QUESTION $4[20$ Marks$]$

a$)$ Explain the usage of air valves in water pipelines construction; and list down and sketch out using symbols the fittings and accessories required to construct drainage crossing cross a $1\mathrm{.}5$ m width drains and the location of air valves.

$[6$ marks$]$

b$)$ Explain the term 'Budgets' and 'Estimates' in the context of civil engineering construction projects and provide a detail estimate of a $1\mathrm{.}5$ km drain construction. Drain is $500$ mm wide and $1000$ mm depth.

$[8$ marks$]$

c$)$ Design a Bills of Quantity for a cast in situ concrete single storey house including foundation and metal roof structure.

$[6$ marks$]$