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Federal Highway Administration > Publications > Public Roads > Vol. 69 · No. 6 > Following the Flow

May/Jun 2006
Vol. 69 · No. 6

Publication Number: FHWA-HRT-2006-004

Following the Flow

by Norm King, Sam Talje, Michael F. Bloom, Jeff Scarborough

TxDOT's new approach to monitoring highway runoff promises improved compliance with clean water standards.

Here, during a rainstorm, a sport utility vehicle and truck are plowing through rainwater as high as the top of the vehicles' tires.
The Houston, TX, area receives more than 114 centimeters (45 inches) of rain per year, much of it during major storms like the one shown here, flooding a local roadway not operated by TxDOT. TxDOT recently developed a GIS-based system to support the management of stormwater runoff from Texas highways.

State departments of transportation (DOTs) operate drainage systems that include ditches, channels, storm sewers, and culverts to manage stormwater and runoff. In addition to stormwater, these systems can carry pollutants, such as sediment, bacteria, trash, metals, and oils, from road surfaces to natural waterways. Agencies that operate urban stormwater drainage systems need to develop and implement detailed plans for reducing pollutant levels in the runoff they discharge. They also need to obtain permits that detail the requirements included in their plans, mandate annual reporting to the governing regulatory agency, and require documentation of compliance activities.

This inspector is recording information on a small outfall using a tablet computer to record structural and environmental information about the outfall pipe. The white dome in his backpack is the GPS receiver, which uses satellite signals to obtain a fix on the exact location.
This inspector is recording information on a small outfall using a tablet computer to record structural and environmental information about the outfall pipe. The white dome in his backpack is the GPS receiver, which uses satellite signals to obtain a fix on the exact location.

Many transportation agencies rely on hardcopy forms to document compliance with regulations regarding stormwater management. But this approach has limitations. One challenge in particular is producing reliable records demonstrating that stormwater discharge points, known as "outfalls," were inspected frequently enough. (An "outfall" is the point at the end of a stormwater conveyance, such as a pipe or channel, at which the stormwater enters receiving waters, such as a creek.) In addition, physical access to hardcopy forms may be restricted when forms are stored in one site and needed in another. Making phone calls and exchanging hardcopy documents among DOT staff to support both decisionmaking and demonstrations of compliance can be time consuming. Data may be available only in text format, making it difficult to display key information graphically, unless a map is specially produced for the task. These limitations become apparent when the data are required for a compliance audit, when demonstrating compliance may become a cumbersome task.

The Texas Department of Transportation (TxDOT) recently met these challenges by developing an electronic, automated tool that collects, stores, and retrieves information on compliance with stormwater regulations. According to TxDOT officials, the Outfall Tracking System (OTS) will streamline annual reporting, facilitate field survey and inspection work, reduce compliance costs, provide greater access to information on drainage systems, improve distribution and delegation of permit compliance duties, and create a framework for automating and tracking compliance in the future.

"[Although] it took a huge commitment of time and resources upfront to create this powerful tool, TxDOT will reap the benefits for decades," says Dianna Noble, director of the TxDOT Environmental Affairs Division.

For stormwater management and monitoring, moving from hardcopy to electronic records is the trail blazed in Texas.

DOTs as Stormwater System Operators

The burden of proof of compliance, which rests with State DOTs and other entities that release pollutants or are otherwise responsible for managing them, can be traced to the Federal Water Pollution Control Act Amendments of 1972, better known as the Clean Water Act. The act aimed to regulate "point" sources of pollution (for example, sewage treatment plants) entering the Nation's "navigable waters." Subsequent years saw a general expansion of Federal and State regulatory involvement, and in 1987 the U.S. Congress authorized the U.S. Environmental Protection Agency (EPA) to develop and expand the National Pollutant Discharge Elimination System (NPDES) to regulate urban discharges of stormwater pollutants (Section 402).

In the early 1990s, EPA issued Phase I regulations, as they are commonly known, which covered urban centers with populations greater than 100,000. Phase II regulations, issued in 1998 but effective in 2003, added smaller locations within "urbanized areas," as defined by the U.S. Census Bureau. Both sets of regulations require that certain entities, including State DOTs, develop and implement stormwater management programs.

