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

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GUIDE TO SPECIFICATION PREPARATION FOR SLURRY WALLS AND CLAY LINERS AS A COMPONENT OF A COLORADO MINED LAND RECLAMATION PERMIT September 2000 Colorado Department of Natural Resources Division of Minerals and Geology Michael B. Long, Director H. Bruce Humphries, Minerals Progr~ Supervisor Allen Sorenson, Contact Person for this Guide 1313 Shennan Street, Room 215 Denver, Colorado 80203 303/866-3567 http://mining.state.co.us/ INTRODUCTION It has become a common practice to reclaim gravel pits to a developed water resource land use through the installation of clay pit liners or sluny walls. The purpose of these installations is to isolate the constructed water storage reservoir from the surrounding ground water system. The State Engineer's Office has established design and performance standards for pit liners and sluny walls (see sections on Post Construction Testing below). It is the responsibility of the Mined Land Reclamation Board to hold sufficient bond to assure that the State Engineer's performance standard can be met if the Operator of a pit were to default and the state of Colorado were to reclaim the site with the forfeit bond. Under the Division of Minerals and Geology policy on lined-pits dated March 29, 2000, Operators may choose the option to bond for 100 percent installation or replacement cost of a sluny wall or pit liner or may select a regulated construction option and become eligible for a 20 percent installation or replacement bond. Operators are free to design and install the liner or sluny wall with relatively minimal design information, specifications and quality assurance detail in the permit application under the 100 percent bonding option. The assurance that the pit will be reclaimed to developed water resources is primarily managed through the amount of bond held by the Board. For an Operator to be eligible for the 20 percent bonding option, the Division must have a high degree of assurance that the liner or slurry wall installed by the Operator will meet the State Engineer's performance standard. This assurance is provided through inclusion of design documents, plans and specifications, and a quality assurance program as enforceable components of the reclamation pennit. This memorandum provides an outline that is intended to guide reclamation permit Applicants that are pursuing the 20 percent bonding option. Applicants that intend to bond for 100 percent of the installation or replacement cost of a slurry wall or clay liner do not have to provide the information