2010-07-27_REVISION - M1977223 (21)

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IMPOUNDMENT LINER CONSTRUCTION SPECIFICATION I. Scope This specification provides for the earthen lining of the Colorado Beef Reservoir in Prowers County, Colorado. This specification is intended for construction and inspection methods for the lining of the reservoir with on -site earthen materials to minimize seepage from the structure. Site specific geotechnical testing will be required of a qualified geotechnical engineering firm to provide the field testing values (density and moisture readings) for the installation of the liner material. As -built samples of the installed liner material will be laboratory- tested for permeability. 2. Foundation Preparation and Excavation The foundation area of the reservoir should be prepared to assure a homogeneous bond with the fill material by removing loose, dry material, and scarifying, discing, adjusting water content, and compacting as necessary. As referenced in the EEC report, in -situ and embankment soils shall be scarified to a depth of nine inches, moisture - adjusted and compacted to 95 % of Standard Proctor at optimum moisture content ( -1 to +3 %). 3. Liner Material Soils from 5 to 17 feet below surface in the area of excavation of the reservoir have been identified as PREFERRED (EMBANKMENT AND) LINER MATERIAL by the Engineer and as referenced in the EEC report. These preferred materials are identified as `Bulls 7 9.0" and "Bulk 10 5.0" in the EEC report and are classified as Lean Clay or Lean Clays with Sand. The reservoir liner shall be constructed of this material and any variance from the soil types referenced shall not be used. Soils used shall be free of foreign material such as vegetation, organic matter, trash, brush, fallen trees or other objectionable material. Stones over two (2) inches in diameter shall be removed from the fill material The preferred material for use in the Iiner has tested for the following: Atterburg Limits, description/classification, No. 200 sieve analysis, permeability, Maximum Dry Density, and Optimum Moisture. During excavation of the reservoir, sufficient quantities of this material shall be stockpiled for liner and embankment placement prior to constructing roadways or building pads. Should installation of the PREFERRED LINER MATERIAL be installed as per these specifications, the Iiner should meet the seepage requirements of Colorado Mined Land Reclamation Permit. As liner excavation takes place, the liner material should continually be field inspected for homogeneity. If unanticipated soil materials are encountered during excavation, these materials should be sampled and laboratory tested to determine their suitability as liner material. The liner material must possess properties which meet or exceed those as specified as the PREFERRED LINER MATERIAL. Any materials which will not meet these permeability criteria will not be used. If sufficient amounts of suitable liner material are not available at this site, the Engineer may approve materials from borrow areas, or the addition of soil amendments, such as bentonite. If soil amendments are required, the Engineer shall specify the mixing ratio in order to achieve the desired hydraulic conductivity. No alternate Iiner materials are identified as part of this specification. However, at the discretion of the Engineer, alternate materials may be incorporated into this specification as necessary. 4. Liner Placement and Compaction The earthen liner material placed in the fill shall be free of sod, roots, frozen soil, stones over two (2) inches in diameter, and other objectionable material. Only materials specified for use as liner material are to be used as fill. The distribution and gradation of materials shall be such that there will be no lenses, pockets, streaks, or layers of SECTION 31 00 00 - 3