Dave Johnston Power Plant · adjacent to the embankments’ crests, URS does not recommend any credit to the membrane for seepage prevention or embankment stability, however, PacifiCorp

2015 Coal Combustion Residuals Annual Inspection

Dave Johnston Power Plant 4A Pond

Prepared for PacifiCorp Energy North Temple Office 1407 West North Temple Salt Lake City, Utah 84116

Final December 29, 2015

URS Corporation 756 East Winchester, Suite 400 Salt Lake City, Utah 84107

2015 Dave Johnston 4A Pond Inspection i

Contents1 Findings ................................................................................................................................................. 1

2 Description and History of 4A Pond ...................................................................................................... 3

2.1 General Overview ......................................................................................................................... 3

2.2 Location ......................................................................................................................................... 3

2.3 4A Pond Descriptions .................................................................................................................... 3

2.4 Performance History ..................................................................................................................... 6

2.5 Construction History ..................................................................................................................... 6

2.6 Review of Operating Record Files ................................................................................................. 6

2.6.1 Design and Construction Information ................................................................................... 6

2.6.2 Previous Periodic Structural Analyses ................................................................................... 6

2.6.3 Results of Inspection by a Qualified Person .......................................................................... 6

2.6.4 Results of Previous Annual Inspections ................................................................................ 7

3 Field Inspection of 4A Pond .................................................................................................................. 7

3.1 4A Pond Geometry ........................................................................................................................ 7

3.2 General .......................................................................................................................................... 8

3.3 Instrumentation ............................................................................................................................ 8

3.4 Impounded Water Depth and Volume ......................................................................................... 8

3.5 Storage Capacity ........................................................................................................................... 8

3.6 Observed or Potential Structural Weaknesses ............................................................................. 8

3.7 Observed Changes ........................................................................................................................ 8

4 Limitations and Consultant Qualifications ............................................................................................ 9

4.1 Limitations ..................................................................................................................................... 9

4.2 Professional Engineer Qualifications ............................................................................................ 9

5 References .......................................................................................................................................... 10

Appendices

Appendix A Photograph Log

Appendix B Annual Inspection Report Form

Appendix C Example PacifiCorp Inspection Form

2015 Dave Johnston 4A Pond Inspection 1

1 Findings This annual inspection and report are being completed for the purpose of providing due diligence by PacifiCorp to ensure the safety of its coal combustion residual facilities. The inspection was performed according to the requirements for annual inspections under Section 257.83 (CCR surface water impoundments) of 40 CFR Parts 257 and 261, Hazardous and Solid Waste Management System; Disposal of Coal Combustion Residuals from Electric Utilities, Final Rule, dated April 17, 2015 [18].

The field inspection was performed on August 31, 2015 and found the principal project features of the 4A Pond to be in satisfactory condition. Nothing was observed suggesting an active or impending dam safety issue. Figure 1-1 is a site plan showing the location of 4A Pond in relation to 4B Pond and 4 Clear Pond.


Figure 1‐1. Site Plan for 4A Pond


Observations from the 2015 inspection include:

1. Inoperable overflow CMP outlets

2. Area of damp soil along the 4A Pond south embankment

A CCR rules requirement for signage requires the 1) name of owner; 2) name of unit; and 3) state ID

number. The following photo (Figure 1‐2) demonstrates that a sign is in place. No state ID number has

been assigned to 4A Pond embankment; consequently URS recommends that the NPDES Permit Number

WY0003115 be added to the sign to satisfy the CCR rules requirement.

Figure 1‐2. Sign for 4A Pond

2 DescriptionandHistoryof4APond

2.1 GeneralOverviewThe Dave Johnston Plant (Plant) is operated by PacifiCorp (PacifiCorp). An aerial photograph depicting

the Dave Johnston Plant and associated facilities is presented as Figure 1‐1.

2.2 LocationThe Dave Johnston Power Plant is located immediately north of Interstate 25, approximately 20 miles

east of Casper in Converse County, Wyoming. The plant was originally a mine‐mouth facility, but is now

supplied with coal by rail. PacifiCorp owns and operates all four units at the Dave Johnston Power Plant.

