Borehole Drilling with Base Titanium

It was late June when we, the water club members, headed to Base Titanium for a field trip on borehole drilling. Not only did we learn about borehole drilling but also about fire extinguishing. Geoffrey Wekesa (our club patron), Willy Sasaka (hydrogeologist), and Geoffrey Mwania (our guide from Base Titanium) helped us on this visit.

We learned that a borehole is often drilled to tap water from underground. Different types of ground material moves out when the hole is being drilled. We learned about two types of borehole drilling:

  1. Air drilling – this type uses an air compressor: This is where air from an air truck is put in a drilling rig so that air can be compressed to the hole so that it can be drilled.
  2. Mud-drilling – this type uses water when drilling: This is where two water holders are dug. An amount of polymer is added to one of the water holders, a truck is connected to it so that it can transfer the polymerised water to the drilling rig. The drilling rig is than connected to a drill bit and the polymerised water is transferred to the hole being drilled. The polymerised water that will have been used will then be transferred to the second water holder. It will contain different types of ground materials which will have been emitted from the drilled borehole. The water will settle out the material and then be transferred to the first water holder again. The polymer that is added to the water is slippery, so as to prevent collapse of the walls of the hole being drilled. It is non-biodegradable; that is, it cannot be changed to a harmless natural state by the action of bacteria.
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Written by Zuhura Adam

Note: Some drilling polymers are biodegradable (often made from guar gum), but they are prone to rotting during the drilling process, especially in the ambient temperatures that are common in Kwale County. So drilling contractors here use non-biodegradable polymers instead. They use two types, commercially known as Poly-Bore and EZ-MUD. Both are manufactured by Baroid Industrial Drilling Products and are not ecotoxic. Although they do not biodegrade, they can break down naturally by UV radiation if left exposed to sunlight for long enough. They can also be chemically broken down. After drilling is complete, the drillers add granular Chlorine 60 (calcium hypochlorite) mixed with gravel to the annular space to disinfect the borehole and, in the process, break down (denature) the polymer. The annular space is the gap between the outside of the pipe that is inserted into the borehole (also referred to as casing) and the sides of the hole (called the wellbore). The borehole is then ‘developed’ – a process that clears out fine drill cuttings and dirty water (including the denatured polymer). Water is pumped out of the borehole and monitored for physical and chemical parameters until only clean water is coming out – meaning it is free from fine suspended materials and has stable pH and electrical conductivity. At this point the borehole is no longer impacted by the polymer or other effects of drilling and the water can be used.

All About Aquifers

It was on Sunday in June, at 10 AM we left for Munje where Saskia Nowicki has come to stay while working in Kwale. We arrived and we were arranged into three groups of nine. Our first activity was measuring how deep the water was at one of the wells nearby. We were accompanied by two colleagues who are working with Saskia. Achut and Heloise explained more of the machine used for measuring depth and we found the water was 6.25 m deep.

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We also engaged with other activities to find out:

  • Between sand and gravel which holds more water?

We used two small cups, one filled with gravel and the other with sand. Water was filled in syringes and delivered to the two cups [until they were full]. The water left in the syringes was subtracted from the measurement before it was delivered and it was found that the sand held more water than the gravel.

  • How water in the aquifer is recharged: what is the speed of water passing through different materials?

We watched an experiment testing different materials and how they allow the passage of water. [Materials were in buckets that had holes in the bottom for drainage] The materials were:

  1. Empty bucket
  2. Bucket with gravel
  3. Bucket with clean sand
  4. Bucket with garden soil

The bucket with gravel had the ability to pass water as fast as the empty bucket. This shows that gravel in the ground can allow water to move through it very quickly. [The bucket with sand passed water more slowly but all of the water did drain out. The bucket with soil passed some water quickly but not all of it. By the time the experiment ended a lot of the water still had not come out of the soil. This shows that soil can hold on to water, which is important for plants that grow in the soil and use the water that the soil retains.]

  • How water in the aquifer is polluted?

