Radon Testing and Mitigation in Nine Mile Falls

Nine Mile Falls sits in the Spokane River canyon, on flood gravel with granite, basalt and lake clay in the hills around it. ZIP 99026 splits between two counties: in 2020, 61.6% of its residents lived in Stevens County, mostly in Suncrest. In the census tract covering most of the ZIP, just over half of reported radon tests reached 4.0 pCi/L.

Or call (509) 278-2215

48-hour test from $195 · Systems from $1,295 · Post-mitigation test included

How it works in Nine Mile Falls

1. STEP 1
   Test

   A 48-hour continuous monitor in your lowest living level, under closed-house conditions. Report the same day it comes out.

2. STEP 2
   Look and quote

   We check the foundation, run a suction test and plan the pipe route for Nine Mile Falls winters. You get a fixed price in writing.

3. STEP 3
   Install

   Most systems take one day: suction point, sealing, fan, manometer and the electrical permit.

4. STEP 4
   Re-test

   A post-mitigation test at least 24 hours after the fan starts shows the new number. The guarantee is below 4.0 pCi/L.

Radon mitigation cost in Nine Mile Falls

Two utilities serve this area, Avista and Inland Power, and which one bills you depends on the address, so running costs differ. Wells add a second check: if the house draws from a private well, a water test belongs next to the air test. Crawl spaces and mobile homes need a membrane, which puts them higher on the price list.

Starting prices include the electrical permit and the post-mitigation test. Bold: systems common in Nine Mile Falls homes. Estimate your system →

for a typical 60-watt fan running around the clock, depending on which utility serves your address. Energy charge only, at 2026 residential rates.

A 20-watt fan costs about a third of that, a 90-watt fan half again as much.

Permits and local rules in Nine Mile Falls

Nine Mile Falls at a glance

Area figures describe the neighborhood, not your home. Only a test tells you your number. Sources are listed at the end of this page.

Flood gravel in the canyon, granite in the hills

Here the Spokane River runs in the main channel of the Missoula floods, several hundred feet deep and apparently filled entirely with flood gravel: boulders, cobbles and coarse sand of granitic and metamorphic rock. The western arm of the Spokane Valley–Rathdrum Prairie aquifer ends about a mile south of Nine Mile Dam, and its water rises back into the reservoir above the dam.

The bedrock around it is mixed. State mappers found Cretaceous biotite granite and a second granite they consider most likely the same age as the Mount Spokane granite, along with Columbia River basalt and Latah Formation silt and clay. In the northeast part of the map area, glacial Lake Columbia lakebeds sit under a cap of flood sand. The U.S. Geological Survey links most of Washington's uranium occurrences to granitic and metamorphic rock north and northwest of Spokane.

In 1993 USGS expected homes in most valleys north and northwest of Spokane to average above 4 pCi/L. Washington's test records point the same way: in the census tract that covers most of ZIP 99026, on the Stevens County side, 51.7% of reported tests reached 4.0 pCi/L or more. That figure rests on roughly 60 tests, so read it as a signal, not a forecast for any one house.

average indoor level USGS expected in homes of most valleys north and northwest of Spokane (1993)⁸

Nine Mile Falls questions