8 WASTEWATER COLLECTION, TREATMENT AND DISPOSAL

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1 8 WASTEWATER COLLECTION, TREATMENT AND DISPOSAL 8.1 THE APPROACH The issue of wastewater collection and disposal is crucial and should be adequately addressed to ensure that the wastewater produced by the occupiers of the morcellement and the users does not create pollution of any surface or groundwater resources. This important issue is fully addressed in this section. 8.2 SOURCE AND NATURE OF WASTEWATER The wastewater produced by the households of the residential components of the morcellement will emanate from: Kitchens Sanitary appliances These wastewaters are basically domestic wastewaters which are easily biodegradable. Wastewater produced by shops and offices within the commercial plots will also essentially be of the biodegradable type, albeit in bigger quantities, accounting for domestic toilets and food processing activities with occasional washing. 8.3 ESTIMATION OF VOLUME OF WASTEWATER It is estimated that at full development and occupancy, the residential component of the morcellement will produce a daily wastewater flow of the order of 56m 3 /day as substantiated below: It is estimated that at full development and occupancy, the residential component of the morcellement will produce a daily wastewater flow of the order of 125m3/day as substantiated below: (a) Number of residential plots: 57 (b) Unit daily water consumption: 1m 3 /day (c) Estimated daily wastewater produced: 800litres/day i.e. 0.8m 3 i.e. 80% of water consumption (d) Hence daily domestic wastewater production emanating from the residential components of the morcellement totals to 47m 3 /day (e) For the commercial activities, the volume of wastewater generated has been computed: 55No shops/offices at 80% of estimated daily consumption of 200litres per shop/office per day amount to 9m 3

2 Hence the gross total wastewater production of the entire morcellement will be of the order of 56m 3 /day 8.4 WASTEWATER TREATMENT AND DISPOSAL SYSTEM The issue of wastewater treatment and disposal for a development of this size is of critical importance. Given that the region of Tamarin is not sewered, an individual micro wastewater treatment plant, included in the deed of sale, will be installed at construction stage by each plot owner so as to treat the domestic effluents to tertiary level and re use it for irrigation of individual gardens and lawns. Such individual compact wastewater treatment plants have been preferred to the conventional septic tank and absorption pit/leaching bed approach because of the proximity of the Tamarin River. The proposed method for treatment and disposal of wastewater is discussed below. The effluent of septic tanks and absorption pit/leaching beds is bound to percolate into the ground and may well reach the river. While effluent of the compact wastewater plant will be chlorinated and re used for irrigation of the leisure and gardens of the individual plots. 8.5 MICRO-WASTEWATER TREATMENT PLANTS Domestic Wastewater It is estimated that the domestic wastewater will be the only type of wastewater which will be of the order of 56m 3 /day on average arising out of the daily activities as calculated above at sub section 8.3. For this level of wastewater discharge, and taking into account that no sewerage network exists presently in the region, septic tanks with associated absorption pits would in normal circumstances have been considered to be a suitable treatment and disposal method. However, on account of the Tamarin River which runs towards the southern boundary of the site, the promoter has agreed to make use of a compact wastewater treatment plant which would automatically treat the wastewater to a higher standard and whose final effluent will be treated to tertiary level and therefore reused for irrigation Advantages of the Compact Wastewater Treatment Plant The advantages of choosing a WWTP as compared with a septic tank and absorption pit system are enumerated below: (i) (ii) The BOD removal capability is higher, thereby producing an effluent of higher quality. The effluent will be treated to tertiary level and re used as irrigation water, whereas this is not possible in the case of septic tank and absorption pit.

3 (iii) (iv) (v) No utilisation of CWA water for irrigation which would be more costly. No risk of perception by the villagers of Tamarin that they are being deprived of their water supply in favour of a big project. In its stride, this approach will lead to a better and smother relationship between the project promoter and the Force Vives Process The biological wastewater treatment plant works due to a treatment based on an aerated submerged fixed film reactor. Its process has been designed for residential and commercial projects which are not connected to the main public sewer system The proposed compact WWTP comes with the following advantages: Easy installation Very low maintenance Noiseless Odourless Complete below ground operation One of the highest purification rates on the market An efficient and eco friendly treatment process Mode of operation Domestic wastewater flowing into the compact WWTP unit is treated in three stages namely stages 1, 2 and 3 as explained below: Wastewater flows from one compartment to another as shown in the figure 6 1 below: Figure 8 1: Three Stage Treatment

4 8.5.5 Stage 1 - Primary Settling Compartment In this compartment, water undergoes its first treatment, where suspended solids settle at the bottom. Light matters float forming a crust on the surface. Anaerobic digestion takes place which consists of bacteria digesting organic matters and liquefying solids. A ventilation pipe allows the gas evacuation and avoids any olfactory pollution Stage 2- Biological Compartment After the primary settling compartment, pre treated wastewater flows into the biological reactor. This compartment is filled with a bio carrier i.e. tiny plastic membranes which support the bacteria which cling to form a thin layer called the biofilm. Those bacteria feed on organic matter. Oxygen is blown and diffused into the water to allow aerobic bacteria to develop. Aerobic bacteria are more efficient than anaerobic bacteria: they decompose the organic matter and nitrify ammonium Stage 3- Secondary Settling Compartment In this compartment, the remaining suspended solids (detached layers of biofilm) settle at the bottom and are circulated back thanks to an airlift or a pump from the settling cone into the primary settling compartment. A denitrification process is enabled. An integrated sampling chamber has been designed to control treated wastewater. Clear water is discharged as a final effluent. This effluent can therefore be treated to a tertiary level which normally comprises of chlorination which renders the water fit for irrigation Treatment Performances Typical treatment levels can reach: BOD 5 : < 25mg / litre COD : <125 mg /litre SS : < 30mg/litre NH 4 N : 96% P( tot ) : 30% The Bio-Carrier The bio carrier is a light and resistant honeycomb shaped (recycled) plastic media. Its high surface area (200m 2 / m 3 ) and void ratio allows a successful biofilm development without clogging. The bio carrier does not need replacement over time.

