This presentation was presented in 'The Lahore Project' Monthly Discussion Forum on Utility Infrastructure (Strom-water Management) by Mr.Wasif Ali, on 21st Aug.2013 at Dabistan-e-Iqbal, (2-S, Gulberg II) Lahore.

1. Utility Infrastructure of Lahore City
(Stormwater Drainage)
Engr. Wasif Ali
B.Sc. (Civil Engineering)
M.Sc. (Environmental Engineering)
The Lahore Project
Working Session

2. Presentation Outline
 Existing Scenario
 Stormwater Management Techniques
 Case Study…… Mohlanwal Area
 Design & Analysis of Stormwater Systems
 Conclusions & Recommendations
The Lahore Project
Working Session on
Utility Infrastructure
21 August 2013

3. Existing Scenario
 Frequent and Widespread Stormwater Flooding
 Unplanned Development Pattern
 Water Table Decline
 Limited Space & Funds for Drainage
 Poor Assessment of Existing Drainage facilities
 Authorities are in mode of crisis
The Lahore Project
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21 August 2013

4. Existing Scenario
The Lahore Project
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21 August 2013

5. Existing Scenario
 Groundwater Decline
Sr.
No
Location
Water Level below NSL (ft) Avg.
Decline
(ft/yr)Year Feet Year Feet
1 A-Block Gulberg 1977 40.75 2000 87.74 2.04
2 Nawan Kot Police Station 1981 30.83 2000 66.22 1.86
3 Takkia Lehri Shah 1978 33.75 2000 86.92 2.41
4 Singh Pura 1981 45.40 2000 86.59 2.16
5 Rehman Pura 1987 58.71 2000 94.46 2.75
6 Masti gate 1987 46.08 2000 85.11 3.00
8 Masoom Gunj 1987 26.57 2000 70.81 3.40
9 Avari Hotel 1987 70.68 2000 107.45 2.83
10 Jia Musa 1987 25.65 2000 37.72 0.93
Source: Integrated Master Plan of Lahore for 2021, NESPAKThe Lahore Project
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21 August 2013

6. Existing Scenario
 Design Rainfall Distribution Curve for Lahore (1953-2005)
Source: Pilot Balloon Observatory (PBO) LahoreThe Lahore Project
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21 August 2013

7. Existing Scenario
 Rainfall Distribution
Source: Pilot Balloon Observatory (PBO) LahoreThe Lahore Project
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Utility Infrastructure
21 August 2013

8. Stormwater Management Techniques
 Conventional Techniques
☼ Rapid Removal of Water
☼ Reactive Approach
☼ Increased Flooding
☼ Increased Erosion and Pollution
☼ Reduced Aquifer Recharge
☼ Complex Pipe Network
☼ Expensive
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9. Stormwater Management Techniques
 Alternative Techniques
☼ Nomenclature
☼ BMPs… Best Management Practices
☼ SUDS… Sustainable Urban Drainage Systems
☼ USM… Urban Stormwater Management
☼ Localized Stagnation
☼ Lesser Erosion & Pollutant Loads
☼ Aquifer Recharging
☼ Flexible Network
☼ Proactive Approach
☼ Economical
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10. Best Management Practices (BMPs)
 Green Roofs
 Rooftop Runoff Controls
 Bioretention / Recharge Garden
 Dry Well / Seepage Pit
 Pervious Pavements
 Vegetated Swale
 Infiltration Trench
 Infiltration basin
 Wet Pond / Retention Basin
The Lahore Project
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21 August 2013

11. Green Roofs
 Reduced & Delayed Runoff
 (up to 70% peak reduction)
 Insulation of Buildings
 Lower Energy Consumption
 Habitat for Birds and Insects
 Reduced Carbon Dioxide levels
 Higher Cost
 Leakage
 Harsh Conditions for Vegetation
 Higher Maintenance
Benefits
Limitations
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12. Rooftop Runoff Control
Benefits
Limitations  Limited Suitability for small houses
 Requires Proper Maintenance
 Pumping Cost may involve if sub surface storage
is provided
 Irrigation of Landscaped areas & Gardens
 Firefighting Storage
 (Building like WAPDA house, School etc)
 Reduced Peak Volume of Stormwater
 Reuse for Grey Water….i.e. flushing toilets.
 Reuse for Athletic Field Irrigation
 Cost Savings during Summer
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13. Rooftop Runoff Control
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14. Bioretention/Rain Garden
Limitations  Regular Inspection
 Rain Gardens may Require Watering in dry season
 Reduce Runoff Volume
 Filter Pollutants
 Recharge Groundwater
 Enhance Aesthetics
 Provide Habitat
Benefits
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21 August 2013

