Soil compaction. plate tampers, rammax machines, and jumping jacks

And now back to our regularly scheduled programming.*

Once the holes have been dug up it's backfilling time. Backfilling is no mean art as evidenced by the high dollar radioactive testing equipment used to test the density, moisture, and a host of other factors.

What's going on top of your backfill determines the degree of compaction required - areas with buildings over top may require 96% compaction, whereas landscaping areas may be in the 80-85% range. Across the board 3-7% moisture is usually acceptable... with particularly dry dirt water may be required, and after a heavy rain it may be necessary to wait a while.

There are many tools in the trade, today we're going to briefly review the three most commonly used for small and medium scale work - the plate tamper, the jumping jack, the rammax.


Plate tampers are awesome. For making temporary sidewalks, working around hills and obstacles. Safe and simple to use for applications requiring 3-5 inches of compaction nothing is better. Most tampers have a water tank attached that serves to moisten the ground beneath and achieve better compaction, especially useful with rock dust used in temporary walkways and such.


When your backfill is less homogeneous and you are adding dirt 8"-12" at a time in a small or sensitive area the plate tamper is no longer sufficient, and a jumping jack is a better choice. The video link goes to the Wacker tamper - and well maintained they are some of my favorite machines in the field. Bomag also makes a great machine. Ultimately keeping the oil levels, fuel mixtures, and air filters correct should keep any of these machines running for years.


The last compactor for this post is my personal favorite, the Rammax. Like xerox the Rammax is a brand of drum roller... and across the board these diesel machines are the workhorses of backfilling. Many of them now come with remote controls - this is essential for backfilling deep trenches where human safety is a concern. A modern Rammax may compact soil up to 30" deep, although in practice lifts of 8"-12" are recommended. Although remarkably simple to use these machines are extremely top heavy and prone to rolling over. For steep hills jumping jacks are often required.

Soil compaction and backfilling is one of the most important and time-consuming part of underground utility work. It is often a management headache because of the dangers associated with trenches, however with proper testing the backfill should remain steadfast for years to come.

---------------------------------------------------------

*For anyone keeping score this site is the good, the bad, and yes.... the very ugly of construction. As most of the libel and slanderous speech has dropped and now that Faulconer Construction has sent me the majority of the $$'s that they owe me (except that check for ~$300 from the first week of work that they seem to want to hold on to... all in good time, fellas) I'm excited to get back to informative postings rather than dogging Faulconer. Oh yeah, and lay off Ole Fitz. He may be a jackass, however he's a lovable jackass and one of the best Superintendents Faulconer has.