r - part - usaid

farms part of the broad overhezd c ~st of WDA administration.
The ma&el assumes three visits to the site by the
hydrogealogfst and assistant (Appendices 4.4.9 znd 4.4.2, Table
The purpose of the first visit is site selection, the
second visit occurs during cirilLizg, and the third visit is fur
aquifer testirg. Scme time is allowed at the office for
analysis and reportisg. The difference in cost between the two
versions represents the difference in cine allowed for travel to
the site. The total times estimated for the hydrageological
work in the Bay Segion and the Central Range are 15 and 24 days
respectively.
4-1-3. Drilling
As ran be seen from Figures 2 .4.; and 2.4.2, the actual
drilling phase. af weif construction is the most significant.
These figvres exclude WDA overhead costs kt include direct
costs, capital recovery, anc? aaintenance charges. Drilling
accounts for alms? 50% of the total cast of a well equipped
with a diesel puzp in the Bay Region, and for over 63% in tke
Central Range. From Fiqures 2.4.3 and 2.4,4 the percentages
rise to 808 and 66% respectively for wells equipped with a
bandpump.
The average depth of a borehole in the Bay Region program
is taken as 12031 [Appendix 4,4.1, Table 2). For the Central
Eange program, 150m is assuaed (Appendix 4.4.2, Table 2). In
both cases a 5n surface casing is assumed, an average of 16n of
steel screen is used, acd the remainder of the hole is lined
with solid steel casing. The nodel does net automatically
relate the depth to the time taken to drill the well. Drilling
time is dependent upon a number of other variables.
Based on projecx experience, a drilling crew in the Bay
Zegiun has been employed on each production borehole for an
average of 35 days, and on each exploratory borehole for 23 days
(Table 2.015). Tn the Central Range, the corresponding figures
are 57 days and 38 days (Table 2.4.6). On average, an
exploratory wall takes two tkirds the time of a production well.
he model bases the cost for IzSuux, and, more signficantly, for
running coscs, capital replacement, and spares and maintenance
for all equipment and vehicles, on this nu~,ker of days. This
rule is only varied fox calcula%kng the fuel costa of the drill
rig,