In April 2020 Risk Management Limited were instructed by Affinity Water to undertake an intrusive soil investigation to determine the proposed route for a 700mm diameter mains between Blackford Booster and Ickenham Booster. The project was part of a larger 20-year investment programme named Supply 2040
A total of 22 No. boreholes were drilled along 3 proposed linear routes for the mains pipeline using a tracked window sampler rig. Boreholes were drilled to depths of between 2.00m and 10.00m below existing ground level.
A large area of the site comprised a former Landfill and in addition to geotechnical testing on samples recovered to aid sub-structure foundation advice, numerous contamination and waste acceptance criteria (WAC) tests were scheduled to provide information to assist in the best possible route for the mains pipe.
Risk Management Limited were commissioned to undertake Trial Pits against existing foundations at basement and ground floor level across a Grade II listed warehouse in Limehouse Cut.
The work involved undertaking twenty-three hand excavated Trial Pits, assisted by a mini-excavator with breaker at certain locations, to find column/pad undersides. Trial Pits were logged, photographed before backfilling and reinstating as per the existing make-up.
In addition 3 No. concrete cores were undertaken across the site to assess the slab structure.
Risk Management Limited were employed to undertake both a Phase I, non-intrusive, Desk Study and a Phase II, intrusive, Site Investigation at a large parcel of land in Romsey, Hampshire.
The work involved thirteen light percussion boreholes, thirteen MEXE Probe CBR tests and twenty-two Soil Infiltration Tests. Falling head permeability tests and land -borne gas monitoring completed the fieldwork.
Comprehensive geotechnical and contamination testing were scheduled to provide allowable bearing pressures and advice for the remediation of the site.
Risk Management Limited were commissioned by Derek Lofty & Associates to provide information on the existing slab and sub-soil conditions at Whitehawk Bus Depot in Brighton.
The investigation consisted of a number of concrete cores through the existing slab to note the overall depth of concrete and presence and size of reinforcement. Unconfined compression tests were subsequently undertaken on the cores retrieved to determine the core strength.
In addition to the slab assessment, three boreholes were sunk through the aforementioned cores to determine the underlying soil conditions and two hand excavated trial pits to assess the existing foundation make-up and depth. Contamination and Asbestos identification were also undertaken.
Risk Management Limited were employed to undertake intrusive work at a Primary School in Brixton, South London to provide the Consulting Engineers, Pellings LLP, information on the existing structure.
The work consisted of six hand excavated trial pits against existing walls to uncover the foundation make up, dimensions and depth to underside. Furthermore, the internal walls and roof structure of the building were opened up in six areas to ascertain the make-up.
Risk Management Limited were employed by local house building company Alfred Homes to undertake a full BRE 365 Soil Infiltration Test at a property in the village of Weeke, Winchester.
A 3 ton mini excavator was utilised owing to the access restraints to dig a trench to 2.70m depth, with sides and base kept as straight as possible. The trench was then measured and the strata photographed and logged before filling using a 2000 gallon lorry mounted bowser. The rate of fall was then used to calculate a Soil Infiltration Rate (f) which facilitates drainage design by others.
Risk Management Limited were commissioned to install 2 No. deep borehole Soakaway installations for a new care home in Chesham, Buckinghamshire.
The work involved undertaking two 15m deep cable percussion borehole in 8” diameter through the superficial beds and into the underlying Chalk strata. After a basic permeability test two 6” diameter soakaways were subsequently installed to 15m depth within each borehole.
Following installation three falling head tests within each soakaway were performed using a 2000-gallon lorry mounted bowser and hose and more than adequate soakage was observed.
Risk Management Limited were commissioned to undertake a Phase II, intrusive, Site Investigation at an existing Warehouse in Merton, Surrey. The investigation comprised verification of the existing slab condition and surrounding ground conditions for a small Barrier Booth building adjacent to the warehouse.
A concrete coring crew were subcontracted to core the existing warehouse slab in multiple locations with the resultant cores scheduled for Unconfined Compressive Strength testing. Drive-in-Sampler boreholes and MEXE Probe CBR tests were undertaken within the above-mentioned core holes to enable foundation design parameters.
Risk Management Limited were instructed to undertake a Land-Borne Gas Risk Assessment requested by North West Leicestershire District Council at a site of a former open-cast mine in Ashby-De-La-Zouch.
The work involved monitoring a number of gas standpipes, installed by RML across the site, at two-weekly intervals over a period of 18 weeks. Concentrations of Carbon Dioxide, Oxygen, Methane, Hydrogen Sulphide and gas flow were measured along with Volatile Organic Compounds (VOC’s).
Risk Management Limited were commissioned to undertake a Phase II Site Investigation at a parcel of land in Ashford, Kent for a proposed Extra Care Facility.
The underlying geology of Weald Clay can be difficult to penetrate with standard drive-in-sampler/window sampler techniques and consequently Cable Percussion techniques were employed to achieve the required 15m depth.
