CMPDI Prevention of soil erosion
CHAPTER - I Background
1.0 Purpose CCL had submitted a proposal to concern department for the release of 6.59 Ha . of forest land for Jharkhand opencast project to MoEF, G o I through DFO, East D ivision, Hazaribagh. Stage – I clearance ha s been accorded by MoEF vide letter N o. 8 - 52 /2003 - FC - (vol - I) dated 2 2 . 03 . 10 of Sr. Assistant Inspector General of forest MoEF, Govt. of India with certain conditions. As per clause no. 3 (I, II, III, IV & V) of the said letter the user agency has to comply with; - Preparation of a scheme for the proper mitigation measures to minimize soil erosion and choking of stream s to be implemented; Planting of adequate draught hardy plant species and sowing of seeds to arrest soil erosion; The area shall be reclaimed keeping in view of the international practice or stabilizing the dump grading/benching , so tha t the angle of repose (normally < than 28 0 at any given point) is maintained; Top soil management plan should be strictly adhered to ; Stu dy on soil erosion/soil flow from the overburden area with help of GIS in consultation with the F orest D epartment.
Keeping in view of the above, CCL has requested CMPDI (HQ) to prepare the necessary scheme for fulfillment of the above condition , vide the ir letter no. CGM (P&P) 10 / 2495 – 83 dated 1 1 . 12 .2010 . Accordingly, CMPDI (HQ) has taken up job with job no.0903 10 155 .
Jharkhand OCP(1.0 Mtpa) 1 Job no. -- 0903 10155 CMPDI Prevention of soil erosion
1.1 Consultation with forest officials A formal meeting between CCL and PCCF cum executive director of F orest D epartment, Jharkhand has been held on 7.12.09 in the office of later to discuss the compliance the condition lay down by Sr. Assistance Inspector General of Forest vide the ir letter no. 8 - 52 /2003 - FC - (vol - I) dated 2 2.03. 10 of Sr. Assistant Inspector General of forest MoEF, Govt. of India with certain conditions regarding the release of 6.59 h a. of forest land for Jharkhand Opencast Project. On the basis of above meeting , forest department has given guideline s for the fulfillment of the condition s, set by Assistan t Inspector General of Forest.
1.2 Scope of Work : - Study of soil erosion from the leasehold area including overburden area with the help of GIS and preparation of a detailed scheme with sketches and drawings along with cost estimate to minimize/prevent the water pollution , soil erosion arises due to surface runoff , and choking of streams in the mine lease area of the Jharkhand OCP .
1. 3. Objective of the scheme - The objectives of this project are the p revention of Chutua Nala / Kedla nala and their tributaries from being choked along with protection of the leasehold areas from being eroded due to high velocity of surface run - off, reduction of the fertility due to soil erosion owing to the on going Jharkhand OCP for the benefit to the local habitants, animals and plants to get good quality of land and clean water in sufficient quantity. It will also help in enhanc ing the ecological balance of the area and will take care of the natural eco - system.
1.4 Project History : - Jharkhand Opencast Project is a n existing mine producin g coal at different capacity from 0.6 to 0.9 Mty during 1999 to 2010.
Jharkhand OCP(1.0 Mtpa) 2 Job no. -- 0903 10155 CMPDI Prevention of soil erosion
Balance Coal and OB in the Mine till the end of March 2010
Coal(MT) OB(Mcum) SR(Cum/t) Reserves as per Project Report 21.50 47.00 2.19 Mined out till 31/3/2010 in the 6 .47 16.38 2.53 PR boundary Balance within the PR boundary 15.03 30.62 * 2.04
This OB volume excludes the amount of OB to be rehandle d which may adversely affect the strip p ing ratio.
1.5 Purpose of Report The purpose of this report is to apply for grant of enviro nmental clearance for 6.59 ha. forest land in Jharkhand OCP from Ministry of Environment & Forests, Govt. of India as per provisions of EIA Notification, 2006. It is envisaged that Jharkhand OCP will run as per approved PR , producing coal at normative and highest achievable capaci ty of 1. 00 M tpa & 1. 2 0 M tpa respectively.
Jharkhand OCP(1.0 Mtpa) 3 Job no. -- 0903 10155 CMPDI Prevention of soil erosion
CHAPTER - II
Project Profile
2.0 General A report for Jharkhand Opencast Project , CCL, a subsidiary company of CIL, has been prepared for target capacity of 1. 0 0 Mt pa by RI - III,CMPDI. Present balance mineable reserve , 15.03 Mt of coal of “ W - IV ” g rade from Lower Seam (Seam III & IV) is required to be extracted in balance 2 5 years of mining life span with the help of shovel - dumper combination . Coal from this mine is being transported and despatched through road to near by Kedla was hery, NR Siding, TTPS Lalpania & local sale through road as well.
2.1 Location: - Jharkhand OCP project is located in west Bokaro coalfield ltd of CCL under the Hazaribagh area in Jharkhand. It is covered by the Survey of India toposheet no. 73 - E/9(RF 1 :50000). Ranchi, company HQ and capital of State – 90 KM away .
2.1 Surface Communication : - 2.1.1 Road - Chutua nala / Kedla nala , flowing from west to east is located in the eastern part of the quarry . The project is about 20 Km North - East of Ranchi t hrough Ranchi - Hazaribagh NH - 33. 2.1.2 Railways - Nearest railway station is Dania Railway station at a distance of 8 Km . from the project . This railway station is situated on Gomoh – Barkakna loop line of Eastern Rly. 2.1.3 Airways - Nearest Air service is available from Ranchi , that is 90 Km. away from the project. 2.1.4 Distance of important place a) G.M.office, Kathara 15 km. b) Ranchi - -- 90 km. (Takes 3.0 hr. by road)
Jharkhand OCP(1.0 Mtpa) 4 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
c) Hazaribagh -- 90 km ( 2 hr. by road)
2. 1.5 Topography : - The general topography of the area is undulating broken by small hill Ground elevation varies between 324m to 382m above MSL. The topography in the south and North - west is hil ly and rugged terrain. Kedla nala flow through the project area and join Chutua nala at north east corner outside the project area. Chutua nala flowing northen side of the project. Bokaro nala flowing from west to east is located on southern side of the p roject.
2.3 Climate Tropical climate prevails in this region having three main seasons : winter, summer and rainy season, which pass through extreme conditions. Each season spreads over three months : April to June is summer season, July to September i s rainy season having generally 73 rainy days and average rainfall is 1200 mm and December to February is winter season. Summer days are very dry, scorching heat and dusty day, temperature soar to about 47 0 C while winter nights are very chilly cold and tem perature goes down to as below as 3 0 C and rainy season have heavy rain fall. Prominent wind direction in summer is from north - south,
2.4 Drainage Pattern : - The drainage of the upper side block is controlled by the Chutua nala flowing along the Nort hen side of the block boundary. The Bokaro nala flows south of the block property and control the drainage system of lower part of the block. This nala discharges their load ultimately into the Damodar river.
