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 Whale ROCK Dam No. 1-40 County San LUIS Obispo Type of Dam Earth Type of Spillway Concrete Weir with Concrete Channel Water is 53.8 feet below spiilway crest and 70.8 feet dam crest. Water Surface Elevation: 1622 it MSL Weather Conditions Partly Cloudy Skies and Cool Contacts Made Noah Evans, John Millar, and Ed Humphrey with the City of SLO. Reason for Inspection Periodic Maintenance Inspection Important Observations, Recommendations or Actions Taken The woody vegetation growing along the upstream slope and in the small section located on the upper right corner of the bench was adequately removed as requested during the previous inspec?on. The east spillway wall offset measurement results needs to be discussed in the instrumentation engineering evaluation, particular the offset movements seen in Control Points 3 and 25. According to the latest instrumentation report dated September 15, 2015, a reservoir bathometric survey was performed in May 2014, and the report mentions the spillway elevation for the dam was adjusted from El. 216 (NGVD 29) to Ei. 218.3 (NAVD 88). ?The City should continue to reference all elevations with respect to the dam to the NGVD 29 datum 'to alleviate confusion. Otherwise, the instrumentation plots and data, the as-built drawings, and the Certificate of Approval will need to be revised based on the NAVD 88 datum. Conclusions From the known information and visual inspection, the dam, reservoir, and the appurtenances arejudged safe for continued use . Observations and Comments The crest, bench, groins, and toe area were walked. The gravel covered crest appeared level, uniform, and in satisfactory condition. The visible portion of the riprap lined upstream slope and the slope appeared uniform, stable, and in satisfactory condition. The groins and toe area appeared normal and the abutments stable. Vegetation control was overall good. The sporadic woody vegetation growing along the upstream slope and in the small section located on the upper right groin corner ofthe bench was adequately removed as requested during the previous inspection. No concerning rodent activity was noted during this inspection. Spiliway The approach, control channel, and exit were clear of concerning debris. The concrete comprising ogee crest, the invert, and the walls appeared In good condition, having no sign of instability or distress. No significant changes with respect to movement at the top of the spillway walls were observed. The top of the east and west spillway channel walls at Joint No. 3 have offsets of approximately 2~inches, and has the largest offset of the 29 wall panel joints. The movement at these locations appears negligible as compared with the recent inspection reports. This movement developed shortly after construction and is monitored by the observation of concrete saw- -cuts that have been scribed onto the tops of the two concrete wall sections, and inspected by Bill Vogler Photostaken? Yes I No 04/14/0216 ccfor Owner/Book DateofReport 05/05/2016 Gin/iv) 4 own 1261 (Rev. 10:09) Sheet 1 of Cr DAM AND RESERVQIR iN CERTIHED STATUS Name ofDam Whale Rock . Darn No. 1-40 Date of inspection 04/14/2016 Observations and Comments Outlet Seegage reported in the instrumentation submittal. The outlet works consists of an upstream sloping intake structure with five 24-inch butterfly valves at various elevations and a 30?inch butterfly blowoff valve that tees off of the 48?inch concrete encased steel pipe that passes through the dam. Reportedly, the lowest 24~inch butterfly? valve is silted-in and has not been operable for many years. The upstream butterfly valves and the blowoff valves were not cycled during this inspection. According to Mr. Evans, the outlet valves were cycled in the fail of 2015. The outlet valves were last cycled in DSOD's presence during the previous May 20, 2015 inspection. N0 seepage or signs of seepage were observed on the face, along the groins, or toe area. The dam has a chimney drain that connects to a 30-inch perforated reinforced concrete pipe that in turns drains into the East and West 30?inch diameter abutment drain pipes and a center crushed rock drain (approximately 5~ft wide by 4-ft high) that drains into a collector drain that discharges at the east side of the spillway, just south of the access road bridge. The seepage from the East and West drains were dry. The Stilling Basin V?Notched Weir, which reads combined flows from the East, West, and crushed rock drain, read 1/2-inch 0.2 gpm), which is typical for this reservoir?s low water level. Horizontal Drains R1-R5 were installed in the right abutment and Drains were installed in the Spillway area between December 1985 and January 1986. Horizontal Drains R1-R5 were dry and Drain S1 had a flow of 0.13 gpm, and Drains S2 and 83 both had a flow of 016 gpm. These seepage conditions are considered normal for the low reservoir water elevation during this inspection. The two 8?inch auxiliary abutment drains, located high?up each groin, were installed to provide a warning of high phreatic surfaces. These drains were dry during this inspection. instrumentation at this dam consists of sixteen hydraulic piezometers, six nested open weli piezometers, eight