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Mmix,' ~GI:ug.. ...-......- -.- . -~ Page 4 July 24,2000 Il~,~ MIIri><~~.. ,~--..- -- Page 5 July 24, 2000 DESCRIPTION: Station mark is small It is 16. the ground. disk attached to a pipe projecting 3 cm from a 1.6-ft. round concrete post flush with 1-ft. south of, and slightly higher than the road center, 8.2-ft. north of the right-of- NAME TR88 AP4 ORDER THIRD ELEVATION 6,585.1 7.6 miles southeast from Carbondale, In Eagle County, 7.6 miles southeast along the Denver and Rio Grande Western Railroad from the station at Carbondale, Garfield County, 190 feet southeast of the center of a road crossing, 45 feet east of the Frank Berthoud Home, 30 feet southwest of the centerline of the track, 6 feet northwest of an east fence comer, and 3.5 feet northeast of the fence. 1 The basis of vertical control for the surveyed Roaring Fork River cross-sections is NA VD 29 sea level datum originating at USGS benchmark for Township 8 South, Range 87 West, Section 12 TR62. The locations of the four benchmarks used in the survey are described below: DESCRIPTION: A standard disk, stamped G 158 1934 and set in the top of a concrete post. The station is located about 2.9 miles east-southeast of Emma, 1.8 miles southeast of Basalt and 1.3 miles south of he Eagle-Pitkin County Line, in the northeast 1,4 of Section 20, T 8 S, R 86 W, at State Highway 82 milepost 24.8. Ownership - Old Railroad right-of-way to reach the station from the bridge over the Frying Pan River just before it goes into the Roaring Fork River in Basalt, go southeast on the old State Highway 82 for 1.75 miles to the crossing of the railroad tracks and the highway and the station on the right. The station is a standard disk set in the southeast comer of the abutment of a railroad bridge crossing the Roaring Fork River. It is 250.0 feet west-northwest of the center of the crossing 'of State Highway 82, 228.0 feet west-northwest of railroad milepost 385, 108.3 feet east of the center of the bridge over the Roaring Fork River, 6.07 feet south of the near rail, 1.3 feet north of the southern edge of the abutment, 1.0 feet southwest of a witness post, 0.7 feet east of the west edge of the abutment, about 2.0 feet below the near rail and at Bridge 384A over the Roaring Fork River and the siding at Wingo. Vertical control points for control for the mapping. similar to CA-35. Generally, field topographic contours surveys agreed well with topographic mapping except appeared to be high in certain locations. the cross sections were three-quarter inch rebar pins, which were used as aerial These points are shown on the mapping and are designed by letters and numbers 4 NAME G158 ORDER SECOND ELEVATION 6,640.8 in areas of heavy brush where Sopris Engineering surveyed 44 cross-sections in areas of special interest (e.g. bridges, wide valley bottoms, or where floodplain development had occurred). In addition, bridge measurements were verified and spot elevations taken at critical points. the The topographic mapping for this study from the GarfieldlEagle County line through the Wingo Bridge was provided by the Greenhorne & O'Mara. This mapping was available at scales of I" = 200'. The contour interval of the mapping was 2 feet. The upper Pitkin County mapping from the Wingo Bridge to the confluence with Snowmass Creek was obtained from the Roaring Fork Railroad Holding Authority and was produced with a contour interval of 5 feet. DESCRIPTION: A standard disk, stamped E 158 1934. 2.5 Cobble-bed streams such as the Roaring Fork River exhibit instability problems when the cobble particles are mobilized. Those particles begin to move when the water exceeds a shear stress on the bed particles beyond the threshold value for incipient motion. When flow rates and velocities are high enough to mobilize the cobble, the channel becomes unstable. Calculations can estimate the flow conditions under which cobble will be mobilized. Bedload calculations and sediment rating curves have been developed specifically to estimate the flow frequency (i.e. 5-year flow conditions, lO-year flow conditions, 25-year flow conditions) under which particle mobilization will occur at particular locations of stream instability. Ma 3 NAME E158 DESCRIPTION: A standard disk, stamped 158 1934 and set in the top of a concrete post 5.8 miles northwest from Woody Creek. 5.8 miles northwest along the Denver and Rio Grande Western Railroad from benchmark A 158 at Woody Creek, Pitkin County, 0.2 miles east of the station at Rose, 330 feet east of milepost 387, 56 feet west of a corrugated pipe culvert, 40 feet northwest of the center of a road crossing, 30 feet southeast of pole 2547, 20 feet north of the centerline of the track, and 4 feet higher than the top of the rail. ORDER SECOND ELEVATION 6,749.l8. THIS SURVEY - 6,749.43 PUBLISHED 2.4 Channel Flood flows on the Roaring Fork River typically result from rapid melting of the mountain snowpack during the period from May to early July. Snowmelt runoff may occasionally be augmented by rain. The snowmelt runoff is characterized by sustained periods of high flows and marked diurnal fluctuation. Examination of meteorological and climatological conditions and precipitation and stream flow records show that summer cloudbursts are not a great flood threat on these streams. Instabilit 2. NAME D158 To reach from the junction of State Highway 82 and the Basalt turnoff (at stoplight, about 0.4 miles south of Basalt), go west on Highway 82 for 1.35 miles to a paved road right just before reaching crossroad. Turn right, north, for 0.05 miles to aT-road. Turn right, east, on paved road for 0.1 miles to the station on the right at job in fence line. ORDER SECOND ELEVATION 6,898.60 The month of ""'h a normal spring o Fahrenheit. way fence, 13.8-ft. west of the north post to a deer gate (lets animals off highway) at ajob in fence, north of a fiberglass witness post and 3.6-ft. east of a fiberglass witness post. ort Town 0 le & Pitkin Counties, Colorado ort Town 0 & Pitkin Counties, Colorado 3-ft.