March 17, 2015 12:12

The Challenges of Stormwater Management

A long time ago, in a galaxy far, far away, “stormwater” was just rain water. It fell from the sky every now and then—sometimes less, sometimes more. It was just something you lived with. People have been channeling it, collecting it and sheltering against it for thousands of years, but they didn’t call this “stormwater management” until recently.

In today’s world, stormwater management is an umbrella term that covers a great many techniques and a wide variety of tools. Despite constant innovation, managing stormwater has never been an easy profession. And, it probably never will be.

Each job presents its own unique set of challenges.

There’s the physical difficulty of defending against what Nature throws at us. Next, there’s the need to comply with federal, state and local regulations. Add to that the sorts of things all contractors deal with—budgets, personalities, politics.

Regulations, regulations and more regulations

If you don’t like dealing with forms, bureaucracy and long lists of rules, you shouldn’t get into stormwater.

One form every stormwater professional is familiar with is the Stormwater Pollution Prevention Plan (SWPPP). To ensure that only clean stormwater leaves construction sites, any project with over an acre of earth disturbance is required to have one.

The EPA (Environmental Protection Agency) provides guidelines for how SWPPPs should be implemented. A majority of states have also taken on that responsibility, and issued their own guidelines. Some of these guidelines are even stricter than the EPA’s.

In order to comply with SWPPPs and avoid fines, big construction companies often have in-house environmental departments charged with keeping their projects compliant. Translation: compliant with all of the various rules and regulations involved in any given project. That, in itself, is a full-time job.

The Canby, Oregon-based Wilson Construction Company has one of these departments.

“At our environmental department’s inception, about ten years ago, it was somewhat unique,” recalls Matt Hooge, senior environmental scientist and a CPESC (Certified Professional in Erosion and Sediment Control). He’s also a California-certified QSD/QSP (qualified SWPPP developer/practitioner).

His department is involved from the estimating stage of a project all the way through to completion. It’s a model that has worked well for Wilson.

Hooge says that all of the states have the same goal, to meet the EPA’s requirements. The differences lie in how the documentation is handled. Depending on the state, there may be more specifics about which BMPs (Best Management Practices) are to be used and the ways those BMPs should be put into place.

Wilson works in Canada and in several western U.S. states, including California. It’s Hooge’s job to keep track of what all the different governments’ requirements are.

It keeps him on his toes. For instance, “California’s stormwater program was revamped a few years ago, and is very stringent,” said Hooge. “They’ve separated conventional sites from linear projects, so each type has a different SWPPP that needs to be implemented.”

A “conventional” project is the construction of a building with four corners. A “linear” project is something like a pipeline that may continue for hundreds of miles. As a utility construction company, a lot of Wilson’s work is linear, involving moving and installing electrical power lines.

John Baker, CPESC, CPSWQ (Certified Professional in Stormwater Quality), and CESSWI (Certified Erosion, Sediment and Stormwater Inspector), is an erosion control coordinator at Burnsville, Minnesota-based Ames Construction, Inc. He works out of the regional office in Scottsdale, Arizona, on the company’s projects in that state.

Baker often runs into sets of rules and regulations that conflict with one another. “We have to follow the SWPPPs, but in Arizona, we also have to follow the “specials” (Roadway Design Special Provisions) that ADOT (the Arizona Department of Transportation) has.”

“A lot of times, the SWPPPs and the specials will conflict with each other. Sometimes it’s hard for us to figure out exactly what we need to do to stay legal.”

Here’s an example. “Say I come on a job and I do an inspection, and something’s out of compliance. ADEQ (the Arizona Department of Environmental Quality) says we have seven days to fix it. But ADOT’s special says we only have four.”

“If I’m doing the inspection on a Thursday, that gives my guys only five days to do the work, and get it done by Monday,” says Baker. “But that’s five calendar days, not workdays, and my guys don’t work weekends. That’s not enough time.”

Sometimes ADOT wants a certain type of silt fence put in, and the supplier doesn’t have it in stock. If he has to order that, or some other BMP, that’s another delay. “And many times, we have to drive quite a distance to pick up the product.”

Baker says that a lot of times these agency people are looking at the black-and-white of what the permit or the special says, and they don’t give him any wiggle room.

If his crew exceeds the amount of time they’ve been given, these agencies can issue a “stop work” order, effective until some official comes out and inspects the site. There might not be a fine or penalty, but the work stoppage alone costs the company money.

“Now we’ve got machinery and guys not doing any work. I’m management, on salary, but a lot of the guys in the field are hourly, so they’re losing money, too.”

Engineers vs. contractors

In his job as an erosion control coordinator, Baker often finds himself in situations that are, well… uncoordinated.

“The biggest frustration I run into has to do with engineering plans. Usually, the guys that write them, the engineers, aren’t out in the field. They’re sitting in an office somewhere, looking at a topographical map. They don’t know what the real-life conditions are, what the actual topography of the sites look like.”

