Retaining Wall for Asphalt Driveway

[infiniti007]

Hi all - wanted to get some more opinions on whether a retaining wall is required for an asphalt driveway expansion / widening I am planning. My existing driveway is maybe about 10-12 inches at its peak higher than the side yard where I am intending to have the expanded asphalt driveway. The new part of the driveway will be built up to be similar grade as the existing driveway and then pitch slightly to the left to help with water drainage.

I've had one contractor say that they would just run the asphalt to the edge of the property line (where the railroad tie and neighbor fence are) and tamp it down at a 45 degree angle. I've had another contractor suggest that I absolutely need a retaining wall on the left side and quoting nearly $5,000 for the wall alone. Price aside, just trying to see if a retaining wall is needed in this application or if there are any alternatives? Pictures below

Thanks

 

[kbeefy]

I'm no road engineer, but a retaining wall for a 12" 45* slope of compacted fill seems excessive.

I'm only posting because I have a similar situation and am interested in everyone elses opinion.
I have an existing gravel and concrete pad below grade 12" and am curious if I need a retaining wall or if I can just pack some crusher run in and call it good. It previously had a modular home on it, which has been removed and I would like to turn it into an RV pad.

 

[kbeefy]

Also, Welcome to the forum!

 

[The Cobbler]

asphalt is quite weak at the edges, especially when it's above grade . it always tends to slide away and that will develop cracks and sinking over time .
a concrete curb would be best .
also with higher petroleum costs, concrete is not as out of line as it once was. ( around here anyway) might look into a concrete extension

 

[nadogail]

If I happen to be selling Concrete Retaining Walls, you can be assured that I will recommend them highly to anyone who might be able to pay for one.

 

[cvairwerks]

How p.o.'d is your neighbor going to be with you for dumping the excess runoff into his yard? PO of my house screwed up the backyard drainage and I now have 4 yards undermining my driveway. Going to cost me a lot to fix it.

 

[240sxguy]

How p.o.'d is your neighbor going to be with you for dumping the excess runoff into his yard? PO of my house screwed up the backyard drainage and I now have 4 yards undermining my driveway. Going to cost me a lot to fix it.

Good point, I know around here if you do something that ends up flooding a neighbors yard you'll likely have to fix it.

 

[Two Speed]

How much wider where you planning on? The water drain issue is real, and looking at your photo if you build up your driveway right to the property line the water from your property is going to be draining right onto the neighbours, along with everything that flows from the sideyard will be diverted to the nieghbours, and that will be a problem for you to resolve. My neighbour ended up installing a french drain to correct his diversion. He thought he'd just let everything dump onto the sidewalk by my garage and using my driveway/sidewalk as the "drain" becuase my driveway slopes to the street. (ended up with water pooling up against my garage foundation). That song didn't play long when presented with a printout of the local bylaws pertaining to drainage.

 

[infiniti007]

Thanks for the responses so far - sounds like due to the asphalt edges being potentially compromised and the drainage issues, a retaining wall could be needed. Are there lower cost alternatives that are just as effective? It is about 30-40 ft in length. Is it just necessary to build the wall up to the same height or little higher than the driveway?

 

[wssix99]

I've had one contractor say that they would just run the asphalt to the edge of the property line (where the railroad tie and neighbor fence are) and tamp it down at a 45 degree angle.

This will work and hold up. ...just long enough for the contractor to take your money and run far away before it all crumbles.

As noted above, with your slope, you'll need a solid structure at the edge if you want this to hold up. You will also need to account for drainage and will need to do something major - more than just putting fill under the driveway. Your property looks contoured to take runoff from the back and side of your house and send it past your current driveway to the road. If you fill in and add a driveway on top, the water from your property is going to pool up along the side of your house. This will turn the side of your house into a marsh and then flow all your water to your neighbor's property.

 

[Zeke]

Does the new asphalt have to be level?

 

[reader2580]

I poured a large concrete curb along the asphalt driveway at my previous house because there is about an 8” to 12” drop on that side.

 

[infiniti007]

Does the new asphalt have to be level?

If it's not, I assume I would then need a retaining wall between the two levels of asphalt?

 

[Jeepster04]

What sort of vertical grade do you have there? It doesn't look like much.

Must the driveway be level? I'd much rather have a slope with no drop off (either a conc. wall or the 45 degree option) so people wont be getting out of a vehicle and falling off a drop off.

 

[The Cobbler]

What sort of vertical grade do you have there? It doesn't look like much.

