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

m-31
TASK mc
PROCESS(FS) BEST SUITED TO EFFICIENT RECOVERY AND CONVERSION
TO POT ABLE WATER
As discussed in Section rnA, "the best suited" process(es), so to speak, for the efficient recovery and
conversion to potable water from brackish water "varying from mildly to very brackish" will fall into one
of three process types, specifically the following:
1. Electrodialysis Reversal (EDR)
2. Reverse Osmosis (RO)
3. Multistage Flash Evaporation and major variations (MSF)
The procedure involved in making a decision among the EDR, RO, and MSF alternatives for the purpose
of incorporating one or more of them into the design and implementation of a GP/GT powered
desalination plant of sufficient size and economy to provide a total or supplementary supply of potable
water to a municipality or region is iterative and requires a thorough evaluation of:
(a)
(b)
(c)
the availability and chemical composition of nearby feedwater source(s),
the availability and characteristics of significant quantities of GP/GT energy, and
comparative feasibility, technical and economic.
These evaluations are presented as follows:
A. Availability and Chemical Composition of Nearby Feedwater Source(s)
A substantial amount of information regarding the availability and chemical composition of both the deep
GP/GT fluids and the relatively shallow aquifer systems is presented in the write up on Task n -
Resource Assessment of this Report. As regards co-location between the deep GP/GT zones and the
shallow aquifer systems, a comparison of Figure II entitled Reservoir Area Location Map (taken from
Section I of the write up) and Figure 5 entitled Approximate Productive Areas of the Major Sources of
Ground Water in the Lower Rio Grande valley (taken from Section II of the write up) indicates that, for
the most part, the locations of these two resources coincide horizontally, and that only in that portion of
Hidalgo County to the north and east of McAllen is there an area which is probably underlain by the deep
GP/FI fluids, but not a productive zone of shallow ground water with relatively low salinity levels.
Based on a review of the information in the write up on Task II and the co-locations findings described
above, the results of this facet of the evaluation are summarized as follows:
1. Substantial portions of Hidalgo County and the western part of Cameron County are
underlain by sufficiently large quantities of mildly to moderately brackish shallow ground
water to justify their use via desalination as major sources of potable water supply.