Hi folks,

I finally took the plunge and started digging to discover the cause of
my drainage problems. Surprise, surprise - it's heavily compacted soil
on top of solid clay ... lots of clay.

I haven't got the patience to wait for the effects of soil improvement
techniques, so I've decided to start from scratch and just excavate the
whole site.

What I need to know is this:

1) ... What depth should I dig to? (I have a digger).
2) ... What type of aggregate and organic materials do I need?
3) ... What depths should each material be, and in what order?

My best guess is (top to bottom):

Compost
Topsoil
Sharp sand
Chips (granite?)
Hardcore

Is this correct? What depths for each?

Is the materials and depths different for lawn areas than for borders?

I've already excavated a test area about 12'x3' and discovered all kinds
of builders rubbish, including massive lumps of concrete and plastic
bags, etc.

Both front and back gardens are flat; the back has full sun; the front
is shaded. I'm in the N/E coastal area of Scotland (clay country), and
it's wet and windy.

Thanks,

[H]omer

[H]omer wrote:
Hi folks,

I finally took the plunge and started digging to discover the cause
of
my drainage problems. Surprise, surprise - it's heavily compacted
soil
on top of solid clay ... lots of clay.

I haven't got the patience to wait for the effects of soil
improvement
techniques, so I've decided to start from scratch and just excavate
the whole site.

What I need to know is this:

1) ... What depth should I dig to? (I have a digger).
2) ... What type of aggregate and organic materials do I need?
3) ... What depths should each material be, and in what order?

My best guess is (top to bottom):

Compost
Topsoil
Sharp sand
Chips (granite?)
Hardcore

Is this correct? What depths for each?

Is the materials and depths different for lawn areas than for
borders?

I've already excavated a test area about 12'x3' and discovered all
kinds of builders rubbish, including massive lumps of concrete and
plastic bags, etc.

Both front and back gardens are flat; the back has full sun; the
front
is shaded. I'm in the N/E coastal area of Scotland (clay country),
and
it's wet and windy.

If your topsoil is reasonably deep, all that may be unnecessary. But
as you can't wait, my experience of hardening up a west Wales clay
patch about 80' x 35' suggests a foot of 4" to 1" limestone with what
little soil and compost I could spare on top (varying in depth from
6" to 1/2" -- the stone was badly levelled) will do the trick near
enough for jazz. Where the soil was thin, the resulting lawn was prey
to moss: don't believe it if they tell you moss doesn't grow on lime,
as nature has a species for every condition.

This lawn was a bit higher along its length than the adjoining field:
this made a big difference, I'm sure, so I'd try to design a good
step down at the edge if at all possible. You don't want to build a
water-retaining clay saucer just under your lawn.

It sounds as though you may have a bit more money than I did, so you
can do a more refined job. Either way, these big jobs are fun. I did
something similar for somebody in Kent, though that wasn't a drainage
problem of the same kind, and am itching to do another.

--
Mike.

Mike Lyle wrote:
[H]omer wrote:

I finally took the plunge and started digging to discover the cause
of my drainage problems. Surprise, surprise - it's heavily compacted
soil on top of solid clay ... lots of clay.

I've decided to start from scratch and just excavate the whole site.

What I need to know is this:

1) ... What depth should I dig to? (I have a digger).
2) ... What type of aggregate and organic materials do I need?
3) ... What depths should each material be, and in what order?

my experience of hardening up a west Wales clay patch about 80' x 35'
suggests a foot of 4" to 1" limestone with what little soil and compost
I could spare on top (varying in depth from 6" to 1/2"

So you reckon 12" of chips followed by 6" of organic material?

6" doesn't sound very deep. I was planning on planting trees as well.

Is that really all I need?

It sounds as though you may have a bit more money than I did, so you
can do a more refined job.

Well I can pretty much afford to do anything I like with this garden, so
yes, I want to do the best job possible.

Thanks for the info.

-
[H]omer

In article , [H]omer wrote:

So you reckon 12" of chips followed by 6" of organic material?

6" doesn't sound very deep. I was planning on planting trees as well.

Is that really all I need?

Most clays are very fertile - all they need is to be opened up
so that water can drain and air reach the roots. So you don't
want to remove the clay so much as dilute it in the soil with
coarse material. This needs to be done fairly deeply, for the
drainage.

