Nmmc Sewerage Dpr

Underground Sewerage project under JnNURM Detailed Project Report

Navi Mumbai Municipal Corporation, Navi Mumbai 1

VOLUME-1 INTRODUCTION

SECTOR BACKGROUND CONTEXT & BROAD PROJECT RATIONALE ............................. 5 1.1 Existing status of physical infrastructure.......................................................................... 5 1.1.1. Geography:.................................................................................................................... 5 1.1.2. Location and Connectivity:........................................................................................... 5 1.1.3. Geology......................................................................................................................... 6 1.1.4. Topography................................................................................................................... 6 1.1.5. Climate.......................................................................................................................... 7 1.1.6. Temperature .................................................................................................................. 7 1.1.7. Rainfall.......................................................................................................................... 7 1.1.8. Humidity ....................................................................................................................... 7 1.1.9. Wind.............................................................................................................................. 7 1.1.10. Soil ................................................................................................................................ 7 1.2 Demography...................................................................................................................... 7 1.2.1. Existing Population....................................................................................................... 7 1.2.2. Population Density........................................................................................................ 9 1.2.3. Assumptions.................................................................................................................. 9 1.2.4. Population Projections for NMMC area-2042............................................................ 10 1.3 Land use .......................................................................................................................... 10 1.4 Existing scenario of sewerage system in NMMC & Need For Project .......................... 11 1.4.1. Water Demand and supply projections as base for sewage collection ....................... 13 1.4.2. RECENT PROJECT: .................................................................................................. 14 1.4.3. Existing Tariff & Cost Recovery Methods ................................................................. 14 1.4.4. Private Sector/ Community participation.................................................................... 14 1.4.5. Key Issues ................................................................................................................... 15 1.4.6. Long Term Improvements. ......................................................................................... 15 1.4.7. Short Term Improvements. ......................................................................................... 16

CHAPTER-2................................................................................................................................... 18 PROJECT DEFINITION, CONCEPT & SCOPE ..................................................................... 18

2.1. Land .................................................................................................................................... 18 2.2. Physical infrastructure component...................................................................................... 19

2.2.1. Scope of Work ............................................................................................................ 19 2.2.2. Methodology for computation .................................................................................... 21 2.2.3. Wastewater Quality..................................................................................................... 22 2.2.4. COLLECTION SYSTEM DESIGN CRITERIA........................................................ 23 2.2.5. DESIGN BASIS OF SEWAGE PUMPING STATION............................................. 29 2.2.6. Design Basis for Sewerage Treatment Plant............................................................... 30

2.3. Environmental Assessment of Sewerage System ............................................................... 31 2.3.1. Air quality: .................................................................................................................. 31 2.3.2. Noise quality: .............................................................................................................. 32 2.3.3. Vegetation:.................................................................................................................. 32 2.3.4. Soil investigation & Water level................................................................................. 32 2.3.5. Meteorological profile ................................................................................................ 32

2.4. Environmental Impact Assessment Of The Improvement Schemes And Mitigation Measures 33 2.4.1. Impact of the project on air quality:............................................................................ 33 2.4.2. Impact of the project on noise level:........................................................................... 33 2.4.3. Air Pollution Mitigation:............................................................................................. 34



2.4.4. Noise Pollution Mitigation:......................................................................................... 34 2.4.5. Mitigation for loss of vegetation:................................................................................ 34

2.5. Environmental Management Plan....................................................................................... 35 2.5.1. Environmental Management Measures....................................................................... 35 2.5.2. Cost Estimates for Environmental Protection............................................................. 49 2.5.3. Institutional Set-up and Coordination For Environmental Management.................... 49 2.5.4. Reporting Requirements ............................................................................................. 51 2.5.5. Institutional Strengthening.......................................................................................... 52 2.5.6. Training Program........................................................................................................ 52

2.6. Rehabilitation & Resettlement............................................................................................ 53 2.7. Specialized Procured Services ............................................................................................ 54 2.8. Other Information ............................................................................................................... 54 2.9. Utility Shifting .................................................................................................................... 54 2.10. Clearance............................................................................................................................. 55 2.11. Disaster related Risk Assessment ....................................................................................... 55 2.12. Risk Management ............................................................................................................... 57

2.12.1. Vulnerability Assessment ........................................................................................... 57 2.12.2. Vulnerability Assessment ........................................................................................... 57 2.12.3. Administrative aspects and response capacity............................................................ 58 2.12.4. Physical aspects and impact on the service................................................................. 58 2.12.5. Mitigation and emergency measures .......................................................................... 58 2.12.6. Types of hazards and their consequences of water and sanitation systems................ 59 2.12.7. Floods.......................................................................................................................... 60

PROJECT COST ............................................................................................................................ 62 PROJECT INSTITUTION FRAME WORK.................................................................................. 63

4.1 Existing Institutional frame work for Sewerage system in Navi Mumbai...................... 63 4.1.1. Manner of under taking construction work (Construction Agency):.......................... 63 4.1.2. Involvement of construction entity in the subsequent O & M activity:...................... 63 4.1.3. Scope of Public Private Partnership............................................................................ 64 4.1.4. Involvement of Private Sector in Construction Phase ................................................ 64

PROJECT FINANCIAL STRUCTURING .................................................................................... 66 5.1 Overall financial structuring ........................................................................................... 66 5.2 Grants under JNNURM .................................................................................................. 66 5.3 Financial Returns ............................................................................................................ 67 5.4 Review Options for ......................................................................................................... 67

PROJECT PHASING ..................................................................................................................... 68 6.1 Schedules for Tendering/selection of procurement of services ...................................... 68 6.2 Construction contractors ................................................................................................. 68 6.3 Consultants...................................................................................................................... 68 6.4 Specialized Activities: .................................................................................................... 68 6.5 Schedule for bringing in state level and ULB level contributions to the project...75 6.6 Schedule of clearance ..................................................................................................... 68 6.7 Schedule for shifting utilities .......................................................................................... 68 6.8 Project infrastructure component wise implementation ................................................. 68 6.9 Key Mile Stone ............................................................................................................... 69 6.10 PERT & CPM Chart ....................................................................................................... 70

PROJECT O & M PLANNING...................................................................................................... 73 7.1 Possible O&M Framework ............................................................................................. 73 7.2 Performance based Contract ........................................................................................... 73



7.2.1. Customer Service ........................................................................................................ 74 7.2.2. Customer Complaints.................................................................................................. 74 7.3 Tariff & User Cost Recovery.......................................................................................... 74

PROJECT FINANCIAL VIABILITY & SUSTAINABILITY...................................................... 75 8.1 Overall project perspectives............................................................................................ 75 8.2 ANNUAL MAINTENANCE ......................................................................................... 75 8.2.1. Revenue Structure....................................................................................................... 75 8.2.2. 0& M Costs & Revolving Fund.................................................................................. 75 8.2.3. Assumptions of Financial Analysis ............................................................................ 76 8.2.4. NMMC level perspectives and financial situation assessment ................................... 76

PROJECT BENEFIT ASSESMENNT........................................................................................... 79 9.1 Positive Impact.................................................................................................................... 79 9.2 Negative Impact .................................................................................................................. 79 9.3 Mitigation measures............................................................................................................ 80

Annexure-1 Recapitulation sheet and cost estimates VOLUME-2

Collection System: Cost Estimates, Measurement sheets & Design outputs.

