2018 Annual Dam and Dike Inspection Report...Inspection photos are included in Attachement A....

2018 Annual Dam and Dike Inspection Report

Ash Pond Complex

Conesville Plant

AEP Generation Resources, Inc.

Coshocton County, Ohio

August 28, 2018

Prepared for: AEP Generation Resources – Conesville Plant

Conesville, Ohio

Prepared by: American Electric Power Service Corporation

1 Riverside Plaza

Columbus, OH 43215

GERS-18-037

---Page Intentionally Left Blank---

Pages 3 of 10


Pages 4 of 10

Table of Contents 1.0 Introduction ............................................................................................................................................. 6

2.0 Description of Impoundment .................................................................................................................. 6

2.1 Definitions of Visual Observations and deficiencies .......................................................................... 6

2.2 Fly Ash Pond Complex ....................................................................................................................... 7

3.0 Review of Available Information (257.83(b)(1)(i)) ................................................................................ 7

4.0 Inspection (257.83(b) (1)(ii)) .................................................................................................................. 8

4.1 Metals Cleaning Waste Tank Dike (Non-CCR).................................................................................. 8

4.2 Ash Pond Complex ............................................................................................................................. 8

4.2.1 Changes in geometry since last inspection (257.83(b)(2)(i)) ....................................................... 8

4.2.2 Instrumentation (257.83(b)(2)(ii)) ............................................................................................... 8

4.2.3 Impoundment Characteristics (257.83(b)(2)(iii, iv, v)) ............................................................... 8

4.2.4 Visual inspection (257.83(b)(2)(i)) .............................................................................................. 9

4.2.5 Changes that effect stability or operation (257.83(b)(2)(vii)) ...................................................... 9

5.0 Summary of Findings .............................................................................................................................. 9

5.1 General Observations .......................................................................................................................... 9

5.2 Maintenance Items ............................................................................................................................ 10

5.3 Items to Monitor ............................................................................................................................... 10

5.4 Deficiencies (257.83(b)(2)(vi)) ......................................................................................................... 10

Attachments Attachment A – Pictures

Attachment B – Site Maps

Attachment C – Instrumentation Data

Pages 5 of 10


Pages 6 of 10

1.0 Introduction This report was prepared by AEP- Geotechnical Engineering Services (GES) section, in part, to fulfill

requirements of 40 CFR 257.83 and the Ohio Department of Natural Resource (ODNR), Division of Water

Dam Inspection Section and to provide AEP Generation Resources and the Conesville Power Station with

an evaluation of the facility.

Ms. Beth Mullen, Plant Environmental Coordinator for the Conesville Plant provided onsite coordination

for inspection activities. The inspection was performed on August 28, 2018 by Brian Palmer of AEP

Geotechnical Engineering. Weather conditions were overcast with temperatures in low 70°s F to upper 80°s

F and 0.4-in of precipitation occurred in the preceding seven days prior to the inspection.

2.0 Description of Impoundment

2.1 Definitions of Visual Observations and deficiencies

This summary of the visual observations uses terms to describe the general appearance or condition of an

observed item, activity or structure. The meaning of these terms is as follows:

Good: A condition or activity that is generally better or slightly better than what is

minimally expected or anticipated from a design or maintenance point of view.

Fair or A condition or activity that generally meets what is minimally Satisfactory:

expected or anticipated from a design or maintenance point of view.

Poor: A condition or activity that is generally below what is minimally expected or

anticipated from a design or maintenance point of view.

Minor: A reference to an observed item (e.g., erosion, seepage, vegetation, etc.) where the

current maintenance condition is below what is normal or desired, but which is not

currently causing concern from a structure safety or stability point of view.

Significant: A reference to an observed item (e.g. erosion, seepage, vegetation, etc.) where the

current maintenance program has neglected to improve the condition. Usually,

conditions that have been previously identified in the previous inspections, but

have not been corrected.