6" of organic matter is far more than most soils have. My loam
has 12-18" of topsoil, of which only a small proportion is actually
organic material, and it is nearly as fertile as soils get.


Regards,
Nick Maclaren.

Nick Maclaren wrote:
In article , [H]omer wrote:

So you reckon 12" of chips followed by 6" of organic material?

6" doesn't sound very deep. I was planning on planting trees as well.

Is that really all I need?

Most clays are very fertile - all they need is to be opened up
so that water can drain and air reach the roots. So you don't
want to remove the clay so much as dilute it in the soil with
coarse material. This needs to be done fairly deeply, for the
drainage.

6" of organic matter is far more than most soils have. My loam
has 12-18" of topsoil, of which only a small proportion is actually
organic material, and it is nearly as fertile as soils get.

I didn't make it clear before, but my current 'soil' is about 1/2" of
what looks like mainly sand (think the kind of soil you get at the
inland edge of a beach), followed by ???" of clay (I haven't struck rock
yet!!!). Therefore, for all intents and purposes, there is no real soil
on site; I'll have to buy some in.

/me gets his calculator out

Is this about right then? ...

I excavate 24", and keep the clay.
I mix the clay with aggregate, and backfill 12".
I buy in a skip of topsoil, and backfill 6"
I buy in a skip of GP compost, and backfill the remaining 6"

Does that look OK?

Thanks,

-
[H]omer

[H]omer wrote:
Nick Maclaren wrote:
In article , [H]omer
wrote:

So you reckon 12" of chips followed by 6" of organic material?

6" doesn't sound very deep. I was planning on planting trees as
well.

Is that really all I need?

Most clays are very fertile - all they need is to be opened up
so that water can drain and air reach the roots. So you don't
want to remove the clay so much as dilute it in the soil with
coarse material. This needs to be done fairly deeply, for the
drainage.

6" of organic matter is far more than most soils have. My loam
has 12-18" of topsoil, of which only a small proportion is
actually
organic material, and it is nearly as fertile as soils get.

I didn't make it clear before, but my current 'soil' is about 1/2"
of
what looks like mainly sand (think the kind of soil you get at the
inland edge of a beach), followed by ???" of clay (I haven't struck
rock yet!!!). Therefore, for all intents and purposes, there is no
real soil on site; I'll have to buy some in.

/me gets his calculator out

Is this about right then? ...

I excavate 24", and keep the clay.
I mix the clay with aggregate, and backfill 12".
I buy in a skip of topsoil, and backfill 6"
I buy in a skip of GP compost, and backfill the remaining 6"

Does that look OK?

I wouldn't bother buying in the compost: the topsoil you buy probably
won't be brilliant, but it'll do perfectly well; and compost alone
won't provide enough physical support for plants (remember it's used
in pots and other containers, not the open ground). I reckon the
stone underneath should give you reasonable drainage, as long as the
water's got somewhere to _go_. If there's no way out, all your
operations won't have any long-term effect. So if you're going to dig
out, it would be worth putting in some plastic land drains (local
farmer's merchants or Jewson-type place). But of course, they'll
still have to lead somewhere.

I think I'd let it all settle for a year before putting in trees: it
won't be very stable. (I have to say it's amazing what will survive
in almost pure clay; and of course growing things will improve the
soil in itself.)

--
Mike.

In article , [H]omer wrote:

I didn't make it clear before, but my current 'soil' is about 1/2" of
what looks like mainly sand (think the kind of soil you get at the
inland edge of a beach), followed by ???" of clay (I haven't struck rock
yet!!!). Therefore, for all intents and purposes, there is no real soil
on site; I'll have to buy some in.

That smells wrong. I strongly advise analysing it first - your clay
may not be entirely clay. My soil is 60% sand, 18% silt and 22% clay,
and you should likke at various loams - if you have basically clay,
you WANT the sand.

To analyse clay at home, half fill a clear glass wine bottle with
soild from a particular horizon, put a spoonful of washing powder
(the corrosive type) into it, fill up with water and shake until
it is an emulsion. The sand will drop out almost immediately
(20 seconds?), the silt fairly quickly (30 minutes?) and the clay
over a period of days to weeks. Somwhere on the net is the actual
description of the method and times.

