STATE OF CALIFORNIA CALIFORNIA NATURAL RESOURCES AGENC DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Darn Seeger (Nicasio) Darn No. 33-8 County Marin Type of Dam ERTH Type of Spillway Concrete side channel ogee Water is 1.3 feet above the spillway crest and 13.7 feet below the dam crest. Weather Conditions Overcast with light rain Contacts Made Lucy Croy, Trinity Leonard, Carl Sanders and Ronnie Chasteen during the inspection Reason for Inspection Periodic Evaluation Important Observations, Recommendations or Actions Taken Vegetation control continues to improve and is now excellent. As requested, additional clearing of the toe and lower right groin has been performed to improve access for monitoring by MMWD staff. The most 24?inch outlet control valve has been repaired, was fully cycled during this inspection, and is now fully functional. repeated my request that ruts within the lower access road across the face of the dam be filled and graded to prevent rainfall from ponding on the face. Conclusions From the known information and visual inspection, the darn, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments 123m The visible portions of the upstream face, crest, face, and abutments are in satisfactory condition with no indication of surficial distress or instability. The upstream face is armored with large boulder riprap that remains in satisfactory condition. I repeated my request that ruts within the lower access road across the face of the dam be filled and graded to prevent rainfall from ponding on the face. Vegetation control is excellent, and the crest, groins, and both faces of the embankment are covered with ankle tall grass and other low ground cover that protect against erosion without hindering inspection and monitoring for seepage and other defects. As requested, additional clearing of the toe and lower right groin has been performed to improve access for monitoring by MMWD staff. Similar to the previous inspections, rodent control also remains satisfactory and little indication of rodent activity was observed within the embankment footprint. Rodent activity is abundant within the adjacent natural ground but the embankment surface appears to be too rocky to attract burrowers. Spillway The approach, control section, and exit channel were open and clear. The spillway was flowing approximately 1 .3 feet deep across the entrance weir. Flow within the concrete spillway chute appeared normal, and there was nothing to suggest a significant flaw within the concrete spillway channel The current design storm, prepared in 1985, is for a 40,000 year return period . ?-5.447? ?/5125; Age! 7 Inspected by J. Lowe's? Photos taken? Yes ND Date of Inspection 7 cc for Owner/Book Date of Report 10 February 2017' Jill) DWR1261 (Rev. 10:09) Sheet 1 of 5 $06 givtf if INSPECTIO. 3F DAM AND RESERVOIR IN STATUS Name of Dam Seeger (Nicasio) Dam No. 33-8 Date of Inspection 7 February 2017 Observations and Comments (~492 I sq mi) from the 35.9 square mile drainage area. The spillway capacity is ~30,000 which is greater than the peak inflow. Total freeboard is 15 feet and the residual freeboard for the design storm is 8.6 feet. Freeboard is satisfactory. Four 24~inch diameter butterfly valves on the inclined inlet structure provide upstream control for the fully encased normally pressurized outlet. The four mechanically operated valves are located at elevations 157.0?, 146.0?, 126.0', and 90.0?. A pair of geared head drive 24?inch butterfly valves arrayed in series provides control. The most 24?inch outlet control valve has been repaired, was fully cycled during this inspection, and is now fully functional. None of the remaining outlet controls were cycled during this inspection, but all upstream and controls were partially cycled during the 5 April 2016 inspection. Seepage Rainfall prevented evaluation for minor seepage. No evidence of significant seepage was observed within the face, groins, or abutments. The seepage weir and drainage channel beyond the weir were inundated during the inspection and couid not be evaluated. Instrumentation consists of: a Ten (10) survey monuments. Survey monuments were installed to monitor post construction settlement of the crest and settlement and displacement of the crest following significant seismic events. Survey monuments have been read at irregular intervals. 