The GEM Magazine #1 by The Dewatering Institute

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GEM

Your guide to the latest news and insights into the global dewatering industry

A Safe and Sustainable Future

When asked to write the foreword for the very first Groundwater Engineering Magazine (GEM) I felt an enormous responsibility. The global groundwater industry is at a pivotal point in its evolution and to come up with the words to introduce the many wonderful professionals, projects, and innovations that The Gem will highlight is a real challenge. I chose to draw on my own life experiences and my current approach to work and personal life to deliver a message that should resonate with everyone.

I have spent many years drilling water wells across East Africa. As a young adult thrust into the wilds of this amazing continent, it became abundantly clear during my journey through Uganda, Kenya, Tanzania, and South Sudan, that water truly is life. Taken for granted by many, water is – and will remain, top of the critical resources league table.

TEAM

Publisher

The Dewatering Institute

Designer Ian Mackie

Sub-Editor

Sharon Marshall

Content Writer

Nicole Steyn

Business Associate Director

Riëtte Laas

Marketing, Sales & Content

Riëtte Laas

Contributer

Vivian Botha-Veldstra

Disclaimer

The views expressed in this publication are not necessarily those of the publishers. Whilst every effort was made to ensure accuracy the publisher and editors cannot be held responsible for any inaccurate information supplied and/or published.

The copywrite for all material published in this magazine is strictly reserved.

Tel: +27 +711 773 779

Email: riette@dewateringinst.com www.dewateringinst.com

So as the world’s political leaders andthe wider sustainability community disperse from COP27, we need to ask what agreements are in place to protect the world’s groundwater? With this in mind, how are we going to contribute as an industry to safeguard this vital resource?

The delicate balance between Planet, People & Profit continues to pose dilemmas for both developed and developing nations. Urbanisation continues to trend upwards as people flock towards cities, whilst 40% of the world’s population rely on the ocean for habitat and work. They face a threat to their livelihoods as rising sea levels continue to endanger coastal habitats across the globe. Climate adaptation is affecting large sections of society, and water remains the number one critical resource for all of humankind. As groundwater engineers we interact with this valuable resource every day, and as more and more countries develop critical infrastructure to accommodate growing or transitional populations, the way in which we think about approaching groundwater control, protection, pollution should be a priority for us all. So how do we ensure the industry mindset evolves to face this challenge?

I work at Fugro and some five years ago we decided to re-assess our purpose and to embed ‘Create a Safe and Liveable World’ in everything we do. This is a journey that everyone understands and can be an active part of. Our main goal is to achieve a net-zero carbon target by 2035, which is a considerable challenge considering our fleet of vessels. However, it’s about believing in the purpose, and everyone pulling in the same direction to make this a reality. Sustainable innovation underpinned by the right mindset is the way we can progress our efforts in the near-surface engineering world.

Advancements in technologies that contribute to a lower carbon footprint, whilst making it a safer place for people to work, yet still allowing for businesses to thrive, is the fine balance I referred to earlier.

On a personal level in striving towards a greener future, I think carefully about my daily choices. As a leader I provoke thinking amongst the team and push them to be the difference. I encourage them to collaborate and influence our clients from governmental, developers or tier-one contractors to develop a greener way forward for the way work is procured. As an industry we can make incremental improvements day by day, year on year to our operations that will produce a safer world for our children and their children to grow up in.

When I look back on those early days of extracting groundwater in rural areas of East Africa, seeing the joy on children’s faces as we pumped out for the first time, the lives we changed by bringing this resource to their community - that is truly humbling. This is what started my own personal journey to make a difference. As members of the groundwater engineering community, we all have the power to make a difference.

This is what GEM is all about, an opportunity to come together and learn all about the latest developments and opportunities. I hope all will enjoy reading this first edition and feel insipred to look into the future.

Peter Brooke Regional Director Strategic Sales & Marketing – Europe & Africa, Fugro.

Peter pictured together with chief driller Sylvester Mwanza installing water wells on the island of Pemba, Zanzibar in 1998

Foreword by Peter Brooke - TDI Advisory Council member

THE GROUNDWATER ENGINEER MAGAZINE THE

3 Peter Brooke. A Safe and Sustainable Future

5 Ferrer and Hölscher Wasserbau form partnership in Canada

6 Doubling up on Dreissiger. Joe Dreissiger, Project Senior Manager, Hölscher Dewatering

12 Young Professionals in Dewatering. Francois Gous, TDI's Graduate Advisory Council Member

Persistence IS Everything. Dr Kym Morton. Founder of KLM Consulting

Ferrer and Hölscher Wasserbau form partnership in Canada

Ferrer has entered into an agreement with German-based Hölscher Wasserbau to form a partnership strengthening their presence in North America. The new brand, Hoelscher Ferrer North America Inc. is based in Bolton, Ontario and run by Alfredo Rodríguez as the main executive. The consortium will reinforce the identity of both European companies as strategic partners.

In this new partnership, FERRER will provideour extensive technical expertise as well as our innovation expertise in numerical modelling and drilling systems. HÖLSCHER

WASSERBAU will contribute to the partnership with its extensive experience and potential in water treatment, signal management and control transmission,

explains FERRER’s CEO, Alejandro Ferrer.

Hoelscher Ferrer North America Inc will operate in the field of hydrogeology applied to engineering works The new company will focus its activities on groundwater control (Dewatering) and on the movement of large bodies of surface water (Bypass Pumping) in the civil construction, building and mining sectors in Canada.

Alejandro Ferrer explains that the firm commitment to promoting Dewatering in Canada is based on the country’s macroeconomic stability. “After analyzing the different markets, we believe that we can provide innovative technological solutions to achieve efficient drilling techniques and numerical calculation models that optimize and reduce the operational costs associated with the dewatering activity”, he affirms.

Ferrer Dewatering Canada receives machinery for dewatering and bypass pumping

FERRER already has its own machinery and technological equipment in Canada for the execution of dewatering projects. The company has transferred a supply of specialized drilling machines and pumping equipment to carry out Dewatering and Bypass Pumping.

The CEO, Alejandro Ferrer, explained that the purpose “is to avoid subcontracting work by having all the machinery and in-house technology necessary to carry out the work in our specialty in Canada. Thus, we maintain all the autonomy and control of the processes, to provide the best service to the client, avoiding the implicit dependence on subcontracting”.

Implementation In Canada

The transfer of its own machinery and technological equipment adds to other important steps that the company has already taken to progressively establish itself in Canada For example, the incorporation as a member of the Canada-Spain Chamber of Commerce (CCCE), which provides essential work in establishing business, economic and business relations between the two countries.

Doubling up on Dreissiger

Share a bit of your background: tell us your dewatering history and how you got into the industry?

I’ve been involved with groundwater management since I graduated from university. was in consultancy for about 20-22 years, working on the jurisdictional part of things where I focused on specialised reporting and consulting with the waterworks and various third-party bodies that had something to do with groundwater; I found solutions to their problems. I actually have a background in hydrogeology which is exactly the opposite of the focus within the company.

When the possibility to work at Hölscher Wasserbau came up 8-9 years ago, I was at a huge advantage because I am aware of the complexities involved in the dewatering operation, and everything that it entails, including the hydrogeological impact there is on the environment outside the building site. And from a legal point of view, what the dewatering operation implies, and what kind of discussions need to be conducted with local authorities.

My advantage today is that I have all-round knowledge of how the dewatering operation needs to be designed and conducted. And, when in discussions with third parties, a further understanding of exactly what that dewatering operation can superimpose on those living around the construction site. This understanding of the issues that surrounding communities will face means that I can feel the impact that the operation will have on them even before I go into the discussion, which makes it easier for me to find compromise.

In your opinion, what has been the biggest development in the industry through the years?

The necessity to conceptualise sustainably. For example, in areas where water isn’t sustainably recharged by rainfall, or other forms of recharge, to conduct dewatering operations in such a way as to create opportunities

What are the biggest challenges that you’ve seen in the industry over the past few years, and what do you see as potential challenges in the future?

Climate change. The requirement in the future in certain areas, at least here in Germany, is to apply permanent dewatering installations.

To be able to regulate groundwater levels in those areas where, due to heavier rainfall caused by climate change, water tables in total will rise. We need to compensate that through implantation of permanent dewatering systems. We’ll have to find recharge methods of redistributing the extracted water into the system to ensure the overall balance is neutral; and, in those areas where I do infiltrate, there isn’t excessive groundwater level rise.

Within the next 10-20 years, we will really feel the pinch with climate change. It’s not just sea water levels that will rise; groundwater flow towards the sea will decrease and if you can’t compress water, it will begin to rise. The amount of water in the whole hydrogeological system won’t change and we won’t physically be able to destroy water. How we manage those excessive amounts found in many areas of the world will be the challenge.

The Munich West Project. We compacted the surface for a deeper groundwater extraction scheme, which enabled, for the first time, a multistorey car park with five levels to be constructed near to a groundwaterdependant surface river. It involved intense planning and consultation with the regional government, difficult construction and complex monitoring.

The dewatering wells were placed with their filter screens already connected, not only at different depths, but in different hydrological systems, to lower groundwater and to decrease the pressure head on deeper artesian aquifers. All the while not affecting the river negatively and altering groundwater levels in the immediate surroundings of the abstraction site.

What would you recommend to the new generations coming into this industry and why?

To have an in-depth understanding of the background of what I said earlier about climate change, before you start to gain experience in overall groundwater dynamics and groundwater management on a large scale.

The dewatering itself can be learned in the webinars given by TDI. You don’t necessarily get the required experience in a dewatering company. Gain your first five years experience outside by getting experience on the overall picture.

What’s the best piece of advice you would give a younger version of yourself?

Certainly to have studied geology, but also to combine it with civil engineering so that I would’ve got more out of the traditional groundwater hydrogeology sector, and then being able to combine it with engineering practice and experience. It would’ve put me in a more versatile position in handling different situations. Many have experience in one or the other but very few have experience in both.

Over the last few years in dewatering, I have often run into problems which made me see I am missing the core competence in some civil engineering subjects. You can study them separately, but you can’t study what we do. If you want to call yourself a dewatering engineer, you need both sides of the coin.

There are constant changes in legislation from the government and the industry; are there any areas where you consider the legislation to be too weak or too strong?

With the regionals, it will only work if everyone works together. One example is the dam on the Nile - the surrounding countries need to co-operate on a large hydrogeological scale. The only way to mitigate this is to work together. There’s no national way forward, it’s international on a continental scale.

Any pertinent words about why TDI is important?

Exactly what we were talking about before, it can function as an instrument to promote the overall education of everything required for dewatering, and it can act as a body to participate in that process that will be required in the very near future to mitigate climate change. Climate change will result in a complete imbalance of the groundwater equilibrium that has built up over historic and geological time, the challenge is to find methods of bringing that balance back under altered climatic conditions through both de- and re-watering.

I think our job will change in its nature, it’ll be less classical and there’ll be more large regional groundwater management plans to mitigate the groundwater level rises instigated by climate change.

“ ”

for recharging water supplies. Such an opportunity would be through reinjection so that, even though the dewatering process will lower the water table within the site, there will be no net loss of groundwater from the overall hydrological system.

I think next to the classical dewatering operations themselves, dewatering companies in coastal regions will be increasingly required to build large systems to regulate water, groundwater flow and groundwater levels.

Reflecting on years gone by, can you mention a few memorable moments?

