rainwater harvesting builder’s yard - cuve waters · #1 ferrocement tank #2 rectangular...

IN COOPERATION WITH INDUSTRY PARTNERS

Proposal for a

Rainwater Harvesting Builder’s Yard

Benefits of and preconditions for the establishment of a builder’s yard to

promote and intensify the construction of rainwater harvesting and storage

facilities in northern Namibia.

2

Cuve Waters

Technische Universität Darmstadt

Institut IWAR

Fachgebiet Wasserversorgung und Grundwasserschutz

Franziska-Braun Str. 7

64287 Darmstadt

Germany

www.iwar.tu-darmstadt.de

in cooperation with:

ISOE - Institute for Social-Ecological Research

Hamburger Allee 45

60486 Frankfurt am Main

Germany

www.isoe.de

and

One World Consultants Ltd., Kenya

www.cuvewaters.net

1st version, October 2015

3

Lead Authors:

Isaac Kariuki (One World Consultants, Kenya)

Andre Müller (TU Darmstadt)

Alexander Jokisch (TU Darmstadt)

Mareike Zurmühl (TU Darmstadt)

All publications of this series:

Water Storage:

#1 Ferrocement Tank

#2 Rectangular Underground Tank

#3 Pond

Horticulture and related Infrastructure:

#4 Greenhouse

#5 Drip Irrigation

#6 Sustainable Techniques and Practices for Water Harvesting and Conservation and their

Effective Application in Resource Poor Agricultural Production

(copy provided by the Water Research Commission South Africa)

Organisation and Extension Services:

#7 Proposal for a Rainwater Harvesting Builder’s Yard

#8 Extension services in horticulture and irrigation with

special reference to rainwater harvesting in Namibia

#9 Cost Sheets for Rain- and Floodwater Harvesting

Proposal for a Rainwater Harvesting Builder’s Yard

4 IN COOPERATION WITH INDUSTRY PARTNERS

Preface

„CuveWaters – Integrated Water Resources Management in central-northern Namibia” is a joint

research project of German and Namibian partners funded by the German Federal Ministry of

Education and Research (BMBF). Main research partners are the Institute for Social-Ecological

Research (Frankfurt, Germany) and the Technische Universität Darmstadt (Darmstadt, Germany).

Partners in Namibia are for example the Ministry of Agriculture, Water and Forestry (MAWF) and the

Desert Research Foundation of Namibia (DRFN), the project furthermore closely cooperates with One

World Consultants (OWC) from Kenya. CuveWaters has developed different technologies for water

supply and sanitation in central-northern Namibia, ranging from Groundwater Desalination to Rain-

and Floodwater Harvesting as well as Sanitation and Water-reuse. Between 2009 and 2013 different

pilot plants were constructed at different places all over central-northern Namibia.

The idea of this paper is to support capacity development measures within the technology line of rain-

and floodwater harvesting. It is intended to show how a dissemination of RWH throughout central-

northern Namibia could be facilitated and which aspects have to be considered financially and

process-related. Main focus of this paper lies on the economic advantages and business opportunities

of builder’s yard operation compared to other supply processes.

This manual succeeds a series of Rain- and Floodwater Harvesting Manuals for Namibia which form

the basis for RWH extension:

Water Storage:

#1 Ferrocement Tank

#2 Rectangular Underground Tank

#3 Pond


Horticulture and related Infrastructure:

#4 Greenhouse

#5 Drip Irrigation

#6 Sustainable Techniques and Practices for Water Harvesting and Conservation and their Effective

Application in Resource Poor Agricultural Production

(copy provided by the Water Research Commission South Africa)

Organisation and Extension Services:

#7 Proposal for a Rainwater Harvesting Builder’s Yard

#8 Extension services in horticulture and irrigation with

special reference to rainwater harvesting in Namibia

#9 Cost Sheets for Rain- and Floodwater Harvesting

For more information on organisational, institutional and other general aspects of rain- and floodwater

harvesting please have a look in the “CuveWaters Rain- and Floodwater Harvesting Toolkit”:

http://www.cuvewaters.net/Toolkits.112.0.html

For more information on the CuveWaters project please visit http://www.cuvewaters.net

Alexander Jokisch


Darmstadt, 23.10.2015


http://www.cuvewaters.net/



About

Manual on Training in “Extension Services in Horticulture and Irrigation with special reference to

Rainwater Harvesting in Namibia”

CuveWaters – Integrated Water Resources Management in Namibia

2015

This manual is also available on http://www.cuvewaters.net/Toolkits.112.0.html

For more information on Rainwater Harvesting in Namibia please contact

Prof. Dipl.-Ing. Dr. nat. techn. Wilhelm Urban


Institute IWAR, Chair for Water Supply and

Groundwater Protection

E-mail: [email protected]

or

Dr. Nicola Schuldt-Baumgart

ISOE – Institute for Social-Ecological Research

Science Communication and Public Relations


or


mailto:[email protected]



Isaac Kariuki

OWC – One World Consultants, Kenya

Phone: +254 72 174 4096


or

Okashana Rural Development Centre

Phone: +264 65 285 312 / 244 100

Fax: +264 65 285 315


“CuveWaters – Integrated Water Resources Management in Namibia” is sponsored by:


8

Table of Content

Preface ..................................................................................................................................................... 4

About ....................................................................................................................................................... 6

1 Preliminary considerations ............................................................................................................ 10

1.1 Planning ................................................................................................................................. 10

1.1.1 Material Procurement and Logistics .............................................................................. 11

1.1.2 Tools Logistics and Construction Schedules ................................................................. 12

1.1.3 Labour ........................................................................................................................... 12

1.2 Financing ............................................................................................................................... 13

1.3 Legal ...................................................................................................................................... 13

1.4 Builder’s Yard Suppliers ....................................................................................................... 13

2 Builders’s Yard .............................................................................................................................. 15

2.1 Concept of a Builder’s Yard .................................................................................................. 15

2.2 Builder’s Yard for extension of RWH ................................................................................... 15

2.3 Assignment and Responsibilities ........................................................................................... 16

2.4 Business Opportunity ............................................................................................................ 16

3 Example ......................................................................................................................................... 17

3.1 Number and Configuration of RWH Sites (Exemplary) ....................................................... 17

3.2 Material Requirements for RWH Sites (Exemplary) ............................................................ 17

3.2.1 Ferrocement Tanks ........................................................................................................ 18

3.2.2 Drip Irrigation Systems ................................................................................................. 19

3.2.3 Greenhouses .................................................................................................................. 20

3.2.4 Ponds ............................................................................................................................. 21

3.3 Tool Requirements for RWH Sites (Exemplary) .................................................................. 21

3.3.1 Ferrocement Tanks ........................................................................................................ 21

3.3.2 Drip Irrigation Systems ................................................................................................. 22

3.3.3 Greenhouses .................................................................................................................. 23

3.3.4 Ponds ............................................................................................................................. 24


3.4 Estimated Builder’s Yard Material Inventory (Exemplary) .................................................. 24

3.5 Estimated Builder’s Yard Tool Inventory (Exemplary) ........................................................ 27

4 Summary ....................................................................................................................................... 29


10

1 Preliminary considerations

The construction of a single rainwater catchment, an adequate storage tank, and maybe even a

greenhouse for farming activities requires a certain amount of construction materials as well as

specific tools. Aiming on dissemination of RWH for the improvement of irrigation water availability

in northern Namibia, it can be helpful to re-think construction process with regards to the number of

RWH sites where rainwater storage tanks shall be constructed. This paper shows which considerations

are to be made for planning and logistics, finance, construction, and maintenance when larger numbers

of tanks shall be constructed. The aspects arising from an increased number of tanks to be constructed

will be discussed, possible obstacles will be identified and advice how to handle the additional

challenges will be given. Finally, the reader will see the business opportunities of operation of a

builder’s yard for RWH supplies.

In the following, all considerations will be made taking ferrocement tanks into account as storage

solutions for rainwater. Other types of storage tanks like Polyethylene tanks, brick tanks, underground

tanks, or tanks made of iron, are possible as well.

In general, the concept of a builders’ yard can be described as a central centre for temporary storage

and distribution of construction material and tools. This concept may offer the chance to reduce efforts

for material and tools delivery in remote regions where no hardware shops are present, as it is the case

in central-northern Namibia. A bundled procurement of material and tools for several RWH

construction sites usually allows for discounted purchase prices. A bundled delivery of construction

material to the builders’ yard results in less cost for heavy duty truck delivery. Finally, the distribution

of material and tools from the builders’ yard to each of the RWH construction sites can be done with

smaller local transportation whenever it is required.

1.1 Planning

For a larger amount of rainwater storages tanks to be built, upfront planning efforts are a lot higher

than for a single storage tank.

Each of the potential construction sites has to be evaluated regarding their suitability for RWH as

described in the RWH Toolkit. If a site is suitable and the decision for a storage tank was made,

preparation for construction begins. The following questions should be answered (amongst others) for

each of the sites:

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- Where to build the tank?

- How to deliver material, tools, and labour to the specific site?

- When is the best time to build?

- Who is constructing the tank, can local labour help?

- How is the construction?

1.1.1 Material Procurement and Logistics

Planning construction work on more than one site at a time requires some more thoughts on material

availability and supply, availability and assignment of labour, and construction schedules. Whereas the

amount of materials for a single tank is usually available at a hardware store, the amount for 10 or

even 20 tanks may not be on stock and hence requires distribution of the retailer itself. Depending on

the distance from construction sites to hardware stores, the available storage space, the availability of

material and the construction schedules for all sites, different supply schemes may be suitable:

- All at Once: All material for all construction sites is delivered to each site at once. This

requires sufficient storage space at each site. This method bears a very high risk of material

damaged by bad weather condition or lost due to theft. The number of trips necessary for

disposition of all materials needed is minimal (1).

- Step by Step: All material needed for one single tank or material for only a few tanks is

delivered to the specific construction site shortly before construction begins. This method

requires sufficient storage space at each site. The risk of material damaged by bad weather

condition or lost due to theft is reduced since material is stored at one or a few sites only. The

number of trips to supply all sites is higher.

