Simple to Sophisticated: The Right Tools for Stormwater Monitoring

Sept. 19, 2016

On an old, late-night movie, a rangy cowboy tells his younger sidekick, “You see, kid, you don’t bring a knife to a gun fight.” In the construction trade, the mantra is, “You must have the right hammer for the job.”

The same is true in stormwater monitoring: There’s an abundance of tools out there. So, do you need something simple or high tech for your program? Professionals across the country are getting what they need from both ends of the scale.

In the vast, open spaces of Texas, a stormwater consultant chooses simple 1-liter plastic bottles and trains his clients to retrieve and send them in for analysis. In Albuquerque, NM—where the endangered silvery minnow is protected by EPA—Patrick Chavez uses his laptop to graph dissolved oxygen. In Canada, which is losing forest and wetlands, continuous sampling helps track what’s happening. In Washington DC and Maryland, the Council of Governments works with a program in the cloud, using probes and sensors that remotely control storage and flows.

These four scenarios range from simple to high tech in stormwater monitoring. And yet, there’s so much more in the mid-range of products. It still comes down to the old question: What tool do you need for your job?

Monitoring the Great State of Texas
Charles “Dude” Hall, principal at Timber Creek Environmental LLC, an environmental consulting firm from Conroe, TX, has clients located pretty much all over the state south of Conroe and extending over into west Texas as well. It’s a lot of land to cover.

The company performs regular water sampling for different types of industries covered under the industrial stormwater permit, including chemical manufacturers, oil and gas facilities, landfills, and recycling facilities. Sampling must occur within the first 30 minutes of a qualifying rain event. Storms large enough to qualify are relatively rare in Texas, but when one does occur, the company needs to sample at multiple client locations simultaneously. And because such storms are uncommon in Texas, “You want to collect as many samples as possible during the first event of the season, in case that’s your only shot at it,” says Hall.

The options include installing programmable autosamplers for every outfall, which would be expensive, or hiring a team of people ready to be deployed at a moment’s notice when the rain starts—even more unfeasible. Timber Creek has found a more affordable solution using 1-liter Nalgene bottles from Thermo Scientific—what Hall describes as “the little bottle with the Taj Mahal cap on top.” The sample bottles are placed in holding tubes that are installed by hand into drains, culverts, ditches, or outflows. They capture the first-flush flow automatically. They have a floating ball valve; as the water rises, the valve shuts and seals the bottle.

After the storm, the Timber Creek team collects and replaces the bottles and transports them to a lab for analysis. Hall also provides training to his clients so they can get the samples to the lab if needed.

“They take it out, put it on ice, and ship it to the company overnight,” he says. “They only ship Monday through Thursday, so it doesn’t end up sitting over a weekend in a back room someplace.” The outer mounting tube simply stays in place waiting to be loaded with another sampler bottle.

“This sampler makes it economically feasible to monitor an unlimited number of widespread outfalls simultaneously and collect samples within the first 30 minutes of discharge every time. It’s a simple yet elegant solution,” says Hall.

Credit: Timber Creek Environmental
Nalgene sampling bottle installed in the ground at a monitoring site

“Each regulated industry has a set of baseline compliance tasks they must complete,” he explains. “Additionally, certain industries, as determined by their Standard Industrial Classification codes, may have requirements above and beyond the baseline requirements. These may include additional monitoring, specific best management practices, or more stringent inspections.”

He explains, “Collection volumes are based on the analytical requirements, and typically one liter will suffice. Say, for a landfill that’s one hundred acres, you’ll need a half-inch. But, for a trucking company, you would need less.”

Runoff volumes differ based on types of surfaces. “Concrete and impervious surfaces have roughly a 90% runoff coefficient, whereas vegetated areas may only have a 60% runoff coefficient. So, a 0.5-inch rainfall may not generate runoff at a landfill, but the same rain at a paved trucking facility will generate a significant runoff.”

Once the samples are analyzed, required inspections are performed. “Everyone has to have visual inspections quarterly, and it all has to be documented. Then there are other [clients] that will have benchmarks. Theirs go to the lab for potential pollutants. These are done semi-annually. And, again, each sector is different.”

He watches these benchmarks carefully and from them creates graphs to show what constituents are moving up or down. If something is moving very far, consistently, Hall begins an investigation to see what’s causing it.

“For instance, if iron is high, we want to look at what might make it high. Is there maybe a metal scrap yard on the premises or old cars and trucks that can be removed? If the total suspended solids are high, again, we look at why. And how can we bring those numbers down? Can we move the equipment or put in silt ponds?”

The time of year can sometimes have more to do with an incident than actual BMPs that are in place. Such was the case with a recycling facility that was having trouble with some high numbers. When Timber Creek began to look at trends and peaks, it landed on the Christmas season as the culprit and helped the client schedule more manpower and equipment to break down and bale cardboard and other packaging material so the product wasn’t sitting on docks for long periods of time.

