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1 This is a digital dcument frm the cllectins f the Wyming Water Resurces Data System (WRDS) Library. Fr additinal infrmatin abut this dcument and the dcument cnversin prcess, please cntact WRDS at wrds@uwy.edu and include the phrase Digital Dcuments in yur subject heading. T view ther dcuments please visit the WRDS Library nline at: Mailing Address: Water Resurces Data System University f Wyming, Dept E University Avenue Laramie, WY Physical Address: Wyming Hall, Rm 249 University f Wyming Laramie, WY Phne: (307) Fax: (307) Funding fr WRDS and the creatin f this electrnic dcument was prvided by the Wyming Water Develpment Cmmissin (

2 (Willwd Dam) cpy 2 WILLWOOD DAM REHABILITATION PROJECT FINAL REPORT SUBCONSULTANTS BANNER ASSOCIATES, INC. CHEN-NORTHERN, INC. - s (])... ~ -... r:/)...,s ~, 8 :::::::::::::... ~,'r,.l., CI:l 0 ~ ==== LI) ; , = 0 ~;J M \0 iiiiiiiiiiiiiii~~_""'~p. ~...!:B~OX~1 g~oo:...-~z~/p~8~24:.;.14:...::..:.ph~o~n E~30~7 -~58~7-:.:49~11 E--- S5 ~ \0 ~ I~ ~ c~ ~ :RING ASSOCIATES - CODY, WYOMING CW).~~~~M 9 ~] ~~ 'JNSULTING ENGINEERS & SURVEYORS ~ - ~~ -~..J

3 WILLWOOD DAM REHABILITATION PROJECT FINAL REPORT PREPARED FOR: WYOMING WATER DEVELOPMENT COMMISSION MEMBERS: Beryl Z. Churchill William L. Glanz Myrn Gdsn Paul Hickey Wayne Mre Leslie Petersen Merl Rissler Kathleen Sun Gerge Zebre ADMINISTRATOR: Michael K. Purcell CONSULTANT: SUBCONSULTANTS: ENGINEERING ASSOCIATES P.O. BOX 1900 CODY, WYOMING BANNER ASSOCIATES, INC. CHEN-NORTHERN, INC. DATE: NOV2MBER 1, 1989

4 TABLE OF CONTENTS PAGE PHASE I REHABILITATION PLAN 1.0 INTRODUCTION INSPECTIONS RIVER CONTROL DURING CONSTRUCTION REHABILITATION PLAN PRELIMINARY COST ESTIMATES - RIVER CONTROL PRELIMINARY COST ESTIMATES - REHABILITATION PLAN WILLWOOD IRRIGATION DISTRICT PRIORITIES 11 PHASE II FINAL REPORT INTRODUCTION CONCEPTUAL DESIGN COST ESTIMATES ECONOMIC ANALYSIS PERMITS, EASEMENTS, AND AGREEMENTS 30 FIGURE 1 - FIGURE 2 - FIGURE 3 - FIGURE 4 - WILLWOOD DIVERSION DAM SPILLWAY APRON DOWNSTREAM TURBIDITY CONTROL FACILITIES CROSS SECTION OF WILLWOOD DAM FIGURE 5 - TYPICAL SECTION - RECONSTRUCTED SPILLWAY APRON FIGURE 6 - TYPICAL SECTION - RECONSTRUCTED RIGHT WINGWALL FIGURE 7 - RIGHT ABUTMENT - CONTACT APPENDIX OPERATING CRITERIA WILLWOOD DAM WILLWOOD DAM TURBIDITY AND FLOW DATA CHEN-NORTHERN, INC., LETTER REPORT WILLWOOD IRRIGATION DISTRICT, LETTER

5 PHASE I REHABILITATION PLAN

6 1.0 INTRODUCTION 1.1 PROJECT DESCRIPTION The Willwd Dam Rehabilitatin Prject invlves the identificatin f necessary repairs and imprvements t the Willwd Irrigatin District Diversin Dam and the cnceptual design and preparatin f cst estimates fr the repairs and imprvements. The Phase I Rehabilitatin Plan cnsists f the identificatin f needed repairs and the preparatin f preliminary estimates f design and cnstructin csts. 1.2 WILLWOOD DAM DESCRIPTION The Willwd Diversin Dam, shwn in Figure 1, cnsists f a cncrete gravity gee weir with embankment wings, lcated n the Shshne River 8 miles dwnstream frm Crbett Dam and 13 miles nrtheast f Cdy, Wyming. The dam has a structural height f 70 feet, a hydraulic height f 41 feet, a weir crest length f 271 feet, and a ttal crest length f 476 feet. The weir c~=st is at elevatin The canal utlet wrks cnsists f a rectangular cnduit thrugh the right end f the dam and embankment wing t the Willwd Canal cntrlled by tw, 5.6 x 7.0 ft diversin gates. The sill elevatin f the diversin gates is Three sluiceways with a sill elevatin f are cntrlled by 3.6 x 5.5 ft cast irn gates lcated n the upstream face f the dam. An utlet was prvided thrugh the dam near the right abutment fr future cnstructin f a pwerplant. This utlet has an upstream sill elevatin f and a dwnstream invert elevatin f The dam was designed by and built under the supervisin f the Bureau f Reclamatin. Cnstructin was cmpleted in The dam diverts water frm the Shshne River int the Willwd Canal and is used fr irrigatin. The canal capacity is apprximately 320 cfs. 1.3 WILLWOOD DAM OPERATIONS Since January, 1982, peratins f Willwd Dam have been subject t an agreement executed by Bureau f Reclamatin, Wyming Department f Envirnmental Quality, and the Willwd Irrigatin District. A cpy f this agreement is included as Appendix A. A significant cntrl impsed by the perating agreement is a limitatin n the allwable turbidity increase f 10 NTU in the Shshne River frm the upstream t the dwnstream side f the dam. The agreement als stipulated that recrds be kept f the upstream turbidity, dwnstream turbidity, upstream water surface elevatin, and gate penings during the time sluice gates are in peratin. Infrmatin derived frm these recrds, which cver the nn-irrigatin seasn frm December 16, 1982 thrugh April 10, 1989 is included as Appendix B. Althugh nt stipulated in the agreement, the Willwd Irrigatin District perates the sluice gates nly during the nn-irrigatin seasn. 1

7 1.4 SHOSHONE PROJECT OPERATIONS The Willwd Irrigatin District is a divisin f the Shshne Prject and is impacted by Shshne Prject peratins. The Bureau f Reclamatin prepares annual perating plans fr the Shshne prject. The nn-irrigatin seasn releases frm Buffal Bill Reservir will definitely impact cnstructin dne at Willwd Dam as any cnstructin will have t be cmpleted during the nn-irrigatin seasn. Criteria fr nn-irrigatin seasn releases, frm the 1987 annual perating plan, is summarized belw: Nrmal Years with Adequate Water Supply Very Dry Year 2.0 INSPECTIONS 2.1 SPILLWAY APRON Release frm Buffal Bill Dam 100 cfs 50 cfs Flw In Shshne River belw Heart Mtn. Pwer Plant 350 cfs 100 cfs In 1982 the Bureau f Reclamatin determined the elevatin f the cncrete alng a series f crss-sectin lines spaced at ten feet intervals starting frm the dwnstream end f the aprn and prgressing twards the face f the dam. The aprn was nt dewatered s a visual inspectin was nt made. The results f the Bureau's survey indicated a significant lss f cncrete dwnstream f the nrth sluice gate. There were als areas where the cncrete elevatins culd nt be determined because f silt depsits n the aprn. In August, 1988, Engineering Assciates investigated the pssibility f dewatering the dwnstream aprn with temprary pumping t enable a visual inspectin f the cncrete and an inspectin f the dwnstream side f the sluice gates. After an analysis f the funding available and an estimate f the water flw in the river the investigatin was abandned. The pumping capacity available within the funding limitatins appeared t be inadequate t handle the flws which might ccur in the River. On September 27, 1988, Engineering Assciates cnducted a survey t determine the elevatin f the tp f the cncrete n the spillway aprn alng apprximately the same sectins used by the Bureau f Reclamatin in their 1982 wrk. The water surface elevatin in the dwnstream pcl was The design elevatin f the tp f cncrete varies between 4454 and A rubber raft was used and elevatin shts n tp f the cncrete were taken every ten feet alng crss-sectin lines which were spaced ten feet apart. 2

