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DR1101-CS081013Page 1 of 1 Ken Griffin - FW: Luminant - Dam Inspection Report From: "Bill Walker" <BWalkergBillingsleyco.com> To: <jwittgci.coppell.tx.us >, <kgriffingci.coppell.tx.us> Date: 10/13/2008 3:55 PM Subject: FW: Luminant - Dam Inspection Report CC: "Laura E. Hebert" <lhebert9CCSB.com> Attachments: 080926 Luminant Letter.pdf; Dam Inspection Report.pdf From: ROY.WILSHIRE @kimley- horn.com [mailto: ROY.WILSHIRE @kimley- horn.com] Sent: Thursday, October 09, 2008 10:56 AM To: Bill Walker Cc: Dan.Grant @kimley- horn.com; brad.moss @kimley - horn.com Subject: Luminant - Dam Inspection Report w Attached is a copy of the 2007 Dam Inspection Report for your files. I'll return the original to you this afternoon. Roy L. Wilshire, P.E. Kimley -Horn and Associates, Inc. 12700 Park Central Drive Suite 1800 Dallas, Texas 75251 972 - 770 -1300 972 - 239 -3820 (fax) 214 - 914 -1193 (cell) file: //C:\D ocuments and Settings \lhenderson \Local Settings \Temp \XPgrpwise \48F36F62Cit... 3/5/2012 0 11 Luminant Date: September 26, 2008 To: Brett Wiggs cc: From: Rick Jeanes Subject: 2007 Phase I Dam Inspection Report for North Lake Dam Office Memorandum In response to your request, I have enclosed with this letter of transmittal a copy of the 2007 Phase I Dam Inspection Deport for North Lake Dam. This report is based upon an inspection conducted on November 14, 2007 by Janis Murphy, P.E., of Freese and Nichols, Inc. As stated within the report, North Lake Dam was determined to be in satisfactory condition and able to perform its design function upon completion of the 2007 inspection. Since the completion of this inspection, Luminant has reviewed the evaluation by Freese and Nichols and made significant progress toward addressing identified maintenance repairs. Luminant's progress to address these action items is as follows: • The roadway across the crest of the main embankment and saddle dam has numerous cracks and deep potholes that were standing in water at this inspection_ These cracks and potholes need to be filled in to prevent water from saturating the embankment and causing additional surfical slides. Approximately 2500 linear feet of roadway repair work has been completed between the pavilion and the right abutment of the saddle dam. • The old 18 -inch cast iron outlet pipe on the left side of the service spillway has been abandoned with a blind flange installed at the intake during reservoir construction. This outlet should be monitored periodically for seepage which would indicate that the blind flange or outlet pipe is leaking. This area is currently overgrown preventing observation. This area should be cleaned out and the valve monitored. Accumulated soil and debris have been cleared from around the outlet to facilitate monitoring by plant personnel during routine inspections. • The rodent holes on the saddle dam and the main dam should be filled and the areas seeded. Inspecting for and repair of rodent holes is a routine maintenance item conducted by plant personnel. • The right abutment area on the saddle dam should be regraded to improve drainage. Seepage will most likely still be present and it should be monitored for changes in clarity or quantity. Although the identified seepage area on the right abutment of the saddle dam remains dry during the summer months, this area has been regraded to improve rainfall runoff to eliminate pooling of water in rutted areas caused by mowing activities. The area will continue to be monitored for any signs of seepage by plant personnel performing routine inspections. • The rock riprap in the left abutment area should be monitored. The exposed bedding material may need to be covered with additional rock riprap. The exposed bedding material located at dam station I5 +00 on the saddle dam is presently stable and recent inspections have not revealed any signs of exposed embankment soil which would warrant the need for immediate repair. Plant personnel will continue to monitor this area during routine inspections. • The spillway joints which have some separation should be filled with a joint sealant. This will most likely be an ongoing maintenance item. Expansion joints in the uncontrolled concrete spillway have been cleaned, primed and sealed with an elastomerle joint sealant CONFIDENTIAL • The trees and thick vegetation adjacent to the spillway discharge channel should be cleared. This work has been completed • The vegetation adjacent to the spillway walls should be removed. This