15. Bioretention/Rain Garden
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16. Dry Well/Seepage Pit
 2’ Separation to Bedrock and Water Table
 Min. 10’ distance from Foundation
 Overflow Outlet for Large Storms
 Min. One Observation Well.
 Maximum Drain-Down Time is 72 hours
Imp.
Features
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17. Pervious Pavements
Limitations
 Higher Construction and
Maintenance Costs
 Depends on Infiltration Rates of
Underlying Soils
 Less Durable
 Good for impervious areas
 Reduces runoff
 Increased infiltration
 Healthier vegetation
Benefits
The Lahore Project
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18. Pervious Pavements
Variations
1) Pervious Bituminous Asphalt
2) Porous Concrete 3) Pervious Pavers BlocksThe Lahore Project
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19. Vegetated Swale
Imp.
Features
 Significantly slow the rate of runoff
conveyance compared to pipes
 Attenuation & Infiltration of runoff
 Pollutants Removal
 Longitudinal slope = 1 to 6%
 Check Dams for steeper slopes
 Side slope = 3:1 to 5:1
 Bottom width = 2 to 8 ft
The Lahore Project
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21 August 2013

20. Vegetated Swale
1) Vegetated Swale with Infiltration Trench
3) Swale with Check Dams2) Grassed SwaleThe Lahore Project
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21 August 2013

21. Infiltration Trench
Benefits
Limitations
 Ground Water Recharging
 Stormwater Treatment
 Good for Small Sites with
Porous Soils
 Groundwater Contamination
 High Clogging Potential
 Significant Setback Requirements
 Geotechnical Testing Required
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22. Infiltration Basin
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23. Infiltration Basin
 100% Reduction in the Load Discharged to
Surface Waters
 Approximation of Pre-Development Hydrology
 Channel Erosion Control
 Not Appropriate for Industrial / Spill sites
 Not suitable on Fill-Sites or Steep Slopes
 Infiltration rate ≥ 0.5 and ≤ 2.4 inch/hr
 Difficult to Restore once Clogged.
Benefits
Limitations
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24. Wet Pond/Retention Basin
 Wildlife and Wetlands Habitat
 Aesthetic & Recreational Value
 Public Amenity when integrated
into a Park
 Water Quality Improvement
 Public Safety Concern
 Mosquito Breeding
 Cannot be Placed on steep slopes
Benefits
Limitations
The Lahore Project
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21 August 2013

25. Study Area
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26. Study Area
Master Plan
of the
Mohlanwal
The Lahore Project
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27. Study Area
 Building Bye-Laws
 LDA Land-Use Distribution for New Schemes
Sr.# Land Use Area Requirement
1 Open Spaces / Parks Not less than 7% of Total Scheme Area
2 Graveyard Not less than 2% of Total Scheme Area
3 Commercial Area Not more than 5% of Total Scheme Area
4 Public Buildings 2 to 10 %
 LDA Bye-Laws for Open Areas in Residential Units
Category
Area (Sft) Deduct
Car Porch
& Drive
Way
(Sft)
Net
Open
Area
(Sft)
%age
of
Open
AreaPlot
Open
Front Side Rear Total
2-kanal 9,000 1,500 1,800 750 4,050 600 3,450 38.3
1-Kanal 4,500 500 365 350 1,215 300 915 20.3
10-Marla 2,250 350 235 245 830 300 530 23.6
5-Marla 1,125 125 0 125 250 0 250 22.2The Lahore Project
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21 August 2013

28. Design & Analysis
of Stormwater Systems
☼ Stormwater Systems
 Conventional Techniques
 Partially Combined Sewer System (Model #1)
 Separate Storm Sewer System (Model #2)
 Alternative Techniques
 Storm Sewer System with Park Storage (Model #3)
 Storm Sewer System with Park & Lawn storage (Model #4)
☼ Analysis / Design Tool
 Storm Water management Module (SWMM)
The Lahore Project
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21 August 2013

29. Design & Analysis
of Stormwater Systems
The Lahore Project
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21 August 2013

30. Design & Analysis
of Stormwater Systems
Model
#
1 & 2
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21 August 2013

31. Design & Analysis
of Stormwater Systems
☼ Summary of Node Flooding
Node Type
2-Yrs 5-Yrs 10-Yrs
Total
Flooding
(acre-in)
Total
Minutes
Flooded
Total
Flooding
(acre-in)
Total
Minutes
Flooded
Total
Flooding
(acre-in)
Total
Minutes
Flooded
J1 Junction 15.59 364 34.98 384 48.57 393
J2 Junction 5.05 71 23.68 218 43.85 355
J3 Junction 0.01 0 0.01 0 2.81 48
J4 Junction 0 0 0.01 0 0.70 30
J5 Junction 8.79 372 15.31 393 20.36 402
J6 Junction 29.19 364 57.46 384 76.84 393
J7 Junction 5.04 121 18.61 354 31.39 363
J8 Junction 0.00 1 4.62 63 8.65 83
J9 Junction 10.09 374 18.29 399 25.46 412
J10 Junction 10.95 352 29.65 372 43.84 384
J11 Junction 21.67 362 51.63 380 75.32 387
J12 Junction 0 0 0 0 0.00 1
J13 Junction 0 0 0 0 0.00 0
J14 Junction 0 0 0 0 0 0
O1 Outfall 0 0 0 0 0 0
Model # 1
Partially
Combined
Sewer
System
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32. Design & Analysis
of Stormwater Systems
☼ Summary of Links
Link Type
Diameter
(inch)
Link Type
Diameter
(inch)
C1 Circular 9 C8 Circular 9
C2 Circular 15 C9 Circular 12
C3 Circular 24 C10 Circular 18
C4 Circular 24 C11 Circular 12
C5 Circular 9 C12 Circular 24
C6 Circular 12 C13 Circular 24
C7 Circular 15 C14 Circular 27
Model # 1
Partially
Combined
Sewer
System
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21 August 2013