Joe Dreissiger. Senior Project Manager Hölscher Wasserbau - Germany.

Credit: Raiko Goldenbaum

Tap into the deep trough of groundwater research with Joe Dreissiger and his journey with Hölscher Wasserbau.

Deep Pipe Dreamers

With vast knowledge of deep well and flooded mine dewatering applications, CHPPS’s modern production equipment, competent personnel, extensive training and advanced support technologies has positioned it time and again as the preferred piping partner for leading industries around the globe.

The project is lead by Chief Executive Officer, Chris Munnick, who has over two decades of broad experience and deep insights and expertise in the execution of turnkey electrical and mechanical projects – from conceptual design to installation and integration.

CHPPS has been involved in mine dewatering projects throughout Africa – including South Africa,Namibia, Botswana, Zambia and the Democratic Republic of Congo, where its application of know-how, ingenuity, advanced fabrication equipment and highly trained staff successfully ensure the commencement or continued productivity of the mining projects.

Turnkey specialists

Carl Hamm Pipes Solutions (CHPPS) is a South African subsidiary of Carl Hamm GmbH in Germany, a fourth generation family business with a global hands-on history in pumps and over 90 years’ experience in the mining industry.

CHPPS has a firm belief in forging sound partnerships with experienced organisations that contribute to the success of these projects. One of CHPPS’s industry supply partners is Duchting Pumpen, specialising in the field of advanced centrifugal pumps – producing single-stage and multi-stage pumps ideal for almost every application where the transportation of water plays a role.

(Carl Hamm PPS is the local distributor for this product).

Another partner, Stuwa Brunnedfilter Bohrbedarf, a leading manufacturer of high-quality well-construction technology, has extensive experience and expertise in the production of well screens in PVC/steel and stainless steel, as well as geothermal products and drilling accessories.

CHPPS has recently partnered with FELUWA Pumps GmbH – its unique MULTISAFE double hose-diaphragm pumps are perfect for handling aggressive and demanding media reliably and with little wear. The linear flow through the hose membrane and the valves ensure that the pumped

medium does not come into contact with either the pump head or the hydraulic chamber.

In addition to selling its products, CHPPS also offers a Turnkey Solution – taking full control and accountability for site safety files – offering one-stop shop cost-saving for specialist services such as Acid Mine Drainage, Pumps, Drilling and Pipelines, Well Construction, Borehole Sinking and Geotechnics Divisions.

CHPPS provides the differentiated products, advisory expertise, and best-ofbreed training to plan, install and assure efficient running of client operations, while motivating staff and creating new skills in broader terms.

CHPPS offers on-site commissioning assistance, troubleshooting, laser alignment, condition or vibration analysis, flow rate measuring, workshop pump rebuilds, repair, and supervision. It also offers its clients training to enable them to receive full instruction in the use of their products.

CHPPS’s complete turnkey solution (from pump to motor) in the scope of supply, includes electrical switch gear, variable speed drives, power generation and e-house infrastructure.

Whether operative or not, water in mines must be kept at an acceptable and safe level and contaminated water must be brought to the surface for treatment.

CHPPS’s ZSM system is the solution – a safe, quick and flangeless installation to handle the abstraction and dewatering of mine water for virgin mines, control in closed mines, and reclaiming of flooded mines. The convenience of the ZSM

system is that it suspends pumps and dewaters from surface, eliminating the need to enter the mine. The ZSM system works for both open pit/underground mines and in deep wells.

The patent-protected tight sleeve solution that the ZSM system employs is unique in its quick and easy assembly/ disassembly and ensures cost-savings through the whole life cycle.

The Ideal Supplier

CHPPS, with its vast experience in water management, is a competent partner in abstraction and drainage projects. Safety is a primary focus for CHPPS, which, as founding member of The Dewatering Institute (TDI), is committed to safety-assured operations for its staff, clients, community and all relevant stakeholders, ensuring its staff are suitably trained to observe protocols and uphold all systems as good corporate citizens.

CHPPS fulfils both local and international requirements with its management systems certified under DIN EN ISO 9001:2000 and are an approved specialised company for welding applications (AD 2000 HPO & DIN EN ISO 3834-3) in addition to producing certificates of process reviews and individual welding qualification certificates for all our MAG, TIG and submerged arc welders, amongst others.

For know-how, ingenuity, advanced fabrication equipment and highly trained staff to help you master current and future challenges – on time, within budget and compliant with international industry standards – CHPPS will deliver efficient management and mitigation of the risk that water poses to a mining operation.

Left: Aerial view of equipment at work.

Top: Swing that fits pipe in center with the secured coupling.

Layne,

Originally established in 1882, Layne offers a rich history of delivering safe,

and reliable water and minerals solutions throughout North America. Granite acquired Layne and its subsidiaries in the fall of 2018, to further Granite’s strategy to grow through acquisition and diverse end market expansion.

a Granite Company joins The Dewatering institute as a founding member

“Having the team of Layne on board as founding members of TDI brings further great experience to the institute and its followers. Their willingness to contribute and share their expertise in the field of specialised well drilling, installation, rehabilitation, water well pumps, motors and water treatment technologies will prove very valuable to our industry and help promote TDI’s fundamentals. From discussions with James Cooper and the team from Layne, it was evident that they will also play an active and important role in the compiling of industry best practices by TDI ” explained executive member of the TDI Advisory Council and industry professional, Christoffel Botha.

Water Resources Division

From water well drilling to related infrastructure services, Layne are experts in providing comprehensive solutions for various markets. Specialities include well drilling, pump design and service, well rehabilitation, and water treatment services. They offer comprehensive solutions for government agencies, commercial and municipal water suppliers, industrial facilities, agricultural, and energy companies. Their teams identify and develop new water sources and deliver potable water to communities and facilities throughout North America.

Mineral Services Division

Having provided drilling and borehole services to the world’s premier mining companies for over

a century, Layne’s mineral services division is driven by the need to identify, define and develop underground base and precious mineral deposits. They strive to operate at the highest level of safety, technology, and environmental responsibility.

Safety by Choice

We are excited as an organization to contribute, collaborate and share our expertise on the world stage. I believe it is critical to our company and industry to capture, understand and close the gaps in our best practices,

said James Cooper, special projects manager at Layne, whose safety culture is based on shared knowledge and engagement at every level of the organisation.

Operating under the banner, “Safety is about stories, not statistics,” Layne focuses on deeply personal training. “We are responsible for making safe choices not only for ourselves, but for those around us. We must take care of each other.”

Young Professionals in Dewatering

The Dewatering Institute (TDI) is delighted to introduce Francois Gous, TDI’s Graduate Advisory Council Member.

Francois is currently working as a Geohydrologist/ Technical Engineer for Project Dewatering Limited (United Kingdom) while also enrolled at North-West University (SouthAfrica) completing his Master’s degree in Hydrology and Geohydrology.

Francois made his debut into the dewatering industry under Christoffel Botha, Advisory Council Member at TDI. He assisted Christoffel with various tasks within TDI and Project Dewatering Limited (PDL). During this time Francois acquired valuable knowledge working closely with the TDI team, attending webinars and assisting with dewatering designs. More recently, he accepted an offer to work for PDL as their Technical Engineer, with various responsibilities from documenting tenders to client communications and dewatering designs to quote formations.

When asked why he would recommend a career in the dewatering industry to younger generations, Francois said:

“The need for dewatering engineers and geohydrologists has never been higher, driven by new legislation put in place to protect our environment.

”He continues to explain that there are always new projects and problems to solve which helps you exercise the skill of technical thinking and knowledge of subsurface mechanics. In a fastlearning environment, it gives you loads of experience in a very short amount of time.

Francois notes that a lack of young graduates entering the dewatering industry is one of the biggest challenges the industry is currently facing. He encourages graduates to consider a career in the dewatering industry as it is growing rapidly and requires more professionals to start coming up through the ranks and learn from the more seasoned professionals.

Francois is passionate about improving the image of the dewatering industry, particularly among contractors who have who often have a limited understanding of dewatering. Dewatering professionals are a crucial component during the initial stages of construction operations to anticipate potential challenges and prevent delays and waiting for permits to be issued.

During his time at TDI, Francois saw first hand how TDI impacts the industry through knowledge sharing and networking. “The free webinars are a great way of spreading new information, [new technologies] and educating those that want to learn more,” Francois explains. Bringing the industry closer, the information-sharing and networking opportunities that TDI provides is highly beneficial for anyone in the industry

Francois Gous. Geohydrologist/ technical engineer for Project Dewatering Limited - South Africa.

from large companies down to new graduates. “It’s a great initiative that should keep growing for decades to come,” Francios concludes.

Young Professional of The Year

TDI was thrilled to honour the industry’s young professionals at the 2021 TDI Awards. Hendrik Koers from Hölscher Group was the winner of the Young Professional of the Year Award, followed by finalists Fadhala Mohamed Wajdi of Hydroserv and James Watson of OGI Groundwater Specialists.

If you’d like to nominate a young professional for the 2022/2023 TDI Awards, please submit submit your nomination and find more information on dewateringinst.com

Dewatering forms part of Hölscher Wasserbau GmbH, Europe’s largest dewatering contractor, servicing

TSi 150T Truck-Mounted Sonic Drill Rig (2012)

TSi 150CT e-Sonic Truck-Mounted Drill Rig (2022)

Wind Wisdom

In the northwest corner of Flevoland, a wind farm of 37 onshore wind turbines was constructed with Dura Vermeer as main contractor. During the start-up of the first dewatering and recharging wells, both the discharge rate and the dissolved iron contents were higher than expected in a preliminary third-party investigation, and the scheme was completely revised by CRUX.

Vertical stability

Revisions included a wind turbine foundation, which consists of a pile plan and a concrete mast base with a diameter of about 21 m. To realize the concrete base, an excavation of 1.5 m had to be carried out in dry conditions, with vertical stability to prevent uplift of the impermeable soil layers: a complex operation, because of variability of thickness and properties of the peaty soil and the head in the aquifer. A geotechnical investigation was conducted, consisting of 338 cone-pressure tests and 527 drilling logs, laboratory investigation of soil material and several monitoring well measurements. The challenge was to translate the large amount of data and complexity of the soil into an efficient and effective design, by reducing the need for dewatering activities.

Authors: T. Sweijen / R. Wimmers / J. Knüppe

Using automative engineering, vertical stability for each wind turbine location was determined, and groundwater level was determined to tailor an excavation strategy. The trade-off schedule, which required close co-operation between contractor, hydrogeological consultants, software engineers and Dura Vermeer’s band of excuting parties, shows the excavation methodology for different groundwater levels, for each wind turbine location. A technical feasibility process of the excavation, was conducted at the drawing board and behind the computer, detailing width trench, preferred sequence of excavation, size of excavation areas, geotechnical and hydrogeological calculations. An extensive and timeconsuming and process (almost 900 drill logs and cone pressure tests), almost every step was automated in an engineering process applied by CEMS, as CRUX's consultant, which required automating for almost all steps.

The first calculation step in the methodology was the classification of the cone pressure tests. This classification was conducted based on CEMS' CPT model, which is an artificial intelligence model that is trained with cone pressure tests and drilling log descriptions. The second computational step links the volume weights of the soil to the

classification of the cone pressure tests. The volume weights are based on the laboratory investigation, from which a key for lithology and volume weight was derived. In the third calculation step, the vertical stability for each cone pressure test was determined, where the optimum excavation level or maximum allowable groundwater level was determined, in accordance with geotechnical standards.

