Erosion Control Materials for New Construction Storm Water Permit
Posted by Robert Ellenwood on Mar 18, 2015
In a post on “New Construction General Permit for Storm Water” (Rockblog, Tina Lau, 7/28/10), Tina writes that the New General Permit has increased the need for additional erosion control products and Best Management Practices. Here, we will breakdown the available products to assist in your storm water management plans. Depending on your Project Category Risk Level, most products will work with great success.
Managing Slopes and Stockpiles
Rapid surface runoff is the number one issue when it comes to accelerated soil erosion. The goal here is to reduce the velocity of water, whether airborne or the runoff after touching ground.
The best product to use to keep soil intact is a root system. Millions of acres of steep hillside remain intact for thousands of years due to the natural anchoring system of roots and vegetation. If your site has been cleared of vegetation for a project, it is best to duplicate whatever was there before when revegitating the site. If existing growth is not an option for completion of your project, then there are many varieties of seeds or rooting ground cover systems available to match your final landscape plan.
Protecting the Seed
Once your soil has been prepared and the seed is placed, how do we protect it from birds or wind blowing it away?
Hydroseed is a method using encapsulated seeds, binders and tackafiers to hold the seed in place and is ideal for large land mass or hard to reach areas.
Blankets are a great way to protect your seeds and holding them in place allowing successful germination. There are many blankets to choose from and you must know your slope conditions and length of time for managing your project. There are blankets for 4:1 low slope application, all the way to 1:1 steep slope application. The length of planned management will also determine the type of blanket you should use for the job. Companies such as North American Green provide a sprayed dot system showing you proper fastener placement based slope degree of you project.
Another means of slowing the velocity of runoff water is the use of wattles. Wattles are usually a rolled straw byproduct encapsulated in an open weave nylon mesh which will breakdown over time. Wattles are ideal for assisting the slowing of waters running down the hillside, it will also trap sediment on the backside of the wattle, which usually contains native seed and promote the growth of that seed, creating a natural berm.
Silt fence is a temporary product designed to trap any silt that may make it past your first lines of defense. This product should be maintained throughout the length of the project and removed according to your Storm Water Management Plan.
Drain Inlet Protection
Drain Inlet Protection is basically the last line of defense for storm water management. Drain Inlet or D.I. Protection can be a variation of products and must be inspected regularly. In most situations it will be a combination of products used such as a drain bag and gravel bags. The Drain Bag actually hangs into and captures any silt entering the drain and must be managed regularly. The Gravel Bags are heavy duty sand bags, usually made from woven geotextiles and placed around the drain inlet, stopping any sediment from entering the drain.
There are many other specialty products available for nearly all situations; the goal here is to use “Best Management Practices” with the guidelines to manage your storm water plan.
If you have any questions about a particular product you can reach me directly at 831-392-3759
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