Alexandria Township owners ask about active sub-slab depressurization more than you would think for a town this size.
What usually prompts the call
- A finished basement that is used as living space and has never been tested
- A test came back at or above 4.0 pCi/L on a basement or slab home
- Cracks and utility penetrations through a slab you can see daylight around
Why this comes up in Alexandria Township
Very little of Alexandria sits inside a public supply area. A well here draws from the rock at the western margin of the Newark Basin — the same rock under the slab.
Alexandria Township — the state's own numbers
38% of the 672 test results NJDEP holds for Alexandria Township were at or above the 4.0 pCi/L action level — 258 of them. That puts it in Tier 1 — high potential.
Farmsteads and 19th century village houses along the old roads, with substantial large-lot residential development from the 1980s onward.
Practicalities in Alexandria Township
Large lots with ample room around the house on most properties.
Construction permits go through Alexandria Township, and installing radon mitigation for a fee anywhere in New Jersey requires NJDEP certification.
The usual approach
The standard fix. A suction point is cut through the slab, pipe is run up through the house or along an exterior wall, and an in-line fan mounted outside conditioned space pulls soil gas from under the floor and discharges it above the roofline. Sizing follows a diagnostic reading of how permeable the fill under the slab actually is, not the square footage of the house.
Typical cost in Hunterdon County, NJ
$1,200 – $2,600 — typical range, not a quote. What your building needs can only be settled by a certified business that measures it on site.
Local experience matters here — the ground under Alexandria Township does not behave like the other end of the county.
Who is allowed to do this in New Jersey
Under N.J.A.C. 7:28-27 this is not work a general contractor may take on. It requires a business certified by NJDEP for radon mitigation, with a certified mitigation specialist directing the work. We verify that on the state register, note the date, and route accordingly — but a verified certification is a fact, not a recommendation.
Never tested, and wondering whether to?
Give us the short version and the timeline. We'll put it in front of crews who can work to it, and tell you honestly if nobody can.
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Also common in Alexandria Township
Other work in Alexandria Township
Same ground, different question.
Active sub-slab depressurization nearby
Neighbouring towns on the same ground.