Page 6 - sfdcoronersverdict

3rd. The dip. strike of the planes of eavage of the

schist were at very unfavorable angles with reference to the

lines of pressure of the dam and very favorable for landslides
on the east wall of the site of the dam.

4th. The conglomerate upon which the western portion of the

dam was built is variable in structure, badly seamed in

several directions, and very deficient in bonding material.

Whi le it has the appearance of rock when dry, it is weak in

compressive strength: and, when saturated with water, it dis-

integrates into a slippery mass of clay, sand, small pebbles

and other included materials.

5th. Gouge materials at the contact between the two

formations were inferior in strength to either of the two

principal formations, causing a zone of weakness that can

always be expected at such contacts.
- In addition to the contact fault there is another
6th.

fault crossing the dam transversely and intersecting the

contact fault about 150 feet downstream from the toe of the

dam

7th. The dam was not carried far enough into the bedrock

and had no cutoff walls.

8th. There was no reinforcement or blanketing with

concrete at the contact between the dam and the rock abutments,

as isusual where the formations are not of the best. No

pressure grouting of the bedrock was done.

9th. The dam was not provided wi th inspection tunnels

with drainage pipes, discharging separately into the

inspection tunnels for the purpose of locating any leakage

and grouting it off if necessaryo The only drainage pipes

installed were confined to the center portion and connected

to one manifold and outlet, making it impossible to localize

leakage.

10th. The dam was built without predetermined expansion

joints. This is a debatable questions but the best practice

at present calls for their use.

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