Environmental Engineering Reference
In-Depth Information
there is surplus water in the galleries, part of this
flow cannot be stored in irrigation pools. The fol-
lowing problems are generated.
The high cost of pipelines from catchment
to the raft. Flow losses in the transport of water
(approximately 25-30%). evaporation losses once
stored in the raft.
The underground drilling once it enters the
saturated zone, is draining the water, once enough
has been drilled to obtain a target flow, planned or
economically and socially profitable, is preparing
to channel the flow through the pipe or channel
to areas of consumption. The average length of
drilling in the Western isles is between 1,500 and
2,500 meters, each island has its gallery average
length as a function of their geological characteris-
tics, while currently on the island of el hierro are
under the mean lengths in the island of Tenerife
has higher average lengths some galleries with over
4,000 water meters.
in the case of a borehole or a well no more com-
plex the regulation of water flows, is sufficient to
disconnect the pump.
Figure 3. concrete dike and hatch access to the next
section of the gallery of water.
With regard to the geotechnical characteristics of
the terrain to be excavated, usually is a massive
material, like basalt, no stability problems. scoria-
ceous material in part, the pyroclastic often result
in more rounded section, before it can be used to
support systems can be a good option use shotcrete
cement, with the task of arming the field.
The gallery is usually constructed with an straight
line, although at times, and because the different
materials are encountered with different geotechnic
properties, there may be changes in direction, at cer-
tain times of the excavation.
The first kilometers usually run dry, when we
enter the into the aquifer, the infrastructure is
introduced into the saturated zone, water flow
is not adjustable, leaves in continuous due to the
slope built into the exit of the gallery.
along the trace of the water gallery covers sev-
eral dikes which are listed with Roman numerals
to the left of the trace, is usually choose later, for
geomechanical closures, depending on the quality
of the dike, width, minimum of 6 m, finally the
water that dikes can store and its area of influence,
these closures represent a significant innovation in
this type of drilling, because the geomechanical
closures can store water in the aquifer and regulate
their use.
2.2
Construction method
once selected the dikes, following the methodology
of the engineer soler liceras in 1996, dug three feet
wide to include the reinforcement of concrete and
steel bolts that will make this artificial structure in
solidarity with the basalt dike.
The assembly of the reinforcement of concrete
needs to replace cast iron pipes that are responsible
for draining the water from one area to another
and remove water from the gallery, we must record
that can be done several dikes in a single opera-
tion in according to the capacity of the aquifer and
geologic structures that are available.
We must also give way to vent pipe for further
drilling.
once it is finished metal structure, is followed
by the concrete pump. With the concrete we have
to consider the environment in which to build the
structure, leaving space for the door be left large
enough for the operation of the gallery according
to the initial dimensions.
We have to bear in mind that, if cracks form our
gallery exploitation is destroyed by high pressure
water, the most contentious in this regard is the
gate, so we have to include some wetsuits and test
the installation.
The gate must withstand the high pressures
exerted by water at extrados, which in the case
studies have reached 72 m of water column, as
is the case in the gallery of los Padrones on the
island of el hierro (spain). This gate is made of
steel and made to measure, although in the last gal-
lery, where this infrastructure has been included in
2
UnDeRGRoUnD WaTeR UsinG Dikes
2.1
Stating the problem
as has been said the main problem of the galler-
ies, is the lack of water resources regulation, which
means that once it has penetrated into the aqui-
fer, the water flows continuously therefore cannot
regulate the water flows.
This poses a problem, especially in winter, when
there is a good rainy season, at that time of year
