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Automatic and manual systems to measure the health of the watershed By Carol Brzozowski Eric Gurr likens his job of water-quality monitoring in central Florida to that of a surgeon, with his tools and techniques used to identify the maladies and take corrective actions. Like his counterparts throughout the planet, Gurr’s concern is twofold: to protect the environment for the local citizenry as well as save citizens the costly expense of rectifying the sins of the past or the negative impact of the work of nature. There are a number of reasons why those in Gurr’s camp are adding more tools to their arsenal in the battle to improve water quality: National Pollutant Discharge Elimination System (NPDES) permit requirements, aquatic habitat restoration, post-construction pollution concerns, total maximum daily load (TMDL) levels, 303(d) monitoring for impaired waters, agricultural runoff, and high fecal coliform levels. The complexity of monitoring for so many different parameters requires more sophisticated monitoring equipment. Gurr is the stormwater utility manager for Kissimmee, FL. When he took on his job more than two years ago, he made it a priority to execute a stormwater model. The state established stormwater-quality criteria through its Florida Watershed Restoration Act in 1999, setting TMDL levels for impaired bodies of water throughout the state. The TMDLs were incorporated into NPDES and managed for the USEPA by the Florida Department of Environmental Protection (FDEP). Gurr was particularly concerned about being proactive on TMDLs—given the potential for the EPA to overestimate pollutant loads and the estimated $100 million price tag associated with meeting TMDL criteria—and wanted an aggressive monitoring program in place to improve upon the city’s tradition of hiring consultants to prepare master drainage studies. To boot, three hurricanes had passed through the area in recent years, resulting in concerns about flooding and water quality. Part of the city’s livelihood is tied into its being one of the world’s renowned bass fishing destinations. Many of the area’s water bodies discharge directly into Lake Tohopekaliga. That lake, among other water bodies in the state, has been monitored by the FDEP as well as the city, which sought to assess its allocation of pollutant loads for the Basin Management Action Plan slated to begin in June. The plan establishes corrective measures. Doing the stormwater monitoring and developing a model go hand in hand, Gurr says. By developing a model, the city will know what’s needed to meet the state’s criteria. The city can reduce the costs to meet those criteria and will continue to assess the effectiveness of corrective measures that are slated to be in place in June 2007 as the state’s final program phase. “My goal for screening is doing the model; the whole point is to identify what’s going on,” Gurr says. “A lot of people are sitting back right now and saying they’ll see what happens. What happens is if you don’t get proactive, you won’t find out where the constituents are coming from.” The city uses YSI’s EcoNet technology—including data upload onto the city’s Web site—as well as DHI Software’s ECO Lab, MIKE SHE, and MIKE 11 for hydrological modeling. There are 20 monitoring locations citywide, and monitoring is performed continuously—triggered by rainfall—as well as through handheld grab samples. “It’s a great model,” Gurr says of the software. “This monitors the actual constituents as they flow down in the model—it’s like a spreadsheet analysis coming out of it that allows you to interact with the constituents as they flow down for any time set as it mixes and disperses.” Gurr uses the model to create a whole-flow picture. The city also installed precast concrete U-channels to help adjust minimum water levels so flow data can be obtained even in dry periods.
“We need at least 9 to 12 inches of flow for proper measurements in shallow water for depth velocity, so we had to increase the volume in the channels to make sure we had that depth flow,” Gurr says. Using water-quality monitoring tools is like performing a surgical procedure, he says. “You have the TMDL, and you don’t have a lot of options, because you don’t know where they [the constituents] are coming from,” he says. “Our analysis is an examination to find out where the highest concentrations of pollutants are, and, like a surgeon with a scalpel, cut out them out with extensive BMPs in those areas—whatever I can do to keep the sediment load out of the areas.” An Extreme Case On a day-to-day basis, the Louisiana Department of Environmental Quality’s (DEQ’s) routine ambient water-quality monitoring network collects a host of parameters at subsegments throughout the state. Monitoring includes field parameters generated by using a meter in the field, as well as laboratory samples.
