AtlasRob: "What were you putting in the trench?"
That particular ditch was for sanitary sewer, HDPE pipe.
When I started on that project 345C and 365C’s were being utilized to excavate all the pipe trenches. The machines had to be equipped with pin grabber couplers so they could go back and forth from rippers to 30” buckets. The result was a lot of broken ripper shanks; buckets peeled in half and cracked sticks on machines with less than 2000 hours on them.
They were running 3-4 mainline excavators digging trench to each single pipe crew. Once each operator had enough trench excavated to lay a pipe, he’d call the pipe crew on the radio, they’d come over and set it, then go to the next excavator that was ready. Production was terrible and the material coming out of the trenches ended up being handled several times from excavating to crushing to backfilling.
The municipality allowed us to substitute most of the SDR-35 pipe with HDPE. And in some cases the DIP as well. For sewer pipe the trencher would cut the ditch and at the end of shift I’d pull off one of the D8’s or D9’s to spend the last hour of the day pushing all the spoils back into the ditch until he was caught up with the trencher.
Then, instead of a 345 or 365 having to excavate the pipe trench we’d use a 320C with a 30” deeply heeled bucket to spoil the material back out of the ditch and grade it utilizing a GPS on the machine. Because of the hardness of the rock the spoils coming off the trencher were fine enough that we were allowed to use them as bedding and backfill for any HDPE pipe. So just drag the fused pipe up to the ditch and drop it into the pregraded ditch.
At manholes we’d bring in a 365C or 375L with ripper and excavate the grade for the manhole, vault box, etc. Since the trencher had cut right through the middle of where the manhole would sit it gave the rock somewhere to go and was pretty easy to dig out. Manholes were then placed on grade and the HDPE pipe was attached.
"Cant see it being steel gas as there is no room for sidebooms and that previous corner looks a bit on the sharp side"
That first picture actually has me standing where the spoils were pushed back into the ditch. There is a radius back behind me that originally called for 5 manholes to get through it with the SDR-35 pipe. Due to switching to HDPE we eliminated the need for the manholes (saving money) and the trencher just cut right through and we laid the pipe.
"Will the arisings go straight back in, pre graded or bedding first ?"
Where we were allowed to use HDPE pipe the material coming off the trencher in most places on that project was so fine that it passed the municipalities inspection as bedding. On the SDR-35, DIP and ADS pipes we had to use a ¾” crushed AB for bedding/shading and then used the trencher’s spoils for the remaining backfill.
With pipe that required laborers to get into the ditch, like DIP or storm drain lines we’d cut a trench as shown in the pictures, then push the material back in. Then have the trencher cut a ditch right next to the previous ditch, making for a total 64” wide trench. A 320-330 would then be used to excavate the trench with trench boxes/shoring, place the pipe, etc. It was a tight fit inside the trench box for the pipe layer with that narrow of a ditch but it drastically increased production compared to excavating the native rock and eliminated the double and triple handling of the material.
I ask as there doesnt appear to be much room for access, so I am thinking plastic water !