gswsp dprphaseiii.pdf

8/15/2019 GSWSP DPRphaseIII.pdf

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U m i e w R i v e r , s o u r c e o f G r e a t e r S h i l l o n g W a t e r S u p p l y P r o j e c t


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GoM : Phed DPR of GSWSP (Phase-III) i

CONTENTS

Sl.

No.Descriptions

Page

No.

1 Sector Background context & Broad project rationale. 1

1.1 Existing status of the physical infrastructure. 1

1.2 Baseline information in terms of user coverage & access. 6

1.3 List of various projects proposed for the sector in the city development plan(CDP) and confirmation/explanation of how this project is aligned with

stated CDP priorities.8

1.4 List of other capital expenditure projects supported by other schemes for the

sector (sanctioned projects that have yet to commence as well as ongoing

projects).10

1.5 Existing tariff and cost recovery methods and extent of cost recovery. 11

1.6 Existing areas of private sector/community participation in the sector for

design, construction project management, and/or O&M services (including

billing & collection).

15

1.7 Any other qualitative information 15

2 Project definition, concept and scope. 17

2.1 Land. 17

2.2 Physical infrastructure components. 18

2.2.6 Design consideration 24

2.2.8 Detailed design engineering 39

2.2.8.1 Design on economic size of rising transmission main for intake pumping

station.

39

2.2.8.2 Design of RCC Sump for intermediate pumping station. 43

2.2.8.3 Design on economic size of transmission main for intermediate pumping

station.

43

2.2.8.4 Design calculation of pumping plant for intake pumping station. 47

2.2.8.5 Design calculation for pumping plant of intermediate pumping station. 49

2.2.8.6 Design of 8 Mld. water treatment plant 51

2.2.8.7 Process design of the treatment plant units. 51

2.2.8.8 Design of RCC sump for clear water pumping station 62

2.2.8.9 Design of clear water rising main 63

2.2.8.10 Design calculation for a pumping plant of clear water rising main for 6th

Mile to Laitkor 672.2.8.11 Design of clear water gravity transmission main 69

2.2.8.12 Design and computation for capacity of service reservoir 71

2.2.8.13 Design of storage reservoir 72

Map showing town under SUA and area covered by GSWSP (Phase I & II) 73

Map showing zoning of project area 74

2.2.8.14 Design of distribution system 75

Map, length and route of pipe lines

Map showing distribution network Zone-I 76

Length of pipe line Zone-I 77

Proposed pipeline route Zone-I 82


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GoM : Phed DPR of GSWSP (Phase-III) ii

Sl.

No.Descriptions

Page

No.

Map showing distribution network Zone-II 92

Length of pipe line Zone-II 93

Proposed pipeline route Zone-II 100

Map showing distribution network Zone-III 113

Length of pipe line Zone-III 114

Proposed pipeline route Zone-III 122

Map showing distribution network Zone-IV 137

Length of pipe line Zone-IV 138

Proposed pipeline route Zone-IV 143

Map showing distribution network Zone-V 152

Length of pipe line Zone-V 152

Proposed pipeline route Zone-V 165

Map showing distribution network Zone-VI 186

Length of pipe line Zone-VI 187 Proposed pipeline route Zone-VI 192

Map showing distribution network Zone-VII 202

Length of pipe line Zone-VII 203

Proposed pipeline route Zone-VII 207

Map showing distribution network Zone-VIII 215

Length of pipe line Zone-VIII 216

Proposed pipeline route Zone-VIII 236

Map showing distribution network Zone-IX 267

Length of pipe line Zone-IX 268

Proposed pipeline route Zone-IX 283

Map showing distribution network Zone-X 309

Length of pipe line Zone-X 310

Proposed pipeline route Zone-X 324

Map showing distribution network Zone-XI 349

Length of pipe line Zone-XI 350

Proposed pipeline route Zone-XI 354

Map showing distribution network Zone-XII 362

Length of pipe line Zone-XII 363

Proposed pipeline route Zone-XII 372

Drawings

Long section of Raw water rising main 389

Raw water stage I pumping system, pump house layout plan & elevation 390

Raw water stage I pumping system, Intake structure, pump house, inlet

and typical pump installations.

391

Raw water stage II pumping system, layout plan of pump house, RCC

sump and pumping installations

392

Raw water stage II pumping system, elevation and pumping installation. 393

Hydraulic flow diagram of water treatment plant 394


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GoM : Phed DPR of GSWSP (Phase-III) iii

Sl.

No.Descriptions

Page

No.

Water treatment plant of 8 Mgd Layout plan 395

Water treatment plant of 8 Mgd Layout plan of Filter house 396

Long section of clear water gravity main from WTP, Mawphlang to 6th

Mile, Upper Shillong.

397

Clear water pump house and RCC sump : Layout plan 398

Clear water pump house and RCC sump : Elevation 399

Schematic flow diagram of gravity/pumping transmission mains 400

2.3 Environmental compliance/protection measures/improvement measures 401

2.4 Rehabilitation and resettlement 403

2.5 Specialised procured services for design, independent supervision and

quality assurance

404

2.6 Other information 404

3 Project cost 405

3.12 Cost estimation 4063.12.2 Physical infrastructure detail estimate 406

3.12.4 Any other detail estimate 441

4 Project Institution framework for construction. 444

4.1 Roles of different institutions involved in the construction phase of the

project.

444

4.2 Manner of undertaking construction works. 445

4.3 Involvement of the construction entity in the subsequent O&M activities. 445

4.4 Areas of involvement of the private sector in the construction phase. 445

4.5 Construction “packages” for works construction. 446

5. Project Financial Structuring. 447

5.1 Overall financial structuring of the project 447

5.2 Review of option of institutional depth and/or private sector participation 447

6 Project phasing 448

6.1 Schedule for tendering/selection for procurement of services 448

6.2 Schedule for bring instate level and ULB level contribution to the project 448

6.3 Schedule for obtaining all clearances 449

6.4 Schedule for shifting utilities 449

6.5 Project infrastructure component-wise implementation 449

7 Project O & M 451

7.1 Institution framework (organisation and operation) strategy 451

7.2 Tariff and user cost recovery. 453

8. Project financial viability & sustainability 453

8.1 Overall project perspective 453

9. Project benefits assessment 454

9.1 A list of benefits from societal perspective 454

9.2 A list of negative externalities 454


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GoM : Phed DPR of GSWSP (Phase-III) iv

Sl.

No.Descriptions

Page

No.

Annexures

2. Project implementation planning 455

3. Schedule for financial contribution and sources 456

4 (a) Project cash flow for JNNURM 457

4 (c) Details of Operation & Maintenance Charges 458

4 (d) Statement showing Operation & Maintenance cost, status of supply,

water tariff and expected revenue generation.

459

4 (e) Water supply tariff 460

Appendixes

1 Constituents of Shillong Urban Agglomeration 461

2 Population forecasting 462

3 Zone wise breakup of population of areas under Shillong UrbanAgglomeration.

467

4 Zone wise breakup of population of areas under Shillong Urban

Agglomeration

469

5 Zone wise breakup of water requirement under Shillong Urban

Agglomeration

471

6 Statement on pipe requirement for distribution network 474

7 Statement on pipe requirement for clear water gravity main 475

8 Statement on pipe requirement for the whole project 476

9 Source reliability study and report on Umiew river 478

10 Analysis report on water source 495


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GoM:Phed DPR of GSWSP (Phase III) 1

1. Sector Background context & Broad project rationale.

1.1 Existing status of the physical infrastructure.

1.1.1 Shillong, the capital of Meghalaya occupies the northern slopes and foothills of Shillong

peak at an average altitude of 1496 metres above mean sea level. The city derived its name

from a deity named Shillong, whose dwelling place is known as Shillong Peak. He is

believed to have established the art of democratic governance and rule of justice in the

formation of the princely State of Shillong (Hima Shillong), which was subsequently

bifurcated into Mylliem State and Khyrim State in 1830. During the British Rule, Shillong

consisted of only a few scattered clusters of hamlets. The British Administration shifted the

headquarters of United Khasi and Jaintia Hills District from Cherrapunjee to Shillong. In

1874 the State of Assam was created out of Bengal and the city became its provincial

capital. In 1972, when the State of Meghalaya became a separate State, the city became its

capital.

1.1.2 The city is situated in the East Khasi Hills District and is also the district headquarter. It is

well connected by a network of roads within the State and with all important cities in the

neighboring States. It is connected with the rest of the country through Guwahati by road,

rail and by air. Helicopter service is also available between Shillong-Guwahati-Shillong and

Shillong-Tura. There is a minor airport at Umroi, 35 kms from Shillong. All the State

Government offices and important Central Government offices are located in Shillong.