A site plan of the power plant complex and 4‐Series Ponds(4A and 4B) is shown on Figure 1‐1.

2.3 4APondDescriptionsThe 4‐Series Ponds (4A and 4B) were constructed in approximately 1971 to accommodate increased ash

loading associated with the addition of Unit 4. The ponds typically receive only bottom ash, but have


previously also received fly ash and FGD wastes. The 4A Pond has a surface area of 19.5 acres and a

storage capacity of 144.6 acre‐feet (see Table 2‐1).

The perimeter embankment crest elevation of 4A Pond is 4962.5 feet and the 4A/4B interior dike is set

at elevation 4965.0 feet as shown in Figure 2‐1.

Figure 2‐1. 4 Series Pond Features

The inflow to 4A Pond occurs at the north end of the ponds. The 12‐inch inflow pipelines to 4A Pond are

shown in Photo 7.

Periodically, 4A Pond is dewatered to allow excavation and removal of accumulated bottom ash and

sediment. Table 2‐1 is a summary of pertinent data on 4A Pond.


Table 2‐1. 4A Pond Pertinent Data [1]

Description Design Value

Pond:

Total Pond Capacity (acre‐feet) 144.6 [14]

Maximum Pond Elevation (feet) 4,961 [14]

Surface Area (acres) 19.5 [3]

Pond Perimeter (feet) 3,800 [3]

Drainage Area (square miles) 60.9 [5]

Design Freeboard (feet) 1.5 [14]

Embankment:

Type Fly ash Core with Sand Shell [14]

Maximum Design Height (feet) 12.5 [14]

Design Crest Width (feet) 18 [14]

Design Crest Length (feet) North Embank.: 600 [14] East Embank.: 1,200 [14]

Design Crest Elevation (feet) 4,962.5 [14]

Design Upstream Slope (feet) North Embank.: 4:1 [14] East Embank.: 4:1 [14]

Design Downstream Slope (feet) North Embank.: 3:1 [14] East Embank.: 3:1 [14]

Pond Outlet Structure:

Type 4A/4B Reinforced Concrete Outlet Control Structure

Crest Elevation (feet) Unknown

Crest Length (feet) Unknown

Gates Slide Gate

Gate Invert Elevations (feet) 4,948 [14]

Conveyance 30” RCP [14]

Conduit Length (feet) Unknown

Conduit Upstream Invert Elevation (feet)

4,950 [14]

Conduit Downstream Invert Elevation (feet)

Unknown

Energy Dissipation Concrete Apron

Emergency Spillway: Yes

Type Box Culvert

Crest Elevation (feet) 4,961.75 [14]


2.4 PerformanceHistoryBetween 1992 and 1995, a geosynthetic membrane liner was installed in in 4A Pond to reduce seepage.

Between the GEI site inspection in 2011 [3] and 2013, the 4A/4B Outlet Control Structure at the downstream end of 4A and 4B Ponds filled with ash, allowing ash to flow into and fill 4 Clear Pond. Ash clogged the intake to the Scrubber Pump Station and may have overflowed and filled portions of the Blowdown Canal. The CCR was subsequently removed from the downstream features.

The discharge structure has been reconstructed and improved as observed during the 2015 inspection.

2.5 ConstructionHistoryModifications to the ash disposal system in 1971 included the addition of the 4A Pond. When

completed, bottom ash and sometimes FGD waste were pumped to either the 4A or 4B Pond.

2.6 ReviewofOperatingRecordFilesThe list of operating records to be reviewed during the annual inspection as contained in 40 CFR §257,

Disposal of Coal Combustion Residuals for Electric Utilities is “CCR unit design and construction

information required by §§2557.73(c)(1) and 257.74(c)(1), previous periodic structural stability

assessments required under §§257.73(d) and 257.74(d), the results of inspections by a qualified person,

and results of previous annual inspections”[18]. The following subsection describes the review of

operating record files.