horizontal drains, three underdrains, nineteen survey monuments, two slope inclinometers, a crossarm gauge, and offset measurements at the top of the spiliway wall joints. The latest instrumentation submittal was dated September 15, 2015 and the reporting period covered through December 2014. Survey Monuments Since the previous DSOD instrumentation review, the latest surveys were performed on November 14, 2013 and May 20, 2014. The dam has nine monuments located on the creSt, two monuments located on the buttress and eight monuments were recently instaiied in 2012 on the slope. Survey monuments SM1-SM9, located on the crest of the dam, have shown expected settlement since the dam was completed in 1961. The iargest cumulative settlements have occurred at Monuments SM-5 (0.84-ft) and which are located near the maximum section of the dam. Cumulative crest deflection measurements have ranged from 0.04-ft for Monuments SM-9 to 0.4-ft for Monument The changes in crest settlement and deflection between the 2013 and 2014 were negligible. Survey Monuments SM-10 and are located on the slope of the dam and above the mid-slope bench. Cumuiative settlement for Monuments and was 0.8-ft and 0.48~ft, respectively. The cumulative deflection was 0.73~ft for Monument and DWR1261 (rev.10!09) Sheet 2 of 4 INSPECTIQN Lyr- DAM AND RESERVQIR lN STATUS Name of Dam Whale Rock Dam No. 1-40 Date of inspection 04/14/2016 Observations and Comments - 0.54-ft for Monument since 1981. Vertical and horizontal movements at these monuments appear to be minimal (less than 0.1-ft) over the last ten years; however, there appears to be scatter in the data that was not addressed in the engineering evaluation of the submittal. The oscillatory movements have no apparent trends. Eight survey monuments, through were installed in 2012 on the slope to provide additional monitoring. The baseline survey was performed on November 14, 2013. Both the settlement and deflections were negligible between the baseline and 2015 surveys. Hydraulic Piezometers Eleven of the sixteen original twin tube hydrauiic piezometers are operational. Upstream Piezometers-1, 2, and 5 are located at or near the foundation and respond closely to the reservoir?s water elevation. Piezometers P2are located upstream of the chimney drain and all but P4 have tips within Zone 1 of the embankment. These six piezometers have water levels that indicate a normal and expected phreatic surface. Piezometer 3 is located in the alluvial channel, approximately 50?ft below the three channels that drain the chimney drain. Piezometers 10 and 11 are also located just below these drains. All three piezometers have water levels near 45-ft, which is approximately 7-ft above the drain channels and the water levels have remained constant since 1990. ideally, the water level in these three piezometers would be below the drains, but the higher water levels can be expected since the drain was constructed with three channels instead of a centinuous blanket drain. The drains appear to be effective since there is no rising trend indicated by the data. None of the hydraulic piezometers are indicating any abnormal behavior or adverse trends and the levels are within historical norms. Open Standpipe Piezometers Twelve open standpipe piezometers were installed in the 1980s that have tips that are located in the foundation, abutment, and embankment right of the maximum section of the dam. There are two piezometers nested per hole and are designated 8 for shallow and for deep. Piezometers 17D, located in the central portion ofthe dam and having its tip located in the alluvial streambed remains blocked and Piezometer 178 was repaired in April 2010 and has remained dry through the 2014 monitoring period. Piezometers 18S and 18D are located near Hydraulic Piezometers 10 and 11 and below the West Drain. Both piezometers have constant levels and are influenced by the reservoir?s water elevation. Piezometer 18D has large spikes that may be related to rainfall. Piezometers 19D and 198 are located in the lower west abutment of the dam within the foundation bedrock and dam embankment and their levels have remained within historical norms. Both piezometers appear to be influenced by rainfall with Piezometer 198 being more influenced than 19D. Piezometer 19D also appears to be affected by the reservoir water level. Piezometers 208, 20D, 21 S, and 21D, located in the west abutment and closer to the spillway remained dry (except for seasonal spikes) and these piezometers could indicate if the horizontal drains installed between December 1985 and January 1988 were becoming less effective. Piezometers 228 and 22D are located through the crest at the right end of the dam with sensing zones in the core and foundation. Both Piezometers 22S and 22D had consistent water levels of a few feet. The open well piezometer data does not indicate any abnormal behavior or adverse trends and appears to indicate normal pore pressures and phreatic surface. Horizontal Drains There are eight horizontal drains that were installed between December 1985 and January 1986, due to high pore pressures in the right abutment and spiilway areas. Except for occasional seasonal spikes, the drains produced less than 1 and have not shown any