0 One (1) seepage-measuring weir. The seepage?monitoring weir was installed to monitor flow beneath the toe of the embankment and is read The ten survey monuments consist of seven (7) crest monuments, two (2) auxiliary monuments, and one (1) spillway monument. The seven survey monuments are located along the centerline of the embankment crest. Two (2) benchmarks are used to locate and reference the survey monuments. The latest instrumentation data was received from the owner on December 16. 2015, and no new data has been received since that time. The last instrumentation review is presented in the 5 April 2016 inspection report, and is not repeated here; direct the reader to the earlier report for a detailed explanation of the instrumentation monitoring the dam, and the performance of the dam as reflected in the 16 December 2015 submittal. The conclusion of the April 2016 review was that, "Based on the data submitted the dam appears to be performing satisfactorily, and no additional instrumentation is believed necessary at this time". DWR1261(rev.10i09) Sheet 2 of 5 INSPECTIO. JF DAM AND RESERVOIR IN CE. STATUS Name of Dam Seeger (Nicasio) Dam No. 33-8 Date of Inspection 7 February 2017 The upstream face and the spillway control weir as viewed from the outlet tower access road. Flow over the weir is approximately 1.3? deep. ii": The face as viewed from the access road to the base of the dam. Vegetation control is excellent and access for inspection and monitoring for seepage and other defects is unimpeded. Sheet 3 of 5 INSPECTIO. JF DAM AND RESERVOIR IN IFIED STATUS Name of Dam Seeger (Nicasio) Dam No. 33-8 Date of Inspection 7 February 2017 repeated my request that ruts within the lower access road across the face of the dam be filled and graded to prevent rainfall from ponding on the face.-.-4-.. ,r eta-.11., . .1 21111.4 ?231$ I11.11.. 11,; a: H31 - ?1 ?aw, -. . 1 .(u?rl 5131' h? a. . -- .. 'Jhw .29the dam showing the seepage weir location (circled) which was inundated by high spillway flow. Sheet 4 of INSPECTIC 3F DAM AND RESERVOIR IN CE STATUS Name of Dam Seeger (Nicasio) Dam No. 33-8 Date of Inspection 7 February 2017 Spillway flow leaving the concrete spillway channel and entering the unlined exit channel, above. The bottom photograph shows the recently repaired most outlet control valve. A recently installed and very well constructed guardrail installed to protect workers operating the outlet control valves. DWR1261(rev.10f09) Sheet 5 of 5 STATE OF CALIFORNIA CALIFORNIA NATURAL RESOURCES AGENCY DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Seeger (Nicasio) Dam No. 33-8 County Marin Type of Dam ERTH Type of Spillway Concrete side channel ogee Water is 0.1 feet above the spillway crest and 15 feet below the dam crest. Weather Conditions Clear and mild Contacts Made Alex Anaya, Carl Sanders, and Ronnie Chasteen during the inspection Reason for Inspection Periodic Evaluation Important Observations, Recommendations or Actions Taken Vegetation control remains quite good, and continues to improve, but some additional clearing of the toe and lower right groin is desirable to improve access for monitoring by MMWD staff. The most 24?inch outlet control valve is inoperative, directed Mr. Anaya to repair or replace the valve as quickly as possible, to restore the outlet to full function. The seepage weir and drainage channel beyond the weir have been cleared of sediment, leaves, and other debris, as requested. Ruts within the lower access road across the face of the dam should be filled and graded to drain away from the face. Conclusions From the known information and visual inspection, the dam, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments Da_m The visible portions of the upstream face, crest, face, and abutments are in satisfactory condition with no indication of surficial distress or instability. The upstream face is armored with large boulder riprap that remains in satisfactory condition. Ruts within the lower access road across the face of the dam should be filled and graded to drain away from the face. Vegetation control is generally quite good, and the crest, groins, and both faces of the embankment are covered with ankle tall grass and other low ground cover that protect against erosion without hindering inspection and monitoring for seepage and other defects. Some additional clearing