Application Tips: Erosion control

Controlling water pollution and erosion at construction sites is a big, complicated issue.

The U.S. Environmental Protection Agency has a plethora of regulations pertaining to storm water management and erosion control. And with all you have to deal with on a daily basis, memorizing pages of rules probably isn’t the first thing you do during downtime.

But a lot is at stake here. “If you’re not compliant to the erosion control standard, you might be shut down,” says Scott Bruce, president and owner of Spread Rite Organics, a company that specializes in erosion control. “It’s a complex issue, but erosion control is something you have to do because you are mandated.”

According to the EPA, sediment accounts for more than two-thirds of all pollutants entering U.S. waterways. This pollution can cost taxpayers millions, and this cost can come back to contractors who aren’t compliant. For each violation of the regulations, you could pay up to $25,000 per day.

“You have to be aware,” says Maria Tegeler, technical services assistant for North American Green, a producer of erosion control products. “All the pollution in the water means the EPA has put the hammer down to regulate better.”

Fortunately, there are plenty of resources to help you understand the rules. One way to stay compliant is to understand the equipment used in erosion control. Three specialized tools – silt fences, hydroseeders and blower trucks – can be particularly helpful in battling soil runoff.

Silt fence machines
Silt fencing is a common fixture on many worksites, particularly where there is danger of sediments spilling into a stream or sewer system. The principal function of a silt fence is to slow and pool water in order to allow soil particles to settle, but it is not designed to withstand high water levels.

Despite its effectiveness, a silt fence can be a hassle to install. The traditional method is to dig a trench and either work the silt fence into the ground and then install the posts, or install a prefabricated silt fence with the posts already attached. The main problem with installing silt fence this way is it’s time-consuming and difficult to do correctly. The most common causes of silt fence failure are allowing excessive drainage, digging trenches that are too shallow for the silt fence or improperly attaching the posts.

Another method of installing silt fence is to use a silt fence attachment. Several companies manufacture these attachments, and they all do basically the same thing: bury the lower portion of the silt fence in the ground using a slicing technique that eliminates the need to trench. A silt fence machine can be attached to a utility tractor or a skid steer.

“It slices silt fence into the ground so you can get in there good and tight,” says Chris McCormick, owner of McCormick Equipment, which makes a silt fence attachment. “Then you come and put your posts in to stake the fence up.”

David Hermann, president of Applied Turf Products, a company that sells Finn brand erosion control equipment, says a silt fence attachment can install 4,000 to 5,000 feet of silt fence a day. “Using the old method, someone will put in about 200 feet per day,” he says. “At that level, they are usually only working small jobs. Either that or they haven’t seen the productivity of a silt fence machine.”

These machines use hydraulics to apply a mixture of seed, fertilizer, tackifier, polymer and some type of bio-stimulant to prevent moisture loss, provide some protection from wind and rain and promote germination in soil.

The hydroseeder is equipped with a large tank and cannon. The benefit of hydroseeding is that organic mixtures can be applied in one pass, and the stickiness of the mixture – which resembles creamed spinach – holds it in place on the ground. The mixture is applied over bare soil and allows grass to take root quickly.

“Hydroseeding is probably the most widely accepted because it is a one-pass operation,” Hermann says.

Blower Trucks
The purpose of a blower truck is the same as that of a hydroseeder: to apply organic material to soil. The difference between the two is that while the hydroseeder applies organic material in a wet mixture, the blower truck does it with a dry one.

The truck is equipped with a tank and uses air pushed through a hose that ranges from 300 to 500 feet in length. Blower trucks can cover the ground with straw, bark and sometimes sod.

The hose can make the blower truck cumbersome to use, especially when the jobsite contains steep grades or hilly terrain. A hydroseeder might be a better choice in such applications.

“There is going to be a time with the blower truck when someone won’t be able to walk up a very steep hill with 300 pounds of material in that hose,” says Hermann. “With the hydroseeder, you can apply it with the hose on the cannon.”

Hermann says it isn’t uncommon for an environmental contractor to have all three types of erosion control equipment in his arsenal to account for the limitations of each.

Erosion control primer
It’s not possible to detail the EPA’s regulations in a few pages, but these are the basics of erosion control.

The EPA’s National Pollutant Discharge Elimination System rules went into effect in two distinct phases.

Phase I was developed in 1990 as a response to amendments made to the Clean Water Act in 1987. This phase was designed to address sources of runoff that could negatively impact water quality. EPA required permit coverage for storm water discharges from medium and large municipal storm sewer systems located in incorporated municipalities or counties with populations of 100,000 or more. Phase I was also meant to regulate eleven industrial activities, including construction at sites larger than five acres.

Phase II went into effect in March 2003. It expands on Phase I by requiring a permit for storm water discharges from small municipal storm sewer systems and construction sites that disturb between one and five acres of land.

Phase II rules require you to:

  1. Submit a notice of intent including general information and certification the activity will not impact endangered or threatened species.
  2. Develop and implement a storm water pollution protection plan with best management practices to minimize discharge of pollutants from the site.
  3. Submit a notice of termination when final stabilization of the site has been achieved as defined in the permit or when another operator has assumed control of the site.

Internet resources:
The best way to stay in compliance with EPA regulations is to be educated. Below is a list of resources that can help you on the way to work site compliance.

Environmental Protection Agency NPDES page

NPDES general permit fact sheet

Silt fence alternative?
While it’s not necessarily a replacement for silt fence, a cofferdam system uses a wood or steel frame and waterproof fabric to retain or divert water on a site. The drawback to using a cofferdam only for erosion control is that it is not cost effective.

“It would be a costly replacement for silt fence,” says Gerry Mann, national sales manager for Portadam, a company that sells a portable cofferdam. “It does the same thing but a whole lot more. If all a contractor has to do is retain turbidity on a site, then it would not be a cost effective alternative. But if he or she is looking to dewater the site, that is an added benefit.”

A full description of Portadam’s cofferdam system is at this site.