Can't answer your question, but I'm led to believe that there may be a large footprint for the house, drive, patios, sidewalks. Now would be the time to look into what alternative materials you could use in constructing (excluding the home) for rainwater control. There are many permeable product options. I've seen many applications - they make so much sense.

It may be that the type of woods are not well suited for a large increase in runoff. In that case, it would make sense to add a rain garden to decrease the amount and rate of runoff.

Whether the woods are suited for runoff or
not didn't enter into the site planner's design.
The handbook they use is intended for urban
environments. Where I'm hoping this forum
can help me is to find resources that I
can bring to their attention that will lead
to a more nuanced design that spares both trees
and the slope in the area they were going to
clear and level and might even do something
about the invasive thorny vines that
comprise the understory.

Start by Googling "sustainable landscaping" and see where that leads you. There is a good web site on the general principles that I can't lay my hands on at the moment, perhaps later. Sustainability is a buzz word at universities and colleges that offer courses related to the landscape, if you have one of those locally that might be another resource.

In the event you haven't already...Google "Maryland rainwater management requirements" - something in all the PDF files popping up at the top of the lists might give you a hint as to necessity vs over-officiousness.

Most rainfall on urban surfaces such as roofs, driveways, roads, parking lots and patios ends up as stormwater runoff. Rainfall on natural surfaces (e.g., forests and meadows) soaks into the ground where it can replenish groundwater and recharge streams.

Its difficult to go through the process of building a house without designers, builders, site crews pushing one to compromise the desire to work with the environment. Its easier for construction to take place without those pesky trees in the way of equipment, materials and crews. Its a lot easier to not worry about compression damage to tree roots. There is a lot of money to be made removing and then selling your loam and replacing it with some nice cheap sand.

My advice would be to look long and hard for the right builder who will work with your goals. get a landscaper involved now, to work with the site planning. And be very aware that your instinct that saying "we will build a rain garden after the house" is just pushing problems off to someone down the line rather than addressing them now.

you might be interested in the "what if" thread discussion.

Here is a link that might be useful: what if

I guess it really would depend on the type of trees and the type of soil in the area. There are many bottomland woodland habitats that such as floodplains along the banks of rivers that periodically have standing water, and many species of plants that depend upon moist soil. Those types of woodlands are common here in SE Michigan (well, they were before suburban sprawl), and they contain many plants that thrive in wet environments such as skunk cabbage, ostrich, royal, and cinnamon ferns, sedges, mosses, wild iris, etc. These tend to be wet in the spring and often dry up quite a bit in the summer. If things get too dry, the plants just go dormant.

I don't think the two ideas are mutually exclusive if you have the type of trees that can tolerate some moisture, such as red maples, some of the hickories and oaks, ash, black gum, etc. You could probably just selectively remove a few trees if necessary to bring in more light if its very thick forest.

I am very busy. Just the time available to add a few thoughts. First, Denninmi's comment above is very important. Wish I had the time to describe a study I did with a major engineering firm on that subject many years ago. It was the basis of much of the drainage legislation in this country as the owner of the engineering firm was a major educator, mover and shaker in that business.

The answer to this question lies in the sophistication of the local government issuing the building permit. Is there a Board of Appeals? Has the local Building Dept. set up someone available to consult with builders? Bottom line, head for local Building Dept. and ask questions.

Many ways to meet the required codes in this matter. As already mentioned, check out new permeable outdoor stone methods available. Just installing a lawn area one inch below grade so it forms a lower but not noticeable "basin' can be a good detaining feature on soils which drain.

I was going to say the same thing as demmini but he beat me to the punch.

Thanks to everybody who replied. One of the Maryland documents contains material that supports my case for an alternative to a rain garden on my type of site.

cpacker, please share what this alternative could be.

Vegetated buffers and grass channels. If I can divert
"disconnected impervious runoff" -- i.e. my roof area --
to these, according to the document, "no large stormwater
structures need be constructed," assuming my development
meets a few other size criteria, and it appears that it
does.