decreasing trends. Underdrains During the 2013-2014 reporting period, the highest readings for the East Abutment Sheet 3 of 4 ENSPECTIQN liar: AND RESERVQER EN STATUS Name of Darn Whale Rock Darn No. 1-40 Date of Inspection 04/ 1 4/201 6 Observations and Comments Drain, West Abutment Drain, and the Stilling Basin were 1.3 gpm, 2.02 gpm, and 1.5 respectively. These fiows are considered low and remain within historical norms. Slope lnciinometers Two slope inc'linometers were installed in the east abutment landslide in October 1983 to monitor movement in the landslide area. The inclinometers have been generally recorded at 2-year intervals and the last reading was performed on May 22, 2013. The readings are calibrated with the baseline readings of September 23, 1993. lnclincmeter 81?1 shows a cumulative displacement of approximately 0.5-inches and 81-2 shows a cumulative displacement of approximately 0.7~inches since 1993. The inclinometer data appears to indicate minor surface movement with no evidence of significant movement or changes. Crossarm Gauges There is a crossarm gauge through the crest with the access pipe located near Monument The crossarm continues to show minimal settlement and are likely related to the precision of the instrument. The maximum measured settlement has been approximately 0.05-ft since the dam was completed in 1961. Reportedly, the owner also reads the water levels in the crossarm casing. Spillway Wall Movement Measurement - Measured movements between the kerfs cut into the t0p of the spillway walls at the panel joints continue to show minimal movements since the measurements were started back in 1967. The offset of the kerf cut on the top of the west wall remained unchanged at approximately 5/16-inch, and the offset of the top of the east wall remained unchanged at approximately 5/8?inch. Survey control points have also been established on the outer face of the east spillway wall, and the report included offset measurements for the Control Points 1-40. Except for Control Points 3 and 25, the offset measurements for the East Spillway Wall were stable with minimal movement. Control Points 3 and 25 are showing an increasing offset movement trend. Control Point 3 has shown an offset of 0.6?inches and Control Point 25 has shown an offset of 0.5-inches. The report?s evaluation did not discuss the results of the east spillway offset measurements, and although the movements are small, the report needs to include this data in their evaluation. Conclusion The instrumentation data indicated that this dam is performing adequately. The existing instrumentation and their monitoring frequency are judged sufficient at this time. DWR1261(rev.10i09) Sheet 4 of '4 FILE 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 Whale Rock Dam No. 1-40 County San Luis Obispo Type of Dam _E_a_rt_h_ _ _ _ _ _ _ _ _ _ Type of Spillway Concrete Weir with Concrete Channel Water is 48 feet below spillway crest and 65 feet below dam crest. Weather Conditions_C_le_a_r_a_n_d_w_a_r_m_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Contacts Made Noah Evans with the City of SLO Reason for Inspection Annual Maintenance Inspection Important Observations, Recommendations or Actions Taken The four operable inspection. valves and valve were satisfactorily cycled during this Vegetation control was overall satisfactory, with exception to a small section on the upper right downstream corner of the downstream bench where the groin contact has been incorrectly defined. This vegetation needs to be removed, as discussed during the inspection. Minor woody vegetation along the upstream face also requires removal. The latest instrumentation submittal is overdue. The last submittal was transmitted to us on September 10, 2013. Instrumentation submittals need to be submitted annually. The owner informed me during the inspection that the latest submittal is scheduled to be completed within the next few months. As stated in our last inspection report, the next submittal needs to address scatter in the data for the measurements of Survey Monuments SM-10 and SM-11. Conclusions From the known information and visual inspection, the dam, reservoir, and all appurtenances are judged safe for continued use. Observations and Comments The gravel crest was in satisfactory condition. Both faces exhibited no signs of distress or instability. Riprap protection along the upstream face was uniform, stable, and intact. Vegetation control along both faees was good, with exception to a small section on the upper right downstream corner of the downstream bench. The groin contact has been incorrectly defined in this area. I pointed out the location to Mr. Evans during this inspection and he agreed that the vegetation can be removed. The downstream face is otherwise covered in low growing well maintained grasses. Minor woody vegetation was observed emerging through the upstream face riprap including some small trees. I requested this vegetation be removed. Rodent control was overall satisfactory. Increased activity was, however, observed along a section of the mid downstream left groin. I requested the large burrows be backfilled and compacted and rodent control efforts continue. Spillway The spillway approach, concrete weir, control