2010-10-22_PERMIT FILE - M2010071 ‎(3)‎

• Permit No: M2010071
• IBM Index Class Name: PERMIT FILE
• Doc Date: 10/22/2010
• Doc Name: New Appl- Ground Water Response Study
• From: The City of Lafayette
• To: DRMS
• Media Type: D
• Archive: No

the depth to ground water from the ground surface at the Swartz Residence from
about 24 feet to 16 feet or an estimated rise to about 6 feet below the basement floor.
CTL T recommends the City place a drain (see Figure A-1 and Appendix A)
along the south side of the new reservoir and a portion of Reservoir No. 3 to reduce
the groundwater rise resulting from the construction of Reservoir No. 2 to little or
nothing. The drain would empty into Reservoir No. 1 to the north.
SITE DESCRIPTION
The reservoir complex is approximately one-half mile to three-quarters of a
mile south of Boulder Creek (Figure 1). Chain-link fence surrounds the reservoir
complex. The two existing reservoirs in the complex are lined, "mined-out" gravel
pits now used for raw water storage. The reservoirs are surrounded by compacted
earth embankments up to 15 feet tall.
The South Platte Supply Canal and Lower Boulder Ditch cross the north end of
• the complex. The Union Pacific Railroad (UPRR) borders the north and U.S. Highway
287 the east side of the complex. The City of Lafayette owns the house just north of
Reservoir No. 3. The lands south and west of the complex are cultivated fields.
The Swartz residence, a single-family residence with a full-depth basement, is
located within the region where this study shows a rise in ground water will likely
occur in response to expansion of the Reservoir Complex.
PROPOSED RESERVOIR NO.2
Reservoir No. 2 will be created by excavating (mining) the overburden
materials from a 36-acre area to the underlying bedrock. The mining depth will vary
from about 5 feet to a maximum of about 45 feet. No embankments are planned. The
proposed normal water surface elevation will be about El. 5,049.5 and the storage
capacity will be about 616 acre-feet. Reservoir side slopes of 3:1 (horizontal: vertical)
are planned. The new reservoir will be surrounded by a slurry wall from the ground
surface into the bedrock to reduce water loss from the reservoir. The City plans to
• sell the materials mined to create the new reservoir site over a several year period.
McLAUGHLIN WATER ENGINEERS, LTD. 2
GOOSE HAVEN RESERVOIR COMPLEX EXPANSION
CTL T PROJECT NO. FC04797.002-145