Focusing on Illicit Discharges

In Texas, as in any State, the stormwater management program must be designed to reduce pollutants to the maximum extent practicable as required in the Clean Water Act and its implementing regulations. The program must include (1) public involvement, education, and outreach; (2) construction runoff and postconstruction stormwater management for new development and redevelopment; and (3) good housekeeping, that is, minimizing or eliminating contact between stormwater and onsite pollutants, such as oil used for auto repair.

In addition, any stormwater program must include a component focused on detecting and eliminating illicit discharges, which are nonstormwater discharges that generally contain higher pollutant loads. Examples include drainage from unlicensed commercial carwash operations, leaking sanitary sewers, or improperly plumbed industrial sites.

The illicit discharge program requires periodic field inspections of outfalls during dry weather. Field data must include the outfall location, any physical observations, flow rate, and water quality measurements, if flow is present. Once illicit discharges are identified, additional investigations must track down their sources and, if possible, eliminate them either directly or through third-party actions, such as notifying a State regulatory agency or neighboring municipality. The agency or municipality can then levy appropriate fines or enforcement actions. Illicit discharges can contribute high levels of pollutants that degrade receiving waters. Therefore, regulatory agencies tend to emphasize strict implementation of this portion of a discharger's stormwater management program.

Moving Toward Electronic Tracking

In 2004, TxDOT started updating its approach to managing data, beginning with illicit discharge compliance, as it was the most data intensive of the agency's stormwater programs. Managers of the stormwater program and information technology staff in four TxDOT divisions and districts worked together to develop a model for how outfall data would be collected, stored, and retrieved. TxDOT's Houston and Dallas Districts, along with the Information Systems and Environmental Affairs Divisions, also participated in developing the comprehensive data management tool, which came to be known as OTS (Outfall Tracking System).

OTS is a collection of programs, Web pages, and a relational database with geographic information, also called a "geodatabase." The initial system, largely completed by the summer of 2005, included the following components:

  • A customized field data collector used to gather information during outfall inspections
  • Web pages for collecting and loading data associated with laboratory analysis results, desktop mapping of outfalls, and other sources
  • A statewide relational geodatabase that stores outfall information along with reference information on geographic and other physical features, such as streams, rivers, streets, roads, and geopolitical boundaries
  • A Web-based map viewer that displays, saves, and prints full-color maps with color-coded outfalls (based on classification) along with geographic information
  • Custom, Web-based reporting tools that display and print photographs, documents, sketches, and tabular information on outfalls

As of December 2005, data collection functions were still under development. Although the current OTS only accommodates manual loading of data, TxDOT officials anticipate that the system will be able to upload data electronically by the summer of 2006. Web-based functions for data collection will enable users to upload desktop mapping information, hydrology information, and the results of laboratory analyses. Users also will be able to synchronize outfall inspection results from tablet personal computers (handheld devices that can be carried and used in the field to facilitate collecting data electronically). Users also will be able to create status updates, input descriptive information about an outfall, and create links to scanned documents.

"OTS is so comprehensive because it came about through a collaborative, cooperative effort," says Jim Crisp, an environmental specialist with TxDOT's Dallas District. "This is a tool [that] all TxDOT districts can use to address regulatory compliance needs in a technologically advanced manner. OTS not only provides huge labor savings for us, it is extremely user friendly too."

Outfall Organization

Because the Houston metropolitan area is flat, has relatively impermeable soils, and is subject to intense rain exceeding 114 centimeters (45 inches) per year, local transportation officials sought a high level of detail on stormwater outfalls and the contributing drainage areas.

To capture this information, TxDOT developed an approach to collecting and mapping data on desktop computers that involves the following steps:

  • Collecting "as-built" drawings illustrating the final configuration of constructed drainage infrastructure
  • Digitizing the drawings and positioning them in the proper coordinate system
  • Tracing relevant portions of the drawings so key information on drainage systems can be imported into OTS
  • Documenting tabular supporting information about each object, such as a description of the material, shape, size, and location
  • Loading the information into OTS

Customized desktop mapping tools and procedures support two mapping processes: inside the right-of-way (ROW) mapping and outside ROW mapping. The former captures information about roadway drainage areas discharging stormwater runoff through outfalls. Outside ROW mapping captures information about regional watersheds draining to hydraulic structures, such as culverts, pipes, and channels, at roadway crossings.

