Driveway Dry-Well, etc.

Old 01-21-07, 06:00 AM
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Driveway Dry-Well, etc.


Will post here, but should ask if this is the most appropriate Forum for a driveway question ?

Have moved into a 30 year old house that has an asphalt driveway with the house at the bottom of.

Near the bottom there is what I believe is called a "dry-well".
There's a heavy metal grate that is over what I guess can be called a "pit".

At one time the metal grate was level with the asphalt, I would imagine, but isn't any more. The grate has sunk about 6 or 8 inches, and the asphalt looks "collapsed" around it.

In the Spring will probably have a top coat of new asphalt applied, or the present asphalt dug up and I guess new gravel put in place, and then the new asphalt.

Haven't gotten any quotes yet on the two approaches, although the digging up the old, and placing new gravel down is probably the better, and more expensive certainly, way to go. What do you think ?

Questions, please:

a what is typically done: just the top layer removed and a new asphalt layer of a few inches placed right over the existing gravel ? Or, should one always dig up the old gravel and replace with new gravel ?

Suggested thicknesses for new gravel, and for the asphalt.

b. How were these dry wells usually constructed. Can't tell by looking.
Is it likely they placed some sort of pre-cast pit in there first ?

If it has sunk a bit, how would it be repaired to bring the surface of it level again ?

Would like to learn a bit about these things before asking contractors over.

Old 01-21-07, 06:30 AM
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Are you sure it's just a "dry well", or is there a discharge pipe leading out of it. I just replaced a similar thing 2 years ago for a neighbor. He had a trench drain (about 1 foot wide by 8 inches deep) in front of his garage with a metal grate over it. It discharged into a 4" plastic corrugated pipe which was plugged with debris and roots. The runoff from his asphalt driveway would fill up the trench, and then flood his garage and sometimes his house.

I broke out the old pit and repoured it with concrete to about 1 foot by 1 foot, with the bottom sloping toward one end. I re-used his metal grate. I placed an 8 inch (yes, that's what he insisted on!) discharge pipe and ran it all the way around back of his house to a low part in the yard.

We have had torrential downpours many times since, and his garage has stayed dry.

As to your other questions: I think just removing the asphalt and leaving the gravel would be the best. It has probably been there a long time and is very compact. It sounds like it has been built up many times with more asphalt. I would bet on that instead of on the drain sinking. They can put the new asphalt on top of that base.

I would re-do the trench drain, encasing it in a concrete garage apron, and discharge the water somewhere. It's possible that your drain pipe is there now, but just clogged up with years of debris.

Any contractor you talk to should be able to give you good advise based on what he sees. Good luck.

Old 01-26-07, 12:05 AM
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I have worked on several of these same type projects during my career and most pits did have a drain leading somewhere. In the newer homes the drain led directly to the sewer system. 8 is a lot for the pit to sink and it is probably cracked as well so I would replace the pit the same way Pecos suggest.

As for the asphalt depth, in Chicago the code is 2 compressed (after it is rolled) and 1.5 for resurface. That means that an extra inch is laid to allow for rolling compression.

Asphalt is measured and bought by the ton, a ton of asphalt covers near the same area as a yard of concrete @ 4 depth = 81 sq ft, more for resurfaced areas.

You need to decide if you going to resurface or remove and pave new asphalt before you replace the pit as the resurfaced grade will be 1.5 higher, and YES the old stone can be used as a base if it is of proper depth and in good shape. Our asphalt crews would install a four inch base of crushed limestone with screenings as the base for NEW paving projects.

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