Project Grant R23AP00325

THE OVERALL BENEFIT TO THE PUBLIC AND RECLAMATION WILL BE HAVING AN EFFECTIVE FISH SCREEN OPERATING IN THE GVIC CANAL, THEREBY KEEPING ENDANGERED AND THREATENED FISH IN THE COLORADO RIVER. MORE SPECIFIC ADVANTAGES FOR EACH OF THE PROJECTS IS FURTHER DETAILED BELOW. THERE ARE TWO MAIN ADVANTAGES TO RAISING THE DAM AND THE LOW FLOW CONDITIONS IN THE RIVER SYSTEM THAT HAVE BECOME MORE COMMON OVER THE LAST TWO DECADES HAVE MADE THESE ISSUES BECOME MORE APPARENT. FIRST, WHEN THE COLORADO RIVER IS AROUND 2000 CUBIC FEET PER SECOND (CFS) OR BELOW, THEN THE HEADGATES OF THE GVIC DIVERSION DAM ENTER A PARTIALLY SUBMERGED STATE OF OPERATION. OPERATING GATES IN A PARTIALLY SUBMERGED STATE MAKES MANAGING A CONSTANT FLOW INTO THE CANAL VERY CHALLENGING AND CAN QUICKLY LEAD TO SITUATIONS WHERE THE FISH SCREEN IS BEING OVERLOADED OR LACKING WATER FOR DELIVERIES IN THE CANAL AS WELL AS FISH SCREEN OPERATIONS.SECOND, WHEN FLOWS IN THE COLORADO RIVER BECOME VERY LOW, NEARLY ALL WATER REMAINING IN THE RIVER CAN BE DIVERTED INTO THE GVIC CANAL. DURING THESE TIMES THERE IS SOME WATER WHICH MAKES IT OVER THE DIVERSION DAM INSTEAD OF GOING INTO THE CANAL. IN THIS SITUATION GVIC SHUTS OFF THE FISH RETURN PIPELINE AND STOPS FISH SCREEN OPERATIONS TO ENSURE THEIR WATER USERS RECEIVE THEIR DECREE.THE WORK SHALL INCLUDE 4 MAIN CONSTRUCTION COMPONENTS: RAISING THE EXISTING DIVERSION DAM WITH A CONCRETE CAP PATCHING DETERIORATED AREAS OF THE EXISTING DAM SURFACE OUTSIDE THE CAP AREA REPLACING 4 RADIAL GATES AT THE SOUTHWEST CORNER OF THE DIVERSION DAM SUPERVISORY CONTROL AND DATA ACQUISITION (SCADA) SYSTEMTHE PROJECT SHALL RAISE THE EXISTING DIVERSION DAM CREST APPROXIMATELY 9-18 WITH A CONCRETE CAP OVER THE ENTIRE 1,100 LF FOOT LENGTH OF EXISTING STRUCTURE. THE FISH PASSAGE STRUCTURE AND ASSOCIATED IMPROVEMENTS ON THE NORTHERN END OF THE DIVERSION DAM SHALL NOT BE ALTERED IN ANY WAY. THE WIDTH OF THE EXISTING DIVERSION DAM VARIES BUT THE PROPOSED CAP SHALL INCORPORATE A 12FT WIDE LEVEL SECTION, WHICH WILL ALLOW MAINTENANCE VEHICLES TO TRAVEL ACROSS THE STRUCTURE, THAT THEN TAPERS AT 2H:1V SLOPE TO TIE INTO THE EXISTING DIVERSION DAM ON THE DOWNSTREAM SIDE OF THE CAP. THE UPSTREAM EDGE OF THE CAP SHALL HAVE A ROUNDED EDGE TO FACILITATE THE PASSING OF TRASH AND DEBRIS ACROSS THE STRUCTURE.THE PROJECT SHALL ALSO INVOLVE EXTENSIVE PATCHING OF DETERIORATED PORTIONS OF THE EXISTING DAM SURFACE OUTSIDE THE PROPOSED CONCRETE CAP EXTENTS TO MAINTAIN INTEGRITY OF THE STRUCTURE WHILE REDUCING HYDRAULIC TURBULENCE ACROSS THE STRUCTURE. THIS PATCHING PORTION OF THE PROJECT SHALL BE PART OF THE RECIPIENTS RECURRING OPERATION AND MAINTENANCE ACTIVITIES. SINCE WATER CONTROL MEASURES WILL BE IN PLACE DURING THE DAM RAISE ACTIVITIES, IT IS ALSO THE IDEAL TIME FOR GVIC TO ATTEND TO THESE MAINTENANCE ACTIVITIES.THE FOUR RADIAL SPILL GATES LOCATED IN THE COLORADO RIVER TOWARD THE SOUTHWESTERN CORNER OF THE DIVERSION DAM ARE UTILIZED TO CONTROL FLOWS INTO THE SYSTEM AND OVER THE DIVERSION DAM. IN ORDER TO CAPITALIZE ON THE FULL POTENTIAL OF THE DAM RAISE, THE PROJECT SHALL REPLACE THESE EXISTING GATES WITH NEW RADIAL GATES AND ACTUATORS.THE NEW GATES WILL MATCH THE WIDTH OF THE EXISTING GATES, BUT THEY SHALL BE TALLER TO ACCOMMODATE THE PROPOSED DAM RAISE. THE NEW GATES SHALL BE INSTALLED IN THE EXISTING STRUCTURE BAYS BUT THE SEALING SURFACES ON THE SIDES OF THE GATES SHALL HAVE TO MODIFIED AND RAISED WITH CONCRETE CAPS TO MATCH TO NEW GATE HEIGHTS.THE SCADA SYSTEM TO BE INCORPORATED FOR THE PROJECT SHALL CONTROL THE HEADWORKS OF THE CANAL AS WELL AS THE FISH SCREEN. THEREFORE, ANY NEW EQUIPMENT NEEDS TO COMMUNICATE WITH GVICS EXISTING SCADA INFRASTRUCTURE. THE TRAVELING SCREEN HAS SIGNIFICANTLY MORE MOVING COMPONENTS THAN THE EXISTING FISH SCREEN. THE SCADA SYSTEM SHALL ALLOW THE TRAVELING SCREEN AND CANAL HEADWORKS TO OPERATE AT OPTIMUM EFFICIENCY WITH MINIMAL HUMAN INTERACTIONS.