2.6.1 DesignandConstructionInformationURS staff reviewed the as‐built drawings prepared by Ebasco Services, Inc. [14]. The drawings provide

plans and sections for the embankment.

2.6.2 PreviousPeriodicStructuralAnalysesIn general, the existing stability analyses for the embankments meet the minimum factor of safety

requirements reported by the GEI [3] reports in 2011. With the exception of the pseudo‐static analyses,

the minimum factors of safety established by various design reports are consistent with current

standard practice for the loading conditions evaluated.

A detailed check of stability calculations was not part of the scope of work for this inspection. The

review of these analyses is based solely on associated assumptions, inputs, and results as summarized in

the available documents.

2.6.3 ResultsofInspectionbyaQualifiedPersonDave Johnston 4A Pond is subject to periodic inspections by the Dave Johnston Power Plant staff. URS

reviewed the inspection reports; however, this is the beginning of the first cycle of inspections under

CCR regulations and the record is limited to a few weeks of inspections. These inspections are

documented and retained by PacifiCorp. A sample of PacifiCorp’s Inspection form can be found in

Appendix C. In the opinion of this report author, the interim inspections by the plant staff are adequate

and appropriate for this CCR unit.


2.6.4 ResultsofPreviousAnnualInspectionsThis is the initial and only annual inspection conducted under CCR rules [18] for the Dave Johnston 4A

Pond. PacifiCorp has completed other independent inspections by third parties. None of the

observations from this or previous inspections indicated imminent dam safety concerns.

This report and other pertinent reports and data are accessible at the following website:

http://www.berkshirehathawayenergyco.com/ccr/ppw.html

Section 5 of this report is a list of references reviewed for this report for the Dave Johnston 4A Pond.

3 FieldInspectionof4APondA field inspection was conducted on August 31, 2015 by URS staff, Rick J. Cox, P.E. and Matthew Zion.

Mr. Cox previously was the principal author of the previous inspection report. Personnel from the Dave

Johnston Power Plant provided site orientation, escort, and transportation during the inspection. Dave

Johnston Plant staff participated in a close‐out meeting with the URS team to review observations and

answer additional questions.

A photograph log documenting features and their condition at the time of the inspection is presented in

Appendix A.

The completed Annual Inspection Report form is presented in Appendix B. This checklist should be

considered an integral part of the report and remain attached whenever the report is forwarded or

otherwise reproduced.

3.1 4APondGeometryThe 4‐Series Ponds embankments, constructed in approximately 1971, appear to be maintained at

approximately the same configuration and heights. The west side of the 4B pond is a cut (“incised”)

slope. The north embankment, east embankment, and south embankment of the pond are of varying

height and constructed of a 2H:1V compacted fly ash core and 4H:1V (upstream) and 3H:1V

(downstream) sandy soil shell embankments [14]. The north, east, and south embankment have lengths

of approximately 1000 feet, 1150 feet, and 800 feet, respectively [14].

The Plant staff reports that a single geosynthetic membrane liner was placed in 4A Ponds during

cleanout periods between 1992 and 1995. Based on several observed instances of liner damage

adjacent to the embankments’ crests, URS does not recommend any credit to the membrane for

seepage prevention or embankment stability, however, PacifiCorp reports that groundwater monitoring

indicates that the lining has benefited by limiting seepage. Figure 3‐1 is a cross section of the

embankment for 4‐Series ponds.


Figure 3‐1. 4‐Series Pond Embankment Cross Section [14]

3.2 GeneralThe field inspection was performed by the URS team by walking along the 4A Pond’s north, south and

east embankments and walking the interior dike between 4A and 4B ponds. Features and conditions

were documented on the Annual Inspection Report form (Appendix B) and were photographed and

marked with GPS coordinates. The approximate locations of the photos are detailed in the inspection

photograph log overview map located at the beginning of Appendix A, Photograph Log. In addition to

documenting current features, the photograph log of existing conditions is intended on aiding future

inspections.

