Utility Trench Settlement- acceptable tolerances
Utility Trench Settlement- acceptable tolerances
(OP)
Could someone help me out on a problem we have with some utility trenching settlement under a roadway.
We have a sanitary sewer project that has experienced settlement from 1/8" to 4"+/- over a 6 month period. The Contractor will return to sawcut, re-compact and repair.
The Contract required 95% compaction by Standard Proctor for backfill compaction.
My question is: Is there an acceptable tolerance off of the straight line (1/4"/ft side slope), measured by a 10' straight edge that is a cut off for what needs to be replaced and/or repaired. Paving standards usually state a 1/4" variation off of straight line side slope is OK, but I can't seem to find a Standard Acceptable tolerance for settlement. One firm I worked at required all settlement to be brought back to 0". Varying from 0, 1/4" and 1/2" would mean the difference is hundreds of feet of repair. We want to be fair and not ask the contractor repair hundreds of feet of road uneccessarily, but also want to make sure anything that needs to be repaired, gets repaired.
Thanks for any help or input.
We have a sanitary sewer project that has experienced settlement from 1/8" to 4"+/- over a 6 month period. The Contractor will return to sawcut, re-compact and repair.
The Contract required 95% compaction by Standard Proctor for backfill compaction.
My question is: Is there an acceptable tolerance off of the straight line (1/4"/ft side slope), measured by a 10' straight edge that is a cut off for what needs to be replaced and/or repaired. Paving standards usually state a 1/4" variation off of straight line side slope is OK, but I can't seem to find a Standard Acceptable tolerance for settlement. One firm I worked at required all settlement to be brought back to 0". Varying from 0, 1/4" and 1/2" would mean the difference is hundreds of feet of repair. We want to be fair and not ask the contractor repair hundreds of feet of road uneccessarily, but also want to make sure anything that needs to be repaired, gets repaired.
Thanks for any help or input.





RE: Utility Trench Settlement- acceptable tolerances
By the way, the kind of settlement that you are seeing likely indicates that the backfill was not compacted to anything like 95% standard.
RE: Utility Trench Settlement- acceptable tolerances
RE: Utility Trench Settlement- acceptable tolerances
If you are not going to follow a definitive 0", 1/4", 1/2" or whatever, observe the project after a rain. Any birdbaths or other areas traping water should be repaired regardless of the depth of settlement.
RE: Utility Trench Settlement- acceptable tolerances
RE: Utility Trench Settlement- acceptable tolerances
RE: Utility Trench Settlement- acceptable tolerances
What were the actual specifications?
Did the contractor meet those specifications?
Was there a performance standard?
If the contractor met the specifications and met any performance standards, how is he responsible for what appears to be an improperly specified job? I have personally witnessed and retested a project with 10' to 14' deep backfills, which was exhumed and found to meet 95% of Standard and the client wished the settlements were only 4".
To be rendering opinions without knowing the soil types and depths of fills may not be prudent. We really need a little more information before a proper opinion can be rendered.
I practice in an area with some extreme conditions. In my area, for some soil types and conditions, the use of the Standard Proctor is a setup for settlement.
RE: Utility Trench Settlement- acceptable tolerances
RE: Utility Trench Settlement- acceptable tolerances
However, I agree with emmgjld points, and also feel that cvg only refers to a portion of the original question in his second post. The question boils down to one item - How much do we make the contractor repair? Although not in question form, it was stated: "We want to be fair and not ask the contractor repair hundreds of feet of road uneccessarily, but also want to make sure anything that needs to be repaired, gets repaired." This is what emmgjld referred to, and is truly dependent on the spec. If the contractor met your specs, and your QA passed his work, and the settlements are within tolerance allowed in the contract, then technically the contractor met his obligation, and the owner should repair at their dime.
So, what does your contract say? Does it need some upgrades before the next project goes out the door? I have often seen this type of thing where the lack of specifics in an often-used specification is not noticed until there are contractual issues. To be fair, make the contractor repair the items not meeting spec, and pay them for the items that you want fixed that did meet spec. Then, be prepared to take it form an upset client.
RE: Utility Trench Settlement- acceptable tolerances
RE: Utility Trench Settlement- acceptable tolerances
RE: Utility Trench Settlement- acceptable tolerances
RE: Utility Trench Settlement- acceptable tolerances
Richard A. Cornelius, P.E.
WWW.amlinereast.com