VOLUME-3 L-sections & Drawings



INTRODUCTION

The Government of India has announced the Jawahar Lal Nehru National Urban Renewal Mission (JNNURM) for certain

cities of India with this aim to achieve systematic development in these cities keeping in view the futuristic planning for 30

years. In this JNNURM it is expected to prepare Mission document under urban Infrastructure & Governance elaborating

the existing situation of various aspects of the city and the master plan of future development of city with the methodology

for fulfilling the gaps and to achieve various milestones. The JNNURM will provide financial aid to the city as per norms

prescribed.

Navi Mumbai (Marathi: , IAST: Navi Muba), formerly known as New Bombay, is a twin city of Mumbai, India. It was developed in 1972, and is the largest planned city of the world, with a total area of 344 km out of which 163 km is

developed and transferred to the jurisdiction of the Navi Mumbai Municipal Corporation (NMMC)[1]. Navi Mumbai lies on

the mainland on the eastern seaboard of the Thane Creek.

This detailed project report is for improvement of underground sewerage system in Navi Mumbai city, in view of achieving

the goal of Jawahar Lal Nehru National Urban Renewal Mission (JNNURM) in creating infrastructure. While preparing this

DPR, it has been tried to provide sufficient details to ensure appraisal, approval & subsequent project implementation in a

timely & efficient manner.



CHAPTER-1

SECTOR BACKGROUND CONTEXT & BROAD PROJECT RATIONALE

1.1 Existing status of physical infrastructure

Navi Mumbai is worlds largest planned city with a horizon of 344sqkms. It includes an area of 95 villages in it,

having a coastal stretch of 34.2 kms along Thane and Panvel creeks. To avoid the haphazard spill over of Mumbai,

Plan for Mumbai Metropolitan Region (MMRP) was prepared under the provision of Maharashtra Regional and

Town Planning act 1966, which was sanctioned by Govt in 1973. One of the most important propositions of the

sanctioned MMRP was to develop a new metro city in Trans Thane creek and Trans harbor area extending inland

up to Panvel and Uran.The new metro city was subsequently named as New Bombay (Now Navi Mumbai). It

comprises of the strip of marshy land lying between village Dighe in Thane district and Kalundre village of Raigad

district parallel to the then Greater Bombay. The City & Industrial Development Corporation of Maharashtra Ltd

(CIDCO), a Company fully owned by the state Government, was declared as New Town Development Authority

under the Provisions of MRTP Act, 1966, to plan and develop the city of Navi Mumbai. For this purpose, the State

Govt. notified all the privately owned lands within the notified area of Navi-Mumbai for acquisition under the L.A.

Act. The land so acquired by State Government was vested in CIDCO for the development and disposal purpose.

CIDCO carved out 14 nodes (small townships) of the land with a view to facilitate comprehensive development and

to give it an identity of new city. These nodes are named Airoli, Ghansoli, Kopar Khairane, Vashi, Sanpada, Nerul,

CBD Belapur, Kharghar,Kalamboli, Jui Kamothe, New Panvel, Ulwe, Pushpak and Dronagiri. As the city grew in

size, a need was felt to create an urban local body to take care of day to day maintenance of the city as well as

other functions such as public health, primary education etc. which was not the mandate of CIDCO. The NMMC

accordingly came into existence on 1st Jan.1992 with its jurisdiction covering 29 villages out of Navi Mumbai project

area and another 15 villages from Kalyan complex area (Total of 44 villages from Thane Taluka) with a combined

area of 162.5 sq.Km. This area is known as NMMC Area. Subsequently the developed nodes within the jurisdiction

of NMMC were transferred by CIDCO to NMMC for maintenance purpose although CIDCO continues to own and

develop vacant land within these nodes as the14 development authority. All the capital and revenue expenditure in

these nodes is borne by NMMC.

1.1.1. Geography: NMMC area is spread in district of Thane in Maharashtra. It is located in latitudes of 20 N 73 E. It consists of hilly

areas and certain parts under wetlands.

1.1.2. Location and Connectivity:

NMMC area lies on the eastern main land of Thane creek. It starts from Digha, Airoli in the north and Nerul Belapur

in the south. NMMC area is well connected to Greater Mumbai and other cities like Thane and Pune. Apart from the

decades old Thane creek bridge connecting Mankhurd with Vashi, there are two road bridges and one rail link and

third connection via Sewri is proposed by MSRDC. Seven railway stations on Mankhurd- Belapur line at different

nodes provide full connectivity to NMMC area up to Kurla. Five railway stations on Thane Sanpada line also

connect Kalyan via Kalwa. A new international airport is also planned in Navi Mumbai region.



1.1.3. Geology

The rock formation in the region is derived mainly from Deccan Basalt and also from granites, gneisses and laterite.

The gently sloping coastal low lands are observed in patches and are covered with moderately shallow to deep

soils, mostly lateritic in nature, sometimes oxidized to yellow murrum.

1.1.4. Topography

To part of Western Konkan coast is a narrow coastal strip along the western part of Sahyadris. It is bound on the

eastern side by hillocks of height of 50-200 mt. and on the west side by Thane creek.

Map-1: Location map of NMMC area



1.1.5. Climate

This area has sub-tropical monsoonal climate of humid-per-humid to semi-arid and sub humid type. Overall climate is equable with high rainfall days and very few days of extreme temperatures.

1.1.6. Temperature The mean annual temperature ranges from 25C to 28C. The mean maximum temperature of the hottest month in this area varies from 30C - 33C in April-May while mean minimum temperature of coldest month varies from 16C to 20C. Extremes of temperatures, like 38- 39C in summer and 11-14C in winter, may be experienced for a day or two in respective season.

1.1.7. Rainfall The rainy season is mostly confined to south-west monsoon with 80 percent of the rainfall received during June to October (60-70 days). This area, on an average, receives 2500 to 3500 mm rainfall.

1.1.8. Humidity The area has marine humid-per humid climate with more humidity and less daily variations. Relative humidity varies from 41 to 97%. Driest days being in winter and wettest ones are experienced in July. 16

1.1.9. Wind Features such a presence of large water body (the creek), presence of hill ridges etc. influence the local wind patterns to some extent. No significant micro-climatic variation is noticeable in the region.

1.1.10. Soil The soil of this area is highly saline in the vicinity of creeks and non-saline at other places. They are calcareous, neutral to alkaline in reaction (pH 7.5 to 8.5), clayey, with high amount of bases and have high water holding capacity (200-250 mm/m). The soils located on moderately sloping residual hills are lateritic in nature and show intensively leached surfaces. They are loamy and slight to moderately acidic (pH 5-6.5) with moderate base status (< 75%)

1.2 Demography

1.2.1. Existing Population To review the overall growth of a city, socio-economic indicators play an important role. These indicators give a true picture of the level or standard of living city is offering to its inhabitants. Also gives measuring tool to rate city over the surrounding settlements.



Below a picture has been presented of NMMC area from the year of establishment.

Table 1 Population in NMMC

Table 2 Population in NMMC area (2001 Census)

Year Total Population Source 1971 116789 Census 1981 198290 Census 1991 387206 Census 1995 475301 SES CIDCO 2001 703947 Census 2002 726126 UHP Survey 2003 759311 UHP Survey 2004 846100 UHP Survey 2005 875311 UHP Survey



It is very evident that a major change in the demographic profile has been seen in NMMC area after creation of MIDC to NMMC area and projects like JNPT and APMC were initial growth triggers for development in the area. With affordable housing in NMMC area a shift was observed among the people from Greater Mumbai to this part of land. Since the facilities and amenities are worked out for the city from day one, as it is a planned city, so infrastructure was also an attraction for this place which justifies the growth rate which NMMC area has experiences over last two decades.

