MUNICIPAL CORPORATION OF GREATER

MIDDLE DAM TAL : Mokhada , DIST:

1.0 PREAMBLE:

Mumbai a commercial capital and is one of the thickly populated metropolitan city in the country. Mumbai has the largest inflow of migrants. Municipal Corporation of Greater Mumbai is continuously making concrete efforts to cope up with the growing demands for water towards domestic and industrial consumption. Vaitarna River, a west flowing river originating from Sahyadri ranges, is one of the major sources of water supply to Mumbai city. The river potential has already been partly harnessed by constructing two storage dams in series across the river e.g. Upper and Lower Vaitarna i.e. Modak Sagar dam, with combined yield of 986 million liters per day. The two dams are 42 km apart. After construction of the proposed Middle Vaitarna dam, releases from Upper Vaitarna Power Station will flow in to Middle Vaitarna reservoir. The city’s present population is 14.50 million. The projected population in 2021 will be 17.15 millions, in 2031, 19.39millions, and 2041 it will be 21.21millions. In spite of attempts to reduce population concentration, to restrict the influx of migrants by systematic development of Suburbs like Navi Mumbai, the population is still at a sizable figure.

Supply of water is one of the major factors, which leads to development of city. Present supply of water to Mumbai is drawn from four major and two minor sources. Availability from these sources is given below.

Table -I

Water Sr. No. Source Supply in Remarks Mld.

1) Tansa 455 2) Upper Vaitrana 635 3) Lower Vaitrana 455 4) Bhatasa Project 2020 5) Tulsi 18 6) Vihar 90

Total 3673

At present available quantity of water at source is 3688 Mld as against water demand of 4240 Mld. This gap will go on increasing in future. 1.1 RECOMMENDATIONS OF Dr. CHITALE COMMITTEE:

The expert committee was appointed by Government Of in the year 1993, under the chairmanship of Dr. Chitale ( Ex. Secretary Water Resources Deptt. Government of India) for advice on the long term planning for augmentation of water supply to Mumbai. The committee recommended water supply norms for the good health and to prevail good environmental conditions. Based on surveys carried out by the committee, considering the sub tropical climate and modern gadgets, the planned development requirement is worked out as 240 lpcd and that for slum at 150 lpcd, considering the continuous water supply system. Committee also recommended development of projects like Pinjal and Gargai. The probable water supply from these sources will be as under.

Table-II

Sr. Proposed Source Mld. No. 1) Middle Vaitrana Dam 455 2) Gargai 440 3) Pinjal 865 Total 3361 Government of Maharashtra has accepted Dr. Chitale Committee’s recommendation and approved the above mentioned source. MCGM has therefore taken the Middle Vaitarna Project as an immediate additional source of water supply to augment the present water supply scheme.

2.0 DETAILS OF DAM:

Contract: This is one of the ambitious projects owned by Municipal Corporation of Greater Mumbai, Maharashtra, India. The work had been awarded to M/s CWE SOMA Consortium. The contract period was 54 months inclusive of monsoon.

Salient Features :

1) Length of Dam: 565m. 2) Height : 102.40m.

3) Dam Top RL : 287.40m 4) Full Reservoir Level : 285.00m

5) Max. Water Level: R.L. 285.0m 6) Crest R.L. : 273.00m.

7) River Bed R.L. : 185.00m. 8) Gate Size : 15m x 12m , 5 Nos.

9) Pier Thickness : 3.50m 10) Lenth of Overflow Section: 96m 11) P.M. F. : 6348 Cumecs 12) Length of NOF: 408m on Right & 61m on left.

Construction Program : Total volume of concrete for dam is 15,50,000 cum. Out of which Roller Compacted Concrete is 12,15,000cum and conventional concrete is 3, 35,000 cum. The placement of the RCC was based on 15.45 month period.

Split Level Construction : Considering dam length of 568m with total quantity RCC 12.05lakhs, and availability machinery a split was proposed at RD 235m. While deciding split, maximum quantity in one layer and the progress that can be achieved in the available machinery was taken into account. Considering the construction period of sixteen months, an average rate of placement of 80,000 cum per month was planned. To achieve this, a peak month placement was 1.50lakhs to 1.60lakhs cum, and peak day 7500 to 9000 cum was planned. However, observed placement of RCC peak was 1,36,000 cum a month and average 77,515 Cum.

Important Highlights of the project :

9 The RCC at Middle Vaitarna has been completed almost exactly two years after the first RCC was placed in the dam. 9 The total time taken to place the RCC in the dam has been 15.45 months at an average rate of placement of 77 815 m3/month making Middle Vaitarna the Ninth fastest RCC dam at the time of completion so far. 9 The RCC dam at Middle Vaitarna is estimated to be 37% cheaper than any other form of dam construction 9 It is claimed that Middle Vaitarna has been completed two years earlier than a traditional concrete dam. 9 It was possible to impound to Elevation 273 (i.e. spillway crest level) during the 2012 monsoon. 9 The quality of Middle Vaitarna in terms of the impermeability is excellent and in terms of strength exceeds the specified requirements. Annexure 1 Details of projects approved by the MoEF in respect of project proponents, for diversion /use of lands of Pas since coming into force of the WLPA1972, and of areas falling within the Ecologically Sensitive zone or radius of 10 km of such PAs

SR No Name of Agenda item Protected Area approved Conditions Date of the no. and date area/ESZ in PA/ESZ for imposed by Commencement project, of meeting of involved use/diversion SC(number) of work and state SC (ha.) 1 Middle MoEF Letter 634 634 Attached ϮϳKĐƚŽďĞƌ 2008 Vaitarna 8-137/2002- water FC dated 27 supply april 2004 project refers