At 100 tpd per site, cash flow after debt service cost is slightly positive. When you hit 250 tod at a site, you make a noticeable return on investment as long as you don't have high cost VC investors involved. The sweet spot begins at 500 tpd as you run full out and can absorb the cost of a indirect and maintenance overhead staff. To go much above this level, in plant handling becomes an issue which warrants automation.