PUBLIC REALM UPLIFTING OF AL DAHAB
SQUARE IN JEDDAH HISTORIC DISTRIC
CIVIL CALCULATIONS
JULY 2020
Prepared by:
Contents
1. Potable Water / Fire Water ................................................................................................................. 3
1.1. Average Daily Domestic Water Consumption............................................................................... 3
1.2. Design Flows ................................................................................................................................. 3
1.3. Pressure Requirement .................................................................................................................. 3
1.4. Velocity Requirements .................................................................................................................. 3
1.5. Hydraulic Analysis ......................................................................................................................... 3
1.6. Evaluate the capacity of the 250 dia uPVC ................................................................................... 4
1.7. Conclusion ..................................................................................................................................... 5
2. Sanitary Sewer Calculations. ................................................................................................................ 5
2.1. Sanitary Sewer Sources ................................................................................................................. 5
2.2. The Average Sanitary Sewer Discharge ........................................................................................ 5
2.3. Maximum Sanitary Sewer Discharges ........................................................................................... 5
2.4. Minimum Cover of Pipes ............................................................................................................... 6
2.5. Manhole Spacing ........................................................................................................................... 6
2.6. Hydraulic Design ........................................................................................................................... 6
2.7. Capacity of 200mm dia. pipe @ minimum slope of 0.05% ........................................................... 6
2.8. Conclusion ..................................................................................................................................... 7
3. Attachments ......................................................................................................................................... 7
4. Storm Drainage Calculations .............................................................................................................. 10
4.1. Design basis and delineation area .............................................................................................. 10
4.2. Calculations ................................................................................................................................. 10
4.3. Conclusion: .................................................................................................................................. 10
4.4. STORM DRAINAGE SYSTEM CALCULATION................................................................................. 12
5. Irrigation Calculations ........................................................................................................................ 13
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1. Potable Water / Fire Water
1.1. Average Daily Domestic Water Consumption
Table 1 - Water Consumption and Demands
SOUK QABEL
Land Use Occupancy Average Peak Average Peak
Water Water Water Water
Demand Demand Demand Demand
(m3/day) (m3/day) (l/s) (l/s)
Offices 55 4.40 6.60 0.05 0.08
Retail 1211 223.32 334.98 2.58 3.88
Residential 62 9.0 13.50 0.10 0.16
Cultural* 92 6.58 9.87 0.08 0.11
Mosques* - 4.08 6.12 0.05 0.07
Total 1793 247.38 371.07 2.86 4.29
Reference: Al Balad Master Plan 2019, Chapter 16.
1.2. Design Flows
The potable water supply distribution network is designed to satisfy the peak hour demand
(Potable Water), defined by Table 1 - Water Consumption and Demands.
1.3. Pressure Requirement
The minimum pressure required at the remotest fire hydrant during fire flow conditions
shall not be less than 20 psig or 140 kPa.
As per the drawings layout water all tie in connection with existing shall not less than
20 PSI.
During normal conditions the minimum pressure on the potable water system shall be
275 kPa or 40 psig.
1.4. Velocity Requirements
Minimum velocity 0.70
Maximum velocity 2 m/s
1.5. Hydraulic Analysis
The analysis of flow in the pipe network shall assume an appropriate “C” value
depending on the pipe material to be used in the Hazen-Williams formula.
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Hazen-Williams Formula:
V= 0.85 C (d)0.63 S00.54
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Hf = 6.85 L (V)1.852 (1 )
C d1.17
S0= 10.7 (Q)1.852
d4.87 C
Where:
V = Velocity in meters per second
C = Roughness coefficient of pipe
d = Pipe inside diameters in meter
L = Pipe length in meters
hf= Hydraulic head losses in pipeline in meters
S0= Hydraulic slope
Q = Flow rate cubic meter per second
Hazen-Williams roughness coefficient “C” value for various pipe materials.
Description of Pipe Value of “C”
plastic pipe 150
The hydraulics of the water network shall analyze on the following conditions:
a) Peak Flow
b) Firefighting water flow 1000 gpm (hydrant)
1.6. Evaluate the capacity of the 250 dia uPVC
The total Flow = 0.0042947917 domestic use + Fire Hydrant flow = 0.06309
Accordingly, total flow = 0.067384 m3/sec
Assuming velocity = 1.40 m/s
Using the formula
Q=AV
A = 0.0490625
Pipe diameter (D) = 250 mm
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1.7. Conclusion
Main pipe line diameter at Qabel Street and Souq Al Alawi = 250 mm
2. Sanitary Sewer Calculations.
The main factors considered in the design of Sanitary Sewer gravity system are as follows:
Sanitary Sewer sources.