Excessive: A reference to an observed item (e.g., erosion, seepage, vegetation, etc.) where the

current maintenance condition is above or worse than what is normal or desired,

and which may have affected the ability of the observer to properly evaluate the

structure or particular area being observed or which may be a concern from a

structure safety or stability point of view.

This document also uses the definition of a “deficiency” as referenced in the CCR rule section

§257.83(b)(5) Inspection Requirements for CCR Surface Impoundments. This definition has been

assembled using the CCR rule Preamble as well as guidance from MSHA, “Qualifications for

Impoundment Inspection” CI-31, 2004. These guidance documents further elaborate on the definition of

deficiency. Items not defined by deficiency are considered maintenance or items to be monitored.

A “deficiency” is some evidence that a dam has developed a problem that could impact the structural

integrity of the dam. There are four general categories of deficiencies. These four categories are described

below:

Pages 7 of 10

1. Uncontrolled Seepage

a. Uncontrolled seepage is seepage that is not behaving as the design engineer has

intended. An example of uncontrolled seepage is seepage that comes through or

around the embankment and is not picked up and safely carried off by a drain. Seepage

that is collected by a drain can still be uncontrolled if it is not safely collected and

transported, such as seepage that is not clear. Seepage that is unable to be measured

and/or observe it is considered uncontrolled seepage. [Wet or soft areas are not

considered as uncontrolled seepage, but can lead to this type of deficiency. These

areas should monitored my frequently.]

2. Displacement of the Embankment

a. Displacement of the embankment is large scale movement of part of the dam. Common

signs of displacement are cracks, scraps, bulges, depressions, sinkholes and slides.

3. Blockage of Control Features

a. Blockage of Control Features is the restriction of flow at spillways, decant or pipe

spillways, or drains.

4. Erosion

a. Erosion is the gradual movement of surface material by water, wind or ice. Erosion is

considered a deficiency when it is more than a minor routine maintenance item.

2.2 Fly Ash Pond Complex

The fly ash pond complex is comprised of diked embankments on the north, southeast, and south sides.

County Road 273 runs along the toe of the north dike, a Plant haul road run along the top of the north dike,

and a coal haul road runs along the crest or exterior of the Southeast dike. The northwest side of the Ash

Pond Complex is located adjacent to a closed landfill area. There are three main ponds within the Ash

Pond Complex as listed below.

List of Main Ponds within the Ash Pond Complex

Fly Ash Pond

Bottom Ash Pond

Clearwater Pond

The Fly Ash Pond has internal splitter dikes that divide it into areas referred to as Ponds 1, 2, 3, and 4. The

Bottom Ash Pond has an internal splitter dike creating the Bottom Ash Pond and Pond 5. Water enters the

Ash Pond complex through either the Bottom Ash Pond or Pond 1. From the Bottom Ash Pond or Pond 1

water flows through the Ash Pond Complex in order from Pond 2, Pond 3, Pond 4, and Pond 5 before

reaching the Clearwater Pond where it is discharged to the Holding Pond.

The inspection included the dike for the Metals Waste Cleaning tank as it is adjacent to the South dike of the

Ash Pond complex

3.0 Review of Available Information (257.83(b)(1)(i)) A review of available information regarding the status and condition of the Ash Pond Complex, which

include files available in the operating record, such as design and construction information, previous

periodic structural stability assessments, previous 7 day inspection reports, and previous annual inspections

has been conducted. Based on the review of the data there were no signs of actual or potential structural

weakness or adverse conditions.

Pages 8 of 10

4.0 Inspection (257.83(b) (1)(ii))

4.1 Metals Cleaning Waste Tank Dike (Non-CCR)

A visual inspection of the dike for Metals Cleaning Waste Tank was conducted to identify any signs

of distress or malfunction of the secondary containment system. Overall the facility is in good

condition. The secondary containment is functioning as intended with no signs of potential structural

weakness or conditions which would be disruptive to the safe operation of the containment system.

