When I opened your attachment the first thing I said was "OMG! Vicksburg". I worked for Dr. Pavlo from 1981 until his death in 1989. After 40+ years in this business, Pavlo was still the best place I ever worked at. As an aside, Vicksburg was the prototype for the Silver Memorial Bridge between Point Pleasant W VA & Galiapolis OH. Anyway, sentimentality aside, I was thinking along the lines of David, adding a tab plate, see attached sketch. It's based on a similar detail we use on some NYSDOT projects with 18"x18" scuppers.
If it's not too much trouble, could you tell me the names of the people on the drawing? When I worked there, some of the Vicksburg crew were still around.