2.5 RESERVE : The quarry boundary has been ma ximized to the extent possible and mining upto Seam VI has been considered. The extractable reserve has been estimated as 15.03 MT of coal. The life of the mine has been estimated as 15 years.
Jharkhand OCP(1.0 Mtpa) 5 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
Present statuus of mine: It has been worked extensively in up per Seam only(Seam V& Seam VA).Lower Seam (Seam III & IV) proposed for coal extraction in the PR have been left in most of the mine take area. Overburden have been dumped internally without extracting the lowermost seam. Operational plan proposes identific ation of overburden dumped over workable lower seams and rehandling of OB dump internally in decoaled area along with p roper advancement of upper benches to synchronize the extraction of Coal from lower benches so that enough void is created for internal d ump.
Seam wise Mineable Reserve
OB(Mcum) Coal(MT) Parting Between V & IV 0. 39 Seam IV 0.207 Parting Between IV & III 0.94 Seam III 0.793 Total 1.33 1 .00 SR(cum/T) 1.33
O verburden & stripping ratio A total o f 15.03 million Cum of overburden at an average stripping ratio of 2.04 m3/te. The break - up of the seam wise coal reserves and total volume of OB/partings are given below.
2.6 Mining Technology Coal deposits in different sector s of Jharkhand geological block in different seams are potential seams for opencast mining, both qualitatively and quantitatively. Considering the geological and mining conditions of the opencast project, viz. occurrence of multiple seams, their thickness, intervening partings, gradient and hilly terrain, opencast mining with shovel - dumper combination has been proposed for this project. The coal and intervening partings will be mine d strip by strip with horizontal slices. The width of the working and non - working
Jharkhand OCP(1.0 Mtpa) 6 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
benches will be 40m and 25m respectively and maximum height of the benches will be 10m.
2. 7 MICRO - METEOROLOGICAL STATUS Climatological Condition 2.7.1 Weather - The climate i s sub tropical. Maximum precipitation takes place during the monsoon season (June to Sept.). The average annual rainfall is about 1200 mm and 80% rainfall occurs during monsoon season. The average monthly rainfall during the non - monsoon period is 20 mm (ap pox,). During summer April to June the days are the scorching hot with dusty winds but nights are generally pleasant. In winter season the days are generally pleasant but nights are severing cold. The maximum summer temperature and minimum winter temperat ure generally varies between 46o C and 3oC. 2.7.2 Temperature : The study season, summer are very hot from March to June. The maximum and minimum temperature during Summer vary from 17 deg to C to 42 deg C. The Summer nights are pleasant. The Winter mont hs from November to February are cold and minimum temperature goes down to 30C.
2.7.3 Rainfall : The rainy season is generally start from June to September. The average total rainfall during monsoon period is 950 mm and total rainfall during the who le year is about 1200 mm. Total rainfall during study period is 31.5mm
2.7.4 Humidity The daily average relative humidity values study period are in the range of 14% to 91 %. The seasonal average humidity value is observed to be 52.7 %.
2.7.5 Wind Velo city and Direction :
Jharkhand OCP(1.0 Mtpa) 7 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
Generally, light to moderate winds prevail through out the season. Winds were light and moderate particularly during the morning hours. During the afternoon hours the winds were stronger. Wind speed readings are ranging from <1 km/hr. to 14.2 km/hr. The seasonal average wind speed is observed to be 5.4 km/hr. The wind patterns of the season are presented below:
The analysis of wind pattern during the season shows that the predominant wind direction is from North - West with wind frequen cy of 14.04%. It is followed by South - West with 10.47% frequency. The other observed directions are South (6.17%), South - East (5.67%), North (5.13%), North - East (4.27%), etc. The calm conditions prevails 20.72%. The wind speeds of 1 - 5 km/hr and 5 - 11 km/h r were recorded for 42.31 % and 34.57% of the total time respectively.
2.7.6 Cloudiness The cloud cover is expressed as OKTAS and denotes total area of sky covered by clouds is in the units of 1/8 parts. Generally clear sky was predominant during study p eriod. Max. cloud cover is visualized as 1 to 6 Oktas.
Jharkhand OCP(1.0 Mtpa) 8 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
CHAPTER – III Soil Erosion
3 .0 - General When the top layer of soil wears away and its worn part is carried from one place to another by certain external agency, this phenomen on is called soil erosion. A t the same time, due to action of some rain and wind, disintegration of rocks is continuous process and in natural process it forms the soil . This process is continuous so that there is natural balance between the erosion and formation of soil. Due to action of rain and wind, some portion of soil gets eroded and transported naturally. Soil erosion has affected land all over the world from small residential landscaped properties to large forests and deserts. Soil erosion is described as soil particles being shifted around due to the devastating impact of Rainfall, Wind and Ice melts. It is a natural process but in most cases, human activity speeds up the process. Following are the description of Soil Erosion caused by above agencies: -
3.0. 1 Rain Fall Erosion Our ancestors used to believe t hat water erodes the soil when it flows over the surface in the form of surface runoff. But , today this idea has been proved to be almost wrong. T he investigation has shown that most of the erosion done by water is due to the impact of the falling rain - dro ps. The erosion capacity of surface run - off is very small and it acts only as a partner. The water erosion process starts as soon as the rain starts. The two principal erosive agents that become active during the rain storm are: (a) Falling rain drops ; (b) Flowin g runoff ;
Jharkhand OCP(1.0 Mtpa) 9 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
a) Falling rain drops - When a rain drop strikes the soil surface, it breaks down the clods and the aggregates of the soil and thus, the soil particles are torn loose from their moorings in the soil mass. The energy of the falling water is appl ied from the above and is utilized in detaching the soil particles, while the energy of the surface runoff is applied parallel to the surface and is utilized in transporting the dislodged soil particles.
The erosion caused by rain storms is also known as Splash - Erosion - Process . Another important fact which we must mention here is that, the amount of erosion from hilly catchments is always more than that from flat catchments (provided all other conditions remain the same). This is, because, when a rain fa lls
Splash - Erosion over the flat area, the incoming splash balances the out going splash; while when the rain drops str ike the sloping land surfaces, a major proportion of the splash moves down. Hence, relatively larger quantities of soil is transported when catchments is sloping than the catchments is flatter. b) Flowing run - off - The fraction of the rainfall which doe s not infiltrate (soak into) the soil , will flow downhill under the action of gravity; it is then known as run - off or overland flow.
Jharkhand OCP(1.0 Mtpa) 10 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
If rain continues, the depth of water flow will eventually increase. Overland flow that is released in this way is likely to flow downhill more quickly and in greater quantities (i.e. possess more flow power as a result of its kinetic energy), and so may be able to begin transporting and even detaching soil partic les. Where it does so, the soil surface will be lowered slightl y. Lowered areas form preferential flow paths for subsequent flow, and these flow paths are in turn eroded further . Following chart s show infiltration capacity under different type of management. Tab le – 3.0.1(b)
Water infiltration under different types of management
3.0. 2 Wind Erosion - Soil erosion by wind may occur , wherever dry, sandy or dusty surfaces, inadequately protected by vegetation, are exposed to strong winds. Erosion involves the picking up and blowing away of loose fine grained material within the soil. Dama ge from wind erosion is of numerous types. The most serious and significant by far, however, is the change in soil texture caused by wind erosion. Finer soil fractions (silt, clay, and organic matter) are removed and carried away by the wind, leaving the c oarser fractions behind. This sorting action not only removes the most important material from the standpoint of productivity and water retention, but leaves a more sandy, and thus a more erodable soil than the original. Wind erosion mainly depends upon th e type, speed and duration of storm.