Again, you can find it on the net, but look up what a good loam is.
If I recall, equal parts of sand and clay is heavy, but good. Mine
is a fairly sandy loam. If your clay contains a fair amount of
sand, you may want to add a bit more sharp sand or fine gravel (or
small aggregate), but the key is to loosen it. This will be tricky
as diggers compact the soil - so you may need to reverse carefully.

Anyway, while I am no expert, that is roughly right.


Regards,
Nick Maclaren.

[H]omer wrote in message
...
Hi folks,

I finally took the plunge and started digging to discover the cause of
my drainage problems. Surprise, surprise - it's heavily compacted soil
on top of solid clay ... lots of clay.

I haven't got the patience to wait for the effects of soil improvement
techniques, so I've decided to start from scratch and just excavate the
whole site.

What I need to know is this:

1) ... What depth should I dig to? (I have a digger).
2) ... What type of aggregate and organic materials do I need?
3) ... What depths should each material be, and in what order?

My best guess is (top to bottom):

Compost
Topsoil
Sharp sand
Chips (granite?)
Hardcore

Is this correct? What depths for each?

Is the materials and depths different for lawn areas than for borders?

I've already excavated a test area about 12'x3' and discovered all kinds
of builders rubbish, including massive lumps of concrete and plastic
bags, etc.

Both front and back gardens are flat; the back has full sun; the front
is shaded. I'm in the N/E coastal area of Scotland (clay country), and
it's wet and windy.

Thanks,

[H]omer

Hi Homer,

I wonder how deep you're excavating, and how close to your house. I must
assume that your house is built on the same heavy clay, and I am concerned
about subsidence if you materially change the surrounding soil. Here, on
heavy London clay, we have already had to rebuild our garage due to
subsidence, and that's with just the clay's normal reaction to rain and
drought. We are constantly watching for cracks now. Other houses in our
road have also had to be underpinned.

Insurance companies are very aware of the way clay reacts, and charge a
higher premium on building insurance policies where properties are affected.
It would not be wise to undermine your house *and* risk voiding your
insurance policy.

You may, of course, be a surveyor and know exactly what you're doing. I
don't mean to frighten you, but if I have awoken any doubts, please consider
consulting a surveyor (and, perhaps, your building insurer) before it's too
late.

Hope everything goes okay and you get the garden you crave for.

Spider

Nick Maclaren wrote:
In article , [H]omer wrote:

I didn't make it clear before, but my current 'soil' is about 1/2" of
what looks like mainly sand (think the kind of soil you get at the
inland edge of a beach), followed by ???" of clay (I haven't struck rock
yet!!!). Therefore, for all intents and purposes, there is no real soil
on site; I'll have to buy some in.

That smells wrong. I strongly advise analysing it first - your clay
may not be entirely clay. My soil is 60% sand, 18% silt and 22% clay,
and you should likke at various loams - if you have basically clay,
you WANT the sand.

To analyse clay at home, half fill a clear glass wine bottle

Hi Nick,

Yeah I remember doing the soil-test-in-a-jar experiment way back in my
school days.

Let me put it this way, the clay under my garden has the consistency of
putty, i.e. it is nearly pure, terracotta-red, potter's clay. It's so
'good' in fact that I am actually going to be selling it to a local arts
and crafts club.

It would seem that I'm sitting on top of a clay pit. Oh lucky me.

I am brassed off that the property developers slapped lawns directly on
top of wet-clay with zero drainage.

I understand that clay is not intrinsically the evil entity that some
people think it is; it is rich in nutrients after all, but it's also a
pain WRT drainage.

I think my garden may actually be one of those that really does need
field drainage pipes.

I'm going to be calling in a guy who's a tree surgeon and landscaper, to
help me with a tree that's been blown partly over by the horrendous wind
we get round here, so I'll ask for his expert opinion about drainage on
site as well.

Thanks again,

-
[H]omer

Spider wrote:

I wonder how deep you're excavating, and how close to your house. I must
assume that your house is built on the same heavy clay

I'm afraid that it certainly looks that way.

,and I am concerned about subsidence if you materially change the
surrounding soil.

Me too.

I don't mean to frighten you, but if I have awoken any doubts,
please consider consulting a surveyor (and, perhaps, your building
insurer) before it's too late.

You have, and you have, in that order.

