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Additional Article Content

• Counting the Small Stuff

When it comes to addressing stormwater management problems and dealing with the permitting process of the National Pollutant Discharge Elimination System (NPDES), stormwater managers and hydrologists have more tools in the toolbox these days than ever before. Software programs can help municipal managers with hydrologic/hydraulic modeling, and new technologies are available for water-quality monitoring and pipe inspection.

While such tools come at a cost, those who work in stormwater management say they derive a return on the investment through the confidence the technology gives them to make predictive statements about flooding and accurately plan for future capital improvement projects.

Austin’s Flood Early Warning System
Case in point: Austin, TX, which has been given the moniker “Flash Flood Alley.” The city’s annual rainfall is about 40 inches. However, as Susan Janek notes, “We have some extreme rises in the watersheds when it rains and have had deaths in some of these watersheds, particularly in some of our urban watersheds. We have had people literally swept downstream.” Janek is an engineer with the Watershed Engineering Division of the city’s Watershed Protection and Development Review Department.

Mitigating those flooding problems was a major impetus for adopting a Vieux software system, Janek says. Vieux provides products for rainfall monitoring as well as for hydrologic modeling and analysis.

Austin, an NPDES Phase I community, invested in RainVieux and Vflo technology in 2004 to develop and manage its Flood Early Warning System by obtaining more accurate information about the region’s rainfall patterns. RainVieux uses both radar data and rain gauge data to provide more accurate rainfall estimates, and that information can be input into the distributed hydrological model Vflo.

“It’s extremely useful from a modeling perspective,” says Janek. “We have hazard areas in Austin. We have known in the past about areas in Austin neighborhoods that will need to be evacuated due to flooding, and there’s not a lot of time to mobilize forces to get people out. Investing in this technology helps provide us with the time tool to make us better forecasters and be more responsive first responders.”

The technology merges Doppler information with that from the gauge network and re-aggregates it over a square kilometer, creating hydrographs.

Based on a previous experience in which a radar site went down during a severe weather event, Austin has since added redundant radar feeds, so that if one radar site goes down, the RainVieux technology will shift to another, Janek adds.

Austin also uses a feature that attaches a flood threat level number to each of the sub-basins in the watershed.

“If we have been using information on our rainfall frequency that’s been reestablished by the United States Geological Survey [USGS], we can very easily obtain a threat number on a
watershed based upon the average rainfall a basin has received over a set period of time. That’s a useful tool for us from a flood warning standpoint,” says Janek.

That information is used to help pull up maps that may show, for example, a watershed with a threat level of 3, enabling Austin officials to determine which areas are flooded, which roads should be closed, who may need to be evacuated, and what the approximate floodplain boundary might be for a threat level of 3, 4, or 5.

Janek says Vflo has proven to be “very stable” and has worked well in the environment to which it is applied. “We’ve developed models in association with Vieux for a good number of our watersheds,” she says. “Prior to doing this, we entered into agreements with the USGS for the construction, maintenance, and development of a full range of rating curves for 28 USGS gauging stations on our urban watersheds.

“We use those as forecast points for the Vflo model. What the Vflo model can do is, as we have a storm progressing, every 15 minutes it will give us a new forecast on a particular forecast point. Our models are calibrated, and they track very closely to the USGS gauge readings.”

For some of the area’s watersheds, flood-warning time has been improved by as much as an hour. For some larger watersheds—where the potential for evacuation has been substantial—forecasting time can be improved by as much as four hours.

“That’s pretty phenomenal for us to be able to do that,” says Janek.

The models run continuously on an Internet site hosted by Vieux. “They’ve created a visual interface on their Web site,” she says. “If we get a storm, we have a watch or warning level based upon this predicted model. It will visually alert us or page us when we have a problem we need to address. That’s tremendous for us, because that does a lot in terms of us getting advanced warning out on something we feel confident about. It’s one thing to issue an advanced warning; it’s another thing to have some confidence in that forecast.”

Austin has rain and stream-level sensors that provide information on what’s occurring at any particular point in time.

“The predictive models can help us identify the future threat, which is what the warning time is all about,” says Janek. “We’ve been running the models in our urban watersheds continuously, and we found that in the urban watersheds, they track very consistently with the USGS gauges over time, so that provides us a level of confidence in those models. If we get a forecast, we’ll believe that forecast.”