Jharkhand OCP(1.0 Mtpa) 11 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
3 .0.3 Ice erosion Snow and glacier melt occur only in areas which are sufficiently cold and temperature goes below freezing point. Typically snowmelt will be maximum in spring and glacier melt in the summ er, leading to pronounced flow in rivers affected by them. The most important factor in increasing the rate of melting of snow or glaciers is air temperature and the duration of sunlight. In high mountain regions, streams frequently rise on sunny days and fal l on cloudy days . Soil erosion due to ice melting is not applicable in this region because it is a tropical region and temperatures do not go down to freezing point.
3 . 1 Consequences of Soil erosion Damage from the soil erosion is of numerous type . H ow ever , the most serious and significant consequence s are mentioned below - 1) Water Pollution ; 2) Unbalanced water availability ; 3) Chocking of Streams ; 4) Change in soil texture ;
3.1. 1 Water pollution - Water is the most essential requirement after air for surviv al of any kind of life and needs more or less some fixed quantity of water. It holds the pivotal position in the total environment, so that its availability is in optimum quantity, it can protect all aspects of the environments and if availability is less or more than requirement then quality of all aspects of environments gets endangered. Water is made available by the nature in good quantity and quality in the form of rain water, under ground water and through river, Nala, ponds etc. This water gets affec ted due to disturbance in the nature by means of man’s activities associated with construction, mining activities, etc. Mainly two types of actions are responsible for complete or partial water pollution.
Jharkhand OCP(1.0 Mtpa) 12 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
a ) Mixing of foreign substance with natural wate r causing physical and chemical changes. b) Interception or diversion of water in complete or partial from any source.
The operation of mining and allied activities of this project will have impact on water quality through generation of waste water in the surrounding area in the ways discussed below. The source of such a polluted liquid effluent has their impact on water quality , and these are discussed elaborately and seperately in EMP report.
3.1. 2 Un availability of sufficient water - L ess the soil is covered with vegetation, mulches, crop residues, etc. more the soil is exposed to the impact of raindrops. When a raindrop hits bare soil, the energy of the velocity detaches individual soil particles from soil clods. These particles can clog s urface pores and form many thin, rather impermeable layers of sediment at the surface, referred to as surface crusts. They can range from a few millimeters to one cm or more; and they are usually made up of sandy or silty particles. These surface crusts hi nder the passage of rainwater into the ground reservoir and reduce the water holding capacity of the earth with the consequence that runoff increases. Soil erosion reduce s the capacity of the local ponds, wet land, stream/nala,etc. This increased the spee d of the surface runoff and creates the flood like situation any where in down stream side. Due to low infiltration rate, ground water reservoir does not get full y recharge d resulting in the shortage of quality water at this place. Thus create inappropriat e water availability in the region.
3 .1.3 Cho c king of Streams - Rainfall water which does not infiltrate into the soil starts to flow downhill under the action of gravity. Initially, run - off moves down the slope as a thin diffused film of water which has lost virtually all the kinetic energy which it possessed as falling rain. Thus, it moves only slowly, has a low flow power, and is generally incapable of detaching or transporting soil particles.
Jharkhand OCP(1.0 Mtpa) 13 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
If rain continues, the increasing depth of water will event ually increase. Overland flow that is released in this way is likely to flow downhill more quickly and in greater quantities (i.e. possess more flow power as a result of its kinetic energy), and so may be able to begin transporting and even detaching soil particles and pick up soil contaminants from such as: - a) Runoff from OB Dump – 47 mm 3 of O.B. materials would be dumped internally in the decoaled area after rehandlin g the dump already dumped on coal seam III which has been proposed to be extracted . OB material would consist of broken stones, shales, coal and finer particles. The surface run - off from the embankment would be polluted with suspended and dissolved Runoff from OB dump solids. These polluted run – off would
ultimately drain into Konar River . through small channel and will pollute its water and choke the stream if allowed to discharge in the streams untreated
Jharkhand OCP(1.0 Mtpa) 14 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
b) Run - off from Construction Site - During the construction phase of the project, large area of land would be dev egetated and degraded on account of site preparation for construction of roads, buildings etc. The runoff from these areas would carry large quantity of suspended solids, which can pollute and choke the natural drains, flowing through the area such as Chut ua nala/ Kedla nala only in the initial phase of construction.
C) Run - off from Coal Dump - The project has been so planned that coal dumps will not be created. But, if there may be situation when coal dumps would be unavoidable. So surface run – off from these dumps would be polluted with coal particles and other suspended particles which will finally pollute the Chutua nala/ Kedla nala , if unattende d .
D) Runoff from built up Areas - Surface runoff from built up areas i.e. building, roads, roof tops e tc. may not be highly polluted, but even then run – off may have high concentration of suspended solid i.e. sand, silt and coal particles. Above run - off, besides the soil particles, also carries the municipal garbage, petroleum , pesticides , fertilizers , pebbles, etc and discharge it in the next orde r stream, river and is transported well away from the point of origin and finally merge in sea. However, sediment may also be deposited within the rill or gully, or beyond the rill or gully’s and confines in a depositional fan, at locations where the grad ient slackens. Thus, it chokes the water ways. Here it may be stored for a variable period of time, possibly being reworked by tillage activity, until a subsequent erosion event of sufficient size to re - erode the stored sediment. It may then be re - deposite d further downstream.
3.1. 4 Change in Soil Texture - The most serious and significant affect of the soil erosion by far is the change in soil texture caused by wind/water erosion. Finer soil fractions (silt, clay, and organic matter) are removed and carri ed away by the wind, leaving the coarser fractions behind. This sorting action not only removes
Jharkhand OCP(1.0 Mtpa) 15 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
the most important material from the standpoint of productivity and water retention, but leaves a more sandy soil and thus a more erodible soil than the origina l. Successive removals eventually create such a soil condition wherein the plant growth is minimized and erodibility is greatly increased. Damage results both from the erosion and the consequent dust storms. Control becomes more and more difficult. In the extreme, the sands begin to drift and form unstable dunes which encroach on better surrounding lands. Throughout recorded history, huge agricultural areas have been ruined for further agricultural use in this manner . 3.2 Estimation of Soil Erosion Erosio n is a natural geomorphic process occurring continually over the earth’s surface and it largely depends on topography, vegetation, soil and climatic variables and, therefore, exhibits pronounced spatial variability due to catchments heterogeneity and clima tic variation Soil erosion is a three stage process: (1) Detachment, (2) Transport, and (3) Deposition of soil. Different energy source agents determine different types of erosion. There are four principal sources of energy: physical such as wind , wate r, gravity, chemical reactions and anthropogenic, such as tillage. Soil erosion begins with detachment, which is caused by break down of aggregates by raindrop impact, sheering or drag force of water and wind. Detached soil particles are transported by flo wing water (over - land flow and inter - flow) and wind, and deposited when the velocity of water or wind decreases by the effect of slope or ground cover. Three processes viz. dispersion, compaction and crusting, accelerate the natural rate of soil erosion. T hese processes decrease structural stability, reduce soil strength, exacerbate erodibility and accentuate susceptibility to transport ed by overland flow, interflow, wind or gravity. These processes are accentuated by soil disturbance (by tillage, vehicular traffic), lack of ground cover (bare fallow,
Jharkhand OCP(1.0 Mtpa) 16 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
residue removal or burning) and harsh climate (high rainfall intensity and wind velocity).
