Rainwater Harvesting- An Industrial Case Study

IJSTE - International Journal of Science Technology & Engineering | Volume 2 | Issue 07 | January 2016 ISSN (online): 2349-784X

Rainwater Harvesting- An Industrial Case Study Sambhavi S. Chachire M. Tech Student Department of Civil Engineering G. H. Raisoni College of Engineering, Nagpur - 440016, Maharashtra, India

P. J. Wadhai Associate Professor Department of Civil Engineering G. H. Raisoni College of Engineering, Nagpur - 440016, Maharashtra, India

Dr. V. P. Thergaonkar Ex - Scientist NEERI, Nagpur, Maharashtra, India

Abstract Ever increasing shortage of water particularly for industries in the urban areas has prompted to undertake studies on feasibility of rooftop and runoff rainwater harvesting (RWH) system. A typical industrial establishment was selected for a study, for this rooftop area, paved area and drainage system was selected. Total rooftop surface available was 53061 m2, paved open space was 54535 m2, area under plantation was 18750 m2. Estimated flow in the drain within plant area was 1.584 m3/sec. Rainfall pattern in Nagpur during the past 5 years was used to compute probable recoverable rainfall quantity. This period was selected because rainfall was below normal and would give minimum water quantity which could be available for harvesting. Geology, topography and other land features are proposed to be studied for suggesting i) Rainwater harvesting structures and ii) containing aquifers for groundwater recharge. This paper presents the feasibility study of rooftop and runoff rainwater harvesting system in a particular industry under study.

Keywords: Rainwater harvesting, Rooftop, Runoff ________________________________________________________________________________________________________

I. INTRODUCTION The increasing growth in population, industrialization and urbanization is causing severe impact over the water resources. All over the world, it has been acknowledged that spatial rainfall pattern has changed. Study of periodicity of monsoon in Vidharbh region is no more reliable. This has been resulted in non-availability / erratic recharge of aquifers. Rainfall in catchment areas of the reservoir (natural or artificial) is also uncertain. In India, with the increasing population and strain on natural resources, especially water, the use of RWH system is becoming very essential. RWH implies conservation of rainwater. The RWH system depends upon the topography, land use, land cover and rainfall pattern.

The industry undertaken for study is located in industrial area where facilities are provided by the State Industrial Development Corporation. It includes water supply, drainage, power connections etc. The plant manufactures tractors. Production units in the plant are Transmission Plant, Engine Plant, Hydraulic Building, Marketing Building, Ware House Building, Tractor Transmission, Tractor Assembly, PT-CED.

II. LITERATURE REVIEW: 1) Che-Ani A.I et al., “Rainwater Harvesting as an Alternative Water Supply in the Future”. It is about the rainwater harvesting system and its implementation in Malaysia as part of the solution proposed by government to avoid water crisis in the future.

It first reviewed the scenario of water shortage in Malaysia.

2) P. Sai Rukesh Reddy et al. “Rainwater Harvesting in hostel 12 and hostel 13 of IIT Bombay”. In this paper, rainwater is being conserved/harvested only for two hostel areas. And they used two methods of distribution of harvested rainwater (Rapid depletion method & Rationing method). Finally, the cost for construction of tank was calculated.

3) Prof. R. K. Panda “Rainwater Management in Urban & Industrial Catchments- Case Studies”. It is about Design of RWH Systems for utilization of rainwater from the rooftops of Bokaro Steel Plant. The artificial recharge structures have been designed as per the soil strata in the Vadose zone and as per the aquifer characteristics.

III. RAINWATER HARVESTING SYSTEM Rainwater can be stored by using the rainwater harvesting system. Rainwater harvesting is the technique of collecting rain water from the roof catchment and storing in surface/subsurface reservoirs. RWH system is direct collection of rainwater from roofs and other catchments (Che-Ani A.I et al.,2009). The systems can be categorized as small, medium and large scale (Gould, 1999). In general, the size of rainwater harvesting system depends upon the size of catchment area (Thamer et al., 2007).

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Rainwater Harvesting- An Industrial Case Study (IJSTE/ Volume 2 / Issue 07 / 046)

Objectives: RWH system has following objectives: 1) To provide supplementary water requirements.

2) To increase ground water levels and soil moisture.

3) To reduce the load on treatment plant by preventing the runoff from going into sewer or storm drains.

IV. METHODOLOGY Geographical Location: Present study is conducted in the Tractor Industry located in Hingna area (Nagpur). The industry has a total area of 179,966 m2.

