5.4 Preliminary information needed before starting sampling and groundwater measurements
At least the following preliminary information shall be available at the site before the sampling and/or groundwater measurements can start (see e.g. Annex A):
- a) objective of the sampling and groundwater measurements;
- b) location of the planned boreholes or excavations or groundwater measurements;
- c) orientation, inclination and acceptable deviations in boreholes;
- d) surveying requirements, and expected geological and hydrogeological conditions;
- e) required accuracy and uncertainty of measurements in accordance with the Guide to the expression of uncertainty in measurement;
- f) frequency of measurements;
- g) environmental and safety risks associated with, e.g. flushing media or suspensions intended to be used as well as regulations for their use;
- h) possible risks, e.g. underground and overhead services, traffic, unexpected and unexploded ordnance, contamination;
- i) identification and planned depths of boreholes and/or excavations;
- j) sampling method and sampling category intended;
- k) requirements on numbering of boreholes, excavations or samples;
- l) sample handling, storage and transport intended;
- m) in situ tests intended;
- n) borehole or excavation completion method and site reinstatement (backfilling or grouting);
- o) environmental care;
- p) emergency arrangements;
- q) name of contact person;
- r) the planned flow of information.
5.5 Backfilling and site abandonment
5.5.1 When sampling is completed it is of the utmost importance that the site is restored and no hazardsare left which would be of potential harm to the public, the environment or animals. The backfilling shall be carried out in accordance with national regulations, technical or authority requirements, and take into consideration the strata, contamination of the ground and its bearing capacity.
5.5.2 Every borehole and excavation shall be fenced or temporarily capped in a safe manner until the borehole and excavation is finally and permanently capped or backfilled.
5.5.3 Unless a borehole is required to be kept open for a specific purpose, it shouldbe infilled, consolidated and capped in such a manner that there will be no subsequent depression at ground level due to the settlement to the infill material.
5.5.4 Boreholes shall normally be filled with materials of equal or less permeability than the surrounding ground, e.g. in order to prevent contamination and connections between aquifers. If mixed grout is used, it should be placed by means of a tremie lowered to the base of the borehole. The tremie shall be slowly raised as the grout is placed. If there is an influence on future projects, special technical requirements for backfilling shall be specified in advance, e.g. for tunnel projects. Voids shall not occur during the placement of the filling material in the borehole.
5.5.5 The site should be left in a safe, clean and tidy state.
5.6 Safety and special requirements
5.6.1 Regarding safety on the site and safety of the working practices, the respective national standards, specifications or statutory requirements for execution of boreholes, trial pits, heading and shafts shall be applied, as long as respective international standards are not available.
Drill rigs shall be in accordance with EN 791 and EN 996.
5.6.2 Regarding nuisance and environmental protection, for each particular situation, as long as respective international standards are not available, the national requirements and the local requirements shall be applied.