Cities and towns of every size face the ongoing challenge of keeping their underground utility infrastructures in good operating condition. One of the basic obstacles in effectively performing this task can be the lack of accurate information about buried pipelines. In the past, mapping procedures often have been haphazard and sometimes, non-existent. Rapid growth has also contributed to the construction of a confusing underground maze.
Clearly it is extremely difficult to maintain a sewer system when no one knows how many structures the system consists of or where all of its elements are located. This paper will discuss the various methods used to rectify the legacy of errors, in developing information where record drawings do not exist, and in removing inconsistencies between the City of Indianapolis’ asset management database and Geographic Information System (GIS).
Like many cities, Indianapolis has sewers with a history. “More than 100 years ago, Indianapolis built a sewer system to carry storm water away from homes, businesses, and streets. When indoor plumbing came later, homes and businesses hooked their sewage lines to these storm sewers, making them combined sewers.” (A Decision Making Guide for Indianapolis Residents July 2000) Today Indianapolis requires separate storm and sanitary sewer lines. The combined sewers still carry raw sewage and storm water in one system. Each year, the Combined Sewer Overflows (CSOs) send sewage, disease-causing bacteria and viruses, industrial chemicals and other pollutants into the city’s waterways. In an effort to fulfill state and federal requirements for CSOs and to improve city response to other storm water drainage complaints, the city has used various methods to track its sewer system.
In 1979 Indianapolis developed a series of paper sewer map books. These books were updated by hand. As sewer as–builts were turned into the city and a room full of draftmen would draw in the sanitary sewer features. The city also used sanitary and contours maps, that were hard to use and updates resulted in a costly reprinting of the documents. The Map books consisted of two-foot contours of the city with sanitary manhole and sanitary line information. The map books used a 1":200' and 1":400' engineering scale In 1986- 1987, the city converted years worth of sewer as-built drawings from the permit division and paper maps into a new digital system, an automated mapping system called SYNERCOM. Asset numbers were assigned to each sewer feature in the city's Facilities Management System (WCMS by Hansen) to track work, and also manage the costs associated with each sewer asset. Corresponding asset numbers were entered into the GIS to provide a link between the 2 databases. The automated mapping (AM) and Facilities Management (FM) systems were then maintained somewhat independently and susceptible to errors, particularly in keeping the unique asset numbers in synch. In this original project, only the sanitary sewers were included.
The next effort was to develop an inventory of the storm drainage system. This was to be a larger task since the City did not have any paper maps showing the storm facilities. The original field inventory of the storm drainage system was conducted in 1990. Crews of private contractors went into the field to collect storm data with hand held data collectors. The Combined Sewer Area, located primarily within the old city limit, contained many inlets and leads. Information was not collected for these features due to budgetary constraints, and higher priority was given to main pipes. This data collection effort resulted in a fairly accurate representation of the storm drainage facilities. However, the data was once again placed in the 2 separate databases, linked with the corresponding asset numbers.
During the next 3 – 4 years, the inefficiencies of maintaining the separate databases took a toll on the overall match rate between the 2 databases. During the mid 1990’s, the graphical SYNERCOM system was migrated to an Esri GIS platform, and the WCMS system was moved to another Hansen product called Infrastructure Management System (IMS). Other as-built conversion projects that followed the field inventory of 1990 eventually contained storm sewer information. Storm sewer information was not originally required for these as-builts. Therefore, when storm drawings were finally required for permit acceptances, it was difficult to enforce a policy to collect complete storm drawings. This made it hard to track repair work on these facilities and also keep a completed inventory.
The nature of the storm and sanitary data collection caused some data inconsistencies and even inaccuracies. Two different engineering firms conducted field inventories with a separate firm entering the attribute information into the IMS database. No independent quality control checking occurred either by another firm or by the city of Indianapolis. The vender was trusted to enter data correctly without the confidence of another pair of eyes. Even though the firms who entered graphical data into GIS and the IMS database information did not synchronize their data entry, the city also did not check to see that the two systems were matched up.
Another problem occurred during the as-built conversion project. Many of the as-builts had been misplaced leaving gaps in the data where no source information was available. The only copy of these plans may not have been in the stack to be digitized, but rather on someone's desk being used for another city project. Consequently, this data was missed and never entered into the city’s database.
The city of Indianapolis is now feeling the pain of years of legacy errors that must now be rectified. According to Governmental Accountancy Standards Board (GASB) Statement No 34, the city is required to report a complete inventory of all City assets by end of year 2003. In an effort to keep an already excellent credit rating, the city must quickly harmonize the graphical and tabular representation of the sewer data to the real world.
In Indianapolis where the sewer system is combined, whenever there is a heavy rain or a snowmelt, it causes the sewers to overflow directly into the city waterways. The Combined Sewer Outfall (or CSO) issue has become a public concern. CSOs have been a hot topic for Indianapolis and many other cities that still maintain a combined system of sewers. CSOs sends an estimated 6 billion gallons of rainwater and raw sewage into the White River and neighboring streams each year. The EPAs Clean Water Act requires the city to control these overflows. The GIS maps help to locate and evaluate each Combined Outfall. With GIS it is possible to identify what sensitive areas deserve priority attention, like nature preserves and places where children are known to wade or play. Another reason that the city needs to maintain a comprehensive storm and sewer layer is for its own agencies and departments. Some departments rely so heavily on these GIS resources that if an inaccuracy is found, the work will wait until the data can be updated or corrected. Accurate GIS data is crucial in the areas of Customer Service, Permits, Planning, Public Safety, and Environmental Protection.