work has been completed • The security fence at the downstream property limit should be repaired. This work has been completed • The low area in the main embankment should be monitored for additional signs of movement. Plant personnel will continue to monitor this area during routine inspections. • Continue to pump the toe drain system on the main dam. Pumping of the toe drainage system is required due to siltation and inadequate drainage on South Grapevine Creek off Luminant property. Pumping of the toe drain system will be continued until downstream property owners correct the drainage problems which are backing water into the toe drain outlet pipe. • Survey the reference monuments installed on the crest of the main dam annually to monitor for additional signs of settlement. An annual survey of settlement monuments along the crest of the main dam was conducted in 2008. A comparison of the new survey data with baseline data was unremarkable. • Continue to read the piezometers. The frequency of readings can be changed to quarterly. Piezometer P- 105 has exhibited some erratic readings and should be abandoned and a new instrument installed in the vicinity of the current one. Although piezometer P -I05 continues to exhibit erratic readings, recent piezometric water elevation readings are below the action level established by Freese and Nichols, Inc. No action has been taken at this time to replace this piezometer. • The void under the concrete crest of the service spillway at the left end should be filled. This work has been completed .Rick jeanes CONFIDENTIAL Page 2 of 2 Phase I Darn Inspection Report for North Lake Dam TX 00832 Phase I Dam Inspection for North Lake Daze TUE07434 ATR: 58280 Agreement No. S 0204353, Amendment 3 January 2008 Prepared for Luminant Power i ]•� -J� N _ ., �i • �I a i/ X1 , Freese and Nichols, Inc. 4055 lntemational Plaza Suite 200 Fort Worth, IX 76104 8171735 -7300 TABLE OF CONTENTS Phase I Dam Inspection Report for North Lake Dam Page 1.0 INTRODUCTION ...................................................................................... ..............................1 2.0 PROJECT DESCRIPTION ........................................................................ ..............................1 3.0 REVIEW OF PREVIOUS REPORTS ....................................................... ..............................3 4.0 CURRENT INSPECTION ......................................................................... ..............................4 5.0 EVALUATION AND RECOMAH NDATIONS ....................................... ..............................7 APPENDICES Appendix A References Appendix B Photographs Appendix C Dam Inspection Check List Appendix D Instrumentation Readings North Lake Dam i 2007 Inspection PHASE I DAM INSPECTION REPORT FOR NORTH LAKE DAM 1.0 INTRODUCTION The dam safety inspection of the North Lake Dam was conducted on November 14, 2007. The inspection was performed in accordance with Freese and Nichols proposal dated, October 9, 2007, and authorized by L uminan t Power's ATR 58280 dated October 29, 2007. The inspection consisted of visual observations regarding the general condition of the dam and a review of previous inspection reports. Participants in the field inspection were Milton Vrla, P.E., Greg Stuckey and Terry Perry of Luminant Power and Janis Murphy, P.E. of Freese and Nichols, Inc. 2.0 PROJECT DESCRIPTION North Lake Dam was constructed in 1956 and 1957 to provide a cooling reservoir for the operation of North Lake Steam Electric Station. The dam is located in northwestern Dallas County, Texas and is maintained by pumping from the Elm Fork of the Trinity River when necessary. Normal water elevation in the reservoir is elevation 510 feet msl. The dam consists of two separate embankments, designated herein as the main daze and the saddle dam with a combined length of approximately 4,800 feet. The north end of the main dam is tied into a dike system approximately 5,000 feet in length along the north shoreline of the lake. The main dam is oriented in a north -south direction and consists of an unzoned earthen embankment with upstream and downstream side slopes of 3 horizontal to 1 vertical and a crest width of 12 feet. The dam has a maximum height of 65 feet and a design top- of-dam elevation of 515 feet msl. The upstream slope is protected by rock riprap extending from elevation 490 feet msl to the crest. The downstream slope is protected by a well- maintained grass cover. The crest of the dam has a paved asphalt road. In