Austin also is working with Vflo forecast information in conjunction with Federal Emergency Management Agency (FEMA) floodplain maps to get them digitally and spatially oriented, says Janek. “We’re taking the output we get from that model and are developing predictive floodplain maps from those,” she adds. “We are able to create a surface of the floodplain from the Vflo model and do an assessment of our roadways or areas that frequently flood.

“For instance, we’ll know in advance if we have a particular roadway that will be inundated, or if we have an area that will need to be evacuated,” continues Janek. “We are working toward getting that
citywide.”

The system has helped Austin in future stormwater management designs by providing physical data, says Janek. “To have the distributed rainfall—where it falls within the watershed, how intense and how long—determines a lot of what our flooding situation will look like and how much warning time we have—and how well our infrastructure behaves,” she adds.

The Vieux systems have helped Austin save time, Janek points out. “One of the nice features about them is that we can create, modify, and evaluate these models over time,” she notes. “Every time you develop a model, there will typically be times you need to go back and recalibrate it based upon additional information that you receive.”

The learning curve for the Vieux systems is fairly simple, she says. “It’s intuitive. It does take a fair amount of effort for the development of the Vflo models and the calibration over time. That is a little bit more intensive. It is something the Vieux folks will work with us on, so it’s certainly not an insurmountable task.

“In Austin, we’ve been fortunate in that we are utilizing a lot of the work that has already been done—whether it’s been done by FEMA, or through all of the historical information we have, or through our gauging network. We have a lot of the pieces that are already created, so we are taking advantage of them.”

Planning Capital Improvements in Fort Worth
To the north of Austin, Fort Worth, TX, also has a reputation for flash flooding. Fort Worth has an area of 300 square miles and an annual rainfall of about 36 inches.

“Typically, our heaviest rainy seasons are in the spring,” says Steve Eubanks, a senior professional engineer in charge of stormwater planning for Fort Worth, an NPDES Phase I community.

“We can get about 20 to 25 inches in the course of two or three months,” adds Eubanks. “Typically, we have wet springs every three years or so. It seems, lately, like it’s been two dry years and a wet year, two dry years and a very wet year.” Consequently, the city has had to deal with a lot of flash flooding as a result of spring and summer thunderstorms.

“And we have a very old drainage system,” adds Eubanks. “The city did not even adopt any kind of drainage standards until 1967, and it was 1987 before we had a 100-year design standard on our storm drain systems. So we have a lot of grossly undersized storm drains.”

The city originally tried to model some of the systems using the EPA’s Storm Water Management Model (SWMM5). “I worked with a group of consultants, and we started with some of our worst watersheds and went through quite a bit of work to get these SWMM5 models,” says Eubanks.

One of the consultants attended a users’ conference for Wallingford Software, which develops products for water resource management, and came back impressed.

“We had looked at other software from time to time, and ultimately we decided that, if we were going to be able to model these storm drain systems, we needed not only to be able to have something that would really tell us where the overland flow is, but also something that would provide us with a variety of solutions, since we didn’t really have the budget to come in watershed after watershed and start over from scratch,” says Eubanks.

Fort Worth now uses Wallingford’s InfoWorks SD for its storm drain system and InfoNet for asset management.

One of the issues in Fort Worth is that in the early part of the last century, the city’s development policy included filling in creeks with pipe and paving them over. In many cases, the pipes don’t have the capacity to handle flow from a one- or two-year storm.

“When the pipes fill up, the only overland flow path is between houses and through houses,” says Eubanks. “We have 29 storm drain systems that drain over 300 acres each, and our largest one is a single storm drain system draining about 900 acres.”

“The capacity problems are really severe,” he adds. “In some of our heavier storms, we have water 5 feet deep running not down the street, but running the street, so properties on one side are getting flooded, and properties on the other side are getting flooded.”

Some 300 homes and businesses were flooded during storms in 2004.

“They were all due to the thunderstorm-type flooding; it wasn’t due to river flooding at all,” notes Eubanks. “In fact, most of the flooding that we have is not even in a mapped FEMA floodplain because it is on the smaller storm drain lines.”

