Significance and Use
4.1 General:
4.1.1 Many CCPs are suitable materials for the construction of engineered structural fills. CCPs may be used as: structural fill for building sites and foundations; embankments for highways and railroads, road bases, dikes, and levees; and in any other application requiring a compacted fill material. Their low unit weight, relatively high shear strength, ease of handling, and compaction make CCPs useful as fill material. However, the specific engineering and environmental properties of these materials can vary from source to source and must be evaluated for each material, or combination of materials, to be used for an engineered structural fill. Information contained in Guide D5759 may be applicable to some CCPs to be used in engineered structural fills. AASHTO Standard Practice PP059-09-UL also addresses the use of coal combustion fly ash in embankments. The requirements for the type of CCPs that can be used for specific engineered structural fills may also vary because of local site conditions or the intended use of the fill, or both. Environmental considerations are addressed in Section 5.
4.1.2 CCPs can be a cost-effective fill material. In many areas, they are available in bulk quantities at a reasonable cost. The use of CCPs conserves other resources and reduces the expenditures required for the purchase, permitting, and operation of a soil borrow pit. CCPs often can be delivered to a job site at near optimum moisture content and generally do not require additional crushing, screening, or processing as compared to comparable native materials.
4.1.3 Use of CCPs conserves natural resources by avoiding extraction or mining of soils, aggregates, or similar fill material that also conserves energy and reduces greenhouse gas emissions.
4.1.4 The volume of beneficially used CCPs preserves valuable landfill space.
4.2 Regulatory Framework:
4.2.1 Federal—Currently, there are no federal regulations addressing the beneficial use of CCPs. States and local jurisdictions have oversight of CCP management and beneficial use activities within their states
4.2.2 State and Local Jurisdictions—Laws and regulations regarding the use of CCPs vary by state and local jurisdictions. It is incumbent upon the project owner and designer to determine any local or state guidance, policies, or regulations pertaining to the use of CCPs.
Scope
1.1 This guide covers procedures for the design and construction of engineered structural fills using coal combustion products (CCPs) including but not limited to fly ash, bottom ash, boiler slag or other CCPs that can meet the requirements of an engineered fill as described herein. CCPs may be used alone or blended with soils or other suitable materials to achieve desired geotechnical properties.
1.2 This guide describes the unique design and construction considerations that may apply to engineered structural fills constructed of with CCPs that have been adequately characterized as being suitable for this beneficial use.
1.3 Beneficial utilization of CCPs consistent with this standard conserves land, natural resources, and
1.4 This guide applies only to CCPs produced primarily by the combustion of coal.
1.5 The testing, engineering, and construction practices for coal ash fills are similar to generally accepted practices for natural soil fills. Coal ash structural fills should be designed using generally accepted engineering practices. However, when CCPs are used in saturated conditions such as ponds or impoundments, the potential for liquefaction may need to be considered.
1.6 Laws and regulations governing the use of coal ash vary by state. The user of this guide has the responsibility to determine and comply with applicable requirements.
1.7 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
