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DAM NAME: San Luis Tailing Dam DATE OF REPORT:July 11,2024 <br /> TAILINGS DAM INSPECTION FORM <br /> Directions: Mark and X for conditions found and underline words that apply <br /> SEEPAGE AND TSF UNDERDRAIN OUTFALL <br /> PROBLEMS NOTED: <br /> ❑ (30)NONE 0(31)SATURATED EMBANKMENT AREA 0(32)SEEPAGEEXITSONDAM <br /> ❑(33)SEEPAGE EXITS AT POINT SOURCE ®(34)MINOR PONDING OF PIPE SEEPAGE <br /> AT TOE <br /> DRAIN OUTFALL SEEN: ®YES 0 NO <br /> ❑(35)FLOW ADJACENT TO DRAIN PIPE El(36)DRAIN OUTFLOW TURBID 0(37)DRAIN DRY/OBSTRUCTED <br /> El(38)OTHER <br /> SHOW LOCATION OF DRAIN ON SKETCH See Figure 1 <br /> AND INDICATE AMOUNT AND QUALITY OF SEEPAGE Minor clear seepage from underdrain outlet creates puddle,attracting animals,but no pipe damage. <br /> Per Steve Carino,the temporary access berm and culvert to right of the drain outlets will be removed. <br /> CONDITIONS OBSERVED: 0 GOOD IS/ ACCEPTABLE ❑ POOR <br /> STORMWATER MANAGEMENT SYSTEM <br /> PROBLEMS NOTED: <br /> ❑ (40)NONE 0(41)NO EMERGENCY SPILLWAY 0(42)EROSION AT DROP STRUCTURE <br /> ❑(43)CONCRETE DETERIORATED/UNDERMINED ❑(45)STRUCTURE MAY BETOO SMALL <br /> ❑(46)DIVERSION CHANNEL EROSION 1:1(47)INADEQUATE CHANNEL FLOWCAPACITY ❑(48)CHANNEL FLOW OBSTRUCTED <br /> 0 (49)OTHER Rilling along the south side of drop structure-continue monitoring and plan for repairs. <br /> South diversion channel and downstream toe runoff collection swales are in good condition. Mitigation of erosional tilling south of <br /> drop structure is required. <br /> CONDITIONS OBSERVED: ❑ GOOD ® ACCEPTABLE ❑ POOR <br /> MONITORING <br /> EXISTING INSTRUMENTATION FOUND: <br /> ❑(50)NONE ❑(51)GAGE ROD IN POOL AREA 0 (52)PIEZOMETERS <br /> El(53)SEEPAGE WEIRS/FLUMES ❑(54)SURVEY MONUMENTS ®(55)OTHER Underdrain flow <br /> MONITORING OF INSTRUMENTATION: <br /> El (56)NO WEIRS/FLUMES El(57)YES <br /> PERIODIC INSPECTIONS BY: <br /> ® (58)OWNER ® (59)ENGINEER <br /> Standpipe piezometers remain dry. Eight new VWPs installed in 3 borings in the impoundment in 2024(Fig.1). Average underdrain <br /> flow measurements from April 2023 to April 2024(26.7 gpm)are lower than from 2016-2024(33.0 gpm). Continue jetting and video <br /> inspection program. <br /> CONDITIONS OBSERVED: El GOOD ❑ ACCEPTABLE ❑ POOR <br /> MAINTENANCE AND REPAIRS <br /> PROBLEMS NOTED: <br /> ❑ (60)NONE 0(61)ACCESS ROAD NEEDS MAINTENANCE 11(62)CATTLE DAMAGE <br /> O(63)BRUSH ON:UPSTREAM SLOPE/BEACH,CREST,DOWNSTREAM SLOPE,TOE <br /> El(64)RODENT ACTIVITY ON:UPSTREAM SLOPE/BEACH,CREST,DOWNSTREAM SLOPE,TOE <br /> 0(65)OTHER <br /> Per Steve Carino,the temporary access berm and culvert to right of the drain outlets will be removed. <br /> #42,#49:Disturbed areas adjacent to the South Diversion Ditch Drop Structure that are not protected by riprap were seeded in 2019,but due <br /> to drought conditions vegetation establishment is poor to date and erosional rilling has progressed along the south side of the structure to the <br /> point that mitigation is required. <br /> CONDITIONS OBSERVED: 0 GOOD ® ACCEPTABLE 0 POOR <br /> OVERALL CONDITIONS <br /> Based on this Inspection and recent file review,the overall surficlal condition Is determined to be: <br /> ❑ SATISFACTORY El CONDITIONALLY SATISFACTORY 0 UNSATISFACTORY <br /> Page 2 of 4 <br />