channel, and downstream exit were clear and unobstructed. The spillway was viewed from the approach channel, downstream overhead bridge, and from along portions of both spillway walls. The concrete surfaces remain in good condition with no significant cracking or spalling observed. The walls appeared to remain straight and level showing no significant signs of movement. The 2-inch offset at Joint No. 3 located at the top of both spillway walls appeared unchanged from previous reports and photos. The movement ~/2-rsl T'S' Photos taken? cc for Yes DWR 1261 (Rev. 10/09) x No Owner/Book Inspected by Date of Inspection Date of Report T. Jimenez (...L. f='I /') I tf.r(J.J 5/20/2015 luf;\{ ti /fJJ/.tS 5/28/2015 ~t /JJ;Vl Sheet of 4 Name of Dam Whale Rock Date of lnspection _ _ _ _5_/2_0_/_2_0_15 _ _ __ developed shortly after construction and is annually monitored by the owner and included in the instrumentation submittal. Vegetation control was good. Tule growth was observed at the downstream exit of the channel. The tules are not considered a significant obstruction at this time. Outlet The low-level outlet consists of a pipe . The pipe is equipped with valves located on and a downstream valve. The lowest upstream valve is reportedly silted in and was not operated during this inspection. The owner fully cycled the operable upstream valves with no problems. The downstream valve was also satisfactorily cycled during this inspection. Visible concrete compromising the intake structure and downstream dissipater structure remains in good condition with no signs of distress observed. Seepage No seepage was observed on the downstream face, groins, or toe of the dam. The dam is equipped with several drain pipes and seepage monitoring locations. The flowing observations were made during this inspection: • 8-inch Auxiliary Abutment Drains, located high up each groin: Dry • Horizontal Drains S1, S2, and located in downstream spillway area: S1-Trickle, S2 and S3- Dry. • Horizontal Drains R1, R2, R3, R4, and RS, located along the toe of the dam installed in the downstream right abutment: Dry • Stilling Basin V-Notch Weir, measures combined flows from East, West, and crushed rock drain which collect flows from the 30-inch perforated pipe connected to the chimney drain: 518" (- 0.7 gpm). Theses seepage conditions are considered normal for the low reservoir level observed. The East and West drains connected to the chimney drain could not be individually measured due to confined space issues, but visual observations were made. The East drain was dry and the West drain had a small flow. Instr. Instrumentation at this dam consists of 16 hydraulic piezometers, 6 nested open well piezometers, 8 drains, 19 survey monuments, 2 sloped inclinometers, a crossarm gauge, and offset measurements at the top of the spillway wall joints. The latest instrumentation submittal was transmitted to us on September 10, 2013, and reviewed in our last inspection report. The data indicated that the dam was performing adequately; however, we requested scatter in the data for the measurements of Survey Monuments SM-10 and SM-11 be addressed in the next instrumentation submittal. The existing instrumentation is judged to be sufficient at this time. The latest instrumentation submittal is overdue. I reminded Mr. Evans that the instrumentation submittals need to be submitted annually. He informed me during the inspection that the latest submittal is scheduled to be completed within the next few months and apologized for the delay. DWR 1261 (rev. 10/09) Sheet 2 of 4 INSPECTIC Name of Dam OF DAM AND RESERVOIR IN CEl.dFIED STATUS Whale Rock Dam No. 1-40 ---------- Date of lnspection _ _ _ _ 5_ / 2_0_/2_0_1_5_ __ 1. Upstream face viewed from the left abutment. . 2. Red arrow points to example of small tree requiring removal on the upstream face. DWR 1261 (rev. 10/09) Sheet 3 of 4 INSPECTIC:. Name of Dam Whale Rock OF DAM AND RESERVOIR IN CE.~ dFIED STATUS Dam No. 1-40 ---------- Date of lnspection _ _ _ _ S_/2_0_/2_0_1_5_ __ 3. Spillway channel viewed looking upstream from overhead bridge. Red line outlines approximate area requiring vegetation removal on the downstream face. 4. Ariel view of downstream face of dam taken from Google Earth. Red line identifies area where vegetation removal is required, as outline above. DWR 1261 (rev. 10/09) Sheet 4 of 4 STATE OF CALIFORNIA ALIFORNIA NATURAL RESOURCES AGENCY DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Type of Dam Whale Rock Earth 31 feet County San Luis Obispo Concrete Weir with Concrete Channel spillway crest and 48 feet below dam crest. Dam No. 1-40 Type of Spillway ~~~~~~~~~~~~ Water is below Water Surface Elevation: 185 ft MSL Weather Conditions Clear Skies and Mild Contacts Made Noah Evans, Don Thomas, Marcus Henderson, Joe Zegota, and Travis Trutt with the City of SLO. Reason for Inspection Periodic Maintenance Inspection Important Observations, Recommendations or Actions Taken 1. The low spots in the crest had been leveled with imported fill and restored to El 233 as requested during the previous inspection. 2. The upstream butterfly valves need to be cycled during the next DSOD maintenance inspection and special arrangements may be needed as not to disrupt ongoing water deliveries. 