SCHEME 2 PUBLIC HEALTH AYA NAGAR DEVELOPMENT PROJECT

Transcription

1 SCHEME 2 PUBLIC HEALTH AYA NAGAR DEVELOPMENT PROJECT 19 th August 2009 GREHA Registered under the Societies Act XXI of 1860, number of Eco Options, Mandir Marg, A2, Aya Nagar, Phase 5, New Delhi India. TeI Fax

2 SCHEME 2 PUBLIC HEALTH 1.1 DRAINAGE SCHEME One of the key aspects of maintaining good public health is the design and use of an effective drainage system. A large number of killer diseases are known to be waterborne and a badly functioning drainage system can accelerate the effects of the same in a community. Aya Nagar is a case in study whereby a decentralized, self sustaining, in situ drainage system is proposed which will ensure that a clean and hygienic environment can be maintained to a large extent by the residents themselves. 1.1.a PRESENT SITUATION The population in Aya Nagar has more than doubled in the last decade. The systems established for a small village settlement have been unable to cope with the increasing pressures of population growth. This has resulted in a complete failure of the working systems in the area. The present situation in Aya Nagar is a clear example of the lack of a proper drainage system. Open drains along plot edges serve as the main spines for the street which carry grey and black water. Inappropriate slopes of drains, and blockages caused due to disposal of solid waste chokes these drains, and the accumulation of sewage water becomes a potential breeding hub for disease causing germs and mosquitoes. The situation is aggravated during the monsoon season as most of the unbuilt surface is solid paved allowing little or no penetration of rain water to the ground. Further, the surface run-off usually mixes with the sewage water in open drains and overflows, making the streets completely unhygienic. Existing Situation Narrow open drains Lack of ground water recharge due to hard paved surfaces Blockages caused due to solid waste disposed in the drains. Lack of proper system of rain water drainage. Fig. 1 Typical Street Section aya nagar development project, new delhi 1

3 1.2 PROPOSED DRAINAGE SCHEME 1.2.a PROPOSED SYSTEM The waste and grey water from each built plot undergoes a two - level treatment process before it reaches the Johar (water harvesting / oxidation pond). The water from each plot is first treated in a local digestor (STP) which will dramatically reduce the harmful nitrates and bacteria through the use of organic bio sanitizers. The overflow from the digestor (STP) shall enter a grey water pipe which shall run along the street edge sloped towards the Johar. The 2 nd level treatment of water will be done by root zone treatment through a designed reed bed, before it enters the Johar. The BOD levels of water will be tested at 2 stages. The first test will be done just before the treated water enters the grey water pipe from the digestor. The second test will be conducted when the water leaves the reed bed and enters the Johar. The overall system can be described in the following diagram; Waste and grey water from each plot Treatment Lvl-1 Digestor (STP) for a group of plots Digestor (STP) prototype developed Digestors (STP) connected with pipes laid to natural slope Treatment Lvl. 2 Reed beds adjoining the Johar to clean the water before it enters the reservoir. Recycled water to be used for maintaining the Eco Park along the Johar. Overflow of the Johar directed towards the ravines for harvesting in new Johars. Recycled water to be stored in a reservoir and supplied to residents for irrigation. aya nagar development project, new delhi 2

4 1.2.b CALCULATIONS AND FEATURES OF DIGESTER 1.2.b.i Assumptions and Calculations The following assumptions and limitations are being considered for quantification / design. Current Population in the Street 1 (implementation street) Projected growth in population in the selected street Total population in Street 1 (implementation street) to be considered Total waste water generated (Grey + Sewage water) Total quantity of waste water = 350 x 150 Total Number of Digestors (STP) proposed in the 10,000 mts c/c Proposed load per Digestor (STP) = 52,500 / 5 Total number of users per digester (STP) = 10,500 / 150 Total treated water available for irrigation etc from 5 Digestors (STP) 250 persons 100 persons 350 persons 150 Litres /day /person 52,500 Litres 5 10,500 lts. per day 70 persons 52,500 ltrs per day Limitations of Site:- Width of streets largely varies between mts, therefore the width of the digestor (STP) should ideally be restrained within mts. 1.2.b.ii Features of the Proposed Digester (STP) Broadly, the following features are required in the design of the proposed digester (STP). Leak proof and non porous to avoid any contamination. Lightweight and easy to install as a prefabricated module. Should withstand vehicular traffic load. Durable and cost effective. aya nagar development project, new delhi 3

5 1.3 PROPOSED DIGESTOR Based on the requirements of the scheme, prefabricated Glass Reinforced Plastic (GRP) digesters are proposed for the drainage scheme (Ref. Fig. 2 & 3). Fig. 2 Plan of Proposed GRP Digester (STP) Fig. 3 Typical Section of Proposed Digester (STP) 1. PROCESS DESCRIPTION FOR (DIGESTER) STP: * 1.1 The effluent from the entire contributing Houses etc. shall be brought by pipe to the digester (STP) through the screen chamber. All the Floating materials are to be removed manually from this chamber and wastewater shall flow to the anaerobic reactor. 1.2 In the digester (STP), Microorganism OS1 will be dosed on daily basis for rapid fermentation process and decomposition of Biodegradable organic matter. Microorganisms will assimilate BOD load. 1.3 After digester (STP) this treated wastewater will be flow to the Reed Bed. Further this water flows by the gravity to the Johar (Oxidation pond). 1.4 This treated water will be stored in the Johar (Oxidation tank) from where it is pumped for irrigation. 1.5 Treated water after filtration will be clear, unobjectionable, low BOD (< 50 mg/lit), low suspend solids, and floating matter not noticeable can be used for non-potable applications like irrigation. 1.6 Excess sludge from the digester (STP) will be taken out periodically and can be used as compost. *Extracted from report submitted by Organic Solutions to GREHA on 9 th Jan aya nagar development project, new delhi 4

6 1.4 SYSTEM FOR RAIN WATER DRAINAGE The only drainage provision at present is open channels on sides of roads. These carry waste as well as sewage and rain water. Often the open channels are blocked by solid waste and garbage. The proposed system for drainage separates sewerage and waste water from rain-water, which is flowing on the surface of open areas, roofs, and finally on roads. With sewerage and waste water being provided at sub-surface level, the road surface will carry only rain-water. It is proposed that roads are surfaced with concrete pavers laid to slopes for carrying surface water (Ref. Fig. 9) to harvesting locations like the Johars. The pavers are designed to be laid dry on compacted earth so that water percolation is possible, and the size and shape allows stacking and ease of laying (Ref. Fig. 4 & 5). Fig. 3 Proposed road section Fig. 4 Details of pre cast concrete blocks Fig. 5 Proposed laying pattern of the pre cast concrete blocks There is a growing trade in building construction materials of late in Aya Nagar, which is causing environmental pollution. It should be possible to divert local initiative and resources towards manufacture of pre-cast concrete blocks for road surfacing. aya nagar development project, new delhi 5

7

8

9