- Just in Time: All material is delivered to the construction sites as needed for specific

construction progress on each construction site. The required storage space at each site is

minimized, since only the amount of material is delivered which is needed for construction on

a certain day or on a few days. Consequently, damage or theft of material is rather unlikely.

The number of trips for disposition of material is highest.

- Builder’s Yard: All material needed for all sites is supplied to a storage space – the builder’s

yard - close to the construction sites either “All at Once” or “Step by Step”. Sufficient storage

space is needed to store all material at once. A single storage location allows for better

protection of construction material against bad weather and theft. Supply of material from the

builder’s yard to the specific sites can be done “Step by Step” or “Just in Time”.


12

Depending on above mentioned circumstances (distances, available space, schedules, availability of

material) any of the listed methods of material supply should be favoured. The “Builder’s Yard”

method is most suitable if construction sites are way off cities and respectively hardware stores. For

most of the potential RWH construction sites in central-northern Namibia this situation is the case.

The “Builder’s Yard” method combines the advantages of all other methods and allows for low

number of trips for heavy loaded trucks.

Nevertheless, protection of construction material is comparatively easy. Material supply from the

builder’s yard to the construction sites can be done “Just in Time” or “Step by Step” which allows for

a low amount of material needed to be stored at a site. The number of trips from the builder’s yard to

the sites is in fact comparatively high. Nevertheless, it is only for short distance and can be done with

normal loaded pick-up/vehicle or other local transportation such as donkey cars.

1.1.2 Tools Logistics and Construction Schedules

The construction of ferrocement tanks and RWH related facilities requires certain tools for proper

execution of work and efficiency. Depending on the overall number of tanks to be constructed in the

timeframe in which the tanks shall be built, the general construction schedule may be optimized for a

circulation of tools from one construction site to another. The amount of construction tools provided

can e.g. be calculated to fit for 5 constructions sites operated at a time. When at one site a certain

construction step is finished, the tools are forwarded to another site where construction can be started

or continued yet.

Special equipment, such as plate compactor, vibrator for compacting of concrete, plaster sprayer, etc.,

can be moved from one construction site to another if this is considered in construction schedules and

timings. This may require that construction work on one site start one or two days later than the

construction started on another site.

1.1.3 Labour

Planning construction of many RWH sites requires a good upfront coordination of labour as well.

Depending on the distance of the single construction sites and the timeframe in which all tanks shall

be built, it has to be decided whether assignments for construction is given to labour available on-site

or if a certain group of workers shall move from one site to the next. Most important is to ensure a

certain number of experienced workers is available at any site. Furthermore, have in mind that usually

transport and food has to be provided for the labour as well.

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1.2 Financing

The construction of more than only one ferrocement tank or RWH facility requires higher financial

resources. Above mentioned aspects of planning of course have financial implications as well.

Material needed has to be paid for, tools used have to be bought or hired. Finally, experienced workers

and casuals have to be paid for the amount of work done for construction of RWH sites.

Make sure all potential costs are considered early in planning to avoid an overall failure. E.g. do not

order material and supply it to a builder’s yard when it is unclear how the labour for construction can

be paid.

1.3 Legal

Legal aspects become more and more important when scale of RWH is increasing. For a project of

many RHW sites make sure all permissions needed are available. These may e.g. be permissions of

local chiefs or regional water boards. If any permission is missing, the whole project and RWH for all

sites may be at risk.

1.4 Builder’s Yard Suppliers

To supply RWH projects in the region with all material and tools needed, the builder’s yard operator

has to purchase and stock the required amount of material and tools. Most tools, poles and

construction material for tanks can be obtained from most hardware shops in Namibia. For this reason,

it is advisable to request quotes from several suppliers and ask quantity discounts.

Drip irrigation equipment can only be ordered from selected specialized shops located in Windhoek,

Okahandja and Epalela (Olushandja Dam). We recommend to order drip irrigation equipment from

Aqualand, located with its headquarter in Okahandja, if prices quoted are competitive to other

suppliers. Another possibility to buy drip irrigation equipment is the company Sinclair in Windhoek:

(www.sinclair.com.na). The dam liner necessary for pond construction is not available in Namibia but

can be ordered from Build it South Africa via its Namibian branches. Delivery from South Africa will

take up to three weeks and causes additional cost, so plan and order well in advance. Unfortunately the

quality of greenhouse plastic foil that is available in Namibia is not sufficient for the purpose of

covering the greenhouse and easily breaks due to strong winds typical for central-northern Namibia.

For this reason, order plastic foil from South Africa or from Kenya. Contacts for Kenyan plastic foil

can be provided for example from One World Consultants ([email protected]).

http://www.sinclair.com.na/


14

Also, keep in mind that prices can differ in the different shops and seasonal variations are also

common. So estimate the demand well in advance and compare the prices in the different shops. Most

hardware shops offer delivery of the materials for reasonable prices.

