Storage Tanks for Rain Water From Roof Catchment in A.M.U. Campus, A Case Study

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1 ISSN 94 8 Volume 4, Issue 1 December 017 Storage Tanks for Rain Water From Roof Catchment in A.M.U. Campus, A Case Study Khalid Rasheed Assistant Professor, Civil Engineering Section, University Polytechnic, A.M.U. Mohammad Athar Professor, Civil Engineering Department, A.M.U., Aligarh ABSTRACT With the increase of population in urban areas, the demand of water is also increasing drastically. Rain water is the fresh water available in plenty amount which if harvested will be asset for the use of people in many ways. Aligarh Muslim University ( AMU) is situated in district Aligarh. The rain fall condition of the city including AMU area is moderate. During rainy season of four months from June to September, scanty amount of water is available in the are coming as rain. The ground water table is going below and below drastically due to larger use of this water. This paper presents the need, design and cost estimate of a surface and sub-surface reservoirs to store rain water during monsoon periods which may be used in number of ways. For this purpose few larger buildings of AMU are selected and only detailed design and estimate of one new building (Bibi Fatima Hall for girls students) in A ligarh Muslim University Campus has been discussed. KEYWORDS: Rainwater, Rainwater Harvesting System, Storage Tank, Dugwell. INTRODUCTION Rain Water Harvesting is an artificial technique which makes use of the collection (trapping) of rain water during monsoon period from the paved surfaces such as roofs of the buildings, towers and roads where water cannot infiltrate into the ground directly. The rain water which is a precious commodity and needed everywhere for a sustainable livelihood for living beings (human and animals) may be used in many ways such as washing, bathing, irrigating lawns and gardens in general and improving ground water table in particular by recharging this water directly into ground through various ground water recharging systems. This technique is also used in many countries such as America, Kenya, Japan, Thailand, Egypt, Indonesia, Pakistan, Brazil, China etc. For water collection wooden made tanks were used in USA. Fero-cement tanks were used in Kenya.. Roman Villas and even whole cites were designed to take advantages of rainwater as the principal water sources for drinking and domestic purposes since at least 000 B.C. In the Negev desert (Israel), tanks (ground reservoirs) for storing runoff from hill sides for both domestic and agricultural purposes In India in many metropotan cities like Bombay, Delhi, Chennai etc. the rain water harvesting system from roof catchment of multistoried buildings are in practice. In Darjeeling it is mandatory for each house hold not to allow rain water to fall the road aside but to collect it and then either use it or let it to pass through side drains..in this thesis an attempt has been made to plan, design and construct rain water harvesting as well as recharging systems for A.M.U. Campus. Few selected buildings of AMU campus have been selected for the study. The design details of water collecting tanks and estimates of cost of only only one new building. has also been presented here. 47 Khalid Rasheed, Mohammad Athar

2 ISSN 94 8 Volume 4, Issue 1 December 017 TABLE NO -1 RUNOFF COEFFICIENT OF VARRIOUS SURFACES 1 Roof Catchment Coefficient 1.1 Tiles Corrugated metal sheets Ground surface covering.1 Untreated ground catchments.1.1 Soil on slope less than 10% Rocky material catchment Business area.1..1 Down town Neighbourhood Residential complexes in urban areas..1 Single family Multiunits detached Multiunits attached Residential complexes in suburban Industrial.4.1 Light Heavy Parks,cemeteries Play grounds Fig. 1 Roof Catchment System WORK PLAN OF A.M.U.CAMPUS ALIGARH. Since in A M U Campus, the surface water is inadequate to meet the demand and basically we depend on ground water and also due to rapid growth of buildings populations and roads etc, infiltration into the subsoil has decreased drastically and recharging of ground water has diminished, an attempt has been made to minimize the problem of water shortage by planning, design and construction of rainwater harvesting techniques in A.M.U. Campus, various approaches of design etc are presented in this paper. RAINFALL & CLIMATE. The normal annual rainfall is 708.7mm. The standard derivation is 58.4 and coefficient of variance works out to be 8.0%. The maximum rainfall occurs during the monsoon period is June to September. Aligarh experiences the tropical monsoon type of climate the summer and winters are severe. Maximum temp shoot up to 45 0 c during May and min temp. remain 18 0 c. In the winter the temp rest around 1 0 c & min temp remain around 10 0 c. 48 Khalid Rasheed, Mohammad Athar

