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If your erosion control plan at your wind farm were to be graded, what type of grade would it receive? Given all of the potential devastating effects from erosion, wind owners and operators should aim for an A and take every necessary step they can to minimize damage and protect their projects. The past decade of droughts and catastrophic wildfires have left parched landscapes ill prepared, so site assessments and maintenance practices are particularly critical. Many wind energy projects are built in mountain passes, where mudslides are a looming danger, while others are built on or around dry lakebeds, where land is inherently flat and soil peculation is minimal. Either way, this typically means that even a minimal amount of rain can create a maximum amount of problems.

 

Protect the site first

Water always behaves the same way – it seeks its own level. What does change is the topography and elevation in the settling points. As soil is deposited, it diminishes the volume of a drainage route or a retention basin. Therefore, drainage routes and basins must be cleared of obstructions, dirt and debris that may have accumulated. Flow channels, swales, riprap beds and culverts need to be cleaned out to allow unrestricted water passage. In addition to removing debris, trash and silt buildup, contractors in operations and maintenance (O&M) should make any repairs necessary to drain grates, catch basins, inlets, channels and roadways to ensure storm water flows freely. Pay close attention to culverts under roadways using adequate lighting to ensure unobstructed water passage can occur. Maintain a channel cleaning and maintenance program that addresses vegetation trimming, debris, sediment and trash in those flood channels.

On a smaller scale, blockage in culverts can lead to similar damage, causing water to flow over roadways and also erode or destroy site-access infrastructure. To help prevent this, swales or drainages leading into basins must be intact and capable of carrying storm water at a controlled rate. A breach in a drainage route or flow path negates the design capabilities to move water across the property or into an appropriate catch basin. A good rule of thumb to follow is “inspect what you expect” by looking at the “story marks” on the property from the last wet weather event.

 

Mudslides and more

Mudslides are a looming danger for projects that can come with heavy rains – especially after a severe drought, as we have experienced in the western U.S. Because water flows and ends at the lowest point by diverting around or destroying any mitigation measures, operators need to ensure that best management practices are in place and water is allowed to flow. One way to protect a project substation in a low-lying area is by placing a diversion (dirt berm) that will train the water flow around the area rather than through it. This can help minimize the extensive work and cost involved with cleaning a substation damaged by a mudslide.

Another great tool to minimize damage to wind energy projects is a Tiger Dam, a quick, versatile and reusable system for extreme conditions that helps provide added flood protection to projects in areas where storm water can rise rapidly during rain events. A Tiger Dam section spanning 50 feet can be installed in only a few minutes and can perform the same function as 500 sandbags. The system involves 50-foot sections of water-filled bladders that can be used individually or linked together to form a continuous protective barrier over longer distances.

Tiger Dams can be reused from year to year and storm to storm to provide added efficiency, and they can be installed within very quick time frames to provide added flood protection where storm water levels may rise. This additional tool can be used at projects that experienced “over-topping” during rain events in 2010, when storm water rose slightly above the flood channel walls and onto adjacent roadways and property.

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Hydroseeding

Good erosion control measures will go a long way when it comes to preventing or controlling wind and water erosion on wind energy projects. Vegetation, such as grasses and windflowers, and other materials such as straw, fiber, stabilizing emulsion, protective blankets, mulch and more are placed to stabilize areas disturbed by grading operations, reduce loss of soil due to the action of water or wind, and prevent water pollution.

Hydroseeding is a quick, cost-efficient way to apply seeds, mulch and fertilizer to recently disturbed soils found on any construction project. The value of hydroseed can be seen in both erosion control and dust mitigation. It’s also an effective revegetation strategy. Selecting the right contractor is always important, as is ensuring it has trained applicators who have sprayed on wind energy projects. Seed mix, mulch rate, fertilizer, application uniformity, overspray mitigation and other factors need to be well thought out. Selecting the right seed mix for your projects’ climate and soil content and working with an unbiased consultant to help determine the appropriate seed is also important. The seed mix can change your price per acre by hundreds of dollars. With projects ranging from 20 acres to 2,000 acres, this can be a significant savings.

When using hydroseeding, consider the following:

 

More tips

In addition to site preparation steps such as hydroseeding, it is just as essential to develop an equipment and materials checklist for the wet weather season. This should include materials on hand such as sandbags, shovels, plastic five-gallon buckets, plastic sheeting and tarps. Equipment needs should include portable water pumps with the appropriate suction hoses/strainer and discharge hoses, a generator, and lights.

Here are some additional preparation steps to include in your plan:

Facilities must review the regulatory requirements as dictated by the site-specific Storm Water Pollution Prevention Plan to gain a detailed understanding of expectations for water retention and pass-through, sampling frequencies, testing, and record retention. With this knowledge, the next step is to create a standard operating procedure (SOP) for wet weather events and develop personnel training so that adherence to the SOP becomes procedure-driven companywide. Implementing this gives contractors in O&M time to set up vendor support agreements to assist if the water intrusion is more evasive than the site and staff can effectively manage.

Although there is no way to predict exactly how much rainfall we might see in any given year, and how that will affect a site in terms of erosion, what we do know beyond a doubt is that preparation now will reduce potential damage. Wind energy professionals, especially on the O&M side, need to take time now to set up vendor support agreements to assist if water intrusion and potential erosion are more evasive than the site and staff can effectively manage.

 

Travis Dees is the wind division director at World Wind & Solar, a renewable energy services provider. He can be reached at tdees@worldwindservices.com.

Environmental Protection

How To Prepare Your Site For Flood, Debris And Erosion

By Travis Dees

Check out these tips to minimize damage from stormy weather.

 

 

 

 

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