Photo Nevada County OES

GRASS VALLEY, Calif. January 17, 2017 – Slope stabilization work is underway at a massive sinkhole in Grass Valley. The sinkhole appeared during the last storm behind Liberty Motors in Grass Valley and was reportedly caused by a clogged city drain pipe.

Work is now underway to mitigate the unstable sides and the area remains closed to the public.

Photo Nevada County OES.

A video by engineering firm Holdrege & Kull posted on January 12 showed the initial size. By now, the sinkhole is seven stories deep, according to Tim Kiser with the City of Grass Valley.

Today, the Nevada County BOS declared a state of emergency, Grass Valley and Truckee declared local emergencies as early as January 11.

10 replies on “Grass Valley’s “Big Dig” sinkhole now 7 stories deep – photos”

  1. This appears to be man made. Is this a spoil pile over city plumbing. Never saw red earth this thick over bedrock. Doesn’t look like tertiary river sediments generally there are layers of gravel between fine sediment. Spoil pile taller than house and trees. My guess is man made. Yes or no.

    1. It probably got into some old mine shafts up there and that’s way it opened up so big. When we did the grading work for the beer distributor up past Foster and son we broke into some big shafts up there.

  2. Most of the sink holes are from mine shafts and air holes. Empire mine has a display in the visitor’s entrance. You can clearly make a connection between sink holes and air shafts. So, you can blame it on man made, “yubanet”. I am 3rd generation Native to Nevada County and my family mined in area. Sink holes are common and so is denial to those who have no clue of area and it’s history of mining. Ask natives in area, they’ll tell you story’s of old days. The new residents of area need to see empire mine and do a little research. They will be surprised when realizing most of town is built on tunnels. Empire Mine is a great place to learn about our Mining history and where our mining tunnels ran in country.

    1. Not all sinkholes are alike. Yes, sinkholes are common in the area – however this one was caused by a failing drainage pipe. That determination was made by the City of Grass Valley and engineers. Totally agree everyone should visit the Empire Mine museum, it’s a great place to learn about the mining period. As for the several hundred miles of tunnels under Grass Valley and in the surrounding area, that’s widely known but it’s always good to remind people, thank you for that.

  3. I park there every morning and do my computer accounts. It started out pretty big. Now it is so huge. I always wonder when this is gonna happen and where. When I lived next to Mt.St Helens, I went in a lava tube 300 feet below the surface of the earth.. You just wonder when it is gonna collapse, and where next.

  4. The folks running G V dont care about our mining history or the toxins that lay just under a very thin skin that is keeping it in place .Little Wolf creek destroyed because they wouldnt listen to any of our non profit stream and land groups we are blessed to have in our county .This is gov.abuse at its best and environmental destruction at its worst. WAKE UP GRASS VALLEY CALIF get involved! !!

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