In this project, the vertical stability was determined for 10 excavation scenarios, where the preference was for an integral excavation as deep as possible (ideally to a depth of 1.5 m).

From the integral excavation level, further excavations and a soil improvement could be applied if needed. As a final option, dewatering of the underlying aquifers was considered. In the fourth calculation step, the above calculation steps were checked using the vertical stability of the boreholes. As a fifth and final calculation step, the most conservative calculation results per wind turbine location were reported for each scenario.

For the sake of clarity, all calculations were translated into an understandable format. The contractor then translated this into work instructions.

Results

Using the automatic classification and resolving the vertical stability, it was possible to include all available cone pressure tests instead of only the normative ones that were used in the initial design. This clarified the spatial variability of the complex properties of the soil and provided a clear insight into the probabilities and risks per wind turbine. The results were summarised in a consideration scheme, which required good interaction between contractor, consultant and software engineer, because the starting points for geotechnical calculations have to be

closely co-ordinated with the feasibility of implementation. Using a method which considered aspects such as width of excavation strips, sequence of excavation and soil improvement of various pipeline strips and excavation depths, it tuned out that full-scale dewatering was not necessary at most foundations.

Many advantages

Through automated engineering, the large amount of data was translated in a short time into a feasible consideration scheme for excavation and dewatering strategy. Through close co-operation

between the executing parties, consultant and software engineer, the excavation and dewatering strategy was optimized. The benefits were multiple, namely: the schedule was met, despite the setbacks; a large reduction in the discharge rates, allowing the existing dewatering permits to be maintained; and an optimal cost picture compared to alternatives such as discharging groundwater into nearby lakes.

Thomas Sweijen is Geohydrological Consultant at CRUX; Robin Wimmers is software engineer at CEMS and Jorine Knüppe is project manager of Infra National Projects at Dura Vermeer.

Replacement wind turbines

The municipalities of Dronten and Lelystad are working on a new wind farm, within the project Windplanblauw. The existing 74 wind turbines are being replaced by 61 larger turbines with more power. They will generate enough power for the annual household electricity consumption of one million Dutch citizens.

The project is being developed by Vattenfall and SwifterwinT. Construction on land started in 2021; on the IJsselmeer in 2022. Placement of the turbines on land will take place between April and September 2022; on the IJsselmeer between April and August 2023. At the beginning of 2023 all onshore wind turbines were up and running. The wind turbines avoid CO2 emissions of about 700,000 tonnes.

Schematic overview of the vertical stability calculations

Impression of pouring concrete into the excavation (photo: Dura Vermeer)

Above: Impression of excavation (photo: Dura Vermeer)

Above: Impression of excavation in progress (photo: Dura Vermeer)

Tailings Disposals Best Practice

Author: Andrew Vietti

Andrew Viette, Director at Vietti Slurrytec, sheds a light on mine tailings and explains its usage at Jagersfontein in South Africa.

What are tailings?

Most mine tailings can be classified into either coarse solids or fine solids. The coarse solids (usually overburden material) are generally stored in free-standing dumps which are dry and self-supporting. The fine solids are generated after the ore is processed to recover the valuable product. These solids are suspended as a liquid slurry which needs to be dewatered (normally by a thickener) before disposal to a tailings storage facility (TSF).

How are tailings disposed?

The best way to store the fine solids is to do so with the least amount of water possible. The selection of the dewatering unit process can often determine the type TSF design selected and the construction method used to store the tailings. Traditional dewatering processes such as High Rate thickeners are only capable of dewatering the fine tailings to a low density cream-like consistency. More modern thickeners such as High Density or Paste units are able to

reduce the amount of water so that the tailings have the consistency more like a toothpaste. Even higher amounts of water can be removed if the tailings are filtered to a dry cake. However, it is not always easy to obtain a dry filter cake because of the clay content in some mineral tailings – notably diamond tailings such as the Jagersfontein tailings.

Many

factors affect the final selection of a particular TSF dam design, such as the properties of the tailings, the type of dewatering process used and the topography of the land.

Even if the tailings contain a lot of water and they are stored correctly, they could be perfectly safe - take for example a regular water dam where the volume is held in a valley with a well-designed dam wall.

However, mines in South Africa are located on flat topography where the tailings cannot be stored in valleys. Consequently, construction methods using liquid tailings to store fine solids have been developed successfully such as Ring Dyke dams using Upstream and Downstream construction methods. It is clear that the vast majority of tailings should be dewatered as much as possible and that the existing TSF designs should be phased out in favour of Best Available Technology (BAT) methods which utilise High Density/Paste thickening to build Paste dams using Central Thickened Discharge or Down-Valley Discharge construction methods (Figure 1).

What happened at Jagersfontein?

There were a combination of factors which build up to the failure. Firstly, diamond tailings contain a significant proportion of clay minerals which in Jagersfontein’s case are naturally “dispersive”, which means that they will not settle and dewater in a thickener (Figure 2).

This property means that ANY thickener is incapable of thickening the tailings and therefore a very watery tailings was pumped out to the Jagersfontein tailings facility. It is unfortunate since (i) the dewatering thickener at the Jagersfontein processing plant was actually designed to dewater the tailings to a high density paste and (ii) the tailings behaviour can be modified so that the clays do settle so that the thickener can operate properly. Unfortunately, the

mine staff were unaware that modifying the process water chemistry would have solved this problem. The second major failure was that the Jagersfontein TSF was constructed as a Ring Dyke facility on flat topography which meant that the fine tailings were stored above ground level and were contained by a dam wall constructed using coarse solids. This design of TSF is not suitable for storing watery tailings as the basin of the facility is elevated above the surrounding land

and can easily become unstable when filled with large volumes of water (Figure 3).

In the final analysis, the management/ operators at Jagersfontein may be excused for not understanding the colloidal properties of their tailings material, however, they should be held to account for allowing the operation to continue when it was obvious that the dam was overfilled with water.

Figure 1: A “Paste” TSF Design in Kimblerley (top left); The Jagersfontein “Ring Dyke” TSF design (right)

Figure 2. “Paste” TSF Design in Kimblerley (left); The Jagersfontein “Ring Dyke” TSF design (right)

Figure 3 below: Time sequence for the Jagersfontein TSF failure

2022

TDI AWARDS 2022

We’re excited to announce that entries are now open for the 2022 TDI awards!

The TDI Awards bring together dewatering & groundwater control professionals on a global scale to acknowledge and honor the outstanding work and achievements of our network.

The inaugural 2021 ceremony was the highlight of the year for TDI and we look forward to hosting members and other industry professionals of the community and more, once again at the next ceremony in 2023.

Judging Panel

The judges for the TDI awards include some of the most successful and knowledgeable professionals in the industry.

The TDI Awards provide an opportunity to showcase expertise, experience and knowledge in the construction, mining and groundwater engineering sectors. Our eight awards categories have been chosen to cover a range of key aspects in the industry and also to drive innovation, sustainability and carbon reduction in our field of work.

TDI Award Categories

Fort Lauderdale Aquatic Center Project

The Challenge

Owner:

City of Fort Lauderdale,

United States

Client: Hensel Phelps

Time: 2/2020-11/2020

The site geology added to the complexity of any groundwater control efforts. The soil consists of 10 inches of sand followed by 10 feet of soft limestone, followed by an additional 12 feet of sand and then alternating layers of sand and limestone. The water contribution from limestone layers is highly variable due to fracturing and the potential for these fractures being connected to the intercoastal waterway created concerns with pumping volumes and discharge rates.

Engineering High Flow Systems

The project began with a significant design and engineering effort to ensure proper sizing of the wellpoints, header pipe, pumps, and discharge system. A wellpoint system is used to dewater projects with a depth of up to 20 feet, so the excavation depths were within the functional limits of a wellpoint system. We were concerned with the potential for high flow due to limestone underlying the site and proximity to the intercoastal waterway. The design effort included a thorough numerical analysis using MODFLOW to determine the potential impact from the underlying limestone.

Hensel Phelps was contracted to rebuild the Fort Lauderdale Aquatic Complex pools. The project required the demolition and replacement of eight pools. The site is located on a peninsula surrounded by the intercoastal waterway.

The work involved eight excavations over 6feet in depth, including several excavations greater than 12feet below grade. The site’s observed water levels were approximately 4feet below grade and were heavily influenced by tides due to the proximity to the intercoastal waterway, which was within 50feet of all excavations. Griffin was contracted to control the groundwater level in seven excavations and assist with seepage and rainwater control in the eighth.

Dewatering System Design

Based on the analysis, the Competition Pool, the largest excavation at the site, was designed with 2 inches wellpoints (as opposed to the standard 1.5 inches model) to accommodate the potential for high flow indicated in the worst-case scenario model (approximately 2,000 gallons per minute). This design was meant to eliminate the need to mobilize additional equipment to the site to prevent any delays once the installation was underway.

Wellpoint System

› 400 Wellpoints were installed 4 feet apart to a depth of 22 feet

› All wellpoints were connected to a common header pipe with flexible swing hoses

› Header was connected to 8-inch wellpoint pump stations with primary & backup wellpoint pump

› Water was discharged to a baffled settling tank to allow turbidity & suspended solids to settle prior to discharge into the waterway

Pumping Tests

After the completion of ten wellpoints all installation activity was halted to allow for a production test of the wellpoints. This test required four hours of pumping while measuring drawdown in adjacent wellpoints and allowed us to calculate the observed permeability of the soil at the site.

This test confirmed that we would not be faced with the worstcase scenario and installAtion continued inside the sheeted perimeter of the pool. Additional systems for the subsequent excavations were installed in the same fashion, with multiple systems being connected to a single wellpoint pumpstation.

Innovative Monitoring System

Strict Discharge Guidelines

The permit for discharging into the intercoastal waterway required daily monitoring done at the discharge point and a background location. To stay in compliance the turbidity in the discharged water could not exceed background water quality by more than 28 NTUs. This monitoring was originally planned to be completed by Hensel Phelps personnel, who would be dedicated for at least 4 hours per day to collecting and analyzing the samples and reporting the results.

THE GRIFFIN DIFFERENCE

Griffin’s comprehensive design and execution process allowed us to deliver a first-class groundwater control solution for the project. Griffin was able to design, install, and test a dewatering system that was the minimum viable solution for the client allowing them to proceed efficiently with the work.

Griffin met strict discharge permit guidelines for monitoring and reporting turbidity, requiring turbidity levels to be no more than 28 NTUs greater than measured background turbidity. Griffin was also able to innovate a monitoring system to help Hensel Phelps save on labor and money.

To assist with project cost control Griffin introduced a Hach monitoring system to Hensel Phelps. The system was able to monitor and report turbidity levels in real time and kept a log of all data. One sensor was installed at the discharge point while another was put on a Griffin manufactured floating device to monitor the background location in the intercoastal waterway. The Hach system was updated every 60 seconds allowing for real-time data on the quality of the water being discharged. This helped Hensel Phelps save money by not having to pull water samples manually

Van Tongeren takes off and takes over

Meet groundwater guru Guido van Tongeren, this century’s family brain behind Henk van Tongeren Water & Techniek, who was instrumental in taking over the Raaijmakers Company in September.

With over 70 years of technical experience, Henk van Tongeren Water & Techniek has recently become the largest groundwater dewatering company in the Netherlands and an international leader in groundwater dewatering. The company was founded in 1949 by plumber Henk van Tongeren which contributed to the reconstruction of the Netherlands during the time post-World War II.