The following list is exemplary and based on the experiences during CuveWaters RWH development

phase:

Oshana Build it, Ongwediva (recommended, first choice)

Benz Building Supplies, Ongwediva (recommended, second choice)

Pennypichers, Ongwediva

Pupkewitz Megabuild, Oshakati

Chico, Oshakati

Also have in mind that some materials can be purchased from rural development centres (RDCs) and

agriculture development centres (ADCs) which support the rural development and people new to

agriculture.

15

2 Builder’s Yard

The idea of a builder’s yard supporting construction works in a region is not a new one. All over the

world people use a central place to store building material and tools and distribute those to the

construction site where they are needed.

2.1 Concept of a Builder’s Yard

The concept of a builder’s yard can be described as a central centre for temporary storage and

distribution of construction material and tools. When several construction projects are to be done in a

region where infrastructure or availability of suppliers is limited, a builder’s yard offers the chance to

reduce the efforts for material and tools delivery into the region. Material and tools can be bundled and

delivered over a long distance in only a few truck loads. The distribution in the area where the

construction sites are can be done with smaller vehicles or (pick-up) trucks later on.

The builder’s yard therefore, is kind of project related distributor which ensure material needed is

ordered, stocked and finally distributed to the construction sites. Very important, when implementing

and operating a builder’s yard is a good bookkeeping on materials needed, delivered, stocked, and

distributed. Good records of incoming and outgoing material as well as of tools, reduces the risk of

loss of material or thefts.

2.2 Builder’s Yard for extension of RWH

When RWH is developing from demonstration scale to extensive usage in northern Namibia, all over

Namibia, or anywhere else in southern Africa, the construction of RWH facilities and rainwater

storage tanks may be much easier using builder’s yards. In rural areas, where no hardware stores are

present, a builder’s yard allows for efficient and easy distribution of materials and tools to the

construction sites.

For setting up a RWH builder’s yard it has to be clear how many construction sites will be supplied

from the builder’s yard and where they will be. Depending on the exact configuration of each RWH

site the overall amount of material and tools can be calculated. RWH sites configuration and material

required is determined by type and size of rainwater catchment, gutters needed, type and size of

storage tank, types and number of horticulture facilities (greenhouse, shade house, drier unit), and

irrigation systems.


16

2.3 Assignment and Responsibilities

The operation of a builder’s yard can either be part of an institutional roll-out of RWH or done

autonomously. The operation of the builder’s yard is a challenging task and requires specific skills to

allow the overall RHW project to be a success. For this reason, a person with some experience in

purchasing and distribution of construction materials should be assigned as the responsible for the

builder’s yard. This person should be in very close contact to the leaders of the project to ensure

material type and amount of material required is always known and schedules for distribution are

ideal. The responsible person should be able to perform a good and continuous bookkeeping on

incoming and outgoing materials to ensure proper use of each material and prevent losses or theft.

Furthermore, the responsible person for the builder’s yard should be able to communicate with

suppliers and negotiate prices and terms of delivery. Ordering material for 5 or more RWH sites may

allow for negotiations on substantial discount rates.

When the builder’s yard is in operation and started as a business, the financial resources for purchase

of material have to be acquired as well. Usually, payments for purchase of tools and materials have to

be paid before revenues can be expected from sale of materials to the specific RWH project sites. The

period until income is generated can e.g. be covered by short term loans with adequate interest rates or

other available assets.

2.4 Business Opportunity

Operation of a builder’s yard for RWH supply can be a good business opportunity in case RWH is

rolled out and support schemes increase the demand for RWH. Main aspect for a successful business

is the acquisition of information on when and where RWH facilities are to be constructed in

communities in the region. Furthermore, the material ordering and handling has to be managed well

regarding time and amount, to ensure no losses occur and seasonal variations of purchase prices can be

avoided or compensated. An owner of a RWH builder’s yard can be establish his or her business as the

single point of contact when the supply of goods covers all material and tools needed for RWH

activities and when prices are competitive to existing competitors in the buildings supply sector. Focus

on RWH extension and supply of material to several construction sites allows for quantity discounts

when purchasing goods. The profit margin for a builder’s yard operator comes with the price

differences from discounted purchase and sale at a fair market value.

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3 Example

Following, a fictional scenario of RHW extension will be created to show how plans for a builder’s

yard exemplarily look like. This example shall guide later project planners who have to adapt numbers

of sites and type and amount of material needed to their specific projects.

3.1 Number and Configuration of RWH Sites (Exemplary)

For this paper we assume that in a rural region, way-off from hardware shops, RWH facilities shall be

built to increase the availability of irrigation water. In the model region, in total 12 sites will be

equipped with RWH facilities of different sizes and configuration. Some already have corrugated roofs

which will be used for rain water catchment and need a storage tank only. Horticulture is done already.

Consequently, no new irrigation system is necessary. Some others will need a tank and an addition

irrigation system to start horticulture. Finally, two sites will be used for erection of a greenhouse with

pond and horticulture with irrigation systems needed.

