Erosion Control – Ineffective Methods and What Actually Works

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New construction creates conditions that have the potential to cause slope destabilization, dangers to wildlife and fisheries habitats; stormwater runoff increases and results in increased sedimentation. Careful erosion control planning is required to ensure environmental stewardship and safety for generations to come.

In defining an effective approach to erosion control, one should take into consideration both the long-term effectiveness as well as financial feasibility.

The following approaches and methods of erosion control have proved to be ineffective for various reasons:

  1. rill erosion controlInadequate site assessment. Though not an end solution, the site assessment is critical when determining which method is used. When important aspects of the site conditions are not taken into consideration, inappropriate “solutions” may be prescribed.

    One example of a site condition is the steepness of the slope. The erosive forces of runoff increases with both slope gradient and distance down slope and therefore erosion is typically at it’s maximum at the lowest part of the steepest slope section. Not recognizing or taking into account the destructive force of water during seasonal runoff in scenarios with significant slope and distance will result in ongoing and increasing site erosion.

  2. A focus on sediment control (managing sediment that has already eroded) instead of focusing on the root of the erosion problem through prevention.Though silt fences and other sediment barriers may be effective in keeping stormwater and fisheries habitats from undue sedimentation, the approach should only be used temporarily. Filter socks like Denbow’s Filtersoxx can be used both as a temporary sediment barriers but also as part of a more comprehensive deployment of erosion control products.  Single application solutions, not comprehensive. These methods may provide partial or temporary results but are often not effective for the following reasons:
    • Engineered structures – Though usually immediately effective, engineered structures like block retaining walls, do not adapt to changing site conditions, can become progressively weaker over time and are often the most expensive solution. For this reason engineered structures are not always the best method of erosion control.
    • Adding rip rap to ditches to minimize/slow runoff. In some scenarios with minimal run-off, rip rap can be effective but in instances with significant water speed and sedimentation, erosion control is not mitigated.
    • Adding vegetation alone, without a structural component. Though grasses can create a groundcover that can absorb some moisture, they have no slope stabilization benefits have less effective storm water filtration ability compared to native ground cover.

Erosion Control Solutions that Work

Cascadia Wall Rexford Place ProjectThe solution to these incomplete and ineffective methods is to combine them into a comprehensive bio-structural approach. This approach includes engineered structural components that are paired with natural, vegetative products that will adapt and grow within the site structure over time. Starting with expert consultation to identify the appropriate method, the following are a few combination solutions available for different applications.

  • Similar to hydroseeding, but providing much more of the underlying structure needed to prevent erosion, Terraseeding uses compost-based soils and growing mediums. During the Terraseeding process,  seed is injected directly into the soil compost mixture as the material is blown into place, providing optimum moisture and nutrient availability.
  • Denbow’s Kicking Horse Canyon Park Bridge project in Golden is an perfect example of combination solutions that utilized Terraseeded EcoBlanket and Filtrexx Rip-rap Grout installed to address erosion and to vegetate extremely steep slopes.

    EcoBlanket – On areas with a slope of 50% or less, EcoBlanket is uniformly applied directly at the soil surface with a pneumatic blower as specified by Rexius. Typically applied at a depth of 1 to 2 inches, but application depth can vary depending the site requirements. In extreme conditions and where specified by the Engineer, EcoBerms or FilterSoxx may be added and constructed at the top of the slope and in parallel intervals down the profile of the slope if necessary.
  • Extreme slope erosion may require a natural retaining wall solution for reinforcing slopes like Cascadia Green Wall, which allows for natural buffer zone design and water gardens. It is a cost effective solution when compared to concrete, block, gabion retaining walls.

Contact Denbow for an erosion control solution that stands the test of time.

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Rain Gardens at Tsawwassen Mills

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Erosion Control vs. Sediment Control

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The overarching principle of Erosion Control vs. Sediment Control is that it is much easier and cheaper to prevent erosion from occurring in the first place than to try and remove the sediment once it has eroded.

Erosion and Sediment Control is a rapidly changing field. Traditional approaches have been applied with varying levels of success over the years. In addition, there are a host of new approaches, practices, and proprietary products that should be shared, understood, and considered on construction and municipal sites. Sites can be sustainably managed by minimizing the impact of earthwork using proven erosion and sediment control measures..