5 Environmental benefits The compact WWTP is characterised by the following environmental features and benefits: (i) (ii) (iii) (iv) High And Constant Performances: It has been independently tested by quality control organisations in France, Belgium and Germany and has successfully passed the applied protocols, including stress conditions (peaks and stop/start) representative of both permanent and holiday/vacation homes. Easy to install The compact WWTP has been designed to reduce the installation time and the shipping costs, not matter the type of tanks ( either plastic or concrete) chosen. No impact on environment Limited footprint Discreet below ground operation Quiet and Odourless High Outflow The difference between IN and OUT is minimum and allows the equipment to be installed anywhere. (v) Easy and Economical maintenance Low desludging period Limited eletromechanical parts Low running cost (vi) Easy access for maintenance tasks The overall design of the compact WWTP has been planned to ease maintenance tasks and allow an easy access to each removable component. Note: The environmental impacts associated with the wastewater management on the project site are discussed at sub section 7.17 of Chapter 7 Prediction and Mitigation of Environmental Impacts Advantages of Micro-Wastewater Treatment Plant The advantages of the proposed micro wastewater treatment plant over the traditional absorption pit/septic tank arrangement are as discussed below: (i) Unsewered areas are generally served by on plot septic tanks and absorption pits or leaching fields (required in cases of Coastal Lands areas, high groundwater areas and on less permeable ground particularly). Many of the installed septic tank systems have been poorly designed and constructed and consequently contribute to pollution of adjacent properties, water courses and potentially the important groundwater and surface water resources. The proposed micro wastewater treatment plant will act as standard wastewater treatment plant and produce effluent of higher quality which will be used for irrigation purposes

6 (ii) (iii) (iv) (v) As outlined in the Black River District Council Planning Scheme 2011, the practice of constructing a septic tank system sized for a single residential unit and then connecting several apartments or housing units is usual practice and should be discouraged; in many instances it is likely that the constructed facilities provide practically no treatment and are little better than pit latrines. Within the ambit of the residential and commercial morcellement, the use of micro treatment plant will be included in the Title Deed and made compulsory for any plot owners Septic tank systems can treat sewage to a reasonable standard and are appropriate only where the soil conditions are suitable and where the development is of relatively low density. The proposed sewage treatment system will be appropriate in any soil conditions insofar as the effluent will be of better quality and will adequately be treated to tertiary levels for re sued as irrigation water Such micro wastewater treatment plant produces high quality effluent which can moreover be treated to tertiary levels, by means of filtration and disinfection Furthermore, it offers re use possibilities of the effluent for example as watering of gardens and lawns thereby obviation the need to purchase CWA domestic water for irrigation purposes. This constitutes a water conservation strategy offered by the project In any case written approval of the design of this type of sewage disposal will be duly sought and obtained from the WMA. As per the latest promulgated legal and statutory requirements, the WMA has developed special and stringent technical questionnaires which should be filled and submitted to them for approval, prior to installation on site. This laudable initiative is welcomed and the promoter, through his technical team, will comply with all the stipulated requirements and specifications. 8.6 TREATMENT OF OTHER WASTEWATERS Wastewaters emanating from kitchen sinks will be discharged into a grease trap before being channelled to the micro sewage treatment plant. This grease removal mechanism, to be placed upstream of the compact treatment plant, achieves the recommended removal of oil and grease, which otherwise will impair the operation and performance of the compact treatment plant. Wastewaters being generated by wash basins, showers, bathtub and/or washing machines will be conveyed directly to the wastewater treatment plant. The typical grease trap arrangement has been enclosed at Annex 8A at the end of Section STATUTORY REQUIREMENTS After the obtention of the EIA Licence, the promoter will carry out the detailed design of all the required sewage infrastructure in conjunction with the WMA. The relevant questionnaire will be duly filled in and submitted to the WMA for approval.

7 The relevant drawings of the typical grease trap, micro wastewater treatment plant showing clearance distances from boundaries will be submitted to the WMA and the BRDC for approval. Such drawings will thereafter be included in the individual deeds of sale as a condition for compliance by the eventual purchaser. 8.8 STATUTORY COMPLIANCE Following application to the WMA for obtention of clearance, a joint site visit with the promoter and representatives of the WMA has been organized on 15 th November 2013 to describe the project scope. Via a letter reference WMA/EIA/2115 dated 19 th November 2013, the WMA has requested for additional information to further process the application to which the promoter is attending. Copy of the WMA letter has been enclosed at Annex 8B at the end of Section 8. The promoter will abide with all the conditions of the WMA in due course.