of the toe and lower right groin is desirable to improve access for monitoring by MMWD staff. Similar to the previous inspections, rodent control also remains satisfactory and little indication of rodent activity was observed within the embankment footprint. Rodent activity is abundant within the adjacent natural ground but the embankment surface appears to be too rocky to attract burrowers. Sgillway The approach, control section, and exit channel were open and clear. The spillway concrete structure remains in satisfactory condition and is free of significant cracks or spalls indic/atnreg excessive stress or deterioration. inspected by {2L--l:owe ?2 Photos taken? Yes N0 Date of Inspection 5 April 2015 cc for Owner/Book Date of Report 6 April 2016 DWR 1261 (Rev. IOIOQ) Sheet DAM AND RESERVQIR IN GER STATUS Name of Dam SESQEF (Nicasio) Dam No. 33-8 Date of Inspection 5 April 2016 Observations and Comments Seepage Total freeboard is 15 feet and the residual freeboard for the design storm is 8.6 feet. Freeboard is satisfactory. Four 24-inch diameter butterfly valves on the inclined inlet structure provide upstream control for the fully encased normally pressurized outlet. The four mechanically Operated vaives are located at elevations 157.0?, 146.0?, 126.0?, and 90.0?. A pair of geared head drive 24?inch butterfly valves arrayed in series provides control. All upstream and controls were partially cycled, and all except for the most 24-inch butterfly valve function properly. The most outlet control valve is inoperative due to an apparent failure of the geared head drive. I directed Mr. Anaya to repair or replace the valve as quickly as possible, to restore the outlet to fuil function. The face, groins, and abutments were dry and free of evidence of any seepage. The seepage weir and drainage channei beyond the weir have been cleared of sediment, leaves, and other debris, as requested. Ciear seepage flow at the toe weir was roughly 5 and is within historic values. Instrumentation consists of: a Ten (10) survey monuments. Survey monuments were installed to monitor post construction settiement of the crest and settiement and displacement of the crest following significant seismic events. Survey monuments have been read at irregular intervals. a One (1) seepage-measuring weir. The seepage?monitoring weir was installed to monitor flow beneath the toe of the embankment and is read The ten survey monuments consist of seven (7) crest monuments, two (2) auxiliary monuments, and one (1) spillway monument. The seven survey monuments are located along the centerline of the embankment crest. Two (2) benchmarks are used to locate and reference the survey monuments. The iatest instrumentation data was received from the owner on December 16, 2015; survey data covers the reporting period between January 1982 and September 2015. There is no indication of increasing settlement of the embankment in the past fifteen years, and the apparent movement indicated by the survey data is most likely instrumentation or reading error. Lateral displacement data shows quite a bit of scatter, but again, there does not appear to be any continuing long-term trend of dispiacement. The owner reports that, ?Seeger Dam (Nicasio Lake) is trending toWard stabilization: settlement of -0. 13 ft. (maximum) and alignment of -O. 13 ft. direction; maximum)? Ciear seepage measured at the monitoring weir correlates closely to rainfali; in the absence of rainfall seepage drops to essentially zero. Normal peak seepage, in the range of 40 or more gpm, quickiy falls to near zero foiiowing the secession of winter storms. Based onthe data submitted the dam appears to be performing satisfactorily, and no additional instrumentation is believed necessary at this time. DWR1251(rev.10i09) 'Sheet 2 of- 4 INSPECTION DAM AND RESERVOIR IN IED STATUS Name of Dam Seeger (Nicasio) Dam No. 33-8 Date of Inspection 5 April 2016 The upstream face as viewed from the upstream end of the spillway channel. The large boulder riprap face protection remains in good condition. if"; *5 h- .I 1, The face, spillway outflow channel, and stilling basin. The outlet discharges into the stilling basin just upstream of the drain pipe visible in the bottom center of the photograph. DWR1261 (rev. 10mg) Sheet 3 of 4 INSPECTION DAM AND RESERVOIR IN STATUS Name of Darn Seeger (Nicasio) Dam No. 33-8 