Some of the other important institutions which are located in Shillong are the headquarter of

the North Eastern Council, North- Eastern Hill University, Headquarter of Eastern Air

Command; 101 Communication Zone of the Army and other Para military organizations.The schools, colleges and other educational institutions attract students from all over the

North Eastern Region. The Shillong State Central Library and Museum offers scope for

study and research of the ethnic cultures in the region. It is one of the few hill stations with

motorable roads all round the city. Shillong has its own charm, different from other hill

stations, and presents a natural scenic beauty with waterfalls, brooks, pine grooves and

gardens. The place, the people, the flora and fauna and the climate all combine make

Shillong an ideal resort throughout the year.

1.1.3. The mission statement as per Shillong City Development Plan envisages planned

development of Greater Shillong Planning Area (GSPA) covering an area of 174 sq.km

including an area of 10.73sq.km falling under Shillong Municipal jurisdiction. The Greater

Shillong Planning Area comprises of 7 urban centres and 32 villages surrounding the Urban

Centres. The present structure of GSPA, its problems and magnitude of the problems to be

faced by it in future have been indicated in the Shillong CDP. The city of Shillong despite

its physical threshold and constrains is likely to expand and grow. Population of the

Shillong Urban Centres (SUA) has increased from 1.56 lakhs in 1971 to 2.68 lakhs in 2001

and expected to increase to 3.16 lakhs by 2011. The existing problems which required

immediate attention and large magnitude of investment would assume challenging

propositions in case not addressed and taken care of.


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1.1.4 The existing main supply sources to the project area (SUA) is the Greater Shillong Water

Supply Project (GSWSP) designed to cover the areas under Shillong Urban Agglomeration

(SUA) in existence during the period (1978) viz. Shillong Municipal Board (SMB),

Shillong Cantonment Board (SCB), Mawlai and Nongthymmai. Phase I of the project

whose implementation commenced in the year 1978-79 was completed and commissioned

in the year 1986. The source of supply is the river Umiew at Mawphlang about 30km awayfrom Shillong. The project (phase-I) envisages lifting of water from the run-off the river in

2 stages against a total head of 312m and convey via 2.42km parallel M.S. rising main of

600mm dia. to the water treatment plant at Mawphlang. The treatment plant constructed

under Phase I of the project has a capacity of 34.05Mld. Treatment comprises of chemical

coagulation, flocculation, settlement, filtration and post chlorination. A total length of about

30km of pipes varying in size from 750mm dia. to 150mm dia. were laid to convey the

treated water by gravitational flow from Mawphlang towards different parts of Greater

Shillong Area and zonal reservoirs of total storage capacity of about 6.81Ml were

constructed under Phase I of the project.

Intake structure and pumping system constructed under GSWSP (Phase I) in 1985-86 consist of

2 Nos. R.C.C. Well of 8.20m clear diameter of about 36 m in height, a Pump House on top of the well andan approach bridge of span about 40m.

Under Phase I, 6 Nos. Vertical Turbine, Kirloskar Make BHR 35-30° 4 Stage Self Water Lubricated

Pumps coupled to 6 Nos. KEC Make 300Kw squirrel cage induction motor were installed. Each Pump has asuspended column assembly length of 38m. The pumps capable of lifting 51.30 Mld of water against aHead of 122m and conveying it to the RCC Sump at the Intermediate pumping station via a 0.32 Km.

parallel main of 0.600m diameter were commissioned in the year 1986. The pumps were designed todevelop the required discharge pressure at a speed of 1482 Rpm.


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The Intermediate structure & pumping system constructed under Phase I consist of RCC Raw WaterSump 2 Nos.x14.00 dia. x 4.30m and a Pump House, 6 Nos. Kirloskar make MN 54-30o 2 Stage Horizontal

Pumps coupled 6 Nos. Kirloskar Electric make motors 530 Kw. The pumps designed to lift 51.30 Mld ofwater against a Head of 190m and conveying it to the Treatment Plant at Mawphlang via a 2.10 Km.

parallel main of 0.600m diameter were installed and commissioned in the year 1986. The pumps whichwere designed to develop the required discharge pressure at a speed of 1482 Rpm, failed, on account ofthe fluctuation in the frequency of power system leading to installation of Booster Pumps Station after

stage II pumping system.

The Treatment Plant constructed under Phase I of the Project and commissioned in the year 1986 has acapacity of 34.05 Mld.


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1.1.5 Phase II of the project comprises construction of mass gravity concrete dam of about 130m

wide and 50m high across the river Umiew at Mawphlang downstream of the existing

intake structure; construction of additional water treatment plant of capacity 17.25Mld

(3.8Mgd), gravity feeder main of a total length of about 25km varying in size from

400mm dia. to 150mm dia. and construction of zonal reservoirs of total storage capacity of

11.40Ml.

Gravity concrete dam of about 130m wide and 50m high across river Umiew downstream of Intake structure was

constructed under Phase II of the GSWSP. The dam which was taken up for construction in 1997 and completedin 2003, provides storage of 9.145MCM. The dam is meant solely for drinking water supply and is owned and

maintained by State PHED.


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1.1.6 Works for distribution of water supply were taken up from 1980 onwards on a piecemeal

basis depending on availability of fund. The pattern of existing water distribution in the

project area is from the zonal tank to the supply tank (GI Tank) and from the supply tank to

consumers trough a lengthy service lines mostly of GI pipes. A bunch of as many as 50

service lines take off from a single supply tank. The service lines are 15mm G.I and are

laid over ground and usually inside the drain.

1.1.7 The pumping machineries for Stage I and Stage II pumping system which were

commissioned in the year 1986 have been replaced through the scheme sanctioned and

funded under State Plan. The pumping machineries have since been commissioned and the

Greater Shillong Water Supply Project (Phase I & II) are now meeting the designed

capacity of 51.30Mld. Though following the commissioning of the new pumping

machineries for both Stage I and Stage II pumping system of Greater Shillong WaterSupply Project, the generation and supply has improved considerably; however, considering

the high percentage of UFW in clear water main and distribution networks including supply

to enroute to villages, the total available supply in the project area from all sources of

supply including Greater Shillong Water Supply Project is about 23.60Mld. The water

availability in the project area is indicated in table 1.1.1.

Table 1.1.1.

Sl.

No. Name of Schemes in SUA

Quantity available

Mld

1. GSWSP

Quantity generated 51.30 Mld

Less treatment losses @ 3% (-) 1.54 Mld

Less supply to enroute to villages (-) 2.60 Mld

Less UFW in clear water main between Mawphlangand other Zonal reservoirs @ 20% (-) 10.26 Mld

Less UFW in the distribution system

mainly in SMB areas @ 35% (-) 17.95 Mld

Available supply from GSWS for urban areas 19.15

2. Available supply from other sources of PHED 1.95

3. Available supply from 7 nos. traditional sources 2.50

Total : 23.60


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1.2 Baseline information in terms of user coverage & access.

1.2.1. The Shillong Urban Agglomeration comprises of 7 urban centres. The total population of

SUA as per 2001 census is 2.68 lakhs. The Project under consideration takes into account

initial period of the Project as 2011, intermediate period as 2026 and ultimate period as2041. Population forecasting was arrived at using the programme developed by CPHEEO.

The print out of the population forecasting is appended as Appendices.

1.2.2 The Population of Shillong Urban Agglomeration as worked out on the basis of 6 decades

of population (1961-2001) is indicated in table 1.2.1.

Table 1.2.1

Year Population Remarks2001 2,67,662

2008 3,01,000

2011 3,16,000 Initial stage

2021 3,74,000

2026 4,05,000 Intermediate stage

2031 4,39,000

Shillong Urban Agglomeration

2041 5,12,000 Ultimate stage

1.2.3 The population of Shillong Urban Agglomeration for 2007, 2011, 2021, 2026, 2031 and

2041 and the corresponding water requirement @135 Lpcd including UFW @15% as

worked out is indicated in the table 1.2.2.

Table 1.2.2 Daily water requirementYear Population

@135LpcdMld

Total with UFW @15%Mld

2008 3,01,000 40.63 46.72

2011 3,16,000 42.66 49.06

2021 3,74,000 50.49 58.06

2026 4,05,000 54.68 62.88

2031 4,39,000 59.27 68.15

2041 5,12,000 69.12 79.49


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1.2.4 The Greater Shillong Water Supply Project (Phase I & II) which was originally formulated

in the year 1978 was designed to cater supply to areas covered under SUA which at the time

comprises of 4 towns viz. SMB comprising areas under Shillong Municipality, SCB

comprising areas of cantonment and 2 census town viz. Mawlai and Nongthymmai. While

both SMB and SCB have civic status of municipality and cantonment board respectively;

Nongthymmai and Mawlai are the non municipality town since 1971 census. At the time(1978), Madanriting, Pynthorumkhrah and Nongmynsong were still regarded as rural areas

and are therefore, outside the coverage of Greater Shillong Water Supply Project

(Phase I & II). Madanriting and Pynthorumkhrah came into existence as census town in

1981 census and Nongmynsong came into existence as census town only in 1991 census.