With few resources or money for expensive machinery, Henk made use of old war vehicles to build his own machines and tools – a tiny token of his inventiveness, decisiveness and will to always get things moving.

The company expanded with a second and third branch in 1995 under the leadership of the second generation of van Tongerens, with branches in Germany and Lithuania.

Could you share a bit of your background: tell us about your dewatering history and how you got into the industry?

I grew up in the family business, so it was only natural that I would continue in the industry. I would walk around the company from a very young age. I got my first real job working for my grandfather’s company at only 11 years old.

In your opinion, what has been the biggest development in the industry through the years?

on track. We are already seeing a nice reduction and all three companies currently meet the requirements of the CO2 performance ladder level 3. In order to be a frontrunner in sustainable entrepreneurship, it is our goal to become completely CO2 neutral by 2030. These are challenges that we will still face for many more years to come.

Can you mention your most memorable moments in the industry if you had to think back over the years?

Secondly, in 2016 when my family gave me the opportunity to take over the family business completely.

What would you recommend to the new generations coming into this industry and why?

The biggest development in the industry is most definitely the technology and machinery. The machines are continually getting better and more efficient. These developments in technology also allow our employees to work safely and sustainably in all conditions and environments. Manpower, technique and experience can only take us so far, but with the right machinery, we can complete any project that comes our way.

What are the biggest challenges that you’ve seen in the industry over the past few years, and what do you see as potential challenges in the future?

Firstly, in 2012 our company was awarded a contract to provide dewatering for the A2 motorway tunnel in Maastricht, Netherlands. This project took four years to complete. For us, the biggest challenge was that the geology under Maastricht (a city in the far south-east of the Netherlands near the Belgian and German borders) is actually very un-Dutch. There is a four-metre-thick layer of loam here, with around 10 metres of very coarse gravel and stones underneath.

The most important factor for success is the people. Make sure they are always number one. If your people are doing well, then your company is doing well. Since technology and developments in the industry don’t stand still,neither should our employees. For thisreason, our employees are given every opportunity to complete various training courses to always keep their knowledge up-to-date.

What’s the best piece of advice that you would give a younger version of yourself?

Always think entrepreneurially and keep believing in opportunities, but most of all in yourself. We are all heading towards a very bright future in which we can only make the world a better place.

Since 2006 the company has been in the capable hands of the third generation of van Tongeren, in the form of Guido, who continues to move the industry forward and expand on his grandfather’s mission. With his leadership role, Guido adopted Werner Wils’ DSI® technology (Düsen Saug Infiltration) from Germany which allowed the company to take an important step forward in establishing Henk van Tongeren Water & Techniek as the most innovative dewaterer. This technology gave the company the ability to handle water disposal in many large construction projects.

The company acquired Theo van Velzen and Tjaden Consultancy in January 2021 for both soil well drilling and groundwater dewatering, and Tajden Consultancy for soil mechanics, which has added 65 colleagues to the fold. All three companies are cut from the same cloth: family-run and owned businesses with a passion for water and technology.

We spoke with Guido van Tongeren to learn more about his role in Henk van Tongeren Water & Techniek.

One of the biggest challenges in our industry is energy consumption and especially the consumption of diesel. In addition, we still use too many plastics. It is important that we eventually become completely carbon neutral. Since carbon emissions are significant in companies like ours, we have set targets to reduce our CO2 emissions and calculate our footprint every six months to remain

Underneath this is a thick marl layer that is tens of metres thick. Our challenge was to pump the marl layer dry so that the sheet piling of this enormous construction pit would remain firmly in place. The depth of this building pit was between 18 and 24 metres. The first Dutch double-layer motorway tunnel was eventually built in the pit. The extraction was always around 1,200 m3/h, with a maximum of even 2,300 m3/h. In addition, 80% of the water had to be returned to the soil by means of the DSI® infiltration system.

There are constant changes in legislation from the government and the industry, are there any areas where you consider the legislation to be weak or on the other hand too strong?

Too little attention is paid to energy consumption and the waste of fresh water. As stated earlier, the civil engineering industry is currently focusing on carbon neutral goals, and how we address this in the future should be taken into consideration more.

Guido van Tongeren. Owner / Entrepreneur Van Tongeren Watertechniek & GeoHydronNetherlands

In recent years, we have developed a unique machine for installing plastic sheet piling up to a depth of 10 metres without vibration. These sheet piles are ideally suited to:

For use as over protection and shoring Anti-piping screens for dikes Encapsulating pollution and contaminants

It is sustainable because it consists of 100% recycled material and has a lifespan of 100 years!

Distinctiveness for large complex projects

Because of our large and total service, we can do more for you. As a result, our customers know how to find us for the big complex works. Some of the works we have done in recent years are:

- A2 Maastricht tunnel: double-sunken tunnel 2.5 kilometres long.

- N31 Harlingen: Deepened carriageway 2 kilometres long.

- Amaliahaven: Construction of harbour quay 2.5 kilometres long.

- Blankenburg connection: Construction of new motorway (2 kilometres sunken + tunnel under river Scheur.

To infiltrate rainwater into the soil in a sustainable way, we are continuously developing our own system. We own the DSI® system and deploy it in many places.

For instance, we started the Aerfit project together with the municipality of Apeldoorn. Aerfit is a component within the Life+ programme from the European Union. Within this project, we areinstalling 150 rainwater infiltration wells at various locations within the municipality of Apeldoorn. Together with partners (including several universities), we are monitoring and improving the system.

For more information, see www.aerfit.eu

■ Provides a more rapid understanding of site dimensionality

■ Initial ground modelling and risk assessment to optimise design

FUGRO

■ Optimal targeting for follow-on site investigations

■ Light footprint

SWANSTM (3D PASSIVE SEISMIC )

THE FUGRO DIFFERENCE

FUGRO SWANSTM (3D PASSIVE SEISMIC )

At Fugro, we deliver solutions that provide essential Geo-data insights in all environments from urban areas to remote locations. SWANSTM turns ambient signals into a three dimensional representations of the subsurface that can inform permitting, feasibility, planning and conceptual design decisions to support more economic construction, for a safe and liveable world.

As part of Fugro’s initial site screening solution, SWANSTM provides key insights into subsurface properties and structure by using passive seismic data to create a 3D ground model. This innovative technology is applied in both greenfield and industrial areas where there is a growing need for the development of underground space and infrastructure with deep foundations.

PASSIVE, NON-INTRUSIVE 3D CHARACTERISATION

As part of the design phase, site characterisation in urban and industrial environments is often limited by a number of factors such as pavements, roads, and private properties that limit access to the subsoil. Our SWANSTM screening technology overcomes these challenges minimising environmental and community impact.

SWANSTM can effectively turn ground vibrations into valuable Geo-data.

LISTENING TO AMBIENT NOISE

BENEFITS

LISTENING TO AMBIENT NOISE

Most geophysical methodologies applied in site characterisation are severely hindered by difficult access and the ambient noise generated by human activity. SWANSTM however, captures the ambient seismic signals that are ever-present in urban and natural environment, such as those arising from heavy machines, road traffic, metros, wind and waves, and uses these vibrations to characterise the ground.

■ Provides early foresight of potential ground risk and geohazards

BENEFITS

■ Provides early foresight of potential ground risk and geohazards

■ Provides insights into ground conditions that reduce design uncertainty

■ Supports earlier decision-making to accelerate design schedule and control costs

■ Informs and optimises conventional ground investigation programmes

■ Supports earlier decision-making to accelerate design schedule and control costs

■ Informs and optimises conventional ground investigation programmes

Unique drilling technique: installing plastic sheet piling by auger drilling / flushing

DSI: Our Fast High Volume Infiltration technic

Persistence IS Everything

Few prove it more than Dr Kym Morton, founder of KLM Consulting and International expert on mine dewatering design

Can you tell us more about your work history and how you got into the dewatering industry?

I have a background in geology. I started at Witwatersrand University, Johannesburg, after which I was awarded a scholarship to Kings College, London, where I did my BSc Honours. My first job was in Namibia at Rossing Uranium, where I took two years to install their monitoring network around the open pit and far into the desert. I was then headhunted by a consulting company for a water exploration project in Botswana where the team discovered the Ntane and Mosolotsane aquifers which are still supplying Orapa and other mines today. I realised that it was important to gain additional qualifications in hydrogeology, so returned to London to attend University College and obtain an MSc in Hydrogeology. At the same time, the team created the first dewatering strategy for Letlhakane mine in Botswana.

Since then, I’ve worked all over subSaharan Africa, including 18 years for De Beers and Debswana on their diamond mine dewatering projects world-wide. My PhD was on mine dewatering design for deep block caves; the research

work was done over 10 years at Finsch diamond mine in South Africa. I have also consulted internationally covering countries such as Indonesia, Russia, Spain, Ireland, Germany, Australia. After many years in water supply and dewatering design, I realized it is very important to talk the language of business so as to connect the science with the application and funding. I therefore completed an MBA at Imperial College, London producing a thesis on Mine Dewatering and the Dewatering Industry. It is really important to understand the business side of mine water control to ensure the advice is cost-effective and innovative.

What are your favourite projects that you’ve worked on in your career?

I’ve worked in around 70 different countries. The largest project I’ve worked on was an underground copper mine in the Congo, which is now the fastest growing mine in the world. One of my favourite projects was for Mir diamond mine in Siberia on their underground transition and re-opening following a flood. Mir mine temperatures range from +43 degrees C in summer to -48 degrees C in winter: the permafrost and halite are complicated aquifers. Another one of my favourite projects was in Angola,

What aspects of the industry do you think need improving?

In our industry there is innovation going on all the time, there’s been an explosion in improved tailings management using detailed monitoring (such as Insight-terra.com) of causation not just effect, which is very exciting. The use of gaming skills in visualisation is also very important, real-time monitoring and alerts so you can see exactly what is happening in a specific area in the world. So you can sit in your boardroom in Vancouver, London or Perth and you can see exactly what’s happening to your mine in deepest Congo, Mali or Angola.

Areas that are sluggish are perhaps the regulators and governments, who don’t seem to understand that water management has a lot more opportunity for innovation. There needs to be much better co-operation between governments, corporations and the mine sites themselves. By reducing the contact of water with a mine, this also reduces the environmental impact. At the end of the day if you don’t waste water, you don’t pollute, so the more you conserve water and the better you look after it, the better the business will be.

Can you tell us why TDI is important to the industry?

Dr Kym Morton. PhD MBA C Geol FGS FSAIMM FGSSA DIC Pr Sci - KLM Consulting - South Africa

where the mining company is opening the fourth biggest kimberlite pipe in the world.

What are some of the biggest challenges you’ve seen in the industry?

The biggest challenge we have is with education; we have a lot of young geologists who focus on computer modelling before understanding the aquifers. It is essential that a conceptual model is drawn up and argued before numerical modelling is started. What is really important in this industry is getting to site, getting your boots dirty and using real-time evidence to improve decision making.

Why would you recommend younger generations a career in the dewatering industry?

I think mining is a very exciting career, because it takes a huge amount of thought to get the logistics right. So my advice to younger people if they really want an exciting career that will always stimulate them, then mining and managing mine water would provide an excellent career. The Environmental, Sustainability and Governance (ESG) issues are very interesting when based on a thorough understanding of the physical processes.

