Officials are beefing up efforts to educate contractors about controlling erosion and sediment on slopes and enforcing the EPA’s Phase II stormwater runoff regulations. Here’s some advice from experts to help keep you out of hot water.
Four years after the EPA began implementing regulations to limit the amount of sediment in stormwater runoff from construction sites 1 acre or larger, there’s still plenty of room for grading and excavating contractors to improve their erosion and sediment control practices on commercial and residential development projects, say stormwater management experts.
The Phase II rules of the EPA’s National Pollutant Discharge Elimination System (NPDES Phase II), which became effective in early 2003, require operators of a construction site that disturb between 1 and 5 acres of land with such activities as clearing, grading, and excavating to obtain a permit before allowing stormwater runoff to leave the site. (In some areas, local agencies may require a permit for construction sites that disturb less than 1 acre. Permit requirements for operators of construction sites that disturb more than 5 acres are covered by similar Phase I rules, which have been in effect since the early 1990s.)
Under the Phase II rules, the holder of the permit, who may be the project owner, developer, or contractor, must minimize the amount of sediment carried offsite in stormwater runoff from slopes by using best management practices (BMPs). These include such measures as mulch to protect bare slopes from the erosive impact of raindrops, silt fences or brush barriers to trap sediment in runoff from slopes, drainage swales to direct runoff away from slopes, check dams to reduce erosion of drainage channels, inlet filters to keep sediment out of storm drainage systems, and temporary and permanent vegetation to control erosion of slopes and drainage channels.
It’s taken some time for the federal, state, and local authorities to begin implementing the Phase II rules and educating grading and excavating contractors on the program. As these agencies step up enforcement of the rules, they’re finding more violations of the rules by project owners, developers, and contractors.
Attitude Adjustments
In some cases, the difference between contractors who comply and those who don’t may reflect a difference in priorities, notes Mikael Isensee. As the urban conservationist with the Dakota County Soil and Water Conservation District in the Minneapolis–St. Paul, MN, metropolitan area, he oversees inspection of more than 300 active Phase II construction sites each year. By his estimate about half the contractors on these sites understand the Phase II rules. And the rest?
“They probably have a different set of priorities,” he says. “If the performance evaluations of site supervisors are based in part on how well they manage erosion and sediment control during mass grading operations, then they have a good understanding of Phase II. However, if erosion and sediment control activities are lumped under a supervisor’s general responsibilities and the company is not providing any training in this area, then erosion and sediment control tends to drop by the wayside.”
In other cases, lack of compliance with Phase II may reflect inadequate enforcement due to an insufficient number of inspectors to cover all the construction sites in a given jurisdiction. Certified Professional in Erosion and Sediment Control (CPESC) Shirley Morrow offers a national perspective on this issue. As a senior environmental scientist with Tetra Tech EM Inc., an engineering consulting firm in Lenexa, KS, she trained municipal and state agencies around the country in erosion and sediment control practices.
“Sometimes, it takes enforcement to get people to follow the rules,” she says. “If you’re not complying with Phase II requirements, you’re likely to be caught at some point by a federal, state, or municipal inspector. Ask yourself, ‘Is it worth the risk not to comply?’ Once you’re found in violation, I, as a consultant, can’t help you. The fines can cost you thousands of dollars.”
For example, in 2005, five contractors in Dakota County, MN, were cited for violating Phase II and assessed penalties averaging $10,000, reports Isensee. The Phase II rules call for penalties of up to $32,500 per day per violation. Nationwide, fines totaling as much as $500,000 and more for non-compliance are not unheard of.
Even if a violation doesn’t result it a fine, it can still take a financial toll on your grading and excavating profits. Without proper slope protection, sheet or concentrated flows over the slope can create small rills, which can quickly become large gullies. Repairing them can require the additional expense of backfilling and re-dressing the slope. Drainage channels also require appropriate measures to resist the erosive forces of flowing water.
“Correcting a violation often ends up requiring more erosion and sediment control measures and expenses than preventing the problem in the first place,” Isensee says. “For example, often it requires immediate action, and calling out an erosion and sediment control contractor on short notice usually involves extra charges.”
Planning for Success
The key to minimizing erosion and sediment control problems on a construction site is to get the slopes to final grade and final stabilization as soon as possible. For all but the steepest slopes, that usually means establishing a permanent vegetative cover over the soil so that the stems and leaves of grass and other plants can cushion the impact of raindrops and slow runoff, while root systems help anchor the soil in place.