Configuration Quantity Gutters Tank Irrigation

System

Pond Green-

house

Gutters & Tank only 5 5 5 - - -

Gutters, Tank, Irrigation

System

5 5 5 5 - -

Greenhouse, Pond,

Irrigation System

2 2 - 2 2 2

Grand Total 12 12 10 7 2 2

Table 1: Configuration of fictional RWH builders’ yard scenario

3.2 Material Requirements for RWH Sites (Exemplary)

The material required for each type of RWH configuration will be calculated below. Requirements are

based on the construction manuals and the toolkit developed during an earlier stage of

CuveWaters project. The toolkit can be found on the CuveWaters homepage

(http://www.cuvewaters.net/Toolkits.112.0.html). Keep in mind that no site is like another and

therefore, amount of required material usually differs. For this example, all sites of one configuration

are assumed to require the same amount of material.



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3.2.1 Ferrocement Tanks

The amount of material needed for construction of 10 ferrocement tanks is derived from the

“CuveWaters Construction Manual # 1-Ferrocement Tank” which is part of the CuveWaters Toolkit.

The table below shows material required and the specific amount for a single and for 10 construction

sites. It is important to check whether some of the material needed, can be reused at other sites as wells

(e.g. see empty sacks).

Material Quantity Single Site Quantity 10 Sites

1 Cement 42 420

2 Weld Mesh 2.4m x 6m x 8mm 6 60

3 Binding Wire 2mm x 200m 15 kg 150 kg

4 Chicken Mesh 25mm x 1.2m x 50m 1 roll 10 rolls

5 Steel Deformed Bars 8mm x 6m 3 30

6 Bib Tap Garden 20mm 1 10

7 Galv. Elbow 20mm 1 10

8 Galv. Plug 20mm 1 10

9 Galv. Standpipe 20mm x 600mm 2 20

10 Galv. Standpipe 20mm x 750 mm 1 10

11 Galv. Socket 20mm 1 10

12 Galv. Tee 20mm 1 10

13 Manhole Cover 50cm x 50cm 1 10

14 PVC Pipe 4” (110mm) x 6m 1 10

15 PVC sheeting 0.15mm x 4m x 10m 1 10

16 Gravel / Concrete stone (½” to ¾”) 2.5 m³ 25 m³

17 Clean River Sand 10 m³ 100 m³

18 Sisal Rope 1 Ply 500 gr. 4 kg 40 kg

19 Assorted Nails Wire 100mm x 4mm 1 kg 10 kg

20 Empty Sacks 60 360*

21 Water ** **

*It is assumed, that most sacks for ferrocement tank construction in general can be reused and schedule

of construction sites allows for reuse of sacks from one site at another.

**Mixing of concrete and curing of ferrocement needs a large amount of water. Make sure sufficient

water is available from piped connection or supplied to construction site in any other way.

Table 2: Comparison of material required for a single ferrocement tank construction site and ten construction sites.

19

3.2.2 Drip Irrigation Systems

The exemplary boundary conditions for the irrigation systems on small-scale gardening on household

level are as follows: It is assumed to have 6 beds of 15 m length each, which contain two rows of

plants and therefore two rows of drip lines. The total area consequently is about 6 m x 15 m. The

distance between the tank and the beds is assumed to be 5 m. For different garden sizes, quantities for

material will differ. The material requirement calculated is based on the “CuveWaters Construction

Manual # 5 - Drip Irrigation”.


1 Water Line LDPE 40mm 10 m 70 m

2 Pipe LDPE 32mm 10 m 70 m

3 Drip Line 4l/h x 30mm 200 m 1400 m

4 Drip Saddle and Nuts 15 105

5 Valve Ball Lever 40mm Full Bore Agri-Lock 1 7

6 Water Tank Polyethylene 1000l 1 7

7 Gate Valve Brass 32mm 2 14

8 Screen Filter 1 7

9 Water Gauge 1 7

10 Nylon Tee 40mm 1 7

11 Pipe Clip UPVC 40mm 4 28

12 Galv. Reducing Socket 20 x 15mm 2 14

13 Galv. Reducing Socket 40 x 20mm 2 14

14 Nylon Adaptor Male 40mm 4 28

15 Nylon Elbow 40mm 2 14

16 Nylon Adaptor Male 32mm 4 28

17 Nylon Coupling Reduce 40/32mm 2 14

18 Tape PTFE Each Loose 10 70

19 Hose Clamps 32 x 57mm 10 70

20 Hose Clamps 19 x 44mm 6 42

21 Binding Wire 1.6mm x 100m 1 7

22 Wooden Support Poles 100mm, 3m 6 42

23 Wooden Support Poles 50mm, 2.4m 8 56

24 Wire Nails 120mm x 5mm 1kg 3 21

Table 3: Comparison of material required for a single drip irrigation construction site and ten construction sites.


20

3.2.3 Greenhouses

The construction material listed here is based on the “CuveWaters Construction Manual # 4 –

Greenhouse” which guides through construction of a steel tube made greenhouse of a size of

8 m x 15 m. Other sizes or construction materials (such as wood) will make adjustments necessary.


