St. Johns Road, Harrow, London

December 2023

RML carried out both a Phase I Desk Study and Phase II Site Investigation for the demolition of an existing building on the site and construction of hotel accommodation (Use Class C1) and construction of basement level; ancillary restaurant and conference rooms (Use class E); together with associated bin store; landscaping and parking.

Walkover Survey

A walkover survey was carried out by an RML Engineer to establish if contamination is present from any undocumented practice or industrial use of the land and surrounding land and if necessary to confirm the accuracy of the information obtained from elsewhere as part of the Preliminary Risk Assessment (PRA) data gathering process . A visual assessment of the land to check for signs of industrial activity, landfilling, fly tipping , fuel storage, fuel tanks, asbestos related materials or any land contamination was undertaken and a photographic record made to provide evidence to show the condition of the land at the time of the Walkover Survey.

Phase 1 Environmental Risk Assessment

Environmental data, comprising geo-environmental hazards, hydrology and hydrogeology, was obtained for the current site covering an area of up to 1000m from the site boundary.

Historical Maps

Historical Ordnance Survey maps were also obtained for the site, as part of the PRA data gathering process. These maps were used to inform of potential historical contaminative processes.


Fieldwork was undertaken in line with British Standards BS 5930:2015+A1:2020. 1 No. Cable Percussion borehole, 5 No. Drive-in-sampler Boreholes, 3 No. Hand Excavated Trial Pits and MEXE Probe CBR Tests were undertaken at the site. Monitoring installations were subsequently fitted within the boreholes to facilitate land-borne gas monitoring.

Laboratory Testing

Natural Moisture Contents, Undrained Triaxial Compression Tests, pH & sulphate tests, chemical analysis, Waste Acceptance Criteria (WAC) and Asbestos Identifications were undertaken for the project.