8/9/2019 Weaverley Housing Coop Design Report.pdf
1/21
WEAVERLEY HOUSING COOPERATIVE
WEAVERLEY HOUSING COOPERATIVE
INFRASTRUCTURE DESIGN PARAMETERS
FOR RESIDENTIAL DEVELOPMENT
D NDE CIVIL PROJECTS
CONSULTING ENGINEERS
Civil &Structural Engineering Consulting
P.O Box 6851HarareTel. 04-771484Cel. 0773 282 522
FEBRUARY 2015
8/9/2019 Weaverley Housing Coop Design Report.pdf
2/21
2
WEAVERLEY COOPERATIVE HOUSING
INFRASTRUCTURE DESIGN
PARAMETERS FOR RESIDENTIAL DEVELOPMENT
CONTENTS LIST
Page
1. INTRODUCTION 4
1.1 General 4
1.2 Town Planning 5
1.2.1 Town Planning Development 5
1.2.2 Survey & S.G Co-ordinated Plans 5
2. SITE DESCRIPTION 6
2.1 Location 6
2.2 Topography 6
2.3 Geology 6
3. PARAMETERS OF DESIGN 7
3.1 Design References 7
4. CIVIL ENGINEERING SERVICES : RETICULATION 8
4.1 Local Roads 8
4.1.1 General 8
4.1.2 Road Cross Section 8
4.1.3 Horizontal Alignment 9
4.1.4 Vertical Alignment 104.2 Local Stormwater Control 11
8/9/2019 Weaverley Housing Coop Design Report.pdf
3/21
3
4.2.1 General 11
4.2.2 Design 11
4.2.3 Materials 12
4.2.4 Ancillary Stormwater Control 12
4.2.5 Sub Surface Drainage 13
4.3 Sewer Reticulation 13
4.3.1 Sewer Reticulation 13
4.3.2 Sewer Reticulation Design 13
4.3.3 Computer Analysis 14
4.3.4 Pipeline Layout and Gradients 15
4.3.5 Material Specifications 15
4.4 Water Reticulation 16
4.4.1 Water Demand 16
4.4.2 Water Reticulation Designs Development 16
4.4.3 Design Parameters 16
4.4.4 Computer Analysis 18
4.4.5 Pipe Materials Specification 18
8/9/2019 Weaverley Housing Coop Design Report.pdf
4/21
4
1. INTRODUCTION
1.1 General
Dande Civils was appointed by Waverley Cooperative for the design of their
infrastructure services for 271 stands for residential purpose. This design report
forms part of the Consultants’ appointment and covers the strategy for the
planning, designing and construction of the of the infrastructure services.
Weaverley cooperative intend to develop the site with the installation of Civil
reticulation, for the 271 stands , with associated bulk and link infrastructure on
behalf of Kadoma Municipality.
The development principles to be adopted by the development team of Town
Planners, Engineers and Architects is to develop a township with ‘green’ areas,
adopt green engineering principles and appropriate engineering technologies
as is practical.
Engineering Reticulation Services will therefore be as follows;
Civil Engineering
- Kerbed and surfaced roads
- Stormwater control primarily in the roads, then channelled to
open channels as topography dictates
- Waterborne sewerage reticulation
- Individual metered water supply to each stand.
- Fire protection for the development within the water reticulationnetwork.
8/9/2019 Weaverley Housing Coop Design Report.pdf
5/21
5
1.2 Town Planning
1.2.1 Town Planning Development
The original Town Planning from the own plan developed by the
Regional Office of the Department of Physical Planning was used. This
town plan was the layout used for the initial civil design.
1.2.2 Survey & S.G Coordinated Plans
Topographical Survey
Detail ‘on site’ topographical survey is required for detailed
design of,
• Sewer reticulation
• Roads reticulation
SG Coordinated Plans & Site Pegging
SG Plan
• The SG coordination plan is dependent upon the Town Planning
• The coordinated Town Plan was received by Dande Civils for
detail design in January 2015.
8/9/2019 Weaverley Housing Coop Design Report.pdf
6/21
6
2. SITE DESCRIPTION
2.1. Location
The proposed housing development is located on portions of Subdivision A of
Plot 3 of Railway Farm 9 situate in the district of Kadoma and is situated in
Kadoma.
