digitalgeotechnics
commented
2 years ago I would say intention is definitely not to define the method. As said in the OP that would duplicate the HDPH. Seems to me an unusual thing to have been left off - is "borehole" a naughty word in the UK?
From the group notes:
• The LOCA_TYPE code is used to categorise the type of activity that has occurred at the location. • The details of exploratory hole construction are contained in the HDPH group. If LOCA_TYPE codes are used that represent the type of exploratory hole construction then they must be correlated with the code or combinations of codes in HDPH_TYPE. Alternatively the code 'EH' could be used to represent an Exploratory Hole the details of which are contained in HDPH.
It seems the intention of underlying AGS UK standard is:
- Both
LOCA_TYPEandHDPH_TYPEshould be populated and they should correlate - if there happens to be more than one
HDPH_TYPE(eg "AUGS" then "RC" (auger then rotary cored) thenLOCA_TYPE=EHand "AUGS" and "RC" would be used over their respective intervals inHDPH.
My thoughts on the function of this field:
a. While the AGS LOCA group notes relate the data with the drilling method and states that they should correlate (which indeed they should), the most practical function of LOCA_TYPE is defining the "class" of information available at this location. While the class of information is inherently related to (dependent on?) the hole construction method, there can be multiple (sometimes competing) methods used in hole construction for reasons completely independent on the information objectives of the test location.
b. Having a high level of detail recorded about how the hole was constructed is useful for may reasons, hence the structure of HDPH. Knowing the "location information class" is also useful for many data interactions as well. eg1 when assessing an overall investigation project, we plot the test locations using symbols which in most cases reference this field. In this activity we want to know the class of information which is available in that area, but don't care about the minute details of hole construction. LOCA_TYPE can also be used by software to select the correct lof report template. LOCA_TYPE can also be used to raise alerts when unexpected values appear in a data set (eg it would be unusual to have bulk samples at a location with LOCA_TYPE)
My conclusion:
i. If we adopt the approach that LOCA_TYPE conveys the class of information 'EH' is too generic as it could be used for multiple information classes.
ii. I think forcing use of 'EH' with the requirement to perform some form of analysis on the data in HDPH in order to ascertain the information class would be problematic and make things like plotting test location plans more complicated
iii. With this in mind I don't think adding 'BH' is too unreasonable an idea. Although in some ways it is generic - 'BH' is still generic eg it could be used for a hand auger hole as well as a deep cored hole.
iv. if 'BH' is to generic I think its worth having a code representing a hole which is augered then rotary cored. 'ARC'?
FWIW LOCA_LOCA is often overloaded with this information as well "BHxxxx" which is wildly problematic when the hole type is changed in the field (eg a planned borehole at a location is changed to trial pit). I can't see a way around this as it's a succinct way of communicating the "location information class" in everyday communication. But it can cause information conflicts.
People are a bit confused by the change of use of HOLE_TYPE in AGS 3,1 RTA 1.1 vs LOCA_TYPE in AGS 4.1.1 such as 'BH' is no longer in the LOCA_TYPE list.
Cara at SMEC wrote Is it the intention in the point table to define the drilling or excavation method rather than just the original it’s a borehole or it’s a test pit? There seems duplication between that and HDPH Method. Based on comments on the AGS discussion forum you say to use the list. Does this mean EH (exploratory hole) replaces the term Borehole (BH).