1.2.5 The Shillong Urban Agglomeration (SUA) comprises of 7 Urban Centres. Water supply

poses a serious problem as major areas of SUA are yet to be covered with organized water

supply system. The areas which are covered by Greater Shillong Water Supply Project have

access to organized water supply system and other areas outside coverage of Greater

Shillong Water Supply project depends on other small water supply schemes like deep bore

wells and other local sources for water supply. High leakage losses occurred in the

consumers lengthy service lines as well as in the supply tank. The losses in the transmission

main and distribution system account to about 55%. Though the existing project generate its

full desired capacity, available supply at consumers’ end is about 78 Lpcd.

N


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1.3 List of various projects proposed for the sector in the city

development plan (CDP) and confirmation/explanation of how this

project is aligned with stated CDP priorities.

1.3.1 UFW in GSWSP accounted for the loss in treatment process @ 3%, losses in clear watermain between treatment plant and different zonal reservoirs @ 20% and loses in distribution

networks as a result of lengthy service lines @ 35% totalling to 58%. Taking into

consideration implementation of various measures for UFW reduction through replacement

of 750mm C.I. water main and improvement in the existing distribution system like

replacement of the existing bunched connection system prevailing in the SMB areas to the

sub main system including reducing the losses in feeder main etc., the UFW can be brought

down from the present level of about 58% to about 15%. The water availability against

daily water requirement of the project area keeping in view the present UFW @ 58% and

future improvement in UFW @15% is indicated in table 1.3.1

Table 1.3.1

Water availabilityYear Daily water requirement

Mld

With 58% UFW

Mld

With 15% UFW

Mld

Shortfall

Mld

2008 46.72 23.60 - 23.12

2011 49.06 - 55.75 - 6.69

2021 58.06 - 55.75 2.31

2026 62.88 - 55.75 7.13

Say 8.00

2031 68.15 - 55.75 12.40

2041 79.49 - 55.75 23.74

Say 24.00

1.3.2 For the project under consideration, the shortfall on water availability for 2026 and 2041 is

8Mld and 24Mld respectively. Taking this into consideration, infrastructure for generation

and distribution of additional quantity of water to meet the shortfall is required to be created

without any loss of time.

1.3.3 River Umiew the source of GSWSP is a dependable river. The Dam constructed across the

river Umiew at Mawphlang provide storage of 9.145 MCM of water for pumping by thesystem. The catchments of river Umiew is about 115sqkm and large area of the catchment

is in close proximately to Cherrapunjee. As a result, the catchment receives a fairly good

amount of rain in comparison to other areas. During the dry weather months of

2007 & 2008, Umiam reservoir (Barapani) water level dropped alarmingly low warranted

State Electricity Board to resort to load shedding to conserve water. The situation was

comparatively different with Umiew river. Records available indicate daily spilling of water

almost 24 hrs. a day despite lifting about 51.30 Mld, indicating that the river has the

potential to cater to the additional and future increase in population of the Shillong Urban

Centres.


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1.3.4 Due to very high pressure, the 750mm C.I. clear water main is reported to be frequently

prone to bursting disrupting the supply to the city for days together. Further, the clear water

main of C.I Pipes with lead joints accounts for very high percentage of UFW. The clear

water main has also outlived its useful life. Frequent disruption of water supply as a result

of frequent bursting of clear water main including control of losses in the main would only be possible through replacement of the main. The proposed project viz. GSWSP (Phase III),

therefore, include provision for replacement of the existing CI 750mm water main with a

new D.I. water main of 1000/900 mm , capable to convey both the existing supply of

GSWS (Phase I & II) and additional supply of GSWSP (Phase III).

1.3.5 The project also takes into consideration improvement of the existing distribution networks

of GSWSP (Phase I & II) and laying of distribution networks to all uncovered areas of

Shillong Urban Centres. Key improvement to the existing distribution system shall be the

replacement of existing bunched connection system to the sub main system so that UFW

can be considerably reduced, contamination of water due to leakages in lengthy service

lines can be checked as roadside drain continue to be the carrier of storm water. This

conversion shall be critical towards.

Supply of adequate quantity of water to consumer’s end with sufficient pressure.

Reduction of high UFW present in the system.

Conversion of un-metered supply to metered supply to ensure control and equitable supply of water to

all areas.

Ensuring water quality at the consumer’s end.

1.3.6 Though considering the high difference in level between pump floor level of the existing

intake structure with the water level of dam, there may be a scope for increasing the height

of the existing Dam to increase live storage, taking up feasibility study for increasing the

height of the dam is not necessary at this stage as sufficient water is available to meet the

additional demand.

1.3.7 All above proposals considered under the project is in line with the various provision of

water supply sector under the City Development Plan (CDP).


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1.4 List of other capital expenditure projects supported by other schemes

for the sector (sanctioned projects that have yet to commence as well as

ongoing projects).

1.4.1 The pumping machineries for Stage I & Stage II pumping station were commissioned in1986 and have since outlived the designed life of 15 years. Prioritizing the urgent needs of

phasing out the existing machineries for the pumping system, new machineries were

installed for Stage I & Stage II pumping station of the GSWS project (phase I & II) under

the scheme sanctioned by State Government with fund made available under State Plan.

While installation of new pumping machineries for Stage I was completed in March 2006,

installation of new pumping machineries for Stage II pumping station was completed in

October 2007. The new pumps installed, discharged water directly into Water Treatment

Plant by-passing the existing Booster Pumps Station. The system GSWS (Phase I & II) is

now lifting about 51.30Mld of water from the dam.

1.4.2 The scheme which comprise replacement of pumping machineries and treatment units of

34.05 Mld. Water Treatment Plant also includes installation of VVVF drives for pumping

system, Automation Control and visualization system for pumping system and water

treatment plant. Excepting replacement of pumping machineries for Stage I and Stage II,

which were completed and successfully commissioned, other components of the scheme are

ongoing.

A battery of 6 units Voltas Ltd. make VH 350-4S/036 self water lubricated vertical turbine pumps coupled toCrompton Greaves 6.6Kv 310Kw squirrel cage induction motor for the Stage I Pumping System installed andcommissioned in 2006. The pumps were designed to lift 51.30Mld of water against a head of 112m. Pumps weredesigned to develop the required discharge pressure at a speed of 1400 Rpm.


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A battery of 6 units KBL make MN 54-30° 2 stage horizontal pumps coupled to SIMO X’ian make 6.6Kv 630Kw

squirrel cage induction motor for Stage II pumping system installed and commissioned in 2007. The pumps weredesigned to lift 51.30Mld of water against a head of 190m. Pumps were designed to develop the requireddischarge pressure at a speed of 1400 Rpm.

1.4.3 The GSWSP (Phase I & II) which was originally designed to cater supply to

Greater Shillong Area was also designed to cater supply to enroute to villages for a total

population of 40,000. Following the necessity to delink the supply to villages from that of

Greater Shillong Area, state government has sanctioned a scheme for supply of water to

the enroute villages separately and from a separate source to delink the GSWSP from

enroute villages. The scheme is ongoing.

1.5 Existing tariff and cost recovery methods and extent of cost recovery.

1.5.1 The Shillong Urban Agglomeration comprises of 7 towns viz. SMB, SCB, Mawlai,

Nongthymmai, Madanriting, Pynthorumkhrah and Nongmynsong. While both SMB and

SCB have civic status of municipality and cantonment board respectively, Mawlai,

Nongthymmai, Madanriting, Pynthorumkhrah and Nongmynsong are non municipality

town. As per present arrangement, areas under the control of SMB, supply is made by State

Phed in bulk and individual services to households and other institutions is being extended

by SMB. Similarly, water is only supplied in bulk to SCB for distribution to consumers by

the Cantonment Board. In areas outside of SMB and SCB, individual services to household

and other institutions is being extended by State Phed.


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1.5.2 The old water tariff formulated by the state Phed is a simple tariff and provides realization

of cost of unmetered supply made to consumers on the basis of fixed charges base on

ferrule size. The tariff also provides for realization of cost of supply to bulk consumers as

per bulk supply rates. The tariff which has been in existence for the last many years is

indicated in table 1.5.1.

Table 1.5.1 Sl.