Because of the extensive flooding, Fort Worth launched a stormwater utility with an emphasis on raising money for numerous capital projects to bring the storm drain systems up to date.

“At that time, we had estimated about a $550-million backlog,” says Eubanks. “We’ve done quite a bit of work since then, and we think we have about a billion-dollar backlog now. As a result of all these planning studies that we are doing and intend to do in the future, we’ll have a better handle on that number.

“We can’t just go into one neighborhood that says the flooding is real bad and spend $50 million dollars without considering the fact that there are maybe two or three other neighborhoods that aren’t going to be able to get fixed because of the high price of that one,” he adds.

InfoWorks SD offers Fort Worth the opportunity to look at flooding patterns throughout all neighborhoods and track the most severe flooding, so the city is not merely depending upon citizens who call the most to determine where the worst flooding is, says Eubanks. The software will enable city officials to document the number of homes flooded and obtain reliable cost/benefit information.

“Because of the way the Wallingford software works, we can actually track the overland flow through a neighborhood and determine all the properties that are going to be impacted by it,” says Eubanks.

“We are now in the process of looking at some alternatives and at two of our worst watersheds,” he says. “We’re going to be looking at deep detention. Everything now in our system is all gravity, so if we adopt deep detention with pumps, it changes the way we look at maintenance.”

The city also is considering tunneling and traditional open-cut solutions. Any open-cut solution would include property buyouts.

“We’re not talking about 4- to 6-foot-diameter pipes. We’re talking, for example, of a double 6-by-6 box as a relief pipe, where we might have a 48-inch pipe now,” says Eubanks. “We have a lot of really large deficiencies, and as we’re going to use the Wallingford modeling over the next 10 years, trying to map the flooding in most of our larger storm drains, we’ll also be able to use it to determine the best kind of solution that will alleviate most of the flooding.”

That may involve a phased solution that entails improvements in a bad area upstream done in such a way that does not create worse flooding downstream. “Only in having a real reliable hydraulic model will we have confidence that we can look at these various solutions, and that they will give us an accurate depiction of what kind of improvements we need to make and what’s going to be our best course of action,” says Eubanks.

Fort Worth has an engineer on staff, Amy Cannon, who is becoming an expert at using the Wallingford software, says Eubanks.

“She was really surprised at how quickly it went to build the first model,” he says. “Now she’s spending a lot of time tweaking it to get it to run better, but she’s really satisfied with the capabilities it’s giving her to look at the problems with this system.”

As Fort Worth develops the models, it will undertake projects such as retrofits, redevelopment, and land use changes, says Eubanks.

“It will provide us with the tools so that, over the next 30 to 40 years, we’ll be able to line up the capital work that needs to be done and identify the most critical projects,” says Eubanks. “We will continue to calibrate it. We will be able to say we will need additional improvements in the neighborhood that we were only able to spend $15 million in at one point.

“It gives us a lot of confidence that we will actually have something that will give us continual information on how our system is going to respond.”        

Until recently, the city had only a few sets of schematic maps, with the most recent being from 1992. Since bringing Wallingford Software on board during autumn 2008, the goal has been to do a complete mapping of the city’s entire storm drain system.

“This is one of the initiatives our stormwater utility kicked off in 2006,” says Eubanks. “We are going to run all of the models through InfoNet as part of the GIS [geographic information system] mapping. InfoNet will give us a lot of tools for diagnosing our system.

“One of the things it can do is create a profile of a storm drain system, so you can instantly see if you had an invert elevation that was entered incorrectly and the pipe goes up 15 feet before it goes back down again,” says Eubanks. “We know that doesn’t happen. By running everything through InfoNet, it will help us get the most of our system model ready. Then we can hire the consultants to go back through and evaluate each of the watersheds as it comes up in our budget priority and develop projects around existing flooding: How many homes are affected, and what’s going to be the range of cost and solutions to fix this?”

Eubanks says Wallingford Software has saved Fort Worth both time and money. “We’d always heard it’s the Cadillac of modeling software, and it costs us quite a bit. But because we are dealing with several hundred million dollars of capital improvements, and they’re all going to be complex because they are storm drains through developed areas that follow the old terrain which has nothing to do with the street grid, we think we are going to recoup our investment in Wallingford probably within the first project or two,” says Eubanks. “We are looking at spending tens of millions of dollars on some of these projects.

