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North Lake PP-SY080926 II Luminant Office Memorandum To: Brett Wiggs Date: September 26, 2008 cc: From: Rick Jeanes ~ CITY MANAGER CITY OF COPPELL Subject: 2007 Phase I Dam Inspection Report for North Lake Dam In response to your request, I have enclosed with this letter of transmittal a copy of the 2007 Phase I Dam Inspection Report 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 1500 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 monitoredfor 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 15+00 on the saddle dam is presently stable and recent inspections have not revealed any signs of exposed embankment soil which would warrant the needfor immediate repair. Plant personnel will continue to monitor this area during routine inspections. . The spillway joints which have some separation should be filled with ajoint 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 elastomeric 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 Dam Inspection Report for North Lake Dam TX 00832 January 2008 Phase I Dam Inspection Prepared for Luminant Power for North Lake Dam TUE07434 ,""'". _~~ or ''''. -~ ~ ..........l:-t 'f :t? ... * ...-f~, -. .. .. .', ~.: \.' ".eA..__.-.Ae. ., ~ JANIS C. MLRPHY ~ 'I. ~_.__..~" ~"t\.~ 61882 QI..~: ,,~~..tCI ST~~~..~~': f, ~~ ........ ,,<3 - ',,' ONAl ~_-- / .---" \"~~:r v1A. 'j~~\ ~ c 'iAJ"Wq ~~} 'Iollo~ , ATR: 58280 Agreement No. S 0204353, Amendment 3 Freese and Nichols, Inc. 4055 International Plaza Suite 200 Fort Worth, TX 76109 817 n35-7300 TABLE OF CONTENTS Phase I Dam Inspection Report for North Lake Dam ~ 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 RECOMMENDATIONS..................................................................... 7 APPENDICES Appendix A References Appendix B Photographs Appendix C Dam Inspection Check List Appendix D Instrumentation Readings North Lake Dam 2007 Inspection 1 PHASE I DAM INSPECI10N 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 Lllminant Power's A TR. 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 ms!. The dam consists of two separate embankments, designated herein as the main dam 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 ms!. 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 msl) precast concrete wave wall was added in 1993 to provide additional freeboard against wave action during a Probable Maximum Flood event. Seepage control is North Lake Dam 2007 Inspection 1 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 of25 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's, 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 of510 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 surfica1 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 unknown. 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 2007 Ip.spection 2 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. r'~ 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 last year 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 vegetation present in the rock riprap. This item ~hould 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 lealrs 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 2007 Inspection 3 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 mainlenance items. 4.0 CURRENT INSPECI10N 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 Dam 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. ,.-. 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 Lmninant North Lake Dam 2007 Inspection 4 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-I 05 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 rotted and pond water. Most of these areas were located near the left end of the saddle dam. The wave wall on the upstream edge ofth~ 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. Spillway 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 2007lnspection 5 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. Expansionjoints 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 IS-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 leakage. This structure is an offset area along the spillway channel. The area is very overgrown with reeds and observation was not possible. River Pump Station Dischar~e Outlet The river pump station discharge outlet structure located on the left upstream abutment of the dam was observed. r-' 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 Lnminant 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 surfica1 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 2007 Inspection 7 07-6 The spillway joints which have some separation should be filled with ajoint sealant. This will most likely be an ongoing maintenance item. 07-7 The trees and thick vegetation adjacent to the spillway discharge channel should be cleared. 