Tanda TPP-II, (2x660 MW)

ASH DYKE PACKAGE


BRIEF SCOPE OF WORK:


The scope of work includes construction of starter ash dyke at two locations, covering one storage lagoon and one sedimentation basin at Dyke-1 location & two storage lagoons and a common over floe lagoon(OFL) at dyke-2. Construction of two well type water escape structures & Spillways is also envisaged for decanting the slurry water (if any) and rain water. Bituminous Inspection road all along the periphery of ash dyke and over the top of dyke with provision of cross drain is also envisaged.


The detailed scope and description of work covered under this package has been specified in relevant clauses of Part-A of Technical specifications.


SALIENT TECHNICAL FEATURES:


The scope of work includes construction of two starter ash dyke at two different location, covering one storage lagoon with sedimentation basin at dyke-I location and two storage lagoons with a common overflow lagoon (OFL) at dyke-II location. Construction of well type water escape structures & Spillways is also envisaged for decanting the slurry water and rain water in both the ash dykes. Bituminous Inspection road all along the periphery of both the ash dykes with provision of cross drain works is also envisaged. Perimeter RCC drain is also envisaged all around the periphery of both the ash dykes. Impervious lining with Bentonite mixed soil for bottom of dyke-II is also envisaged. Diversion of existing natural nallah at dyke –I location is also considered under the scope of this package.

The major work involved in this package will be as given below;

  1. Earth work in Embankment Construction = 20,00,000 cum ( with earth excavated from inside ash pond area))

2. Providing Sand filter = 3, 60,000 cum

  1. Providing Coal Mill Reject filter = 1,00,000 cum

  2. Providing Rock toe & rip rap with Coal

Stone Boulder = 1,60,000 cum

  1. Reinforced concrete work = 14,200 cum

  2. Water Bound Macadam = 30,500 cum

  3. Fly ash bricks (Free issue) = 6,00,000 Nos.

  4. Bituminous Courses = 11,050 cum

  5. Non woven Geotextile = 30,000 Sqm




DETAILED SCOPE OF WORK.


The scope and description of work covered under this package has been specified in relevant clause of Technical specifications. However, the Contractor may note the brief description of works of this package as below:


The proposed ash dyke areas is within 5 km from the plant boundary. The scheme for ash disposal envisages one storage lagoon with sedimentation basin at Ash Dyke- I location and two storage lagoons & a common over flow lagoon at Ash dyke-II location in the ash disposal areas. The topography of the proposed ash dyke areas is almost flat. Ground level is varying from RL 86.0 to 89.0M for Ash Dyke-I & from RL 88.0 to RL 90.0M for Ash Dyke –II. The total length of the starter for both the dykes is estimated to be about 11.0 km. Construction of two well type water escape structure with flexible opening is also envisaged for decanting water from storage lagoon to over flow lagoon/sedimentation basin. Decanted water from storage lagoons through RCC well will be collected into over flow lagoon (OFL). Construction of spillways is also envisaged for discharging excess rain water from storage lagoons to OFL/RCC perimeter drain and from OFL to the existing drainage. Scope of work also involves construction of rock toe, toe drain and rip rap for down stream slope protection works of dyke embankment. Impervious lining to bed of storage lagoons and OFL at Ash Dyke-II with bentonite blended soil is also envisaged under scope of this package. Construction of bituminous inspection road and RCC perimeter drain all around the periphery of the dykes is also under the scope of this package. Scope of this package also include diversion and training of existing nallah at dyke-I & II.


All construction works shall be carried out based on the drawings which are released by the owner for construction.


The Work involved is mainly related, but not limited, to the following:

      1. Preparation of work areas / clearing site / jungle clearance.

      2. Ground stripping.

      3. Excavation.

      4. Foundation preparation.

      5. Formation of the dyke section with earth as per drawing.

      6. Formation of sand chimney, sand blanket and sand filter.

      7. Construction of dyke rock toe, rip rap and filters with coal mill reject & coal stone for forming toe drain/rock toe/rip rap.

      8. Dyke outer slope protection with turfing & rip rap using geotextile.

      9. Dyke inner slope protection with coal mill reject & coal stone boulder packing confined within coal stone boulder masonry panel walls.

      10. Construction of dyke slope drains, kerb wall & Steps on D/s Slopes with brick masonry.

      11. Construction of RCC works for water escape structures, Hume pipe cross drainage for bituminous inspection roads, RCC peripheral Drain & RCC Spillways.

      12. Laying and embedding RCC Hume pipe.

      13. Bituminous Inspection roads all along the periphery of starter ash dyke and over the top of dyke.

      14. Installation of instruments for monitoring purpose.

      15. Impervious lining with bentonite mixed soil