“Obviously, having confidence that our models are reliable is important,” he adds. “We have to make sure we’re not spending $25 million dollars on a project, but at the end of it we’ve still got a flooding situation because the modeling was not that reliable. We do have a lot of confidence in what Wallingford is giving us.”

Real-Time Data and Better Modeling in Kentucky
The more sophisticated data a stormwater manager can obtain, the more helpful it is in future stormwater system planning.

To that end, the Louisville/Jefferson County (Kentucky) Metropolitan Sewer District (MSD) has used OneRain technology for several years. The system provides Web and local visualization services, radar rainfall estimation, rain gauges, real-time satellite telemetry, telemetry system integration, and storm properties analysis.

Annual rainfall averages 44 inches in the county, a Phase I community, which measures 400 square miles. The district’s service area covers 90% of that area, with the remaining areas still not served by sewers, says Justin Gray, a senior technical services engineer with the Louisville/Jefferson Kentucky MSD.

The OneRain data has been useful in helping the district in planning its response to a consent decree to mitigate all combined sewer overflows (CSOs) and sanitary sewer overflows (SSOs) through an $800-million capital improvement project, Gray says.

“From a planning perspective, it’s helped save money, because it gives us better-calibrated models and better distribution of how our rainfall events actually occur within our county, which, ultimately, makes our planning process for sizing of detention basins, underground storage basins, or treatment facilities more credible,” he says.

“The better you know how your rainfall normally occurs in the county, the better your planning projects are going to be down the road,” adds Gray. “Operationally, it saves time, because you can target areas that are being hit the hardest rather than waiting for customers to call in and tell you that their basements are backing up. We can see areas that received 5 inches of rainfall in two hours, so we can direct crews out to that area to look for problems. You can be proactive, and you’re not spread as thin.”

Historically, the district has partnered with the USGS, which for years has maintained stream gauges throughout the county. “The OneRain products helped us utilize that [stream gauge information] in a real-time fashion more effectively through our own system,” says Gray.

He notes that a significant portion of the district’s system is a combined sewer system that conveys both sanitary and stormwater flows to its largest wastewater treatment plant. The combined lines are large, with the largest being 27 feet by 18 feet.

“During any given wet-weather event we have, depending on its pattern, we could have storage capabilities in portions of the line that aren’t experiencing the heaviest rainfall,” says Gray. “So we put in control points, almost like a traffic system, where we can raise or lower gates to store water in pipes.”

To assist in that matter, the district uses OneRain’s predictive gauge-adjusted radar rainfall estimates. “We use the two-hour predictive rainfall estimate and run it through the hydraulic model that monitors the current state of the system,” says Gray. “It looks at the predictive rainfall amounts that are incoming and sets the set points of our controls at about eight different places.”

The Louisville/Jefferson Kentucky MSD recently got online with Contrail Web, a site that allows district officials to access a map showing predictive rainfalls four hours out for the region.

“It also reflects our rainfall gauge distribution,” says Gray. “We have about 16 within the county, and we can access rainfall gauge data directly from that site. We can download data for any time period and export it into any format and do whatever we want with it from that point.”

The ability to see the pattern of incoming rainfall and where it is the heaviest has made operations more effective, Gray says.

The OneRain technology also is enabling the district to reflect data from USGS stream gauges, of which there are 28 throughout the county.

“They have an agreement with USGS, and they directly reflect the real-time USGS data so we can see the stream stage and velocities,” says Gray, adding that the system can be customized to send out an alarm when a specific stream gauge reaches a certain level.

The district also goes beyond the use of rain gauge and stream gauge data to analyze radar rainfall data to help get a more detailed look at rainfall distribution during a rainfall event.

“We use it for historical event analysis, and we also use it for our sewer modeling, to calibrate a rainfall event,” says Gray. “We can take the radar data for a storm event for which we’ve also recorded the level of some of the sewers throughout our system, and we can calibrate our model to reflect those levels during particular events. We use those models for planning purposes, for overflow abatement operational modifications.”

