Geological reports

What it is for

The geological report reconstructs the geological model of the site — the succession of soils and rocks, the geomorphological setting, groundwater circulation and hazard conditions — and assesses how it interacts with the planned works. It is the document on which geotechnical and structural choices are based, together with the check that the works are compatible with the territory.

When it is mandatory

Under Ministerial Decree of 17 January 2018 (Italian Building Code, NTC) and its Circular no. 7 of 21 January 2019, a geological report is generally required for:

• new civil and industrial buildings;
• extensions, additional storeys and works that change structural behaviour or transfer new loads to the ground;
• foundation works, retaining walls and support structures, significant excavations and fills;
• works on existing buildings involving seismic upgrading or improvement;
• urbanisation works, infrastructure, tanks and underground structures;
• urban planning instruments and their variants (geological component).

At regional level, Lombardy also applies the provisions on the geological, hydrogeological and seismic component of planning (Regional Council Resolution IX/2616/2011 and later updates) and the procedures of the regional seismic desk.

What it contains

• Geographical and cadastral framing of the area and description of the works;
• Geology and geomorphology: lithology, structural setting, landforms and ongoing or potential processes;
• Hydrogeology: permeability, aquifers, water-table depth and fluctuation;
• Seismicity: basic seismic hazard, subsoil and topographic category, expected local effects;
• Investigation programme and results (boreholes, penetration tests, geophysics, laboratory tests);
• Reference geological model: interpretative logs and sections, geological parameters;
• Geological hazard and feasibility: opinion on the compatibility of the works, requirements and recommendations for geotechnical design.

Geological report and geotechnical report

They are two distinct and complementary documents:

Geological report

describes the geological model of the site and falls within the competence and signature of the geologist.

Geotechnical report

translates the geological model into a geotechnical model and into the design checks of the works; it may be drafted by the geologist or the engineer according to their respective competences, starting from the data and characterisation provided by the geological report.

The practice can provide both documents, or the geological report alone with the geotechnical characterisation of the soils, working together with the structural designer.

Procedure and timing

1. Assignment and site visit — review of the project, collection of mapping and existing data, definition of the investigation plan.
2. In-situ investigations — geophysical and penetration tests (usually in a single field day for a building plot); boreholes, if any, with a specialised contractor.
3. Processing — data analysis, definition of parameters, drafting of the report and graphic annexes.
4. Delivery and filing — transmission of digitally signed documents and support for filing with the municipal building office (SUE) and, where required, with the seismic desk.

Delivery times depend on the type and number of investigations needed and are agreed at the quotation stage; for an ordinary building plot the report is generally available within a few working days of carrying out the investigations.

Useful documents for the quote

• Address and cadastral references of the plot
• Description of the works (new building, extension, support structure…)
• Available drawings (site plan, sections, foundation plans)
• Any previous investigations or geological reports on the area