SECTION (3): DRAFT PREPARATION OF TERMS OF REFERENCE (DWT)
3.1 INTRODUCTION TO YAMUNA ACTION PLAN
Yamuna Action Plan (YAP), initiated with the assistance of JBIC in 1993, is currently being implemented along the entire stretch of Yamuna in the states of U.P., Haryana and Delhi with the aim of water quality improvement of Yamuna. Until 2002, the first phase of Yamuna Action Plan (YAP-I) was implemented with second phase to continue till 2009. Under the Yamuna Action Plan (YAP) project, sewage treatment facilities have been created in towns of UP including Agra, Haryana and Delhi. New sewage treatment facilities have been proposed based on the Decentralized Wastewater Treatment (DWT), which is increasingly being seen as better alternative to Centralized Wastewater Collection and Treatment in those areas which are not likely to be connected in near future. Cheap and low maintenance technology options are being explored to adapt and implement Decentralized Treatment Systems in India for Municipal Wastewater Treatment. Reuse of Treated Wastewater is also being explored as a possible option for reducing stress on water supply systems and improving the water quality in Yamuna through reduced wastewater discharge. Japan Bank for International Cooperation (JBIC) has shown an interest in facilitating a feasibility study for Techno-Economic and Ecological viability of an Integrated Wastewater Management project based on implementation of Decentralized Wastewater Treatment systems in water bodies/inland lakes and implementation of Pilot Projects for demonstration, which would act as a model for other facilities in Delhi, U.P. and Haryana.
The executing agency for YAP implementation is National River Conservation Directorate (NRCD), Ministry of Environment and Forest (MOEF), Government of India. The physical implementation of the project components is being carried out by the respective state agencies. In Delhi, part of implementation is the responsibility of the Municipal Corporation of Delhi (MCD). Government of India has already appointed Project Management Consultant, having Tokyo Engineering Consultants (TEC) as the lead partner.
3.2 PROJECT FOCUS
The YamunaRiver and its floodplain represent a key fresh-water resource, although with a deteriorating ecological quality as a result of water pollution. This document seeks to address the problem of wastewater discharge into urban water bodies, through a decentralized approach to wastewater treatment. This issue is more evident in the areas that are un-sewered/inadequately sewered/ have non-functional or partly functional wastewater management in various areas of Delhi, which lie within the jurisdiction of the MCD.
Through the discharge of untreated sewage and the unmanaged surface runoff flowing into these water bodies, their physical and ecological condition is very poor, often resulting in offensive odour, breeding of mosquitoes, and other adverse effects to public health. The dumping of solid waste, construction debris, and accumulation of refuse in some of these water bodies has resulted in a further deterioration of this urban ecological resource. By adopting more localized and decentralized wastewater treatment (DWT) systems, it is possible to address the deteriorating condition of urban water bodies and expect an improvement of the water quality, physical condition, and the ecological quality of these urban water bodies.
Such an approach to DWT for water bodies shall also identify options for wastewater reuse (from DWTs for activities such as ground water recharge, horticulture, pisciculture, and agriculture irrigation). The approach shall further extend to address not only the water bodies but also the water being received into them by natural or anthropogenic processes.
Consultants are expected to outline a clear process for improvement of the same in the context of water quality, physical characteristics, and ecological indicators. An essential part of this effort will be to identify the mechanisms for long term sustainability of the improvement actions proposed in terms of financial viability and community ownership.
3.3 SITUATIONAL ANALYSIS
3.3.1 Wastewater Generation and Sewerage System in Delhi
Water quality and wastewater treatment are one of the major issues facing the city of Delhi. Delhi generates about 3600 MLD of wastewater out of which operational treatment facility is available for 1680 MLD (Source: Central Pollution Control Board- Annual Report 2001-2002). Delhi's population, which stood at 9.37 million in 1991, is now estimated to be around 13 million, and is projected to rise to 20 million by 2010. A total of 2083 MLD wastewater is generated within sewered areas of Delhi.
Even in the areas with sewer networks, all sources of wastewater (including households) are not connected to the sewerage system. As a result, a significant volume of wastewater generated remains untapped and finds its way into the open drains, which empty into river Yamuna, contributing to its pollution load. The total amount of BOD, which is released by direct house-connections or through the open drains does not reach to the STPs in the same quantity, but gets exerted due to decomposition of organic matter during course of travel. The extent of exertion can be indicated by the BOD concentration in the sewage at the inlet of each STP.
