levee certification
levee certification
(OP)
is there any concensus on the spacing requirements for borings along a levee to be constructed or reconstructed in order to be certified by FEMA?
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RE: levee certification
I would imagine that FEMA could answer that question for you. I don't suppose that FEMA relies on the USACE criteria?
Jeff
RE: levee certification
RE: levee certification
RE: levee certification
ht
However, the only criteria for spacing I have found is in EM1110-2-1913, Design and Construction of levees which indicates a spacing between 200 and 1,000 feet. It seems to leave it up to the designer. In my case, debate with the geotech was between 1,000 or 500 feet which results in twice the borings and essentially twice the cost for field work. The reasoning was that "FEMA required it".
RE: levee certification
Levees are definately a case where one size does not fit all. Boring sites should be picked both at random, i.e. at some spacing and based on site condition. Aeiral photos are very helpful for looking for unusual site conditions that need to be explored. Also, borings should be placed not only on the center line but also riverward and landward of the center line.
I would question any geotech who just quotes a standard spacing. Also, geophysical mehtods can be used in some cases along with CPT borings.
RE: levee certification
Assume that if your client ever needs to certify their levee, that any extra soil borings required by the agency in question can be taken at that time. You and your geotech should agree to perform however many soil borings are needed to properly design/analyze your improvement project. Note that certain areas may warrant borings in a tighter spacing than others (corners, critical section, abutments, areas of soil transitions, etc.).
I also suggest you and your geotech should also review the post-Katrina recommedations for levee design, which are not current in the EM1110-2-1913 publication.
Thanks for the great question.
Jeff
RE: levee certification
that is exactly what we discussed - doing the borings at approx 1,000 feet now and doing the analysis and design to meet FEMA criteria. Then if we (the owner) decides to certify the levee later, and if FEMA asks for more supporting soil data, get additional borings at that time. However, my geotech has settled on approx 500 feet spacing now.
RE: levee certification
http://www.asce.org/files/pdf/ERPreport.pdf