07-8 The vegetation adjacent to the spillway walls should be removed. 07-9 The security fence at the downstream property limit should be repaired. 07-10 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-I05 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 Wlder the concrete crest of the service spillway at the left end should be filled. North Lake Dam 2007 Inspection 8 APPENDIX A REFERENCES APPENDIX A REFERENCES 1. Texas Department of Water Resources, Phase I Dam Inspection/or North LaJce Dam, Dallas County, Texas, October 1978. 2. Freese and Nichols, Dam Saftty Inspection Report for North LaJce Dam, TX00832, Dallas, Texas, March 2004. 3. Quality Consultants, Phase I Dam Inspection North LaJce Dam, Dallas, Texas, June 13, 2007. APPENDIX B PHOTOGRAPHS CJI f\) o o ~ N o o o i ~~ ~ 3 :!:!. o :I ~ OlD -- 0" . ... o ." c; c ~ ,., 1111 ....... .... IDaho.. ____1lID root ...... T_ 711_ ""- - (117) 73/l-J300 r.. - (111) '73lI-7..' LUMINANT POWER NORTH LAKE DAM CML 2007 PHASE I INSPECTION PHOTO LOCATIONS ~ t~ I i zc} ~lJ ::0 ~ Z (i) rJ) -t )> ::! o z ~ Photo No.1: Looking at the crest orthe saddle dam toward the right abutment. 1-- - -------- I "t;;J:/J/ Photo No.2: Looking along the crest of the saddle dam from near the right end. North Lake Dam 2007 Inspection November 14,2007 - Looking along the crest of the saddle dam toward the left abutment. Photo No.4: Ponded water in the road on the crest of the saddle dam. North Lake Dam November 14,20.0.7 20.0.7 Inspection Photo No.5: Looking along the wave wall at the upstream edge of the crest of the saddle dam. >~ " \ r> cor cf ", ,. '~, jlJ. il.: Photo No.6: \ Looking at the wave wall on the saddle dam. the wall. North Lake Dam 2007 Inspection November 14, 2007 .- . ~ Photo No.7: Looking at the upstream slope of the saddle dam from the right abutment. R Photo No.8: <c;I l.i... :~..I <~r~ Looking at the upstream slope of the saddle dam. North Lake Dam 2007 Inspection November 14, 2007 '" Photo No.9: Looking along the waterline of the saddle dam. Note irregular water line. , A Photo No. 10: Overview of the downstream slope of the saddle clam. North Lake Dam 2007 Inspection November 14, 2007 1<<".. ",. t . ';)i....~.'..'..~.. '.<.. i ;'!\'.~ ,.-..;~ n.~ ~1~, Photo No. 11: Overview of the right abutment of the saddle dam. Area is roughly graded and has numerous arcas of seepage. One of several areas of seepage at the right abutment of the saddle dam. North Lake Dam 2007 Inspection November 14, 2007 Photo No. 13: Animal burrow located on the saddle dam near the toe. Photo No. 14: North Lake Dam 2007 Inspection November 14, 2007 -,",' Photo No. 15: Looking across the crest of the service spillway. ,;.. Photo No. 16: Approach to the service spillway. North Lake Dam 2007 Inspection November 14, 2007 r ..,. .... "-- :'f~"1t. 'i,: '",~<. ,~ "'~ >- ..r~ . ~- " ~.. .1-.'. '."-:; Photo No. 17: Approach to the service spillway. Rock protection appears thin in places. Photo No. 18: Area of ponded water in the approach to the service spillway. North Lake Dam November 14,2007 Photo No. 19: Photo No. 20: Entrance to the side channel spillway. North Lake Dam November 14,2007 --': - -- 1;' ,. .t .,,, ,. ;'~ ~' , , ..~~~ , <'- '~1:. 1'. 't, >r.;, .-'t.. ,g.::::, ~~' :t;~~ ;< -~(",;;! Photo No. 21: Pipe which carries water under the road on the service spillway crest. Photo No. 22: Hole located on the downstream side under the road on the service spillway at the left end. North Lake Dam November 14,2007 Photo No. 23: Looking at the junction of the service spillway channel with natural ground between the saddle dam and the spillway. Photo No. 24: Open joint on the slope paving downstream of the crest of the spillway. North 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. 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. North Lake Dam November 14,2007 Photo No. 29: Low flow 18-inch outlet pipe which has been decommissioned. Note seepage from adjacent wall drain. Photo No. 30: Repaired section ofthe spillway wall. Note continued movement at the joint. North Lake Dam November 14,2007 . J..