The learning curve on the system is relatively quick, says Gray. “It’s Web-based, and most everyone is familiar enough with the Web tools that they’ve made available,” says Gray. “It’s very straightforward to review incoming rainfall and to actually get the raw data and export it out to a separate program.

“We’re still getting our heads around how to best monitor different points throughout the system, using their site, to give us a full warning of things we might be concerned about,” says Gray. “But their product has proven to be useful and I think we will find it much more so as we move forward.”

Following the Terrain in New Jersey
With a population of 5,613, Watchung, NJ, is a small municipality located 23 miles southwest of New York City, NY.

“Regardless, we are still charged to provide the best service possible for the taxpayer,” says Charles Gunther, the principal public works manager for Watchung, a municipality with the Phase II, Tier A municipal stormwater general permit.

Watchung had always been in the “dark ages” with respect to stormwater system mapping, notes Gunther. The 5-square-mile town has a small stormwater system consisting of about 100 outflows and about 1,000 catch basins. But addressing problems was a matter of guesswork.

“Geographically, we have many hills, and the stormwater system we have is very dynamic and doesn’t necessarily follow the topographical contour of the roads,” says Gunther. “It’s very helpful for us to map out our stormwater structures and our system for the simple process of maintenance, and also getting an understanding of which catch basins are tied to which outflow. It’s useful not only from a regulatory standpoint, but also from an emergency management standpoint.”

Gunther also serves in the office of emergency management for the community. Having information about the stormwater system is a valuable in predicting what type of environmental problems could be caused by a severe storm.

Photo: City of Tampa The City of Tampa truck with closed-circuit television inspection equipment

“We are in a valley where we have two bodies of water—Watchung Lake and Best Lake, which intersects our community and ultimately discharges into Stony Brook,” explains Gunther. “Stony Brook’s receiving water is the Raritan Basin.”

Watchung has been able to streamline its stormwater operations through the use of VUEWorks Storm, an integrated GIS asset and work management software tool. Storm interfaces with VUEWorks Core to provide asset management for storm drain systems. For example, flow arrows assist emergency crews in intercepting a contaminated spill before it reaches sensitive areas. The software can also assist with tracking stormwater quality in pipes, managing watershed master plans, and planning for capital improvement projects.

VUEWorks has helped the community develop an equitable system for service calls and work orders so that employees have more well-defined work assignments, says Gunther.

“I can’t express how much our productivity level has increased by virtue of having something tangible,” he says. “It allows me to organize my work, prioritize my jobs, and put things on the backburner that need to go there.”

While Gunther found the initial learning curve to be “a little awkward,” he says it does have a “logical progression.” He notes, “It took me about a month to get used to it, but after that, I became proficient at it.”

Now he is using VUEWorks to tie in GIS information with stormwater system design. “When we have new road improvement projects and are introducing more catch basins into our system, we can archive the documentation showing how old the systems are, how old the catch basins are, and if we have any key catch basins in the community that are troublesome,” says Gunther.

Because of the hilly nature of the community’s terrain, a great deal of surface debris accumulates in low-lying areas, says Gunther.

“I did not have the ability to record the troublesome basin areas and the culvert areas and develop a work order system for an anticipated rain event,” he says. “I can now send my crews out and tell them which catch basins I want them to locate, rather than just sending them out on patrol, because there was a lot of wasted time.”

VUEWorks has also played a critical role in documentation for disputes.

“We had a tort liability claim from a resident who claimed that we failed to maintain our stormwater system, which caused water to be discharged into his home,” says Gunther. “Fortunately for me, I was able to have that [maintenance] documentation. All that stuff is archived: the time that the assignment was given out, who did the assignment, who cleaned that catch basin. It also gives us a record, historically, of how often those troublesome areas are being addressed.”

Gunther lauds VUEWorks for its ability to tailor itself to the size of a community and its level of service.

“I’m only maintaining a small stormwater system of 1,000 catch basins, but it sure does simplify things,” he says. “Also, as the work orders that are given out, we can attach certain documentation—even photos of work that the foreman may be doing with his crew—to document damage and deterioration. He can make notations, include before and after photographs, and that is all being archived so that I can express that to a councilman.