2.2 Topography
The site generally slopes down towards stand number 3666
2.3 Geology
Attached is a preliminary site assessment of the insitu soils – Appendix 1.
Material is generally SG5-SG9 material with a few areas with SG3
8/9/2019 Weaverley Housing Coop Design Report.pdf
7/21
7
3. PARAMETERS OF DESIGN
3.1 Design References
CIVIL
ZIMBABWE
Ministry of Local Government & Housing for Water, Sewerage, Road
& S/W BCHOD : 1981
- Design Approach to Water and Sewerage Problems Relative to Urban
(predominantly High Density) and Rural Communities in
Zimbabwe.
SOUTH AFRICA
- Guidelines for the provision of Engineering Services&
Amenities in residential township Development – South Africa
(Red Book)
8/9/2019 Weaverley Housing Coop Design Report.pdf
8/21
8
4 CIVIL ENGINEERING SERVICES : RETICULATION
4.1. Local Roads
4.1.1 General
The road reticulation system within the Township is developed on the following
principles :-
- To provide all weather access to stands – Class 5a/5b
- To provide linkage to the distribution roads by vehicle or bus – Class 4
- All Class 5 and Class 4 roads to be designed to transport Stormwater within
the township and to avoid potential Stormwater damage to properties.
Design speed on the roads is to be limited to 40 km/hr by the use of traffic calming
measures mini traffic circles or speed bumps. However, and where possible, the design
stopping / site distance is to be designed for a traffic speed of 60km to ensure additional
safety within the local streets for pedestrian movement.
Adjacent all local streets and the bus route, one side only , paved footways are to be
installed providing all weather pedestrian movement facility.
Roads geometric and pavement design has been undertaken with criteria from the
Guidelines for the Provision of Engineering Services in Residential Township issued by the
National Housing Board SA.
4.1.2 Road Cross-Sections
Class 4 Road- Local bus route
18m Road Reserve
- Road carriageway offset to allow for Electrical HT Servitude
- Carriageway 6m wide with 2½ % crossfall
- Edging support of pre cast concrete mountable kerb on low side and pre cast
concrete edging on high side
- 900mm wide footway on low side (Acts with the road as an additional paved
S/W channel in the event of substantial storm water discharge.
- Road reserves to be compacted to grades to assist S/W control and stand
access as detailed on the typical road section detail drawing.
- Reserves to be top soiled and grass seeded to avoid erosion and
provide a visually pleasing finish to the reserves.
- Classification
8/9/2019 Weaverley Housing Coop Design Report.pdf
9/21
8/9/2019 Weaverley Housing Coop Design Report.pdf
10/21
10
10m for class 5a to 4
15m for class 4 to class 3
4.1.4 Vertical Alignment
Road Gradient
Class 4 Max gradient 10% Class 5
Max gradient 12%
In certain short sections of roads these grades will need to be exceeded to ensure
stormwater control and avoidance of erosion to reserves, as the dictates of the topography
and design in minimizing cut/fill requirements.
Vertical Curves
Class 4 : Verified curve length 40 m min
2% change of grade – no curve required
Class 5 : Vertical Curve Length 20 m min
3% change of grade – no curve required
Access junction between roads -an allowance of up to 5% change of grade with no
vertical curve can be implemented as a valley between road crossfall and vertical
alignment of the adjoining road ensuring minimum cut/fill and avoiding potential
ponding of stormwater discharge from the road junction.
Pavement Design
Road Class 4 : Category UB 0.05≥3 E80s : Class E1
Road Class 5a/5b : Category UC/UD < 0.2 E80s : Class ER / EO
Roads to be designed with allowance for const ruction traffic use.
General CBR Min 10 (3 < 7 in vlei areas)
Roads to be granular material with pre mix surfacing
Footways to be granular material with 60mmblock paving surfacing and
cement stabilized base.
8/9/2019 Weaverley Housing Coop Design Report.pdf
11/21
11
Bus bays to be 80mm block paving and cement stabilized base.
