A city utilities worker observes professionals from Advanced Valve Technologies use a special machine purchased by the city to install a valve in a six-inch water line in the 900 block of Griffith Avenue this week. In this photo, the blue machine appears to jut upward 18 inches or so from the water pipe. The technology allows valves to be inserted without shutting off the flow of water through the line and interrupting service to neighborhoods. Gate valves such as this allow the city more flexibility in keeping a stable flow of water in all parts of the city. About half a dozen city workers observed the live valve insertion as part of training in the machine’s use. Dick Boyd, a city supervisor at the site, said the average cost of using a professional service to install a valve with a live flow of water is $35,000. The city will have paid for the new machine after just a few uses, he said. HANK MURPHY PHOTO