System Design

The OTS design architecture developed by TxDOT includes components based on geographic information systems (GIS) and Environmental Systems Research Institute, Inc. (ESRI) software including the following:

  • SQL/Oracle® geodatabase
  • ArcSDE® spatial database engine
  • Web portal for easy information access and retrieval
  • ArcIMS® Internet map server
  • Automated desktop digitization applications for ArcGIS® and MicroStation
  • ArcPad® application for automated field data collection, integrated with a global positioning system (GPS)
  • Tadpole Technology's Go! SyncTM automated geodatabase synchronization from field data collectors
  • Automated reporting for compliance regulations
An inspector records information on an outfall located under a highway overpass. In situations such as this where the overpass blocks transmission of GPS satellite signals, inspectors can define the outfall location by clicking on a detailed aerial photograph of the site displayed in ArcPad on the tablet computer screen.
An inspector records information on an outfall located under a highway overpass. In situations such as this where the overpass blocks transmission of GPS satellite signals, inspectors can define the outfall location by clicking on a detailed aerial photograph of the site displayed in ArcPad on the tablet computer screen.

The relational database contains 42 spatial feature classes, 26 nonspatial tables, 97 tables for choosing domain attributes. The following systems and data are included in the design:

  • Political and organizational boundaries
  • Aerial photography
  • Roadways
  • Topography
  • Land use
  • Floodplains
  • Watershed boundaries
  • Outfalls and contributing drainage areas
  • Crossing points and contributing drainage areas
  • Outfall inspection results
  • Hydrography (streams and rivers)
  • Instruments and calibration records
  • Laboratory results

The map viewer application was developed using ESRI's ArcIMS with ArcMap Server software, ASP, and JavaScriptTM. The Web interface application was developed using ASP.NET and the C# programming language.

The application that collects field data is a customized application of ESRI ArcPad software using Microsoft Visual Basic® scripting. Synchronization is performed using Go! Sync software combined with a Web application for transferring nonspatial data.

"This information is enormously useful in tracing the source of an illicit discharge, one of our most challenging tasks," says Crisp. "ROW mapping also can be called upon in drainage studies and planning efforts."

Peak runoff flow rates at stormwater discharge locations can assist agencies with determining pollutant loads as well as aid in planning and designing drainage systems. TxDOT also is developing a way to collect data on hydrologic values that will use traditional calculations to determine the peak runoff flow rates arising from hypothetical storms. These calculations generally follow TxDOT's design manual procedures. Calculated values will be stored in a simple spreadsheet and then uploaded to OTS and the main geodatabase.

Field Inspection Improved

According to Crisp, one of the most powerful OTS tools is the field data collector, which is a transportable tablet computer that enables inspectors to record inspection results electronically rather than on hardcopy forms. During an outfall inspection, as part of the assessment of whether an illicit discharge may be present or is suspected, field staff members make and record a number of measurements and observations about the outfall. Inspectors typically determine if any flow is present. If so, they record the flow characteristics, such as odor and color, and measure and record water quality parameters using field instruments. Other indicators of an illicit discharge are assessed, such as the presence of foam, staining, distressed vegetation, or deposits.

In addition, field observations confirm the size, material, shape, and other physical factors of the outfall. Field researchers use the tablet PC to record and then document the coordinates of the outfall using digital photos and sketches. After completing the field work, some geographic information may need to be converted to a consistent coordinate system, and the collected data will be uploaded to OTS and then to the main geodatabase.

With the mobile OTS field data collector, TxDOT staff members can enter all this information electronically via simple drop-down menus and point-and-click computer functions. Field staff also may view detailed maps and aerial photographs of the area being surveyed.

"Field survey efficiency is improved dramatically with the easy-to-use functions and the ability to see previously surveyed outfalls, landmarks, roads, streams, and other features in the field," Crisp says.

TxDOT staff who collect data in the field can use the rugged Tablet PC (personal computer), shown here, even in bright direct sunlight. The computer's internal mounting hardware and rubberized corners make it impact resistant. TxDOT staff who collect data in the field can use the rugged Tablet PC (personal computer), shown here, even in bright direct sunlight. The computer's internal mounting hardware and rubberized corners make it impact resistant. Xplore Technologies® Corp.

Intelligent Data Storage

All collected information, whether from field survey work, desktop mapping, or other input methods, is stored in a geodatabase that relates all collected information to objects and features in space. This means that information about a particular outfall is linked to geographic information, including the roadway, receiving stream, county, TxDOT district, land use, and drainage area. Each outfall, in turn, is linked to all of the inspection, hydrology, and desktop mapping results from that outfall.