..........

I see a lot of grade . OP states maybe 10" to 12" grade can be very deceiving

 

[CraigStu]

Which ever way you go w/ widening your driveway, I see another drainage problem. The grass behind your widened drive and next to your garage. That grass currently seems to drain Ok. But your widening project would form a wall approximately where the white downspout drain pipe is but all the way to the fence. Now, none of that water can drain toward the road. I all has to go through the fence to your neighbor's property.

 

[infiniti007]

What sort of vertical grade do you have there? It doesn't look like much.

Must the driveway be level? I'd much rather have a slope with no drop off (either a conc. wall or the 45 degree option) so people wont be getting out of a vehicle and falling off a drop off.

Do you mean building the widened driveway such that it is level where it meets the existing driveway but then pitches down gradually to grade level? The grade of the side yard is about 10-12" below the top of the existing driveway.

 

[BillK]

Might as well throw in another monkey wrench . . . . around here they are getting very picky about non permeable surfaces and runoff. Can only be a certain percentage of the lot. Do you require a permit ? Might want to look into it.

 

[neverdone]

Does your municipality have a side yard setback for impervious?

 

[kaymccampbell]

Maybe you could go with crusher run overlaying you side yard? With a bit of a compacted bevel at the edge? Here crusher run counts as permeable surface. I'd leave a 12 inch gap near the fence, so any runoff could do whatever it normally does.

 

[infiniti007]

I'm covered from a setback and permit perspective - no issues there

 

[CraigStu]

Be careful about crusher run or gravel. In Md they counted standard grey driveway gravel as impervious. I found out when needing a permit for a deck. I had graveled next to our garage to park the boat on a trailer over the winter. Oops. $260 gravel cost >$1000 to remove and replace w/ top soil.

 

[Old Moparz]

The curb is a good idea to divert the water & keep it from washing onto your neighbor's property but only if there is an existing pitch that can send the water to the street. The curb doesn't need to be hideous concrete like you see in store parking lots, it can be granite, bluestone or some other type of decorative block.

If you decide not to go with curbing there are also ways to contain & strengthen the edge of the asphalt. It can be thickened by excavating deeper at the edge & tapering the asphalt downward & installing it thicker. There's also metal edging specifically for the edge of the asphalt.

 

[infiniti007]

Thanks for all the responses and ideas. What would be a low cost effective wall option here? Concrete cinder blocks? I assume pouring a concrete curb or other type stone wall is a lot more.

 

[reader2580]

I poured my own concrete curb. It cost me about $500 15 plus years ago. I got the concrete from a local rental place that sold ready mix concrete that you haul home in a trailer. I used about a yard of concrete for a 25 to 30 foot long wall that was 8" to 10" and a similar thickness.

 

[CraigStu]

Is the fence yours or theirs. Wondering if it is yours could you put a 1x6 or 1x8 against the bottom of it to use as a form? Could blacktop be formed so you have kind of a swale along the property edge. Thinking if the blacktop has kind of a valley in it that comes back up the last foot or so as it approaches your form that could run water out to the road. I am still not sure of the best way to deal w/ drainage from next to your garage though.

 

[jonshonda]

IMHO asphalt extension should stop maybe 12" away from lot line. Dig a 12" deep trench and fill it with the same gravel they will use for the base. That will get you the drainage you need, and as long as you aren't parking right at the edge of the asphalt it should be just fine.

 

[andyvh1959]

I agree drainage needs to be considered. However that area and the back yard drains now must be planned for to provide adequate drainage after the driveway is widened. Maybe consider drain tile from the back to the front alongside the fence?

 

[BombShelter]

Most modern homes are built with a yard drainage plan, that sloped swall between the homes is it.

Over time homeowners will build fences on the line, build up plant beds or even build up for a driveway extention. This all changes the water dynamics when it hit the ground, instead of having a low spot between the homes leading to the street or alley, it goes nowhere.

If you decide to add the driveway, I'd also be adding an underground drainage system and not the cheap 4" plastic rolled piping. Currently it looks like your dumping thousands of gallons for every inch of water in that area. I'd look over code, some cities don't allow underground piping systems, or at least concentrated water flow dumping in the street, alley or sidewalk.

Even if you got a permit, I'd also look over % of yard coverage with a driveway in the code, most cities restrict how much of the property can covered, they don't want the area looking like a parking lot. I've talked with homeowners that did similar projects only to have to rip them out because they didn't meet that code.