Something does not sound right, If the house behind you have been fined they have to correct the problem. You do not just get a fine and walk away. Without a picture I am assume you are going to have a bigger problem than a puddle in your lawn. What about your house?

We have reworked a terraced area. I don't know what you mean by: do all the plants above each tier need to be lifted. My DH is also an engineer and no way would he bother to work unless I got all the plants out of his way. I can't imagine you won't want to rearrange a tish anyway.

I wouldn’t add soil on top of the crown.

What are you going to use to build the retaining walls? How long is the run for that two foot drop? Got any pics? If you’re going to have French drains to manage the water at the lawn level your big task is to increase the garden drainage enough that the water quickly gets to the French drains and off your property. I’d ask my local government to reimburse my expenses from the fine they collected. They might laugh, but you don’t know until you try.

marquest, the house is set higher, so it is not affected. When the problem was first created 29-odd years ago and we complained, the village brought in a truckload of dirt and some workers. It was not enough. The storm sewer for a grouping of about 6 houses is between our house and the next neighbor's to the side. (it's the development behind us that is higher) The village said they would not raise the level of our yard higher than the top of that storm sewer. That we HAD to be lower than everyone else. Basically, "You're IT."

arcy, I don't know how else to explain it. One tier just finished stands 1 foot high. That means the area behind that tier needs to be backfilled with soil. Everything really close to that tier has been removed and will be replanted at the new higher level. But going up the slope, there are more plants whose soil height right now is a little below the height of the retaining wall. .

any chance at a couple pix?

Sounds like an individual plant by plant problem. Some will probably be ok with an extra two inches of soil on top. Is the bed planting varied or all hostas?

Here are the photos:

Below is the old terraced section. This has been in place for 15 years. There are 2 levels. You can see the newly installed french drains in the lower area.

Below: this is the end of the old terrace, lower level, and its extension into the new area. We have not decided yet if this lower one will extend further to the left.

Below is another shot of the transition zone.

Here is the main part of the new terrace: plants right near it removed. Hostas behind it may need to raised up when soil is backfilled. One of the little arborvitaes too. The evergreens are there to hopefully hide that ugly huge cable box, during the winter especially.

This photo below shows the steepness of the grade we are dealing with.

This below shows the hostas and plants above and below the upper level terrace.

zkathy, hostas are the most prominent but there are also ferns, some natives like great blue lobelia and red cardinal flower; a variety of geraniums, seed-grown heuchera villosa cultivars.

Looks like you’ve got your work cut out for the rest of the summer! Heucheras and hostas don’t like to be too deep. Don’t know about the others.