If you have a “P” you piss money away.
A “P” is the sort of classification you hope you never get when you commission a soil report on a site on Hamilton Hill. Especially if you’re hoping to build a home of architectural note there, as I am doing. A “P” means if you want to suspend anything, cantilever anything or build pretty much anything at all, there’s going to be some serious engineering required to stabilise your building’s footings.
My “P” is not a “P” for perfect, in case you were wondering.
It’s a “P” for problem site, due to (in the words of the report I received) the presence of uncontrolled fill material and trees. It’s also the worst classification you can get, according to the CSIRO’s Foundation Maintenance and Footing Performance guide.
I’ll ask you to take a look at the borehole diagrams below (at the risk of boring you to death).
During my soil test, Borehole 1 at the top of the site encountered “gravelly silt, light grey, orange, brown, moist and hard”. Don’t be dirty. I know what you’re thinking. This is a shit result. That’s true in every sense but keep it clean, please.
Borehole 2 encountered “gravelly clayey silt, grey, brown, moist, stiff” as well as “very stiff to hard”. I’m sure on long, lonely trips away from home the occasional geologist may have felt that sort of reaction, but I’m not experiencing any stiffening or hardening at this news. If anything, I’m feeling loosening in my bowels.
What about Borehole 3? Well, there is good news, right at the bottom. Two metres down past more shitty, yellow, brown, moist, gravelly silt, the borehole finally hit rock.
My impression is that Borehole 3 with its metre of weathered rock, two metres down, has encountered the only secure foundation available on site. Though it’s also halfway down the slope and too close to the boundary for my liking.
However, the advice I get from Paul Hotston (and he’s one of my architects so he should know) is that Borehole 3 is no good. He says to my relief that there is “good foundation territory around the existing building pad” at Borehole 1.
Not content to be completely reassured, I draw his attention back to the other aspect of the “P” classification: the presence of trees.
Ah, yes the trees. There’s been a whole lot of talk about one particular tree. This one.
The gracefully (dangerously) bent Jacaranda that stands in the centre of the street side boundary. It’s hard to ignore this tree when you arrive at the site. It has endured the site’s brutal redevelopment with quiet dignity and strength and it arches over the road and acts as a natural screen, a green modesty veil between neighbours across the ravine. Sadly the tree’s lean is terminal.
The two arborists I subsequently engaged to review the tree’s struggle with the savagely cut retaining wall and the angle of the slope, both reported back with hopeful suggestions that were punctuated with far too many disclaimers for my liking, so all I could hear was the sound of chainsaws.
All death is inevitable of course, but life is the time you spend delaying the inevitable. Thankfully, Paul Hotston recommended we delay the demise of the Jacaranda and not just out of squeamishness. He told me the removal of the tree now, may only create issues with a decaying stump, which will later create a “drainage pit”. Better we leave it until we know what kind of earth works we’ll be engaging in as part of the landscaping at the front of the block. I’m happy with that idea. It’s a “P” site after all. Right now, it’s “P” for procrastination.