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RESPONSE TO MINED LAND RECLAMATION DIVISION HYDROLOGY CONCERNS AT THE ALMA PLACER MINE Memos have been issued by Mined Land Reclamation Division (NERD) ndicating concerns regarding pond embankments that will be used to contain he recirculating rater for the Placer mining operation. In response to these concerns from the MLRD, pond embankments have been altered in the field, and office reassessment has been performed. Field work is continuing and minor differences may occur from estimates contained herein. ~u~i:f?~'~~ •~ 9lstory A brief history of the embankments is useful information. The pc embankments present in the Field today have a core embankment the place for over 50 years. The relatively small historic embankmer by several mining operations over the years. Usage of the ponds mine raters upstream of the embankment and fine materials, i.e., clays, (also known as slimes) settled into the bottom of the pond indicate that these fines xere bulldozed out of the pond bottoms on top of the historic berms. Some of this material slid down tt slope of the resulting embankment and impinged on some vegetation of the embankment. This raised the ire of regulatory agencies, a applicant was directed to remove the material From the vegetation this goal, bulldozers were used to pull the downstream face of tt embankment up the slope and discharge it into the impoundment ere in order to clear the downstream toe. Additional concerns Erom t the time this operation was taking place resulted in more extensi evaluation and reconstruction. As a result, the downstream face of the modified historic embank cleaned to within zero to three feet of the apparent original gr The material was then replaced in approximately 12 inches loose compacted using a vibrating sheet roller. The downstream slope reconstructed in a slope of 3 horizontal to 1 vertical as shown The earthwork movement became so extensive, that the removal and effort was repeated For the upstream Face of the embankments as downstream face. • Soils Data As discussed above, the embankment section has been extensively that which previously existed. Soils tests were performed on th embankments and the material was found to fall into two classifi SM and CL. The clay soils (CL) are relatively limited in extent be the slimes that were pushed out of the pond. For the most pa has been in s were used mpounded ilt and Reports nd pushed up downstream at the toe d the mine To achieve loose temporarily e MLRD at e embankment ants has been and level. ifts and Plate lA. mpaction 1 as the evised from disturbed ations, SW- and appear to t, a 1