GIS STORMWATER DRAINAGE DATA COLLECTION FOR CITY OF WHITEHORSE

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1 GIS STORMWATER DRAINAGE DATA COLLECTION FOR CITY OF WHITEHORSE Abstract Mirjam Fabijanic, Engineering Asset Co-ordinator, Whitehorse City Council The City of Whitehorse is located 15 kilometres east of Melbourne and covers an area of 64 square kilometres and has a resident population of approximately 151,000 people. This paper is about the project for collection of GIS Stormwater Drainage Data (approximately stormwater pits and pipes) from Council s existing information sources (drainage plans) with associated attributes and inclusion of the data in Council s GIS stormwater drainage dataset. Whitehorse City Council is currently implementing Hansen8 as its Corporate Asset Management System and a complete stormwater drainage asset dataset needs to be migrated into Hansen8 as a part of the process. The external consultant was engaged through the Tendering process to complete the GIS stormwater drainage dataset. Data migration to Hansen8 is to be undertaken by Council upon the completion of the stormwater data collection. The scope of the project was to organise, scan, catalogue and spatially capture the geographic extent of the unscanned plans (approximately 2,000 plans) provided by Council into GIS plan catalogue, to collect stormwater drainage pits and pipes information with associated attributes information from Council information sources into a defined data structure and to undertake Quality Assurance (QA). Key Words: GIS Stormwater Drainage Data Collection Whitehorse City Council Introduction The City of Whitehorse is located 15 kilometres east of Melbourne and covers an area of 64 square kilometres and has a resident population of approximately 151,000 people. The municipality is bounded by the City of Manningham to the north, the Cities of Maroondah and Knox to the east, the City of Monash to the south and the City of Boroondara to the west. Whitehorse s suburbs include Blackburn, Blackburn North, Blackburn South, Box Hill, Box Hill North, Box Hill South, Burwood, Burwood East, Forest Hill, Mitcham, Mont Albert, Mont Albert North, Balwyn North, Nunawading, Surrey Hills, Vermont and Vermont South. Figure 1 show Whitehorse City Council location. Figure 1 Whitehorse City Council Whitehorse City Council is currently implementing Hansen8 as its Corporate Asset Management System and a complete stormwater drainage asset dataset needs to be migrated into Hansen8 as a part of the process. Council seeks to build a comprehensive stormwater drainage dataset and asset register to:

2 Support decision-making for the drainage rehabilitation program Achieve management goals of Council s Drainage Asset Management Plan, and Integrate with Hansen8, Council s Asset Management System Council is responsible for the Stormwater Drainage System with the exception of the larger pipes and creeks, which are the responsibility of Melbourne Water. Council utilises the ESRI suite of GIS products for its GIS requirements, Council also delivers a range of spatial products and services both internally via the corporate GIS viewer as well as externally via Council s website. The current GIS stormwater drainage dataset is made up of stormwater pits and stormwater pipes which are incomplete and largely unpopulated with attribute data. The GIS stormwater drainage dataset was created in the late 1990 s by digitising paper based stormwater drainage index maps (not the actual stormwater drainage plans). The dataset only contained stormwater pipes without attribute information. In March 2010, Council awarded a contract to Geospatial Data Services to carry out field collection data of all stormwater pits within Council road reserves and subsequently integrate these pits into Council s existing GIS stormwater drainage dataset. Geospatial Data Services collected 22,247 pits and performed around 24,267 line amendments which resulted in an additional 9,660 pipe segments, with sub metre (<1m) accuracy. These stormwater drainage pits provided a good reference point for capturing information from the plans. Upon delivery of the work provided by Geospatial Data Services, Council undertook a comprehensive quality check and analysis of the GIS stormwater drainage dataset which included data QA, cleansing and topological verification to ensure it was fit for purpose prior to loading into the GIS. At that stage, the GIS stormwater drainage data primarily represented stormwater drainage assets located within Council road reserves, and it largely excluded those located in off-road easements, laneways, parks, off-street car parks and service access roads. Attribute information pertaining to the GIS stormwater drainage dataset was virtually nonexistent. The only attribute attached to the dataset was that of the pit type. Other attributes such as material, date of construction, pipe diameter, etc., were not known. In recognition of the requirement for a comprehensive GIS stormwater drainage dataset, a temporary appointment was made to undertake further data collection commencing in May Approximately 6,350 drainage pits and 6,194 drainage pipes were collected as part of this process. Due to the need to complete GIS stormwater drainage dataset to support Council operations and the Hansen8 Asset Management System, Council decided to accelerate the data collection by seeking assistance from external consultants. It was anticipated to observe the same collection procedures as are being used previously to complete the GIS stormwater drainage dataset by 31 December Creation of a stormwater drainage network was planned to be undertaken by Council upon completion of the data collection prior to its migration into the Hansen8. There were approximately 8,463 plans available electronically. However, there were approximately 2,000 hard copy plans that were to be scanned and therefore not electronically available. In situations where field verification is required due to erroneous records within the GIS stormwater drainage dataset which cannot be resolved in the office, consultant was to be required to undertake the field survey.

