Sewer Structure Library

In a sewer network, there are a few types of structures used at the junctions. The Sewer Structure Library command allows you to create, edit and store sewer structures. The details of the design and construction of sewer structures can be found in the HEC-22 manual.

The working structure data file is stored (by default) in the Carlson Software Install\User directory and is available across all Carlson Software projects. Existing structures can be edited, sorted or removed from the Structure Library and the Library itself can be saved or re-loaded as desired. The Copy function makes a new structure with the dimensions copied from an existing structure.

The Custom Properties function defines additional fields for each structure. Values for these fields can be entered into the Structure Library. Then these fields are available in the Report Sewer Network command.

Clicking New gives you the ability to create one of the five types of sewer structures allowed in the Carlson Hydrology module:

Outfalls are outlet structures at the sewer outlet location. A regular outfall may consist of a headwall and two wingwalls while a funnel outfall consists of a funnel shape structure.
Box Structures are usually used to support inlet openings and connect them to the underground piping system.
Circular Structures are manholes that provide access to the sewer network for inspection and maintenance. Manholes are usually installed where pipes change direction (horizontally, vertically or slope), where two or more pipes join or where the pipe sizes change.
Headwall Inlets are an open-end section similar to a culvert entrance and is used to capture flows at low points.
Pipe Connections used for lateral connection to main network.

For each structure type, a Draw option allows you to place a "profile aspect" detailed image of the structure (complete with annotation) into your drawing.

Outfall Structure

In the Structure ID box, type the structure name. For the regular outfalls, enter the dimensions of the headwall and wingwalls. For the funnel type outfalls, enable the Use Funnel Symbol toggle and enter the length and widths of the funnel.

Box Structure

In the Box Structure dialog, type the name of the structure in the Structure ID box, enter the length and width of the structure.

In addition to specifying the physical dimensions of the box structure, you also have the ability to indicate one or more "offset locations" that may better position the box structure around the pipes in situations where the roadway direction is skewed relative to the orientation of the pipes:

Consider the following example showing a Box Structure with custom offset:

"X" offsets can vary between -1 (Left) through 1 (Right) as a decimal factor relative to the structure length.
"Y" offsets can vary between -1 (Back) through 1 (Front) as a decimal factor relative to the structure width.

Circular Structure

In the Structure ID box, type the structure name. Select a Taper Format and enter the Bottom Diameter, Top Diameter, Taper Offset and Taper Height of the structure. A graphic box on the right side of the dialog displays the graphic of the currently defined manhole.

Headwall Inlet

The headwall inlet is very similar to the outfall structure of headwall type. In the Structure ID box, type the structure name. Enter the dimensions of the headwall and wingwalls. Inlet loss coefficient is used in hydrograph routing calculation.

Pipe Connection

Type the Structure ID and add Custom Properties if required.

Pulldown Menu Location(s): Network > Sewer Network Libraries > Sewer Structure Library
Keyboard Command: strlib
Prerequisite: None