3.3 InstrumentationThe 4A Pond has no instrumentation in its embankments. Photograph 8, Appendix A shows a

groundwater quality monitoring well that is installed on the interior dike.

3.4 ImpoundedWaterDepthandVolumeOn the day of the field inspection, the freeboard was estimated by the inspection team to be 1.5 feet,

making the water surface at 4,961. The pond was nearly full of CCR material on the day of the

inspection. It is estimated by the inspectors that the depth of water was less than 2 feet and total

volume of water less than 1 acre‐foot.

3.5 StorageCapacityThe pond’s capacity is reported at 144.6 acres feet [1].

3.6 ObservedorPotentialStructuralWeaknessesThere were no observations that indicated imminent weaknesses in the embankment (no tension cracks

or movement) or outlet works (no increased seepage or subsidence above the pipe). An area of

moisture was observed (Photo 11, Appendix A); however, it did not indicate a structural concern and the

2015 recommendation is to monitor for changes.

3.7 ObservedChangesThis is the initial and only annual inspection conducted under the CCR rules [18] for the Dave Johnston

4A Pond. However, PacifiCorp historically commissioned other third party inspections that were not


related to the CCR rules, the latest being completed by URS in 2014 [1]. This report of observed changes

is based on the 2014 report.

There were no observable changes in the structure of the 4A Pond’s embankments. Photo 15

documents an irregularity along the south embankment and Photo 11 documents a moist area along the

same south embankment. These locations are marked on the Appendix A overview map and should be

monitored in any further inspection for change.

At the time of inspection, 4A Pond was being used for the impoundment of FGD waste (Photo 9).

4 LimitationsandConsultantQualifications

4.1 LimitationsThis report presents observations, and conclusions drawn from a review of pertinent documents

referenced in Section 5, and a field inspection of the Dave Johnston 4A Pond. The purpose of the review

and inspection has been to assess the safety or adequacy of the facilities against catastrophic failure of

the major constructed elements during normal operations or unusual or extreme events based on visual

inspection and available information. A secondary purpose is to identify any potential deficiencies

related to the CCR rules [18].

The conclusions and professional opinions presented herein were developed by the independent

consultant and are in accordance with generally accepted engineering principles and practices at the

time and location the services were provided. URS makes no other warranty, either expressed or

implied.

4.2 ProfessionalEngineerQualificationsThe professional engineer for this inspection is Rick J. Cox. He is licensed in the State of Wyoming

(13825) as a civil engineer. He has over 32 years experience in civil/structural engineering and has

performed inspections and safety evaluations on dams, canals and numerous other water containing

structures.


5 References[1] URS, “2014 Coal Combustion Residuals Impoundment Inspection and Assessment – Dave

Johnston Power Plant,” February 2015.

[2] Cornforth Consultants, Inc., “Dave Johnston Power Plant, No. 4B Ash Pond, No. 1A Ash/Clear

Pond and No. 1B Ash/Clear Pond Impoundment Strucutures, Geotechnical Site Reconnaisance,

Caspar, Wyoming” May 15, 2009.

[3] GEI Consultants, Inc., “Specific Site Assessment for Coal Combustion Waste Impoundment at

PacifiCorp Energy, Dave Johnston Power Plant,” Glenrock, Wyoming, June 2011.

[4] United States Geological Survey [USGS], “2008 Interactive Deaggregations,” 2014. [Online].

Available: http://geohazards.usgs.gov/deaggint/2008/. [Accessed: 05‐Nov‐2014].

[5] Tetra Tech, “Slope Stability Analysis and Hydrologic Analysis of Pond 1A/1B Clear Pond South

Embankment and the 4 Clear Pond South Embankment, Dave Johnston Power Plant, 1591 Tank

Farm Road, Glenrock, Wyoming,” Tetra Tech Project No. 114‐510464, November 30, 2011.

[6] PacifiCorp Energy [Online] Available:

http://www.pacificorp.com/content/dam/pacificorp/doc/Energy_Sources/EnergyGeneration_Fac

tSheets/RMP_GFS_Dave_Johnston.pdf

[7] Wyoming Safety of Dams Safety Law. (1992). W.S. 41‐3‐307 through 41‐3‐318. Enacted 1977,

amended 1992.

