CONSTRUCTION OF AN ASH POND WITH WRP, FLY CONSTRUCTION OF AN ASH POND WITH WRP, FLY

ASH AND LOCALLY AVAILABLE SOIL – ASH AND LOCALLY AVAILABLE SOIL – A Case Study A Case Study

by by 1. A.K.Choudhary, 2. J.N.Jha and 3. B.P.Verma1. A.K.Choudhary, 2. J.N.Jha and 3. B.P.Verma

1. Lecturer, Deptt. of Civil Engg., 1. Lecturer, Deptt. of Civil Engg., NIT, Jamshedpur NIT, Jamshedpur

2. Professor, Deptt. of Civil Engg., Guru Nanak 2. Professor, Deptt. of Civil Engg., Guru Nanak Dev Engineering College, LudhianaDev Engineering College, Ludhiana

3. Director, Sangvi Innovative Acad Indore, MP3. Director, Sangvi Innovative Acad Indore, MP

IndexIndex

IntroductionIntroduction MethodologyMethodology - Present problem- Present problem - Possible Solution - Possible Solution Laboratory investigation and test resultsLaboratory investigation and test results Section of the Ash Pond DykeSection of the Ash Pond Dyke ConclusionsConclusions AcknowledgementAcknowledgement ReferencesReferences

IntroductionIntroduction

Development of national linked with Development of national linked with industrial growthindustrial growth

Quantity of waste generated Quantity of waste generated increases with industrialization increases with industrialization causing causing

a) Disposal problema) Disposal problem

b) Environmental degradation b) Environmental degradation

Cont….Cont….

In India In India

a) 75% energy supply is from coal a) 75% energy supply is from coal based thermal power plant (TPP)based thermal power plant (TPP)

b) 90 thermal power plants produces b) 90 thermal power plants produces 100 million tonne of fly ash 100 million tonne of fly ash

c) Disposal of fly ash (TPP) is by use c) Disposal of fly ash (TPP) is by use of ash pondof ash pond

Cont.Cont.

Problems associated with Ash Pond Problems associated with Ash Pond constructionconstructiona) Require huge quantity of soila) Require huge quantity of soilb) If good quality of soil not available b) If good quality of soil not available nearby site, cost of construction nearby site, cost of construction become too high/prohibitive also.become too high/prohibitive also.c) No well defined design c) No well defined design procedure/codal provision exist for procedure/codal provision exist for ash pond construction. ash pond construction.

Methodology (Present Problem)Methodology (Present Problem)

Construction of an ash pond dyke for Construction of an ash pond dyke for a thermal power station (Tata Power a thermal power station (Tata Power -427.5 MW, Jamshedpur, Jharkhand)-427.5 MW, Jamshedpur, Jharkhand)

Proposal for ash pond dyke:Proposal for ash pond dyke:Construction of containment dyke Construction of containment dyke with impervious core overlain by with impervious core overlain by relatively pervious casing on U/S and relatively pervious casing on U/S and D/S side, with imported soil wherever D/S side, with imported soil wherever necessary.necessary.

Cont…Cont…

Good quality soil not available locally.Good quality soil not available locally. Huge transportation cost of borrow Huge transportation cost of borrow

material required thus increasing cost of material required thus increasing cost of constructionconstruction

How to reduce transportation cost. Use of How to reduce transportation cost. Use of locally available industrial waste : Blast locally available industrial waste : Blast Furnace slag coming out of the Tata Steel Furnace slag coming out of the Tata Steel (Waste recycled product-WRP)(Waste recycled product-WRP)

Cont.Cont.

WRP : Size Range:Sand and GravelWRP : Size Range:Sand and Gravel Fly Ash: Size : Silt ParticleFly Ash: Size : Silt Particle Waste material : Non plastic and Waste material : Non plastic and

highly permeable highly permeable Difficult to meet slope stability and Difficult to meet slope stability and

permeability requirement.permeability requirement. For better gradation require close For better gradation require close

packing of grains (Compacted mass packing of grains (Compacted mass of dyke). of dyke).

