Soil

Movin’ Down the Highway

Linear construction projects have their own rules.

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Two decades ago, while working as the erosion control supervisor in Orange County, NC, Warren Faircloth, the then-county inspector, frequently observed a recurring problem with sediment control on construction projects.

“Most of the sites had porous stone dams intended to let mud settle in the basin and release clean water downstream, but when I inspected the site and went below the dams, there was a lot of mud built up,” says Faircloth, whose innovation and product development launched Faircloth Skimmer Surface Drains.

“What happened was the drain was typically at the bottom of these ponds, or they had a porous stone dam. The pressure of the water bearing down would wash mud out the bottom of the basin, so basically the mud was still going downstream,” he explains.

Faircloth’s solution to the problem was to drain the cleanest water from just under the surface slowly and at a constant rate, allowing the sediment time to settle to the bottom and remain in the basin as intended.

With this concept in mind, Faircloth started gluing PVC together in his garage with the intent of creating a product that contractors could use on their sites to control sediment. Working with a local contractor, he installed a skimmer in a basin and waited three months for rain to show that the concept worked. Research by Albert Jarrett, Ph.D., in the Department of Agricultural and Biological Engineering at Pennsylvania State University, confirmed and quantified the effectiveness of the skimmer. The final incarnation was dubbed the Faircloth Skimmer and patented.

As is typical, the success of the project increased demand, and the operation soon outgrew the home-based manufacturing setup. “We outgrew our garage, so we first rented a building, and now we have our own building, so it’s been a good success.”

And of course, Faircloth left his position at the county and never looked back.

He says the company today “offers the Skimmer in eight different sizes, and it is a simple concept but it is hugely effective. The orifice is customized by the user to achieve the dewatering rate they need. What this means is that the flow rate and the orifice are sized to your need. So, for example a 39,000-cubic-foot volume of water using a 4-inch skimmer size with a 3.2-inch orifice takes three days to drain, whereas a 6-inch skimmer can dewater about 155,520 cubic feet in the same amount of time.”

He explains that the extension arm leading to the outflow is smaller than the orifice to reduce buoyancy when the pipe is less than full. This buoyancy would tend to lift the inlet, causing it to float upward, and could reduce flow through the skimmer. The arm is vented to allow the orifice size to control the flow rate.

At first glance, the unit appears somewhat similar to a long-handled broom surrounded by a square of PVC that resembles a 4-foot-square lifesaver. The long arm, or barrel, is in fact attached to a horizontal PVC tube in the float whose intake orifice inside has a constant hydraulic action, with its opening covered by a trash screen. This intake unit is attached to the square “lifesaver,” which performs as a flotation unit and allows the device to rise and fall on the water surface as the basin fills and drains.

“As it floats on the surface, with sediment falling to the bottom of the basin, the cleanest water is released to an outlet discharge drain. The barrel is connected to that outlet by means of a flexible hose, and this is the only exit for the basin water; therefore, it is taking in only the cleanest water from near the surface. Eventually in the drawdown, the cleanest water has been removed at surface level while the sediment is at the bottom,” explains Faircloth.

He adds, “It’s just operational by simple gravity—there is no electricity, pump, or power source,” but to further increase efficiency in sediment capture, the company recommends porous baffles be installed within the collection ponds and basins.

“The North Carolina State University Soil Science Department suggests using baffles, which can be a series of silt-style fences placed in the collection pools; that will improve efficiency by slowing down water. This goes one step further in efficiency if you use a porous baffle like jute backed by a coir blanket, or coir mesh. These allow the water flow to be evenly distributed, which works to reduce turbulence and flow rates. In the end, you get better sediment retention as water flows through these permeable baffles, with really effective sediment settling,” he says.

Because the product is so simple and easy to use but effective, Faircloth says it is ideal for department of transportation projects.

“For almost two decades now we’ve been hearing from customers who use this both on temporary and permanent detention ponds during highway projects, and they are very satisfied with its simplicity and effectiveness. Our skimmer is being used in numerous highway detention ponds and is accepted by multiple DOTs, including North Carolina, Alabama, and many others. And our mission to promote the concept of surface drains to the local EPA has been successful.

“Many local agencies are now including this surface drain sediment process in their regulations, which will help all the watersheds whose soils are being disturbed through new construction, installation, or utility upgrades,” says Faircloth.

Credit: JW FAIRCLOTH AND SON
Unfilled pond with baffles

Confronting Urban Sediment
Old cities plus old infrastructure equals a litany of engineering headaches for all municipalities, large or small. This is the equation that many of the nation’s oldest cities face on a daily basis: water main breaks, combined sewer overflows, and endless underground surprises during maintenance, upgrade, or replacement work.