3 ISSN 94 8 Volume 4, Issue 1 December 017 GROUND WATER MANAGEMENT STRATEGY Proposed Suitable R.W.H Ground water levels in the district is declining very fast and it is strongly recommended that exploitation of ground water through private and shallow tube wells. Dug wells have become defunctional due to lowering of water table. Information available at Engg Hall.( Bibi Fatima Hall), A.M.U., Aligarh The isometric view of Bibi Fatima Hall is shown in Fig. The design data are as follows: No of Student =0 Roof area (sqm) =10.0 sqm. Total rainfall volume for considering A.M.U =9.cum Volume available for recharging 80% cum = cum Rainfall intensity for A.M.U Campus = 708.7mm/ year. Soil type = Alluvial. Structure Recommended for recharge = Recharge dugwell. Rainfall Quantity: Rainfall is the most unpredictable variable. In the calculation, to determine the potential rainwater supply for a given catchment, reliable rainfall data are required, preferably for a period of at least 10 years. Also, it would be far better to use rainfall data from the nearest station with comparable conditions. Hence, the data for the quantity of rainfall over A.M.U. Campus, Aligarh is collected from Indian Meteorological Department (IMD). The precipitation pattern in Aligarh city and nearby are is shown in Fig PRECIPITATION (mm) 50 0 Jan feb march april may june july aug sept oc t nov dec Fig. Variation of Rainfall over AMU Campus, Aligarh Pattern The number of annual rainy days also influences the need and design for rainwater harvesting. The fewer the annual rainy days or longer the dry period, the more the need for rainwater collection in a region. However, if the dry period is too long, big storage tanks would be needed to store rainwater. Hence in such regions, it is more feasible to use rainwater to recharge groundwater aquifers rather than for storage. 49 Khalid Rasheed, Mohammad Athar

4 440 Khalid Rasheed, Mohammad Athar International Journal of Engineering Technology Science and Research ISSN 94 8 Volume 4, Issue 1 December 017 DESIGN OF WATER TANK FOR ENGG. HALL An attempt has been made to design a water collecting/storing tank with sufficient capacity to store almost full amount of rainwater coming from the roof of proposed building of the Engineering Hall (Bibi Fatima Hall, AMU, Aligarh). The tank was designed as resting on the ground as well as underground reservoir (tank). The detail design procedure is discussed below. (A) Tank resting on Ground Rainwater harvesting potential = Rainfall (mm) x collection efficiency. rainfall in (August) = 5 mm Area of roof catchment (Engg. Hall) = 10 m, No. of students = 0 Volume of water over the plot = Area of catchment x Rainfall =10 x 0.5 = 77 m Effectively harvested water = volume of water x roof coeff. x Wastage coeff. = 77 x 0.85 x 0.80 = 5 m Considering factor of safety thus increasing volume by 0% Volume of tank = 5 x 1. = m, Size of the tank base = 9 m x 8 m Free board = 150 mm Materials: M 0 grade concrete and Fe-415 HYSD bars Permissible Stresses cb = 7 N/mm st = 150 N/mm m = 1 Height of water = 4. m, Height of tank = = 4.75 m,... L/B = 9/8 = 1.1 < 9x8 Therefore, walls are designed as continues slab subjected to water pressure above H/4 or 1m from bottom whichever is greater. (H-h) = =.75 m At 1 m from base, the intensity of pressure, P = (H-h) = 10 (4.75-1) = 7.5 kn/m Alternatively, the design labels of IS: 70 (Part IV) 197 Clause. can be used for computation of moments in tank water. Moments in side walls L = 9 m, B = 8 m (i) (i) Pl 7.5 x 9 Pl 7.5 x 9 Long wall 5 knm, 78k Nm Pl 7.5 x8 Pl 7.5 x 8 Short wall 00 knm, 00 knm Moments at supports = 8 knm Moments at centre for (long wall) = Moment at centre for (short wall) Maximum moments = 8 knm, d 78 8 =150 knm = 00 8 = 7 knm Maximum moments Q x b Effective depth d = 45 mm, Overall depth D = 40 mm Direct tension in long wall, T 1 = (7.5 x 8)/ = 150 KN Direct tension short wall, T = (7.5 x 9)/ = 19 KN 8 x10 1. x1000