Complete premises are divided into 8 subunits namely Transmission Plant, Engine Plant, Hydraulic Building, Marketing Building, Ware House Building, Tractor Transmission, Tractor Assembly, PT-CED. Given below a satellite picture, fig. (1), showing majority of the buildings in the industry.

Fig. 1: Satellite picture of industry (Google Earth)

Data Collection: During field visits general observations as well as resource mapping to indicate the location and distribution of any available resources such as wells, nalas and trees are conducted. This was important in order to identify whether there was any existing in site RWH technique being implemented. Catchment area is measured and calculated manually.

Rainfall Data Collection Tractor Industry is located at 79.0370 E longitude and 21.1228 N latitude in Nagpur district of Maharashtra. Average annual rainfall is 1000 mm/year. The average monthly rainfall data was collected from Indian Meteorological Department, Nagpur. Thus monthly rainfall data of the Nagpur city is given below in the table (1) which is assumed to be same for the Tractor Industry in Hingna area.

Table - 1 Monthly Rainfall Data 2012 2013

Year

2011

2014

2015

Month

Avg rainfall (mm)

Avg rainfall (mm)

Avg rainfall (mm)

Avg rainfall (mm)

Avg rainfall (mm)

Jan Feb March April May June July Aug

11.38 8.09 13.93

24.25 15.33 8.05

24.38 20.83 11.24

3.1 13.6 26.6 14.6

0.60 5.28 5.76 16.1 30.19 2.71 16.39

Sept

8.75

15.23

6.95

14.39

15.91

Oct Nov

-

4.35 8.00

29.85 -

3.43 -

10.9 -

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Rainwater Harvesting- An Industrial Case Study (IJSTE/ Volume 2 / Issue 07 / 046)

Dec

-

-

-

-

-

Estimation of Catchment Area The industry under consideration for the study have large roof area and large site area and therefore can harvest large quantities of rainwater. The rooftop areas of all buildings, paved areas, unpaved areas are measured. This measurement was done manually with the help of 'reinforced fiber tape' which is the simplest method known as 'tape survey'. Before using the tape, tape was checked for any zero error and also length of the tape was also carefully checked for its accuracy. The calculated rooftop areas of all the buildings in the industry and drain details are given in table (2).

Table - 2 Calculation of rooftop area of all buildings Serial no.

Buildings Name

Rooftop Area (m2)

No. of drains

Drain spacing (m)

Diameter of drains (mm)

1.

2.

3.

4.

5.

6.

7.

8.

Transmission Assembly Engine Assembly Hydraulic Marketing Transmission Machine Ware House Tractor Assembly PT-CED

7910 11850 4969 4424 5086 4134 7146 7542

37 30 20 8 34 20 26 24

8 12 8 6 8 8 12 12

150 150 150 150 150 150 150 150

Hydrological Analysis: On the basis of experimental results by Henry Darcy, (1865) founded a law governing the rate of flow (i.e. the discharge) through the soils and contented that discharge is directly proportional to head loss (H) and the cross sectional area (A) of the soil, and inversely proportional to the length of the soil sample (L). In other words, H Q Îą .A (1) where,

H L

L

= Hydraulic gradient (I) Q = Runoff Q = C.I.A

(2) where, C = Co-efficient of permeability Similarly, based on the above principle, water harvesting potential of the catchment area was calculated.

The total amount of water that received from rainfall over an area is called the rainwater legacy of that area. The amount of water that can be effectively harvested is called the water harvesting potential. The formula for calculation for harvesting potential or volume of water received or runoff produced or harvesting capacity is given as: V = A.P.C (3) where, V = Vol. of water Received (m3) A = Area of Catchment (m2) P = Amount of rainfall (mm) C = Runoff coefficient Value of runoff co-efficient with respect to ground cover is given below in table (3).

Table - 3 Value of runoff coefficient (C) (Rainwater harvesting and conservation manual)

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Rainwater Harvesting- An Industrial Case Study (IJSTE/ Volume 2 / Issue 07 / 046)

REFERENCES [1] [2] [3]

Che-Ani A.I et al. (2009) “Rainwater Harvesting as an Alternative Water Supply in the Future”.

P. Sai Rukesh Reddy et al. (2008) “Rainwater Harvesting in hostel 12 and hostel 13 of IIT Bombay”.

Prof. R. K. Panda “Rainwater Management in Urban & Industrial Catchments- Case Studies”.

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