But for large, dense urban areas, there are additional problems. The added component of working on pipelines that are typically under or next to city streets causes disruption to traffic, merchant economies, and pedestrian flow. Nathaniel Krause, acting chief of Baltimore City’s Department of Public Works Plans Review and Inspections Section, says this type of work requires largely keeping out of the way: “At the end of the day, the contractor has to be picked up and gone.”

He says, “City environments cannot keep roadways blocked after hours, and traffic must be minimally blocked during business hours. So this means that their inlet protections have to be such that they do not impede traffic while working, and can stay in place in the nonworking hours.

“You can’t use silt fencing, for example, while you are excavating, because these are a roadway impediment. But our crews and contractors are all very sensitized to our Chesapeake Bay watershed regulations, and there are stiff penalties for violations of escaping sediment.”

Baltimore has recently been engaged in a massive gas, water, and sanitary pipeline upgrade, removing old pipes and installing new systems.

“It’s typical here for pipes to be 70 to 80 years old or more. Finding pipes less than 50 years old is unusual—our last big building boom was right after World War II in the 1950s,” explains Krause.

“In fact, I was notified about a year ago that a wooden sewer pipe was unearthed, and although it was not in operation, that tells you how far back our systems go.”

He adds that today’s city system now includes 1,100 miles of storm drains and 50,000 storm inlets. If you look closer, you’ll see that many inlets have brass plaques with an image of a fish and the words “This water goes directly to the Chesapeake Bay.” The bay’s economic value to the area in crab, fish, and oyster is more than $3 billion annually.

Krause says that efforts to upgrade these older and sometimes failing systems have changed from being reactive to proactive.

“We can extend the life of our system by going in and doing a good cleaning, relining if necessary, and making sure that the customers like hospitals on old lines that are serving a large population are in good shape.”

He adds that Baltimore is on its fourth National Pollutant Discharge Elimination System permit. “Since the 1980s, we have had a strong erosion and sediment initiative that has stayed strong. Now our stormwater utility has grown since that has started, as we still face a big sediment problem.”

Credit: JW FAIRCLOTH AND SON
Filled pond with skimmer

In the past few decades, new technologies have been developed to replace the use of gravel piles used to protect inlets and capture construction sediment. Krause says that during highway work or underground pipeline projects, the trenching done in the city streets requires inlet protections as designated by city regulations. Contractors submitting bids for highway projects are always required to use inlet protection as stated in those policy guidelines. Krause says, “Contractors are certainly free to specify a proprietary source such as Dandy Bags, Gutter Buddy, or other products; as long as it is in their budget, they can use those.”

However, once the work has started, Krause points out that contractors must pack up and leave for the night, “which explains why we have steel plates in many of our roadways; those are work sites in process.

“When they return to that site, they have to pump out the water and collect sediment, which must then be removed to a filter bag or a portable sediment tank. They can’t just pump out the muddy water. Then this sediment needs to be removed to an approved stockpile area, which could be on a contractor’s staging site or some other location farther out in the county.”

He adds that with heavy equipment moving in and out of a site, a lot of mud is generated. “Good contractors will sweep their road area three times a day to prevent sediment from getting into the storm system. They will hit the street with the sweeper first thing in the morning, in the middle, and then the end of the day,” he says.

However, he cautions that even with a rough cleanup from sweeping, “You still have mud on the road surface, and this is subject to getting into the storm drains, which makes the inlet protections even more imperative.”

Finally, Krause says, these linear projects are unique in the world of sediment and erosion control and require a different approach than the typical static construction site.

“When you are continuously moving down the road with your work, you have to manage sediment collection for the current day, and be mindful of what’s left from the day before, and anticipate the day ahead. Water and mud may be washed much farther away from the immediate worksite, especially on sloping highways, and inlet protections must be accounted for. You may not see what’s happening a mile away, but the inspectors surely will.”

And all the effort is worth it for another reason. “I tell the contractors we are doing this for our crabcakes.”

Weighing in on New Options
Hearing the term “Gator Guard” for the first time might conjure an image of threatening and inescapable reptilian jaws. Bob Hanson, company president and innovator of Gator Guard Environmental Products, agrees that attributes of toughness, resiliency, and inescapability (for sediment) are an accurate reflection of what his erosion and sediment management products can do.

The company provides a wide range of products including foam logs, check dams, sediment control wattles, and, most recently, weighted wattles and weighted gutter wattles. All of these linear units will work “on almost any job site where disturbed water or soil could threaten local waters,” explains Hanson.

“Our 6-inch by 25-foot foam-filled sediment wattles are so lightweight, a 12-year-old can easily pick them up overhead. They are clean, green, and you can reuse them, or, as we say, ‘throw them away—it’s OK!’” says Hanson. He adds, “Heavy equipment can just go right over them—both tracks and tires—and they hold up beautifully.”