“It was a matter of being prepared,” he says. “Increase your temporary labor. Schedule your equipment and transfers. Pack it, bale it, and get it on down the pipeline.”

Albuquerque Metropolitan Arroyo Flood Control Authority and the Little Fish
As with many other cities, Albuquerque has had its National Pollutant Discharge Elimination System (NDPES) stormwater monitoring program in place for several years. The difference in the last few months, says Chavez, is that the city can now monitor in real time. Chavez is the stormwater quality engineer with the Albuquerque Metropolitan Arroyo Flood Control Authority (AMAFCA).

He has recently been using In-Situ’s Aqua Troll 600 Multiparameter Sonde to monitor turbidity in the Rio Grande River as part of AMAFCA’s stormwater management plan. Currently, AMAFCA has preset frequencies of 30 minutes to measure for turbidity, temperature, and dissolved oxygen. When he needs to collect the information, he can do so by flipping on his laptop computer.

AMAFCA is very involved with the community and tribes of the area and advises a mult agency group about the health of the Rio Grande. Particularly, the stretch known as the Middle Rio Grande (MRG), which was selected by EPA for a pilot program in 2009.

Credit: AMAFCA
Deploying a sonde to monitor turbidity in the Rio Grande River

Based on the 2009 report published by the National Research Council (NRC) titled “Urban Stormwater Management in the United States,” EPA announced a pilot program to examine watershed-based permitting. The Middle Rio Grande watershed in Albuquerque, the Ramsey-Washington Metro Watershed District in Minneapolis/St. Paul, MN, and the Menomonee watershed in the Milwaukee, WI, area were the three pilot areas selected. The MRG was chosen in part because of existing water-quality impairments and the opportunity to work on the challenges presented by an arid or semi-arid climate. Other factors EPA considered when selecting the MRG included upstream pollutant contributions, and the opportunity to establish partnerships and cooperation among watershed stakeholders and permitees with the goal of improving stormwater management programs. The watershed’s hydrological and topographical features played an important role as well. The Rio Grande provides ceremonial use, drinking water, fishing and recreation, and agricultural irrigation for the local communities and tribes of the area. Contributions to stormwater runoff come from community, industrial, residential, state, university, federal, roadway, parking lot, and other sources.

The US Fish and Wildlife Service designated several endangered species within the MRG watershed. The silvery minnow, Hybognathus amarus, is found in the Rio Grande and its tributaries, including the North Diversion Channel.

“We have three locations along the Rio Grande where we can monitor for dissolved oxygen 24 hours a day,” says Chavez. “One is in Bernalillo at the Highway 550 bridge—we call it the north end. And upstream, actually above the North Diversion Channel outfall and the southern-most area, is the Central Avenue bridge. That’s where the sondes are located for real-time monitoring.”

Credit: Greyline Instruments
Installing the Stingray logger

The Rio Grande silvery minnow is in the cyprinid family and is considered to be one of the most endangered fish in North America. A fairly small fish, with adults reaching only 3.5 inches in length, it was classified as endangered in 1994. Currently, it is found in little more than 5% of its natural habitat in the Rio Grande. Because the silvery minnows are herbivores, they are thought to help clean up water by eating algae and by skimming the bottom of streams and rivers.

The city of Albuquerque and AMAFCA submitted a strategy in 2012 to address dissolved oxygen levels in the Rio Grande receiving waters. The plan was implemented partially in response to a fish kill in 2004, although no silvery minnows were associated with that particular kill. The strategy was part of the pilot program. As soon as AMAFCA and the city of Albuquerque were aware that there was a problem with oxygen levels at the North Diversion Channel, they began addressing the problem through an investigation and stormwater samples. In spring of 2012, as per the strategy developed, a wide shallow pool was constructed for better river water circulation and to provide a natural nursery habitat for the minnows.

“One storm event can change things,” says Chavez. “At that site, dissolved oxygen was usually high. But with stormwater and river water there, we had an area where the water was stagnant that contributed to a decline in dissolved oxygen levels. Then runoff from the next storm pushed the stagnant plug into the river, which made the dissolved oxygen go down storm after storm.

“If we have a storm now, I check the graphs and see where the dissolved oxygen was before the storm and after,” he continues. “The Aqua Troll is a really good analysis tool, and we can use it for compliance, as well. And the 600 unit has an auto scrubber that cleans the probes, so it keeps the readings true. It can also see the increase in turbidity downstream in real time.”

Turbidity impairs aquatic life and light transmission. Extreme turbidity can also affect the levels of E. coli by blocking UV rays.