8 Due t the fact that the sluice gates had been clsed since the start f the irrigatin seasn in April, and water had been flwing ver the crest f the dam, the aprn was free f silt. This survey cnfirmed the severe cncrete damage dwnstream frm the nrth sluice gate and indicated pssible lss f cncrete elsewhere. At ne lcatin, slid material culd nt be fund by prbing with the rd. The rd was able t penetrate the material encuntered dwn t an elevatin f /-, which is apprximately 5 feet belw the calculated tp f cncrete elevatin at that pint. This culd indicate that the cncrete has been erded thrugh, expsing the underlying strata. Results f the survey are shwn graphically in Figure CANAL GATES AND CONCRETE On January 26, 1989, representatives f Engineering Assciates, Banner Assciates, Inc., and Chen-Nrthern, alng with Wilber Higgins, Willwd Irrigatin District Manager inspected the dwnstream side f the canal gates. The water surface elevatin f the upstream pl was which prevented an examinatin f the upstream side f the gates. Seepage was ccurring arund bth gates and sme lss f cncrete behind the gate frames was bserved. Chen-Nrthern als cnducted a visual inspectin f the tunnel behind the gates, the dam, and the retaining walls. Their reprt is included as Appendix c. 3.0 RIVER CONTROL DURING CONSTR~CTION 3.1 GENERAL A majr ltem f cst during cnstructin will be cntrl f the River. During nrmal peratins there are 3 ways t pass Shshne River flws by Willwd Darn. 1. Flw ver the tp f the Darn. 2. Diversin int Willwd Canal. 3. Discharge thrugh the Sluice Gates. Nne f the prpsed repairs r replacements can be accmplished when water is flwing ver the tp f the dam. Diversin f water thrugh Willwd Canal is nt cnsidered a viable ptin because the first wasteway which wuld allw returning the flw t the Shshne River is lcated apprximately 4 miles dwnstream frm the head gate. If this ptin is used, there wuld be n significant flw in the Shshne River frm Willwd Darn dwnstream t the wasteway. This ptin wuld nt permit wrk n the canal gates r the sluice gates. The sluice gates each have a maximum capacity in excess f 500 cubic feet per secnd and a capacity f apprximately 170 cubic feet per secnd with upstream water surface elevatin at Experience has shwn that peratin f the sluice gates at near maximum capacity r with the upstream pl at lw elevatins generally results in turbidity increases in excess f 10 NTU. 3

9 During the nn-irrigatin seasn, all r part f the Shshne River flw culd be diverted int the Garland Canal at Crbett Dam and returned t the river belw Willwd Dam at Eaglenest Creek apprximately 1.8 miles dwnstream frm Willwd Dam. This wuld require cnsent f the Shshne-Heart Muntain Irrigatin District. The Wyming Game and Fish Department wuld als have t make a determinatin f the minimum flw they wuld require between Crbett Dam and Willwd Dam. 3.2 TURBIDITY CONTROL Fr estimating purpses the assumptin has been made that the fllwing facilities wuld be required fr turbidity cntrl: 1. Cnstructin f a dike alng the right river bank frm a pint immediately dwnstream f the dam and cntinuing dwnstream fr apprximately 3,000 feet. 2. Cnstructin f a temprary diversin dam dwnstream frm the wrk area t divert the river flws int the area behind the dike. The water wuld be diverted ut f the river channel and flw thrugh the area behind the dike int a pnd at the dwnstream end and then wuld be discharged back t the river. Cnstructin f the temprary diversin dam acrss the river wuld cause turbidity increases but they shuld be f shrt duratin. 3.3 FLOW IN SHOSHONE RIVER The flw rates will have a direct impact upn the cst f river cntrl. Pumping may be required n a temprary basis during the installatin f cfferdams, with pumping capacity and energy csts increasing as flws increase. Because f site limitatins, the maximum temprary pumping capacity which culd be installed is in the range f 50 t 100 cfs. The size f detentin pnds fr turbidity cntrl will increase as the flw increases. 3.4 SPILLWAY APRON REPAIR Repair f the identified damage area dwnstream frm the nrth sluice gate culd be accmplished by installing a cffer dam n the aprn between the nrth sluice gate and the center sluice gate and extending the cfferdam t the river bank dwnstream f the aprn. The area within the cfferdam wuld be dewatered by pumping. The river flw culd be passed thrugh the center sluice gate. Hwever, at higher river flws the velcities will very likely increase the turbidities abve the allwable limits, necessitating turbidity cntrl measures discussed in Sectin

10 3.5 CANAL GATE REPLACEMENT Wrk n the canal gates requires lwering the water surface elevatin n the upstream side f the dam belw elevatin The discharge tables fr the sluice gates indicate that at elevatin 4485 each sluice gate has a capacity in excess f 450 cubic feet per secnd when wide pen. Again, perating the sluice gates in this manner wuld very likely cause the turbidity t exceed the allwable limits, necessitating the turbidity cntrl measures discussed in Sectin SLUICE GATE REPLACEMENT Wrk n the sluice gates requires cmplete dewatering f the upstream pl as the sluice gate sills are at elevatin 4454 near the bttm f the dam. The estimate was based upn the fllwing plan: 1. Install turbidity cntrl facilities described in Sectin Install a temprary pipe frm the dwnstream end f the pwer utlet past the end f the spillway aprn. 3. Install a sheet pile cfferdam upstream f the dam. 4. Install temprary pumping facilities t pump the river flws frm the upstream side f the cfferdam t the dwnstream side f Willwd Dam. 5. Dewater the pl between the cfferdam and Willwd Dam. 6. Install a temprary pipe thrugh the cfferdam and int the upstream end f the pwer utlet. 7. Divert the river thrugh the temprary pipe. This plan fr river cntrl wuld allw wrk n the spillway aprn and the canal utlet wrks as well as n the sluice gates. 4.0 REHABILITATION PLAN 4.1 SPILLWAY APRON The spillway aprn was under water n the date f ur inspectin. Fr details f the riginal spillway aprn, see Figure 2. Frm the survey cnducted in September, 1989, it appears, at a minimum, the aprn dwnstream frm dam Blck 9 and the suth 23 feet f Blck 10, shuld be remved and replaced. The right wing wall shuld als be remved and replaced. During the final design, if pssible, the spillway aprn shuld be dewatered and inspected. If this is nt pssible, then during the cnstructin f the prject the entire aprn shuld be dewatered and inspected. The Bid Dcuments shuld include sme methd whereby the Owner can make any repair required. 5

11 4.2 CANAL OUTLET WORKS The canal utlet-wrks cntrls flws up t 320 cfs with tw 4.6 x 7.0 ft. cast irn slide gates with a sill elevatin f ft. The headwrks fr the canal utlet-wrks have been in peratin since The gates are mtr perated with a manual backup. The headwrks are ld, but appear t be in gd perating cnditin. These gates were inspected n January 26, Bth gates were shut but were leaking water at that time. Attempts have been made by the Owner t stp this leakage in the past, but d nt appear t have been successful. The rehabilitatin plan fr the canal utlet-wrks shuld cnsider replacement f bth f the existing canal gates with new gates f equal size and shape. This wuld include new frame, gates, seats, peratrs and headwrks. The life expectancy f cast irn gates is n the rder f 50 years. These gates are lder than 50 years. 4.3 SLUICE GATES The three sluice gates are 3.6 x 4.5 ft cast irn slide gates with a sill elevatin f ft. The right sluice gate is autmated s that it will maintain a designated upstream pl elevatin. The rehabilitatin plan fr the Willwd Dam sluice gates at a minimum shuld cnsider the fllwing items. The middle and nrth sluice gates shuld be replaced with new gates f equal size and shape. This wuld include new frames, gates, seats, peratr and headwrks. The life expectancy f cast irn gates is in the rder f 50 years. These gates are lder than 50 years. These gates were nt inspected during ur field investigatin due t the fact that bth sides f the cnduit were under the water surface. The suth sluice gate has nt been perated due t the fact that the gate stern is bent and has nt been straightened r replaced. If this gate is t be abandned the Owner shuld evaluate the effect f its lss in sluicing peratins. The suggested rehabilitatin plan fr the sluice gates requires that the upstream face f the dam be expsed during cnstructin f this prject. 4.4 RIGHT ABUTMENT CONTACT The rehabilitatin plan t crrect this situatin cnsists f the fllwing: 1. Drill anchr blts back int the vertical face. 2. Cnstruct a 20 ft wide reinfrced cncrete wall frm the tp f the dwnstream wing wall t the tp f the radway surface and anchr the new wall int the existing wing wall and int the vertical cncrete face f the nrth pier supprting the radway. 3. Prvide weep hles at apprpriate intervals in the new wall, backfill the space behind the wall with clean gravel, and place a cncrete cap n tp. 6

