Gary,
I would see this exactly the opposite way and recommend the pump to be near the outlet of the sediment chamber. Mind you that this is just an experienced opinion but it is based a different understanding of how the pump will work.
Many pumps do not suck water uphill very well but almost all pumps will push or lift water. A pump is made up of a motor and then a "Wet-end". Most pond pumps are impeller designs enclosed in a housing. Pumps that are very efficient and use less energy will generally have impeller designs that move lots of water when wet but potentially function poorly when trying to suck air out of the line to get at the water they really want to chew.
Even the so called "self priming" pumps will work better in the inlet water is freely supplied by gravity with the pipe run and any potential rise in elevation being located "downstream" from the pump.
By locating the pump at or near the settlement chamber outlets, then you have the flexibility to raise the level of the filter barrels at the other end of the pond and this may work much better with you grade and rocky soil constraints.
Again due to your sloping location, you can probably daylight the drain from the sediment chamber AND daylight the drain from the pump pit to make sure you pump always stay dry and happy. External pumps can become very unhappy when submerged.