DERIVING THE FORMULA FOR ESTIMATING DAM STORAGE CAPACITY

At the preliminary design stage of the dam, the storage capacity is estimated by the following formula:

   Q = LTD

            6

Where;

            Q = Storage Capacity in m³

          L = Length of the Dam at Full Supply Level in m

          T = Throwback in m and approximately in a Straight Line from the Wall

          D = Maximum Depth of the Dam at Fully Supply Level in m

The formula is derived as shown below:

The above method is accurate to within 20% and should be revised when a more detailed survey has been undertaken. The factor 6 in the formula is conservative so based on experience and local knowledge it can be adjusted. 

INDEGINOUS IRRIGATION WATER MANAGEMENT EXPERTS-CASE OF KAMBILONJO FARMERS

On 11 July 2013, I was in a gravel investigation mission around Kambilonjo Area (also known as Ssera in Mozambique) for earthworks on a construction project. It is located about 20km from Tsangano Turnoff on the Ntcheu-Tsangano-Neno Road. This area is known for its hard working farmers and it is synonymous with Irish Potato growing. As I was driving along the potato fields I was impressed with the hard work and commitment of these true daughters and sons of Malawi. In my view these patriotic Malawians deserve national accolades for dedicating their lives in keeping us alive in the cities. Along the way something caught the attention of my expert eye-their Irrigation Water Management Technique.

The area has perennial rivers however the water is not adequate to afford 'flooding' of their fields as most smallholder farmers believe is the best way to irrigate. Therefore they developed a mean approach to irrigation. Do not think that they have installed drip irrigation systems.

Irish Potato Fields in Kambilonjo Area (Green Patches)

Surprisingly, furrow irrigation system is the most prevalent method of irrigation. The farmers use locally available resources to construct their gravity fed irrigation system. They use sand filled bags to build temporary weirs which act as headworks for stream diversion. Interestingly they optimize water use by digging small canals of about 100mm wide and 100mm deep to transport water to their fields. Technically the farmers construct canals with small wetted area hence little water is lost due to percolation. I also noted that the farmers by using small streams are conscious with the actual application to the plants as a result they do not over-irrigate. This is really a beacon of sustainable irrigation in light of climate change.

I hope my fellow irrigation experts can borrow a leaf from these farmers to emphasize if not overemphasize to other farming community who think irrigation is flooding their fields. To those who have time and resources please visit the area and see these indigenous irrigation water management experts.

EFFECTIVE STEPS TO FOLLOW IN MATERIALS INVESTIGATION FOR A PROJECT

Introduction

 In a road or an earth dam project, earth works form a big chunk of the works. For instance, in a road project there is need to have suitable material for fill, sub base and base while in an earth dam the same is required for the core, shell, blanket filter and rip rap. Ideally it would be reasonable to use the cut material for fill however practically there is still a huge deficit. It is therefore important to prepare a mass balance diagram (to be covered separately on this blog) to establish your material needs. As a result the material is investigated closest to the project area in order to reduce haulage costs. Materials Prospecting is not an easy task, just imagine you are looking for about 100,000m³ of suitable material for a 100Km road project. It is against this background that this article is written to help with some practical steps to  effectively investigate materials for a project. The steps suggested have effectively worked for the author and he hopes they also do for you.

Step 1: Estimate the Net Volume of Earth Works Required

I will use a hypothetical data of a 5km section of a road project and assume the material being investigated is fill

Start by drawing a schematic representation of the road and indicate the material cut, volume of fill, volume of cut materials which is suitable for fill and the net required fill within the first 5 km, see an illustration below

Cut	10m3
Chainage	0 +000	5+000
Fill	12m3
Cut Material Suitable  for Fill	2m3
Fill Required	10m3

Note: The suitability of the Cut Material for fill is established by testing the material on the center-line of the road every 500m.

Step 2: Mark a 10Km Radius on Google Earth or Map around your Project Area and Establish Hints for availability of the Materials

·         Observe Land Use and Vegetative Cover . Gravel is associated with shrubs and stunted growth of crops. This can be established by using Land Use Database for Malawi available at Land Resource Conservation Department and Google Earth

·         Observe Topography. Naturally as you approach rivers in a highly hilly area there is likelihood of finding gravel due to weathering of rocks.

·         Observe if there is existing infrastructure that used materials of similar nature i.e. existing road, earth dam etc and establish the borrow pits used previously

·         Use available Local Knowledge. Locals have an idea where gravel material can be found

If there is no or insufficient gravel within the 10 km radius then draw  15 km radius and so forth.