12 4.5 EROSION AT RIGHT WING WALL The prpsed rehabilitatin plan cnsists f the fllwing: 1. Backfill the erded area fr a length f apprximately 40 feet dwnstream frm the end f the wing wall t a surface slpe f 1-1/2 t Place a layer f filter fabric n the face f the slpe. 3. Cver the filter fabric with wire enclsed riprap anchred t the slpe with suitable stakes. 4.6 ABUTMENT GROUTING The rehabilitatin plan estimate fr abutment gruting was based n the fllwing assumptins: 1. A single rw f grut hles n 5 ft centers wuld be drilled in each abutment f the dam. 2. The hles wuld be drilled t a depth f 100 feet. 3. The bttm 75 feet f the hles wuld be gruted. 4. The vid space in the frmatin t be gruted wuld be than 5%. less Due t the uncertainties cnnected with any gruting prgram, the actual cst f gruting culd vary significantly frm the estimate. 4.7 SEEPAGE THROUGH DAM FACE Chen-Nrthern in their reprt identified an area n the dwnstream face f Blck 1 which was seeping water. There is als a hrizntal crack that extends almst the entire width f Blck 10 which als seeps water. The rehabilitatin plan fr this si tuatin wuld cnsist f drilling int r thrugh the cracks and injecting an epxy grut. 4.8 MISCELLANEOUS CONCRETE REPAIR In several places n the dam and wing walls the surface f the cncrete is beginning t deterirate. In additin there ma~ ~e areas f cncrete deteriratin belw the water line in the dwnstream pl and n the upstream face f the dam. Fr purpses f this estimate a unit price per square ft f miscellaneus cncrete repair was develped. 4.9 CANAL TUNNEL The canal tunnel was inspected January 26, The tunnel was in gd cnditin with n visible signs f significant cracking r settlement. There was a layer f silts n the tunnel flr, hwever, n flr cracks culd be detected. 7

13 There is n evidence f significant vlumes f water traveling either int r ut f the tunnel walls r weep hles. The tunnel is in exceptinal cnditin fr the date f cnstructin (1924). Therefre, we d nt believe rehabilitatin wrk is required at this time fr the canal tunnel. 5.0 PRELIMINARY COST ESTIMATES - RIVER CONTROL A general cntractr with extensive experience in river cntrl prvided assistance in develping the river cntrl cst estimates. The estimated csts are in prjected 1990 dllars. 5.1 TURBIDITY CONTROL DOWNSTREAM Install and remve temprary diversin dam Cnstruct and bliterate sedimentatin pnd Incidental wrk SUB TOTAL Engineering Cntingency TOTAL $ 12,000 $ 30,000 $ 8,000 $ 50,000 $ 5,000 $ 7,500 $ 62, SHEET PILE COFFERDAM UPSTREAM, TEMPORARY PIPE THROUGH POWER OUTLET, SILT REMOVAL UPSTREAM SUB TOTAL Engineering Cntingency TOTAL $320,000 $ 32,000 $ 48,000 $400, TEMPORARY PUMPING FACILITIES 50 CFS CAPACITY Mbilizatin/Dembilizatin $ 50, days $ 20, COFFERDAM INSTALLATION FOR SPILLWAY APRON REPAIR 6.0 PRELIMINARY COST ESTIMATES - REHABILITATION WORK SUB TOTAL $ 70,000 Engineering $ 7,000 Cntingency $ 10,500 TOTAL $ 87,500 SUB TOTAL $ 70,000 Engineering $ 7,000 Cntingency $ 10,500 TOTAL $ 87,500 Many f the rehabilitatin items require river cntrl. If several items are cmbined in ne prject, a given river cntrl item wuld nly have t be dne ne time. Estimated csts are in prjected 1990 dllars. 8

14 6.1 SPILLWAY APRON Remve existing cncrete - LS Replace fundatin material, 450 $50.00 Replace cncrete, 460 $ Remve right wing wall - LS Replace right wing wall, 65 $ SUB TOTAL Engineering Cntingency TOTAL $ 10, , ,500 $ 10, , , ,000 $ 36,625 $300,000 Requires River Cntrl Items 5.1 and CANAL OUTLET WORKS Remve existing gates and frames, $10,000 Install new gates, frames and peratrs, $50,000 SUB TOTAL Engineering Cntingency TOTAL 5 20,000 $100,000 $120,000 $ 12,000 $ 18,000 $150,000 Requires River Cntrl Item SLUICE GATES Remve existing gates and frames, $8,000 Install 2 new gates, frames, and peratrs and grut suth cnduit SUB TOTAL Engineering Cntingency TOTAL $ 24,000 $ 81,000 $105,000 $ 10,500 $ 16,500 $132,000 Requires River Cntrl Items 5.1, 5.2, and RIGHT ABUTMENT CONTACT Cnstruct cncrete wall, 60 $ Install anchr blts, 1000 $15.00 Gravel backfill, 400 $ EROSION AT RIGHT WING WALL Place and shape backfill, 200 $5.00 Wire enclsed riprap and filter fabric, Requires River Cntrl Item 5.1 SUB TOTAL Engineering Cntingency TOTAL SUB TOTAL Engineering Cntingency TOTAL $ 30, ,000 $ 5,000 $ 50,000 $ 5,000 S 7,500 S 62,500 S 1,000 S 8,000 S 9,000 $ 900 S 1,300 $ 11,200 9

15 6.6 ABUTMENT GROUTING Mbilizatin - LS 40 grut $1,000 Grut 6.7 CRACKS ON DOWNSTREAM FACE OF DAM Mbilizatin - LS 20 grut $ Grut 6.8 MISCELLANEOUS CONCRETE REPAIR SUB TOTAL Engineering Cntingency TOTAL SUB TOTAL Engineering Cntingency TOTAL $ 4,000 $ 40,000 $ 56,000 $100,000 $ 10,000 $ 15, ,000 $ 4,000 $ 6, ,000 $ 12,000 $ 1,200 $ 1,800 $ 15,000 Remve cncrete 4" deep, per sq. ft Patching material, per sq. ft Sub ttal $50.00 Assume 400 Sq. $50.00 Engineering Cntingency TOTAL $ 20,000 $ 2,000 S 3,000 $ 25,000 Repairs in areas such as the bttm f the wing walls r upstream face f the dam wuld require ne r mre f the river cntrl items. 6.9 TOTAL PROJECT COST Obviusly, the ttal prject cst will vary depending upn which items are selected fr replacement r repair. If all the items identified in this reprt are cmpleted the preliminary cst estimate is shwn belw: River cntrl items 5.1, 5.2, 5.3, & Spillway Aprn 6.2 Canal Outlet Wrks 6.3 Sluice Gates 6.4 Right Abutment Cntact 6.5 Ersin At Right Wing Wall 6.6 Abutment Gruting 6.7 Crack On Dwnstream Face f Dam 6.8 Miscellaneus Cncrete Repair TOTAL $ 637,500 S 300,000 S 150,000 $ 132,000 S 62,500 S 11,200 S 125,000 $ 15,000 $ 25,000 $1,458,200 10

16 7.0 WILLWOOD IRRIGATION DISTRICT PRIORITIES After reviewing the Draft Rehabilitatin Plan, the Willwd Irrigatin District determined their pririties fr the rehabilitatin items. Their pririty list was transmitted t the Water Develpment Cmmissin by letter dated August 24, 1989, which is included as Appendix 4. Our cmments n each f the items are cntained in the fllwing sectins and are based n the fllwing cnsideratins: 1. Willwd Dam was cnstructed in 1924 and has been in peratin since that time, a perid f 65 years. Therefre, we tend t believe that replacement f equipment such as canal gates and sluice gates shuld be cnsidered rather than attempting repairs t crrect existing deficiencies. Obviusly the remaining useful life f these facilities is unknwn. Hwever, replacement with new facilities shuld result in a usable facility fr a lnger perid f time than if the ld equipment is repaired and left in place. 2. It appears that river cntrl will be expensive and it therefre seems lgical t attempt t prvide slutins which will minimize the need fr future dewatering which will be required if the repaired facilities ultimately fail r require additinal wrk. We recgnize there are limitatins n the funding capabilities f the Willwd Irrigatin District. The district's capabilities t fund repairs and replacements are discussed in the final reprt. 7.1 SPILLWAY APRON REPAIR We agree that repair f the spillway aprn shuld receive the highest pririty and be cmpleted as sn as pssible. If left uncrrected, the situatin has the ptential t cause serius damage t the structure. 7.2 CANAL GATES REPAIR - REPLACE SEAT Replacement f the canal gate seat wuld prbably slve the prblem f leakage arund the gates during the times when the canal is shut dwn. Hwever, because f the assciated csts t cntrl the river t allw access t the canal gates, we believe cnsideratin shuld be given t replacing the 65 year ld gates. 7.3 RIGHT ABUTMENT REPAIR We agree that cnstructin shuld be cmpleted t prevent further lss f material at the right abutment cntact. Cntinued lss f material at this lcatin culd result in undermining f the rad at the nrth end f the dam. 11