Inspection photos are included in Attachement A. Additional pictures taken during the inspection can

be made available upon request.

4.2 Ash Pond Complex

4.2.1 Changes in geometry since last inspection (257.83(b)(2)(i))

No modifications have been made to the exterior geometry of the Ash Pond Complex since the 2017

annual inspection.

4.2.2 Instrumentation (257.83(b)(2)(ii))

The location and type of instrumentation is shown on Figure 2 in Attachment B. The maximum

recorded readings of each instrument since the previous annual inspection is shown in Table 1

below.

Table 1 – INSTRUMENTATION DATA

Ash Pond Complex

Instrument Type

Maximum Reading

since last annual

inspection

Date of reading

B7 Piezometer 729.53 2/27/2018

P-11 Piezometer 733.92 2/27/2018

P-12 Piezometer 747.82 2/27/2018

P-13 Piezometer 749.9 4/24/2018

B-0901 Piezometer 732.78 2/27/2018

B-0902 Piezometer 762.46 2/27/2018

B-0902R Piezometer 739.07 09/10/2018

B-0903 Piezometer 749.02 2/27/2018

B-0904 Piezometer 743.29 2/27/2018

NOTE: A review of the piezometer construction and locations identified issues with the construction of

B-0902 and B-0903 resulting in B-0902R replacing B-0902 in May 2018 and B-0903 was abandoned as

it is replicated by P-12.

Piezometers readings were generally consistent since the last inspection. Piezometer well

hydrographs are included in Attachment C. B-0902R is discretely screened in the embankment and

better characterizes water elevations in the dike.

4.2.3 Impoundment Characteristics (257.83(b)(2)(iii, iv, v))

Table 2 is a summary of the minimum, maximum, and present depth and elevation of the impounded

water & CCR based on the bathymetric survey conducted Nov. 9, 2017 and water elevation at time

of inspection; the storage capacity of the impounding structure; and the approximate volume of the

impounded CCR at the time of the bathymetric survey.

Pages 9 of 10

Table 2 – IMPOUNDMENT CHARACTERISTIC DATA

Impoundment Characteristics Ash Pond Complex

Approximate Minimum depth of impounded water

Pages 10 of 10

vegetation along the embankments was well established. The crest did not contain any ruts or

other signs of instability.

3) The Clearwater Pond hydraulic structure is in good condition. There were no signs of deterioration of the concrete or steel structures. The maximum pool elevation (762 ft. msl) is

also clearly marked on the structure. Stop logs were available for use. Flow within the

discharge pipe appeared unobstructed.

5.2 Maintenance Items

The following maintenance items were identified during the visual inspection, see inspection map for

locations:

Metals Cleaning Waste Tank Dike

1) No specific items identified related to the Metals Cleaning Waste Tank Dike.

Ash Pond Complex

2) Continue work to clear the vegetation on the exterior embankment along the Coal Haul road to the toe of the embankment and groin ditch plus a minimum of 25 ft. along the opposite slope

and ascertain the origin of the seepage observed within this area.

3) Work on the removal of vegetation at the toe of the north dike along County Road 273.

4) Continue monitoring and taking corrective actions related to groundhogs and other burrowing animals.

5.3 Items to Monitor

The following items were identified during the visual inspection as items to be monitored, see

inspection map for locations:

Metals Cleaning Waste Tank Dike

1) No specific items identified related to the Metals Cleaning Waste Tank Dike.

Ash Pond Complex

2) The abandoned culverts under original coal haul road need to be inspected quarterly for seepage.

3) Continue to monitor for areas of erosion and repair as necessary.