Table 3.1: Pollution Load of DrainsMeetingRiver Yamuna in Delhi[1] (January – December 2001)
S. No. / Drains / Flowm3/sec / %
Contribution / BOD Load
Tonnes/day / %
Contribution
1. / Najafgarh Drain / 23.85 / 51.51 / 78.13 / 25.12
2. / Magazine Road / 0.09 / 0.19 / 1.64 / 0.52
3. / Sweepers Colony / 1.21 / 2.61 / 1.04 / 0.33
4. / Khyber Pass / 0.06 / 0.12 / 0.06 / 0.02
5. / Metcalf Drain / 0.08 / 0.17 / 0.38 / 0.12
6. / Mori Gate Drain / 0.48 / 1.04 / 4.66 / 1.50
7. / Tonga Stand / 0.07 / 0.15 / 1.20 / 0.39
8. / Civil Mill Drain / 0.70 / 1.51 / 14.15 / 4.55
9. / Power House / 0.47 / 1.02 / 7.86 / 2.53
10. / Moat Drain / 0.03 / 0.06 / 0.19 / 0.06
11. / Sen Nursing Home / 1.86 / 4.02 / 34.28 / 11.02
12. / Drain No. 12 A / 0.23 / 0.50 / 0.69 / 0.22
13. / Drain No. 14 / 1.59 / 3.43 / 15.27 / 4.91
14. / Barapulla Drain / 1.38 / 2.98 / 9.22 / 2.96
15. / Maharani Bagh / 1.09 / 2.35 / 32.78 / 10.54
16. / Kalkaji Drain / 0.09 / 0.19 / 0.36 / 0.12
17. / Tuglakabad / 0.14 / 0.30 / 1.23 / 0.39
18. / Shahdara Drain / 6.70 / 14.47 / 48.44 / 15.57
19. / Sarita Vihar Drain / 1.10 / 2.38 / 25.42 / 8.17
20. / Drain Near LPG Plant / 0.48 / 1.04 / 2.74 / 0.88
21. / Drain Near Bridge Sarita Vihar / 4.49 / 9.70 / 29.66 / 9.53
22. / Tehkhand Drain / 0.11 / 0.24 / 1.65 / 0.53
i.Total
/ 46.30 / 100 / 311.05 / 100It is observed that there are continuous efforts by Delhi Govt. to augment the treatment capacity, improve sewerage systems, and reduce the pollution load entering the Yamuna. However, the high rate of population growth, and the discharge of sewerage into the urban water bodies and drains is nullifying the results. The gap between sewage generation and treatment is widening in spite of the efforts of the authorities and monitoring by the Hon’ble Supreme Court. Table 3.1 shows the pollution load of drains meeting river Yamuna in Delhi.
Considering that more than 50% of the sewer lines do not reach the existing treatment plants and reportedly about 90 km of the total 131 km of main trunk sewers have collapsed while a majority of over 5,000 km network of branch sewers needs immediate replacement, the crumbling sewage infrastructure is causing the wastewater to come above ground in many places. As a result, sewage at certain locations finds its way into storm water drains and flows directly into rivers/ nallahs (drains) bypassing the treatment plants. In addition, the sewage is often intentionally diverted from the trunk sewer lines to storm water drains to avoid blockages and stagnation of wastewater, resulting in further discharges into the rivers and drains. Under YAP–II, one of the major concerns is to provide a viable wastewater management system that addresses the sewered and unsewered wastewater being generated.
3.4Problem Analysis
3.4.1 Water Bodies in Delhi
Numerous studies and exercises have been undertaken in the past to document and characterize the state of water bodies in Delhi. The protection, management, and restoration of these water bodies is of crucial importance as a contributor to the fresh water resource in the city, as a means to recharge the groundwater, and for the improvement of the urban environment.
Among these numerous water bodies, Delhi has about 38 lakes or natural depressions, many of which are at the verge of extinction due to rapid urbanization of the city. Delhi Tourism has identified as may as 15 ancient lakes within the city limit for reclamation and restoration of water quality.
Information on these selected lakes/reservoirs and their existing uses are presented in Table 3.2 while Table 3.3 indicates the trace metals in Water of Lakes and Reservoirs in Delhi.
Table 3.2: Lakes/Reservoirs in Delhi and their existing uses:
S. No. / Lakes/Reservoir / Location / Existing Uses1. / BhalswaLake / Bhalswa / Tourism
2. / NainiLake / ModelTown / Tourism, wildlife, fishing
3. / Jehangirpuri Marsh / Jehangirpuri near J.J. Colony / Dumping of waste, construction material, sewage from adjoining areas etc.
4. / Mundella Khurd / Mundella Kalan / Cattle wading, wastewater discharge from village, cultivation etc.