Methodology (Possible solution) Methodology (Possible solution)

Fly ash and WRP if mixed with some Fly ash and WRP if mixed with some admixture (Cement/Clay) : admixture (Cement/Clay) :

To improve shear strength and To improve shear strength and permeability requirement.permeability requirement.

The combination if found effective The combination if found effective can solve twin problem of industrial can solve twin problem of industrial waste disposal as well as waste disposal as well as environmental degradation.environmental degradation.

Cont…Cont…

Series of Geotechnical investigation Series of Geotechnical investigation carried on mix containing fly ash and carried on mix containing fly ash and WRP with admixture (small WRP with admixture (small quantity). quantity).

Suitable section of ash pond Suitable section of ash pond recommended.recommended.

Ash pond is functioning satisfactorily Ash pond is functioning satisfactorily since 2001.since 2001.

Lab. investigation and test resultsLab. investigation and test results

Sieve Analysis and Classification Sieve Analysis and Classification (IS:1498)(IS:1498)

WRP : SPWRP : SP Fly Ash: MLFly Ash: ML Clay Soil :CIClay Soil :CI

Table-1: Trial MixTable-1: Trial Mix

MixMix Flyash:WRPFlyash:WRP RemarkRemark

M1M1 20:8020:80 Flyash is in Flyash is in terms of dry terms of dry weight of WRPweight of WRPM2M2 30:7030:70

M3M3 40:6040:60

M4M4 50:5050:50

Table:2 WRP and Fly Ash MixesTable:2 WRP and Fly Ash MixesMix Mix MDD(kN/m3)MDD(kN/m3) OMC(%)OMC(%) C (kPa)C (kPa) Ø (°)Ø (°) K (cm/sec.)K (cm/sec.) RemarksRemarks

M1M1 18.6418.64 14.0014.00 -- -- -- Flyash on lower side Flyash on lower side

M2M2 17.8417.84 14.4014.40 6060 3030 1.78x101.78x10-5-5 Stable Stable

M3M3 16.6616.66 15.6015.60 8585 2525 1.75x101.75x10-5-5 StableStable

M4M4 16.0916.09 17.2017.20 -- -- Flyash on higher side Flyash on higher side and slushy due to and slushy due to high moisture high moisture content content

M2, M3 : Unconsolidated untrained trained test M2, M3 : Unconsolidated untrained trained test Falling Head permeably testFalling Head permeably test Permeability requirement 10Permeability requirement 10-7-7 cm/sec. cm/sec.

Table 3 : WRP Fly ash and cement Table 3 : WRP Fly ash and cement mixture mixture

MixMix Cement*(%)Cement*(%) MDD –OMCMDD –OMC K(cm/sec.) K(cm/sec.) Remakrs Remakrs

C(kPa)C(kPa) Ø (°)Ø (°)

M3 C1M3 C1 33 2525 3636 2.39 x10-62.39 x10-6 MDD and MDD and OMC value OMC value for the for the mixes mixes consider consider same as M3same as M3

M3 C2**M3 C2** 55 100100 3333 3.30x10-73.30x10-7

M3 C2**M3 C2** 77 120120 3030 2.38x10-72.38x10-7

*Cement used as dry weight of WRP and fly ash (mix M3)*Cement used as dry weight of WRP and fly ash (mix M3)** confirm permeability requirement and posses considerable shear ** confirm permeability requirement and posses considerable shear strengthstrength

Cont.Cont.

For mixes M3C1, M3C2, M3C3 : For mixes M3C1, M3C2, M3C3 :

a) Failure strength in the range of 6- a) Failure strength in the range of 6-

8% 8%

b) Exhibit brittle behaviour b) Exhibit brittle behaviour

c) Proper mixing, if not done at the c) Proper mixing, if not done at the site. Chances of granulation site. Chances of granulation formation increases, making it more formation increases, making it more vulnerable to internal erosion. vulnerable to internal erosion.

Cont.Cont.

Cost of huge quantity of cement Cost of huge quantity of cement required may effect the economic required may effect the economic aspect of the project. aspect of the project.

The cement stabilised mix may lead The cement stabilised mix may lead to formation of interconnected cracks to formation of interconnected cracks with in the dyke. with in the dyke.

