Backfill
Backfill
(OP)
I have specified sand backfill around water lines and conduit. The contractor is insistent on using CA-7. Has anyone experienced a problem with CA-7 used in this manner?
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RE: Backfill
RE: Backfill
If I remember correctly, CA-7 is 1-1/2-inch minus coarse aggregate (hence "CA") with no sizes smaller than 1mm. I would imagine that this could potentially leave voids or be difficult to compact well around the water lines/conduit. I would say the samallest diameter pipe I would use CA-7 with would probably be 4 inches. I would recommend that you stick to your guns (figuratively) and tell the contractor that they need to use sand.
I would think there shouldn't be a problem with a spec of 6 to 12 inches of sand above and below the conduit with CA-7 above and below the sand zone. This helps also if excavating in future for repair as the sand indicates that the utility is close and hand excavation becomes appropriate to avoid unnecessary damage.
Good luck,
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
www.ttlassoc.com
The views or opinions expressed by me are my own and do not necessarily reflect the views or opinions of my employer.
RE: Backfill
RE: Backfill
RE: Backfill
BTW, my field experience is that it is very difficult to get a contractor to fully compact the soil around pipe to meet the drawing specs unless you continually watch him.
RE: Backfill