WSPC00304

• File Number: 8220.106.I
• Description: Colorado River Water Projects - Animas La Plata - Environmental Studies
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 4/15/2004
• Author: DOI-BOR
• Title: Animas La Plata Project - Environmental Commitment and Monitoring Plan
• Water Supply Pro - Doc Type: Report/Study

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a) A voidance/Minimization:
i) By Design:
(1) Ridges Basin Dam:
(a) Design specifications will require design performance of Ridges Basin Dam to
withstand a maximum credible earthquake for seismic sources in the vicinity
of the Ridges Basin Dam site,
(b) Reclamation will develop a program for filling Ridges Basin Reservoir to
reduce potential for induced seismic impacts.
(c) Reclamation will develop an engineered process plan to limit, control and
manage dam site methane gas releases during construction.
ii) General Construction:
(1) Ridges Basin Dam, Durango Pumping Plant, Inlet Conduit, Navajo Nation
Municipal Pipeline:
(a) Construction contractors of Project facilities and end-use facilities will
utilize erosion control guidelines and BMP to control soil erosion.

b) Monitoring:
i) Ridges Basin Dam and Reservoir:
(1) General Construction:
(a) The cpnstruction contractor will be required to monitor methane seepage
during dam construction. Refer to 17) Public Health and Safety (17.b) for
more information.
(2) By Operation:
(a) A facilities operation program will be developed for the operation of the
project. That program will include a monitoring plan for the shoreline of
Ridges Basin Reservoir to detect landslides and slumping. Reclamation will
provide for public notification and control public access in areas where a
high landslide and slumping potential exists.
(b) Reclamation will monitor the Ridges Basin Dam area for gas releases during
project operation.
(c) Reclamation will develop a program to reduce erosion and sedimentation
resulting from reservoir filling and drawdown rates.

8) Cultural and Paleontologic Resources - Significant Historic properties would be adversely
affected, Construction activities associated with the structural components and inundation of
Ridges Basin could disturb or destroy cultural resources eligible for inclusion in the National
Register of Historic Places (NRHP); operation and recreation activities associated with
Ridges Basin Reservoir would create potential for disturbance of cultural resources eligible
for inclusion in the NRHP; and construction disturbance and other activities associated with
the land acquisition, the potential end uses and conveyance systems would create potential
for disturbance and increased public access to cultural resources eligible for inclusion in the
NRHP. Construction activities associated with the structural components and inundation of
Ridges Basin; operation and recreation activities associated with Ridges Basin Reservoir; and

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