Removal of tree close to footpath, carpark and property

[Dbarnard]

Hi I was looking to remove a 30 year old hawthorn from the back of my garden. The tree is around 10m high and 6m wide. I've attached pictures. The tree is next to a tarmac foot path and around 1m from that is a hedge with stone risers and 1m from that is a blocked paved carpark. There is a property 5m to the left of it.

 

Ive been reading online about ground heave and it has me very worried. From the facts I've gathered.

 

The property was built in 1979. So the tree was planted after the property was built.

 

I'm trying to work out if the soil is clay because I've heard that can be bad as it can swell when the tree I removed. Do you know how I can test this? Dug a whole by the tree this morning. Its black and slightly sticky. Worried about it because i know for certain that around 5m from the tree back towards my house theres a patch of clay.

 

I'm trying to gauge what steps I need to do to remove the tree. I have read online a gradual reduction of 1/3 a year can work? And when the tree is eventually a stump it can be grinded out. I've read that this means the soil can recover per year.

 

Behind the tree it's pure tarmac I.e theres no soil. But I'm paranoid what's beneath the tarmac. One picture I've attached is where the tarmac on the boarder has slightly raised. It isn't huge but it has me worried the roots have propagated out further.

 

If and when the stump is removed I guess I need to contact the council to repair the tarmac.

 

Just looking for advice really. I've contacted an alborist to see what they have to say but just trying to gather information.

 

Edit: had another look at the soil I think it is loam/clay you can feel grit in some bits but you get the odd bit that is silky smooth. I've had a look on a soil map of the uk and that matches with that. The soil map says theres a slight impedance to drainage. Hoping this is only really an issue for pure clay soil?

Edited December 23, 2019 by Dbarnard
Checked soil type

[Chris at eden]

1 hour ago, JonnyRFT said:

No offence taken. I’m often wrong and try to learn from mistakes but my original answer stemmed from the trees size compared to its location. Judging from the picture I would say there’s 9m to the closest property and the impact of the removal of this tree would be tiny. I would also hazard a guess that the tarmac is durable enough at this point to accommodate any further movement in the future after the stump is treated. There’s also a neighbouring tree (maybe Ash?) that may regulate moisture content of the soil over time.

 

But, I was unaware of the 12.5m zone of influence. Could this be the case for the tree in question considering it relatively small size?

Hello mate

 

Thanks for taking it in the spirit it was intended. 

 

The ZOI is calculated by cross referencing the mature height of the tree species  and then multiplying by:

 

• 1.25 for high water demand trees.
• 0.75 moderate water demand trees.
• and, 0.50 for low water demand trees.

It uses mature height as trees grow and so you have to consider the long term implications.  The mature height of Hawthorn in the standard is 10m so the calculation is 10 x 1.25 =12.5m.  That tree is at about 10m anyway so yes 12.5m would be about right.     

 

If you look at something like Birch - this is low water demand with a height of 14m  - so 14m x 0.50 = ZOI of 7m.  Bigger tree with a smaller ZOI.  Or, Wellingtonia with a height of 30m and moderate water demand - 30m x 0.75 = ZOI of 22.5m, so a moderate water demander but with a larger ZOI just due to its size.  Then Hybrid Black Poplar has a ZOI of 35m as it is big and has high water demand. 

 

You can view the list in NHBC Chapter 4.2 which you should be able to find on Google. 

 

As Gary said its not perfect and there are instances where damage can occur outside of these numbers but its the main source of info we have at present.  There is a famous quote by Giles Biddle which goes along the lines of 'the only predictable thing about tree related subsidence is its unpredictability'.  Sums it up pretty well.

 

Cheers        

 

[JonnyRFT]

35 minutes ago, Chris at eden said:

Hello mate

 

Thanks for taking it in the spirit it was intended. 

 

The ZOI is calculated by cross referencing the mature height of the tree species  and then multiplying by:

 

• 1.25 for high water demand trees.
• 0.75 moderate water demand trees.
• and, 0.50 for low water demand trees.

It uses mature height as trees grow and so you have to consider the long term implications.  The mature height of Hawthorn in the standard is 10m so the calculation is 10 x 1.25 =12.5m.  That tree is at about 10m anyway so yes 12.5m would be about right.     

 

If you look at something like Birch - this is low water demand with a height of 14m  - so 14m x 0.50 = ZOI of 7m.  Bigger tree with a smaller ZOI.  Or, Wellingtonia with a height of 30m and moderate water demand - 30m x 0.75 = ZOI of 22.5m, so a moderate water demander but with a larger ZOI just due to its size.  Then Hybrid Black Poplar has a ZOI of 35m as it is big and has high water demand. 

 

You can view the list in NHBC Chapter 4.2 which you should be able to find on Google. 

 

As Gary said its not perfect and there are instances where damage can occur outside of these numbers but its the main source of info we have at present.  There is a famous quote by Giles Biddle which goes along the lines of 'the only predictable thing about tree related subsidence is its unpredictability'.  Sums it up pretty well.

 

Cheers        

 

Well that was the best and most insightful answer I’ve received in a long time. Thank you.

[Gary Prentice]

1 hour ago, Chris at eden said:

As Gary said its not perfect and there are instances where damage can occur outside of these numbers but its the main source of info we have at present.  There is a famous quote by Giles Biddle which goes along the lines of 'the only predictable thing about tree related subsidence is its unpredictability'.  Sums it up pretty well.

Just something to throw into the thread for consideration.

 

As Chris has said these categories are derived from trees that have been involved in subsidence cases. We should also consider all the trees on similar soils close to structures, of similar foundation design and depth, that haven't caused subsidence!

[Frank Kerman]

It seems like very old tree. you should damage the roots to completely remove tree. you can use any acid on roots.

[doobin]

1 hour ago, Frank Kerman said:

It seems like very old tree. you should damage the roots to completely remove tree. you can use any acid on roots.

 

^Ignore the Indian spam/witch doctor above, I'm sure he'll be gone shortly.

Edited February 2, 2020 by doobin