augment the raw water supply from the Churchill dam and water will be treated at the existing water treatment works. Conceptual designs have been completed and commencement is dependant of funding provision. It is estimated that an additional 3 to 4.3 Mℓ/day should be available on completion of this scheme. An additional 26 boreholes could see an increase of between 5.6 and 8.9 Mℓ/day.
- Non-potable groundwater-use at municipal facilities
NMBM has drilled 27 boreholes at selected municipal pools, parks, stadiums, and sports fields. Of these, seven boreholes provided suitable water quality and sufficient sustainable yield to take the respective facilities off-grid. All seven boreholes were equipped in June 2019 and have cumulatively saved the NMB 19 000 kℓ of potable water to date.
Word of caution
Paxton cautions all potential users against choosing the cheapest groundwater solution. “Groundwater development can be a costly investment. However, the worst approach is to take the cheapest route. Currently, there is a lot of panic and a rush to drill boreholes in NMB and people are choosing inexperienced and unqualified people to do the job. From the start, get a registered professional scientist who is a member of the GWD to guide you; from locating the best position to drill, sourcing reputable drillers, managing the drill process, yield and quality testing to helping you find the correct pumps and registering or licensing the borehole.”
Each rock type has different characteristics and in NMB, there is a lot of sand and loose particles, hard rock and clay, as well as rock layers which yield highly saline groundwater. A hydrogeologist therefore needs to work with drillers to design a borehole. By doing this, one can avoid disappointment and needless expenditure in the long run.
“I cannot emphasise enough how important it is to get a qualified hydrogeologist to manage the whole groundwater development process. South Africa has some of the best fractured aquifer hydrogeologists in the world. Do your due diligence. There has been an influx of ‘one stop shops’ and ‘self-proclaimed Hydrogeologist’ with zero quality control. And because groundwater is shrouded in folklore and mystery, they find it easy to evade responsibility when something goes wrong,” he continues.
A common misconception is that groundwater does not require maintenance. However, if a hydrogeologist is working with a suitable driller, the borehole will be designed appropriately for the geology, and the required maintenance will be less frequent. Huge maintenance costs will arise when untested groundwater that contains certain mineral elements is connected to an irrigation or plumbing system, causing damage to pipes and pumps over time. This can be averted or mitigated at the very beginning. Regularly inspecting the pump and borehole integrity will also improve the longevity of both.
As an unseen and often forgotten resource, Paxton feels that there is a dire need for education around groundwater. “I often see water cycle diagrams that do not include groundwater. Everyone needs to be aware of its value and potential.”
Policy and regulation
While South Africa has top-notch groundwater policies, it’s the implementation of these policies that is challenging. However, the goal of all policies and regulation is to protect groundwater for the use of all South Africans.
It is a requisite to register a borehole with NMBM. “Unfortunately, the current application process for registering and or licensing boreholes is tedious, unnecessarily rigid with a box-ticking approach that is often non-site specific. This dissuades end-users from even starting the process. Regulatory bodies need to create an enabling environment rather than taking a punitive role. But this is a challenge as they are understaffed,” adds Paxton.
Registering boreholes creates invaluable data for the municipality where the levels of groundwater abstraction from the aquifer can be understood and accurate water supply strategies can be formulated.
He suggests that there is a need for groundwater user associations (similar to water user associations) where private stakeholders manage their own groundwater in a sustainable manner together with guidance from government. “Monitoring groundwater use with a flow meter and levels with a sensor will ensure that a borehole is used sustainably and is a legal requirement by the Department of Water and Sanitation (DWS). It protects the end user with surety of supply but also helps immensely in the licensing process. As a user of a borehole, it is important to understand how an aquifer is reacting to groundwater abstraction.”
Advice for municipalities
While groundwater should not be a standalone solution in pushing back Day Zero, it is an integral part of the solution. “All municipalities should make use of groundwater now, even if there is a good rain season and no threat of drought. Do not wait for a crisis. Furthermore, make use of experienced and qualified hydrogeologists to manage groundwater. When projects are put together to go out for tender, they need to be designed and I implemented by hydrogeologists – not drillers or NGOs. This will promote quality control and long-term supply,” concludes Paxton.
GWD Eastern Cape Branch Chairperson
MSc | Senior Hydrogeologist | Director
Pr. Sci. Nat: 115125
Pivotal Farming – Natural Resource Assessment