The New Age for Sewer Planning at the City of Los Angeles

Transcription

1 The New Age for Sewer Planning at the City of Los Angeles Mario Dimzon 1 * P.E., Fernando Gonzalez 1 P.E., Ali Poosti 1 PE, Adel Hagekhalil 1 PE, Erick Heath 2 P.E., Rajan Ray 2 P.E., Erin Breen 2 P.E. 1 City of Los Angeles, LASAN 2 Innovyze, Inc. * mario.dimzon@lacity.org ABSTRACT The City of Los Angeles Department of Public Works Bureau of Sanitation (LASAN) is responsible for operating and maintaining one of the world s largest wastewater collection and treatment systems. It has been conducting advance planning for its 6,700-mile sewer system for decades using very conservative and technically sound engineering principles and tools. The sewer assets are rapidly deteriorating and so it is paramount for LASAN to continually upgrade the sewer system to ensure that the health of the public and the environment are protected. In 2007, LASAN custom-developed an application called SPOT (Sewer Planning Optimization Tool) to fit the specific planning needs of LASAN. SPOT was successfully used to prepare the 100 highest priority secondary sewer basin plans required by a Collection System Settlement Agreement (CSSA). The SPOT model played an important role in secondary collection system (i.e., sewers less than 16 inches in diameter) planning and rehabilitation by efficiently tracking and addressing structural and hydraulic deficiencies, conducting studies to evaluate the effectiveness of various root control methods, and providing support for Difficult-To-Access Reaches (DAR) program. This customized solution seemed to be a great fit but it posed to be a large challenge when the contract with the SPOT developer expired resulting in a program that would quickly be obsolete. LASAN needed to continue their progress with their sewer planning and they identified a need to obtain a Commercial-Off-the-Shelf (COTS) software that provides as a minimum, the same basic functionalities as SPOT, and is supported by a commercial vendor who can provide maintenance and upgrade at a nominal cost. LASAN selected Innovyze s InfoMaster tool to fill that role. By utilizing CCTV inspection data, GIS data layers, GIS-integrated hydraulic models, O&M data, and other available data sources within Innovyze s InfoMaster tool, LASAN is continually and systematically able to continue where SPOT left off and obtain a more complete estimation of the true likelihood and consequence of sewer asset failures. With this information, they are able to continue to provide defensible prioritization schedules on their most critical sewer assets. This paper concentrates on how LASAN is using off-the-shelf GIS-integrated applications that integrate with their existing workflows to develop a comprehensive capital planning tool. Techniques, tips, and requirements for these types of analyses will be presented along with a working example demonstrating how LASAN performed a detailed Risk Assessment and develop a complete Rehabilitation Plan for the LASAN wastewater system. 1353

2 KEYWORDS Sewer System Planning, CCTV inspection, Sewer Renewal, Risk Analysis, Likelihood and Consequence of Failure, COTS software, GIS, InfoMaster, Innovyze, LASAN, City of Los Angeles, Prioritization, Asset Management, Risk Assessment, Failure Probability BACKGROUND The City of Los Angeles (City) wastewater system is a huge and complex system. It serves over 4 million residents in over 600 square miles of area. It consists of a network of over 6,700 miles of sewers ranging in size from 6-inch to 150-inch in diameter and 47 pumping stations connected to four wastewater treatment plants with a total treatment capacity of 572 mgd. It serves 29 cities and agencies that contract with the City for their wastewater conveyance and treatment. See Figure 1. Figure 1 LASAN Service Area The City of Los Angeles Department of Public Works Bureau of Sanitation (LASAN) has been conducting advance planning for its sewer system for decades using very conservative and technically sound engineering principles and tools. It has an extensive advance planning program that identifies the existing capacity deficiencies and future needs for its wastewater facilities. The City has identified, planned, built and renewed thousands of miles of sewers over the years to accommodate growth and system needs. The City's planning documents, master plans, and concept reports analyze the sewer system in detail and generate existing and future flows and identify existing and future deficiencies, flow accumulation, and flow generation procedures. 1354

