E.B., Medford

A. Douse the cracks with vinegar; any kind will do to kill the grass and other weeds. If you do this early in the season, nipping the weeds in the bud, you can keep them away pretty much until fall. If they persist, another dousing will help. But be persistent; it is impossible to keep them away doing nothing. People with brick and block patios have similar problems, especially in the sun. Vinegar confined to under the pavement and patio will do little or no environmental harm. You can dose dilute it with water the next day.

Straight liquid bleach will also help kill the weeds, and the good thing about bleach is that it changes into a more benign element (more benign than bleach itself) when it goes into the ground.

Q. I plan to have my driveway dug out and a new one put in. What specifications should I look for?

KAREN STOLOFF, Canton

A. First of all, you may not have to dig out the old driveway, unless it is badly heaving and breaking up. If it is in fair shape, you can apply a new layer of asphalt, typically 3 to 4 inches thick. This would bring the new driveway up a few inches, so you have to be careful at the edges. Or, regrade to bring the soil up to the level of the new driveway. Or, install border timbers or other kind of edging to protect the asphalt edges and keep the driveway a little higher. But if you take out the old driveway, the ``specs'' are these: 6 inches of crushed stone to allow proper drainage under the asphalt, preventing undue cracking and heaving. If there is already crushed stone under, OK. The installer may use crushed asphalt pavement, which is fine, and a good example of intelligent recycling of an otherwise worthless product. For the asphalt, technically called bituminous concrete because it is made of stones bound together with asphalt, an installer might use 1 1/2 to 2 inches of a rough coat and 1 1/2 to 2 inches of a finish coat. Another might use 3 inches of finish. Either is acceptable.

Q. The installer of my new driveway plans to dig a dry well in the driveway with a grille on top to gather water running down the driveway. The driveway is 20 by 25 feet, and the installer plans to put in a 6-inch grille and dig down 6 inches. Is this big enough?

J.D., Brookline, Mass.

A. I frankly don't think so; that driveway is 500 square feet, pretty big for a six-inch opening, especially for a dry well that is 6 inches deep. I suggest a 12-inch grille and excavating 12 inches. Better yet, have a trench built across the driveway where you want the water to go, and make it 12 inches deep along its full length. If you build the trench, it could be 6 inches wide, but 12 inches would be better. A longer, wider grille will cost you more, but I think it is worth it.

Q. How can I clean tire marks and grease from a concrete driveway to which red coloring was mixed in the concrete before it was laid? I have tried all suggestions up to now, without success; things like Simple Green, Ajax, 409, grease eaters, etc.

B.M., California

A. There are a ton of cleaners out there, some for concrete, some for asphalt. These are two of them: Driveway Klean Strip cleaner and Spray & Wash, if you can find them. Here's another, for concrete: Make a stiff paste with 5 percent sodium hydroxide (sold in chemical supply houses) and ground limestone. Spread 1/4 to 1/2 inch thick, let stand for 24 hours, scrape off and flush.

Still another: Make a paste of 1 pound TSP (trisodium phosphorus) in 1 gallon hot water. Add powdered talc or whiting. Leave it on 24 hours, then scrape and flush.

You'll notice the recommendaiton of leaving these materials on the concrete for a day or so. It might not have to be that long, but leaving it on gives the cleaner a chance to do its job.

To remove oil: Scrape up solid stuff. Mix 1 cup Lestoil in a pail three-quarters full of warm water. Apply this solution, leave it on for several minutes, then scrub and rinse.

Q. My driveway is on hardpan, and is too long to pave with asphalt. I can't cover it with gravel or crushed stone because of the risks from winter plowing. The driveway still looks good, and stands up nicely, but it is developing pot holes about two feet in diameter and two inches deep. How can I fill those potholes?

JAMES MEADOWS, Cohasset

A. You could fill the holes with almost anything, but first you have to make the holes deeper (four inches or so) and with steep edges, so any filler that you use will stay put.

You can put in concrete, making it level with the driveway itself. The concrete will be very different in color from the driveway, but it will stay put.

Or, try soil (after all, hardpan is compacted soil), and compact it as heavily as possible. A final idea is to fill the holes with soil cement, a mixture of Portland cement and soil that hardens up nearly as hard as concrete, and as hard as hardpan. To make soil cement, fill the hole with soil, stir in cement (10 to 15 percent by volume of the soil), add water, and tamp.

You cannot practically do the concrete or soil cement in freezing weather, so fill the holes with anything until spring. As a temporary fill, crushed stone will do, without interfering with plowing.

Q. My driveway is impossible. It is only 3 1/2-car lengths and goes up to the garage at a 45-degree angle. Is there any way I can straighten that driveway out, or lessen the slope?

D.L., Randolph

A. There sure is, but you will have to sacrifice your garage. Actually, it might be worth your while to convert the garage into living space.