33. Design & Analysis
of Stormwater Systems
Model # 3
Storm
Sewer
System
With
Park
Storage
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21 August 2013

34. Design & Analysis
of Stormwater Systems
Model # 4
Storm
Sewer
System
With
Park &
Lawn
Storage
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21 August 2013

35. Design & Analysis
of Stormwater Systems
☼ Evaluation of different Models
 Flooding
Velocity
%age Peak Domestic flow as Stormwater Allowance
Provided as per
WASA Criteria
Required as per SWMM Analysis
Return Period
fps 2-Yrs 5-Yrs 10-Yrs
2.0 100 345 635 1000
2.5 100 460 825 1275
3.0 100 570 1005 1550
Comparison of Stormwater Allowance for different Frequencies
 Length-weighted Diameter {(D1xL1+D2L2+……..DnLn) / ΣLn}
 Cost of the System
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36. Design & Analysis
of Stormwater Systems
Type of
Stormwater System
Length-weighted Diameter
(inch)
Cost
(Millions Rs.)
2-Yrs 5-Yrs 10-Yrs 2-Yrs 5-Yrs 10-Yrs
Combined System 16 16 16 2.6 2.6 2.6
Separate System 34 45 52 6.7 11.0 14.7
Storm Sewer with Park
Storage
16 22 26 2.9 4.4 5.5
Storm Sewer with Park
and Lawn Storage
09 16 19 1.5 2.9 3.5
 Summary of the Network Sizing & Cost
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37. Conclusions & Recommendations
1) Mean average decline in ground water table of Lahore comes to be
2.03 ft/yr which clearly shows the need to implement the alternative
storm water techniques instead of conventional techniques.
2) The “knee of curve” for Lahore is in the range of 0.60 to 1.00 inch of
rainfall hence BMPs will be most efficient and economical in Lahore
if they target the storm event having the value lesser than 1.0 inch.
3) The value of “Storm water Allowance”, as per WASA design criteria
is taken as 100% of peak domestic flow but this study shows that it
varies from 345% to 1000% for 2-yrs and 10-yrs return period
respectively. Hence the value suggested by WASA is of no use if
one is designing combined system for No-flooding condition.
☼ Conclusions
The Lahore Project
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21 August 2013

38. 4) This study shows that ample reduction in conduit size can be achieved
by utilizing BMPs. For example the ultimate diameter for separate
sewer system are 42, 54 and 66 inch respectively for 2, 5 and 10 year
return period while using only two BMPs (i.e. Lawn Depression and
Park Storage) the ultimate diameters are 12, 21 and 24 inch for 2,5 and
10 year return period respectively.
5) Common misconception about the additional land requirement for any
storage facility can be wrecked by the results of this study that even
using the current open space regulation of LDA, 89% of peak flow
reduction can be achieved through BMPs.
Conclusions & Recommendations
☼ Conclusions
The Lahore Project
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21 August 2013

39. 1) The rainfall data is a basic requirement for the analysis purposes.
Continuous recording of rainfall is required to develop a shorter time
interval for rain fall intensity curves. Presently most of the data is in 3-hr
interval form and only a limited record of continuous recording rain-
gages is available. It is strongly recommended that meteorological
department should make such arrangements that rainfall can be
recorded up to 5 minutes interval.
2) Main emphasis of the bye-laws in Lahore is on ventilation and sunlight
criteria. No provision is made in these bye-laws to meet the sustainable
drainage. Hence it is needed to develop such guidelines by which
sustainable development can be achieved.
Conclusions & Recommendations
☼ Recommendations
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21 August 2013

40. 3) Peak and quantity of the stormwater flow should be reduced by the
application of storage BMPs. Government agencies like WASA should
prepare a master drainage plan for all major drains (natural as well as
man-made) and a specific quantity and peak of flow should be allotted
to each and every section of these drains. A stormwater tax should be
imposed if society discharges any additional flow than that of allotted by
the competent authority like WASA.
4) The LDA should encourage the vertical growth so that more and more
space can be utilized for the BMPs. Constructed wetland, wet ponds
and many other storage facilities require a huge land area. It will not
only increase the ground water recharging but at the same time such
spaces can be utilized as recreational spot, walkways and children’s
play areas.
Conclusions & Recommendations
☼ Recommendations
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41. 5) Most of the BMP techniques can only be implemented by the active
public participation hence educational and awareness campaigns
should be set up for local community groups. Electronic media can play
an important role in this regard.
6) Because of rapid urbanization, extensive and more frequent flooding
has been occurring in recent years and the continued use of
conventional techniques to stormwater management result in
municipalities becoming victims of their municipality’s development
success therefore it makes sense to implement the Alternative
techniques to stormwater management.
Conclusions & Recommendations
☼ Recommendations
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42. Questions & Answers
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