Riprap_Specifications.pdf

SECTION 313700 RIPRAP

April 2020

BEAR RIVER MBR

WATER CONTROL STRUCTURES

Section 313700 – Riprap

PART 1 - GENERAL

1.1. DESCRIPTION:

A. The work of this Section includes furnishing and placing rock riprap.

1.2. REFERENCES:

A. American Association of State Highway and Transportation Officials (AASHTO):

1. AASHTO T 24: Obtaining and Testing Drilled Cores and Sawed Beams of Concrete.

B. ASTM International (ASTM):

1. ASTM C 535: Standard Test Method for Resistance to Degradation of Large- Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine.

2. ASTM D 7012: Standard Test Method for Compressive Strength and Elastic Moduli of Intact Rock Core Specimens Under Varying States of Stress and Temperatures

C. Colorado Department of Transportation (CDOT):

1. Standard Specifications for Road and Bridge Construction.

D. Urban Drainage and Flood Control District:

1. Drainage Criteria Manual, Volumes 1, 2 and 3, latest edition.

1.3. SUBMITTALS:

A. Submit the following in accordance with Section 013300.

B. Trip tickets showing source, type, and weight of each load of material delivered to site.

C. Quality Control Submittals:

1. Certified Test Results:

a. Riprap: Provide the following test results prior to importing to the project site and during production on request of Engineer:

1. Gradation.

2. Abrasion Resistance: ASTM C 535.

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WATER CONTROL STRUCTURES

3. Unconfined Compressive Strength: ASTM D 7012.

b. Provide applicable test reports for concrete grout, including air content, compressive strength, and unit weight.

2. Submit certified test results for riprap within 10 days after award of contract.

1.4. QUALITY ASSURANCE:

A. Riprap Source: Rock for riprap shall be procured from a quarry that has produced riprap and has performed satisfactorily on other projects for at least 3 years.

PART 2 - PRODUCTS

2.1. RIPRAP:

A. Rock for riprap shall be Type M riprap which corresponds to designations listed in Table MD-7 Classification and Gradation of Ordinary Riprap, of the Urban Drainage and Flood Control District’s “Drainage Criteria Manual”, Volume 1. Rock shall consist of hard, dense, durable quarry stone, angular in shape, well-graded, and resistant to weathering. Rounded stone or boulders will not be accepted as riprap material. The stone shall have a specific gravity of at least 2.5.

Table MD-7 Classification and Gradation of Ordinary Riprap

Riprap Designation % Smaller Than Given Size by

Weight

Intermediate Rock

Dimensions (inches)

D50 (inches)*

Type M

70-100 21

50-70 18

35-50 12

2-10 4

*D50 = mean particle size (intermediate dimension) by weight.

B. All riprap should be placed at a minimum thickness of 24-inches. Urban Drainage and Flood Control District Type II Bedding should be placed to a depth of 12-inches under all new riprap (UDFCD, 2016).

C. Do not use flat or elongated shapes unless the thickness of the individual pieces is at least one-third the length.

D. Material shall be clean and free from deleterious impurities including alkali, earth, clay, refuse, and adherent coatings.

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E. Riprap material shall meet the following requirements for abrasion resistance and compressive strength:

Test Description Test Method Specification Requirement

Abrasion Resistance by Los Angeles Machine

ASTM C 535 50% loss, maximum

Unconfined Compressive Strength of Drilled Core Specimen

AASHTO T 24 2500 psi, minimum

PART 3 - EXECUTION

3.1. SUBGRADE PREPARATION:

A. Prepare subgrade to receive riprap in accordance with Section 310000.

3.2. PLACING RIPRAP:

A. Place riprap to the lines, grades, and thicknesses shown on the Drawings. Stones with typical stone dimensions that are equal to D50 and larger shall be placed at the top surface with faces and shapes matched to minimize voids and form as smooth a surface as practical.

B. Dumping and backhoe placement alone is not sufficient to ensure a properly interlocked system. The material may be machine-placed and then arranged as necessary by use of equipment such as a Gradall with multi-prong gapple device or by hand to interlock and form a substantial bond. Riprap shall be placed with smaller rock fragments used to fill in the voids between larger rock fragments in such a manner as to form a smooth, uniform, well-graded layer of riprap that is stable and not susceptible to sliding. Riprap shall also be placed to form smooth transitions to embankment slopes, channel slopes, and channel side slopes. No distinct horizontal, vertical or angular joints will be allowed in the riprap that would reduce the interlocking capability of the riprap.

C. After final placement to line and grade and before grouting, the riprap shall be plated by mechanical means so there are no protruding angular surfaces above finish grade.

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