I've got a homebrew system (at home, I'm at work atm)
Basically it makes the colony a character with four Parameters (Ability Scores) being Economy (Con), Authority (Cha), Culture(Wis+int), Enforcement (Str+Dex)
Anyway a Colony gets Feats and Skills like a character and can make skill checks
so to Harvest Wood you use an Economy check D20+Econ mod+ Prof:Lumberjack skill
vs DC = Yeild/Labour units/Time
eg I need 200 units of lumber and have 10 workers available for 2 days 200/10/2 => 10
200 units of wood will build me say 5 huts (value 500gp) so I use another Econ check using Prof:Builder (Prof:Architect gives synergy bonus) vs
DC = 500gp/labour/time=>500/8/5 = 12 -ie it takes 8 people 5 days to build 5 huts on a skill result of 12. A failed check either means it takes longer or the houses have a flaw (maybe they leak), a successful check means they finish faster