10 January 2002
table 4-2 because of the extra bends and associated movement in the loops. In low profile systems, vertical
expansion loops may be used as road crossings. Details will be provided indicating support types and
locations throughout the loops and bends.
f. Vents and Drains. Provide venting of all piping high points and draining of all low points to allow
total drainage of the system. Vent and drain locations will be indicated on the profile drawings. Vents and
drains are similar to those used for the concrete shallow trench system, figure 4-15.
g. Transition to Buried Systems. When a buried system transitions to an aboveground system a valve
manhole will be provided at that point. A manhole top penetration will be provided to allow expansion of the
distribution piping in the man-hole top yet keep rain and ground water out of the manhole. Figure 7-8 shows
such a transition in a valve manhole with a concrete cover. The valve manhole used for this transition must be
large enough to be accessible and will be designed in accordance with chapter 3 of this manual.