RFIs-and-Responses.docx

RFIs and Responses

1. Tunneling beneath the building slab Would tunneling be accepted as an alternative method for replacing the sanitary sewer piping beneath the existing building slab instead of open-cut demolition and replacement of the interior concrete slab?

We have successfully performed sewer replacements using this method at government facilities and school districts under the oversight of engineers and architects. Parkhill is the Architect of Record for our most recent sewer replacement project utilizing this approach.

Our proposed method would generally include:

1. Excavating access pits at approved locations.

1. Tunneling beneath the existing slab along the sewer-line route.

1. Removing and replacing the existing sanitary piping from below.

1. Supporting the new piping with clevis hangers attached to concrete anchors drilled into the underside of the slab.

1. Installing supports at a maximum spacing of four feet on center, or closer where required by code or the approved piping manufacturer.

1. Maintaining the required pipe slope throughout the system.

1. Backfilling the tunnel and access areas with flowable fill.

1. Testing and inspecting the completed piping before backfilling.

1. Restoring all affected access-pit and surface areas.

This method could substantially reduce interior slab demolition, dust, noise, finish restoration, facility disruption, and overall construction duration.

Tunnelling, as described above, is an acceptable alternative.

2. Original as-built drawings Are original as-built drawings, record drawings, plumbing plans, or utility surveys available for this building?

Gov’t providing response

3. Existing sewer-line depths Are the approximate depths or invert elevations of the existing sanitary sewer lines known?

See attached updated sheet PD-100 for approximate depths.

4. PVC pipe alternative In lieu of the cast-iron sanitary piping, would either of the following be accepted for the replacement sanitary sewer piping?

1. Schedule 40 PVC DWV pipe and fittings.

1. Schedule 80 PVC pipe and fittings.

If PVC is not acceptable throughout the project, would it be accepted specifically in restroom and ordinary sanitary-waste areas while retaining epoxy-coated cast iron in process-waste or high-temperature discharge areas?

PVC is only acceptable at the restrooms and extending to sewer mains. All sewer piping connected to lab areas or receiving drainage from floor sinks mop sink and non-restroom drainage is to be coated cast iron. See attached updated Section 221316 SANITARY WASTE AND VENT PIPING.