How we work with you
Each member of our network works independently but may collaborate with other members on specific projects.
Depending on project location, dimension, and nature (kind of wastewater, to be integrated or not with public landscaping, kind of ecosystem receiving treated water and/or agricultural reuse, etc.), we work with a network of people and at times organizations around the world with complementary expertise who join us on a per-project basis.
We either bring together our own construction teams or work with the Client’s constructor.
1. Consulting and Design Services
Important design factors
Climate and regional applicability
Since WWG systems rely primarily on green plants and microbes, they perform more efficiently, requiring less area, in warm, sunny conditions. But the approach is ideal for climates ranging from tropical to semi-Mediterranean-type climates and some southern hemisphere semi-desert and desert climates. In these conditions with higher temperatures and increased sunlight, system productivity is high year-round. Applications for colder regions however can also be very effective as has been shown in WWG projects in New Mexico and Poland, located in high elevation sites with long winters. However, in colder climates, the necessary surface the same amount of wastewater must be larger (at least twice than for a warmer climate) to accomplish similar treatment. Wastewater Gardens are not only especially recommended for use in on-site systems, close to the facilities they are to service, but have also demonstrated their responsiveness in areas with groundwater close to the surface, for sites with rocky or impermeable clay soils (that often prevent standard leach fields from operating), as well as for sensitive areas close to rivers, lakes, and coastal waters (possible creation of buffer zones).
Greywater treatment
Greywater refers to wastewater other than that from the toilet (including sometimes toilet lavabo) referred to as faecal or blackwater. Greywater includes showers and bath water, laundry machines, sinks and kitchen water (although in some applications kitchen water can be joined to the faecal water and be treated by a WWG unit as well, as it contains food particles, grease, and oil). Some water issued from industrial operations can also be classified as greywater although the water content would be carefully analysed to adapt the constructed wetland’s design to purify ecologically harmful and sometimes synthetic compounds.
In numerous situations however, greywater doesn’t call for a treatment as intensive as what is provided by a constructed wetland / WWG unit and so the WWG unit is used just to treat the black water. If land is not an issue though and that there is a large quantity of graywater to be treated, then a constructed wetland / WWG unit is also appropriate and will generally represent much smaller surfaces than if it was treating blackwater.
In the case where both types of water are separated, keeping WWG systems for blackwater treatment only, greywater would only need to pass through a sedimentation tank before going directly into subsurface irrigation trenches. The advantages of separating greywater are that more irrigation can be accomplished with the wastewater and overall project costs will be lower, as the WWG unit will treat a smaller quantity of water. However, we often work in situations where the separation between black and grey waters is too difficult and/or expensive, just as a “retrofit” to existing plumbing, and therefore design the WWG system to treat both types of water.
Stormwater treatment
In urban settings and in regions subject to flooding during storms, constructed wetlands are being employed to clean the water and to slow down the movement of water which creates flood pulses. Stormwater from urban and paved surfaces often contain pollutants like oil and fuel residues which can be readily cleansed in a wetland. In addition, in areas where freshwater supplies are limited or expensive, making use of the stormwater enables the greening of the landscape using a natural and renewable resource.
Space requirements
In the Western-type housing sector for example, we assume normal wastewater generation of 125-200 litres per person per day (European average) although this number can vary greatly according to cultural norms, geographical location and type of infrastructures and appliances (in the USA for example average amount of wastewater per day per person can be as high as 500 Liters); for example, a city dweller will have the tendency to use more water than a countryside dweller and a hotel guest for example can have a water consumption that is double or triple than a resident’s. For a generation of 150 Liters of both blackwater and greywater mixed, depending on the climate and requirements of purification, we would apply a surface of 2.5 to 4 m2 of WWG surface of horizontal flow design. This indication depends on many factors including the climate (the warmer the climate, the smaller an area is needed since the plants and microbes are more effective year-round), the kind of infrastructure and water faucets used, the amount and nature of wastewater generated, what standard of treatment is required or desired. In cold climates, these numbers may be twice or three times as large, depending on the level of treatment required during the cold periods of the year when plants are dormant and bacterial activity is slower.