17 7.4 REPAIR SLUICE GATE STEMS If cmplete dewatering f the upstream pl is required t repair the sluice gate sterns cnsideratin shuld be given t replacing these 65 year ld gates because f the high cst assciated with the dewatering. 7.5 CRACKS ON DOWNSTREAM FACE OF DAM While the seepage thrugh the cracks n the dwnstream face f the darn des nt appear t be threatening the integrity f the structure at this time, we agree that they shuld be repaired. 7.6 MISCELLANEOUS CONCRETE REPAIR There are several lcatins where cncrete repair shuld be undertaken t prevent further deteriratin. 12

18 PHASE II FINAL REPORT

19 8.0 INTRODUCTION 8.1 DESCRIPTION The Phase II Final Reprt includes the preparatin f cnceptual designs, develpment f final cst estimates, an ecnreic analysis, and the identificatin f perreits necessary fr cnstructin. In additin, further discussin f elements f the Phase I Rehabilitatin Plan are included and an alternate plan fr river cntrl while replacing sluice gates is presented. 8.2 TURBIDITY CONSIDERATIONS The agreement discussed in Sectin 1.3 limits the increase in turbidity frm the upstream side t the dwnstream side f Willwd Dam t 10 NTU. The Shshne River belw Willwd Dam is a brwn trut fishery and the Wyming Game and Fish Department initiated the prcess that lead t this agreement in rder t prtect the fishery. Prir t the peratinal changes impsed by the agreement, the Game and Fish Department had been bserving fish kills dwnstream frm Willwd Dam that appeared t be related t the sluicing peratins. The fllwing infrmatin cncerning the brwn trut was btained frm Rn McKnight, Area Fishery Supervisr, fr the Game and Fish Department: 1. The brwn trut is a fall spawning ppulatin. 2. The trut start t spawn in late Octber r early Nvember, depending n water temperature and ther cnditins. 3. There shuld be n manipulatin f flws dwnstream frm Willwd Dam during the mnths f Nvember and December. The reductin f flws during this time culd uncver the eggs, and an increase in flw culd result in an increase in the water depth ver the eggs, bth f which will negatively impact the hatch. 4. Turbidities abve 15 NTU start t impact the trut. An analysis f the turbidity and flw data cntained in Appendix 2, yields the infrmatin cntained in Tables 1 and 2 belw: TABLE 1 Upstream Water Surface Elevatin % f Time Turbidity Increase Exceeds 10 NTU When Operating at r Belw Tabulated Elevatin 25.0% 25.7% 25.6% 25.9% 30.6% 36.8% 46.9% 13

20 TABLE 2 Sluice Gate Discharge cfs % f Time Turbidity Increase Exceeds 10 NTU When Discharging at r Belw Tabulated Rate 25.0% 23.4% 19.6% 17.7% 13.3% ~1.1% 9.7% Table 1 indicates that as the water surface elevatin f the upstream pl drps belw 4496, turbidity increases greater than 10 NTU becme mre frequent. Table 2 indicates that as the discharge thrugh the sluice gates decreases, the frequency f turbidity increases greater than 10 NTU als decreases. The significance f the infrmatin presented in Tables 1 and 2 will be discussed in subsequent sectins. 8.3 DEWATERING AND RIVER CONTROL Cmpletin f many f the repairs r replacements identified in the Rehabilitatin Plan will require dewatering and river cntrl at Willwd Dam. Figure 3 shws a cnceptual design fr facilities t reduce turbidity dwnstream frm Willwd Dam during cnstructin. Figure 4, which is a typical crsssectin f the Dam, shws the elevatin f varius facilities which may require repair r replacement and gives an indicatin f the extent f dewatering required t accmplish the necessary wrk Canal Gates Wrk n the canal gates wuld require lwering the water surface n the upstream side f Willwd Dam belw elevatin The flw in the Shshne River wuld have t be either pumped arund the dam r passed thrugh a sluice gate. Pumping appears t be prhibitively cstly therefre, use f the sluice gates appears t be the nly viable ptin. The calculated capacity f ne sluice gate, wide pen, wilh the upstream water surface at elevatin 4485 is in the range f 480 cis. Reference t Tab~e 1 indicates that at water surface elevatins belw 4493, turbidity increases wuld exceed 10 NTU a significant percentage f the time. Therefre, it appears that the turbidity cntrl measures discussed in Sectin 3.2 and shwn in Figure 3 will be required. 14

21 8.3.2 Sluice Gates - River Cntrl Alternate There appears t be an alternative t the methd discussed in Sectin 3.6 fr dewatering the upstream pl t allw wrk n the sluice gates. Preliminary calcu1atins indicate that the sluice ways thrugh the darn have a capacity f :00 t 150 cfs with the upstream water surface at elevatin The sluice way capacity is als dependent upn the elevatin f the water n the dwnstream side f the dam. This alternative plan fr dewatering wuld cnsist f the fllwing steps: 1. Cntrl the flws in the Shshne River abve Willwd Darn t 100 t 150 cfs. 2. Lwer the upstream pl t the lwest elevatin pssible us~ng the tw perable sluice gates. This wuld very likely result in a significant amunt f silt being carried thrugh the sluice ways ane depsited n the dwnstream aprn. 3. Remve sufficient silt upstream f the dam, using a drag line r sme ther methd, t enable the cnstructin f a small cfferdam which wuld allw the river flws t be alternated between the tw perating sluice gates. 4. Divert the river thrugh ne f the sluice ga~es and cmplete the replacement f the ther tw gates. Then divert the river flws thrugh ne r bth f the replaced gates and cmplete the wrk n the remaining gate. This plan wuld definitely require the cnstructin f the dwnstream turbidity cntrl facilities discussed in Sectin 3.2. The silt which wuld very likely be flushed thrugh the sluice ways and depsited n the dwnstream aprn wuld remain in place until water flwed ver the tp f the dam the fllwing spring, necessitating leaving the dwnstream diversin dam and sediment pnd in place and diverting the flws thrugh the sediment pnd t reduce the turbidity. If the river flws were t high, the detentin time in the sediment pnd culd be insufficient t maintain turbidity increases belw 10 NTU. If the decisin is made t replace sluice gates, the ptential impacts f this methd f river cntrl shuld be discussed with the Game and Fish Department. 15

22 Shshne River Flws Table 3 belw shws ~he average mnthly gain in cfs in the flw in the Shshne River between USGS gage and Willwd Dam. Gage is lcated west f Cdy, belw Buffal Dam and the pwer plants. Fr the perid f , the flw at Willwd Dam was assumed t be equal t the flw reprted at a secnd USGS gage which was lcated 3.3 miles upstream frm the Dam. Fr the perid , the flw at Willwd Dam was derived frm sluice gate perating data. TABLE 3 Average Between NOV Mnthly Gain in Shshne River USGS Gage & Will","d Dam - DEC JAN FEB MAR cfs Table 3 indicates that fr many mnths the gain in the Shshne River is very near the sluice way capacity if the upstream pl is lwered sufficiently t allw wrk n the sluice gates. As discussed in Sectin 1.4, during n~mal years with adequa~e wate~ supply, the flw in the Shshne River belw Heart Muntain Pwe~?lant is maintained at 350 cfs during the nn-irrigatin seasn. If there were any releases frm Buffal Bill Dam r the pwer plants during the perid when wrk was in prgress n the sluice gates, mst f the water wuld have t be diverted arund Willwd Dam. The Garland Canal which diverts frm the Shshne River at Crbett Dam, apprximately 8 miles abve Willwd Dam, has a capacity f apprximately 1,200 cfs, with a wasteway lcated n Eagle Nest Creek which flws int the Shshne River apprximately 1.8 miles dwnstream frm Willwd Dam. The use f this canal during the nn-irrigatin seasn wuld enable the diversin f a significant amunt f Shshne River flw arund the Willwd Dam site. Hwever, the amunt f flw diverted might be limited by the capacity f Eagle Nest Creek t carry the return flw and the canal culd be subject t icing during extreme cld weather. 16