No.Category of supply Ferrule size Monthly water tax

1. Domestic 15mm

20mm

25mm

Rs. 70.00 per connection per month



2. Commercial Rs. 1.50 per Kl

1.5.3 Though cost recovery is being implemented from consumers provided with individual

service connection to households and other institutions through unmetered supply as well as

metered bulk supply, the extent of cost recovery is not satisfactory as realization of charges

from all bulk consumers could not be effected. Supply is presently made to SMB in bulk

free of cost and without any charges. The cost of supply from other bulk consumers

viz.SCB and other private organizations though regularly recovered, the amount of recovery

is negligible in comparison with the cost of O&M. The number of individual services to

household in other census towns viz. Pynthorumkhrah, Madanriting and Nongmynsong is

also negligibly less as these areas are still outside of the coverage of GSWSP (Phase I & II).

The extent of cost recovery during the last 5 years is indicated in table 1.5.2.

Table 1.5.2

Yearly cost recovery from

Unmetered supply through individual service

to households in the census town area outside

of SMB and SCB

Yearly cost recovery from

Metered supply to bulk consumers

Year

No. of

connection

of 15mm

ferrule size

Applicable

rate per

connection/month

Yearly revenue Applicable

rate

Per kl

SMB SCB &

MES

Other private

agencies

Yearly

revenue

Total yearly

revenue from

both

unmeteredsupply and

bulk supply

2002 2920 Rs. 70.00 Rs.23,23,800 Rs.1.50 Nil Rs.4,54,500 Rs.1,29,000 Rs.5,83,500 Rs.29,07,300






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1.5.4 In Meghalaya, available water in rivers, streams and dams including ground water is

required to be lifted and transported against considerable head and distance to a place of

treatment to make it safe for drinking and thereafter required to be transported again over

long distance to consumers in urban areas. Tremendous amount of Electrical Energy is

required for lifting and transportation of water. In Meghalaya especially, the electricity

tariff applicable to water works is not only the highest in the country but the highest amongall category of supply much higher than rates applicable to commercial and industries. In

addition to the high cost of electricity, cost of salary and wages and other inputs,

considerable amount of chemicals are also required in the treatment process to make the

water safe for drinking. The high cost of electricity charges on public water works has had a

direct bearing on cost of production of water.

1.5.5 The steep increase in O&M of water works vis-à-vis inapplicability of the existing rates of

water charges to commensurate with the expenditure necessitated state Phed to reframe the

water tariff, revising and refixing the standard rates and charges for different category of

supply. The revised water tariff as finalized is indicated in table 1.5.3.

Table 1.5.3 Category of supply Applicability Rates per

connection/month

Category 1:

Domestic unmetered

connection

Premises used purely for residential purposes.

Hostels of educational institutions, working women’shostels and hostels attached with educational

institutions having separate water connections.

Destitute homes, homes for physically & mentallychallenged and orphanages.

Religious premises and cremation grounds.

15mm : Rs. 194.00

20mm : Rs. 388.00

25mm : Rs. 581.00

Category 2 :

Domestic metered

connection

Same as above Rs. 8.00 per 1000 ltrs.

Category 3:

Non Domestic/commercial

metered connection

Shops, non-AC restaurants, office premises.

Household industry requiring water only for drinking

purpose.

Government/MCD schools/educational institutions

Public urinals and latrines, cattle troughs,vegetable/milk booths.

Government institutions, professional training

institutions, jails, crèches, libraries, reading rooms,

dairies, dry cleaners.

Office of PSUS, Govt. undertakings, local bodies,

banks.

Government hospitals and Govt. dispensaries.

Health care centres without in patient facilities like

clinics.

Rs. 12.00 per 1000 ltrs.


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Category of supply Applicability Rates perconnection/month

Animal husbandry unit.

Playgrounds, zoo, any unit/concern offering

professional services.

Non AC-Guest houses maintained by Govt. or public

sector undertaking or corporate bodies.

Category 4:

Non domestic/commercial

metered connection

Hotels with lodging and boarding facilities, any

industrial unit run in factory area/industrial area, guest

house, AC restaurants, banquet halls.

Cinema halls, private hospitals, AC/Non-AC nursing

homes.

Factories, ice factories, ice cream factories, aerated

water factories

Cooling plant, cold storage.

Horticultural activities, hot mix-plants.

Swimming pools excluding of education institutions.

Private educational institutions.

Petrol pumps with or without service stations,

petroleum depots, laundries, printing press, bakeries,flour mills, theatres, circus.

Motor garage/workshop.

Power generation plants, gas oil installations, photo

labs.

Manufacturing works of RCC/PCC/marble/ mosaic

tiles, marble and stone cutting shops.

Warehouse/godowns, recreational/sports club/golf

clubs/race course.

AC/Non-AC beauty treatment parlours/clinics andAC/Non-AC massage parlours/centres.

All types of industries excluding households industries

mentioned under category-II.

Yard/workshop.

Exhibition grounds, ISBT/DTC Depot.

Fountains for ornamental use of water,

poultry/agricultural/horticultural farms and allied agro

based activities, Stadium.

Rs. 18.00 per 1000 ltrs.

Bulk Supply Municipalities/local bodies. Rs. 9.50 per 1000 ltrs.


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1.5.6 The basis, assumptions and method of calculations in arriving at the standard rates and

charges as per revised water tariff is indicated herein below :

Water availability in the project area which excludes

New Shillong Township : 37.62 Mld

Yearly generation : 1,34,43,200 Kl

In an area where supply of water is made from a number of

sources/ schemes, production cost of water in the system could

only be worked out by combining the O&M cost of all the

sources/schemes. The O & M cost of the schemes under

SUA. : Rs. 1,286.60 lakh

Cost of production per Kl : Rs. 9.35

Say : Rs. 9.50

1.5.7 Analysis of monthly water tax on individual service to household for unmetered connection base on ferrule size is worked out accordingly based on the generation cost, average flow in

the pipe according to ferrule size and average hours of supply.

1.6 Existing areas of private sector/community participation in the sector

for design, construction project management, and/or O&M services

(including billing & collection).

1.6.1 Private sector/community participation in any areas of the sector is presently nil. The state

Phed has all along shouldered the responsibility of project design, project execution, project

management and/or O&M services of all water supply system in the state including Greater

Shillong Water Supply Project. State Phed which is a well structured organization with

proper hierarchy has at its disposal, technically competent engineers in the cadre for

maintaining urban and rural water supplies.

1.7 Any other qualitative information.

1.7.1 The list of key issues that are of importance to this sector and the project are :

Protection of water sources : Though major watersheds of the Umiew river, the source of GSWSP

needs to be protected and flow of silt into the Umiew river needs to be controlled, the same is excluded

from the scope of the project.

Enhancement of source : As water impounded by the dam would be sufficient to meet the additional

demand, feasibility study for enhancement of the capacity of source would not be necessary and

excluded from the scope of the project.

Enhancement of production capacity : Creation of necessary infrastructure for generation, treatment

and supply of additional 24 Mld to fulfill long term requirements.


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Inadequate distribution networks and inefficiency in distribution system : High leakage losses

occurred in the consumers lengthy service lines as well as in the supply tank. The losses in the

transmission main and distribution system account to about 55%. Though the existing project generate

its full desired capacity, available supply at consumers’ end is far below the designated norm.

Needs for modification of distribution : Bunched connection system for distribution of water needs to

be changed. Modification and laying of distribution network for changing over to sub:main system inalready covered areas is required to be undertaken.

Distribution system for non-covered areas : All uncovered areas to be extended with new distribution

system.

Establishment of a full fledge dedicated and well equipped laboratory: The existing laboratory at

Mawphlang is not fully equipped. A full fledged laboratory equipped with all necessary equipments isrequired to be set up at the water treatment plant at Mawphlang.

Installation of chlorinators : Chlorinators are required to be installed at some strategic location to

supplement the treatment provided at the treatment plant so as to ensure the availability of adequate free

residual chlorine at consumer’s end for improved water quality.

Metered connection : Conversion of all unmetered connection to metered connection through

installation of water meters.

Cost recovery measures : Realization of cost of supply on the basis of realistic water tariff for ensuring

system self sustainability.

UFW assessment and leak reduction programme :

Production and transmission losses upto the zonal reservoirs accounts for about 20.35% which may

be due to losses in the treatment process, leakages in the supply main, old sluice valves and air

valves.

Distribution losses accounts for about 15% which is mainly due to long length of individual service

lines, leakages from service tanks, air valves and sluice valves, overflowing from storage tanks,

continuous running of water from stand posts and inefficient use of domestic connections.

The need to conduct study for UFW assessment and possible reduction of UFW from the existing

level of 30.35% to about 18% and then to 15%.

Installation of bulk water meters at generation end, reservoirs and pipelines for assessment of water

losses.

Institutional arrangement : Institutional restructuring for ensuring efficient management of theservices.

