The roadway above the new Fortuna water tank failed last week and a collaborated effort, including hardware designed by a Humboldt County business was used to stabilize the area.
The Spiralnails that were used to anchor the reinforcing wire mesh were manufactured by Hilfiker Retaining Walls in Eureka, and owner Bill Hilfiker and son Arthur were both on site on December 2nd to participate in the repair work.
The Spiralnails are 20 to 25 feet long, and perforated to let water run out. Fortuna Mayor Doug Strehl was watching over the repair work onsite and said “It's good to have this type of local expertise, and also good that they (Hilfiker representatives) were here (to help with the repairs).”
The roadway failed on Nov. 30, leaving a muddy mess of soil and debris against the new water tank and causing concern among Stewart Street residents that there might be bigger problems.
Truckloads of dirt were removed on Nov. 30 and repairs continued for the next three days. The repair work was conducted under the direction of water tank installation geologists SHN Engineers & Geologists, and included stabilizing the toe of the slide beneath the soil nails. The project geologists will continue to monitor the site and direct additional steps if necessary.
The situation was discovered Nov. 29 as a crack in the Stewart Street roadway above the new water tank, and appears to have been exacerbated by excessive rainfall over the next several days.
GHD, Inc. (formerly known as Winzler & Kelly) is also a contractor in the project. Senior project manager Merritt Perry noted that there were multiple springs in the area of the new water tank. “There is so much water in this hillside,” he said. He also complimented the crew that came together to fix the situation. “These are good contractors and innovative people,” he said, referring to those who helped make the repairs.
Once the hillside is stabilized, the area between the new water tank and the roadway will be filled.
The installation of the new water tank is nearing completion. The new 2 million gallon water tank on site now replaces two older 500,000 gallon concrete tanks on that same location. The 75-year-old circular and 100-year-old rectangular tanks on the site have now been replaced, and a portion of one of the original tanks was left intact to support the hillside.
The contract for the new water tank was originally awarded to Sacramento-based Ariza Construction in October 2011, a contract that was later terminated. The city of Fortuna then entered into a contract agreement in March of this year with Wahlund Construction Inc. of Eureka to finish the project.
Photos by Heather Nyberg-Schlotzhauer/Beacon
1. Repair work is conducted on the road failure and slide near the new two million gallon water tank in Fortuna (portion of new tank in far left of photo). A section of one of the older 500,000 gallon tank was left in place to support the hillside
2. Spiralnails were used to stabilize the slide area near the new Fortuna water tank. Hilfiker Retaining Walls in Eureka developed the product as part of a method of soil reinforcement.