addition, a three -foot high (elevation 518 feet ms1) precast concrete wave wall was added in 1993 to provide additional fimboard against wave action during a Probable Maximum Flood event. Seepage control is North Lake Dam 1 2007 Inspection provided by a sand blanket along the toe of the dam. A French drain collection system has been tied into the sand blanket and discharges into the South Fork of Grapevine Creek. A cutoff trench under the dam extends into unfissured clay or shale. The saddle dam is located south of the main dam, has a maximum height of 25 feet and has a 12 -foot wide crest. The saddle dam was constructed in a similar manner as the main dam except that the cutoff trench was omitted. During the 1970'x, additional fill was installed to flatten the downstream slope to 3.8 horizontal to 1 vertical. The upstream slope is protected by rock riprap. A three -foot high precast wave wall was also built on the saddle dam. The spillway consists of an uncontrolled concrete overflow section built into a hill separating the two embankments with a crest elevation of 510 feet msl. The spillway discharges into the South Fork of Grapevine Creek (part of the watershed of the Elm Fork of the Trinity River) through a concrete -lined channel. The area downstream of North Lake Dam has undergone considerable residential development which makes the dam a high hazard dam.. Both the main and saddle dams have experienced surfical slides on several occasions. These slides are attributed to the high - plasticity clays in the embankments. The installation of a sprinkler system to maintain moisture in the downstream topsoil has reduced dessication cracking which is a major contributor to surfical slides. A French drain seepage collection system has been installed in the sand blanket at the toe of the main dam to reduce piezometric pressures in the slope. The piezometers initially installed to verify this reduction have been abandoned, so the actual piezometer level is unl mown. Settlement monuments for the main dam were moved to the centerline of the roadway after being damaged by a contractor performing repairs to the irrigation system control wiring. These monuments were not surveyed prior to the 2007 inspection. The Emergency Action Plan for North Lake Dam was updated in 2005 and there are annual updates of the phone numbers. An 18 -inch service outlet with a valve control on the downstream side was made inoperable during construction. The pipe was capped on the upstream end with a blind flange. According to the record drawings, a break in the pipe was discovered after the lake was North Lake Dam 2 2007 Inspection i L.._, filled. A blind flange and a small drain were added a few years ago at the downstream end to check for leakage. A river pump station outlet is located on the left end of the dam. This structure consists of a 42 -inch pipe to pump water from the river to the lake. Two 12 -inch valves can release water back into the Elm Fork of the Trinity River. 3.0 REVIEW OF PREVIOUS REPORTS North Lake Dam has been inspected on numerous occasions. The most recent inspection was performed in 2006. The inspection found the dam to be in satisfactory to good condition. The items recommended included the following: 06-01 Continue periodic repair of ruts and depressions in access road across main embankment and saddle dam by filling with crushed road base material. This item is a repeat of item 02 -1. This was performed adequately lastyear and can be removed from the action list although the activity should continue as part of routine maintenance. Item 07 -01 replaces this item. 06 -02 Continue annual vegetation removal and eradication program in the rock riprap on the upstream slope of the main dam to control brush, weeds, vines and Johnson grass. This had been performed last year, but there was some vegetationpresent in the rock riprap. This item should be added to a list of routine maintenance items. 06 -03 Continue monitoring of seepage (when it occurs) on the downstream slope and settlement within the parapet wall. Included in this dam is also the monitoring of five piezometers in 2004 to assist in the assessment of the possible increase in piezometric pressures within the embankment. The present low lake level has yielded tentatively stable pressure readings: The seepage was determined to be leaks from the irrigation system. This item can be removed from the action item list. 06 -04 Continue monitoring of both future vegetation growth and additional signs of movement within the concrete lined service spillway. Relatively minor spalling has been noticed at some joints in the spillway. Additional movement will require either further assessment or replacement of specific areas. The vegetation has been North Lake Dam 3 i 2007 Inspection r ..i removed from most of the spillway channel. There were a couple of areas which need vegetation removed This item should be added to a list of routine maintenance items. 