1.7.2 The project under consideration is intended to materialize the vision envisages under the

CDP in respect of water supply sector viz. to provide to consumers with an equitable,

adequate and sustainable water supply.

1.7.3 The project is designed to address all key issues/problems of the water supply sector under

the CDP and it is expected that upon implementation, the project would provide solution to

all key issues/problems under this sector.


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2. Project definition, concept and scope.

2.1 Land.

2.1.1 The GSWSP (Phase I & II) was implemented after an agreement was entered into by thegovernment in Phed with the Hima of Mawphlang. The agreement provides for the Hima ofMawphlang to donate raid land or community land free of cost to State Phed for

implementation of different components of the project, and in return, State government

would provide employment in the project for eligible youths of the Hima. Following the

agreement, sizeable area of land was donated by the Hima of Mawphlang at the Intake site

and at the WTP site where Intake & Intermediate structure and WTP were constructed

respectively. The land which was acquired and under the control of state Phed has enough

area for creating additional infrastructure for generation and treatment of water.

2.1.2 For the project under consideration viz. GSWSP (Phase III), further acquisition of land for

construction of intake structure (Stage I) and intermediate structure (Stage II) includingconstruction of WTP would not be necessary as these components are proposed to be

constructed in the area of land already acquired and under the control of state Phed.

Additional land is required to be acquired for only a few portion of the rising main and for

laying of clear water gravity main that passes through land of private parties. Since the land

to be acquired is located in rural areas, acquisition of land would not therefore pose any

problem.

2.1.3 Clear water gravity feeder mains of smaller diameter from 6th

Mile, Upper Shillong towards

different zonal reservoirs are proposed to be laid along the state road and by the side berm

of the road. Acquisition of land in this context may not be necessary since compensation forrestoration of damaged portion of the road as a result of pipe trenching is to be paid to

PWD.

2.1.4 Distribution networks is also proposed to be laid along the state road by the side berm as far

as possible avoiding laying of pipes along land of private parties. Though compensation is

required to be made for restoration of damaged road as a result of trenching along the

piping routes, acquisition of land is not necessary except incase where pipes passes private

land.

2.1.5 The quantum of land required is indicated in table 2.1.1.

Table 2.1.1. Sl.

No.

Particulars Area of land required to be acquired

M²

1. Source development (Intake structure, Intermediate structure,

building for offices, housing and roads).

Nil

2. Raw water rising main 4,000.00

3. Water treatment Nil

4. Clear water transmission system (clear water gravity main,

booster station and control room & clear water rising main).

36,000.00

5. Service Reservoir. Nil

6. Distribution system Nil


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2.2 Physical infrastructure components.

2.2.1 The population of Shillong Urban Agglomeration for 2008, 2011, 2021, 2026, 2031 and

2041 and the corresponding water requirement @135 Lpcd including UFW @15% as

worked out is indicated in the table 2.2.1.

Table 2.2.1 Daily water requirementYear Population

@135Lpcd

Mld

Total with UFW @15%

Mld

2008 3,01,000 40.63 46.72

2011 3,16,000 42.66 49.06

2021 3,74,000 50.49 58.06

2026 4,05,000 54.68 62.88

2031 4,39,000 59.27 68.15

2041 5,12,000 69.12 79.49

2.2.2 The daily water requirement, the water availability keeping in view the present UFW @

58% and future improvement in UFW @15% is indicated in table 2.2.2.

Table 2.2.2

Water availabilityYear Daily water requirement

Mld

With 58% UFW

Mld

With 15% UFW

Mld

Shortfall

Mld

2008 46.72 23.60 - 23.12

2011 49.06 - 55.75 - 6.69

2021 58.06 - 55.75 2.31

2026 62.88 - 55.75 7.13

Say 8.00

2031 68.15 - 55.75 12.40

2041 79.49 - 55.75 23.74

Say 24.00


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2.2.3 For the project under consideration, the shortfall on water availability for 2026 and 2041 is

8 Mld and 24Mld respectively. Taking this into consideration, infrastructure for generation

and distribution of additional quantity of water to meet the shortfall is required to be created

without any loss of time. Considering the potentiality of the river Umiew to cater to

additional water requirement, the project proposed to create an infrastructure at Mawphlang

for lifting and treatment of additional 24Mld of water.

2.2.4 The infrastructure to be created with the source from Umiew river at Mawphlang shall be

designed to cater to the stages of design as indicated in table 2.2.3.

Table 2.2.3

Stages of design Year Daily water requirement

Mld

Initial stage 2011 -

Intermediate stage 2026 8.00

Ultimate stage 2041 24.00

2.2.5 The proposed project viz. GSWSP (Phase III) which is described herein below (excepting

pumping machineries) is designed to provide 24Mld of water service to all the category of

consumers, improve the period of service and extend the distribution service to the urban

poor.

1. Source development.

(i) Type of source : The source of the project is the river Umiew. A mass gravity concrete dam across the riverhas already been constructed under Phase II of the GSWSP. The project (GSWSP Phase III) does not bear

any provision for further enhancement/augmentation of the source.

(ii) Diversion structure : This component has not been included under the project.

(iii) Raw Water Intake structure and pump house (Stage I) : 1 no. RCC well of 10m clear diameter of about36m in height is proposed to be constructed. An RCC pump house shall be constructed on top of the intake

structure alongwith an approach bridge of span about 40m. 3 nos. vertical turbine 4 Stage Self Water

Lubricated Pumps coupled to 200Kw electric motor are proposed to be installed. The Pumps considered is

designed to lift 8Mld of water against a total head of 112m. VVVF drives including automation control and

visualization system is proposed to be installed and as such the pumping machineries and other associated

equipments shall be compatible with VVVF drives including automation control and visualization system.

(iv) Raw Water Intermediate structure and pump house (Stage II): Located at about 0.70Km from IntakePumping Station. This consist of RCC Raw Water Sump 9.00 x 4.30m and a pump house. 3 Nos. 2 Stage

Horizontal Pumps coupled to 315Kw electric motor. The pumps considered is designed to lift 8Mld of water

against a head of 190m. VVVF drives including automation control and visualization system is proposed to

be installed and as such the pumping machineries and other associated equipments shall be compatible with

VVVF drives including automation control and visualization system.

(v) Other structure : Approach road to Stage I & Stage II pumping system, water treatment plants, colonyareas of total length of about 1km including construction of minimum number of staff quarters to provide

accommodation for housing facilities for O&M staff.


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2. Raw water transmission main : About 0.70km of 500mm MS rising main is proposed to

be laid to convey 24 Mld of raw water to be lifted by the Stage I pumping system to the

RCC sump at Stage II pumping system and about 2.5kms of 500mm MS rising main is

proposed to be laid to convey 24 Mld of raw water lifted by the stage II pumping system to

the Water Treatment Plant.

3. Water treatment plant : For providing effective treatment to raw water lifted by the

pumps, Water Treatment Plant with conventional treatment having a capacity of 8 Mld of

civil structure and to be installed with machineries/treatment units of capacity 8 Mld is

proposed to be constructed at the site of the existing water treatment plant of GSWSP

(Phase I & II) to produce and maintain water that is hygienically safe, aesthetically

attractive and palatable in economical manner. Treatment shall comprise of chemical

coagulation, flocculation, settlement, filtration and post chlorination. The water treatment

plant shall comprise of the following units.

(i) Inlet works: The inlet works shall comprise of stilling chamber and measuring channel.

(ii) Chemical house and dosing systems: Chemical house of adequate size for storage of chemicals and for

preparation of chemical solution required for treatment is proposed for construction. Alum with a solution

strength of 5 to 10% is proposed to be used as coagulant. For preparation of alum solution, 2 alum mills are

proposed to be installed each alum solution tank shall have a capacity to hold 8 hrs. requirement at the

maximum demand of chemical at the designed flow. The solution shall gravitate to a constant head dosing

tank placed over the raw water channel and the solution shall flow directly from the dosing tank into raw

water channel through a taper needle valve at a preset dosage which shall adjust itself automatically to any

change in flow rate of raw water. For PH adjustment, lime solution is proposed to be used. For preparation of

lime solution, 2 lime mills are proposed to be installed. Lime dosage shall gravitate to the raw water inlet

stilling chamber, an area of maximum turbulence, for proper mixing of the solution.

(iii) Rapid mixing : For rapid mixing of raw water with the coagulant, flash mixer is proposed to be installed.

After measuring channel, raw water alongwith coagulant shall enter a flash mixing well where the coagulant

added shall be rapidly and intimately mixed with raw water by the agitator assembly.

