WSP10308

• File Number: 8449
• Description: Platte River Studies
• State: CO
• Basin: South Platte
• Date: 3/23/1993
• Author: Smith Geotechnical
• Title: Design Report Peterson Lake Dam
• Water Supply Pro - Doc Type: Publication

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existing dam.

The proposed dam site was not Investigated by advancing borings and obtaining
rock samples at this time due to weather constrains and SIlOW. The site was
Investigated usIng seismic refraction methods to determine the depth to rock and
will be further Investigated with borings during the summer of 1993. The
attached report by Hadley & Hollingsworth, Ltd. outllnes the seismic Inveetlgatlon
that was conducted.

D, Desl~n.

a. RCC Properties. A theoretical RCC mix design has been determined
for the project but a laboratory mix design conducted using the onslte aggregates
has not been conducted at this time, Test pits were dug and samples taken from
the potential borrow areas to determine that enough aggregate of the size
required exists on site to complete the project.

The stability and stress analysis, and cracking analysis were all baeed on
publlshed values of RCC properties. The design Is based on a compressive
strength of 2000 psi at 180 days and the temperature analysis was based on
using 200 pounds of cement per cubic yard with no fly ash. Typical values of
strength were taken from Figures 2,16 and 4.3, Roller Compacted Concrete Dams,
by Hansen and Reinhardt and from Roller Compacted Concrete. Engineer Manual,
EM-llI0-2-2006, Corps of Engineers.

Laboratory mix designs will be conducted on the materials from the Intended
borrow areas during the summer of 1993. The solis approach to the mix designs
will be followed and strengths will be detennlned. SophIsticated testing to
determine tensile strength and Joint bond strength are not planned for this pro-
ject. The conservative values used for the analysis should not be difficult to
attain and are more a function of proper construction quality control and
especially proper 11ft JoInt preparation.

The bond between lifts Is critical for the stability and water tightness of the
dam and the design Is based on bonding the first 10 feet of the upstream portion
of each Joint with beddIng concrete. The remainder of the Joint must stili be
capable of providing a good bond and will also be bedded with concrete In any
area that Is more than eight (8) hours old or that Is dried out or In any way
disturbed.

Table I lists the strength values used for the stability analysis of the dam.

b. Rock Properties, The properties of the rock were based on values
given In "Dams On Rock Foundations-Some Design Questions", by Don U. Deere,
ASCE Specialty Conference, Rock Enl(lneerlnl( For Foundations and Slopes. August
16-18, 1976, Boulder, Colorado, and "Dams On Rock Foundations", by Lloyd B,
Underwood, ASCE Specialty Conference, Rock Enl(lneerlnl( For Foundatlone and
Slopes. August 16-18, 1976, Boulder. Colorado. Table I In the last reference
contains actual test results of gneiss, granite, and schistose rocks. Table I
below lists the properties used for the rock foundation materials.

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Peterson Lake Dam Design Report