Borehole Drilling. Logged As It Comes Up.

Residential boreholes are sized to the base of excavation plus one to two metres. If the depths are already specified, send them with the address. If not, the Principal Engineer reads the plans and the block before quoting and sets them against the structure and the ground beneath it. Where the ground turns to rock, the hole continues as NMLC rock coring.

Each log describes every layer by material, moisture and consistency, with the Dynamic Cone Penetrometer results beside the hole, groundwater observations during and after drilling, and the depth of every sample. The log is written in the field, not from photographs the next day. Consultancy and commercial programmes add Standard Penetration Testing results. A plan shows where each hole went.

Yes. Seepage is noted as it appears during drilling, and the standing water level is recorded after the hole is finished. No single observation changes a basement or footing design more often. Both are readings taken on the day of drilling; where the design needs the water table monitored over time, SFGEO scopes a groundwater monitoring well and a drilling contractor installs it.

Yes, when the site warrants it rather than by default. The engineer reads the material in the hand as it comes up and decides on site which depths to sample and what the design needs tested. Disturbed and undisturbed samples go to NATA-accredited laboratories. A geotechnical investigation report with laboratory testing is typically 8 to 12 business days from fieldwork, confirmed in the written quote, with interim findings available where the programme needs them.

Most Sydney boreholes start in fill or topsoil over residual clay and finish in weathered shale or sandstone: shale-derived clays across the inner west and the Cumberland Plain, Hawkesbury Sandstone through the north and east, and sand over the Botany basin. Solid flight augers advance through cohesive soils and weathered rock, and each layer is logged as it comes off the flights. Hollow stem augers are chosen where the hole would collapse, in loose sand or below the water table, because the stem holds the hole open for sampling and testing. Where the auger refuses on rock and the design needs more, the hole continues as NMLC rock coring.