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INSPECTION OF DAM AND RESERVOIR IN STATUS Name of Dam Union Valley Dam No. 1009?3 Date of Inspection 8/24/2016 Observations and Comments Outlet Seepage Instr. bridge, approach section, and walked the upper and lower concrete channels. Th- gates and upstream and face coatings appeared to be in satisfactory condition. All visible structural members ofthe gates showed no signs of distress. The concrete surfaces also appeared to be in satisfactory condition. No significant cracking or spalling was observed. Repairs to the channel invert continue to hoid up well. The outlet controls were last cycled in our presence on 9/30/15 and 10/7/15. The vaive was operated with some difficulty, as documented in our report dated 11/5/15. Reportedly SMUD has made some adjustments for a smoother operation. agreed to demonstrate the fully operation of the valve during some scheduled inspections this October. Th_ was walked during this inspection. Seepage conditions in the tunnel are described below. Conditions in the tunnel appear unchanged when compared with past descriptions. The penstock coating appeared to be in satisfactory condition. The unlined tunnel walls appeared sound and showed no signs of instability or distress. 9am: No seepage was observed on the face or groins ofthe dam. Junction reservoir butts up to the toe of the dam and obscured seepage conditions, as well as inundated both seepage weirs at the toe. For this reason no readings at the toe weirs were taken this inspection. The right and left manhoie drains were observed along the iower groins. A trickle of flow was observed emanating from the left manhole drain and ~2 was observed from the right manhole drain. The historically staked seepage areas along the left groin were observed. Conditions around the stakes were dry, with exception to the most stake located approximately up from the toe. Damp conditions were observed around the lowest stake, but no live flow was observed. Conditions at the stakes vary historicaliy and are beiieve to originate from the left abutment and not be dam related. No unusual seepage conditions were observed at the dam and conditions were considered normal. Dry conditions were observed toward the end of the tunnel, Minor dampness and wet conditions were observed as we walked toward the upstream and to the tunnei plug. Seepage in the tunnel is measured at two v?notch seepage weirs. One iocated near the tunnel plug and another near the and of the tunnel. The tunnel plug weir read 005? (~0.66 gpm) and the tunnel weir read (111? (~47 gpm). The seepage conditions are considered normal. Spillway: No seepage was observed in the spillway channel. The right wall weep drains, drains at the lowered spillway section invert, and drains under the flip bucket section were all dry. Instrumentation at this dam consists of piezometers, seepage weirs, embankment drain pipes, and survey monuments. The latest instrumentation report was submitted with an owner?s letter dated January 29, 2016, covering caiendar year 2015. Sheet 2 of 6 INSPECTION OF DAM AND RESERVOIR iN STATUS Name of Dam Union Valley Dam No. 1009?3 Date of inspection 8/24/2016 Observations and Comments Open Well Piezometers: The dam has 7 open well piezometers installed in 1988. The piezometers are located in the shell above the chimney drain. Data in the report is provided from 1992 2015. Data for piezometers 1V, 3V, 4V, and 6V remain within approximately- of the tip elevation and display minimal movements over the iife of the readings. Over the last year Piezometer 1V showed a rise of approximatel_. The piezometer will be closely monitored for changes and developing trends over the next year, as stated in the report. Piezometer 7V has fluctuated about 1 to 3 above the tip elevation. The small measurements in these piezometers are likely related to nuisance water. No unusual conditions are observed. Piezometers 2V and 5V continue to measure perched water lenses unrelated to reservoir levels, as discussed in our letter dated February 20, 2015. in 2015, Piezometer 2V measurec_ above the tip elevation and Piezometer 5V measurec_ above the tip elevation. The data for these two piezometers generally fluctuates within a few feet throughout the year, but since 1992 the data has remained consistent and shown no significant trends. Twin Tube Hydraulic Piezometers: The original 26 twin-tube hydraulic piezometers have reached end of their useful life and are no longer monitored. As stated in our letters dated October 7, 2013, March 26, 2015, and February 18, 2016, the District needs to keep us apprised of their plans for abandoning