Erosion Controls are source controls designed to prevent erosion from occurring. Solutions include seeding solutions like hydroseeding and terraseeding, wood chip mulch and rolled erosion control products.

Sediment Controls are downstream controls designed to remove sediment from runoff. Solutions include sediment fences and barriers, filter socks and other forms of mechanical filtration.

At the detailed design stage impacts can be minimized through efficient earthworks and erosion and sediment control measures. It is vital that development be successfully completed in balance with the natural environment.

The Erosion and Sediment Control Association of British Columbia is a non-profit organization is dedicated to increase the level of expertise in the Erosion & Sediment Control field throughout British Columbia. Their list of Best Management Practices are divided into Erosion Control and Sediment Control solutions that we think you will find useful.

Is Coloured Mulch Safe for Your Garden

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Is Coloured Mulch Safe for Your Garden?

The use of coloured mulch has increased over the last number of years, as the bold and rich colour offers an attractive look for landscaping while continuing to offer the benefits of mulching. Unlike natural, non-dyed mulch, which tends to fade to gray, coloured mulch can hold its colour for a year or longer.

However, with these benefits, public concern has also been raised regarding the use of coloured mulch. The primary question is:  Is Coloured Mulch Safe for Your Garden?

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What about the dye?

The typical dyes used for colouring mulch are iron oxide-based and carbon-based. Iron oxide, used to produce red mulch, is commonly known as rust, and is used extensively in paints, cosmetics, and even used to dye flowers.  Carbon, used to produce black mulch, is an element often used for ink or paint. Both bases for these dyes are considered natural, non-toxic and safe for handling. Most other colours are made with vegetable-based colourants, also from naturally occurring elements.

A study (“Are Mulch Colorants Safe”) conducted by the Mulch and Soil Council, determined that colourants typically used for coloured mulch are deemed non-toxic and when used properly, would not have any negative effects on the environment.

Of course, a savvy customer should ask about the product they are purchasing, and the company should know about their product. For example, at Denbow, we know that our mulch is coloured with non-hazardous, safe for the environment, ingredients.

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What is in the wood?

As the colourant used in coloured mulch has been generally deemed safe for use, eyes have turned to the content of the wood. The use of recycled wood is a beneficial practice for the environment, yet depending on the content of the wood, harmful toxins (such as lead) could be lingering from past uses.

When purchasing coloured mulch, then, it is important to consider the wood content. In an effort to improve the quality of our products, Denbow produces a number of our own materials, including processing our own mulches. We work with select sources of material to minimize foreign material in our finished products. Our red and black coloured mulches are made of locally recycled wood, free from these contaminants.   

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Will it affect the soil?

There is a concern that when using wood mulch, the carbon of the wood will interact with the nitrogen in the soil, using the nitrogen to help the decomposition process, but in turn, pulling the nutrients from the soil. Coloured mulch actually decomposes at a slower rate than regular wood mulch, which means the nitrogen is removed from the soil at a slower rate.

Use of a nitrogen-rich fertilizer is encouraged, as for whether or not mulch is used, the soil can benefit from the implementation of a regular fertilization program. It is recommended when adding new mulch, to take the time to remove old mulch or be sure to cultivate your existing mulch on a monthly basis in order to help healthy decomposition.

At the end of the day, if you are looking for a pop of colour to refresh a garden bed, or seeking to landscape a new area and considering an alternative to the natural mulch, coloured mulch is a safe and beautiful option. Is coloured mulch safe for your garden? Yes, Denbow’s coloured mulch definitely is.

Protecting Fraser Valley Dykes from Erosion

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Protecting Fraser Valley Dykes from Erosion of the Fraser River Banks

Starting in the Rocky Mountains, and pouring into the Strait of Georgia, the Fraser River is B.C.’s longest river, and largest flowing into the Pacific seaboard of Canada. The Fraser is a busy river: it is home to sturgeon, a provider of water for pulp mills, and in the Fraser Valley, its banks neighbour rich farmland.

