Limited Environment Study of a Thermal Power

Project – A Case Study

Satyendra Mittal, A.A. Kazimi, Ashish Pippal, Ashwini Ahiri, Akansha, and S.Singh

Abstract—Thermal power stations are generally believed to create some adverse impact on environment, though a large amount

of power generation is done through such projects. In India, for every new thermal power project or for augmentation of capacity of any existing project, a detailed environmental impact study is done in terms of Leachability, Hydrogeology, ground water etc. The present paper discusses a case study of one such thermal power project in India, quite recently. This paper discusses in brief the impact of flyash on ground water, rainwater harvesting system, hydrogeology of area etc. The mitigation measures of contamination of ground water are also discussed.

Keywords—Flyash dykes, hydrogeology, leaching, stability

measures.

I. INTRODUCTION

N India, power supply is met through Nuclear, Thermal and

Hydro power stations. There are non-conventional energy

sources also eg. Solar, geothermal, wind and small hydro

power stations, but their contribution is meagre. Sixty five

thermal power stations of India attribute a major share of

power demand in the country as India has a big reserve of

coal. Many such power stations are in expansion phase. But

before any new unit is added, an environmental study is

essential to get a feedback of existing units. Present paper

discusses limited parameters out of the full detailed report

prepared by authors for Kasimpur Thermal Power Station of

North India.

II. STUDIES UNDERTAKEN

The studies included leaching stability of existing ash

dykes, Hydrogeological study, geotechnical study, fish

culture, socio-economic impact etc. But this paper discusses

only the limited study of project area which includes stability

study of dyke, Hydrogeological study of site, testing of water

quality and flyash of site due to limitation of space.

Satyendra Mittal, Associate Professor (Geotechnical Engg.) l Investigator,

Civil Engineering Deptt., I.I.T., Roorkee-247667, India Ph: 01332-285837(O),

274565®, 09412074237 & 09760014237 (Mob), Email:

satyendramittal@gmail.com

A.A. Kazimi, Associate Professor (Environmental Engg.) & Co-

Investigator

Ashish Pippal, Senior Design Engineer, Maccaferri Environmental

Solutions, New Delhi

Ashwini Ahiri , PG Student, Civil Engg. Deptt., IIT Roorkee, India

Akansha, Research Associate, Civil Engg. Deptt., IIT Roorkee, India

S.Singh, Asstt. Professor, KLDAV Degree College, Roorkee, India

III. GEOTECHNICAL STUDY

The stability study analysis was conducted by Geo-5

software. The soil parameters thus obtained were as follows:

c = 0, = 30.5º, = 11.5kN/m3

For stability analysis of dyke, design parameters adopted

were:

Seismic parameters, h = 0.1, v = 0.05, Surcharge traffic

load = 22 kPa

The FOS for naturally existing dyke was obtained as 0.6

Since the FOS was coming less than 1.0 for naturally

occurring dyke when subjected to traffic loads, it has been

suggested to provide gabion wall at the toe of dyke.

Fig.1 Stability study of existing ash dyke

The FOS with gabion wall was computed as 1.4 m in

seismic conditions. The stability analysis has been shown in

Fig. 1 (for naturally occurring dyke) and Fig. 2 (for gabion

supported wall). The study shows that gabion (duly filled with

boulders) wall may provide passive support to existing dyke.

Fig.2 Stability study of existing ash dyke (with gabion wall)

I

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IV. HYDROGEOLOGY OF SITE

After careful study of lithological logs of borehole and

perusal of fence diagram and various sub-surface geological

cross - section, three tier aquifer systems had been demarcated

in the area.

Perusal of these data reveals that maximum discharge of

3000 lpm can be obtained from the moderately deep tube

wells tapping the shallow aquifer group, at a reasonable

drawdown of 5-10metres. Permeability (K) of aquifer material

ranges from 16 to 34.2m/day. Transmissibility (T) ranges from

250 to 1300 m2/day. Storativity (S) had been computed to the

order of 6.02×10-2 to 7.7×10-4, showing semi confined to

confine state of aquifers.

The shallow cavity borings of 30 to 40 meters deep area

were capable of yielding 8 to 10 lps. The results of chemical

analysis conducted on water samples from site are given in

Table I below.

TABLE I

CHEMICAL ANALYSIS RESULTS OF GROUND WATER AND SURFACE WATER SAMPLES COLLECTED FROM THE PROJECT AREA

Sampling Sites pH EC

(µS/cm)

TDS

(mg/L)

DO

(mg/L)

Flouride

(mg/L) Fe(mg/l) Mn(mg/l) Pb(mg/l) Zn(mg/l) Ni(mg/l) Cr(mg/l)

H.P, main sub station new

colony 7.13 760 486 - 0.45 0.253 0.042 0.122 0.04 0.104 N.D.

TW,main sub station new

colony 7.35 769 492 - 0.13 0.179 0.074 0.124 0.037 0.044 N.D.