3. The two 8-inch auxiliary abutment drains, located high-up each groin, should be inspected during the next inspection. 4. There appears to be scatter in the data for the measurements of Survey Monuments SM-10 and SM-11 since 2004 that needs to be addressed in the engineering evaluation of the instrumentation submittal. 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 gravel covered crest appeared level, uniform, and in satisfactory condition with no sign of distress. The low areas of the crest were leveled with imported fill and had been restored to near El. 233, as requested during the previous inspection. The imported fill appeared to be road base (i.e., gravely sand) that was spread and compacted by wheel rolling. The existing crest survey monuments where the crest was leveled were protected by installed extension collars and covers. The visible portion of the riprap lined upstream slope and the downstream slope appeared uniform, stable, and in satisfactory condition. The downstream groins and toe area appeared normal and the abutments stable. The Owner has invested considerable effort in removing vegetation throughout the dam site and the vegetation control was overall good. No concerning rodent activity was noted during this inspection. Spillway The approach, ogee crest, control channel, and downstream exit were clear of concerning debris. The concrete comprising of the weir entrance, the invert, and the walls were in good condition with no sign of instability or distress. No significant changes with respect to movement at the top of the spillway walls were observed. The top of the east and west spillway channel walls at Joint No. 3 have an offset of approximately 2-inches and has the largest offset of the 29 wall panel joints. The movement at these locations appears negligible as compared with the recent inspection reports. This movement developed shortly after construction and is monitored and reported in the instrumentation submittal. Inspected by Photos taken? Yes cc for DWR 1261 (Rev. 10/09) No Owner/Book Date of Inspection Date of Report Bill Vogler 10/2/2013 1/2/2014 Sheet of \I \0 l \z\5 ( Name of Dam Whale Rock Date of Inspection 10/2/2013 ~~~~~~~~~~ Observations and Comments The outlet works consists of structure with valves valve that tees off of the at various elevations and a dovvnstream pipe that passes through the dam. Reportedly, the lowest valves valve is silted-in and has not been operable for many years. The four upstream were not cycled during this inspection as not to affect the water quality for the water delivery that was ongoing during this inspection. The downstream valve was fully cycled during the inspection and it operated smoothly and no problems were encountered. According to Mr. Evans, the upstream valves were used during the past year to draw water from different elevations. The last time DSOD witnessed the operation of the upstream valves was during the April 2010 inspection. I reminded Mr. Evans of DSOD's requirements that all valves associated with the low-level outlet valves need to be cycled annually and in our presence every three years. The upstream need be cycled during the next maintenance inspection, which includes making special arrangements as not to disrupt water deliveries. Seepage No seepage or signs of seepage were observed on the downstream face, along the groins, or toe perforated reinforced concrete pipe area. The dam has a chimney drain that connects to a diameter abutment drain pipes and a center that in turns drains into the East and West crushed rock drain that drains into a collector drain that discharges at the east side of the spillway, just south of the access road bridge. The seepage from the East and West drains were not measured due to confined space issues, but by visual inspections from the respective manhole entrances, the East Drain was dry and the West Drain had a small flow. The Stilling Basin V-Notched Weir , which reads combined flows from the East, West, and crushed rock drain, read 1-inch (== 2 gpm), which is normal for this reservoir's water elevation. Horizontal Drains R 1-R5 were installed in the downstream right abutment and Drains S 1-S3 were installed in the downstream spillway area between December 1985 and January 1986. Horizontal Drains R 1-R5 were dry and Drains S2 and S3 were dry and S 1 had a steady drip. These seepage conditions are considered normal for the reservoir water elevation during this inspection. auxiliary abutment drains, located high-up each groin, were installed to provide a The two warning of high phreatic surfaces. These drains were not inspected and should be visited during the next inspection. Instr. Instrumentation at this dam consists sixteen hydraulic piezometers, six nested open well piezometers, eight drains, nineteen survey monuments, two slope inclinometers, a crossarm gauge, and offset measurements at the top of the spillway wall joints. The latest instrumentation submittal was dated August 15, 2013 and the reporting period covered through 2012. Survey Monuments - The latest survey was performed on November 20, 2012. The dam has nine monuments located on the crest, two monuments located on the downstream buttress and eight monuments were recently installed