The set up was in a clear plastic box where we put gravel and spread it to the sides of the box making a depression (to be a lake) in the middle and half filled it with clear water. Then we mixed a beaker of water with food dye and then poured it into the set up at one of the sides. It showed that the pollutant could easily pass through the gravel structure and mixed with the pure water.

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  • How water is cleaned using [activated] charcoal?

The challenge was how we could clean polluted water with charcoal. We added charcoal to a small cup and pumped [pink] water from the trough used in the above experiment to half fill the cup. We covered the top of the cup with filter paper and it was left [to allow the activated charcoal to absorb the impurities]. We then delivered the water [by pouring it through the filter paper] into another cup. The water that came out was clear.

  • How water is pumped out of an aquifer and how pollutants move around?

The set up was tested with two boxes whereby one had gravel at the bottom, a layer of clay to act as a confining layer that does not allow water to pass through, and a layer of sand at the top. Two holes were made at the sides where one hole had a handpump [a small plastic pump was used] and the other hole represented a latrine (a tube with a syringe that contains coloured water to act as a pollutant). [The handpump went into the bottom gravel layer and the latrine went only as deep as the top sand layer.] Clear water was rained on the top of the sand and it moved [through the sand and into the bottom gravel layer] through some spaces left in the layer of clay that act as fractures to the layer of gravel. Water was pumped out and the polluted water in the syringe was delivered in. The layer of clay has fractures and the layer of gravel has a lot of spaces so the pollutant water passes through easily and hence spread to the pump, when this happens in real aquifers it is dangerous for human consumption.

The second box had the sand layer at the bottom then the clay layer [covering only haf of the box] then the gravel layer at the top. A handpump [went into the bottom sand layer] and the latrine on the opposite side [went into the top gravel layer]. Clear water was poured like rain and passed easily through the gravel layer and reached the sand layer on the side of the box where there was no clay layer. It was pumped and the water came out dirty [Nylon stocking was used as a screen on the bottom of the tube attached to the plastic pump but some of the sand particles were fine enough to pass through the screen and get pulled up into the tube along with the water. That is why the water came out looking brown. This did not happen with the first box because the pump was pulling water from a gravel layer and the bits of gravel were too big to pass through the screen, so only water was drawn into the tube. Screen size is an important consideration for boreholes/pumps in real aquifers]. Pollutant water was then poured in the latrine and it spread slowly at the sand layer and was eventually pumped.

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Written by Siti Nassor

A lot of the activities described by Siti Nassor were done using Awesome Aquifer Kits that are sold by the Groundwater Foundation. The video below shows how these kits can be used to demonstrate some basic groundwater concepts.

The students also spent some time watching videos, like the one below, that explain why groundwater is an important resource. 

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Measuring the Rain

The Kingwede water club installed a rain gauge at their school so that they can understand how rainfall is measured and learn about rainfall variability. Michelle Cherop tell us how it’s done:

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By: Michelle Cherop

The installation was on 5th May 2017 with help from Rural Focus Ltd: Calvince Wara, Ali Dola, Said Banje and Geofrey Wekesa.

A rain gauge is used to measure the amount of rainfall received in an area. In this case, the water club will use it to approximate the rainfall received in our school.

Requirements of installation of a manual rain gauge are:

  • Cement,
  • Gravel,
  • Spade/digging tools,
  • Water,
  • Tape-Measure,
  • Rain gauge, and
  • a stand.

The parts of a rain gauge are:

  • Funnel: Direct the water to the measuring cylinder.
  • Measuring Cylinder: Measure the amount of rainfall in a given period.
  • Jar: Collect the overflow water from measuring cylinder.
  • Stand: To support the rain gauge

Procedure:

  1. We dug a hole of 50cm below the earth’s surface using a jembe and a talimbo (digging tools).
  2. We mixed the cement, gravel sand and water.
  3. We kept some amount of the mixture to the hole then we placed the stand in the hole while we continued to add the mixture to the hole and levelled it.
  4. We fixed the rain gauge to the stand.

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Our manual rain gauge is 80cm above the ground to avoid backsplash of water into the rain gauge and to avoid running water entering the rain gauge. The stand is metallic to prevent it from being destroyed by pests. Our rain gauge is located in an open [area] and free from trees and buildings. It is on a flat area/land to stabilize the rain gauge.