“Based on our TMDL for E. coli that’s been established for our stretch of the Rio Grande, each MS4 has a waste load allocation that determines the amount of E. coli they can discharge to the river,” explains Chavez. “We can monitor the increase, or the decrease, of turbidity in real time and go back and be smarter about why the E. coli did or did not change. Just because there was a storm, it doesn’t mean there was an increase in E. coli.”

Credit: Greyline Instruments
Installing a sensor

Raisin Region Conservation Authority: Hanging Onto Wetlands
In 1963, the Raisin Region Conservation Authority (RRCA) was established to address local environmental issues such as flooding, poor farm drainage and the provision of water supplies to and from the St. Lawrence River. The St. Lawrence River, containing approximately 21% of the world’s fresh water by volume, is listed among the world’s largest rivers and helps to drain the massive Great Lakes fresh water system.

“There’s several Areas of Concern [AOCs] in the Great Lakes basin, with issues including pollution, habitat loss, and a variety of other environmental issues,” explains Chris Critoph, manager of environmental services with RRCA.

An Area of Concern is designated as such because of significant pollution and subsequent habitat loss. Both Canada and the United States are equally responsible for the St. Lawrence AOC and for implementing the remedial action plans that are part of that responsibility. Identifying the environmental challenge is the first stage of the plan, followed by a plan report. Once delisting of the AOC is accomplished, then it continues to be monitored as necessary.

“Intensive agriculture is a large contributor to the eutrophication, or high phosphorus and undesirable algae, we see in our area,” explains Critoph.

Matt Levac is the planning and regulations technician in charge of water-quality sampling stations at each of 14 tributaries on the St. Lawrence River. He uses the Greyline Instruments Stingray 2.0 Level Velocity Logger.

“The overall water monitoring program has been going on since 2004, but by using the Stingray Logger now, it gives us a good idea of exactly how the tributaries are performing,” says Levac. “With the logger we get continuous sampling. But if we do get a large rain event, we try to get out there sooner, too.”

“We’re primarily monitoring the phosphorus concentrations in the tributaries,” adds Critoph. “We want to know what the total phosphorus loading into the St. Lawrence River is. If we know the quantity of water and its concentration of phosphorus in each of the tributaries flowing into the St. Lawrence River, we can then determine the quantity of the phosphorus going into the river.”

Levac uses the Stingray Logger at sites that are located closest to the tributaries of the St. Lawrence. The portable Stingray 2.0 Level Velocity Logger can measure water level, velocity, and temperature in open channels and sewer pipes. Levac chose to install it in a culvert.

“We chose large culverts,” he says, “and we bolted it inside the culvert. Then we go out and collect monthly.”

Designed for use in municipal stormwater, raw sewage, and combined effluent for the wastewater industry, the Stingray’s submerged sensor works accurately for extended periods of time in irrigation waters and stream flows as well.

Greyline Instruments Inc., located in both Canada and Massena, NY, provides the Windows software that is used for flow analysis and can be preset for data to be downloaded to a client’s laptop. “From there,” says Critoph, “we can just figure out the flow data, and the software produces the charts we need.”

Levac stresses the importance of being able to see the water data in real time. After he retrieves a log file, all it takes is a click within the program to produce a flow chart.

“There’s a decline in our wetlands and reduction of forest cover,” explains Levac. “There is a direct impact to our quality of water. As we lose those filters, the concentration of phosphorus will continue to increase.”

In an effort to delist the AOC on the St. Lawrence River, the RRCA sought target goals, sampling and observing to find a good control watershed for the study. The general target for total phosphorus is 0.03 mg/L, but because of the historical intensive agriculture in the area, Levac and Critoph were having a difficult time finding tributaries that would consistently sample in that range.

“We chose Hoople Creek to watch because it’s doing really well,” says Critoph. “It’s a baseline. It still has a lot of farming and woodlands, yet it’s doing well. But, in comparison, we have at least three watersheds in intensive agricultural areas with no buffers. Their phosphorus levels are through the roof.”

The RRCA saw that there were problems with these areas where the land had lost its forest and wetland buffers had been over-farmed from row crops. The idea of reaching the 0.03 mg/L total phosphorus level seemed daunting, even unattainable.

The decision was finally made to bring in private consulting group, AECOM, from Bracebridge ON, Canada, to help set up an achievable target for total phosphorus. In its evaluation, AECOM reviewed stream nutrient criteria for the St. Lawrence River and its tributaries, and then developed an assessment to look at the water quality in the sampled tributaries in relation to criteria for delisting. Additionally, it sought a scientific rationale for developing alterative and site-specific delisting criteria based on export coefficients that take into account land use in the tributary watershed.

AECOM notes, “Criteria for delisting should acknowledge irreversible human-induced conditions whereby the watershed has been altered by some kind of agriculture or urbanization. Therefore, delisting goals should be to restore impaired uses and water quality to its best achievable levels.”