5. / MayapuriLake / Mayapuri / Dumping of solid waste, construction material, sewage discharges from slums, open defecation
6. / HarinagarLake (Tihar Jheel) / Hari Nagar / Tourism, fishing
7. / Dwarka Depression / Papankalan / Automobile waste discharge, cattle wading
8. / Bagdola Pond / Bagdola, Papankalan / Tourism, fishing
9. / SanjayLake / Trilokpuri / Tourism, wildlife, fishing
10. / Seelampur Depression / Seelampur / Wastewater discharge from adjoining colonies, open defecation
11. / Jhilmil Colony Depression / Jhilmil Colony Opp. Police Station / Cattle wading, open defecation
12. / JhilmilColonyLake near Hanuman Mandir / Barapulia / Waste water discharge, open defecation
13. / Duckweed Pond / Wazirabad / Duckweed culture, fish culture, waste water treatment
14. / Fish Pond / Wazirabad / Fish culture
Table 3.3 : Trace Metals in Water of Lakes and Reservoirs in Delhi
S. No. / Lakes/Reservoirs / Trace Metals, mg/lCadmium / Chromium / Copper / Iron / Nickel / Lead / Zinc
1. / SanjayLake / NT / 0.02 / NT / 0.58 / NT / NT / 0.06
2. / Tihar Jheel / NT / NT / NT / 3.72 / NT / NT / NT
3. / NainiLake / NT / NT / NT / 0.70 / 0.20 / NT / NT
4. / JhilmilColonyLake / NT / 0.19 / 1.42 / 21.38 / 0.17 / NT / 0.79
5. / BhalsawaLake / NT / NT / NT / 0.75 / 0.04 / NT / NT
6. / MayapuriLake / NT / 0.01 / 0.01 / 0.28 / NT / NT / NT
7. / Mundella Khurd / NT / 0.07 / 0.07 / 15.38 / 0.32 / NT / 0.09
8. / DwarkaLake / NT / NT / 0.01 / 3.36 / NT / NT / NT
9. / Bagdola Pond / NT / 0.02 / NT / 0.49 / NT / NT / NT
10. / Duckweed Pond / NT / NT / NT / 0.39 / NT / NT / 0.03
11. / Fish Pond / NT / 0.05 / 0.02 / 13.99 / NT / NT / 0.01
The project proposed will examine these, and all other water bodies within Delhi, which are adversely affected by the discharge of sewage, with the intent of developing a master plan for a decentralized system for treatment of wastewater entering these water bodies.
3.4.2 Water Quality in Water Bodies
Most water bodies in Delhi are shallow and are silt laden which normally absorb sunrays and warm up more rapidly than clear water. Tihar Jheel and DwarkaLake were the typical example of such phenomenon. The pH of water in various water bodies ranged between 7.00 to 8.04. The high values of conductivity in water of lakes indicate high level of dissolved solids, causing ionic imbalance in a water body to an extent, which may disrupts aquatic life. Maximum concentration of total dissolved solids (4002 mg/l) leading to very high conductivity (6160.0 µmhos/cm2) of water was observed in BhalsawaLake. The increased dissolved oxygen levels in the lakes during daytime depict eutrophic conditions in most lakes/reservoirs. The nutrient level of the lakes in the form of BOD, COD, Nitrites, Nitrates, Phosphates etc. have been found quite elevated. Almost all the lakes/ reservoirs have been affected by faecal contamination. The sources of increased number of total coliforms indicate soil-originated contamination of the water bodies.
3.4.3 Background Studies
Under Yamuna Action Plan Phase – I, a study was conducted in year 2001 to find out the options of treatment of wastewater from unauthorised areas or areas where the sewerage facility could not be provided up to 10 years. It was proposed that Decentralised Waste water Treatment (DWT) is the suitable option.
Subsequently, MCD conducted a study of major water bodies to explore options to protect the existing water bodies. The objective of the study was to demonstrate the scope of decentralised wastewater management in urban setting like Delhi, the technologies best suited to serve each area, and the options available for wastewater reuse for non potable purposes and / or ground water recharge. Based on the above study, site visits were taken by MCD and a few sites were identified for DWT implementation.
3.5Decentralized Wastewater Treatment
The decentralized concept of wastewater management provides a framework for an "alternative" to the conventional, centralized system, and which in many situations may also be more fiscally reasonable, more socially responsible, and more environmentally benign than conventional practice. The decentralized concept holds that wastewater should be treated-and beneficially reused, where practical, as close as possible to where it is generated, with the least capital cost, operating cost and implementation time. DWT makes sewerage treatment a sustainable activity. As the concept suggests, the decentralization process dictates that the overall systems would be composed of many small wastewater collection/treatment facilities. Large catchments areas would be dividedinto a number of smaller zones with independent treatment facilities. Also the decentralized concept systems can be designed and installed in response to development only as it occurs.
