WSP11823

• File Number: 8281.400
• Description: Colorado River Studies and Investigations -- Colorado River Depletion Projections
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/25/1955
• Title: Report on Depletion of Surface Water Supplied of Colorado West of Continental Divide
• Water Supply Pro - Doc Type: Report/Study

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DEPLETION OF SURFACE WATER SUPPLIES

About 500,000 tons of oil shale have been mined during the period
of investigation, taking advantage of the fact that the rich beds are
. exposed along the face of the cliffs several thousand feet f,lbove the
. level of Colorado River. In general, the mining process developed
here consists of driving a. series of headings, each 60 feet in width by
about 40 feet in height, with cross connections so as to leave a suc-
.cession of pillars 60 feet square with 60 feet clear space between them.
. Alternate rows of pillars are staggered to provide better support for
the roof and freer access to all parts of the mine. The next step has
:been to remove about 35 feet more in depth by benching operations.
,The blasted material is loaded by power shovels into large trucks and
,hauled outside to the crushing plant. More efficient means may be
,developed for mining the oil shale, but it has been demonstrated that
,this can be done safely and economically and at any desired rate of
production.
When the oil shale is brought out of the mine it is nothing but
broken rock impregnated with organic matter. This rock must be
crushed to suitable sizes before it can be started through the refining
process. The crushing plants for large-scale operations would probably
be located close to the openings of the mines.
. The first step in the refining operation is known as "retorting" and
Consists essentially in driving off the volatile matter with heat under
controlled conditions, the heat being supplied by burning the oil
ghale itself. Various types of.retorts have been used in the test
operations and the one now under test approaches the size which
clould be used commercially. Such retorts would naturally be located
riear the mine headings and just fa,r enough in elevation below the
crushing plants to permit gravity feed. .
i Sha,le oil is somewha,t similar to very viscous and impure crude oil
llind it could not be tmnsported more than a few miles economically.
Refining of the shale oil could be limited locally to reducing the
viscosity enough for pipeline transportation, or complete refining'
C9uld be undertaken to produce ga,soline and all other products
cllstomarily obtained from natural petroleum. Neither is proba,ble;
it' is the present belief of those best informed that gas oil would be
produced locally and that this would be carried through pipelines to
existing refineries on the Pa,cific coast or elsewhere close to the con-
s1.lming ma,rket.
: Should the rate of production of shale oil reach 1 million barrels
per day, the spent shale from the retorts would occupy a space .of
about 300,000 acre-feet in each. year. Fortunately, physical condi-
tions a,re favorable to the disposal of such wastes. The richest de-
posits are about 3,000 feet above the elevation of Oolomdo River
from which deep tributary canyons extend back into the plateau.
Many millions of acre-feet of storage capacity are thus locally avail-
able for the accumulation of wastes; eventually, however, it would be
nepessary to dispose of the spent shale by backfiling worked-out
portions of the mines.
,!\. large volume of gas would be produced at the oil shale retorts.
This gas would have a heat value of only about 10 percent of that of
natural gas and thus could not economically be transported any great
distance. However, it could be used advantageously as fuel in refining
oPlirations and for the prod1.lction of power at plants in the valley
of :Colorado River adjacent to the oil shale deposits. Other gas

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