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LJ <br />July 31, 1984 <br />Page 3 <br />riser pipe. A 12 inch lower outlet gate will also <br />be required. Seepage collars shall be installed, <br />one on the upstream and, one on the downstream <br />portion of the core with locations being determined <br />in the field. Seepage collar construction will <br />consist of 1/4 inch steel plate flanged and banded <br />to the outlet pipe. Unless otherwise noted, outlet <br />gates shall be of steel body and provided with a <br />rubber seal. The gate should be provided with a <br />c/w hard wheel operator. Riprap shall be placed <br />below the outlet works for both ponds, with a <br />minimum 6-inch thickness, minimum width of 15 feet, <br />and a minimum length of 25 feet. An open channel <br />emergency spillway is to be designed and con- <br />structed to convey and provide a residual freeboard <br />of at least one foot during the 100 year, 24 hour <br />peak flow event. The spillway will be constructed <br />when the outlet design has been approved by the <br />Colorado Mined Land Reclamation Division. <br />n <br />U <br />INSPECTION AND TESTING <br />Inspection consisted of observing the excavation of the sediment storage area, <br />the installation of the trickle tube, and the observation of the fill place- <br />ment. Results of these inspections are documented in the Daily Field Reports <br />(Attachment 2). <br />laboratory soil tests include Modified Proctors and the percent of material <br />passing the No. 200 sieve. These tests were performed by Randall and Asso- <br />ciates, Inc., Steamboat Springs on three samples considered for use as suit- <br />able fill and core material. The fill material used to construct the struc- <br />ture was obtained from the upper reservoir (Pond 2) storage area. <br />Approximately 50 density tests were performed on the compacted fill during <br />embankment construction. Location and results of all performed tests are <br />presented in the attached Field Density Test Report (Attachment 3). <br />CONCLUSIONS AND RECOMMENDATIONS <br />I • <br />Based on laboratory and field testing and the construction inspection results, <br />it is our opinion that the construction of two sediment ponds, for Sun Coal <br />Company at the No. 1 Meadows Mine are in compliance with the construction <br />recommendations made in the July 6, 1983 Tender Documents. <br />the lower reservoir trench was overexcavated so that excess unsuitable topsoil <br />material would be removed. It is our opinion that excavation was necessary to <br />- 271 - <br />(Rev. 5/86) <br />