- SPECIAL REPORTS
- THE MAGAZINE
New construction, developments and roadways represent the telltale signs of a thriving town. They also contribute to the ongoing challenges faced by cities in maintaining accurate GIS data for their assets. For the city of Modesto, Calif., ongoing civic expansion paired with rising challenges to facilitate routine data collection resulted in a heightened need in 2008 for an updated program. By then, gathering an accurate view of the city’s infrastructure meant inventorying 641 miles of sanitary sewer main pipe, 135 miles of storm drain main pipe and 21,500 utility holes.
Fortunately, a well-devised strategy and efficiently executed program with appropriate partners provided the city with not only with an advanced GIS but also statewide acclaim from the engineering community.
On the Front LinesFor a city with more than 125 years of history (and an equally aged infrastructure in some places), Modesto’s challenges in maintaining a GIS were not unusual. Data on access points (manholes) to the city’s storm and sewer systems were regularly inventoried and logged through the 1980s. However, shifting municipal resources and priorities in the ensuing years did not allow ongoing maintenance of infrastructure and parcel information. Consequently, gaps were evolving in the city’s spatial data.
Robert Beckler, Modesto’s GIS coordinator, assumed responsibility of the system in 1999. “When I arrived on the job, we were beginning to acquire CAD drawings while I surveyed Modesto’s landscape with one other employee working to compile GIS data from paper plans,” he explains. “While we were somewhat successful, we were discovering holes in the data and realized we didn’t have a complete picture of what was out there with respect to sewer and storm systems.”
Beckler notes that among noticeable issues were challenges faced by maintenance crews addressing incidents, such as a sewer blockage at night. Without access points clearly identified either on a facility map or a comprehensive GIS, maintenance staffs working with limited light often had difficulty resolving the problem. Additionally, the city wanted to integrate its GIS fully with its Cass Works maintenance software to allow more-precise ways to locate and address storm and sewer issues.
By 2007, Beckler and city engineering staff had identified several of the gaps in data while making strides to collect new geographic information. An estimated 50 to 60 percent of the data points in the system were accurate to within 1 to 3 feet, but the accuracy of other areas ranged between 10 to 75 feet. Noting its outstanding needs, the city of Modesto made a conscious effort to enlist the support of an outside consultant to quickly bring the system up to speed.
Forging AlliancesBeckler and a key group of city representatives formed a selection committee that compiled and distributed a detailed RFP to targeted surveying firms to assist the city in collecting GIS data. Among the unique attributes of the information requested was a statement of each firm’s working philosophy. “To remain cost efficient, we needed to know more about the individual project components and the costs associated with them--not just project completion fees,” Beckler says. The firms also needed to possess a blend of technical expertise and local knowledge.
After reviewing several potential vendors, Beckler and his counterparts found the appropriate mix in Stantec Consulting Inc., a North American firm with an office in Modesto, teamed with locally based O’Dell Engineers for ancillary project support. Stantec’s Modesto-based survey manager, Seth H. Irish, PLS, served as the project manager for the work. “The city of Modesto was very clear about the resources they had and the expectations they wanted a retained firm to meet with respect to timeframe,” Irish says. “This actually helps a firm like ours to set accurate budget parameters with respect to scope of work and necessary personnel.” (See the sidebar on page 14, “Keys to a Successful Partnership.”)
Devising a Strategy
Noting the project scope, Irish and his team reviewed the city’s existing data assets and determined that data collection would require the inventorying of hundreds of miles of sewer main and storm drain pipe and utility hole attributes. To gather the inventory, the Stantec team collected the existing GIS assets, scanned as-builts of sanitary sewer and storm drain plans, updated city/county benchmarks, and exported information from external databases.
With the initial inventory complete, Stantec led a field survey effort with support from O’Dell Engineers consisting of 8 to 12 crews to effectively capture each site for integration into the system.
To manage the project in a grid format, the systems were divided into 54 geographic areas so that regions with similar surface characteristics could be addressed uniformly and avoid overlapping of efforts. Each area would require two to three days of crew coverage. At each site, field staff would be responsible for locating and conducting inventory of sanitary sewer and storm drain structures, in addition to dry well catch basins.
The use of GNSS technology played an integral role in streamlining the process. Each survey crew member was armed with a Trimble handheld device that contained the inventoried data of the city’s systems using ArcGIS software. They also utilized the printed sheets of the city’s existing recorded GIS points for added direction in finding locations. Once the sites were located in the field, surveyors relocated each structure’s X, Y and Z coordinates using Trimble R8 GNSS receivers linked to a VRS (virtual reference system) network and Trimble S6 robotic total stations (in tandem, when necessary) and stored the assets in the units. Beckler and Irish would oversee daily quality control of the new assets before integrating them into the GIS through an AutoCAD program. Production goals included 100 site inventories per day, with an average of 10 minutes needed per location. The crews relied on the support of eight to 12 GNSS units in use at any one time.
To ensure that each crew member had a consistent understanding of project goals and procedures, the team underwent a three-hour training session before initiating work. Among the most pressing issues to address was making sure field staff were recognizing poor positional dilution of precision (PDOP) signals within the urban environment and that accurate data were being collected. Without due attention to these and other quality management matters, crews would run the risk of wasting an entire day’s effort if reliable data were not obtained.
To make certain that GNSS devices used by both O’Dell Engineers and Stantec worked cohesively, a pilot program was completed in a test area to recognize, address and resolve compatibility issues before moving on with the entire project.
