Wednesday, December 12, 2012

High strength raschel knitted geogrids

Geogrids are good all-round materials used in the construction sector. They are used to separate adjacent types of ground, remove solid components when used as filters, absorb liquids over a wide area, prevent soil erosion and provide mechanical protection.
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Undue erosion and sedimentation from land disturbing dealings have been linked to serious land and water management issues, which are a large concern to the county residents. Of course, one of the most common ways to prevent erosion is to plant vegetatio. Plants act as protective shields that can lessen the impact of rainfall that can loosen the soil. Good water drainage also helps lessen erosion because it diverts excessive watering. 

In the United States, said a report by the U.S. Climate Change Science Program in January 2009, "rising sea levels are submerging low lying lands, eroding beaches, converting wetlands to open water, exacerbating coastal flooding, and increasing the salinity of estuaries and freshwater aquifers
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"The big gorillas in terms of sea level are Greenland and Antarctica," polar glacier scientist Eric Rignot told Gary Braasch for his book Earth Under Fire

Saturday, August 18, 2012

Stabilizing Surficial Slope Failures

 Surficial failures

Surficial failures occur frequently on the slopes of earthen embankments and earth fill dams which are predominantly rainfall induced.

                              Unstable slopes

 Unstable slopes create numerous management and engineering issues as we try to prevent slope failure.
Based on the literature review and interviews conducted with selected state highway engineers, researchers identified three innovative methods of using vertical members to stabilize surficial slope failures:
• Installing small structural members by conventional methods.
• Installing launched soil nails.
• Installing earth anchoring systems.
Investigators also determined that some of these methods are more cost-effective than conventional repair methods.


 Vegetation as an ecotechological solution can assist us in preventing slope failures. 
Vegetation is unlikely to have a significant impact on slope stability where slope planes are deep-seated, due to the shallow nature-of many species. 
However vegetation may protect the ground surface from erosion by wind and water and prevent erosion at the toe of slopes where the slope is being undercut by wave action in water courses.
The stability of the toe of a slope, stabilized by vegetation, may be sufficient to maintain the stability of the slope as a whole (Coppin and Richards 1990: Gray and Sotir 1996).
 Deforestation and wildfires on hillsides and valley slopes may also lead to increased soil erosion. The streams and rivers that meander and flow down theses slopes may undercut the hill-slopes and cause bank instability.  
Ground bio-engineering : the Use of Vegetation to Improve Slope Stability,  is an accepted engineering technique for stabilizing bank erosion.
You may reduce erosion and sedimentation by rapid re-vegetation of areas disturbed by harvesting operations or road construction.

                        Eco-engineering methods

Eco-engineering methods are particularly suited to natural slopes, where management is generally long term and the site is large-scale.
Artificial slopes or earthworks are either cut into natural rock or soil or built up to form embankments, dams, water tips or spoil heapes. 
Vegetation could be used for stabilizing cut slopes, soil embankments , water tips, spoil heaps and terraced slopes.  
On the other hand plant life is less likely to be of value in dams where engineering stabilizability is critical and vegetation could affect soil permeability. 
Ground bioengineering techniques are commonly used on artificial and terraced slopes, as this fast and effective solution should be considered during slope construction and remediation-ecological enhancement of earth structures. 
Vegetation provides protection and stabilization of both natural and man-made slopes along transportation routes.


 Embankments typically occur along highways, railways and canals and are made from materials such as soil or rock excavated from elsewhere and placed on natural ground.

Slope failure in embankments during and after construction is sometimes associated with the interface between the natural ground and the fill material. Pore water pressures and seepage within the embankment and natural ground may exacerbate slope failures.  
A suitable combination of vegetation types, e.g. willow pole, can help to stabilize embankments  that may be prone to the shallow translational slide failure  (Croppinj and Richards 1990). 
Vegetation may help to stabilize the toe of deeper slips. For deep seated slides,  a combination of geosynclines and vegetation may be more  appropriate.

                   Effects of terraces on erosion

Terraced slopes are common features in many parts of Asia (Storey 2002).
Built to conserve soil and water on steep slopes for a variety of agricultural uses, but if not implemented correctly, soil loss may be rapidly increased. 
For example, if hill terraces for the cultivation of crops are poorly constructed or maintained, topsoil erosion and slope instability will be exacerbated  through water collecting on overstepped terraces(Sidle et al. 2006).
Abandonment of terraces can result in the loss of vegetation  and root  reinforcement thus leading to an increase in the rate of soil erosion (Goudie 2000;Commeraat et al 2005;van Beck et al. 2005).
If the terraces collapse, breaches will focus surface runoff leading to gully formation and increase sediment transport down slope (McConchie and Ma 2002)


Wednesday, March 7, 2012

Minnesota sealant firm takes stand vs. pollution

An Eagan-based company that is a national leader in driveway coating said Friday that it will stop using coal-tar-based sealants to help curb chemical pollution in stormwater ponds.

Jet-Black International said its franchisees in Minnesota and Wisconsin will switch to newly developed asphalt-based coatings by next year. The company said it also has recommended that its franchisees in 10 other states make the switch.

"We are concerned that continued use of coal-tar sealants will lead to unsustainable and costly pond clean-ups at the expense of the citizens of Minnesota," the company said in a statement.

The company's voluntary switch is a victory for pollution control officials, who have campaigned to end the use of coal-tar-based sealants, long an industry standard. An estimated 85 million gallons of the sealants are sold annually.

"They are doing the responsible thing," said Tom Ennis, an engineer who works for the city of Austin, Texas, and tracks the issue on a blog called Coal Tar-Free America. "It is what we who have worked on the science have been waiting for. If the industry just looks at the facts and stops arguing, then real progress
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Thursday, March 1, 2012

FG to invest $500m World Bank loan in erosion control

THE Federal Government has said it plans to use a $500 million World Bank loan to tackle erosion in some states across the country, using the watershed approach.

Director of Flood and Erosion Control, Federal Ministry of Environment, Mr. Adekunle Oshikoya, while making this known in an interview with newsmen in Abuja on Thursday, added that, ‘The approach under this World Bank programme is the watershed approach; we are trying to solve the degradation problem from the watershed view, which is holistic.
‘We are probably not going to look at individual erosion sites alone; we are going to tackle it holistically. That’s why the approach may be like a once and for all thing to solve erosion problem in the area.’
The director added that the executors and stakeholders of the project held two joint appraisal meetings, with a third scheduled for early March.

He disclosed tha