As Chris Piehler, a senior environmental scientist with the Louisiana DEQ, describes, “We collect a little water and bring it back to the lab. Our analyses can be for both the conventional water-quality parameters like nutrients, hardness, alkalinity, and others, as well as for very specific compounds and elements, such as metals. We also do volatile organics routinely, and in some areas do acid and base neutral extractables, as well as bacteria sampling.” The Louisiana DEQ sets up a schedule at the beginning of each year for the ambient water-quality network. “We’re not doing any event-based monitoring. We’re just trying to capture ambient conditions as they may occur in any given time throughout the year,” says Piehler. Many of the state’s stormwater discharge permits include specific conditions regarding first flush, generally within the first 30 minutes of certain-sized rainfall. “In those cases when we are dealing with a compliance situation—or if we were to receive a complaint that there may be something associated with a given pollution input as a result of a nonpoint- or stormwater-related event—then we would also be gauging our response to try to capture that first flush,” Piehler says. The state uses Hach Environmental’s Hydrolab water monitoring instruments. “We use both profilers and continuous monitors. The data from the continuous monitors are usually downloaded to a laptop and then forwarded through e-mail to persons handling the data for database entry,” says Piehler. The state has some nonpoint-source projects for which it contracts the work, such as a determination of turbidity relative to a rainfall event, with the sample information gathered by a flow meter. “Although we are aware of methods of integrating our data collection, it hasn’t been necessary for us to do that on a routine basis,” says Piehler. “There’s an expense involved with added equipment that we probably wouldn’t use very often with our processes. But these contract efforts are tailored to a specific watershed.” Piehler says Louisiana’s governor has asked the DEQ to develop a plan to reduce the number of impaired water bodies to 25% by the year 2012. The state currently has impairments in 60% to 70% of its sub-segments. The biggest issue is fish and wildlife propagation, Piehler says, “primarily because of dissolved oxygen and then nutrient levels.” The DEQ is still in discussion with the EPA over what is a naturally occurring low dissolved oxygen versus oxygen that is low because of pollution. While the state’s day-to-day operations don’t center on event-based monitoring, one event was inescapable: Hurricane Katrina. Piehler says there never was such a thing as the “toxic soup” widely touted in the media following the storm event. “The storm surge from Lake Pontchartrain and the marshes of St. Bernard Parish overtopped and broke through levees, flooding areas normally protected by flood protection levees,” Piehler explains. Because of the area’s topography, the water had to be pumped off to be removed. “There was a great deal of concern about this ‘toxic soup,’ and we suspected, but had to demonstrate, that these floodwaters in the greater New Orleans area and were no different than [those in] any municipality that floods,” Piehler says. The only difference was that the water had to be actively removed. “Because it stayed there, it stagnated,” he says. “It was hot, it stunk, and there was a lot of sewerage associated with it. It looked bad and smelled bad.” Thus, the DEQ conducted extensive water-quality monitoring of the floodwaters as they were in place and as they were pumped off into the receiving waters of Lake Pontchartrain, as well as of the lake itself and its surrounding estuaries. The DEQ applied its normal routine ambient water-quality monitoring techniques, selecting sites that would be representative and doing so on a schedule that officials figured would capture the needed information. The department used handheld equipment to capture the information. The first floodwaters were collected on September 3, 2005. The DEQ continued to assess the ambient condition of surrounding estuaries around the lake for a few more months while some other areas required additional scrutiny on top of the department’s routine ambient water-quality monitoring network. Piehler says the DEQ did not find any chemical contamination of concern. “We expected to see trace levels of components used in household hazardous materials—disinfectants like phenol,” he says. “We saw low levels of the old banned pesticides that have been discontinued since the 1960s or 1970s.” The DEQ also found metals typically associated with stormwater in any highly populated urban area, such as lead and arsenic, the latter of which is found in native soils throughout the US. Practical Questions Harmel is an agricultural engineer with the USDA Agricultural Research Service (ARS). In his work he utilizes Teledyne Isco’s 6700 series water monitoring equipment. Harmel was inspired to do equipment testing after he started with ARS seven years ago and worked on many projects involving stormwater-quality monitoring from agricultural watersheds. “We were surprised and disappointed at the lack of practical information on how to set them up,” Harmel says of the monitoring systems. “They could help us with what button to push to program it the way we wanted, but there wasn’t any information on how high was the system trigger level and what size storm you want to monitor.” Harmel and his colleagues did not know if they had to take hourly samples or how many cubic feet of flow was needed—“all those practical questions,” he notes. “We thought we’d monitor the water quality but then do some research to answer some of these questions so everybody