MBMG-216851

Montana Bureau of Mines and Geology

Located in Cascade County, Montana, this groundwater monitoring location is associated with a water well in the Paleozoic aquifers.

Well Construction

Depth Description
-2.5-425.0 ft 6.0 in diameter steel casing
0.0-20.0 ft 10.0 in diameter steel casing
-2.0-470.0 ft 4.0 in diameter pvc-sched40 casing
440.0-470.0 ft 4.0 in diameter factory slotted screen
Depth Lithology Description
0.0-3.0 ft unknown UNCONSOLIDATED SAND AND SILT WITH SOME GRAVEL
3.0-14.0 ft unknown GRAY AND BROWN CLAYSTONE AND MEDIUM-GRAINED SANDSTONE; LITHIFIED AT 3 1/2 FEET
14.0-15.0 ft unknown GRAY HARD CONGLOMERATE; SOME PEBBLES OF GRANITE OR GNEISS.
15.0-21.0 ft unknown GRAY CLAYSTONE AND LIGHT GRAY FINE-GRAINED SANDSTONE
21.0-30.0 ft unknown GRAY CLAYSTONE AND FINE SANDY SHALE--SHALE IS MOTTLED ORANGE LOCALLY
30.0-50.0 ft unknown GRAY SHALE AND THIN SANDSTONE
50.0-60.0 ft unknown GRAY SHALE. HARD. BREAKS TO ANGULAR CHIPS; FEW VERY FINE-GRAINED SANDSTONES (3-60 FT IS FIFTH MEMBER OF THE KOOTENAI FORMATION)
60.0-70.0 ft unknown DARK GRAY AND GRAY VERY FINE-GRAINED SANDSTONE AND HARD GRAY SILTSTONE; FEW SOFT SHALE/CLAYSTONE BEDS (<1 FT THICK); RARE CARBONACEOUS SHALE (OR BLACK CHERT) GRAINS; SOME ORANGE-YELLOW OXIDIZED SANDSTONE
94.0-96.0 ft unknown GRAY SANDY AND SILTY SHALE (60-96 FT IS FOURTH MEMBER OF THE KOOTENAI FORMATION)
96.0-102.0 ft unknown FINE AND MEDIUM-GRAINED SANDSTONE WITH DARK GRAINS ALONG LAMINATIONS; HARD SILTSTONE AND ORANGE LIMONITIC SANDSTONE
102.0-116.0 ft unknown BROWNISH REDDISH AND GRAY SILTSTONE AND SANDSTONE
116.0-162.0 ft unknown GRAY VERY FINE- MEDIUM- AND FINE-GRAINED SANDSTONE; VERY HARD PURPLISH SILTSTONE OR CHERT TAN CHERT AND BROWNISH REDDISH AND GRAY SILTSTONE; SLOW DRILLING (96-162 FT IS SUNBURST MEMBER OF THE KOOTENAI FORMATION)
162.0-173.0 ft unknown GRAY TO VERY LIGHT GRAY VERY FINE- FINE- AND SOME MEDIUM-GRAINED SANDSTONE; SOME REDDISH BROWN CLAYSTONE; FAST DRILLING
173.0-183.0 ft unknown LIGHT GRAY TO WHITE FINE- AND VERY FINE-GRAINED SANDSTONE; GRAY (10YR 5/1) CLAYSTONE AND SILTSTONE; SOME LIMONITE CEMENTED MEDIUM-GRAINED SANDSTONE AND REDDISH CLAYSTONE; SLOW DRILLING; LESS THAN 1 GPM
183.0-187.0 ft unknown LIGHT GRAY SANDSTONE AND REDDISH CLAYSTONE FAST DRILLING
187.0-197.0 ft unknown MODERATE BROWN SILTSTONE AND SANDSTONE; LIGHT GRAY FINE-GRAINED SANDSTONE; DARK GRAY SILTSTONE; SLOW DRILLING (162-197 FT IS SECOND MEMBER OF THE KOOTENAI FORMATION).
197.0-213.0 ft unknown LIGHT GRAY FINE- VERY FINE- AND MEDIUM-GRAINED SANDSTONE; SOME LIMONITE-STAINED SANDSTONE; GRAY MUD; HARD SLOW DRILLING 6-INCH INTERVALS.
213.0-223.0 ft unknown DARK GRAY CHERT; GRAYISH BROWN (2.5Y 5/2) SILTSTONE; LIGHT GRAY FINE-GRAINED SANDSTONES.