[8] Wyoming State Engineer's Office Regulations and Instructions; Part I, Surface Water, Chapter 5.

Adopted in 1913, last revised in 1974.

[9] Federal Emergency Management Agency’s (FEMA), Federal Guidelines for Dam Safety: Hazard

Potential Classification System for Dams, April 2004.

[10] PacifiCorp Energy, “Scope of Work, Coal Combustion Residuals Impoundement Inspection and

Assessment”, prepared by Thermal Resources, Rev. 1, September 10, 2014.

[11] PacifiCorp Energy, “Dave Johnston Plant Water Balance, WYDPES 0003115 Renewal 5/28/2014,”

May, 2014.

[12] PacifiCorp Energy, “Unit 1, 2, 3 Piping and Instrumentation Diagram (P&ID), Bottom Ash System,

Bottom Ash Ponds, Dave Johnston,” Drawing G‐210039‐3 (“redrawn” 03‐18‐08, “as‐built verified”

03‐06‐1.

[13] Ebasco Services Incorporated “Access Road Embankment & Canal, Plan & Sections,” Drawing G‐

145159, 100‐MW Unit A, 1956. Updated to “As‐Built” for Unit B, 1964. Included in Appendix A to

this report.

[14] Ebasco Services Incorporated, Various “Ash Disposal System” Drawings G‐195908, G‐195909, and

G‐195910, Unit 4 Extension, 1971.


[15] Chas. T. Main, Inc., “Waste Water Facilities Modifications, Structural, Ash Ponds Outfall”, Drawing

F‐3859 (renumbered to PP 681809‐8145‐407), 1974. Updated to “As‐Built”, 1977.

[16] Lancaster Technical Resources, Inc., “Dave Johnston Power Plant, Initial Report &

Recommendation, Bottom Ash Pond System – Dike and Culvert Condition Inspection,” June,

2014.

[17] Lancaster Technical Resources, Inc., “Dave Johnston Power Plant, Final Report, Bottom Ash Pond

System – Dike and Culvert Condition Inspection,” September, 2014.

[18] Environmental Protection Agency (EPA), 40 CFS § 257 Disposal of Coal Combustion Residuals

from Electric Utilities, April 17, 2015.

2015 Dave Johnston 4A Pond Inspection

AppendixA

PhotographLog

Inspection Photographs PacifiCorp Energy

4A Pond – Dave Johnston Power Plant August 31, 2015

Page No. A-1



Page No. A-2

Photograph No. 1 4A Pond, View from northeast side of pond towards the southwest.

Photograph No. 2 Outside face of the northeast embankment. View to the south.



Page No. A-3

Photograph No. 3 Outside face of the northeast embankment. View to the north.

Photograph No. 4 Groundwater monitoring well outside pond near the southeast corner. View to north.



Page No. A-4

Photograph No. 5 Crest of east embankment of 4A Pond.

Photograph No. 6 Valves for slurry pipelines. 4B Pond in the background by equipment.



Page No. A-5

Photograph No. 7 Discharge channel into 4A Pond.

Photograph No. 8 Survey monument and groundwater monitoring well on dike between 4A Pond and 4B Pond.



Page No. A-6

Photograph No. 9 FGD slurry discharge pipe to 4A Pond.

Photograph No. 10 Control gate for discharge from 4A Pond to 4 Clear Pond.



Page No. A-7

Photograph No. 11 Moist area on downstream face of embankment between 4A Pond and 4 Clear Pond. Located above water surface in Clear pond.

Photograph No. 12 Downstream face of embankment between 4A Pond and 4 Clear Pond.



Page No. A-8

Photograph No. 13 Exposed membrane liner at southwest corner of 4A Pond.

Photograph No. 14 Exposed membrane liner on upstream face of embankment between 4A Pond and 4 Clear Pond.