23 8.4 REPAIRS AND REPLACEMENTS The Rehabilitatin Plan identified the ~epair items listed belw: and replacement Spillway Aprn Canal Outlet Wrks Sluice Gates Right Abutment Cntact Ersin at Right W~ng Wall Abutment Gruting Cracks n Dwnstream Face f 0am Miscellaneus Cncrete Repair 8.5 WILLWOOD IRRIGATION DISTRICT PRIORITI3S After review f the ~raft Rehabilitatin Plan, Willwd Irrigatin District identified their pririties in a letter t the Wyming Water Develpment Cmmissin, dated August 24, 1989, which is included as Appendix C. Further discussins with the manager f the Willwd Irrigatin District have prvided additinal infrmatin abut the items n their pririty list. The Willwd Irrigatin District feels that their irrigatrs are presently being assessed clse t the maximum amunt which they can affrd. Therefre, their pririty list nly addresses the items which they feel may be critical and emphasizes repair rather than replacement f many facilities. Because there is a pss~bility that much f the majr wrk culd be funded under the Pick-Slan Missuri Basin Prgram, at essentially n cst t the irrigatrs, the District wants t minimize the amunt f debt incurred at this time. The Pick Slan Prgram is discussed further in Sectin 11. The items n the Irrigatin District's pririty list are discussed in subsequent sectins Spillway Aprn Repair The Irrigatin District recgnizes the need t repair the cncrete damage n the spillway aprn as sn as pssible Canal Gate Repair - Replace Seat At sme time in the past the bttm was brken ff the gate frame f the nrth canal gate. This situatin prevented the gate frm clsing prperly and allwed a significant amunt f seepage int the canal during the winter. The Irrigatin District attempted t crrect this situatin by welding a bar n the inside f the frame but this attempt was nt ttally successful. In additin, the suth gate n lnger clses tightly and allws seepage int the canal. 17

24 A study f the drawing f the riginal canal gates indicates that the frame is very likely a casting. This being the case, crrectin f the prblem with the nrth gate wuld require at a reinimum remving the gate and frame, fabricating a new frame ut f steel, and rep~ac~ng the gate and frame. The drawi~gs als indicate that it may be pssi~le t replace the bttm seating surface n the suth gate frame if the frame itself has nt been damaged Right Abutment Rep2ir The intentin f the Irrigatin District is t repair the cncrete n the right abutment dwnstream wing wall whic~, in sme places, has deterirated t the pint that reinfrcing steel is expsed. The District's pinin is that the prblem which was discussed in the Rehabilitatin Plan under item 4.4 as Right Abutment Cntact, des nt affect the integrity f Willwd Vam. This prblem, if left uncrrected, culd ultimately undermine the rad acrss the dam at the nrth end f the structure, resulting in clsure f the rad. The Willwd Irrigatin District des nt need this rad t perate their structure and, therefre, feels that the prblem shuld be addressed by Park Cunty, which has respnsibility fr maintaining the rad. T~e ersin at the dwnstream end f the right wing wall whic~ was discussed in the Getechnical Reprt in Sectin 4.5, is nt deemed a critical prblem by the Irrigatin District. They placed sme riprap in this area several years ag and n further ersin has ccurred since that time Repair Sluice Gate Stems The perating stem f the suth sluice gate is visibly bent, rendering this gate inperable. In additin, the perating stem n the center sluice gate is slightly bent. The gate is still perable, althugh it has nt been perated since In additin, there may be sme stem guides which are brken away frm the face f the dam which shuld be replaced. The Irrigatin District's intent is t replace nly thse bent sectins f the perating stems and repair r replace stem guides as necessary Cracks n Dwnstream Face f Dam The Irrigati~ District is willing t repair the cracks n the dam face if this wuld nt increase the cst t the irrigatrs abve what they feel can be affrded Miscellaneus Cncrete Repair As in item 5 abve, the Irrigatin District is willing t undertake miscellaneus cncrete repair within their perce~ved funding limitatins. 18

25 9.0 CONCEPTUAL DESIGN Cnceptual designs are included fr the items identified by the Willwd Irrigatin District n their pririty list as well as sme items which we feel shuld be cnsidered fr repair r replacement if funding is available. In cases where Willwd Irrigatin District indicated that they wanted nly t cnsider repairs, we have included cnceptual designs and cst estimates fr the repairs as well as replacement. As mentined several places in this reprt, many f the features requiring repair r replacement are under water and we were unab~e t inspect these facilities t determine the actual damage and amun~ f repair r replacement wrk necessary. In these cases we have tried t estimate the maximum amunt f wrk necessary and develped ur cst estimates accrdingly. 9.1 SPILLWAY APRON The actual extent f ersin and damage t the existing cncrete spillway aprn cannt be determined until the surface f this area is dewatered, cleaned, and inspected. If pssible, this inspectin shuld be perfrmed during final design t accurately define the scpe f repair and rehabilitatin wrk needed. It appears at this time that, at a minimum, Blck 9 and the suth 23' f Blck 10 f the aprn, ttaling apprximately 3,700 square feet, shuld be remved and replaced (see Figure 5). Saw cutting the cncrete will be re~uired n the line 23' nrt~ f Blck 9, and at the cnstructin jints at the east end f the aprn and between Blcks 8 and 9, t ensure a straight and unifrm edge after demlitin. Due t the apparent degree f erded r damaged cncrete, it is anticipated that the tp f the underlying fundatin strata will need t be remved and replaced. The estimated quantity f the fundatin material (400 cubic yards) is based n an average depth f 2.5'. Rck anchrs gruted int the underlying strata and steel dwels at jints between the new and existing cncrete shuld be installed prir t placing the aprn cncrete. The estimated quantity f replacement cncrete (430 cubic yards) is based n an aprn sectin similar t the existing. Reinfrcing steel shuld be prvided in the aprn cncrete t resist shrinkage and temperature stresses, and as required by final design. The right wing wall shuld be replaced in its entirety (see Figure 6). The existing wall is designed as a cantilever retaining wall supprted frm the spillway aprn. Due t its age and prbable cnditin, the existing aprn may nt be capable f prviding stability fr a recnstructed wall. Therefre, a sectin f the aprn adjacent t the wall, apprximately 12' wide, shuld be remved and replaced as described abve. Cntinuus reinfrcement shuld extend frm the aprn int the wall t resist lateral earth pressures. 19

26 Recnstructin f the damaged areas f the spillway aprn and the right wingwall will require river cntrl measures described in Sectin 3.4. In additin, dewatering the excavated areas wil: likely be necessary during cnstructin t cntrl grundwater seepage and any leakage. Prvisins t cntrl r divert the leakage frm the pwer utlet and canal gates shuld be made t prevent water frm flwing dwn the spillway face and erding freshly placed cncrete. 9.2 CANAL OUTLET WORKS The leakage bserved with the gates clsed ccurs primarily at r near the bttm seats. Althugh the gate assemblies n the upstream face f the dam were nt inspected, it is prbable that the bttm frame and seat are brken, resulting in insufficient seating f the gate. Crrsin at the bttm f the gate leaf r at the adjacent cncrete may als be cntributing t the leakage. A clse examinatin f the upstream side f the gates will be necessary t accurately determine the cause and extent f the leakage r ther prblems assciated with the peratin f the gates. Replacing the gate frames and bttm seats wuld require lwering the water surface elevatin n the upstream side f the dam belw elevatin 4487, and perfrming turbidity cntrl measures described in Sectin 3.2. Making repairs with divers may be pssible; hwever, if the scpe f repair wrk is extensive, underwater repair may nt be feasible and the cmpleted wrk may nt be adequate. New frames and seats, fabricated t match thse existing culd be installed. The wrk wuld include remving the existing gates, frames and stems, repairing damaged r deterirated cncrete and anchr blts, installing new frames, grinding and repairing damage t the gate leaves, and reinstalling the gates and stems. It is pssible that nly the seat bar and a prtin f the gate frame wuld require replacement. Due t the age f the gate assemblies and the assciated csts f river cntrl, we recmmend that cnsideratin be given t replacing the gates, frames, headwrks, and peratrs. New gates wuld prvide a better lng term slutin and reduce subsequent maintenance and peratin csts. In additin, peratrs with limit and trque cntrl wuld reduce the pssibility f future damage t the gates. 9.3 SLUICE GATES The sluice gates were nt inspected during ur field investigatin and the cnditin f the gates and frames belw the surface f the water is unknwn. The stems n the center and suth gates are bent, and shuld be straightened r replaced. It is prbable that sme stem gules may be brken and n lnger prvide lateral supprt t the stems. 20

