Chama Coaling Tower - Question

I’m working on a model (O scale) of the Chama coaling tower and have a question about the coal pit where the buckets are lowered. In particular, the area between the two inside vertical support that guide the buckets:
The ‘General Plan’ for the DRGW coaling towers show 4 – 1’ square concrete struts that run from front to the back of the coal pit. Two of these would be just to the inside, and attached to each aforementioned vertical supports. I do have some plans specifically for the Chama tower, but no details in this area, so I planned on modeling it according to the general plan until I recently ran into a photo that possibly shows otherwise. In the photo it appeared that there was a vertical walls, instead of the struts, just to the inside of each of the inside vertical supports and the area between these walls was filled with dirt, thus creating two separate pits into which the buckets are lowered. Unfortunately, the area I’m interested in was not the subject of the photo, so it’s hard to make out the details. Is it one large pit or two smaller ones?
If I have confused you, I’m sorry, this area is not easy to describe, let alone understand unless you are familiar with the tower. I could post (or email) some drawings if someone needs clarification.
Thanks for any insight,
Dennis