1.2.2. Population Density NMMC area has population density of 4167 persons per square km. the figures show, comparatively, Greater Mumbai has density of 26722persons per sqkm and eastern suburbs have density of 20140 persons per square km, whereas western suburbs have density of 24605 persons per sqkm as compared to the most dense Mumbai island where density is 49163 persons per sqkm. Population projections Projections provide a base for determining the future needs. Based on past trends and internal and external factors, assumptions are framed and thus population projections are worked out. It is very crucial to determine the growth trends as it gives base data to estimate the physical and social infrastructure.

1.2.3. Assumptions NMMC area is a fast developing city. Due to the expedition of regional economy and availability of residential areas, a shift has been observed to NMMC area. Based on the following assumptions the population projections for year 2042 have been worked out: Average of Annual growth rates from 2001 to 2006 is considered for projecting population from 2006 onwards till the nodes attain full development except For Belapur population figures from 2002 onwards are projected as per the UHP (Urban Health Post) survey as it is considered to be the latest one. After the nodes attain full development Growth rate of 2% annually is considered (1% as natural growth rate and 1% due to migration on account of proposed airport, proposed SEZ and expansion of sea port and IT parks). Redevelopment of existing properties and redevelopment of slums pockets and other congested areas like gaothan would create space to accommodate the above additional population. As projected in Draft development Plan, growth rate of 3% per annum is considered for Dahisar up to 2015 and 10% thereafter. It is assumed that by 2015, the nodes developed by CIDCO will attain full development . For existing population of various nodes survey data of UHP has been used from year 2002 to 2005.



Exceptional and negative growth rates are not considered for calculating average annual growth rate and are calculated based on Arithmetical Progression Method.

1.2.4. Population Projections for NMMC area-2042 Based on above mentioned assumptions, projections for population have been worked out as below:

Table 3 Population Projection in NMMC Population-Villages

Name of Village

Population 2042

Name of Village

Population 2042

Belapur 40381 Kopari gao 48526 kille 84469 Juhu gaon 65561

Diwale 27363 KK gao 25530 Agroli 14435 Bonkode 50415 Nerul 47025 Gothivali 105144

Shirvane 25852 Talavali 64937 SARSOLE 40437 Airoli gao 32001 DARAVE 44923 Diva 17860

KHARAVE 63097 sanpada

gao 13002 Vashi Gaon 8202 Jui pada 14736

Turbhe Gaon 50377

1.3 Land use After formation of NMMC on 1st January1992, 29 villages in CIDCO and 15 of Kalyan notified area were included in its municipal area. Total area under jurisdiction of NMMC is 162.5sqkm. Land use plan of NMMC area depicts that major area (almost half of total area) is under residential activity followed by regional parks and forest areas and industrial areas. At present, agricultural activity in NMMC area is extremely limited. 26.65sqkm (16.35%) of total area of NMMC is under forests. The land use distribution in NMMC is as shown in the following chart.

Year Total Population Source 2006 925346 UHP Projection 2011 1293987 Projected 2021 1879274 Projected 2031 2388082 Projected 2042 2911032 Projected



At the city level, the institution responsible for delivery of water supply is NMMC the flow chart shows the various functions performed by NMMC in Water Supply delivery and their linkages. The decision to undertake the project is taken by NMMC. The plan preparation, construction of reservoirs, laying of transmission lines and distribution lines, their maintenance and financial inputs are all bear by NMMC and State Government. The NMMC is also involved in providing house connections and collection of registration and user charges.

Investment Plan: 2007 2012

(Rs. Lacs)

City

Infrastructure

Basic Services to Urban Poor Total

Share in Total

Water 45800 5656 51456 20.00%

Sewerage 29325 5100 34425 13.40%

Drainage 27200 2900 30100 11.70%

Solid Waste Management 22550 350 22900 8.90%

Transport 37079 3134 40213 15.70%

E Governance 810 810 0.30%

Housing for Urban Poor 76921 76921 30.00%

Overall for NMMC 162765 94061 256826 100.00%

Proportion of Total .. 63.40% 36.60% 100.00%

1.4 Existing scenario of sewerage system in NMMC & Need For Project

A well planned basic system comprising trunk and main sewers exists in NMMC area. Total length of

sewer is 306.412Km. About 80 % of area of developed nodes in NMMC is covered by underground

drainage system with trunks and mains with due and developing sub-mains and laterals. There are total

8 numbers of sewage treatment plants in NMMC area located at CBD Belapur, Sanpada, Nerul, Vashi,

Koparkhairane & Airoli. The raw sewerage generated in NMMC area is about 244.00 Mld.



NMMC has commissioned STPs at Vashi, Airoli and Nerul with state of art technology recently. The

STPs are giving excellent results. The STPs are designed for 5 mg/l BOD discharge of treated sewage.

The treated sewage shall be at par with drinking water. There is tremendous potential for recycle for

treated sewage. The Re-constructed STPs Shall improve environmental condition in NMMC area to the

maximum possible.

NMMC has redesigned sewerage system at Airoli sector-3, Koparkhairane Sector-14, Vashi Sector 1&2

, Kopari sec-26, Nerul sec-50 And converted the sewerage system in gravity flow. This has resulted in

elimination of SPS-3 Airoli, SPS -14 Koparkhairane, SPS-26 Kopari, SPS-3 Vashi, SPS-17 Vashi and

SPS-50 Nerul. This has saved appreciable cost of electrical energy and O & M cost. This shall lead to

improved environmental conditions in nearby locality.

Remaining part of the city which has left out from earlier coverage of sewerage schemes needs to be

sewered on priority as the development have taken place in unprecedented manner in those localities.

Also few smaller diameter sewer lines needs to be replaced which are either are in broken or highly

deteriorated condition.

All the STPs for Navi Mumbai were constructed 35 to 35 years ago based on conventional approach.

Most of them were deteriorated and was in need of rehabilitation or reconstruction. Out of total eight old

STPs NMMC recently discarded and constructed three no of STPs at Vashi, Airoli and Nerul based on

SBR technology. The physical status of remaining STPs is very bad. Those also needed to be replaced

on priority.

The original sewage collection, conveyance and treatment system for Navi Mumbai was designed by

CIDCO for water supply rate of 180 lpcd with 50 % infiltration for ultimate population based on land use

pattern . The system comprises of NP 2 ,NP 3 RCC piped collection system,19 no. of sewage

pumping stations and 8(eight) number of sewage treatment plants.

Details of Existing Sewer lines in NMMC area

Sr.no. ZONE Length Of Sewers, Km 1 CBD Belapur 39.309

2 Nerul 63.693

3 Vashi 37.111

4 Turbhe/Sanpada 29.561

5 Koparkhairane 66.836

6 Ghansoli 14.382

7 Airoli 29.880 TOTAL 306.412



Existing Sewage Treatment Plants in NMMC Area

Sr.No. Node Location Sector

Capacity MLD

Treatment Scheme

1 Belapur 12 21 Facultative Lagoon with aerators

2 CBD 26/27 0.15 Facultative Lagoon 3 Nerul 2 17 Aerated Lagoon 4 Nerul 50 100 Cyclic Aerator Sludge

technology 5 Sanpada 21 31 Work in Progress 6 Vashi 18 100 Cyclic Aerator Sludge

technology 7 Koparkha

irane 14 36 Aerated Lagoon

8 Airoli 18 80 Cyclic Aerator Sludge technology

TOTAL 385.15

1.4.1. Water Demand and supply projections as base for sewage collection The water demand and supply unto 2042 is calculated as per the population projections done

in earlier chapter. The projections are done by considering the water supply as 150 lpcd. The

water supply falls short to the demand only in 2042 with water supply of 450 MLD and corresponding sewage flow

generated will be 392 Mld excluding infiltration.

