Using InfoNet to manage a planned sewer maintenance program


Courtesy of Innovyze

OnSite is a framework contractor for Severn Trent Water, one of the ten water service companies of England and Wales. The company is one of the project coordinators for the utility’s planned sewer maintenance programme and one of three framework contractors working in very close collaboration on its CCTV survey and sewer cleansing program. In addition the company undertakes man-entry surveys, hydraulic flow surveys and operational sewer support services, blockage removal, planned sewer cleansing and wet well cleansing, for Severn Trent’s western region.

Severn Trent, an enthusiastic early adopter of InfoNet, utilises Infonet to manage its programmed works. OnSite’s Patrick Hopcroft explains that there are a number of types of CCTV survey undertaken by Onsite for the company: critical sewer surveys; non-critical sewer surveys; building over surveys; sewers under railways; pre- and post-cleanse surveys; CSO health check surveys; flooding team surveys and reactive surveys. These capture large amounts of data that is fed back to the utility.

Implementing InfoNet has allowed for the seamless two-way transfer of Severn Trent’s survey requirements and the resulting CCTV data .The items or areas to be surveyed are sent to Onsite as an InfoNet Snapshot file. Survey plans and schedules are thus produced directly from the UADMS sewer records that Severn Trent holds in InfoNet. Upon completion of the site survey, a Snapshot file of the validated CCTV data and any alterations to the sewer records are returned to Severn Trent and ultimately used to update UADMS. The next step was to see if InfoNet could bring similar efficiency gains to other areas of work, in particular the planned sewer maintenance programme.

Planned sewer maintenance
Prior to this project, planned cleansing work was issued in the form of a spreadsheet on an annual basis. Manhole references defined the upstream and downstream nodes of a run of pipes, defining a ‘site’ to be cleaned or surveyed rather than an asset. Severn Trent provided paper plans, and the results of the exercise would be fed back in the form of an update to the same spreadsheet.

“The spreadsheet became a constantly-growing entity, with extra cleansing and pre-cleansing in additional rows in the spreadsheet, and pre-cleansing CCTV work generating a separate spreadsheet,” Mr Hopcroft commented.

He added: “The system was not without its merits - it was straightforward and transferable. There was a lot of excellent local knowledge about sites and problems, and an emphasis on sites rather than assets - it had to be manageable and using assets would have made it unwieldy. Information collated against a run of pipes was more manageable when using this format.”

However, there were also disadvantages - all of the manhole references were incomplete, using only the four-figure reference, rather than the full ten figures based on the National Grid Reference system. The emphasis on sites also had a downside - with the development of the UADMS system, there was a need to relate surveys and other data to individual assets, the idea being that a history is attached to an asset and readily available. The original spreadsheet could not take geographical or spatial data of any kind, and it became unwieldy as it progressed over time. Analysis of any spatial or temporal trends to ensure efficient targeting of resources was simply not possible.

The data exercise
As it was already using InfoNet to manage its data, in October 2006, Severn Trent took the decision to move to one cohesive dataset that could be used as a planning tool. It therefore issued a version of the spreadsheet detailing 1366 sites on its planned cleansing program.

The first task commissioned was to return an asset-based dataset compatible with UADMS and InfoNet to the utility prior to the commencement of the 2007-08 maintenance program. It was important to retain the advantages of the old system, such as the comments relating to each pipe run. The second task was to investigate how the resulting data could best be handled in InfoNet.

The first step
The spreadsheet was used to generate a non-mappable table in MapInfo that could be used to cross-reference the data with Severn Trent’s sewer records. There were a number of potential pitfalls, one fairly serious one being the potential presence of non-existent node references, for example where asset references had been changed, the assets moved or the network redesigned. There were to be many instances where the upstream or downstream node reference could not be found in the Severn Trent database.

An investigation was performed to check if a run of pipe crossed from one National Grid kilometre square to another one, because if this occurred the manhole reference became incorrect. Trying to undertake downstream traces where there were bifurcations was also difficult, and incorrect flow directions -simple transpositions - made the data task far more arduous than it could have been.

