Letchworth to Royston Trunk Main

February 2023

RML were commissioned to carry out a Site investigation for a information on the sub-soil conditions at points along a proposed water main route, together with laboratory testing, in order to provide information to assist foundation design, potential contamination and the choice of pipe materials.

Field Work

Fieldwork was undertaken in line with British Standards BS 5930:2015+A1:2020. 14 No. Light Percussion Boreholes, 4 No. Drive-in-sampler Boreholes and 1 No. Sonic Coring Borehole was undertaken across the route.

Ground Conditions

According to information published by British Geological Survey (BGS) the underlying geology at the site site is the Holywell Nodular Chalk Formation and the New Pit Chalk Formation (Middle Chalk). Superficial deposits were sporadic across the route and if found to be present would comprise of either Head Deposits or Glacial Till.

Laboratory Testing

Natural Moisture Contents, Atterberg Limits, Particle Size Distribution, Quick Undrained Triaxial Compression Tests, Chemical Analysis, Asbestos Identification and pH and Sulphate Tests were the Laboratory tests undertaken for the project.

Sundon Reservoir, Bedfordshire

June 2021

Risk Management Limited were employed on behalf of Affinity Water to undertake a Phase II Site Investigation at an existing reservoir to inform the design and construction of a new water condition plant.

Intrusive fieldwork consisted of 6 No. drive-in-sampler boreholes up to 9m depth, 2 No. hand auger boreholes up to 2m depth, TRL Dynamic Cone Penetrometer (DCP) tests up to 1.20m depth, 2 No. Soil Resistivity tests using a Wenner 4-point array, 3 No. falling head permeability tests and dynamic headspace analysis for Volatile Organic Compounds (VOC’s) using a Photo-inonisation Detector (PID).

Laboratory testing was undertaken in line with the Consulting Engineers, Mott MacDonalds, specification and included Natural Moisture Content tests, Atterberg Limit tests, Particle Size Distribution tests, Resistivity, MCV, MCV-Moisture Content Relationship, Lab CBR tests, Organic Matter, Carbonate Content, pH and Sulphate tests and Soil and Groundwater Contamination tests.

Groundwater and gas monitoring was undertaken over 4 visits and included purging, micro-purging and sampling of groundwater using either dedicated bailers or a Peristaltic Pump and low flow cell.