The projections are as given below

Table 8 : Projected Water Demand Node wise (including 15 % losses)

2005 2015 2025 2035 2040 2042Belapur 10 17 22 27 30 31 Nerul 31 63 76 93 103 107 Vashi 27 41 50 61 67 80 Kopar Kahirane 20 30 36 44 49 51 Ghansoli 7 13 24 33 36 38 Airoli 14 29 35 42 47 49 Sanpada 9 17 20 25 27 29 TTC 15 36 56 69 76 79 Digha 13 22 27 33 36 38 Total MLD 147 266 347 427 471 502



1.4.2. RECENT PROJECT:

Recently NMMC has commissioned STPs at Vashi, Airoli and Nerul with state of art ( SBR) technology

. The STPs are giving excellent results. The STPs are designed for 5 mg/l BOD discharge of treated

sewage. The treated sewage shall be at par with drinking water. There is tremendous potential for

recycle for treated sewage. The Re-constructed STPs Shall improve environmental condition in NMMC

area to the maximum possible.






1.4.3. Existing Tariff & Cost Recovery Methods

Capital expenditure & Operation expenditure of Sewerage sector is met with sewerage tax 3% & sewerage benefit tax included which is part of property tax. Sewerage tax for residential area is 3% for non residential area is 7%. Sewerage benefit tax is 1 % for residential area & 2% for non residential area.

1.4.4. Private Sector/ Community participation

NMMC is executing most the works by Private Sector Participation. The overall strength of NMMC staff is small hence overhead expenses are minimum. Existing areas of private sector / community participation are given in details in following Table 1.6.1

Sewage Generated Node/Year 2005 2015 2025 2035 2040 2042

Belapur 7 12 15 19 21 22 Nerul 22 44 53 65 72 74 Vashi 19 29 35 42 47 56

Kopar Kahirane 14 21 25 31 34 35 Ghansoli 5 9 17 23 25 26

Airoli 10 20 24 29 33 34 Sanpada 6 12 14 17 19 20

TTC 10 25 39 48 53 55 Digha 9 15 19 23 25 26

Total MLD 102 186 241 297 328 349



Table 13 : Existing Areas Of Private Sector/Community Participation In NMMC

1.4.5. Key Issues

The sewerage system in Navi Mumbai was conceptualized, designed and constructed by CIDCO from

1975 to 1990 and was handed over to NMMC. That means the age of existing sewerage infrastructure

is between 15 to 30 years. As far as collection system in the area is concerned, it is giving excellent to

average service till date. Although about 10 to 15 % of collection system needs the replacement, the

remaining collection system is expected to be serving satisfactorily for next eight to ten years after

which it may need replacement/rehabilitation.

This project is classified into two categories,

A) Long Term improvements.

B) Short Term improvements.

1.4.6. Long Term Improvements.

The sewerage system in Navi Mumbai was conceptualized, designed and constructed by CIDCO from

1975 to 1990 and was handed over to NMMC. That means the age of existing sewerage infrastructure

is between 15 to 30 years. As far as collection system in the area is concerned, it is giving excellent to

average service till date. Although about 10 to 15 % of collection system needs the replacement, the

remaining collection system is expected to be serving satisfactorily for next eight to ten years after

which it may need replacement/rehabilitation.

The phase wise replacement and or repair/rehabilitation program may be conducted ahead of 2016.

Table showing priority wise need for replacement of collection system and pumping stations as per the

age of construction.



Node No. Node Replacement work

Planned Initiation year

1 Vashi 2016

2 CBD 2017

3 Nerul 2018

4 Koparkhairne 2019

5 Airoli 2020

6 Ghansoli 2021

The detailed conditional assessment survey of all the components shall begin in the year 2012 -13 and

a phase wise replacement plan shall be implemented accordingly.

1.4.7. Short Term Improvements.

Recently NMMC has commissioned STPs at Vashi, Airoli and Nerul with state of art technology

recently. The STPs are giving excellent results. The STPs are designed for 5 mg/l BOD discharge of

treated sewage. The treated sewage shall be at par with drinking water. There is tremendous potential

for recycle for treated sewage. The Re-constructed STPs Shall improve environmental condition in

NMMC area to the maximum possible.






In addition to above it is necessary to augment existing collection system with two number of additional

sewage pumping stations and three number of sewage treatment plants.



Proposed immediate improvements

Sr No.

Components

1 Reconstruction of old STPs

2 Inclusion of left out part in city area under sewage collection system

3 Inclusion of 100 % Gaothan area under sewer network

4 Construction of additional pumping stations



CHAPTER-2 PROJECT DEFINITION, CONCEPT & SCOPE

2.1. Land

Total quantity of the land required for the project particularly for Sewerage treatment plant or pumping station is available with Navi Mumbai Municipal Corporation.

Sr.No Project Components

Land Acquisition

required Yes/No

Area M2

Location Owner Remarks/Details .

1 Working Survey

NO ---- ---- ---- ----

2 Augmentation to Collection Network

No ---- ---- ---- Sewer lines are to be laid along the existing internal road the right of way for which is

already with NMMC

3 Sewage Pumping Stations

No 10500

9000

Vashi Sector-31

Dighe

NMMC

The Land is possession Of

NMMC. The detailed location sketch is

attached. 4 Sewage

Treatment plant No 48530

36480

62500

CBD Sector -12

Sanpada Sector -21

KoparKh. Sector-16

The Land is possession Of

NMMC. The detailed location sketch is

attached.

5 Miscellaneous Works

Security Guard Rooms, Compound

walls, etc

No ---- ---- NMMC ----

Guard rooms etc. are proposed in premises of existing pumping stations the land for which is already in

hold of NMMC

6 Computer, Plotters, GPS etc.

No ---- ---- ----

7 Communication strategy, public awareness campaign etc.

No. ---- ---- ----



2.2. Physical infrastructure component

2.2.1. Scope of Work

The major project components are as follows

I. Collection & conveyance System

The Collection & conveyance System is essentially consists of providing & laying of 148 kms of Np-4 & NP-

3 category of RCC pipes having diameters ranging from 150 mm to 1200 mm.

The collection system is to be laid in following villages and zones for left out and newly developing areas:

Sr.No. Name of Village Network Length m

1 Agroli 471

2 Airoli 1756

3 Belapur 1340

4 Bonkade 1086

5 Darave 1373

6 Digha 2236

7 Divagaon 980

8 Diwale gaon 908

9 Gothovali 956

10 Juhu gaon 1441

11 Jui nagar 827

12 Karave 3811

13 kk 1801

14 Kopari 1002

15 Nerul gaon 2149

16 Sanpada 1100

17 Sarsole 387

18 Shirvane 1576

19 Turbhe 601

20 vashigaon 826

21 Ghansoli gaon 2141

22 Killa Gaon 2803

23 Talavli 855



City Area (Node) wise length

No Node Network Length

Km

1 C.B.D 1.327

2 Airoli 15.18

3 Koparkhairne 30.60

4 Nerul 18.80

5 Sanpada 24.10

6 Vashi 27.92

II. Sewage Pumping Stations

Two number of Sewage Pumping stations of 10 Ml and 2 Ml capacities are to be provided in Vashi and

Digha node respectively.

