Summary of Drilling Methods to Collect Soil Samples for Infiltration Basins
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Drilling Method Description Sample Collection Possible Depth Advantages Limitations References Example Photo
Soil Probe Soil probes are a basic form of soil sampling, used to collect shallow or surface samples by pushing a T-shaped probe into the ground. The probe cuts a core sample smaller than the diameter of the probe body. The sample can also be collected within a liner inside the probe. Small diameter soil surface profile ≤ 3 feet Inexpensive Quick Easy to use May not be able to collect enough information to determine if infiltration is possible due to depth and limited soil information collected. Unable to perform blow counts. http://www.amssamplers.com/hand-tooling/soilsamplers/soil-probes.html X
Hand held or machine auger The auger is held vertically and is driven into the ground and rotated by the handle while applying leverage. At every 30 cm of depth penetrated, the auger is taken out and the samples of the soils are collected separately for examination. This method works best in loose materials ranging from clay to sand to gravel. Bag/jar samples of material ≤ 50 feet Inexpensive, Easy to use. Large selection of auger types Only suitable for unconsolidated deposits (loose materials) Slow compared to other methods Equipment can be heavy. Unable to perform blow counts. http://www.theconstructioncivil.org/boring-types-of-boring/ http://www.lboro.ac.uk/well/resources/technical-briefs/43-simpledrilling-methods.pdf X
Excavation Test Pit or Trench A pit or trench is dug manually or with an excavator to depth desired in order to visually observe subsurface soil conditions. Grab samples or bulk samples of material ≤ 20 feet Quick, Easy to do, Shallow exploratory drilling method Must be onsite during excavation to coordinate locations and depth as well as observe subsurface soils and behavior, taking photos and soil samples Shallow form of subsurface drilling Must be cautious of collapsable soils when digging Requires back fill and compaction. Unable to perform blow counts. http://geoinfo.nmt.edu/staff/mclemore/projects/environment/documents/SOP_09v12_TestPits_final.pdf http://www.fhwa.dot.gov/engineering/geotech/pubs/05037/04c.cfm X
Direct Push Technology (DPT) Geoprobe or Strataprobe is pnuematic hammer driven with continuous sampling into plastic tubes. Blow counts are not provided through this method. Single tube and dual tube systems are available. Bag/jar samples of material usually up to 60 feet but can go to over 100 feet Minimal to no cuttings Quick and efficient Small, relatively mobile rig Continuous sampling Unable to perform blow counts http://geoprobe.com/soilsampling-equipment-continuousdiscrete X
Rotosonic Rotosonic drilling is a method where continuous samples are taken. It is good for pentrating through most formations, but due to the ground disturbance, is not suitable for collecting undisturbed samples. Samples are brought out of the subsuface in clear plastic sleeves. Bag samples of material >100 feet Continuous sampling Quick and efficient Produces little to no waste Mobilization cost can be expensive. Unable to perform blow counts. http://www.astm.org/cgibin/resolver.cgi?D6914 http://www.sonicdrilling.com/Flash/Website%20Brochures/Environmental%20Applications%20%20Brochure.pdf X
Standard Penetration Test (SPT) using Hollow Stem Auger (HSA) drilling method Augers act as casing for borehole (prevent caving) Center of augers is hollow for sampling Bag/jar sample Split-spoon (or other disturbed samples) Thin-wall samples (or other undisturbed samples) >100 feet Augers do not need to be removed to sample Can be used above and below water table. Can collect blow counts. Heaving sands may clog the hollow stem auger. Can be slow when drilling in soils with cobbles and boulders. http://www.astm.org/cgibin/resolver.cgi?D6151D6151M-15 http://www.astm.org/cgibin/resolver.cgi?D1452-09 X