4.0 CURRENT INSPECTION At the time of the current inspection, the lake level was slightly below elevation 510 feet msl, the normal water level. The weather condition at the time of the inspection was clear. Photographs taken during the inspection are included in Appendix B and the TCEQ checklist is provided in Appendix C. The following items were observed in this inspection: Main Data The crest of the main dam has an asphalt road which was in good overall condition. There was some damage to the road from repairs to the irrigation system which were accomplished earlier this year. The wave wall on the upstream edge of the crest is misaligned both horizontally and vertically. The timber guard posts on the downstream edge lean significantly. There is some longitudinal cracking along the downstream edge of the crest road, and one area had a void under the edge of the pavement. There is one area near the right end of the main dam which appears to have experienced settlement. The upstream slope has a good layer of rock riprap. There are a few areas with some minor vegetation growing in it As can be seen in Photo No. 37, the water line is uneven near the right end. This corresponds to an area of settlement in the dam. i The downstream slope was in good overall condition. The downstream slope has had a history of minor surface slides. A large slide occurred in January 2007. A second slide occurred in June 2007. Both have been repaired and the areas have been covered with grass. The downstream slope of the main dam should be monitored for additional signs of movement. Prompt repairs of the surface slides are important to the long term stability of the dam. There have also been some repairs to the irrigation system on the downstream slope. A few animal burrows were noted on the downstream slope. The main dam sand blanket toe drainage system discharge pipeline has been plugged downstream of Manhole No. 2 due to blockage in South Grapevine Creek off of Luminant North Lake Dam 4 2007 Inspection .., property. Any seepage collected in the drainage system is being pumped to keep the sand blanket properly drained. There are piezometers located on the main dam which are read monthly. The instrumentation readings are included in Appendix D. Piezometer P -105 has exhibited some erratic readings. The other instruments have readings which are considered reasonable. Saddle_ Dam The crest of the dam was in good overall condition. The road consists of an asphalt road which has been covered with crushed stone. There are a couple of areas which are netted and pond water. Most of these areas were located near the left end of the saddle dam. The wave wall on the upstream edge of the crest is misaligned both horizontally and vertically. The upstream slope has good rock riprap protection. Portions of the slope appear steeper than others. The water line is somewhat uneven and the rock at the waterline is smaller than the rock higher on the slope. The larger rock was added during the installation of the wave wall. One area near the left junction with the natural hillside appears to have some exposed bedding material at the waterline. There is some minor vegetation growing in the rock riprap which needs to be removed. The downstream slope is in good overall condition. It has adequate grass coverage. A sprinkler on the saddle dam was broken in early November and repairs have been made. The right downstream abutment area has a large area with numerous wet spots. There was no apparent flow, but several areas of ponded water. This area is roughly graded which probably contributes to the ponding of the water. The grass coverage is good and the slope is well maintained. There are a couple of areas of thin grass coverage. There are a few animal. burrows on the slope and one area where there are five to six holes together and one large (three -foot diameter by one -foot deep) hole. One area on the slope had water present. This area was where the mowers had formed some ruts. Snillway The spillway crest and overflow area are in good overall condition. The approach to the spillway is protected