references - jabatan kerajaan tempatan...

7/27/2016

1

RAINWATER HARVESTING SYSTEM DESIGN

Ir Hj Ismail Abd RahmanCawangan Kejuruteraan Awam dan Struktur

Ibu Pejabat JKR Malaysia

RAINWATER HARVESTING SYSTEM

REFERENCES

DESIGN OF RWHS SHALL REFER :-

a) MSMA Chapter. 6 – Rainwater Harvesting System

b) NAHRIM Technical Guide No. 2

c) Rainwater Harvesting Guidebook – JPS

d) Garis Panduan SPAH – KPKT

e) Uniform Technical Guide Line Water Reticulation & Plumbing

7/27/2016

2

DESIGN GUIDE

DESIGN GUIDE

7/27/2016

3

DESIGN PROCESS• DETERMINED THE ROOF AREA WHERE RAIN WATER TO BE

HARVESTED• DETERMINED THE USAGE OF RAINWATER – LANDSCAPING,

GENERAL WASHING OR TOILET FLUSHING• GUTTER & RWDP SIZING• LEAF FILTER• FIRST FLUSH DIVERTER• TANK SIZING• DISTRIBUTION PIPE• WATER TOP UP/BACK UP• RAINWATER FILTER • PUMPS – IF NEED PUMPING

RAINWATER HARVESTING PROCESS

7/27/2016

4

STEP BY STEP RWH INSTALLATION

1. ROOF SURFACE

2. GUTTER MESH

3. GUTTER OUTLETS

4. LEAF FILTER

5. FIRST FLUSH DIVERTER

6. TANK SCREEN

7. RAINWATER TANK

8. INSECT PROOF SCREEN/AIR GAP TO OVERFLOW PIPE

9. WATER BACK UP

10. PUMPS

11. RAINWATER FILTER

12. WATER LEVEL INDICATOR


GRAVITY FED SYSTEM

• water collected in storage tank and fed by gravity to the points of use

7/27/2016

5


INDIRECT FED SYSTEM• water collected in storage tank, pumped to

an elevated cistern and fed by gravity to the points of use


DIRECT PUMP SYSTEM

• water collected in storage tank and pumped directly to points of use

7/27/2016

6


PROJECT INFORMATION

• Type Building = TABIKA (single storey)• Student Numbers = 40 person• Roof Material = Metal• Rainwater Usage = landscaping & Toilet

Flushing• Roof Area = 240 m2

RAINWATER DEMAND FOR DOMESTIC

• Table 6.1 : -5 Chapter 6 MSMA 2nd Edition

7/27/2016

7


RAINWATER DEMAND PER DAY

• Indoor Toilet (single flush) = 9 liter/flush

• Number of Student = 40 person

• Frequency of Flushing = 5 times/day

• Average Usage Toilet Per day = 1800 liter/day

• Landscaping = 10 min per/day

• Average landscaping usage = 200 liter/day

• Total usage per day = 2000 liter/day


MEAN ANNUAL RAINFALL

• Table 6.2 : Page 6-5 Chapter 6 MSMA 2nd Edition

7/27/2016

8


How much water can we harvest?

x

Catchment Area(m2) Amount of rainfall

(mm)

=x COLLECTION COEFFICIENCY

Volume of water received(Litres)

Rain Water Collected From Both Sides of the Roof

W

CALCULATION RAINWATER CAN BE HARVESTED

Roof Area = 240 m2 (8m x 30m)

Annual Rainfall = 2527 mm

Collection Efficiency = 85 %

Water can be harvested = 240 m2 x 2.53 x 0.85

= 516 m3/year

= 43.01 m3/month

= 1.44 m3/day

= 1440 liter/day

7/27/2016

9

ESTIMATED WATER DEMAND

MINIMUM STORAGE CAPACITY

7/27/2016

10

WATER DEMAND BASED ON FITTINGS

RAINWATER DEMAND (MSMA)

