CT2016-2001 Approval Letter

• Contract/PO #: CT2016-2001
• Contractor Name: Tunnel Water Company
• Contract Type: Loan
• Loan Projects - Doc Type: Approval Letter

Tunnel Water Company Agenda Item 22c
September 15-17,2015 Board Meeting(Updated September 18, 2015)
Page 3 of 4
makes it very ry d iffi cult to access the tunnel for maintenance. Additionall y, the east portal's (outlet)
concrete energy attenuation structure, which has been resurfaced many times before, is heavily
spalled and near failure.
Alternative 1 - Do Nothing: This alternative was considered unacceptable as it will eventually result in
the failure of the west portal of the tunnel, rendering it unusable pending emergency repairs. A failure
of the east portal's concrete energy attenuation structure would cause re-routing of flows and
significant erosion damage, including damage to Highway 14 immediately below the east portal.
Alternative 2 - New Tunnel: This alternative was considered not feasible as there are no suitable
locations nearby and the costs and environmental permitting involved would be prohibitive.
Alternative 3 -Abandon Tunnel: This alternative was considered not feasible as the Company is
unaware of any alternate sources of water should the tunnel be abandoned. The tunnel carries a
significant amount of water that is vital to WSSC and WRCC.
Alternative 4 - Resurface Tunnel Infrastructure: Under this alternative the existing timber cribbing
and concrete lining of the west portal would be replaced like for like and the energy attenuation
structure would be patched again. This was rejected because the existing west portal's cross-section is
too small and restricted to handle mining equipment and because the steep grade makes entry and
egress difficult, particularly when performing maintenance activities. The energy attenuation structure
has been resurfaced many times already. It is heavily spalled and additional patching is not an
acceptable long-term solution.
Selected Alternative 5 - Rebuild Tunnel Infrastructure: This alternative will rebuild the west portal
and extend its length by 165 feet. The timber structures will be replaced with an 8'x8' reinforced
concrete box culvert and the grade will be reduced from 21% to 5%. Removable energy attenuation
curbs will be installed in the west portal approximately every 2.5 feet along the invert to control water
velocity while still allowing maintenance access. This work will require a new inlet structure and a
trash rack. The East Portal's concrete energy attenuation structure will be replaced with one of similar
size and construction. This Alternative meets the goals of the Company.
The costs associated with this alternative are shown in Table 2.
TABLE 2: PROJECT COST
Task COST
Design Engineering $60,000
Construction Phase 1: West Portal $670,000
Construction Phase 2: East Portal $290,000
Construction Management $50,000
Contingency $155,000
TOTAL $1,225,000
Permitting: The Project lies within the Canyon Lakes District of the Arapaho and Roosevelt National
Forest. The Company holds a 2.5 acre USDA-F5 special use permit but may also be required to obtain a
temporary construction special use permit based on the final area to be disturbed. Preparation for the
temporary permit application is underway.
Schedule: The Company opened bids on July 30 for construction on the west portal (phase 1) and
issued a Notice to Proceed in August 2015. Phase 1 Construction will occur between the 2015 and 2016
irrigation season. Construction on the east portal (phase 2) will be bid separately and occur between
the 2016 and 2017 irrigation season.