STG Engineering - Geotechnical Site Engineers

STG Engineering is a small geotechnical consultancy based in the South Hams with over 18 years’ experience. Working alongside local architects, civil engineers, structural engineers and builders we offer high quality geotechnical sitework to include:

• Infiltration Testing for Soakaways
• Percolation Testing for Drainage Fields
• Slope Stability (Rock & Soil)
• Ground Investigations
• Waste Classification Testing
• Compliance Testing of Engineered Fill

We offer competitive rates including a free initial site visit to discuss your needs; with a quick and efficient turnaround. Upon completion of site work, a specific report is issued ranging from basic to comprehensive dependent on your requirements.

Soakaway & Drainage Field Testing:

We undertake Soakaway Testing (infiltration) in accordance to BRE Digest 365 and can source all necessary plant (excavator, tractor and water bowser). Upon completion of site work we calculate the soil infiltration rate (f) and produce a Surface Water Drainage Assessment Report for your planning application. If your site is within Flood Zone 2,3 or within a Critical Drainage Area (Kingsbridge, Ivybridge and Modbury) we can also produce a relevant Flood Risk Assessment (FRA). If soakaways are not feasible (limited space, poor infiltration rate etc) we can produce a Drainage Strategy Report where we move down the surface water drainage hierarchy to either discharge to watercourse (if available) or discharge to sewer with consent from South West Water.

We undertake Percolation Testing for Foul Water Drainage Fields in accordance to BS6297: 2007 (and Building Regulations Approved Document H2 – Drainage and Waste Disposal 2015) for sites that are not on mains sewerage. Upon completion of site work we calculate: percolation value (V_p), subsequent floor area (A_t) and the lengths of perforated pipe required, and provide recommendations for the drainage field. This is detailed within a Foul Water Percolation Test Report for your planning application and we can also complete the necessary FDA1 Form.

In addition, we can recommend a local supplier for all your drainage equipment, in conjunction with local installers.

Slope Stability Analysis:

We undertake visual assessments on both rock and soil slopes including: cliffs, cuttings and embankments to identify the cause and extent of failure, whether further failure is expected and recommendations as to the remedial actions required. Recommendations may include further assessment and monitoring, in conjunction to a Ground Investigation or a detailed rock inspection using rope access engineers that we can source.

Upon completion of site work, a Slope Stability Report is issued outlining recommendations and options for remedial works. This can be passed on to specialist design engineers for approved remedial works if required.

Ground Investigations (Phase 1 & 2):

Phase 1 – Site walkover in conjunction with OS Maps, documents and databases to produce an interpretative desk study report outlining site settings, potential geological hazards and environmental issues including potential site contamination.

Phase 2 - Intrusive investigation tailored to your requirements to determine the engineering properties of soil and rock. We obtain necessary geotechnical parameters for foundation and/or retaining wall design and to distinguish different strata, soil strengths/densities and determine depth of bedrock. Site work involves: Trial Pits (hand-dug using insulated tools to 1.20m depth and/or machine excavated to ~4m depth), Windowless Sampler boreholes (using a small tracked rig undertaking core samples to depths of 5m, Standard Penetration Tests (SPTs) to depths of 8m and continuous Dynamic Probes (DPs) to depths of 12m) and Rotary boreholes (large tracked rig e.g Commachio 205 that is capable of core samples to depths in excess of 30m).

Samples are obtained for analysis and subsequent geotechnical testing is undertaken in a UKAS accredited laboratory whilst geo-environmental (contamination risks to human health, property and the surrounding environment e.g hydrocarbons, heavy metals and asbestos) is undertaken in a MCERTS accredited laboratory. 

Within the boreholes, standpipes can be installed for monitoring of gas, groundwater and movements. We can undertake rounds of monitoring to identify any gas (methane, carbon dioxide, oxygen, hydrogen sulphide and carbon monoxide), groundwater levels on site and obtain groundwater samples for geo-environmental testing.

Upon completion of all works an Interpretive Ground Investigation Report (GIR) is issued.

Waste Classification Testing:

If exporting any soil offsite (deemed waste) to a local exception site (U1) we can obtain necessary samples for Waste Classification Testing in a MCERTS accredited laboratory. Upon receipt of results, analysis is undertaken outlining status and classification. Please note, whilst the classification of waste is within our remit, how you dispose of this material is not the responsibility of STG Engineering Ltd.

Engineered Fill:

We can undertake a range of in-situ tests to ensure adequate compaction of engineered fill has been achieved as per the specifications within a Geotechnical Design Report (GDR) in accordance to BS 1377 and includes: Plate Load Tests (PLT’s), plate CBR’s, hand-held Dynamic Cone Penetrometers (DCP’s), Sand Replacement Density (SRD) and Shear Vanes.  

Upon completion of works a comprehensive Earthworks Validation Report is issued.

Site Supervision:

With CSCS, IOSH and Emergency First Aid Trained we can work on a variety of sites undertaking monitoring and supervision of site work, earthworks, ground investigations and engineered fill.

Furthermore, Personal Track Safety (PTS) and Individual Working Alone (IWA) competency allows work to be carried out on the railway sector.

Full geotechnical logging (Structural, Interval and Sampling) can be undertaken on rock cores for mining and civil industries.

Call us or send us a message via the green message button to discuss your requirements