WSP08226

• File Number: 8276.500
• Description: Glenwood-Dotsero Springs Unit - Salinity Control Projects
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1985
• Title: Preliminary Assessment of the Salt Tolerant Emergent Plant ‎(STEP)‎ Process for the Beneficial Use and Disposal of Saline Water -- EXECUTIVE SUMMARY
• Water Supply Pro - Doc Type: Project Overview

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brine. Additional water il evaporated. and 8 acre-feet of calciu.
sulfate (EYPSU.) is produced each year. The laturated brine il
transported to final evaporation ponds where 179 acre-feet of 73~
solids is produced annually for use or disposal.

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DurinE the STEP process, the freezinE point of the Glenwood SprinE8
o 0
saline water is reduced fro. 30 F to 0 F per.ittinE operation of
at least part of the STEP process (spray evaporation ponds. etc.)
durinE the winter. Winter carryover storaEe is also provided within
the desiEn of the STEP ponds.

The STEP crop production ponds include an extensive underdrain syste.
to prevent water salinity in the root zone fro. beco.inE excessive.
In addition. all ponds are underlain with a 20 .il thick polyethylene
i.per.eable liner. A new lining technique (Pozzolan) with a 10 year
history of satisfactory perfor.ance with saline waters with salt
concentrations ranging fro. sea water to saturation is briefly
discussed. This lining technique offers the possibility of a
superior liner at lower cost.

PRELIMINARY COST ESTIMATES

All STEP process costs are reported in 1985 dollars. The cost
effectiveness of beneficial use (i2norin2 profits) and disposal of
all the Glenwood Sprin2s saline water (12,236 acre-feet per year) and
the salt it contains (310,321 tons per year) at the Mack site is $52
per ton. This aay be coapared with costs of $107 and $110 per ton
for the G and DG West Salt Creek Alternatives (January. 1983.
dollars) .

At the
represents
process.
avera2e
ton and
cost.

Mack site, the Glenwood Springs transaission pipeline
67~ of the total construction costs of the STEP
Accordingly it was deterained that the base cost (for an
existin2 2round slope of 1~) of the STEP process is $17 per
that each aile of pipeline adds 30 cents per ton to this base'

Overall.
24~ that
available

the land requirements for the STEP process are only 20 to
of evaporation ponds. so a wider variety of sites are
to reduce the length of the transmission pipeline.

For the saae quantity of water evaporated per unit tiae. STEP crop
production ponds have construction costs about 67~ that of spray
evaporation ponds and about 34~ that of evaporation ponds.

PROCESS ECONOMICS

The preceeding biological. site and engineering considerations are
consolidated and analyzed to identify determinants of perfor.ance and
cost. These determinants are quantitatively related and assembled
within a co.puter .odel utilized to assess cost-effectiveness of the
process and its sensitivity to changes in perforaance. to
construction options. and to siting alternatives. This is done to
guide future development toward cost-effective design. construction.
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