GIS Capturing of Water and
Sewer Infrastructure

SiQ was appointed by the Water and Sanitation Department of the City of Cape Town to capture reticulation network entities, water as well as sewer, from information indicated on as-built drawings. The project was launched in July 2010 and ran over a two year period.

SiQ are always focused on maximizing efficiency and accuracy and are committed to provide deliverables to their clients that are of the highest standard. To achieve these objectives, SiQ developed a well-documented process for the efficient capture of accurate data, as well quality assurance and tracking of progress being made.

Paper drawings received from City of Cape Town were first scanned and geo-referenced, after which water and sewer entities were digitised via a process of heads-up digitising.

The digitising process was guided by a digitising rules document that each digitiser needed to follow. The digitising rules document included a detailed description of which entities needed to be captured, including attributes needed for each entity type. Prescribed procedures that needed to be followed for the capturing of these entities were also included.

The quality control procedures that needed to be followed were set out in a detailed quality control procedures document. This document ensured that quality control was standardised and that all necessary checks were performed, which worked towards the goal of providing accurate data of high quality.

A tracking database was used to manage the digitising process, as well as to provide progress reports and summaries of features digitised for invoicing purposes. All drawings were logged in the database as soon as it was received and the date of each process (e.g. received, scanned, geo-referenced, digitised, checked, and delivered) was recorded. When a drawing was completed, it was marked in the database as such and the total number of features on the drawing was entered in the appropriate fields.

SiQ’s structured approach to the project, as well as processes that have been put in place regarding training, data capturing, quality assurance and tracking of progress, ensured that high quality data was delivered to the client in a timely fashion. An amount of 560 500 features was delivered to the client in the 2 year period of the project.