Above problems can be circumvented by describing the catchments into approximately homogeneous sub - areas using Geograp hic Information System (GIS). In this study, the remote sensing and GIS techniques (through Satellites Imagine and interrelated software) were used for derivation of spatial information, catchments describing, data processing, etc. Various factors of Univ ersal Soil Loss Equation (USLE) were generated and overlaid to compute spatially distributed gross soil erosion for the area using 11 - year rainfall data. The concept of transport accumulation of soil was formulated by using the GIS for generating the trans port capacity. Using these formulae, the amount of sediment rate from a particular sub - area is indicated. Following three formulae have been used for estimation of soil erosion in this project. This formula uses the USLE , WET and SMCP equation s. 1). USLE (Universal Soil Loss Erosion) 2). WET (Watershed Erosion Tool) 3). SMCP (Soil Management & Conservation Practice)
F actors included in these equations are collected, studied and reviewed using the Geomatic information system ( GIS ) and data, plan and infor mation gathered from the field and others sources . Following are the data source required in the above equations.
3.2.1 Data Source The following data are used in the present study:
Primary Data Satellite data [IRS - P6/LISS - III; Band# 2,3,4,5; Path#106, Row#55] was used as primary data source for the study. The raw satellite data was obtained from NRSA, Hyderabad, on CD - ROM media.
Jharkhand OCP(1.0 Mtpa) 17 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
Secondary Data Secondary (ancillary) and ground data constitute important baseline information in remote sensing, as they imp rove the interpretation accuracy and reliability of remotely sensed data by enabling verification of the interpreted details and by supplementing it with the information that cannot be obtained directly from the remotely sensed data. The following secondar y data were used in the study: (i) Survey of India topographical map – 73E/9 &10, and 73E/5&6 (ii) Vicinity map supplied by CCL showing village, road and drainage etc. (iii) Present and proposed Landuse Plan. (iv) Cross section of nala and OB dumps.
3.2.2 Area under consideration for soil erosion calculation Jharkhand OCP is running project and producing coal from small patch. A Project report of Jharkhand OCP 1. 2 Mt pa prepared and has been sanctioned. Soil erosion for present condition and proposed condition will different. So assessment for soil erosion will be done for both the existing and proposed condition. a) Following table shows the proposed land use plan of the Jharkhand OCP which is to be used for the different activities. Table Bottom Top Area Ave. Slope Slope Sl no Infrastructure Area m 2 m 2 angle % length m 1 Lease hold area 277.10 - 5 - 2 Quarry area 76.42 - - - 4 Dump 87.00 24.20 35 130 All other Infra 5 22.42 - 4 - struc tures Green land & 6 91.26 - 5 - safety zone
3.2. 3 The general formula of USLE is given below The USLE Equation is: A = R * K * LS * C * P Where, A = P redicted soil loss (tons per acre per year)
Jharkhand OCP(1.0 Mtpa) 18 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
R = R ainfall and runoff factor K = soil erodibility factor LS = slope factor (length and steepness) C = C rop and cover factor P = Pre servation practice factor A - The tons of soil lost per acre per year. The value "A" is usually compared to a value "T". T is the amount of soil loss that is considered "tolerable". Each soil series has a value T listed in the soil survey. R - Rainfall and runoff factor. R is based on the total erosive power of storms during an average year and depends on local weather conditions. calculation of R factor is the summation of daily erosive factor (y). Where in (y) = 3.2353+1.7890 In (x) K - Soil erodibility factor. Depends on texture , structure , and organic matter. The k - factor was generated from detailed - reconnaissance soils map (1:100,000) and assigned values according to soil texture as studied by GIS.
LS – L factor and S factor are combined into one factor. The LS - factor layer is then generated from the following equation:
LS = (L/22.1) m (0.065 + 0.045 S + 0.0065 S 2 ), Wischmei r and Smith (1978) n m LS = (L s / 22.1) x (Sin β / 0.0896) by Moore & Wilson (1992): L - Length is the distance between the beginning of water runoff on the land and location of sediment deposition on the land or runoff enters a well - defined channel. The slope length factor computes the effect of slope length on erosion. Slope length longer than 1000 ft are not used in this interactive calculator because t he calculation may not be reliable. S - Slope steepness. The slope steepness factor S computes the effect of slope steepness on erosion. C - Cover factor. Compares cropping practices, residue management, and soil cover to the standard clean fallow plot. C - factors for different management practices are developed based on their observed deviation from the standard, which is clean - till w ith continuous - fallow conditions.
Jharkhand OCP(1.0 Mtpa) 19 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
P - Pre servation practices implemented into the management system. It is the soil loss with contouring and /or strip cropping, or terracing to that with straight row cropping / planting up - and - down slope ( i.e . , parallel to the slope).
This method is most suitable for moderate slope and slope length but for large area. It may be used in both barren and covered land. So this formula is used for determination of soil erosion for natural ground which has low slo pe and having low cover . So, soil erosion from infrastructures sites , which has low slope and low cover have been done by using the USLE formula. a ) Following table shows the different parameters of the proposed infrastructures Table Land Runoff Soil slope Cover Ave. soil Sl consider factor erodibility factor factor erosion Method no for erosion R factor K LS C t/a/y A ll Infra 2.73 1 564.9 0.2 4 0. 5 0. 04 USLE structures t/a/y
3.2. 2 SMCP (Soil Management & Conservation Practice) This calculator determines erosion or detached sediment by considering following factors. i) The first factor is the size or area of the site of interest. ii) The second factor involves the idea of raindrop impact energy. When a raindrop falls from the sky and hits the ground, the surface soil adsorbs the energy. Erosion occurs when the energy is powerful enough to detach soil. The amount of ene rgy the rainfall of a particular storm depends upon the frequency of the storm and the location. Certain areas of the country frequently have higher energy storms than other areas. iii) A third factor is the soil texture. Just as soil texture influence wat er infiltration, it also impacts how easily soil can be detached. iv) A fourth factor is the influence of the arrangement of the land surface or the topography of the site of interest. The steepness and the length of distance down the slope both will affe ct erosion.
