Construction of an ash pond with wrp,


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Ash pond construction using waste recycled product (WRP) Flyash and Locally available soil

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Construction of an ash pond with wrp,

  1. 1. CONSTRUCTION OF AN ASH POND WITH WRP, FLY ASH AND LOCALLY AVAILABLE SOIL – A Case Study by 1. A.K.Choudhary, 2. J.N.Jha and 3. B.P.Verma 1. Lecturer, Deptt. of Civil Engg., NIT, Jamshedpur 2. Professor, Deptt. of Civil Engg., Guru Nanak Dev Engineering College, Ludhiana 3. Director, Sangvi Innovative Acad Indore, MP
  2. 2. Index <ul><li>Introduction </li></ul><ul><li>Methodology </li></ul><ul><li>- Present problem </li></ul><ul><li>- Possible Solution </li></ul><ul><li>Laboratory investigation and test results </li></ul><ul><li>Section of the Ash Pond Dyke </li></ul><ul><li>Conclusions </li></ul><ul><li>Acknowledgement </li></ul><ul><li>References </li></ul>
  3. 3. Introduction <ul><li>Development of national linked with industrial growth </li></ul><ul><li>Quantity of waste generated increases with industrialization causing </li></ul><ul><li>a) Disposal problem </li></ul><ul><li>b) Environmental degradation </li></ul>
  4. 4. Cont…. <ul><li>In India </li></ul><ul><li>a) 75% energy supply is from coal based thermal power plant (TPP) </li></ul><ul><li>b) 90 thermal power plants produces 100 million tonne of fly ash </li></ul><ul><li>c) Disposal of fly ash (TPP) is by use of ash pond </li></ul>
  5. 5. Cont. <ul><li>Problems associated with Ash Pond construction </li></ul><ul><li>a) Require huge quantity of soil </li></ul><ul><li>b) If good quality of soil not available nearby site, cost of construction become too high/prohibitive also. </li></ul><ul><li>c) No well defined design procedure/codal provision exist for ash pond construction. </li></ul>
  6. 6. Methodology (Present Problem) <ul><li>Construction of an ash pond dyke for a thermal power station (Tata Power -427.5 MW, Jamshedpur, Jharkhand) </li></ul><ul><li>Proposal for ash pond dyke: </li></ul><ul><li>Construction of containment dyke with impervious core overlain by relatively pervious casing on U/S and D/S side, with imported soil wherever necessary. </li></ul>
  7. 7. Cont… <ul><li>Good quality soil not available locally. </li></ul><ul><li>Huge transportation cost of borrow material required thus increasing cost of construction </li></ul><ul><li>How to reduce transportation cost. Use of locally available industrial waste : Blast Furnace slag coming out of the Tata Steel (Waste recycled product-WRP) </li></ul>
  8. 8. Cont. <ul><li>WRP : Size Range:Sand and Gravel </li></ul><ul><li>Fly Ash: Size : Silt Particle </li></ul><ul><li>Waste material : Non plastic and highly permeable </li></ul><ul><li>Difficult to meet slope stability and permeability requirement. </li></ul><ul><li>For better gradation require close packing of grains (Compacted mass of dyke). </li></ul>
  9. 9. Methodology (Possible solution) <ul><li>Fly ash and WRP if mixed with some admixture (Cement/Clay) : </li></ul><ul><li>To improve shear strength and permeability requirement. </li></ul><ul><li>The combination if found effective can solve twin problem of industrial waste disposal as well as environmental degradation. </li></ul>
  10. 10. Cont… <ul><li>Series of Geotechnical investigation carried on mix containing fly ash and WRP with admixture (small quantity). </li></ul><ul><li>Suitable section of ash pond recommended. </li></ul><ul><li>Ash pond is functioning satisfactorily since 2001. </li></ul>
  11. 11. Lab. investigation and test results <ul><li>Sieve Analysis and Classification (IS:1498) </li></ul><ul><li>WRP : SP </li></ul><ul><li>Fly Ash: ML </li></ul><ul><li>Clay Soil :CI </li></ul>
  12. 12. Table-1: Trial Mix 50:50 M4 40:60 M3 30:70 M2 Flyash is in terms of dry weight of WRP 20:80 M1 Remark Flyash:WRP Mix
