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DAM NAME: San Luis Tailing Dam DATE OF REPORT: 08 25 20 <br /> TAILING DAM INSPECTION FORM <br /> Directions: Mark an ✓for conditions found and underline words that apply <br /> SEEPAGE AND DRAIN OUTFALL <br /> PROBLEMS NOTED: ❑(30)NONE ❑(31)SATURATED EMBANKMENT AREA ❑(32)SEEPAGE EXITS ON DAM <br /> ❑(33)SEEPAGE EXITS AT POINT SOURCE Z(34)MINOR PONDING OF PIPE LEAKAGE AT TOE <br /> 1 DRAIN OUTFALL SEEN: ❑YES 0 NO ❑(35)FLOW ADJACENTTO DRAIN PIPE ❑(36)DRAIN OUTFLOW TURBID <br /> ❑(37)DRAIN DRY/OBSTRUCTED ❑(38)OTHER: <br /> SHOW LOCATION OF DRAIN ON SKETCH <br /> ' AND INDICATE AMOUNT AND QUALITY OF SEEPAGE <br /> See Figure 1 for location. Table 1 summarizes toe drain discharge rates over reporting period. Photos 4 and 5 show conditions at time of inspection: toe <br /> drain manifold collection pipe was connected so drainage from pipes could not be directly observed.Minor leakage from outfall pipe was observed and is <br /> causing ponding in toe area. <br /> CONDITIONS OBSERVED: ❑GOOD 0 ACCEPTABLE ❑POOR <br /> STORM WATER MANAGEMENT SYSTEM <br /> PROBLEMS NOTED: Z(40)NONE ❑(41)NO EMERGENCY SPILLWAY <br /> ❑(42)EROSION AT DROP STRUCTURE ❑(43)CONCRETE DETERIORATED/UNDERMINED ❑(45)STRUCTURE MAY BE TOO SMALL <br /> ❑(46)DIVERSION CHANNEL EROSION ❑(47)INADEQUATE CHANNEL FLOW CAPACITY ❑(48)CHANNEL FLOW OBSTRUCTED <br /> ❑(49)OTHER: Photos 9 through 15 show conditions of South Diversion Ditch South Diversion Ditch Drop Structure.Drop Structure project was <br /> completed in 2019. Drop Structure and South Diversion Ditch appear to be in good condition. Sediment accumulation due to storm-water runoff from <br /> right groin area continues to be a minor maintenance/access issue in the toe area. <br /> ' CONDITIONS OBSERVED: ❑GOOD ❑ACCEPTABLE ❑POOR <br /> MONITORING <br /> EXISTING INSTRUMENTATION FOUND: ❑(50)NONE ❑(51)GAGE ROD IN POOL AREA ❑(52)PIEZOMETERS <br /> ❑(53)SEEPAGE WEIRS/FLUMES ❑(54)SURVEY MONUMENTS 0(55)OTHER: Underseepage flows <br /> MONITORING OF INSTRUMENTATION: ❑(56)NO 0(57)YES <br /> PERIODIC INSPECTIONS BY: ❑(58)OWNER ❑(59)ENGINEER <br /> See Figure 2 for piezometer measurements-all instruments remain dry. See Figure 3 for underdrain flow rates;average underseepage flow rates <br /> (measured at outfall pipe)over past 2 years have decreased by about 5 gpm compared to historic(5 previous years)record,and vary between 32 and 37 <br /> gpm over current reporting period. <br /> CONDITIONS OBSERVED: 0 GOOD ❑ACCEPTABLE ❑ POOR <br /> ' MAINTENANCE AND REPAIRS <br /> PROBLEMS NOTED: ❑(60)NONE ❑(61)ACCESS ROAD NEEDS MAINTENANCE ❑(62)CATTLE DAMAGE <br /> ❑(63)BRUSH ON: UPSTREAM SLOPE/BEACH,CREST,DOWNSTREAM SLOPE,TOE <br /> ❑(14)RODENT ACTIVITY ON: UPSTREAM SLOPE/BEACH,CREST,DOWNSTREAM SLOPE,TOE <br /> 0(65)OTHER: Consider re-directing surface runoff from right lower groin away from d/s toe area to prevent deposition of sediment. Disturbed areas <br /> adjacent to the South Diversion Ditch Drop Structure that are not protected by riprap were seeded in 2019,but due to drought conditions vegetation <br /> establishment is poor to date. Maintain these disturbed areas as needed. If surface erosion rilling or gullying develops,reseeding may be necessary. <br /> Repair minor tearing of exposed liner on downstream left groin ditch.Repair minor leakage from toe drain outfall pipe between manifold and exit. <br /> CONDITIONS OBSERVED: ❑GOOD 2 ACCEPTABLE ❑ POOR <br /> OVERALL CONDITIONS <br /> Based on this inspection and recent file review,the overall surficial condition is determined to be: <br /> 0 SATISFACTORY ❑CONDITIONALLY SATISFACTORY ❑ UNSATISFACTORY <br /> Page 2 of 4 <br />