1 Round Steel Tubes 38 mm x 1.6mm 43 86

2 Bolts 80 160

3 Nuts 80 160

4 Washers 80 160

5 Builders Line 0,85 x 100m,70LBS 1 2

6 Cement 32.5R 50kg 2 4

7 Sand 0,3 m³ 0,6 m³

8 Stone Concrete 19mm 0.5cbm 1 2

9 Gate Mesh 900 x 1800 x 32 x 75mm 1 2

10 Gutter 0.5 x 100 x 125mm x 6m 5 10

11 Gutter Brackets Square Purlin 125 x 100 15 30

12 Gutter Downpipe 100 x 75 x 2.7m x 0.4mm 3 6

13 Gutter Square 3.6m x 100 x 75 x 0.4mm 1 2

14 Nails Wire 75mm x 3.55mm 1kg 15 30

15 Neo Industrial Aluminium Paint 1l 4 8

16 Transparent Plastic Sheet (for Roof) 1 2

17 Poles CCA 50/75mm x 2.4m 4 8

18 PVC Junction SV Plain 110mm x 90° 1 2

19 PVC Down Pipe 110mm x 5m 1/2 1

20 Roofing Screws & Washer 90mm (100pp) 3 6

21 Shade Cloth 40% 3m 55 110

22 Timber Purlin 50mm x 76mm x 6m (4pcs) 2 4

23 Timber Brandering 38mm x 50mm x 6m

(9pcs)

1 2

24 Twine Sisal 1 Ply 500gr 2 4

25 Welding Rods 2.5mm 1kg 2 4

26 Blades Hacksaw 32TPI HSS 1 1

Table 4: Comparison of material required for a single greenhouse construction site and two construction sites.

21

3.2.4 Ponds

The exemplary site configuration shows that two greenhouses are built and each of them is equipped

with a pond for rainwater storage. The table below shows the amount of material needed for a single

pond and in total for both ponds. Basis for the table is the “CuveWaters Construction Manual # 3 –

Pond”.


1 Gum Poles 50/75mm x 3.6m 20 40

2 Gum Poles 75/100mm x 4.2 5 10

3 Binding Wire 2mm x 200m 1 2

4 Twine Sisal 1 Ply 500gr. 8 16

5 Nails Wire 120mm x 5mm 1kg 4 8

6 Dam Liner, 26m x 9m 1 2

7 Shade Net 80%, 3m 65 m 130 m

Table 5: Comparison of material required for a single pond construction site and two construction sites.

3.3 Tool Requirements for RWH Sites (Exemplary)

Similar to the materials required for RWH extension projects, tools have to be provided to ensure

construction work is done efficiently and in the right quality. The exact amount and types of tools

needed can be derived from the total amount of construction sites, the configuration of each RWH site,

and finally, from the project schedule of all sites. In general, tools can be moved from one site to

another when construction work was finished at the first site. If the overall project schedule aims on

many RWH construction sites to be done in parallel, more tools are required than in case of working

on sites one by one. Nevertheless, the transport of tools from one site to another has to be considered

and planned.

3.3.1 Ferrocement Tanks

The table below shows the tools and the quantity needed for construction of a ferrocement tank at a

RWH site. The columns show how big the difference is when construction work is conducted only on

a few sites at the same time compared to conducting construction work on all sites at a time. To reduce

amount of tools required and consequently the costs, the RWH extension project should plan for 2 to

max. 5 project sites to be worked in parallel. If more than 5 sites are worked in parallel, the costs for

tools increase disproportionally.


22

Tools Quantity

Single Site

Quantity 3 Sites

in parallel

Quantity 12

Sites

1 Spade 1 3 12

2 Shovel Round Nose 1 3 12

3 Wheelbarrow 1 3 12

4 Bolt Cutter 600mm 1 3 12

5 Plastering Trowel 280mm 3 9 36

6 Plastering Float, Wooden 280mm 2 6 24

7 Hand Saw 550mm 1 3 12

8 Hammer Claw 500gr 1 3 12

9 Sewing Needles 4 12 48

10 Spirit Level, Aluminium 600mm 1 3 12

11 Bucket, builders 12l 2 6 24

12 Gloves, builders PVC 1 3 12

13 Gloves, leather 3 9 36

14 Rake, garden medium duty 1 3 12

15 Pliers, combination 2 6 24

16 Hacksaw Frame 1 3 12

17 Blades, Hacksaw 32TPI HSS 1 3 12

18 Roof Support Poles (Gum Poles) 70 210 840

19 Plaster Sprayer 1 3 12

Table 6: Comparison of amount of tools required when several ferrocement tanks are constructed in parallel.

3.3.2 Drip Irrigation Systems

As for gutters and tanks, the tools required for installation of drip irrigation systems depend on the

number of construction sites that are done in parallel. Furthermore, many tools, which are needed for

drip irrigation system installation are needed for tank construction as well and therefore need to be

ordered only once. The table shows which tools are needed in general and which of them are already

to be ordered for tank construction and can be used for drain system installation as well.

