Oil Tank Sweep in Philadelphia

The survey covers the ground around the property where a tank would plausibly sit: yards, side paths, driveways, under paved areas and against the walls where a fill line would have run. It is combined with a walk of the building looking for the physical traces, meaning fill pipes, vent stubs, capped supply lines in a basement and patched brickwork where a line was removed.

Ground penetrating radar is the more accurate method for locating buried tanks. A magnetometer or metal detector finds ferrous metal, which in a Philadelphia rear yard also means old pipe, rebar, buried fencing and a century of discarded iron. Radar reads the shape of what is down there rather than just the presence of metal.

Heating oil tanks were standard in properties built between the 1920s and the 1960s, which is most of the rowhouse and twin stock across the Northeast, Olney, Germantown, West Philadelphia and the river wards. When those houses converted to gas, a large share of the tanks were simply left in place and the line was cut.

The result is a city where the absence of a visible tank tells you very little. Rear yards have been concreted, driveways poured and extensions built over the exact spots where tanks sat, and the paperwork from a 1988 conversion does not exist.

A clean sweep is meaningful evidence that no tank is present in the areas surveyed. It is not a guarantee, and anyone selling it as one is overselling it. Radar cannot see reliably through heavily reinforced concrete, and it does not read what is under a building footprint or beyond the surveyed area.

It also says nothing about contamination. A tank that was removed properly in 1995 and a tank that was removed while leaking both leave no tank behind. Where there is evidence a tank was once present, the useful follow-up is soil sampling, not a second sweep.

The sweep belongs in the inspection window, alongside the general inspection, because that is the period in which the finding can still change the deal. A tank found before closing is a negotiation. The same tank found after closing is your tank and your cost.

If a sweep does find something, the sequence is to establish what it is, then decide between removal and a documented closure in place, and to price soil sampling into whichever you choose.