i see you are rather new to GW.. welcome.. please dont let me scare you away ... lol ...

is this a spoof.. if so.. its brilliant ... lol ...

you have 100 foot trees.. and 4 to 8 inch flowering shrubs.. and you think you have a problem???

the only problem i see.. that involves large machines.. is to strip out the driveway down to hard pan.. and re-lay it there.. to avoid the swamping there ..

and ignore your trees ... as you say.. well established.. trees dont really need you 'fixing' something they dont consider to be a problem ....

and who advised you this.. the machine renter???:

I have been advised to bring in some fairly stern equipment and drill holes all over the yard down through the hardpan.

i like the mountain/mole hill analogy ...

ken

ps: why did you have a tree in the middle of your driveway???? oh.. dirt driveway??? ... wait.. city lot.. in my world that means paved drive .. i am so confused.. and entertained.. lol ...

Ken,
I'm not sure if you'll be disappointed or not but... it is all true.

The house I bought was owned by a very old woman who died in it. According to the locals she was born in this house and planted the trees. She did no maintenance on the place for more than thirty years. The driveway was decomposed granite. The property is big enough that the driveway did a circle around a garden of sorts with a bunch of different trees. The only one that was still alive was the big crepe myrtle that I moved.

The house itself is being held up by the termites. I'm afraid that if I tent it the place will turn to dust. The slope between the dinning room and living room is steeper than most beginner ski hills. Around the house itself are a bunch of these huge ornamental trees that I am slowly but surely moving to other parts of the property. There are a couple of big ones that I can't move and so I am designing the new house to be built around them. Oh I almost forgot. As the old lady headed into her dotage she became paranoid and the place is ringed by a 7 foot concrete fence. There are stadium level lights that come on at night or would if the bulbs weren't burnt out. The only thing missing is concertina wire or maybe guard towers.

An acre of land in the city covered in mature trees. I love it. I have even become fond of the fence. I have now got almost enough foliage around the perimeter that I can't see it and no one can see me.

The problem that I am trying to rectify is that the whole lot is essentially a swamp and I really do like to walk around all these trees. I also would like to be able to use all of my driveway. The chances of me taking the driveway down to hardpan and building it up are zero. For starters that would be about 8 dump trucks worth of dirt and the cost of rock fill would be huge.

Finally the advice came from a friend who owns an orchard and a geologic engineer. I am just worried that changing the ecosytem will be a hardship for the trees. That I would not want.

grizwald,
IMHO, drilling through the hard pan as described would likely result in the death of many of those trees. That is probable how they are getting water in the dry season, and trees that large don't tolerate much in way of root disturbance. As for the people that made the suggestion to you, they are very limited by their experience/knowledge. A orchard manager irrigates, and their trees are 15-20' at most, not 100'. The geologic engineer is not a Arborist, Biologist, or Botanist with learn term experience preserving large trees. So neither likely have any real understanding from a longer term biological perspective of the trees.

As for getting around the property, you might consider paths of thick mulch. You could walk on these and not compact the soil, nor sink into mud. Lastly, you mention building a new house, and that will present hugh problems in protecting those trees. Not the least of which is that construction workers like to park under them compacting the soil resulting in possible death of those trees, and contractors like to pile loads og soil over the root zones that kill the roots, and therefore the trees, construction workers tend to bang heavy equipment into the trees and damage them, tend to not care period.

Point being, you have many many more hurtles to go to protect your trees. You may already know this, but I wanted to make sure you are aware,

Arktrees

Drill through the hardpan?! Who knows how deep you would have to drill to do this? Hardpan can be hundreds of feet deep. It's not caliche. Ask a local well driller for an educated guess. Drilling records are on file. Personally I don't that's the solution.
You're on a hill. With some shovel work, you can contour out a way to drain the excess water in the winter.
With about two feet of topsoil to deal with, I'd be afraid some of those 100 ft. tall trees will blow over.
Any chance of some pictures?
Mike

The answer is wood chips. You should be able to get them for free from your city. Basically what you do is dump a thick layer (around a foot or two) where you are having these issues. As it decomposes it will act as a sponge holding all that standing water. Also it will improve your overall soil conditions creating a home for worms and microbes that will losen up that hardpan. Permaculturist use this same method.

This post was edited by greenthumbzdude on Thu, Jan 10, 13 at 13:17

Thanks for the thoughts.
I like the mulch idea and the path. I am going to have to do something about the driveway maybe the trench and drain. As far as pictures I will see what I can do although I am not much of a photographer.

I have a reasonable amount of experience with construction folks and I have found they respond fairly well to offers of cash and threats of violence. I plan on demarcating paths for vehicles that must come in and locking the gate against those that don't. My biggest worry is cement trucks although I might be able to use a pumper.

Again thanks for the thoughts.
Griz