Typically you don't want to distrupt the sub-surface at all because of the great possibility for weed-seed to germinate. It is much easier to create a native area without disturbing the sub-surface than it is to disrupt the sub-surface and fight off countless varieties of different weeds as a result.
Establishing native areas that look and function as they should is very difficult. Fescues are very slow to germinate but do very well with their high tolerance to drought, heat, compaction, acidic soils and insects. Native areas have been and continue to be established on river banks, rock outcropping areas and large hill-sides. Once established from seed, these areas can be thinned out by scalping the grass down to about 1 1/2" or so a few times a year for several years. There is a post-emergent herbicide available called Sethoxydim which can be used to eradicate any and all unwanted grasses contaminating the area. For the broad leaf weeds there is a post-emergent called Speedzone, among many others. These herbicides are best applied on warmer, dry days and preferably after the area has been scalped down.
Watering these areas, lightly, during establishment is important. However, if the watering continues after establishment, the area will become overgrown with thick and heavy grass and weed varieties. Fertilizer is unnecessary but some Supers will add some to the mix if using a hydro-seeder.
Establishing native areas and getting them to look and play as they should requires time, cultural/chemical inputs and perhaps most importantly, patience from the membership.