Exploration of a suspected site of old landfills from historical research and exploratory investigation to basic waste characterisation and hazard assessment – using the example of a site in Leer
M&P Ingenieurgesellschaft Hannover – a member of the SIERA Alliance – was commissioned to carry out a detailed investigation of a site in Leer as part of a planned construction project. The aim was to clarify whether known old deposits from the surrounding area protrude into the area and whether previous or current uses could potentially have led to soil or groundwater contamination.
This article provides an insight into the structured approach of M&P Ingenieurgesellschaft Hannover – from historical research and orientation investigation to basic waste characterization and initial hazard assessment.
1. Historical research: Basis for every reliable assessment
At the beginning, historical documents were systematically collected and evaluated. These included in particular:
- historical maps
- Aerial photos of different eras
- Multitemporal evaluations of land use
The analysis showed that it was not possible to completely exclude possible offshoots of an old deposit adjacent to the south. This resulted in an immediate need for investigation, which M&P Ingenieurgesellschaft Hannover then deepened in the field.
2. Orientation investigation: small-scale ram drilling, dredging and groundwater sampling
Based on the results of the research, a targeted exploration of the subsurface was carried out. To this end:
- Small pile driving boreholes (KRB) sunk
- Excavator trenches created
- Pile driving level for groundwater sampling installed in the inflow and outlet of the current plant
Results of the ground approach
- Eastern study area: largely inconspicuous soil conditions
- Western siting area: significant landfill residues came to light in the southern section
- up to 50% external shares
- Materials: metal, rubble, glass, ceramics
- Clear assignment to the known southern old deposit
These findings confirmed the suspicion that parts of the historical deposits extend into the site.
3. Waste law investigation and analysis in accordance with the Substitute Building Materials Ordinance
Since soil is produced as displacement material during the planned construction project, the samples taken were extensively analysed. M&P Ingenieurgesellschaft Hannover carried out investigations in accordance with:
- Substitute Building Materials Ordinance (EBV)
- Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV)
- Soil-human pathway
- Soil–groundwater pathway
Analytical results
The consistency of the pollutant patterns was remarkable:
- Similar pollutant profile in:
- of the landfill sample
- of the immediately adjacent groundwater sample
This suggests that pollutant input into the groundwater from the landfill residues.
At the same time, the sands below the deposits showed no abnormalities.
4. Initial risk assessment: What can already be said?
In the course of the exploratory study, the following facts could be clearly delineated:
What could be ruled out
- There is no soil or groundwater contamination due to the current environmentally relevant use of the site.
What remains unclear
- It has not yet been possible to conclusively clarify whether the observed groundwater contamination is clearly due to the landfill residues.
This means that there is a need for further investigation, especially for the exact determination of the origin of the pollutants.
5. Necessity of a detailed examination (DU)
In order to be able to conclusively assess whether there is a hazard according to the BBodSchV, a detailed investigation (DU) is required. This is intended to:
- Clearly determine the origin of the contamination
- Analyze the soil-groundwater pathway in depth
- Enable a reliable risk assessment at the site of assessment
- Creating a data basis for possible measures or remediation concepts
M&P Ingenieurgesellschaft Hannover – a member of the SIERA Alliance – will once again apply a structured, standard-compliant approach in order to create clarity for the client and the planned construction project.
6. Table: Overview of the examination modules
| Investigation module | Objective | Result / Insight |
| Historical research | Examination of usage history & old deposits | Suspicion of foothills of the southern deposit remains |
| Small pile driving drilling & excavator trenches | Testing of soil conditions | Landfill residues in the west up to 50 % foreign substances |
| Groundwater samples | Assessment of the soil–groundwater impact pathway | Similar pollutant pattern to landfill sample |
| Waste law analysis according to EBV | Evaluation of BV-external recycling | Site shows contamination in backfill material |
| Basic risk assessment | Clarification of potential risks | Cause of GW contamination still unclear; current use inconspicuous |
| Recommendation DU | Further clarification | Required for final assessment according to BBodSchV |
Result
The study shows that historical deposits can still have environmental relevance decades later. M&P Ingenieurgesellschaft Hannover – a member of the SIERA Alliance – has created a sound basis for further evaluation through structured research, targeted terrain surveys and standard-compliant analytics.
A detailed investigation is now the next necessary step in order to be able to conclusively assess the risk situation.
Call to action
Are you planning a construction project, need support with the assessment of contaminated sites or would you like to have a risk assessment carried out in accordance with the BBodSchV?
👉 Contact M&P Ingenieurgesellschaft Hannover – your experts for environmental technology, contaminated sites and geotechnical investigations.
