Using Erosion Control Measures During Construction Activities

If your project falls under NPDES regs, the question isn’t whether but when and how you’re going to comply.

By Jerald Fifield

Are you ready for Phase II? If your reaction is "What is Phase II?" then it is safe to assume you’re not ready. However, if you know about the Environmental Protection Agency’s Phase II requirements, then you need to ask yourself, "Am I willing and ready to implement erosion control measures while construction activities occur?" All contractors should be ready since it will save them money!

Phase II Requirements

Beginning in 2003, if construction activities disturbed 0.4 ha (1.0 ac.) or more of land, a National Pollutant Discharge Elimination System (NPDES) permit will have to be obtained if stormwater is to be discharged from the site. If best management practices (BMPs) to reduce sediment in runoff waters are not properly installed, continually inspected, and maintained, holders of the NPDES permit may be subject to fines of up to $25,000 per day per violation and/or incarceration for up to two years. Obviously, the most important question for contractors is: What BMPs should be installed that will provide the greatest bang for the buck?

Erosion vs. Sediment

Is there a difference between a sediment control plan and an erosion control plan? Most definitely. If a contractor uses a set of drawings labeled "Erosion Control Plan" that illustrates the use of straw/silt fence barriers, sediment containment systems (i.e., sediment basins or traps), and rock check structures, then the designer has provided a "false sense of goods." These BMPs are used in an attempt to control sediment, all of which can be very expensive and ineffective.

If you are confused with definitions, here are three that all contractors must remember:

  • Erosion: The process by which, through the action of wind or water, soil particles are displaced.
  • Sediment: Eroded material suspended in water or in the air.
  • Sedimentation: The deposition of eroded material.

An important rule all contractors should also remember is: Good erosion control will result in excellent sediment control; however, sediment control never results in erosion control. Too many individuals think that methods for controlling sediment will result in effective protection of the environment from sedimentation. Usually the opposite occurs.

What methods are used to control sediment in runoff waters? Actually, none unless 100% of all runoff waters are totally contained. Some of the more common (and usually ineffective) structural BMP methods for reducing sediment in runoff waters while construction activities occur include the following:

Best Management Practice

Estimated Installation and Maintenance Cost

Estimated Effectiveness

Silt Fence Barriers

$19.70/linear m*
($6.00/linear ft.)

0-40%

Bale Barriers

$39.35—$65.60/linear m**
($12.00—$20.00/linear ft.)

0-10%

Rock Check Structures

$100/structure*

0-10%

Sediment Containment Systems

$500-$50,000/structure*

20-80%

* EPA (1998) estimated costs ** Projected from EPA (1998) values and actual costs

What does it take to control erosion? Again, no method will totally control erosion unless the surface is 100% impervious. However, some of the more common nonstructural BMP methods for minimizing erosion from rainfall, runoff, or wind that can be installed while construction activities occur includes the following.

Best Management Practice

Estimated Installation and Maintenance Cost

Estimated Effectiveness

Maintain Existing Vegetation

$0.00/ha (ac.)

90-99%

Temporary Cover Crop

$1,235/ha ($500/ac.)

55-65%

Perennial Grass and Mulch

$3,710/ha ($1,500/ac.)

80-94%

Slope Drains

$16.40/linear m* ($5.00/linear ft.)

100%

Drainage Swales

Grass
Riprap
Asphalt
Concrete

$2.50/m2 ($3.00/yd.2)*
$3.34/m2 ($4.00/yd.2)*
$37.62/m2 ($45.00/yd.2)*
$29.26/m2 ($35.00/yd.2)*

90-99%
90-99%
100%
100%

Rolled Erosion Control Products

Hillside
Channels

$1.50—$2.27/m2 ($1.25—$1.90/yd.2)
$2.57—$10.82/m2 ($2.15—$9.05/yd.2)

80-90%
80-90%

* EPA (1998) estimated costs

Review of the two tables clearly demonstrates that the effectiveness of erosion control methods is far greater than sediment control methods. Yet when one evaluates sites, the predominant BMPs used during construction activities are those associated with structural measures to control sediment. Why?

Some Reasons for Predominate Use of Structural Measures During Construction

  1. It is what appears on the plans. Unfortunately, this is may be the correct situation that clearly demonstrates the designer’s lack of knowledge of what it takes to develop an effective sediment and erosion control plan. Ironically, when contractors try to implement more-effective methods, their ideas and suggestions are often rejected by the designer or regulatory agency. Contractors need to (try to) work with designers and regulatory agencies to ensure they fully understand what is needed for effective sediment and erosion control on a construction site.
  2. I am not aware of the many methods available. This is a lame excuse! Contractors must get educated about methods to reduce sediment and minimize erosion on construction sites or else be prepared to pay some hefty fines in the near future.
  3. It is what we have always used. Another lame excuse. Heavy equipment eventually replaced the use of picks and shovels to effectively move larger amounts of soil. Why? To increase profits. Contractors using more effective methods for minimizing erosion and reducing sediment in runoff waters will also increase their profits.
  4. Sediment control BMPs do not cost as much as erosion control BMPs. On a short-term basis, this might be a correct statement. Once storm events occur and maintenance costs are continually expended, however, then long-term costs for sediment control far exceed what is paid out for erosion control. Look at the long-term costs for sediment and erosion control.
  5. We cannot implement erosion control methods during construction activities. Depending on the stage of construction, this statement may also be correct. For example, when heavy equipment is continually moving earth material, erosion control measures are difficult to implement. However, contractors should still assess the feasibility of installing erosion control measures during construction activities.

If any of the following questions can be answered by "yes," then an opportunity for implementing erosion control practices during construction activities can occur.

  1. Does all the vegetation have to be removed, or can removal be "staged"?
  2. When cut and fills are at the desired grade, can topsoil be immediately applied, seed planted, and mulch applied instead of waiting until the end of the construction activities?
  3. When final grade is achieved, can temporary grass be immediately planted?
  4. As lifts of soil are placed, can temporary slope drains be installed as the fill slope is being developed to ensure that runoff waters do not cause massive gully erosion?
  5. Can drainage ditches be stabilized against erosion by installing riprap or a rolled erosion control product (e.g., a turf reinforcement mat) immediately after they have been developed?

In summary, there is no reason why erosion control methods cannot be used while construction activities are occurring. They can be used in conjunction with properly installed and maintained sediment control measures to ensure maximum effectiveness in minimizing sediment from leaving a construction site in runoff waters.

Some Reasons for Implementing Erosion Control Methods During Construction

  1. Save money! Once erosion control practices are implemented, less maintenance costs will occur.
  2. Save money! If erosion is minimized, there should be little need to regrade the land or cut/fill slopes.
  3. Save money! If sediment is kept to a minimum, there should be no need to clean out culverts or remove material from downstream properties.
  4. Make more money! If contractors do not have to pay staff members for continual maintenance of structural (i.e., sediment control) measures, then greater profits will be realized.
  5. Make more money! If no fines for violations of Phase II requirements are levied, then contractors will earn more profits.
  6. Make more money! If contractors are known to be environmentally conscious, they will likely win more bids.

In summary, implementing erosion control practices during construction activities is a win-win situation. The environment wins and the contractor wins. So why not install erosion control BMPs during construction activities? All you will be doing is saving money.

Jerald Fifield is president of HydroDynamics Inc. in Parker, CO, and author of Designing for Effective Sediment and Erosion Control on Construction Sites and the newly published Field Manual on Sediment and Erosion Control Best Management Practices for Contractors and Inspectors.

 
 

 

 

 
 

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