In the absence of vehicles and means of transport in the past, qanat practitioners and workers had to stay away from their houses, near the qanats under construction. So, they had to build temporary houses, named "bookan". The bookan was constructed near the qanat. Its roof was at the same level as the ground surface, and workers entered it by stairs. The thickness of the roof was about 2 meters. Nowadays, bookans like payabs have lost their function, and today there is no active bookan left. But in the past, the bookan was essential, especially for the long qanats; and without it, the work could not be continued. The length of a plain qanat may reach 30 Km and more, so there might be a long distance between workers' house and their work place. It was impossible for the workers to travel this distance and back, every day, so, construction of the ookan was essential for qanat workers. Moreover, the bookan was used as a small forge for sharpening picks. The workers, who rested in the bookan, prepared food for other workers who were digging the qanat and also to sharpen the picks for them. The forge in the bookan was connected to the outside through a chimney.
Figure 1:Plan of bookan
The workers lit the forge and sharpened the picks on it by pounding on them with a sledge hammer. This process was named "kolang keshi". The method of building a bookan was as follows: first the workers dug a slanted gallery in the ground, and at the end of that gallery they built an underground room in a conical shape. They were cautious about probable cave in and so were very careful in constructing a bookan.
In order to prevent collapse, they used to leave a column of earth intact in the middle of the room. They placed the dirt taken out around the entrance hole to prevent rain from coming in. Another hole was dug to let the smoke of cooking out. Sometimes this hole played the role of a chimney and sometimes an air vent, because air for breathing was also provided by this hole. The size of the bookan depended on the number of the people who were to stay there, the more the people, the bigger the bookan.
Collapse is likely, due to the instability of the earth after leaving the bookan, unless it has been dug in a hard ground.
Depending on the number of muqanis, several niches were dug into the walls, 0.5 meters above the floor, forming small chambers or sleeping platforms. After digging the main parts of the bookan, they also gouge out some smaller niches in the wall of living room, so that the muqanis could put their personal stuff in them; there was also a special place for putting the oil lamps and torches, and another for putting the instruments used for digging. A place separated from the living room was used designed for cooking.
Almost every 3 kilometers along the gallery, a new bookan was built; but if the gallery was dug in a hard area, the muqanis could stay in one bookan for a long time.