27 Remval and replacement f the stems and repair f the stem guides under the water surface, as well as a limited inspectin f the gates and frames, may be able t be perfrmed by divers. Althugh dewatering f the upstream pl wuld nt be necessary, the silt depsits near the suth gate shuld be remved befre wrk n the stems is perfrmed and the gate is put int peratin again. Wrk n the gates and frames, if required, will necessitate cmplete dewatering f the upstream pl as described in Sectin 3.6 (remval f the upstream silt is included in this wrk). Cnsidering the high cst assciated with the dewatering peratins, we recmmend that cnsideratin be given t replacing the gates and frames if cmplete dewatering is perfrmed. Operatrs with limit and trque cntrl shuld als be cnsidered t reduce the ptential f future damage t the gates and stems. 9.4 RIGHT ABUTMENT CONTACT Ersin alng the cntact line between the right abutment and and the natural grund surface is starting t undermine the rad n the dwnstream side f the dam. If this situatin is left uncrrected, the pssibility exists that all r part f the rad culd becme under~ined, rendering it impassable. One methd f crrecting this situatin wuld be t extend the vertical wall at the right abutment f the dam dwnstream apprximately ten t fifteen feet and cnstructing a wall frm the dwnstream end f the new wall back t the existing rck face. The base f the new wall wuld rest n the tp f the existing r replaced dwnstream wing wall and be dweled int the existing vertical wall. Anchr blts wuld be drilled int the embankment face and cnnected t the new wall t prvide additinal stability. The space behind the wall and in frnt f the existing rck face wuld be backfilled with a clean gravel which wuld drain any water thrugh apprpriately spaced weep hles thus minimizing the build-up f hydrstatic frces. The design cncept is shwn in Figure CRACKS ON DOWNSTREAM FACE OF DAM The cracks, which are hrizntal, are very likely alng cnstructin jints made during riginal cncrete placement. There is a shrt crack near the suth abutment which is visible during the winter when n water is flwing ver the crest f the dam. The ther crack extends almst the full width f Blck 10 at the nrth abutment f the dam. The methd prpsed t crrect this situatin anticipates drilling hles at a fur r five ft spacing int the face f the dam near the crack and riented t intercept the crack behind the face f the dam. Apprpriate chemical grut wuld be injected int the hles under pressure t seal the cracks. 21

28 9.6 MISCELLANEOUS CONCRETE REPAIR Repair f areas where cncrete deteriratin has ccurred can be accmplished by remving the damaged cncrete in these areas until sund cnc~ete is encuntered. The existing cncrete surface wuld then be cated with an apprpriate bnding agent anc new cncrete placed t fill the damaged area back t its riginal surface cr.figuratin COST ESTIMATES The cst estimates assciated with the recmmended rehabilitatin w~k a~e presented n the fllwing pages. The estimates ~eflect 1990 prices, and unit prices are based n bid tabulatins f recent prjects, cnstructin estimating guides, and cnversatins with material suppliers and cntractrs. The estimates prvided are a budget-level estimate and ttal cnstructin csts include a 15% cntingency RIVER CONTROL FOR SLUICE GATE REPLACEMENT - ALTERNATE The cst estimate fr the alternate methd fr dewatering the upstream pl discussed in Sectin is presented belw: Mbilizatin/Dembilizatin - LS Silt Remval - 40,000 $3.00 Flw Diversin Thrugh Sluice Gates - LS $ 4,000 $120,000 $ 6,000 SUBTOTAL Engineering Cntingency TOTAL $130,000 $ 13,000 $ 19,500 $162,500 22

29 10.2 SPILLWAY APRON Mbilizatin/Dembilizatin - LS Saw cut existing cncrete, 184 $10.00 Remve existing aprn cncrete, 430 $22.00 Lcal dewatering, 25 $ Install rck anchrs, 630 $15.00 Replace fundatin material, 400 $40.00 Install dwels, $12.00 Replace cncrete, 430 $ Aprn Subttal Saw cut existing cncrete, 62 $10.00 Excavatin, 545 $10.00 Remve existing aprn/wall cncrete, 150 $22.00 Install rck anchrs, 180 $15.00 Replace fundatin material, 98 $40.00 Install dwels, $12.00 Replace aprn cncrete, 100 $ Replace wall cncrete, 62 $ Cmpacted Backfill, 600 $12.00 Wing Wall Subttal SUBTOTAL Engineering Cntingency TOTAL $ 10,000 $ 1,840 $ 9,460 $ 5,000 $ 9,450 $ 16,000 $ 3,300 $139,750 $194,800 $ 620 $ 5,450 $ 3,300 $ 2,700 $ 3,920 $ 960 $ 32,500 $ 24,800 $ 7,200 S 81,450 $276,250 S 27,625 $ 41,125 $345,000 Requires River Cntrl Items: Turbidity Cntrl Dwnstream Cfferdam Installatin Subttal $ 62,500 $ 87,500 $150, CANAL OUTLET WORKS Replace Frames Only Remve existing gates, frames, and stems, $3500 Repair cncrete and frame anchrages, $5500 Fabricate new frames and seats, $8000 Repair gate leaves, $2500 Install new frames, reinstall gates and stems, $4500 SUBTOTAL Engineering Cntingency TOTAL $ 7,000 S 11,000 $ 16,000 S 5,000 S 9,000 S 48,000 S 4,800 $ 7,200 $ 60,000 Requires River Cntrl Items: Turbidity Cntrl Dwnstream $ 62,500 23

30 Replace Cmplete Gate Assemblies Remve existing gates, frames, stems, and peratrs, $4500 Rep2i~ cncrete and frame anch~ages, $5500 Install new gates, frames, and peratrs, $50,000 SUBTOTAL Engineering Cntingency TOTAL $ 9,000 $ 11,000 $100,000 $120,000 $ 12,000 $ 18,000 $150,000 Requires River Cn~rl Items: Turb~dity Cntrl Dwnstream $ 62, SLU!CE GATES lo.4.1 Replace Stems Only Remve silt upstream at suth gate, 4700 $5 Remve existing stems, $2200 Repair stem guides and anchrages, $800 Fabricate and install new sterns, $5000 SUBTOTAL Engineering Cntingency TOTAL $ 23,500 $ 6,600 $ 14,400 $ 15,000 $ 59,500 $ 5,950 $ 8,950 $ 74, Replace 2 Gate Assemblies - Abandn Suth Gate Remve existing gates, frames, and sterns, $6000 Repair stem guide anchrages, $500 Install new gates, frames, sterns, and peratrs, $35,000 Grut Suth Cnduit SUBTOTAL Engineering Cntingency TOTAL $ 18,000 $ 6,000 $ 70,000 $ 11,000 $105,000 $ 10,500 $ 16,500 $132,000 Requires River Cntrl Items: 5.1 Turbidity Cntrl Dwnstream $ 62, Cfferdam and Silt Remval Upstream, Temprary Pipe $400, Temprary Pumping Facilities $ 87,500 Subttal $550,000 If the methd f river cntrl discussed in Sectin and estimated t cst $162,500 can be used, items 5.2 and 5.3 culd be eliminated. The ttal cst fr river cntrl wuld be $225,

31 Replace 3 Gate Assemblies Remve existing gates, frames, and stems, $6000 Repair stem guide anchrages, $500 Install new gates, frames, stems, and peratrs, $35,000 SUBTOTAL Engineering Cntingency TOTAL $ 18,000 $ 9,000 $105,000 $132,000 $ 13,200 $ 19,800 $165,000 Requires River Cntrl Items: 5.1 Turbidity Cntrl Dwnstream $ 62, Cfferdam and Silt Remval Upstream, Temprary Pipe $400, Temprary Pumping Facilities $ 87,500 Subttal $550,000 If the methd f river cntrl discussed in Sectin and estimated t cst $162,500 can be used, items 5.2 and 5.3 culd be eliminated. The ttal cst fr river cntrl wuld be $225, RIGHT ABUTMENT CONTACT Scale existing rck face, LS $ 3,000,... Cnstruct reinfrced cncrete wall, 60 $450 y 27,000 Install 50 anchr blts, 20' $15.00/LF $ 15,000 Gravel backfill, 400 $12.50 $ 5, CRACKS ON DOWNSTREAM FACE OF DAH SUBTOTAL $ 50,000 Engineering $ 5,000 Cntingency $ 7,500 TOTAL $ 62,500 Mbilizatin/Dembilizatin, LS $ 4,000 Drill, 20 $200 EA $ 4,000 Set and cnnect t surface fitting and pump grut, 20 $100 EA $ 2,000 Grut $ 2,000 SUBTOTAL $ 12,000 Engineering $ 1,200 Cntingency $ 1,800 TOTAL $ 15,000 25

