BOARD01548

• Board Meeting Date: 1/25/2005
• Description: Proposed Revisions to the Rules and Regulations for Dam Safety and Dam Construction
• Board Meetings - Doc Type: Memo

5.7.5 For Minor, Low Hazard and all NPH dams, the report shall include, as a minimum,
field and laboratory classification of natural and placed soils.

5.7.6 For all dams, except Minor Low Hazard and all NPH, with a spillway located on an
earth foundation, the report shall include the following:

1. Laboratory Classification of soils along the alignment of the
spillway;

2. A profile of soils along the channel extending to a depth of at least
five feet below the bottom of the spillway; and

3. Density or bearing capacity of foundation soils beneath spillway
structures except for riprapped or unlined sections of the channel.

5.7.7 For all dams, except minor Low Hazard and all NPH, with spillways located on a
rock foundation, the report shall include a geologic description of the rock, description of
the bedding and jointing patterns, and an evaluation of the site's suitability to accommodate
the spillway.

5.7.8 The following criteria shall be required, as a minimum, in the geotechnical design:

1. The shear strengths of the foundation soils (including suitable factors of
safety) shall not be exceeded under any foreseeable loading conditions;

2. Seepage through the embankment, abutments, and foundation shall be
controlled to prevent internal erosion and extemal sloughing;

3. The embankment shall be protected against external erosion;

4. The crest width shall be equal to the jurisdictional height of the dam in
feet divided by 5, plus 10 feet. The maximum crest width required shall be
25 feet;

5. Minimum compacted density for embankment materials shall be 95
percent of maximum dry density for ASTM D-698 (Standard Proctor) or 90
percent for ASTM D1557 (Modified Proctor), as found in the 2004 "Annual
Book of ASTM Standards", Section 04.08, Soil and Rock; Building Stones,
1916 Race Street, Philadelphia, Pennsylvania, 19103, (later amendments,
editions or subsequent publications not included). Impervious zones with
clay fines shall be controlled using Standard Proctor criteria to maintain the
plastic nature of the material; and

6. The minimum density for cohesionless materials shall be 65 to 75 percent
relative density as determined by ASTM D-4253 and 4254 as found in the
2004 "Annual Book of ASTM Standards," Section 04.08, Soil and Rock;

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