This is what I suggest: Rip out the driveway and excavate into the hill where the driveway goes up at such an impossible angle. You can excavate enough to make the driveway level, right up to the foundation of the house. In fact, it might be possible to cut into the foundation if it is there, and make part of the basement your garage. Or, excavate a little less and make the driveway slope considerably less. Or, excavate just enough to bring the driveway part way into the yard.

With digging out all that earth, you will have vertical sides; you will have to build a retaining wall to hold back all that earth on each side of the new driveway. It is not a good idea to make those sides gradually sloping instead of sheer, because you will get a lot of water flowing down each side onto the driveway. But, if the driveway still has a slope downward to the street, the water will flow into the street.

You could also build a stairway into one of the sheer sides to allow easier access to the house.

Q. What's the latest thinking on driveway sealer? I live in a new neighborhood, and the driveways are a year old. Several neighbors are sealing theirs. I thought I read where it is better not to as the driveway needs to ``breathe.'' What do you think?

DAN, from E-mail

A. I don't think it is a matter of breathing, but a matter of cosmetics. Driveway sealers, for asphalt driveways, are 90 to 95 percent cosmetic, and since you cannot make a silk purse out of a sow's ear, don't bother. Driveways are practical, but not pretty, and nothing will make them prettier, despite the propaganda from the sealer people. The only time you might want to use a sealer is to cover a driveway that has a lot of repaired cracks; the sealer will even everything out and will, in fact, make the crack-patched driveway look better.

Q. Do you have a formula for cleaning a driveway? Mine has mostly mildew with a little ground-in dirt and a little grease.

THANKS, Lake Jackson, Tex.

A. First off, I have to assume the driveway is concrete, not asphalt. There are a number of driveway cleaners on the market, including Savogran, Gunk, Driveway Klean Strip Cleaner, That done, treat the concrete with a solution of one part bleach and three parts water, which will take care of the mildew and the dirt. Apply this solution, let it sit for a minute or so, then rinse. This might not do much for the grease, so for that, wet the grease spots with paint thinner, then sprinkle cat litter liberally, let it sit for an hour or so, sweep it up and throw it away. A strong solution of TSP cleaner and water also will do it, in conjunction with the cat litter, which will absorb it.

Q. I have had five estimates on replacing my concrete driveway. The present one, with no gravel under it, is breaking up badly.

Two contractors suggested breaking up the concrete, and taking it away, excavating several inches, and installing crushed stone under the new concrete. Others said to take away the old concrete and pour new concrete on the ground. Some suggested 5 inches of concrete, with reinforcing mesh wire; others said 6 inches without wire. Now I'm all confused. What will work best?

JEAN WALKAUSKAS, Bradford

A. In as few words as possible: 6 inches, with mesh, on 6 inches of crushed stone is best. The old driveway broke up mainly because it was laid on the ground, providing no drainage at all. Any concrete driveway will be expensive, but I offer one more point: Install the driveway in 10- to 15-foot increments, divided by expansion joints, which will make the driveway resistant to cracking.

Q. My driveway is so big that I can't quite see resealing it in one operation, so I plan to reseal it in thirds. Would that be acceptable?

Also, my Formica countertops are sticky to the touch. How can I clean them to get rid of the stickiness?

P.S., Scituate

A. Sure, you can do the driveway in thirds; there might be a demarcation line between the spaces, but it will blend in quite well after a short time. Remember, driveway sealers are mostly cosmetic. Cosmetic or not, use a tar emulsion sealer.

For the sticky counter top, try a strong solution of Spic and Span and water, or a strong solution of baking soda and water. Don't use them together. Apply the solution, let it stand for a minute or so, wipe with the applicator cloth, then wipe dry with a dry cloth. Or, try paint thinner, or rubbing alcohol. Or try De-Solv-It, which safely removes sticky cleaning problems. If all else fails, dust the counter top lightly with a little talcum powder. The latter works for a sticky vinyl wall, so it might work for a counter top. It's worth trying, especially if everything else fails.

A final thought: The plastic might simply be wearing out.

Q. I have several sink holes in my driveway and yard. Some in the driveway are 24 inches wide, and another, in the yard, I could stick a hoe handle into it right up to the hilt. Can I fill them? If so, with what?

S.D., Woburn

A. Sink holes are simply areas where earth has settled into a void, bringing the top soil down with it. Sometimes the cause is the fill; too often old wood and other organic materials are used as fill and, when they decay and disintegrate, they create the voids. They can occur anywhere, including asphalt driveways. Despite the holes, you can be thankful that they are not bigger; some sinkholes can devour whole cars and, when that happens, the papers and TV stations get all excited and take all kinds of pictures.