5.4 Deficiencies (257.83(b)(2)(vi))

There were no signs of structural weakness or disruptive conditions that were observed at the time of

the inspection that would require additional investigation or remedial action. There were no

deficiencies noted during this inspection or any of the periodic 7-day or 30-day inspections. A

deficiency is defined as either 1) uncontrolled seepage, 2) displacement of the embankment, 3)

blockage of control features, or 4) erosion, more than minor maintenance. If any of these conditions

occur before the next annual inspection contact AEP Geotechnical Engineering immediately

ATTACHMENT A

Photos

Date: August 28, 2018

Inspector: B. Palmer

Photo #: 1

N40 11.366 W81 51.965

Photo #: 2

N40 11.351 W81 51.979

Description: Groin

Notes: Crest of SE dike haul road

Location: Looking SW

Notes: Exterior slope/crest of SE dike

Location: NE corner looking SW

Page: 01

AEP GES Dam Inspection

Plant Name: Conesville

Unit: Ash Pond

Description: Crest



Photo #: 3

N40 11.362 W81 51.964

Photo #: 4

N40 11.332 W81 51.987

Description: Other

Notes: Left groin exterior slope of SE dike

Location:

Notes: Groundhog hole on slope, identified as part of plant inspection and flagged for repair. Groundhog removed

Location:

Page: 02



Unit: Ash Pond

Description: Groin



Photo #: 5

N40 11.310 W81 52.014

Photo #: 6

N40 11.309 W81 52.016

Description: Toe

Notes: Toe of SE dike cleared at least 25ft from exterior toe


Notes: Toe of SE dike needing additional work to clear exterior toe area

Location: Looking NE

Page: 03



Unit: Ash Pond

Description: Toe



Photo #: 7

N40 11.200 W81 52.172

Photo #: 8

N40 11.200 W81 52.172

Description: Slope

Notes: General condition of exterior slope of SE dike

Location: Looking NE

Notes: General condition of exterior slope of SE dike


Page: 04



Unit: Ash Pond

Description: Slope



Photo #: 9

N40 11.143 W81 52.232

Photo #: 10

N40 11.146 W81 52.227

Description: Other

Notes: Old CMP culverts along exterior toe of SE dike

Location:

Notes: Old concrete culvert near old CMP pipes

Location:

Page: 05



Unit: Ash Pond

Description: Other



Photo #: 11

N40 11.089 W81 52.302

Photo #: 12

N40 11.100 W81 52.299

Description: Culvert

Notes: General condition of of slope above access road to outfall pipe discharge

Location:

Notes: Outlet of discharge structure

Location:

Page: 06



Unit: Ash Pond

Description: Slope



Photo #: 13

N40 11.542 W81 51.863

Photo #: 14

N40 11.541 W81 51.862

Description: Groin

Notes: General condition of north dike exterior slope

Location: East end looking west

Notes: Right exterior groin and abutment north dike

Location:

Page: 07



Unit: Ash Pond

Description: Slope



Photo #: 15

N40 11.560 W81 52.020

Photo #: 16

N40 11.543 W81 52.293

Description: Crest

Notes: General condition of exterior toe of north dike along county road

Location: Looking west

Notes: General condition of crest outside of fence

Location: Looking east

Page: 08



Unit: Ash Pond

Description: Toe



Photo #: 17

N40 11.108 W81 52.350

Photo #: 18

N40 11.106 W81 52.317

Description: Slope

Notes: Crest SE dike above coal haul road

Location:

Notes: SE dike exterior slope above coal haul road

Location: SW corner looking NW

Page: 09



Unit: Ash Pond

Description: Crest



Photo #: 19

N40 11.103 W81 52.392

Photo #: 20

N40 11.142 W81 52.443

Description: Slope

Notes: General condition of SW dike exterior toe and slope


Notes: General condition of SW dike exterior slope


Page: 10



Unit: Ash Pond

Description: Toe



Photo #: 21

N40 11.140 W81 52.448

Photo #: 22

N40 11.128 W81 52.472

Description: —

Notes: Metal Cleaning Waste Tank (MCWT) east dike general condition

Location:

Notes: South MCWT dike general condition

Location:

Page: 11



Unit: Ash Pond

Description: Other



Photo #: 23

N40 11.158 W81 52.474

Photo #: 24

N40 11.159 W81 52.470

Description: —

Notes: West MCWT dike general condition

Location:

Notes: North side of MCWT about SW dike of Ash Pond

Location:

Page: 12



Unit: Ash Pond

Description: Other



Photo #: 25

N40 11.218 W81 52.547

Photo #: 26

N40 11.222 W81 52.544

Description: Crest

Notes: General condition of SW dike exterior toe and slope


Notes: General condition of SW dike crest

Location: Looking se

Page: 13



Unit: Ash Pond

Description: Other



Photo #: 27

N40 11.224 W81 52.538

Photo #: 28

N40 11.235 W81 52.549

Description: Other

Notes: Interior slope of SW dike in bottom ash pond

Location: Looking SE

Notes: Bottom ash discharge pipes crossing top of berm at SW corner. Wood vegetation is starting to develop.

Location:

Page: 14



Unit: Ash Pond

Description: Slope



Photo #: 29

N40 11.229 W81 52.513

Photo #: 30

N40 11.226 W81 52.517

Description: General

Notes: General condition of bottom ash outlet pipes

Location: Bottom ash pond

Notes: Bottom ash canal

Location: Bottom ash pond

Page: 15



Unit: Ash Pond

Description: Other



Photo #: 31

N40 11.236 W81 52.542

Photo #: 32

N40 11.315 W81 52.446

Description: Crest

Notes: Toe and exterior slope on west side dike at bottom ash pond

Location: Looking north

Notes: Crest and interior slope of west side dike at bottom ash pond

Location: Looking southth

Page: 16



Unit: Ash Pond

Description: Slope



Photo #: 33

N40 11.532 W81 52.213

Photo #: 34

N40 11.513 W81 51.919

Description: Slope

Notes: North dike haul road crest

Location: West end looking east

Notes: General condition of North dike interior slope


Page: 17



Unit: Ash Pond

Description: Crest



Photo #: 35

N40 11.413 W81 51.909

Photo #: 36

N40 11.415 W81 51.909

Description: Slope

Notes: Overview of Ash Pond Complex

Location: Looking SW from NE corner

Notes: SE dike interior slope

Location:

Page: 18



Unit: Ash Pond

Description: General



Photo #: 37

N40 11.177 W81 52.245

Photo #: 38

N40 11.169 W81 52.253

Description: Other

Notes: SE dike above coal haul road

Location: Looking SW from clearwater pond

Notes: Outlet riser in clearwater pond

Location:

Page: 19



Unit: Ash Pond

Description: Slope



Photo #: 39

N40 11.155 W81 52.331

Photo #: 40

N40 11.148 W81 52.321

Description: Other

Notes: General condition of walkway to outlet riser

Location: Clearwater Pond

Notes: Discharge opening at outlet riser

Location: Clearwater Pond

Page: 20



Unit: Ash Pond

Description: Other

ATTACHMENT B

Inspection / Instrumentation Location Maps

740 740

750

750

750

750

750

750

760

760

760

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760

760

760

760

760

760

760

760

760

760

760

760

760

760

760

760

760

760

760

760

770

770

770

770

770770

770

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770

770

770

770

770

780

780

780

780

780

790

790

790

790

800

800

800

810

810

DOCK

CONVEYOR

748.65

808.80

104

105

760.2W.E.

758.1

758.1W.E.

W.E.

749.6W.E.

755.3W.E.