Step 3: Resource Planning

Before you set off for the field trip please plan in advance the resources you will need for materials investigation. The resources required are as follows: Sample Bags, 4x4 Vehicle, Materials Technician, Driver, Casuals, Handheld GPS, Hoes, Shovels, Safety Gear ( Safety Boots, helmet, gloves, mask, goggles and snake gutters), tape, strings and notebook

Conclusion

This article has looked at some of the important steps to bear in mind when prospecting material for construction project. In the subsequent posts the author will provide you with other pertinent tips on materials investigation.

HOW TO PENETRATE THE MARKET AS A CIVIL ENGINEERING CONTRACTOR IN MALAWI

Inexperience is a big minus for the start up civil engineering contractors in Malawi since clients want to engage experienced contractors only. However, come to think of it, all experienced contractors were start ups at some stage. How did they penetrate the market? This article tries to highlight some helpful tips.

Advertise

It’s important to advertise your firm to general public or your targeted clientele. You can achieve this by doing some of the following;

• Write Letters of Introduction to your targeted clients with well designed Letterhead
• Advertise through Social Media
• Distribute Company Brochures and Business Cards
• Write in visible letters your Company Name on your Car
• Create a website if resources are available

Network

In any business it is important to connect with the old guards. This way you can learn some tricks of doing certain things, or see the gaps in the industry and capitalize on them

Start as a Sub-contractor

This is the way most contractors start. You can negotiate with an experienced contractor who has for instance a road surfacing project to subcontract your firm to construct drains.

Target Individual Clients

You can target some individual clients who might be interested in a contractor to do minor construction works like access road, culvert, car park to their new house, irrigation system for their farm etc

Do your first Project Professionally

If you win your first project please work to impress by ensuring quality work within agreed time period.

COMMON CHALLENGES FOR START UP CONTRACTORS IN MALAWI

Any start up business has its own challenges, the biggest challenge is to develop a strategy to overcome them. Knowledge of the likely challenges one would face in a business is the beginning of successful strategy to win market share. This article looks at some of the common challenges that start up contractors in Malawi especially contractors in the MK 5 Million Category and MK 15 Million Category face.

 Inexperience

The challenge of inexperience is double faceted. Firstly, most if not all clients require an experienced contractor to undertake their projects and there are no or little deliberate arrangements to accommodate inexperienced contractors. This is evident in most bid documents as it is stated clearly that as part of the Qualification Criteria the contractor must have undertaken a specified minimum number of projects of similar nature so that his or her bid can be considered responsive. Secondly, it is lack of prior experience on the part of the owner of the contracting firm. This makes it difficult if not impossible for the owner to take control of the operations in the firm as he or she relies on the expertise of the employees. If some foremen or site agents note that the owner (in most cases is the managing director) has no experience on a particular project they capitalize on that weakness to siphon money by lying about some requirements or activities.

Lack of Capital or Assets

Lack of capital or assets is one of the drawbacks for start up contractors. If you have no capital or assets it is difficult to access loans, advance capital, performance bonds, bid securities, insurance, procure or hire plant/equipment.

Poor Negotiation Skills

In construction, negotiations are part of the game. There are situations in which the contractor must negotiate for a better deal. Time and again moments arise when the contractor has to negotiate or let the clients do things their way.

HOW TO BECOME A CONTRACTOR IN MALAWI

Contractors are involved in construction of roads, bridges, buildings, water and irrigation infrastructure, airports, electrical installation and all kind of infrastructure. In Malawi you do not have to necessarily be an engineer or architect to be a contractor however it is advisable to have knowledge of construction in order to successfully control your construction business operations. To that end, short courses are offered by the National Industry Council  which ranges from a period of a week to 3 months or so.This article looks at  how you can become a contractor in Malawi.

Step 1: Register with Registrar of Business Names

Every business is by law required to register with the registrar of business names in Blantyre City. An applicant is required to pay a registration fee. The firm can be registered as a limited company, partnership or sole proprietorship. A registration certificate is issued roughly after 3 weeks.

Step 2: Register with National Construction Industry Council (NCIC)

When the registration certificate is out the contractor must also as required by law register with NCIC. The contractor can register as a building contractor, civil engineering contractor, electrical contractor etc. Within each main category (i.e building contractor, civil engineering contractor etc)  contractors must apply in a particular category like MK 5 Million, MK 15 Million etc.  MK 5 Million is likely category for a start up however registration in a higher category is at the discretion of NCIC.

Step 3: Register with Malawi Revenue Authority (MRA)

It is important to pay tax obligations as such the contractor must register with MRA. Most clients these days request for a tax compliance during bidding.

Note: Electrical Contractors may be required to register with Malawi Energy Regulatory Authority