Item A: Public Hearing onMetro Plan Amendment (Delta Sand and Gravel)

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Lined Pit Guide 2 September 2000 discussed in the following sections in their permit applications. A general plan for liner or slurry wall installation is sufficient for permitting under the 100 percent bond option. Included below are discussions and lists of those elements of designs, plans, and specifications that the Division will look for in applications for lined pits seeking the lower bond amount. The discussion and lists provided are necessarily generalized, and must be tailored to site specific operations and conditions. The examples provided are not intended to be Standard Specifications. Numerical information in the example specifications are typical for the vast majority of slurry wall and clay liner installations, but may be modified if justified to suit specific site conditions. The Mined Land Reclamation Board and the Division of Minerals and Geology want to emphasize that this is a guidance document only and is not a rule or regulation. Any time the Division provides guidance to reclamation permit Applicants, the information is intended to simplify and streamline the permitting process and minimize the need to extend decision dates or involve Applicants in extended adequacy review processes. The guidance provided is not intended to stifle the flexibility Applicants have to design their mining and reclamation plans and is not intended to serve as a template for any future rule making. Applicants may use this guidance to their benefit or may provide an application that does not follow the guidance and propose a different, innovative plan for permitting a slurry wall or clay liner. The Division and the Board will consider each application individually under the terms of the Mined Land Reclamation Act, and no Applicant will ever be penalized for, or encouraged to use the permitting guidance provided in this document. SLURRY WALLS The factors that may influence the performance of a slurry wall, and that should be addressed in a reclamation permit application are: · Design (including construction plans and appropriate drawings) · Technical Specifications · Construction Quality Control/Construction Quality Assurance (CQA) · Final Construction Report including the CQA Engineer's Certification The design documents and drawings must be sufficient to describe the major construction activities involved in building a soil-bentonite (S-B) slurry wall, which are: · Preparation of the site · Slurry mixing and hydration · Trench excavation · Backfill preparation · Backfill placement · Site cleanup The sl urry is used to hold the trench open until backfill can be placed. Slurry is composed of water with 4-8 percent sodium bentonite. The S-B backfill typically consists of a minimum of 2 percent