It had occurred to me before actually. The property developer was
brought to task by other residents over several issues, including
flooding. Basically they built the entire site on a known ancient
floodplain, and within the first year nearly every house was under 3ft
of water. They then "diverted the source upstream", but still the
flooding came. Eventually the council took drastic action to dam the
source, and we haven't seen any flooding since.

Everyone round here is aware that the developers are a bunch of cowboys.
The state of our 'new' houses when we moved into them was pitiful, so it
didn't really surprise me to discover we were sitting on top of a clay
pit. I was angry, but not surprised.

Hope everything goes okay and you get the garden you crave for.

Well there's always Water lilies, I suppose.

Thanks,

-
[H]omer

It had occurred to me before actually. The property developer was
brought to task by other residents over several issues, including
flooding. Basically they built the entire site on a known ancient
floodplain, and within the first year nearly every house was under 3ft
of water. They then "diverted the source upstream", but still the
flooding came. Eventually the council took drastic action to dam the
source, and we haven't seen any flooding since.

Everyone round here is aware that the developers are a bunch of cowboys.
The state of our 'new' houses when we moved into them was pitiful, so it
didn't really surprise me to discover we were sitting on top of a clay
pit. I was angry, but not surprised.


and you blame all of this on the builders?

Who gave them Planning Permission? They may be 'Cowboys', but they didn't
give themselves Planning Permission. Perhaps you were not there at the time,
but were any objections lodged? Not only have I had a planning application
for a couple of blocks of flats turned down because of possible flooding if
the development went ahead, but I have caused the Council to withdraw a
large chunk of land they wishes to sell for building on, off the market
because of possible flooding. The two houses opposite me flooded to above
skirting board level 4 times in the first 16 years I was here. "Nothing can
be done, its the lay of the land" so said the Council and the Water
Authority. I fought to have the road surface re-aligned so the water could
run down the road instead of down their drives and flood them.

Sorry, you can't blame it all on the builders. Blame the Council, the owners
of the land and the people around for not shouting out in the first place.

Mike

[H]omer wrote:
:: Spider wrote:
::
::: I wonder how deep you're excavating, and how close to your house.
::: I must assume that your house is built on the same heavy clay
::
:: I'm afraid that it certainly looks that way.
::
::: ,and I am concerned about subsidence if you materially change the
::: surrounding soil.
::
:: Me too.
::
::: I don't mean to frighten you, but if I have awoken any doubts,
::: please consider consulting a surveyor (and, perhaps, your building
::: insurer) before it's too late.
::
:: You have, and you have, in that order.
::
:: It had occurred to me before actually. The property developer was
:: brought to task by other residents over several issues, including
:: flooding. Basically they built the entire site on a known ancient
:: floodplain, and within the first year nearly every house was under
:: 3ft of water. They then "diverted the source upstream", but still
:: the flooding came. Eventually the council took drastic action to
:: dam the source, and we haven't seen any flooding since.
::
:: Everyone round here is aware that the developers are a bunch of
:: cowboys. The state of our 'new' houses when we moved into them was
:: pitiful, so it didn't really surprise me to discover we were
:: sitting on top of a clay pit. I was angry, but not surprised.
::
::: Hope everything goes okay and you get the garden you crave for.
::
:: Well there's always Water lilies, I suppose.
::

If you contact building control[1] at your local council they may be able to
tell you on what foundations your house is built....from what I can glean
from your posts it sounds like infill, thousands of tonnes of clay over the
top of what was there before, if this is the case, it's highly likely your
house is built on piles (concrete stilts which go down very deep, usually
until bedrock is found)...once all these piles are in place, a reinforced
concrete strip is then poured on top and the house built on that, other than
that it could well be on a raft - one huge block of concrete, usually at
least a metre deep and the entire floor area of your house, the idea with
this is that if anything moves, it all moves.


[1]
There may be a search fee, but I'd do this before contacting your insurers,
they will double your premium at the drop of a hat.

--
"Our enemies are innovative and resourceful, and so are we.
They never stop thinking about new ways to harm our country
and our people, and neither do we."
- George W. Bush, 5.8.2004

Mike wrote:

It had occurred to me before actually. The property developer was
brought to task by other residents over several issues, including
flooding. Basically they built the entire site on a known ancient
floodplain, and within the first year nearly every house was under 3ft
of water. They then "diverted the source upstream", but still the
flooding came. Eventually the council took drastic action to dam the
source, and we haven't seen any flooding since.