Page No. A-9

Photograph No. 15 Approximate location of submerged outlet from 4A Pond to 4 Clear Pond. Note irregular face of embankment.

Photograph No. 16 Control gate for discharge from 4A Pond to 4 Clear Pond.



Page No. A-10

Photograph No. 17 Inoperable control gate (buried) from 4A Pond to 4 Clear Pond. Note gate in open position.

Photograph No. 18 View of intermediate dike between 4A Pond (right) and 4B Pond (left). View to northeast.


AppendixB

AnnualInspectionReportForm

Annual CCR Impoundment Inspection Report

Issue Date: 8-24-2015 Form XXXXX Revision A

Page 1 of 4

Feature Name: Dave Johnston 4A Pond

Feature ID: Date: August 31, 2015

Station/Owner PacifiCorp

County, Converse

State Wyoming

Inspected By Rick J. Cox, P.E. and Matt Zion

Date 8-31-15

Phone No. 801-904-4096

Type of Dam Concrete Gravity Embankment Concrete Arch Stone Masonry

Concrete Buttress Other Weather Wet Dry Snow Cover

Other Type of Inspection Initial Periodic Follow up Other Hazard Description Low. No buildings immediately downstream.

Condition Assessment Satisfactory Unsatisfactory Poor Not rated Fair

Hazard Class Low (A) Intermediate (B) High (C)

Remarks This was the initial inspection under CCR regulations.

Actions None Maintenance Monitoring Minor Repair Engineering

Recommendations Inspection letter Inspection by DSE Deficiency letter Dam safety order EOR notice Enforcement Engineering study Periodic reinspection Inspection by EOR

Pool Level (ft) URS team estimated freeboard at 1.5 feet.

Total Precipitation since last inspection Recent minor precipitation.

UPS

TREA

M S

LOPE

/FAC

E

Problems COVER:

1. None 2. Vegetation >2” dia. 3. Veg. height >6” 4. High bushes 5. Animal Burrows 6. Livestock damage

7. Wave Erosion 8. Slides 9. Depressions 10. Bulges 11. Cracks 12. Spalling

13. Scarps 14. Sloughing 15. Holes 16. Undermining 17. Displaced joints 18. Deteriorated joints

19. Exposed reinforcement 20. Veg. or sediment in rip rap 21. Displaced rip rap 22. Sparse rip rap 23. Other Erosion 24. Other

Vegetation Rip rap Concrete Asphalt Other

HDPE membrane liner. Earth cover.

Comments /Action Items


TOP

OF

DAM

/CRE

ST

PROBLEMS COVER: 1. None 2. Vegetation >2” dia. 3. Veg. height >6” 4. High bushes 5. Animal Burrows 6. Livestock damage

7. Ruts 8. Depressions 9. Unlevel 10. Misalignment 11. Signs of overtopping

12. Cracks 13. Deteriorated joints 14. Displaced joints 15. Exposed reinforcement 16. Settlement

17. Scarps 18. Spalling 19. Sinkholes 20. Puddles 21. Other


gravel Comments /Action Items




Page 2 of 4

Feature Name:

Dave Johnston 4A Pond Feature ID: Date:

August 31, 2015

TOE CONTA

CT

PROBLEMS COVER:

1. None 2. Vegetation >2” dia. 3. Veg. height >6” 4. High bushes 5. Poor grass cover 6. Animal Burrows 7. Livestock damage

8. Wetness 9. Seepage 10. Boils 11. Puddles 12. Erosion 13. Slope instability 14. Scarps

15. Sloughs/bulges 16. Depressions 17. Undercutting 18. Rutting/rills 19. Cracks 20. Scour 21. Spalling

22. Displaced joints 23. Deteriorated joints 24. Exposed reinforcement 25. Riprap needs attention 26. Veg. or sediment in rip rap 27. Other


28. Does standing water or seepage contain sediment? Yes No NA

Describe seepage with regard to quantity and clarity (turbidity). Note changes:



ABUTM

ENT CONTA

CTS

PROBLEMS COVER:

1. None 2. Vegetation >2” dia. 3. Veg. height >6” 4. High bushes 5. Poor grass cover 6. Animal Burrows 7. Livestock damage







DOWNSTREA

M SLO

PE/FA

CE

PROBLEMS COVER: 1. None 2. Vegetation >2” dia.\ 3. Veg. height >6” 4. High bushes 5. Poor grass cover 6. Animal Burrows 7. Livestock damage




Vegetation Rip rap On

4 Clear Pond side.

Concrete Asphalt Other

28. Does standing water or seepage contain sediment? Yes No NA

29. Is there natural hillside seepage in embankment area? Yes No NA

Describe seepage with regard to quantity and clarity (turbidity). Note changes: No seepage but wet spot on downstream slope . Refer to

Photo 11, Photo Log.

Comments /Action Items: Monitor wet spot for changes.




Page 3 of 4

Feature Name:


August 31, 2015

PRINCIPAL SPILLW

AY

OBSERVATIONS No Spillway

Is spillway control system operating properly? Yes No

PROBLEMS CHANNEL LINING 1. None 2. Trashguard 3. Debris 4. Obstructed 5. Plugged/Clogged 6. Gates Damaged 7. Gates leaking 8. Gates Rusted

9. Misalignment 10. Joints leaking 11. Joint deterioration 12. Joint displacement 13. Conduit collapsed 14. Exposed reinforcement 15. Erosion

16. Undermining 17. Voids 18. Cracks 19. Holes 20. Spalling 21. Slides 22. Outlet

undercutting

23. Sloughing 24. Scarps 25. Deteriorated lining 26. Boils 27. Outlet erosion 28. Displaced rip rap 29. Sparse rip rap 30. Other




EMER

GEN

CY SPILLW

AY

OBSERVATIONS

No emergency spillway Same as primary spillway

PROBLEMS CHANNEL LINING

1. None 2. Debris in channel 3. Gates 4. Misalignment

5. Joint deterioration 6. Joint displacement 7. Exposed reinforcement 8. Erosion

9. Undermining 10. Voids 11. Cracks 12. Holes 13. Outlet erosion

14. Displaced rip rap 15. Sparse rip rap 16. Outlet undercutting 17. Inadequate capacity 18. Other


Comments /Action Items No controlled spillway. Box culvert at southeast corner that would perform as an emergency spillway.


DRAINS/OUTLET

STR

UCTU

RE

Observations

1. Is discharge system operating properly? See Comments below Yes No N/A

2. Valves and operators in good condition? Not manually operated during inspection. Yes No N/A

3. Walkway in good condition? Yes No N/A

4. Is there any turbidity observed at the outlet? Submerged by Clear 4 pond. Not observable. Yes No N/A

5. Seepage at pipe outlet. Outlet is submerged. Yes No N/A

6. No Bottom Drain Yes No N/A

7. Bottom Drain Operable Yes No N/A

8. Subsurface Drain Dry Yes No N/A

9. Subsurface drain muddy flow Yes No N/A

10. Subsurface drain obstructed Yes No N/A

11. Animal guard Yes No N/A

12. other Yes No N/A

Comments /Action Items The principal discharge system was recently rehabilitated. There is another inoperable gate. Refer to Photo 17, Photo Log.




Page 4 of 4

Feature Name:


August 31, 2015

OTH

ER

OBSERVATIONS

1. leachate/stormwater (RCP; CMP) drain pipes that pass through or under an ash basin intact? Yes No N/A