Broadly stated, DWT examines conventional and other low-cost, low-tech sewerage design and construction practices and adjusts them to reflect the environment and affordability of recipient communities. In most cases this produces a reduction in cost but there is also some easing of institutional responsibility. The DWT system may also comprise of several smaller subsystems for collection, treatment and reuse, allowing expansion and replication as the demands of the community increase.
Advantages of opting for Decentralized wastewater management Systems
- Increased use of onsite management to remove grit and bulk solid matters.
- Lesser cost of sewage collection and management of sewerage system, Use of alternative collection systems by avoiding big pumping stations
- Easy management of the wastewater due to its lesser volume, Cost effective treatment technology, Treatment processes tailored to the wastewater stream from each separate subsystem.
- Progressive construction possible as modules. No need for large investments in main trunk sewers and lift stations to transport wastewater away from the communities to the wastewater treatment plants. In contrast, intensive investment has to be made for centralized systems, which often are initially oversized but become undersized.
- Because less depth trench is used, construction will be quicker.
- Reuse opportunities are often within or near the generating community for landscaping, and agriculture for industry for revenue to operate the existing treatment system.
- Involvement of people/builders/developers in the wastewater treatment and management.
- Decentralized management retains polluting fecal matter closer to its source and thus reduces the spread of pollution.
- The probability of simultaneous failure of all smaller systems is significantly lower than that of failure of one system serving all the community.
3.5.1Considerations for Development of DWT for Urban Water Bodies
Taking into consideration the available water in the water bodies, the available space around the water body, associated societal use and practices related to the water and the water body, the contributors to its pollution, and the desired end-purpose, the design of an appropriate DWT system and water body improvement program can be undertaken.
3.5.2Technology Options
Technology assessment is required to identify feasible options of treatment of municipal wastewater and to review the state of the art. While the focus of this project is to review low-cost systems such as constructed wetlands, oxidation ponds, and aerated lagoons, etc., the technological diversity in the development of these requires careful consideration, especially in the context of operation and maintenance efforts.
A. Wetland Systems
"Natural wetlands are considered to be areas where the water surface is at or above the ground surface for a long enough time each year to maintain saturated soil conditions and the growth of related vegetation." These natural systems have inherent ecological characteristics to treat the water, improving its quality, providing natural habitat flora and fauna, and promoting the recharge of groundwater aquifers.
Mimicking the functional benefits of these natural systems, artificially constructed wetlands are developed to help improve water quality through the use of naturally occurring plants, micro-organisms, and other natural processes.
There are three major types of constructed wetlands that mimic these natural systems: Free Water Surface (FWS), Horizontal Subsurface Flow (HSF) and Vertical Flow (VF) systems. These systems consist of a series of connected ponds or reed beds through which the wastewater flows. All constructed wetlands are designed to prevents untreated wastewater from infiltrating and potentially contaminating groundwater. Aquatic plants are introduced within constructed wetland systems that are capable of thriving in saturated, nutrient-rich conditions. Because constructed wetlands mimic natural native systems, there is often a level of increasing native species diversity as the system progresses and nutrient and organic compound levels decrease.
B. Functions of Wetlands
The following functions are processes that occur because of the physical and biological character of wetlands. They reflect the primarily hydraulic nature of these sites:
-Groundwater Recharge
-Groundwater Discharge
-Floodwater Alteration
-Sediment Stabilization
-Sediment/Toxic Retention
-Nutrient Removal/Transformation
-Production Export
-Aquatic diversity/Abundance
-Wildlife Diversity Abundance
C. On-site treatment system
In case of lake or pond where the wastewater from the nearby populated area flows directly into it, treatment techniques can be provided depending on the space available, inclusive of the water body and the land around it, to treat the wastewater flowing into the water body.
D. Riverine Wetlands
"Riverine" refers to a class of wetland that has a floodplain or riparian geomorphic setting. The water sources for the riverine class are precipitation, surface flow, and groundwater discharge. Surface flow consists of overbank flow when channel capacity is exceed by discharge and overland flow that parallels the soil service when precipitation fails to infiltrate. The groundwater source includes discharge from saturated and unsaturated sources.
The continuous nature of these three sources makes it difficult to separate classes based on water source alone. Riverine wetlands occur in floodplains and riparian corridors in association with stream and river channels. They continue upstream until the features of channel (bed) and bank disappear, and are replaced by slope wetlands, poorly drained flats, depressions, or uplands. Large riverine wetlands may themselves contain sites with affinities to other classes. Rivers and floodplains are assumed to be integral parts of the riverine wetland ecosystem.