Jharkhand OCP(1.0 Mtpa) 20 Job no. -- 0903 10155
CMPDI Prevention of soil erosion v). The final factor is land cover. Erosion level depends on how much of the bare soil is vulnerable to raindrop impact. The erosion calculator will show how each of these factors affect the erosion. This method is most suitable for steep s lope but small length. So this formula is used for determination of soil erosion from external dump and embankment which has steep slope and small length.
a ) Following table gives the assessment of soil erosion from external dump and embankment which has steep slope but small length of the proposed mines. Table Ave. soil Length Slope Ave. Slope Sl no Infrastructure erosion Method ft length angle % t/a/y 1 Extrenal Dump 2500 120 35 3.7 SMCP 2 Active Dump 500 60 30 3.0 SMCP
Results Output from SMCP calculator: - Based on the previously inputted of parameters and a 20 year simulation, soil loss was determined. The results in the above table and the following figures represent the output o f the Water Erosion Prediction project ( WEPP ) calculation. The following table and graph presents the result output, slope profile and soil loss & deposition location.
W EPPCAT Simulation Results
Scenario: Baseline State: Alabama Climate Station: TROY Management: Fescue Soil: AMY(SIL) Slope Shape S - shaped(45%) Slope Length (ft): 120 Slope Width (ft): 3000 Average Annual Precipitation (in/yr) 53.3 Average Annual Runoff (in/yr) 7 Average Annual Soil Loss (ton/A/yr) 3.7 Average Annual Sediment Yield (ton/A/yr) 3.6
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CMPDI Prevention of soil erosion
AREA OF NET SOIL LOSS A . ** Soil Loss (Avg. of Net Detachment Areas) = 3.7 t/a ** ** Maximum Soil Loss = 6.7 t/a at 61.2 ft. **
Area of Soil Loss Soil Loss MAX MAX Loss MIN MIN Loss Net Loss MEAN STDEV Loss Point Loss Point ft. t/a t/a t/a ft. t/ a ft. ------0.0 - 118.8 3.7 1.8 6.7 61.2 1.4 118.8
B. AREA OF SOIL DEPOSITION
** Soil Deposition (Avg. of Net Deposition Areas) = - 7.6 t/a * * ** Maximum Soil Deposition = - 7.6 t/a at 120.0 ft. **
Area of Soil Dep Soil Dep MAX MAX Dep MIN MIN Dep Net Dep MEAN STDEV Dep Point Dep Point ft. t/a t/a t/a ft. t/a ft. ------
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CMPDI Prevention of soil erosion
118.8 - 120.0 - 7.6 0.0 - 7.6 120.0 - 7.6 120.0
Single Point Single Point Soil Area Dep ft. t/a ------120.0 - 7.6
3.2. 3 WET (Watershed Erosion Tool) The erosion calculations are based on the WEPP model, developed by a group of scientists at the National Soil Erosion Research Laboratory . The WEPP erosion model is a continuous simulation computer program which predicts soil loss and sediment deposition from overland flow on hills lopes, soil loss and sediment deposition from concentrated flow in small channels, and sediment deposition in impoundments. In addition to the erosion components, it also
includes a climate component which uses a stochastic generator to provide d aily weather information, a hydrology component which is based on a modi fied Green - Ampt in filtration equation and solutions of the kinematic wave equations, a daily water balance component, a plant growth and residue decomposition component, and an irrigatio n component. The WEPP model computes spatial land temporal distributions of soil loss and deposition, and provides explicit estimates of when and where an watershed or on a hill slope that erosion is occurring so that conservation measures can be selected to most effectively control soil loss and sediment yield. In this model, following parameters are required as input data in the WET computer programming calculator for soil erosion. 1) Field length 2) Field width 3) Slope size 4) Steepness of slope 5) Type of soil 6) Regio n as per rainfall 7) Management system
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CMPDI Prevention of soil erosion
This method is most suitable for both steep & flat slope of short or long length but should have some type of land cover it may be wooded, residential and agricultural. So this formula is used for determination of so il erosion from the green land, green belt / safety zone s . . a ) Following table gives the assessment of soil erosion from green land & safety zone which has large area with some covers of the proposed OCP mines. Table Length Ave. soil Sl Area Soil Land Steepness Item Region along erosion no in Acre Texture Cover of soil slope t/a/y Green land & Rocky Light 1 168 Sandy Moderate Long 0.68 safety zone Mts Wooded
Input Data and Result Of WET Calculator
Location Input: Desert (SW) Land Area Land Use and Land 168 Rocky Mts. Soil Texture Cover acres (NW) If Ariculture, Sand Wooded Storm Frequency Appalachain Crop Mts.(NE) Sandy Residential Frequent Loa m Row Crops Central Agriculture Storm Lowlan ds (Upper Silty If Wooded, Pasture Midwest) Infrequent Clay Loam T illage Implement Storm Heavily Wooded Great Plains Clay Very (Lower Midwest) Lightly Wooded Conventional Plow Infrequent Atlantic & If Residential, Storm Gulf Coasts (SE) No - Till Plow Tillage Direction Slope Scraped Bare during Resul ts: Length along slope Construction Steep Up & Down Slope Erosion Mulched during Very Long Mod. Construction (Detached With Sediment) Steep Long Young Grass Contours 115.032641 tons Moderate Moderate Established Grass Flat Short
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CMPDI Prevention of soil erosion
3.3 Final assessment for soil erosion a ) Following table shows the different parameters of the different landuse of the existing Jharkhand OCP .
Following table shows the differ ent parameters of the different landuse of the proposed Jharkhand OCP . Table Ave. soil Sl Area Characteristic of erosion t/a/y Method no Under use land without PP Low slope & low 1 All Infra structures 1 .73 USLE cover 2 External Dump Very steep slope 3.7 SMCP 3 Active dump & small length 3.0 SMCP Green land & Large area and 4 0.68 WET safety zone with some cover
Following chart shows side by side predicted and prevented soil erosion in t/a/y
Predicted
4 3.7 3.5 3 3 y / a / t
2.5 n o i
s 2 1.73 o r E
l 1.5 i o S 1 0.68 0.5
0 Inf. Stu Ext Dump Active dump Green land
Predicted
Result Interpretation Prediction for soil erosion form the Jharkhand OCP is done by using the USLE equation and SMCP & WET mode l . All model were used on most suitable land use conditions such as; -
Jharkhand OCP(1.0 Mtpa) 25 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
USLE equation was used for soil erosion calculation for the land patches of infrastructures sites. SMCP model was used for soil erosion calculation for the dumps and embankments WET model was used for soil erosion calculation for the Greenbelt and safety zone. Result come out for different landuse area is between 0. 68 to 3.7 t/a/y which is between in the normal range of soil erosion in this type of soil. If this project had not been exist ing and all land was virgin , the normal soil erosion process would had been taking place and this must has been more than 0. 68 t/a/y. It is observed that only 10 to 25% of total eroded soil get s lost (carried away out side the leasehold area) and remaining eroded soil deposited where the slope is easy . S oil loss grap h substantiate the observation. This soil erosion can be minimized around 9 0% by providing optimum cover and suitable arrangement such that baffle wall, guiding channel, gully plug, etc. In our case about 95% of soil loss can be prevented by providi ng the proper treatment such that Plantation, grassing, sedimentation pond/tank, gully plug weir, etc.
