Explosive ordnance investigation for sewer construction and drainage

Investigation should begin once the route, shaft locations, construction method, trench depth and construction sections are sufficiently identifiable. For new construction, renewal, stormwater retention basins, pumping stations, culverts or open utility trenches, the suspected hazard, existing utilities, dewatering and accessible investigation volumes must be brought together before tendering.

The utility trench, shaft excavations, property connections, pumping stations, retention basins, culverts, launch and reception pits and site establishment areas differ in area, depth and access. An area survey of the route corridor does not automatically address deep shafts or bore paths. Each ground volume therefore receives its own location and depth reference.

Stop work in the affected area immediately. Do not touch or move the object or expose it further. Leave the immediate area, keep others away without putting yourself at risk, and in Germany notify the police immediately on 110. Outside Germany, use the local emergency reporting route. Then inform site management. The responsible authorities determine further investigation and the involvement of the explosive ordnance disposal service under the local procedure. A measured anomaly alone is assessed under the agreed specialist investigation procedure.

Shafts and pumping stations often require deep excavations, shoring, dewatering and localised foundations. Investigation must cover the excavation geometry, shoring alignments, base elevation and any piles or anchors. Near-surface surveys are sufficient only if the entire ground volume of the subsequent works can be technically covered and assessed by a specialist.

Where possible, provide site and route plans with chainage, pipe dimensions, invert levels, shaft lists, excavation and shoring details, open-cut or trenchless construction method, construction sections, existing utilities, dewatering, historical assessments and existing survey reports. Incomplete existing-condition plans are also relevant if their uncertainty is identified.

Include existing information and conditions from authorities with their dates, complete attachments and spatial scope. In Germany, the responsible explosive ordnance disposal service, local public order authority and, where applicable, building control authority are identified for the project location. Outside Germany, coordination takes place with the authorities responsible there. Outstanding questions are assigned to the actual construction section.

The work is linked to the section sequence, traffic management, dewatering, material logistics and access. Areas that can be surveyed are brought forward where possible. Necessary investigations and protective measures are defined before groundworks during demolition or surface removal. Areas accessible only afterwards receive their own investigation date. Where an explosive ordnance survey alongside construction is technically suitable, technical investigation and assessment of each working layer are scheduled before controlled removal. Supplementary visual inspection, excavation layers, hold points and documentation are agreed before work begins; the sequence is repeated down to the agreed excavation base.

The documentation links the route, chainage, shaft or structure identifier, plan revision, method, depth reached, interference zones, anomalies, outstanding areas and follow-up decision. This makes it possible to trace which utility or shaft section was investigated and which measures are still needed before the next civil engineering step.

Decisive factors are route length, working width, trench depth, number and depth of shafts, traffic phases, utility density, surface, construction method, dewatering, necessary depth investigations, inaccessible areas and documentation scope. A reliable cost calculation therefore requires clear plan revisions, chainage and construction section priorities.