Importance of measuring rain:

  • Helps the farmers to know when to prepare the land for farming.
  • Also helps the farmers to know the types of crops to be planted in a certain area.
  • Helps the people to know the types of clothes to wear on a particular area and season.
  • After some time it can help us to know if amounts of rain are changing.

Water Management at a Titanium Mine

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By: Fatma Posho

On Wednesday 17th the water club members visited Base Titanium to know how they recycle their water after mining since they use water during mining. Base Titanium is a company found 50 km from Mombasa, 7 to 11 km from the Indian Ocean and location in Kwale County. Its mine construction started in 2011.

Titanium was discovered [in the coastal area in the 1950’s and further exploratory campaigns were conducted in the 90’s], they noticed the minerals and experts were called to survey and found three minerals. These are:

  • Rutile
  • Ilmenite
  • Zircon

We visited the central dune where the Muku dam is located and its source in Mukurumudzi River. The spillway was constructed to prevent the wall from breaking during floods [it protects the dam from damage by allowing excess water to flow out of the reservoir]. Fishing and swimming activities aren’t allowed because water is so deep (max depth 20 m) and also it is risky because crocodiles are found in the water.

No swimming sign above the Mukurumudzi dam.

We visited settlement ponds which were three, and their purpose was to remove sediments from water. Settlement C was the furthest settlement pond where it had gabions on its side to prevent [erosion] and trap soil particles [from the pond banks] to have clear water where it is recycled back to the plant.

Gabions where water returns to Mkurumudzi river below the dam
Gabioned channel downstream of the dam where water returns to the Mukurumudzi river.

We visited the dry and wet plants and waterhouses. Sands are heaped through a funnel and driven to the wet plant where heavy minerals rutile, ilmenite and zircon are separated from the rest of the sand. The leftover sand and slime is taken to the tailings storage facility (TSF). The minerals are taken to the dry plant where separation to final product is done in efficient and economical way.

When water gets low in the Muku reservoir, there are four boreholes owned by BTL, using electricity, these pump water from the aquifers. [These production boreholes are used throughout the year except when the reservoir behind the Muku dam is so full that water is flowing out the spillway. These boreholes also have collection points for domestic water supply for the surrounding communities.] Two of the boreholes are found in Gongoni Forest [and two are within the Fihoni / Madzi Kuko area].

We visited a nursery where they have 20047 trees for rehabilitation in the areas impacted by mining activities. They have 214 species. All of these species are indigenous ranging from most endangered species to those that are not endangered. [In addition to being used for rehabilitation of mined areas, these trees are also given to communities and schools for planting and have been used to to create forest corridors connecting existing forested areas together].

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Water club members at the Base Titanium nursery.

The club heard motivational speeches from different people after the site touring including:

  • Esther Shake (Environmental Technician): She insisted on being prayerful and said that we have potential because there is no end to what you want to do, for our dreams are valid no matter your background place.
  • Mwanaidi Ali (Community Awareness Officer): She talked about success which is determined by vision, hard work and discipline. She said to respect ourselves as girl child and we have potential to do our best if we put the speech into progress.
  • Rehema Ahmed (Administrative Officer, Environment Department): She added “let hard work be your voice” and also talked about respect.

The first field trip was a success and club members are eager to have more of them in different ecological set-ups.

 

 

 

Water Filtration and Testing for E.coli

At the end of March, enthusiastic water club members took a few hours out of their Saturday for a field study about microbial water quality and water filtration. As pictured below, they sampled water from a variety of different sites – the taps at their school, a hand pump, a covered well and an open trough.

The girls were also given a demonstration of a portable water filter that was designed and built by their teacher, Geoffrey Wekesa. They sampled water both before and after it passed through the filter.

The girls were taught how to use compartmental bag tests to estimate the concentration of E.coli bacteria in the samples. The tests were left to incubate at room temperature for two days and then the club returned to assess the results. They were eager to understand and talk about the results, even though the bags smell rather bad after incubating!

For more info on the compartmental bag tests, how they work and where to order them from, check out this website.