3 It was estimated that upon completion of the Collection of Stormwater Drainage Dataset from existing Council plans, the completeness of the GIS stormwater drainage dataset will be in the range of 85-90% for the actual pits and pipes and approximately 60% in terms of their attributes completeness. Any missing gaps in the data will be identified and this will enable specific areas to be targeted for future field inspections and/or data collection. The objectives of this project were: To provide Council with data collection services and internal Quality Assurance methodology to ensure the quality of the collected stormwater drainage dataset is as per specification. To organise, scan, catalogue and spatially capture the geographic extent of the unscanned plans (approximately 2,000 plans) provided by Council into GIS plan catalogue as per Technical Specification. To collect stormwater drainage pits and pipes information with associated attributes from Council information sources into a defined data structure. To conduct possible site verification of anomalies identified within the existing Council stormwater drainage dataset and any uncertainties found during the data collection process which are unable to be resolved in the office. In order to bring data up to the standard of enabling effective integration with Hansen8, Council has specified the data structure to ensure the GIS stormwater drainage dataset meets current needs and is suitable for further enhancement. This paper is primarily about the Stage 5 Data Collection of drainage assets, and future steps that are to be undertaken. Figure 2 shows different stages of the drainage data collection from digitising paper base stormwater plans in late 1990 s until present time. STAGE 1 Late 1990's Digitising paper based stormwater drainage index maps without atribute information. STAGE 2 March 2010 Field Collection Data of all stormwater pits within Council road reserves and integration in to Council's existing stormwater drainage dataset (22,247 pits and 24,267 line amendments). STAGE 3 Early 2011 In-house quality check and analysis of the GIS stormwater drainage dataset, 6340 "orphaned" pits identified STAGE 4 May 2011 In-house data collection for 6, 350 stormwater drainage pits and 6,194 drainage pipes with associated attributes from Council plans. STAGE 5 March 2012 Decision made to accelerate the data collection by seeking assistance from external consultants. Urban Water Solutions in conjunction with Morphum Environment Ltd were commisioned. STAGE 6 December 2013 The final database contained a validated network of a total of 41,500 pits and 40,500 pipes delivered. STAGE 7 Present In-house QA of drainage data and on-going data collection and database validation to be continued, and integration of data into Hansen8 to be completed. Figure 2 Flowchart - different stages of drainage data collection from late 1990 s until present Drainage Data Collection Project Stage 5 Preliminary works The Tender advertised for the collection of the data required included stormwater drainage located in the road reserves and drainage easements on private and freehold land only. Drainage assets that are owned by other relevant Authorities (e.g. VicRoads, Melbourne Water etc.), were not required to be collected at this stage. The successful Contractor was required to organise the required hardware(s) and software(s) (i.e. PC, GIS software and licenses, GPS unit etc.) and to undertake the provision of Services.

