rev 1 unit 1 ash pond closure plan - lowman...

REV 1

UNIT 1 ASH POND CLOSURE PLAN

Lowman Power Plant

B&V PROJECT NUMBER: 198677

PREPARED FOR

PowerSouth Energy Cooperative

DECEMBER 2018

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Authorization 82 Report Revisions and Record of Issue

December 2018 RR-1 Black & Veatch

Report Revisions and Record of Issue

Rev. Date Issue Status Revisions and Record of Issue EDT CHK APP

0 11/29/2018 Draft Issued for Client Review GDS CMK LJA

1 12/04/2018 Final Final LJA LJA

© Copyright, Black & Veatch Corporation, 2018. All rights reserved.

The Black & Veatch name and logo are registered trademarks of

Black & Veatch Holding Company


Authorization 82 Table of Contents

December 2018 TC-1 Black & Veatch

Table of Contents

1.0 Unit 1 Ash Pond Closure Plan

..................................................................................................................................................................1-1

1.1 PROJECT DESCRIPTION ......................................................................................................................1-1

1.2 DESCRIPTION OF CLEAN CLOSURE...............................................................................................1-2

1.2.1 Procedures for Water Removal.....................................................................................1-2

1.2.2 Removal of CCR Material .................................................................................................1-2

1.2.3 Area Reuse .............................................................................................................................1-2

1.3 PROJECT SCHEDULE.............................................................................................................................1-3

1.3.1 General.....................................................................................................................................1-3

1.4 ASH POND CLOSURE DESIGN DRAWINGS ..................................................................................1-3

List of Figures

Figure 1-1 Lowman Plant Site Aerial View

........................................................................................................................................................................1-1


Authorization 82 CCR Pond Close Sequence of Work

December 2018 1-1 Black & Veatch

1.0 Unit 1 Ash Pond Closure Plan

1.1 PROJECT DESCRIPTION

PowerSouth Energy Cooperative (PowerSouth) requested Black and Veatch Engineers

prepare a Closure and Post-Closure Care Plan for the CCR Ponds at the Charles R. Lowman Power

Plant as required by ADEM Admin. Code r. 335-13-15-.07(3)(b) and (5)(d). The CCR Ponds function

collectively as an interconnected, multiunit system for the storage of CCR and the management and

treatment of wastewater. This document describes the closure and post-closure care plan for the

Unit 1 Ash Pond located at the Lowman Power Plant. Figure 1-1 shows an aerial view of the Lowman

Plant site and the location of the Unit 1 Ash Pond, Unit 2/3 Ash Pond, and the FGD Impoundment.

Figure 1-1 Lowman Plant Site Aerial View

The Unit 1 Ash Pond is currently used as a settling pond for CCR wastes containing bottom

ash, fly ash, and other plant wastes and is approximately 15.91 acres in area. Bottom ash from Unit

1 is transported to the impoundment via wet sluicing. In addition to the bottom ash sluicing

operation, the facility periodically disposes of fly ash, scrubber waste, and other low volume plant




wastes within the impoundment. The maximum CCR inventory of Unit 1 is approximately 300,000

cubic yards.

Following shutdown of coal operations and the last receipt of CCR waste, PowerSouth will initiate

clean closure of the Unit 1 Ash Pond as outlined in this report. It is expected this Closure Plan will be

amended at that time to address current site conditions and to develop issued for construction plans

and specifications. Closure of the pond will generally consist of the follow activities:

1. Removal of free water from within the impoundment.

2. De-watering of interstitial water contained within the remaining CCR waste.

3. Removal of CCR material and transporting to the exiting Unit 2/3 Ash Pond and FGD Pond as

fill for closure of those impoundments.

1.2 DESCRIPTION OF CLEAN CLOSURE

1.2.1 Procedures for Water Removal

As required by 335-13-15-.07(3)(b)1.(ii), closure will be accomplished through removal of

the CCR material in the Unit 1 Ash Pond. The Unit 1 Ash Pond material is also useful to grade the top

of the Unit 2/3 Ash Pond for final cap and closure operations. Dewatering the Unit 1 Ash Pond area

will occur in two stages. The first stage will consist of removal of “free” liquids within the

impoundment using suction lifts pumps, or similar method. Following removal of “free” liquids, a

dewatering Contractor will be employed to remove all interstitial water in the material removal area,

allowing the material to be moved to the Unit 2/3 Ash Pond. It is anticipated that gravity dewatering

methods will be implemented.

1.2.2 Removal of CCR Material

CCR material from the Unit 1 Ash Pond will be removed and placed within the Unit 2/3 Ash

Pond or FGD Pond. The sequencing of CCR removal will require coordination with closure

operations at the Unit 2/3 Ash Pond and FGD Pond.

The original ground surface within the Unit 1 Ash Pond area was between elevations 10 to

13 feet. The crest of the embankment was constructed to elevation 35 to 38 feet. The ash pond was

constructed without a bottom liner. There are approximately 300,000 cubic yards of CCR material

within the Unit 1 Ash Pond to be removed. Visual observation of the native grade will be required

for the clean closure.

1.2.3 Area Reuse

After removal of the CCR material, the Unit 1 Ash Pond area can be used for future plant

purposes.




1.3 PROJECT SCHEDULE

1.3.1 General

As required by 335-13-15-.07(3)(b)1.(vi) a project schedule is provided below outlining the

necessary steps to close the Unit 1 Ash Pond and the estimated time frames to complete each step.

The project schedule for the Unit 1 Ash Pond closure will require coordination with the closure

plans for Unit 2/3 Ash Pond and the FGD Pond.

Table 3.1 – Project Schedule

TASK TIMEFRAME

Removal of Free Water and Dewatering of CCR Material 18 months

Excavation and Hauling 7 months

Backfill 3.5 months

Total Project Time 28.5 months

1.4 ASH POND CLOSURE DESIGN DRAWINGS

The attached Black & Veatch drawing 198677-OSTF-S3000 shows the location of the Unit 1

Ash Pond in relation to the Unit 2/3 Ash Pond and FGD Impoundment to which the Unit 1 ASH CCR

material will be transferred.

rev 1 unit 1 ash pond closure plan - lowman...

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