2. Drainage/ diversion ditches/riprap‐lined channels in good condition? Yes No N/A

3. Other steel structures/steel reinforcement in concrete structures in good condition? Yes No N/A

4. Other concrete structures in good condition? Yes No N/A

5. Overflow pipes and flap gates on filter dam/ drain pipe filter zone in good condition? Yes No N/A

6. Howell Bunger Valves in good condition? Yes No N/A

7. Weirs in good condition? Yes No N/A

8. Fences and Gates in good condition? Yes No N/A

9. Security devices in good condition Yes No N/A

10. Signs in good condition Yes No N/A

11. Instrumentation in good condition Newly install Yes No N/A

12. Reference monuments/Survey Monuments in good condition, Newly installed. Yes No N/A

13. other Yes No N/A



Routine instrumentation monitoring (piezometers, inclinometers, etc.) are recorded separately. Have these measurements been collected, and properly recorded. Yes No N/A Newly installed groundwater monitoring wells and survey monuments. Photo 8, Photo Log. Are additional sheets included, if applicable to address regulatory, or third party inspection issues? Yes No N/A

Are there any other abnormal conditions at the Impoundment that could pose a risk to public health, safety or welfare; the environment or natural resources Yes No

Inspector Signature

Date 8/31/2015

RESER

VIOR/POOL

OBSERVATION

Has there been a sudden drop in the content level of the Impoundment Yes No

PROBLEMS

1. None 2. Inadequate freeboard

3. Skimmer 4. Depressions

5. Whirlpools 6. Sinkholes 7. Unwanted growth in pond water




AppendixC

ExamplePacifiCorpInspectionForm

1

Issue Date: Rev. 1

Dave Johnston Impoundment Inspection Report

Impoundment Name: Dave Johnston 4A Pond Date: Time:

Inspected By:

Type of Impoundment: Active Inactive Weather Conditions: Wet Dry Snow Cover Other

Discharge: Yes No Water Elevation: Instrumentation Monitoring Completed: Yes No NA

Inspection Frequency: Routine Weather/Seismic Event High Flow Other _____________________________

Up

stre

am F

ace

1. Evidence of erosion from surface runoff or other effects on the face of the embankment. Yes No 2. Riprap or erosion protection damaged, needs repair. Yes No 3. Water elevation exceeds freeboard requirements for the impoundment and may overtop. Yes No 4. Animal burrows or other animal damage present on the face of the embankment. Yes No 5. Vegetation taller than 6 inches is present on the embankment. Yes No 6. Signs of settlement, low spots, depressions, sinkholes, cracks, or other instability visible on the embankment.

Yes No

Observations:

Actions: None Maintenance Monitoring Engineering Notification/Work Order#:

Dow

nst

ream

Fac

e

7. Indicators of seepage or evidence of seepage are present on the face, abutments, or toe of the embankment.

Yes No

8. Evidence of erosion from surface runoff or other effects on the face of the embankment. Yes No 9. Animal burrows or other animal damage present on the face of the embankment. Yes No 10. Vegetation taller than 6 inches is present on the embankment. Yes No 11. Signs of settlement, slides, low spots, depressions, sinkholes, cracks, or other instability visible on the embankment.

Yes No

Observations:


2

Issue Date: Rev. 1

Cre

st

12. Signs of surface damage from vehicles (wheel ruts), drainage, or other activity are present. Yes No

13. Evidence of erosion from surface runoff on the crest. Yes No 14. Animal burrows or other animal damage present on the crest. Yes No 15. Vegetation taller than 6 inches is present on the crest. Yes No 16. Signs of settlement, low spots, depressions, sinkholes, cracks, or other instability visible on the crest.

Yes No

Observations:


Ru

le

17. Any appearance of actual or potential structural weakness and other conditions which are disrupting or have the potential to disrupt the operation or safety of the CCR unit?

Yes No NA

18. Abnormal discoloration, flow, or discharge of debris or sediment from outlets or structures that pass underneath the impoundment, or through the dike?

Yes No NA

19. Outlets, conduits, and hydraulic gates malfunctioning, with seepage or other evidence of damage. Yes No NA

20. Instrumentation, pump-back systems, drains, and other monitoring intact. Yes No NA

21. Other non-structural or non-emergency safety issues. Yes No NA

Observations:


Inspector Signature: ________________________________________________ Date: _________________________

Documents

Dave Johnston Power Plant · adjacent to the embankments’ crests, URS does not recommend any credit to the membrane for seepage prevention or embankment stability, however, PacifiCorp