Building 453 developed a need to increase the flexibility of liquid cooling for advanced development computers planned in the future. This new computing is anticipated to have a greater heat load than what is currently available in the building. Cerrudo Services provided new underground low conductivity water (LCW) supply and return piping from LLNL’s existing underground supply and return piping into Building 453, requiring approximately 600 LF of trenching.
Work occurred adjacent to Haussmann Lake. During mobilization Cerrudo erected approximately 600 LF of special exclusion fencing around the work area to keep endangered red legged frogs from migrating into the work site and the trench. Pipe materials were received and the proposed pipeline trench surveyed. Asphalt paving was removed then potholing was conducted to locate existing utility lines.
After identification and marking of existing utilities, excavation of the five foot deep trench proceeded from the (east) building end towards the (west) existing LCW pipe connection location. Sand bedding was placed, then 12” diameter Aquatherm polypropylene supply and return pipes were placed over the bedding. Each 40 foot pipe section was connected by heat fusion. Tracer wire was installed on top of the pipes. The trench was backfilled and compacted, then a five inch thick concrete slurry cover was poured over the backfill.
At the building, the two pipes penetrated the exterior metal-panel wall, through an eight foot plenum space, then into the interior of the building through an existing damper location that was demolished and infilled. Since no construction dust created from the installation of the pipes was permitted to escape to the plenum, containment was constructed to seal off the plenum area from the work area. Pilot holes were drilled in the exterior wall to confirm stud spacing and absence of wall utilities, then holes were cut into the façade and pipes installed through the building envelope.
At the existing 18” LCW pipe location, approximately five feet below grade, the site was excavated and a 8’ x 4’ x 4’ pre-cast concrete vault installed over a level gravel bed. The pipes coming from the building were run into the east side of the vault. After shutting off and draining the water from the existing 18” supply and return piping, those pipes were cut, custom tee’s installed and new 12” pipe fused to the tees and brought into the vault to connect to the pipe coming from the building side. After all connections were made, the vault was backfilled.
After pressure testing the pipe, new asphalt paving was installed over the concrete slurry and the site restored.