3.1.2. Layers explanation

3.1.2.1. Main layers

TWW is constructed around two main layers :

• Wastewater structures tww_app.vw_tww_wastewater_structure

• Reaches tww_app.vw_tww_reach

3.1.2.1.1. Wastewater structures tww_app.vw_tww_wastewater_structure

Main layer for manholes, special structures, infiltration installations, discharge points (and wastewater treatment plant (wwtp) structure). Creating a new record in this layer always creates a new wastewater structure, a new cover and a new wastewater node. In the edit form, you have access to a lot of the related tables (e.g. structure parts, maintenance events).

Even if there are several covers or wastewater nodes, there is just one point for every wastewater structure in this layer. By default, the position of the wastewater node created first is used as the point coordinate.

Attention

Do not export this point coordinates as covers. Use the layer vw_cover for this.

3.1.2.1.2. Reaches tww_app.vw_tww_reach

Main layer for line-wastewater structures (channels). Creating a new record in this layer always creates a new reach and a new channel. In the edit form, you have access to a lot of the related tables (e.g. structure parts, maintenance events).

3.1.2.2. Wastewater Structures

3.1.2.2.1. Wastewater Structures Details tww_app.wastewater_structure

This layer shows and enables you to edit the detailed geometries of wastewater structures. You can add a new detailed geometry using the layer vw_tww_wastewater_structure action called digitize detailed geometry.

See digitizing detailed geometries for more information.

3.1.2.2.2. Structure Parts tww_app.structure_part

Cover is the only structure part with a point-geometry itself. All other structure parts are just linked to their wastewater structures and should by only edited by the main layers (vw_tww_wastewater_structure and vw_tww_reach).

3.1.2.2.3. Covers tww_app.vw_cover

Use this layer to change the situation of some specific cover (and not the whole wastewater structure) or to add a new cover to an existing wastewater structure. You can add an additional covers in the covers-tab of the vw_tww_wastewater_structure too. Additionally, use this layer to show the detailed position of the covers (e.g. in network_plan or pipeline_registry) or to export the cover positions situation_geometry.

3.1.2.2.4. Channels tww_app.vw_channel

The channel-class has no geometry and is therefore mostly changed in the vw_tww_reach layer.

3.1.2.2.5. Organisations tww_od.organisation

organisation contains the organisation that you can select in attributes like fk_dataowner, fk_operator, fk_provider, fk_owner, etc.

This table is today a little bit hidden in the wastewater_structures group (but it is not only related to wastewater structures).

3.1.2.3. Maintenance events tww_app.vw_tww_maintenance

Maintenance events can be created through the view tww_od.vw_tww_maintenance.

These maintenance events are used in the maintenance tabs in the main tables. They can be linked to one or several wastewater structures.

See editing maintenance events for more information.

3.1.2.4. Value Lists tww_vl.*

These value lists are defined in the VSA-datamodel. Do not change.

3.1.2.5. Hydraulic

3.1.2.5.1. Wastewater nodes tww_app.vw_wastewater_node

Use this layer to change the situation of one selected wastewater node (and not the whole wastewater structure) or if you want to add a new wastewater node to an existing wastewater structure. You can add additional wastewater nodes in the wastewater nodes-tab of the vw_tww_wastewater_structure too.

3.1.2.5.2. Overflow tables tww_app.vw_tww_overflow

These tables are connected to wastewater nodes. In the project-file template (Version 8.0, 4.6.2020) are no relations defined for these tables.

3.1.2.6. Topology

3.1.2.6.1. Nodes tww_app.vw_network_node and segments tww_app.vw_network_segment

These two layers are used by the tww-extension for the profile and the network-following functionalities. Use the tww_app.vw_network_segment layer to show the flow direction, if you use a markerline (filled_arrowhead) as symbol.

See connect wastewater network elements for more information on how to create and maintain a good Topology.

3.1.2.7. Catchment tww_od.catchment_area

Main layer to digitize and edit the catchment_areas.