Baker has run into situations where a state or city has agreed to what an engineer has specified. His company goes ahead and installs that BMP. But then, the first big rainfall comes and takes it out, because the engineers failed to account for something they might have foreseen, had they visited the actual site.

“A lot of times they’ll say, ‘Just throw in a 20-inch straw wattle.’ They’ll ask for that to be put in as a perimeter control, or along a slope, instead of putting in a rocklined channel, like they should have. And the next thing you know, there’s streams of water coming in off the desert that just blow right through it. We usually have to go back afterwards and fix those problems for them.”

This sort of conflict is nothing new. There’s often a tension between the troops on the ground—the contractors and their crews—and the office-bound generals, the engineers who write the specs.

“I’ve been hearing this sort of thing since I was 13 years old, sitting in with surveying crews,” said Christopher B. Burke, P.E., PhD, D. WRE (Diplomate, Water Resources Engineers), Dist. M. ASCE (distinguished member of the American Society of Civil Engineers), and president of Christopher B. Burke Engineering, Ltd., Rosemont, Illinois.

“Regardless of what type of construction it was, the field guys were always saying, ‘The engineers in the office don’t know how to design a storm sewer, a sanitary sewer, a water main.’” “I used to think that, too,” continues Burke. “Later on, you find out that it was the guy in the field who didn’t know what he was talking about.”

He says that the people on the ground may not understand that much about fluid mechanics, hydraulics or hydrology. (A lot of veteran stormwater contractors would take issue with that statement.)

“They may not get that the 20- inch wattle is there because there’s a ten-acre watershed that’s coming,” continues Burke. “They may not understand the impact that the drainage area has on the design and the infrastructure.”

He concedes, however, that even engineers make mistakes. There are situations when they’ll specify something inappropriate, and the contractor can’t make it work, no matter what he does.

Stormwater mismanagement

Anna Griggs, CESSWI, is national operations account supervisor at Hazelton, Pennsylvania-based DBi Services, a company that provides infrastructure maintenance, operations and management solutions in North America, Europe and the Middle East for public and private clients.

Griggs usually deals with the construction of new retail stores. She says that when she visits construction sites, she often sees that stormwater isn’t being managed at all. She says that often, the lack of management starts at the completion of construction, when the general contractor turns the project over to the property’s owner.

“I’m not going to say that these owners aren’t informed about the need for stormwater management, but I’m going to say that stormwater isn’t first in their vision. The first thing they want to do is open the door and start selling stuff. A lot of times, there’s a disconnect between the construction and post-construction phases.”

“What I tell new clients is, ‘As soon as your contractor says it’s done, let me go look at it,’” says Griggs. “‘Let me see that everything pursuant to the NPDES (National Pollution Discharge Elimination Service) permit and the notice of termination has been done satisfactorily.’ Everything’s supposed to be clean.”

She says she’s not throwing contractors under the bus, implying that they’re not doing what they’re supposed to; rather, that property owners should check things out before they open a new facility for business. Many times what an engineer has written into a construction plan hasn’t always been implemented.

To prevent these types of problems, Griggs would like to see better communication between engineers and contractors.

Baker has also visited sites and observed that stormwater was being mismanaged. “We see that all the time. You can see that sediment has left the boundaries of their site, because they had inadequate erosion and sediment control measures in place.”

No room for BMPs

There are times when stormwater professionals have to be flexible and think outside of the box, as this next example illustrates.

The Long Creek Watershed in South Portland, Maine, is considered an impaired watershed, due to years of commercial development, much of which occurred prior to the advent of water-quality regulations. Water bodies within it were failing to meet state water-quality standards.

The watershed management district wanted to retrofit a section running alongside Maine Mall Road with stormwater management devices. Sebago Technics, Inc., a civil engineering, surveying and landscape architecture firm in South Portland, was charged with figuring out how to get this done.

“The section of the thoroughfare that we were dealing with runs alongside a heavily commercialized area with lots of automobile traffic,” said senior project manager Robert A. McSorley, P.E.

At first, he looked at reducing pavement along the sides of the road, but that wasn’t feasible. Another challenge was a direct-bury, 600-pair communications cable, which would have cost a prohibitive amount of money to relocate. There were also some high-pressure gas mains along the road.

As a result, there were lots of sections of roadway where there just wasn’t much room to install BMPs. “We were trying to find a device that we could install inline with the drainage system, and we just couldn’t come up with anything,” recalls McSorley. “And there were some areas where we just couldn’t get into the right-of-way because of the grading.”

He consulted with Contech Engineered Solutions, LLC in West Chester, Ohio, about using some esplanade box filters in some of the tight spaces. Someone there suggested that perhaps a new type of filter called a “Jellyfish” might work.

This BMP consists of a concrete cylinder with a weir inside. The most important components, however, are cartridges that are screwed down into the bottom of the cylinder. These cartridges contain tentacle-like membranes, hence the name, “Jellyfish.”

These tentacles reach down into the cylinder’s reservoir. As the water is forced down into these cartridges, the tentacles take out the petroleum distillates and heavy metals.

