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E10160-200722 FOP
Page 18
Suggested Grout Mixes
Material Ratio by
weight
Soil Hardness Material Ratio by
weight
Soil Hardness
Portland Cement 1 Hard to Medium Portland Cement 1 Soft
Bentonite 0.3 Hard to Medium Bentonite 0.4 Soft
Water 2.5 Hard to Medium Water 6.6 Soft
See article from Marefat, Contreras for more information about this technique of
installation.
3.5 CABLE IDENTIFICATION
The cables are identified with the gauge factor that is labeled on the piezometer housing.
The gauge factor is stamped on a tag that is fastened to the readout end of the cable. Should
the cable be cut, we recommend the use of our cable splice kits.
3.6 CABLE ROUTING
Transition from vertical borehole to horizontal trench
The cable should be routed along a curved path as it goes from a vertical to the horizontal
position. At the collar of the borehole, embed the cable along a large radius circular path
within a cushion of screened sand and 5% bentonite mix, hand compacted to the
surrounding fill density.
Piezometers installed to monitor rock contact zones are generally installed in shallow
boreholes to protect them against concentrated loads or movements. Run cables emerging
from these holes through the dam core and locate the vertical to horizontal cable transition
zone above the rock surface. Do not lay the cable directly on rock.
Horizontal cable runs
Two methods are currently used to protect horizontal cable runs from damage. Embedment
within selected materials on surface of the fill or in a trench within the fill. Only the latter is
discussed here. Surface installations require continuous surveillance and protection from
the earth moving equipment circulating on the fill. For a description of this method, please
refer to Clements (1982), reference A-6 in Section 6.
Some of the more important considerations that must be given to horizontal cable runs are:

Avoid traversing transition zones where large differential settlements could create
excessive strain in the cable.

Avoid cable splices - if necessary, use only our approved splice kits.

Do not lay cables one on top of the other.

Use horizontal snaking or vertical snaking of the cable within the trenches. For most
materials, a pitch of 2 m with an amplitude of 0.4 m is suitable. In very wet clays
increase the pitch to 1 m.