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A huge drainage mapping project increases the value of stormwater infrastructure. By John Hannel
Hamilton County Surveyor Kenton Ward remembers when he first started at the county in 1977. Most of the land was Indiana farm fields with a few subdivisions here and there. Homes cost well under $100,000. The population was about 70,000. Miles of regulated drains were about 600, the records and maps of which were painstakingly kept on paper. Regulated drains are a big deal in Indiana, a state where water is abundant. From Lake Michigan to the Ohio River and all of the bodies of water in between, the Hoosier State rarely sees a shortage of this resource. The issue of how to manage it has been the subject of debate since settlers first started making their way west across the United States. Various acts by Congress and the State of Indiana more than a century ago established regulated drains mainly as a way to make more land suitable for farming purposes. Under current law, county drainage boards, of which the county surveyor is a member, oversee agricultural field tiles, urban storm sewer closed drains, and open drains/ditches. In Hamilton County, the drainage board also oversees drains within some of the municipalities, including drains that were once in unincorporated township areas but became part of a municipality through annexation. The drainage board also has the power to ensure new drains are built as needed. Through the late 1970s, the 1980s, and into the early 1990s, Hamilton County continued to meticulously maintain paper records and maps of its regulated drains. “We had so much data, if someone needed information, I might spend an hour digging through just one file drawer,” Ward says.
But this sleepy county directly north of Indianapolis was about to be jarred awake by an influx of new citizens wanting to build new homes and new businesses. The county’s population, which had been growing steadily through the decades, was about to sharply spike. Landowners would want to know what they could do and couldn’t do in terms of development and drainage—and they’d want to know faster than paper records could provide. Hamilton County Project Manager Suzie Mills remembers it was almost like a light switch went on. “Right about the mid-1990s, the boom started.” It hasn’t abated. Today, Hamilton County is the fastest growing county in Indiana and the 16th fastest growing in the United States, according to the US Census Bureau. The population is 231,760. From 1990 to 2000, 73,804 people moved into the county—a 68% population increase. The county has the highest per-capita income in the state. Fashionable Hamilton County cities like Carmel and Fishers are among the addresses of choice in the Indianapolis metro region, with home prices pushing half a million dollars and more not uncommon.
The number of regulated drainage miles that the county tracks and maintains today is 1,145 and counting—almost double the 600 miles maintained back in 1977. “In 1995, we inspected eight subdivisions. In 2004, we inspected 89,” Mills notes. Near the beginning of the boom, the county invested in the development of a geographic information system (GIS) and started to digitally map data. But for stormwater features, a huge gap existed between what was digitized starting in 1996 and all of those meticulously maintained paper records and maps, some dating as far back as the 1800s. “Large parts of our stormwater GIS features didn’t have historical data, and nothing had been done with all of the development maps,” says Mills. “We were so busy with growth, it was all we could do just to input basic new stuff as it came in.” Meanwhile, new government mandates were looming on the horizon: the National Pollutant Discharge Elimination System (NPDES) and Governmental Accounting Standards Board (GASB) Statement 34, mandates that have now become a part of every stormwater manager’s vernacular—mandates that would require better, faster record-keeping and analysis.
It was time to upgrade the stormwater GIS layers, and that meant going through the multitudes of drainage files. Because of the huge amount of development in the county, this effort required not only reviewing each record, but also, for each area, identifying the drainage records that were the most current. The most time-consuming part of this effort was to compile all of these records and input only the most current into the GIS. Many information resources were used to accomplish this goal, including multiple years of orthophotography, surveyors’ notes, platted subdivision documents, the tremendous number of drainage records, and even field verification when necessary. With this effort, Hamilton County would become among the first in the nation to GIS-map its regulated drains to a level of detail that also included field tiles—something most communities don’t put into a GIS because usually no paper records exist of field tiles. Hamilton County’s years of thorough record-keeping down to field-tile detail put the county in the unusual position of being able to digitally map every regulated drain. For any community on the cusp or in the midst of a growth spurt, Hamilton County’s experience in building the new GIS—the lessons learned and the benefits gained—offers good perspective. Building the New Stormwater GIS Layers
Indiana passed the Drainage Code in the 1960s, and authority for drainage passed to county drainage boards, of which the county surveyor is the technical advisor and a non-voting member. About this time, the Hamilton County Surveyor’s Office started making Mylar maps of the regulated drains and compiling them in “greenbook” summaries, an indexing system that correlated each drain to its legal description. It was the most recent greenbook summary that the county handed to Woolpert Inc., its civil engineering consultant, and said, “Here’s where and what we think things are. Verify it.” So, armed with the list, by name, of the more than 350 known regulated drains, as well as the current stormwater GIS layers, the Woolpert team dived into a pool of paper stored at the county and began the verification process.
“It was a huge undertaking—rarely do you see that quantity of paper, that level of detail in record-keeping. But we had to go through everything—see how everything fit together—to understand where everything stood today,” says Jared Livingston, one of the Woolpert managers assigned to the task. Because of the quantity of the data, the team determined the best option was to do all review and digitizing onsite at the county. Livingston and Jonathan Hull, a Woolpert GIS analyst, moved into the surveyor’s office full-time for about a year, clocking about 4,000 hours reviewing thousands of paper records and maps and orthophotos, deeming what data were necessary for field verification, what maps should be digitized, and what records should be scanned and saved as PDF files for archival and public-access purposes.