Simply fill them. Fill with sand or crushed stone or earth, although sand is easiest to pour in small openings. Wait a few days, and push and pull a rake or hoe handle into it to open up any more voids that can be filled. Fill it to 6 inches from the surface, then add enough loam so you can plant grass or other plants.

Sometimes a sink hole will collapse into an abandoned cesspool. In that case, the entire space must be filled with sand; it should have been done originally.

As for the hole in the driveway, chip out enough asphalt to create vertical walls. Fill with sand or crushed stone to within 6 or so inches of the surface. Then put in cold patch, which is an asphalt concrete (Sakrete makes one) sold in hardware and building supply stores. Fill the hole halfway (work in the hottest weather you can stand so the cold patch will be more compactible), and pack it down with a tamper or your feet. Add a second layer so it comes above the surface of the driveway. Tamp, then put a piece of plywood on the patch and drive your car over it several times to press it down and compact it as best you can.

In fact, you can leave a car wheel over the patch overnight. With luck, you will compact the patch so it is level with the rest of the driveway.

Q. My new house is wonderful except for the asphalt driveway, which has hot spots that turn soft in the heat, and cause tracking of tar into the house. How can I prevent that tracking? Would sealer help?

VINCENT DePALMA, Stoneham

A. If the house is that new, get after the contractor to fix it; the driveway is defective, or at least those hot spots are. I don't think sealer would solve the problem. If you can't get the contractor to do it, try this: Sprinkle fine sand or stone dust on the hot spots and try pressing it into the tar. Do this on a hot day. What you are doing is making asphalt concrete. You might even use very finely crushed stone instead, but enough sand should be adequate. The next day, add more sand and press it in the tar until the hot spots can be walked on without tracking.

Q. Do you have a formula for cleaning a driveway? It has mostly mildew with a little ground-in dirt and a little grease.

A. W., Lake Jackson, Tex.

A. First I have to assume the driveway is concrete, and not asphalt. Mildew never seems to be a problem with asphalt. That settled, I think power washing will do a lot for all three situation (mildew, ground-in dirt, and grease).

For mildew, wash the driveway with one part bleach and five parts water. For ground-in dirt, you need scrubbing, and the bleach solution will be good enough as a wash. Wear skin and eye protection when working with bleach. Rinse with a hose. If this doesn't work, make a strong solution of TSP cleaner and water, apply this liberally, wait a few minutes but don't let it evaporate, then scrub and rinse.

For the grease, you need a degreaser, and paint thinner is as good as most. Apply the paint thinner, let it sit awhile, then scrub, and wipe up with a dry cloth. Dispose of oily cloths safely by burning them. Sometimes the paint thinner will drive the oil deeper into the concrete; if that seems likely, do this: Apply the paint thinner, then sprinkle on a lot of an absorbent (cat litter, Speedy Dry, or baking soda). After an hour or so, sweep it up and throw it away. Repeat as necessary.

Q. Last fall I had the driveway sealed. Now people who walk on the driveway are tracking marks onto the kitchen floor. The man who sealed the driveway suggested I wash it with Lestoil. Will that work? If not, what can I do?

GEORGE LEHMAN, Canton

A. Washing a driveway with Lestoil? Sounds like a pie in the sky, although it might dissolve or remove some of the sealer but I personally am skeptical. Besides, it was his sealer that failed, so he should do the cleaning. My option would be to apply another coat of sealer, this time using Jennite, which is a tar emulsion and should work well. Jennite is the original sealer, and has a good track record.

In the future, avoid sealing any driveway; sealing is 95 percent cosmetic and it is impossible to make a silk purse out of a sow's ear. In other words, it is impossible, in my opinion, to pretty-up asphalt.

Q. I am having a new asphalt driveway installed. I expected to see several inches of gravel installed before the asphalt paving was put down, to provide proper drainage under the paving. But instead I saw some grayish, dirty-looking stuff. Is that OK?

J.M., Foxborough

A. Yes, it's OK. It is crushed or ground up paving, and being mostly stones (and busted up apshalt, which is like stones) it will drain as well as crushed stone or gravel. It's another recycling technique developed by the industry, and it is a good thing, using something that otherwise would be thrown away and hazardous as a disposal item.

Q. I have a gravel driveway that constantly needs sweeping to put the wayward stones that scatter onto the lawn back in the driveway. I am thinking of bluestone or crushed stone, quarter-inch to three-eighths-inch size. Which is better?

G.P., Wellesley

A. The bluestone and crushed stone are virtually the same; both are crushed stone, although the bluestone is softer than the crushed stone, which is probably granite. I suggest crushed bluestone; being softer than granite, it will pack down better and will be less prone to scattering. The gravel you have now is round-edged natural pebbles (uncrushed), and will scatter and slew around more under tire tracks and people's feet. Crushed stone has sharp edges, making it stay where it belongs.