\, ~ l,.r,. ~'; it .. , , -di ~ ,; 7~ .. *. r _ I'F ~fIIt< ~ /(14 '"...'!. j ..", -'''' ,. Photo No. 31: Separation of the spillway wall from the channel floor. -;OJ J " -<., '-";J.. .. ~- i,. I Photo No. 32: Exposed rebar at the bottom of the wall. North Lake Dam November 14,2007 Photo No. 33: End sill of the basin and channel downstream. Left side is about a 0.5 inch lower than right side. -,c ~.~~~ ",.:' '" ,r,.: J. '. ' " I ~~- .'$-~. - .;:~ ~~ ;{~ l").f,"'" I .t.,.~,~.,..;.ms; '<Y'.J} '. ,.,,~..'t: }~',,,""~,.r<it'W~>l" j - Photo No. 34: North Lake Dam 2007 Inspection November 14, 2007 Photo No. 35: Looking along the crest of the main dam from near the middle. Wave wall is also misaligned on the main dam. ~.... -.-' Photo No. 36: Hole under the asphalt road on the crest of the main dam. North L~lkc Dam 2007 Inspcction Novcmber 14, 2007 ....... Photo No. 37: --- Photo No. 38: Offset in wave wall on main dam. .-.. North Lakc Dam 2007 Inspection Novcmber 14, 2007 -- ,-' Photo No. 39: Overview of the downstream slope of the main dam. Photo No. 40: Repaired slope failure on the main dam from January 2007. -^- North Lake Dam 2007 Inspection November 14,2007 - Photo No. 41: Irrigation system repairs on the main dam. Photo No. 42: Toe drain vault at toe of the main dam. North lake Dam 2007 Inspection November 14, 2007 /'- - ..... 1 1f,"'':;~ . , ..... Photo No. 43: Inside the manhole shown in photo No. 42. 'J#} '--1 ~ :\ " Photo No. 44: Recently completed slope repair area on main dam from a June 2007 slide. .-"- North Lake Dam 2007 Inspection November 14, 2007 i-:, Jii.'<" ..r " ~ P ,] i * ~r;' :. f;!... ~ ;y,~ '"^- Photo No. 45: Looking at the left abutment of the main dam. -' Photo No. 46: I.ast toe drain manhole where water is pumped from the system. North Lake Dam 2007 Inspection November 14, 2007 r" '" Photo No. 47: .-'- r-- Photo No. 48: Looking at the pipe insidc thc servicc outlet structurc. Note deterioration of the stem pipe for the valve operator. North Lake Dam 2007 Inspection November 14,2007 .$' .... .n '" ." ., :: ~~~y *_il< .;.~... 1- Photo No. 49: Houses located downstream of the darn. "....... Photo No. 50: One of the several holes in the fence on the downstream property line. North Lake Dam 2007 Inspection November 14, 2007 .' " { APPENDIX C DAM INSPECI'IONCBECKLIST Texas Commission on Environmental Quality Dam Inspection Form Inspection Results--Dam Conditions Dam Name: North Lake Dam Inventory No: TX 00832 Name ofInspector/s: Janis Mwphv. P.E.. Freese and Nichols. Inc. Name ofContact/s: Milton Vrla.. P.E.. Tem PeI'l"Y. Greg Stuckev. Luminant Power Date of Inspection: 11/14/07 Start Time: 8:00 am End Time: 12:30 pm Weather: cooL dry Crest level (at center) above water: 5 feet Service spillway level lEI Above or D Below water: 510 feet msl Emergency spillway level above water: 0' Ground Moisture Condition: DDry DDamp D Wet 0 Snow _ D Other: ;' Crest of Embankment General Condition: lEI Good 0 Fair 0 Poor Width: 12 feet Height: 65 feet main dam: 25 feet saddle dam Length: 4.000 feet Problems Noted: D None lEI Rutting D Erosion 0 Poor Drainage o Trees 0 Depressions 0 Bulges 0 Livestock Damage 0 Cracks o Misalignment of Crest 0 Misalignment of Utility Poles 0 Misalignment ofFences or Rails OSinkhole o Burrows 0 Breached 0 Other: Comments: Upstream Embankment General Condition: lEI Good D Fair 0 Poor Slope: 3:1 main and saddle Problems Noted: 0 None DRip-Rap 0 Erosion 0 Too Steep 0 Burrows D Trees 0 Cattails o Depressions 0 Bulges OLivestock Damage 0 Slides D Concrete Decay D Cracks D Sinkhole o Benching 0 Misalignment of Rip-rap 0 Open Joints in Concrete Comments: Minor vegetation in rock ripraD. Downstream Embankment General Condition: lEI Good D Fair 0 Poor Slope: 3: 1 main: 3.8 saddle Problems Noted: 0 None D Sloughing lEI Erosion 0 Too Steep IZI Burrows D Trees 0 Cattails D Depressions 0 Bulges 0 Livestock Damage 0 Slides 0 Concrete Decay 0 Cracks 0 Sinkhole o Other: Comments: TCEQ-20361 (2/07) - 1 - Seepage on Downstream Slope Amount: 0 Major 0 Moderate C8J Minor 0 None Found Problems Noted: 0 None 0 Saturation Starts at % up Embankment o Presence of Sediment in Flow 0 Cattails at Toe of Dam 0 Surface Water at Toe of Dam o Seepage Associated with Sloughing 0 Continuous Flow 0 Sporadic Flow Comments: Wet at the right abutment of the saddle dam. Downstream Hazard Conditions 0 Narrow Canyon 0 