Table 4: WRP, Fly ash and clay Table 4: WRP, Fly ash and clay mixture mixture

MixMix Clay Clay (%)*(%)*

MDD MDD (kN/m3)(kN/m3)

OMC OMC (%)(%)

K(cm/K(cm/sec.)sec.)

M2C4**M2C4** 1010 17.8217.82 15.8015.80 2.36x12.36x10-70-7

M2C5**M2C5** 1515 18.0418.04 16.4016.40 2.04x12.04x10-70-7

*Clay is taken as dry weight of WRP only *Clay is taken as dry weight of WRP only ** Confirms permeability requirement ** Confirms permeability requirement

Table :5 WRP, fly ash and Clay Table :5 WRP, fly ash and Clay mixture mixture

MixMix Shear strength parameters Shear strength parameters

MDD-OMCMDD-OMC SaturationSaturation

C(kPa)C(kPa) Ø (°)Ø (°) C(kPa)C(kPa) Ø (°)Ø (°)

M2 M2 C4**C4**

6060 3535 2525 2929

M2C5 M2C5 ****

8080 3030 3030 2525

** confirm permeability requirement and posses considerable shear ** confirm permeability requirement and posses considerable shear strengthstrength

Contd.Contd.

Clay Stabilizes Mix M2C4 and M2C5Clay Stabilizes Mix M2C4 and M2C5

Specimen exhibited ductile behaviorSpecimen exhibited ductile behavior Range of failure strain 12 to 14%Range of failure strain 12 to 14% Clay stabilized mix preferred over cement Clay stabilized mix preferred over cement

stabilized mixstabilized mix Mix M2C4 finally selected for design of Mix M2C4 finally selected for design of

dyke section (considering economy and dyke section (considering economy and maximum utilization of waste)maximum utilization of waste)

Two sections of ash pond dyke were Two sections of ash pond dyke were suggested. suggested.

contd.contd.

Major portion of dyke section consists of Major portion of dyke section consists of mixture of WRP, Fly Ash and Clay.mixture of WRP, Fly Ash and Clay.

Right portion on the upstream side Right portion on the upstream side consists of local soil, consisting of gravel, consists of local soil, consisting of gravel, sand and silt. sand and silt.

The local soil is to be borrowed from within The local soil is to be borrowed from within the ash pond itself thus making the the ash pond itself thus making the construction economical viable and also construction economical viable and also saving construction time and creating an saving construction time and creating an additional storage capacity in the ash additional storage capacity in the ash pond. pond.

Contd.Contd. Suitable side slopes for downstream and up Suitable side slopes for downstream and up

stream as indicated in section were arrived at stream as indicated in section were arrived at based on slope stability analysis (Bishop’s based on slope stability analysis (Bishop’s simplified method).simplified method).

Horizontal sand filter and a rock toe were Horizontal sand filter and a rock toe were provided for internal drainage.provided for internal drainage.

The down stream slope were protected against The down stream slope were protected against gully formation due to slope water with riprap gully formation due to slope water with riprap placed over a bed of gravel or by maintaining placed over a bed of gravel or by maintaining grass turfing.grass turfing.

Suitable free board was also provided. Suitable free board was also provided. The dyke was constructed like a rolled fill dam The dyke was constructed like a rolled fill dam

with proper quality control measure. with proper quality control measure.

ConclusionConclusion Two industrial waste WRP and Fly Ash Two industrial waste WRP and Fly Ash

were used as fill material for the were used as fill material for the construction of Ash Pond Dyke. construction of Ash Pond Dyke.

Proposed solution and methodologies Proposed solution and methodologies adopted were found to be techno-adopted were found to be techno-economically viable at the site.economically viable at the site.

It helped in saving the construction time, It helped in saving the construction time, saving natural resources (and also in saving natural resources (and also in creating addition storage capacity by use creating addition storage capacity by use of local soil)of local soil)

The Ash Pond Dyke constructed is The Ash Pond Dyke constructed is functioning well since 2001.functioning well since 2001.

Thank You……………..Thank You……………..