On 2/21/12 8:16 AM, saltdog wrote:
Hi Folks,

I just joined the forum today so thought I'd pop on to say hi. I've
recently finished building a new house which I'm over the moon with.
Unfortunately, my house with a footprint of 93 square metres is sitting
on a building site of 870 square metres which I want to change in to a
lovely garden. However, the house has swallowed most of my money and my
fingers are decidedly un-green!! Little bits at a time though.

Firstly, I'm based in Orkney so you can rest assured that my garden will
get plenty of wind and rain. The soil seems to be a thin layer of
topsoil with some horrible wet, sticky clay beneath. At the weekend I
hired a mini-excavator and took out the bottom of my sloping back
garden. My intention is to increase the width of the path at the back
of the house by 200% to create a nice patio. I also plan to hold the
garden back with a retaining wall at about 2-3 feet high. I'll decide
on the final height when I see it. I'm going to be doing all the work
myself which I'm quite looking forward to.

The last thing I paid my builder to do was to build a perimeter wall
around my land. He did a top job and it's looking amazing.
Unfortunately, as my house is on a slope, the water has really started
gathering at the back of the wall round the front of my house. Not
good!! So, I'm going to have to think about putting in some drainage.
I was considering just digging a sump and filling it with hardcore but
I'm not sure if that's going to be enough. I may have to connect a
perforated pipe to the surface drain connected to the SUDS. More than
likely, I'll end up having to do the same with the retaining wall at the
back.

My aim is to have grass in this year so I'm up against it trying to fit
everything in with a full time job and dark evenings. Not to mention
the awful weather.

Is it worth me digging in the sticky clay while it's still soaking wet?
I need to put in a base for my patio. Will sand alone be sufficient for
that or so I really need hardcore? I'm sure I'll have loads of
questions throughout my adventure but I'm in it for the longhaul so am
looking forward to the challenges.

A well-built wall -- either a perimeter wall or a retaining wall --
should have weep holes to allow for drainage. If your perimeter wall
does not have weep holes, you should get a good masonry drill bit and
create some.

To make the clay less sticky and more easy to dig, broadcast a generous
amount of gypsum over the area, perhaps a centimeter (1/3 inch). Let
the rain rinse it into the soil. Repeat at least once.

A retaining wall needs to be engineered correctly. This is generally
NOT a do-it-yourself project. There are issues about footings (depth
and width), anchoring into the slope, amount and size of rebar (steel
rods), grout, etc.

A retaining wall is not a slough wall. I have the latter at the foot of
a slope. It does not hold the slope but merely prevents small amounts
of loose soil from reaching the flat area of my garden. When my slope
failed, it overtopped the slough wall. It cost over $150,000US to
regrade the slope; it would have cost twice that to use a retaining wall
to hold the slope.

--
David E. Ross
Climate: California Mediterranean, see
http://www.rossde.com/garden/climate.html
Gardening diary at http://www.rossde.com/garden/diary