136 
IOWA ACADEMY OF SCIENCE 
reasonably thick, but at most points it consists almost wholly of 
combustible matter ; and where fires have occurred the soil is shown 
to be chiefly loose rock, with neither sand nor gravel, and conse- 
quently not porous and suitable for effective filtration. At some 
points along the route clay and silt deposits are evident; but these 
materials are not suitable filtering media, for they do not permit 
percolation. In view of these facts, special provision will be neces- 
sary for proper disposal of such waste matters as may find their 
way to the surface of the ground within and near the limits of the 
right of way during construction and operation of the road; for 
without such provisions, the said wastes would inevitably be washed 
into the river in times of heavy rainfall, and, in the event of their 
containing pathogenic organisms, might lead to disastrous out- 
breaks of infective disease. The fact is, however, that the character 
of the water can be adequately safeguarded by the adoption of 
methods which will be described in detail farther on. 
“The safeguarding of the water supply during the construction 
of the proposed road is by no means a simple matter, for construc- 
tion involves the introduction of large numbers of men into the 
watershed, whose wastes must be prevented from reaching the 
river. It will be necessary to establish camps at various places, 
and these camps must be provided with water, must be drained, 
must be provided with bathing and laundry facilities and latrines, 
and in all respects must be under constant competent sanitary in- 
spection and control far more stringent than, under ordinary con- 
ditions, is necessary. It is fortunate that a number of sites for 
such camps are available, at least 500 feet away from the river, 
on benches, where the soil, largely gravel, is dry and porous, and 
hence easily drained and entirely suitable for latrines. Two camps 
may easily be established outside the watershed; one below the 
intake, and one near the power house and just over the divide, 
within the drainage area of the Snoqualmie; and between these 
two points are the several sites above mentioned, on not more than 
two of which should camps be established. 
“At the several camps the necessary latrines should be board 
outhouses placed over reasonably deep pits for the reception of the 
discharges, which, out of abundant caution, should be disinfected 
by the application of milk of lime, made from freshly slaked lime, 
and kept protected from contact with the air. This should be pre- 
pared as often as twice per week, since with age it loses in caus- 
ticity and germicidal power. As the pits become nearly filled, the 
filling should be completed with clean soil, and new ones should be 