in 2012 on the downstream slope. Survey monuments SM1SM9, located on the crest of the dam, have shown expected settlement since the dam was completed in 1961. Survey Monument S1, located on the west end of the dam's crest, showed a heave of approximately 0.4-ft in 2001 for an unknown reason and has stayed relatively constant since then. The largest cumulative settlements have occurred at Monuments SM-5 (0.8-ft) and SM6 (0.92-ft), which are located near the maximum section of the dam. Downstream crest deflection DWR 1261 (rev. 10/09) Sheet 2 of 5 Name of Dam Whale Rock Dam No. Date of Inspection _1_-4_0_ _ _ _ _ _ _ __ 10/2/2013 --------~~ Observations and Comments measurements have ranged from 0.2-ft for Monuments SM-2 to 0.3-ft for Monument SM-6. The crest monuments have shown negligible settlement and horizontal movement during the past 10 years. Survey Monuments SM-10 and SM-11 are located on the downstream slope of the dam and above the mid-slope bench. Cumulative settlement for Monuments SM-10 and SM-11 was 0.6-ft and 0.5-ft respectively. The cumulative downstream deflection was 0.3-ft for Monument SM-10 and 0.4-ft for Monument SM-1 since 1961. There appears to be scatter in the data for the measurements of Monument SM-11 since 2004 that needs to be addressed in the engineering evaluation of the instrumentation submittal; however, no trends are apparent. Eight survey monuments, SM-12 through SM-19, were installed in 2012 on the downstream slope to provide additional monitoring. The first readings were taken on November 20, 2012 and will serve as a baseline reading for future measurements. Hydraulic Piezometers - Eleven of the sixteen original twin tube hydraulic piezometers are operational. Upstream Piezometers 1, 2, and 5 are located at or near the foundation and respond closely to the reservoir's water elevation. Piezometers P2, P4, P6, P7, PS, and P9 are located upstream of the chimney drain and all but P4 have tips within Zone 1 of the embankment. These six piezometers have water levels that indicate a normal and expected phreatic surface. Piezometer 3 is located in the alluvial channel, approximately 50-ft below the three channels that drain the chimney drain. Piezometers 10 and 11 are also located just below these drains. All three piezometers have water levels near 50-ft, which is approximately 12-ft above the drain channels and the water levels have remained constant since 1990. Ideally, the water level in these three piezometers would be below the drains, but the higher water levels can be expected since the drain was constructed with three channels instead of a continuous blanket drain. The drains appear to be effective since there is no rising trend indicated by the data. None of the hydraulic piezometers are indicating any abnormal behavior or adverse trends and the levels are within historical norms. Open Standpipe Piezometers - Twelve open standpipe piezometers were installed in the 1980s that have tips that are located in the foundation, abutment, and embankment right of the maximum section of the dam. There are two piezometers nested per hole and are designated S for shallow and D for deep. Piezometers 170, located in the central portion of the dam and having its tip located in the alluvial streambed remains blocked and Piezometer 17S was repaired in April 2010 and has remained dry through the 2012 monitoring period. Piezometers 18S and 180 are located near Hydraulic Piezometers 10 and 11 and below the West Drain. Both piezometers have consistent levels and are influenced by the reservoir's water elevation. Piezometer 18D has large spikes that may be related to rainfall. Piezometers 190 and 19S are located in the lower west abutment of the dam within the foundation bedrock and dam embankment fill and their levels have remained within historical norms. Both piezometers appear to be influenced by rainfall with Piezometer 19S being more influenced than 190. Piezometer 19D also appears to be affected by the reservoir water level. Piezometers 20S, 20D, 21 S, and 21 D, located in the west abutment and closer to the spillway remained dry (except for seasonal spikes) and these piezometers could indicate if the horizontal drains installed between December 1985 and January 1986 were becoming less effective. Piezometers 22S and 220 are located through the crest at the right end of the dam with sensing zones in the core and foundation. Piezometer 22S remained dry during the 2012 reporting period and Piezometer 220 had a consistent and low column reading of a few feet. The open well piezometer data does not indicate any abnormal behavior or adverse trends and appears to indicate a normal pore pressures and phreatic surface. Horizontal Drains - There are eight horizontal drains that were installed between December 1985 DWR 1261 (rev. 10/09) Sheet 3 of 5 INSPECTION l Name of Dam DAM AND RESERVOIR IN CERli :o STATUS Whale Rock Date of Inspection 10/2/2013 ~~~~~~~~~~ Observations and Comments and January 1986 due to high pore pressures in the right abutment and spillway areas. Except for occasional seasonal spikes, the drains produced less than 1 gpm and have not shown any rising trends. Slope Inclinometers - Two slope inclinometers were installed in the east abutment landslide in October 1983 to monitor movement in the landslide area. The inclinometers have been generally recorded at 2-year intervals and the last reading was performed on May 22, 2013. The readings are calibrated with the baseline readings of September 23, 1993. Inclinometer S1 -1 shows a cumulative displacement of approximately 0.5-inches and S 1-2 shows a cumulative displacement of approximately 0. 