Date of Inspection 5 April 2016 - - . . . Aw . was? n. I I no A closer look at the lower right face and toe. Overhanging vegetation indicated by the yellow line should be removed to improve access for monitoring by MMWD staffwaft. i -: .I . .. The spillway channel looking in the direction. The spillway concrete structure remains in satisfactory condition, and is free of significant cracks or spalls indicative of excessive stress or deterioration. Sheet 4 of 4 STATE OF CALIFORNIA CALIFORNIA NATURAL RESOURCES DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Seeger (Nicasio) Dam No. 33?8 County Marin Type of Dam ERTH Type of Spillway Concrete side channel ogee Water is 0.1 feet above the spillway crest and 15 feet below the dam crest. Weather Conditions Clear and mild Contacts Made Alex Anaya and Ben Bauer during the inspection Reason for Inspection Periodic Evaluation Important Observations, Recommendations or Actions Taken Vegetation control is generally quite good, but some additional clearing of the toe and right groin is desirable to improve access for monitoring by MMWD staff. Bushes and brush piles also need to be cleared from the access road to the outlet outfall to permit unimpeded access to the outlet controls. The seepage weir and drainage channel beyond the weir are obstructed with sediment, leaves, and other debris, which make meaningful seepage measurements impossible. i asked Mr. Anaya to clear the weir and weir channel as required to allow for accurate seepage measurements. There are no prior outstanding administrative requirements. The total class weight of 24 appears satisfactory. Conclusions From the known information and visual inspection, the dam, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments Dam The visible portions of the upstream face, crest, face, and abutments are in satisfactory condition with no indication of surficial distress or instability. The upstream face is armored with large riprap that remains in satisfactory condition. Vegetation control is generally quite good, and the crest, groins, and both faces of the embankment are covered with ankle tall grass and other low ground cover that protect against erosion without hindering inspection and monitoring for seepage and other defects. Some additional clearing of the toe and right groin is desirable to improve access for monitoring by MMWD staff. Bushes and brush piles also need to be cleared from the access road to the outlet outfall to permit unimpeded access to the outlet controls. Similar to the previous inspections, rodent control also remains satisfactory and little indication of rodent activity was observed within the embankment footprint. Rodent activity is abundant within the adjacent natural ground but the embankment surface appears to be too rocky to attract burrowers. Spillway The approach, control section, and exit channel were clear and unobstructed. The spillway concrete structure remains in satisfactory condition, and is free of significant cracks or spells indicative of excessive stress or deterioration. The current design storm prepared In 1985, is for a 40,000 year return period producing 17 ,647 (~492 sq mi) from the 35.9 square mile drainage area The current TCW for this dam? Is 24 --The Inspected by Lowe [vgy 2 Photos taken? Yes No? Date of Inspection 24 February 2015 I I cc for Owner/Book Date 01? Report 27 February 2015'/1 4I DWR 1261 (Rev. 10/09) Sheet DAM AND RESERVOIR IN FIED STATUS Name of Dam Seeger Dam No. 33?8 Date of inspection 24 February 2015 Observations and Comments Seepage spillway capacity is ~30,000 which is greater than the peak inflow. Total freeboard is 15 feet and the residual freeboard for the design storm is 8.6 feet. Freeboard is satisfactory. Four 24~inch diameter butterfly valves on the inclined inlet structure provide upstream control for the fully encased normally pressurized outlet. The four mechanically Operated valves are located at elevations 157.0?, 146.0?, 126.0?, and 90.0?. A pair of geared head drive 24?inch butterfly valves arrayed in series provides control. All upstream controls were partially cycled; fuiiy cycling the upstream controls was not performed because the water treatment plant was in operation at the time of inspection. Both controls were fully cycled, and water was released from the outlet at full reservoir head. There did not appear