Appendix E

Well Shock Chlorination Exercise

A Lifewater well was just drilled to a depth of 30 meters feet. The pumping rod and riser pipe have been installed and, prior to sealing the well, it should be disinfected. The water level in the well is 8 meters feet below surface. What are the steps that should be taken to disinfect this well? How much sodium hypochlorite should be added? How much calcium hypochlorite?

1. Determine the volume of water in the well
• Area of a circle = Pi r².
  Pi = 3.14
  r = radius = 5.08 cm (casing diameter = 4 inches) = .05 m
  Area = 3.14 x 0.05m x 0.05m = 0.00785 m²
• Height of water column = Well depth - depth to water
  well depth = 30 m
  depth to water = 8 m
  height of water column = 22 m
• Volume = Area x Height
  Area = 0.00785 m²
  Height = 22 m
  Volume = 0.00785 m² x 22 m = 0.173 m³
  = 0.173 m³ x 1000 L/m³ = 173 L
2. Determine the amount of sodium hypochlorite to add to the well
3. Assume sodium hypochlorite is not available and calculate the amount of calcium hypochlorite which should be added to the well.