“ ”

I think TDI is a marvellous initiative and fits very well with my ambition to be more transparent and spread more information about water management. There should be good competition in the industry, but at the same time there needs to be collaboration.

TDI can help increase transparency and share knowledge through promotion of the TDI courses and webinars. The initiative is fabulous because what kills our industry is ignorance, people make decisions without the right knowledge. When this is linked to accurate and visible, welldisseminated, monitoring dashboards then the whole industry and stakeholders benefit.

What has been the most inspiring thing someone has said to you within your line of work?

Not necessarily inspiring but very sensible, I was working on a project in Botswana, I had been on site for about nine years and an Anglo-American civil engineering team were going to take it over. Our whole team was being demobbed from that project, which had become very close to my heart. When I was about to catch the last flight out, an Irish engineer, who saw I was worried, said to me, “Take your hand out of a bucket of water and see what difference it makes”. The whole philosophy is that you’re never as big as the project, the project is bigger than you, if you’re taken out of the equation it will still carry on. When water is involved, the impacts are far bigger than the individual. Once you take ego out of the work you’re doing and don’t mind who takes the credit, it’s amazing how much can be achieved.

As you have worked all over, what is your favourite place to work?

I’d have to say a beautiful copper mine in Spain, near Seville. After work you get to drink Spanish wine, eat Spanish food and work with lovely Spanish people and it’s also a fantastically run mine. But I always, always, enjoy flying back to Johannesburg and working in South Africa. The magical smell of the highveld transports you the moment you open the plane door.

What is your life motto?

“Never give up, persistence is everything”. At some point you might want to give up or might need to, nothing lasts forever, change is inevitable and there’s huge opportunity in chaos.

Above: Visual observation of in pit seepages and then accurate seepage mapping is necessary to understand pathways for water flow.

Right: At a shaft head with over 300 000 m3/hr being pumped to surface from below 1km deep (Zambia).

Above: Inspecting an unlined canal that recycles water pumped from underground back into the mine workings (Zambia).

Royal Eijkelkamp joins as TDI's latest member

TDI is excited to announce that Royal Eijkelkamp, based in Giesbeek in the Netherlands, with its existing knowledge and expertise of soil and water specialists, has joined The Dewatering Institute as a company member. From field measurement equipment to smart sensoring and sampling and from Edelman augurs to sonic drilling, Royal Eijkelkamp has a wide range on offer.

From its early days as a village blacksmith, Royal Eijkelkamp has been focused on becoming the world’s preferred supplier of solutions, including one-stop shop solutions – for soil and water within the categories Land Degradation, Food Security, Urbanisation, Pollution, Land Development and Natural Resources.

Royal Eijkelkamp is represented by specially selected partners in five continents and in more than 9 countries. More than 100 years of experience have brought us a long way, but we are still motivated to do more, act better and

serve our world. The best decisions are made based on high-quality data: the more data is collected over time, the better the insights gained.

Thanks to long-time monitoring, parameters such as soil moisture, water level, water quality, or the discharge of a river can be studied in more detail, which gives insight on the influences of external

conditions like evaporation, dehydration and water flow.

Their solutions help soil and water managers in their research and continuous monitoring of groundwater and surface waters. Alarms can be set for certain events so that action can be taken in time, like timely warnings of high water levels (floods), low water levels (drought) or polluted water.

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Remote Monitoring of Critical Components

Remote mon toring a lows dewatering companies to keep real-t me ins ghts on their operat on 24/7 and ensures that every part of equ pment operates ns de its normal parameters

Chaplin Station

Company: Country:

Chaplin Station is part of the Eglinton Crosstown Light Rapid Transit (ECLRT) Project in Toronto, Canada. The ECLRT project comprises 19.7km of light rail transit running along Eglinton Avenue, with 25 stops/stations.

The Chaplin Station project involved the construction of a new Station Box, Main Entrance (West), and Secondary Entrance (East) Buildings (see Figure 1). This required connection with existing twin running tunnels, with excavation of an area circa 117.0m long by 18.0m wide, to 22.0m below existing ground level.

The twin running tunnels were constructed and completed by 2016. Part of the construction sequence at Chaplin was the excavation through the twin running tunnels during the excavation of the station box, used to connect the tunnels with the new station (see Figure 4). The geology at the site comprises an upper sand aquifer overlying a lower sand aquifer separated by a low permeability silt and clay layer (see Figure 1). This results in both perched groundwater in the upper sand, and artesian confined groundwater

Saint Gobain Glass Factory Eggborough

Deep Well Dewatering & Recharge Scheme

Saint Gobain Glass (SGGUK) first approached Stuart Wells looking for a permanent solution to rising groundwater issues they were having at their floating glass manufacturing facility in Eggborough. As the site was located within a Groundwater Protection Zone, the project involved working closely with the local Environmental Agency (EA) at all stages in the submission and granting of initial GIC and later groundwater transfer licence.

A conceptual model was developed followed by an application to the EA to undertake a pumping test, under an EA GIC (Groundwater Investigation Consent). The pumping test data was used to finalise the design of the permanent dewatering system, obtain hydrogeological information, abstraction and recharge potential, together with assessment of any environmental impact.

The pumping test involved reinjecting all abstracted groundwater back into the aquifer using recharge wells. The test highlighted issues with recharging and the conceptual model was altered to accommodate more recharge wells than initial envisaged. The final design for a permanent dewatering system and basis

Company: Stuart Wells Limited Country: UK

Client: Saint Gobain Glass

Location: Eggborough, Yorkshire

Duration: June 2020 – February 2021

for an application of an EA groundwater transfer licence consisted of permanent abstraction wells, with all groundwater being recharged back to the aquifer. This consisted of a series of abstraction boreholes around the perimeter of target area to control groundwater level in the Sherwood Sandstone. With all abstracted groundwater transferred via a pipeline to a series of recharge wells located on the site boundary and injected back into the Sherwood Sandstone aquifer.

Between October and Christmas 2020, a total of 6no x 50m deep abstraction wells and 31no recharge wells were drilled, installed, and developed. With approval and granting of the EA transfer licence received before the end of the year, full commissioning and testing of the system including the placement and insulation of the PE recharge pipeline was successfully completed early 2021.

Pumping Test

Ahead of the application to investigate a groundwater source was submitted.

A Water Features Survey to evaluate the impact of the proposed abstraction (dewatering) on the surrounding water environment; sensitive water receptors and abstractions was undertaken by Stuart Wells.

The pumping test was undertaken to GIC conditions and involved the installed of 2no abstraction well and 8no recharge wells, all located and designed to enable reuse in any subsequent permanent dewatering system. Groundwater levels were observed in existing site monitoring wells, together with all identified environmental assists; prior and during the pump test phase. Pump Testing consisted of the following scope: the pump test phase. Pump Testing consisted of the following scope:

Activity

Pre-test monitoring

Equipment Installation and individual operation test

Recovery period

Pumping Test of Abstraction Well No. 1 to Recharge Wells

Pumping Test of Abstraction Well No. 1 and No. 2 to Recharge Wells

Data and information generated from the pumping test was used to model a permanent dewatering and recharge design to comply with both groundwater engineering requirements, in terms of required drawdown, contingency wells to allow for long-term maintenance and environmental objectives and constraints.

The achievable recharge flow rates observed during the pumping test and subsequent modelling identified the need for more recharge wells than initially envisaged, together with additional ongoing monitoring requirements. In October 2020,

Stuart Wells mobilised 2no rotary drilling rigs to site and drilled, installed and developed installed all remaining abstraction and recharge wells over a 6-week period.

415V Caprari submersible borehole pumps c/w level probes were installed within each abstraction well on 2.1/2” steel riser. In turn these connected to a 110mm PE collection main that linked to a 225mm PE recharge main with individual take-offs at recharge well locations.

All wells were housed within manhole chambers with cablings buried and contained within ducting. The pumps were controlled by 2no 4-way variable speed drive pump control panels, that in turn where connected to site mains power supply.

Groundwater levels were monitored using pressure transducer dataloggers and abstraction flow rates recorded by MAG flowmeters. All monitoring data was managed to enable remote monitoring, establishment of an alarm arrangement, all powered by solar panel set up at individual location.

The Project Blankenburgverbinding

Connection between the A15 and A20 near Rotterdam.

Company: Henk van Tongeren & Waterthechniek

Country: Netherlands

Cient: Dutch Government

Location: Blankenburgverbinding, Rotterdam

Duration: 2019 – 2024

The biggest dewatering project in the Netherlands, the project Blankenburgvinding is situated between the A15 and A20 near Rotterdam. Hosted by the Dutch government and contracted by BAAK BV, the highway is about 6km long, of which 4km are tunnels and other sunken locations.

Key factors relating to dewatering:

• Project time 2019 until 2024

• Estimated turnover of E11,3 million

• Deployment of approximately 280 pumps

• A total of 8 kilometres of pipe

Technically challenging pipe

Main contract:

The government has set up a Design and Construct contract. This means that the contractor must arrange all contracts himself, including all water permits. The Water Boards (two for this project) also had to grant its permits. Before getting the permits, the contractor has to make the design first, get approval, and after that, the contractor can apply for the permit.

Soil structure:

The project is near the river ‘het Scheur’ and the soil structure is very erratic, consisting of layers of clay and peat. A typical meander soil structure, it consists of a polder landscape with many different polder levels. The soil is prone to settlement.

Innovation and complexity of dewatering and methods and techniques used

Development of 30 DSI groundwater return wells to reduce the environmental influence of the project area. The groundwater consists of a lot of iron and salt. The dewatering installation is built anaerobically (80%) to reduce the effect of iron in the system. Due to the many different soil layers, there are also many different rise heights in the different layers. During the different soil layers, this was taken into the design of the dewatering installation.

Technical risk identification and mitigation

Environmental influence: Too much lowering of the groundwater level:

To measure the groundwater levels, we installed 122 monitoring levels including divers. With this divers we can monitor 24/7 the groundwater level. As mentioned, the landscape consists of various polders with their own levels. This ensures a specific approach and monitoring requirements for each polder..

Salt water:

The project is located near the North Sea, so the groundwater is very salty. They build a robust system, we use a lot of HDPE material. In addition, we inspect the pipes weekly to determine that they are still good.

Different soil structures:

The centre of the project is the river ‘Het Scheur’. The north port of the project has a different soil structure than the southern part, including different (including different water ports and

Water Boards). The dewatering installation of the northern part is different than the southern part.

HSE workforce safety considerations

The contractor BAAK maintains a zero tolerance policy in the field of safety. In the first place, they punish the employee. If employees of a particular company break the rules too often, the company will be rejected from the project. Before entering the constructions site, every employee receives a safety instruction which is followed with a test. The test has to be repeated every year. BAAK uses several safety coordinates to control safety on the construction site. The construction site has additional safety requirements. Before we can start with our dewatering activities, we make a project specific HSE plan. The enforcement of the HSE plan is checked periodically.

Sustainable methods considered / used

All pumps to be used are electric, powered by a fixed power connection. We only use generators as a back-up in case of a failure. This is the cleanest energy source at the construction site.

As mentioned, we installed 122 groundwater monitoring wells including divers. The measured groundwater level is linked to the control of the pumps. We control the groundwater level with minimal running times of the pumps. The less time the pumps run, the less water is extracted, which in turn results in lower energy consumption. With this, we also limit the environment influence. Less groundwater extraction also results in less settlement risk.

