Case Histories - The Sinking Truck

On March 20, 1995, a city cleaning truck was parked on the east side of the Hayward City Airport and was about to muck out a manhole when it began to sink. The city crew watched in amazement as the front of the trunk slowly sank beneath the street. The driver was uninjured, because he was one of the spectators at the time. As one might guess, the truck was there to muck out soil that came from a topless 36" sewer pipe directly under the truck. Upon review of the sewer line, the city determined that the top of over 350' of sewer line downstream of this drop manhole was either missing or unable to sustain a load. Emergency! Panic! City pressing the political button!

The city directed one of their top engineers, Dan Owre, to direct the repair efforts. Dan's superior, Bob Bauman, Deputy Director of Public Works/City Engineer directed the overall coordination with the various city departments: Traffic Control, Bypass Pumping, etc. The city spilled 10,000,000 gallons of raw sewage before bypass pumping was set up on March 23rd to bypass 3.2 MGD. It started to rain, and another 10" pump was set up to bypass over 5 MGD total.

John Bogart, our rep in Northern California, has done a lot of promotional Vylon® sliplining in the Bay Area, and Dan's first action was to call John and obtain additional technical and delivery information on Vylon® sliplining. Dan, after calculating loads, etc. was satisfied that Vylon® could handle the 23' deep bury and saturated sultry sands, i.e. the material that has blocked and filled the line and surrounds the host pipe. John obtained credit approval expecting an order. We received an order on Wednesday, April 5th, and had the pipe on the job site Friday, April 7th.

I flew to Hayward, California on Sunday, April 9th, to instruct the city and the contractor, Manuel Jardim, Inc., on installation procedures. Proverb --sliplining jobs never start when scheduled. The city cleaned the pipe line on Monday, Tuesday, and Wednesday, and on Thursday morning, I reviewed the tapes for the second and last time --the line was clean.

The contractor had the insertion pit finished by 8:00 p.m. The city made the decision to work into the night to finish the sliplining and turn the pumps off. We started sliplining at 8:30 p.m. and finished the 400' run at midnight. The city and the contractor were both very pleased with the way the 30" Vylon® sliplining performed. To install HDPE, this pit would have been 90' long and cost the city an additional $150,000. Open cut would have cost an additional $300,000. The city has two more miles of the same line to review and repair, no doubt with Vylon® sliplining.