223.0-270.0 ft unknown LIGHT GRAY LIGHT BROWNISH GRAY AND PALE YELLOW FINE- AND MEDIUM-GRAINED SANDSTONE; SOME BLACK CHERT; FEW PYRITE CUBES AT 258 FT.
270.0-275.0 ft unknown DARK BLUISH GRAY (GRAY 2 4/1) SILTSTONE; LIGHT GRAY SANDSTONE WITH ABUNDANT CHIPS OF BLACK CHERT; PRODUCING 5-10 GPM WATER (197-275 CUTBANK MEMBER OF THE KOOTENAI FORMATION).
275.0-278.0 ft unknown YELLOWISH BROWN (10YR 5/4) SILTSTONE YELLOW MUD.
278.0-284.0 ft unknown BLACK SHALE GRAY SILTSTONE LIGHT REDDISH BROWN MUDSTONE; SLOW DRILLING.
284.0-285.5 ft unknown WHITE AND LIGHT GRAY MEDIUM GRAINED SANDSTONE; WELL ROUNDED QUARTZ GRAINS.
285.5-287.0 ft unknown LIGHT REDDISH BROWN SILTSTONE AND SHALE SLOW DRILLING
287.0-290.0 ft unknown LIGHT GRAY MEDIUM- AND FINE-GRAINED SANDSTONE NONCALCAREOUS.
290.0-302.0 ft unknown LIGHT REDDISH BROWN SILTSTONE AND GRAY FINE- AND VERY FINE-GRAINED SANDSTONE AND SILTSTONE.
302.0-318.0 ft unknown GRAYISH BROWN (2.5Y 5/2) MEDIUM- AND FINE-GRAINED SANDSTONE QUARTZOSE FEW CARBONACEOUS SHALE GRAINS SLIGHTLY CALCAREOUS POROUS; LOST CIRCULATION AND INCREASE IN WATER AT 309 FT.
318.0-333.0 ft unknown GRAY SILTSTONE AND SHALE
333.0-338.0 ft unknown LIGHT GRAY FINE GRAINED SANDSTONE NONCALCAREOUS HOLE MAKING ~10 GPM.
338.0-372.0 ft unknown GRAY AND LIGHT BROWN SILTSTONE AND CLAYSTONE; BROWN SANDY SILTSTONE; NONCALCAREOUS.
372.0-387.0 ft unknown GRAY (GLEY 1 6/1) SILTSTONE AND MICRITIC LIMESTONE; CALCAREOUS SILTSTONE AND SANDY SILTSTONE.
387.0-400.0 ft unknown DARK GRAY (10YR) AND GRAY (2.5Y) PYRITIC SILTSTONE; BROWN PYRITIC SILTSTONE AND GRAY LIMEY SILTSTONE.
400.0-407.0 ft unknown BROWN SHALE. GRAY PYRITIC SILTSTONE; FEW VITREOUS COAL PARTICLES; GRAY CALCAREOUS FINE-GRAINED SANDSTONE; VERY SLOW DRILLING.
407.0-422.0 ft unknown DARK GRAY (2.5Y 4/1) FINE-GRAINED SANDSTONE; CALCAREOUS; INCREASE IN WATER (275-422 FT IS THE MORRISON FORMATION).
422.0-423.0 ft unknown YELLOWISH RED (5YR 4/6) OXIDIZED BRECCIA AND YELLOWISH BROWN (10YR 5/8) FINE SANDY SILTSTONE AND WHITE AND LIGHT GRAY SILICIFIED BRECCIA; HUGE INCREASE IN WATER PRODUCING ~1000 GPM OF REDDISH BROWN WATER WATER WAS CLEANING UP; STATIC WATER LEVEL 48.5 FT
423.0-440.0 ft unknown CEMENTED ABOVE AND DRILLED OUT CEMENT; LIGHT GREY TO WHITE CRYSTALLINE LIMESTONE (SPARITE).
440.0-450.0 ft unknown TAN AND LIGHT GRAY LIMESTONE. LOCALLY VUGGY. WHITE CRINOIDS; PRODUCING ~10 GPM.
450.0-460.0 ft unknown LIGHT GREY SPARITE WATER INCREASED AT 457 FT TO 20 GPM.
460.0-465.0 ft unknown LIGHT GREY (7.5YR 7/1) MICRITE AND 2% LIGHT BROWNISH GRAY (10YR6/2) CHERT.
465.0-470.0 ft unknown LIGHT GREY (10YR 7/2) SPARITE; INCREASE TO 70 GPM AT 467 FT. INCREASE TO 200+ GPM AT 469 FT; CAN'T DRILL BEYOND 470 FT, MAKING TOO MUCH WATER FOR HAMMER TO FIRE.

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