After settlers came to the Fraser Valley, they were met with the power of the Fraser River. 1894 brought a disastrous flood to the region when the area had no defense against the rising waters of the river. A dyking system was soon created, but in 1948, with lack of care for the aging dykes, and the banks protecting them, another even more consequential flood, devastated the region, with an equivalent of over $200 million in damages.Protecting Fraser Valley Dykes from Erosion from the might fraser river

In 2013, new erosion on the banks of the Fraser River raised an alarm. Existing erosion arcs, where strong currents had worn down the soft silt at the bottom of the riverbank, were monitored, and advancing development of a new arc called for immediate action, as it was only 30 meters from the dyke; the spring freshet could mean a repeat of history for the area. The dyke was protecting over 12,000 acres of diverse agricultural land, the historic Clayburn and Matsqui villages, land belonging to the Matsqui First Nations, and major regional infrastructure, such as gas mains, water transmission main, and the wastewater treatment plant. Flooding of this area would have even greater negative impact than it did over 60 years ago, an estimated $2 billion in damages.

The city of Abbotsford called for help, and made an emergency repair in early 2014 on the bank using rock armoring, or riprap, providing a new boundary for the river’s flow. Use of riprap is beneficial, as it deflects the impact of the current, absorbing the energy of the water, and therefore protecting the bank. It also slows the flow of water, and provides further protection from debris that the river might be carrying.

An example of such work can be found in Denbow’s Strachan Point project, where Charles Creek erosion was a threat to a CN Rail bridge, the highway bridge, and two private bridges providing access to local homes. Building up and widening the creek bed, and then reinforcing with the process of rock armoring, eliminated the threat.


erosion-arcs-of-the-fraser-river-Protecting Fraser Valley Dykes from ErosionLong-term, the Fraser Valley has more work to do to fight erosion. Since the 2014 fix, two new erosion arcs have developed. The city of Abbotsford engaged the services of Northwest Hydraulics Consultants to undertake a study on the Fraser River erosion. Their findings urged the city to not only continue the upgrades to existing bank protection with rock armoring, but also to utilize rock spurs.

Rock spurs are linear structures, placed at the bottom of the bank, to assist in changing the direction of the river’s flow. This would slow the process of erosion drastically, by moving the force of the water away from the bank toe, which is where erosion arcs begin.

The city approved the proposed project in December 2015, with an estimated $8 million price tag. In April 2016, British Columbia’s Ministry of Transportation and Infrastructure announced $4 million will be provided for the project from the 2016 budget. While the Fraser Valley continues to fight to protect its land and livelihood from the power of the Fraser River, the Ministry has further committed to collaborating efforts to ensure the communities with potential impact are kept safe; work on upgrading the dykes themselves will also be prioritized.Protecting Fraser Valley Dykes from Erosion by the fraser river

Protecting Fraser Valley dykes from erosion of the Fraser River banks, proactive measures need to be taken. Erosion control will ensure infrastructure remains sound, homes are protected, farms flourish, and our historical sites live on.

 

Team Canada Plays to a Bronze Medal in Women’s Softball

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Team Canada Plays to a Bronze Medal in Women’s Softball.

During the week of July 15-24 Team Canada hosted and participated in the 2016 Women’s World Softball Championship tournament at Softball City in Surrey BC.

Team Canada won five straight games leading into their quarter final game against Japan.  Unfortunately, they fell 11-1 to Japan in a mercy-ruled four innings in Sunday’s semifinal before a the home crowd of 4,500.

To finish the tournament, the U.S. were crowned world champions again, after they defeated Japan 7-3 in Sunday evening’s final. It’s the sixth straight World’s that the two teams, Japan and the U.S., have battled for gold.

Canadian supporters where not disappointed as Canada’s bronze marks their highest finish since they took the third-place hardware at the 2010 worlds in Caracas, Venezuela. They finished fourth at the worlds two years ago in Haarlem, Netherlands.

Denbow would like to officially congratulate our 2016 Women’s Softball team. Great job team Canada!

In addition we would like to express our appreciation to  the City of Surrey, the official host city of the games. We supported Surrey through our Playchip top-up program as well as our mulch blowing services to get the Softball City park in tip top shape for the games.

If you enjoyed the article please feel free to share it with your family and friends.

You can read a great article summary on Team Canada’s bronze medal run by Steve Ewen of the Province News Here.

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