5 ISSN 94 8 Volume 4, Issue 1 December 017 Ast (long wall corners) M Tx σst Jd T σst (8 x 10 ) (150 x 10 ) 150 x 10 = 500 mm 150 x 0.8 x Provide 8 mm 10 mm c/c Reinforcement at centre of span (long wall) is computed as Ast (150 x10 ) (150 x x 0.8 x 45 x100 ) 150 x = 40 mm Provide mm c/c For short walls the moment being small provide 50% of the bars at corners (i.e. 0 mm diameter bars at 480 mm centre at centre span). Reinforcement for cantilever moments (For 1 m height from bottom) Cantilever moment = (.5 x 10 x 0.5 x 0.) = 5.8 KN. 5.8 x 10 Therefore, Ast 104 mm 150 x 0.8 x 45 Minimum reinforcement in the vertical direction is computed. Ast (min) = 0. percent = (0.00 x 1000 x 40) = 180 m. Steel on each face = (0.5 x 180) = 90 mm Spacing of 10 mm dia bars = 1000 x 50 ( ), Adopt 10 mm dia bars centre on both faces 110 mm c/c 90 Long wall Length = x = 9.9 m, Width = 0.4 m, Depth = 4.75 m Volume= 9.9 x 0.4 x 4.75 = 1.8 m Total volume of long wall = x 1.8 = 4.5 m Short wall Length = 8 m, Width = 0.4 m, Depth = 4.75 m, Volume = 8 x 0.4 x 4.75 = m Total volume of long wall = x = 4.9 m Base Slab Adopt base slab thickness = 40 mm % age of reinforcement in base slab = 0.0% of concrete section = 0.00 x 40 x 1000 = 90 mm Provide half the reinforcement near each face, Ast = 0.5 x 90 = 40 mm Spacing of 10 mm dia bars = π 4 x (10) 40 x 1000 = 170 mm c/c 441 Khalid Rasheed, Mohammad Athar

6 ISSN 94 8 Volume 4, Issue 1 December 017 Table- Details of Measurement and Calculation of Quantities Item Name of Items and Details Nos. Length Breadth (m) Depth (m) Quantity No. (m) R.C.C. work (1:1.5:) concrete 1. Long wall Short wall Base slab Top Slab Beam Materials Cement 5.4 m Fine sand 5.5 m Coarse aggregate 107 m 7. Reinforcement Long slab 18 / 4 x (0.01) x (vertical bars) Horizontal bars 8 / 4 x (0.08 ) x Short slab (vertical bars) 14 / 4 x (0.01) x Horizontal bars 4 / 4 x (0.08 ) x Base slab 10 / 4 x (0.01 ) x Along length Along width 118 / 4 x (0.01) x Top slab 1.5x / m Total 1.8m x78.5 = 108 qtl Table- Abstract of Cost Rectangular Tank Resting on Ground Item Item of works Nos. Quantity Labour Rates Overall Rates Amount No. R.C.C. work Including shuttering, supply of materials labour, tools and plants etc. R.C.C. work 1:15: 1. Long wall 4.5 m 70/m Short wall 4.9 m 70/m Base slab m 70/m Top slab 1 1.5m 70/m Reinforcement Long slab 44.9qtl Short slab.78qtl Base slab qtl Top slab qtl Total 5% Contingency 10 % Contractor Charge Grand Total Khalid Rasheed, Mohammad Athar