Overall Impressiveness of dewatering project

It is a very large and complex area. Because of the different soil structures and construction methods, the project actually consists of two projects, north and south. Many different stakeholders, such as the Port of Rotterdam Authority, have an interest, and therefore an influence on the work. The planning is often under pressure. This requires us to be very adaptable. As mentioned, the soil is susceptible to settlement and because of the changed planning, we cannot simply carry out any dewatering.

We must first check whether this change will have a negative effect on the environment.

Big Bend Modernization

Company: Griffin Dewatering

Country: Tampa Bay, Florida, USA

Client: Big Bend Power Plant –Tampa Electric

Duration: August 2019 – April 2021

Involves the partial conversion of the existing coal fired Big Bend Unit 1 Power Station into a natural gas 2x2x1 combined cycle plant. The new facility consists of two new combustion turbine generators, two new heat recovery steam generators, and one steam turbine generator. The gross output for the facility will be 1,100 MW.

› Footprint for the new natural gas facility is a 650 feet. x 450 feet.

› Located on peninsula that extends within 100 feet. of Tampa Bay

› The water table is approximately 4’ below the site grade

› Numerous excavations for foundation and pipe work with typical subgrade of 10’ below grade (6’ below groundwater)

› Several deep sumps and an oil/water separator extended to almost 18’ below grade (14’ below groundwater)

Challenging Site Size & Location

The size and location of the site challenged TIC and Griffin to find innovative ways to ensure the system would accomplish the dewatering needed but also be placed in areas that would not get in the way of others working on the site that could possibly damage the system. This was important to ensure there would be no project delays.

Multiple Excavations & Aggressive Schedule

The project had an aggressive construction schedule that included multiple excavations below the groundwater table occurring simultaneously. Numerous excavations of ±10 feet. depth were required in a 650 feet. x 450 feet. area.

Custom Designed & Engineered Dewatering Solutions

Griffin's engineering and operations teams collaborated with TIC during the project design phase to determine the most efficient approach to dewatering the various excavations.

Wellpoint System Installation

Griffin provided dewatering for all excavations by installing a perimeter wellpoint system, which included three wellpoint pump stations (each with primary electric and backup diesel pumps), header pipe, wellpoints, and other appurtenances required for a fully functioning system.

Wellpoint Dewatering System

› System works by installing a 1½” PVC with a wellpoint

› Wellpoints are installed approximately six feet apart then, using flexible swingjoints, connected to header pipe

› The header pipe runs along the outside of the system

› Header pipe is connected to a vacuum pump

› Discharge water at an agreed-upon site location

Performance Testing

Due to the large size and high-water table of the excavation site, it was possible that an additional internal row of wellpoints would be needed to obtain the target drawdown in the center of the site. To help lessen extra cost and time, during the installation Griffin conducted performance testing that indicated that the perimeter system would fully dewater the site without additional internal dewatering efforts.

This eliminated a potential obstacle from the excavation area and saved TIC approximately $100,000 over the course of the project.

Innovative Monitoring System

Griffin provided numerous backup pumps with auto-start functionality and auto-dialers. These systems would alert Griffin and TIC of any pump issues, removing the need of a full-time operation and maintenance crew. This equipment provided a labor savings of approximately $120,000 over the course of the project. additional internal dewatering efforts. This eliminated a potential obstacle from the excavation area and saved TIC approximately $100,000 over the course of the project.

Griffin - The Difference

› Total project cost is estimated at $853 million

› Innovative testing and monitoring allowed initial contract value to drop from $700,000 to contracted scope of $480,000

› Worked closely with TIC to determine the best method to address their concerns regarding access to the site and the potential for system damage

› Pump tests used site's hydrogeologic parameters to verify system design

› Potential excavation issues and O&M labor costs were eliminated, saving TIC over $200,000

› Griffins in house engineering expertise allowed us to design a custom system that would be most efficient and cost-effective

› Griffin began work on August 15, 2019 and completely demobilized on April 7, 2021

› The contract was a combination of lump sum and time and materials charges

› Self-performed 100% of the work with our own labor force and rented all site equipment from fellow ABC members Herc Rentals and Mobile Mini.

iFLUX Sensing

The Dewatering Institute Awards 2021 INNOVATION OF THE YEAR

Company: iFLUX

Country: België, Belgium

Groundwater Treatment

iFLUX supporting paragraph of why the project is the best suited to win the category: Groundwater is an important part of the water system. Groundwater has long been ignored in the overall water system but is rightly receiving more attention. However, it is invisible, and the dynamics are complex, which makes the challenge even greater. iFLUX mission is to make groundwater visible! iFLUX delivers a new generationgroundwater monitoring solutions, based on a real-time IoT sensor network and integrated data system, using artificial intelligence to improve environmental risk assessment by visualizing and integrating the dynamics of groundwater and groundwater pollution.

Core technology is our newly developed groundwater sensing probe which monitors low-flow conditions, combining water levels and infiltration rates with accurate and real-time pollution measurements.

The ability to detect groundwater fluxes in the range of 0,5-500 cm/day, multidirectional, makes it unique in the market. Deploying dewatering systems is controlling your groundwater, without impacting surroundings or extraction pollution sources.

Risk management becomes more crucial as public awareness rises and emerging contaminants become an ongoing concern. By installing our sensing technology, the dewatering sector will take a step towards circular water use and closing the loop by installing even smarter pumping system and infiltrating it again in suited groundwater layers. Impact assessment is done real-time.

Project WalleWolfsburg gas pipeline

IUnique technology

iFLUX Sensing is an innovative monitoring solution to measure groundwater speed and direction real-time either horizontally (in prepack monitoring well) or vertically (directly in the soil).

n general, large infrastructure projects bring with themselves a numerous boundary conditions and challenges that have to be considered by the companies carrying out the work. This was also the case with a gas infrastructure project between Braunschweig and Wolfsburg, for which Hölscher Wasserbau GmbH was commissioned with the dewatering and water treatment works.

The gas pipeline in question was laid over a total distance of 30 kilometres between the cities of Braunschweig and Wolfsburg. In future it will ensure energy supply to the VW plant and the city of Wolfsburg with the help of two ultra-modern gas-fired power plants on the VW plant premises in Wolfsburg. The switch from coal to gas will lead to a significant reduction in CO2 emissions and is an important measure taken by the VW Group to protect the climate.

Challenges

Along the entire stretch of the gas pipeline Hölscher Wasserbau GmbH had to contend with constantly changing groundwater management requirements. Whilst in some places it was possible to simply lay the pipelines in dry ground, other sections of the route laying beneath the groundwater table would require dewatering and accompanying water treatment procedures in constantly varying intensity and scale. In all cases, simply pumping the excavation pits empty, i.e. open dewatering, was no longer sufficient. In addition to this, the issue of climate and environmental protection was always at the forefront of this project: the aim was to keep the impact on nature as small as possible during the entire construction phase and to meet the strict requirements for water protection. To achieve this, Hölscher Wasserbau GmbH developed a sophisticated system of various pumps not only dewatering the water intrenched section of the route, but also transporting the water to a central groundwater purification plant.

Technical implementation

In order to temporarily lower the groundwater level during the construction phase (closed dewatering), Hölscher Wasserbau GmbH first set up vertical filter wells in the excavation pits and installed electrically operated high-

Company: Hölscher Wasserbau GmbH

Country: Germany

Client: VW Plant in Walle-Wolfsburg

Location: Northern Germany

performance pumps. A further hurdle to overcome, was implementation of a permanent and stable power supply to keep the pumps running non-stop and to ensure round the clock groundwater management.

By means of booster stations, the water pressure in the previously laid pipelines transporting the water from the excavation pits was increased enabling the extracted water to be transported to the groundwater purification plant. There it was tested for impurities and purified accordingly, before being re-infiltrated back into the natural water cycle. The tailor-cut groundwater purification plant was characterised by a total capacity of 150 m³/h and various purification stages. The system was operated with high base pressure and high volume, which resulted in high energy consumption, compensated by two 400 kVA power generators providing the necessary energy around the clock. Each equipped with a double oil sump and extra-quiet motors, not only performance but also all environmental requirements were successfully addressed.

In addition to the centrepiece of the project, the groundwater purification system, various water pumps (Grundvos single and stage pumps, Netzsch positive displacement pumps and various submersible pumps) were in use on the entire track construction site to ensure round the clock groundwater management. Particular care was required at road crossings and other

structures crossing the track construction site, as the dewatering here differs significantly from other "normal" sections of the route. Uncontrolled leakage of water on the passage to the treatment plant was to be prevented at all costs, and continuous operation of the entire system was required. Various pumping and booster stations were therefore built to ensure the smooth running of the water, even under challenging conditions.

In order to be able to guarantee a safe power supply even in the case of unexpected failure or maintenance work, so-called back-up sets have been installed for additional protection. In addition to the power generators in continuous operation, there was a redundant emergency power generator that automatically took over the power supply if required. The fuel supply was ensured by means of level gauges integrated in the tanks of the power generators, external 1,300 litre tanks as well as large 16,000 litre tank containers.

Conclusion

Through the engineering design devised by ourselves and the resulting dewatering system and groundwater purification plant, Hölscher Wasserbau GmbH has been able to not only make a substantial contribution to a large infrastructure project, but also actively contribute to climate protection. Our focus during the entire project was on a type of groundwater management in balance with climate protection.

Water Infrastructure Land Restoration

Site Remediation Agriculture

case

Drilling to augment urban water supply

Company: Umvoto Africa

Country: South Africa

Client: Department of Water and Sanitation

Umvoto Africa (Pty) Ltd (Umvoto) has 30 years’ experience in the groundwater industry and has undertaken numerous groundwater development projects across all aquifer types throughout South Africa and Africa, including fractured rock aquifers (TMGA), basement aquifers (Malmesbury Group, Cape Granite Suite), primary aquifers (Cape Flats Aquifer [CFA], Atlantis Aquifer), and karstic aquifers (Malmani Dolomites).

Umvoto has played an integral role in assisting the City of Cape Town (CoCT) to develop alternative bulk water supply, initiated with the Table Mountain Group Aquifer (TMGA) project as early as 2002 (see Figure 5). Prior to 2017, TMGA exploration phase work undertaken by Umvoto had already proven the feasibility of large-scale groundwater abstraction from the TMG aquifers. Through the feasibility study, select production drilling target zones (wellfields) with a clear geographical linkage to the existing surface water supply infrastructure for future groundwater development were identified and delineated.

The recent “Day-Zero” drought experienced throughout the Western Cape between 2015-2018, forced local government to seek alternative water resources to augment bulk water supply. These included re-use, desalination and various groundwater resource development initiatives, including the TMGA and CFA, as part of the New Water Programme (NWP), which was initiated in 2017.

Historically, an abundance of literature about the potential of the CFA prompted the interest into exploring this resource for groundwater production. Umvoto undertook a Situation Assessment of the CFA in 2014 to evaluate the potential of the CFA for bulk water supply and provided recommendations on using the aquifer with an adaptive management approach and thereafter developed

the Cape Flats Aquifer Management Strategy (2015) on behalf of the Department of Water and Sanitation which outlined measures to remediate and use the aquifer sustainably. Initial exploration of the proposed Cape Flats Aquifer Management Scheme (CFAMS) commenced through an airborne electromagnetic and magnetic geophysics campaign to define the lateral extent, thickness, and aquifer geometry over the delineated aquifer area. Accessible areas where higher groundwater potential zones were identified, were targeted for exploration drilling.

basal formations of the tripartite Cape Supergroup particularly focusing on the fractured aquifers of the mature quartz arenite dominated Table Mountain Group (TMG). Selected target zone areas aimed to intersect major structural feature(s) of hydrogeological interest (also referred to as hydrotects). The two main targeted TMG hosted aquifers included the locally unconfined to semi-confined Nardouw Aquifer and deeper confined Peninsula Aquifer. The interstitial Winterhoek Megaaquitard acts as a confining unit for the underlying Peninsula Aquifer, with associated deep confining high pressure (>10 bar) artesian conditions.

