36 BULLETIN 155, U. S. DEPARTMENT OF AGRICULTURE. 
At one point some distance below the intake where uncovered for 
repairs, the staves of the lower half of the pipe were found to be de- 
cayed toa mere shell. The 4-inch spacing of bands indicated a fairly 
good internal pressure. The backfill was stony. Near-the’ dam, 
where the pressure was not more than 10 or 15 feet, the staves were 
badly decayed, and it is probable that much of the pipe was in poor 
condition at this time. On a bridge where it had always been fully ~ 
exposed there was no appreciable decay of the staves other than at 
leaky joints, and the same was true along the top of the pipe where 
exposed or covered with only an inch or two of coarse soil, which 
permitted it to remain dry. 
R. M. Hosea, chief engineer of the Colorado Fuel & Iron Co., 
writes as follows about a pipe several miles long: 
The oldest line we have—28 inches in diameter—was built in 1900. -For 
five years past it has been repaired in places by inserting new staves wkere 
old ones were badly rotted on the exterior. This allows bands to sink into 
soft wood and staves to leak. The rot progresses until one-half to three-fourths 
of the wood is rotted. It occurs in patches, or on certain staves their full 
length, according to amount of pitch in the wood, or some variation in its quality. 
This pipe was of Texas pine staves. I should add also that the bands become 
rapidly corroded where leaks have formed and ground is moist, and I should 
doubt a life of 20 years for this line even if repairs are kept as above indicated, 
where we are constantly putting in new fir staves and some new bands. 
This pipe is laid in fine adobe soil and covered to a depth of 2 feet 
or more. 
By the side of the pipe just mentioned, and under the same condi- 
tions, a 48-inch fir pipe was laid in November and December, 1906. 
Mr. Hosea says that in three years it was decayed sufficiently to cause 
leaks. When inspected in October, 1913, it showed serious decay, 
and was being incased with reinforced concrete. This pipe was 
‘covered with the adobe soil from 18 inches to 2 feet deep, and where 
examined was under a head of perhaps 30 feet or more. In most 
instances the decay extended half way through the staves. Sdéme- 
times a sound stave occurred, while those on each side of it might be 
badly rotted, The bands were in good condition and only slightly 
corroded. Twenty-five other pipe lines built by this company about 
the same time as this one have also been incased with concrete, decay 
in the case of each having made more or less progress. 
Under date of May 15, 1912, L. B. Youngs, water superintendent 
of Seattle, Wash., writes as follows: 
The first wood pipe that we installed in this city was put in 12 years ago, 
and was made out of our native timber here, known as Douglas fir. * * * 
In clay soils the pipe lasts fairly well, and I would place its life at from 12 
to 20 years; in sandy and gravelly soils I would place its life at from 7 to 12 
years. However, in the case of large pipe with individual bands the cost of 
reinstallation would be the cost of the wooden part of the pipe only, as we 
find the iron bands to be in good condition after 10 to 12 years’ service, so that 
they could be used for the new wood. 
