Rebuilt Twin City Lock Now Requires 
Further Reconstruction 
Reference has been made that the reconstruction 
of the lock in the Twin City dam, following its 
failure, was completed in September, 1930, this com- 
pletion date being nine months after the report of 
the Board of Engineers dated December 16, 1929 
(Doc. 290) had recommended the 9-foot channel. 
It would seem a reasonable expectation that this new 
lock built following such report would meet satis- 
factorily, not only the existing but the then proposed 
future requirements; that it was intended so to do is 
evident from the latter part of the previous quotation 
from page 94, document 137. However, this con- 
dition will not be met, as is evident by a later refer- 
ence on the same page, where it is stated: 
"The land wall of this lock was built to form the 
center wall of twin locks. The lower approach to 
this lock is unsatisfactory because the guide wall 
was designed for the auxiliary of twin locks. This 
condition could be remedied by building another 
guide wall on the land side and by excavation. 
However, the single small lock is also inadequate in 
that it causes considerable delay to the passage of 
larger tows." 
This frank admission that the work just com- 
pleted is '*unsatisfactory and inadequate" is startling, 
but without explanation the report immediately fol- 
lows with further recommendations for remedying 
this unfortunate situation as follows: 
"(c) PROPOSED WORK. It is proposed to build 
a second lock to the landward of the existing lock, 
with guide walls as shown on sheet 18 accompany- 
ing. The work to be done involves 300,000 cubic 
yards of rock excavation, 35,000 cubic yards of 
earth excavation, construction of the land wall, 
sills, guide walls, and lock gates, together with the 
piping, etc., for operation. The estimated total 
cost is $1,300,000." 
s(d) PRIORITY. Because the     conditions dis- 
cussed above, which make the existing lock unsatis- 
factory even for 6-foot navigation, the construction 
of a second lock at Dam No. 1 is given a priority 
of A." 
Here it is seen that this new lock, although built 
for a 9-foot waterway with 10-foot depth over the 
sill, is "unsatisfactory even for 6-foot navigation." 
The meaning of "priority of A," as disclosed later in 
the report, is that this work and the expenditure 
therefor "are needed immediately.to care for existing 
commerce." (Page 29.) 
C71