4 The access to the relevant information required to undertake the project was provided, including: Existing GIS stormwater drainage dataset Current transport, property, contour and easement spatial datasets, as well as Council s aerial photography. Access to the electronic version of design and construction plans (approximately 8000 plans) Access to paper copies of construction plans dating from 2002, not digitised (approximately 2,000 plans). Access to Pureplayer (Road Condition Visual Survey) Gross pollutant trap locations; Melbourne Water stormwater assets; Yarra Valley Water sewer assets; Contours at 0.5 m intervals in ArcGIS format; LIDAR Data; Creek layer in ArcGIS format. Standard drawings for pit types. The ultimate goal of the project was to have a topologically sound stormwater drainage dataset to be constructed in Council desired format, in order for the dataset to be migrated into Hansen8 Asset Management System. The final output was to be delivered in ESRI Personal Geodatabase format, with the stormwater drainage dataset consisting of storm water pits and pipes feature classes in the specified structure; plan catalogue feature class and a field verification table. The stormwater drainage dataset was to be structured as a topological model based on the principles of connectivity. Spatial accuracy was to be +/-1m, although it will vary across the dataset based on source and ability to correctly verify collected information. Urban Water Solutions (UWS) in conjunction with Morphum Environment Ltd (Morphum) were commissioned by Council to complete the validation of the Stormwater Drainage dataset. Taylors Infrastructure (Taylors) were engaged as a specialist sub-consultant to the project team to undertake the field investigation work. Guidelines were provided by Council for the collection of data for the GIS Stormwater Drainage Dataset to facilitate future development, integration into corporate systems and management of the dataset. UWS developed customised software within the ArcGIS environment including, data entry forms, tracing, long section and QA routines to minimise errors during the data collection and attribution phase. The catchment area was broken up into 61 into drainage catchment areas (DCA's), delineated based upon natural drainage catchments, for the purpose breaking up the project into logical and reasonably sized work packages. Where possible, data was extracted from existing drainage plans. Due to the age of the stormwater system across the catchment area, accurate data was available for just over half of the assets. Engineering judgements based on LIDAR data, longitudinal sections and similar assets in nearby locations were made to create and populate the connected stormwater network. To verify complex drainage configurations that were unable to be confirmed by Council information sources, 52 site visits were undertaken by field surveyors, Taylors. These site visits confirmed the connectivity of 700 key drainage assets. The Final database contains a validated network of a total of 41,500 pits and 40,500 pipes; 70,000 assets were validated by UWS and Morphum, with 12,000 previously validated by Council. Prior to the commencement of the asset data entry stage a number of key tasks were undertaken including establishing procedures and protocols, preliminary data processing and software design. By developing a suite of software tools, procedures and QA checks this ensured the efficient, accurate and consistent data entry throughout the project.

5 These tasks included: Software Development (to minimise the opportunity of human error, to establish table structures, customised data entry forms and QA routines, data cleanup and processing tools, developed multiple fields for pit cover levels to store data); Scanning and georeferencing of stormwater plans; Splitting the system into drainage catchment areas (DCA); Creation of an initial database from the existing stormwater GIS data; Preliminary data clean up; Creation of individual DCA geodatabases; Testing of software and methodology on a pilot DCA. The software was developed to run in the ArcMap platform and incorporated the following data entry features, data source capture features, and processing tools: The software was tested on a pilot area and modifications were made to the software and processes as required to deal with the range of issues encountered. The pilot database was used to ensure that Council requirements were satisfied and to ensure a consistent workflow was followed. Approximately 2,200 plan sets (containing 4,235 drawings) were scanned into PDF format at between 350 and 600 dpi. Every plan sheet was also saved in 'TIF' format to enable importing into ArcMap as a raster image. Geo-referencing of the plans was required to establish the exact location of pits. The following three screen captures display an example plan (Figure 3), the geographical extents of the plan captured in the GIS (Figure 4) and the corresponding polygon created in the Plan Catalogue with associated data (Figure 5). Figure 3 - Plan Scanned in PDF and TIF Figure 4 - Geographical Extents Captured in GIS and Plan Details Figure 5 - Plan Catalogue Polygon and Associated Data A complete record of all plans scanned and catalogued was generated. Database Creation The GIS asset data (pits and pipes), supplied by WCC, was imported into commercially available hydraulic modelling software, InfoWorks CS, to create a "raw" database. The first stage of the network clean-up was undertaken, on the "raw" database, using InfoWorks CS. Checking and correcting of network connectivity using upstream and downstream tracing functions was undertaken.

