Two giant anaerobic digesters shaped like Faberge eggs have for years served as landmarks for commuters traveling on Interstate-695 east of downtown Baltimore. And cranes, recently removed, signaled the location of one of the latest projects in a years-long, $1.6-billion construction program to upgrade the 100-year-old Back River Wastewater Treatment Plant. “You probably won’t see a collection of this many ‘sticks’ anywhere else in the city,” Shane Lippert noted back in October.