with rock riprap. The rock provides adequate protection but is smaller North Lake Dam 5 2007 Inspection r_ near the right side. There is one area where the rocks appear to have been moved and water is ponded due to the creation of a low spot. The roadway crest concrete is in good overall condition. The upstream edge of the trench which collects low flows and directs them under the road has experienced some deterioration of the concrete and some exposed rebar. The pipes which flow under the road are in good overall condition. There is a void under the concrete at the left downstream end of the road. There is some minor seepage at the bottom of the expansion joints on the sloped portion of the spillway. Expansion joints on the sides of the spillway are open. Sealant has been placed in these joints but movement or shrinkage has occurred opening them up again. The channel is in good overall condition. There is some seepage from the wall drains. There is also some cracking and calcification. The vegetation is encroaching on the outsides of the spillway walls. There does not appear to be any significant trees yet, but the vegetation is hanging over the walls. The spillway channel was replaced in 1999, and some additional repairs have been made to the walls where separation and cracking has occurred. There are a couple of areas near the downstream end on the left side where there is a void at the junction of the wall with the floor. The stilling basin was in good overall shape. The left end is approximately a half inch lower than the right end. There were some rocks in the basin which should be removed. The discharge channel downstream of the stilling basin has become very overgrown with reeds and trees. Many of the trees are large. The 18-inch low flow outlet was abandoned during initial construction of the reservoir and a blind flange has been installed on both ends of the structure. There is a small drain valve which was added to check for leafage. This structure is an offset area along the spillway channel. The area is very overgrown with reeds and observation was not possible. Riv r hM Station Dischar a Outlet The river pump station discharge outlet structure located on the left upstream abutment of the dam was observed. North Lake Dam 2007 Inspection 6 The metal portions of the structure are in need of painting. The two valves do not appear to function. There is significant corrosion of the pipes, valves, and stems. Other Areas There is significant development occurring downstream of the dam. Newly constructed houses are immediately adjacent to the downstream security fence. There are numerous holes in the fence and construction debris from the housing development has been dumped on Luminant property. There is also some wet area adjacent to the downstream fence. The source of the seepage in this area is unclear. 5.0 EVALUATION AND RECOMMENDATIONS Based on the visual inspection, North Lake Dam is in satisfactory condition and able to perform its design function. The following recommendations are made: 07 -1 The roadway across the crest of the main embankment and saddle dam has cracks and low areas that hold standing water after rains. These cracks and low areas need to be filled in to prevent water from saturating the embankment and causing additional surfical slides. 07 -2 The old 18 -inch cast iron outlet pipe on the left side of the service spillway has been abandoned with a blind flange installed at the intake during construction of the reservoir. This outlet should be monitored periodically for seepage which would indicate that the pipe -is leaking. The area is currently overgrown preventing observation. This area should be cleaned out and the valve monitored. 07 -3 The rodent holes on the saddle and main dams should be filled and the areas seeded. 07-4. The right abutment area on the saddle dam should be regraded to improve drainage. Seepage will most likely still be present and it should be monitored for changes in clarity or quantity. 07 -5 The rock riprap at the left abutment area should be monitored. The exposed bedding may need to be covered with additional rock riprap. North Lake Dam 7 2007 Inspection 07-5 07 -7 07 -5 07 -9 07 -10 The spillway joints which have some separation should be filled with a joint sealant. This will most likely be an ongoing maintenance item. The trees and thick vegetation adjacent to the spillway discharge channel should be cleared. The vegetation adjacent to the spillway walls should be removed. The security fence at the downstream property limit should be repaired. The low area in the main embankment should be monitored for additional signs of movement. 