Tools Quantity

Single Site

Quantity 3 Sites

in parallel

Required for

Tank as well

1 Spade 1 3 Yes

2 Saw Hacksaw Frame 1 3 Yes

3 Hammer Claw 500gr 1 3 Yes

23

4 Spirit Level, Aluminium 600mm 1 3 Yes

5 Pliers, combination 1 3 Yes

6 Bit HSS 9.5mm 1 3 No

7 Bit HSS 7mm 1 3 No

8 Screwdriver 6x100mm 1 3 No

9 Puncher or Drill Bit 1 3 No

10 Tape Measure 5m x 25mm 2 6 No

Table 7: Comparison of amount of tools required when several drip irrigation systems are constructed in parallel.

3.3.3 Greenhouses

The configuration of the exemplary RHW extension project assumes two greenhouses to be build.

Specific tools used for greenhouse construction are to be ordered only once, if greenhouses are build

in sequence (i.e. in parallel to tank construction on others sites only). As for the drip irrigation system

installation, tools are to be ordered only once for all projects, when they are already needed for tanks

or irrigations systems and therefore are part of the tables above.

Tools Quantity Single Site Required for Tank or

Irrigation as well

1 Spade 1 Yes

2 Hand Saw 550mm 1 Yes

3 Hammer Claw 500gr 2 Yes

4 Spirit Level, Aluminium 600mm 1 Yes

5 Bucket, builders 12l 1 Yes

6 Pliers, combination 2 Yes

7 Bit HSS 10.5mm 1 No

8 Bit HSS 9.5mm 1 Yes

9 Bit HSS 7mm 1 Yes

10 Brush 75mm 2 No

11 Builders Square 1 No

12 Screwdriver 6x100mm 1 Yes

13 Tape Measure 5m x 25mm 2 Yes

14 Saw Hacksaw Frame 1 Yes

15 Positioning Tool 4m No

16 Welding Unit (equipment of welding specialist) No

17 Soldering Unit (equipment of welding specialist) No

Table 8: Comparison of amount of tools required when several greenhouses are constructed in parallel.


24

3.3.4 Ponds

The two ponds which serve as storage for the rainwater caught on the roof of the greenhouses require

the tools listed below. Most of the tools are also required for the other RWH facilities and therefore do

not have to be ordered specifically for the ponds.

Tools Quantity Single Site Required for Tank,

Irrigation, or

Greenhouse as well

1 Spade 2 Yes

2 Shovel Round 4 Yes

3 Handle Hoe 3 No

4 Hoe Head 3 No

5 Hammer Claw 500gr 2 Yes

6 Pliers, combination 2 Yes

7 Sewing Needles 5 Yes

8 Hand Saw 550mm 2 Yes

9 Tape Measure 5m x 25mm 2 Yes

Table 9: Comparison of amount of tools required when several ponds are constructed in parallel.

3.4 Estimated Builder’s Yard Material Inventory (Exemplary)

The total material to be ordered and stocked in the builder’s yard is a summary of the material needed

for each of the RWH construction sites.

Material Tanks Irrigation Green-

house

Pond Total

Cement 420 4 424

Weld Mesh 2.4m x 6m x 8mm 60 60

Binding Wire 2mm x 200m 150 kg 200 kg

Binding Wire 1.6mm x 100m 7 7

Chicken Mesh 25mm x 1.2m x 50m 10 rolls 10 rolls

Steel Deformed Bars 8mm x 6m 30 30

Bib Tap Garden 20mm 10 10

Galv. Elbow 20mm 10 10

Galv. Plug 20mm 10 10

25

Galv. Standpipe 20mm x 600mm 20 20

Galv. Standpipe 20mm x 750 mm 10 10

Galv. Socket 20mm 10 10

Galv. Tee 20mm 10 10

Manhole Cover 50cm x 50cm 10 10

PVC Pipe 4” (110mm) x 6m 10 1 11

PVC sheeting 0.15mm x 4m x 10m 10 10

Gravel / Concrete stone (½” to ¾”) 25 m³ 1 m³ 26 m³

Clean River Sand 100 m³ 0,6 m³ 101m³

Sisal Rope 1 Ply 500 gr. 40 kg 2 kg 8 kg 50 kg

Wire Nails 100mm x 4mm 10 kg 10 kg

Wire Nails 120mm x 5mm 1kg 21 kg 8 kg 29 kg

Wire Nails 75mm x 3.55mm 1kg 30 30

Empty Sacks 360 360

Water Large amounts of water are needed for mixing of concrete and

curing of ferrocement.

