Sheetflow Construction Turbidity, Erosion, & Sediment Control

July 3, 2018

Clean Water Diversion Using Jersey Barrier and Asphalt Berm

Filed under: Video — Sheetflow @ 7:00 am

The more clean water you keep from flowing into your job site, the less dirty water you will have to manage. Placing a berm along the base of “Jersey Barrier” is one way to accomplish this. Materials you can use include cold patch, extruded asphalt curbing, or sand bags.

June 20, 2018

Pump, Plug and Infiltration Pond Used to Dispose of Turbid Water

Filed under: Video — Sheetflow @ 7:43 am

Construction erosion and sediment control is really just temporary management of stormwater until the permanent, post-construction stormwater system is functional. Stormwater from this 3 acre site is managed by pumping turbid runoff to an on-site, infiltration pond.

May 14, 2018

Geotextile and Foam Check Dam Bad Installation

Filed under: Video — Sheetflow @ 7:00 am

Yet another example of poorly installed and maintained check dams. Even worse, it’s hard to install geotextile and foam check damsincorrectly. Here is an installation detail to use as a guide for proper installation:Geotextile-encased Check Dam

April 7, 2018

Pipe Slope Drain is Too Short

Filed under: Video — Sheetflow @ 7:08 am

Pipe slope drains are a great best management practice for conveying water down to the base of a slope. Water allowed to flow over a slope will cause rills and gullies to form, depositing tons of sediment at the bottom of the slope. This clip shows a good application of a pipe slope drain, except the pipe doesn’t go to the base of the slope.

March 1, 2018

Raindrop Impact in Slow Motion

Filed under: Video — Sheetflow @ 7:00 am

Researchers from Vanderbilt University have shed new light on the process of water erosion by analyzing slow motion images of rain drops striking sand grains.

February 15, 2018

Straw Wattles Reduce Erosion on Slopes

Filed under: Video — Sheetflow @ 7:04 am

As water runs down a slope, it starts as sheetflow. If left unchecked, the water picks up velocity and erodes, forming small channels called rills. If the rills are left unchecked and the water flow continues to increase in velocity as it runs down the slope, it begins to form gullies. At this point, significant erosion is occurring. Straw wattles placed on a slope, on contours and at regular intervals, will intercept flowing water, reducing its velocity and reducing erosion. Straw Wattle Installation Drawing

January 20, 2018

Straw Wattles on Slope in Rain

Filed under: Video — Sheetflow @ 7:00 am

Here is another example of the benefits of using straw wattles on a slope. For another example, go to last week’s post.

December 10, 2017

Extruded Asphalt Curbing as a Best Management Practice (BMP)

Filed under: Photo — Sheetflow @ 7:00 am

Here is an an example of extruded asphalt curbing being used as a barrier to keep storm water out of the construction area, on the left, and keep site water from flowing outside the project, to the right. In this case, the non-project water is dirtier because the paving is broken up and equipment is driving through muddy areas. The object of the construction project is to grind existing, poor, asphalt, rebuild the base using the ground asphalt, then lay new asphalt over the top. This is being done in phases to keep from opening up too much area as this work is being done in winter.

Click on the image for larger size.

November 25, 2017

Guide to Handling Fugitive Dust from Construction Projects

Download: Guide to Handling Fugitive Dust from Construction Projects.PDF

The classic brochure developed in 1997 by the Associated General Contractors (AGC) of Washington Education Foundation and the Fugitive Dust Task Force, Seattle, Washington. Updated and edited for the Internet by: www.sheetflow.com, February 2009.

October 20, 2017

The More Grass the Cleaner the Water

Filed under: Video — Sheetflow @ 9:42 pm

The Clean Water Act requires construction sites to meet water quality standards. One of the standards is turbidity, the measure of the cloudiness of water. Turbidity is measured in NTUs, nephelometric turbidity units, using a turbidity meter. The turbidity meter shines light through a water sample and measures the light intensity difference between the light emitter and collector; the cloudier the water, the higher the NTUs. The chief cause of turbidity in construction stormwater runoff is fine soil particles; fine silts and smaller. Persistent turbidity is caused by colloidal soil, particles which are so small the soil particle’s negative electrical charge is stronger than the force of gravity. This causes the particles to remain in the water column for long periods of time. Particles of this size do not settle out. The best way to keep the colloidal particles from entering stormwater is to protect the soil surface, both from the force of raindrop impact, as well as the shear stress of flowing water. Vegetation is the single best way to protect bare soil from these forces; the more vegetative cover the better. In this video, the affect of grass cover is apparent. Turbidity samples, taken from runoff from a grassy area with 70 to 80 percent soil cover is under 25 NTUs, the allowable discharge number.

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