Is building possible according to this geological survey???

[Mark Beekman]

I'm looking to build a single family home (or put up a mobile home) on a flat .34 acre residential lot in PA.

Some background:

There used to be a house on the lot, built in the 1960s, that suffered settling issues due to being built on uncompacted fill. The house, and the other houses in the neighborhood, were apparently built on an old mining site from 100 years ago. There are neighboring houses on all sides of the property in question, with one next door being built in the 1990s. All neighboring houses are within 25 feet of the subject property lines.

The Township had done a geological engineering report a few years back. From the report:

"Borings and samplings taken clearly and consistently encountered construction debris, organics, cinder, grass, brick, wood, etc. to depths of 30-35 feet. Soils below the uncontrolled fill were moisture sensitive, highly compressive soils down to refusal at depths of 45-67 feet. Five borings were taken; one at each corner of the ranch structure and one was taken in the rear yard...

...The site has very extensive fill to depths of 30-35 feet. Based on IBC Section 1804, there is no presumptive load bearing value of this uncontrolled/unprepared fill material (which also contains construction debris, organics, cinders, grass, brick, wood, etc.). The bearing capacity below this fill is only 1000 PSF down to refusal at 45-67 feet."

I realize that there may not be any geological engineers here, but I figure that some of you may be familiar enough to give me a ballpark of whether building is worth exploring or not.

[Mike Wood]

@Mark Beekman There are ways to build houses on soil that has low soil bearing capacity (less than 1000 psf), some of which are not cost prohibitive.  In Louisiana, we build most of our houses using deep foundations, which generally is wood or concrete pilings driven into the ground.  For 1-2 family houses in New Orleans, we generally drive these pilings down anywhere from 20-40 ft below the surface. The house is then built on top of these pilings, and the piling carry the load, not a spread footing like a typical house.  You could also get an engineer to design a foundation to suit the site conditions, as the IRC typically requires a minimum soil bearing capacity of 1500 psf.  My concern with this would still be setting, given what the geological report stated about moisture sensitive soil.  Even if you designed an engineered foundation to account for the low soil bearing capacity, the house could still shift as the soil expanded and contracted due to the moisture content of the soil.

@Mike Reynolds gave some good guidance on the IBC code.  The IRC does not address deep foundation (i.e. pilings), but the IBC does, section 1810.

Driving piles is pretty cheap.  My guess is most of your expense will be related to documenting the piling capacity at your site. In Louisiana, the local city/parish(county) dictates the allowable pile loading capacity based on the location.