The CFA is a Quaternary unconsolidated, primary, coastal aquifer which covers an area of ~488 km2 from False Bay in the south to Tygerberg Hills and Milnerton in the northeast and northwest.

Deposited by varying laterally extensive fluvial, marine and aeolian palaeodepositional processes, the vertical and lateral heterogeneity of the CFA is complex and not well understood. Target aquifer material generally comprises of palaeo-channel quartz-rich gravels with clay and peat of the Elandsfontyn Formation, fine to medium-grained sands with shells of the Varswater Formation and the well sorted and rounded, fine to medium-grained mature sands of the Springfontyn Formation. Collectively these target formations form part of the major CFA (refer to Table 1).

On the other hand, the TMGA study area is set within the structurally complex (Cape Fold Belt syntaxial zone)

9 target zone wellfields

Total of 285 boreholes drilled (NWP 2017-2021)

Total Meterage: 11 153m

Consisting off:

25 MAR Boreholes

72 Production (average recommended yield: ≈9 l/s)

184 exploration/monitoring

Total of 1343 m sonic core

Expected cumulative abstraction of 55 Ml/day with MAR

25 Ml/day without MAR

The diversity of the aquifer settings and targets related to each of the project areas required vast research into specific drilling techniques to meet the target design requirements for each setting. For the TMGA, this entailed the drilling of comparatively shallow (~150300 m; still considered deep in most of Africa for water supply) and deep (>800 m) wide-diameter Nardouw and Peninsula Aquifer production boreholes (telescopic 586-152 mm diameters), respectively. Prior and concurrent to wellfield development, exploration core drilling (123-60 mm diameters) informed potential production borehole design, hydrostratigraphic conditions and expected challenges. A total of 49 production and exploration boreholes were drilled. Additionally, the exploration boreholes were incorporated into the robust multitechnique monitoring network, allowing aquifer conditions to be monitored throughout the various phases of wellfield development.

From the inception of the CFA project in early 2018, 285 exploration, monitoring, production, and Managed Aquifer Recharge (MAR) boreholes were drilled throughout the target areas identified in the Cape Flats . Initially, exploration (203 mm diameter) and production borehole (457 mm diameter) drilling took place simultaneously. (cont.)

Table Mountain Group Aquifer (TMGA)

3 major target zones wellfields

12 target site area cluster

10 core boreholes drilled during Exploratory Phase

Total of 49 boreholes drilled (NWP Phase 2017-2021)

Total meterage: 20 319m

Rotary wireless core:

32 boreholes in total

13 213m total

40-949 mbgl depths

Wide diameter boreholes:

13 Nardouw (3106m) - 8 selected for production (>5-50l/s)

4 Peninsula (400m)

134 to >1000 mbgl depth

Total of 13 213m of core

15-20 Ml/day (Steenbras Wellfield)

study of the Cape Flats and Table Mountain group aquifers - Umvoto. Cape Town, South Africa.

Cape Flat Aquifer (CFA)

This approach ensured that a monitoring network was established through the repurposing of exploration boreholes. In addition to exploration and production boreholes, the CFAMS requires a MAR component comprising of productiondiameter injection boreholes. A single test injection borehole with a diameter of 1016 mm was drilled to compare its efficiency, operation and clogging potential to the more standard 304.8 mm stainless steel casing.

Both the TMGA and CFA project areas faced unique challenges, including a host of hydrostratigraphic, environmental and socio-economic factors, which had to be overcome during each drilling phase. The major factor contributing to challenging drilling conditions throughout each project area was the complex geological settings. In the TMGA this included extremely competent TMG quartz arenites, structural complexity, highly unstable fractured, brecciated and gouged fault zones, and large pseudokarstic cavities. The vertical and lateral lithological heterogeneity of the CFA and TMGA posed borehole design challenges that required adaptive approaches to the construction designs.

To overcome the geological onditions in the TMGA, various drilling methods were used to achieve target drilling depths, diameters and yields. Exploratory diamond core drilling was undertaken with the primary focus on locating (depth and contacts) and hydrogeologically classifying the Nardouw and Peninsula Aquifers. Wide-diameter boreholes targeting the Nardouw Aquifer, relied completely on the traditional Down-The-Hole (DTH) rotary air percussion drilling technique. This is the most cost effective and rapid drilling technique for shallow targets in fractured aquifers. The reverse circulation (RC) air percussion method was used interchangeably with the DTH method to maintain target drilling diameters at depth and adhere to strict environmental protocols.

Drilling advance and productivity in both surface pneumatic air percussion methods was largely limited by the uphole velocities required to overcome the hydraulic head, which increased with depth and high-yielding water strikes. Boreholes targeting the Peninsula Aquifer, were initially drilled using the same air DTH and RC method up to ~250 m, whereafter the limit to up-hole velocity and drill operating pressures, required a shift to a non-air reliant technique. The rotary flooded RC technique was used for drilling between depths of ~250 m and 800 m and served to simplify environmental mitigations and advance through deep, unstable (fractured, faulted

and/or heterogenous) lithologies. It is notable that the use of tri-cone bits and the flooded RC technique prior to the TMGA project deep drilling was novel for TMG boreholes. The water hammer technique was utilised in the last >800 m of drilling, where significant hydrostatic water column (>80 bar) and artesian pressures (up to >10 bar) were encountered. During use, the water hammer technique achieved extremely fast penetration rates of 3-6 min/m and minimal hole deviation.

In addition to site specific environmental method statements, on-site control officers and general mitigation measures, it was critical to completely isolate the target aquifers and seal off unwanted water strikes related to non-target TMG lithologies. This was achieved through the final installation sequence of annular grouted casing sets. In the deeply confined Peninsula Aquifer target boreholes this comprised of a tapered 256-203 mm set of 8 mm thick (1400 psi collapse strength) steel casing. Casing and sealing throughout the drilling process additionally served to ensure environmental compliance (no uncontrolled annular artesian discharge) and critical borehole sidewall integrity.

Due to the lithological heterogeneity of the CFA, a number of techniques were trialled and used for the drilling of the boreholes. Overburden Drilling EXcentric (ODEX) was attempted but failed due to the soft unconsolidated nature of the sediments.

was used and a total of 36 sonic boreholes were drilled. This technique was the most accurate for identifying and logging lithological changes, and proved to be cost effective, with the boreholes then been included into the monitoring network.

The pristine setting of the TMGA within the Cape Floristic Kingdom (and corresponding protected areas and reserves) meant that all contractor activity had to be stringently planned, managed, and monitored to ensure limited impact to rare and endangered flora and fauna. Contrastingly, CFA mostly underlies densely populated residential and informal settlements, industrial - commercial and agricultural areas. Accompanying the densely populated surface area, an array of contamination hazards and complex social conditions was encountered throughout the project tenure. Additionally, numerous existing groundwater users, such as the farmers of the Philippi Horticultural Area (PHA), had to be taken into consideration during the design of the CFAMS. This was all undertaken whilst being accompanied by armed security, for the safety of consultants, contractors, and equipment alike.

Majority of drilling was undertaken using the mud rotary drilling technique as this was the most cost effective and allowed rapid drilling of narrow and widediameter boreholes

Ultimately each drilling technique has its pros and cons, and is dependent on the type of geological material, accuracy of data required and target depth that needs to be achieved. Implementing multi-technique drilling technologies has allowed Umvoto to achieve >1000 m deep boreholes targeting the Peninsula Aquifer in the TMGA project. Identifying the need for accurate lithological detail in the CFA, has given Umvoto the opportunity to accurately site 25 injection boreholes for recharge, and plan for future MAR expansion, which is a step towards sustainable management.

The lithological heterogeneity proved to be complex for the siting and planning of MAR boreholes. Discontinuous clay lenses needed to be accurately identified to ensure recharge would not cause any surface flooding. To overcome these and to ensure efficient planning, the air core drilling was tested, but due to the creation of possible cavities the method was rejected and therefore, sonic drilling

The challenges were overcome by combined planning, continual adaptation and mitigations initiated between the hydrogeological sub-consultant (Umvoto), drilling contractors, consultant ECOs, client, and specialists. Umvoto’s extensive experience in the applications of various drilling techniques in a variety of aquifer settings played an integral role in this. The truly innovative and integrated approaches resulted in a standard being set for large scale diverse aquifer-targets for South African municipal supply. Additionally, the TMGA boasts with producing the deepest wide-diameter municipal water supply boreholes in the Western Cape.

Groundwater Specialist appointed as TDI Advisory Council Member

Bronson Gerken, P.G., has been in the dewatering industry for over 11 years and is the Vice President of the Technical Services department at Griffin Dewatering. He obtained his Bachelor’s in Geology from the University of Nebraska at Omaha and is a licensed geologist in the States of Kansas, Nebraska, California, Florida, North Carolina, and Washington.

Bronson has been involved in numerous groundwater control projects across the United States and currently leads a team of geologists and engineers in designing groundwater control systems to meet each of their client’s needs. He has had the opportunity to be involved with multiple aquifer pumping tests, has become proficient at creating and understanding groundwater modelling, and has come to understand proper water well construction and design.

Can you tell us more about your work history and how you got into the dewatering industry?

I started in the dewatering industry as an intern in 2011 at the Omaha, Nebraska Griffin Dewatering location. I had very little understanding of dewatering at the time and was actually applying for a labour position (just needed a job!). The local office manager saw that I was studying geology and invited me to interview as an intern instead. was incredibly excited about the opportunity as it combined my interests in both hydrogeology and engineering. Shortly after being hired as an intern, I also attended a summer field camp with a focus on hydrogeology which was very helpful as I began my career in

dewatering. Since then, I have worked on projects all across the United States and Canada and was given the opportunity to lead Griffin’s design team as the Vice President of Technical Services. During my tenure at Griffin, we have also added several new services which I have been able to assist with and learn about including temporary water treatment services and comprehensive permitting services.

Griffin has been a great place to work, and I have learned a tremendous amount about the dewatering industry over the 11 years I have worked here.

I look forward to many more years in this industry!

What are your favourite projects that you’ve worked on in your career?

I have worked on some very interesting projects over the years. My favourite types of projects are dams/levees and commercial high-rise structures. These are challenging but rewarding projects and often entail a temporary water treatment component as well. The Alexan Bus Depot (which was the 2021 TDI Treatment Project of the Year) is a great example.

Another interesting project was the dewatering of a 35-foot deep tunnel at

dewatering system’s performance remotely to understand flow and drawdown so we can alert our clients of potential issues. Groundwater modelling software has also become a staple of a thorough dewatering analysis. We regularly create groundwater models during the design process to give us additional insight into how a system might perform or what impact shoring/ adjacent water bodies/variable geology might have on the system design.

As stated previously, permitting and other regulations have changed over the years which has required additional testing of the dewatering effluent prior to discharge. Temporary treatment of dewatering discharge has been an increasing occurrence because of this, especially as new contaminants and regulations are encountered (i.e. PFAS).