Overcoming ObstaclesThe landscape varied from residential areas to congested downtown regions, so Stantec had to work creatively with the city to cover the diverse areas. Among the initial challenges was the city’s flourishing vegetation and greenery, especially in some of the town’s more historic areas. With nearly half of the 54 areas heavily shaded by trees, poor PDOP situations were frequently encountered. The R8’s Glonass capabilities provided improved initialization times and measurement precision in many of the canopy-covered areas. In situations where the overhead obstructions were causing degraded satellite signal reception, the field teams conducted conventional surveys using the robotic Trimble S6 total station.
Other areas of the city represented a different challenge--access. By day, many of the targeted regions were blanketed with parked cars or were in highly trafficked thoroughfares, making entry difficult. For these sites, the surveyors conducted their inventories at night working with city traffic control staff to minimize road delays during peak hours.
Throughout the survey effort, field crews made note of sites were access was obstructed by turf, pavement or other cumulative development that made inventory impossible. With a growing list of these sites, the city partnered with the team to provide maintenance crews to remove soil, asphalt or other elements. The last five percent of the site inventories fell into this category, and the collaborative efforts between the survey team and the city supported the accelerated schedule goals.
Communicating the MissionConducting a widespread effort in a city such as Modesto required an element of understanding, occasional patience and overall acceptance on the part of its residents. The City of Modesto did an excellent job of communicating the overall strategy to the public through local newspapers and other media outlets. Even so, the surveyors were often on the front line fielding the questions of curious residents. “To every single question or concern voiced by a resident to one of our crews, I developed a simple but effective strategy,” Irish says. “I gave each surveyor a stack of my business cards and told them to encourage residents to call me personally with their queries.”
By his estimate, Irish distributed 500 cards in this manner and fielded 100 calls. “The majority of residents feel comfort alone in knowing they can call someone if need be,” he says.
The Stantec team’s survey crews were also the first point of contact for residents whose property required access for data collection. For each of these scenarios (there were roughly 300 such cases), Stantec handled the requests and follow-up questions on behalf of the city.
Managing the DataThroughout the project, Stantec worked with the city to maintain an FTP site that made all GIS and project status files fully available to all stakeholders. Each time a new file folder was added to the site, the survey team sent an e-mail notification to the various city departments. Microsoft Project played a key role in providing a stream of status reports to key counterparts throughout the city. PDFs were also distributed for anyone who didn’t have access to the software.
A total of 42,500 points were captured by survey teams during a 54-week period. The infrastructure assessment and field verifications on the city’s sanitary sewer and storm drain systems yielded a precision of 0.03 feet horizontally and 0.10 feet vertically for all locations. “The situation has so greatly improved--we can say now we’re at nearly 100 percent,” says Beckler, who notes that a small margin of the system will remain in constant flux exponentially with ongoing city development.
Working as cohesive teams, the survey crews were able to capture each site in an average of 6.5 minutes--considerably faster than the 10-minute capture time that was originally proposed. This time savings was instrumental in meeting the project’s accelerated schedule.
Beckler has since worked to make the GIS data available via the city’s intranet, providing unprecedented utility information to various city departments. With the GIS data current and integrated into the city’s other utility databases, the city has innovative capabilities beyond most cities of its size and dynamics, including spatial modeling. Using the newly acquired data, the City of Modesto can proactively or reactively measure a flooding dynamic and anticipate the water flow and reach. Additionally, the new GIS can be used to assess quantities of piping materials for inventory purposes. Proactively, Beckler and his counterparts can provide long-term oversight on regions of the system and identify pipe segments or areas of the system that require the most frequent maintenance. This type of intelligence can be a considerable asset, as the city can now potentially pinpoint larger-scale issues to address in those sectors that experience increased maintenance needs.
With continued support to the city, Stantec provided a summarized report with both analytical and observational notes on accomplishments and lessons learned. Additionally, Irish and his team created a compiled booklet of revised facility maps and a procedure manual to describe the methodology for the project, such as a data dictionary, document management system, surveying data collection standards, and rules for validating GIS data integrity.
Earning Statewide Acclaim
Following the project’s completion, the City of Modesto’s enhanced GIS system was recognized in 2010 by the American Council of Engineering Companies California with a merit distinction in the organization’s Engineering Excellence Award Competition. Among the elements earning the city and the Stantec team this distinction was the expedient delivery, effective use of GNSS technology, and the quality of the resulting GIS data, which will support the city of Modesto for decades in locating assets, evaluating longevity and condition, and assisting during emergencies. “Cities should really value the potential for a GIS system in addressing a wide scope of issues,” Beckler says. “Many departments at the City of Modesto have really come to understand the value of this information with its newfound accessibility.”
Keys to a Successful PartnershipBoth Beckler and Irish agree that three key elements made the initiation of the partnership successful for the Modesto project. These same strategies can be applied in any municipality project.
• Provide precise data accuracy goals. Rather than making a general request for GIS data upgrades, the city discussed Stantec’s capabilities and ultimately specified that data points would need to be measure to a high degree of precision (within 0.03’ horizontally and 0.10’ vertically). This provided a clear benchmark to evaluate success.
• Develop a realistic schedule and deadline. To address overdue city needs and available windows of public agency funding, the City of Modesto was seeking an accelerated schedule that would bring the project to completion in July 2008, providing an overall window of five to seven months. Although the timeframe was challenging, having the information at the outset allowed Irish and his team to estimate an average data collection time per site that would allot a feasible schedule for project completion.
• Identify mission-critical components at the outset. Working with the city, Stantec made recommendations to alter the project scope so it could eliminate components that were nonessential to meet the objective efficiently. Revisions to the strategy resulted in the project costs being reduced nearly 50 percent, a final component to solidify the relationship between the city and the Stantec/O’Dell team.