Your understanding is on track, but not complete. Snowshoe's plan was to build another treatment plant at the bottom for the Hawthorne subdivision only; not to treat the mountain. It was a small waste load allocation. I know this is going to sound ridiculous, but this is true: Snowshoe, daily, trucks raw sewage from Hawthorne at the bottom, up the mountain, and pumps it into a manhole of the mountain's sewage system. So there is no doubt Snowshoe has problems.
Anyway, Snowshoe withdrew their application for this smaller plant. Pressure from other developers was a factor.
Many septic systems are better than one for the unique geography and economics of this area, in my opinion. The West Virginia Rivers Coalition recommends the use (page 29)
of "cluster" systems for "small communities" (such as in the Slatyfork area). These employ individual septic tanks but fewer treatment/leach fields; i.e. many tanks go to one field.
This is better because in leach fields, effluent is dissipated into the soil over a large area. The amount of effluent for each treatment field would be far less than the centralized plan's allocation of 1.5 million gallons per day. Far less. Moreover, soil is a better natural filtration mechanism for effluent than is simply piping it all into a river. A very precious river, the Elk, I might add.
Also, having many points (i.e. septic tanks) is better than having one point for this situation. Septic tanks are very reliable, and when one has a problem, it won't bring the whole "system" down. A failure of the centralized plant and/or its miles-long pipe would be major, possibly catastrophic.
The cluster approach also puts the financial burden where it belongs: on the homeowner/association.
Finally, the utilization of immersed membranes
could retrofit Snowshoe's existing system specifically and get them back to compliance with room to grow. Other ski resorts have in fact done this.
So that's what we need. For Snowshoe to take their system to the "next level," and for Slatyfork's future development to embrace cluster systems. This is the best way to preserve the valley, the rivers/forks, and distribute the bill.
Thanks for asking, I'm glad you did. :-)