Radon testing — 48 hours of hourly data, not a charcoal guess.
Eden Prairie sits inside EPA Radon Zone 1. Local averages run 4.5–6.2 pCi/L — above the 4.0 action threshold. We deploy a continuous radon monitor for 48 hours and deliver an hourly graph with weather correlation, not a single number.
Zone 1 geology, sealed-slab homes.
Hennepin County is EPA Radon Zone 1 — the highest-risk classification. Glacial till and fractured bedrock produce strong soil-gas radon. Tightly weatherized premium homes in Bearpath, Cedar Forest, Hennepin Village, and the Mitchell Lake area concentrate it indoors. Sealed slab construction, dense insulation, and conditioned basements keep gas in. We have measured properties exceeding 12 pCi/L on hourly peaks — three times the EPA action threshold.
Six readings that change the recommendation.
A continuous monitor records hourly values, temperature, humidity, and pressure. These six patterns drive the post-test recommendation — and they are invisible to a single-average charcoal kit.
Sustained > 4.0 pCi/L
48-hour average above the EPA action threshold. Mitigation recommendation. Most common Eden Prairie outcome on basement testing.
Spike pattern > 12 pCi/L
Hourly peaks 3× the threshold. Often correlate with barometric drops or HVAC cycling. Strong mitigation case even when average is borderline.
Slab penetration leakage
Sump pits, plumbing penetrations, and slab cracks act as soil-gas pathways. Sealing alone rarely solves it — but documents the entry route.
Pressure-driven swing
Radon climbs when outdoor barometric pressure falls. Continuous data shows this clearly; charcoal averaging hides it.
Borderline 2.0–4.0 pCi/L
Below action threshold but above EPA's "consider mitigation" floor. Re-test in winter (closed-house season) before final decision.
Existing system underperforming
Mitigation already installed but post-test still elevated. Fan failure, blockage, or under-spec design. Re-commission required.
Where the readings tend to land.
Field-aggregated readings by Eden Prairie subdivision. Use as orientation only — your home's reading depends on construction, ventilation, and weather during the test.
| Neighborhood | Build era | Typical 48-hr average | Risk |
|---|---|---|---|
| Bearpath | 1992–2010 | 5.5–9.0 pCi/L (sealed slabs) | High |
| Hennepin Village | 1998–2008 | 4.5–7.5 pCi/L | High |
| Cedar Forest | 1985–2005 | 4.0–6.5 pCi/L | Medium |
| Mitchell Lake area | 1972–1990 | 3.5–5.5 pCi/L | Medium |
| Round Lake area | 1968–1978 | 2.8–4.5 pCi/L (leakier envelopes) | Medium |
| Eden Prairie Center area | 1975–1990 | 3.0–5.0 pCi/L | Medium |
Three steps. Certified result on retrieval day.
Place the continuous monitor
Lowest livable level, away from exterior walls and HVAC supply, at breathing height. Closed-house conditions confirmed with the seller. Often coordinated with the home inspection appointment.
48 hours of hourly data
Continuous radon monitor logs hourly pCi/L plus temperature, humidity, and barometric pressure. Tampering and door-open events are flagged on the log.
Certified result + recommendation
Retrieval, hourly graph, weather-correlated narrative, and clear recommendation: pass, mitigate, or re-test. Integrated into the inspection report your agent uses for negotiation.
Add radon testing to a home inspection — or book it standalone.
Two-minute quote. Continuous monitor. Hourly graph.