the terminal well housing the twin tube piezometer equipment, and also the long~term seepage monitoring plan in the well. A written work plan needs to be submitted to us for review and approval prior to any terminal well modifications. Seepage Weirs: The dam has four seepage weirs. Two weirs are located at the toe of the dam and two are located in th_. Readings at the upstrea_ weir are not included in the instrumentation submittals. The report provides data plots from 1988 - 2015. In 2015, the right toe weir peaked at ~130 gpm, the center toe weir read dry, and the tunnel weir peaked at ~12 gpm. Lower reservoir levels since 2014 reflect a decrease in seepage data at the toe weirs. The data remains within the historical limits since 1988, and displays no unusual trends, Embankment Drains: The dam has two embankment drains. Drains are located and measured in manholes near the toe of the dam. Data in the submittal is presented from 1988 - 2015. The right drain peaked at 0.5 and the left drain peaked at 0.6 in 2015. The seepage drain data displays no usual trends and is considered normal. Survey Monuments: The dam has eight survey monuments located along the crest of the dam. Monuments are surveyed annually for horizontal and vertical control. The latest survey was performed in 2015. The dam was built in 1963 and a baseline survey was performed in 1972. Data in the submittal is provided from 1973 to 2015. Since 1973, gradual settlement has been observed over the years. Maximum settlement from 1973?2015 i- observed at monument 5 near the maximum section of the dam. The year to year settlements have been less thar_ The settlement data is considered minimal for _tall Earth and Rockfill Dam constructed with 4? feet of camber. Horizontal data displays minor movements that oscillate in the upstream and direction. Since 1973, the greatest horizontal movement i-in the upstream direction at Monument 3. Annual movements tend to be less the-with occasional spikes up t_ The data shows no unusual trends and appears normal. The past two inspection reports in 2014 and 2015 indicate settlement movements up tc?, due to the data given in Table 3-2 of the report and the settlement time plot Figure C-4. Reported Sheet 3 of 6 53AM AEATSMEB Name G'f'?am' U'n?ganVa?ey . 9am Na, 10:33:33 Desi-? 0f inspectim l-Qbsewa?ms and ?ammanm mam-merits and data g?rwi?ed in Figure Q5 the: {apart indisata hawevers- up is 3mm MAME-1 Eadie-y 'i?sziEIQ-ancidan with mun ta gia??; we .sett?em'smi data_.. Ma: . MQF?dden stateij that there is an :fosat in tha dam and agiiead is irwastiga-E? and ?arify 'i?he mas-5m i far ?ha csff'sei in me mag-xi; sub?mii?a}, 5 Tim nursfam insi?mmema?c? neiwark is judged adaquateg, and add?i?fnai iimafmm-a?iatim is deamm amass-aw at ihiiss time; New paved. dam mast viewed the jig-hit end of ?rhe 'dam.? ?33 12.61 (re-v. i 0.9033} Sheei A m? gm?. @me m2 awamawzmmu? ma?y?a% 22$ wamBCEam 4.sz . . . . . 2n. 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The- tunnel was walked by Mr. Ordoubigian during this inspection. No change from past inspection descriptions was reported. Patches along the penstock coating remain in good condition. Minimal dampness and seepage was observed along the tunnel walls. gem: No seepage was observed on the face, groins, or toe of the dam. The historically staked damp locations along the left groin were observed and all locations were dry. Seepage at the marked locations has varied historically and is believed to originate from the left abutment and not be dam related. Conditions were not considered unusual. The two 90? v~notch seepage weirs located at the toe of the dam were both dry. The center toe weir box was satisfactorily cleared of sediment and vegetation, as requested The manhole drains were observed and had minimal fiows. The right manhole drain was flowing ~0.5 and the left manhole had a trickle. The conditions are considered normal considering the low reservoir level. The tunnel is equipped with two seepage weirs, one located .near the tunnel plug and one at the and of the tunnel. The tunnel plug weir gpm) and the tunnel weir reac_ gpm). The seepage conditions are considered normal. Spillway: No seepage conditions were observed in the spillway channel. The right wall weep drains, drains at the end of the lowered spillway section, and drains under the flip bucket section were all dry. Instrumentation at this dam consists of piezometers, seepage weirs, embankment drain pipes, and survey monuments. The latest instrumentation report was submitted with an owner?s letter dated January 29, 2015, for calendar year 2014. Open Well Piezometers: The dam has 7 open well piezometers (iv-7V), which were installed in 1988 in the shell above the chimney drain. Piezometers 1V, 3V, 4V, 6V, and 7V continue to read dry with some small measurements of nuisance water. Piezometers 2V and 5V continue to measure perched water. in 2014, piezometer 2V measurec_ above the tip elevation and piezometer 5V measur- above the tip elevation. These readings are consistent with past data and do not track reservoir levels. The data at both piezometers typically oscillates within a few feet. The instrumentation report included an analysis of the functionality of Piezometer 5V, as requested. In our letter dated February 20, 2015, we concurred with the District that water levels in Piezometer 5V do not track reservoir levels, as well as concurred with consulting engineer Richard Harlan?s 1999 report that the piezometer is performing properly and is likely measuring perched water lenses that are not related to reservoir levels. No further investigation work is required on Piezometer 5V at this time. Sheet 2 of 5 INSPECTION DAM AND RESERVOIR IN CERT ED STATUS Name of Dam Union Valiey Dam No. 1009?3 Date of Inspection 9/30/2015 Observations and Comments The piezometer data has followed historical trends and displays no unusual conditions at this time. Twin? Tube Hydraulic Piezometers: The originai 26 twin-tube hydraulic piezometers have reached the end of their useful life and are no longer. monitored. As stated in our letters dated October 7, 2013, and March 26, 2015, the District needs to keep DSQD apprised of their plans for abandoning the terminal well housing the twin tube piezometer equipment, and also the District?s long-term seepage monitoring plan in the well. A written work plan needs to be submitted to us for review and approval prior to any terminal well modifications. Seepage Weirs: The dam has a total of four seepage weirs, two at the toe of the dam and two iocated inside th_. Readings at the upstrea_ weir are not inciuded in instrumentation submittals. Data has been recorded at the weirs since 1988. The toe weirs have historically shown fluctuations with the reservoir level. Peak readings in 2014 were 115 at the right toe weir and 0.7 at the center toe weir. The tunnel weir peaked at 15.9 in 2014. The weir readings have remained within their historical range and to not show any unusual trends. Embankments Drains: The dam is equipped with two embankment drains, viewed and measured in manholes located nearthe toe of the dam. Measurements have been recorded since 1988. Readings peak at 1.5 at the left drain and 2.5 for the right drain. The 2014 data displayed no unusual trends. Survey Monuments: Eight survey monuments located along the crest of the dam are surveyed annually for horizontai and verticai control. Data has been recorded since 1973. Total settlement values range between 0.1 an_ with the greater settlement values near the maximum section of the dam. 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The penstock conduit and coating appeared to remain in good condition. Dam: No seepage was observed on the face or grains of the dam. The historically marked damp areas on the face near the left groin were observed during this inspection. These areas are monitored by the owner and marked with stakes. The areas were all dry, but green grasses around the marked locations were observed. Seepage conditions in the marked areas vary historically and have not correlated with changes in the reservoir level. The seepage is believed to originate from the ieft abutment and not the reservoir. The dam is equipped with two 90? v-notch seepage weirs located at the toe of the dam. The following readings were taken during this inspection: Right Toe Weir 0.34? (~77 gpm) Center Toe Weir 006? 1 gpm) These measurements are considered normal. I did request the center toe weir box be cleared of sediment and vegetation. The two seepage manholes for the embankment drains were also observed. The right manhole drain was flowing at approximateiy 1 and the left manhole drain was releasing a trickle. These conditions are considered normal. Live flows were audible heard along the hillside adjacent to the powerhouse. As described in the last inspection report, these flows originate from a French drain installed around the powerhouse use to divert hillside seepage. The flows observed were not abnormal and are not believed to be reservoir related. Minimal dampness and leakage was observed along the tunnel walls. The tunnel is equipped with an upstream and weir to measure flows. The upstream weir read 005? (~07 gpm). The majority of this flow was observed emanating from the tunnel plug. The weir read 010? (~37 