6 Approximately 51,000 assets were present in the database upon completion of the data clean-up process. This resulted in a fully connected and traceable stormwater network. A digital terrain model (DTM) was generated in InfoWorks from the 0.5 m contours provided by WCC. From the WCC contour data InfoWorks created a TIN (Triangular Irregular Network) ground model to represent the ground surface of the catchment. The ground surface is represented by triangles with known elevations at the triangle vertices. The DTM was then used to assign an initial cover level to each pit in the dataset through use of the inference tool in InfoWorks. Once each pit had a cover level assigned, initial estimates for pipe invert levels could be made. Pipe inverts were calculated by assuming an average pipe depth of 1.2 m which is an indicative average depth for the majority of stormwater pipes. Assigning initial values for both cover levels and pipe inverts provided a good starting point for data entry and validation. It enabled the data to be visually checked using the long section viewing tool and provided a sense check against data entered from plans or field inspection. Establishment of Drainage Catchment Areas (DCAs) The complete stormwater database required splitting into individual catchments to expedite project management, incremental data delivery, QA and progress tracking purposes. Using the DTM, logical boundaries were established to split the network into Drainage Catchment Areas, (DCAs). DCAs were established based on natural drainage catchments and major roads to minimise the frequency of pipes crossing between different DCA's. Figure 6 illustrates the 61 DCAs based on natural drainage catchments, contours and major roads. The area delineated in red illustrates the portion of the network that had previously been validated by Council and is referred to as the "exempted area". Figure 6 - Catchment Subdivision and Council Exempted Area Digitisation and Validation Methodology Prior to commencing work on a DCA, a number of internal set up tasks were undertaken: Using the plan list developed for DCA, every plan containing stormwater data was printed at A3 size and reviewed, marked and checked for spatial accuracy; Associated GIS data such as cadastre, aerial photography, Yarra Valley Water (YVW) sewer network, Melbourne Water (MW) drains, easements, etc. were loaded into ArcMap. When new pits and pipes were required to be added to the database, pits were initially located using offsets, distances or chainages from existing features, particularly property boundaries and existing pits. Frequent use of "Streetview" and aerial photography provided by Council was required to confirm the existence of pits, confirm pit type or even to clarify the drainage connectivity. Pit and pipe attribute fields were populated via the customised data entry forms. Cover levels assigned from the DTM were compared with cover levels derived from plans or survey levels where available. Where plans levels were based on an arbitrary site datum, the DTM value was used as final cover level. Parallel pipes were digitised as per the Council specification and the "PARLINENO" field attribute updated accordingly.

7 QA Checks, Individual Database Delivery and QA Reports An important aspect of the project was the Quality Assurance checks undertaken for each of the 61 individual databases. QA process was developed by the external consultant as per Council Specification. Once a DCA had been completed, extensive QA reviews were undertaken. Interim databases were delivered for Council review after completion of digitisation and Quality Assurance checks. Council undertook in house QA checks on the submitted databases and provided detailed reports of identified issues. The databases were subsequently updated by UWS and Morphum if changes were suggested by Council. Field Verification Due to the large number of locations that were identified as requiring investigation, (approximately 600 at the first cut), it was subsequently agreed with Council to undertake additional checks in order to reduce the number of assets to be investigated. Engineering judgement and assumptions were made to reduce the required number of drainage verification requests to 84. Priority was given to those areas where drainage connectivity was uncertain and not yet determined. A total of 52 Drainage Verification Requests (DVRs) were approved by Council; 24 Future Drainage Verification Requests (FDVRs) were issued and eight were solved by Council using plans information and making engineering judgements. Areas where traffic management was required, were considered as FDVR's For the approved DVRs, a work package was prepared for the nominated field survey subcontractor, Taylor's, to resolve in the field the identified anomalies or data gaps. Some survey equipment is shown in Figure 7. Figure 7 - Survey Equipment Field verification data was incorporated into the interim DCA geo-databases to rectify the identified anomalies. Reports were generated identifying the issues encountered and detailing the changes applied to the databases. Final Deliveries DCAs were combined in a logical sequence to enable the individual database to be joined together into a single geo-database for final delivery to Council. QA checks were undertaken for all areas at the database joins and along the boundaries of the DCAs. All "border plans" identified during the initial creation of the DCAs were reviewed carefully to ensure that no duplicate assets had been generated. A final Master Database including pits, pipes and plans tables was submitted to Council. The final master database consisted of 10,639 plans, 41,476 pits and 40,497 pipes, for a total of 81,973 assets. As results of validation and digitisation processes, the number of pits and pipes in the system increased by 66 % and 53 % respectively. Assumptions and engineering judgement were applied to include linking pipes to maximise logical system connectivity. A total of 1,226 pipes were added to the system in this manner. Where such engineering judgements were made the pipes have been flagged accordingly as per specifications. Dummy nodes were used to identify the end of the extent of pipes shown in the drainage plans. These nodes were flagged for future field investigation because the connectivity could not be determined.

