REV92756

• Permit No: M1985029
• IBM Index Class Name: Revision
• Doc Date: 6/8/1990
• Doc Name: RESPONSE TO ADEQUACY LETTERS ALMA PLACER AMENDMENT NO 1 FN M-85-029 PURSUANT TO THE MLRB PRE HEARING
• From: LAW OFFICES OF J KEMPER WILL
• To: MLRD
• Type & Sequence: AM3
• Media Type: D
• Archive: No

combination of these two soils was noted. Standard Proctor tests
the two soil samples. The bulk of 'ire embankment is the sandy-sil
which has an optimum moisture content of 7.8X and a maximum dry de
133.5 pounds per cubic foot. The Eine soil, which was quite limit
extent, had an optimum moisture content of 19.4X and a maximum dry
109.5 pounds per cubic Eoot. It is not anticipated that signiEica
of this clayey soil will be found on the project site. The SW-SM
more representative of what is found on site, although a higher cl
is typically found and reflected in the sample that was tested.
In-place testing of the compacted embankment material has reveale
125 to 135 pounds per cubic foot and about 6X moisture content.
to 100X of the standard Proctor density, which is in accordance w
geotechnical construction. Although the embankment may utilize s
of the historic berm as a Foundation, the density found in the hi
was also in the vicinity of 135 pounds per cubic foot. This indi
resulting compacted embankment can be considered a well construct
structure. The embankment can be generally classified as a homog
embankment rather than a zoned dam. For this classification it i
for some seepage to appear in the downstream face of the dam duri
state high water level conditions. As long as no piping (washing
out of the dam) occurs, such seepage is a common, expected situat
not endanger the structure.
• flLbank~ent Slope Design
As shown on Plate No. lA, the revised embankment is called for to
slope upstream and downstream, a 15 foot wide crest, and a maximu
approximately 20 feet above the downstream toe of the embankment.
structural height of the dam will be significantly less since not
rises significantly and probably is on the order of 10 to 14 feet
center line of the embankment. The embankments were laid out acc
standardized slopes presented in the Bureau of Reclamation's Desi
Dams, a standard reference text for small earth embankments. Thr
slopes may actually be conservative, since 2.5 or 2:1 slopes woul
those accepted guidelines. However, it was decided that conserva
preferred. Since standard, commonly accepted embankment slopes a
in accord he`nsite materials Found at the Alma Placer
s ability anal sis has not been performed. A stability analysis
~-
only performed when an aftempf~s made to optimize the embankment
steeper slopes than those recommended by the guidelines noted abo
• Pond Capacity
+e re run on
:y material,
laity of
~d in
density of
it amounts
:oil is much
iv content
values of
is is 95X
h good
ie portions
oric berm
tea the
reliable
eous
customary
steady-
f material
n that does
ave a 3:1
height of
The
al ground
t the
ding to the
be within
sm was
being used
oject,~
pically is
nd utilize
It is anticipated that the bottom of the ponds will be enlarged s mewhat
upslope of the embankments. At this time, estimate that the m ximum depth
of storage water will be on the order of feet and the maximum urface area
will encompass an area 800 feet long by 200 eat wide.
2