Design will be based on the catalogue of designs in the Red Book Section 6
Appendix 5 to suit the relevant road category and traffic E80 Class as
designated above and to be based on granular bases in moderate to dry
region Figure 5A.
Note: For Class 5b roads E/O compaction of G5 material to obtain a CBR of >60 will be
used for the road base material to limit the import of G4 / or crusher run base material.
4.2 Local Storm-water Control
4.2.1 General
As noted in Section 4.1 the local residential access roads are to be utilized as far as
possible to transmit localized Storm-water discharge to U/G pipe system or side
drains.
The pipe system, side drains or direct discharge from the roads via kerb chute outlets
will transfer the storm-water discharge into the three existing drainage channels on the
northern side of the development area of 271 stands.
Local design storm intensity will be for 1:5 storm discharge with 1: 10 year storm
surcharge onto the roads.
The roads and road reserves will also act as the major S/W discharge conduit for
storms up to 1:50 year intensity.
4.2.2 Design
Storm-water discharge design will be based on the Rational formula : Q =
AIC m³/sec360
Intensity will vary to suit the time of concentration (Tc) based on :
- the return storm intensity
- Topography
- Vegetations / Ground coverage
- Paved areas
8/9/2019 Weaverley Housing Coop Design Report.pdf
12/21
12
- Channelized Flow
- Mean annual Rainfall of 900mm / annum
4.2.3 Materials /Installation
- Inlets to U/G pipework will be via kerb inlets or gulley inlets with concrete inlet
chambers and brick manhole chambers
- Concrete inlet channels will be used to increase the capacity of the standard
2m long Kerb inlets with end inlet to the KI to cater for the additional flow.
- Concrete chute outlets (precast and insitu) will be used on kerbed roads to
discharge to open drainage systems
- Pipework will be precast concrete pipes with spigot and socket flexible joints
equivalent to Class C pipework with Class B bedding – full granular surround andbedding factor 1.8.
- Cover under roads to be 1m to soffit but with concrete surround, 750 mm to soffit
will be acceptable provided a minimum of 450 mm cover to the pipe is available
when the road pavement is being constructed.
- Open drains will be designed to suit the required flows with concrete or stone lining
to avoid erosion where required.
- Manholes are to be brick manholes with full depth benching to ensure
constant velocity transfer through the manholes. The shape of the manhole is
dependent upon pipe sizing, number of inlets and turning requirements Covers to
be cost iron, or cast iron frame with concrete infill in open areas.
4.2.4 Ancillary Stormwater Contro l
To assist Stormwater discharge certain stands will be deemed Stormwater servitudes
to assist the control of major Stormwater run-off and avoid damage to houses if theywere to be constructed in that location.
These areas generally occur :
- At the bottom of steep roads when the flow ‘cannot’ change direction due to
velocities or horizontal alignment requirements of the Town Planning Layout
- Transfer of pipework or open drains to avoid bends and major direction
changes
- Areas that will be damaged with flood discharge
The open areas will generally be graded to form a central shallow V drain which may or
8/9/2019 Weaverley Housing Coop Design Report.pdf
13/21
13
may not have the invert lined dependent upon stormwater discharge velocities.
However, as drain lining can also act as paved walkways I is considered that lining of the
invert should be undertaken
4.2.5 Sub Surface Drainage
- Due to the topography and the type of soil ground water is not expected in
many areas. However, areas where ground water may be encountered are :
- Potential perched water tables at the intersection of the granite sills and
granite ‘whale backs’
In these areas single aggregate stone bedding will be used to ensure protection to
underground pipework and open concrete lined drains and underground fin drains
will be installed adjacent roads to protect the road pavement.
4.3 Sewer Reticulation
4.3.1 Sewer Capacity
The Design Approach to Water and Sewerage Problems Relative to Urban
(Predominantly High Density) and Rural Communities in Zimbabwe and Guidelines
for the Provision of Engineering Services and Amenities in Townships Development-
South Africa identify typical water consumption rates in urban centers as:
Item Description Return to Sewer Design Guideline
1 Medium Income 70% Water Demand +
15% for S/W ingress.
850liters/stand/day
Zimbabwe Guidelines
4.3.2 Sewer Reticulation Design
The designs developed for sewer reticulation are based on data containedabove. Designs have taken into account the following.