III Raw Sewage Pumping Mains Providing lowering laying 250 mm dia, 3800 m and 450 mm dia 450 mm 2300 m ductile iron raw

sewage pumping mains from sewage pumping stations to STPs

IV Sewage Treatment Plants Three no. of sewage treatment plants at following location and capacities are proposed under this project.

Sr.No. Location /Node Capacity of STP

1 Koparkhairne(/Ghansoli) 87.5 Mld

2 Nerul 37.5 Mld

3 C.B.D 19 Mld

V Treated sewage Pumping main for reuse (Ring Mains)

The treated sewage effluent will be supplied to bulk industrial customers by pumping.

Sr No. STP Location Reuse quantity to be

pumped

ML

Diameter

mm

Length

m

1 Airoli 10 450 2100

2 Koparkhairane 10 450 4600

3 Vashi 10 450 2400

4 CBD 10 450 2100

VI. Miscellaneous Works Miscellaneous works consisting of construction of Security Guard Rooms, Meter Rooms, Compound

walls, etc. around STPs.



VII. Project Office & Computer, Plotters, GPS etc.

The municipal Corporation is in the process of implementing sewerage scheme and this shall require

considerable establishment for implementation & further operations & maintenance of the scheme.

VIII. Provision for Communication strategy, public awareness campaign for water tariff rationalization and judicious use of water assets

Since the cost of water & its treatment is high it is essential to have public awareness campaign for

judicious use of water and avoid water wastage, provision is made in the estimate to take up such

campaign. Also the treated water is supposed to be reused by industries and housing societies which

requires an effective communication program & awareness campaign.

IX. Shifting of Existing Utilities

Since the collection and conveyance pipelines are required to be laid on main roads which shall require

shifting of utilities like telephone cables , electric cables , water pipelines etc. for which the payment has

to be made to the relevant departments for shifting them.

X. Construction of staff quarters, vehicles etc.

Constructions of staff quarters, project vehicles, staff training and institutional strengthening have been

made.

2.2.2. Methodology for computation

i) For the purpose of design, the wastewater generated is estimated considering Water supply rate as

150 lpcd and it is assumed that 80% of the water supply reaches the sewerage system.

ii) The quantum of wastewater in a given area is related to its water use as most of the flow to the

sewer system is derived as a portion of water supplied to that particular area and returned as spent

water. This percentage of spent water joining the sewer system is expressed as a return factor.

iii) The wastewater collection system consisting mainly of a network of sewers should have the capacity

to receive these flows over the design period from the contributory population or users and convey

through a system of pumping stations and gravity mains/ pumping mains finally to the point of

treatment.

iv) Wastewater generated would comprise domestic wastewater from residential, commercial

and institutional use and from industries/ industrial areas and infiltration.

v) Infiltration into the wastewater system occurs through defective sewers manholes etc. The

rate of infiltration into sewers also depends upon the ground water table and permeability of

the surrounding soil. Through strict quality control and good workmanship will ensure



minimum infiltration in initial but the same may increase as the system condition deteriorated

with age. It is normal practice in the Hydraulic of sewers to make an allowance for infiltration.

The infiltration allowance is considered as 5% of flow.

vi) For the purpose of design the total wastewater generated for the design period i.e. for the

year 2041 in the zones where sewerage scheme is proposed is worked out based on

projected population and population density.

2.2.3. Wastewater Quality

i. The quality of wastewater returned to a sewer system depends on the quality of water supplied,

nature of water use, intensity and quantity of use, condition and extent of the wastewater system.

Since municipal wastewater contains both domestic and industrial wastes, the type and extent of

industrial area are also important. The enforcing agencies require the industries to treat their own

wastes to prescribed standards before discharge into sewers.

ii. Important characteristics such as temperature, suspended solids, biochemical oxygen demand,

sulphates etc are subject to seasonal and geographic variations. It can be seen that BOD [5 days]

concentration is very low and sulphate concentration is very high. High sulphates may be from

the original water supplies of the project area or industrial waste of from infiltration of brackish

ground waters. Typical raw sewage characteristics are as follow

iii. BODs = 25gms /capita / day

iv. S.S = 10gms /capita /day

v. COD = 1.6 to 1.9 into BODs

vi. Sulphide Generation, Corrosion and Corrosion Projection in Sanitary Sewers.

vii. A sanitary sewer is considered a potentially corrosive environment where Hydrogen Sulfide [H2S]

may be generated. H2S may cause various problems including odour, hazard to maintenance

crews and corrosion of some sanitary sewer pipe materials.

viii. Factors Influencing Sulphide Generation.

ix. The factors that influence sulphide generation in sewers include

a) Temperature of sewage

b) Strength of sewage

c) Velocity of flow,

d) Time of travel of sewage upto the point in question

e) Sulphate concentration in sewage

f) Ventilation of the sewer.



2.2.4. COLLECTION SYSTEM DESIGN CRITERIA

I. Introduction This system design is essentially based on design criteria based on present practice as spelt in the

manual on sewerage and sewage treatment published by CPHEEO, manuals and codes of other

nations, studies reported in literature and papers in journals etc. Where possible, changes are

suggested to evolve a more efficient design to effect economy in cost, within the constraints of an

acceptable performance level for individual components and without comprising engineering.

II. Design Year

The design year considered for the wastewater system is 2041. i.e. 30 years from the year 2008 and

3 years construction period.

III. Design Flow

The design flow is based on the wastewater expected to be generated in the year 2041 and would

include wastes from domestic use in residential, commercial and institutional areas and non domestic

use in industrial areas and infiltration.

Avg. dry weather flow [Q avg.] per manhole = {Population [ P ] X Sewerage Flow (Water Supply

[lpcd] X Expected Sewer 80 % as per CPHEEO manual page No. 39 point 3.2.4)} + Infiltration 5% of

flow.

= P x (150 lpcd X 0.80) + Infiltration 5% of flow.

IV. Per Capita Wastewater Flow

For the purpose of design the wastewater generated is estimated considering population and water

supply rate as 150 lpcd and it is assumed as 80% of the water supply to reach the sewers.

V. Rate of Infiltration

The infiltration allowance is considered as 5% of sanitary flow.

VI. Peak Factor

The peak factors considered for design of sewers range between 2 to 3 as per the recommendations

of CPHEEO manual based on contributory population. The peak factors are applied to the projected

population for the design year considering an average per capita wastewater flow based on

allocation.

As pipes deteriorate with age, a roughness coefficient is assumed for the design period assuming fair

condition in sewers. The roughness coefficient 'n' is assumed to be the same for all diameters and is

taken as 0.011 for R.C.C. as per CPHEEO Manual.



VII. Design of Collection System

Manning's formula is adopted for the design of sewers.

vf = R2/3 S1/2 given that Where

vf = Velocity when pipe flows full in mps.

A = Cross sectional area of pipe in sqm.

n = Manning's roughness coefficient when pipe flows full

R = Hydraulic radius.

S = Slope of energy gradient

VIII. Design Aspects

Sewers are designed to carry estimated peak flows generated in the year 2041 and to run

partially full at all flows. The pipes are designed to flow at depths where the maximum

permissible depth of flow in sewers for established velocity criteria are tabulated. From

considerations of ventilation in wastewater flow, sewers have been designed to flow partially full

at ultimate peak flow. To ensure that deposition of suspended solids does not take place,

minimum self-cleansing velocities to be attained once in a day need to be considered in the

design of sewers. The minimum partial velocities during peak flow suggested are 0.8 m/s and the

maximum velocity 3.0 m/s. This velocity is adequate to keep a wide range of particles

encountered in the wastewater system in suspension.