(iv) Clari-flocculator : Primary treatment : From the flash mixer, dosed water shall flow through a hume pipe of

600mm bore to the central shaft of the clarifier and enter the flocculating zone at the top of the shaft through

4 openings in the shaft wall, each opening 600mm high and 150mm wide. In the flocculating zone, whichshall be 8.4m dia. with an effective flocculating depth of 3.5 m, the water while flowing downwards shall be

stirred by 4 sets of flocculator paddles. It shall then passes below the flocculator wall to the settling zone of

the clarifier flowing radially outwards and upwards to the outlet launder. The clarifier has a diameter of 20m

and side water depth of 3 m. The detention time of flocculator shall be 30 minutes and that of clarifier2.8Hrs.

(v) Filters House and associated plant and equipments: Settled water from the clarifier shall pass through a

battery of 2 nos. rapid gravity sand filters. Filter cleansing shall be effected by first agitating the beds with

compressed air. After agitating the beds with compressed air, water at the suitable rate per m² of bed surface

area shall be allowed to flow in the reverse process. The associated plant and equipments to be installed shall

be compatible with automation control and visualization system provided with centrally control and

monitoring.

(vi) Clear water reservoir : Filtered water from each of the 2 filters shall flow into the common channel

chlorinated enroute into the reservoir having the capacity of 8 Ml. Water from the reservoir shall be

simultaneously transferred to the supply main maintaining maximum pressure in the reservoir at all time.


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(vii) Disinfection : For sterilization of the filtrate, chlorination with chlorine solution shall be used. The flow of

chlorine from the chlorine cylinder into the absorption tower shall be adjusted and control by the chlorinator

control panel.

(viii) Control room & laboratory : The various process of the plant shall be centrally monitored and control

from the control room of the existing WTP through automation control and visualization system. A full

fledged dedicated and well equipped laboratory is also proposed to be set up.

4. Clear water transmission system : The areas demarcated for covering under the project

(GSWSP Phase III) is divided into 13 zones including 9 zones which were earlier

demarcated for coverage under GSWSP (Phase I & II). These zones are Zone I to Zone X

excluding Zone VII comprising areas of Pynthorumkhrah. Although substantial works were

carried out under the scheme which includes substantive improvement in reservoir and

primary pipe line, considerable amount of works are yet to be done in distribution of water.

Clear water from the water treatment plant at Mawphlang shall be transmitted to reservoirs

constructed/proposed to be constructed for each zones. Under the project, a total length of

about 58.063km of pipes varying in sizes from 1000mm to 100mm are proposed to be laid.

Booster arrangement is proposed to be installed at 6th Mile, Upper Shillong for lifting water

via. a 300mm dia. DI rising main to the main reservoir at Laitkor for distribution to

Madanriting. The zonewise breakup of population is appended as appendices and the

summary of the zonewise breakup of population is indicated in table 2.2.4. The zonewise

break up of daily water requirement of all the zone under the project area as worked out is

appended as appendices. The summary of the zonewise daily water requirement is indicatedin table 2.2.5

N


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Table 2.2.4 Projected populationZonewise

Classifica

tion

Areas of Coverage

2007 2011 2021 2026 2031 2041

I Police Bazar, Jail Road, Oakland &

Assembly Areas

11127 11290 14145 14749 16857 20305

II Lachumiere, Secretariat 11686 12189 15535 17643 18815 23495

III Laitumkhrah 16695 18175 22405 24090 27610 34477

IV Malki, Dhankheti Areas 11623 13215 15368 16377 18322 22768

V Nongthymmai, Pohkseh 37142 38085 42431 45530 47052 50146

VI Pasteur Institute, Lawmali, Part of MawlaiMawroh, Polo Bazar, Polo Hills, ForestColony, Nongmali

4674 4741 5777 6031 6594 7920

VII Pynthorumkhrah, Pynthorbah 26723 28627 36424 39257 41653 43876

VIII Mawlai 41858 42748 46090 48012 49128 50756

IX Laban, Bishnupur, Rilbong & Kench’sTrace

41923 45055 57562 63849 71578 91748

X Mawprem, Jaiaw, Mawkhar, South EastMawkhar, Barapathar

44848 51072 58804 64266 71682 91070

XI Nongmynsong 15613 16057 18077 18943 21380 22941

XII Madanriting, Happy Valley areas. 19426 21118 25747 28076 29028 32083

XIII Shillong Cantonment Area 12662 13628 15635 18177 19301 20415

Total : 296000 316000 374000 405000 439000 512000

Table 2.2.5 Daily water requirement worked out @ 135 Lpcd for of the population

and UFW @15%Zone

2007 2011 2021 2026 2031 2041

I 1727467 1752773 2196011 2289782 2617049 3152351

II 1814252 1892342 2411809 2739076 2921029 3646046

III 2591899 2821669 3478376 3739973 4286453 5352554

IV 1804471 2051629 2385882 2542529 2844491 3534732

V 5766296 5912696 6587413 7068533 7304823 7785167

VI 725639 736040 896879 936313 1023719 1229580

VII 4148746 4444342 5654826 6094649 6466628 6811749

VIII 6498455 6636627 7155473 7453863 7627122 7879869

IX 6508546 6994789 8936501 9912557 11112485 14243877

X 6962652 7928928 9129321 9977297 11128631 14138618

XI 2423918 2492849 2806454 2940901 3319245 3561590

XII 3015887 3278570 3997222 4358799 4506597 4980886

XIII 1965776 2115747 2427334 2821979 2996480 3169429

Total: 45954004 49059001 58063501 62876251 68154752 79486448


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5. Service reservoir : The capacity of storage reservoir is computed on the basis of 20 hours.

pumping and the capacity required, the capacity of reservoir in existence under GSWSP

(Phase I & II) and additional capacity required to be constructed is indicated in table 2.2.6.

Table 2.2.6

Zones Areas proposed to be covered Capacity ofstorage reservoir

required

(Ml)

Existingreservoir

capacity

(Ml)

Proposedcapacity of

storagereservoir

(Ml)

1 2 3 4 5

6½ Mile - - - 3.30

4½ Mile - - 2.90 -

I Police Bazar, Jail Road, Oakland and Assembly areas. 1.09 1.16 -

II Lachumiere and Secretariat 1.26 1.12 0.14

III Laitumkhrah 1.85 0.23 1.12

IV Malki and Dhankheti areas 1.22 3.75 -

V Nongthymmai and Pohkseh 2.69 3.38 -

VI Pasteur Institute, Lawmali, parts of Mawlai Mawroh,Polo Bazar, Polo Hills, Forest Colony and Nongmali

0.43 0.34 0.09

VII Pynthorumkhrah, Pynthorbah and Lyngkien shyiap 2.36 - 1.00

VIII Mawlai 2.73 1.39 0.84

IX Laban, Bishnupur, Rilbong and Kench’s Trace 4.93 1.25 1.03

X Mawprem, Jaiaw, Mawkhar, South-east Mawkhar andBarapathar

4.89 0.34 1.17

XI Nongmynsong, Ishyrwat, Mawpat and Lyngkien 1.23 - 1.23

XII Madanriting, Happy Valley areas and Mawshabuit 1.72 - 1.72

XIII Shillong cantonment area. 1.10 - -

Total : 27.50 15.86 11.64

6. Distribution System : Control of the very high UFW under the existing distribution system

is extremely difficult. The project, therefore, proposed to lay a well planned distribution

network for the entire project area. The proposed distribution system is a Loop System and

designed to ensure residual pressure differential at various node to remain in a manageable

band of 7 meters to 17 meters. DI pipes has been considered for use in the distribution

system. Considering the topographical condition of the project area, installation of pressure

reducing valves are proposed to be used at some strategic location in the distribution

networks to ensure equitable distribution of water.


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2.2.6 Design consideration.

2.2.6.1 All components of the scheme are designed/considered as per the norms and standard laid

down in the Manual on Water Supply and Treatment published by CPHEEO, Ministry of

Urban Development, Government of India as far as practicable.

2.2.6.2 The scheme is designed to meet the requirement over a period of 30 years after completion.

The time lag of 3 years between design and completion of the project have been taken into

account thereby making 2011 as the initial period, 2026 and 2041 as the intermediate and

ultimate period of the scheme respectively. The 30 years period of the project is however

modified in regard to certain components of the project depending on their useful life and/or

the facility for carrying out the extensions when required so that expenditure far ahead of

utility is avoided

2.2.6.3 In forecasting the population of the town, the programme developed by MoU, CPHEEO is

adopted to arrive at the initial, intermediate and ultimate period of the scheme.

2.2.6.4 As implementation of sewerage project is contemplated in the project area, the per capita

rate of supply is considered as 135Lpcd.

