Today we had a situation where bankfull widths 2 and 3 had what appeared to be the abutment for an old bridge along one of the banks. Wondering if it is appropriate to take bankfulls along the structure. If not, where should they be taken? Thanks!
Christian - Bank armoring that occurs near the structure, and is present in the area where upstream bankful widths would be taken, should not be skipped over for that set of bankfull widths. That set, the 'Upstream' set, is attempting to characterize the environment right around the structure, which would include the presence and influence of armoring on the channel. Please not in the comments which Upstream BFWs were taken in an armored section.
However, at the channel bankfull widths, if there is some armoring, we ask that you move upstream of downstream a little to try and avoid it - if possible. If the entire bank, from near the crossing to all the way up to the channel bankfull widths (a minimum of 100' away) is armored, than you can't avoid it and just be sure to note in the comments that all BFWs (Upstream and channel, and Downstream too if necessary) were recorded in armored sections.
Hope that helps further clarify.
Makes sense, I should have mentioned this is occurred at the first set of bankfulls upstream.
Just to reiterate, bank armoring is part of the environment, and therefore bankful widths should be taken at bank armoring?
Another tricky situation.
So, in my opinion - and I will be asking my coworkers to confirm - the answer here depends on which bankfull widths you are measuring.
If you encounter this when measuring the upstream bankfull widths, I would take them where the protocol says to take them - similar to if their was extensive bank armoring near the culvert. The upstream bankfull width characterize the environment immediately outside the structure (just upstream of the structure ending), so armoring and other structures like this do make up part of the environment just upstream of the crossing.
if you encounter this in the area where you are attempting to measure channel bankfull widths, I would just move past it by a couple of feet, note it in the comments, and then continue as usuall.
Does that make sense?