Tube well in the Hospital 7.18 581 372 - 0.24 0.894 0.078 0.116 0.049 0.039 N.D.

HP in Dayanand shishu

mandir 7.56 375 240 - 0.21 0.309 0.0472 0.178 0.063 0.0516 N.D.

T.W number 10ER New

colony 7.67 517 331 - 0.16 0.579 0.097 0.441 0.062 0.053 N.D.

CISF Colony TW no. 9 7.68 715 458 - 0.14 0.047 0.197 0.222 0.0136 0.044 N.D.

HP Samudyaik kendra

Jawan 7.01 701 449 - 0.56 0.749 0.116 0.258 0.218 0.0606 N.D.

Surface water, Up stream

UGC 7.2 193 124 7.56 0.37 1.548 0.113 0.26 0.093 0.059 N.D.

Surface water

Downstream UGC 7.17 195 125 7.49 0.67 0.321 0.047 0.383 0.034 0.041 N.D.

HP near Downstream

UGC 7.18 232 148 - 0.78 0.766 0.117 0.275 0.09 0.053 N.D.

TW80Inside existing Po

wer house 7.45 489 313 - 0.35 0.148 0.053 0.306 0.093 0.05 N.D.

cavity well Inside plant

premises 7.34 230 147 - 0.78 0.92 0.071 0.316 0.075 0.062 N.D.

HP at the gate of A power

house 7.23 807 516 - 0.13 0.448 0.084 0.364 0.026 0.0768 N.D.

TW in old guest house 7.19 412 264 - 0.15 0.445 0.121 0.393 0.051 0.057 N.D.

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The Table II below explains positions from where water samples were collected.

TABLE II

THE COORDINATES* OF 14 POINTS OF STUDY

Sl. No. Place Latitude Longitude

H.P, main substation new colony 28*00.685" 78*07.524"

2. TW,main substation new colony 28*00.657" 78*07.524"

3. Tube well in the Hospital 28*00.514" 78*07.642"

4. HP in Dayanand shishu mandir 28*00.394" 78*07.443"

5. T.W number 10ER New colony 28*00.671" 78*07.334"

6. CISF Colony TW no. 9 28*01.109" 78*07.481"

7. HP Samudyaik Kendra Jawan 28*01.100" 78*06.703"

8. Surface water ,Upstream UGC 28*01.279" 78*07.850"

9. Surface water Downstream UGC 28*00.241" 78*08.492"

10. HP near Downstream UGC - -

11. TW80Inside existing Power house 28*01.231‖ ―78*07.756‖

12. cavity well Inside plant premises 28*01.361‖ 78*07.694‖

13 HP at the gate of A power house 28*00.200‖ 78*09.184‖

14. TW in old guest house 28*00.538‖ 78*08.096‖

Note: Latitude and Longitude of Sl. No.10 had not been measured.

*As observed in GPS during field survey

V. LEACHABILITY STUDY

For Leachability study at this site, the flyash

characterisation was done on collected flyash from site. This

flyash was tested for the presence of heavy metals which

could mix with rain water and pollute ground water.

The results of the same are as follows (Table III).

TABLE III

RESULTS OF TESTING OF FLYASH

The above results indicate that the Iron and Lead have more

concentration i.e. more than permissible range (the permissible

range are given in Table IV.

But it is to be noted here that Iron content may not harm,

but lead quantity was more than permissible. It could further

harm the ground water quality. Hence a mitigation plan has

been suggested by authors.

VI. MITIGATION OF GROUND WATER CONTAMINATION

The ground water contamination can be stopped by

providing HDPE/LDPE film below the existing dykes. This

can be achieved by gradually removing the ash for 8 m depth

(to reach upto natural ground) and then laying the film there.

But this process cannot be achieved in one step. Hence it is

suggested to divide the entire ash area in some sectors (say 10

or 12) as shown below (Fig. 3 & 4) and then removing the ash

from one sector first (shown hatched area) and making it

empty. Thereafter HDPE/LDPE film may be laid at that sector

followed by further filling of ash. After treating area of first

sector, the other sectors can also be treated in this manner.

Plan

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TABLE IV

INDIAN STANDARD SPECIFICATIONS FOR DRINKING WATER (AS PER IS:

10500)

Section 1-1 Fig.3 Suggested Plan for Mitigation of Ground Water Contamination

Fig.4 Refill of ash after laying film

VII. CONCLUSIONS

Present paper discusses only a limited data out of a detailed

report prepared by authors for a thermal power project in north

India. The mitigation plan of ground water contamination is a

novel design which may act as a guideline for future research.

The properties of flyash mentioned in paper shows general

trend of properties of Indian Flyash.

REFERENCE

[1] Geotechnical, Leachability, stability and hydro-geological study for 1

x 660 mW proposed unit at HTPS, Harduaganj, U.P. – Report

prepared by IIT Roorkee, India, 2014.

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