797.4760.3

801.1

770.9

803.2

764.9

806.6

806.7804.9

809.2

770.5

749.3

763.6

762.7

766.7

762.2

775.1

774.7

761.5762.6

773.2

759.3773.1773.5

759.3

760.9758.7

761.2758.9

761.3758.2

758.5

760.5757.3758.4

811.8

760.9758.3

760.3

760.3757.4

760.4815.6

760.5760.7

759.9759.1815.6

760.4759.1

813.4816.8

759.3

760.3

760.7815.9

760.5811.1

760.8814.9

761.3815.1

760.5761.1811.7

812.8

760.4760.8

766.9

760.9

760.7

762.9

763.5

765.5

763.8

763.1

763.1

775.4

775.9

759.6

771.4

751.6

750.9

747.3

760.6

758.7

750.9

751.3

752.7

752.7

764.4

747.5

797.3

796.5

761.6756.9

750.7

766.6

759.7

759.6

759.2

767.4

758.3

757.1

757.8

767.1

768.3

768.7

767.2

762.3

767.4

767.1

766.4

751.5

749.4

759.3

758.5

763.1

763.6

761.6

768.7

766.7

757.3

767.6

769.3

767.1

761.1

761.2

762.7

763.7

765.4

762.1

765.3

759.1

767.2

758.8

763.3

758.9

757.9

759.7

767.5

758.9

766.8

768.9

759.8803.6

805.3

755.2

761.5

766.4

770.5

777.3

784.4

789.1

793.4

797.4

807.2

809.5

740.7

774.5772.9773.1

767.4766.4

773.9773.3773.5773.7

773.9773.9

738.7737.8

737.8736.8736.5737.1

737.7737.5

764.5

762.3

762.3

762.4

767.0

766.2

774.4

751.4

768.9757.8

804.7

749.4762.7

747.5

747.1

752.2

774.8

774.1

755.6

750.7

768.2

759.6

757.8

765.1

765.6

764.2800.2

763.2759.4

769.4

755.7

763.8

762.3

766.7763.9

816.1

757.7

762.3 762.9

764.5

764.2

764.4

764.7

780.6

778.4

769.9

761.9

766.4

768.4

775.7

768.8

768.8

766.5

764.8

759.1

762.4

765.7

763.2

767.9

751.7

752.2

750.8

750.8

751.7

757.7

757.9

768.2

756.9

757.6

756.9

766.7

759.9

762.4

762.1

759.9

762.7

762.8

766.4

768.3

757.8

764.3

765.7

770.9

763.1

759.9

771.1

772.1806.1

774.3

761.2

IMAGERY DATE: MARCH 2006

UNIT: U.S. SURVEY FEET

ZONE: OHIO NORTHERN

DATUM: NORTH AMERICAN DATUM OF 1983 (NAD83)

HORIZONTAL CONTROL:

W E

N

21

44

00

02144000

2144500

2145000

21

44

50

0

2143000

21

42

50

0

21

43

00

0

21

43

50

02143500

21

45

00

0

2147000

21

46

50

0

21

47

00

0

21

47

50

02147500

21

45

50

02145500

2146000

2146500

21

46

00

0

190500

190000

190500

191000191000

189000189000

189500

190000

189500

191500

21

41

50

02141500

2142000

2142500

21

42

00

0

192000

191500

192000

192500192500

P13

P11

B-7

PZ-0901

PZ-0902

PZ-0903

PZ-0904

P12

DATE:

SCALE:1"=400'

DRN BY:AG

1 RIVERSIDE PLAZA

COLUMBUS, OH 43215

AEP SERVICE CORP.

DWG NO:FIGURE 2CONESVILLE POWER STATION

INSTRUMENTATION PLAN

ASH POND COMPLEX

PL

OT

DA

TE:

PL

OT

TI

ME:

BY:s279452

2:2

6:4

4

PM

9/21/2018

PZ-0902R

ATTACHMENT C

Instrumentation Data

720

725

730

735

740

745

750

755

760

765

ELE

VA

TIO

N, F

EE

T

TIME, QUARTERLY

FIGURE 3 - INSTRUMENTATION DATA.

FAP CWP B-7 P-11 P-12 P-13 B-0901 B-0902 PZ-0902R B-0903 B-0904 BAP

2018 Annual Dam and Dike Inspection Report...Inspection photos are included in Attachement A....

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Transcript of 2018 Annual Dam and Dike Inspection Report...Inspection photos are included in Attachement A....