He notes that the motto “tough and effective” is not just a marketing phrase; the San Diego State University Soil Erosion Lab has performed tests to challenge the wattles’ ability to hold back soil. In an onsite simulation, researchers pitted straw wattles against Gator Guard and against no soil protection. Then, water was sprayed onto a confined 3:1 slope to simulate a 10-year storm equivalent.

“The results showed that Gator Guard was 98% effective and reported a 1-kilogram soil loss, whereas straw had a 20-kilogram soil loss and was 55% effective, and of course the no-treatment channel had zero effectiveness and had a 45-kilogram soil loss.

“Most construction projects will probably not encounter this severe of a challenge to the product, but it’s good to know that in anything less than that it will do a great job filtering water and keeping sediment in place,” says Hanson.

On highway projects, he says, the lightweight product works well, but “we had customers who kept asking if we had a weighted wattle.” He explains that contractors liked the convenience of being able to connect the guards end to end with ease, and how conveniently they can fold up for shipping and transport. “But they were saying that when you do street work, the typical sandbags or rock bags get run over, and the sleeves are not durable, so they break open and it’s a mess,” he says.

Hanson says the company created several test models and designed the final Weighted Wattles to meet the multiple demands of customers: not too heavy, made of durable materials, pliable to conform to surfaces, and with quick-connection capability.

“These new Weighted Wattles come in 12-foot pieces and have a 20-inch connection sleeve on one end. They are six inches in diameter but only weigh 50 pounds, which is manageable by one person. This was an important request we heard from contractors; they wanted these weighted units to be a one-person job, not requiring two or three workers to load, unload, and install onsite.

Credit: GATOR GUARD
Weighted Wattle at the base of a sand pile

“The outside shell is made of really heavy duty, six-ounce woven monofilament geotextile, similar to monofilament fishing line. For the bottom surface we chose a soft, nonwoven eight-ounce geotextile that feels like felt. The reason we chose this material is the wattles are often used on roadways or curbs and other scenarios where surfaces are uneven. This material conforms to the shape you are setting it on and allows water to flow through, but still stops the sediment. If it’s a stiff material, it causes gaps and defeats the purpose.

“For the weight, we tried a bunch of different things but we ended up using clean coarse sand inside a six-mil-thick polyethylene sandbag, which is then covered with a six-ounce woven monofilament inside shell. To add height and to increase water permeability, we covered that unit with a sheet of one-inch foam,” says Hanson.

He describes their performance as creating a small settling pond. “Both lightweight and weighted wattles collect sediment but let the cleaner water run through by filtering through the geotextile and letting it come out the other side.” The foam-filled wattles come with installation nails and can run along any length or shape needed, conforming to any site configuration, including slopes.

“The foam-filled wattles have a double apron that can be laid either upstream or both up and down. You nail the upstream apron to the ground, cover it with one inch of dirt, and foot-compact this to minimize underflow washouts. When placed downhill, the apron prevents splashing and doesn’t create those little valleys you see that cause more erosion.”

The wattles are UV resistant, retaining 90% strength after 500 hours of exposure.

“One thing we learned is that when the black polypropylene material is created, a product called carbon black is part of that process, and this is a natural ultraviolet light inhibitor. We had tried other colors, but they break down much sooner, so the black units have better longevity.”

Hanson says the material’s tensile strength resists puncture of up to 120 pounds. “We anticipate customers getting a good five years of use out of these wattles,” he says.

For highway projects, Hanson affirms that they are ideal for keeping mud off the roadway and sediment out of the watershed. “Contractors on these linear projects can just pick these up and keep moving, reinstalling them as the work advances,” he says.

State highway jobs have lists of approved products for sediment and erosion management, and Hanson advises contractors who want to use Gator Guard to approach their state engineer to get them placed on lists. “They know these things are much more effective than what they typically specify and can do a superior job in sediment management.”

Awareness is Key
“If we really want something to change, we sometimes have to change our strategy in how to make that happen,” says engineer and environmental consultant Jerry Fifield of Colorado-based firm HydroDynamics Inc.

For several decades, Fifield has been involved in drainage issues, water rights, and sediment and erosion control both in the US and other countries; he says this wealth of experience is the basis for his urging revaluation and overhaul of existing tactics in erosion management. At the forefront of his efforts in promoting this awareness are the four educational manuals he’s authored that address multiple environmental issues often inherent to building projects.

“Since 1983 when I first started HydroDynamics, I have seen trends develop in the arena of environmental policy and regulation. This is primarily in the ‘who’ and ‘how’ aspects of shaping and then enforcing policies during building projects.”

He notes, “One of the big problems we have is not with contractors, and not with inspectors [of projects], but with the designers, who rarely if ever go into the field to see how their projects are faring.