gpm). The seepage conditions are considered normal. at this dam consists of piezometers, seepage weirs, embankment drain pipes, and survey monuments. The latest instrumentation report was submitted with an owner's letter dated January 29, 2014, for calendar year 2013. An addendum report was submitted with an owner?s letter dated May 29, 2014, addressing comments listed in our March 21, 2014 letter. Open Well Piezometers: The dam has 7 open well piezometers (1V-7V). The piezometers are located in the shell, of the chimney drain and above the blanket drain. Piezometers 1V, 3V, 4V, 6V, and 7V have essentially measured dry since readings began in 1992, indicating functioning chimney and blanket drains. Piezometers 2V and 5V, however, have consistently recorded values approximately 10 an_ above their tip elevations. This condition has existed since 1992. As stated in our past inspection reports, there were problems with the bentonite seal at piezometer 5V during construction that may be the cause for the abnormal readings. The high readings have yet to be addressed in the instrumentation report, as we have requested in our past letters and reports. SMUD has, however, committed to submitting a final written justification to DSOD by October 16, 2014 and include this justification in the 2015 instrumentation submittal, as stated in their letter dated May 29, 2014. The data is not presenting a dam safety concern at this time, has remained fairly consistent, and is not displaying any alarming Sheet 2 of 5 INSPECTION ?3 DAM AND RESERVOIR IN STATUS Name of Dam Union Valiey . Dam No. 1009-3 Date of Inspection 8/21/2014 Observations and Comments trends. Twin-Tube Hydrauiic Piezometers: The original 28 twin-tube hydrauiic piezometers have now all been abandoned in-piace as they have each reached the end of their useful lives. The proposal to discontinue monitoring the twin tube piezometers was approved in our letter dated October 7, 2013. plans to keep DSOD informed on all plans regarding the abandonment of the hydraulic piezometer equipment. They are currently investigating several options, ali of which provide for long?term seepage monitoring. SMUD has committed to provide us with one or more proposed actions by December 1, 2014, as stated in their letter dated May 29, 2014. During this inspection, we accessed the terminal well housing the hydraulic piezometer equipment. The piezometer equipment has been left in?place since abandonment. A trickle of ieakage was observed emanating from several tubes. The bottom flooring of the well had approximately 6 to 8- inchs of standing water. No drain in the well was observed. Reportedly these conditions are normal. Seepage Weirs: The dam has a total of four seepage weirs, 2 along the toe of the dam and 2 in the Readings at the upstrea_ weir are not included in the instrumentation submittals. Historical readings began in 1988. Both toe weirs have historically showed fluctuations with the reservoir level, more notabie at the right toe weir. Readings at the right toe weir have generally fluctuated between 0 and 450 gpm, with some occasional outlier data. The center toe weir has generally fluctuated between 0 and 100 gpm. Data over the last year has remained within these values and displayed no concerning trends. Since 1988, readings at the tunnel weir have ranged between approximately 4 to 20 gpm. From 1990 to 2009, readings were regulariy recorded between 6 and 8 gpm. Since 2009, data has jumped between 4 and 20 gpm. The readings are not considered abnormal and the data does not display any concerning trends at this time. Embankment Drains: The dam has 2 embankment drains, viewed and measured in manholes located near the toe of the dam. Both the right and left drains have historically recorded less than 2 gpm, since 1988. Data recorded over the last year has remained normai. Survey Monuments: The dam has a totai of 8 survey monuments located along the crest of the dam, which are surveyed annually for horizontal and vertical control. Horizontal and vertical movements since the last survey have been minimal, with less thar? of settlement and less thar_ of horizontal movement. Since surveys began in 1973, the maximum settlement equais approximatel_ and the maximum upstream and movement is equal to approximatel_ The movements are considered minimal over the last 40 years for the 453- foot tall dam. The current instrumentation network is judged to be adequate, and no additional instrumentation is deemed necessary at this time. As stated in the owner?s letter dated May 29, 2014, they have committed to submitting a final justification for the abnormal piezometer readings in open well piezometer 5V by October 16, 2014, and provide us with one or more actions for abandoning the twin-tube piezometers by December 1, 2014. Sheet 3 of 5 GTEGTE 3F LG: $13: GG. 