Proposed approach for creating longitudinal sections of a water distribution network or any other
pressurized system with the DC-Sewer-Design Extension.
After the network has been designed in the horizontal dimensions (x, y) it has to be designed as well
in the vertical dimension (z) which means the grades of the pipes have to be defined. After the
required data has been added to the pipes in ArcView the longitudinal sections can be printed with the
"create profile" function of the DC-Sewer-Design-Extension.
1.
Basic Steps

In order to obtain the ground elevations of the project area either an accurate field survey has
to be carried out or a DEM (Digital Elevation Model) has to be calculated on the basis of
precise contour lines digitized from existing base maps (e.g. scale 1:50,000, larger scale
would be even better (1:10,000 or 1:5,000)).

After a network has been designed in x-y-coordinates utilizing digital basemaps or satellite
images the z-coordinates have to be defined. That means the invert level of the pipes have to
be calculated considering the minimum pipe cover and the minimum grade of pipes.

As a first approach to obtain the most convenient grades for all pipe work a certain minimum
cover has to be assumed (e.g. 1.0 m). Thus a first estimation of the invert level would be:
Invert level = ground elevation - 1.0 m.

Afterwards the whole network has to be split in short pipe sections (e.g. 20 m) and the profile
of each pipe has to be printed out in an appropriate scale (e.g. 1:1000 horizontal, 1:100
vertical).

Now the design invert levels can be determined whereby the minimum slope of 0.5 %, the
minimum cover of pipes, high- and low points are representing the restrictions within the invert
levels are to be chosen. For significant points like high and low points, change of gradient,
section valves, air valves or washouts the invert levels will be determined manually on the
print outs. Thus the gradient of the pipes will be determined as well.
2.
Designing Invert Levels:
2.1
Data Fields
In the tables of the pipe.shp and the junction/node.shp the following fields are to be provided:


Pipe.shp
o
Groelev_up
(ground elevation upstream, 3 digits)
o
Groelev_dw
(ground elevation downstream, 3 digits)
o
Invert_up
(invert level upstream, 3 digits)
o
Invert_dw
(invert level downstream, 3 digits)
o
Length
(Length in m, 3 digits)
o
Gradient
(slope/gradient of pipe, 5 digits)
o
Check
(optional, set to "not checked", type in "ok" after
finishing the calculations for a certain sequence of
pipes in order to control progress of design)
Junction/Node.shp
o
Groundelev
(ground elevation of node)
o
Invert
(invert level of pipe at node)
2.2
ArcView Procedures

With the "manhole data to line" function of the DC-Sewer-Design-Extension, transfer
the ground elevation from the node.shp to the pipe.shp (Groelev_up, Groelev_dw).

Enter the invert upstream values – determined under "Basic Steps" (should be written
in your print outs) – into the Invert_up field of the pipe table.

Now use the “Calculate constant gradient” function (button in your view tool bar which
shows a single line with a constant slope) as described in the sewer design extension
manual under chapter 4.3.2. With this function the invert levels (upstream and down
stream) for a selected sequence of pipes will be calculated and written into the chosen
fields as well as the (constant) gradient. NOTE: Select the pipes from the view and
choose “Theme – Start Editing” from your menu. Then the “Calculate constant
gradient” function will become active and you can run it.

Check the calculated invert levels and gradients carefully by comparing them to the
levels and gradients written on your printouts.

With the "Line data to manhole" function of the DC-Sewer-Design Extension transfer
the "Invert_up" and "Invert_dw" values of the pipe theme to the "Invert" field of the
node theme.

At locations where 2 or more pipes are sharing the same downstream node, make
sure that the downstream node is having the same invert level for each pipe.

Optional: Change the "check" field for the finalized pipes from "not checked" to "ok"

Start
drawing
profiles
with
the
"create
profile"
function.
TIP: It is helpful in order to organise your profile-views if you add a field to your nodetable called “node_no” (e.g.) in which the name of the manhole or node will be written.
In your profile configuration file (config.txt) then set the Manhole.ID=node_no (first
line). First you will have this node_no written in the text box of your profile plus the
view which contains/shows the profile will be named with the start and end node of the
related sequence of pipes instead of the dc_id.

NOTE: For any selected sequence of pipes the flow direction must be unique!

Open and prepare a layout with required frame and plan head and load the views with
the
profiles
you
have
created
into
the
layout.
NOTE: Watch the length of the pipe sequence you have chosen. E.g. for a 1:1000
scaled map in A1 the max length of a sequences is between 550 and 600 m.