In addition to geotechnical testing and Waste Acceptance Criteria (WAC) tests, a full BRE 365 Soil Infiltration Test was also undertaken to inform drainage design and assess the capability of the underlying ground for potential soakaways.
Risk Management Limited were instructed to undertake a Phase I Desk Study and Phase II Site Investigation at a parcel of land adjacent to Redhill Train Station for a proposed multi-story residential development in the heart of Redhill town centre.
The underlying geology in Redhill, of the Sandgate Formation, required RML to employ Rotary drilling techniques in order to penetrate the sandstone to the required depth.
A comprehensive suite of both geotechnical and chemical tests were undertaken to inform the developer of foundation design parameters and environmental requirements for the site.
Risk Management Limited were commissioned by WCJ Structural Engineers to undertake a ‘heave assessment’ at a property in Tonbridge, Kent.
Due to excessive cracking on the property an 8m deep borehole was undertaken close to the area of interest. A moisture content profile was undertaken and, by comparing this to assumed ‘equilibrium’ natural moisture contents, a Heave Assessment was undertaken.
Risk Management Limited work regularly with many local developers who often instruct us to undertake a ‘package’ consisting of a Phase I, non-intrusive, Desk Study and Phase II, intrusive, Site Investigation with contamination assessment, gas/groundwater monitoring and an Interpretative Report.
This package was utilised at a site in Sutton, Surrey, where the intrusive investigation comprised one 7m deep borehole with in-situ SPT testing and 3 shallow drive-in-sampler boreholes. Subsequent permeability, gas/groundwater monitoring was undertaken along with two contamination tests including asbestos.
Risk Management Limited were commissioned to undertake a Phase I, non-intrusive, Desk Study and Walkover Survey together with a Phase II, intrusive, Site Investigation at a parade of shops in Dollis Hill, London. The proposed development included the demolition of existing buildings and garages and the construction of a multi-storey building with associated landscaping and parking areas.
Two 20m deep cable percussion boreholes and six shallow drive-in-sampler boreholes were undertaken across the site to aid in providing geotechnical information. In addition, soakage tests to BRE 365 were undertaken to assess the soakage properties of the underlying geological strata and gas/groundwater monitoring performed.
Laboratory testing included the normal geotechnical testing as well as Oedometer tests and Contamination and Waste Acceptance Criteria (WAC) testing.
Risk Management Limited were commissioned to undertake a Phase I, non-intrusive, Desk Study and Walkover Survey and Phase II, intrusive, Site Investigation at an existing National Grid Car Park. The Phase I, non-intrusive, Desk Study found that the site lay within the boundary of the ‘Chartered Gas Works’ in 1877, by the end of the nineteenth Century the majority of the Gas Works had been removed.
A four to five storey office/residential building was proposed at the site. Due to the past usage of the site as a Gas Works the site was designated a ‘Red Site’ in accordance with the ‘Specification for Ground Investigation’ publications by the Site Investigation Steering Group of the ICE.
A total of three deep cable percussion boreholes and six shallow drive-in-sampler boreholes were undertaken across the site to provide suitable information to allow for foundation design. Subsequent gas/groundwater monitoring was undertaken on six occasions along with organics measured using a MiniRae Lite PID.
Laboratory testing included the normal geotechnical testing as well as Coal Tar, SVOC and TOC analysis and groundwater contamination testing owing to the past usage.
Following on from the Phase I and II work noted above a Phase III Remediation Method Statement and Phase IV Verification Report were undertaken.
Risk Management Limited were contracted to undertake an intrusive Site Investigation along the linear route for a new watermain running from Childrey Warren Water Treatment Works (WTW) to Lark Hill Reservoir for Thames Water. Thames Water are committed to ceasing water abstraction at Childrey Warren WTW and the proposal to construct a link main between Lark Hill Reservoir and Childrey Warren WTW would allow this.
A total of fifteen geotechnical Trial Pits were undertaken using a Kubota mini-excavator and eight Rotary Cored boreholes, up to 25m deep, using a tracked Commachio 250 drilling rig at locations along the proposed link main route.
Laboratory testing included, moisture contents, Atterberg Limits, CBR tests, Compaction tests, pH and Water Soluble Sulphate tests, Saturation Moisture Content, Chalk Crushing Value, Natural Moisture Content of Chalk, Unconfined Compressive Strength and Point Load Index of Chalk and Contamination testing.
Risk Management Limited were contracted to undertake a Phase II, intrusive, Site Investigation at a warehouse unit in Southwark, London. The scope for the investigation required a deep borehole to at least 20m depth to enable foundation and pile design.
Considering the limited headroom and access difficulties Risk Management Limited utilised a low-headroom ‘cut-down’ cable percussion rig in order to achieve the required depth. The ‘cut-down’ rig is ideal in environments where depths in excess of 10m are required, or tough ground conditions require a cable percussion rig, and headroom is limited.BACK TO POSTS