Thousands of tons of rock.  Truckload after truckload is brought to fill what used to be wetland.  Some problems occurred when they tried to dewater the site, and they had a good deal of difficulty finding bottom.

Wetland is not the best place to build.  Very often you have clays that will shrink in the summer and expand in the winter.  Many buildings constructed in wetlands have difficulty with doors closing properly, and some even have pipes break.  Wet basements, cracked foundations and cracked pavement is not at all uncommon.

The City of St. Helens has provided builders with permits to build homes on hydric soils.  A number of developments are now in progress on Sykes and Bachelor Flat Rd.
DSL has told complaining neighbors that they are "too busy" to check.