Typically, the NPDES permit requires that any area not disturbed for 14 days—cut-and-fill slopes as well as stockpiles of soil—must be stabilized, at least temporarily. In some places, such as Florida, this requirement drops to a seven-day minimum.
Before tackling the challenge of stabilizing slopes and, for that matter, drainage channels on a construction site, it makes sense to know the rules. Many states publish BMP manuals that describe standards and specifications that must be followed in installing and maintaining erosion and sediment control measures. All states also require a stormwater pollution prevention plan or similar description of how erosion and sediment will be controlled as one of the conditions for receiving an NPDES permit.
“The project owner should provide a plan for complying with Phase II and the grading and excavating contractors should follow it,” says Isensee. “You can help protect yourself from a violation by understanding this plan. Study it and bring any shortcomings you see to the attention of the project owner and design engineers for them to correct.” The information in this plan can also help in designing and altering the stormwater drainage system, another key component of the overall erosion and sediment control plan for the site, as grading and excavating activities change the topography during the project.
“Stormwater runoff has to go somewhere,” says Isensee. “Failure to plan the drainage system and to stabilize drainage channels is a common problem, especially on large construction sites. The trick is to have a rapid stabilization plan for defined drainage paths before construction activities begin.”
More Protection
Often erosion and sediment control is a single bid item in a project plan. It is critical for grading and excavating contractors to examine the bid documents for separate items for temporary and permanent erosion control. Temporary erosion control is required to protect exposed soils from the erosive forces of precipitation or flow.
Exposed soil areas that will not be actively worked for 14 days but will be re-disturbed before final vegetation is established require temporary cover. Often, however, all erosion and sediment control measures are included as a lump sum bid item, Isensee notes. As a result, many grading and excavation contractors base their bid only on providing erosion control when establishing the final vegetation and incur significant additional expenses providing large quantities of required temporary erosion control.
“We feel very strongly that both temporary and final erosion and sediment control practices should be included as separate line items in the bid documents,” Isensee says. “Otherwise, the grading contractor becomes financially responsible for any erosion and sediment control problems that occur before the final vegetative cover is established. Bidding on the basis of both temporary and final practices also helps level the playing field by ensuring that conscientious contractor doesn’t lose the project to a contractor who bases the bid only on final erosion and sediment control.”
Preventing Trouble
The best way to limit the stabilization work is to limit the amount of area disturbed at any one time.
“When clearing a site, don’t denude the entire area of vegetation at once,” Morrow advises. “Remove only as much as you have to, and get that area to final stabilization before moving onto another area of the project.”
However, that approach requires phasing the project, which contrasts with traditional land clearing practices and complicates the construction work. For example, at one time it was customary to follow an easy path by waiting until after all final cuts and fills have been made and all the roads and utilities have been installed on the whole project before calling in a landscaping contractor to put in the permanent vegetation.
“Phasing offers a big opportunity to limit your exposure to erosion and sediment problems by stabilizing slopes and other trouble spots earlier in the project than has normally been done in the past,” Morrow says. “It costs more time and money because you have to call in the erosion control or landscaping contractors several times throughout the project. However, it can pay off with much more effective and, ultimately, less costly erosion and sediment control over the long run.”
The preventive approach also holds for temporary slope stabilization methods, such as protecting the soil with straw mulch.
“Timing is everything,” says Alex Zimmerman, CPESC. “Get the slope stabilized before the rain starts.”
Whatever your choice of temporary stabilization practices, they should match the job, he adds. “It can become a balancing act,” Zimmerman says. “For example, in the case of a temporary vegetative cover, the site should remain undisturbed long enough for the vegetation to become established. That, in turn, depends on several variables, such as type of seed, time of seeding, and availability of any needed irrigation.”
Proper planning for erosion and sediment control can also help ensure that the job is done right the first time.
“The idea is to put all the BMPs together in a way that the site stays together,” Zimmerman says. “Your success in getting another job with the developer can depend on how well you do that. After all, you don’t want the slope unraveling after you leave the site.”
Making the Plan Work
Here are other tips on some of the steps you can take to help ensure your success in complying with Phase II requirements on your grading and excavating projects.
Protect exposed slopes from stormwater flows—Install a small berm along the top of the slope to direct water to slope drains for conveying concentrated flows across and away from slope faces, says Steve Gucciardi, CPESC. He’s senior erosion control coordinator for the City of Charlotte, NC, Erosion and Sedimentation Control Program. This program has been honored by the International Erosion Control Association for its effectiveness in protecting water quality.
He suggests using black corrugated plastic pipe for the slope drains.