McSorley describes this BMP as kind of a hybrid between a hydrodynamic separator and a water-treatment process. “With a hydrodynamic separator, you’re mainly getting sediment and trash out. This hybrid unit enabled us to give the water an additional element of treatment.”

Three of the devices were used, along with some of the aforementioned box filters. Now the system could handle the peak flows it would get during a flash event.

Also unique to the project was another BMP, a hybrid bio-retention design that used the concept of a gravel wetland to treat runoff in small treatment cells. “This was developed by the University of New Hampshire’s Stormwater Center under the direction of Dr. Robert Roseen, who was a subconsultant on our project,” said McSorley.

Antique sewers

Burke says that many of the challenges faced by stormwater professionals, particularly in our older cities, are due to the way the sewers were built back in the horse-and-buggy era.

“A lot of urban areas don’t have storm sewers, they have ‘combined sewers’ (where stormwater co-mingles with sewage). They bring a lot of pollution along with them. Combined-sewer overflows are still a major problem in almost every older, urban area in the country.”

Burke explains that “the city of Chicago was built more than 100 years ago. Back then, no one realized that we really needed to put the stormwater in one sewer, and the sanitary sewer waste in another.”

He said that during rain events, Chicago’s wastewater treatment plants get full of clear water that could have gone straight to a waterway, if not for the city’s antiquated sewer system. The problem is compounded by the fact that the pipes are undersized for stormwater, so even minor storms cause lots of flooding, with overflows into waterways.

“If we could go back in time, we wouldn’t put combined sewers in,” adds Burke. “But the price tag of separating sewer systems is very expensive.”

This situation creates both opportunity and difficulty for stormwater professionals trying to create solutions in our older urban centers.

But doesn’t opportunity often come disguised as a problem? For those who work in stormwater management, challenges are all in day’s work.

Permeable Pavers continued from page 23

In areas that have soils with low infiltration rates, permeable pavement can be combined with subsurface drainage systems, such as stormwater infiltration trenches, to slow runoff.

Safety is another factor. Pervious paving systems should not be installed in areas where hazardous materials are stored. A toxic spill on a pervious surface could seep down and contaminate groundwater.

A soil’s infiltration rate is also affected by the depth of the seasonal water table below the pavers, the average amount of regional rainfall, and the amount of runoff collected from surrounding pavements. Every detail ties into the equation, so you want to make sure you know exactly where your runoff is coming from before you start the installation.

An integral part of the design process involves determining not only how much water can be stored in the system, but also how fast it will drain from the system.

While most rainfall events deliver less than 25 mm (1 inch), rainfall intensity must be considered as

the average amount of regional rainfall, and the amount of runoff collected from surrounding pavements. Every detail ties into the equation, so you want to make sure you know exactly where your runoff is coming from before you start the installation.

An integral part of the design process involves determining not only how much water can be stored in the system, but also how fast it will drain from the system.

While most rainfall events deliver less than 25 mm (1 inch), rainfall intensity must be considered as well. During a big storm, the water table below the pavement can rise, preventing precipitation from absorbing into the ground. Adding bioswales, rain gardens and underdrain systems are often considered during this stage of design.

“Understanding all of the characteristics will help determine the right application to install,” said Messmer. “Only after you fully understand all aspects of the jobsite can a design be put in place.”

When Champlain College in Burlington, Vermont, set out to pave a main promenade, their first assessment of the site proved to be incorrect. Its goal was to have a hard surface that could withstand the weight of both pedestrians and vehicles, while providing stormwater management.

“Originally, they put down a pervious concrete sidewalk on top of a series of graded aggregate materials,” said Barnes. “It failed in about a year, and they installed pavers instead, which are still there today.”

Additional benefits 

To the multiple environmental benefits associated with pervious paving, we can add the financial advantage of cost-effectiveness. Areas paved with them may eliminate the need for retention ponds and other underground drainage applications, because the pavement itself acts as the retention area. Not having to build or maintain a retention pond saves an untold number of dollars.

“Prior to pervious pavers, you would need an additional acre or two for a retention pond. Now, if you pave that area with pervious paving, you allow the water to filtrate through, eliminating the need to retain that water,” Killingsworth said.

According to a study published by the American Society of Civil Engineers, only 12 to 18 percent of a project’s total surface area is required for optimal drainage and stormwater management. Pervious paving systems are relatively compact, and therefore free up land to be used for other purposes. Property owners can maximize the use of their land and develop larger areas at lower cost.

The development of alternative paving systems is just one way our industry continues to promote sustainability. The increasing use of pervious pavers and other green-infrastructure products can have a huge significance in lessening our impact on the environment.

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In many ways, we are fortunate that, in our chosen profession, we are able to help people when certain disasters occur: the tornadoes in Missouri, Oklahoma, Louisiana and Georgia, the flooding in Louisiana, the snows in the northeastern part of the country, the rain in California, and the snow in Colorado....

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