- The proposed phasing of the development.
- The availability of materials and cost
- Contributing figures for sewage based upon water consumption figures
- Projected population figures
- Proposed types of housing units
- Pumping Station requirements
- Ease of maintenance
8/9/2019 Weaverley Housing Coop Design Report.pdf
14/21
14
Sewerage reticulation is mid-block where the plan and terrain permits it. The
sewer lines are located at 1.0 meter from the stand (plot) boundary.
The minimum pipe size is 110 millimeters in diameter. (O/D UPVC)
Sewage velocities have been designed to be high enough to transport solids,
but not so high that scouring of pipes would occur. Minimum velocities for
design have been achieved at the daily peak, which is not less than 0.6 m/s
with pipe flow 0.5D.
Peak flow factors have been limited to 5.25 x dry weather flow which is the
requirement to meet the blue standard of reticulation design as per Zimbabwe
regulations.
Stand connections are to be Y-connections, capped and attached to markers
to indicate their location. Each connection shall be located at the lower end of
the stand. If convenient erf connection will be made directly to the sewer line
M.H.
The design for connections has been based on 1:60 fall from any point on the
stand GL. +450mm (min) to give a minimum connection depth to the main
161mm dia sewer line.
Manholes have been located at a maximum spacing of 80m for 110mm
diameter pipes and 90m for pipes of 225mm diameter and above. Manholes
locations for larger diameter pipes have been designed to accommodate the
maintenance equipment available to the maintaining authority.
4.3.3 Computer Analysis
The sewer reticulation will be analyzed by Autocad CIVIL 3D software
package that carries out the pipe line hydraulic calculations for design flow
and maximum flow. The software out data is listed below:
• Longitudinal sections of sewer line annotated automatically with pipe
specifications, diameter and bedding specifications.
• Hydraulic information also placed automatically on longitudinal section.
• Manholes are numbered and sorted in branch order.
•
Pipes are numbered and sorted.• Manhole / pipe topology automatically determined
8/9/2019 Weaverley Housing Coop Design Report.pdf
15/21
15
• Pipe length calculated and totaled.
• Ground and invert levels determined at special chainages such as pipe or
road crossings.
• Manhole invert
• Pipe grades
• Drop manholes
• Pipe earthworks excavation quantities for all branches in the network,
pipeline layout and gradients
4.3.4 Pipeline Layout and Gradients
The sewers are laid with a minimum cover of 750mm depth between stands and
900mm Min cover elsewhere.
Road crossing are to be 1.25m depth to soffit to allow for road construction to be
undertaken without damage to any installed sewers.
Diameter (mm) Gradients
Maximum Minimum
160 1:10 1:120
200 1:16 1:150
250 1:24 1:200
315 1:30 1:300
400 1:40 1:350
675 1:70 1:600
Note : 1 in 80 is the minimum grade at the start of a sewer run
4.3.5 Material Specification
The pipeline material to be used is uPVC pipes sewer class 34 with flexible spigot
and socket joints for all sewer reticulation. Pipework above ground on pipe bridge
sections will be Mild Steel coated and painted as specified with Viking Johnson
Coupling Joints to allow for expansion.
Manholes are to be pre-cast concrete rings 1m dia unless noted on the drawings.
8/9/2019 Weaverley Housing Coop Design Report.pdf
16/21
16
4.4 Water Reticulation
4.4.1 Water Demand
Item Description Water Demand Design Guideline
1 Medium Income 1000liters/stand/day South African
Guidelines
2 Schools - Day 20liters/ pupil/day Zimbabwe Guidelines
3 Shops 20 liters / Employee Zimbabwe Guidelines
4 Bars 300 liters / Stand Zimbabwe Guidelines
5 Offices 20 liters / Employee Zimbabwe Guidelines
6 Dry services industry 10 000 -15 000 liters
/Ha
Zimbabwe Guidelines
4.4.2 Water Reticulation Designs Developed
The designs developed for water reticulation are based on data contained in
the above documentation.
