2014-10-07_GENERAL DOCUMENTS - M1981184

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ITEM 7.0 RECONSTRUCT STREAM CHANNEL FROM GOLD RUN TO RIVER LEVEL Gold Run Creek runs through the center of the site, and is a single thread channel with a steep gradient (4-10%) grade, relatively straight and is entrenched. The stream falls into class A of the Rosgen Stream Classification (Rosgen, D.L. and H.L. Silvey. 1996. Applied River Morphology. Wildland Hydrology Books, Fort Collins, CO.) The dominant profile of this stream is a step-pool formation that is natural to this class of stream. The dominant channel material is boulder to cobble sized particles. Approximately one hundred feet (100') of stream will be affected by this task. To prevent further erosion and down cutting, approximately six (6) Cross Vanes will be constructed equally spaced spanning the one hundred feet (100') of stream channel from the Gold Run to the River Level to restore and stabilize the stream channel. Using a track hoe with a thumb, mini excavator or method of CONTRACTOR'S choosing and non acidic materials harvested on site, the stream bed will be stabilized by enhancing its step-pool formation. The Current width of the stream, approximately three to four feet (3'-4') and existing sinuosity (lateral movement from center line) will be maintained. In-stream structures known as Cross Vanes , a U shaped rock structure across the width of the stream with the apex or center third of the structure orientated upstream. The one third of the structure on either side of the apex will be angled approximately twenty to thirty degrees (20-300) as measured downstream from the plane created by the center third. The Cross Vanes will be used to create step pools and direct flow away from the banks (Figure 4). Cross Vanes will be spaced no more than sixteen feet (16') apart as measured from the center third section of the structure with a small scour pool created below the apex. The scour pools will be lined with cobble sized non acidic material found on site. The Cross Vane will be constructed no more than two (2') tall as measured from the top of the structure to the bottom of the scour pool to dissipate stream energy and prevent down cutting. Measure and Payment Payment for this task will be made at the unit prices established in Item 7.0 of the Bid Schedule. Measurement for payment will be made to the nearest one foot of open channel constructed. The price bid shall include all costs for labor, materials, equipment, and all other items necessary and incidental to complete the tasks as described in Item 7.0. Payment will be made upon completion of the described task and approval by the PROJECT MANAGER. ITEM 8.0 SEDIMENT POND/ SURFACE EROSION CONTROL MEASURES The Gold Run and River Levels have large semi-flat areas of this task are prone to erosion by overland flow. These areas are connected by a small road. The goal is to regrade and roughen these areas to minimize surface erosion, direct runoff flows towards the sediment pond, dredge to deepen and expand the sediment pond. ITEM 8.1 EXPAND SEDIMENT POND The sediment pond is a small circular pond with an estimated diameter of twenty feet (20') and an estimated depth of one to two feet (1-2'). Using a medium track hoe or mini excavator or method of the CONTRACTORS choosing this pond will be expanded to an approximate diameter of thirty feet (30') and an average depth of three feet (3'). The slopes of the bank will be relaxed to no steeper than 3H:1V. Upon the approval of the PROJECT MANAGER dredged material can be dried and used in directing runoff flows toward the sediment pond. 12