“We have some unique targets for our areas,” explains Levac. “They are about double. But we’re reaching them. We’re concerned about the loss of wetlands and forests and trying to reach out to landowners”

“We try to encourage landowners to install buffers along streams and keep cattle back,” says Critoph. We have them plant shrubs and trees native to our area that the wildlife also like, such as willows and dogwoods. They also hold the banks in place and filter the water. And they provide wildlife habitat and cover.”

He adds, “We also encourage them to use the ALUS program—that’s the Alternative Land Use Services. It’s a totally voluntary program. It helps the landowners to install buffers, and they get a small compensation. But again, I want to stress that it’s all voluntary. That just seems to work better.”

AECOM noted that the delisting criterion of 0.03mg/L total phosphorus represents a watershed that has not been impacted by agricultural or deforestation practices. It might, therefore, be an unattainable goal in the St. Lawrence River watershed due to its current and historical land-use practices.

Anacostia Watershed Restoration Partnership
The Anacostia River flows into the massive Chesapeake Bay by way of the Potomac River. Compared to the vast 64,000 square miles of the bay watershed, Anacostia’s mere 176 square miles might seem insignificant. But with its population climbing to more than 800,000, and with an aging water infrastructure, the importance and health of this relatively small urban river is vital.

It’s safe to say that the Anacostia Watershed Restoration Partnership (AWRP) has an extensive amount of work on it hands, in spite of the abundance of restoration efforts since the 1960s. The partnership oversees what was once referred to as “the forgotten river” of the Washington Metropolitan Area. The AWRP was originally established in 1987 as the Anacostia Watershed Restoration Committee and is made up of local governments, including Montgomery and Prince George’s counties in Maryland, the District of Columbia, and the Metropolitan Washington Council of Governments (COG). The COG is an independent, nonprofit association that brings area leaders together to address major regional issues in the District of Columbia, suburban Maryland, and northern Virginia. COG’s membership comprises 22 local governments, the Maryland and Virginia state legislatures, and US Congress.

Supporting agencies with the AWRP include the US Army Corps of Engineers, EPA, state of Maryland, and the National Park Service.

Phong Trieu, COG technical manager with the Anacostia Restoration Program, says to a great extent the effort involves sharing of information across these jurisdictions. “Right now, we primarily provide technical services,” he explains. “But with stormwater monitoring, we do in-situ sampling and continuous monitoring, as well as biological monitoring of the downstream areas.”

As part of this partnership, the COG helps supply technical services to AWRP and makes administrative staff available as well. Reaching out to the citizens in the jurisdictional areas resulted in yet another arm of the program, the Anacostia Watershed Citizens Advisory Committee (AWCAC), formed in 1996. The committee has grown to be an important component of the program.

After watching a presentation from Opti in 2013 on the new CMAC (Continuous Monitoring and Adaptive Control) technology, OptiNimbus, the then-chair of the partnership’s Anacostia Management Committee decided to bring the same presentation to the technical group and subsequently coordinated with COG to submit a proposal for a 2013 National Fish and Wildlife Foundation Grant. The group was awarded the Chesapeake Bay Innovative Nutrient and Sediment Reduction grant, which has helped restore more than 10 acres of tidal wetlands along the Anacostia River, increased outdoor recreation, and improved flood control in the capital district. Trieu says there have been grants in three areas of concentration, included wet ponds, dry ponds, and bioretention ponds. Whether it’s working with new wet ponds or retrofitted dry ponds, Opti’s CMAC stormwater technology has established cost-effective solutions to some of the most challenging stormwater issues.

Credit: Maryland Council of Governments
CMAC wet pond implementation in Montgomery County, MD, with power panel, communication tower, and pond outfall

By integrating information from continuous probes or sensors that are installed in the ponds with real-time forecasts, technicians can remotely manage stormwater storage and flows.

“Opti is geared to the weather,” explains Trieu. “If the forecast says there’s a 70% chance of rainfall and the rainfall is predicated to be x amount or inches of rain, the system will start to set its operation in motion.” OptiNimbus uses the forecast information to gear the system to receive the predicted amount of rainfall—waiting for peak flows to pass and releasing water retained in the ponds afterward, reducing the chance of flooding.

Trieu adds that as they continue to work with the Opti program and the Dashboard’s cloud-based program, he will be watching its performance.

“We’ll be looking at the system to see if it’s what we desire. In other words, will we observe improvements? Will we see better performance than what the ponds were even designed for? To tie it in with the big picture, we’re gathering the data so it can be utilized for NPDES programs, and to get the information to other COG members to see if it’s something they would want to use.”

He concludes, “The Opti program should be a cost-effective option for converting traditional stormwater practices to higher-functioning sediment and nutrient control measures and reducing operation and maintenance.”

About the Author

Linda Robinson

Linda Robinson is a journalist specializing in agriculture and land-use planning.