Frequently Asked Constructed Wetland Questions
Following is a selection of questions commonly asked about Constructed Wetland Systems. Most of the common questions on Reed Bed Systems and Zero Discharge Willow Facilities are given on the relevant pages. If you have a question that isn't addressed here just email us. I had wanted this to be a much more comprehensive page, but in order to answer the most common question: "What's the best system for my site?" I ended up writing a book on the subject: Septic Tank Options and Alternatives
What are constructed wetlands? What are the main advantages over other forms of wastewater treatment? What are the main applications?
These questions are answered in the Constructed Wetlands page, so have a look there for more specific information on constructed wetlands.
What is the difference between a constructed wetland and a gravel reed bed?
In short, a constructed wetland is typically a soil based marsh with water flowing through the plants, above the soil level. Reed bed treatment systems are gravel filled systems which allow the water to flow beneath the gravel surface. For more information on the differences between the two systems, and between horizontal and vertical flow gravel reed beds, see the Reed Beds page.
What is the best time to build a constructed wetland?
Ideally, apply for planning permission as part of the overall planning application for a new house or development project. Build the system at the same time as the house goes up, so that the plants have thickened by the time the new occupants are ready to flush the loo. Planting is best carried out in the spring, when plants are about to put a good push on, but any time of year is ok as long as you are willing to wait until the following spring before they look good and start to work at their best.
What would a wetland cost for a typical single house system?
For filtering the effluent from a domestic septic tank, a wetland area of about 100m2 would be required. The cost of designing, building and planting this is usually about €3000-4000 depending on site conditions. This does not include the septic tank, piping, fencing or landscaping.
What is the cost for larger systems?
The cost is dependent on many factors and is highly variable from site to site. Factors include, for example; topography, soil type, subsoil characteristics and effluent quality requirements. For details of specific projects telephone our office, details on the contacts page.
What elements of the work does FH Wetland Systems Ltd. offer?
We carry out the initial design work and the final planting work. We do not generally get involved in the construction element of the work. It is typically more cost effective to get your own groundworks contractors to do the wetland excavation while the house foundations are being excavated. For existing houses, local machine contractors are usually employed directly by the client to carry out the work.
Once the system is built and running, how will I know how look after it?
The maintenance input for constructed wetland systems is relatively small, and for the work that is needed, a full explanation is provided with the initial designs. With over ten years of experience with constructed wetlands in Ireland, we are also available to answer telephone questions or visit your system if any queries should arise.
Is there always a pond?
Increasingly we have omitted ponds from domestic scale system designs. This is mainly a safety decision. More wetland marsh area is needed to compensate for the loss in volume within the system, but overall, similar wildlife habitat and treatment efficiency characteristics are achieved. For larger commercial constructed wetlands, ponds are often included in the designs.
Where can I source plants?
FH Wetland Systems have been supplying wetland plants since our start-up in 1996. Make sure you don't connect your sewers until after the plants are established. Typically we'd carry out a system check on the day of planting so that you know that the construction has been carried out correctly.
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