If in the ponding areas there is a natural drainage to one side or the other, ( ideally all to the same side).

Option 3; install a collector box beside the walk at the ponding areas connected with 2" PVC and yes there is a specific drain hub which prevents "other" occupancy.

Here is a picture - it's taken from back by the parking lot, looking down between the buildings. The dark spots on the sidewalk are where the water ponds - they're mud left over from where yesterday's rain pooled up. Unfortunately it happens on both sides of the sidewalk. Just beyond the end of the walk, down by the giant oak tree, there is a very large ponding area, and about 30 feet beyond that, the landscape drops off toward the street.

Of the two options,french drain is the more practical because those surface drains will be a maintainance nightmare keeping them from becoming clogged. Perhaps an open concrete gutter could be poured alongside the walk. If you go that route,install a redwood or asphalt expansion between new and old concrete. Would overlaying the sidewalk with brick or flagstone prevent water ponding on walk? .

Where the pond is substantially balanced a collector can be placed on both sides and interconnecting.

And yes there can be a substantial cost of annualy removing the covers, scooping the acccumulated debris into a single 5gal. bucket and replacing the box grate.

Possibly as much as as 1 and 1/2 man hrs.

As opposed to the cost of the french drain.

Something to keep in mind, you are acting on behalf of the community.

For the collector drains in the spots that pond - would we need to dig a trench and lay gravel/pipe for those to discharge on the slope down to the street? I can see that being a far more cost-effective option.

Yes, with the exception of the gravel.
Thankfully, you have a natural grade to follow.

Also, you'll need to be prudent in the removal and replacement of the sod.
Where the collectors are placed on both sides, an inexpensive sidewalk drill connected to PVC pipe does a good job.
You had also mentioned "mud". If the source of this alluvium is from other than natural occurring dust, it should also be a concern.

This post was edited by snoonyb on Tue, Feb 25, 14 at 5:21

"would we need to dig a trench and lay gravel/pipe for those to discharge on the slope down to the street?"

Yup,them gates need drain lines and when them lines clog,there is no "scooping" them clear. The solution is called Hydro-Jetting,ask a plumber what that costs and while you are asking,ask if cheap,thin pipe will resist damage by the jetter. If you are digging ditches anyhow to bury pipe,add gravel and use preforated pipe for french drains. The french drains should run to daylight. Have you noticed all the grass clippings,sticks and mud in the ponding areas after heavy rain? If that gets in the lines it will cause blockage more often than you want to deal with.

klem1
It's why "maintenance," is called that.

These collector boxes are available with screens to mitigate those issues.

Or MAYBE install shallow swales on each side of main sidewalk.

1) Use a string level to make sure you have a positive grade from one end of main walk to the other, and can outlet water at low end with no problems.

2) Grade ground to slope sides gently to bottom of swale, especially making sure side next to main sidewalk slopes gently away from sidewalk for two to three feet.

3) For the short walks coming from the units perpendicular to the main walk, you'll need to bore under them and install 3 small diameter PVC pipes in series under each. These pipes should be about 10' long.

4) Slope ground away from perpendicular walks about 3 to 4 on each side to inlet and outlets of the pipes you just installed (to keep folks from stepping into a drop off if they happened to step off the walk. Also looks better).

5) Add gravel to discharge end of pipes to prevent erosion. Could also add larger rock to inlet ends to help prevent clogging.

6) Grass the swales, or create rain gardens with appropriate plants for function, beauty and to treat runoff.

This should stop ponding in low areas unless there's an area of the walk itself that's depressed. If so, that section should be removed and relaid.

NOTE: in large storms swales may fill and top walkways temporarily, depending on number and diameter of pipes under perpendicular walk, width and depth of longitudinal swales, etc.

Are those dark spots on the sidewalk the only places you get ponds? Or is that the center spot of a much larger pond?

Bcs if it's only those small places, maybe the problem is that your sidewalk is not level, and is not elevated or graded properly. Maybe you only need to re-pour the sidewalk. Or just those sections.

But I don't really know anything. Since no one else has suggested this, maybe it's only in my brain.