8 Engineering judgements were used for pit depths to populate gaps in the database. Judgements were based on contours, pit location, pit type and depth of surrounding pits. The pit depth was obtained by interpolation of upstream and downstream pit depths. The invert levels were then calculated based on the difference between the pit cover level and pit depth. The main source of issues during the project was the quality of plans provided by Council, being incongruence between plans, missing or incomplete plans, plans superseded by another more recent plan or drainage layout superseded or plans never constructed. Also, field investigations were unable to be completed for assets located in or near main roads due to traffic management requirements. These areas were highlighted for future investigations using full traffic management setups. Minor issues regarding connectivity, logical inclusion and assumed connections, asset existence, pit type etc., were flagged in the Master Database as requiring Future Field Investigation. Conclusion The drainage database developed during this project provides a robust platform from which Council can build an effective and valuable asset management system. On-going data collection and database validation is essential in creating a strong tool which can be utilised across Council. Precise and controlled integration of data into the Hansen8 system will be important in creating a functioning and efficient data management tool. With the completion of the project and receipt of a comprehensive stormwater geo-database, Council has the potential to develop an Asset Management System that leads the way in network understanding and utilisation across Victoria. With the new and powerful technologies available, Council can assimilate, organise and present multiple data in a way that provides more clarity to the wider inter-complexities of our networks, systems and the environment. The project has produced a good base from which a very strong system can be developed. It is essential that the future database is constantly maintained and improved to ensure its true value is realised. The subsequent stages of the process are to increase data accuracy and validity in areas of significance. This can be achieved most effectively through targeted surveying of priority areas, based on network capacity and criticality. By targeting priority areas, an effective solution is achievable. The following are some pathways and future directions that could be considered by the Council to leverage the maximum use of the existing data and incrementally improve the quality of the data set while resolving other issues in the drainage system: Development of Customised Tool for GIS unique ID assignment to new and existing assets, upstream and downstream tracing, longitudinal section review, pipe direction flipping, a suite of QA tools The longitudinal view tool enabled the user to display a long section along the length of a selected run of stormwater pipes (Figure 10). Data such as cover levels, pit type, pit depth, pipe diameter and invert levels were displayed in the longitudinal section view and can be configured to display data from any field in the data tables. Figure 10 - Longitudinal Section of Selected Pipes Figure 11 illustrates a 3D visualisation of the drainage network and aerial photograph draped over the digital terrain model (DTM) in Infoworks.

9 The DTM was used to interpolate and assign a cover level for every pit in the network. flooding for 1 in 100 year storms events, however that information can be improved in the future. Overland flowpaths (OLFPs) are an essential part of any drainage network. Understanding the below ground connectivity of the pipes is necessary to determine the everyday workings of stormwater networks; to understand the full picture during storm conditions when the network performance is critical, overland flowpaths also need to be identified. Figure 11-3D Visualisation of DTM Council has a number of flood prone areas within its jurisdiction. The data collected during this project will enable Council to: Develop hydraulic models of the drainage network for the known problematic catchments; Determine the adequacy of the network data and assess the need for targeted survey at key locations; Commission limited field survey; Update and validate the network attributes in the model with the survey results; Run hydraulic simulations to identify deficiencies in the pipe network as well as the available overland flow paths; Develop 2D mesh from LIDAR data in the flood prone areas to assess depth, velocity and extent of flooding. This may require site visits and feature survey; Holistically analyse the root cause of the flooding problems and subsequently assess the impact of proposed solutions on the model; Include proposed works onto Capital Works program; Update the GIS with the updated network data. Once the known or recurring problem areas are dealt with, Council could embark on a systematic process over a number of years to identify potential problem areas. At the moment Council has identified the areas that are prone to Overland flowpath generation can be achieved through a combination of LIDAR data, design rainfall runoff rating curves and stormwater modelling software. The result of the modelling process is a complete set of defined OLFP s for the entire catchment area. The information is represented spatially in GIS and can be made available to users across the Council. Detailed OLFP maps will support better stormwater planning, design and urban design planning in general and reduce the incidence of flooding occurring. This in turn will support more sustainable development. Acknowledgments Author Biography & Photograph Mirjam Fabijanic has a Bachelor Degree in Civil Engineering from the University of Zagreb, Croatia, equivalent to Master s degree, specialising in hydraulics, and has over 20 years of experience in Local Government in Australia. She has worked in various Councils, mainly in Asset Management, both in roads and drainage.

10 She has undertaken drainage catchment analysis for drainage upgrades, developed the procedures for flood level analysis and worked in determination of the flood levels for land liable to flooding (overland flow for 1 in 100 storms), drainage design etc. She has been actively involved in implementation of Integrated Asset Management System Hansen, focusing both on roads and drainage assets, as well as financial reporting for roads and drains, data collection and surveys of drainage and road assets, development of Road Management Plan and Road and Drainage Asset Management Plans. Currently she is employed by Whitehorse City Council, metropolitan Melbourne municipality, as Engineering Asset Co-ordinator, where she manages both drainage and roads data collection and maintenance, as well various civil permits and approvals related to the extensive development in the area.