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DAM NAME: San Luis Tailing Dam DATE OF REPORT:July 5, 2023 <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 ❑(31)SATURATED EMBANKMENT AREA ❑(32)SEEPAGEEXITSONDAM <br /> ❑(33)SEEPAGE EXITS ATPOINT SOURCE N(34)MINOR PONDING OF PIPE SEEPAGE <br /> ATTOE <br /> DRAIN OUTFALLSEEN: N YES ❑ NO <br /> ❑(35)FLOWADJACENTTODRAINPIPE ❑(36)DRAIN OUTFLOW TURBID ❑ (37)DRAIN DRY/OBSTRUCTED <br /> ❑(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 /> CONDITIONS OBSERVED: ❑ GOOD X ACCEPTABLE ❑ POOR <br /> STORMWATER MANAGEMENT SYSTEM <br /> PROBLEMS NOTED: <br /> ❑ (40)NONE ❑(41)NO EMERGENCY SPILLWAY N(42)EROSION AT DROP STRUCTURE <br /> ❑(43)CONCRETE DETERIORATED/UNDERMINED ❑(45)STRUCTURE MAY BETOO SMALL <br /> ❑(46)DIVERSION CHANNEL EROSION 0(47)INADEQUATE CHANNEL FLOWCAPACITY 0(48)CHANNEL FLOW OBSTRUCTED <br /> ®(49)OTHER Rilling along both sides of drop structure is advancing-continue monitoring and begin planning mitigation strategy. <br /> South diversion channel and downstream toe runoff collection swales are in good condition except for choking of culvert south of toe <br /> drain(Photo 12). Mitigation of erosional rilling at 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 ® (52)PIEZOMETERS <br /> ❑(53)SEEPAGE WEIRS/FLUMES ❑(54)SURVEY MONUMENTS ®(55)OTHER Underdrain flow <br /> MONITORING OF INSTRUMENTATION: <br /> ❑(56)NO WEIRS/FLUMES N(57)YES <br /> PERIODIC INSPECTIONS BY: <br /> N (58)OWNER N (59)ENGINEER <br /> Piezometers remain dry. Average underdrain flow measurements from 2020-23(31.7 gpm)are lower than from 2016-2023(34.0 gpm). <br /> Reduction is likely due to ongoing severe regional drought,but continue jetting and video inspection program. <br /> CONDITIONS OBSERVED: N GOOD ❑ ACCEPTABLE ❑ POOR <br /> MAINTENANCE AND REPAIRS <br /> PROBLEMSNOTED: <br /> ❑ (60)NONE ❑(61)ACCESS ROAD NEEDS MAINTENANCE ❑(62)CATTLE DAMAGE <br /> ❑(63)BRUSH ON:UPSTREAM SLOPEBEACH,CREST,DOWNSTREAM SLOPE,TOE <br /> ❑(64)RODENT ACTIVITY ON:UPSTREAM SLOPE/BEACH,CREST,DOWNSTREAM SLOPE,TOE <br /> ®(65)OTHER <br /> #48:Clear toe runoff channel culvert immediately south of toe drain outfall pipe. <br /> #49:Disturbed areas adjacent to the South Diversion Ditch Drop Structure that are not protected by riprap were seeded in 2019,but due to <br /> drought conditions vegetation establishment is poor to date and erosional rilling has progressed along both sides of the structure to the point <br /> that mitigation is required. <br /> CONDITIONS OBSERVED: ❑ GOOD X ACCEPTABLE X POOR <br /> OVERALL CONDITIONS <br /> Based on this inspection and recentfile review,the overall surficial condition is determined to be: <br /> ❑ SATISFACTORY N CONDITIONALLY SATISFACTORY ❑ UNSATISFACTORY <br /> Page 2 of 4 <br />