The initial problem with the property was that it was built on a slope composed of about 30 feet of man-imported fill, which was done at a time when grading standards were far less stringent.
RANCHO PALOS VERDES, Calif. (PRWEB) June 03, 2018
In a recent interview with James Chantler, Structural Assessor for Alpha Structural, Inc., Chantler states, “The initial problem with the property was that it was built on a slope composed of about 30 feet of man-imported fill, which was done at a time when grading standards were far less stringent.” He goes on to state, “The previous contractor had replaced the existing sinking slab addition with a steel reinforced slab. However, unfortunately, the replaced slab wasn’t properly tied into the existing slab, and it was not on a deepened foundation system, and so it sank again.” This time around with Alpha Structural, the homeowners went the whole nine yards with the deepened underpinning system for a permanent resolution.
This particular project was an interesting one due to the lack of accessibility for heavy machinery. Alpha Structural was only able to get a very small drill rig in there, requiring much of the new foundation system to be hand-excavated. Additionally, Alpha Structural had to cut open parts of the deck structure and overhangs in order to place the steel cages for the friction piles which ranged from 35 to 45 feet deep. The friction pile rebar cages were installed using a 100-ton crane provided by Champion Crane. The concrete grade beam stretched around 3 sides of the addition and was also extended to underpin the existing deck structure that was also sinking.
The project took approximately 2 months from start to finish once ground was broken. The majority of the time and labor was the excavation of the piles and getting through several shelves of hard rock. Chantler states, “During the excavation, we were hitting, 3, 4, 5-foot-thick shelves of hard rock which the drill rig couldn’t drill. We had to get down inside the holes with air hammers and demolish by hand. We had to case shore the holes, pump air down inside, harness the crews, etc.” It was tricky, and required creativity and technical precision, but this is something Alpha Structural specializes in and has been regarded as an expert in accomplishing since 1993.
In discussing the project with Steve Ferguson, Job Supervisor for Alpha Structural for this project, Steve stated, “This mostly comes up on hillside homes. Over time the hill will give way or creep as the soils engineers call it. In this particular project, we think that there wasn’t enough compaction when they built the house or the addition. No problem. We get the soils engineers report and design a pile and grade beam job which is basically a big trench going all the way around the back end of the house with the piles that go deep enough into the bedrock to hold it. Every structure is unique and every hillside is unique, so it really depends on what they are composed of and how deep we need to go in order to get far enough into the bedrock to secure the ends of the concrete piles. Normally our guys don’t have the luxury of having the steel built before we lower it in, usually we will build the cages inside the piles, but in this particular case we needed to crane the steel cages over the house and into the piles. It was awesome.”
The homeowner had the following to say about the team at Alpha Structural, “All of the people from Alpha Structural that I dealt with were extremely responsive. James Chantler, the agent that initially investigated the situation, Steve Ferguson, the Project Manager, and the engineers who designed the project were all great. The Foreman, Mario, and his crew are some of the hardest working and polite men you’d ever hope to meet. When they left the job site at the end of every day, it appeared cleaner and neater than when they arrived to start the day. I am very satisfied with Alpha Structural’s performance, and I consider myself fortunate to have found and engaged them to execute the project.”
James Chantler of Alpha Structural states that fortunately or unfortunately, Alpha Structural encounters this sort of project frequently in the Rancho Palos Verdes area, and it’s a worthwhile investment of time to minimally have the hillside and structure evaluated if you notice any signs of settling or sinking in the home. A proper evaluation should be done in order to be 100% certain.