to be any excessive or concerning cavitation or vibration of the control valves during either partial or full flow. The face, grains, and abutments were dry and free of evidence of any seepage. The seepage weir and drainage channel beyond the weir are obstructed with sediment, leaves, and other debris, which make meaningful seepage measurements impossible. I asked Mr. Anaya to clear the weir and weir channel as required to allow for accurate seepage measurements. Seepage flow at the toe weir was roughiy 5 gpm. Instrumentation consists of: 9 Ten (10) survey monuments. Survey monuments were installed to monitor post construction settlement of the crest and settlement and displacement of the crest following significant seismic events. Survey monuments have been read at irregular intervals. . a One (1) seepage-measuring weir. The seepage-monitoring weir was installed to monitor flow beneath the toe of the embankment and is read The ten survey monuments consist of seven (7) crest monuments, two (2) auxiliary monuments, and one (1) spillway monument. The seven survey monuments are located along the centerline of the embankment crest. Two (2) benchmarks are used to locate and reference the survey monuments. Survey data transmitted on September 24, 2014 was reviewed in the October 30, 2014 inspection report. DWR1261{rev.10l09) Sheet 2 of 4 DAM AND RESERVOIR IN FIED STATUS Name of Dam Seeger (Nicasio) Darn No. 33-8 Date of Inspection 24 February 2015 The upstream face as viewed from the right abutment, above, and the face as viewed from the lower left abutment, below. Vegetation control is generally quite good, but some additional clearing of the toe and right groin is desirable to improve access for monitoring by MMWD staff. DWR1261(rev.10f09) Sheet 3 of DAM AND RESERVOIR IN FIED STATUS Name of Dam Seeger (Nicasio) Dam No. 33-8 Date of Inspection 24 February 2015 debris, which make meaningful seepage measurements impossible. Flow direction is indicated by the arrowBoth controls were fully cycled, and water was released from the outlet at full reservoir head. Sheet 4 of 4 STATE OF CALIFORNIA IFORNIA NATURAL RESOURCES AGENCY ARTIVIENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Darn Seeger (Nicasio) Dam No. 338 County Marin Type of Dam Concrete gravity Type of Spillway Concrete side channel ogee Water is feet above spillway crest and 22 feet below dam crest. Weather Conditions Sunny and mild Contacts I?v?lade Carl Gowan before and Alex Anaya, Carl Sanders, Ben Bauer during the inspection Reason for Inspection Periodic Maintenance Inspection Important Observations, Recommendations or Actions Taken There are no prior outstanding administrative requirements. The total class weight of 24 appears satisfactory. Conclusions From the known information and visual inspection, the dam, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments Dam The visible portions of the upstream face, crest, face, and abutments are in satisfactory condition with no indication of surficial distress or instability. The upstream face is armored with large riprap that remains in satisfactory condition. Vegetation control is satisfactory. No undesirable woody vegetation was noted on the embankment or along the groins. The crest, groins, and both faces of the embankment are covered with ankle tall grass and other low ground cover that protects against erosion without hindering inspection and monitoring for seepage and other defects. Rodent control also remains satisfactory and little indication of rodent activity was observed within the embankment footprint. Spillway The approach, control section, and exit channel were clear and unobstructed. The spillway structure concrete remains in satisfactory condition, and is free of significant cracks or spalls indicative of excessive stress or deterioration. Minor vegetation emerging in the spillway channel construction joints needs to be removed. The current design storm, prepared in 1985, is for a 40,000 year return period producing 17,647 (~492 I sq mi) from the 35.9 square mile drainage area. The spillway capacity is ~30,000 which is greater than the peak inflow. Total freeboard is 15 feet and the residual freeboard for the design storm is 8.6 feet. Freeboard is satisfactory. Outlet Four 24-inch diameter butterfly valves on the inclined inlet structure provide upstream control for the fully