7 ISSN 94 8 Volume 4, Issue 1 December 017 ( B ) Tank Below Ground Level There may be two possibilities. CASE -1 When Tank is full ( Previous done ) In this case when tank is full with water, the sides of tank will be subjected to thrust ( or pressure) from both sides ie by water and by soil. Due to presence of coefficient Ka, (active pressure), the soil pressure is reduced by 1/ rd amount hence magnitude thrust will be less than that of water. The water pressure will be more and tank will be designed for maximum pressure ie pressure of water. This case will be similar to the case when is resting on ground and water is full from inside. CASE - When tank is Empty (No water) 1 Sin Assume angle of internal friction = 0 o, Ka 1 Sin 1 Sin0 1 1 Sin0 Coefficient of active pressure Height of tank = 4.75 m, Dimension of tank = 9m x 8m, Thickness of base slab = 40 mm Density of earth = 18 KN/m Maximum bending moment at base of wall Ka Wh M Effective depth ' d' 1 18x(4.75) x x10 1. x1000 = KNm mm Effective depth d = 00 mm, Overall depth D = 50 mm, Adopt effective depth d = 45 mm Overall depth D = 40 mm Ast x x 0.8 x 45 Spacing of 0 mm dia bars = Adopt 0 mm dia at 10 mm c/c 1910 mm Distribution reinforcement = 0.15% Spacingof 10mm dia bars / 4 x (0) x x / 4(10) x Provide 10 mm dia bars at 40 mm c/c on both faces. 14 mm x = mm Long wall Length = x = 9.9 m, Width = 0.4 m, Depth = 4.75 m Volume = 9.9 x 0.4 x 475 = 1.8 m Total volume of long wall = x 1.8 = 4.5 m mm 44 Khalid Rasheed, Mohammad Athar

8 ISSN 94 8 Volume 4, Issue 1 December 017 Short wall Length = 8 m, Width = 0.4 m, Depth = 4.75 m Volume = 8 x 0.4 x 4.75 = m, Total volume = x = 4.9 m Base slab Length of slab = x x = m Width of slab = x x = 9.84 m Depth = 0.4 m, Volume = x 9.84 x 0.4 = m % age of reinforcement in base slab = 0.% of concrete section = 0.00 x 40 x 1000 = 40 mm Provide half the reinforcement near each face / 4(10) x1000 Ast = 0.5 x 90 = 40 mm,spacing of 10 mm dia bars = 170 mm c/ c Top Slab Design Effective span = = 8.4 m, Spacing of Tee beams =.1 m, Assume live load = 4 KN/m M 0, Fe 415, Permissible Stress, cb = 7 N/mm, Q = 0.91, st = 00 N/mm, J = 0.90, m = 1 40 Loads Self weight of slab = 0.1 x 5 x.1 = 8.05 KN/m Self weight of rib = 0. x 0.7 x 5 = 5.5 KN/m Live load = 4 x.1 = 1.8 KN/m Plaster finishes = 0.45 x.1 = 1.45 KN/m Total Load = 7.5 KN/m Bending moment and Shear force BendingMoment(M) Shear Force (V) Reinforcement M Ast st Jd Wl Wl 8 7.5x (8.4) 8 7.5x KN 4.5 x mm 00 x0.9 x70 Provide 4 bars of 8 mm diameter, (Ast = 44 mm ) Effective flange width Least of the following =4.5 KNm 8000 (i) bf = (L o/ + bw + Df), 00 x100 mm (ii) bf = c/c of ribs = 10, Hence bf = mm Check the stresses Let n = Depth of Neutral axis, Bf n / = m Ast (d-n), x n / = 1 x 44 (70-n) 444 Khalid Rasheed, Mohammad Athar

