GPS Capturing of Water &
Sewer Infrastructure

SiQ was appointed by the Frances Baard District Municipality to capture the GPS positions of water and sewer infrastructure such as valves, manholes, sewer ponds, reservoirs etc. in the municipal areas of Phokwane, Magareng and Dikgatlong. These areas contain towns such as Hartswater, Jan Kempdorp, Pampierstad, Warrenton, Windsorton, Barkley West and Delportshoop.

The project had an extremely short time scale and commenced 9 March 2012 with the compilation of an inception report as the first step. The final inception report was delivered on 2 April 2012. The fieldwork was done during 12 April to 22 June 2012, a period of just more than two months.

Normally a project of this nature will commence with the digitizing of the as-built drawings (as described in a separate data sheet: "Cape Lines project"), but due to the unavailability of these drawings and the short timescales allowed for this project, the methodology had to be adapted. SiQ developed and documented a 10 step process which ensured that not only the complete area was covered, but that quality assurance was built in through every step and that the maximum number of features were captured.

Below is a picture of the GPS tracks of the fieldworkers, that were captured as part of the process and that were used to determine which areas the fieldworkers have missed.

Fieldworkers were issued with maps of the area they had to survey, and these maps were updated as the data was received from the field. A total of three rounds of maps were compiled for any specific area during the complete process.

GPS points had to be captured with sub-meter accuracy, and as such Trimble ProXR, ProXRS and PF Power Receivers were used, coupled to Trimble Nomad handheld controllers.

Post processing was applied to these points to ensure the most accurate capturing possible.

In the office the combined knowledge and experience of the field staff and the office staff was used to digitize the pipelines, as well as to determine direction of flow, fix topology issues etc.

Knowledgeable technical personnel from each municipality were also involved in many steps of the process, as many of the features are not visible to the eye (e.g. water pipes that are buried underground). In the final fieldwork step the completed data, in the form of a map was discussed in detail with each of the technical personnel, and they had to agree to the contents thereof.

The final deliverable was a set of GIS vector files containing all the features that were captured, as well as the attributes linked to them captured in the field, in the office and after discussions with the technical personnel.