When using a sheep foot roller, build the lifts thin enough so that pressure penetrates all the way down to the lift below. Do not allow the soil surface dry before adding the next lift or you will end up with poorly bonded layers in your dam. Some kind of shallow scarification and then wetting is desirable before adding the next lift. This will create a surface that will bond to the next lift. Moisture content is important because it is the polar properties of water molecules that create bonding between charged surfaces of soil micelles (small clay particles). To much water is like too much glue. Too much water lessens the resistance to shear and leaves excessive voids between soil micelles. In these spaces you may have lack of adhesion, wetting and drying, freezing and thawing, places for plant roots to grow into etc., and there goes any compaction you had over time. Dozers though heavy do not compact well because of the large surface area they apply to level ground. The grouser bars on dozer track pads are designed for traction and do a negligible job of applying pressure to any depth. Dozers will do a fair job of packing the surface of a steep slope for reasons I will not get into. Wheel rolling with a loaded truck or wheel loader is far better for good compaction than a dozer is, but tires will also create a smooth �seal� on the surface of your lift which you do not want before adding the next lift. Same goes for a sheep foot roller if you over do it. Keep large rocks out of the material to be compacted or there will be an area around them which will be �protected� from the compaction of a roller or what ever you are using which will result in a weak spot. A vibratory roller is nice if you can afford it. Jumping jacks and plate compactors are only good for very small jobs and confined areas. Having an engineer test with a neutron probe once the optimum moisture content is determined in a lab would also help to see how you are doing, but these services are not free and it needs to be done upon the completion of each lift.
