WSP07478

• File Number: 8272.600.60
• Description: Colorado River Basin Salinity Control Program - Basin Member State Info - Utah
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/1/1982
• Title: Salt Uptake in Natural Channels Traversing Mancos Shales in the Price River Basin - Utah
• Water Supply Pro - Doc Type: Report/Study

Site I Site 2 Site 3 (1974), a s imp Ie test was designed. Sha Ie
BurIe"Qverti- Bur ied1i"O"r izon- Burled verti- samples were obtained from exposed formations
tv .cally in the tally in the ca lly in the at four sit es within the Coal Creek drainage
o channel bottom channel bank channel bottom (Figure 3.1) :
0) 6 cm depth 3 cm depth I, cm depth 1. Macrochannel
~'18 cm depth 13 cm depth 13 cm depth 2. Middle site
29 em depth 24 cm depth 23 cm depth 3. Spring
41 em depth 36 cm depth 33 em depth 4. Lower site

r
~
I
~
r

The sensors were adapted to be monitored
wel~kly with a Yellow Springs Model 33 con-
ductivity meter.

At the beginning of each flow test,
accumulated salt (efflorescence) was esti-
mated by removing a I-em deep sample from
the channel bottom at the three soil sensor
sites. The samples were dried at l030C for
24 hours, weighed, placed in 1 liter of
distilled water, mixed for 1 minute, and
settled for 30 seconds. The condu'ctivity was
then measured.

f
,-
~
I
I
I
~
~,
I
I
r
I
r
I
I
~.

Laboratory Tests

To assist in defining in-channel salt
pickup mechanisms, laboratory studies were
proposed. The increased control over
experimental variables in the laboratory was
expected to define specific mechanisms more
clearly than was possible under field condi-
tions. The initial tests utilized a re-
circulating tilting flume charged with
sediment obtained from channel bottoms
in the Price River valley. The objective of
the tests was to develop relationships of
rates of salt dissolution versus flow.

Several problems were encountered: 1)
mass movement of the sediment, 2) nonuniform
flow, and 3) plugging of the recirculation
system. The flume tests, therefore, were
abandoned in favor of simpler sediment-jar
tests. All data recorded during these
laboratory tests are in Appendix D.

Potential salt contributions from both
suspended sediment and bed-load were ex-
amined. Nine sediment samples were obtd ined
from the macrochannel study (Figure 3.3).
Each sample was halved in the field and
removed from solution by vacuum filtering
through a Whatman CF/A 12.5 cm glass fiber
filter. One-half of the sample was placed in
500 011 of distilled water, and one-half was
air drierl. Prior to each measurement, the
saturated sample was vigorously mixed,
allowed to settle, and the conductivity was
measured. The dried samples were weighed,
sieved, and the grain size fraction calcu-
lated. The samples were then saturated with
distilled water at a 1:1 weight ratio and the
rnndltc.tivity monitored as previously de-
scribed.

r
t

,
~.
,
,
I
~
~.
I
~
l

~

To test if wetting and drying cycles
increasell salt release as sugRested by Burge

Fragments passing a 1 3/8" sieve and
retained upon a I" sieve were rinsed with
distilled water and dried at 1030C for 24
hours. The remaining portion of the four
samples were divided into six subsamples;
three for a control group and three for an
experimental group. The subsamples were
saturated with distilled water at a 1: 1
weight ratio. Periodically, the temperature
was measured, then the sample was gently
stirred; and following settling, conductivity
was measured. On days 2 and 43 from the
beginning of the laboratory test, the experi-
mental group was rinsed with distilled water
and dried at 1030C for 24 hours. After
drying, the samples were again saturated. On
day 45, the control group was rinsed with
distilled water and saturated.

To estimate the rate of salt release
from the shale samples with respect to grain
size and cyclic weathering, two tests were
conducted. For both tests, the shale samples
were separated into four size fractions by
sieving (Appendix D. Table D-4). For the
first test, six 10-gm subsamples from each
size fraction (for a total of 96 subsamples)
were obtained. The subsamples were saturated
with 20 ml of distilled water and mixed in a
Precision Scientif ie water bath and shaker
(Model #66802) at' 250C for 30 seconds,S
minutes, 30 minuteH, 8 hours, 24 hours, and
72 hours, respectively. At the end of each
time period a sample was removed, vacuum-
filtered through a Whatman GF/A glass fiber
filter, and the conductivity was measured
with a Brinkman conductivity bridge.

For the second test, 50 gms of shale
from each size fraction (for a total of 16
subsamples) were obtained. Each subsample
was saturated with 100 ml of distilled water
and placed within a Brinkmann rotoevaporator
and an auxiliary (500C) water bath, respec-
tively. The rotoevaporator was rotated
slowly for 15 minutes, after which 5 rol of
supernatant was removed and filtered through
a Whatman GF/A glass fiber filter. The
conductivity of the filtrate was measured
with a Beckman model RC-19 conductivity
bridge. A vacuum was applied to the remain-
ing sample, and the sample was rotated
rapidly for approximately 1 hour or until
camp letely dry. D is tilled wa ter (l00 m 1) was
then added, and the process was repeated an
average of four times for each subsample.
The results of these analyses are also
included in Appendix D.

21

J
J_