Another trick to keeping the stone in the driveway -- where it belongs -- is to build a border on the driveway, using pressure-treated boards flush with the ground, or any other border material, such as on-end bricks or other masonry. Then, make the driveway stone an inch or so below the top of the border.

Q. I plan to build a driveway of decorative stone, but a mason said decorative stone on a driveway is no good and won't last. Is that so, and if so, what will last?

BARRY STEARNS, Waltham

A. First we have to define our terms. Just what is decorative stone? If it is patio blocks (2-inch-thick concrete slabs in various square and rectangular shapes), they won't last on a driveway but are fair for a patio. If it is so-called paving stones (made of super-compressed concrete) in various shapes, they will last a lifetime because the concrete is compressed. If it is granite paving stones (granite cut into various shapes and 4 to 6 inches deep), they will last a millennium. If it is hard brick, set on their narrow sides, they will last 100 years and longer.

Q. My driveway was resurfaced with a 2-inch coat of asphalt some years ago. Now there are cracks up to 1 inch wide. How can I fill them?

G.P., Milton, Mass.

A. For cracks a quarter-inch and less, use an asphalt caulking, sold in cartridges for use in a caulking gun. For larger cracks, even as wide as 1 inch, use a fabric repair kit, a self-adhesive tape that will span the crack as well as fill it. One such material is Driveway Medic, made by Co-Fair Corp., 3124 West Lake Ave., Glenview, IL 60025. Co-Fair recommends that the fabric be cut 2 inches wider than the width of the crack. And, Co-Fair advises, if the cracks are wider and deeper than a half-inch, first fill them with a ``suitable filler material'' (sand or stone dust are two good choices as fillers).

Extra wide and deep cracks can be filled with cold patch, sold in hardware and building supply stores.

A sealer can be applied to the patched driveway to diguise the patchwork. While it is mostly cosmetic, the sealer also will fill hairline cracks, which are too narrow to hold any other filler.

Q. Some power steering fluid spilled on my driveway, and not only stained it, but softened it and deteriorated some of the asphalt. How can I stop that deterioration? The fluid is oily.

JERRY POWELL, Kingston

A. If the fluid is still liquidy, sprinkle an absorbant clay such as Speedy Dry or cat litter, even baking soda on the spot, letting it mound up an inch. Leave it for an hour, then sweep it up and throw it away. If it is not liquidy, apply paint thinner and then put on the absorbant material. Repeat as necessary. If the deterioration is not too deep, you can then seal the surfce (probably the whole driveway) with a driveway sealer. If that doesn't work, you may have to cut out that section of asphalt and put in a cold patch of new asphalt.

Q. My driveway slopes down toward the garage, and I have installed railroad ties across the driveway to stop cars before they run into the garage, which I do not use for cars any more. The ties have rotted out, and now I have to put something else in their place. What can I use that will last longer than the ties?

A.H., Marblehead, Mass.

A. You could use 4- by 8-inch pressure-treated timber, bolted into the asphalt. To bolt it in place, drill a hole into the timber and drive a three-quarter-inch steel reinforcing bar about 12 inches long into the asphalt. Or, buy speed bumps that can be bolted onto the asphalt. Speed bumps are not an everyday item at the lumber store. You have to send away for them. One maker is Barco Products Co. of Batavia, Ill., which makes quite a few kinds. To order, call 800-338-2697.

Q. I have a slight imperfection in my poured concrete driveway. The concrete was laid in two different slabs, creating a 2 1/4-inch dropoff where the two slabs meet. How can I turn that bump into a ramp?

BOB, from Indianapolis

A. Fixing it should be easy, I think. Buy a large pressure-treated beam, say 6 by 10 inches, and cut it at an angle, like a wedge. Stick this wedge up against that 2 1/4-inch lip. Drill holes through it and into the concrete and insert a long bolt or reinforcing bar into each hole to hold the wedge in place. Presto, a gradual ramp so your teeth won't set on edge when you drive over it. To drill through concrete, rent an impact drill; it hammers as it drills and goes through concrete as if it were butter. It would take days with a power drill.

Q. Should an asphalt driveway be sealed every year? How can I fill small cracks in my asphalt driveway?

BEN SIMON, Somerville

A. An asphalt driveway does not have to be sealed; sealer is mostly cosmetic, and while a sealer may make the driveway look nice, it is doing little else. A sealer should last 10 years or so.

Fill small cracks in a driveway with, well, a driveway crack sealer; it comes in a caulking cartidge and is easily applied, but it won't do much good if you can't get it into the crack. But cracks should be looked after, because water can get into such cracks, and if it freezes in winter, it expands, making the cracks wider. That brings us back to the sealer; a sealer will, indeed, fill very small cracks, so if you do have them, then sealing the driveway makes sense.