Part D - Minimum requirements on site investigations 
35 
summarising geological assessment is added. In addition, for classification in accordance 
with DIN 18311, characteristics of undrained shear strength (for cohesive soils) and the den 
sity (non-cohesive soils) should also be stated. Further details regarding reporting and carto 
graphic representations can be seen in Table 10. 
Table 10: Requirements of the geological-geotechnical survey and investigation for cable 
route corridors. 
Corridor investigation 
Monitoring 
Objectives 
• Establishing the actual installation route 
and the cable length 
• Creating the planned cable route corri 
dor with regard to bathymetry and mor 
phology incl. all aspects relevant to 
cable installation 
• Investigating the composition of sedi 
ment, the geological bedding condi 
tions and the geotechnical properties of 
the upper levels of the seabed incl. all 
relevant aspects for cable installation. 
• Mapping wrecks, other obstacles and 
also munition if there is evidence that 
such has been deposited 
• Exact positions of existing cables and 
pipelines 
• Detecting potential hazards to the cable 
• Monitoring riprap or similar measures 
to protect the cable 
• Detecting the mandatory minimum level 
of cover with sediment to ensure that 
the cable is protected from hazards 
Scope 
• Investigating the planned cable route 
corridor using geological, geophysical 
and geotechnical methods 
• Area-covering survey of a corridor, the 
width of which corresponds to the 
width of the planned cable route corri 
dor plus a clearance of at least 50m on 
both sides of the corridor, with side 
scan sonar and multi-beam echoso- 
under(MBES). 
• Linear measurement of the planned 
cable route corridor with high-resolu- 
tion subbottom profiling methods 
• Monitoring of the entire cable route cor 
ridor in the first few years 
• After a suitable database has been 
submitted, modified monitoring inter 
vals can be requested for periodic 
investigations 
Timing 
• As a one-off for planning installation, a 
repeat measure is required close to the 
installation date in morphologically 
changeable areas 
• In the initial years after installation 
check once per year, early on in the 
year