IX. Pipe Material for Collection System.

Reinforced Cement Concrete (R.C.C.) pipes, with rubber gasket at joints is proposed for

sewers as those are better in performance and workmanship than GSW, glass fiber

reinforced plastic (GRP) and high density polyethylene (H.D.P.E.) pipes. Prohibitive costs

preclude the use of the GRP and HDPE and therefore are not considered. R.C.C. pipes are

available in three classes i.e. NP2, NP3 and NP4. In keeping with discussions with MBMC

officials R.C.C. NP3 and NP4 class pipes have been preferred over NP2 pipes in view of

heavy traffic conditions.

1 . n



X Other Aspects

a) Minimum size of sewers The minimum size of sewers adopted is 150 mm diameter for analysis and identification of

proposed sewers under this study, along the major rods. The size is adopted to minimize possibility of

clogging.

b) Minimum depth of cover The minimum depth of cover on sewers is taken as 0.8 meters.

c) Recommended Maximum Depth of Flow in Pipes All sewer have been designed to flow 0.8 full at ultimate peak flow.

d) Type of bedding Type of bedding for various pipes (first class bedding, concrete cradle etc.) depends on the depth

at which the sewer is laid, type of pipes used, load due to backfill and super imposed load. Accordingly,

suitable bedding A Class, B Class and C Class for pipes is provided.

Class A bedding may be either concrete cradle or concrete arch. Class B is a bedding having a shaped

bottom or compacted granular bedding with a carefully compacted backfill. Class C is an ordinary bedding

having a shaped bottom or compacted granular bedding but with a lightly compacted backfill. Class D is

one with flat bottom trench with no care being taken to secure compaction of backfill at the sides and

immediately over the pipe and hence is not recommended.

The pipe bedding material must remain firm and not permit displacement of pipes. The material has to be

uniformly graded or well graded. Uniformly graded materials include pea gravel on one size material with a

low percentage of over and under sized particles. Well graded material containing several size of particles

in stated proportion, ranging from a maximum to a minimum size coarse sand pea gravel, crushed gravel,

crushed screening, can be used for pipe bedding. Fine materials or screening are not satisfactory for

stabilizing trenches bottom and are difficult to compact in above manner to provide proper pipe bedding.

Well Graded material is most effective for stabilizing trench bottom and has a lesser tendency to flow than

uniformly graded materials. However, uniformly graded material is easier to place and compact above

sewer pipes

e) Backfilling

Backfilling of the sewer trench is a very important consideration in sewer construction .The

method of backfilling to be used varies with the width of the trenches, the character of the material

excavated, the method of excavation and the degree of compaction required. In developed streets, a high

degree compaction is required to minimize the lode while in less important streets; a moderate

specification for fill may be justified. In open country it may be sufficient to mound the trenches and after

natural settlement return to regrade the areas.



The refilling shall proceed around and above the pipes. Soft material screened free from stones

or hard substances shall first be used an hand pressed under and around the pipes to half tire height.

Similar soft material shall then be put up to a height of 30 m above the top of the pipe and this will be

moistened with water and well rammed. The remainder of the trench can be filled with hard material, in

stages, each not exceeding 60 cm. At each stage the filling shall be well rammed, consolidated and

completely saturated with the water and then only further filling shall be continued. Geosynthetic polymer

solutions shall be mixed proportionately which works as a soil stabilizer and reinforcing agents also

helping to reduce the void between soil particles and thereby helping in gaining proctor density of 95% by

compaction. Before and during the backfilling of the trench, precaution shall be taken against the

floatation of the pipe line due the entry of large quantities of water into the trench causing an uplift of

empty or the partly filed pipe line. upon completion of the backfill, the surface shall be restored fully to the

level that existed prior to the construction the sewer.

Typical Road restoration section:

40 mm Asphalt concrete

50 mm Bituminous Macadam

50/75 mm BBM

Size metal layer

Over Size Metal layer

Total 750

mm

Sand/Gravel bedding( Trench Fill)

Appurtenances

a) Manholes

a) Manholes will be provided at all junctions, change of sewer size, gradient and

alignment.

b) The manhole frame and cover shall be Precast Concrete conforming to the IS

12542 (Part I) 1988 and Part II 1991, the clear opening of manholes shall be(1.) 560 mm as

per IS 4111. (2) The manholes with conical wall is proffered over vertical wall. The bottom

slab of manhole shall be of reinforced concrete, wherever required, depending on site

conditions.

c) Since water table is high in the project area seventy percent manholes are proposed to be

constructed in reinforced cement concrete of grade M20 with adequate waterproofing to

minimize infiltration.

b.) Supporting Strength of Rigid Conduit The ability of a conduit to resist safely the earth load depends on its inherent strength as well as

the distribution of vertical load, bedding reaction and on the lateral pressure acting against the



sides of the conduit. The inherent strength of a rigid conduit is usually expressed in terms of the

three edge bearing test results, the condition of which are however different from the field load

condition, For strength calculation of NP class precast RCC pipes, IS:458-1988 is used.

c.) Field Supporting Strength

The field supporting of a rigid conduit is the maximum load per unit length, which the pipe will

support while retaining complete serviceability when installed under specified condition of

bedding and backfilling. The field supporting strength however does not include any factor of

safety. The ratio of the strength of a pipe under any stated condition of loading and bedding to its

strength measured by the three edge-bearing test is called the load factor. The load factor does

not contain a factor of safety. Load factors have been determined experimentally and analytically

for the commonly used construction condition for both trench and embankment conduits.

The basic design relationships between the different design elements are:

Safe supporting strength,

W = Field supporting strength/Factor of safety

1. = (Load factor X three edge bearing strength)/Factor of safety

A factor of safety of at least 1.5 should be applied to the specified minimum three edge bearing

strength to determine the working strength for all the rigid conduits, The class of bedding

considered is B type, whose load factor as per the CPHEEO Manual is 1.9

d.) Type of Bedding

The type of bedding provided for pipes will be selected from granular bedding to concrete (M20)

cradle bedding or concrete encasement (M20) and the choice will depend on the depth at which the

sewer is laid, three edge bearing strength of pipes used, load due to backfill and superimposed

vehicular traffic loads, Technical suitability of such bedding, as per the guidelines of CPHEEO, is

studied and adopted as found acceptable.

e.) Force Main Sewage may have to be carried to higher elevations through force main, The size of the main should

be determined by taking into account the initial cost of pipeline and cost of operation of pumping for

different sizes of pressure main has been calculated for velocity of 1.1 to 1.5 m/sec for designing

peak flows with a maximum velocity up to 2.0 m/sec.

Losses in values. Fittings, etc. Are dependent upon the velocity head v2/2g Loss in bends, elbows

depend upon the ratio of absolute friction factor to pipe diameter, besides the velocity head. Loss due

to sudden enlargement depends upon the ratio of diameters.

Each individual case needs to be studied form various aspects such as operation of pumps, the

specified limits, availability of land required for duplicating the main in future, etc.



DI pipes conforming to IS: 1536 -1989 and DI pipes as per IS: 8329 -1194 corrosion resistant with an

expected life of about 100 Years. CI pipes will be jointed either by rubber gaskets suitable titan joints

or by lead joint.

1. Construction methods

(a) Trench The width of trench at and below the top of sewer should be the minimum necessary for its proper

installation with the due consideration to its bedding. The width of sewer at bottom will D+0.8 where

0.8m is considered as working space. The width of trench increases 0.6 m foe every 1.5 m.

