Since Tony and Jeannine threw the call for info. out to folks in Lexington, I wi
ll stop lurking on this one.  The privies I dug in Kinkeadtown (now finally avai
lable if anyone is interested) in Lexington, were fairly shallow (1-1.5 m deep)
and, if not lined with brick (I had only one instance of brick lining), were in
sufficiently stiff clay that cave-ins really were not a problem.  In fact, loose
 fill was only a problem when we dug a looted privy that had been refilled.  Tho
se were a mess and of such little informational value that in the future, I migh
t bisect them with a backhoe and take what samples I can to date them and look a
t shape but that would be about it.  Jay Stottman has recently published an arti
cle in one of the Kentucky Heritage Council volumes on privy architecture in Lou
isville (1995; Historical Archaeology in Kentucky edited by Kim and Steve McBrid
e and Dave Pollack).  Steve or Kim would be good people to contact on privies as
 they have dug quite a few in L!
exington.  But to get back to special precautions, I found that at Kinkeadtown,
the privy fill was fairly homogeneous and did not contain the discrete layers of
 fecal material that Bob had encountered in Covington.  It appeared that groundw
ater moved through the deposits rapidly and in sufficient volume to break down
fecal material and incorporate its components into the soil that was being throw
n into the privy to keep it "sweet".  It probably also flushed (no pun intended)
 out a lot of microscopic sized stuff at the same time.  Thus it did not seem to
 be much of a health hazard.  But who knows what foreign organisms may be lurkin
g in my system?  Nevertheless, no one complained of any health problems that mig
ht have been associated  with privy excavation on this particular project.  And
we had no problem with unstable walls in undisturbed privies.