The second step
Step two was a two-stage process. Where the data was of sufficient quality, an SQL query was run to discover whether the upstream and downstream manhole data were correct, and to select individual pipe lengths per site. Around 880 sites were successfully geo-coded in this way, with the remainder having to be investigated individually and the pipes added to the selection.

The result has matched exactly to Severn Trent’s requirements - the engineer comments have been retained, but divided into pipe lengths and their constituent assets. The dataset is also now compatible with Severn Trent’s sewer records from UADMS. The next stage involved asking how to best use InfoNet to manage the data.

In cooperation with Severn Trent, OnSite manages its maintenance work using Infonet. Each length of pipe to be surveyed or cleansed is used to generate a Pipe Repair item within InfoNet. Each of these items has a unique ID, though each Site Reference or job number relates to more than one asset, for example, a group of assets or one run of pipe. OnSite staff worked with colleagues at Severn Trent and agreed a format for importing and exporting - each repair ID is uniquely defined as US.DS.LinkSuffix.MonthYearJob_Code.

This enabled Severn Trent to unite the asset-based data supplied by OnSite with any original site information based on the common site code. The Open Data Import Centre in InfoNet allows Severn Trent to import this easily into the asset database.

To build an asset history, each job generates a separate repair that records if an associated CCTV survey is required and/or cleansing work. The two operations or repairs required here have different cost codes, so it has been deemed preferable to keep them separate, so only the request is taken into the grid.

An InfoNet Snapshot file is issued by Severn Trent on a monthly basis detailing Pipe Repair Items for both CCTV surveys and cleansing, two months in advance. The schedule of work and site plans are determined and produced by OnSite utilising InfoNet. CCTV survey data is imported into InfoNet as a standard .dat file and returned to Severn Trent as a Snapshot file. It is also validated against Severn Trent’s validation rules prior to return to the utility.

CCTV and cleansing work are staged to allow survey data to be reviewed prior to issuing subsequent cleansing work - for instance, there may be a six-monthly cleansing program with an interim three-month CCTV program. This allows discussion at subsequent planning meetings to decide if the pipe needs to be retained in the cleansing program or removed. The CCTV survey data can also be reviewed to ensure that future cleansing work can be efficiently targeted. All feedback from site cleansing work teams is used to update Pipe Repair objects within InfoNet.

“The new system is much more efficient, as we had hoped based on our existing use of InfoNet. Planned maintenance work can now be cross-referenced with all otherprojects we undertake for Severn Trent in order to avoid duplication. CCTV data from this project and any other can very easily be filtered according to pre-defined criteria (such as debris>20%, root mass, etc), and the associated assets flagged for inclusion or omission from the subsequent maintenance programme.” explained Mr Hopcroft.

At the moment, as the work is in its early stages, although defect codes have a unique ID, the company is not yet using defect type and cause of failure in the rehabilitation planning. However, the system allows the utility and contractor to be confident that project costs will be accurate. Other advantages of the new system include the fact that all work is referenced to the UADMS sewer records, and all work and collected data is tied to the asset so there is no confusion with incorrect manhole IDs. Spatial analysis is possible, and data can be examined with respect to any form of GIS data the company has available. Resources can be targeted far more efficiently - the integration of the cleansing data and CCTV work allows Severn Trent to determine exactly what remedial work is required.

Future developments
There is other work that Severn Trent and OnSite plan to bring into InfoNet -CSO health check surveys, which Severn Trent has in a very specific form, and reactive CCTV survey and maintenance work. This would include utilising InfoNet for emergency call outs and analysing how the planned work mirrors the reactive work, thus determining if it could be better targeted. Examining how this work is issued, and tying this information to the assets themselves utilising InfoNet’s built-in tool is the next major project.

 Flood team survey work data is currently not compatible, so another objective for the near future is to ensure that all survey data is imported into and is available from within InfoNet.

Mr Hopcroft added: “The system allows very easy transfer of data. With different clients and different projects however, there is the issue of data being available in a slightly different way. This project has demonstrated that it is flexible enough to be used as a powerful tool even when tailored to be used in a way that was not originally intended.”

This article is based on a presentation made to the 2007 Wallingford Software International User Conference by Patrick Hopcroft of OnSite.

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