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GtaGiG G, and intact The: Gang ihG? edge the WGVG run LG, 3G: rem-Gina: Gthi'G iG-tGGt. No GGtiviiy was. Dams ?3"in weir WGCG TGG EGG in EGG- EG the} Gay as. pm the ?e?i?ca?w Th8 gaffe-?5 mating in. TGG GEQQGG Gf and Skin arms and ta G2: in B-G'th gaiGG fuiiy in on 5 ?s er?- MG: SG by T. TT Fhatosiaken? Yes 3% Ga {Ga Gfif?stGC?Gn arm/2013; TTAT GG-fm Gate Gf'RGp'Grt 53.9"? 0123?! 3 GWR 1.251 {Reva She-Gt ff OF DAM AND RESERVOIR IN DER . STATUS Name of Dam Union Vailey Dam No. 1009?3 Date of Inspection 8/16/2013 Observations and Comments Outlet Seepage We entered the spillway from the end of the channel. The weep? ?ho e drains along the right wall appeared to be clear and functioning properly. Ms. Roach reported that concrete repairs were completed within the spillway channel just two weeks prior to this inspection. The repair work appears to have been satisfactorily completed. Existing repairs in the channel appear to be holding up well. Minor cracking and spalling still exists along the channel invert, but is not a dam safety concern at this time. The surfaces shouid continue to be monitored and repaired as necessary. The small vertical drops between invert panels, observed throughout the spillway, are a construction feature and not a sign of movement. Vegetation control throughout the spillway was good. The upstream gate and valve were fully cycled in presence on 9/26/2012. The owner annualiy operates the gate and valve to fulfill cycling requirement. The outlet tunnel and - penstock were not observed during this inspection. The unlined tunnel was last inspected by DSOD on 9/26/2012, and it was found to be in good condition. Arrangements to inspect the tunnel should be made during the next annual inspection. Dam: No seepage was observed on the groins. The historical wet spots on the face, by the left groin, were observed. Wooden posts mark the areas where seepage has been observed. A third wooden post has been added within the last year, as requested in the last inspection report. Each area was damp, but no live fiow was observed. Seepage conditions at the marked locations vary historically and have not correlated with changes in reservoir level. The seepage is believed to originate from the left abutment and not the reservoir. inspected the two seepage manholes for the embankment drains at the toe of the dam. The right embankment drain was flowing gpm, and the left embankment drain had only a trickle of flow. The two 90? degree v-notch weirs at the toe of the dam had the following readings: Right Toe Weir 0.29? (~52gpm) Center Toe Weir dry These seepage conditions are considered normal. The live flow observed emanating from the hillside adjacent to the powerhouse, described in the last inspection report, was observed. DSOD requested the owner install a new seepage weir to measure this flow. The owner has investigated the seepage conditions and found the flow is actually originating from a French drain, which was installed to divert hiilside seepage around the powerhouse. There are two French drain outfall locations, one upstream of the powerhouse (location described in this report) and a second outfall of the powerhouse. Since the seepage is not reservoir related, the owner does not see a need to install a seepage weir. I agree with this assessment. The drain outfall upstream of the powerhouse, near the toe of the dam, was flowing approximately 5 during this inspection. Tunnel: The unlined tunnel is equipped With two 90? v?notch seepage weirs, one located of the tunnel plug (upstream weir) and the other at the and of the tunnel Sheet 2 of 7 OF DAM AND RESERVOIR IN GEEK i STATUS Name of Dam Union Valiey Dam No. 1009?3 Date of inspection 8/16/2013 Observations and Comments Instr. weir). The following readings were taken during this inspection: Upstream Weir Not observed during this inspection. Weir 0.12? gpm) The weir reading is considered normal. Spillway: Minimal dampness was observed at various spillway joints, as is typically reported. The right wall weep drains were emanating only a trickle. The drain pipes observed under the flip bucket section were dry. These seepage conditions are normal. instrumentation at this dam consists of 7 open well piezometers, 2 twin?tube hydraulic piezometers, 2 seepage weirs, 2 embankment drain pipes, a tunnel plug weir, and 8 survey monuments. The latest instrumentation report was submitted with an owner?s letter dated