geotechnical info on structural drawings

huangyhg

geotechnical info on structural drawings
for building projects i work on, geotechnical requirements (subgrade compaction, slab base materials, etc.) are usually contained in a soils report that is not officially included in the contract documents that the contractor bids on.  because the soils report recommendations are not written in mandatory language and are not part of the contract documents, the architect sometimes asks that the information be shown on the structural drawings.
i try to resist this because i am not in responsible charge of the geotechnical engineer and do not want to assume liability for areas beyond my expertise.  i suggest that the geotechnical engineer prepare drawings and/or specifications to be included in the contract documents.  however, this usually does not seem to be included in the geotech's scope and the client does not want to pay for it.
have others experienced this?  how do you handle this?
i worked for the owner of a large industrial project that had extensive geotechnical investigations performed under a dedicated contract. for the follow-on construction contracts, we presented the geotechnical "general arrangement" drawing as reference documents. these drawings showed information such as the location of soil borings, field blow counts, etc. a statement in the request for proposal told the bidders that they could review the geotechnical detail information (filling about 3 drawers in a filing cabinet) at the owner's office. had no problems or "squabbles" later.
here is what i do:
1. i include the geotechnical report as an appendix to the constructions specifications (i hope everyone do these)
2. edit the specification section for earthwork to either match the soils report or cross reference the contractor to the appendix).
3. on large projects, i draw the boring logs on the plans (usually where piles drawings is involved).
4. i also have notations on the drawings general notes sheet.
i found through the years that some contractors do not read the specifications, as they should. that is why i leave data on the drawings as well.
good luck
we basically do what lutfi does except we rarely draw boring logs on our plans.
the geotechnical report is either included as an appendix to the specs, or we state in the specs/drawings that the report is available and its recommendations should be followed.  
our first sheet (notes sheet) includes reference to the report and its author/date/project number for future reference if needed and we include our applicable bearing pressures on the same sheet.
while the geotechnical reports are not written in mandatory specification language, they are still an essential part of any building project.  our structural plans can make the geotechnical recommenations "mandatory" by referencing them and stating "compaction (or fill, or whatever) shall be in accordance with the recommendations of the geotechnical report".
the following is from standard notes that i use:
foundations have been designed for an allowable soil pressure of 4,ooo psf, except as noted on plan, in accordance with the geotechnical report prepared by xxx, dated xxx.  contractor shall refer to the information contained in this geotechnical report supplement it as required.
(stuff deleted)
footing beds shall be inspected and reviewed by a geotechnical engineer prior to pouring concrete.
i do not bind the report into the construction documents nor do i refer to only 'part' of the geotech report... i was involved with one 'kerfuffle' where the consultant only included 'pertinent' parts of two separate reports.
if you're designing in an area that uses ubc, section 1804.3 says that the "...soil classification and design-bearing capacity shall be shown on the plans..." except for stud bearing walls where specific footings are required.  
this is much easier said than done.  within a project, there will be multiple soil classifications and bearing capacities.  we don't do it except in vague general terms or when requested to by a plan checker.  we either include the geotechnical report or make it available on request.
i typically do what each of you has stated.  i reference the soils report on my drawings, show the parameters that were used in the structural design, and note that the soils report recommendations are to be followed.  however, i am usually a subconsultant to an architect and do not have control over whether the soils report is included in the contract documents.  occasionally, the architect does not want the soils report included in the contract documents  and asks that the information (slab sub-base materials, type of vapor barrier, etc.) be reproduced on the structural drawings.  this is clearly not part of my design and should not be shown on the structural sheets.  agree?
i usually have no problem with including the geotechnical information on my sheets.  if you're worried about expanding your liability, forget it, you're going to get sued no matter what.  i'd rather put the information out there to get the best chance of having it constructed correctly.  if the instructions are hidden in a report somewhere, the contractor might (will) miss them and i haven't really gained anything.  all of this assumes you correctly use the recommendations.
think of it this way;  you use geotechnical information indirectly whenever you design a footing or concrete pier.  what's the difference in directing the contractor in preparing the subgrade?
taro,
i'm not sure i agree with the thought that geotechnical recommendations that affect my structural design are not part of my services (such as subbase prep and vapor barriers).  these are integral aspects of my structural design.
i see the geotech report as a site-specific recommendation that gives me design parameters to create a structural entity.  this is really not much different than the results of some research ending up in a code that guides my design as well.
i use the geotech recommendations to size my footings or to prepare the fill under the building.  this is my engineering task as the structural engineer of record.  yes, i base it on the geotech report but its my job to ensure the foundation is properly designed and communicated to the contractor.  the geotechs do not prepare plans and specs for the contractor.  where else would this information get communicated to bidders?
vapor barrier recommendations are not real critical, and many times i ignore the geotech's advice, but its our job to take those recommendations and do something with them....not assume the contractor can get his hands on the report (non-contract binding) and respond to it intelligently.
jedclampett,
in terms of liability, the difference could potentially be huge.  say, for example, that there are localized areas of poor soil underneath a slab.  the soils report recommends not removing the bad soil and replacing with structural fill, but instead bridging over the areas with geotextile fabric to save money.  as a structural engineer, i have no idea whether this system will perform adequately.  but if i show it on the structural drawings, i am assuming the liability.  i would have a difficult time convincing a judge (who has no technical background) that i am not responsible for the information on the drawing that has my stamp and signature.
jae,
you wrote "the geotechs do not prepare plans and specs for the contractor.  where else would this information get communicated to bidders?"  that's exactly my point.  the geotech should prepare plans and specs.  most state licensing laws expressly forbid licensees from practicing outside their area of expertise.  i am not a geotechnical engineer and should not be specifying geotechnical items.  i think there is a big difference between that and using allowable soil bearing pressure to size a footing.
taro:
lets explore this a bit more.  your points are well taken and i agree that we should not "perform engineering" outside our expertise.
when a geotech submits a report for a project, you take their advice and proceed with a structural design (let's say a footing).  you have taken the geotech's advice and produced a footing design based upon soil parameters which are theoretically outside your expertise.  are you then practicing engineering outside your area?  i don't think so.  you are depending upon another engineer's professional recommendation to produce a design of something you are taking responsibility of. this does not make you liable for the accuracy of the geotech's recommendation beyond the "standard of care" that any other competent engineer would take.
similarly, if the geotech recommends a certain procedure for preparing soil beneath a building, you are not necessarily taking on his liability if you outline the procedure on your plans.  if you can show that you followed the geotech report, and even explicitly say on your plans that the geotech report should be followed, then you have done what most prudent structural engineers do all over the country (usa).  many engineers even send their 100% documents back to the geotech to respond/comment on what is specified....which is an excellent practice.
granted:  anyone can sue, but by leaving off this information and expecting the owner/client to ensure that the geotechnical report is followed to prepare that subgrade properly is, in my opinion, not the proper standard of care for a structural engineer.
i have never seen geotechnical "plans" and don't believe this is ever done for most building projects.
your thoughts?