Credit: GATOR GUARD
Foam-filled wattle

“After a designer has submitted a project to the contractor, who then takes it to the municipality for approval, we see that it is stamped by the engineer. Yet there are many examples of engineer-approved projects that result in tremendous problems once the project gets going. The inspector visits and finds a problem, and the contractor is usually first to take the hit of blame. But in the fact of it, the contractor is simply doing what they were told to, and unless there is great variance, it’s a case of following directions that were faulty at the outset. Unfortunately, when the inspector sees violations and any number of water-quality impacts, no one questions those directions because, after all, the engineer approved them, so they are assumed to be valid.”

After a career in the field, Fifield, a registered hydrologist and a Certified Professional in Erosion and Sediment Control, knows whereof he speaks, and preaches.

“Therefore, the key to successful projects is not an engineering stamp of approval; it is in fact before that, and all in the planning,” he says. The clarion call to bring improvements to erosion control on job sites was launched with Fifield’s founding of the Certified Inspector of Sediment and Erosion Control (CISEC) program. This certificate program, administered through the not-for-profit organization of the same name, gives enrollees the education and tools to improve inspecting skills.

“It’s important that people going out in the field understand what they are looking at and can discern that contractors may be performing mitigation as instructed by the approved plans, but that these are not doing the best job possible. We want inspectors to know how best management practices work in the field, are they are installed properly, and is the right BMP designated for the right job.”

Credit: GATOR GUARD
Gutter wattle

One of his most pressing concerns is that designers who write the specifications for projects spend more time in the field than is current practice.

“We saw a lot of designers simply doing a cut and paste of things that were good 20 years ago, and these just slip by with a stamp of approval without any question. Certainly we have new mitigation technologies being developed every year, and these designers need to get out from behind the desk and into the field and see what’s going on in the trenches, literally.”

He adds that real policy change in the arena can be leveraged by designers adopting new techniques and by being truly familiar with how they work, which can only happen by actually witnessing the BMPs in action.

“My thought is that the EPA should require that designers of plans go out at least once a month and then once a quarter to do an inspection of their project. They already inspect bridges and storm sewers, but they don’t inspect erosion and sediment practices they have written up, which many besides myself consider mandatory. And it’s equally important to understand the science behind mitigation technologies. For example, how did anyone determine the spacing of fiber rolls on, say, a 30% slope?”

Fifield cites a highway project in Hawaii that underscores his point. “Here was a case where an inlet barrier is required, and the project was designed by and approved by engineers. However, in actual fact, when inspectors walked the linear roadway project, which was determined to have a 10% slope, the inlets spaced at 36 feet apart would have been totally blocked by the barriers, causing a massive flooding downstream. The contractor put in his observations on this, stating he knew it was going to fail. In this case, sediment control barriers would be better, but the reviewers had already approved it.”

On a linear project like this, he says, “incorporating a sediment pond and having continuous erosion control is one of the most important things they can do as they develop the highway.” This includes near-immediate reseeding as crews move along, he says, which is all part of his mandate for better project planning.

The hydroseeding crews should plan to be in place “following the contractor as they go down the road, not four months later—this fast turnaround in revegetation can go a long way with erosion management and it improves the look of the project as well,” he says. EC_bug_web

Early Inspiration for Stormwater Management

Founded on a harbor of the western coast of the Chesapeake Bay, colonial Baltimore began experiencing runoff and sediment issues as early as 1729. Sediment had stopped up inlets, land-locking ports and affecting all commercial activity. Dredging was required to maintain commerce and provide supplies. While the early colonists may not have been aware of it, Maryland is the only state in the US that lacks a single natural lake. Therefore, all Maryland waters drain to the Chesapeake Bay, with runoff literally coming to the bay from everywhere. According to existing records, by 1873 the growing city of Baltimore had installed a 1,700-foot-long, 5- or 6-foot-diameter storm sewer pipe to handle the runoff.

But that wasn’t enough.

The Jones Falls River that ran through the city—and whose racing waterway was channeled for factories and mills in the second half of the 19th century—quickly became legendary for its sewage and industrial output, giving the city a dubious distinction of having the highest typhoid fever rates in the country. When a massive engineering effort was finished in 1915, the Jones Falls had been channeled into a huge culvert with its outfall at the Inner Harbor.

But the Great Baltimore Fire changed everything, providing both the incentive and opportunity to fix the burgeoning water management problems. With half the city burned to the ground, Baltimore realized a chance to improve its infrastructure. Reputed to be the first of its kind in the US, a separate storm and sanitary sewer system was approved by voters in 1905, and a treatment facility for human and industrial wastes was built.


Jerry Fifield and Tina Evans of HydroDynamics offer a multipart webinar, “Effective Sediment and Erosion Control Plans for Roadway Projects,” through Forester University. See www.foresteruniversity.com for more information.

 

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