Hello, everyone.

This is Enta.

Landscaping used to be all the rage, but it’s becoming less and less common these days, isn’t it?

Past Projects

This slope was probably built more than 30 years ago.

The reason is the head treatment.

It’s been exactly 30 years since I entered this industry (it’s been a long time, but it’s also flown by).

Aluminum caps were already around back then.

 

I believe it was during the transition period from the era when concrete was used to encase the head.

So, to put it simply, this legal framework dates back more than 30 years.

 

Given the era, I'm pretty sure the area inside the frame was green.

That's pretty much how things stand right now.

 

I think the slope is about 50 degrees, which is steep enough to support vegetation.

Since the rock is exposed throughout, the cut slope must have been made of much fresher, rock-hard bedrock back then.

 

It appears that a layer of vegetation substrate at least 10 cm thick has been sprayed there. (If bedrock is exposed to this extent, the layer would need to be quite thick to allow for vegetation growth.)

Here's what the result looks like.

Current Situation

Nowadays, the base material for that green space has eroded away, leaving the rock fully exposed.

There are some spots where shrubs are growing due to the bedrock having been covered by sediment.

In some areas, moss is growing thickly, and the surface of the bedrock is quite weathered.

 

I guess greening bedrock areas really is a bit of a stretch, isn't it?

Rain washed away the planting substrate; the seeds died due to summer sun and winter freezing; and the substrate material rose and sank due to the freeze-thaw cycle in winter.

And once again, it gets washed away by the rain...

There are virtually no nutrients from the soil, so once the fertilizer in the landscaping substrate is used up, it becomes difficult for grass to grow.

No matter how much you try to create something unnatural within nature and blend it in, it simply won’t grow in an environment where it can’t.

 

There have been many projects to green bedrock areas in the past.

I imagine there were steep slopes, bedrock, and various other harsh conditions.

However, based on my experience, I don't think there are that many places where things are going well.

The first few years are fine.

I do think things will be pretty tough from here on out. (After going to see some of our past projects)

What are the essential requirements for greening?

I think water is a key factor. Well, that’s pretty basic, though.

Is water a factor in slope greening?

Is water seeping out of the slope?

Is there water in the bedrock?

Just doing this alone really boosts the success rate of greening, doesn't it?

It is extremely important whether the mountain itself retains water.

The water-retaining agent in the landscaping substrate isn't enough on its own.

Contradictory

But the biggest enemy of a slope is water, isn't it?

Water is necessary for greening.

However, the cause of the collapse is water.

And it is water that accelerates weathering.

 

So, in the end, it’s more effective in the long run to focus on drainage and sprayed mortar for the bedrock section rather than forcing vegetation to grow there, right?

In today's world, with labor shortages and rising management and maintenance costs, this is what a permanent slope maintenance solution would look like.

 

I have a feeling that future landscaping projects will gradually shift toward mat-based systems, and that drainage work will become the norm.

In particular, what measures should be taken for existing slopes?

I'd like to make sure we're ready to use drainage rock bolts when the time comes, lol.

 

See you later.