Heavy Rain On New Lawn

After more than a month without and measurable rain, I was beginning to think I could ignore the possibility of rain in my new lawn plans.  Silly me...

I got the new lawn soil leveled and planted in the front yard in plenty of time for the soil to settle and the new grass to emerge and set down roots.  The back yard waited.  I got the back leveled and seeded about 10 days ago.  The grass barely emerged when we finally got some rain.  And of course, not just some rain, but a lot of it.  We have had 3.75" so far.

That left me 3 concerns for the front yard.

First, would serious heavy rain overflow the drainage easement and wash some of my new soil away at the edge?  Second, would the heavy rain wash some of the new grass away and/or create runoff ditches?  Third, would I discover new places of standing water (part of what my soil-raising efforts were intended to stop)?

The first is uncertain.  I can't see any drainage edge erosion, but I can't get too close to it to be sure.  The new soil is too soft to walk on to go investigate.

The second worked fine.  There was a full day of light drizzle and that settled the soil a bit, and the soil was so dry it soaked up almost all the rain.  The grass seems to have stayed in place.

The third isn't so good.  I have a 4'x10' standing puddle in the front of the lawn.  OK, there is supposed to be a "swale" there ("a slight depression for directing water runoff", in my case to storm drains at either side of the front of the yard).  But it ISN'T supposed to have a low spot that holds water. 

It wasn't obvious by eyeballing the new soil level, but water never lies.  There is a low spot that won't drain in either direction.  So I need some more soil to add there.  I don't need much; a cubic yard (cubic meter) should do fine.  I just need the rain to flow off toward either drain.  It could be worse; my adjacent upstreet neighbor has an actual concrete channel for a swale (makes for awkward mowing, it keeps filling with dirt and debris, and it is ugly).

The back yard did not fare so well with the rain.  I planted the grass seed there 8 days ago and it was barely up when the rains hit.  The day before the rains, there was a uniform fuzz of new grass.  Today, there are large bare spots and a few channels 2" deep where the rainfall flowed downslope.  I'm going to have to relevel that and plant new seed.  Fortunately, a local garden expert addressed that very question online Saturday and said there was still time to plant new grass seed in a week after the soil dries out a bit.  Of course, that's assuming we don't get another hard rain in a week (none forecast though).

Well, nothing is ever guaranteed when planting anything.  Sometimes, you have to do it again.  At least I'm not depending on grass as food, LOL!  If I was a cow, this would be a lot more serious.