2.2.6.5 The source of the existing water supply project i.e. GSWSP (Phase I & II) is the river

Umiew. A mass gravity dam across the river has already been constructed under Phase I of

GSWSP. The dam constructed provide storage of 9.145Mcm of water for pumping by the

system. The catchment of the river Umiew is about 115 sq.km and a large area of the

catchment is in close proximity to Cherrapunjee. As a result, the catchment receive a fairly

good amount of rain in comparison to other areas. During the dry weather months of

2006-07, Umiam reservoir (Barapani) water level dropped alarmingly low warranted theState Electricity Board to resort to load shedding for a pretty long period of time. The

situation was comparatively different with Umiew river. During the same period, water

from the dam of GSWSP is spilled daily for almost 24 hr. a day despite lifting about

34.00Mld of water indicating that the river has the potential to cater to the additional

requirement. The project under consideration, has, therefore, no provision for

enhancement/augmentation of the source.

2.2.6.6 Considering the weather condition of the area, the necessity for construction of all weather

road to different work sites viz. pumping stations, sub:stations, WTP & staff quarters for

transportation of construction materials during construction and pre-commissioning period

and to facilitate O&M of the project on post commissioning period including construction

of minimum numbers of staff quarters for O&M personnel is absolutely necessary and

therefore considered.

2.2.6.7 The site for construction of the intake structure under the project is located a few distance

away from the intake structure of the existing source (Phase I & II). The source being the

same i.e. water impounded by the dam, construction of intake structure is to be considered

with respect to HFL and LWL of the dam and the level position of intake structure of the

existing project (Phase I & II) is also to be considered to ensure same level is adopted for

pump floor level and delivery floor level. Considering the topographical and soil condition

of the site, considerable excavation may have to be carried out for proper foundation of theIntake well.


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The size of the intake structure is arrived at taking into consideration the space requirement

and the out planning of pumping system for the ultimate stage. The factors considered are

as under:

The minimum water level/crest level of dam is at RL 1562.00m above mean sea level and the high flood level is

at RL 1577.00m above mean sea level. In order to keep the operating floor free from obstruction and pipe work,

delivery is taken below the pump floor level i.e. at RL 1583.20m, 2.40m below the pump floor level which is atRL 1585.60m and 8.6m above the high flood level in keeping the same level with the existing intake structure

The depth of the Intake well has been considered taking into consideration the minimum water depth required

upto minimum WL to satisfy NPSHR for VT Pump to avoid air entry during drawdown.

Provision for prevention of vortex formation.

Provision for obtaining uniform distribution of the in-flow to all the operating pumps and to prevent starvation ofany pump.

Though civil structure has been designed to cater to the demand of the ultimate stage, the pumping units has been considered to cater to the demand of the intermediate stage.

2.2.6.8 The size of the pump houses is arrived at taking into consideration the space requirementand the out planning of pumping system for the ultimate stage. The factors considered are

as under :

The availability of sufficient space in the pump house to locate the pump, motor, valves, pipings, control panels

and cable trays in a rational manner with easy access and with sufficient space around each equipment for the

maintenance and repairs.

The availability of sufficient space between two adjoining pumps/motors.

The provision of sufficient space for the control panels as per the Indian Electricity (I.E.) Rules.

The provision of service bay in the station with different space to accommodate overhauling and repairs of the

largest equipment.

Provision of a ramp or a loading and unloading bay so that all pipings and valves can be laid on the lower floor

permitting free movement in the upper floor.

Provision of a head room and material handling tackle with adequate clearance to lift the motor clear off the faceof the coupling and also carry the motor to the service bay without interference with any other apparatus

including adequate clearance to dismantle and lift the largest column assembly.

Though civil structure has been designed to cater to the demand of the ultimate stage, the pumping units has been considered to cater to the demand of the intermediate stage.

2.2.6.9 The size of RCC sump at the Intermediate pump house is arrived at taking into

consideration, the storage requirement and the out planning of the pumping system for the

ultimate stage. The factors considered are :

Avoidance on starvation of pumps in the event of sudden tripping of pumps of the Intake Pumping

station for a duration of about 30 minutes or so.

Avoidance of mutual interference between two adjoining pumps by maintaining sufficiency clearance.

Avoidance of dead spots by keeping rear clearance from the center line of the pump.

Avoidance of sudden change in the direction of flow by provision of a stilling chamber to reduce thevelocity gradually to about 0.3 m/s near the suction bellmouth.

Avoidance of dead spots at the suction bell mouth by maintaining the bottom clearance.

Provision for adequate submergence of the inlet of pump under the LWL, so as to prevent entry of air

during draw-down and to satisfy NPSHr.


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2.2.6.10 In a water supply projects, pipelines are a major investment and constitute a major part of

the assets. Pipes represent a large proportion of the capital invested in water supply projects

and therefore are of particular importance. Pipe materials for the project have therefore been

judiciously selected not only from the point of view of durability, life and overall cost

which includes, besides the pipe cost, the installation and maintenance costs necessary to

ensure the required function and performance of the pipeline through out its designedlifetime.

2.2.6.11 The final choice of pipe materials for the project was arrived at taking into consideration the

technical factors such as internal pressure, co-efficient of roughness i.e. ‘C’ value, hydraulic

and operating conditions, maximum permissible diameter, internal and external corrosion

problems, laying and jointing, type of soil, special condition etc.. For the raw water rising

main, the alignment passes through very difficult terrain. In view of the site conditions, the

choice of pipe materials are governed by the following factors :

The ease or difficulty of transportation, handling and laying and jointing.

The safety, economy and availability of manufactured size of pipes and specials.

The availability of skilled personnel in construction and commissioning of pipelines.

The ease or difficulty of Operation & Maintenance.

2.2.6.12 Considering the factors, the choice of pipe materials for raw water rising main and is

limited to MS pipes. Pipes proposed to be laid underground shall be protected against

external corrosion by providing necessary treatment like hot applied coal-tar asphaltic

enamel reinforced with fibre glass fabric yarn and those proposed to be laid on/above

ground shall be properly painted. The economical diameter for rising main was arrived at,

using computer software viz. Ecodia.

2.2.6.13 Since the pumps to be installed for Stage I pumping system are vertical turbine pumps, the

frequency of breakdown of pumps is comparatively higher than that of a horizontal pumps.

Since pumps with parameter to suit the scheme would have to be tailor made and

considering the remoteness of the location of the site, 3 units of vertical turbine pumps are

proposed to be installed. The vertical turbine pumps shall be of 1400Rpm, 4 stage self

water lubricated. Out of the 3 units, 2 would be in operation at a time on roaster basis to

cater to the demand of intermediate stage of 8 Mld.

2.2.6.14 To facilitate correlation of discharge of the pumps of the Intake and Intermediate pumping

stations; 3 units. of horizontal pumps are also proposed to be installed at the Intermediate pumping station. Out of the 3 units, 2 units will be in operation at a time to cater to the

demand of intermediate stage of 8 Mld.

2.2.6.15 Frequency in the power system is a vital parameter which determines the quality of AC

supply. The rated frequency in the country is 50 Hz.. and all electrical equipments as well

as the whole power system are designed for obtaining the optimum efficiency when

connected to a power supply of this rated frequency. The performance of the electrical

equipments and the power system changes when the frequency deviates from 50 Hz. and

though it is necessary to maintain the system frequency as close to 50 Hz. as possible, so as

to have the best efficiency of operation, frequency fluctuate whenever load connected in

the system does not match with that of generation.


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2.2.6.16 In a hydraulic machineries, the laws of interrelation between discharge Q, head H and

speed N are as under :

Q N and H N²

2.2.6.17 Likewise, the laws of interrelation between speed N of electric motor and frequency f of

power system is as under :

Ns =

Where,

Ns = Synchronous speed of field in Rpm

F = Frequency in cycle per sec or hertz. (C/s or Hz.)

P = No. of stator poles of motor.

As P is constant, Ns f

2.2.6.18 Frequency of power system in the state is highly fluctuating. The frequency dips as low as47.50 Hz. and shoots as high as 51.50 Hz.. The highly fluctuating frequency of power

system in the state has had an adverse impact on the original pumping system of GSWS

(Phase I & II) where the 2 stage pumping system commissioned in 1986 had to be

converted to a 3 stage pumping system through the installation of Booster Pumps station in

1996 following continuous problem encountered in lifting of water by the system on

account of continued fluctuation in frequency of power system.

2.2.6.19 Though following the replacement of the original pumping units with new ones in 2007

Booster Pumps station was eliminated and stage II pumping system could discharge

directly into the WTP, special consideration in designing of pumps units were taken into

account to overcome fluctuation in the frequency of power system, the new pumps

installed and commissioned were designed to develop required discharge pressure at a

speed of 1400Rpm corresponding of motor speed when connected to power system with

frequency of 47.50 Hz.. The motor capacity was considered taking into consideration the

power to be drawn by the pump when speed suddenly shoots up as a result of sudden

fluctuation in the frequency of power system to the upper limit.

