Following up some posts from further back up the thread, I looked for 'Water charity' who Mummy had mentioned as having a model very like the one for Archwell. I am assuming that the organisation Mummy meant was 'charity: water' - correct me please if I'm wrong. That was interesting because it brought up the Charity Navigator site which seems to aim to appraise how charities work and how well they are doing at a range of things. Here is the entry for charity: water, for example
www.charitynavigator.org/index.cfm?bay=search.summary&orgid=12548
Looking up Archwell on the site, you get this entry
www.charitynavigator.org/ein/852213963
Lots that they can't score yet, which is understandable as it's pretty new. I note though that at one point it says:
The IRS NTEE classification code is T30,Public Foundationswithin the Philanthropy, Voluntarism and Grantmaking Foundations category.
That suggests it's philanthropic and that they'll endow it with their own money. But further down under the Business Master File heading you get:
Foundation Status:
Organization which receives a substantial part of its support from a governmental unit or the general public 170(b)(1)(A)(vi) (BMF foundation code: 15)
That suggests it's going to be public donations or government grants that will make up the money. 
So it's hard to be clear on what the model is. But it will be interesting to see what sites like Charity Navigator can show about Archwell when it's been operating for longer. At the moment its merits and activities are largely self-proclaimed.