Madico Underground Storage Tank Sump Upgrades

CommTank provided an underground tank sump upgrade service for the existing 8,000-gallon chemical storage tank containing AP-81 at Madico in Woburn, Ma. This work focused on sump #1, sump #2, and sump #3 of the chemical storage tank. Surface water was entering the Highland Titan steel tank and diluted the AP81 chemical used to produce polyolefin foam. After CommTank tested the tank we determined that the sump was the source of the leak and needed to be replaced.

CommTank installed fiberglass sumps and tank collars from Petroleum Containment to replace the sumps on the underground tank. The AP-81 chemical storage tank was constructed using a stainless steel inner tank and a steel exterior tank with a heavy epoxy coating. CommTank crews had to grind away the coatings to achieve a clean surface to mount the fiberglass sump collars down. There was an adapter double bolt ring for each tank manway lid that had a fittings plate for all piping to enter the tank. This ring bolted to the tank and then provided studs that allowed for the fittings plate. The original polyethylene sump bolted to the outer ring but this ring was no longer needed since the fiberglass sump mounted directly to the steel surface of the tank. CommTank ordered special expanded PTFE gaskets for the manways to prevent moisture from entering and to stand up to the AP-81.

Steps to Upgrade Underground Storage Tank Sumps from Steel to Fiberglass

  • Provided safety plan and permits for work that was performed 
  • Customer drained the tank of contents (AP-81) before work began 
  • Saw cut and broke up existing concrete pad over the AP-81 tank 
  • Remove reinforced concrete debris from site 
  • Excavated around sump area and stored backfill materials on site 
  • Flooded AP-81 tank with Argon gas before manways were opened, fittings were broken, or hot work performed 
  • Cut and disassembled piping and conduits to prepare for removal of sumps 
  • Removed and disposed the three (3) existing sumps and manways on the AP-81 tank 
  • Retained the sump sensors and conduit for reuse 
  • Retained the interstitial space 12” manhole and cover for reuse 
  • Provided and installed three (3) new 36”dia. x 36”H sumps with new hardware and Teflon gaskets 
  • Provided welder to reinstall/restore piping that was cut to remove the sumps  
  • Backfilled tank and sump areas using existing backfill materials 
  • Provided new backfill for new underground tank pad area 
  • Provided and installed new hardware and Teflon gaskets, 316 stainless steel fittings, flanges, and adaptors to replace the black iron or galvanized items that were in place inside the sumps  
  • Performed test on tank and sumps to ensure manways were tight once they were installed 
  • Provided and installed new piping entry boots at the sumps 
  • Reinstalled sump sensors and seal packed the connections 
  • Provided and installed new 42” manways with secured fiberglass covers 
  • Painted and reinstalled the 12” manhole and cover for the interstitial space 
  • Provided and installed approximately 24’L x 10’W x 10”H 4,000psi, ¾” aggregate, ½” rebar reinforced concrete pad over the AP-81 UST
  • Provided as-built drawings and tank test results for the work performed