32 10.7 MISCELLANEOUS CONCRETE REPAIR Remve cncrete 4" deep, per sq. ft. Patching material, per sq. ft. Subttal Assume 400 Sq. $50 $ ,000 SUBTOTAL $ 20,000 Engineering $ 2,000 Cntingency $ 3,000 TOTAL $ 25,000 Repairs in areas such as the bttm f the wing walls r upstream face f the dam wuld require ne r mre f the river cntrl items TOTAL PROJECT COST The ttal prject cst estimate is based n the assumptin that the items discussed in the Phase II Reprt will be replaced rather than repaired. River Cntrl Items 5.1, 5.2, 5.3, & 5.4 $ Spillway Aprn $ Canal Gates - Replace Cmplete Gate Assemblies $ Sluice Gates - Replace 3 Gate Assemblies $ Right Abutment Cntact 5 Cracks n Dwnstream Face f Dam $ Miscellaneus Cncrete Repair $ 637, , , ,000 62,500 15,000 25,000 River cntrl amunts t 46% f the ttal cst 10.9 TOTAL PROJECT COST - RIVER CONTROL ALTERNATE TOTAL $1,400,000 River Cntrl Items 5.1, 5.4, & $ Spillway Aprn $ Canal Gates - Replace Cmplete Gate Assemblies $ Sluice Gates - Replace 3 Gate Assemblies $ Right Abutment Cntact $ Cracks n Dwnstream Face f Dam $ Miscellaneus Cncrete Repair $ 312, , , ,000 62,500 15,000 25,000 River cntrl amunts t 29% f the ttal cst TOTAL $1,075,000 26

33 10.10 PROJECT COST - WILLWOOD PRIORITY LIST Because f their cncern abut the magnitude f additinal assessments t their irrigatrs, the Willwd Irrigatin District is cnsidering repairs rather than replacement f many f the items. River Cntrl Items 5.1 and 5.4 Spillway Aprn Canal Gates - Replace Frames Only Sluice Gates - Replace Stems Only Cracks n Dwnstream Face f Dam Miscellaneus Cncrete Repair $150,000 $345,000 $ 60,000 $ 74,400 $ 15,000 S 25,000 TOTAL $669,400 River cntrl amunts t 22% f the ttal cst ECONOMIC ANALYSIS 11.1 ABILITY TO PAY Current District Assessments The tables belw summarize the 1989 assessments paid by landwners in three irrigatin districts, including Willwd, which are part f the Shshne Prject. The assessments are in dllars per acre. WILLWOOD $ PER ACRE Operatin & Maintenance R & B Prject-Repayment Cmplete Cnstructin Lan-Repayment Cmplete Ttal Average GARLAND Operatin & Maintenance R & B Prject Crbett Tunnel Ttal HEART MOUNTAIN Operatin & Maintenance R & B Prject Cnstructin (Average) Ttal

34 Federal Funding Surces The Bureau f Reclamatin is currently cnducting a Rehabilitatin and Betterment (R & B) study fr the entire Shshne Prject. The Bureau f Reclamatin is ~u~ding 50% f this study and the irrigatin districts are funding the ther 50% with funds prviced by the Wyming Water Develpment Cmmissin. The purpse f the R & B study is t identify irrigatin facilities that need repair r replacement and prepare cst estimates fr the wrk. An element f the R & B Study is a farm budget analysis t determine a district's ability t pay fr R & B prjects. The Farm Budget Analysis is scheduled fr cmpletin in Nvember, R & B prjects are funded by zer interest lans with a maximum term f frty years, with the term f the lan being set by the Bureau f Reclamatin. The lans cver the design and cnstructin csts f the prjects. Under the R & B prgram, an irrigatin district can cmplete all r part f the wrk with their wn frces and equipment and be reimbursed fr their csts. Anther Federal funding surce is the Pick-Slan Missuri Basin Prgram. Funds fr the Pick-Slan Prgram are derived frm pwer revenues frm generating facilities assciated with irrigatin prjects. There are n direct csts t the irrigatin districts fr prjects funded under the Pick-Slan Prgram. Hwever, under Pick-Slan, the prjects require cngressinal legislatin fr funding. Given the current situatin with the Federal budget, funds under Pick-Slan culd be difficult t btain and might require several years befre they became available Alternative Funding Plans Tables 4, 5, and 6 present an annual cst per acre fr the three prjects discussed in Sectin 10, under varius cmbinatins f funding. The csts are calculated based n 11,422 acres f assessable land in Willwd Irrigatin District. In ur pinin, repair prjects wuld prbably be subject t a shrter repayment perid than prjects in which the existing facilities are replaced with new cnstructin. 28

35 TABLE 4 - TOTAL PROJECT ANNUAL COST IN DOLLARS PER ACRE LOAN REPAYMENT PERIOD 10 YR 20 YR 30 YR 40 YR TOTE-_L?ROJECT COST $1,400,000 WWDC GRANT FUNDING 50% $700,000 WWDC LOAK 4% INTEREST $700,000 $7.56 $4.51 $3.54 $3.10 WWDC GRANT FUNDING 67% $938,000 WWDC LOAN 4% INTEREST $462,000 $4.99 $2.98 $2.34 $2.04 USBR R & B LOAN 0% INT. $1,400,000 $12.26 $6.13 $4.09 $3.06 ~lwdc GRANT FUNDING 50% $700,000 USBR R & B LOAN 0 96 INT. $700,000 $6.13 $3.06 $2.04 $1.53 WWDC GRANT FUNDING 67% $938,000 USBR R & B LOAN 0% INT. $462,000 $4.04 $2.02 $1.35 $1.01 TABLE 5 - TOTAL PROJECT WITH RIVER CONTROL ALTERNATE COST IN DOLLARS PER ACRE LOAN REPAYMENT PERIOD 10 YR 20 YR 30 YR 40 YR TOTAL PROJECT COST $1,075,000 WWDC GRANT FUNDING 50% $537,500 WWDC LOAN 4% INTEREST $537,500 $5.80 $3.46 $2.72 $2.38 WWDC GRANT FUNDING 67% $720,250 WWDC LOAN 4% INTEREST $354,750 $3.83 $2.29 $1.80 $1.57 USBR R & B LOAN 0% INT. $1,075,000 $9.41 $4.71 $3.14 $2.35 WWDC GRANT FUNDING 50% $537,500 USBR R & B LOAN 0% INT. $537,500 $4.71 $2.35 $1.57 $1.18 WWDC GRANT FUNDING 67% $720,250 USBR R & B LOAN 0% INT. $354,750 $3.11 $1.55 $1.04 $

36 TABLE 6 - WILLWOOD'S PRIORITY LIST ANNUAL COST IN DOLLARS PER ACRE LOAN REPAYMENT PERIOD 10 YR 20 YR 30 YR 40 YR TOTAL PROJECT COST $669,400 WWDC GRANT FUNDING 50% $334,700 WWDC LOAN 4% INTEREST $334,700 $3.61 $2.16 $1.69 $1.48 WWDC GRANT FUNDING 67% $448,498 vlwdc LOAN 4% INTEREST $220,902 $2.38 $1,42 $1.12 $0.98 USBR R & B LOAN 0% INT. $669,400 $ $1.95, $1.47 WWDC GRANT FUNDING 50% $334,700 USBR R & B LOAN 0% INT. $334,700 $2.93 $1.47 $0.98 $0.73 WWDC GRANT FUNDING 67% $448,498 USER R & B LOAN 0% INT. $220,902 $1.93 $0.97 $0.64 $ BENEFIT COST ANALYSIS The prblems with Willwd Dam which are the subject f this reprt are such that very little can be dne frm a maintenance stand-pint n an annual basis t crrect them. Therefre, there wuld be n significant reductin in annual maintenance csts due t the crrectin f any f these prblems. Hwever, if failing t crrect sme f the prblems ultimately created a situatin that prevented delivery f all r part f the water t the lands under the Willwd Canal, there wuld be significant adverse ecnmic impacts n the farmers in the district as well as n the surrunding area. Sme examples f such impacts are: A. Farmers frced int bankruptcy due t inability t service their debt. B. Willwd Ir~igatin District defaulting n lans due t farmers being unable t pay their assessments. C. Lss f prperty and sales tax revenues. D. Lss f business in the surrunding cmmunities PERMITS, EASEMENTS, AND AGREEMENTS Several permits, easements and agreements are required fr the cnstructin necessary t rehabilitate Willwd Dam. These permits cnstitute a significant effrt in time and mney. Sme f these permits shuld be secured by the Owner prir t bidding the prject, due t the cmplexity and lng lead time required. Other permits which are speci ic t a Cntract~'s peratin and methd f cnstructin shuld be btained by the Cntractr. Owner-secured permits as well as Cntractrsecured permits will be identified in this sectin f the reprt. 30