In the industrial sector, no pre-indication can be given as WWG surface will depend on the nature of the industry and thus on the type of compounds to be treated in the water
INITIAL CONSULTATION:
We determine with you whether our system is suitable to your needs. If so, we sign a consulting contract to undertake the process necessary to produce a design that can bne implemented.
While initial contact, data and discussions can be exchanged via email, we may need to review your site and the infrastructure(s)’ location plans to understand your site, evaluate its need and discuss possibilities for the location of the WWG system.
PROJECT EVALUATION, SITE SURVEY AND PROPOSAL:
We will need data from you to evaluate overall project sewage generation. Depending on the project, we may need to visit your site or request that important information be given to us. These include topographic maps showing land contours and infrastructures, already existing sewage systems, including septic tanks and discharge pipes, percolation tests of the soil, existing trees and vegetation, possible drainage areas, options for use of treated wastewater, and other factors that will affect the proper functioning of the WWG system.
ACCEPTANCE OF OUR PROPOSED DESIGN:
We agree on contract terms and payment schedules. Then we send you a document containing the project study, the dimension and size of necessary installations, schematic plans, and necessary informative documents to obtain permission to build (when necessary). Final fine-tuning of the system and shape of the WWG units will be discussed at this time as well as types and varieties of plants suitable to the project and owner’s preferences.
2. Implementation/Construction
CONSTRUCTION: We always work with a local construction company where the WWG unit/s are to be implemented and can in some cases be contractors as well. We only deliver final plans of the WWG systems when we are secured that we will be co. supervisors of the construction or that we are assured of the experience and Know-How of the construction supervisor. If WWG team is not to be involved in the construction, in-person or phone/email meetings with the contractor are needed to ensure that system engineering will be properly applied and that each principal step before final testing and planting will be respected.
If our study includes the installation or upgrade of an existing primary treatment (septic tank, Imhoff tank, etc.) as well as other general installations, these recommendations will ideally be implemented prior to WWG unit implementation.
If WWG-International is also acting as contractor we will decide with Client the construction calendar. In most cases, materials, machine rentals when necessary and labor will be paid directly by the Client to providers.
INSPECTION: Regardless of who is supervising construction, the following essential points will need to be monitored prior to planting:
– AN ADEQUATE PRIMARY TREATMENT, well sized and built with final filter, ensuring a good separation of solids from liquids;
– VERIFICATION OF THE TEXTURE AND NATURE / GRANULOMETRY OF SOILS: when choosing drainage into the soil, it is fundamental that a permeability test of the soil be done in order to ensure proper drainage.
– LINING TESTING, LEVELS AND WATER FLOW: if WWG units are built in concrete, reinforcements will need to be inspected when framed, before the cement is poured. If they are waterproofed via a membrane, the liner will need to be inspected. We must also ensure that the pipes are well placed and that the water flow between the system’s different components is proper, ensuring correct levels and positions.
– WATERPROOFING / LEAK TESTING AND DRAINAGE: after the lining is placed, we must supervise a water leak test to ensure proper sealing with no leak/s. When soil drainage is chosen, drainage network must be properly placed, laid-out and piped (with testing of equal distribution of water at the end of each line).
– GRAVEL / MEDIA USED IN THE WWG UNIT /S: before gravel is placed in the unit/s and sometimes in the drainage lines, we must ensure is nature (porosity, density), grading (size) and that it is properly cleansed, without impurities.
Construction Process
Photos of the construction/implementation process for homes, businesses/hotels and community projects.
After marking the terrain and taking a point 0 as reference level (it should be the entry point of pipe into the WWG unit), excavation of WWG basin + Control Box (by hand or by machine)