They poured through the multitudes of historical and contemporary data—the books on the shelves and the newer data stuffed into rows of filing cabinets that snaked around cubicles in the surveyor’s office. They reviewed multiple years’ worth of orthophotos; the county had flown orthos about every other year since 1996. The reasons for reviewing each year’s worth of orthos were big and small. Often, orthos from one year showed farm fields; two years later, the subsequent orthos showed subdivisions. “The landscape had completely changed in just two years’ time and, with it, the regulated drains,” Livingston says. Sometimes, the review indicated something as small as a car covering up a street drain, but then the subsequent ortho would reveal the drain.
Ultimately, the data deemed valid and current for each drain were updated in the GIS, and the originals were boxed and moved to a secure spot with controlled but easy access for authorized personnel. The bulk of the paper was moved into “dead-file” storage after scanning. Scanned files were stored appropriately. Items that still were valid were stored and linked back to the GIS and corresponding drain feature. Items that were no longer relevant were digitally archived. With GASB and NPDES in mind, Woolpert performed the following for each drainage facility:
As part of this data-compilation process, the team also converted regulated drainage easements into the GIS. The county knew it would be important not only to know where these easements existed but also to recognize and report on their value, as assets, in the GASB valuation process. However, because development had so radically changed the landscape and the drains, it was more logical to input the easement features on the heels of completing the actual drainage layers—in other words, to input the easement features in the GIS, the most accurate and current map. In the end, the team had physically researched every regulated drain and easement within the county to ensure its currency and accuracy. Old paper records had proved so complete that only eight drains, out of 365, were newly identified in the field. Accurate, Accessible Repository “I have complete confidence in the GIS. When I go into it, I know this is the single most accurate repository of our data,” Mills says. Now, anyone—whether a county employee, a resident, or a developer—can view, download, and use the data. GIS stormwater layers and other data reside in the “map room” on Hamilton County’s Web site (www.co.hamilton.in.us). Drawings of each regulated drain are available, as are documents of record for each drain, scanned and saved as a PDF file. Documents include:
“We had a lot of data, and we had to make choices about what to keep digitally and what to let go of,” Mills says. “The process didn’t just force us to look at the past; it also forced us to consider the future: What kind of data could we realistically maintain as the county continued to develop?” As a result of this process, the county came to several conclusions:
GASB Statement 34 Without a GIS, meeting GASB’s requirements is a less accurate, more painful process. “A lot of governments make a ‘best guess’ about the amount, condition, and value of their infrastructure,” Livingston says. “Unfortunately, that method almost never does true justice to an organization’s balance sheets.” With its new GIS, Hamilton County’s balance sheet looks more like a business, which, in turn, drives up its bond rating, enabling the county to make more capital improvements. The county can easily calculate, report, and leverage the value of its infrastructure. The county’s GIS drives a customized GASB tab in POSSE, the county’s customized CMMS (computerized maintenance and permit management system), eliminating the need to separately input infrastructure values into a spreadsheet, a task that could take at least a couple of days. Linking the GASB tab directly to the maintenance and permit management system ensures the most accurate values, because POSSE is updated more frequently than the GIS layers. “We just go to our GASB tab and, with the click of a button, can calculate GASB reporting in a few minutes’ time. No more guessing the value of our infrastructure. Now, we know, and we know fast,” Mills says. Based on the new stormwater GIS layers, the county saw a net gain of almost $208 million in GASB Statement 34 reported value of drainage assets in 2004 versus in 2003 (when the county did not have these stormwater GIS assets firmly in place). In terms of easement assets alone, values jumped to $159.8 million in 2004 from $10.4 million in 2003. NPDES
“What I like about the GIS is it enables us to have a complete picture of the watershed. Before, we’d have to pull out four or five Mylar maps. Now, we can easily see how doing something in one area will have an impact on a surrounding area,” Ward says. “We can manage all the variables and come up with the best solution for our citizens and the development community, and for meeting government requirements.” Tasks such as these occur daily at the surveyor’s office. What once took hours with paper records now takes minutes with the GIS layers. As part of continuing NPDES efforts, the county recently conducted a pilot project of outfall mapping along three creeks—about 3% of the county—in order to locate and attribute county stream inflows and develop a baseline of GIS data to support dry-weather screening requirements. Woolpert flew a LiDAR (light detection and ranging) mission in 2005 and also captured new orthos at 6-inch-pixel resolution in order to create new floodplain maps. The LiDAR and ortho data, their planimetrics, and stormwater GIS data were loaded onto pentop computers—along with the county’s existing assessment base map layers—which were used by Woolpert field crews who walked the county waterways, verifying locations and attributes using Woolpert’s SmartSurveyor software in conjunction with global positioning system satellite surveying technology. Although NPDES requires pipes 12 inches or greater in diameter to be mapped in the next five years, it was decided that all outfalls in the pilot area would be captured regardless of pipe size. The work also included identifying flow and taking photos of the outfalls. GIS analysts then “scrubbed” the incoming data, correcting any errors. The project helped establish a method for future outfall mapping of the remaining 215-plus miles of streams in Hamilton County. Conclusion John Hannel is a project manager in Woolpert Inc.’s Indianapolis, IN, office.
SW May/June 2006 |
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