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Home , Constructed wetland

Integrating Watershed and Coastal Areas Management CONSTRUCTED TREATMENT SYSTEMs MADE EASY

“It’s harder to change spark plugs on your car than it is to put in a .” Michael Ogden, President, Natural Systems International, USA. “WHAT”… “WHY”… are constructed wetland systems? should I use a constructed wetland wastewater treatment system? Constructed are an clarified middle layer (effluent) A properly designed, installed it doesn’t attract bugs, and is alternative wastewater treatment is filtered and then travels to the and maintained constructed safe to have around your family. method that mimics natural constructed wetland tank or cell. wetland wastewater treatment processes to cleanse water. In the constructed wetlands, system is a great way to treat the that naturally live wastewater coming from your in water, on rocks, in , and on home, while also reducing risks to the stems and of wetland human health and damage to the plants feed on organic materials environment and improving the and nutrients, removing appearance of your property. from the wastewater. Constructed Wastewater flows through wetlands are created to similarly the wetland, where plants, filter the waste (grey or black) , and other beneficial microorganisms consume the

The plants that grow in the wastewater remains below the system thrive on the nutrients in surface. This controls mosquitoes wastewater and help to beautify and offers little chance of human both the environment and your contact with the wastewater. homes. The system is more Cattails, bulrushes, reeds, and efficient than a soak-away in other aquatic plants are planted cleaning the water before it is in the cell. Microorganisms living released in the environment either on the surface of the and above ground or in the soil. This plant roots break down organic means that your family, your water from a household. materials in the wastewater. The neighbours and the environment A constructed wetland system plants in turn provide and are safer and better protected. . consists of a , remove some of the nutrients waste, making the water safer Less results in less the wetland tank or cell, and from the wastewater. Some of the once it is released back into illness which results in happier a method for returning the wastes settle out and attach to the environment. Because people! Don’t forget about the treated wastewater back to the particle surfaces. the wastewater is treated flowers which attract birds, environment, such as a drain or underground, there is no smell, butterflies and good vibrations! . After treatment, the water is released, most often into the main In the septic tank, wastewater drain. However, the water can receives initial treatment. Bacteria be reused on lawns or gardens begin to break down wastes, and through a drip system, once the solids settle to form a effluent quality is good. Other layer, while greases and oils uses include evaporating the float to form a scum layer. The water in a pond or watering livestock.

1 Wetland Wastewater Treatment System Section View, EcoSolutions LLC, 2008 2 “HOW”… “BUILDING”… should I use a constructed wetland wastewater treatment system? a tank or cell for the artificial wetland Siting • Glue (for PVC) Step One: Step Two: 1. It should be downhill from • Gravel (filtering the ) Dig a pit to accommodate a This outlet pipe must be connected your septic tank. If you don’t • Rotting coconut fibre concrete structure approximately to the base of the water level have a septic tank you will (filter, growing plants) 4 feet by 10 feet. Essentially, the control. While you can buy a need to install one with a • Septic tank filter (can be length should be two and a half water-level control device, a simple minimum capacity of 1,000 constructed from PVC and times the width. Make sure that you covered plastic bucket will suffice. gallons. netting) divert the surface rain water from In the middle of the section of 2. If your land is flat (and the • Water level indicator (plastic getting into the wetland. Large the wetland system and below wastewater from the septic bucket) families or combined households the outlet pipe, you need to run a tank cannot flow by gravity), • Outlet tap with more than one septic tank you will need to connect a • Plastic drum or barrel (for can build a larger wetland provided pump from the septic tank filtering black- and grey-water) that they keep the dimensions in outlet to the inlet of the • Plywood (for building casing proportion. The wetland should wetland system. for casting the concrete) be about 4 feet deep. You should use plywood or cheap lumber as Materials needed: the frame for casting the concrete. • Cement (for building the Advice: The walls should be built of pure concrete structure) “While you may be able to concrete with reinforced steel (3/8 • Water sealant (to be mixed Plan View build an artificial wetland or 1/2 inch). The concrete mixture into the concrete for should include a water sealant. In length of 4inch PVC pipe which has waterproofing) yourself, it is always best to get some advice and help constructing the frame for casting an elbow joint at the inner end (the • ½-inch steel (for reinforcing the system, you would need to part within the tank) that projects the concrete) if you need it. You should identify where the water outlet above the level of the water in • Wire (to tie the steel rods contact your local Public should be and insert a piece of 2 the system. The other end leads together) Health or Environmental inch PVC where the hole should be out of the concrete tank. Both • PVC Piping (different lengths Health Department for – almost 18 to 24 inches above the have screwed on covers that can of 4” and 2” for the inlet/outlet guidance advice and base of the system. The outlet pipe be removed for flushing out the of the system and for cleaning assistance, especially if special should be on the opposite end of system. The part of the pipe within the system) permission is required to the structure from the inlet pipe (4 the tank is perforated so that water • PVC fittings (water level install a wetlands system.” inch pipe from the septic tank). can enter the pipe and get into the control, flush lines, inlet, water-level control bucket. outlet, reducers)

