Cecil I'm going to guess that your talking about Thornton quarry off of 80/294.
I've never seen water in it, but here is something I've found online, so it does leak and use big pumps.
It is 1.5 miles (2.5 km) long, 0.5 miles (1 km) wide, and 400 feet (125 m) deep
'The quarry has to be pumped dry because groundwater runs into the quarry through cracks in the perimeter walls. The northern pit is being deepened the fastest. When finished, it will be sealed off from the southern quarry. Then it will be used as a retention basin for the Metropolitan Sanitary District's Tunnel and Reservoir System, more popularly known as "Deep Tunnel." '
Matt
