Raw water intake The most common type are

Raw water intake

• The most common type are: 1. The floating intake. 2. Submerged intake. 3. Tower intake.

Intake site selection 1. Water quality 2. Water depth 3. Stream velocity 4. Proximity to water treatment plant 5. Environmental impact. 6. Hazard to navigation.

• Screening : Screening as a unit that removes suspended matter from water. screen may be classified as coarse and fine screen. Coarse screen Consist of vertical bars spaced with 5 – 8 CM of clear opening.

Fine screen are used to remove samller objects that may damage pumps or other equipments. Screen with small opening will retain large quality of material, therefore they may require automatic cleaning.

Microstrainer • Microstrainser is are used for the removal of plankton and algae from imounded water

BAR RACKS Hydraulic Loss h. L = 1 0. 7 ν 2 - v 2 1 2 g h. L = head loss 0. 7 = An empirical discharge coefficient to account for turbulence and eddy losses.

v = velocity of flow through the opening of the bar racks v = proposed velocity in the upstream 1 channel g = accelaration due to gravity, (m/s 2)

Fine Screen h. L = 1 Q 2 C (2 g) A Q = discharge through screen A = effective open area of submerged screen, m 2 C = coefficient of discharge for the screen ( typical, C = 0. 84)

Fine Screen h. L = 1 Q 2 C (2 g) A Q = discharge through screen A = effective open area of submerged screen, m 2 C = coefficient of discharge for the screen ( typical, C = 0. 84) 14 of

Intake Works Most grit chambers are designed to capture particles of 0. 2 mm diameter and specific gravity of 2. 65 The usual design parameter are a surface loading rate, Q/A of 100 m 3/h/m 2 at maximum flow and downstream velocity of 0. 3 m/s. • Range of surface rate 27 m 3/h/m 2 to 100 m 3/h/m 2 • Retention time is 90 seconds

DESIGN OF INTAKE WORKS Treatment Plant Capacity = 80 MLD Inplant Used (Provide) = 6% In flow = 80 x 1. 06 = 84. 8 MLD = 3, 533 m 3/h

SIZING OF INTAKE Design Criteria, Surface Load, Vs = 50 m 3/h/m 2 ( Design Range 27 -100 m 3/h/m 2 ) Area Required A = Q Vs = 3, 533 m 3/h 50 m 3/h/m 2 = 70. 66 m 2

SIZING OF INTAKE Provide 2 Channels Area per channel = 70. 66 m 2 2 = 35. 33 m 2 4 B 2 = 35. 33 m 2 B = 2. 97 m Consider L : B ratio of 4 : 1

THE SIZE OF THE INTAKE WORKS 6. 99 2. 97 350 12. 58 m 11. 88 m 350 350

B B 500 HWL NLL LWL 0. 66 m

HWL NWL LWL 0. 66 m 1 m River load

PROPOSED APPROACHING VELOCITY m/s Q = Av A = = PROPOSED WIDTH Water depth, = d = 1. 63 2. 97 d = 0. 55 m = 3533 m 3/h 2 channels x 0. 3 m/s 1. 63 m 2 2. 97 m 0. 3

CONSIDERING 20% OF SILTATION d 1 Depth below the L. W. L, d 1 = 0. 66 m

OTHER FACILITIES AT INTAKE 1. LIFTING FRAME FOR PUMPS 2. SAND INJECTORS SYSTEM FOR SAND REMOVAL 3. SURGE SUSPRESSION SYSTEM 4. ACCESS LADDERS 5. ELECTRICAL SWITCH BOARD

6. ELECTRICAL SUBSTATION (if required) 7. LIFTING FACILITIES FOR FINE SCREEN (manual) 8. PARAMETER FENCING WITH ENTRANCE GATE 9. COMPOUND LIGHTING 10. ACCESS ROAD 11. CCTV, SCADA AND TELEMETRY SYSTEM 12. SECURITY GUARD HOUSE