7/27/2016

11

RAINWATER DEMAND PER DAY

• Indoor Toilet (single flush) = 9 liter/flush

• Number of Student = 40 person

• Frequency of Flushing = 5 times/day

• Average Usage Toilet Per day= 1800 liter/day

• Landscaping = 10 min per/day

• Average landscaping usage = 200 liter/day

• Total usage per day = 2000 liter/day

CONVEYANCE`- GUTTER & RWDP

• Gutters are used to convey water from the roof to pipes to the RWH tank

• Gutter convey water through rain water down pipe (RWDP)• Rainwater may also collect from the surface via on site

detention system• Normally Gutter and RWDP size can be referred to to Architect

detail

7/27/2016

12


GUTTER & RWDP DESIGN

GUTTER & RWDP DESIGN

Gutter and RWDP sizing also can refer to NAHRIM Technical Guide No. 2

Gutter and RWDP sizing can be refer to Chapter 4 : MSMA 2nd Edition

7/27/2016

13

LEAF FILTER

• Prevents debris from entering the rainwater harvesting tank

• Improves water quality

• Reduces tank maintenance

• Size leaf filter shall follow RWDP

LEAF FILTER

7/27/2016

14

FIRST FLUSH DIVERTER

• First line of defence against getting contaminants into rainwater tank

• First Flush Water Diverters improve water quality, reduce tank maintenance and protect pumps by minimizing the first flush of water, which may contain contaminants from the roof,

from entering the tank.

RINWATER HARVESTING SYSTEM


FIRST FLUSH LEAF GUARD

7/27/2016

15

CALCULATE FIRST FLUSH DIVERTER(Table 6.3 Chapter 6 : MSMA 2nd Edition)

ROOF AREA(M2)FIRST FLUSH VOLUME

(LITRE)

Less than 100 m2 0.025 – 0.05

100 – 4356 m2 0.25 – 0.5

Greater than 4356 m2 2.5

Adopt first flush of 5 m3 if surface contains excessive soil, dust or debris.

CALCULATE FIRST FLUSH VOLUME

• First flush depth = 0.5 mm rainfall (MSMA 2nd Edition)

= 1.0 mm rainfall (NAHRIM)

• Roof Area = 240 m2

• First Flush Depth = 0.5 mm rainfall

• First flush down pipe = 150 mm

• Water to be drain out = 240 m2 x 0.0005

= 0.12 m3 or 120 litre

• First Flush Pipe Length = water to drain out (m3) /πr2

= 0.12 m3/(3.14 x 0.075 x 0.075)m2

= 2.83 m length.

• First Flush Pipe is 2.9 meter length to be installed before enter the tank

7/27/2016

16

TANK SIZE ESTIMATION• Simplified Approach• Roof Area = 240 m2

• Tank Size = 0.01 x 240 m2

= 2.4 m3

• Water Demand Per Day

• Average water demand perday = 2000 liter/day

• Average for 1 ½ day storage = 3000 liter/day

= 3 m3/day

• Rainwater Can Be Harvested/Day = 1440 liter/day

• Choose Tank Size = 4 m3


RWH TANK

• Rainwater tanks may be provided to collect rainwater from roof and gutter systems.

• These tanks can be used to:

a) provide water for non potable uses

b) on-site detention storage

• Tank material can be type of material :-

– HDPE

– Poly Tank

– Steel Tank

– FRP

7/27/2016

17

WATER FILTER

• The size of filter shall be determined by flow rate of the rainwater intended (litre/hour)


PUMPS

• Pumps needs to lift rainwater from lower to higher level & boosting the pressure

• Type of pump suitable for various conditions of use – booster, submersible etc

• Pumps need to calculate the flow rate and pressure head required

• Pump size and specification shall refer to mechanical drawing

7/27/2016

18


PROJECT : TABIKA KEMAS SELAYANG – FASA 1USAGE : TOILET FLUSHING & LANDSCAPING

RAINWATER TANK

FIRST FLUSH

OVER FLOW PIPE

WATER BACKUP

LEAF FILTER

DISTRIBUTION PIPE

RAINWATER HARVESTING SYSTEM – KEMAS SELAYANG

– FASA 2

• Rainwater collected from the roof

• Rainwater uses for gardening

• Water bills reduced 15% monthly

7/27/2016

19

PROJECT : TABIKA KEMAS SELAYANG – FASA 1USAGE : TOILET FLUSHING & LANDSCAPING

RAINWATER TANK

FIRST FLUSH

OVER FLOW PIPE

WATER BACKUP

LEAF FILTER

DISTRIBUTION PIPE


GARDENING AREA TOILET FLUSHING

7/27/2016

20


WATER TAP FOR GARDENING DISTRIBUTION PIPE TO TOILET

Thank You..

references - jabatan kerajaan tempatan...

Documents