Ashgabat, the capital of Turkmenistan, is a city of 300,000 people located on the southern edge of the Kara Kum desert near Turkmenistan's border with Iran. Two water treatment plants serve the city of Ashgabat. The northern half of the city is served by a plant supplied by water from the Kara Kum Canal. The facility is approximately 20-30 years old. The aeration tanks are made of wooden slats.
Chlorine gas is used for chlorination.
In a visit to Ashgabat in 1996, I observed a huge chlorine gas cylinder lying on the ground outside the plant, anchored only by its pipe connection to the building. Small earthquakes are common in Ashgabat, so this is not a safe practice. Gas masks hung on hooks just inside the door from the chlorine tank, leading me to infer that a tank had come loose and spewed chlorine gas before. The lab technician does iodometric titrations by hand to determine residual chlorine in the water. All records were kept by hand in log books, and the lab technician checks results against Soviet standards from 30 years ago.