WSP05705

• File Number: 8407
• Description: Platte River Basin - River Basin General Publications
• State: CO
• Basin: Statewide
• Date: 3/11/1964
• Author: CWCB
• Title: Engineering and Geologic Investigation and Analysis of Alternate Proposed Dam Sites on the South Platte River - Morgan and Weld Counties-Colorado
• Water Supply Pro - Doc Type: Report/Study

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the embankment proper would include those of trench excavation

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and backfilling, and the cost of hauling clay for approximately

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seven mile'S; (2) cutoff to bedrocl, ovel' the whole axis except in

the buried channel area, which would involve an open-cut trench

backfilled with clays as described in (1) above, plus either a

dcwatered open-cut below water table or a slurry trench cutoff

extl'nding to approximately elevation 4450. The extra cost items

,I in addition to (1) above would be either the slurry trench cutoff,
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i( or the dewatl'rlCd cut and compacted clay backfill for it; (3) a
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complete cutoff to bcdrocl, fOl' the entire length of axis. This

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'~ would include cutoff (2) above plus either a slLU"ry trench cutoff

in the buried channel area or a grouted cutoff in the buried

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channl,l.

In our opinion, it might be economical to achieve a

virtually complete cutoff at this site, and its cost versus bene-

."~

I

fits should he estimated.

The estimated effects on seepage losses of the various cut-

offs as indicated above area:

(1) Zero Cutoff - - 31 cubic feet per second.

(2) Cutoff to Bedroc), on Abutments and to Water Table in

Stream Channel - - 29 cubic feet per second.

(3) Cutoff to Bcdrocl, over Whole Axis Except Bur ied Channel

- - 25 cubic feet per second.

(<1) Complete Cutoff to Bedrock - - Negligible.

It would be expect~d that the latter complete cutoff would

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also rlCduce the present underflow in the river channel to a

(
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negligible amount.

MATER IALS FOR THE WELD EMBANKMENT

A goncral inventory of materials whicJl could be utilized in