Average and maximum wastewater discharges.
Hydraulic design equation.
Hydraulic design constraints for pipes.
Pipes materials.
2.1. Sanitary Sewer Sources
The Sanitary Sewer sources within the project area are as follows:
1. Sanitary Sewer discharges.
The main factors that affect the Sanitary Sewer discharges are as follows:
a. The land use and population density within the project area.
b. The peak factors, which depend on the population count.
2.2. The Average Sanitary Sewer Discharge
The Sanitary Sewer discharge quantities depend on the potable water consumptions, as
the wastewater discharges are considered 80-90% of the consumed potable water
quantities. For this project, this ratio will be taken 85%.
2.3. Maximum Sanitary Sewer Discharges
Table 2–Sanitary Sewer Demands
SOUK QABEL
Land Use Occupancy Average Babbitt Peak Average Peak
Peak
Sewage Factor Sewage Sewage Sewage
Load Load Load Load
(m3/day) (m3/day) (l/s) (l/s)
Offices 55 3.74 5 18.7 0.04 0.22
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Retail 3722 189.82 4.02 762.41 2.20 8.82
Residential 36 7.65 5 38.25 0.09 0.44
Cultural* 94 5.59 5 27.97 0.06 0.32
Mosques* 136 3.47 5 17.34 0.04 0.20
Total 3813 210.27 3.96 832.98 2.43 9.64
Reference: Al Balad Master Plan 2019, Chapter 16.
2.4. Minimum Cover of Pipes
Generally, the minimum pipe ground cover is 1.20m. Wherever pipes are found to run at
depths shallower than 1.20 m, concrete encasement shall be provided.
2.5. Manhole Spacing
The maximum spacing for the sewage network manholes shall be taken as follow:
100 to 150m for sewage pipes.
Manholes are to be provided at changes in the horizontal or vertical direction and
at changes in pipe diameter.
2.6. Hydraulic Design
Manning’s formula is used for the hydraulic design calculation of the gravity sewer
network.
Where:
Q: discharge, in m3/s
n: roughness coefficient of the Pipe, 0.013
A: flow area, in m2
R: hydraulic radius, in m
S: slope of the conduit, in m/m
The following criteria will be adopted:
Maximum depth of flow in the sewer pipe = 75% of the full pipe diameter
Friction coefficient n for gravity sewer pipes = 0.013 for VC
Minimum self-cleansing velocity = 0.6 m/s
Maximum flow velocity = 3.0 m/s
Minimum pipe gradients will be selected to maintain and conform to the minimum
self-cleansing velocity of 0.6m/s.
2.7. Capacity of 200mm dia. pipe @ minimum slope of 0.05%
Q = Area x Velocity
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A = π d2 = 3.1416 x (0.20)2 = 0.031 cu m
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V = R2/3 x S1/2 = (0.049)2/3 x (0.005)1/2 = 0.738 m/s
n 0.013
Q = 0.023 cu m/s (flowing full Capacity)
2.8. Conclusion
Q = 0.023 cu m/s (flowing full Capacity), and Jeddah Historic District flow = 0.00964 cu
m/s (832.98 Cu m /s as per Table 2 from Al Balad Master Plan 2019, Chapter 16)
And Minimum Pipe diameter = 200 mm, accordingly the main lines pipe size 200 mm.
3. Attachments
Attachment 01 - the calculations for water & fire Water.
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4. Storm Drainage Calculations
4.1. Design basis and delineation area
Storm Drainage calculation is based on the submitted design basis.
Storm drainage delineation plan is prepared using the Google Map, showing the limit of
drainage tributary area (for the Project site only), calculated area in square meter, flow
direction and the Tie - in points of the proposed Drainage system to the existing Al Balad
Regeneration Development Plan Infrastructure Masterplan (see Figure 1).
4.2. Calculations
Calculation is prepared based on Rational Formula. The calculated size of the
pipelines varies from 400 mm diameter to 750mm diameter pipe based on the delineated
area in each segment. (see Table 1 Storm Drainage calculation)
4.3. Conclusion:
The calculation shown in Figure 1 was based on project area tributary area only.
However, since the project will be connected to Al Balad Regeneration Development
Plan Infrastructure Masterplanpart3, size of the pipe adopted in the proposed drainage
system is 1700 mm diameter pipe. (see Storm Water Drainage Plan Drawing no. CIV-
20012 Sheet 1)
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Figure 1- Storm Water Drainage Delineation Plan
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4.4. STORM DRAINAGE SYSTEM CALCULATION
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5. Irrigation Calculations
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