ALP Transfer Inspection Report

Animas -La Plata Project
Feb 13, 2013 Draft Transfer Inspection Report
RIDGES BASIN DAM
A. Ridges Basin Dam and Lake Nighthorse
Ridges Basin Dam is a compacted zoned earthfill embankment with a maximum height of
approximately 273 feet and a total volume of approximately 5,220,000 cy. The crest is at
elevation 6893.00 (without camber), is 30 feet wide, and is 1,633 feet long.
Ridges Basin Dam impounds Lake Nighthorse. Lake Nighthorse is an off - stream reservoir on
Basin Creek (tributary to the Animas River) in La Plata County, Colorado and stretches about 3.7
miles upstream of the embankment. The reservoir has a total drainage area of about 15.7
square miles. Filling of Lake Nighthorse is primarily accomplished by pumping from the Animas
River through Durango Pumping Plant.
The initial filling of Lake Nighthorse was completed in June 2011. Since then no additional
pumping has occurred, and various sources of loss have resulted in a less than full active
conservation pool.
TRANSFER ISSUE
STIPULATION
Reservoir water elevation is
As part of the Project transfer, Reclamation will commit to filling
below top of active
the reservoir to top of active conservation, at the government
conversation
expense, with the assistance of Association staff.
The areas adjacent to, and including Ridges Basin Dam have yet
to be designated for the purposes of public access. Reclamation
Future public access to the
shall provide signage and appropriate deterrents to clearly
dam and surrounding areas
delineate all areas determined to be closed to the public.
needs to be controlled
Spacing and placement shall be coordinated with the Association
and local law enforcement.
There is a lack of
Reclamation will use the upcoming 2013 Comprehensive Security
surveillance capability for
Review (CSR) recommendations to determine requirements for
crest and upstream dam
additional security measures project -wide.
areas
There is no helipad
Reclamation will coordinate with the Association to designate an
designation near the dam
appropriate helipad location, and provide all necessary
for emergency responders
information to local emergency management agencies.
All access points to the dam
Reclamation will provide new access controls as appropriate for
and control house need to
all points of access to the dam and control house, and
be re -keyed
appurtenances.
There is no fall prevention
installed at access portals in
Reclamation will investigate an appropriate solution.
the control house
Power and fiber optic lines
adjacent to the left
Reclamation will relocate this section of the utilities to a more
upstream abutment are
suitable location.
buried in an unstable slope
There is no means to
communicate between the
Reclamation will provide the means to communicate between
gate chamber and the
the gate chamber and control house.
control house
Transferred Works Inspection 3 Animas -La Plata Project