else didn’t have to go through the school of hard knocks to answer them,” he says. Thus, present research is focused not only on monitoring water quality but also on establishing protocols and guidelines for small watershed monitoring. The water-quality research taps into all segments: permit requirements, aquatic habitat restoration, construction runoff, and 303(d)-listed impaired areas. The 303(d) research is the most predominant. The team also wants to get a sense of the impact of agricultural land uses, predominately involving organic fertilizers. The team is looking at nitrogen and phosphorous in dissolved and sediment-bound forms. “We’re trying to establish a database of water quality and all the other supporting data management—economics, rainfall, runoff,” Harmel says. “Modeling has been the main use so far, so that folks who are modeling transport of nutrients can have a good database to start with. Getting good data sets is the big hurdle they face in their modeling programs.” Harmel’s team has a continuous automatic sampling system set up, triggered by the amount of flow to the structure. The water-quality and flow data are not transferred remotely but are manually retrieved. Harmel says the USDA team has not had to send people with handheld samplers to sites because of a reliance on the automated equipment. “We put a big emphasis on maintenance and troubleshooting beforehand; we haven’t had trouble with automated samplers not working,” he says. One of the aspects Harmel favors about the project is that it’s in one of the original ARS watersheds, “so we’ve got continuous flow and rainfall data from the late 1930s. It’s one of the longest data sets available. Not so much on water quality, because that’s a newer issue, but on hydrology, soil loss, and rainfall, we’ve got data since 1937 and 1938,” he says. “We’re very proud of that data set, and now we are tying in issues of nutrient transport and sampling on that site.” Because of the data history, the USDA-ARS is able to analyze changes in climate and management practices in a way that data sets of only five or 10 years don’t lend themselves to as well, Harmel points out. As for the equipment testing itself, Harmel says it’s not intended to monitor the equipment per se—his agency is pleased with the equipment’s performance—but is looking to answer questions such as the minimum flow thresholds needed to sample, whether to use time or flow intervals for sampling, and the differences between compositing or discreet sampling. “Those are the three major questions we’ve looked at, and the point is to look at uncertainty—if we know there’s a true load out there and in whatever scheme we’re using, how close are we getting to measuring the true amount of pollutants that moved off the landscape?” says Harmel. In an attempt to answer those questions, Harmel’s team has, for instance, set up a Teledyne Isco single bottle sampler set to take samples on every millimeter of runoff over the watershed. “With that single bottle sampler, we know the mean concentration of all our pollutants over the storm,” Harmel says. “We made the assumption that that’s the true value, the true amount of pollutants that came off. Then we set up on the same site a sampler to take samples half as often, doubling and quadrupling the sampling interval to see if increasing sampling intervals increases the uncertainty.” The agency also set up the same sampler looking at composite sampling. “We would take the average concentration for the first two references, assuming we composited two samplers in the third and the fourth,” Harmel says. “Basically, with that scenario, we had 15 different sampling strategies we could evaluate with that second sampler by manually picking which sample we wanted to look at.” Harmel, who has published many of his findings, says what excited him about the research is that it showed increasing the sampling interval definitely increased the uncertainty, but compositing samples had no effect on sampling uncertainty. “With cost being such a concern for everybody, that was a big benefit, because you can composite without increasing uncertainty,” he says. “You don’t know as much about how the pollutant changed over the storm event, but if you’re not interested in that—if you’re just more interested in a total load for the storm—you can save a lot of money by compositing.” Educating the Public Down Under
The municipality of South Gippsland Shire Council encompasses the southernmost point of the Australian mainland, Wilson’s Promontory, located north across Bass Straight from the island state of Tasmania. Located within the municipality’s jurisdiction are 28 unsewered small towns dating back to the days of early forest clearing. The dairy and beef farms located on these rich soils receive high rainfall. “Most older households and businesses in these towns had direct greywater discharges to stormwater and potentially to failed septic tank treatment and absorption systems,” explains Callum Morrison, wastewater planner. The public health and environmental implications are obvious, he says. “Unfortunately, the problems are so diffuse and clearly don’t appear in statistics or newspapers, so the necessary state political support to rectify the problems has not been forthcoming,” Morrison says. With wastewater management options being considered for these townships, a starting point was consulting with the public about the current stormwater contamination, he says. Morrison and Skye Scott, environmental health officers, conducted normal stormwater sampling for nutrient and microbiological contamination. “The results were scary to any health professionals, but surprisingly there were no prescriptive standards for what must happen when these