7-inches since 1993. The inclinometer data appears to indicate minor surface movement with no evidence of significant movement or changes. Crossarm Gauges - There is a crossarm gauge through the crest with the access pipe located near Monument SM-5. The crossarm continues to show minimal settlement and are likely related to the precision of the instrument. The maximum measured settlement has been approximately 0.05-ft since the dam was completed in 1961. Reportedly, the owner also reads the water levels in the crossarm casing. Spillway Wall Movement Measurement - Measured movements between the kerfs cut into the top of the spillway walls at the panel joints continue to show minimal movements since the measurements were started back in 1967. The instrumentation data indicated that this dam is performing adequately. The existing instrumentation and their monitoring frequency are judged sufficient at this time. Photo 1. Base rock was placed on the crest to restore the dam crest elevation .. DWR 1261 (rev. 10/09) Sheet 4 of 5 STATE OF CALIFORNIA CALI FORNIA NATURAL RESOURCES AGE N-., Y DEPARTM ENT OF WATER RESOURC ES DIVISION OF SAFETY OF DAMS FILE INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Whale Rock Type of Dam Earth Water is 20 feet Dam No. 1-40 County San Luis Obispo Type of Spillway Concrete Weir and channel spillway crest and 37 feet below dam crest. -----------~ below Weather Conditions_S_u_n_n~y_a_n_d_n_ic_e_ _ __ __ _ _ _ __ _ __ __ _ _ _ __ _ _ _ _ _ _ __ Contacts Made Bob Hamilton and Joe Zog ata with City of San Luis Obispo Reason for Inspection Periodic Maintenance Inspection Important Observations, Recommendations or Actions Taken As requested during last inspection, the own er has completed a survey of the dam and is preparin g to restore the crest elevati on to 233.00 feet. Conclusions From the known information and visual inspecti on, the dam, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments The visible portion of the upstream face and the downstream face appeared stable, normal and uniform. The crest was level, uniform and normal with no signs of distress. The crest cracks that resulted from the past earthquakes have healed and were nowhere to be found. Both abutments appeared stable and normal. As requested during the last inspection, the owner has completed a survey of the dam and is preparing to restore the crest elevation to 233.00 feet. This was also recommended by the owner's consultant. Vegetation management was satisfactory with exception of few brushes on the downstream upper right side of the dam. Work is continuing and these will be removed soon. The owner has been using goats and crews to remove the vegetation. The downstream toe and groins were normal. Upstream rip-rap protection was in satisfactory condition. Rodent control was satisfactory. Spillway The spillway approach, ogee weir, chute, stilling basin, and exit were clear. The spillway concrete was in satisfactory condition and the spillway appeared structurally sound. The 1 to 2-inch movement at the 4th joint of both spillway walls appears unchanged, and it is judged to be minor. Thi s offset developed shortly after construction and has since remained unchanged. The outlet works is comprised of a sloped box intake on the upstream side with five 24-inch butterfly valves to draw water at variou s elevation s. The lowest 24-inch butterfly valve is silted and has not been operated for some time. The low level outlet pipe is a 48-inch concrete encased steel pipe with no concrete collars along the alignment. The downstream blow-off is a 30-inch butterfly valve, which daylights into the creek bed. The blow-off valve tees off the 48-inch low level outlet pipe. All the upstream and downstream valves were cycled and they performed satisfactorily. Seepage No seepage was noted on the downstream face or along the groins or toe of the dam. The dam has an chimney drain connecting to a pipe, which collects the seepage from chimney drain and caries the flows through two · d pipes to the crushed rock drain gravel drain also runs 1 downstream toe of the dam. A between these two pipes. Seepage is then collected at the toe via another pipe which then ~n~ ,\,I~~,..,.. Inspected by Param Dhillon ~OD ~ A -i-~\ ,,.,, [ Yes No X Photos taken? Date of Inspection 9/04/2012 Owner/Book cc for Date of Report 12/03/2012 ,1,. 1 DWR 1261 (Rev. 10/09) Sheet --- of 3 DAM IN L...