8.2　Site Investigation

8.2.1　During site investigation for distinct pipeline points，the present distribution conditions of distinct pipeline points of underground pipeline shall be found out according to the underground pipeline present investigation diagram and underground pipeline present investigation deliverables，and based on the actual site conditions.The exposed underground pipeline on the distinct pipeline points and pipeline associated facilities shall be investigated，measured and recorded in detail.

8.2.2　For site investigation of underground pipelines，the features of pipeline points and attribute data including type，name，specification and material of each pipeline shall be found out.For distinct pipeline point，the burial depth of pipeline shall be measured，and the spatial data of pipeline including routing and flow direction shall be found out.The record sheet for underground pipeline investigation and detecting shall be filled out.

8.2.3　In investigation of underground pipelines，the burial depth of pipeline shall be found out according to the type of underground pipeline and the specification in Table E.0.1 in Appendix E of this Code or the requirement of client，and shall comply with the following specifications:

1　The burial depth of internal bottom of gravity-flow pipeline or underground pipe trench shall be measured.

2　The burial depth of external top of pressure pipeline shall be measured.

3　The burial depth of external top of direct burial cable/optical cable，protection pipe and conduit for cable/optical cable shall be measured，and the burial depth of the internal bottom of cable or optical cable trench should be measured.

4　For road-crossing protection pipe，pipe trench or underground pipeline on pipe-jacking construction site，the burial depth of the external bottom of those shall be measured.

8.2.4　The investigation for distinct pipeline points including pipeline branch points，crossing points and different wells shall comply with the following specifications:

1　For pipeline points including pipeline branch points and crossing points，the plane position，burial depth of external top or internal bottom of all the pipelines shall be measured.

2　For pipeline in the well，the setover offset from all the pipeline center to the center of well cover，and the burial depth of pipeline external top or internal bottom against the edge of well shall be measured.In case of elevation difference between the edge of well and ground surface near well，the burial depth of pipeline buried under the ground near well shall be measured at the same time.

3　The pipeline section controlled by valve，instrument and water meter in the well shall be found out as well as the attribute data and spatial data of all the branch pipelines.

4　The measurement of pipeline burial depth shall comply with the specifications in Article 8.2.3 of this Code，and all the attribute data and spatial data of all the pipelines shall be recorded during investigation.

8.2.5　When setting up distinct pipeline point on the well，the position of such pipeline point shall be set at the center of well cover.If the position of ground surface projection of the centerline of underground pipeline deviates from the pipeline point，and the setover offset is equal to or exceed 0.1m，the pipeline point shall be set up at the position of ground surface projection of the pipeline，and the well shall be handled as discipline pipeline attachment.The unit of setover offset is“m”.

8.2.6　The cross-section size of the pipe trench and protection pipe or conduit of underground pipeline or cable/optical cable shall be measured.The internal diameter of round cross-section shall be measured，and the width and height of the internal wall of rectangular cross-section shall be measured.The unit is“mm”.

8.2.7　For pipeline laid in the underground pipe trench，the attribute data and relative spatial position of all the pipelines shall be found out，and the cross section diagram should be compiled on site.

8.2.8　For the electric power cable，control/telecom cable or optical cable laid underground in pipe trench，protection pipe or conduit，the number of cables/optical cables and the total number and used number of protection pipes and conduits should be found out.

8.2.9　In detecting area，for item of which the distinct pipeline point is not available，or the existing distinct pipeline point cannot but shall be found out，the personnels who are familiar with the underground pipeline in this survey area shall be invited to participate，or site investigation and measurement are done by other detecting method or excavation.