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CMPDI Prevention of soil erosion
CHAPTER – IV Control measures
4.0 General Surface runoff causes the water pollution as well as the soil erosion problem s . The principal environmental issues associated with runoff are the impacts to surface water, groundwater and soil erosion through transport of water pollutants to these systems. Ultimately these consequences translate into human health risk, ecosystem dist urbance and aesthetic impact to water resources. Some of the contaminants that create the greatest impact to surface waters arising from runoff are petroleum substances, coal particles, inorganic substances , soil, etc. These surface runoff translated into overland flow and surface water flow and deposited the soil and others pollutant there. These depositions badly affect land quality and capacity of the river/nala.
4.1 General Concept of Control measures for: - 1) Water Pollution 2) Soil Erosion ( A ) Soil erosion due to surface runoff ( B ) Soil erosion due to blowing wind 4.1. 1 General Concept of Control measures for Water Pollution - Opencast mining has vari ous type of water pollution source which degrade the quality of water of nearby river/nala and under ground water reserve. a) Basic approach to control the surface runoff water i s to differentiate the mine into "clean" area and "dirty" area zone fo r the purpose of surface run - of. "Dirty" area run - off is water coming from stockpile, reclamation area, open cut mining areas etc. and therefore normally it requires treatment prior to discharge. "Clean" areas run - off is water, which passes through the un disturbed areas & green belt areas and it is prevented from entry to "dirty" areas through the use of diversions, drains and allowed to discharge the water into nearest natural drain directly
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CMPDI Prevention of soil erosion
because it does not need treatment. Regular monitoring is done to check the pollution level. b) The liquid effluent generated at washing stations and workshop would be polluted with high concentration of suspended solid, oil & grease. These effluents are treated in treatment plants inside the workshop. No effluent is allowed to go outside because whole system is designed on the basis of zero discharge system. C ) Municipal effluents are not allowed to discharg e on either land or inland water sources without proper treatment because it can pollute land & other stream. E very housing unit or in group will be provided with septic tank and the outflow is led to soak pit. Other municipal effluent will be routed through sedimentation tank. The quality of effluents should conform to standards laid down in IS 4764 (Tolerance lim it for sewage effluents discharged into inland surface water & IS 2490 – tolerance limit for industrial effluents discharged into inland surface water). All effluent shall be tested on quarterly basis. Action
4.1. 2 General Concept of Control measur es for Soil E rosion Soil erosion occurs when wind or water washes away the topsoil from an area of land. So il erosion is natural, but it quickly becomes problematic when people begin construction works and cutting down the vegetation cover. So it i s very important to prevent soil erosion . Erosion of soil is basically depending upon the speed of surface flow / wind speed and vegetation and others type of covers . Appropriate soil erosion control measures of different sources are recommended below to l imit the soil erosion to a minimum extent.
( A ) Soil erosion due to surface runoff List of sources that are responsible for soil erosion, their characteristic and volume have been discussed above. Overland flow that is released is l ikely to flow downhill more quickly and in greater quantities (i.e. possess more flow power as a result of its kinetic energy), and so this flow of water become able to Jharkhand OC P(1.0 Mtpa) 28 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
begin transporting and even detaching soil particles. Where it does so, the soil surfac e will be lowered slightly. Lowered areas form preferential flow paths for subsequent flow, and these flow paths are in turn eroded further and transported up to a location where the speed of flow down to carrying capacity. These depositions creates the ob stacle in the way of spontaneous water flow causing large area submergence, cutting of sides of channel besides the degradation of water quality in Chutua nala/ Kedla nala . In view of the above, basic approach in deciding the appropriate soil erosion control measures, are as follows – The amount of soil erosion that occurs in an area depends upon two factors: the speed with which water and wind travel across it, and the abundance of plant life that is growing there. Since we have no control over the s peed of the wind, how heavily it rains, or the currents of the nala , so we need to concentrate on the factor we can control are (i) Surf a ce cover ( vegetation cover and other) and (ii) B reaking the speed of surface flow . Plant life protects topsoil in ma ny ways. It prevents heavy rains from beating down on land and knocking the topsoil loose. It prevents the soil from drying out as quickly, thereby protecting it from being blown away by strong winds. The roots of the plants hold the soil in place, so it i s not washed away as easily. Soil erosion is inversely prop o rsna te to soil cover and the speed of the runoff . A 60 % of land cover would result in 85 % reduction in soil erosion and further breaking the speed of surface runoff for keeping up below scouring speed by baffle wall and any other means would result in further reduction of soil erosion by 45%. So in this combination 94 % reduction in soil erosion can be achieved. i ) Soil Erosion from Construction site Presently no major civil or any other type s of construction work s is going on in the project. In future, if any construction work would start, the following preventive measures would be taken up to reduce the opport unity of soil erosion/water contamination at construction site. Jharkhand OC P(1.0 Mtpa) 29 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
Site to be taken for construction at different time horizon should be clearly marked. Vegetation removal and breaking of earth would be controlled and confined to site which is immediately required for construction. Catch Drain will be provided around the township /construction sites during construction period to intercept water flowing out. Surface Run off from construction site would be channelised to sedimentation lagoon. The clear o verfl ow water from lagoon will flow into near by natural streams Site for storage of rubbish, excavated earth etc. would be identified and d rainage arrangements will be provided around these and connected to sedimentation lagoon to avoid pollution of natural st reams. As soon as construction is ove r , all site s would be vegetated & planted with trees.
ii ) Soil erosion from OB Dumps – Newly formed and barren OB dumps are the main culprit for the soil erosion particularly active and new OB dumps. Soil of the OB du mp is easily eroded by both wind and water because it is in un - vegetated and in loose conditions. Following preventive measures would be taken up to reduce the opportunity of soil erosion/water contamination from overburden sites.
First of all a Gabion wall of 1. 2 5 m to 1.75 m height, depending upon the prevailing condition, of stone boulders all around the OB dump , w ould be constructed. This measure will check the OB dump from the spreading beyond the Gabion wall. Garland Drains will be provided ar ound the retaining wall of size 1. 5 m (width) x 1.0 m (depth) to check the surface run - off flowing out or into the OB dump. This drain is to convey the intercepted run - off water into sedimentation lagoon. This measure will prevent the surface run - off fro m spreading to any where.
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CMPDI Prevention of soil erosion
A sedimentation tank of sufficient size (5% of total runoff or 10 th highest rainfall in 24 hr which ever is more) will be constructed , so as having the one hour detention period , most of the time. This act will arrest at least 90 % of suspended soil particles that flow out with surface run - off.
Over flow effluent from the sedimentation tank would be allowed to discharge in the nearby natural stream. A series of gully plug will be provided if speed of discharge water is above the scouring speed of soil. This will protect the stream bed and prevent the side from being scoured. Thus, there would be reduction in
soil erosion. Photo showing the toe wall
Quick growing grass and v egetation This will provide extra space for cover would be done on the part of flowing of water and thus will prevent inactive dump all along the inclined spreading of water. a nd top portion of the dump. This will Trees will be planted in three rows all protect the soil particle from being around the OB dump. First row trees detached due to action of rain fall will be of short he ight, second row and hard wind blowing. Thus, there trees will be of medium height while would be reduction in soil erosion. third row trees will be of long height. Quick growing grass and vegetation These measures will break the wo uld be planted on the route of velocity of wind and will prevent the water ways. soil erosion and spreading of dust.