encased normally pressurized outlet. The four mechanically operated valves are located at elevations 157.0?, 146.0?, 126.0', and 90.0'. A pair of geared head drive 24-inch butterfly valves provides control. All upstream controls (No. 1 with handheld hydraulic power head; No. 2, 3, and 4 manually) and both controls were cycled during the inspection. All controls were found to be in satisfactory working condition. inspected by L. Singh . Photos taken? Yes NO Date of Inspection 10/30/2014 cc for Owner! Book Date of Report ?1 1/20/2014 DWR 1261 (Rev. 10mg) Sheet( 1 Of 3 INSPECTION AND RESERVOIR IN STATUS Name ofDam Seeger(Nicasio) Dam No. 33?8 Date of Inspection 10/30/2014 Observations and Comments Seepage The face, groins, and abutments were dry and free of evidence of any seepage. Seepage ?ow at the toe weir was ~0.25 inch over 90 degree v~notch which corresponds to 35 and is considered normal and within historic limit. Instr. Instrumentation consists of: Ten (10) survey monuments. Survey monuments were installed to monitor post construction settlement of the crest and settlement and displacement of the crest following significant seismic events. One (1) seepage?measuring weir. The seepage-monitoring weir was installed to monitor flow beneath the toe of the embankment and is read The most recent instrumentation report was transmitted on September 24, 2014. The report included weir flow plot, survey data in tabular and graphical format, and a brief evaluation of the data. Seepage fiow is consistent with previous year readings and is generally responding to the reservoir water elevation and rainfall. During the current reporting period of 2013?14, seepage varied between 0 to 30 and is considered within acceptable range. Monument Survey are performed annually and the most recent survey were performed in September 2014. Review of the data/plots indicates that both, the settlement and horizontal movement are pr0gressively decreasing and the embankment is trending towards stabilization. The existing instrumentation are judged adequate at this time. Sheet 2 of 3 INSPECTION AND RESERVOIR IN STATUS Name ofDam Seeger(Nicasio) Darn No. 33-8 Date of Inspection 10/30/2014 1. A View of the upstream face and the spillway approach channel as seen from the left abutmentBoth controls (installed in series) being cycled during the inspection. DWR1261(rev.10l09) Sheet 3 of STATE OF CALIFORNIA CALIFORNIA NATURAL RESOURCES AGENCY DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Darn Seeger (NicaSiO) Dam No. 33-8 County Marin Type of Dam ERTH Type of Spillway Concrete side channel ogee Water is 4 feet below the spillway crest and 19 feet below the dam crest. Weather Conditions Clear and mild Contacts Made Ben Bauer during the inspection Reason for Inspection Periodic outlet valve cycling and evaluation Important Observations, Recommendations or Actions Taken This inspection was performed to inspect and evaluate the condition of the outlet controls. There have been no substantive changes in the condition of the dam and appurtenances since the previous annual inspection performed on April 24, 2013. Observations, recommendations, or actions taken during the April 2013 inspection remain as presented in the April report, the details of which are not repeated here. Conclusions From the known information and visual inspection, the dam, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments Outlet Four 24?inch diameter butter?y valves on the inclined inlet structure provide upstream control for the fully encased normally pressurized outlet. The four mechanically operated valves are located at elevations 157.0'. 146.0', 126.0?, and?90.02 A pair of geared head drive 24-inch butterfly valves arrayed in series provides control. Before this inspection, these valves were last cycled in the presence of DSOD staff between July 7, 2009 and July 14, 2009. Upstream control No. 1 was cycled using a handheld E.H. Wachs hydraulic power head; upstream controls No. 2, 3, and 4 are cycled manually. Both controls were cycled manually with the aid of a large ratchet wrench. I All upstream and controls functioned well and are in satisfactory working condition. i Ttde 2. a me 7?03 Inspected by J. Lowe Photos taken? YES N0 Date of Inspection 13 August 2013 or: for Owner/Book Date of Report 26 August 2013 (HIM h} DWR1261 (Rev. 10:09) Sheet 1 of 3 