WSP10860

• File Number: 8274.400
• Description: Colorado River Basin Salinity Control - General Basinwide Salinity Issues - NPDES
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 4/1/1992
• Title: Colorado River Salinity Standards Compliance at The La Plata Mine - NPDES Permit NM0029505 - New Mexico
• Water Supply Pro - Doc Type: Report/Study

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Discharge of untreated mine pit waters directly downstream will
result in a maximum expected salt load of 1219 lbs per day, or
222 tons per year, Although this alternative does not meet the
no-salt-discharge objective OI the Policy, the volume of salt is,
within the 2000 lbs per day, or 350 tons per year, as provided by
waiver in ~he Policy. This is the preferred alternative for
compliance with the Policy,

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Alternatives to direct discharge of mine pit water include
reduction and elimination of salt load by reverse osmosis
treatment and by total solar evaporation, respectively. The cost
estimate for treatment of mine pit water, reducing salt load to
61 lbs per day prior to discharge, is $2008 per ton, For
evaporation, the cost is $1942 per ton to remove pit water salt,
At these cost increments, the salinity control alternatives are
uneconomic and impractical for implementation at the La Plata
Mine, According to experience of the Bureau of Reclamation, cost.
increments of generally $100 per ton or less are ...co~~~.~.!~gt_iY.e~ /1#
for implementation'.

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l Joint Evaluation of salinity control Programs in the Colorado
River Basin, Prepared by Colorado River Water Quality Office
(BOR) and USDA Salinity control Coordinating Committee.
December 1987.

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