~RTIFIED Name of Dam Whale Rock Date of lnspection _ _ _ _9_/_4_/1_2_ _ __ Observations and Comments I discharges the flows into the spillway channel just south of the spillway bridge. The horizontal drains (R1 through RS) were emanating approximately 1 to 2 gpm, as absented from the spillvJay side wall and the access bridge. This seepage appeared to be within historical norms of less than 5 gpm. I did not observe horizontal drains S 1, S2 and S3 or two 8-inch drain pipes, high up the abutments. These horizontal drains are usually dry or emanate less than 1 gpm. The 8-inch drain pipes always remain dry. Instr. Instruments at the dam consists of the original 16 hydraulic piezometers (P1 through P16), 6 open well, nested, piezometers (P17 through P22), 8 drains (R1 through R5 and S1 through S3), 11 survey monuments (SM1 through SM11 ), 2 slope inclinometers (Sl-1 and Sl-2), a cross arm gage, and offset measurements of the spillway wall. The latest data submittal was dated July 31, 2012 covering the 2011. My review of this data reflected satisfactory performance of the dam. Piezometer: There are 16 hydraulic piezometers installed at various sensing locations such as foundation, shells and core. Data is only reported for 11 functional piezometers. Location and sensing zones of these piezometers are presented in the annual instrumentation report. The pore pressures are higher at the upstream piezometers and decrease at the downstream piezometers as pore pressures dissipate. Three piezometers (P3, P10 and P11) have sensing zones, downstream of the inclined chimney drain. Since 1986, these piezometers have remained close to the top of west drain at elevation 40. Performance of these piezometers indicates the chimney drain is letting water escape through the drain and the downstream shell is dry except right above the drain. There is no increasing trend of higher piezometric levels. Open Well Piezometer: There are 12 open well, nested, piezometers installed at various sensing locations such as the foundation, abutments, and the embankment. The piezometers are numbered 17 to 22 with "S" for shallow and "D" for deep piezometers. Piezometers 17D is obstructed and 17S appears to have been made operational recently. Piezometers 18S and 18D are close to Hydraulic Piezometers 10 and 11, and have consistent water levels indicating downstream shell is mostly dry and the drains are working. The piezometers do not show any increasing trend, which would indicate the drains are becoming less effective. Most of the shallow piezometers respond to reservoir surface elevation and rainfall and the deep piezometers are not as responsive. The long term open well piezometer data does not indicate any unsafe conditions. Horizontal Drains: There are 8 horizontal drains that drain the dam's right abutment and foundation on the right side of the dam. Seepage is measured for R1 to R5 at the toe of the dam and for S1 to S3 in the right spillway wall. The abutments drains were installed in 1986 to relieve water pressure near the right abutment and overlying west side of the dam. The seepage has followed the trend of the past and remains within normal ranges. Below are tabulated flows for the drains. 2011 max flows Drains {gpm) Rl Dry R2 Dry R3 0.53 R4 0.01 DWR 1261 (rev. 10/09) Sheet 2 of 3 _1N OF Name of Dam Whale Rock IN STATUS Dam No. _1_-_4_0_ _ _ _ _ _ __ Date of lnspection _ _ _ _9_/_4_/1_2_ _ __ Observations and Comments RS 0.01 r-t ,:)J. 0.48 to 0.01 52 3.10 to O 53 1.19 to O Underdrains: There are three under-drains connected to the inclined chimney drain. East, West and Central. Both the East and West Drains are built with a crushed rock drain. All pipe and the center drain is comprised of a the drains slope into the toe where carrier pipe collects all the seepage and discharges it into the spillway channel just south of the spillway bridge. The East Drain produced maximum flow of approximately 5 gpm and the West Drain produced approximately 15 gpm for the review period in January 2011. The drains are not looked at during inspections due to confined space issues. The seepage has followed the trends of the past and remains within normal ranges. Crossarm Gage: The cross arm shows minimal movements. The maximum movements are less than 0.05 foot over the last 30 years. Spillway Wall Measurements: The spillway has saw cuts on the spillway walls soon after construction in 1967. These saw cuts have since then been continually monitored and have reflected minimal movement Survey Monuments: 9 survey monuments numbered SM1 to SM9 dot the crest of the dam. 2 survey monuments numbered SM10 and SM11 are located on the downstream bench. No abnormal settlement or horizontal movement was noted from the submitted data. Maximum horizontal and vertical movements between 2010 and 2012 were negligible. The long term maximum horizontal and vertical movements from 1960 to 2011 were 0.34 and 0.91 feet at SM6, respectively. SM6 is at the maximum section of the dam. These values fall within acceptable limits. Per their consultant's recommendation, the owner will be adding monuments on the downstream buttress of the dam. Slope Inclinometer: 2 slope inclinometers were installed in 1983 to monitor earth movement within the existing landslide high up the left abutment. The owner monitors the movements every 2 years with next readings in 2013, however the water levels are monitored monthly. No movement readings were taken in 2011. Water levels in these 2 instruments remain constant or fluctuate with rainfall. Conclusion: The available instrumentation data indicates the dam is performing satisfactorily. The current instrumentation network is judged to be adequate. DWR 1261 (rev. 10/09) Sheet 3 of 3