Wide Canyon 0 Lightly Sloping Prairie o Pasture land 0 Large Trees and Forest 0 Brushy and Scrubby Forest 0 No Homes o Lightly Populated 0 Moderately Populated C8J Densely Populated 0 Industrial 0 Businesses Estimated number of homes: Comments: Service Inlet Structure General Condition: OGood C8J Fair 0 Poor Problems Noted: 0 None 0 Blockage 0 Not Located 0 Steel Corrosion 0 Concrete Spalling o Concrete Cracking 0 Reinforcement Corrosion 0 Missing Parts 0 Timber Decay o Leakage Below Water Level C8J Inoperable Valve 0 Other: Comments: River pump station discharge outlet is a 42-inch pipe to pump into the reservoir. Two 12-inch valves can release water back into the Elm Fork ofthe Trinity River. Valves appear corroded. Service Outlet Structure General Condition: 0 Good 0 Fair 0 Poor Problems Noted: C8J None 0 Blockage 0 Not Located 0 Corrosion of Conduit o Presence of Sediment in Flow 0 Inaccessible 0 Concrete Cracking 0 Concrete Spalling o Reinforcement Corrosion 0 Misalignment of Walls/Slabs 0 Open Joints Comments: Low flow system is an 18-inch pipe. Structure is capped on the upstream and downstream end with blind flanges. It has been decommissioned. Service Spillway Condition: C8J Good 0 Fair 0 Poor Depth: 0.5 feet Width: 200 feet Problems Noted: 0 None 0 Blockage 0 Not Located 0 Trees 0 Burrows 0 Back-Cutting Erosion o Inaccessible 0 Livestock Damage C8JConcrete Cracking C8JConcrete Spalling OReinforcement Corrosion 0 Damaged Water-stops 0 Open Joints 0 Sinkholes o Holes in Spillway Chute 0 Seepage C8J Misalignment of Walls/Slabs 0 Damaged Gates o Nonfunctional Gates 0 Lubrication of Gates 0 Testing of Gates Comments: TCEQ-20361 (2/07) - 2 - Emergency Spillway Condition: 0 Good 0 Fair 0 Poor Depth: Width: Problems Noted: 0 None 0 Blockage 0 Not Located 0 Trees 0 Burrows 0 Back-Cutting Erosion o Inaccessible 0 Livestock Damage 0 Concrete Cracking 0 Concrete Spalling o Reinforcement Corrosion 0 Damaged Water-stops 0 Open Joints 0 Sinkholes o Holes in Spillway Chute 0 Seepage 0 Misalignment of Walls/Slabs 0 Damaged Gates o Nonfunctional Gates 0 Lubrication of Gates 0 Testing of Gates Comments: N/A Other Items 0 Major road along crest of dam 0 Private road or driveway along crest of dam o Vehicle bridge along crest of dam 0 Culverts built into crest of dam o Pipeline immediately downstream from dam - Type of pipeline: o Water supply line in crest of dam 0 Other: Comments: IS-inch low flow valve not functional. Repair Items Ranked by Priority Item I: Regrade wet area on saddle dam right abutment Item 2: Fill sDiIlwav ioints. Item 3: Clear area by spillwav trainine: walls. Item 4: Security Issues 0 Vehicle Accessible 0 Vehicle Gates 0 Vehicle Fences and Railing o Pedestrian Accessible 0 Pedestrian Gates and Fences 0 Obscured from Surveillance ~ Locks ~ Breaches in Fence 0 Evidence of Parties 0 Graffiti 0 Security System Comments: Locks are Dresent on access points. but there were breaches in the fence by the houses Downstream. Operational Procedures 0 SOP Available Location Kept: o Logbook Location of Logbook: o Major Events Noted 0 Staff Training Topics of Training: o Manual Gate Operations 0 Powered Gate Operations 0 Automated Gate Operations Comments: N/A TCEQ-20361 (2/07) - 3 - Communications 0 Directory Available 0 24-Hour Coverage 0 Telephone Available at Dam ~ Cell Phone Coverage-Provider: Metropolitan area - all covera2e. Comments: Emergency Action Plan Frequency of Update: Date of Last Exercise: Comments: Luminant Power held an Emergencv Action Plan mAP) training session in October 2007 To review EAP protocol with the staff. The training session was held to educate new staff members. ~ A vailable ~ Filed with TCEQ 0 Change in Downstream Hazard Annually Date of Last Revision: 2005 Instrumentation ~ Present ~ Adequately Maintained 0 Inadequately Maintained 0 Operational o Data Collected ~ Data Analyzed 0 Adequately Protected Comments: piezometers Early Warning System 0 Present 0 Adequately Maintained 0 Inadequately Maintained 0 Operational Frequency of Maintenance: Date of Last Exercise: Comments: N/ A Reservoir Drawdown Capability Method of Draw down: 42-inch pipe Maximum Drawdown: c.f.s. Frequency of Testing: Comments: Backup Power 0 Present 0 Adequately Maintained 0 Inadequately Maintained 0 Operational Frequency of Maintenance: Date of Last Exercise: Comments: N/ A TCEQ-20361 (2/07) -4- APPENDIXD . 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