37 12.1 PERMITS :2.1.1 Dredge and Fill Permits (404 and Natinwide). A key permit required fr this prject is the 404 Permit. The U.S. Army Crps f Engineers, under Sectin 404 f P.L (the Clean Water Act), requires permits t authrize dredging r placement f fill in the waters f the United States. An individual 404 Permit, Natinwide Permit authrizatin, r bth, will be required t permit cnstructin f the dwnstream diversin dam necessary fr turbidity cntrl. Generally, a permit is required t place fill material in r t dredge material frm a stream channel r ther bdy f water. Initial cntacts with Crps persnnel indicate the pssible issuance f Natinwide Permits t accmmdate all activities under this prject. The Natinwide Permit prcess is simpler and much less time cnsuming than the 404 Permit prcess; hwever, a final determinatin f the actual permitting requirements by the Crps has nt yet been made. Nrmal prcessing time fr a nn-cntrversial 404 Permit applicatin is tw t three mnths; hwever, an allwance up t six mnths shuld be prvided. The Crps may als require that a public hearing be cnvened t receive public input. The time frame t secure necessary permitting r authrizatin frm the Crps is dependent upn the need fr an EA, and the necessity t acquire 404 Permits rather than Natinwide Permit authrizatin Sectin 401 Certificatin The Wyming Department f Envirnmental Quality (DEQ), under Sectin 401 f the Clean Water Act, will review the applicatin fr 404 Permit activities with the intent t certify prject activities in accrdance with the Act. Nrmally, n additinal requirements ver and abve the 404 Permit are required by the DEQ and, if they are, these requirements are incrprated int the 404 Permit. Prcessing f the 401 Certificatin is cncurrent with the 404 Permit prcess Archaelgy and SHPO Clearance Clearance frm the State Histrical Preservatin Officer (SHPO) is required befre grund disturbing activities ccur. In rder t receive SHPO clearance, an archaelgical survey f the prject site must be made. If archaelgical sites which are cnsidered eligible fr the Natinal Register are lcated, tw ptins are available: 1. The site can be mitigated by archaelgical excavatin, r 2. If pssible, facilities such as sediment pnds can be mved t avid the area. 31

38 State Engineer's Office Permits fr temprary facilities and cnstructin water are requi~ed by the State Engineer's Office. Temprary sediment pnas require permits t cnstruct frm bth the State Engineer's Office and the DEQ (see paragraph ). If the Cntractr requires temprary sediment pnds fr his peratin, he will be respnsible t btain the State Engineer's permits. These permits generally can be prcessed within 30 t 60 days. Temprary cnstructin water requires the develpment f a Temprary Use Agreement with the permittee frm which the water is being purchased. The Cntractr will be respnsible t lcate and secure the necessary agreements and t file these frms and btain the apprval f the State Engineer's Office Department f Envirnmental Quality (DEQ) Permits Varius permits may be required frm the Wyming DEQ t cnstruct this prject. Mst f these permits are cnstructin riented and the Cntractr shuld be assigned the respnsibility t apply fr and secure the cnstructin riented permits Water Quality Divisin (WQD) Permits are required t cnstruct sediment pnds. Prcessing time fr permits t cnstruct are generally 30 t 90 days. A Natinal Pllutant Discharge Eliminatin System (NPDES) Permit, als called a discharge permit, is required if discharges are made frm sediment int a receiving water f the State. An NPDES Permit is als required if discharges are made int a receiving water frm trench r ther cnstructin dewatering peratin. In lieu f discharging directly int a receiving water as a pint discharge, a diffused discharge f wastewater r dewatering effluent shuld be made. Generally, this prcess is termed land treatment and the DEQ is respnsible t permit such peratins. The Cntractr will be assigned the respnsibility t apply fr and secure land applicatin permits Land Quality Divisin (LQD) The LQD is respnsible fr administering the permit prcess fr mining peratins and slid waste dispsal areas. The Cntractr will require a material surce fr the dwnstream diversin dam and sediment pnd cnstructin. The Cntractr will be assigned the respnsibility t lcate, secure, and btain permits fr brrw areas as required. 32

39 12.2 EASEMENTS Waste areas may be required t dispse f cnstructin debris, ther than petrleum by-prducts. The Cntractr will be respnsible fr acquiring a permit frm the DEQ if he elects t develp a waste area. Otherwise, the Cntractr shuld be encuraged t use existing landfills Air Quality Divisin (AQD) Permits will be required frm the AQD t burn selected cnstructin debris and materials cleared frm the sediment pnds if the Cntractr chses t dispse f these materials by burning. Temprary cnstructin easements will prbably be required fr the cnstructin f sediment pnds and t acquire a staging area fr the Cntractr's peratins. The Owner shuld prbably be respnsible fr acquiring these easements. A lng lead time is nt anticipated AGREEMENTS Shshne River Operatins Significant cntrl f the flws in the Shshne River can be exercised by the Bureau f Reclamatin by cntrlling discharges frm the Buffal Bill Dam, the Buffal Bill Pwer Plant, and the Heart Muntain Pwer Plant. During cnstructin it will be necessary t limit the flws at Willwd Dam t the lwest flws pssible in rder t minimize the cst f river cntrl. As discussed in Sectin there is a pssibility f diverting river flws at Crbett Dam, upstream frm Willwd, and returning the flws t the river apprximately 1.8 miles dwnstream frm Willwd Dam. The Wyming Game and Fish Department very likely has sme criteria fr minimum flws needed t prtect the fishery. Because f the imprtance f minimizing river flws during cnstructin and the anticipated lng lead time t secure an agreement between the parties invlved, discussins with the Bureau f Reclamatin and the Wyming Game and Fish Department shuld begin well in advance f the anticipated start f cnstructin and be cmpleted befre the prject is bid s that cntractrs can be aware f the amunt f flw they will have t divert r pump. An agreement n the amunt f flw t be anticipated at Willwd will als be necessary during design s that sediment pnds can be prperly sized. 33

40 Diversin at Crbett Dam Shshne-Heart Muntain Irrigatin District perates Crbett Dam and the Garland Canal. As discussed in Sectin 8.3.3, Shshne River flws culd be diverted arund Willwd Dam using the Garland Canal, during the nn-irrigating seasn. Discussins shuld be initiated as sn as pssible with the Shshne Heart Muntain Irrigatin District t determine the viability and pssibility f using the Garland Canal fr this purpse, if the selected cnstructin prject wuld require such a diversin APPROVALS Any cnstructin dne at Willwd Dam will be subject t apprval by the Bureau f Reclamatin. In rder t facilitate this apprval, discussins with the Bureau f Reclamatin shuld be initiated early in the final design prcess. 34

41 LIST OF FIGURES FIGURE 1 - FIGURE 2 - FIGURE 3 - FIGURE 4 - WILLWOOD DIVERSION DAM SPILLWAY APRON DOWNSTREAM TURBIDITY CONTROL FACILITIES CROSS SECTION OF WILLWOOD DAM FIGURE 5 - TYPICAL SECTION - RECONSTRUCTED SPILLWAY APRON FIGURE 6 - TYPICAL SECTION - RECONSTRUCTED RIGHT WINGWALL FIGURE 7 - RIGHT ABUTMENT - CONTACT

42 w J E Narc: Prnk'cM G.A~h.'~ct;Pf' 4S n(l"er(j (I, I. ~;:s CDn,-"r".,r~ Tep f Cui L. ( '-~ Ccl7Crek C OF7!'I+' i/!! ~/0t7RcJr UlllfTCD atat.~ RZC'-UIIAT.OCIII s.~~ ~ SHOSHOH PFIQJ CT-WYO,.,IH. IN'ILLYY'OOO CUVISION ~ WI.LL~... a DIVERSION DAM '( I.DI;ATJC!4.DIJ:JIAJ."~AIID SECTIDIIS :'bt---...;..----~~~r-'lr-...,.---i ~ -~~----- fj.~~~.~s_--1 ~~2~3;2;;~~~z~~;~~~~;;~~~~~~~~

43 l--'2,.. 60' "I SUGGESTED WAITS OF CONCRETE I ~ REMOVAL AND REPLACEMENT I I ~ ,~ ~.) ~c: == ~ ~ ~ DOWNSTREAM EDGE OF CONCRETE APRON ~ ~ ~44~... ~ ~ cr J. :J Q '-44S e S2- ===:::= ---- ~ ~ " I '~ I '1" ~I---'~~~~~ ~--~~~ ~--~--~~~~ ~~ ~ " 1 "-"' ~ 1 ' "'- 1 '----- ~ ~~~~-~ ~~ ~--~~ ~--~--~~--~--M-----~~~==~~~~==~~~~--~~~~~~ I..., / I 1 ~ ~.""., <i= ---.",.,..- -"" '" I " I'=-----~,,/ TOP OF EXISTING CONCRETE SURFACE I '../ DETERMINED BY SURVEY SEPT. 27, ~" L _ ~ (TYPICAL) = COMPUTED TOP OF ORIGINAL CON~ SURFACE (TYPICAL) 0+00 I -- " /' I VERllCAL SCALE: ' REVISED 8/7/89 '" HORIZONTAL SCAl.E: ft FIGURE 2

44