2.2.6.20 The pumping units under the project i.e. GSWS (Phase III) has been considered taking into

consideration the highly fluctuating frequency of power system in the region.

2.2.6.21 The electric motor for the project shall preferably have the following characteristics :

(a) Intake raw water pumping system : Stage I

Type of enclosure SPDP suitable for IP.23

Class of duty - S1 suitable for continuous duty.

- suitable for minimum 3 equally spaced starts per hr.

- suitable for atleast 1hot restart.

Class of insulation Preferably Class F on account of dampness, high humidity content

and lightning proneness of the area.

System voltage 6.6Kvfor easy O&M.

120f

P


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(b) Intermediate raw water pumping system : Stage II

Type of enclosure SPDP suitable for IP.23

Class of duty - S1 suitable for continuous duty.

- suitable for minimum 3 equally spaced starts per hr.

- suitable for atleast 1hot restart.

Class of insulation Preferably Class F on account of dampness, high humidity content

and lightning proneness of the area.

System voltage 6.6Kv for easy O&M.

2.2.6.22 In a pumping system generated flow of water increases or decreases with the increase in

motor speed corresponding to the upward or downward fluctuation in the power system

frequency. Though the generated flow could be controlled by mechanical means through

throttling process, these mechanical means of achieving flow control have a major

disadvantage, in terms of friction, resulting in energy loss and overall poor efficiency.

2.2.6.23 Further, energy is a scarce commodity particularly in developing and underdeveloped

countries. Cost of energy is increasing spirally day-by-day. Generally pumping installations

consume huge amount of energy. The proportion of energy cost can be as high as 70% of

overall cost of operation and maintenance of water works. The need for conservation of

energy, therefore, cannot be over emphasized. All possible steps need to be identified and

adopted to conserve energy and reduce energy cost so that water tariff can he kept as low as

possible and gap between high cost of production of water and price affordable by

consumers can be reduced.

2.2.6.24 The GSWS project being a high head pumping scheme envisages multi stages pumping

system, the consumption of energy for lifting of water from the river/dam is exceptionally

high. Considering the high cost in procurement of energy, and the practical difficulties

encountering in operation of the machineries on account of wide range of fluctuation in the

system frequency that adversely affects the efficiency of the pumping system, there is a

necessity for installation of suitable equipment\devices which could maintain a stable

output voltage and frequency thereby enable controlling the generated flow of water during

the process of pumping without effecting conventional mean of flow fluid control viz.

throttling. In such circumstances energy is saved as frictional losses accounted for through

the process of throttling is eliminated.

2.2.6.25 For ensuring stable output voltage/frequency to the pumping system irrespective of

fluctuation of voltage and frequency in the system and also for ensuring that sufficient

energy is saved during the process of pumping, the project GSWS (Phase III) envisages

among others, installation of VVVF drives.

2.2.6.26 In the case of Stage I pumping system, the total pump head is 112m. Considering the total

pump head, the valves inside the pump house including the delivery manifold should have a

working pressure of not less than 1.5 times the working pressure i.e. not less than

20Kg/cm². Good quality, quick closing non-return valve is proposed to be provided in the


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transmission main downstream of the delivery manifold. In the case of Stage II pumping

system, the picture is comparatively bad as the total pump head is 190m. In such a situation,

water hammering would be quite severe in the event of power failure. Considering the total

pump head, the valves inside the pump house including the delivery manifold should have a

working pressure of not less than 30Kg/cm². Non return valves on the individual pump

delivery lines are proposed to be provided with dash pot arrangement to dampen the rate ofclosure towards the end of closure. Air valves are also proposed to be provided in the rising

main.

2.2.6.27 Though good quality, quick closing non-return valves are proposed to be provided, the

situation may not be sufficient to withstand against severe water hammering in the event of

power failure. Providing protection devices against surge pressure is therefore absolutely

necessary for the safety of plant and machineries. Provision, is, therefore included in the

project estimated cost.

2.2.6.28 Raw water is proposed to be lifted from the river against the total head of 112m in the caseof Stage I pumping system and 190m in the case of Stage II pumping system. Sudden

tripping of pumps in the event of power failure or breakdown of machinery, severe water

hammering may be set up in either the pump discharge and/or suction piping which may

have sufficient magnitude to rupture the pipe or damage the connected equipment.

Normally in a pumping system, the strength of the pipes and valves in the pump house will

be as good or better than the strength of pipes and valves in the transmission main. The test

pressure for the pipes and valves are normally fixed in relation to the pump head. This

makes the pipes and valves in the pump house, upto and including the delivery manifold

relatively vulnerable to surge pressure/water hammering. Hence, the surge protection

system, if any, should provide protection essentially for this small vulnerable reach.

2.2.6.29 Though the wall thickness (9.50mm) of the pipes for rising main may be sufficient to

withstand very severe surge pressure, the valves in the pump house including the delivery

manifold is required to be properly selected so as to prevent the damage of the machineries

in the event of sudden tripping of pumps as a result of power failure.

2.2.6.30 The Water Treatment Plant under consideration is designed to produce and maintain water

i.e. hygienically safe, aesthetically attractive and palatable, in an economical manner.

Evaluation of water quality shall not be confined to the end of the treatment facilities but

shall be extended to the points of consumers use. Considering the nature of raw water

quality constituents and the desired standards of water quality including the comparative

economics of alternative treatment steps applicable, the sequence of treatment and units of

operation proposed to be employed in the WTP, shall comprise of chemical coagulation,

flocculation (rapid and slow mixing) and clarification, filtration and post chlorination.

Though, the civil structure for the WTP has been designed to cater to the demand of the

ultimate stage, the treatment units/machineries including electrical-mechanical equipments

considered under the project would cater to the demand of the intermediate stage.

(i) Inlet works : For meeting the demand of ultimate stage, 2 nos. of inlet works are proposed under the project.

Each inlet works shall include raw water stilling chamber at right angle to the flow, a raw water channel with

parshall flume for measurement of flow rate. The raw water channel shall be 2m wide and the parshall flume

shall have a threat width of 1.22m.. Measuring equipment for measurement of flow shall be installed.


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Calibration of the measurement device shall initially be carried out and periodically be checked to ensure

accuracy. Since only 1 No. inlet works would be able to cater to the demand of intermediate stage, the other

inlet works considered under the project is only for civil structure and without any electro-mechanical units.

(ii) Dosing system : Alum solution of 5-10% strength is proposed to be used as a coagulant and lime suspension

is proposed to be applied for PH correction. Alum solution shall be prepared in 2 alum mills and each alum

solution tank shall have the capacity to hold 8 hrs. requirement at the maximum demand of chemical at thedesigned flow. The alum solution tank shall be provided with a free board of 0.3m. The solution tank shall

be constructed with reinforced cement concrete with suitable lining of rubber to resist corrosion. The alum

solution tank shall be located inside the chemical house where chemicals shall be stored and shall be located

at a suitable elevation to facilitate gravity feed of the chemical solution. A lifting tackle for lifting the

chemicals to die elevated tanks shall be provided. The solution tank shall be also be provided with a platform

of at least 0.75m wide to allow the workers sufficient space for handling the chemicals and preparing the

solution. The platform shall be provided with a railing upto a minimum height of 0.75m. The platform shall

be located at an elevation to have clear head room of 2m from the ceiling. The top of the solution tank shall

not be higher than 1m from the floor of the platform.

Dissolving box with the pipe manifold having holes either at bottom or at sides for dissolving chemicals

shall be constructed. Each solution tank shall be provided with mechanical agitator for maintaininghomogeneity of the prepared chemical solution. Alum solution from the solution tank shall gravitate via.

chemical feed lines to a constant head dosing tank placed over the raw water channel and solution shall flow

directly from the dosing tank into raw water through a taper needle valve at a preset dosage which adjust

itself automatically to any change in flow rate of raw water.

Lime suspension shall be prepared in 2 lime mills, each having capacity to hold 8 hrs. of requirement at the

maximum demand of chemicals at the designed flow. Dosage shall be adjusted by regulating a variable ‘V’notch. The dose shall gravitate via. the chemical feed lines to the raw water stilling chamber, an area of

maximum turbulence in the raw water channel.

(iii) Chemical house, administrative building & laboratory : An RCC building to provide for storage of

chemicals, rooms for control and administration including laboratory is proposed to be constructed. The

building to be constructed, takes into consideration the space necessary for storage of chemicals viz. alum,

lime & chlorine gas cylinder for a minimum of 3 months requirement, space required for installation of

2 alum mills, 2 lime mills and chlorination room in one floor, administration & control, electrical &

laboratory in the other floor. The building shall have sufficient space with access for handling bulk storage

allowing for negotiating of vehicles and cranes likely to be u

gswsp dprphaseiii.pdf

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