Fidelity Investments Fiberglass Pipe Replacement
CommTank upgraded the underground fuel oil lines at Fidelity Investments in Merrimack, NH. The 6” fiberglass double-wall containment pipes that ran between the data center and the underground storage tanks (USTs) were excavated and replaced with 3” double-wall fiberglass coaxial piping.
Fidelity hired CommTank to tightness test the underground tank piping because they wanted to check the pipes integrity. Four double-wall fuel piping runs connected the underground storage tanks (USTs) to the Data Facility Building and provided fuel to four large generator sets. The secondary containment for the four fuel lines was pressure tested at 10 PSI and none were able to maintain a pressure as read on the gauges (0 PSIG). CommTank crews excavated around the lines and exposed the pipe. Analysis of the pipe fittings showed an incompatible adhesive was used in the prior installation to bond the pipe joints. The adhesive had become brittle and was no longer providing a tight seal. The pipes were also compromised by a storm drain pipe installed above the pipes. Improper backfill and compaction used to install the storm drain allowed it to settle over time and apply pressure to the secondary containment of the double-wall pipe.
To avoid future problems with the storm drain, the new piping was installed 12’ deeper than the original pipe. The replacement fiberglass pipe was installed according to ‘Ameron Installation Practices for Dualoy 3000/LCX Coaxial Fiberglass Piping System with Bonded Clamshell Fittings, Bulletin 9903, FP824’.
The following summarizes the steps taken to replace the fiberglass fuel piping.
Underground Storage Tank Piping Removal:
- Obtained necessary permits (NHDES approval, piping closure permit, trench permit, etc.)
- Provided Dig Safe utility clearance of property (identify underground utilities)
- Prepared a confined space entry permit and a site-specific health and safety plan
- Provided temporary fencing around excavation site
- Provided a trench over existing piping, approximately (150’ L x 4’ W x 4’ D)
- Provided shoring as needed in trenched area
- Removed fill to uncover piping, piping sump, and foundation wall areas manually, stockpile on poly
- Allowed access for the environmental consultant to review the site
- Exposed existing pipe
- Field screened soil using a photo-ionization detector (PID)
- Drained and removed existing supply and return piping to the first UST. Removed only one UST at a time to allow continued operation of the data facility generators
- Cut the existing supply and return piping at the sump areas of the USTs so that a small length that enters the sumps can be capped off and left in place
- Cap off existing supply and return lines at each UST piping sump and leave in place along with the sump entry boots
- Completed piping installation on the first UST and returned it to service before removing piping from service on the second UST
Underground Storage Tank Piping Installation:
- Provided and installed new supply and return lines from the data center building pump room sump approximately 100’ to UST #1 and approximately 150’ to UST #2 piping sumps. Primary pipe was 3” Ameron Dualoy 3000/LCX coaxial double-wall semi-flexible pressure pipe (approximately 500’ total).
- Provided and installed four (4) transition sleeve fittings at the data center building foundation to allow the XP piping to transition to the 3” NPT schedule 40 existing piping in the building, one for each line (supply and return)
- Provided and installed four (4) double ducted entry boots and test fittings at the UST piping sumps, one for each line (supply and return)
- Provided new welded 3” dia. schedule 40 black pipe fittings to bring connections to meet up the existing steel piping with the new Ameron piping in the sump area.
- Pressure tested lines to 50 PSI on the primary piping and 5 PSI on the secondary piping pursuant to Env-Or 406.23 ‘Pneumatic Tightness Test’ and manufacturer’s recommended practices for installation
- Backfilled trench area surrounding piping with 6” of sand and 4” between piping runs
- Backfilled trench excavation with approved materials
Underground Storage Tank Pipe Testing:
The primary containment for the product supply was pressurized at 50 PSI over a 24-hour period. The secondary containment for the product supply and return lines was pressurized and held at 4 PSI over a 1-hour period. All joints and fittings were soap bubble tested during testing.