07 -11 Continue to pump the toe drain system on the main dam. 07 -12 Survey the reference monuments installed on the crest of the main dam annually to monitor for additional signs of settlement. 07 -13 Continue to read the piezometers. The frequency of readings can be changed to quarterly. Piezometer P -105 has exhibited some erratic readings and should be abandoned and a new instrument installed in the vicinity of the current one. 07 -14 The void under the concrete crest of the service spillway at the left end should be filled. North Lake Dam 2007 Inspection I e�� APPENDEX A APPENDIX A REFERENCES 1. Texas Department of Water Resources, Phase I Dam Inspection for North Lake Dam, Dallas County, Texas, October 1978. 2. Freese and Nichols, Dam Safety Inspection Report for North Lake Dam, TX00832, Dallas, Texas, March 2004. 3. Quality Consultants, Phase I Dam Inspection North Lake Dam, Dallas, Texas, June 13, 2047. APPENDEK B PHOTOGRAPHS z 0 H a CD z a w ,z Q 7 c), Q � n nG. 8 U U) a 0 d� 0 E � LU i p ti a t Ir4 Y � Iq .l _16\a 16,110 o � a z 0 H a CD z a w ,z Q 7 c), Q � n nG. 8 U U) a 0 d� 0 E � LU i p ti a t Ir4 Y � Iq .l _16\a 16,110 � \. ® \�. >��6 \ry z? m�G y Phoio No, 1 1 ooking along [lie crust ol'the saddlc dam FI near the right end. \or*h I ake Dm N-vvvmher 1 200' 2007 InspecLi011 Photo No- 1: Looking at the crest o0he saddle dam (0"'JrLI ±e& l abutment- Photo No. _ >: Looking alone the crc;l Of tllC ti.uicllt c WI) tMWI - d OIC ILII al�ttllltcttl. r F4 ti e � r Photo No. 4 I'mided wma in dw tklml Fiat [tic C1'12st l the 4 ;Id lle chIII, North 1„ tke Dam — -- N«vcmbur lei, 2007 2007 Inspecti011 - 77 4 Photo No. 5: Looking along the wavc wall at the upsti edge of crest of the %addlc (kim. Moo Photo No, 6. Lkinking at (lic \%;tvc vall on the saddle darn. 'tiote 1111sallpill"crit Of the wall. \ - 7 - - v - - orth I A Dam 1007 11IN I . pection Novembu 14. 2007 VIA r.1 x )y vs, j its. . X. V �%% photo No� 7 LookinLl iIt (lie LIJ)StI slope ol*the saddle dam From the right abulmclit. AMA , il.l North Lake Dam November H. 2007 2111 , J7 111SI)CCI Photo No. 9: looking al the upsircam slope of saddlc daill. Pho(o ""o, 9: 1 ooking along the waterlinc ol'thk: sadly dam. Note in %vater line. ,North Lake Dmu Nov�:mhcr 14- 2007 "007 hv�pccfimi Photo No. 10: (hcrview ol'the downstream slope of the saddle daim Phom No. 11: Ow nlcw o[ the right ahutnicni ol'the saddle dam. Area IN WLI�,Ill} LI Z111LI IIZIS MMICI M 0f'SCejM VC- T.TV "At Al J41 i Photo No. 1 2: One of several al-e 0 �CC 1):iL'C .It the ri�Jll mclit of Olc Naddic dani. NOT11i Lake Dan) No% 14, 2007 2007 Inspection r o 4 f r P ' rl kli i r r+rF 1^r }� F , 4 A m t 4 ,p i -'r 1 . 44 a r FA Photo No. 14: I:xlimed L,rovel I)CLI Ing on the lect�abutment (11 tie tiaddle dam. North Lake Dam November 1 .1. 2007 '.007 lnxlic;eticm Ph oto �+o. 13: .r+,tlim burn1'lL IOULLICLI 01) till.' saticlle ddIll iM11 417x: 10C. A AAAP.60, Pho In No. 15: 1. ook I ng acros-, the crest oft he scrvice spi I I �,vay. A A11111'OdCh (L' the servic-c spilkka\. North hake Dam Novcmber 14, 2007 -1 007 Ins � pection I'lioto No. 16: North Lake [lam November 14, 2007 Photo No. 19: Area of ponded water in the approach to the service spillway. .wr c .f F., • I '.,� r fr a. , a ,may d -• Photo Trio. 17: Approach to the service spillway. Rock protection appears thin in places. North Lake [lam November 14, 2007 Photo No. 19: Area of ponded water in the approach to the service spillway. ■, ti k `. , y # W At I way M � � "► 7. � Jk Ax Photo No, 19: Upstream edge of the service spillway crest. Note deterioration of the concrete. Water goes under the road through pipes. p n n Photo No. 20: Entrance to the side channel spillway. SAfti 1 nu North Lake Dam November 14, 2007 Photo No. 21 Pipe which carries water under the road on the service spillway crest. IAI Photo No. 22: Hole located on the downstream side under the road on the service spillway at the left end. North Lake Dam November 14, 2407 Photo No. 23: Looking at the junction of the service spillway channel with natural ground between the saddle darn and the spillway. North Lace Dam November 14. 