January 28, 2013, covering data for calendar year 2012. Piezometers: The open well piezometers (V1 - V7) are located in the shell, of the chimney drain and above the blanket drain. Data is presented from 1992 to 2012. As usual, 6 ofthe piezometers (V1, V2, V3, V4, V6, and V7) have remained constant over the last year and since readings began in 1992. Piezometer V1, V3, V4, and V7 continue to read dry. Piezometer V2 and V6 consistently record levels up to 10 an_ above their tip elevation. Piezometer readings for open well V5 also have remained nearly constant in 2012, at elevation This was below the owner?s action value 01? As noted in previous inspection reports, piezometer V5 has recorded over_ of standing water. It was noted that there were problems during the placement of the bentonite seal during its installation. DSOD has asked the owner to investigate the source of the high readings and the functionaiity of the piezometer. This issue was not addressed in the latest instrumentation submittal. In a March 28, 2013 letter, due to the piezometers being over 30 years old we requested all the open welt piezometers be tested to verify their functionality. Following the letter, the comments were discussed over the phone between Mr. Chris Moffitt with SMUD and Area Engineer Aspet Ordoubigian. It was concluded that the piezometers do not need to be tested at this time and the items will be addressed in the next instrumentation submittal. The twin tube hydraulic piezometers P-5 and P-6 are located near the bottom of the core section. Each piezometer has remained nearly constant over the iast year and over the life of its data; however, in a July 23, 2013 letter from the owner, both remaining twin tube piezometers are reportedly no longer functioning and readings have been discontinued. As mentioned in the last inspection report, the 7 open well piezometers were installed in the late 19808 to compensate for the unreliable data, which was being provided by the twin tube piezometers; therefore, abandonment of the piezometers as they fail is acceptable. Additional information is included in the 8/12/2010 inspection report. The piezometer data indicates that the chimney and blanket drains continue to function properly. No abnormal conditions were noted over the last year; however, the owner needs to address our comments listed in our March 28, 2013 letter, in the next instrumentation submittal. Comments inciude testing all open well piezometers to verify their functionality, as well as plotting the reservoir elevation and piezometer ievels on different y-axis scales for readability. Seepage: Seepage data is presented from 1988 to 2012, in the latest report. Readings for the Sheet 3 of 7 ENSPECTIOR DAM AND RESERVQIR IN CER .. STATUS Name of Dam Union Valley Dam No. 1009-3 Date of inspection 8/16/1201 3 Observations and Comments weirs and drains are taken Seepage readings for 2012 remained within the historical values with exception of a 2/14/2012 reading at the Right Toe Weir equal to 1009.9 gpm. This exceeded the owner?s action value of 680 gpm, The owner inspected the weir following the reading and attributed it to a particularly wet storm during which the reading was taken. All other readings remained within the historical values. Seepage for the weirs and drains typically fluctuate within the following values: Right Toe Weir ~50 to ~500 gpm, Center Toe Weir ~0 to ~100 gpm, Tunnel Weir ~4 to ~12 gpm, and both the Right and Left Embedded Drains measure less than 2 gpm. Occasional spikes in data are observed at each weir. All seepage data is considered normal. Survey Monuments: Survey monuments are located along the crest of the dam and surveyed annually for horizontal and vertical control annually. Monument data dates back to 1973. Settlement values over the last year have been minimal. The maximum settlement observed since 1973, is at monument located near the maximum section of the dam, of approximately 0.12- feet. The majority of settlement occurred following the initial surveys. Since 1988, settlement data has been less thal- Horizontal movements over the last year have also been minimal, approximately less thar- Historically, horizontal movements have been no more than 0.1- feet in either the upstream or direction. Monument movements are considered minimal. The current instrumentation network is judged to be adequate, and no additional instrumentation is deemed necessary at this time. The next instrumentation submittal needs to address our comments included in our March 28, 2013 letter to the owner. Sheet 4 of 7 ?zmw MK mawrww. Emma 093. C333 . . . He. ..Emumsw .way/2 .. a .1Cth/w/rt?g/uwa?? ?mam