2004-02-24_REVISION - M1977153 ‎(4)‎

• Permit No: M1977153
• IBM Index Class Name: Revision
• Doc Date: 2/24/2004
• Doc Name: Construct Slurry Wall
• From: Denver Water
• To: DRMS
• Type & Sequence: AM2
• Media Type: D
• Archive: No

Geotechnical Data Technical Memorandum
Hazeltine -Road Runners Rest II Gravel Pit Lining Project
December 2000
to be monitored for erosion, and if erosion occurs as a result of the discharge of
diverted water, a plunge pool should be constructed, or flows should be diverted
to multiple discharge points.
2.2.4 Dewatering
The Hazeltine Pit was dewatered in early 1999 and dewatering of the pit has been
continuous since that time. The contractor has excavated two dewatering trenches
in the pit bottom. One is along the toe of about the eastern 1800 feet of the south ,
slope and the other, which connects with the one along the south slope, is oriented
north-south near abort the middle of the pit. Both trenches extend about 3 to 4
feet below the floor of the pit.
Currently, the Howe-Haller Pit is being dewatered by use of pumps that channel ,
water through a flexible pipe that drains into the Bull Seep which is at the south
side of the Hazeltine Pit. The Road Runners Rest II Pit was permitted in 1979 as
a wet mining operation. Suburban Sand and Gravel applied for a change from ,
wet to dry mining in 1998. We do not lrnow what mining method is currently
used.
2.3 Water Wells
According to the application for amendment to permit #M-77-153 -Hazeltine Pit, drawdown of f
the water table due to dewatering of the Hazeltine Pit is expected to extend about 900 feet from
the perimeter of the pit. A similar water table drawdown zone of influence of 900 feet from the
perimeter of the pit is expected due to dewatering of the Road Runners Rest II Pit (application
for amendment to permit #M-79-195 -Road Runners Rest II). The estimated zone of influence
in the water table due to dewatering of the Howe-Haller Pit extends between 500 and 2000 feet

beyond the perimeter of the property (application for amendment to permit #M-78-52 - Howe- '
Haller Pit).

Twenty wells were identified within the above estimated zones of influence. The approximate
locations of domestic and irrigation wells in and near the projected limits of influence are
presented on Figure 2.1. The well owner, usage, and depths of the wells shown on Figure 2.1
are presented in Table 2.1. The well numbers listed in Table 2.1 correspond with the numbered
well identified in Figure 2.1. '

GEI Consultants, Inc. 2.4 naas8ro ~m,.~a ,