Sanitary service connection to carrier pipe inside a steel casing pipe

[minnjoe]

We're in the design phase of a sanitary sewer upsizing/replacement project. The new sanitary sewer will be 36" and 30" diameter PVC. Steel casings (bored and jacked) are planned along several runs to help minimize disruptions/impacts to local businesses.

Two existing sanitary services need to be reconnected to the proposed upsized sewer. These services are located along the proposed steel casings pipes.

Question: Is there a clean way to re-connect an existing sanitary service lateral to a 36"/30" PVC carrier ppe inside a 54"/48" steel casing? Casing spacers will be used, so the voids between the casings and carrier pipes will not be filled with pea gravel or grout. More specifically, is there a way the service re-connections can be made that will ensure watertight connections at the sanitary service riser / steel casing wall interface? For service connections to large diameter mains, we generlally specify an Inserta Tee fitting.

I'd be very grateful for insights anyone could offer.

Thanks.

 

[coloeng]

To reconnect these two services, the contractor will need to excavate down to the sewer line, cut the casing pipe out of the way, attach an Inserta Tee fitting and reconnect the service. There is no practical way to connect to the sewerline inside the casing without removing that section of casing.

Is there a reason that boring and jacking casing pipe is being used instead of pipe bursting?

 

[minnjoe]

The existing sewer is 15" VCP. The replacement sewer is 36" and 30" pipe, and will be installed several feet deeper than the existing sewer.

After thinking things over a little more...maybe the casing could be cored - large enough to install an inserta tee and then a flexible saddle tee installed on the on the casing....