3 Advanced planning is conducted for Primary Sewers and Secondary Sewers. Primary sewers include sewers, interceptors and outfalls 16-inch in diameter and larger. Approximately 10% of the 6,700 miles, or 670 miles, of sewers fall into this category. Secondary sewers are defined as 15-inch in diameter and smaller and make up about 90% of the entire system, or about 6,000 miles of sewers. The City s sewer shed is divided into 26 primary sewer basins and further subdivided into 240 secondary sewer basins. In 2007, LASAN custom-developed an application called SPOT (Sewer Planning Optimization Tool) to fit the specific planning needs of LASAN. SPOT was successfully used to prepare the 100 highest priority secondary sewer basin plans required by a Collection System Settlement Agreement (CSSA). The SPOT model played an important role in secondary collection system planning and rehabilitation by efficiently tracking and addressing structural and hydraulic deficiencies, conducting studies to evaluate the effectiveness of various root control methods, and providing support for Difficult-To-Access Reaches (DAR) program. This customized solution seemed to be a great fit but it posed to be a large challenge when the contract with the SPOT developer expired resulting in a program that would quickly become obsolete. DATA AVAILABILITY AND COLLECTION Performing sewer planning for replacement and rehabilitation on 6,700 miles of sewers presents numerous challenges with respect to business processes, coordination and management. There is massive amount of data to be collected, organized and analyzed. Specific challenges include the validation and centralization of existing 18 unique data sources that are important to the decision-making on over 140,000 sewer pipes, standardization of decision processes to ensure consistent results, and management of the data necessary to support the decision process. Some of these data sources have conflicting information that needed to be validated and some are constantly changing. The data sources include pipe and maintenance hole (MH) inventory information, CCTV inspection videos and pipe defect logs, gauging information, cleaning, root control, hot spots or sewer system overflows (SSOs), MH raising program, parallel emergency sewer repair, and other operation and maintenance information. These data sources are scattered through several servers maintained by various divisions and bureaus within the City and needed to be gathered into a centralized database of record. Since CCTV is the primary means of assessment, a critical component is to link GIS to CCTV video and defect information. SOFTWARE SELECTION LASAN needed to continue their progress with their sewer planning and with SPOT not being able to be upgraded and maintained, a need was identified to obtain a Commercial-Off-the-Shelf (COTS) software that provides as a minimum, the same basic functionalities as SPOT, and is supported by a commercial vendor who can provide maintenance and upgrade at a nominal cost. This challenge is widespread across utilities in the US as the technology used to develop these capital improvement programs are either customized solutions or complex, homegrown spreadsheets which are both difficult to maintain, don t make use of all of the most recent data 1355

4 sets available, and it is not straightforward to easily justify and share the results. LASAN selected Innovyze s InfoMaster tool to fill that role. The minimum functionalities required are: Data viewing access to different planning data sources using one interface. Planning Decision Algorithm execute planning decision algorithm to determine replacement, rehabilitation, repair solution CCTV data viewer access to and viewing of videos and defect data Management of planning data centralized database of record Planning report support generate report figures, maps, tables SELECTION OF INFOMASTER InfoMaster not only provides the same basic functionalities as SPOT, but provides additional functionalities that enhance the planning process. With InfoMaster, LASAN is able to continually and systematically continue where SPOT left off and obtain an estimation of the true likelihood and consequence of sewer asset failures. With this information, LASAN are able to continue to provide defensible prioritization schedules on their most critical sewer assets. This solution allows for a more detailed, granular approach for LASAN which every asset now has a risk score either determined by the CCTV inspection associated with the asset or calculated by probability and consequence of failure calculation. Probability (likelihood) of failure will be based on a variety of factors found in their GIS such as age, material, soil type, break history, etc. Consequence of failure (i.e. quantifying the consequences if an asset fails) is based on proximity to critical customers, water bodies, highways, etc. SOFTWARE UTILIZATION The software solution provides a centralized data platform for LASAN s many moving parts when it comes to collecting, storing, and disseminating data across the relevant LASAN teams. With 18 different data sources, InfoMaster provides automatic data retrieval from three existing live servers and allows user to update and add new data sources/servers regardless of source data format. The comparison and validation of LASAN s data sets within InfoMaster provide for increasing levels of data confidence as well as a platform to immediately address data anomalies. Validation rules such as invert elevation discrepancies, unusual pipe slopes, disconnected nodes, diameter discrepancies, crossing pipes, unusual manhole depths, invalid IDs, etc. provide an instant check on new data being applied in the software. These validation rules are customized to LASAN s system so that they are able to fine tune the warnings provided from these queries. For example, invert elevation ranges are based on elevations specific to LASAN services areas. Once validation rules are run, the identified data discrepancies can be flagged and exported to LASAN s GIS team to rectify or they can be adjusted using InfoMaster s inference tools. One can run the inference tools to infer pipe invert elevations, verify network connectivity, fix pipe direction, extract node elevation, fix invalid IDs, and more. As CCTV is a critical data point in assessing the status of a pipe, InfoMaster is able to automatically import videos, geocode defects, and track the history of the assets in terms of 1356