According to Sonny Lelle, systems analyst/technical project leader for TxDOT's Information Systems Division, the heart of OTS is its approach to storing relational data. "With these linkages, powerful reporting and data visualization tools can be created," Lelle says.

In addition to an intelligent approach to storing relational data, OTS includes custom programming to process data and to populate some geodatabase fields automatically, without user intervention. One of these programs helps Texas stormwater managers decide which outfalls require followup investigations by placing each outfall into one of the following categories of illicit discharges: unlikely, potential, suspect, or obvious.

Artificial intelligence features of the OTS software classify outfalls by considering a combination of visual and physical observations of vegetation conditions, staining, or odors; field-measured water chemistry results; and laboratory-measured water chemistry results. The software program used to make the classification assignments runs overnight and identifies all new outfall inspection results loaded into the geodatabase from the previous day.

"Now stormwater managers can review inspection results within a day to determine which outfalls require followup actions," says Crisp. "That improves the effectiveness of our investigations or third-party notifications."

Better Mapping and Reporting

TxDOT officials report that the logical relationships, geographic information, and artificial intelligence features of OTS make the tool especially useful for reporting and mapping. Users select from an array of views and formats to create the reports needed for compliance and decisionmaking.

OTS can display, print, or save information in a graphic map format or in text-based reports. The map viewer offers an interactive screen that enables users to zoom, pan, and display a variety of geographic information. The map viewer includes access to political and organizational boundaries, aerial photography, roadways, topography, water bodies, floodplains, and land uses, as well as outfalls, crossing points, and contributing drainage areas.

In this screen capture from the desktop mapping tool, the left side shows a map of the major TxDOT roads within the urbanized areas in the Houston District. The right side lists the procedures for mapping outfalls and crossing points. A closeup portion represents an aerial photograph of a highway intersection with the mapping results, including the location of crossing points and outfall points, superimposed upon the photo.
In this screen capture from the desktop mapping tool, the left side shows a map of the major TxDOT roads within the urbanized areas in the Houston District. The right side lists the procedures for mapping outfalls and crossing points. A closeup portion represents an aerial photograph of a highway intersection with the mapping results, including the location of crossing points and outfall points, superimposed upon the photo. Source: PBS&J

Users also may generate maps in Adobe® Portable Document Format (PDF) files, which can be printed, saved, or e-mailed to others. Outfalls that were inspected in the field are automatically color coded, based on inspection findings, to indicate the likelihood that an illicit discharge is present. TxDOT stormwater managers have found the mapping feature to be a valuable tool for planning and prioritizing inspection activities as well as followup investigations to eliminate illicit discharges.

Five standard, text-based report formats are available using the OTS data manager. TxDOT designed the reports, which feature tables of data, to provide stormwater managers with information to support decisions, input into annual reports, and document compliance activities. The reports also can be used to manage and track inspection work performed by contractors and third parties. Standard reports include the following:

  • Outfall Datasheets, which summarize an outfall's physical characteristics, location, mapping and inspection histories, latest inspection results, and hydrologic information to assist with maintenance and followup inspections. These reports, and the Crossing Point Datasheets (below), are text-based and include two small embedded photographs.
  • Crossing Point Datasheets, which provide a summary of a crossing point's physical characteristics, location, mapping history, and hydrologic information to assist with planning and maintenance activities.
  • Outfall Inspection Activity Reports, which detail inspection activities on individual outfalls and indicate the location, date of inspection, inspection type, inspecting organization, discharge status, and status and date to manage contractors and keep track of inspection rates. These and the other reports listed below are text-based and appear in tabular format.
  • Inspection Results Reports, which summarize physical observations recorded at an outfall, such as odor, color, size, and material to support followup investigations to eliminate illicit discharges.
  • Outfall Water Chemistry Reports, which list the chemical constituents (field-measured or laboratory-measured) present in any flow detected from an outfall to support followup investigations to eliminate illicit discharges.
  • Statewide Outfall Summary Reports, which summarize inspection activities statewide and indicate the location, date of inspection, inspection type, inspecting organization, discharge status, and status and date to manage contractors and keep track of inspection rates.

Standard reports have fixed column headings; however, they are designed to enable the user to select the data displayed under them. Users can restrict or sort the data by defining criteria such as date range, geographic area, outfall type, roadway, waterway, investigation status, discharge classification, or size category.