9 445 Khalid Rasheed, Mohammad Athar International Journal of Engineering Technology Science and Research ISSN 94 8 Volume 4, Issue 1 December 017 Table-4 Details of Measurement and Calculation of Quantities (Under Ground Tank) Item Name of Items and Nos. Length Breadth (m) Depth (m) Quantity No. Details (m) R.C.C. work (1:1.5:) concrete 1. Long wall m. Short wall m. Base slab m 4. Top slab m 5. Beam m. Materials Cement 5.4 m Fine sand 5.5 m Coarse aggregate 107 m 7. Reinforcement Long slab (vertical bars) 18 / 4 x (0.01) x m Horizontal bars 8 / 4 x (0.08 ) x Short wall 14 / 4 x (0.01) x m (vertical bars) Horizontal bars 4 / 4 x (0.08 ) x m 9. Base slab along length 9 / 4 x (0.01 ) x m Along width 84 / 4 x (0.01) x m 10. Top slab 1.5x / m Total 1.54 m x78.5 = 10 quintal Table-5 Abstract of Cost Under Ground Tank Item Item of works Nos. Quantity Labour Overall Amount No. Rates Rates R.C.C. work including centering, shuttering, supply of materials labour, tools and plants etc. R.C.C. work (1:15:) 1. Long wall 4.5 m 70/m Short wall 4.9 m 70/m Top slab 1 1.5m 70/m Base slab m 70/m Reinforcement Long slab Short slab Top slab Base slab Earth work Excavation 1 0 5/m 4900 Total 5 % Contingency 10 % Contractor charge Ground Total

10 ISSN 94 8 Volume 4, Issue 1 December 017 CONCLUSIONS Following specific conclusions have been drawn based on above study. 1. Since the ground water table is continuously falling down of A.M.U campus and nearby area, it is necessary to plan, design and construct rainwater harvesting system in A.M.U campus to capture rainwater from Roof catchment as well as from road surface.. In A.M.U campus, there are many buildings which area is comparatively higher than that of Engg Hall. Hence depending upon the area, the number of storage tanks before each halls and building may be provided separately.. The total cost of rain water harvesting system may be worked out for whole A.M.U campus if the costs of one or two buildings are known. 4. It will be more better and convenient to provide underground reservoir (Tanks) to store rain water rather than providing storage tank without disturbing landscape of the area 5. For recharging rain water into the ground, the three types of recharging system may be recommended depending upon the maximum rainfall at Aligarh.. It is found that most of the buildings of the A.M.U campus are having the area more than (many times) the area of Engg Hall, where the required number of tanks will be quite large. It is not feasible (due to less space available) to provide many tanks. Hence it is recommended that for bigger buildings to 4 tanks may be provided and ground recharging system also be provided simultaneously along all sides of the building to capture all rainwater. REFERENCES 1. The manual entitled Rainwater Harvesting & Conservation (00) brought by the the Consultancy Services Organization C.P.W.D, New Delhi.. The Ground Water Brochure of Aligarh District, U.P. ( ) by scientist Arun Kumar. The all data for University Builng Areas from Building, A.M.U Aligarh. 4. The book entitled Design of Reinforced Concrete Structures based on working stress methods. 5. Centre for Science and Environment (CSE),Website: International Rainwater Catchment Systems Association (IRCSA),Website: 7. F.B.R. - German Professional Association for Water Recycling and Rainwater Utilisation Website: 8. Development Technology Unit,Website: 9. Texas Water Development Board Website: International Development Research Centre,Website: Water Wiser-The Water Efficiency Clearinghouse,Website: 1. Sustainable Sources,Website: 1. People for Promoting Rainwater Utilization,Website: IRC International Water and Sanitation Centre,Website: Water, Engineering and Development Centre (WEDC),Website: 1. UNDP-World Bank Water and Sanitation Program (WSP),Website: 44 Khalid Rasheed, Mohammad Athar