FLOOD10000

• County: Bent
• Community: Las Animas
• Stream Name: Arkansas River
• Basin: Arkansas
• Title: Las Animas Local Protection Project Design Memo Number 1 Hydrology
• Date: 9/1/1967
• Prepared For: Las Animas
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Project

SIIDED-'.; (m'lAED-ili 3 Oct 67) 1st Ind
SUBJECT: Las Animas Local Protection Project, Las Animas, Colorado,
and Vicinity, Design Hemorandum NO.1, Hydrology

Div Sngr, S;lDiv, CE, 1114 Commerce St., Dallas, Tex. 75202 29 Jan 68

TO: Chief of Engineers

Subject design memorandum is recommended for approval and use in
future pl.anning of the project subject to the following cOllll1ents:

a. Par 7-05, page 26. '!be basis for the assumption that the
Purgatoire River would have a t'low of 20,000 c.f.s. coincident with the
project design flow of 140,000 c.f.s. in the Arkansas River should be
presented; converseJ.y that the Arkansas R:l.ver would have a now of 8,000
c.f.s. coincident with a now of 120,000 c.f.s. in the Purgatoire River.

b. Par 9-03. This paragraph and pl.ates 18, 19 and 20 indicate
three ponding areas may be required behind the right bank levee and one
behind the left bank levee. The permissible eJ.evations of pending stages
A and C determined in accordance with paragraphs 3-03 and 4-04 of
El-! lllO-2-1410 for each of the ponding areas should be given.

c. Par 9-06. Information should be presented as to wether or
not the abandoned gravel pit haG suf'ficient capacity to contain the runoff
from the portion of Las Animas which drains into it without contributing
to interior drainage problem; if' not, the runoff from thin area should be
included in the interior drainage pl.an.

d. Par 9-08, page 30. The numerical value of the rainfalls uned
in denien should be presented.

e. Par 9-09, page 30. It is noted that the rainfall for
Pueblo, Colorado, given in U. S. Weather Bureau Technical Paper No. 25
was used for computation of runoff from the interior drainage areas at
Las Animas. Since publication of Technical Paper Ifo. 25, the Albuquerque
District has been furnished a copy of U. S. Weather BureaU Technical Paper
No. 40. Technical Paper No. 40 shows the one hour 25-year rainfall at
Las An1mas to be 2.3 inches instead of 1.9 inches. '!be district sIjould
determine if the use of the increased rainfall will result in a significant
change in runoff from the interior drainage areas.

f. Par 9-12, page 31. The design flows for the interior collec-
tion ditch should be reviewed in regard. to comment e, above.

g. Par 9-13, page 31. The district should reinvestigate the
required volume of pending in the several 'pending areas with regard to
c01lllllent e, above.

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