How do you see technology playing part in the industry in the future?

an airport which was a great example of a pressure relief project to prevent upheaval of the excavation bottom. We were able to perform a comprehensive pump test as part of our dewatering plan and ended up installing a temporary treatment system to handle hydrocarbon contaminants.

What are some of the biggest challenges you’ve seen in the industry?

Project specifications and requirements, especially when it comes to permitting, have grown more robust over the years. Keeping up with changing regulations and finding ways to meet them can be a challenge. Many times, these regulations stipulate what means/ methods we must use to install a particular system or regulate where we need to discharge and treat the water. We have greatly expanded our own permitting department to help keep up with this evolving industry. Besides finding and maintaining proper personnel, another challenge currently is the supply chain and rising cost of materials. This is especially difficult in a bidding environment as most projects are estimated/bid several weeks/months prior to mobilization.

How have you seen the industry develop over the past decades?

The use of technology, especially as it relates to project plan review and telemetry systems for monitoring, has been a tremendous development. It is extremely beneficial to watch a

Technology plays a large role in the dewatering industry, both in the initial design and in the field. Advancements in modelling software have been a tremendous help with designing complex dewatering systems and determining required flow rates. In the field, telemetry systems can allow us to monitor drawdown/flow/ system performance remotely and can alert operators if something in the system is out of balance and/or fails. Advancements in these technologies and many others will continue to positively impact the dewatering industry going forward.

Why would you recommend younger generations a career in the dewatering industry?

Dewatering is a unique mixture between geology and engineering and provides a broad understanding of both fields. Groundwater is largely misunderstood, especially when it comes to construction. If construction projects go below the ground surface, groundwater control will be a necessary industry. No two projects are ever alike either, so this field offers a lot of variety and the opportunity to learn something new each day. Interning for a dewatering company and spending some time in the field is a great way to get started in the industry. If you have an interest in both science and engineering and want a lot of variety in your work, dewatering is the perfect fit!

What aspects of the industry do you think need improving?

There is a lot of misunderstanding when it comes to groundwater and the impact that has on excavations. Additional education, such as what TDI offers, is key to helping everyone understand what dewatering is and how it positively impacts a project. A thorough understanding of ground-water helps owners and contractors be proactive when it comes to developing

a groundwater control solution rather than reactive when an unanticipated problem is encountered. It can also affect what information is obtained during the geotechnical phase of a project (ie. Piezometer installation, pumping tests, water quality, etc) which in turn provides additional insight regarding the potential groundwater impact on the excavation. Planning a dewatering system in advance can have a tremendous impact on the schedule, budget, and risk of a project.

Why do you think TDI is important for the industry and how it can help the industry develop?

TDI provides a perfect platform for educating contractors, consultants, and engineers on the intricacies of dewatering. There are many facets to a dewatering system and the impact it can have on an excavation, from the type of system, proper well design, and even how to temporarily treat the water prior to disposal. TDI is broadening the understanding of dewatering across the entire construction industry so that projects are ultimately on-time and on budget.

What was the greatest encouragement someone gave you regarding business?

To never give up. There is always a solution to a potential problem, sometimes you just need to look at it from a different angle. This is especially true in the dewatering and water treatment industry where the answer to a problem is not always obvious right away.

What is your life motto?

Don’t expect perfection from geologists; they all have their faults!

First Africa Guide

First Africa Guide celebrates its 4th year proudly serving the latest events & news while connecting suppliers to the ready industry market.

The year 2023 is around the corner and we are looking to extend our digital footprint with more media partnerships and corporate digital banners, newsletters & videos. Get on board.

Reach your audience with our other publications below

Bronson Gerken. Vice President - Technical Services at Griffin Dewatering - United States

Trashing Trash

en route

San Francisco Bay

By Henry Hoffman

Ever noticed storm drains in your neighbourhood with either stencils or medallions indicating dumping will drain directly to the Bay? Or wondered how this drainage system might be different from the one in our homes?

The water that goes down our sink and shower drains ends up in a wastewater treatment facility where the water is filtered and treated. Stormwater, however, flows directly into storm drains, where it ends up in streams, lakes, and open waterways without undergoing any treatment process. When water flows across roads, roofs, and sidewalks, it carries trash into the storm drain system. Stormwater run-off can also pick up household chemicals, paint, motor oil and other harmful pollutants as it makes its way to San Francisco Bay. A study conducted in 2020 estimated that four million gallons of trash is present in our urban streams, degrading water quality, destroying habitats and affecting communities’ mental health. Because stencils and medallions are not a strong enough protection, it is critical the region works collaboratively to install Full Trash Capture Devices.

Trash and other debris is collected in six pipes 480 feet in length, while 650 gallons of water continues to flow. It is designed to tarp paper, plastics, glass, and screens 100 percent of objects five millimeters in diameter and above, because cigarettes are the most common element of trash.

Natural drainage areas help us understand where Full Trash Capture Devices can be the most effective. Site 2, which indicates the device’s location, is strategically located to ensure trash is captured within the 2620-acre red boundary. The boundary includes trashgenerating portions of interstates 580 (green highlighted area) and 238 (yellow highlighted area).

“ ”

Is there a durable, reliable, and customised way to prevent garbage and debris from making its way through your stormwater system?

The watershed begins along the ridge just Southwest of Lake Chabot, where run-off travels through residential and commercial areas of San Leandro to the Estudillo Canal, which is designed to hold up to 365 tons of trash.

Emptied two to four times per year, with a high-pressure hose and vacuum, it can take up to three days to fully remove all of the debris. Some of the larger items have to be removed manually, like this box spring pictured to the right.

How is Save The Bay involved in this effort?

The San Francisco Regional Water Quality Control Board, which enforces the Clean Water Act, requires Bay Area cities and Caltrans to reduce their stormwater trash to the Bay to zero by 2025. Save the Bay is pushing to get Caltrans and cities to form partnerships, like the Estudillo Canal project, an agreement between the Alameda Countywide Clean Water Program (ACCWP) and Caltrans.

Below is a link to an example of a custom-designed system, which has helped prevent garbage from flowing into the ocean https://roscoemoss.com/products/ storm-flo-screen/

Read the feature and watch a video that shows how it works.

For help on stormwater solids removal, reach out to us at https://roscoemoss.com/products/ storm-flo-screen/

Full Trash Gross Solid Removal Device Installed in the concretelined Estudillo Canal channel in 2019.

The Dewatering Institute; bringing together the global dewatering industry

The Dewatering Institute (TDI) is a global platform that brings together the dewatering industry internationally, through a knowledge sharing platform and by promoting best practices. The network includes practitioners from across the industry including mine dewatering, construction dewatering, groundwater control and covers Geotechnical Investigation, Hydrogeology, Drilling, Ground Source Energy Wells,Design, Pipeline, Pumps, Power, Monitoring, Groundwater Treatment, System Operation, Groundwater Recharge, System Decommissioning and more.

To date TDI has had some incredible achievements since its inception in 2020. Notably, the community has grown to include 56 members across the globe. Collaboratively, the community contributed to an extensive knowledge base and delivered [x-number] informative webinars to share industry knowledge.

The 2021 year was filled with many achievements and first for TDI including the inaugural TDI awards and the very first golf day, held in the Western Cape, South Africa. One of the biggest accomplishments of 2022 is the launch of this magazine, the GEM, along with continued growth of the community and knowledge center.

TDI Advisory Council

We have a diverse Advisory Council that brings the required expertise to cover our mine dewatering and construction areas for the institute. Delivering effective dewatering solutions require an in-depth

understanding of the external factors and parameters that may impact a mining operation. Therefore, it is crucial to promote best practices directly from professionals. This year we expanded our Advisory Council board by appointing, Vice President of Griffin Dewatering, Bronson Gerken and a Graduate Advisory member Francois Gous that is currently employed as a Geohydrologist/technical engineer for Project Dewatering Limited (United Kingdom) while also enrolled at North-West University (South Africa) completing his Master’s degree in Hydrology and Geohydrology.

Fundamentals, advantages of becoming a TDI member

TDI’s fundamentals are Education, Knowledge Sharing, Best Practices and Networking. These are put into practice through a range of activities including webinars, training courses, case studies, short guides, and continual professional development. Networking

and brand exposure provides members with a variety of new opportunities to reach a broader audience, through social media, events, blog posts and newsletters. “The events and training courses are crucial to elevate and improve the employee’s knowledge while simultaneously networking with fellow industry professionals across the globe,” explains Christoffel Botha, TDI Advisory Council member. “Our platform brings together players from across the industry. TDI’s purpose is to serve all members and collaborators from the entire life cycle of a project.” As a member of TDI, you will have access to all resources and case studies shared others to promote knowledge sharing within the industry.

TDI Members

Founding members that are supporting TDI in expanding the community include Griffin Dewatering LLC, Asiawaterjet Equipment, Roscoe Moss Company, Stuart Wells Ltd, Carl Hamm Pipes and Pump Solution, Van Tongeren

Watertechniek, Holscher Group, Hydroserv International and Layne ‘A’ Granite Company. Companies that have recently joined TDI include ‘Royal Eijkelkamp’ as a company member and ‘Smartrek Technologies’ as a contributor. Plans moving forward

In the coming years, TDI will focus on building our network and knowledge center and developing best practices across the industry.

We will continue to offer our now well established monthly webinars as well as offer longer courses taught for our member by our members.

“ ”says Christoffel.

TDI’s future plans involve creating industry guidelines using the know-how and practical expertise gathered through the members with diverse topics of focus within the industry and ultimately to establish TDI as an accreditation entity within the dewatering industry.

How to become a member of TDI?

Becoming a TDI member means you get to be a part of a growing and thriving community of industry specialists. Reap the rewards of knowledge-sharing, education, best practices, and networking within the dewatering industry. TDI’s purpose is to serve all its membersand collaborators including project owners, government bodies, engineers, contractors, manufacturers, and suppliers.

To stay up to date

Follow the latest developments in the industry visit the TDI website www.dewateringinst.com, subscribe to the newsletter and follow TDI on social media.

To register as a member contact TDI on admin@dewateringinst.com

Riëtte

Laas

Business Associate Director in

TDI Events

Corne Engelbrecht from GEOSS South Africa Pty Ltd Groundwater and Earth Sciences presents: Part 1 – Borehole Hydraulics (Well efficiency and clogging).

29 June 2022 WATCH HERE

Umvoto Webinar:

TDI Award Winner Wells / Drilling & Finalist Sustainability Excellence Project of the year.

27 July 2022 WATCH HERE

iFLUX Webinar:

TDI Award Winner Equipement / Material innovation of the year. Discover the latest groundwater innovation, real-time monitoring of groundwater flow and direction.

28 September 2022 WATCH HERE

Hydrogeek Consulting Webinar:

Decision Support Groundwater Modelling. Find out how groundwater modelling is used as a decision support tool.

26 October 2022 WATCH HERE

Upcoming 2023

TDI Award Ceremony: 30 March 2023 BBA Pumps Webinar: 24 May 2023

Joe Sopko – Keller Training Webinar

TDI Award Ceremony 2021

Executive member visit to Van Tongeren Watertechniek

WJ Groundwater - Training Webinar

Christoffel Botha visits Hölscher Wasserbau

Winners of the first TDI Golf Day

Griffin Dewatering –Training Webinar

TDI presenting at the Ground- water Conference, South Africa

Vietti Slurrytec - Training Webinar