(b) Shoring

Open timbering in trenches of depth more than 1.5m for shoring and strutting is proposed.

Continuous sheeting shall be provided outside the wall plates to maintain the stability of trench walls.

(c) Sewer Connections Concrete Spigot and socket pipes are laid with rubber joints facing up the gradient on desired

bedding special bedding hunching or encasing may be provided where conditions so demand (as

discussed in 6.5)All the pipes shall be laid perfectly true both to line and gradient (Is:4127-1983)

(d) Hydraulic testing:

Water test Each section sewer shall be tested for water tightness preferably between manholes. To prevent

change in alignment and disturbance after the pipes have been laid. It is desirable to backfill the pipes

up to the top keeping at least 90 cm length of the pipe open at the pipe open at the joints. However

this may not be feasible in the case of pipes of shorter length, such as stoneware and RCC pipes.

With concrete encasement or concrete cradle, partial covering of the pipe is not necessary.

The leakage or quantity of water to be supplied to maintain the test pressure during the period of 10

minutes shall not exceed 0.2 liters/mm dia of pipes per kilometers length per day.

For non pressure pipes it is better to observe the leakage shall be carried out at a time when the

ground water.

(e) Construction of manholes ;- Construction of manholes shall be constructed simultaneously with sewers. The manholes shall be of

R.C.C or brick masonry. The entire height of the manhole shall be tested for water tightness by

closing both the incoming and outgoing ends of the sewer and filling the manhole with the water. A

drop of in water level not more than 50 mm per hours shall be permitted. In high subsoil water it shall

be ensured that there is no leakage of ground water in to manhole by observing the manhole for 24

hours after emptying it.



2.2.5. DESIGN BASIS OF SEWAGE PUMPING STATION

I. Design Approach

The design and selection of pumps for a sewage pumping station involves a multi-disciplinary team of

experts who have to work out every detail of the fluid, mechanical and electrical aspects in order to obtain

a satisfactory design and operation of the pumping station. Different types of pumps have their own

purposes and characteristics. There are a series of decisions that have to be taken while selecting and

designing the pumps. The various factors considered while designing the pumping station are:

Determine location and purpose Determine the required discharge (average and peak flows) Determine the required lift or pressure increase, including the variations therein, as well as the

transport distance Determine the type of liquid Determine in and outflow condition, etc.

II. Location

Pumping stations are normally located at the lowest point of the area as they are intended to serve.

They will frequently, therefore be found alongside the watercourses that drain the area as they are

the natural lowest level.

Proper location of the pumping station requires a comprehensive study of the area to be served

ensure that the entire area can be adequately drained. Special considerations have to be given

undeveloped or developing areas to the probable future growth as the location of the pumping station

will, in many cases, be determined by the future overall development of the area. The site should be

aesthetically satisfactory. The pumping station shall be located and constructed in such a manner that

it will not be flooded at any time. The station should be easily accessible under all weather conditions.

III. Determination of Flows

Having decided on the location of the pumping station, its purpose and the contributory area., the

next stage is to calculate average and peak flows for the present day and a point in the future at

"design horizon' Whilst in the structural sense, concrete structures are designed for 30-50 years, are

normally sized to deal with the peak flow at a 30 year horizon.

IV. Layout

The layout of pumping stations will primarily depend upon the local conditions. In general, it CI said

that the layout of a pumping station is logic fit of all functions of the station with sufficient room to

move between machinery for erection and maintenance purposes, but without unnecessary empty

spaces either in horizontal plane or in vertical plane. In principle, flow lines shall be as short as

possible and no unnecessary bends shall be present in the piping.



Spaces are required for the following units. Inlet chamber Screen chamber Main collection sump Valve chamber / dry well Transformer station Electrical panel room DG set room Operations office

Two type of pump house layout is considered based on type of pumps: Dry well and wet well for horizontal centrifugal pumps Wet well and value chamber for submersible pumps

2.2.6. Design Basis for Sewerage Treatment Plant

As settlements grew bigger, local disposal of night soil in the primitive days gave way to water-carriage

sewage conveyance systems with a sewage treatment facility at a remote end of the town. Costs of

wastewater collection and treatment spiraled up thereby pushing them beyond the means of small towns

in developing countries. Discharge of untreated or partially treated sewage into water bodies became an

order of the day.

A point to ponder here is whether long term economy could be achieved with extreme spatial separation

between points of generation, treatment and utilization. Common sense dictates that smaller closed

systems may be far more economical than larger open systems. It is quite evident that overall costs of

sewage conveyance, treatment and reuse are directly proportional to the total distance over which raw

and treated sewage is carried. The figure below illustrates the potential savings in sewerage system costs

by de-centralization. On one extreme of the spectrum therefore is the traditional centralized

configuration while the other extreme is the treatment and reuse and/or recycle of sewage in individual or

clusters of settlements. There is therefore a continuum of options between these extremes.

The question here arises that if de-centralized collection, treatment and reuse/ recycle of sewage is economical, why has

the concept not gained wide acceptance? There could be several reasons for this:

a. The visual, odor and potential contamination problems traditionally associated with sewage treatment systems

b. Space constraints

c. Lack of local reuse/ recycle avenues for treated sewage

d. Costlier operation due to multiplicity of treatment systems

For the realization of economic benefits of de-centralized treatment options the aforementioned limitations merit serious

consideration.



I. Compact And Aesthetically Designed Sewage Treatment Systems --- A Distinct Possibility

The principle of process intensification makes the development of compact and aesthetically designed sewage treatment

systems a distinct possibility. Use of lamella or tube settlers in place of conventional clarifiers is the simplest example of

process intensification. In biological treatment systems intensification is primarily achieved by an order of magnitude

increase in microbial cell population per unit volume of reactor thereby permitting shorter residence times. This in turn

enables significant reduction in plant footprints.

Compact process technologies enable package, modular design with expansion slots to be filled up for phased expansion.

Compact systems are also amenable to a fully enclosed design with exhaust ducts and de-odorization systems if needed.

This approach enables full exploitation of economies of scale benefits by designing constituents process modules for

different time horizons. With this approach, capacity expansion need not be construed as a replication of an identical

parallel stream but rather as the addition of a module or

TECHNOLOGY OPTIONS

SYSTEMS REQUIRING DIFFUSED AERATION

AERATION BY THIN FILM RENEWAL

MBRSAFFMBBR SBREAASCAS RMBR

MEMBRANE BIOREACTOR

STATIONARY AEROBIC FIXED FILMREACTOR

MOVING BEDBIO REACTOR

CONVENTIONALACTIVATED SLUDGE PROCESS

SEQUENCINGBATCH REACTOR ROTATING

MEDIABIO REACTOR

TBBR

TRICKLE BEDBIO REACTOR

EXTENDEDAERATIONACTIVATED SLUDGE

HYBRID GROWTH SYSTEMS SUSPENDED GROWTH SYSTEMS ATTACHED GROWTH SYSTEMS

2.3. Environmental Assessment of Sewerage System

2.3.1. Air quality:

The existing air quality of the study area was monitored for 24 hrs at Twelve locations, as per zone

divided for sewerage system. The air quality was monitored with respect to CO, SO, NOx , SPM , RPM

and Pb. The existing air quality was compared to the national ambient air quality standards suggested by

CPCB. From the monitored values for the air quality it is observed that the NOx, SO2, Pb, RSPM and CO

values are within the prescribed limits. The level of suspended particulate matter (SPM) is marginally



above the prescribed limits in major traffic roads & near railway station. Though the existing lead (Pb)

levels are below the limits, the difference is marginal.