Using the mix of different technologies, the city is attempting to close these data gaps. The city has contracted a firm to inventory inlets in the combined area that were not included in previous contracts. The city has also incorporated a GIS digital standards requirement into new development contracts Enforcement of digital standards will be a key component of keeping this digital inventory up-to-date. With regard to the mismatch GIS and IMS data, there has been a major effort for an in-house data cleanup. Also, QA/QC procedures have been conducted on all conversion and data entry since 1998. Sewer Map Error Report Forms, blue sheets of paper dotingly called SMERFs, have become the internal field verification used by the city to update field data.
The contract to capture the overlooked inlets and basins in the combined sewer area is an esential part of the sewer clean up. It is important to isolate areas that are known sources of field data. The inlets in the combined area are captured by GPS unit purchased by the city to be used for inventory of these facilities. This is a field verified GPS inventory where the data is delivered using ArcView Shapefiles. The Shapefiles are handled just as any other update and loaded into the system after a careful QC process.
The digital standards caused quite a stir in the engineering community when the first iteration was released in 1999. The digital standards are still just a request for private building contracts. The digital submission standards are now an integral part of all city building contracts. It has taken a long time for building contracts to be accepted by the city. When the standards were first introduced, there was confusion regarding how to adhere to the standards and unacceptable plans came pouring in. The GIS division modified the standards to refine the document based on recommendations from Project Managers from public and private development. In an effort to help the engineering community comply with these new digital standards, the city has hosted training sessions for contractors. The city has been unsuccessful in requiring the digital standard from the private contractors. Successful digital updates will still require QC, but the process of conversion is faster and if the standards were followed by most of the contractors there would not be a need for another expensive conversion contract from a private vender.
A large data clean-up effort is currently underway at the City of Indianapolis. In an effort to synchronize the GIS system and the asset management system, automated scripts have been developed in ArcView to check both systems for matching assets numbers. With interns and full time staff working together, each record that does not correspond is reconciled.
Among the various processes, Woolpert LLP was contracted to rectify data through the use of real-time kinematic GPS (RTK). Additionally, the program uses field crews and has been working with digital plan submissions. The City of Indianapolis is employing an innovative utility mapping and condition-assessment program to improve the maintenance program of its water and wastewater collection and conveyance infrastructure.
The city's Department of Public Works (DPW) implemented a program that employed GPS (Global Positioning System) and infrastructure inventory and field mapping software to accurately identify the location, physical characteristics, and connectivity of the city's storm and wastewater piping networks. The program identified system deficiencies and prioritized the sequence in which they were addressed.
The procedure is innovative because it allows for updating of source mapping and database creation on-the-fly. It is a solution to the age-old problem of how to maintain something you don't know about or don't know where it is.
The GPS program initially began as a pilot project. The city selected 79 areas comprising approximately 16 square miles where existing mapping and infrastructure databases were determined to be insufficient. The Customer Service Division used Arial photos, existing GIS sewer data and the knowledge base of the staff to identify geographic locations where GIS data was missing. Woolpert, a design /engineering firm specializing in creating GIS coverages for utility systems, was hired to make the infrastructure inventory and mapping updates. The goal was to update utility maps in these areas and simultaneously update the City’s IMS and GIS systems.
Woolpert developed a plan that would use its in-house GIS specialization to prepare accurate maps and database information that could be easily imported to the city's Hansen IMS package. The approach developed by Woolpert included a two-pass survey process. The first pass collected information about approximate location of utility elements and confirmed system connectivity. The second step pinpointed location to within three-to-five centimeters with x, y, and z coordinate values.
The first pass used Real-Time Differential (RTD) and GPS receivers connected to pen-based computers operating SmartSurveyor mapping software developed by Woolpert. Existing City infrastructure information was shown on the pen computer as a backdrop. The utility location, identified by the GPS receiver, was pictured as a crosshair.
This method permitted field crew members to see where they were on the map as they located infrastructure and conducted inventory and condition assessments. Based on information in existing as-built and mapping, DPW personnel believed that approximately 1,200 new utility structures would be encountered in the 79 project areas. Initial efforts found many more utility elements than anticipated. After completing fieldwork in 23 of 79 selected areas, Woolpert crews identified more than 1,200 new elements.
The City of Indianapolis is determined to clean up errors left behind from former contracts and the difficult maintenance procedures of separate geographic and management databases. Based on GASB and other requirements, Indianapolis is required to maintain complete and accurate asset data. Integration of a work management system necessitates an accurate inventory. The City is currently in the process of finalizing a new data model in which to store the sewer data. This model is based upon the new ArcGIS environment and will take advantage of many of the new capabilities provided by this product. Although the GIS and the Hansen IMS databases will remain separate for now, a new custom extension to ArcMap will allow simultaneous edit of both data sets. One point of data entry will help reduce the errors. Developing an automated data entry through digital submissions to keep current and accrete to reduce back-log, effort, and cost. There will be other migrations and new software that does bigger and better things, yet it is important to have the data as clean as possible before moving to another system.