(GP/GT) for Additional Water Supply in the Lower Rio Grande

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c. Comparative Feasibility - Technical and Economic
In this analysis of Comparative Feasibility, four different alternatives "couplings" of desalination process types to
feedwater sources, in addition to three different forms of GP/GT energy, namely E(B), E(G), and E(P) need to be
considered at the outset. These four "alternative couplings" are as follows:
Alternative
A
B
C
D
Process Type
Autodesalination using MSF (or a variation thereof)
MSF (or a variation thereof)
RO
EDR
Feedwater Sources
GP/GT brine water from deep rone
Mildly brackish groundwater from
shallow aquifers
Mildly brackish groundwater from
shallow aquifers
Mildly brackish groundwater from
shallow aquifers
The methodology required for the determination of one or more "best suited processes" for an economic conversion to
potable water for a substantial municipal supply involves a step-by-step process of elimination, with the steps being as
follows:
~ - Establish a comparative ranking of the four "alternative couplings" and three GP/GT energy forms on
the basis oftechnical feasibility, and eliminate from further consideration all "alternatives" IGP/GT forms except
those with the highest rankings.
~ - For the a1ternatives/GP/GT forms remaining after ~, establish a comparative ranking on the basis
of economic feasibility, and arrive at the "best suited processes" .
S!at1- In Section N to follow, prepare pro-forma economics for "best suited processes".
S1ml - Technical Feasibility
Process Tvoes
Alternative A - On the basis of the physical chemistry characteristics of the GP/GT brine from the deep rone with it's
very high potential for scaling, the "autodesalination" alternative is precluded from further consideration. Please refer
to Appendix G prepared by Dr. Jim McNutt.
Alternative B - Although to a much lesser extent than for Alternative A, the physical chemistry characteristics of the
brackish groundwater, specificall y the sil ica content with its high potential for scale formation, I imit the efficiency of the
MSF alternative, giving it a relatively low ranking in terms oftechnical feasibility. Statistical information regarding the
silica content (SiOJ for the Group 1-4 shallow brackish groundwater is enclosed as Table 1 of Section II in the write up
for Task No.2 - Resource Assessment.
Alternative C and D - The primary basis for a comparison of technical feasibility between EDR and RO as applied to the
Group 1-4 brackish ground waters from relatively shallow aquifers is a preliminary evaulation prepared by Mr. Gene Reahl
of lonies, Inc., and it is enclosed herein as Appendix _. Mr. Reahl was provided with a copy of Table 1 (mentioned
under Alternative B), and also with TWOB/Groundwater Data System InfreQ.Uent Constituent Reports for wells in
:::ameron and HidalW Counties. A summary of Mr. Reahl's comments regarding comparative technical feasibility is as
follows: