Question 4 (a) If, after a rain storm, you found pools of water with a yellow-br

Question

Question 4 (a) If, after a rain storm, you found pools of water with a yellow-brown discoloration caused by clay, what would you suspect about the soil in the vicinity of these pools? Would this soil bea good material to form the impermeable zone of an earth dam? Explain your answers to both questions above. (3 mark) b) What causes "Acid Sulphate Soils"? What potential impacts could they have to the natural and built environments? Soils? What measures can we take to minimize the impacts of Acid Sulphate (c) Explain why a sand castle is most stable when the sand is kept moist but would collapse when the sand is dried under the sun or when the sand is saturated by rain. (3 mark)

Explanation / Answer

b) Acid sulfate soils are safe and harmless when not disturbed. If acid sulfate soils are dug up or drained they come into contact with oxygen. The pyrite in the soil reacts with the oxygen and breaks down.

This process turns pyrite into sulfuric acid, which can cause damage to the environment and to buildings, roads and other structures.The acid also attacks soil minerals, releasing metals like aluminium and iron. Rainfall can then wash the acid and metals from the disturbed soil into the surrounding environment.

Acid Sulphate soils are common in places where humans live, and sometimes construction in and around these sediments cannot be avoided. In such cases, the first step is to minimise the level of disturbance as much as possible and the following are

C) when water is put into the sand The friction between the particles is modified by the water.Applying the water to the sand will fill the pores with water.  The weight of the particles pressing down squeezes the water out, and this water pressure from the inside reduces the friction binding the sand together.. when the castle is exposed to sun the water in the pores will get evaporated The friction between dry particles can’t hold up a vertical wall of sand and thus collapse

A) brown-colored (water with a brown, yellow or muddy appearance) water after a heavy rain can signal you may have a contamination problem. Typically, this is caused when surface rainwater infiltrates your well through the wellhead. Basically, instead of pumping clean groundwater, you are pumping water that has runoff from the ground into your well. A worst-case scenario is the brown color may be caused by a nearby septic system that has been compromised and leaking into your well.

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