high counts of contamination are detected,” Morrison says. “We were not satisfied these results of conventional sampling provided a clear enough perspective for legislators and residents. “The legislators should have known or been advised better, but most residents also had difficulty comprehending the millions of invisible nutrients of microbes we were measuring.” Continuous digital monitoring of temperature and water levels made it possible to “crudely” show when and how much wastewater was passing through drains, Morrison says. “Anyone who looks in these drains cannot help but be overwhelmed by the smells of the slimy putrid contamination, but sometimes drains appear to be running clean or are too deep or inaccessible to see,” Morrison says. Morrison’s team used In-Situ’s miniTROLL probe. With digital monitoring that uses temperature and water pressure, it is possible to “see” discharges instantly and record what happened after dark, he adds. “The timing of discharges coincided with flush events, and there were recognizable discharge patterns—particularly for showers, baths, and washing machines—for a whole street of houses.” He says it was advantageous to have graphs showing the problem as being communitywide rather than trying to make the point with one sample, which would call into question its source. “The clarity and usefulness of the graphs have grown beyond our expectations and have been very well accepted and understood by the public,” Morrison says. “The public, and their representatives and advisors, now have to consider what options they have to properly manage wastewater to prevent or reduce these discharges to farmland and the environment.” He adds that the same equipment and methods can be used to evaluate the effectiveness of stormwater management programs. Morrison had successfully used the equipment for monitoring septic tank systems, and Scott’s background was in municipal stormwater education. “It seemed like the obvious tool; we already have this submersible computer available,” says Morrison. “It is truly part of our team.” Morrison says he and Scott “don’t stand still long enough” to see what the computer does. “Just writing down the millimeter changes in water levels and accurately recording temperatures every half a second for days and nights would be a challenge,” he says. “Worse than that, imagine the horrible stinking and storm conditions the submersible computer willingly braves. It regularly shows up things never seen before or unexpected, which is exciting, and it does not mind reading repeated or extended observations. Most humans would go mad in the stench in a very short time if they had to record these manually.” Morrison says he likes the fact that he’s not had to run the tests again, because the few tests conducted demonstrate the equipment’s capability. “We can be pretty confident of finding similar results in any unsewered town if anyone ever challenges or has concerns and would like us to run a test somewhere for their benefit,” he says. “We agree more research and analysis needs to be undertaken to get the full benefit of this technique, but most of it is common sense and clearly able to be understood by most people.” In a paper he helped author, Morrison points out that pathogens, nutrients, chemicals and heavy metals and endocrine disruptors such as hormones and antibiotics pose the greatest threats to public health and environment. Most water-quality risks are low, Morrison points out. “However, even the small blips could be something dangerous for public health or the environment if it happened to include a dangerous bug or concentrated chemical,” he says. “The effects also can be cumulative—they compound and increase the longer they are allowed to continue. Public expectations are likely to be clarified when people are presented with this new information.” Morrison says protocols for the program are still in their infancy, and his intent is to develop them through the Australian Institute of Environmental Health. “We hope to provide guidelines on how to use these results for education to those associated with the source of pollution and also the receiving parties,” he says. “New things are continually being discovered. Rain normally showed up as a temperature drop and rapid water-level rise. In warmer times of the year, the road surfaces heat light rain and might account for accelerated odor generation, bug growth, and rapid oxygen reduction at these times.”
Morrison says further research is needed to determine how best to focus the techniques for monitoring catchments and working back upstream to sources. “Other more detailed sampling and analysis—both conventional and digital—should only be undertaken if they prove absolutely necessary,” he says. “We hate to think what else would be revealed if other sampling measures were used. Realistically, all we should need to show is that there is a potential pathway for serious contamination. If wastewater blips show it is getting into stormwater, then there is a problem.” Ideal level and temperature sampling intervals and test periods are still being determined. When monitoring occurs, the results are manually downloaded to a laptop computer onsite. The graphs and data can be viewed onsite and more closely scrutinized if necessary on a spreadsheet, Morrison says. “There is no point in looking beyond the obvious in most situations,” he says. “However, in the future we see this simple tool helping us make a lot more sense of the other parameters we might sample, and when we sample them, if we are trying to make a community sustainable from a discharge perspective.” Carol Brzozowski is a journalist in Coral Springs, FL.
SW May/June 2006 |
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