Is Jetting illegal??

[jupchurch]

Recently, a union rep informed that Jetting to achieve compaction on a washed sand or jetting to pothole is illegal in the state of California. Does anyone know if this is true???

 

[cvg]

just depends on your client. The state of california can't mandate this, however maybe Caltrans doesn't allow it. this would be a good question for the resident engineer. Some agencies allow it for pipe bedding on sewer and waterlines. I haven't seen this method used for potholing and woudn't recommend it.

 

[BigH]

Are you talking jetting as in vibro-compaction or vibro-replacement or puddling as in pouring water on top of the fill to "compact" it?

 

[dicksewerrat]

Or jetting with Vac truck for vac excavating for potholing. Maybe Union rep doesn't represent jet-vac operators

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[cvg]

the term "jetting" as used in California is a hose with a jet pipe on the end which is used to apply water, under pressure. It is used to help consolidate sand in the trench. Bedding and pipe zone backfill around water and sewerlines in California is generally required to be imported clean sand (sand equivalent of 20 per Caltrans test method 217). If native material is clay or rock such that water densification is not practical, then another type of suitable material and compaction method is required for pipe zone material. Alternatively, the contractor is required to bring in a sump and pump to remove the accumulated water from the downstream end of the trench.

Based upon my experience, jetting to consolidate pipe zone material was commonly used in Southern California until at least the mid 90's. I left California and haven't been involved with any construction there since that time, but imagine that jetting is likely still allowed by many agencies in that region.

 

[VAD]

Depending on the material around and below the washed sand and if drainage is not positive, this approach is often not preferred. Of course it probably depend as well on controls to the amount of water used re methodology.

 

[cvg]

Vad

In my experience in southern california in the San Bernardino County area, this was the preferred method and used on most projects.

 

[rconner]

I had not heard that water jetting is "illegal" in the state of California. I believe a quick web search will reveal (by now online specifications etc.) that if this were true several arguably notable communities and entities in California have not yet gotten the message!! I know it is true however that for whatever reasons (perhaps local conditions and/or expertise or other etc.?) several other notable entities or individual job specifications also in California specifically forbid this practice, in favor I guess of mechanical compaction methods.
I did however happen to notice also some time ago that the clay pipe folks e.g. at

http://www.ncpi.org/Handbook/handbook04.htm

now do say under the heading “Geofabric”: “Crushed rock or other coarse aggregate is recommended and used as a bedding material to improve the load bearing capacity of pipe”, and they appear to now in this area specifically dissuade the use of “fine to medium sands” for clay pipe bedding (at least in some circumstances). I don’t know exactly why that caveat was at some point added involving required support for clay pipe systems, but I also noticed in a news article not long ago it appears something like the phenomena discussed may have been used to explain some problems that eventually happened to a clay pipe installation after some significant precipitation/flooding in the Philadelphia area. While I don’t presume to be an expert in that construction field, I’m not sure exactly where that leaves them with regard to ”jetting” ( that I would assume by its nature and this thread requires some sort of sand, and also from reading some of the good replies on this thread sort of “drainability” in the basic trench).