Photo: City of Tampa Preparing to inspect stormwater pipes with CCTV equipment.

“We can point and click on a location in town, click on that catch basin, and it will open up the history of that specific catch basin along with pictures and any other type of narrative,” says Gunther.

Gunther says the VUEWorks technology also is helping with documentation for state environmental protection inspections. Mapping of the stormwater system is about 95% complete.

“The public does not realize what goes into a stormwater maintenance system, especially in a town where there are hills just about everywhere,” says Gunther.

Inspecting Pipes in Tampa
In Tampa, FL, it was a long-established practice to use underground televising equipment to inspect sewer pipes. Three years ago, the city’s stormwater managers decided it would be useful to use that equipment to inspect and catalog the stormwater system as well.

Photo: City of Tampa The Steerable Pipe Ranger after an inspection

“The sewer department has been cataloging its systems and their condition for years, and the only time we asked to have the stormwater pipes done is if there was a problem,” says Gary Mays, a stormwater TV inspection specialist.

Because the city’s wastewater department already has five CUES trucks, the stormwater department elected to go with CUES as well. CUES manufactures closed-circuit television video inspection equipment.

Mays’ job is conducted from an E450 Ford van with a “crackerbox” rear end that houses a CUES OZII optical zoom pan-and-tilt camera system. The camera features directional lighting for 6-inch to 72-inch pipe, remotely activated light for use in black pipes, auxiliary lighting for 84- to 200-inch-diameter pipes, and a 40:1 optical/digital zoom feature. The system also includes a Steerable Pipe Ranger drive unit that easily offers Mays the ability to steer the unit into a pipe or box. “Otherwise, we are just riding walls, and we take a chance of flipping the camera,” he says.

Mays says that in addition to cataloging the stormwater system, Tampa’s stormwater department aims to use the CUES system for preventative maintenance to identify potential problems before they erupt.

He says the system has helped Tampa stormwater officials confirm that the pipe sizes that are in the ground—and their condition—are appropriate to handle the region’s weather events.

“If you are building a new system, you definitely have to have a system that can accommodate [the storms],” he adds. “We are assisting with design.”

Tampa had previously used a smaller underground televising system to locate clogs and cave-ins before purchasing the CUES camera. “It was fairly successful—that’s why we went with a larger full-blown system. As far as the ease of the system, running the cameras is very simple, but I didn’t come from a computer background, so the most difficult part was learning the software,” he says.

“But it’s very repetitive,” he adds. “It’s not a difficult, demanding system. Once I learned it, I was able to locate anything. It’s actually very simple once you get into it.”

Televising Tampa’s storm pipes has yielded some surprises, Mays says. “We’ll just be tooling along, and all of a sudden there will be a very old section where a lot of the drainage is 75 years old or more. We tend to run into some systems that are aging, and we are having some small problems. But we’ve come to find out, especially in the stormwater area, the systems were actually built quite well.

“The larger boxes are all hand-formed, poured-in-place, and it’s pretty impressive workmanship,” says Mays. “We had one system that has to be somewhere in the neighborhood of probably 100 years old that’s all red brick with an arched ceiling. It’s very impressive.”

Some of the challenges with which Tampa is dealing center on NPDES permitting.

“We are trying to install new systems that remove as much of the trash and debris as possible,” says Mays. “We are installing sumps and systems that allow the clearing of yard debris and so forth that get in the system. We are attempting to build more retention ponds.

“But in Tampa, like so many other coastal communities, most of our drainage goes straight into bays or the river. Our biggest challenge is trying to control the debris that goes directly into our waterways and our drinking water.”

Education is a key component in taking the information gained from the underground inspections and sharing it with the public. Mays teaches courses on stormwater at a local technical school, where he explains NPDES permits and best management practices.

He also takes the CUES truck to local elementary schools for the annual Great American Teach-In, which opens classrooms to volunteers who talk to schoolchildren about what they do.

“There’s always an elementary school that requests this truck, so I get to show elementary school kids the video equipment,” says Mays. “I drive the Steerable Pipe Ranger in the yard near classrooms as the kids are walking up. They’re all thinking, ‘What kind of weird thing is looking at me here?’ It’s a fun piece of equipment.”