  13. 13. Table:2 WRP and Fly Ash Mixes M2, M3 : Unconsolidated untrained trained test Falling Head permeably test Permeability requirement 10 -7 cm/sec. Flyash on higher side and slushy due to high moisture content - - 17.20 16.09 M4 Stable 1.75x10 -5 25 85 15.60 16.66 M3 Stable 1.78x10 -5 30 60 14.40 17.84 M2 Flyash on lower side - - - 14.00 18.64 M1 Remarks K (cm/sec.) Ø (°) C (kPa) OMC(%) MDD(kN/m3) Mix
  14. 14. Table 3 : WRP Fly ash and cement mixture *Cement used as dry weight of WRP and fly ash (mix M3) ** confirm permeability requirement and posses considerable shear strength 2.38x10-7 30 120 7 M3 C2** 3.30x10-7 33 100 5 M3 C2** MDD and OMC value for the mixes consider same as M3 2.39 x10-6 36 25 3 M3 C1 Ø (°) C(kPa) Remakrs K(cm/sec.) MDD –OMC Cement*(%) Mix
  15. 15. Cont. <ul><li>For mixes M3C1, M3C2, M3C3 : </li></ul><ul><li>a) Failure strength in the range of 6- </li></ul><ul><li>8% </li></ul><ul><li>b) Exhibit brittle behaviour </li></ul><ul><li>c) Proper mixing, if not done at the site. Chances of granulation formation increases, making it more vulnerable to internal erosion. </li></ul>
  16. 16. Cont. <ul><li>Cost of huge quantity of cement required may effect the economic aspect of the project. </li></ul><ul><li>The cement stabilised mix may lead to formation of interconnected cracks with in the dyke. </li></ul>
  17. 17. Table 4: WRP, Fly ash and clay mixture *Clay is taken as dry weight of WRP only ** Confirms permeability requirement 2.04x10-7 16.40 18.04 15 M2C5** 2.36x10-7 15.80 17.82 10 M2C4** K(cm/sec.) OMC (%) MDD (kN/m3) Clay (%)* Mix
  18. 18. Table :5 WRP, fly ash and Clay mixture ** confirm permeability requirement and posses considerable shear strength 25 30 30 80 M2C5 ** 29 25 35 60 M2 C4** Ø (°) C(kPa) Ø (°) C(kPa) Saturation MDD-OMC Shear strength parameters Mix
  19. 19. Contd. <ul><li>Clay Stabilizes Mix M2C4 and M2C5 </li></ul><ul><li>Specimen exhibited ductile behavior </li></ul><ul><li>Range of failure strain 12 to 14% </li></ul><ul><li>Clay stabilized mix preferred over cement stabilized mix </li></ul><ul><li>Mix M2C4 finally selected for design of dyke section (considering economy and maximum utilization of waste) </li></ul><ul><li>Two sections of ash pond dyke were suggested. </li></ul>
  20. 20. contd. <ul><li>Major portion of dyke section consists of mixture of WRP, Fly Ash and Clay. </li></ul><ul><li>Right portion on the upstream side consists of local soil, consisting of gravel, sand and silt. </li></ul><ul><li>The local soil is to be borrowed from within the ash pond itself thus making the construction economical viable and also saving construction time and creating an additional storage capacity in the ash pond. </li></ul>
  21. 21. Contd. <ul><li>Suitable side slopes for downstream and up stream as indicated in section were arrived at based on slope stability analysis (Bishop’s simplified method). </li></ul><ul><li>Horizontal sand filter and a rock toe were provided for internal drainage. </li></ul><ul><li>The down stream slope were protected against gully formation due to slope water with riprap placed over a bed of gravel or by maintaining grass turfing. </li></ul><ul><li>Suitable free board was also provided. </li></ul><ul><li>The dyke was constructed like a rolled fill dam with proper quality control measure. </li></ul>
  22. 22. Conclusion <ul><li>Two industrial waste WRP and Fly Ash were used as fill material for the construction of Ash Pond Dyke. </li></ul><ul><li>Proposed solution and methodologies adopted were found to be techno-economically viable at the site. </li></ul><ul><li>It helped in saving the construction time, saving natural resources (and also in creating addition storage capacity by use of local soil) </li></ul><ul><li>The Ash Pond Dyke constructed is functioning well since 2001. </li></ul>
  23. 23. <ul><li>Thank You…………….. </li></ul>