Designs have taken into account the following :-
Phase 1
- 271 Units + associated infrastructure
- Balanced reticulation with the 271 reticulation of units for
Phase 1 inclusive of supply line from reservoirs
- Peak flows @ 1.8 to 3 peak hourly factors
- Average Flow + Fire Flow from 1no. Hydrant to be used for final pipe
sizing.
4.4.3 Design Parameters
Item Description Design Guideline
1 Water Demand per stand 400m2 stand.
Medium density – 1000liters per day
South Africa Guidelines
2 Peak hourly factor 3 Zimbabwe Guidelines
3 Minimum Residual pressures at supply points 15m to
20m
Maximum Static pressure 60m
Zimbabwe Guidelines
8/9/2019 Weaverley Housing Coop Design Report.pdf
17/21
17
4 Design Velocity between 0.5m/s to 2m/s Zimbabwe Guidelines
5 Cover over pipelines
Stand connection 450mm
In gardens 750mm
Under roads 1250mm
Zimbabwe Guidelines
6 Fire Flow
Low Risk area. One hydrant to Discharge at any one
time.
Hydrants at 240m coverage / spacing
Flow Rate 15liters per second.
Flow Time 1 hour.
Minimum Diameter of reticulation with Fire main
75mm diameter.
Adjacent to Institutional centers - additional Fire
Hydrant
South Africa Guidelines
Zimbabwe Guidelines
7 Institu tional Demand
Schools – Boarding 80 liters / Boarding pupil
Schools - Day 20 liters /Day pupil
Hospitals-200 - 400 liters /Bed
Primary Healthcare Centre- 10 liters /Out patient
Hotels 300 – 500 liters /Bed
Hostels/Rest Camps 200 - 300 liters/ Bed
Commerce or Administration
Shops 20 liters / Employee
Bars 300 liters / Stand
Zimbabwe Guidelines
Zimbabwe Guidelines
8/9/2019 Weaverley Housing Coop Design Report.pdf
18/21
18
Offices 20 liters / Employee
Industry
These will vary considerably according
to processes used.
Dry services industry 10 000 -15 000 liters /Ha
Wet Industrial to be individually
assessed.
Zimbabwe Guidelines
8 Peak Demand Zoned Areas
Between min 1.8 max 3.5
SA Guidelines
4.4.4 Computer Analysis
The water reticulation system is analyzed by Epanet software package
that carries out a static analysis and a time simulation of the network.
The software out data is listed below:
Hydraulic results for each water pipe include:
• Diameter Chosen (mm)
•
Flow (l/s)• Velocity (m/s)
• Calculated Darcy friction factor
• Calculated equivalent Hazen Williams friction factor
• Friction loss in meters per 100 meters
Hydraulic results for each node include:
• Energy level (m)
• Pressure (m)
4.4.5 Pipe Materials Specifications
The pipeline material will be
• uPVC pipes Class 9 with spigot and socket joints for all water reticulation
pipelines
8/9/2019 Weaverley Housing Coop Design Report.pdf
19/21
19
• HDPE Type 4 pipes with compression fittings for stand connections.
• Joints connections for tees and valve connections to be CI with
spigot and socket joints. Alternative flange joints to be used where
directed specifically on valve connections
• Valves to be CI to water works quality to SABS 665 , with
connections to suit uPVC pipework.
• Bends to be
uPVC pressure bends up to 450 .with spigot and socket joints
450 / 900 bends or where noted on the pipework schedule to be CI with
joints to suit spigot and socket uPVC pipework..
• All bends, tees etc required thrust block as specified on the drawings.
8/9/2019 Weaverley Housing Coop Design Report.pdf
20/21
TITLE : WEAVERLEY COOPERATIVE HOUSING DEVELOPMENT
Project Team : Dande Civils
Client : Weaverley Cooperative
Client Project No : ………..
Status of Report : Final
Morad Report No : 1
Date of this Issue : 10 February 2015
For Dande Civils issuing
Written & by
Compiled
M.Benhura (Bsc) Civil
Hons
Initials & Surname Signature Date
Peer – reviewed
byM Kaendeza (Pr.Eng)
Initials & Surname Signature Date
8/9/2019 Weaverley Housing Coop Design Report.pdf
21/21
APPENDIX 1: INSITU SOILS