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<br />. <br /> <br />. <br /> <br />.BRW <br /> <br />_emlll'=" A-DAMES -& MOORE- GROUP COMPANY <br />Roaring Fork and Fryingpan River Multi-Objective Planning Project <br /> <br />Scope of Services <br /> <br />on each side of the river centerline. We anticipate some expense associated with obtaining digital <br />mapping. The GIS base mapping will be at a 1:24,000 scale or better and show: <br /> <br />. Topography <br />· Major vegetation types (use and interpret existing information - no new field surveys) <br />. Stream centerline and left and right banks <br />. Bankfull dimensions <br />. Streets and highways <br />. Political subdivisions <br />. Major structures (bridges, major utility crossings, encroaching man-made structures) <br /> <br />The enclosed table details the layers anticipated on the GIS and the likely source for information. <br /> <br />In addition to base topographic mapping, one base set of recent (post-1995 flood) comprehensive <br />regional rectified aerial photography will be included with the base mapping. We propose to either <br />piece together and rectify best available aerial photography (this requires approximately one hour <br />of consultant's time per river mile to scan and rectify image), or purchase satellite imagery in black <br />& white with 5 meter resolution ($2,500 for a 70 km x 70 km reach in digital format and rectified). <br /> <br />Our first task will be to inventory available mapping and data. We will prepare a progress memo <br />identifying the information that will be used and where gaps in the data may exist. The progress <br />memo will refine the scope of work under this Task A.2 item to manage the budget. <br /> <br />As discussed in the interview, we believe a qualitative approach to initially define instability will <br />be most efficient by pulling in and "rubber sheeting" to an accurate scale a pre-1983 historic aerial <br />photograph into the GIS system to show migration of the channel after three flood events. We will <br />identify locations that can be studied quantitatively by aerial photographs and those areas with <br />similar characteristics where stability information can be extrapolated. We will utilize gage records <br />and available hydrology to evaluate the flood history of the river. We do not propose any <br />watershed hydrology modeling under this project. <br /> <br />Work product will be the GIS mapping both in hard copy and electronic format along with a <br />narrative in the report on channel instability. <br /> <br />Task A.3. - Determine Causes of Instability <br /> <br />Once critical areas of instability are determined under Task A.2., the sites will be field checked to <br />understand the causes of instability and define the limits of instability. Information on the river bed <br />and bank particle size will be necessary at key locations. A geotechnical firm such as Hepworth- <br />Pawlick Geotech can complete gradation analyses at specified locations for approximately $100 per <br />site. We assume this will be required at 10 locations. Other parameters such as bed slope, channel <br />geometry and hydraulics can be obtained from the GIS mapping or floodplain HEC-2 and HEC- <br />RAS models. We will utilize mathematical and graphical models to define channel stability flood <br />events that will trigger the threshold of instability. <br /> <br />K:\Proposa1\02830-98\O 15\Scope. doc <br /> <br />Page 2 <br /> <br />July 14, 1998 <br />Offices Worldwide <br />