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CMPDI Prevention of soil erosion
Garland drain and all flow channels should be cleaned re gularly specially before the onset of the monsoon.
iii ) Run off from Coal Dumps – The project should be so planned that coal dumps would not be created. If unavoidable, baffle walls and garland drains would be provided around the coal dump to int ercept the surface runoff flowing out from it and also to collect runoff from the surrounding of dump site. This drain will convey the intercepted water into sedimentation lagoon. Over flow from the sedimentation lagoon will be discharged into the natural drainage system. A series of gully plug will be provided if speed of discharge water is above the scouring speed (>1.5km/hr in this condition) of soil.
iv ) Run off from built up areas Open drains would be provided along the roads, workshop, township and other service buildings. These drains will collect the water from built up area which is not much polluted except the normal suspended particles, garbage, silt and sand. This water would be diverted into sedimentation tank and from there to natural drains to convey into Chutua nala/ Kedla nala . A series of gully plug will be provided if speed of discharge water is above the scouring speed of soil. v ) Mitigation m easures for remaining area Area is divided in two zone , clean area zone and dirty area zone . Clean area zone comprises the un - broken zone where is not any type of activities are earmarked and having green land. In dirty area zone, all infrastructures and ac tivities are located . Both the area would be separated by storm drain or water guide chann el so that water flowing out from each zone could not mixed - up. If s peed of water pass ing through these areas is more than scouring speed (0.5m to1.5m per second) , then series of small baffle wall s would be constructed. Height of baffle wall will be 3.0 to 5.0 cm more than the depth of the overland
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CMPDI Prevention of soil erosion
flow and width should be equal or more than the width of surface run - off. So, surface run - off will passes through over these baffle walls which will reduce the speed of flow and result in the settling down of su spended particles. This water coming out from the clean zone area will be allowed to pass through the nearby natural streams directly after breaking down the speed less than the scouring speed of soil with the help of use of series of gully plug. Dirty area zone is further divided into aggressive and non - aggressive area. Photo shows the bund/waffle wall arrangement Aggressive zone contains completely broken area such as quar ry area, building s , industrial buildings, road, coal stockyard area, CHP area and etc. other industrial area. Non - aggressive zone comprises of all administrative
Water flowing out from the non - aggressive zone will be guided to sedimen tation tank. Effluent from here will be allowed to meet the natural local streams after breaking down the scouring speed with the help of series of gully plugs. Surface run - off coming out form the aggressive zone would be treated individually as mentioned in the para of “Mitigation Measures”. Over flow effluent from these sedimentation tanks would be sent into the large sedimentation pond. Effluent from here will be allowed to meet the natural local streams after reducing the speed below scouring speed wit h the help of series of gully plugs. Final effluent will be checked regularly as per monitoring program . If any deficiency is found then suitable rectification will be done. All the vacant land would be vegetated with quick growing grass, bushes and small and medium size trees. Medium size trees would be planted Jharkhand OC P(1.0 Mtpa) 33 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
A ll around the all administrative buildings, infrastructure s buildings, coal storage site, a venue plantation and strip plantation will be done all along the roads and in the colony area. Finally al l the drainage system will be cleaned regularly and more frequently in monsoon season. All sedimentation tanks must be cleaned before the onset of rainy season.
(B) Control M easures for Soil Erosion by wind Damage from wind erosion is of numerous ty pes. The dust storms resulting there are very disagreeable and the land is robbed of its long term productivity. Crop damage, particularly in the seedling stage, by blowing soil is often a major concern. Subsequent yield and quality losses are incurred and , in the extreme, tender seedlings may be completely killed. Often sufficient soil is removed to expose the plant roots or un - germinated seeds, and these results in complete crop failure. Sands begin to drift and form unstable dunes which encroach on bette r surrounding lands Wind erosion depends upon the type of storm, speed, duration and type vegetation covers. It is studied that wind speed less than 20km/h has not much impact on soil erosion. In above attributes, we can only control the negative effect o f the speed of wind by increasing the vegetation cover. Wind speed can be reduced by erecting the some obstacles in the path of wind. Planting of trees would be most suitable obstacle for breaking the wind speed and it also enhance s the vegetation cover upon the soil. These plantations also reduce the evapo - transpiration by 20% and help to maintain the soil moisture content. Bonding affect between the soil particles increase s due to increase in moisture content and it resist s the erosion force. So , the be st arrangement would be to plant two rows of tall trees surrounded by two rows of low trees, making up a 10 - metre strip . Vegetation cover, grass or crop w ould be increased. It is particularly important to repair breaches in a hedge to keep the wind from p ouring through at these points (the Venturi effect) and considerably reducing effectiveness.
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CMPDI Prevention of soil erosion
Soil erosion by wind becomes significant when speed of wind increases to 20km/h means 6m/sec. In our region, wind speed hardily (3 or 4 times per year) increases t o above limit. So there is no major problem of soil erosion caused by wind blow .
4. 1.2 Mitigation M easures for R iver/ N ala First of all only treated water would be allowed to enter the nala. Initially one weir of height 1.5m would be constructed on the Chutua nala/ Kedla nala . This weir would serve our dual purpose; firstly it will stop further transportation of soil, secondly it will facilitate the rain water
Systemic drawing of weir Photo showing the temporary weir harvesting store the water for long period after rainy season and most important it will facilitate the local habitants to utilize the water. The d etail design and specification of the weir would be provide d separately after the clearance of this report , if CCL desire so .
4.1.3 Project Specifics i) OB Dump; - A Gabion wall of 1.5 m height will be constructed all around the OB dumps. It would prevent the internal dump , when its height goes above the ground surface, materials form spreading outside the Gabion wall. A garland drain of size 1.5 m x1 . 0m will be constructed all around the gabion wall. It would intercept all the surface water coming out from dump.