Everyone round here is aware that the developers are a bunch of cowboys.
The state of our 'new' houses when we moved into them was pitiful, so it
didn't really surprise me to discover we were sitting on top of a clay
pit. I was angry, but not surprised.


and you blame all of this on the builders?

Who gave them Planning Permission?

Well there's obviously several people to blame; the council for granting
the planning permission; the developers for going ahead despite knowing
that the area was a floodplain; and the residents for not voicing their
concerns loudly enough.

We weren't here when the development kicked off, and didn't know anyone
in the area. Also, because it was a new property (and for various
reasons we were in a hurry), we made the fatal mistake of not hiring a
surveyor; we took our solicitors word, and that of the developer, that
the property was sound. It was a bit of a rush job, due to us losing our
deposit on another property from the same developer (which was later
honoured anyway, at their discretion, on the new property), and failing
to sell our old house in time for the purchase of the new one. In
retrospect, we should have got a bridging loan and taken more time, but
it's easy to say that now.

To give you an idea of how dodgy this whole affair is: about a year
after moving in we got talking to the local butcher, who said that the
developers had come calling one day to ask about the area (a sort of
questionnaire). The butcher replied that the area was a floodplain, and
had been for centuries. The developer replied, and I quote our butcher,
"Oh, we don't want to hear that", and apparently he wasn't smiling when
he said it.

I think you'll find that the developers made some kind of false
assurances to the council WRT dealing with the flood problem. That would
also have allayed any objections raised by the public.

Maybe they really did intend to deal with the flooding, but like
everything else these developers do, didn't pull their thumbs out and do
it quickly enough (they are still building further up the street - 5
years behind schedule).

Here's another example: the bridge over the river which divides us from
the rest of the world, was grossly inadequate, and became impassable
during the flooding. Essentially it was just a dip in the road, made of
solid concrete and had a small drainage pipe shoved through it. Two
years, and two major floods later, it was still there. It took court
action to force them to replace it with a real bridge, which they have
finally done.

Anyway, I'm sure the council share the responsibility for this mess, but
equally there are a mountain of faults that the developers are
responsible for, not least of which is the clay pit I'm sitting on.

-
[H]omer

Phil L wrote:

If you contact building control[1] at your local council they may be able to
tell you on what foundations your house is built....from what I can glean
from your posts it sounds like infill, thousands of tonnes of clay over the
top of what was there before, if this is the case, it's highly likely your
house is built on piles (concrete stilts which go down very deep, usually
until bedrock is found)

Hi Phil,

Without any official enquiries, here's what I can tell you:

I was in the garden one day, when suddenly I noticed (actually heard)
something moving next to the house. Upon closer inspection it turned out
that the granite chips, that form a 'moat' round our house, were being
'sucked' under the foundation. I got a trowel and started digging the
area, only to discover that there was a void area that seemed to run the
entire width of the foundation, and seems to be repeated at intervals
along the the entire length of the foundation.

I can only assume that these are the concrete stilts you refer to, and
if so, then I am greatly relieved. Given the bog that the foundation is
sitting on, it doesn't surprise me that they used this method, since it
is surely the only way of suspending a building over it.

It would also explain why my tarmac driveway is full of cracks.

I'll make the official enquiry anyway, but thanks for setting my mind at
ease somewhat.

Regards,

-
[H]omer

Anyway, I'm sure the council share the responsibility for this mess,


with regards to giving planning permission, there is no 'share' about it.
Unless they can prove that they did not give planning consent ???? and
unless they can prove in writing that the Builder/Developer was/is going to
do something about the flooding, then the ball is in their court and I would
need a lot of convincing that is not the case.

Of course from here I cannot fully grasp the situation, but I feel that a
Residents Action Committee should have been started a long time ago to fling
more than the proverbial 'Seven Buckets of the nasty stuff' at them.

You might be interested to know that when I was shouting out so much about
the Council and fighting for the residents, that at a meeting, it was
explained that 'There is a vacancy on the Parish Council would you like to
join us?' The neighbours who were being affected by the flooding urged me to
go on and fight for them. I was co-opted on. THEN realised I was on there to
shut me up. Consequently I am not standing for re-election in May.

Are your houses built under the National House Builders Council or whatever
it is called? Whereby your houses are examined at each stage of build and a
20(?) year guarantee placed on them?

Mike