T: m: We INSPECTION DAM AND RESERVOIR IN CER. .. STATUS Name of Dam Seeger (Nicasio) Dam No. 33?8 Date of Inspection 13 August 2013 Upstream controls No. 2, 3, and 4, in the foreground of the top photograph, are cycled manually. Control No. 1, which is painted red, is cycled using a handheld E.H. Wachs P-2 hydraulic power head (above and below). Sheet 2 of 3 INSPECTION b. DAM AND RESERVOIR IN CER . .. IED STATUS Name of Dam Seeger (Nicasio) Dam No. 33-8 Date of Inspection ?13 August 2013 This pair of geared head drive 24?inch butterfly valves arrayed in series provides control. The View is in the direction and the outlet outfall is just behind Mr. Bauer. Sheet 3 of STATE OF CALIFORNIA CALIFORNIA NATURAL RESOURCES AGENCY DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Seeger (Nicasio) Dam No. 33-8 County Marin Type of Dam ERTH Type ofSpillway Concrete side channel ogee Water is 3 feet below the spillway crest and 18 feet below the dam crest. Weather Conditions Clear and mild Contacts Made Carl Gowan and Carl Sanders during the inspection Reason for Inspection Periodic Evaluation Important Observations, Recommendations or Actions Taken Vegetation control is generally satisfactory but some additional clearing of the toe and right groin is desirable to improve access for monitoring by MMWD staff. Bushes also need to be cleared from the access road to the outlet outfall to permit unimpeded access to the outlet controls. A single weep drain in the upper right spillway wall is flowing in the twenty to thirty range. As the spillway was constructed within bedrock, and seepage from the drain is clear, there appears to be little cause for concern at this time. asked Mr. Gowan to confirm the construction particulars in the vicinity of the drain, and to take corrective action if necessary. There are no prior outstanding administrative requirements. The total class weight of 24 appears satisfactory. Conclusions From the known information and visual inepection, the dam, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments Dam The visible portions of the upstream face, crest, face, and abutments are in satisfactory condition with no indication of surficial distress or instability. The upstream face is armored with large riprap that remains in satisfactory condition. Vegetation control is generally satisfactory, and the crest, groins, and both faces of the embankment are covered with ankle tall grass and other low ground cover that protect against erosion without hindering inspection and monitoring for seepage and other defects. Occasional emerging trees and bushes occupy the embankment, but these are cleared as a part of normal annual maintenance. Some additional clearing of the toe and right groin is desirable to improve access for monitoring by MMWD staff. Bushes also need to be cleared from the access road to the outlet outfall to permit unimpeded access to the outlet controls. Similar to the previous inspections, rodent control also remains satisfactory and little indication of rodent activity was observed within the embankment footprint. Rodent activity is abundant within the adjacent natural ground but the embankment surface appears to be too rocky to attract burrowers. Spillway The approach, control section, and exit channel were clear and unobstructed. The spillway concrete structure remains in satisfactory condition, and is free of significant cracks or spalls indicative of excessive stress or deterioration. Clear seepage with rates well below 1 was flowing from various weep drains along the lower Law?? lnspected by J. Lowe ?fr 7-023 Photos taken? Yes No Date of Inspection 24 April 2013 '1 L. cc for Owner/Book Date of Report 26 April 2013 J, I3 DWR 1261 (Rev. 10mg) Sheet 1 0W6 3v '7 INSPECTION Of" DAM AND RESERVOIR IN STATUS Name of Dam Seeger (Nicasio) Dam No. 33-8 Date of inspection 24 April 2013 Observations and Comments Outlet Seepage instr. spillway walls and invert. A single drain in the upper right spillway wall is flowing at a significantly higher rate, in the twenty to thirty range. As the spiilway was constructed within bedrock, and seepage from the higher flow rate drain is clear, there appears to be little cause for concern at this time. asked Mr. Gowan to confirm the construction particulars in the vicinity of the this drain, and to take corrective action if necessary. Total freeboard is 