Water Line LDPE 40mm 70 m

70 m

Pipe LDPE 32mm 70 m

70 m

Drip Line 4l/h x 30mm 1400 m

1400 m

Drip Saddle and Nuts 105

105

Valve Ball Lever 40mm Full Bore Agri-

Lock 7 7

Water Tank Polyethylene 1000l 7

7

Gate Valve Brass 32mm 14

14

Screen Filter 7

7

Water Gauge 7

7

Nylon Tee 40mm 7

7

Pipe Clip UPVC 40mm 28

28

Galv. Reducing Socket 20 x 15mm 14

14

Galv. Reducing Socket 40 x 20mm 14

14

Nylon Adaptor Male 40mm 28

28

Nylon Elbow 40mm 14

14

Nylon Adaptor Male 32mm 28

28


26

Nylon Coupling Reduce 40/32mm 14

14

Tape PTFE Each Loose 70

70

Hose Clamps 32 x 57mm 70

70

Hose Clamps 19 x 44mm 42

42

Wooden Support Poles 100mm, 3m 42 42

84

Wooden Support Poles 50mm, 2.4m 56 56 8

120

Wooden Support Poles 50mm, 3.6m

40

40

Wooden Support Poles 100mm, 4,2m

10

10

Round Steel Tubes 38 mm x 1.6mm

86

86

Bolts

160

160

Nuts

160

160

Washers

160

160

Builders Line 0,85 x 100m,70LBS

2

2

Gate Mesh 900 x 1800 x 32 x 75mm

2

2

Gutter 0.5 x 100 x 125mm x 6m

10

10

Gutter Brackets Square Purlin 125 x 100

30

30

Gutter Downpipe 100 x 75 x 2.7m x

0.4mm

6

6

Gutter Square 3.6m x 100 x 75 x 0.4mm

2

2

Neo Industrial Aluminium Paint 1l

8

8

Transparent Plastic Sheet (for Roof)

2

2

PVC Junction SV Plain 110mm x 90°

2

2

Roofing Screws & Washer 90mm

(100pp)

6

6

Shade Cloth 40% 3m

110

110

Timber Purlin 50mm x 76mm x 6m

(4pcs)

4

4

Timber Brandering 38mm x 50mm x 6m

(9pcs)

2

2

Welding Rods 2.5mm 1kg

4

4

Blades Hacksaw 32TPI HSS

1

1

Dam Liner, 26m x 9m

2 2

Shade Net 80%, 3m

130 m 130 m

Table 10: Estimated builder’s yard material inventory for fictional RWH project scenario.

27

3.5 Estimated Builder’s Yard Tool Inventory (Exemplary)

The tool inventory of the builder’s yard is dependent on the tools needed for the single RWH

construction sites and the project schedule. If the project schedule allows for moving equipment from

one construction site to another less tools have to be bought and overall inventory is consequently less

as well.

Tools Used for Total

Tank Irrigation Green-

house

Pond

Spade x x x x 3

Shovel Round Nose x x 3

Handle Hoe x

3

Hoe Head x

3

Rake, garden medium duty x 3

Wheelbarrow x 3

Bolt Cutter 600mm x 3

Plastering Trowel 280mm x 9

Plastering Float, Wooden 280mm x 6

Hand Saw 550mm x x x 3

Hacksaw Frame x x x 3

Blades, Hacksaw 32TPI HSS x x x 3

Hammer Claw 500gr x x x x 3

Spirit Level, Aluminium 600mm x x x 3

Builders Square x

1

Tape Measure 5m x 25mm x x x 6

Bucket, builders 12l x x 6

Gloves, builders PVC x 3

Gloves, leather x 9

Pliers, combination x x x x 6

Roof Support Poles 50/75mm, 2.4m x 210

Plaster Sprayer x 3

Screwdriver 6x100mm x x 3

Bit HSS 10.5mm x

1


28

Bit HSS 9.5mm x x 3

Bit HSS 7mm x x 3

Puncher or Drill Bit x 3

Brush 75mm x

2

Sewing Needles x x 12

Positioning Tool 4m x

1

Welding Unit (equipment of welding

specialist) x 1

Soldering Unit (equipment of welding

specialist) x 1

Table 11: Estimated builder’s yard tool inventory for fictional RWH project scenario

29

4 Summary

A builder’s yard may be a helpful addition for extension of RWH in any remote region in northern

Namibia or anywhere else. If a project has to be implemented under the above mentioned boundary

conditions of long distance to hardware shops and limited construction infrastructure, then a building

yard may be useful. Nevertheless, usage of the concept of a builder’s yard makes planning more

complex upfront. Different aspects of the project have to be cleared early in the project to allow

planning of project schedule, construction site schedules, material, tool, and financial requirements.

Furthermore, the operation of a builder’s yard requires at least one person who is assigned as the

responsible for material and tool ordering, bookkeeping, and distribution to the construction sites. If

the organizational challenges of a builder’s yard cannot be managed, the RWH extension project as a

whole will be at risk.

How material demand and tools required for an RWH extension project can be calculated is shown in

an exemplary project set-up. However, this project is working with simplified constraints which may

be much more complex in real life. Therefore people responsible for RWH projects always should take

this as a guiding only, and set up plans for their projects on their own. Very important for project

planning are the questions asked above in this paper:

- Where to build the tank, irrigation system, greenhouse, and/or pond?

- How to deliver material, tools, and labour to the specific site?

- When is the best time to build the tank?

- Who is constructing the tank, can local labour help?

- How is the construction financed?

Further questions which should be answered during planning of a project are more accumulative and

not focusing on single RWH construction sites:

- How many and which sites can be done in parallel?

- Does the overall timing allow for low a number of sites to be done in parallel? This may lead

to reduced number of tools required.

- Were all stakeholders included in the planning process? May there be additional helpful input

from anyone?

- Could (lack of) financing of one RWH facility impact another negatively?

rainwater harvesting builder’s yard - cuve waters · #1 ferrocement tank #2 rectangular...

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