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<br />SHEET 3 OF 37 <br />COMMENTARY <br />RALSTON CREEK <br />STATION 234+00 TO 260+00 <br />REACH R3 <br />CITY OF AR VADA <br /> <br />SHEET 3 OF 37 <br />COST ESTIMATE <br />RALSTON CREEK <br />STATION 234+00 TO STATION <br /> <br />CONSTRUCT ION <br /> <br />This area is characterized by intense residential development in the over- <br />bank. The one exception is downstream of the Ralston/ Leyden Creek conflu- <br />ence where a pond and small park have been constructed. A narrow right-of- <br />way has been maintained for the existing channel. The floodplain in this <br />reach is approximately one to two blocks wide and inundates several single <br />family residences. <br /> <br />Drainage improvement costs <br />Street crossing costs <br />Utility relocation costs <br /> <br />Total construction costs <br /> <br />Proposed improvements incl ude the construction of a European 1 ined channel <br />from the downstream end of Sheet 3 of 37 to the downstream end of the park. <br />This channel is si zed to convey the 10-year storm. A drop structure is <br />proposed, immediately downstream of the park. This drop structure will <br />serve to transition flows into the channel section. The west 68th Avenue <br />crossing is to be replaced by three 8' x 14' boxes and one 10' x 14' box. <br />Low flows would be conveyed in a low flow channel which simul ates the <br />existing low flow channel in this reach to enhance the reestablishment of <br />riparian habitat. A maintenance trail should be constructed near the <br />channel bottom through this reach in order to allow access for periodic <br />mai ntenance. <br /> <br />Engineering and contingencies <br />(30% of total construction costs) <br /> <br />Property acquisition costs <br /> <br />TOTAL IMPROVEMENT COSTS <br /> <br />MAINTENANCE <br /> <br />Annual operation/maintenance costs <br /> <br />Floodpl ain regul ations should be superimposed on the recommended improve- <br />ments. This will insure that no imprudent development occurs in the resi- <br />dual 100-year fl oodpl ai n . Prior to the constructi on of recommended im- <br />provements, floodplain management practices should be in accord with the <br />flood hazards identified for the existing channel conditions. <br /> <br />260+00 <br /> <br />$1,634,185 <br /> <br />151,881 <br />72 , 850 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />1,858,916 <br /> <br />557,675 <br /> <br />295,050 <br /> <br />$2,711,641 <br /> <br />$4,837 <br />