Easy and Secure Access

All TxDOT employees who perform regulatory compliance duties will have access to OTS through the Internet using standard Web browsers such as Microsoft® Internet Explorer.® Various levels of secure access are granted to ensure data integrity and restrict editing, viewing, and copying rights. Distributed access across the organization means more rapid retrieval of needed information. It also means that TxDOT can delegate compliance duties to a broader array of staff using the tool.

In his office, a TxDOT employee using a desktop computer is looking at a map of Texas generated using the OTS application.
TxDOT employees now have full access via desktop computer to a wide spectrum of information on NPDES-permitted outfalls throughout the State.

"With OTS being a Web-based system, we were particularly concerned about security," Lelle says. "For instance, we voiced concerns that the source code could be vulnerable to SQL [structured query language] injection. Effective communication between the Information Systems Division and the contracting staff resolved that concern."

SQL, both a programming language and a specific database used by TxDOT, can be vulnerable to hackers. When protections are not in place, a user or hacker might enter programming commands to delete or modify otherwise secure information.

The current version of OTS allows data editing only with proper login credentials. An updated version, now under development, will add comprehensive data change tracking and reporting. This improvement will facilitate the automatic collection, storage, and retrieval of edited information, including the date of the change, the person making the change, the old record, the new record, and the reason for the change. These features will further enhance stormwater compliance and ensure a high level of data integrity.

This screen shot from the OTS map viewer zeroes in on an aerial photo of a stream crossing beneath I-45 north of Houston. Purple dots represent uninspected stormwater outfalls, and yellow shading represents outfall drainage areas. The OTS map viewer interface includes navigation, printing, and search tools (shown on the left). On the right, layer selection buttons enable users to change the information displayed, and a legend tab identifies the symbols and colors used on the map.
This screen shot from the OTS map viewer zeroes in on an aerial photo of a stream crossing beneath I-45 north of Houston. Purple dots represent uninspected stormwater outfalls, and yellow shading represents outfall drainage areas. The OTS map viewer interface includes navigation, printing, and search tools (shown on the left). On the right, layer selection buttons enable users to change the information displayed, and a legend tab identifies the symbols and colors used on the map.

Looking Ahead

As of December 2005, the first version of OTS is complete and available to TxDOT staff via a secure Web server. The electronic field data collector is undergoing pilot testing in the Dallas and Houston Districts, and desktop mapping is underway in Houston. Automatic upload functions for hydrologic data, mapping information, and field inspection results will be finalized during the spring and summer of 2006.

Once construction is complete, new outfalls like the one shown here for an overpass on the Westpark Tollway outside of Houston can readily be incorporated into TxDOT's OTS.
Once construction is complete, new outfalls like the one shown here for an overpass on the Westpark Tollway outside of Houston can readily be incorporated into TxDOT's OTS.

Planning is underway for an expanded set of tools for tracking compliance to better manage information associated with other programs that address stormwater quality, namely public education, public involvement, construction, runoff controls, new development, good housekeeping, and representative monitoring.

TxDOT officials look forward to implementing these additional data management technologies to further streamline compliance with stormwater quality regulations and reduce costs. These features will enhance the State's automated collection, storage, and retrieval tool that already facilitates accurate inspection surveys and reporting, improves data accuracy and access, and simplifies compliance reporting.

This map of Texas shows the location of major roadways maintained by TxDOT, plus rivers, streams, and urbanized areas. Roadways within the shaded urbanized areas are subject to stormwater regulations and must be surveyed using the OTS field data collector.
TxDOT maintains more than 79,000 centerline miles of roadway in the State. Agency officials are pilot testing the OTS in the Dallas and Houston Districts, with statewide rollout in other urban areas to follow.

Norm King is the manager of TxDOT's Ecological Resources Management Branch, Environmental Affairs Division, in Austin. He may be reached at 512-416-2319 or nking@dot.state.tx.us.

Sam Talje, P.E., is the director of hydraulic design, surveying, and mapping at the TxDOT Houston District. He may be reached at 713-802-5653 or stalje@dot.state.tx.us.

Michael F. Bloom, P.E., CFM, DEE is an associate in the Water Resources Program of PBS&J's Houston office. He assists governmental entities in complying with the Clean Water Act. He may be reached at 281-529-4202 or mfbloom@pbsj.com.

Jeff Scarborough is a program manager in the Information Solutions group of PBS&J's Houston office. He may be reached at 281-529-4240 or jlscarborough@pbsj.com.

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