3 4 Step Three: Remember your cleanout or with specific wetland plants that In the middle of the pipe, where system-flushing ports within the will aid in the treatment of the the bucket would be placed, a system must be over 2 feet 6 wastewater. Roots of the plants will T-junction is connected facing inches high (above the gravel and penetrate into the gravel to absorb upward. When that is done, put a coconut compost layers.) Also the water in the basin and provide 2 inch reducer and pass it through coconut husks should already be some treatment of the wastewater. the bottom of the bucket ensuring in a state of decomposition or rot. that the bucket is tightly sealed a T-junction to the barrel. This will Step Seven: and only water from the pipe gets then be connected to the septic The concrete septic tank removes into it. You would need silicone or tank. There will be a screw cap at settleable and floatable solids from plumber’s glue to ensure that the the top projecting above the water the wastewater before it flows to seal is tight. level for cleaning out the system. the system. The septic tank is a Then insert two 4inch PVC pipes two compartment 1,000 gallon The bucket is above the level of the with elbow bends and screwed on tank. The purpose of the filter is fill material and the coconut fiber caps into the sides. These must to prevent solids from discharging compost so that the cover can be to the system. A single filter is removed to adjust the water level installed for in the bucket which then controls protection. Filters can be bought or the water level in the system. It is made using PVC with holes cut in it vital to ensure that there is always Step Four: and wrapped in netting so that the water in the system. Cover the entire concrete cell with solids are separated out and only 2 feet of gravel that is graded, liquids go into the artificial wetland. The bucket or water-level controller washed, and free of dust, , The filter should be taken out and will be filled by the 2 inch pipe , or . Rock sizing may range cleaned annually coming into it. At the side of the from 3/4 inch up to 1.5 inches bucket you need to make a hole Step Eight: for a 4 inch pipe, reduced to 2 Step Five: Connect the pipe from the septic inches which is then connected to also project above the water level tank to the end of the artificial The inlet or area connected to the and are intended for flushing out the 2 inch outlet pipe. This way the septic tank must be opposite the wetland opposite the outlet pipe. treated water is then released from the system. Note, water will also The idea is that the water is treated outlet end. Cut a plastic drum or percolate through the stones. This the system into the drain or for use barrel into two equal segments as by the plants and filtered through in or for a “downstream” is to ensure that the black water the coconut and gravel until it flows shown in the diagram. Insert three is in contact with the coconut lawn or garden. to four rows of holes at the base out at the bottom of the wetland fiber, which in turn will maintain much cleaner than when it went in. in a zig zag pattern to allow water moisture for the wetland plants. from the distribution zone (septic tank) to flow horizontally. Connect Step Nine: Choose your wetland plants to grow in the coconut compost. They must be able to adapt to saturated condition; the plant species must be succulent in nature; the

Step Six: Cover the gravel (two feet deep) with a 6 inch layer of coconut compost which insulates the water. The compost will also be planted

system must not cause damage to the wall structure; and the plant must be easy to maintain and won’t regenerate outside the 5 system or become a nuisance. 6 Other considerations for choosing The St. Lucia Example plant species include root shape, In some parts of the Caribbean the soil density, and depth. Ideally a is too stony to build a soakaway. Some wetland plant with deep roots people build septic tanks but then the and a great deal of surface area, “black” water runs straight into the drains, rivers or the neighbours’ yards without clogging the pore space is causing not only health problems but preferred. These include Blueflags, a lot of friction in the community. Bulrushes, Broadleaf Arrowheads, white Ginger Lillies, and Cattails. In the Fond d’Or community of St. It is best to use native wetland Lucia there are many homes which since they are adapted do not have adequate waste storage to the local environment. and treatment facilities. Untreated domestic waste enters into gutters, gullies and rivers, often resulting in effluent contamination of stream water. The GEF-IWCAM Demonstration Project in Saint Lucia recognized the increasing threat being placed on the streams and rivers by human Step Ten: activity, as well as acknowledged Monitor and maintain the system that communities within the project including: watershed lacked adequate septic tanks and soak-aways to treat black 1. Periodically cleaning out the water. The project then worked with the sewer line which leads to the Caribbean Regional Coordinating Unit septic tank of the United Nations Environment 2. Checking sludge build-up in Program (UNEP-CAR/RCU) and came the septic tank and having it up with an pumped out when it is almost (Constructed Wetlands) for addressing full domestic waste. 3. Cleaning out the outlet filter (to the artificial wetland) at least This process is best in areas where the soil is too hard or dense to build once a year a soak-away or where the residents 4. Making sure there is no water want to beautify their surroundings on the surface of the wetland and create a healthier environment. The GEF-IWCAM St. Lucia Demonstration Project’s Wetland Construction Design Manual and other reference materials are available at: www.iwcam.org

For further information please contact:

Caribbean Environmental Health Institute P.O. Box 1111, The Morne, Castries, Saint Lucia Tel: (758)-452-2501/1412; Fax: (758)-453-2721 E-mail: [email protected] www.iwcam.org