Choosing the Right Silt Curtains: Important Reminders
A silt curtain is also known as a sediment barrier or turbidity curtain, and it plays a vital role in any marine construction project. These barriers prevent silt and sediment from flowing into unintended places. This guide is intended to assist you in making the appropriate choice for the right silt curtains for your construction project. It is also intended to help you avoid costly mistakes for selecting the right silt curtains for your work site. In this article, we will discuss a few of the basics you need to know about choosing silt curtains. The consequences of selecting the wrong ones will also be discussed.
For more information, you can also read “Floating Booms: A Solution To Environmental Problems”.
Below, you can access the headings of this article:
- What is a silt curtain?
- The effectiveness of silt curtains
- What are the silt curtain components?
- Selecting silt curtains by asking the right questions
- The consequences of choosing the wrong silt curtains
- Case study: Replacing silt curtains for hotel chain
What is a silt curtain?
Silt curtains, also known as turbidity barriers, are designed to contain sediment and prevent it from spreading into the surrounding environment. They are commonly used in construction, dredging, and other activities that can generate sediment. A silt curtain does not extend to the bottom of the waterway channel and is placed parallel or perpendicular to the direction of flow.
Best performance of Silt curtain is intended for calm water conditions where it will not be subjected to wind, wave, or current. Silt curtains are appropriate to settle out coarse and granular soils where water depth at the time of construction is greater than or equal to 4 feet.
The effectiveness of silt curtains
The effectiveness of silt curtains depends on several factors, including the quality of the materials used, the design, and the installation of the curtain, as well as the specific conditions of the environment where they are being installed. As a result, it is important to keep in mind that not all silt curtains are created equal and their effectiveness varies accordingly.
Off-the-shelf silt curtains may not be made with the same level of quality or attention to detail as manufactured and fit-for-purpose curtains, and as a result may not perform as well and may cannot contain sediment. It is important to use high-quality, customized silt curtains that are fit for the environmental conditions, your operational requirements and maintenance capabilities, to ensure that they are effective in preventing the transport of sediment out of a site.
What are the silt curtain components?
1- FREEBOARD: The portion of the silt curtain that sits above the water line.
2- DRAFT: The submerged portion of the silt curtain.
3- FLOTATION: Flotation is composed of polyethylene foam with closed cells of high density. These floats are crumble resistant and oil resistant, and ensuring continued flotation.
4- SKIRT: The skirt is manufactured from a special membrane that only allows water to pass through.
5- BALLAST: The curtain is maintained in position by applying a ballast of galvanized chain sewn into a chain pocket at the base of the curtain. This ballast extends consistently for the full length of the curtain, allowing for continuous tension.
6- CONNECTORS: The curtains shall be connected using specially molded connectors to attach the freeboard section of the curtain. These connectors provide strength and durability in the water.
Selecting silt curtains by asking the right questions
1- Product function and application: First, it is important to know what the purpose is for installing. What is the problem that you are facing and what, according to you, is the solution? What are your expected results after installing silt curtains? The environmental conditions at the site will have to be taken into account when we build the curtains.
2- Know your supplier: When looking to purchase products or materials, it is important to research the supplier before deciding. This includes asking questions such as who are you buying from? How long have they been in the industry and what is their engineering capability? Check their website–does it show actual product photos and case studies? Check their experience list and ask for references. Be cautious of large discrepancies in pricing–this can often indicate a mismatch between the materials being supplied and the material specification.
3- Understand the product specification: What purpose does each material component serve? What specification is the most critical for your needs? Are you receiving the exact product you ordered?
4- Installation method: Are there any limitations for installing the silt curtains? What are the environmental conditions where the silt curtain will be installed? What equipment is available on site for installation and anchor handling? Incorrect installation can cause failure and the shutdown of a project site.
5- Maintenance plan: Maintenance is an overlooked but very important factor that affects the effectiveness of silt curtains. Does the client have the resources and equipment on site to handle a failure?
6- Budget: What is the project budget? What’s the cost of prioritizing certain features over others? And more importantly, what is the cost if the installed silt curtains are not fit for purpose and fail?
Having more clarity on these factors helps you choose a more suitable product that fits perfectly with your needs. Failing to choose the right silt curtains can result in increased project costs, environmental damage, and the need for periodic replacement.
The consequences of choosing the wrong silt curtains
There can be several negative consequences associated with choosing the wrong silt curtains. The curtains may not perform their intended function effectively, resulting in environmental damage and increased project costs. Low-grade silt curtains may need to be replaced more frequently, resulting in higher lifetime costs. Additionally, if the curtains are not designed with environmental factors in mind, they may deteriorate quickly and require frequent maintenance. This can lead to unplanned downtime, disruption of the project, and further costs. Therefore, it’s imperative to choose the right silt curtains that are suitable for the specific conditions and application, to avoid these issues and ensure the project’s success.
Case study: Replacing silt curtains for hotel chain
Recently in Europe, our partner, Bolina Booms, worked with a client to replace the silt curtains they had previously installed from another provider which were severely damaged in a very short period. The curtains were made of substituted materials and downgraded components, indicating a lack of understanding of the purpose of material components, engineering principles, and overall silt curtain design. Furthermore, significant gaps between the panels greatly contributed to the curtain’s rapid deterioration. Silt curtains that are not properly constructed, anchored and installed will not withstand bad weather and other challenges to last through the job. Even perfectly constructed and installed silt curtains need to be inspected on a regular basis.
In this project, first step was to conduct a detailed on-site examination of the damaged curtains to identify the reasons for their failure. Next step was evaluation of the surrounding environment where the new curtains would be installed. This help to understand the constraints, potential issues, and any other necessary information needed to design and fabricate customized silt curtains that are durable. After gathering all relevant information, engineering team performed force calculations to determine the most suitable type of silt curtain for the specific environment. New silt curtains successfully installed, which are now operating as designed. The hotel chain is extremely satisfied with the high quality, high-performance curtains that are now finally fit for purpose.
ADOR Tech, as Bolina Booms representatives in Canada, offers a full range of Floating Booms Products and services. For more information, please contact us.