15 feet and the residual freeboard for the design storm is 8.6 feet. Freeboard is satisfactory. Four 24?inch diameter butterfly valves on the inclined inlet structure provide upstream control for the fully encased normally pressurized outlet. The four mechanically operated valves are located at elevations 157.0?, 146.0?, 126.0?, and 90.0?. A pair of geared head drive 24-inch butterfly valves arrayed in series provides control. None of the outlet controls were cycled during this inspection but they are scheduled to be cycled later in the year. All upstream controls were cycled on the July 7, 2009 and both controls were cycled on the July 14, 2009. All of the outlet controls were found to be in satisfactory operating condition. The face, groins, and abutments were dry and free of evidence of any seepage. Seepage flow at the toe weir was roughly 3 gpm. Instrumentation consists of: 0 Ten (10) survey monuments. Survey monuments were installed to monitor post construction settlement of the crest and settlement and displacement of the crest following significant seismic events. Survey monuments have been read at irregular intervals. a One (1) seepage-measuring weir. The seepage?monitoring weir was installed to monitor flow beneath the toe of the embankment and is read The ten survey monuments consist of seven (7) crest monuments, two (2) auxiliary monuments, and one (1) spillway monument. The seven survey monuments are located along the centerline of the embankment crest. Two (2) benchmarks are used to locate and reference the survey monuments. Survey data for the period from January 1982 through January 2011 was reviewed. The maximum cumulative settlement since the original survey of October 1961 was reported as -0.127 feet (1.5 inches) at monument M4 in October of 1990. The maximum increase in settlement within the recording period is 0.047 feet (0.6 inches) at monument M-5, also in October of 1990. Alignment readings are presented and are quite steady up until 1992, after which they make a shift in the direction beginning in 2000. The shift continues through to the 2011 readings, with maximum total displacements of up to 0.4 inches between 1992 and 2011. A new survey instrument was introduced in December of 2005, and the change of instrument, reading and reporting errors, or a change in anchor monument locations are the most likely explanations for the deviations. Several years of consistent data will be required before any meaningful trends can be ascertained, but based on data prior to 1992 the dam remains stable with regard to alignment. The seepage-monitoring weir is located between the spillway exit channel and the left toe. Seepage data for the period from January 2001 through January 20i1 was reviewed. The DWR 1261 (rev. torus) Sheet 2 of 4 INSPECTION OI- DAM AND RESERVOIR IN CERTII STATUS Name of Darn Seeger (Nicasio) Dam No. 33-8 Date of inspection 24 April 2013 Observations and Comments maximum measured seepage during the data reporting period was just over 40 gpm, which occurred in 2005, 2007, 2008, and 2009. A recorded seepage of 100 was reported in the 11 January 1996 which noted that this value was greater than the previous high rate of 64 in 1985, and may be attributable to heavy rainfall. In their April 12, 2012 instrumentation data submittal letter the owner reports, ?The Seeger Dam {Nicasio Lake) weir flow is consistent with historic readings. Seeger Dam (Nicasio Lake is trending toward stabilization: Settlement of -0. 12 ft (maximum) and alignment of -0. 12 feet direction; maximum). i find no alarming seepage trends or significant actual displacement reported for the data period. 5?5" - "ChVegetation control is generally satisfactory but some additional clearing of the toe and right groin is desirable to improve access for monitoring by MMWD staff. The View is from the outlet control access road. DWR1261(rev.10i09) Sheet 3 of 4 INSPECTION DAM AND RESERVOIR IN CERTII .ED STATUS Name of Dam Seeger Dam No. 33-8 Date of Inspection 24 April 2013 A closer look at the right groin and toe. Clearing trees, bushes and low hanging limbs will open up these important areas to improved monitoring for seepage and other defects.II 69? at". :?fslk? Bushes also need to be cleared from the access road to the outlet outfall to permit unimpeded access to the outlet controls, DWR 1261 (rev. 10:09) Sheet 4 of