Water Distribution
The Water Distribution Department is comprised of a four man crew. They are responsible for maintaining the integrity and dependability of the distribution system. This means they are inspecting all new installation of lines and services as well as maintaining the existing and includes fixing broken lines, valves, hydrants and services. The Distribution crew works with road and bridge projects to make sure the contractors do not impact our customers when replacing watermain.
The crew has to be very cognizant of a variety of safety issues, such as call before you dig so we do not damage other services while trying to work on our service. We also need to be aware of traffic safety, trench safety, personal protection equipment, eye and face protection and confined space. Another safety issue we are concerned with is the hydraulics of water pressure. Our system pressures rage from 80 psi (pounds per square inch) to 48 psi. This translates into a 12” line cap could have a pressure rage from 5,426 pounds of pressure clear up to 9,043 pounds of pressure, which is a lot of force and with a water hammer that force could double. If someone working on the line was in the path of the cap when it was blown off they could be seriously injured or killed. When it comes to safety issues it is not only our people we need to be concerned with but also with construction crews, plumbers and the public.
The Water Distribution system for Lebanon has sections over seventy-five years old and our Water Distribution Crew is continually rebuilding the system to ensure we provide the city with safe and reliable service. Many of the old lines were not installed with the capability of supplying the capacity that our fire trucks are can process today. The city and utilities have programs in place to up-date these lines to meet those demands. Hydraulic Modeling of the system allows us to determine the benefits before we make the changes. The hydrants are flushed twice a year. This helps us to check our hydrants and ensure reliable fire fighting service for the city. We also have color coated the tops of hydrants so our fireman will know what size of line they are on.
Most of our lines are between 4 and 5 feet deep so they are below the frost line to minimize the freezing impacts of the earth moving. We also make sure the lines are bedded in sand so as the ground moves the sand allows it to move without snapping the line. Most of the old lines are made of Cast Iron with a few Transite lines. Today most of the lines we install are Ductile with a few smaller plastic lines. Service lines for homes are normally either plastic or copper. We try to install services to the corner of a property with a one inch line. In this way, we can install a splitter at a meter pit and provide service to two homes instead of one. This puts fewer holes in the lines and reduces cost.
Typical Utility Infrastructure Layout
The picture above shows a basic layout of infrastructure in a typical subdivision. The dimensions will change when describing larger conveyance roads but the primary layout should stay the same. Water Meter Pits and Fire Hydrants are normally placed on the property line and then divided to two services. Sanitary laterals are normally placed in the center of the property.