2.3.2. Noise quality:

The ambient noise levels in the study area were monitored continuously for 24 hrs at an interval of one

hour at eleven locations. It was observed that the noise levels exceed the prescribed limits at major

roads & near stations. For the commercial land use near all these area, the day noise levels are only 5

dB(A) above the limits, while the night values exceed by 7 dB(A). For the residential land uses, the day

noise levels exceed by 10 dB(A) and the night levels exceed by 5 dB(A).

2.3.3. Vegetation:

Most of the roads in the study area are lined with mature, shady trees, though the feeder roads to the

stations were generally devoid of trees, especially at the station end. Agriculture is an important activity

in rural areas especially those in the fringes of expanse Agricultural land is on the decline as

development pressures affect it. Low lying agricultural areas along the river, saltpans have also been

converted to wetlands due to sea water entering the farming area through breeches.

2.3.4. Soil investigation & Water level

Soli investigation report has attach in Annexure 1.

2.3.5. Meteorological profile

The study area has warm humid weather and receives rainfall for more than four months a year. The

average wind speed ranges from 5 mph to 9 mph. The predominant wind direction in Navi Mumbai is

south/south-west in monsoon and north/north-east in winter. The meteorological readings for the closest

station at Santa Cruz are as below:

Fig 7 : Mean Monthly Climatic Parameters (Station: Santa Cruz (Mumbai))

Latitude: 19 07 Longitude: 72 51 Height above MSL: 15 Meters



Source: Regional Meteorological Centre, Mumbai

Since the winter temperature is rarely below 15- 20 C problems associated with temperature inversion are not a major issue in the city. However, the humidity and the pollution combined together results in

occasional smog. From the monitored values for the air quality it is observed that the NOx, SO2, Pb,

RSPM and CO values are within the prescribed limits. The level of suspended particulate matter (SPM)

is marginally above the prescribed limits in crowded areas. Though the existing lead (Pb) levels are

below the limits, the difference is marginal.

2.4. Environmental Impact Assessment Of The Improvement Schemes And Mitigation Measures

The impact of the schemes during the construction stage as well as operational stage was assessed

with respect to land use, air quality, noise quality, vegetation, pedestrian and vehicular safety and

convenience, visual intrusion and cultural parameters.

2.4.1. Impact of the project on air quality:

The model does not take into account the numerous complex aspects of air quality predictions, it should

be considered as a qualitative estimate and the figures mentioned are only approximate indications.

During the construction stage most of the schemes will result in increased pollution levels in the study

area. However the use of steel portal frame structures for the walkways reduces on site construction

activities to the minimum. The impacts are likely due to activities related to excavation, drilling,

transportation of material to and from the site and increased vehicular emissions caused by traffic

congestion due to construction activities. However, this is a short-term impact and can be kept under

control by appropriate mitigation measures.

2.4.2. Impact of the project on noise level:

The use of heavy machinery will increase the noise level in the study area during the construction

stage. There will be a marginal improvement in the study areas noise levels due to the reduced

acceleration and deceleration made possible by the improved traffic flow, particularly along feeder roads

to station & Highway.



Impact on aspects like privacy, safety, light and ventilation, visual obstruction etc of the residential and

commercial units:

During construction stage of sewerage network, the commercial areas along the relatively narrow road

are likely to be marginally affected in terms of reduced accessibility.

2.4.3. Air Pollution Mitigation:

A construction management plan should be prepared for each of the schemes by the Project Management

Consultant in consultation with the Contractor, incorporating the mitigation measures suggested in the

Environmental Management Plan. Fugitive dust emissions should be contained within the site by barriers. Dust

covers shall be made compulsory for transporting materials. Drilling operations should be coupled with dust

collectors. All construction debris should be disposed off at the Dumping Ground. Heavy vehicles should not be

allowed in the site during peak hours. A traffic management plan should be made for the construction period

indicating traffic diversions, parking area and parking time changes, vehicular restrictions and time- related

restriction.

2.4.4. Noise Pollution Mitigation:

Construction activities should not be allowed between 10 pm-7 am. As far as possible, maximum noise

producing work should be avoided during peak hours. Localized and stationary noise sources like generators

should be encased within temporary noise barriers. Noise generating equipment should have quality mufflers

installed. All equipment should be lubricated and maintained in a good condition. To avoid use of mixing plants,

ready mix concrete should be used. Proper signage should be provided near the schools ,discouraging the use

of horns. Heavy vehicles should not be allowed to use on smaller road while laying pipes.

2.4.5. Mitigation for loss of vegetation:

To compensate for the loss of trees, twice the number of trees removed should be replanted. Trees that are

viable to be transplanted should be identified in consultation with the tree authority. Planters along Traffic Road

should be planted with shrubs like Lantana and Wedelia Trilocata, which has good dust absorbing properties.

The above mitigative measures are incorporated in the Environmental Management Plan (EMP). The EMP

covers all the mitigative measures suggested for the project, responsible agencies and the monitoring and

reporting schedules. The Project Implementing Agency (NMMC) will get the EMP implemented through the

Project Management Consultant (PMC) by incorporating the EMP requirements in the contractual agreement.

An Monitoring Panel constituted by NMMC with the objective to ensure that the policies related to social and

environmental issues are followed. The panel will meet periodically to review the periodical reports,

environmental compliance report, etc. submitted by PIAs and PMCs/Contractors.



2.5. Environmental Management Plan

The negative impacts associated with many of the proposed schemes can be mitigated by an appropriate

environmental management plan. The mitigation measures during the construction as well as operational

stages, recommendations regarding construction and post construction monitoring, their frequency, and the

responsible agencies have also been covered in the Environmental Management Plan. The Impact assessment

study indicates that the major impacts of the project are on environmental parameters related to air quality,

noise quality, and vegetation and visual/aesthetic quality. Certain land use specific impacts like privacy to

residential areas, light and ventilation; safety etc has also been identified as also impacts related to pedestrian

and vehicular convenience and safe. Mitigation measures for each of these impacts were covered in detail in

point 2.5 .

2.5.1. Environmental Management Measures

Generic environmental management measures suggested for the project are summarized in Table 13 while

project specific measures are included in Table 14. The monitoring and evaluation of the Environmental

Management Plan is critical for ascertaining the effectiveness of mitigating measures in controlling the adverse

impacts. The environmental monitoring schedule for the construction and operation stage of the project is

provided in Table 15.



Table 2.1. Summary of Environmental Management Plan- Generic Measures

S. No

Environmental Parameter- Air Quality

Environmental Management Measures Period Responsible agency

Remarks

1 Signage informing commuters about traffic diversion Construction Stage

Contractor, NMMC

Cross Reference: MoRTH:112

2 Preparation of Construction Management Plan incorporating EMP measures

Pre Construction stage

Project Management Consultant, Contractor

3 Disposal of construction debris at Dumping Yard Construction Stage

Contractor

4 Schedule the activities in such a way that debris related to each stage of the work( site clearance, excavation etc) is removed before the next stage is started rather than pile up the debris in the site till all the work is completed

Construction Stage

Contractor Cross Reference: MoRTH:111.9

5 Maintaining Construction Vehicles in good condition, conforming to the prescribed emission norms

Construction Stage

Contractor Cross Reference: MoRTH:106



S. No

Environmental Parameter- Air Quality

Environmental Management Measures Period Responsible agency

Remarks

6 Dust covers made of tarpaulin on material transporting trucks. Construction Stage

Contractor Cross Reference: MoRTH:111.8, 111.9

Nmmc Sewerage Dpr

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