Jharkhand OCP(1.0 Mtpa) 35 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
Retrieve drain will be provided at incli ned face of the dump @ 100m interval as shown in the drawing. Top surface of OB dump will have t ransverse and longitudinal slope of 1:50 spreading outward so as rain water can be evacuated easily. Berm of 15 to 20 cm will be provided all round the OB dump. This will prevent the water form spillage on inclined face of dump. Two sedimentation tank s /pond s of 8.0mx6.0mx1.6m (5% of total runoff or 10 th highest rainfall in 24 hr which ever is more) size will be constructed, one at south - west corner and other at upper middle part of eastern side of the dump. This lagoon would store all the water coming from garland drain for an hour in normal condition. Overflow from this lagoon would be allowed to meet the local stream after providing three or four gully - plug .
ii) Embankment: - A embankment is required to be constructed at the eastern boundary of the project against the Chutia / Kedla nala . A garland drain of size 1.5x1.0m and 3000m length will be constructed all around the embankment . Top of the embankment would be planted with short height trees of native species. Soil berm of 15cm to 20cm height will be constructed all around the top to prevent the spillage of the rain water. Top surface of embankment will have transverse and longitudina l slope of 1:50 spreading outward so as rain water can be drained out easily as shown in drawing. Two sedimentation tanks/ponds of 8.0m x 6.0m x 1.6m (5% of total runoff or 10 th highest rainfall in 24 hr which ever is more) size will be constru cted . This lagoon would store all the water coming from garland drain for an hour in normal condition. Overflow from this lagoon would be allowed to meet the local stream after providing three or four gully - plugs. iii) Industrial Area: - Gar land drain of size 1.0 m x 0.75m will be constructed all round of the industrial area i.s CHP, Coal stock, etc. This drain will intercept all the
Jharkhand OCP(1.0 Mtpa) 36 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
runoff coming from the area and lead to sedimentation tank/ lagoon . Overflow from this lagoon would be allowed to meet the local stream after providing three or four gully - plugs.
i v ) River/Nala: - A weir/ check dam of 1.5 m height would be constructed, suitably located, in the down stream side of Chutua Nala . This weir/ check dam will serve many purposes: firstly, it will prevent the flowing out the sediments further, secondly, it will serve as rainwater harvesting lagoon and finally it will serve as the storage of water for the villagers during the lean season. A typical cross - section has been g iven but actual size can be determined only after the detailed survey.
4.1.4 Final Soil Erosion after Prevention measures Quantity of soil erosion from the lease hold area has been predicted in previous chapter by the suitable methods. Appropriate preventive m easures as mentioned above are applied and final soil erosion quantity has been predicted and tabulated below. For proposed land use Table - 4.1.4
Ave. soil Ave. soil Sl Area Characteristic er osion Prevention Prevention erosion Method no Under use of land t/a/y measures factor t/a/y without PP with PP 60%cover with All Infra Low slope & 1 1.73 grass 0.2 0.34 USLE structures low cover trees & others 60%cover 0.2*0.45 External Very steep with grass 2 3.7 = 0.34 SMCP Dump slope & trees & terrace 0.09 small length at top 3 Active dump 3.0 Non 1.0 3.0 SMCP Large area Const. of baffle 0.25*0.4 Green land & 4 and with 0.68 wall & more = 0.068 WET safety zone some cover vegetation 0.10
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CMPDI Prevention of soil erosion
Following ch art shows side by side predicted and prevented soil erosion in t/a/y for proposed land use.
Predicted and Prevented Soil Erosion
4 3.7 3.5 3 3
y 3 / a / t
2.5 n o i
s 2 1.73 o r E
l 1.5 i o S 1 0.68 0.5 0.34 0.34 0.068 0 Inf. Stu Ext Dump Active dump Green land
Predicted prevented
Jharkhand OCP(1.0 Mtpa) 38 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
CHAPTER – V Cost E stimate & Conclusion
5.1 Construction It is propose d to construct gabion wall using the stone boulder and iron wire as toe wall along the OB dump. It would be cheaper and effective to serve the purpose . Permanent g arland drain will be c onstructed with brick masonry all along OB dumps and coal stock yard. Temporary garland drain would be constructed along the quarry. All the storm drain along the road or around the colony will be of permanent type. Sedimentation lagoon near OB dump and in the dirty zone will be constructed of temporary type because shape of the OB dump and quarry will be changing with the time. Sedimentation tank near the CHP and workshop may be of permanent type if the location is final. Baffle wall may be of earthen or m asonry construction depending upon the prevailing condition at that time . All the gully plugs would be of permanent type construction.
5.1.1 MAINTENANCE
Sedimentation tank /lagoon should be cleaned every year before the onset of monsoon. Fishery work should be started in the sedimentation tank / recharged pits to keep the water clean and it will also make a way for income. Water analysis of recharging pit and nearby well should be done periodically, so that quality of water can be assessed. Vegeta tion should be done regularly at open spaces, on the way of surface run off, nearby area and other suitable places
5. 2 Cost - Total cost for the scheme comes to 342.7 Lakh s . This amount may changes at the time of construction due to prevailing conditio n and situations .
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CMPDI Prevention of soil erosion
Table Rs. i n Lakh s Sl.no Particular Quantity cost Cost of garland drain along 1 4000 m 120 dumps and quarry. Cost of storm drain along 2 500 m 5 roads and buildings. Weir/Check dam of length 3 1 no 100 50m & 75m 4 Gabion/to e/retaining wall 0.0m 22.4 Sedimentation 5 5 no 2.5 tank/lagoon(Temp.) Guiding channel / baffle 6 500 m 2.5 wall(Temp.) 7 Cost of gully plug 0.3 Cost of plantation over OB 8 dump, embankment and 100 ha. 50 development of green belt Cost of grassing over 9 50 nos. 30 embankment, OB dump Cost of arboriculture/ 10 10hact. 10 vegetation TOTAL 342.7
5.1 Conclusion - a) Soil erodibility is an estimate of the ability of soil to resist erosion, based on the physical characteristics of each soil b) Soil erodibility is directly proportional to intensity of rainfall, speed and quantum of surface flow and inversely proportional to residue cover. c) All formulae used for calculation of soil erosion are based on the research done in foreign countries and it is still in nascent stage. So result may diverge in our prevailing conditions. d) Prevention of soil erosion scheme is prepared on the assumption that breaking the speed of surface run - off and higher the vegetation cover will prevent the erosion. e) Generally , soil with faster infiltration rates, higher levels of organic matter and improved soil structure have a greater resistance to erosion.
Jharkhand OCP(1.0 Mtpa) 40 Job no. -- 0903 10155
CMPDI Prevention of soil erosion
f) Sand, sandy loam and loam textured soils tend to be less erodible than silt, very fine sand, and certain clay tex tured soils. g) Tillage and cropping practices which lower soil organic matter levels, cause poor soil structure, and result to increases in soil erodibility h). Past erosion has an effect on a soil' erodibility for a number of reasons. Many exposed subsu rface soils on eroded sites tend to be more erodible than the original soils because of their poorer structure and lower organic matter. i). Maximum soil erosion occurs from newly dumped overburden waste and it reduced to 50% in each subsequent year.
5. 2 LIMITATIONS The above formula and model used for predicting soil erosion by flowing water resulting from rainfall. These formula and model are based on the research done in foreign countries and it is still in nascent stage. The model may not be valid under extreme values of the parameters considered in the equation. So result may diverge in our prevailing conditions All the data and information used in the model is either supplied by project administration or the planning department of CMPDI. Shape & size of the mine has been changing continuously so the result may changing accordingly. The amount of water received during the monsoon season ( 15 th June to 15 th , Sept ember) is important since this is the period of maximum rainfall. Conversely, rainfall received during the winter season is less significant because it does not cause soil erosion due to the small amounts and low intensity. There may be several other factors, in addition to those considered above, that could play a significant role in soil e rosion. These factors, such as land configuration and management practices, can cause a deviation in estimated soil erosion values under certain conditions.
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