2007 Photo No. 24: Open joint on the slope paging downstream of the crest of the spillway. e Noah Lake Dam November 14, 2007 Photo No. 25. Looking downstream in the side channel spillway. Note slight seepage at the bottom of the expansion joints. Photo No. 26: Looking downstream in the spillway channel. I North Lake Dam November 14, 2007 Photo No. 27: Looking downstream at the stilling basin for the spillway Photo No. 28: Misalignment of the spillway wall on the right side. Photo No. 29: Low flow 18-Inch outlet pipe which has been decommissioned. Note seepage from adjacent wall drain. Photo No. 30: Repaired section of the spillway wall. Note continued movement at the joint. North Lake Dam November 14, 2007 ,r 0 Photo No. 32: Exposed rebar at the bottom of the wall. r § 1 North Lake Dam November 14, 2007 Photo No. 31: Separation of the spillway wall from the channel floor. 71 an qt TIN 1, , � �� Photo No. 13 /��� z � & �' � � � ? �r£ / ��� \� �\ � /�`\�� �d/ ~ � 2� Phuto A» 34 kooking along the crest of dam froill me H \# ClId. \ \ � �� � S NOrlh Lake Dam Novusn r W. 2007 2007 Inspection I : 11 d Si I 1 0 ( t IIC 1XIS i 11 WILI C 11,11i ne I d n stroa in. L et e f t s i de 1 s abo Lit a O.S inch Iowa than right side. PhowMo. 35: |ookiKAo\ongUnc crcx of [lie main Jan, 1rnmnuorUurnxb(1c. \vurc , wail is also misaligned on the main dam. A 7P ' North i/Jko1)� om ---- ------------------------------- --- --- November 1-1, 2007 200 Inspection .. r l'1 olo No.:+g: t )l` wt In 1vaw wall on nmin droll. North Lake Dam Nok 1 -1, 007 24107 Inspects l I'hlltcl No, IT O) crt is \a of dw upstream slope 1lf'the main da m, Nolc change in "'OlG111TIC Alld t[ll'1 CS11011111lit! (.1111 111 '\.:t 't' 1'14111. IL Photo No. ll), (111 downstreall) slope of the maill '. 1 M ir� , 4 Pho(o No. 40 North Lake D No%-cmbcr 14, 2007 21187 Inspecti : Repaired slopc i'llilurc oll flic main dime [rom Jalmar\ 2007. Aill. I'llWA) I llllg,-�Llion sN aem rcImirs on the Illaill daill. Photo N(1. o driin vauh, at to of the miiln Jluil., k — in I - a - kefTl�Iii - '007 Inspection Photo No- Vii: Inside the IminhoiQ shown in photo No. 42, i 1 Photo Nei. 44. Rccently compIcted slope rcparir area on ni,Iin dan't from �I JUIIC 2007 tilicle. Norlh Lake Dmii November H, 2007 "007 Inslicctioll I rl + N , +� ifs• �, � 4r �, ���,�,�y�- � , �.; �_ ,r , - �' ��� 4 �:? •+V .fin r . Nr yll Photo Via, 45: I.00king at the ILCI ahutIax•nt 0t'tIle 11111in d,1111. AOL T � - P s D a Photo, No. 46: 1ANI 11 IC dMi11 m,rnhole Itcre water is ptianpcd from tli s\—Aoni. Nurtlt [A [ }sam — -- - —� November 1'4, 007 M0 I v pectinn 26( Jv i 4 P: I'lloto No. 47: SCMCC ITIlet"outlet at the left end of dw niala dani. North I ake her - 14.200 - 7 - '-0() Inspection Photo No. 49: Looking at the pipe ITISidC the service outlet structure. Note deterionition of the stem pipe For the ,al%e operator. Photo No. 49: fouses located do \ nstrcam o I'the clam. .\orth 1 AL! Dam Novcmber 1 1. _00 - 200 InspcCtiorl I'lint(i No. 50. One of the several holes in the fcnce on the di wnslrciun propem line. APPENDIX C DAM WSPEMON-CEECKUST Texas Commission on Environmental uali Q tY Dam Inspection Form Inspection Results —Dam Conditions Dam Name: North Lake Dam Inventory No: TX 00832 Name of Inspector /s: Janis h P.E. Freese and Nichols, Inc. Name of Contacts: Milton Vrla. P.E., Teruv Perry., Grep—Stuckev, Luminant Power Date of Inspection: 11/14/07 Start Time: 8:00 am End Time: 12:30 pm Weather: coo Crest level (at center) above water: 5 feet Service spillway level ® Above or ❑ Below water: 510 feet msl Emergency spillway level above water: 0' Ground Moisture Condition: ❑Dry []Damp ❑ Wet ❑ Snow ❑ Other: Crest of Embankment General Condition: ® Good ❑ Fair ❑ Poor Width. 12 feet Height: 65 feet main dam: 25 feet saddle dam Length: 4,400 feet Problems Noted: ❑ None ® Rutting ❑ Erosion ❑ Poor Drainage ❑ Trees ❑ Depressions ❑ Bulges ❑ Livestock Damage ❑ Cracks ❑ Misalignment of Crest [] Misalignment of Utility Poles ❑ Misalignment of Fences or Rails ❑Sinkhole ❑ Burrows ❑ Breached ❑ Other: Comments: Upstream Embankment General Condition: ® Good ❑ Fair ❑ Poor Slope: 3:1 main and saddle Problems Noted: ❑ None ❑ Rip -Rap ❑ Erosion © Too Steep ❑ Burrows ❑ Trees ❑ Cattails ❑ Depressions ❑ Bulges ❑Livestock Damage ❑ Slides ❑ Concrete Decay ❑ Cracks ❑ Sinkhole ❑ Benching ❑ Misalignment of Rip -rap ❑ Open Joints in Concrete Comments: Minor vegetation in frock riprap. Downstream Embankment General Condition: ® Good ❑ Fair ❑ Poor Slope: 3 :1m in• 3.8 saddle Problems Noted: ❑ None ❑ Sloughing ® Erosion ❑ Too Steep ® Barrows ❑ Trees ❑ Cattails ❑ Depressions ❑ Bulges ❑ Livestock Damage ❑ Slides ❑ Concrete Decay ❑ Cracks ❑ Sinkhole ❑ Other: Comments: TCEQ -20361 (2107) - 1 - Seepage on Downstream Slope Amount: ❑ Major ❑ Moderate ® Minor ❑ None pound Problems Noted: ❑ None ❑ Saturation Starts at % up Embankment ❑ Presence of Sediment in Flow ❑ Cattails at Toe of Dam ❑ Surface Water at Toe of Dam ❑ Seepage Associated with Sloughing ❑ Continuous Flow ❑ Sporadic Flow Comments: Wet at the right abutment of the saddle darn. Downstream Hazard Conditions ❑ Narrow Canyon ❑ Wide Canyon ❑ Lightly Sloping Prairie • Pastureland ❑ Large Trees and Forest ❑ Brushy and Scrubby Forest ❑ No Homes • Lightly Populated ❑ Moderately Populated ® Densely Populated ❑ Industrial ❑ Businesses Estimated number of homes: Comments: Service Inlet Structure General Condition: ❑Good ® Fair ❑ Poor Problems Noted: ❑ None ❑ Blockage ❑ Not Located ❑ Steel Corrosion ❑ Concrete Spalling ❑ Concrete Cracking ❑ Reinforcement Corrosion ❑ Missing Parts ❑ Timber Decay ❑ Leakage Below Water Level E Inoperable Valve ❑ Other: Comments: River pump station discharge outlet is a 42 -inch gipe to pump into the reservoir._ Two _12- inch_valves can release water back into the Elm Fork of the Trinity River. Valves appear corroded. Service Outlet Structure General Condition.: ❑ Good ❑ Fair ❑ Poor Problems Noted: E None ❑ Blockage ❑ Not Located ❑ Corrosion of Conduit ❑ Presence of Sediment in Flow ❑ Inaccessible ❑ Concrete Cracking ❑ Concrete Spalling ❑ Reinforcement Corrosion ❑ Misalignment of Walls /Slabs ❑ Open Joints Comments: Low flow_sy_stem is an 18 -inch pipe. Structure is cgoed on the upstream and downstream end with blind flanges. It has been decommissioned. Service Spillway Condition: ® Good ❑ Fair ❑ Poor Depth: 0.5 feet Width: 200 feet Problems Noted: ❑ None ❑ Blockage ❑ Not Located ❑ Trees ❑ Burrows ❑ Back - Cutting Erosion ❑ Inaccessible ❑ Livestock Damage ®Concrete Cracking ®Concrete Spalling ❑Reinforcement Corrosion ❑ Damaged Water -stops ❑ Open Joints ❑ Sinkholes ❑ Holes in Spillway Chute ❑ Seepage E Misalignment of Walls/Slabs ❑ Damaged Gates ❑ Nonfunctional Gates ❑ Lubrication of Gates ❑ Testing of Gates Comments: } TCEQ -20361 (2107) -2- Emergency Spillway Condition: ❑ Good ❑ Fair ❑ Poor Depth: Width: Problems Noted: ❑ None ❑ Blockage ❑ Not Located ❑ Trees ❑ Burrows ❑ Back - Cutting Erosion ❑ Inaccessible ❑ Livestock Damage ❑ Concrete Cracking ❑ Concrete Spalling ❑ Reinforcement Corrosion ❑ Damaged Water -stops ❑ Open Joints ❑ Sinkholes ❑ Holes in Spillway Chute ❑ Seepage ❑ Misalignment of Walls /Slabs ❑ Damaged Gates ❑ Nonfunctional Gates ❑ Lubrication of Gates ❑ Testing of Gates Comments: N/A Other Items ❑ Major road along crest of dam ❑ Private road or driveway along crest of dam ❑ Vehicle bridge along crest of darn, ❑ Culverts built into crest of dam ❑ Pipeline immediately downstream from dam - Type of pipeline: ❑ Water supply lime in crest of dam ❑ Other: Comments: 18 -inch low flow valve not functional. Repair Items Ranked by Priority Item 1: Regrade wet area on saddle darn rigbt_abutment Item 2: Fills illwa ioints. Item 3: Cl a by Millwgy training walls. Item 4: Security Issues ❑ Vehicle Accessible ❑ Vehicle Gates ❑ Vehicle Fences and Railing ❑ Pedestrian Accessible ❑ Pedestrian Gates and Fences ❑ Obscured from Surveillance ® Locks ® Breaches in Fence ❑ Evidence of Parties ❑ Graffiti ❑ Security System Comments: Locks are present on access points, but there were breaches in the fence by the houses Downstream. Operational Procedures ❑ SOP Available Location Kept: ❑ Logbook Location of Logbook: ❑ Major Events Noted ❑ Staff Training Topics of Training: _ ❑ Manual Gate Operations ❑ Powered Gate Operations ❑ Automated Gate Operations Comments: NIA TCEQ -20361 (2/07) -3- - Communications ❑ Directory Available ❑ 24 -Hour Coverage ❑ Telephone Available at Dam ® Cell Phone Coverage— Provider: Metropolitan area – all coverage. _ Comments: i... Emergency Action Plan ® Available ® Filed with TCEQ ❑ Change in Downstream Lazard Frequency of Update: Annually Date of Last Revision: 2005 .. Date of Last Exercise: Comments: Luminant Power held an Emergtncy Emergency Action PIan AP zLming session in October 2007 To review EAP pMtocol with the staff. The trainin session was held to educate new staff members. I . Instrumentation ® Present ® Adequately Maintained ❑ Inadequately Maintained ❑ Operational ❑ Data Collected ® Data Analyzed ❑ Adequately Protected Comments: _ _ piezometers L. Early Warning System ❑ Present ❑ Adequately Maintained ❑ Inadequately Maintained ❑ Operational Frequency of Maintenance: Date of Last Exercise: Comments: NIA Reservoir Drawdown Capability Maximum Drawdown: Comments: Method of Drawdown: 42 -inch pine c.fs. 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