How do quarries maintain water levels?

[Jake]

I was joking with a friend that we should open a diving quarry where we live in SoCal. While our diving can be great, there can also be long periods where you can’t dive because of swell conditions.

That made me realize that I don’t actually know how quarries maintain their water levels. Are they generally below the line of the local water table?

Perhaps most importantly, if I rent a backhoe and spend a long weekend digging out a 200x200x30-meter hole, how long do I have to let my hose run to fill it up?

 

[Graeme Fraser]

Various geological reasons, but underground springs are quite common. Many open cast quarries and mines needed to be continually pumped or pressurised to stay dry and were allowed to flood naturally when decommissioned.

 

[Zef]

Perhaps most importantly, if I rent a backhoe and spend a long weekend digging out a 200x200x30-meter hole, how long do I have to let my hose run to fill it up?

Calculated answer depends on the water pressure/flow rate from your hose bib and the internal diameter of your hose....but in general a very long time.

-Z

 

[RyanT]

Converting to inches for imperial measurements your quarry is roughly 7920" x 7920" x 1180". That volume in cubic inches divided by 231 (cubic inches/gallon) gives you a total volume in gallons of about 322 million gallons. If your garden hose can pump 500 gallons per hour (probably a generous estimate), then it will take you 645,185 hours = 26,882 days or 73 years to fill it with your garden hose. Better get started!

 

[tbone1004]

what @Graeme Fraser said. Most are spring fed and they will eventually balance out with the aquifer pressure and "top off" as water evaporates, same way the caves do.

 

[BlueTrin]

I know that my local one: St Andrews in Kent does not have a constant water level.

Sometimes it is noticeably higher

 

[Rusty Shackleford]

It will find the level of the local water table.

 

[rhwestfall]

Converting to inches for imperial measurements your quarry is roughly 7920" x 7920" x 1180". That volume in cubic inches divided by 231 (cubic inches/gallon) gives you a total volume in gallons of about 322 million gallons. If your garden hose can pump 500 gallons per hour (probably a generous estimate), then it will take you 645,185 hours = 26,882 days or 73 years to fill it with your garden hose. Better get started!

And, seeing that 300 gph is likely more close to reality (60%), coupled with soil absorption, and evaporation, and discounting you might hit groundwater, it would likely 50% more time than that.

I can only imagine your water bill (and hope you don't pay sewer rents on that too)....

 

[Steve_C]

Quarries I have seen involved removing stone from a rocky area. So the sides and the bottom may be all or mostly all rock. So the only loss of water is evaporation or overflow. If you just dig a hole the bottom and sides will be porus and you will lose lots of water seeping into the surrounding area.

 

[Rusty Shackleford]

A quarry is a window into the groundwater. Stop thinking of it like a lake or pond.

The rock is fissured and porous from blasting. There is a high degree of interaction with groundwater. This is why most maintain the same temp as the local groundwater at depth.