5 inspections. With GIS-integration, LASAN is now able to view the CCTV video and navigate to specific defects in an integrated 3D and plan view which provides an efficient validation on their CCTV video as shown in Figure 2. Figure 2 Integrated CCTV 3D Pipe and Video Viewing For linear assets that do not have CCTV data, InfoMaster has a set of configurable algorithms for identifying the risk score of an asset and then another multi-step decision algorithm to determine preliminary recommendations for pipe and structure repair. Based on establishing the likelihood and consequence of a pipe failing, LASAN uses InfoMaster to provide defensible criteria for establishing an asset s replacement and inspection priority. Being able to develop risk comparison scenarios based on LASAN s numerous variables that can be weighted appropriately provided another level of validation as staff is able to determine the relative impact of factors such as age, material, soil type, pipe lining, break history, etc. This solution allows for a more detailed, granular approach for LASAN which every asset now has a risk score either determined by the CCTV inspection associated with the asset or calculated by probability and consequence of failure calculation. Probability (likelihood) of failure will be based on a variety of factors found in their GIS such as age, material, soil type, break history, etc. Consequence of failure (i.e. quantifying the consequences if an asset fails) is based on proximity to critical customers, water bodies, highways, etc. See Figure

6 Figure 3 Risk Profile Management Based on existing defects, likelihood and consequence of failure, and other criteria, LASAN s new software solution provides detailed risk analysis for each sewer pipe. Once a risk score is determined for each asset, this is then used to prioritize which sewers require rehabilitation first versus others that may be able to wait until future years. The prioritized Rehabilitation Plan will ensure that LASAN "gets the most bang for the buck" and lower their total system risk as opposed to simply replacing older pipes first. Being completely integrated with GIS is crucial as it allows for smarter rehabilitation actions by corresponding pipeline repairs spatially with existing street paving and restoration schedules. They are also able to facilitate pipe rehabilitation and replacement decisions with configurable tools for building a detailed decision tree. The decision tree automatically updates the attribute table to document the path the asset took to reach its respective rehabilitation decision. This is an advantage from the previous approach as it provides a completely defensible means of establishing why a certain pipe was identified as a replacement, relining, point repair, or other. LASAN is also able to quantify and compare costs based on applying different decision tree models. See Figure

7 Figure 4 Rehabilitation Decision Tree Configurable graphical and tabular reporting and summarization based on the existing SPOT reporting for SSRP was critical for LASAN to continue with a new software solution. LASAN acquired the ability to configure any type of report including forms, graphs, pivot tables, attribute summations, financial calculations, and much more. LASAN can now configure tables of their entire sewer system or by sewer basin with summations of pipe length by age, material, soil type, and other attributes; pie charts; and 2D and/or 3D graphs of maintenance history (leaks, breaks, fixes and repairs). MOVING FORWARD LASAN will continue to incorporate new data sets and results into the InfoMaster database to continually update and improve their asset management strategy. They began managing their top 100 secondary sewer basins in 2007 using SPOT, thereby leaving an additional 140 secondary sewer basins to be analyzed using InfoMaster. The time saved using the functionality of InfoMaster will allow LASAN to better prioritize and allocate funding to the system as needed. They are also looking to produce full sewer basin reports utilizing the built-in custom reporting tool within InfoMaster in order to auto-generate comprehensive CIP reports unique to their needs. While LASAN continues to build upon their strategy, they look forward to being able to utilize the full risk assessment parameters within InfoMaster, as well as regression analysis and asset deterioration modeling. They will continue to use InfoMaster to leverage their existing GIS and IT investments to provide critical insight into all enterprise assets, their conditions and work processes, and utilize the software to drive higher productivity and quality while managing costs and increasing operational flexibility. 1359