“If you’re unsure about what size of pipe to use, it can pay big dividends to have an engineer calculate the correct diameter,” he says. “The bigger, the better.”
He points out that the drainage plan for the project may not include all the interim changes before the final grade is achieved. In the meantime, you may be facing some unexpected concentrated flows on your project.
“As topography changes during the course of construction, you may end up with water being channeled somewhere else between different phases of the project,” he says. “Anticipate these changes and develop a plan to control them when they appear.”
Stabilize drainage channels—Just as Phase II requires that slopes be stabilized in a timely manner once construction activity ceases, even temporarily, drainage paths must also be protected from erosion before the rains hit.
Specific time frames tend to vary from one government jurisdiction to another.
In Minnesota, for example, all drainage ditches and swales must be stabilized 200 feet before the point where they discharge stormwater offsite within 24 hours after earth-disturbing activities end.
“Typically, that might include such BMPs as construction check dams and/or lining the swale with temporary or permanent vegetation and, if needed, protecting the seeding and vegetation with a temporary a erosion control blanket or a permanent turf reinforcement mat,” Isensee notes.
To perform properly, these and other products must be installed according to the manufacturer’s recommendation, adds Gucciardi. “For instance, if erosion control blankets aren’t keyed in properly at the top of a slope, stormwater runoff will flow under the blanket, creating rills and gullies which remain out of sight until they create a large failure of the slope.”
Get seed off to a good start—Prior to seeding a slope, Gucciardi recommends running a dozer or other piece of tracked equipment up and down a slope. This dresses up the slope for improved seeding success by leaving horizontal track imprints instead of a smooth surface. “The track marks become repositories for seed and act like mini-check dams to dissipate concentrated runoff to promote a slower, less disruptive sheet flow across the slope,” he says.”
Here, again, it pays to follow directions. “I’ve seen operators run the tracks across the slopes instead of up and down,” he says. “That leaves vertical track marks, increasing the chance of washing away soils and seed from formation of rills and gullies.”
In addition to tracking the slopes, Zimmerman has been impressed by the results of covering the ground with a blanket of compost before seeding. “The data keep getting better and better about the value of compost in providing a good organic growth medium and control of erosion,” he says.
Use topsoil wisely—After removing the topsoil during grading and excavating activities, savvy contractors stockpile it and then spread it back on the slopes to aid the establishment and growth of erosion control vegetation once the dirt work is completed.
“A pet peeve of mine is that many contractors don’t make the best use of topsoil,” says Morrow. “Efforts to grow vegetation for temporary or permanent erosion control won’t be very effective if you’re seeding directly on subsoil. You need the microbial life and organic matter in the topsoil for best results.
Zimmerman notes another benefit of topsoil. It helps improve post-construction stormwater management. “Topsoil absorbs and holds water much better than subsoil, to reduce stormwater runoff.”
However, Gucciardi cautions, adding topsoil on top of clay may require extra care to keep the topsoil in place, especially if slopes are long and steep.
“In a natural setting, tree roots can penetrate into clay to help hold the overlying topsoil in place,” he explains. “But, when you cover a bare clay cut slope with a layer of topsoil and seed it to grass, the shallow root system of the grass usually won’t penetrate far enough into the clay to hold things together and the topsoil can slough off.”
In these cases he recommends one of two approaches: Build terraces on the slope contours before seeding (they reduce the potential for erosion by creating a series of shorter slopes that slow stormwater runoff and help trap sediment), or protect the slope with materials like coir erosion control blankets, turf reinforcement mats, or cellular confinement systems that provide harder armor than an erosion control blanket made of straw.
“Any time you’re dealing with two dissimilar types of soils, particularly on long, steep slopes, it’s a good practice to involve a geotechnical engineer to help with stabilization practices,” Gucciardi says.
Voice your concerns—If you have thoughts on how requirements of the NPDES permit can be changed to better fit your operations without compromising the purpose of this program, you may have an opportunity to help modify them.
In many states, the original NPDES Phase II permit, which governs their erosion and sediment control programs, will expire within the next year or two. This provides an opportunity to make program improvements to increase compliance rates and administrative efficiencies of the programs.
Finally, call and work with local regulators before beginning construction. In Minnesota, Isensee and others are responding to contractor concerns by working with local units of government to improve erosion and sediment control plans.
“The desirability of including temporary erosion and sediment control practices in the project bid is one area that we are working hard to resolve, “ Isensee says.
“By working with and educating city, county, and state authorities we are increasing the number of projects that provide quantities for all temporary and permanent erosion and sediment control practices. Now, it’s time to bring the private sector up to speed.”