Hydraulic ram pumps and Sling Pumps

OP-32-EIt should be noted that expenditure on spare parts is irregular and varies according to the quality ofoperation and maintenance, and to the type of spare parts. Spare parts can be divided into threecategories:1) frequently needed which should be kept as close as possible to the village (shop, mechanic);2) occasionally needed (every six months or year), which can be at a major centre close by;3) those needed for major rehabilitation or replacement (every few years) which can be kept at thelocal region or state capital.Finally, operation and maintenance costs are not only subject to a certain periodicity, they are alsosubject to variations due to the economic environment, inflation or exchange rate fluctuations whichcan influence the price of spare parts or energy. While identifying costs, it is therefore important tohighlight not only cost items, but also their periodicity and possible variations over time.2.2.2 Estimating costsEstimating investment costs is not difficult, as manufacturers advertise the price of equipment andlabour wage costs are known. However, estimating recurring costs just by using experience from othersimilar projects can be misleading, as recurring costs vary widely from one project to another. Onecommon method of estimating O&M costs is to use a percentage of capital costs, with the percentagesused ranging from 5 to 20%. This approach frequently results in an underestimation of recurrent cost(WASH, 1988a). In this section we show how to estimate real O&M costs as accurately as possible.The main costs of O&M were showed in Box 6, as: personnel, materials, chemicals, energy andcommunication, transport and private contractors. Based on this list, recurrent cost can be estimated asfollows 22 :Estimating Personnel costsa) Full time• determine O&M activities,• estimate the minimum number of personnel,• proceed with an agreement on the size and classification of all staff involved in O&M,• determine the average wage paid for each class of personnel,• sum up all wages.b) Over time• determine O&M activities that require additional time,• estimate number of personnel required for additional time,• determine the average wage paid for this personnel,• sum up all wages.Estimating Material Costs• consider two categories of materials: supplies and spare parts,• detail all the equipment, facilities and components of the water supply system,• detail the nature and frequency of O&M of each piece of equipment, facility, and component,• determine the need for each,• identify the cost of each,• determine the whole cost (and possibly determine unit costs/ m 3 ).Estimating Chemical Costs• identify which chemicals are needed (type, form, and quantities),• identify chemical costs by using unit price information for each chemical,• calculate the annual total cost by multiplying the unit cost by the annual quantity needed.22Adapted from WASH (1988).34